**1. Introduction**

This article forms a very partial account of the experience of offering professional formation in 'anti-oppressive practice' in youth and community work in the period from the mid-1980's to around the turn of the twenty-first century. The term 'anti-oppressive practice' distinguished from the more liberal term 'anti-discriminatory practice' emerged in the 1980's as a challenge, in the fields of social work, youth work and community development, to forms of practice which ignored power relations, especially the impact of the class system and of patterns of racism and sexism. In what follows, the emergence of the term in the field of education of youth and community workers in higher education in the UK is traced in a very partial history. The term arose and became a focus of practice in the 1980's, which has been called the period of 'the politicised years' [1]. It was later codified in particular in social work text books, especially in the popular 'Anti-Discriminatory Practice' [2], which offered an analysis of power and oppression through personal, cultural and structural lenses. It was during this same period that the term 'Informal Education' became well established as a generic term for youth work in the UK, replacing to some extent the earlier terminology of social education, largely thanks to the work of Mark Smith and Tony Jeffs [3].

I first attended a youth club and a youth arts project in the early 1970- s; I became a part-time worker on Adventure Playgrounds, and then a full-time youth and community worker. In 1986 I started working at Manchester Polytechnic as a lecturer in youth and community work. I continued in that work until retiring from Manchester Metropolitan

5

**Citation:** Batsleer, J. Re-Assembling Anti-Oppressive Practice (1): The Personal, the Political, the Professional. *Educ. Sci.* **2021**, *11*, 645. https:// doi.org/10.3390/educsci11100645

Academic Editors: Pam Alldred and Frances Howard

Received: 15 June 2021 Accepted: 7 October 2021 Published: 14 October 2021

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2021 by the author. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

University in 2020, having been part of the UK Youth Work world and educated informal educators throughout that long period. However, I believe this holds much more than merely personal interest, as the trajectory of our work was shaped first by the sense of the 'long 1968 and its influence [4], and then by the post-1989 period of 'capitalist realism' [5], with the hegemonic conviction that 'there is no alternative' to neoliberal economics and forms of education which credentialise and turn students into consumers, only to hold them entirely responsible, in a sickening manner, for their own failures within the education system. This post-1989 turn became linked to an audit culture from which we still need to devise ever more creative methods of escape. The ethical and political imperatives associated with 'anti-oppressive practice' remain in contradiction with the imperatives of 'capitalist realism' in both universities and many contemporary forms of youth work practice. The aspects of educating informal educators presented here follow an arc leading from optimism to a deadening kind of inertia: but they also provoke an awareness of the possibility of a different kind of praxis.

My certainly unreliable memories of the earliest years of my work as a youth and community Work educator at Manchester Polytechnic/Manchester Metropolitan University were re-awakened by the participation in a collective biography project entitled 'Re-assembling Anti-Oppressive Practice' [6]. I have worked over many years with ideas from Frigga Haug's [7] 'memory work' method, which, alongside other 'consciousness raising' methods in both research and movement spaces, was important in the 1980's and continues to influence contemporary work on collective biography [8]. The process we undertook, like Haug's, prompted writing out of everyday memories and experiences of oppression which were then discussed in a group setting. This is the source of the writing presented here. We aimed to explore the theoretical significance of apparently mundane and everyday moments in the marginal and conflicted space of educating youth and community workers in UK higher education. In what follows I have chosen to offer accounts of particular concepts and practices in order to show a set of entanglements between the field of youth and community work, significant social movements of the second half of the twentieth century, and both State or market forms. I am drawing on lived experience and personal archives as well as on courses I have taught throughout the period from the 1970's to the early 2000's. Working with 'the archive' has become a significant method for enquiry into feminist education practices [9]. The idea of 'the archive' is that it does not provide neutral data, but forms part of a genealogy which can be generative of feminist practice in the here and now. It is for this reason that I draw on both established texts and personal memory in what follows, seeking to validate forms of knowing usually excluded from the written and academic record. This builds on work undertaken as part of the Feminist Webs archive collective [10]. In such an approach both marginality and marginalia become the strong thread of a continuously emergent practice.

There has long been a sense that youth and community work courses have offered a 'radical' space at the margins both of higher education and of the field of youth and community work, itself a practice marginal to the mainstream institutions of education and social care. This has been expressed both in terms of the courses being in tension with the requirements of higher education (for example through emphasising experience as much as academic qualifications in recruitment processes) and being criticised for remoteness from the field of practice as a result of an emphasis on the importance of a critical engagement with current policy directives, whatever their origin. At the heart of our discussions in the 'Re-assembling Anti-Oppressive Practice' collective has been the question of the extent to which this field of practice has been and may yet again become permeable to wider radical and democratic social movements and the pedagogies associated with them.

In this genealogy of 'anti-oppressive practice' (a term which emerged at a certain point and then almost disappeared, being replaced by terms such as 'inclusion' and 'equality and diversity') I have chosen to highlight both concepts and practices which show youth and community work in the UK to be a powerfully contested terrain. The term 'antioppressive practice' became a phrase which gathered those who experienced youth and

community work as a site of struggle, especially for the rights of young people in relation to the oppressive forces of, for example, policing or schooling, and against practices of youth and community work which were primarily concerned with the social control of young people. As chair of the UK QAA Subject Benchmark process which established the framework for the recognition of undergraduate courses in this field, such contestation seemed to me to be of the utmost significance, even to the extent of defining the field [11]. The turn from the engagement with social movements to the development of bureaucratic forms of accountability in which 'anti-oppressive practice' became nothing more than a 'tick box' exercise is part of the sorry tale here, but it is the earlier lively struggles to which this essay draws attention. In the end, in the Benchmark process, the conflict took the form of an argument surrounding naming: whether the word 'community' belonged in the naming of this Benchmark at all. The term 'youth and community work' marked a pragmatic compromise, and so this genealogy, which begins with the term 'community' is not innocent. The word 'community', with its dangerous echoes of 'communism', could at times become a code for commitment to a grassroots practice with an ethic which promoted equality and social justice.

This genealogical approach is intended to suggest ways in which emerging conceptualisations, the spaces afforded by higher education, and a specific field of practice have overlapped with one another. It also offers a glimpse of how, in a very small field of practice, relations between individuals and patterns of influence emerge which are as significant as bodies of theory, and are intertwined with them. In particular, the role of individuals in the Training Agencies Group (TAG), the Trade Union (CYWU) and the Youth Work Unit at the National Youth Bureau (NYB/subsequently National Youth Agency/NYA) are the focus of attention. These have been important UK national reference points for the practice of youth and community work. In terms of Educating Informal Educators, the work of TAG, now the Professional Association of Lecturers in Youth and Community Work (PALYCW) is central to the story told here.

The sources and the methods here therefore intertwine the personal, the public and the political. The writing of the six aspects which follow engages with each of these sources. Where possible I have referenced both published texts and personal blogs and other communications. The rest relies on my own memories of the times.

### **2. 'The Long 1968** ... **' and Changing Approaches to Authority**

The Milson–Fairbairn report, commissioned in 1969 [12] by a Labour government to explore links between youth work, schools and Further Education, on the one hand, and adult community groups, on the other, is much less discussed than the Albemarle Report (1960) [13], which is usually treated as the origin document for the formation of Youth Leadership as a profession. Yet this was the report that opened up a difficult, fruitful conversation between 'community development' (rooted in Christian traditions of 'overseas mission') and 'Youth Leadership' (also with strong roots in Christian philanthropy and yet based 'at home' and newly professionalised in the formation of the National College). It also opened the conversation between youth leadership (now termed youth and community work) and the development of democratic forums in formal education such as student unions. In 1969, in line with a salary scale which had long been applicable to 'Youth Leaders and Community Centre Wardens', community development joined counselling and group work as key elements in the curriculum for the training and development of such staff.

The term 'I968 has come to represent a moment which in fact occurred both before and after 1968 and into the early 1970- s, when many traditional hierarchies were being brought into question, not least in education and in the field of charitable endeavours. Paternalistic and patronising forms of practice were becoming increasingly difficult to sustain. Inherited patterns of authority were put strongly into question. 'The Laughter of Stafford Girls High' (as Carol Ann Duffy describes it in the wonderful poem of that name [14]) had been let loose in the world, and the 'youthquake' of that time was moving

faster than any of the newly established youth and community work training courses could hope to capture.

Student movements were central to 'les évènements' of 1968, and movements to reform school education formed an inevitable counterpart to the attempt to reform universities. The student protests centred on the opposition to war, to militarism and to bureaucratic power, but also on the universities themselves, including the ways in which university authorities had repressed civil rights protests and disciplined those involved. In relation to schools, the example of the Little Red School Book [15] (1969, 2014), which presented an open educational approach for young people towards drugs (including tobacco and alcohol) and towards sex (including the discussion of female masturbation), became a cause célèbre for the Christian establishment across Europe to rally against. Opening up such liberalising conversations in Youth Work remained controversial well into the 1970's, so youth work was positioned as behind the curve and as an 'agent of social control' in a moment of youthful rupture against 'establishments' internationally. But courses in higher education settings did begin to open up the possibility of an engagement between youth and community work and the counterculture.

The non-judgmental ethos of the counterculture was present in the emphasis on the 'social' that had developed in both the training of youth leaders and the formation of community development workers. 'Social education' (as it was termed) might turn out to be more than an education in moral development, civilising behaviour and minding your 'p's and q's.' Ideas about 'group work', especially non-directive group work, and peer-led learning came to the fore. Ideas about community development as a form of activism allied to civil rights brought a sense of the politics of the time into recently established courses, which were still forging a sense of 'professionalism' in order to distinguish this practice from 'old style' philanthropy. However, this professionalism was, in its turn, problematic in its assumptions concerning a neutral 'expertise.'

As Stuart Hall and Tony Jefferson [16] made clear in their groundbreaking study 'Resistance through Rituals', the power of youth counterculture was only part of the story. Youth 'sub-cultures'—which were the focus of so much public anxiety and policy attention —were as divided by social class as the rest of UK society. Hall and Jefferson's work enabled a clear grasp of the ways in which cultural expressions mediated class divisions, and had their own power. 'Tuning in and turning on' to such expressions could be seen as an essential means of connection between the youth leader and groups of young people. For many years, courses drew not only on studies of group dynamics but also on cultural studies and radical deviancy studies as essential elements of the curriculum. In subsequent work, Hall (et al.) [17] were to identify the contradictions of this moment as a 'crisis of hegemony' as it developed through the prism of 'race'. 'The appearance of a renewed panic about race in the very moment of this intense polarisation of the political scene and just when the shift from a managed to a more coercive variant of consensus is occurring, cannot be wholly fortuitous.' [17]. The forces which supported a shift towards authoritarian populism, against which the new social movements were pitched, were already present in the late 1960- s, and already strongly focused around issues of race, nation and sexuality.

### **3. The Group** ... ...

Some of the powerful struggles in practice as they were lived are present in the biography of Susan Atkins, one of only 17 women out of 145 students enrolled on the emergency programme for the training of youth leaders which ran at the National College in Leicester from 1961–1970. Susan, who went on to play a significant role as national chair in the development of the Community and Youth Workers Union (CYWU) and was instrumental in the establishment of the Women's Caucus of that union, gives an account of the influence of Peter Duke. Duke became the principal of the first National College for the Training of Youth Leaders, in 1964. With Peter, then the Warden of Oxford House, in Bethnal Green (whose nineteenth century origins lie with High Anglicanism and the Oxford Movement), Susan, as a young woman, was involved in theatricals, including

the production of scenes from Shakespeare's 'A Midsummer Night's Dream'. Susan's account [18] of those years captures the continuity of the struggle in youth work education and training traditions between 'experience' and 'theory': Susan describes first 'learning on the job' as a young woman leading theatricals, then struggling to retain her place on the massively male-dominated emergency programme: a struggle in which, thankfully, she was successful. It was such struggles 'without a name' which prefigured the emergence of the Women's Liberation Movement. One expression of that movement was the formation of the Women's Caucus in the trade union.

With the emergence of professional education and training came the further development of theory to inform practice, and the term 'social education' became central to this. Initially the focus was on association and the dynamics of association: Bernard Davies, in his pamphlet 'From Social Education to Social and Life Skills Training' cites the following set of questions (drawn up for the Derbyshire Youth Service in 1963) as typical of the professional orientation to social education:

*Is association in my club* ... ... ... *harmless* ... ... *?*

*Does association in my club introduce young people to new interests* ... *.. to responsibility?*

*Have any members shown increasing acceptance of themselves* ... ... *.?*

*Are there members who have shown increasing acceptance of others* ... ... *?*

*Are there any who show increasing readiness to consort with members of the opposite sex in a relationship other than one of the forms of courtship? Do some members show increased ability to listen with attention to unfamiliar or accepted ideas* ... ... *? [19]*

There is a resonance here with earlier definitions of 'social education' within youth work promoting the ability 'to entertain oneself; entertain a stranger; and entertain a new idea' [20]. Acceptance and non-judgementalism set the tone.

Group development was also seen as a fundamental element of community development:

*The process of community development (or creation) is envisaged in two stages: the first, development within the groups themselves as the members become more knowledgeable people, more friendly and co-operative among themselves, and more able to conduct their business without outside help and guidance; and the second, development in the community at large as the characteristics developed within the groups influence the conduct of the members in their homes and in their neighbourhood. Thus, through the groups they sponsor the agencies aim to produced socialized and community-minded people, as well as knowledgeable people. They hope that leaders developed in their groups will later become leaders in community affairs [21].*

Reg and Madge Batten (based at the Institute of Education, in London, after 'fieldwork' experience in Africa) influenced the curriculum of courses through their advocacy of a combination of directive and non-directive approaches. The non-directive approach can be understood as a move away from the moral certainties and colonial mastery inherent in earlier approaches, although the traces of colonial power remain in the assumption that 'socialised and community-minded people' need to be 'developed' rather than encountered, supported and resourced. 'The learning group' also became central to emerging approaches to adult education in the UK, as University Extra Mural Departments moved away from lecture courses towards an emphasis on recognising the experience of adults as a foundation for learning. This learning group became a central feature of courses both for part-time youth workers (the 'Bessey courses') [22] and for the original courses for full-time staff to achieve professional qualification. Often combined with a shift from 'lecturing' to 'group facilitation', the covert power of the tutor in the 'tutor group' on such courses became the focus for feminist and anti-racist critique in the 1980's. The scope (both for influence and for exploitation) afforded to the 'tutor as guru' in such apparently 'non-directive' groups became the material for much reflective critique from the 1980's onwards, including in the informal circulation among women of accounts of what was then newly termed 'sexual harassment.'

The field of youth and community work became—in its own understanding—a space for group work and peer learning—and this was associated with self-development and autonomy for young people, in well-boundaried spaces, and with democratic rather than inherited forms of authority. The small group was a space for development and for the integration of learning. However, inherited patterns of authority had far from disappeared, and the disappointment and sometimes furious discontent caused by the ability of such apparently alternative spaces to remain deeply conventional in terms of power dynamics was persistently and acutely felt.

### **4. The Personal Is Political: Experiential Learning That Starts from Discontent**

By the mid 1970's there was a significant flow (always at the margins) between the spaces being created in the new social movements—especially between student activists and the Women's Liberation Movement and Black Youth activism—and the pre-existing spaces of youth and community work. This was partly because these were spaces in which support for those living in the most disadvantaged neighbourhoods could be developed without recourse either to legal powers such as those possessed by social workers or the accompanying pathologising case work approaches and without involvement from the police. It was also because the social movements saw a significant politics in the social in the same moment (but often not in the same way) as youth work theorists saw a democratic educative potential in the same civil society spaces.

The significant new emphases emerging from the social movements was on the experience of power *within* the social and on the role of the small group in investigating and challenging hegemonic power in everyday life, whilst building the collective agentic power of participants. In the Women's Liberation Movement, the role of small groups was now seen as vital and as the central organising tool of the movement [23]. Practices of 'speaking bitterness' and of naming personal troubles as shared and potentially political issues were widely practised both formally, in consciousness-raising groups, and informally, in the many reading groups and campaigning groups which flourished, linked by magazines such as *Spare Rib* or *Red Rag* and by the publishing of pamphlets about emerging practices, theories and issues. All this was supported through newsletters and radical bookshops.  One such newsletter was the '*Working with Girls Newsletter*' [24]. The male dominance of the youth work sector was widely noted and discussed: this applied to the courses which trained youth workers. From the mid 1970's to the mid-1980's the organising by feminists within youth work led to the formation, discussed earlier, of a women's caucus within the trade union, to regular conferences for women associated with the *Working with Girls* newsletter, and to the brief existence of the National Organisation for Work with Girls and Women, which argued for the development of a national training college specifically for women youth workers [25]. These networks developed organising strategies which disrupted any easy sense of the 'social' as a genderneutral space. Feminist women appointed to posts in training agencies (the precursors of today's degree programmes) began to attend the Training Agencies Group (TAG) and to raise issues of gender justice in that organisation, in ways which challenged the sense of an 'old boys club' in which the 'secretariat' (made up of the leaders of the small number of existing courses) shaped agendas and ran the show, even when the meetings happened in the ubiquitous 'democratic circle' of youth work training courses of that era.

The insistence on opportunities for women to meet autonomously within TAG meetings was an early example of a 'disruptive moment'; this was disruptive even though the regular annual conference was held on the weekend of the FA Cup Final and had always included a session dedicated to the watching of the match. In much the same way as newly established, feminist-inspired Girls Nights were often offered on Wednesday evenings, as Wednesdays were a 'football night', the possibility of women meeting at TAG during the match was offered, thus requiring some women to choose between their love of football and their politics. Such 'disruptive moments' are a hallmark of practice developed by

social movements and interventions like these, drawn from the practice of the Women's Liberation Movement, and began to be theorised in ways which potentially transformed the meaning associated with 'experiential learning'.

One's social experience, and active enquiry into experience by experimenting with new patterns became the material for the exploration of social relations of oppression and subordination. Experiences in small groups could give glimpses of the potential for different ways of being in the world, become sources of solidarity and possible liberation, as well as offer discomforting insights into unnoticed and unthinking privilege. As Black Studies emerged alongside Women's Studies to challenge the curriculum and focus of training courses in youth and community work, the exploration and theorisation of imposed silences and subjugated knowledges made 'non-directive group work' deeply controversial in its power to non-directively sustain hegemonic power relationships. Instead, group work and experiential learning became the grounds for enquiry and for opening up the possibilities of change.

### **5. Paulo Freire at West Hill College: An Emphasis on Critical Praxis as the Source of Transformation**

At first, there was considerable resistance in TAG to the inclusion of community work alongside youth work in courses. Subsequently, there was resistance to the inclusion of parttime and work-based courses alongside those historically based in colleges, polytechnics and universities. As the wave of new courses which emerged from the late 1980's onwards was for the most part dedicated to the recruitment of black workers, this suggested an exclusionary attitude towards those 'taking the experience route', which reinforced existing white hierarchies in relation to 'professional qualification.'

Important to all the social movements as they travelled in the spaces of community development, adult education and eventually youth work was the critical approach to education in the work of Paulo Freire [26]. His discussion of 'praxis' became central to understandings of the kind of practices we were engaged in.

*'To speak a true word is to transform the world* ... *when a word is deprived of its dimension of action reflection automatically suffers as well and the word is changed into idle chatter* ... *into an alienated and alienating blah* ... *. there is no transformation without action.*

*On the other hand, if action is emphasized exclusively to the detriment of reflection* ... *action for action's sake* ... *negates true praxis and makes dialogue impossible.' [26]*

It is somewhat amazingly the case that Freire was part of a Conference on Community Development at West Hill College, Birmingham, in 1970. The influence of his work, and that of his critic and powerful advocate bell hooks, has been profound especially in those courses which associate themselves closely with community development. Critical pedagogy and engaged pedagogy offered the theoretical framework for practice.

Freirean approaches were by no means universally welcomed. In particular Freire's emphasis on the directive rather than the non-directive role of the educator was a source of much criticism, as was his revolutionary commitment to the transformation of social relations of oppression, which he termed 'liberation', 'transformation' and 'conversion.' Despite the fact that Freire argued that the educator needed to be directive of the process, not of the student, the sense was that the dialogue proposed by Freire could easily become mimicked as one led by Socrates in which 'yes Socrates/yes Paulo' was the only possible answer permitted to the learner. So, Freirean pedagogy—or 'critical pedagogy', as it came to be known—despite its commitment to dialogic relationships between partners in learning, was too often expressed and even experienced as an alternative form of mastery [27,28]. There was, too, a consistent fear within the world of youth work training and education, of too much emphasis on 'pedagogy' (and therefore education), with the consequent neglect of practices of association, collaboration and community-building, based on enthusiasm and enjoyment as much as on learning [29]. 'If I can't dance, I don't want to be part of your revolution.'

The problem of too much emphasis on 'pedagogy' also related to the issues identified in 1980 by the authors of the London-Edinburgh Weekend Return Group's pamphlet '*In and Against the State*.' 'Your resources we need. Your relations we don't.' [30]. There were significant unmet basic needs among both the young people and the older generations with whom youth and community workers engaged. At the same time, receiving resources from the State involved them in patterns of relationship they had rejected: pathologising communities; assessing individuals and families in terms of educational and parenting skills deficits; administering border controls on the access to opportunities.

Youth workers and other community educators too easily became 'street level bureaucrats' [31] even whilst also carrying traces (within the State) of the social struggles of the past. In a similar way, lecturers on courses also too easily became assessment bureaucrats, whilst carrying the same traces of social struggles in universities. Praxis and the critical linking of reflection and action was the only way to mitigate this in-built tendency. Praxis might mean drawing on university resources to support unfunded women's groups beyond the university; enabling students to undertake placements in newly emerging and not yet professionalised settings such as voluntary sector-based Black Youth Centres; supporting young people 'coming out' as gay in school contexts, and reflecting together across difference on the power of such actions. New thinking on 'diffractive practice' is strong in its critique of the way 'reflective journals' have become routinised and scripted as performances of the self. Reflective conversations in the context of new social movements, which emphasised the importance of conversations and coalitions across difference, and so were committed to the production of new praxis away from racism and sexism, may have been diffractive without knowing it.

### **6. A Significant Text and a More Significant Practice: Defensive Spaces**

Between 1980 and 1982, the Youth Work Unit at the National Youth Bureau, led by Mary Marken, developed The Enfranchisement Development Project 'to consider the needs and therefore the position of young people in relation to organized society.' It drew heavily on work undertaken in a similar period by Steve Butters and Susan Newell [32], 'Realities of Training', in which Butters delineated what he termed 'the social education repertoire' (cultural adjustment, community development and institutional reform) and also posed the possibility of a critical break with social education towards a 'radical paradigm' (selfemancipation) in which workers aligned themselves with the youth against parental controls and fought the system, recognising that this would involve them in conflict, not consensus. The results of this project were published as '*Interpretation and Change: The Emerging Crisis of Purpose in Social Education*', by Marion Leigh and Andy Smart.

In a moment of insight never far from the realities of practice, Leigh and Smart wrote: 'A number of workers would argue (on the basis of bitter experience of having apparently middle of the road non-controversial programmes of sex education and civics style political education subjected to intense political scrutiny) that the real critical break in practice can be found running through all the components of the Social Education Repertoire ... ' [33]. Perhaps the same critical break ran through the courses in universities. The challenges of the late 1970's and early 1980's, which were faced first on the streets, erupted in the form of a recognition of racism and exclusionary practice, subsequently enabling the development of Black Access courses as part of the struggle to establish a black presence and black perspectives within UK higher education. This struggle was felt in the Manchester course, for example, from the mid 1980's onwards, when student complaints about racism and the absence of black lecturers led to an HMI inspection which brought the course to the attention of the university authorities, who threatened the course with closure.

Leigh and Smart [33] end with a reflection on the future of concepts of professionalism in youth work. They sensed that the social democratic model associated with 'the social education repertoire' was under pressure, but found little support among practitioners for other, more radical and critical approaches to youth work, which seemed 'unprofessional.' This was especially the case for the 'oppositional approach', as it involved 'taking sides.'

Yet throughout the book there is the insistent trace of the events that took place on British streets in 1981, after the long period of pressure on young black people, and young men especially, in the form of the 'sus' laws. In what came to be termed uprisings, young men (and some women) started to take their freedom into their own hands. Irvine Williams, from Moss Side Manchester (now youth work manager at the Hideaway a Moss Side Youth Centre), has spoken in a recent podcast of his experience as a young man [34]. He had been a member of Hideaway from age 14, in attendance at a centre in which there were many fights around the sound systems, boiling over among the youth as a result of the pressure from the hostile environment they were growing up in. In July 1981, discontents about unemployment and police brutality following Special Patrol Group's use of the 'sus law' erupted on the streets. At the age of 16, Irvine was picked up during the riots, arrested and taken to the Platt Fields police station in Manchester, just on the edge of the district. At this time, the youth workers all attended the police station to support the young people and were part of the crowd who came to the police station to free them. As a result of the support he received from youth workers in this way, at the age of 18, Irvine became a volunteer at the youth club, and began to associate with other black people running youth clubs in different parts of the country. He remembers powerfully his experience of support and guidance at that time from local youth workers, including Ann Rose, who became his tutor on the Youth and Community Work course at Manchester Polytechnic. This has informed his practice as a youth worker ever since. In this context, the paradigm which Leigh and Smart [32] describe as the 'oppositional paradigm' was far from unthinkable: it formed a basic practice of self- defence and mutual aid among young people who were especially vulnerable to what Leigh and Smart termed 'the encroaching non-welfare state.' Forty years before the coining of the phrase 'school to prison pipeline', youth workers and young people in Black communities such as Moss Side were already forging sustainable practices with which those offering professional formation to youth work professionals would struggle to engage. These were not State-led practices, they were not colonial practices and neither were they neutral, as those between young people and the authorities.

It was out of, and in response to, such experiences that the term 'Anti-Oppressive Practice' came to be coined. 'Race' as a prism through which to understand both the nature of the crisis in hegemony and the resolution of that crisis in new forms of authoritarian populism and in patterns of bureaucratisation and control continues to haunt the education of informal educators. Oppression, under its many names, has often seemed to be focussed in policing and the criminalisation of urban communities. The resistance and mutual aid practices of those communities remain a vital source for understanding what it might mean to be 'anti-oppressive', both including and beyond the experience of racism, as well as continuing to create often fragile civil society spaces which provide a defence for those young people consistently under attack from authoritarian populist responses to the continual crisis which occurs through the prism of 'race' in UK culture.

### **7. New Managerialism and the National Occupational Standards: Paper Trails vs. Ethics**

According to Jean Spence [24], it was already the case in the late 1980's that the struggles of radical practitioners came to be re-interpreted by a managerial ethos in youth services which made commitments to anti-sexist and anti-racist work a managerial edict rather than a primary response to the needs and discontents of young people.

A good deal of energy went into institutional struggles to create a Statement of Purpose of a core curriculum for youth work in 1990, at the Second Ministerial Conference convened by the DES [35], which identified the task of the service as 'seeking to redress all forms of inequality and to ensure equality of opportunity for all young people'. It saw youth work as needing to operate 'through the challenging of oppressions such as racism and sexism and all those which spring from differences of culture race language sexual identity gender disability age religion and class'; And 'through the celebration of the diversity and strengths which arise from such differences.'

Thus, the social struggles of the past left a trace within the documents of the State, or at least in documents aligned to the State. These documents were then to form the basis of 'National Occupational Standards' (NOS) [36] developed for youth work and the pre-degree level during the New Labour period and first published in 2002.

Between 1997 and 2010 the work of the Education and Training Standards Committee of the National Youth Agency and, by association, the work of TAG, became deeply embroiled with the necessity of creating national frameworks within which the work of youth workers, alongside that of other community educators, could be supported. Just as this applied to the education and training offered to voluntary and part-time youth and community workers at a pre-degree level, it also applied to degree programmes in universities. However, the professional field was largely concerned with specifying the skills and competences required of part-time youth workers, whilst the universities remained concerned with the requirement for all professional qualifications to be at the degree level by 2010 (and therefore in line with those awarded to social workers and teachers). It was as if every element of what had previously been a marginal but valued practice was now subject to minute assessment and the requirement of paper trails accrediting skills and competencies, which, like certificates and graduation ceremonies, became more elaborate in inverse proportion to their market or social value.

By 1999, the first Mapping of National Occupational Standards for Youth Work was completed. This period also saw the emergence of PAULO (named after Paulo Freire) as a National Training Organisation for Youth Work, Community Work and Adult Education [37]. PAULO was soon overtaken by a rationalisation process, and youth work' workforce development found itself positioned between Lifelong Learning UK (which it joined in 2005) and the powerful presence of the Children's Workforce Development Council. Just as the youth work workforce was now being 'integrated' into wider partnerships to pursue the 2003 Every Child Matters programme (2003) [38], so the skills and competencies required of Children's Workforce professionals became ever more generic and welfare/safeguarding-based.

It was during this period that I heard a committee report on the development of the National Occupational Standards [37]. When asked what had become of the commitment to anti-oppressive practice, the outsourced company responsible for the design of standards at that stage had taken the term to be a reference to good practice in the restraint of young people in residential settings.

Meanwhile, traces of earlier social movements were to be found in the higher education bureaucracy of the development of Subject Benchmarks. The development of the Subject Benchmark for Youth and Community Work began in 2006 [11]. Perhaps because of the distance from the re-organisation of the workforce, it was possible to retain for a while a sense of the presence of some distinctive commitments to enquiry, association and ethics in this statement. Professor Sara Banks of Durham University had worked with the National Youth Agency in 2000 to produce the Ethical Conduct in Youth Work: A Statement of Values and Principles [38], and it was now here that the strongest statements of values with significance for practice which challenges oppression were to be found.

It might seem that the claims of the social movements on the civil society space of youth work had been reduced to a subsection of a subsection in the National Occupational Standards: *'providing equality of opportunity [39]'*.

#### **8. Without Conclusions**

A second article in this Special Issue [6] engages with the question of how these memories and archive might be living in the present moment, and what new forms of theorising and acting are being offered to youth work committed to understanding and unsettling oppression.

There is a good deal of work on the 'archive' currently, as an aspect of critical humanities. The writing of both these articles can be understood as framed by such an exploration. Karen Barad's [40] thinking on time/space entanglements is very significant for many writers in this field. In this her work connects to that of earlier Marxist visionary thinkers—one of whom, Walter Benjamin, wrote vividly about the artist Paul Klee's 'Angel of History':

*This is how one pictures the angel of history. His face is turned toward the past.  The angel would like to stay, awaken the dead, and make whole what has been smashed. But a storm is blowing from Paradise; it has got caught in his wings with such violence that the angel can no longer close them. This storm irresistibly propels him into the future to which his back is turned, while the pile of debris before him grows skyward. The storm is what we call progress [41].* (Benjamin, 1940; 1959)

Such thinking suggests that time is not best understood as linear or progressive. The wreckage of oppression which continues to be piled up in what we can understand as 'one single catastrophe' faced by peoples across many generations. So, the catastrophes of police violence; or exclusion and violence based on gender and sexuality; or of segregated provision for disabled young people; or of poverty: these were not addressed 'once and for all' between 1970 and 1990, so that progress could be made. Rather, the storm continues to blow us back to the future, and the debris of earlier actions might become driftwood to hold on to as new actions to sustain life are taken. So 'memory work' is a method not primarily designed to provoke nostalgia or melancholy but to spur such new actions and a new praxis.

One way in which the new movements of the 21st century are being characterised is their focus on life and breathing as much as on voice and rights. A critical question that was present in the earlier movements mentioned here and which remains a necessary question is that of the relation between theory and experience, between ways of knowing and ways of being. 'Praxis' has been one term for this, a sense of the unity of action and thinking, as discussed in the work of Paulo Freire [26]. A further question, often provoked by feminist work on 'situated knowing', has been to consider how to avoid those forms of knowing and being that relegate other forms of knowing and being to redundancy and non-existence. In this essay I have sought to emphasise the contribution of unpublished practitioners who do not define themselves as scholars to the development of understandings of anti-oppressive practice in youth work. Therefore, the work with 'the archive' presented here is in itself an attempt to re-ignite those connections between different forms of knowing about informal education, as the new social movements of the current times alert us to the challenges of the current times.

Another current framing of this relation might be to emphasise what happens beneath language and concepts, what enables them, what sustains them. More and more we find ourselves drawn towards practices of care and salvage from the wreckage as the only practices strong enough to counter disaster capitalism and all its oppressive force. It is here, in these practices—in the resulting small-scale activity—that new ways of being—not of self-reflection or self-care, but of being in the world in difference, being in the world as relationality from the very start—can and do emerge, are already emerging. Youth work in community spaces is small enough and marginal enough to be part of that.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The author declares no conflict of interest.


*3.1. Wristbands*

We devised a set of two wristband prototypes as shown in Figure 1 to be worn by the people being monitored. Wristband B detected motion, whilst Wristband A had a more complex composition, as can be observed in Figure 2. The goal pursued by using both of these wristbands was to detect not only the emotion of the people being monitored, but also if they were properly doing the exercises being suggested. The decision to manufacture our own devices was due to the fact that the data from the commercial wristbands were filtered and preprocessed, so they did not have the precision required for our platform.

**Figure 1.** Wristband A and Wristband B (motion detector) prototypes.

To perform the emotion detection using bio-signals, it was necessary to have a specific hardware to acquire these signals. We designed a device capable of acquiring these signals so we could control the tuning and raw signal. There were two signals captured by our device, and the first was a PPG signal. This measurement was made by a sensor (Figure 3) that passed a light beam over the skin, to make the subcutaneous vessels illuminate. This made a part of this beam be reflected, falling on a photo sensor that converted it into an equivalent voltage. Because the skin absorbed more than 90% of the light, the diode pair was accompanied by amplifiers and filters that ensured an adequate voltage.

**Figure 2.** Wristband A prototype composition.

**Figure 3.** Photoplethysmography (PPG) and Galvanic Skin Response (GSR) sensors.

The second signal captured by our system was skin resistance, which is the galvanic response of the skin. This resistance varies with the state of the skin's sweat glands, which are regulated by the Autonomous Nervous System (ANS). If the sympathetic branch of the ANS is excited, the sweat glands increase their activity by modifying the conductance of the skin. The ANS is directly related to the regulation of emotional behavior in human beings. To capture these variations, a series of electronic devices was used, equipped with sensors or electrodes that were in contact with the skin. When there was a variation in skin resistance, these devices registered this activity and returned an analog signal, which was proportional to the activity of the skin. Figure 3 shows the device used to make this capture.

The analog signals returned by the sensors were digitized using the ESP-32's analog to digital converter. Our system used an ESP-32 TTGO development system (Figure 4), which is being widely used in IoT applications. This was mainly due to its easy programming and to the fact that it had WiFi, LoRa, and Bluetooth communication protocols with low power consumption or BLE. These features make this device the ideal tool to be used in monitoring applications.

In this way, the ESP-32 transformed the analog signals returned by the sensors to digital. This was done using the analog-to-digital converter of the ESP-32. The digitized signals were transformed as voltage equivalent to the acquired signal. To carry out the transmission of the acquired data, one of the communication protocols incorporated in the development system was used. The ESP-32 TTGO incorporated three communication protocols, WiFi, LoRa, and low power Bluetooth. We used the HTTP protocol for data transfer via WiFi to the server.

**Figure 4.** ESP-32 TTGO developer board.


**3. Seasonality and intensity of transmission**

Usually, dengue transmission occurs in rainy seasons with appropriate temperature and humidity for surviving of adult and larva mosquito. On the other hand, in arid areas, the rainfall is scant, and therefore, during the dry season, the man-made containers become the main breeding sites for the *Aedes* mosquito. Therefore, this can increase disease transmission.

In the ambient temperature, the life cycle of *Aedes* is shortening; also, there is production of small size mosquitoes, which may lead to the reduction of extrinsic incubation period. This small size mosquito may take more blood meal for egg production, which may lead to the increase in the number of infected mosquito and speedup the disease epidemic in the next dry season [50–52].

Several entomological factors have been associated with the initiation and maintenance of the epidemic including behavior, density, and vectorial capacity of mosquito vector population and introduction of the virus into a community.


**Figure 1.**

*Antibacterial activity and effect of pH on its release (electrospun nanofibers containing cloxacillin) [6].*

**83**

**Figure 2.**

*Electrospinning setup [11].*

*Electrospun Nanofibers: Characteristic Agents and Their Applications*

angora goats. Angora rabbits give us angora fibres [7].

extensively used method of producing nanofibers.

**2.1 Electrospinning mechanism**

Fibres can be natural - from animals or plants, or synthetic – man made. When fibres come from plants, cellulose is the polymer made from the sugar glucose that makes those fibres well-built. Natural fibres from plants include cotton, jute, hemp, sisal, and flax. Silk is formed from the cocoons of silkworms. Wool is soft hair that is cut from animals like sheep, goats, alpacas, llamas, and even rabbits. Both silk and wool are protein. Cashmere is an extra-soft fur from goats. Mohair is wool from

A lot of different polymers can be made into fibres. Fibres are formed when polymer chains are all lined up in the same direction [7]. Metallic fibres, Carbon fibres, fibreglass, mineral fibres, and polymer fibres are all subtypes of synthetic

Diverse types of natural and synthetic types of polymers are used to make nanofibers henceforth they exhibit unlike properties and applications. Instances of manmade polymers include poly lactic acid, polyurethane, polycaprolactone, polyethylene-co-vinyl acetate plus poly 3-hydroxybutyrate-co-3-hydroxyvalerate. Natural polymers comprise cellulose, collagen, gelatine, keratin, silk fibroin, then

There are many different methods to make nanofibers, including bicomponent

When the electrostatic force is applied on solutions or melts, electro-spinning produces fibres with diameters ranging from micrometre to nano-meter scale. A general electrospinning setup consists of three primary components: a syringe with a metallic needle, a high voltage power supply (usually in the kV range), and a grounded collector. When we consider a typical electrospinning course, high power is applied on melts/solutions. Consequently, suspended droplets are formed. A suspended droplet will collapse into a conical droplet as the electrostatic repulsion

alginate and chitosan. Polymer chains are linked via covalent bonds [9].

extrusion, drawing, electrospinning, thermal-induced phase separation, selfassembly template synthesis and centrifugal spinning [9, 10]. Electrospinning is an

*DOI: http://dx.doi.org/10.5772/intechopen.97494*

**2. Nanofiber's production**

fibres [8].


*Edited by Alaeddin Abukabda, Maria Suciu and Minodora Andor*

This book provides a broad overview of the molecular mechanisms associated with relevant and significant cardiovascular conditions that continue to plague humanity. It also discusses potential and promising therapeutic avenues targeted at addressing these conditions. The overarching goal of this multifaceted work is to entice future and current members of the scientific community to direct their endeavors towards improving our current knowledge of cardiovascular disease conditions and curb their impact on our everyday lives.

ISBN 978-1-83881-949-1

Cardiovascular Risk Factors in Pathology

Published in London, UK © 2021 IntechOpen © Lars Neumann / iStock


*Letter* **Low-cost Fiberoptic Probe for Ammonia Early Detection in Fish Farms**

#### **Arnaldo G. Leal-Junior 1,\* , Anselmo Frizera 1 and Carlos Marques 2**

Received: 15 April 2020; Accepted: 29 April 2020; Published: 1 May 2020

**Abstract:** Recirculating aquaculture systems (RAS) are complex systems in which there is an interaction between the fish biomass and water chemistry, where small variations in the environment can lead to major effects in the production. Ammonia is one of the key limiting factors in RAS and its early detection in small concentrations prevents fish mortality and improves the production quality. Aiming at this background, this paper presents a low-cost fiberoptic probe for the early detection of ammonia. The sensor was based on the chemical interaction between the Oxazine 170 perchlorate layer, deposited in an uncladed polymer optical fiber (POF), and the ammonia dissolved in water. In addition, a thin metallic layer (composed by gold and palladium) was deposited in the fiber end facet and acted as a reflector for the optical signals, enabling the use of the proposed sensor in reflection mode. Different configurations of the sensor were tested, where the effects of polydimethylsiloxane (PDMS) protective layer, thermal treatments, and the use on reflection or transmission modes were compared in the assessment of ammonia concentrations in the range of 100 ppb to 900 ppb. Results showed a better performance (as a function of the sensor sensitivity and linearity) of the sensor with the annealing thermal treatment and without the PDMS layer. Then, the proposed fiberoptic probe was applied on the ammonia detection in high-salinity water, where ammonia concentrations as low as 100 ppb were detected.

**Keywords:** polymer optical fibers; ammonia detection; optical fiber coating; aquaculture

#### **1. Introduction**

Aquaculture is the fastest growing food production sector in the world [1] and is therefore responding to the demands of ensuring sustainable global food security. Global aquaculture production has grown by nearly 7% per year. These demands are expected to continue to rise in response to projections of increased global population and the associated need for new protein sources. The marine fish aquaculture industry in Europe is dominated by Atlantic salmon (*Salmo salar*) in the north and by gilthead seabream (*Sparus aurata*) and European seabass (*Dicentrarchus labrax*) in the south.

Since the publication of the European Commission's 2013 Strategic Guidelines on the sustainable development of European aquaculture [2], the Commission has worked closely with Member States to address the barriers hampering the development of the sector while launching several campaigns to promote sustainable and competitive fish farming. A large part of this expansion and species diversification is expected to take place in land-based aquaculture facilities or intensive systems where water is reused in some form, such as recirculating aquaculture systems (RAS).

RAS are currently operating for many different species and have recently been developed to the large industrial scale. The highly technological RAS allows a very high degree of water reuse, normally in the range of 95–99% when compared to the water consumption in a flow-through system. Such facilities need to be designed for safe operation in the long-term, involving continuous and close monitoring of several critical parameters to safeguard fish welfare and profitability. The benefits of RAS are the reduced fresh and saltwater usage, reduced land requirement due to the high stocking density, reduced wastewater effluent volume, increased biosecurity by effectively treating disease outbreaks, and independence from weather and variable environmental conditions. Indeed, RAS satisfy the objectives of European Union for sustainable aquaculture by producing food while sustaining natural resources with a minimum ecological impact. However, RAS are complex systems where fish biomass and water chemistry/quality interact and where small variations may result in suboptimal conditions. These variations may cause stress and reduced feed intake and may ultimately result in reduced growth performance or even mortalities [3].

Ammonia is a limiting factor for producing fish in RAS [4,5], but the tolerance affecting mortality and growth varies [6]. Different water quality parameters affect the kinetics of the RAS biological filters (BF) [7], causing variation in ammonia removal. This gives rise to the dilemma of how to control and limit ammonia levels in order to optimize production under different conditions. Tolerance to ammonia varies between fish species and within different life stages and physiological status (starved, stresses, and health status) of the same species [8,9]. Furthermore, the type of rearing conditions may play a part. Other water quality parameters like temperature, carbon dioxide, oxygen, and salinity may also interact and influence the fish response to water quality and stress [8], which again can vary between different fish farms, and even throughout a production cycle. In addition, ammonia tolerance depends on how the fish acclimate to ammonia [10] and to changing water quality [11]. Not least, the different efficiency in which different RAS system convert ammonia to less toxic N-compounds varies depending on the RAS-design [12]. Acute levels of ammonia lead to acute mortality, while chronic levels of ammonia lead to suboptimal conditions for the fish. These suboptimal conditions are difficult to monitor but may result in reduced appetite and growth and eventually increased mortality [13]. Even in well-managed RAS, this is probably a common issue due to the many and intricate interactions between the fish and the other water quality parameters mentioned. The Food and Agriculture Organization (FAO) of the United Nations has advised that the ammonia levels should cover a range of at least 1-100 ng/mL [14,15].

In this way, water quality and toxicity levels in recirculation systems are critical, and ammonia is an important parameter which is closely linked to the fish excretion and efficacy of the BF. Growth and stocking density (biomass production and loading) are the main factors affecting the ammonia fluctuations and load in RAS [7]. The existing sensors for ammonia are generally used in sewage treatment plants and do not give consistent values in saltwater systems [9]. Moreover, there is a lack of available technology to add sensing elements before and after the BF and degassing column of a RAS.

In this respect, suitable multipoint monitoring elements for ammonia are essential. The use of optical fiber sensor-based devices offers many well-known and desirable features for label-free methods when compared with conventional electrical transducers. Examples are size, immunity to electromagnetic interference, cost, light path control, remote sensor deployment, high transmission rate, multiple sensors just on a single fiber and the use of biocompatible and biofunctionalized materials, and intrinsic safety and inert nature, which enables them to have minimal impact on the environment [16]. These advantages motivate the use of optical fiber sensors in medicine [17], environmental monitoring [18], and antibody detection [19]. Optical fiber sensors are selected for such applications due to their operational safety in aqueous environments and ease of introduction into the tanks, which eliminates the need to take samples to be tested in external instruments. Additionally, sensing can be performed with either a handheld probe or as a set of remotely operated devices along an optical fiber cable.

The optical fiber sensors approach for ammonia assessment is generally related to the use of nanoparticles or dyers that interact with the dissolved ammonia, resulting in intensity [20] or wavelength [21] variations in the optical fiber probe. An optical fiber interferometer was proposed by the authors of [21] for the ammonia detection. Using a nanocomposite coating, the sensor was able of detecting ammonia concentrations as low as 14 ppm, which is higher than the lower bound of ammonia detection in RAS [14]. In addition, wavelength-based sensors need an optical spectrum analyzer, which is generally a high-cost equipment. In order to obtain a low-cost sensor system, intensity variation-based systems have been proposed, such as the one presented by the authors of [22], where the luminescence from the nanoparticles upconversion was used on the sensor development. In this case, the sensor was tested in a range of 100-10000 ppm, i.e., far greater than the ammonia levels recommended in water. Similar techniques employed dyers in the lateral section of an optical fiber to evaluate the differences in the fluorescence as function of the ammonia levels [23]. The authors of [24] proposed a porous waveguide with a combination of copolymers as pH indicator, where ammonia concentrations as low as 10 ppm were measured. Then, with further improvements in the Oxazine 170 perchlorate deposition in polymer optical fibers (POFs), the authors of [20] proposed a highly sensitive ammonia sensor with detection limit of 1.4 ppm, the sensor was tested in stagnated and dynamic water. However, the approach was based on the transmission mode, which, for field applications, can lead to practical disadvantages on the sensor positioning. Moreover, intensity variation-based sensors are also sensitive to light source power deviations, and self-compensation techniques for these deviations need to be addressed for a higher resolution of the sensors.

Considering this background, this paper presents a low-cost POF sensor to cover the ammonia levels required by RAS and suitable to add in critical locations of a RAS, in which the proposed sensor was based on the reaction between the POF cladding with Oxazine 170 perchlorate and the water-dissolved ammonia. Such reaction led to variations in the evanescent field, resulting in optical power variations. In addition, a reflector was manufactured in the optical fiber tip in order to operate in the reflection mode, which brought important advantages regarding to the sensor positioning inside the water tank. Another advantageous feature was the possibility of using unclad POFs recycled from the LCD monitors (as depicted by the authors of [25]) for the sensor manufacturing, where the cladding was based on the Oxazine 170 perchlorate solution.

#### **2. Sensors Development and Experimental Setup**

An uncladed multimode POF with polymethyl methacrylate (PMMA) core was used on the fabrication of the optical fiber probe with a 980-µm core (ESKA Mitsubishi, Japan). The fiber diameter was about 1 mm and the fabrication of the proposed ammonia sensor occurred in a few steps, as summarized in Figure 1. The first step involved the gold-palladium (Au/Pd) thin layer deposition using a sputter coater. The sputter target was composed of 20% palladium and 80% gold. The POF end facet was positioned on the sputter target and the Au/Pd thin layer was created, where this layer acted as a mirror and reflects the optical signals, which enabled the use of the proposed sensor in the reflection mode.

Then, in the second step, the Oxazine 170 perchlorate was deposited on the fiber uncladed region by dip coating. The Oxazine 170 perchlorate deposition followed the methods discussed by the authors of [20], where a dye solution was prepared using 1 mg of Oxazine dissolved in 100 mL of distillated water though a temperature-controlled magnetic stirrer. The uncladed region of the POF was dipped in the Oxazine solution (without dipping the fiber end facet, which had the Au/Pd thin layer) for about 2 hours at 70 ◦C, as shown in Step 2 of Figure 1, where an u-bend was made on the fiber to position it without dipping its end facet. Thereafter, the fiber was removed, and the temperature of the solution was decreased to 20 ◦C. After the solution reached the input temperature (20◦C), the fiber was dipped again for 10 hours. The Oxazine 170 perchlorate dipping step was the one in which the sensor element was fabricated. The operation principle of the proposed sensor was based on the chemical reactions between the dissolved ammonia and the Oxazine layer on the uncladed POF. Such reactions led to differences in the evanescent field, which resulted in the optical power variation in the POF. The operation principle of the proposed sensor is depicted in Figure 2a, whereas a photograph of the sensor (Sample 3) is shown in Figure 2b.

**Figure 1.** Schematic representation of the steps for the samples preparation.

**Figure 2.** (**a**) Operation principle of the proposed sensors. The arrows are only a schematic representation, since the polymer optical fiber (POF) used had multiple propagating modes instead of just the ones presented in the figure. Figure inset shows ammonia diffusion in the sensing layer. (**b**) Photograph of the proposed sensor (Sample 3).

The chemical reaction between the Oxazine and the ammonia occurs at aqueous solution or in the presence of moisture, which is in accordance with the proposed application, i.e., ammonia sensing on water tanks. However, the direct contact between the sensor and the water can result in a lower lifespan of the proposed sensor if the water can remove the Oxazine layer. For this reason, in the third step (after the Oxazine 170 perchlorate deposition), a polydimethylsiloxane (PDMS) layer was applied. The PDMS layer was also applied by dip coating the optical fiber in the region where the Oxazine was deposited. As proposed by the authors of [20], the optical fiber was dipped in a water container before the application of the PDMS layer in order to create a region with entrapped water, which was needed for the chemical reactions between the Oxazine and ammonia. Then, the fiber was dipped in the PDMS curing agent solution with 24 hours for the layer curing. In this case, there was an additional mechanism in the sensor operation principle, which was the ammonia diffusion in the PDMS layer due to the pressure difference between the layer and the solution containing ammonia [20]. A schematic representation of the ammonia diffusion is presented in Figure 2a inset, where the pressure gradients in conjunction with the ammonia concentration resulted in higher ammonia diffusion into the PDMS layer. This additional mechanism can lead to higher response times for the sensor when compared with the one without the PDMS layer. However, as presented in previous works [20], the ammonia diffusion was fast (of a few seconds), and it was expected that the sensors with and without the PDMS layer would present similar response times. Nevertheless, the ammonia diffusion was also related with its concentration. For this reason, in the tests with variation of ammonia concentration, the sensor with the PDMS layer presented lower linearity than the one without this layer, which can be attributed to the concentration dependency of the ammonia diffusion.

In the last step, a thermal annealing was performed in the fiberoptic probe, where the sensor was positioned inside a climatic chamber at about 50 ◦C for 6 hours in order to reduce residual stresses created in the fiber during its manufacturing or during the previous steps of the sensor fabrication. In addition, the thermal annealing also accelerated the PDMS curing and provided a better adhesion of the Oxazine coating layer on the uncladed POF.

For the fiberoptic probe interrogation unit, an optical fiber coupler 2x1 IF 562 (Industrial Fiber Optics, USA) with 50:50 coupling ratio was used. The light source, comprising of a red laser (Phywe, Germany) centered at 650 nm (optical power of 4 mW) and a photodetector IF-D92 (Industrial Fiber Optics, USA), was positioned in the two input ports, whereas the other port was positioned in the fiberoptic probe. The photodetector was connected to a microcontroller with a 16-bit analog-to-digital converter FRDM KL25Z (NXP, Netherlands). The proposed probe was positioned inside a container filled with distillated water in which different concentrations of ammonium hydroxide solutions were injected. In this case, the ammonia concentration in the solutions ranged from 100 ppb to 900 ppb. In addition, the sensors were tested in sodium chloride solutions to verify its capability of detecting ammonia in high-salinity conditions, which are commonly found in fish farms.

In order to evaluate each of the steps for the fiberoptic probe fabrication, different set of samples (with three samples) were fabricated using different combinations of the steps. Figure 3 shows the experimental setup and the indication of which steps were used in each set of samples. It is worth mentioning that all samples were subjected to Step 2, in which the sensing layer was created, which resulted in similar Oxazine 170 perchlorate thickness of 35±5 µm for all samples. The comparison between samples was based on the sensitivity and linearity as a function of the ammonia concentration. In the first analysis, the sensors operating at reflection and transmission modes (with and without Step 1, respectively) were compared (Samples 2 and 4). Thereafter, the influence of the PDMS layer on the sensor responses was analyzed (Samples 1 and 2). Finally, annealed and nonannealed samples were compared, i.e., Samples 2 and 3. In the last test, the differences between the proposed fiberoptic probe spectral responses at high-salinity water were obtained with a spectrometer at the wavelength range of 400 nm to 900 nm USB4000 (Ocean Optics, USA) in order to verify if there were any variations in the spectral responses due to the water salinity.

**Figure 3.** Experimental setup for the sensor's response acquisition. The description of which steps were followed for each set of samples is also shown.

#### **3. Results and Discussion**

First, a statistical analysis was performed for each sample, where 15 consecutive measurements of each ammonia concentration were analyzed. In this case, one-way ANOVA was applied for each sample result to verify if there were significant statistical differences between measurements for a specific sample set. The one-way ANOVA tests perform for each sample and ammonia concentrations showed a p-value lower than 0.05 in all cases. These results indicate that there were no significant statistical differences in 15 measurement for each sample in different ammonia concentrations.

Figure 4a shows the mean and standard deviation results of the sensors with and without the PDMS layer for six ammonia concentrations in distillated water, from 0 ppb to 500 ppb in 100-ppb steps. It is worth mentioning that the responses were not in the same plot due to the larger differences in the sensors' sensitivities. In addition, the linearity of the sensors was presented as the determination coefficient (R2 ) between the sensors' responses and a linear regression. The results in Figure 4a show that the PDMS layer led to lower linearity of the sensor when compared with the samples without the PDMS layer. Although some differences in the sensors' sensitivities were expected due to some minor differences in the Oxazine layer thickness, there was a high difference in the sensitivity of the sensors with and without the PDMS layer. The sensors without the additional PDMS layer had a sensitivity of 0.025 ppm−1 , which was seven-times higher than the one obtained from the sensor with the PDMS layer (0.0036 ppm−1 ). Therefore, concerning the sensors' performance, the sensor without the PDMS layer was preferable for the proposed application. It is worth noting that the fiberoptic probe without the PDMS layer can have lower lifespan than the one with the PDMS protection. This feature can be verified in Figure 4a by the lower standard deviation of the probe with PDMS layer. However, the sensors were fabricated with low-cost methods (a few U\$ per sensor) and with easy assembly that enabled a scalable production and the replacement of probes in field applications.

In order to verify the sensor repeatability and reusability of the sensor without the PDMS layer (since it presented a better performance when compared with the one with PDMS layer), Figure 4b shows the results of the sensor as a function of time for two consecutive cycles, one in 300-ppb concentration, where the sensor was kept in this concentration for about 10 seconds, and the other in 600-ppb concentration. It is possible to observe in both cases that the sensor presented a response reversibility, since the normalized optical power returned to its initial value when the sensor was not immersed in ammonia solutions, where response times close to 5 seconds were found for both increasing and decreasing concentrations of ammonia. As another performance analysis of the sensor, its hysteresis was analyzed in cycles of ammonia concentration. As shown in Figure 4c, the sensor presented low hysteresis of 2.48%, which indicates the suitability of the sensor in detecting ammonia concentrations in dynamic cycles with low errors.

Regarding to the thermal treatment effects on the sensors' performance, Samples 2 and 3 were tested in a larger range of ammonia concentrations (from 0 ppb to 900 ppb) (see Figure 5). The results show that the nonannealed samples presented a nonlinear behavior that could be accurately represented by an exponential regression. Nevertheless, in concentrations below 60 ppb, the nonannealed samples showed lower sensitivity than the annealed ones. The annealed samples showed a high linearity, with R 2 as high as 0.98. However, the sensitivity of nonannealed samples was higher than the annealed one for ammonia concentrations higher than 600 ppb. For early ammonia detection, a sensor with higher linearity in low concentrations of ammonia is desirable. For this reason, the annealed samples were preferable for the proposed application, but it is worth noting that in environments with high ammonia concentrations, the nonannealed samples may lead to a sensor system with higher resolution in the ammonia detection.

**Figure 4.** *Cont.*

**Figure 4.** (**a**) Comparison between the fiberoptic probe responses with and without the PDMS layer as a function of the ammonia concentration. (**b**) Fiberoptic probe responses without PDMS layer as a function of time for two consecutive ammonia concentration cycles. (**c**) Hysteresis analysis of the proposed fiberoptic probe for ammonia detection.

**Figure 5.** Comparison between the fiberoptic probe responses with and without annealing as a function of the ammonia concentration.

The tests performed in the fiberoptic probes operating at transmission and reflection modes are presented in Figure 6, where both sensors presented similar sensitivities, i.e., 0.035 ppm−1 and 0.041 ppm−1 for transmission and reflection fiberoptic probes, respectively. Regarding to the sensors' linearity, the transmission mode presented higher linearity than the one of the reflection mode. However, the R2 values of both sensors were close to each other, which indicates compatibility between both operation modes. Therefore, due to the necessity of regular substitution of the probes and to facilitate their installation, the probe in the reflection mode was the preferable one, since both modes had similar performance.

**Figure 6.** Comparison between the fiberoptic probe responses in the transmission and reflection mode as a function of the ammonia concentration.

Then, the fiberoptic probe in the reflection mode with annealing and without the PDMS layer (Samples 1 and 2 in Figure 3) was tested in a sodium chloride solution to simulate an environment with high-salinity water as observed in RAS. Figure 7a presents the spectra of the sensors at each ammonia concentration to verify if the water salinity leads to other variations in the reflected spectrum (such as shift in the wavelength or spectral width) besides the intensity variation. However, the results in Figure 7a show only an amplitude (or intensity) variation on the reflected spectra, which indicate a similar performance of the sensor when compared with the results in distillated water. The Figure 7a inset shows the magnified view of the peaks, where the differences in the peak intensities can be observed. In addition, the proposed sensor was able to detect ammonia concentrations as low as 100 ppb with a straightforward and low-cost sensor approach, which can be used in many RAS industries for early detection of ammonia. Figure 7b shows the comparison between the sensor responses at distillated water and saltwater, where it is possible to observe that the sensor presented similar responses with a slight sensitivity reduction in saltwater. However, considering the standard deviations between measurements, the upper limit of the sensitivity in saltwater was 0.041 ppm−1 , whereas the lower limit of the sensitivity in distilled water was 0.040 ppm−1 . This analysis indicates that there were no significant sensitivity differences in sensors responses in distilled water and saltwater.

**Figure 7.** (**a**) Fiberoptic probe reflected spectra for different ammonia concentrations in high-salinity water. (**b**) Comparison between the sensors responses as a function of the ammonia concentration in distilled water and saltwater.

#### **4. Conclusions**

This paper presented the design and validation of a fiberoptic probe for ammonia detection. The sensor was based on the chemical reaction between Oxazine 170 perchlorate coating applied in an uncladed POF. Different design options were investigated, including the use of a PDMS layer in order to increase the sensor lifespan as well as thermal treatments (e.g., annealing) and their influence on the sensor performance parameters. Namely, the sensitivity and linearity were investigated. The transmission and reflection operation modes of the sensor were also investigated, where a thin layer of Au/Pd was deposited in the POF end facet in order to create a reflector for the probe operation in reflection mode. The sensor was tested not only in distillated water, but also in high-salinity water

to emulate different operation conditions. Table 1 presents a comparison between different optical sensors for ammonia detection.

**Table 1.** Comparison between lowest measured concentration and sensitivities of different ammonia sensors.

The proposed fiberoptic probe shows its feasibility on early ammonia detection, where concentrations as low as 100 ppb can be estimated with the proposed design. Compared with previously reported sensors in Table 1, the proposed sensor presented the lowest detection limit and highest sensitivity. Therefore, the proposed probe can be applied in different fish farms, including the ones with RAS, as a low-cost method for water quality assessment. In addition, with the development of recycled uncladed POFs [25], the proposed approach can be applied in such fibers for an even higher reduction of the system cost. In future works, the integration of this system with a multiplexing technique for the development of multiple probes and its application in a RAS system will be investigated.

**Author Contributions:** Conceptualization, A.G.L.-J. and C.M.; methodology, A.G.L.-J. and C.M.; formal analysis, A.G.L.-J., A.F. and C.M; investigation, A.G.L.-J. and C.M.; resources, A.F and C.M.; writing—original draft preparation, A.G.L.-J.; writing—review and editing, A.G.L.-J., A.F. and C.M; funding acquisition, A.F. and C.M. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research is financed by FAPES (85426300 and 84336650), CNPq (304049/2019-0 and 427054/2018-4) and Petrobras (2017/00702-6). C. Marques acknowledges Fundação para a Ciência e a Tecnologia (FCT) through the CEECIND/00034/2018 (iFish project) and this work was developed within the scope of the project i3N, UIDB/50025/2020 & UIDP/50025/2020, financed by national funds through the FCT/MEC. This work is also funded by national funds (OE), through FCT, I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19.

**Acknowledgments:** The authors would like to thank Tiago Silva, from Department of Materials and Ceramic Engineering (DEMaC), University of Aveiro, for his valuable support during the Au/Pd thin layer deposition.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).


*2.1. Chemicals*

Commercial reagents and antimicrobials used for the coating preparation were: chitosan (medium molecular weight, deacetylation degree 75%; Sigma-Aldrich, St. Louis, MO, USA); dichloromethane, DCM (Sigma-Aldrich); poly(d,l-lactide-*co*-glycolide), PLGA, Resomer RG503 (50/50; Evonik, Essen, Germany); chlorhexidine, CHX (Sigma-Aldrich); and rifampicin, RIF (Sigma-Aldrich).


**4. Experience in humans: efficacy of the intravenous administration of cyclodextrin**

The first two patients who received IV HP-β-CD (Trappsol® Cyclo™) in USA were treated since April 2009 with 2500 mg/kg weekly over 8 hours, and later modified to administrations every 2 weeks for convenience. The twins were diagnosed at 3 years old with initial symptoms of hepatosplenomegaly, ataxia and seizure activity, and previously were treated with miglustat, without significant benefits. After 18 months of therapy, any objective improvement was reported, and the disease continued to progress as evidenced by positron emission tomography (PET) imaging and neurological assessments [26]. Both patients were described a transient appearance of slight scattered nodules in lungs during bronchoscopy, which were identified as xanthomas, a deposition of yellowish cholesterol-rich material typical of NPD-C, resolved without treatment changes in IV therapy [32].

In October 2010, the FDA allowed the addition of HP-β-CD IT administration at doses of 350 mg every 2 weeks (initial dose 175 mg/2 weeks) [32, 33]. During the first months of concurrent IV/IT therapy, a significant improvement was observed in the validated NIH NPC Clinical Severity Score (NNCSS), as well as in the brainstem auditory evoked response (BAER) [33]. After 18 months, ICV route was authorized by FDA in the twins through an Ommaya reservoir system. One of them tolerated perfectly the ICV and continues today with the treatment, whereas in her sister, ICV was discarded by insertion bleeding and IT route was recovered. Both patients have experienced improvements in alertness, swallow, head control, and ataxia [32, 34].

The second reported use of IV HP-β-CD (Trappsol® Cyclo™) was in two Brazilian sisters at age of 12 and 16 years old with concomitant miglustat treatment. Dr Vieira employed the same IV protocol with a dose escalation from 1200 to 2500 mg/kg/week. Both patients showed, after 1 year of treatment, objective benefits in PET and NNCSS, as well as improvements in motor dysfunction, cataplexy, psychiatric symptoms, behavior, cognitive functions, and memory [27]. Two later reports informed about the simultaneous treatment with IV weekly and IT twice monthly at least 3 years, maintaining the good results previously reported with IV infusions [35, 36]. No adverse events (AEs) were reported, although the published data were limited and only congress abstracts were reported [27, 35, 36].

than previous scores before initiation, whereas the other patient reported a stabilization of NNCSS after IV therapy. In two patients with IV/IT therapy significant decrease in NNCSS were observed comparing pre and post-therapy scores. In the other seven patients was only available post-therapy information, showing in most of the cases an initial de decrease in NNCSS followed with a progressive increase. Other significant improvements were reported, as reduction in hepatomegaly, restoration of language skills, resolution of interstitial lung disease and improvements in fine motor control. The tolerability was favorable,

**Other AEs of interest**

http://dx.doi.org/10.5772/intechopen.71970

103

Port-a-Cath infection Removal of Ommaya

Post-operative delayed Parenchymal hemorrhage

Reservoir

Use of 2-Hydroxypropyl-Beta-Cyclodextrin for Niemann-Pick Type C Disease

Meningitis

Despite the positive results observed in the compassionate use of IV HP-β-CD [26, 27, 32–39], there is no clear evidence to date that IV route has a clinical benefit in CNS symptoms of NPD-C in humans. Most of the reports with neurological improvements combined the use of IV and IT/ICV administrations, making it impossible to demonstrate that these benefits were exclusively associated to IV and not IT/ICV. In addition, doses 1000 times larger than the IT dose should be required to achieve the same concentrations in the CSF reached by IT administration with IV infusions of HP-β-CD. This dosage would probably be unsafe in humans.

**5. Experience in humans: efficacy of the intrathecal administration of**

The IT route was proposed when the efficacy of IV infusions of HP-β-CD was questioned. The first cases of IT administrations were combined with IV, as we previously explained [33–37, 39]. At this point, IT route was proposed as the main route for NPD-C therapy. The first published case report of IT HP-β-CD (Trappsol® Cyclo™) administration was a Spanish girl diagnosed and treated at 2 years old. The dosage varied from 200 to 450 mg every 2 weeks. At 38 months an IT Ommaya reservoir (IT-OR) was implanted in order to increase patient convenience and reduce number of punctures, modifying the dosage to 400 mg every 2 weeks. The patient showed improvements in BAER test, whereas neurological symptoms and NNCSS were stabilized. The patient suffered two episodes of seizures with a fever with IT therapy, resolved without any change in treatment and which could be related to HP-β-CD, the pro-

although some AEs were reported during 6 years of therapy (**Table 1**).

**AEs associated with administration AEs recognized as features of**

**Table 1.** Adverse events related to IV with/without IT HP-β-CD administrations.

**NPD-C**

Seizures Pneumonia Thrombocytopenia Viral illnesses Viral syndrome

**cyclodextrin**

Rash

Headache Nausea Stomach pain

Generalized rash (trunk, elbow) Tremor/chills/vomiting/fever

cedure or the disease [40].

Two reported cases of Japanese NPD-C patients diagnosed at 2 months and 13 years were initially treated at 4 and 14 years old with the IV "Oakland protocol", with doses from 80 mg to 2500 mg/kg/three or two times a week, respectively [37, 38]. These were the first published cases of VTS-270 use in NPD-C. The younger patient reported with IV administration, a mild decrease in hepatosplenomegaly and temporary improvements in EEG and stabilization of disability scores the first 6 months. However, rest of the 2 years with only IV infusions a rapid progression of neurological dysfunction and worsening of swallow, speech, rigidity, and seizures were reported [37]. Furthermore, repeated fever with transient diffuse pulmonary cloudiness episodes were observed, an AE probably related to HP-β-CD IV infusion. After 2 years of IV therapy, IT first and later ICV administrations were combined with IV infusions [38]. The combined therapy obtained objective benefits in EEG, PET and magnetic resonance spectroscopy (MRS), and CSF T-tau level reduction. Furthermore, improvements in eye movement, language, and speech were reported, as well as and stabilization of clinical progression for 2 years. No AEs were detected over the 2 years of IV/ICV combined therapy.

The other patient, a girl of 14 years old at the time of HP-β-CD therapy onset, was only treated with IV infusions for 3 years. At the beginning of the treatment the patient showed benefits in EEG, MRS and visual evoked potential (VEP), but after 3 months disappeared. A decrease in hepatosplenomegaly was observed in abdominal ultrasound and body computed tomography (CT). The general condition, neurological tests, and seizure control were stabilized with therapy, reporting only an improvement in alertness. Tolerance of IV therapy was excellent [37].

Drs Hrynkow and Hastings recently reported in a Congress the clinical experience with 11 patients initially treated with IV HP-β-CD more than 6 years [39]. Two of these patients were only treated with IV infusions, whereas in nine patients IT therapy was added later. In the two patients with only IV therapy, one showed a progression in NNCSS similar

**Table 1.** Adverse events related to IV with/without IT HP-β-CD administrations.

In October 2010, the FDA allowed the addition of HP-β-CD IT administration at doses of 350 mg every 2 weeks (initial dose 175 mg/2 weeks) [32, 33]. During the first months of concurrent IV/IT therapy, a significant improvement was observed in the validated NIH NPC Clinical Severity Score (NNCSS), as well as in the brainstem auditory evoked response (BAER) [33]. After 18 months, ICV route was authorized by FDA in the twins through an Ommaya reservoir system. One of them tolerated perfectly the ICV and continues today with the treatment, whereas in her sister, ICV was discarded by insertion bleeding and IT route was recovered. Both patients have experienced improvements in alertness, swallow, head

The second reported use of IV HP-β-CD (Trappsol® Cyclo™) was in two Brazilian sisters at age of 12 and 16 years old with concomitant miglustat treatment. Dr Vieira employed the same IV protocol with a dose escalation from 1200 to 2500 mg/kg/week. Both patients showed, after 1 year of treatment, objective benefits in PET and NNCSS, as well as improvements in motor dysfunction, cataplexy, psychiatric symptoms, behavior, cognitive functions, and memory [27]. Two later reports informed about the simultaneous treatment with IV weekly and IT twice monthly at least 3 years, maintaining the good results previously reported with IV infusions [35, 36]. No adverse events (AEs) were reported, although the published data

Two reported cases of Japanese NPD-C patients diagnosed at 2 months and 13 years were initially treated at 4 and 14 years old with the IV "Oakland protocol", with doses from 80 mg to 2500 mg/kg/three or two times a week, respectively [37, 38]. These were the first published cases of VTS-270 use in NPD-C. The younger patient reported with IV administration, a mild decrease in hepatosplenomegaly and temporary improvements in EEG and stabilization of disability scores the first 6 months. However, rest of the 2 years with only IV infusions a rapid progression of neurological dysfunction and worsening of swallow, speech, rigidity, and seizures were reported [37]. Furthermore, repeated fever with transient diffuse pulmonary cloudiness episodes were observed, an AE probably related to HP-β-CD IV infusion. After 2 years of IV therapy, IT first and later ICV administrations were combined with IV infusions [38]. The combined therapy obtained objective benefits in EEG, PET and magnetic resonance spectroscopy (MRS), and CSF T-tau level reduction. Furthermore, improvements in eye movement, language, and speech were reported, as well as and stabilization of clinical progression for 2 years. No AEs were detected over the 2 years of IV/ICV combined therapy. The other patient, a girl of 14 years old at the time of HP-β-CD therapy onset, was only treated with IV infusions for 3 years. At the beginning of the treatment the patient showed benefits in EEG, MRS and visual evoked potential (VEP), but after 3 months disappeared. A decrease in hepatosplenomegaly was observed in abdominal ultrasound and body computed tomography (CT). The general condition, neurological tests, and seizure control were stabilized with therapy, reporting only an improvement in alertness. Tolerance of IV therapy was excellent [37]. Drs Hrynkow and Hastings recently reported in a Congress the clinical experience with 11 patients initially treated with IV HP-β-CD more than 6 years [39]. Two of these patients were only treated with IV infusions, whereas in nine patients IT therapy was added later. In the two patients with only IV therapy, one showed a progression in NNCSS similar

were limited and only congress abstracts were reported [27, 35, 36].

control, and ataxia [32, 34].

102 Cyclodextrin - A Versatile Ingredient

than previous scores before initiation, whereas the other patient reported a stabilization of NNCSS after IV therapy. In two patients with IV/IT therapy significant decrease in NNCSS were observed comparing pre and post-therapy scores. In the other seven patients was only available post-therapy information, showing in most of the cases an initial de decrease in NNCSS followed with a progressive increase. Other significant improvements were reported, as reduction in hepatomegaly, restoration of language skills, resolution of interstitial lung disease and improvements in fine motor control. The tolerability was favorable, although some AEs were reported during 6 years of therapy (**Table 1**).

Despite the positive results observed in the compassionate use of IV HP-β-CD [26, 27, 32–39], there is no clear evidence to date that IV route has a clinical benefit in CNS symptoms of NPD-C in humans. Most of the reports with neurological improvements combined the use of IV and IT/ICV administrations, making it impossible to demonstrate that these benefits were exclusively associated to IV and not IT/ICV. In addition, doses 1000 times larger than the IT dose should be required to achieve the same concentrations in the CSF reached by IT administration with IV infusions of HP-β-CD. This dosage would probably be unsafe in humans.