**Author details**

Ercan Oztemel Department of Industrial Engineering, Faculty of Engineering, Marmara University, Istanbul, Turkey

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© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**15**

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Networked Manufacturing Enterprises Management. London: Springer Verlag;

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*3.2.2 Frequency following response*

Few studies have investigated the frequency following response (FFR) in cases of otitis media. A study of two groups of children with a history of bilateral OM (recent onset and long-term) showed that FFR responses were affected in a statistically significant way in the onset portions (waves V and A) and offset portion (wave O), along with reduced values of the VA complex (more specifically VA slope) when responses between the groups were compared. The findings suggest that long-term OM in children is associated with a reduced neural conduction velocity relative to the processing time of speech stimuli, either at the beginning (onset) or final portion (offset), resulting in a decrease in the coding of speech in the brainstem [35] **Figure 4**.

Sanfins et al. [32] reported that children with a history of SOM present an increase in the absolute latency of all FFR waves compared to children with no history of otological problems. In addition, children without hearing loss have more coherent responses in both ears, whereas the group of children with a history of OME has a greater dispersion of latencies in all FFR components (**Figure 5**). Colella-Santos et al. [11] also reported a decrease in VA slope in girls with OME.


Premature ventricular contractions (PVCs) are common electrocardiographic findings in patients with and without structural heart disease. Prior evidence suggests that the presence of PVCs has prognostic value but it is unclear what underlying process they represent. A surprising observation in some studies has been an apparent association between higher mean resting heart rates and the presence of PVCs. Activation of the sympathetic nervous system is an important factor in the genesis of ventricular arrhythmias (Anderson, 2003; Podrid, Fuchs & Candinas, 1990). Enhanced automaticity, triggered activity, and reentry are all mechanisms generating rhythm abnormalities; all three mechanisms are markedly potentiated by the action of catecholamines. We sought to make use of our large database of electrocardiogram (ECG) data to confirm the prognostic significance of PVCs and analyze the interaction between heart rate and PVCs. We hypothesized that both elevated heart rate and the presence of PVCs are markers of sympathetic nervous system (SNS) activity and would, therefore, be correlated with each other and predictive of mortality. This would support the other lines of evidence suggesting that the sympathetic nervous system is active in the genesis of PVCs.

### **3. Research methods**

### **3.1 Study population**

All initial ECGs of consecutive veterans (outpatient and inpatient) who obtained ECGs for any reason at the Palo Alto VA Medical Center from April 1987 until December 1999 were considered in the study. From these 46,959 ECGs, those with atrial fibrillation and paced rhythms were excluded, leaving 45,402 for analysis.

### **3.2 Electrocardiography**

Computerized 12-lead resting 10-second ECG recordings were digitally recorded on the Marquette MAC system. Only the initial ECG was considered for patients with multiple ECGs in the database. Most of the ECG analysis was performed using the GE/Marquette ECG analysis program (www.gemedicalsystems.com). PVCs were defined as at least one QRS complex that was premature, ectopic shaped and had a QRS duration of greater than 120 ms. All ECGs classified as having PVCs were manually over-read by two cardiologists. Of the ECGs originally classified as having PVCs present, 14% were found to be misclassified as having PVCs when none were present. The most common reason for these errors was misclassification of artifact or of aberrantly-conducted supraventricular beats. All the misclassified patients were reclassified into the 'PVC absent' group, leaving 1731 patients for analysis in the 'PVC present' group.

The 'PVC present' ECGs were then reviewed to categorize the patterns and morphologic characteristics of confirmed PVCs. These characteristics included presence of multiple PVCs on a single 10-sec ECG, presence of couplets or salvos (≥3 consecutive PVCs), presence of bigeminal or trigeminal rhythm, and presence of multiform PVC morphologies. For the purposes of this study, complex PVCs were defined as repetitive PVCs (≥2 consecutive) and multiform morphologies. Non-sustained ventricular tachycardia was rarely documented on these short recordings and the few short runs of 3 or more consecutive beats were not analyzed separately.

Heart rate was determined by the program by counting all QRS complex templates in 10 seconds and multiplying by six. When PVCs were present, the R-R interval between the normal, dominant sinus QRS complexes (NN) was manually measured except when the pattern of PVCs made it impossible (i.e., bigeminy). This NN interval was used to calculate the intrinsic sinus rate.

An 'abnormal' ECG was defined as the presence of one or more of the following: pathologic Q waves, left or right bundle branch block, intraventricular conduction delay, Wolff-Parkinson-White syndrome, right or left ventricular hypertrophy (Romhilt-Estes), left atrial enlargement, or abnormal ST segments. All remaining ECGs were classified as 'normal'.

### **3.3 Follow-up**

28 Advances in Electrocardiograms – Clinical Applications

rest PVCs was associated with a 5.5 –fold increased risk of CV mortality (p=0.004). Considering the presence of PVCs during exercise and/or recovery did not affect our results. All five athletes with at least one PVC on a routine screening ECG as part of the annual physical exams had normal echocardiograms and no clinical manifestations of heart disease. Thus, we concluded that PVCs on a resting ECG are a significant and independent predictor of all-cause and cardiovascular mortality. Increased heart rate predicts mortality in patients with and without PVCs and the combination dramatically increases mortality. These findings together with the demonstrated independent association of heart rate with PVCs suggest that a hyper-adrenergic state is present in patients with PVCs and that it likely contributes to their adverse prognosis. In patients with heart failure the presence of PVCs on a resting ECG is associated with a significant increase in risk of CV death independent of age and exercise capacity. PVCs are rare in young athletes and do not appear to be

Premature ventricular contractions (PVCs) are common electrocardiographic findings in patients with and without structural heart disease. Prior evidence suggests that the presence of PVCs has prognostic value but it is unclear what underlying process they represent. A surprising observation in some studies has been an apparent association between higher mean resting heart rates and the presence of PVCs. Activation of the sympathetic nervous system is an important factor in the genesis of ventricular arrhythmias (Anderson, 2003; Podrid, Fuchs & Candinas, 1990). Enhanced automaticity, triggered activity, and reentry are all mechanisms generating rhythm abnormalities; all three mechanisms are markedly potentiated by the action of catecholamines. We sought to make use of our large database of electrocardiogram (ECG) data to confirm the prognostic significance of PVCs and analyze the interaction between heart rate and PVCs. We hypothesized that both elevated heart rate and the presence of PVCs are markers of sympathetic nervous system (SNS) activity and would, therefore, be correlated with each other and predictive of mortality. This would support the other lines of evidence suggesting that the sympathetic nervous system is active

All initial ECGs of consecutive veterans (outpatient and inpatient) who obtained ECGs for any reason at the Palo Alto VA Medical Center from April 1987 until December 1999 were considered in the study. From these 46,959 ECGs, those with atrial fibrillation and paced

Computerized 12-lead resting 10-second ECG recordings were digitally recorded on the Marquette MAC system. Only the initial ECG was considered for patients with multiple ECGs in the database. Most of the ECG analysis was performed using the GE/Marquette ECG analysis program (www.gemedicalsystems.com). PVCs were defined as at least one QRS complex that was premature, ectopic shaped and had a QRS duration of greater than 120 ms. All ECGs classified as having PVCs were manually over-read by two cardiologists.

associated with cardiac disease.

**2. Background**

in the genesis of PVCs.

**3. Research methods 3.1 Study population**

**3.2 Electrocardiography**

rhythms were excluded, leaving 45,402 for analysis.

The Social Security Death Index and California Health Department Service were used to ascertain vital status as of 12/31/00. Cause of death was available from the latter and deaths determined by the Social Security Death Index were classified by review of the Veteran's Affairs clinical data base. All-cause death and cardiovascular death were used as endpoints. Mean follow-up was 5.5 years. Data regarding cardiac interventions or events was not available.

### **3.4 Statistical methods**

Number Crunching System SoftwareÔ (Kaysville, UT) was used for all statistical analyses after transferring the data from a Microsoft ACCESS (Redmond, WA) database. Unpaired two-tailed t tests were used for univariate comparison of variables. Cox proportional hazard analysis was performed to evaluate those with and without PVCs and those with multiple and complex PVCs. Multivariate Cox hazard function analysis was performed to demonstrate if the various PVC characteristics were independently and significantly associated with time until death after considering age and other ECG abnormalities. Analysis was repeated using data from only those patients with normal ECGs. Kaplan Meier survival analysis was again performed after patients were divided into groups by heart rate (<60, 60-79, 80-99 and >100 bpm) and by the presence or absence of PVCs. Multivariate regression analysis was performed with heart rate as the dependent variable and with the following independent variables: age, gender, abnormal/normal ECG classification, in- or outpatient status and PVCs present or not. Logistic regression was performed with PVCs as the dependent variable and with the following independent variables: age, gender, abnormal/normal ECG classification, PVCs present or absent and in- or outpatient status.

The Prevalence and Prognostic Value of Rest Premature Ventricular Contractions 31

Those patients with PVCs had a significantly higher heart rate than those without PVCs (mean SD: 78.6 15 vs. 73.5 16 bpm, P<0.001). This heart rate difference persisted when patients were sub-grouped by gender, race, outpatient vs. inpatient status and those with otherwise normal ECGs (i.e., least likely to have structural heart disease). Those patients with PVCs always had a significantly higher mean heart rate. Further analysis of heart rate differences showed that women had a significantly lower mean HR than men (71.1 ± 13.7 vs 74.0 ± 16.2, p<0.001), outpatients had a lower mean heart rate than inpatients (72.5 ± 15.0 vs 76.9 ± 17.7, p<0.001), and those with an otherwise normal ECG had a lower heart rate than

**P- Value**

Age 65±12 66±11 0.05 65±12 68±10 <0.001

Height 69±3 69±3 0.26 69±3 70±3 0.30

Weight 186±39 186±39 >0.9 186±39 184±37 0.52

BMI 27±6 27±6 0.4 27±6 27±6 0.36

Outpatients 68% 68% 0.89 68% 67% 0.68

Heart rate 77±16 81±15 <0.001 79±16 84±14 <0.001

Q Wave 25% 23% 0.32 23% 31% 0.007

LVH 8 % 9% 0.59 8% 11% 0.18

RVH 0.3% 0.5% 0.60 0.3% 1.5% 0.009

RBBB 7% 7% 0.81 7% 7% 0.85

LBBB 3% 3% 0.77 3% 3% 0.81

LAE 10% 11% 0.81 10.5% 10.6% >0.9

Abnormal ECG 48% 47% 0.72 47% 54% 0.04

Table II. Demographics and ECG findings in patients with single versus multiple and non-

Age, height (inches), weight (pounds), BMI and heart rate are presented as the mean ± SEM. BMI = body mass index; ECG = electrocardiogram; LAE = left atrial enlargement; LBBB = left bundle branch block; LVH = left ventricular hypertrophy; PVC = premature ventricular contraction; RBBB =

right bundle branch block; RVH = right ventricular hypertrophy.

complex versus complex PVCs.

**Noncomplex PVCs N=1527**

**Complex PVCs N=199**

**P- Value**

those with an abnormal ECG (73.2 ± 15.6 vs 75.2 ± 16.8, p<0.001).

**Multiple PVCs N=815**

**Single PVCs N=911**

**Variable**

Demographics

ECG Findings

### **4. Results**

After exclusion of patients with atrial fibrillation and paced rhythms, there were 43,671 patients without PVCs and 1731 patients with PVCs (3.8%). Demographic and ECG characteristics of the groups are shown in Table I. The group with PVCs was older than those without PVCs (mean age SD: 65 12 vs. 56 15, P<0.001). As this was a VA study, the patients are 90% male but there was a slightly higher percentage of men among those with PVCs (90% vs. 94%, p=0.01). There were no significant differences between height, weight or BMI. Patients with PVCs had a significantly higher prevalence of Q waves, LVH, LAE, bundle branch blocks and ECGs classified as abnormal. Of the ECG characteristics evaluated, only RVH was similar between the groups.

Age, height (inches), weight (pounds), BMI and heart rate are presented as the mean ± SEM. BMI = body mass index; ECG = electrocardiogram; LAE = left atrial enlargement; LBBB = left bundle branch block; LVH = left ventricular hypertrophy; PVC = premature ventricular contraction; RBBB = right bundle branch block; RVH = right ventricular hypertrophy

Table I. Demographics and ECG findings in patients with and without PVCs.

After exclusion of patients with atrial fibrillation and paced rhythms, there were 43,671 patients without PVCs and 1731 patients with PVCs (3.8%). Demographic and ECG characteristics of the groups are shown in Table I. The group with PVCs was older than those without PVCs (mean age SD: 65 12 vs. 56 15, P<0.001). As this was a VA study, the patients are 90% male but there was a slightly higher percentage of men among those with PVCs (90% vs. 94%, p=0.01). There were no significant differences between height, weight or BMI. Patients with PVCs had a significantly higher prevalence of Q waves, LVH, LAE, bundle branch blocks and ECGs classified as abnormal. Of the ECG characteristics

> **No PVCs N=43,671**

Age 56±15 56±15 65±12 <0.001

Males 90.0% 90% 94% 0.01

Height 69±4 69±4 69±4 0.3

Weight 182 ± 40 182 ± 40 184 ± 41 0.1

BMI 27±6 27±6 27±6 0.4

Outpatients 73% 73% 70% 0.004

Heart rate 73.7 ± 16 73.5 ± 16 78.6 ± 15 <0.001

Q Wave 13% 11% 23% <0.001

LVH 5% 5% 8 % <0.001

RVH 0.3% 0.3% 0.3% 0.6

RBBB 4% 3% 7% <0.001

LBBB 1% 1% 3% <0.001

LAE 4% 3.8% 10.7% <0.001

Abnormal ECG 24% 23% 43% <0.001

Age, height (inches), weight (pounds), BMI and heart rate are presented as the mean ± SEM. BMI = body mass index; ECG = electrocardiogram; LAE = left atrial enlargement; LBBB = left bundle branch block; LVH = left ventricular hypertrophy; PVC = premature ventricular contraction; RBBB =

Table I. Demographics and ECG findings in patients with and without PVCs.

right bundle branch block; RVH = right ventricular hypertrophy

**PVCs**

**N=1,731 P-value**

evaluated, only RVH was similar between the groups.

**N=45,402**

**Variable Total**

Demographics

ECG Findings

**4. Results**

Those patients with PVCs had a significantly higher heart rate than those without PVCs (mean SD: 78.6 15 vs. 73.5 16 bpm, P<0.001). This heart rate difference persisted when patients were sub-grouped by gender, race, outpatient vs. inpatient status and those with otherwise normal ECGs (i.e., least likely to have structural heart disease). Those patients with PVCs always had a significantly higher mean heart rate. Further analysis of heart rate differences showed that women had a significantly lower mean HR than men (71.1 ± 13.7 vs 74.0 ± 16.2, p<0.001), outpatients had a lower mean heart rate than inpatients (72.5 ± 15.0 vs 76.9 ± 17.7, p<0.001), and those with an otherwise normal ECG had a lower heart rate than those with an abnormal ECG (73.2 ± 15.6 vs 75.2 ± 16.8, p<0.001).

Age, height (inches), weight (pounds), BMI and heart rate are presented as the mean ± SEM. BMI = body mass index; ECG = electrocardiogram; LAE = left atrial enlargement; LBBB = left bundle branch block; LVH = left ventricular hypertrophy; PVC = premature ventricular contraction; RBBB = right bundle branch block; RVH = right ventricular hypertrophy.

Table II. Demographics and ECG findings in patients with single versus multiple and noncomplex versus complex PVCs.

The Prevalence and Prognostic Value of Rest Premature Ventricular Contractions 33

event free survival between groups is also clearly demonstrated with Kaplan-Meier cumulative survival curve (Figure 2). The PVC and heart rate stratifications performed similarly when patients were divided into those with normal and abnormal ECGs. Cox regression analysis (controlled for age, gender, outpatient vs. inpatient status and normal vs. abnormal ECG) demonstrates that PVCs (RR 1.61, 95% CI 1.44-1.80, p<0.001) and heart rate (RR 1.02 for each 1 bpm increase, 95% CI 1.01-1.02, p<0.001) are independent predictors of

> **Heart Rate 60-79**


**2. Materials and Methods**

The Nesamovyte Lake is one of the highest mountain waterbodies of its type in Ukraine, located in the central, highest mountainous part of the Eastern (Ukrainian) Carpathians– Polonyno-Chornogora geomorphological area [68], belonging to Carpathian-Danube algofloristic sub-provinces according to algofloristic zoning of Ukraine [69]. The lake is located in the Carpathian National Nature Park (48◦07 36.6 N, 24◦32 26.4 E) and is situated in the glacial mountain trench on the eastern slope of Mount Turkul (Chornohora Ridge, Eastern Carpathians, and is approximately 5 km from the highest mountain in Ukraine—Hoverla) at an altitude of 1 748 m above sea level (a.s.l.) belongs to the water basin of the Prut River (Figure 1). According to the origin of the lake, it can be called a polymictic tarn that refers the following explanation 'a proglacial mountain lake, pond or pool, formed in a cirque excavated by a glacier' [70].

**Figure 1.** Map of the Carpathian region and the location of the Nesamovyte Lake. (**A**)—the Carpathian Mountains with its Eastern part the Ukrainian Carpathians. (**B**)—map-scheme of Chornohora Massif with the location of the lake. (**C**)—littoral zone of the lake.

The lake covers an area of about 0.4 hectares (about 88 × 45 m) and has a depth of about 2 m and, according to the EC Water Framework Directive [29], belongs to the category of small and very small lakes. In general, the lake water is generated by rain and melting snow with a sandy muddy bottom (rocky from geological rocks of sandy flysch near the southern and western coast and sandy-muddy—in the northern part), it has a long period of freezing (October-May up to a depth of 1.5 m). It belongs to the cold climatic zone of the Carpathians. The summer water temperature normally is 18.3–(12.4) ±3.2 ◦C. The lake has a slow underground runoff in the north-western direction, through a narrow channel on the alloy (swamp intrusion). This part of the lake is intensively overgrown by *Carex rostrata* Stokes and *Sphagnum* spp. Other moss-like organisms and sedge-sphagnum alloy cover the surface of the lake up to 35 cm from the shore and occupies about 40% of the lake bed area and reaches 1 m in thickness. The water in the lake corresponds now to the hydrocarbonate-sulphate-sodium class (Table 1) and belongs to zones of saprobity from oligo- to β-mesosaprobic [71–75]. The hydrochemical formula of water of the lake [76] is as follows: M0.018 SO4 HCO3 42/Na 79 Ca 21. According to EUNIS classification, [77], the Nesamovyte lake belongs to biotopes C1.1 or B1.1.1 (permanent oligotrophic lakes, ponds, puddles).

The material for this study was built on the analysis of the first record (1910–1920) for the Nesamovyte Lake published by Wołoszy ´nska, work with samples from 1967–1978 (collectors Prof. Z.I. Asaul and Prof. G.M. Palamar-Mordvintseva) and our previous investigations (2013–2018).

The species list provided by Wołoszy ´nska (collected in 1910) [67] was carefully analysed and describes the period between 1910–1920.

From 1967 to 1978, samples from Algoteca funds of M.G. Kholodny Institute of Botany of NAS of Ukraine (AKW)—NN 16855–16898 (samples from the year 1967–1978, collectors Prof. Z.I. Asaul and Prof. G.M. Palamar-Mordvintseva) were studied (44 samples). In addition, the data based on these samples published from the period of 1967–1978 [2–5] were included in the current analysis.

To characterize the modern period (2013–2021), 18 samples of net plankton (50–100 L of water filtered out), periphyton from vascular plants (dead and living parts of herbaceous plants (*Carex rostrata*) and pine branches (*Pinus mugo* Turra) and squeezes from the moss (*Sphagnum* spp.) were collected along the perimeter of the lake in August 2013–2018. To study the species composition of *Bacillariophyta*, the method of forming a combined sample from different studied substrates was used. This study is based on the living algal material from plankton (algal cultures, with the addition of BBM-medium) [78] and samples that were fixed with 4% formaldehyde solution.

The obtained results are comparable because almost identical methods for collecting and fixation of the algal material were used in all the studied periods (1910–1920, 1967–1978, 2013–2021).

The algae were studied and identified using light (LM) and scanning electron (SEM) microscopy, the permanent slides of diatoms were made according to the standard procedure using 35% H2O2 [79]. For LM investigations, the diatoms were fixed in the synthetic mounting medium Naphrax (refractive index 1.74) and investigated under a BX-53 microscope (Olympus, Tokyo, Japan). The slides are stored in the Algotheca of M.G. Kholodny Institute of Botany, NAS of Ukraine (AKW). For SEM analysis, the samples were put to specimen stubs, dried, covered with gold (10–20 nm) JFC-1600 sputter coater, and examined in a scanning electron microscope JSM-6060LA (JEOL, Tokyo, Japan) at the Institute of Botany in the Center of Electron Microscopy. The resulting micrographs were processed using the software packages Axiovision 4.3.7. (Carl Zeiss MicroImaging GmbH, Jena, Germany) and GIMP 2.8.10.m (Free Software Foundation, Inc., Boston, MA, USA).

1.

Identification of the species diversity was carried out according the Süßwasserflora von Mitteleuropa [80–85] with some newer updates from Diatoms of Europe [86–89], Diatomeen im Süßwasser-Benthos von Mitteleuropa [90] and Flora of algae of Ukraine [91–97] as well as with updates from [98–102], and electronic resources [103]. The identified taxa, as well as all algal species lists from previous years of studies of the territory were validated using the AlgaeBase system [104] and "Algae of Ukraine . . . " [105] monographic series.

Ecological bioindicator species analysis was based both on the historical data (1910– 1920 and 1967–1978 collections) and the results of our studies (2013–2021) [2–4,61,63,65,67, 106,107]. The following ecological characteristics were used: Habitat preference, streaming and oxygenation, pH [108], salinity, trophic state and сlass of organic pollution [109–112]. Identification of organic pollution by the values of saprobity indices and indicator groups, equated to water quality classes [113,114]. Considering the groups of indicators that we identified, the intervals of the quality classes were distributed as follows: I—0–0.5 (x, x-o); II—0.6–1.5 (o-x, x-b, o, o-b), III—(b-o, o-a, b, b-a) and IV—(a) [112,115–117]. Ecological features of the species were presented according to [112,117,118].

The Cluster analysis of algal composition was carried out using the Paleontological Statistics Software (PAST, Palaeontological Association, Hammer & Harper, Oslo, Denmark, Galway, Norway, Denmark, Ireland) to measure the degree to which species composition was similar among the studied periods (1910–1920, 1967–1978, 2013–2021) [119]. For this purpose, the presence/absence of data were used in the meaning of the Sørencen coefficient, calculated in the program as Bray-Curtis Similarity index [120].


**The Use of the Spectrometric Technique FTIR-ATR to Examine the Polymers Surface**

Wieslawa Urbaniak-Domagala

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/48143


**Argyro Pachi**

Dr. Pachi Argyro was born and raised in Athens. She studied at the National and Kapodistrian University of Athens' School of Medicine and holds a Master's degree in the "Mental Health Promotion and Prevention of Psychiatric Disorders" from the National and Kapodistrian University of Athens. She has worked for more than 30 years in primary, secondary, and tertiary psychiatric care. For the last five years, she has been the Director of the Psychiatric Department of the General Hospital of Chest Diseases in Athens. She has a substantial educational and research background with numerous publications in national and international peer-reviewed journals.


*2.5. Missing Data*

Some of the independent variables used in the analysis had a large percentage of missing cases: maternal BMI (5.1%) and equivalised household annual income (7.8%). This would have resulted in a proportion of the sample being lost from the analysis. In response, multiple imputation has been carried out in STATA 13 using the variables maternal age, maternal education, father's education, household class, maternal employment status, current maternal smoking and migrant status to predict the missing values in maternal BMI and equivalised household annual income.


*4.3. Dispute Resolution Pathways and Resolution Preference*

Despite the different categories of land-related disputes in the study areas, they did not translate into widespread tenure insecurity. The field data suggest that the mechanisms for dispute resolution were largely localised within the socio-political system, with very little variation between the study sites (Table 3). From Table 3, the overall results show that traditional courts (including clan/family heads (Abusuapanyins)) and stool land offices were the main adjudicatory institutions utilised by respondents. On face value, this seems to indicate that several fora were opened to landholders in terms of the enforcement and legitimation of their land rights. Critically, however, this does not reflect the actual situation on the ground, which is seemingly complex and negotiated exemplified by opportunism and the elite capture of the adjudicatory process. Indeed, the quantitative analysis demonstrates statistically significant differences regarding access to dispute resolution institutions across studied groups. For instance, when asked whether they had ever sought help from traditional authorities or statutory courts in the resolution of land-related disputes, a far less proportion of respondents in Kakum (11%) and Ankasa (10%) indicated they had made recourse to the traditional authorities or statutory courts regarding the resolution of land-related disputes (Table 3). This observation was corroborated during the interviews as participants explained that in the event of land disputes, they preferred private resolution through negotiation moderated by the Abusuapanyins and/or Odikro6 at first instance. In the failure of such private resolution, recourse was made to any of the above-identified institutions.

**Table 3.** Mechanisms for land dispute adjudication.

Whereas Table 3 demonstrates a limited recourse to adjudicatory mechanisms, there is a sense of trust in the mediation afforded by traditional authorities as opposed to statutory institutions. During the community FGDs, participants cited the inaccessibility, delays in adjudication, cost, public image and fear of being labelled vexatious litigant as the reasons for their preference traditional dispute resolution mechanisms. These customary mechanisms played a pivotal role in maintaining social cohesion in their communities, particularly as most disputing parties are relatives or neighbours in the same village. Traditional authorities (who interpret and administer custom) were well-versed with the

6 Odikro is the village chief or headman in the Akan traditional areas of southern Ghana.

local customs, norms and rules governing communal landholdings and thus more capable of dealing with contestations over land use and ownership. Two typical remarks by key informants are illustrative of the above observation:

*'Most people prefer an amicable settlement of their land-related disputes by making recourse to the Odikro and his elders as opposed to the court. This is due to several reasons, including the fact that the courts are expensive, delays in going to and fro and the fear of being labelled a litigant, which could affect or strain social relationships between families and friends in the community* ... *'. (Interview 1, Kakum)*

*'In this community we see ourselves as one, and as such, we try to resolve any disputes, especially in relation to land, amongst ourselves, sometimes even without seeking help from Odikro and his elders. Neglect of the customary structures could attract some scorn and/or sanctions from other members of the community* ... *'. (Interview 1, Kakum)*

The overwhelming stated preference for traditional adjudicatory mechanisms relative to the statutory courts in the study areas also finds expression in the observation that institutional constraints and allegations of corruption impede the effective functioning of the state courts as secure avenues for the protection of land rights irrespective of social status [39,57,58]. Indeed, interviews with some officials of the stool land office and CLS revealed that the local populace were quite sceptical that the statutory mechanisms would best serve their interests and/or protect their land rights as powerful entities could influence decisions in their favour. This is indicative of Platteau's [57] remark that 'in social contexts dominated by differential access to state administration [as in Ghana's case], there is always the fear that the adjudication/registration process will be manipulated by the elite to its advantage'. At the same time, the foregoing also brings to the fore an important question as to the effectiveness of these customary mechanisms in the protection of land rights of different social groups. This is discussed within the context of the respondents' satisfaction with the customary adjudicatory mechanisms.


**6. Evaluation of antimicrobial finishes**

The AATCC Technical Manual12 has a number of test methods that are useful for evaluating antimicrobial finishes on textiles. These tests are summarised in Table 1. Two types of antimicrobial tests are dominant, the agar-based zone of inhibition tests and the bacteria counting tests. The relatively new ISO/DIS 20645 and the corresponding EN ISO

Textiles with biostatic properties, however, are subject to fewer regulations. The actual mechanisms by which antimicrobial finishes control microbial growth are extremely varied, ranging from preventing cell reproduction, blocking of enzymes, reaction with the cell membrane (for example with silver ions) to the destruction of the cell walls and poisoning the cell from within. In Figure 11 and 12 the chemical structures of some of antimicrobial

agents are shown.

Fig. 12. Bound antimicrobials

4. colourless and odourless;

12. no environmental problems.

chemicals;

2. durable for the life of the product;

It is fairly easy to list the desirable properties of an 'ideal' biocide: 1. wide spectrum of effectiveness against both bacteria and fungi;

5. reasonable cost, and effective at low concentrations; 6. resistant to leaching, weathering and sunlight;

11. withstands processing conditions and temperatures;

10. applicable using standard textile machinery;

**6. Evaluation of antimicrobial finishes**

3. non-toxic to humans at concentrations used – safe to handle and use;

7. no adverse effect on handle or other physical properties of the fabric;

9. does not accelerate or catalyse other degenerative processes;

8. compatible with water-repellent and flame-retardant finishes, dyes and other textile

The AATCC Technical Manual12 has a number of test methods that are useful for evaluating antimicrobial finishes on textiles. These tests are summarised in Table 1. Two types of antimicrobial tests are dominant, the agar-based zone of inhibition tests and the bacteria counting tests. The relatively new ISO/DIS 20645 and the corresponding EN ISO

**5. Practical biocides**

20645 are based on the agar diffusion test and ISO 11721 is a burial test (part 1 for the determination of an antimicrobial finish and part 2 for the determination of the long-term resistance). The main difficulties of these tests are mostly poor reproducibility of the test results and often insufficient correlation between laboratory results and actual conditions in the field. Careful attention to detail and trained laboratory personnel are essential for accurate and repeatable results from these methods.( Schindler & Hauser, 2004)

A more rapid test method, developed by the British Textile Technology Group in the late 1980s, is based on adenosine triphosphate (ATP) luminescence. The growth of microorganisms is assessed by firefly bioluminescent detection and ATP analysis.3

Table 1. Comparison between different AATCC test methods

Antibacterial Agents in Textile Industry 405

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Ghoranneviss.M, Shahidi.S, Effect of Various Metallic Salts on Antibacterial Activity and

Gupta.D, Haile.A, (2007) Multifunctional properties of cotton fabric treated with chitosan

Hashemikia.S, Montazer.M , (2012) Sodium hypophosphite and nano TiO2 inorganic

Hegemann.D, Mokbul Hossain.M, Balazs.D.J, (2007) Nanostructured plasma coatings to obtain multifunctional textile surfaces, *Progress in Organic Coatings,* 58, 237–240

Ibrahim.N.A, Eid.B.M, El-Batal.H, (2012) A novel approach for adding smart functionalities

Ignatova. M, Manolova.N, Rashkov.I , (2007) Novel antibacterial fibers of quaternized

Ignatova.M, Starbova.K, Markova.N, Manolova .Nand Rashkov.I, (2006) Electrospun nano-

Knill.C.J, Kennedy.J.F, Mistry.J, Miraftab.M, Smart.G, Groocock.M.R, Williams.H.J, (2004)

Krishna Raghupathi, R., Ranjit Koodali, T. & Adhar Manna, C. (2011). Size-dependent

Kumar.V, Bhardwaj.Y.K, Rawat.K.P, Sabharwal.S, (2005) Radiation-induced grafting of

Liu.X, Zhao.X, Li.B, Cao.C, Dong.Y, Ding.C, Chu.P.K, (2008) UV-irradiation-induced

Montazer.M, Alimohammadi.F , Shamei.A, Rahimi.M.K (2012) In situ synthesis of nano silver on cotton using Tollens' reagent, *Carbohydrate Polymers,* 87, 1706– 1712 Potiyaraj.P, Kumlangdudsana.P, Dubas.S.T, (2007) Synthesis of silver chloride nanocrystal

Selvam.S, Sundrarajan.M, (2012) Functionalization of cotton fabric with PVP/ZnO

nanoparticles for improved reactive dyeability and antibacterial activity,

anti-bacterial activities, *Radiation Physics and Chemistry*, 73, 175–182

Matsunaga.T, Tomoda.R, Nakajima.T, Wake.H, (1985) FEMS *Microbiol. Lett*. 29 , 211.

Robertson.J, Robertson.P, Lawton.L, (2005) *Photochem.J. Photobiol., A Chem*. 175 , 51.

Schindler.W.D , Hauser.P.J, Chemical finishing of textiles, woodhead publishing,2004

and carboxymethyl chitosan, *Carbohydrate Polymers,* 69, 164–171

fabrics, *Progress in Organic Coatings* , 70, 388–393

*Applied Catalysis A: General*, 417– 418, 200– 208

*Polymer Journal* ,43, 1112–1122

Heywood.D, Textile Finishing, 2003, Society of Dyers and Colourists

alcohol) *, Carbohydrate Research*, 341, 2098–2107

dressings , *Carbohydrate Polymers*, 55, 65–76

nanoparticles. Langmuir, 27, 4020–4028.

on silk fibers, *Materials Letters* 61 2464–2466

Carbohydrate Polymers 87 , 1419– 1424

to cellulosic fabrics, *Carbohydrate Polymers*, 87, 744– 751

2012

552

of plasma sputtering treatment on natural dyeing and antibacterial activity of wool

Physical Properties of Cotton Fabrics, *Journal of Industrial Textile*, online published,

catalysts along with citric acid on textile producing multi-functional properties,

chitosan and poly(vinyl pyrrolidone) prepared by electrospinning, *European*

fibre mats with antibacterial properties from quaternised chitosan and poly(vinyl

Alginate fibres modified with unhydrolysed and hydrolysed chitosans for wound

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bioactivity on TiO2 coatings with nanostructural surface, *Acta Biomaterialia,* 4, 544–


**3. Refrigerants**

*Low-temperature Technologies*

GWP 150+

**Table 1.**

checked every 3 months.

*Source: Regulation (EU) N°. 517/2014 [5].*

*Equipment with dates for prohibiting the use of refrigerants.*

with the dates set out in **Table 1**.

The Article 4 of this Law establishes that stationary refrigeration equipment, air conditioners, and heat pumps must have an operator that checks for leakage points on the equipment according to the equivalent amount of CO2 in refrigerant charge where 5 or more equivalent tons of CO2 should be checked at least once a year. For equipment with an equivalent load above 50 tons of CO2, this check should be performed every 6 months. Systems with loads over 500 tons equivalent must be

**Equipment Prohibition**

Household freezers and refrigerators with HFC refrigerant and greater than 150 GWP January 1, 2015 Cold rooms for commercial use HFC with GWP 2500+ January 1, 2020

Fixed refrigeration equipment with HFC refrigerant and with GWP greater than 2500 January 1, 2020

Mobile residential air conditioning equipment using HFC refrigerant with GWP 150+ January 1, 2020 Fixed residential air conditioners with load less than 3 kg and GWP 750+ January 1, 2025

Commercial central cooling system with a capacity of 40 kW or higher that works with

**date**

January 1, 2022

HFC with GWP 150+ January 1, 2022

Article 13 cites restrictions on the use of F-gas and imposes that from January 2020, the use of F-gas with GWP equal or greater than 2500 shall be prohibited in refrigeration systems with an equivalent load of 40 tons of CO2 or more. Nevertheless, if the fluid used in the system can be recovered, reprocessed, and

**Table 1** shows some air conditioning and refrigeration equipment with their

The questions of the regulation of refrigerants is the application of control mechanisms over the use and disposal of F-gas in each country in order to comply

For the purpose of facilitating the understanding about this chapter and the application in HVAC and refrigeration's systems, some definitions used by law and by some educational and research entities and institutions are presented below:

• **Global warming potential (GWP):** This is the direct mass comparison of CO2 that a fluid causes when released into nature over a 100-year period [5].

• **Tons of CO2 equivalent:** Quantity of mass with a global warming potential

• **Recovery or regeneration:** Process of gathering and direct F-gas storage equipment, i.e., the removal of a refrigerant from system to store it in an external tank [14]. In this process some contaminants found in the systems are removed, like oil, water, oleic acid, and hydrochloric acids. In this sequence, the refrigerant is distilled and then filtered, condensed, and analyzed, and if it complies with ARI 700 Standard (purity, humidity, acidity, non-condensable

gases, and maximum allowable residue levels), then it will be refilled.

• **Recycling:** Reuse of F-gas after a treatment process, that is, is the process involving the cleaning of refrigerant by an oil separator and a filter drier for

reused, it will have its utility extended until January 1, 2030.

multiplied by a global warming potential coefficient.

respective prohibition dates for their refrigerants.

**80**

Refrigerants can be defined as substances that serve as a means of transport and heat transfer, absorbing heat at low temperatures and rejecting it at higher temperatures [15]. From that definition, in principle, any substance that changes phase in the refrigeration or air conditioning cycle, from liquid to vapor during heat absorption and from vapor to liquid during heat rejection, may function as a refrigerant. Their commercial usefulness depends on the temperature ranges and pressure at which the system will operate and, more recently, the environmental impacts that eventually this refrigerant can cause when released into the environment.

Water and air can also be considered as fluid refrigerants, although they do not show phase change during the process as well as other synthetic fluids or not form aqueous solutions that are characterized by operating at temperatures below 273.16 K (0°C) without crystallizing.

Among the various properties that a refrigerant should include for use in air conditioning and refrigeration systems, the most important are [15]:

	- ix.Having adequate compatibility with the materials of the refrigeration system.
	- x.Be easy to detect.
	- xi.In case of leakage, it should not attack or spoil food, should not contribute to global warming, and should not attack the ozone layer.

xiii.Be commercially available at a reasonable cost.

The refrigerant groups available in the Brazilian market are divided into [15, 16]:

• **CFCs (chlorofluorocarbons):** They are refrigerant fluids whose molecule is formed by the element's chlorine, fluorine, and carbon, for example, the fluids R-11, R-12, R-113, R-114, R-115, and R-502, among others. The lifetime of CFCs in the atmosphere ranges from 60 to 540 years, causing high depletion of the ozone layer. Most CFCs have an ozone layer depletion potential (ODP) index ranging from 0.6 to 1.

CFCs were no longer manufactured by industrialized countries in January 1996 and, with some exceptions, by developing countries. These fluids feature high ODP and high GWP. According to the Montreal Protocol, in 1996 these gases were banned from developed countries, and in 2010 they should be banned from developing countries such as Brazil, but these gases are still found in old refrigeration and air conditioning systems. These fluids are used in automotive air conditioners, commercial refrigeration, and home refrigeration (refrigerators and freezers).

• **Hydrochlorofluorocarbons (HCFCs):** In these refrigerants some chlorine atoms are replaced by hydrogen, as an example of these fluids, have it R-22, R-123, R-401A, and R-4012A. These fluids are used in climate control systems, window air conditioners, split air conditioners, self-containers, cold rooms, etc.

These gases represent the second generation of fluorinated gases and were the main alternative to CFCs. They have lower ODP, but the GWP still between 1000 and 5000, so they are a little less harmful to the environment than their CFC predecessors, considering the ozone depletion. HCFCs are not fully halogenated like CFCs. The atmospheric lifetime of HCFCs ranges from 2 to 22 years, and therefore their ODP ranges from 0.02 to 0.1 [15, 17].

Currently, in Brazil, HCFC-22 or (R-22) has been the most commonly used refrigerant in air conditioning systems since the early 1990s. HCFCs have been used as transition fluids, and their restriction on use and manufacturing started in 2004. According to the Montreal Protocol, the elimination of HCFCs in developed countries is expected by 2030 and in Brazil by 2040. Nevertheless, some countries are already well advanced on their elimination. In the European Union the use of HCFCs was terminated in January 2010 and may still be used until January 2015 in some specific cases.

• **Hydrofluorocarbons (HFCs):** In these fluids all chlorine atoms are replaced by hydrogen, for example, R-134a, R-404A, R-407C, R-410A, etc. These fluids

**83**

*An Experimental Study of Synthetics and Natural Refrigerants Gases*

domestic refrigeration (refrigerators and freezers), etc.

(CO2), hydrocarbons, R718 (water), and R729 (air).

systems than HCFC and HFC fluids.

ensures a low risk of fire if a leak occurs.

to other types of fluids.

categories, which are:

are used in automotive air conditioning systems, commercial refrigeration and

As there are no chlorine atoms in HFCs refrigerants, they do not cause ozone layer depletion. HFCs are expected to become the most widely used in air conditioning systems in the coming decades. These fluids can be said to represent the third generation of fluorinated gases that have zero ODP and median and high GWP values. Currently, HFCs are largely used in commercial refrigeration and residential

• **Hydrofluoroolefins (HFOs):** The HFOs represent the fourth generation of fluorinated gases, with zero ODP and very low GWP values. It is already being used in automotive air conditioning systems in developed countries (the United States and Europe). They are fluids used in place of R-134a as they are suitable for high temperature applications and operate at similar

• **Natural refrigerants:** These fluids are generated through natural biochemical processes, so they pose no risk to the ozone layer and have very low or zero GWP indices. The most common natural fluids are R717 (ammonia), R744

Although the application of natural fluids in refrigeration systems is a worldwide trend, each fluid has its own characteristics and requires special care to be

• **Hydrocarbons:** They consist of a group of nontoxic gases with zero ODP and low GWP. They are environmentally friendly and have excellent thermodynamic properties, allowing good efficiency in similar or even better cooling

Because these refrigerant fluids are considered as flammable gas, hydrocarbon refrigeration systems must meet a number of safety guidelines. Typically, these gases are applied in small systems such as refrigerators or indirect systems and cooling secondary systems with other fluids (such as a CO2 cascade system). This

The most commonly used hydrocarbons in refrigeration are propane (R-290) and isobutane (R-600a). In addition to the GWP, the ozone depletion potential (ODP) is another parameter that compares the ozone layer depletion potential regarding the R-11 refrigerant, which is assigned the value 1. This value is compared

Refrigerants can be classified as simple, which are not mixed with other fluids such as R-22, R-134a, and R-32 and natural or blend fluids, which are mixtures of fluids, such as R-410A. The blend fluids may also be azeotropic or non-azeotropic. And this is another classification of refrigerants, which divides them into two broad

• **Azeotropic mixtures:** In these types of mixtures, the components cannot be distilled off. The mixture evaporates and condenses as if it were a single substance. Its properties are totally different from those of its components. As an example, we have CFC/HFC-500, HCFC/CFC-501, and HCFC/CFC-502. For example, HCFC/CFC-501 is a mixture of 75% HCFC-22 with 25% CFC-12 on a mass basis. Azeotropic mixtures causing ozone layer depletion were no longer

manufactured in 1996 in developed countries.

*DOI: http://dx.doi.org/10.5772/intechopen.89119*

air conditioning.

pressures.

implanted.

*Low-temperature Technologies*

x.Be easy to detect.

viii.Having compatibility with the lubricating oil of the compressor.

global warming, and should not attack the ozone layer.

xii.Not posing a danger to the environment.

index ranging from 0.6 to 1.

their ODP ranges from 0.02 to 0.1 [15, 17].

freezers).

xiii.Be commercially available at a reasonable cost.

ix.Having adequate compatibility with the materials of the refrigeration system.

xi.In case of leakage, it should not attack or spoil food, should not contribute to

The refrigerant groups available in the Brazilian market are divided into [15, 16]:

• **CFCs (chlorofluorocarbons):** They are refrigerant fluids whose molecule is formed by the element's chlorine, fluorine, and carbon, for example, the fluids R-11, R-12, R-113, R-114, R-115, and R-502, among others. The lifetime of CFCs in the atmosphere ranges from 60 to 540 years, causing high depletion of the ozone layer. Most CFCs have an ozone layer depletion potential (ODP)

CFCs were no longer manufactured by industrialized countries in January 1996 and, with some exceptions, by developing countries. These fluids feature high ODP and high GWP. According to the Montreal Protocol, in 1996 these gases were banned from developed countries, and in 2010 they should be banned from developing countries such as Brazil, but these gases are still found in old refrigeration and air conditioning systems. These fluids are used in automotive air conditioners, commercial refrigeration, and home refrigeration (refrigerators and

• **Hydrochlorofluorocarbons (HCFCs):** In these refrigerants some chlorine atoms are replaced by hydrogen, as an example of these fluids, have it R-22, R-123, R-401A, and R-4012A. These fluids are used in climate control systems, window air conditioners, split air conditioners, self-containers, cold rooms, etc.

These gases represent the second generation of fluorinated gases and were the main alternative to CFCs. They have lower ODP, but the GWP still between 1000 and 5000, so they are a little less harmful to the environment than their CFC predecessors, considering the ozone depletion. HCFCs are not fully halogenated like CFCs. The atmospheric lifetime of HCFCs ranges from 2 to 22 years, and therefore

Currently, in Brazil, HCFC-22 or (R-22) has been the most commonly used refrigerant in air conditioning systems since the early 1990s. HCFCs have been used as transition fluids, and their restriction on use and manufacturing started in 2004. According to the Montreal Protocol, the elimination of HCFCs in developed countries is expected by 2030 and in Brazil by 2040. Nevertheless, some countries are already well advanced on their elimination. In the European Union the use of HCFCs was terminated in January 2010 and may still be used until January 2015 in

• **Hydrofluorocarbons (HFCs):** In these fluids all chlorine atoms are replaced by hydrogen, for example, R-134a, R-404A, R-407C, R-410A, etc. These fluids

**82**

some specific cases.

are used in automotive air conditioning systems, commercial refrigeration and domestic refrigeration (refrigerators and freezers), etc.

As there are no chlorine atoms in HFCs refrigerants, they do not cause ozone layer depletion. HFCs are expected to become the most widely used in air conditioning systems in the coming decades. These fluids can be said to represent the third generation of fluorinated gases that have zero ODP and median and high GWP values. Currently, HFCs are largely used in commercial refrigeration and residential air conditioning.

Although the application of natural fluids in refrigeration systems is a worldwide trend, each fluid has its own characteristics and requires special care to be implanted.

• **Hydrocarbons:** They consist of a group of nontoxic gases with zero ODP and low GWP. They are environmentally friendly and have excellent thermodynamic properties, allowing good efficiency in similar or even better cooling systems than HCFC and HFC fluids.

Because these refrigerant fluids are considered as flammable gas, hydrocarbon refrigeration systems must meet a number of safety guidelines. Typically, these gases are applied in small systems such as refrigerators or indirect systems and cooling secondary systems with other fluids (such as a CO2 cascade system). This ensures a low risk of fire if a leak occurs.

The most commonly used hydrocarbons in refrigeration are propane (R-290) and isobutane (R-600a). In addition to the GWP, the ozone depletion potential (ODP) is another parameter that compares the ozone layer depletion potential regarding the R-11 refrigerant, which is assigned the value 1. This value is compared to other types of fluids.

Refrigerants can be classified as simple, which are not mixed with other fluids such as R-22, R-134a, and R-32 and natural or blend fluids, which are mixtures of fluids, such as R-410A. The blend fluids may also be azeotropic or non-azeotropic. And this is another classification of refrigerants, which divides them into two broad categories, which are:

• **Azeotropic mixtures:** In these types of mixtures, the components cannot be distilled off. The mixture evaporates and condenses as if it were a single substance. Its properties are totally different from those of its components. As an example, we have CFC/HFC-500, HCFC/CFC-501, and HCFC/CFC-502. For example, HCFC/CFC-501 is a mixture of 75% HCFC-22 with 25% CFC-12 on a mass basis. Azeotropic mixtures causing ozone layer depletion were no longer manufactured in 1996 in developed countries.

• **Zeotropic or non-azeotropic mixtures:** In a zeotropic mixture, its components are separated by distillation process. Thus, the mixture evaporates and condenses at different temperatures. Examples of such fluid types are R-400 and R-401A/B/C. Currently, these are the most promising alternative refrigerants for retrofit in air conditioning and refrigeration systems.

The CFCs and HCFCs are used worldwide in a variety of applications. By the middle of 1980, about 1/3 of CFC consumption occurred in the United States (USA). In 1985, the consumption of these fluids was around 278 tons.

These fluids served industrial sectors of insulating foams, automotive air conditioning, refrigeration and residential air conditioning, and commercial and industrial and other products. The CFC-expanded insulating foams have been widely used in industrial processes. Of this total, 19% was used in automotive air conditioning and 5% in new refrigeration and air conditioning systems. According to ABRAVA the percentage of halogenated refrigerant consumption is as follows: 77% HCFC-22, 10% CFC-11, and 10% CFC-12 [14].

Synthetic refrigerants (CFC, HCFC, HFC, and HFO) are considered safer, simpler to handle, and cheaper; however, most of them present some types of environmental risks. The presence of chlorine in the composition of most synthetic fluids is what makes them harmful to the ozone layer. Fluids that do not have chlorine in their composition are considered ecological but still favor the greenhouse effect, so the group of HFOs represents the promising generation of synthetic fluids.

The natural fluids such as CO2, ammonia, and hydrocarbons are considered more complex and have a higher cost. In addition, they are considered highly flammable, and care should be taken to install the systems that will receive these fluids. They are recommended for low load operations such as vending machines and have good applicability at any temperature.

Ammonia, used in ammonia fluid R-717, is considered toxic and slightly flammable, has good thermodynamic characteristics, and should be used in systems combined with glycol (chiller system), or CO2 (cascade system), for example [18].

The fluids with behavior of one substance, known as simple fluids, are easier to work because they have well defined properties, can be carried gaseous or liquid loads and in case of leaks, composition still the same in the installation, the only change will be in the volume. Azeotropic blend fluids such as R-22, despite being mixtures, have simple fluid characteristics. Non-azeotropic substances (such as R-404A, which has R-125, 44%, R-143 to 52%, R134 to 4%) have fluids with different boiling points and do not mix perfectly, so do not mix well. Thus, do not behave like simple fluid.

The use of these types of refrigerant implies extra care, as in the case of leaks, the composition of the leaked fluid and the composition of the remaining fluid may be unknown requiring a new charge. There is also the characteristic of glide temperature, where the evaporation temperature is not constant.

All these substances used in air conditioning and refrigeration systems are classified by safety groups as defined by AHSRAE. The classification considers the flammability and toxicity of each substance, as shown in **Table 2**, which presents the safety classification according to ASHAE [16]. Each refrigerant group requires a set of safety procedures for their use, installation, and disposal. The refrigerants found in the CFC, HCFC, and HFC categories are mostly classified in group A1 as non-flammable and of low toxicity. They are safe but environmentally aggressive fluids.

HFO refrigerants are less environmentally friendly but are classified in group A2L, i.e., there is a low risk of spreading flames in the event of a leak, and therefore require some caution and safety devices in equipment using these types of refrigerants.

**85**

*An Experimental Study of Synthetics and Natural Refrigerants Gases*

Natural fluids, while an alternative more environmentally friendly, require a lot of care, and their facilities must follow the safety guidelines defined for each application. Propane and isobutane hydrocarbons are classified as highly flammable (group A3) while ammonia as highly toxic and low flammability (group B2L). Although carbon dioxide falls within group A1, it is a choking gas, so your systems

High flammability A3 B3 Low flammability A2 B2

Non-flammable A1 B1

A2L B2L

Low toxicity High toxicity

In a Refrigeration system, the refrigerant is contained within the equipment,

When a coolant leak in a refrigeration system and air conditioning, depending on the design and the refrigerant charge amount used in the system, choking

Most leaks in the air conditioning and refrigeration systems are related to maintenance aspects, from the use of poorly maintained, deteriorated or even inadequate components and equipment as well as precarious labor that only acts

In the refrigeration, the word "retrofit" has been used to designate the adaptations that are made to equipment that works with CFCs so that they can work with alternative fluids (HCFCs, HFCs), making them efficient, modern, and economical. Another solution is the alternative fluid line, also called "blends," which is a good alternative for converting equipment that is operating in the field as it requires minimal changes to the original system, and in most cases no compressor replace-

**Table 3** shows a comparison of the ODP, GWP, and ASHRAE safety ratings of

In the Brazilian market, as shown in **Table 3**, it is observed that the replacement of refrigerant fluid R-22 (HCFC) with R-410A (HFC) is occurring; however, it is worth noting that this substitution does not alter the potential for global

In a direct comparison, R-134a refrigerant (tetrafluoroethane) has similar physical and thermodynamic properties to R-12, but it has lower ozone depletion potential (ODP) due to the absence of chlorine and the shorter lifetime in the atmosphere (16 years versus 120 years for R012). This fluid has a 90% reduction in greenhouse potential when compared to R-12. In addition, it is non-flammable and nontoxic, has high thermal and chemical stability, has compatibility with the materials used, and has adequate physical and thermodynamic properties. In addition, the R-134a refrigerant is free of chlorine and therefore has good compatibility with elastomers. One of the consequences of this change is that during the maintenance process of the air conditioning and refrigeration equipment, the R-22 fluid is released to

According to the Brazilian Ministry of Environment (MMA), the most commonly used refrigerant in cooling and air conditioning is HCFC-22, accounting for 82% of consumption [15, 19]. Considering the indicators shown in **Table 3** and the

must follow a series of precautions to ensure the safety of the installation.

there is no direct contact between users and the refrigerant.

problems may occur in people or product contamination.

when problems occur.

ment is required [19].

nature, without any kind of control.

some refrigerants.

warming.

*DOI: http://dx.doi.org/10.5772/intechopen.89119*

*Source: ASHRAE Fundamentals [16].*

*ASHAE safety classification.*

**Table 2.**

#### *An Experimental Study of Synthetics and Natural Refrigerants Gases DOI: http://dx.doi.org/10.5772/intechopen.89119*

#### **Table 2.**

*Low-temperature Technologies*

• **Zeotropic or non-azeotropic mixtures:** In a zeotropic mixture, its components are separated by distillation process. Thus, the mixture evaporates and condenses at different temperatures. Examples of such fluid types are R-400 and R-401A/B/C. Currently, these are the most promising alternative refriger-

The CFCs and HCFCs are used worldwide in a variety of applications. By the middle of 1980, about 1/3 of CFC consumption occurred in the United States

Synthetic refrigerants (CFC, HCFC, HFC, and HFO) are considered safer, simpler to handle, and cheaper; however, most of them present some types of environmental risks. The presence of chlorine in the composition of most synthetic fluids is what makes them harmful to the ozone layer. Fluids that do not have chlorine in their composition are considered ecological but still favor the greenhouse effect, so

the group of HFOs represents the promising generation of synthetic fluids.

perature, where the evaporation temperature is not constant.

The natural fluids such as CO2, ammonia, and hydrocarbons are considered more complex and have a higher cost. In addition, they are considered highly flammable, and care should be taken to install the systems that will receive these fluids. They are recommended for low load operations such as vending machines and have

Ammonia, used in ammonia fluid R-717, is considered toxic and slightly flammable, has good thermodynamic characteristics, and should be used in systems combined with glycol (chiller system), or CO2 (cascade system), for example [18]. The fluids with behavior of one substance, known as simple fluids, are easier to work because they have well defined properties, can be carried gaseous or liquid loads and in case of leaks, composition still the same in the installation, the only change will be in the volume. Azeotropic blend fluids such as R-22, despite being mixtures, have simple fluid characteristics. Non-azeotropic substances (such as R-404A, which has R-125, 44%, R-143 to 52%, R134 to 4%) have fluids with different boiling points and do not mix perfectly, so do not mix well. Thus, do not behave like simple fluid. The use of these types of refrigerant implies extra care, as in the case of leaks, the composition of the leaked fluid and the composition of the remaining fluid may be unknown requiring a new charge. There is also the characteristic of glide tem-

All these substances used in air conditioning and refrigeration systems are classified by safety groups as defined by AHSRAE. The classification considers the flammability and toxicity of each substance, as shown in **Table 2**, which presents the safety classification according to ASHAE [16]. Each refrigerant group requires a set of safety procedures for their use, installation, and disposal. The refrigerants found in the CFC, HCFC, and HFC categories are mostly classified in group A1 as non-flammable and of low toxicity. They are safe but environ-

HFO refrigerants are less environmentally friendly but are classified in group A2L, i.e., there is a low risk of spreading flames in the event of a leak, and therefore require some caution and safety devices in equipment using these types of

These fluids served industrial sectors of insulating foams, automotive air conditioning, refrigeration and residential air conditioning, and commercial and industrial and other products. The CFC-expanded insulating foams have been widely used in industrial processes. Of this total, 19% was used in automotive air conditioning and 5% in new refrigeration and air conditioning systems. According to ABRAVA the percentage of halogenated refrigerant consumption is as follows:

ants for retrofit in air conditioning and refrigeration systems.

(USA). In 1985, the consumption of these fluids was around 278 tons.

77% HCFC-22, 10% CFC-11, and 10% CFC-12 [14].

good applicability at any temperature.

**84**

refrigerants.

mentally aggressive fluids.

*ASHAE safety classification.*

Natural fluids, while an alternative more environmentally friendly, require a lot of care, and their facilities must follow the safety guidelines defined for each application. Propane and isobutane hydrocarbons are classified as highly flammable (group A3) while ammonia as highly toxic and low flammability (group B2L). Although carbon dioxide falls within group A1, it is a choking gas, so your systems must follow a series of precautions to ensure the safety of the installation.

In a Refrigeration system, the refrigerant is contained within the equipment, there is no direct contact between users and the refrigerant.

When a coolant leak in a refrigeration system and air conditioning, depending on the design and the refrigerant charge amount used in the system, choking problems may occur in people or product contamination.

Most leaks in the air conditioning and refrigeration systems are related to maintenance aspects, from the use of poorly maintained, deteriorated or even inadequate components and equipment as well as precarious labor that only acts when problems occur.

In the refrigeration, the word "retrofit" has been used to designate the adaptations that are made to equipment that works with CFCs so that they can work with alternative fluids (HCFCs, HFCs), making them efficient, modern, and economical. Another solution is the alternative fluid line, also called "blends," which is a good alternative for converting equipment that is operating in the field as it requires minimal changes to the original system, and in most cases no compressor replacement is required [19].

**Table 3** shows a comparison of the ODP, GWP, and ASHRAE safety ratings of some refrigerants.

In the Brazilian market, as shown in **Table 3**, it is observed that the replacement of refrigerant fluid R-22 (HCFC) with R-410A (HFC) is occurring; however, it is worth noting that this substitution does not alter the potential for global warming.

In a direct comparison, R-134a refrigerant (tetrafluoroethane) has similar physical and thermodynamic properties to R-12, but it has lower ozone depletion potential (ODP) due to the absence of chlorine and the shorter lifetime in the atmosphere (16 years versus 120 years for R012). This fluid has a 90% reduction in greenhouse potential when compared to R-12. In addition, it is non-flammable and nontoxic, has high thermal and chemical stability, has compatibility with the materials used, and has adequate physical and thermodynamic properties. In addition, the R-134a refrigerant is free of chlorine and therefore has good compatibility with elastomers. One of the consequences of this change is that during the maintenance process of the air conditioning and refrigeration equipment, the R-22 fluid is released to nature, without any kind of control.

According to the Brazilian Ministry of Environment (MMA), the most commonly used refrigerant in cooling and air conditioning is HCFC-22, accounting for 82% of consumption [15, 19]. Considering the indicators shown in **Table 3** and the

#### **Table 3.**

*Comparison of available refrigerants for air conditioning and refrigeration systems.*

properties listed above, it is important to realize that most refrigerants do not meet the requirements for commercial use in order to comply with Brazilian and worldwide legislation.

The scenario of replacing the R-22 in the refrigeration and air conditioning industry points to a number of alternative fluids. In this context, manufacturers in the refrigeration and air conditioning industry are looking for solutions that meet their goals without neglecting good performance.

According to ABRAVA [14], **Table 4** presents the suggestions of alternative fluids to the use of R-22 according to each application:

In a survey by the members of the UFPA Resfriar Project, in the metropolitan region of Belém do Pará, along with companies that work with the sale, installation, and maintenance of HVAC systems, more than 95% of people involved with the services did not have either training courses or were qualified to develop the services.

In Brazil, it is possible to observe that, in the practical activities, during the maintenance processes, the people qualified for the development of installation,

**87**

these acts.

warming.

**4. Test bench type chiller**

system has been described.

**4.1 Theoretical fundamentals**

*An Experimental Study of Synthetics and Natural Refrigerants Gases*

Air conditioners and heat pumps Residential/small commercial air

**Equipment types Usual application Main refrigerant**

Multi-split systems Residential/commercial R-407C or R-410A Large air conditioning systems Commercial R-134a or R-410A Air condensing chillers Central systems R-134a or R-410A Water condensing chillers Central systems R-134a Commercial refrigeration Commercial R-134a, R-404A,

conditioning

Commercial R-410A

Industrial/transport R -134a or ammonia

Window air conditioners (WAC) Residential R-410A

**substitutes**

R-410A

R-410A, or R-507A

operation, and maintenance activities of air conditioning and refrigeration systems, called in Brazil as "refrigeration professional," are the people who, not necessarily, are technicians of maintenance of air conditioning and refrigeration

It was found that during the development of the analysis and maintenance services, these people either lack adequate equipment, such as a vacuum pump or a refrigerant recovery unit, or lack of knowledge, or because they could not afford to purchase such basic equipment and instruments required to perform the service and release the refrigerants from the equipment to the local environment. Besides that, they always have a recharge for normal system operation and, in many cases, do not have a basic analysis or concern about the consequences of

This common and uncontrolled practice releases thousands of kilograms of refrigerant fluids per year, to the environment, contributing significantly to global

In this topic, the theoretical foundations about vapor compression type cooling systems, with synthetic and natural fluids, necessary for the understanding about the experimental apparatus used are initially approached. After that, the experimental apparatus developed in the ClimatCont laboratory to simulate a chiller

Some scientific studies specifically dedicated to the comparison of natural fluids with the most common synthetic ones, such as R-22 fluid, have been carried out and published. The research conducted by Park and Jung's [20] related the replacement

systems and, in many cases, are called "curious".

*Alternative refrigerants for R-22 refrigerant according to your applications.*

*DOI: http://dx.doi.org/10.5772/intechopen.89119*

Hot and cold air conditioners (multi-split systems)

Industrial and transport

refrigeration

**Table 4.**

*Source: ABRAVA [14].*

*An Experimental Study of Synthetics and Natural Refrigerants Gases DOI: http://dx.doi.org/10.5772/intechopen.89119*

#### **Table 4.**

*Low-temperature Technologies*

R-502/CFC blend R-115 (51%), R-22

R-410a/AZ-20 R-32 (50%), R-125

R-507/AZ-50 R-125 (50%), R-143a

**CFCs**

**HCFCs**

**HFCs**

**HFOs**

**Natural refrigerants (NRs)**

*Source: ASHRAE Fundamentals [16].*

**86**

services.

wide legislation.

**Table 3.**

properties listed above, it is important to realize that most refrigerants do not meet the requirements for commercial use in order to comply with Brazilian and world-

**Number/name Formula ODP GWP ASHAE safety**

R-11/trichlorofluoromethane CCl3F 1 4000 A1 R-12/dichlorodifluoromethane CCl2F2 1 8500 A1

R-22/chlorodifluoromethane CHClF2 0.055 1700 A1 R-123/dichlorotrifluoroethane C2HCl2F3 0.02 93 A1

R-32/difluoromethane CH2F2 0.0 650 A1 R-134a/tetrafluoroethane C2H2F4 0.0 1300 A1

R-1234yf C3H2F4 0.0 4 A2L R-1234ze C3H2F4 0.0 6 A2L R-218/perfluoropropane C3F8 0.0 7000 A2L

R-290/propane, Care 40 C3H8 0.0 ~5 A3 R-600a/isobutane, Care 10 C4H10 0.0 ~5 A3 R-717/ammonia NH3 0.0 <1 B2L R-718/water H2O 0.0 <1 A1

(50%)

(50%)

(49%)

**classification**

0.23 5590 A1

0.0 1730 A1

0.0 3300 A1

The scenario of replacing the R-22 in the refrigeration and air conditioning industry points to a number of alternative fluids. In this context, manufacturers in the refrigeration and air conditioning industry are looking for solutions that meet

According to ABRAVA [14], **Table 4** presents the suggestions of alternative

In a survey by the members of the UFPA Resfriar Project, in the metropolitan region of Belém do Pará, along with companies that work with the sale, installation, and maintenance of HVAC systems, more than 95% of people involved with the services did not have either training courses or were qualified to develop the

In Brazil, it is possible to observe that, in the practical activities, during the maintenance processes, the people qualified for the development of installation,

their goals without neglecting good performance.

fluids to the use of R-22 according to each application:

*Comparison of available refrigerants for air conditioning and refrigeration systems.*

*Alternative refrigerants for R-22 refrigerant according to your applications.*

operation, and maintenance activities of air conditioning and refrigeration systems, called in Brazil as "refrigeration professional," are the people who, not necessarily, are technicians of maintenance of air conditioning and refrigeration systems and, in many cases, are called "curious".

It was found that during the development of the analysis and maintenance services, these people either lack adequate equipment, such as a vacuum pump or a refrigerant recovery unit, or lack of knowledge, or because they could not afford to purchase such basic equipment and instruments required to perform the service and release the refrigerants from the equipment to the local environment. Besides that, they always have a recharge for normal system operation and, in many cases, do not have a basic analysis or concern about the consequences of these acts.

This common and uncontrolled practice releases thousands of kilograms of refrigerant fluids per year, to the environment, contributing significantly to global warming.


**Ros Whelan 1,\*, Eric Prince 1,2,3, Ahmed Gilani 4 and Todd Hankinson 1,2,3**

Received: 2 January 2020; Accepted: 12 February 2020; Published: 14 February 2020

**Abstract:** Pediatric Adamantinomatous Craniopharyngiomas (ACPs) are histologically benign brain tumors that often follow an aggressive clinical course. Their suprasellar location leaves them in close proximity to critical neurological and vascular structures and often results in significant neuroendocrine morbidity. Current treatment paradigms, involving surgical resection and radiotherapy, confer significant morbidity to patients and there is an obvious need to discover effective and safe alternative treatments. Recent years have witnessed significant efforts to fully detail the genomic, transcriptomic and proteomic make-up of these tumors, in an attempt to identify potential therapeutic targets. These studies have resulted in ever mounting evidence that inflammatory processes and the immune response play a critical role in the pathogenesis of both the solid and cystic portion of ACPs. Several inflammatory and immune markers have been identified in both the cyst fluid and solid tumor tissue of ACP. Due to the existence of effective agents that target them, IL-6 and immune checkpoint inhibitors seem to present the most likely immediate candidates for clinical trials of targeted immune-related therapy in ACP. If effective, such agents may result in a paradigm shift in treatment that ultimately reduces morbidity and results in better outcomes for our patients.

**Keywords:** craniopharyngioma; inflammation; checkpoint inhibitors; Interleukin-6


**5. Relationship between serum prolactin concentration and adverse events**

This is a complex question that remains totally unanswered for the potential longer term sequelae but can be partially addressed for short-term adverse events. There would seem to be two potential associations. Firstly, a chronic prolactin elevation that reaches a cumulative threshold over a longer term and secondly, a peak prolactin level that requires a trigger threshold to initiate pathology. Levels <1000 mIU/L are associated with decreased libido and infertility, 1000-1600 mIU/L with oligomenorrhoea, and >2000 mIU/L with amenorrhea and hypogonadism (Peveler et al, 2008). Hypogonadism is the main driver for bone mineral density loss and fractures although the possibility exists that prolactin may have a direct osteoclastic effect. Data on longer term prolactin levels tend not to report the associated changes in sex hormones making interpretation complex. The topic has, however, been reviewed (Bushe et al, 2008) and in cross-sectional prevalence studies that report bone mineral density loss in association with typicals or risperidone over 8-21 years, the mean cohort values ranged 908-3024 mIU/L (Bushe et al, 2010). These levels are common and are reached quickly in patients treated with risperidone and amisulpride (Bushe and Shaw 2007; Bushe et al, 2008). A small case series of patients receiving paliperidone reported hyperprolactinaemia within 3 weeks with levels ranging from 1500-3996 mIU/L (Skopek et al, 2010). Prolactin levels related to breast cancer in schizophrenia and bipolar disorder are unknown, however data are supportive of levels as low as 500 mIU/L being associated with an increased risk of breast cancer in the general population over the medium term (Tworoger and Hankinson 2006, Tworoger et al, 2007). However, it is critical to understand that whereas there is a strong link between prolactin and breast cancer in the general population, there are no data to address this topic in schizophrenia and bipolar disorder. In addition, breast cancer has very many aetiological factors that include social demographics, education, obesity and family history and the role of prolactin is simply not known.


2.**Can knowledge of the set of transitions that caused reaching its present state be considered as artificial consciousness?**

ChatGPT:

No, knowledge of the set of transitions that caused an FSA to reach its present state cannot be considered as artificial consciousness. Artificial consciousness refers to the theoretical concept of a machine or AI system possessing subjective experiences, awareness, self-awareness, or a sense of "being" similar to human consciousness.

The consciousness requirements posed by ChatGPT possibly derive from texts written by people erroneously expecting all these anthropomorphic properties that are inconceivable for a computer system using a general-purpose computer of current technology. These digital computers rely on very simple hardware, the so-called central processing unit (CPU).

No such properties could be attributed to a CPU, which is just an arithmetic processor augmented with a testing facility of the results of the calculations that control the execution flow of a program and some input-output facilities. A CPU can easily be described by an FSA.


**11. References**

252 Advanced Photonic Sciences

nonmagnetic material. It turned out that the numerically converged spin density was a minimal 1.35 x 10-4 *μB*/atom, showing that the proposed procedure is robust against

Fig. 25. The optical *μr* spectrum of Fe crystal obtained from the proposed procedure.

the imposed EM wave in such a way that actually results in the Fresnel equations.

powers. This kind of microscopic approaches are called "dipole engineering".

This chapter contains a clear, yet rigorous, picture as to how the real physical causes behind all these macroscopic optical phenomena – i.e., the microscopic electric and magnetic dipoleswork to come up with such macroscopic results. Both the electric and magnetic dipoles react to

In arriving at the more intuitive "scattering form" of the Fresnel equations, microscopic EMinduced physical electric and magnetic dipoles were rigorously employed as the source of electromagnetic waves by Doyle et al. Motivated by such an approach, the authors started to speculate how the incorporation of permanent dipoles might affect many macroscopic optical phenomena, e.g., the Brewster angle of a specific optical material. Among its predictions, the traditionally fixed Brewster angle of a specific material now not only becomes dependent on the density and orientation of incorporated permanent dipoles, but also on the incident light intensity (more precisely, the incident wave electric field strength). Further, two conjugated incident light paths would give rise to different refracted wave

Theoretical elaboration and then IR experiments on poled polyvinylidene fluoride (PVDF) films were conducted to verify the emergence of asymmetric reflections at varying incident angles, as well as the inverse dependence of reflectivity upon the impinging light intensity. In addition, experiments on dipole-engineered PVDF films show that by way of adding/reducing permanent dipole density and varying orientations, the aforementioned theoretical predictions can be evidenced unambiguously in the visible light range. Further, effective polarization density can be quantified from the above experiments subjected to different dipole engineering processes. As a result, the traditionally elliptic contour of a slanted two dimensional section of the refractive index ellipsoid now manifests symmetric

erroneous initial conditions.

**10. Conclusion**

**10**

*1Bulgaria 2Armenia*

**High Resolution Laser Spectroscopy of Cesium**

David Sarkisyan2, Dimitar Slavov1, Petko Todorov1 and Kapka Vaseva1

*2Institute for Physical Research, National Academy of Sciences of Armenia, Ashtarak*

High resolution laser spectroscopy of alkali vapor contained in conventional thermal optical cells with centimeter dimensions is widely used for various applications: among them wavelength references, atomic clocks, precise optical magnetometers, slow and stored light etc. For all these photonic sensors, the reduction of their dimensions is of significant importance. One of the main concerns is to keep the parameters of the photonic sensor when reducing its size. In this chapter are presented the obtained by authors experimental and theoretical results concerning high-resolution spectroscopy of Cs vapor layer with nanometric thickness. The thickness of the vapor layer varies from 100 nm to about 5000 nm. The practical importance of this study is accompanied by numerous new peculiarities of atomic spectra of 1 D confined atoms, when the nanometric dimension approaches the wavelength of the irradiating light. These peculiarities in the absorption and fluorescence

**2. Unique optical cells for confinement of Cs atomic layers with nanometric**

In this chapter, the high resolution laser spectroscopy is concerned of alkali vapor confined in unique optical cell with nanometric thickness [Sarkisyan, 2001], further on called Extremely Thin Cell (ETC). The transversal and longitudinal dimensions of such cell (Fig.1) differ significantly. The distance between the high-quality ETC windows L varies from 100 nm to (1-3) μm. At the same time, the cell window diameter is about 2 cm (Fig.1b). Therefore, a strong spatial anisotropy is present for the time of interaction between atoms confined in the ETC and the laser radiation used for spectroscopy performed with such

Let us consider Cs atoms flying orthogonally to the cell windows (Fig.1a, atoms denoted by v┴), which average thermal velocity at room temperature is about 200 m/s. Those atoms

**1. Introduction**

**thickness**

optical cell.

spectra represent a basic importance as well.

**2.1 Main characteristics of atomic confinement**

**Vapor Layers with Nanometric Thickness**

Stefka Cartaleva1, Anna Krasteva1, Armen Sargsyan2,

*1Institute of Electronics, Bulgarian Academy of Sciences, Sofia*