**3. Result and discussion**

### **3.1 XRD result**

The XRD pattern of the Gd2O3 sample is shown in **Figure 3**. The diffraction patterns are well matched with standard JCPDS card no. 43-1015, indicating that the sample of Gd2O3 phosphor is in the pure monoclinic phase. The particle size was calculated by the Scherer formula [7] *D* = \_*k*

$$D = \frac{k\lambda}{\beta C \alpha \theta} \tag{1}$$

**81**

**Figure 4.**

*Gd2O3: A Luminescent Material*

of nano range.

**3.3 TEM result**

particle for both fuels [1, 2, 7].

**3.4 Energy dispersive X-ray analysis (EDX)**

*DOI: http://dx.doi.org/10.5772/intechopen.92310*

The signs that get from electron and sample interaction uncover data about the example including outer morphology, elemental composition, and crystalline structure and introduction of materials making up the example. The SEM is likewise fit for performing examinations of chose point areas on the example; this methodology is particularly valuable in subjectively or semi-quantitatively deciding synthetic structures. **Figure 4** demonstrates the SEM micrographs of the Gd2O3 arranged by combustion synthesis method utilizing urea and glycine as a fuel. The black and white SEM micrograph of the prepared powder indicates that all the particles are looking like agglomerated in homogeneously in different shapes/sizes of the order

Transmission electron microscopy (TEM) is an imaging system whereby a light emission is engaged onto an example making a broadened form show up on a fluorescent screen or layer of photographic film or to be distinguished by a CCD camera. The main commonsense transmission electron magnifying instrument was built by Albert Prebus and Lames Hillier at the college of Toronto in 1938 utilizing ideas grew before by Max Knoll and Ernst Ruska. The particle size of the system was determined by high resolution transmission electron microscopy (HRTEM). It is a phase differentiated imaging process because the image formed is due to the scattering of electron waves through a thin surface. In **Figure 5**, HRTEM micrograph demonstrates a Gd2O3 nanocrystal with a width of 8–10 nm seen all through the

Elemental investigation of the prepared samples is generally determined by EDX analysis. The spectrum shows the relation between the X-ray energy, which lies in between 10 and 20 eV, and the number of counts per channel by a plot between them in X and Y axes, respectively. An X-ray line is expanded by the reaction of the framework, delivering a Gaussian profile. Energy resolution is characterized as the full width of the crest at half maximum height (FWHM). In the spectrum of both the Gd2O3 samples, intense peak of Gd and O is present, which confirms the formation of Gd2O3 phosphor (**Figure 6**). For EDX analysis, the entire area of the black and white SEM micrographs was analyzed with EDX mapping and spectrum. The

*Scanning electron microscope image of Gd2O3 phosphor: (A) glycerin fuel and (B) urea fuel.*

where *D* is the volume weighted crystallite size, *k* is the shape factor (0.9), *λ* is the wavelength of Cu Kα1 radiation, *β*hkl is the instrumental corrected integral breadth of the reflection (in radians) located at 2*θ*, and *θ* is the angle of reflection (in degrees) utilized to relate the crystallite size to the line broadening. The average crystallite size of Gd2O3 nanoparticles was found to be in the range of 8–10 nm for both the fuels. No impurity peaks or other possible phases of Gd2O3 were observed. Further, the strong and sharp diffraction peaks confirm the high crystallinity of the products.

### **3.2 Surface morphology**

The scanning electron microscopy (SEM) was utilized as a focused ray of high energy electrons to produce an assortment of signs at the crystalline surface.

**Figure 3.** *XRD patterns of Gd2O3: (A) glycerin fuel and (B) urea fuel.*


3.2.2. Streamlines

boundary layer.

As for the wingsails with different rotating axis positions of the flap at α = 15◦ and *d* = 15◦ , the streamlines on the mid-span of wingsail are depicted in Figure 15. It can be found that a small separation vortex appears in the wake of the wing and a large separation vortex appears in the regions over the suction surface of the flap at Xr = 90%. *J. Mar. Sci. Eng.* **2019**, *7*, x FOR PEER REVIEW 11 of 16

**Figure 15.** Streamlines at mid-span of the wingsail at (a) Xr=75% (b) Xr=85% (c) Xr=90% and (d) Xr=95% with *α*=15°, *d*=15°. **Figure 15.** Streamlines at mid-span of the wingsail at (**a**) Xr = 75% (**b**) Xr = 85% (**c**) Xr = 90% and (**d**) Xr = 95% with α = 15◦ , *d* = 15◦ .

Figure 16 shows the limiting streamline and static pressure contours on suction surface for two-element wingsail at different rotating axis positions of the flap. With the backward movement of the rotating axis position of the flap, the flow separation of the suction surface of the wing expands from the blade root to the top, and the return area becomes larger for the low camber wingsail. The flow separation line appears on the suction surface of the wing at Xr=85%. It explains that the forward movement of the rotating axis position of the flap increases the fluid flow through the slot, delays the flow separation of the suction surface of the wing, or delays stall of the wingsail. An obvious separation helix appears on the suction surface of the wing at Xr=95%, which indicates that the vortex has been formed. When the rotating axis position of the flap is moves backward from 90% to 95%, the flow separation on the suction surface of flap disappears. We guess the fluid flowing through the smaller gap does not supplement the wake of the wing, but flows along the flap Figure 16 shows the limiting streamline and static pressure contours on suction surface for two-element wingsail at different rotating axis positions of the flap. With the backward movement of the rotating axis position of the flap, the flow separation of the suction surface of the wing expands from the blade root to the top, and the return area becomes larger for the low camber wingsail. The flow separation line appears on the suction surface of the wing at Xr = 85%. It explains that the forward movement of the rotating axis position of the flap increases the fluid flow through the slot, delays the flow separation of the suction surface of the wing, or delays stall of the wingsail. An obvious separation helix appears on the suction surface of the wing at Xr = 95%, which indicates that the vortex has been formed. When the rotating axis position of the flap is moves backward from 90% to 95%, the flow separation on the suction surface of flap disappears. We guess the fluid flowing through the smaller gap does not supplement the wake of the wing, but flows along the flap boundary layer.

*J. Mar. Sci. Eng.* **2019**, *7*, x FOR PEER REVIEW 12 of 16

(**e**) Xr = 95%

**Figure 16.** Limiting streamline and static pressure contours on suction surface for the two-element wingsail at (a) Xr=75% (b) Xr=80% (c) Xr=85% (d) Xr=90% and (e) Xr=95% with *α*=15°, d=15°. **Figure 16.** Limiting streamline and static pressure contours on suction surface for the two-element wingsail at (**a**) Xr = 75% (**b**) Xr = 80% (**c**) Xr = 85% (**d**) Xr = 90% and (**e**) Xr = 95% with α = 15◦ , d = 15◦ .

#### 3.2.3. Velocity Magnitude Contours 3.2.3. Velocity Magnitude Contours

It can be seen from Figure 17 that the suction surface of the wing has a large flow separation at *α*=15° with low camber. At Xr=85%, the fluid flowing through the slot complements the flow It can be seen from Figure 17 that the suction surface of the wing has a large flow separation at α = 15◦ with low camber. At Xr = 85%, the fluid flowing through the slot complements the flow separation of the wing wake and the flap suction surface. There is no vortex in the mid-span of the wingsail. The slot jet can be observed clearly at Xr = 90%. As a result of the reduced slot width due to the rotating axis position of the flap backward, the slot jet only divides the vortex of the wing wake and there is a large-scale flow separation on the suction surface of the flap, which causes deep stall of the

experiment in 2016.

flap. This phenomenon has also been observed and described in Biber [27] and Chapin [18]. Because of the smaller slot width at Xr = 95%, the slot jet only flows along the boundary layer of the flap, which has little effect on the separation flow of the wing wake. If the slot is further reduced or not set, the flap setting may aggravate the separation of the wing wake, such as the research of the hybrid sail designed by Qiao Li [14]. However, the forward movement of the rotating axis position of the flap is limited by the flap deflection angle. As shown in Figure 18, when the rotating axis position of the flap moves forward from 90% to 85% at α= 6 ◦ , the large-scale flow separation occurs on the suction surface of the flap, as the phenomenon seen by Fiumara [19] in the two-element sail experiment in 2016. the flap. This phenomenon has also been observed and described in Biber [27] and Chapin [18]. Because of the smaller slot width at Xr = 95%, the slot jet only flows along the boundary layer of the flap, which has little effect on the separation flow of the wing wake. If the slot is further reduced or not set, the flap setting may aggravate the separation of the wing wake, such as the research of the hybrid sail designed by Qiao Li [14]. However, the forward movement of the rotating axis position of the flap is limited by the flap deflection angle. As shown in Figure 18, when the rotating axis position of the flap moves forward from 90% to 85% at *α*= 6°, the large-scale flow separation occurs on the suction surface of the flap, as the phenomenon seen by Fiumara [19] in the two-element sail experiment in 2016. and there is a large-scale flow separation on the suction surface of the flap, which causes deep stall of the flap. This phenomenon has also been observed and described in Biber [27] and Chapin [18]. Because of the smaller slot width at Xr = 95%, the slot jet only flows along the boundary layer of the flap, which has little effect on the separation flow of the wing wake. If the slot is further reduced or not set, the flap setting may aggravate the separation of the wing wake, such as the research of the hybrid sail designed by Qiao Li [14]. However, the forward movement of the rotating axis position of the flap is limited by the flap deflection angle. As shown in Figure 18, when the rotating axis position of the flap moves forward from 90% to 85% at *α*= 6°, the large-scale flow separation occurs on the suction surface of the flap, as the phenomenon seen by Fiumara [19] in the two-element sail

*J. Mar. Sci. Eng.* **2019**, *7*, x FOR PEER REVIEW 13 of 16

separation of the wing wake and the flap suction surface. There is no vortex in the mid-span of the wingsail. The slot jet can be observed clearly at Xr = 90%. As a result of the reduced slot width due to

separation of the wing wake and the flap suction surface. There is no vortex in the mid-span of the

*J. Mar. Sci. Eng.* **2019**, *7*, x FOR PEER REVIEW 13 of 16

and there is a large-scale flow separation on the suction surface of the flap, which causes deep stall of

the rotating axis position of the flap backward, the slot jet only divides the vortex of the wing wake

Figure 17. Velocity magnitude contours at mid-span of wingsail at (a) Xr= 85% (b) Xr= 90% and (c)Xr= 95% with α=15°,d=15° **Figure 17.** Velocity magnitude contours at mid-span of wingsail at (**a**) Xr = 85% (**b**) Xr = 90% and (**c**)Xr = 95% with α = 15◦ , d = 15◦ (**c**) Xr = 95% Figure 17. Velocity magnitude contours at mid-span of wingsail at (a) Xr= 85% (b) Xr= 90% and (c)Xr= 95% with α=15°,d=15°

(**b**) Xr = 90% **Figure 18.** *Cont.*

*J. Mar. Sci. Eng.* **2019**, *7*, x FOR PEER REVIEW 14 of 16

**Figure 18.** Velocity magnitude contours at mid-span of wingsail at (a) Xr= 85% (b) Xr= 90% and (c)Xr= 95% with α=6°,d=25°. **Figure 18.** Velocity magnitude contours at mid-span of wingsail at (**a**) Xr = 85% (**b**) Xr = 90% and (**c**) Xr = 95% with α = 6 ◦ , d = 25◦ .

#### **4. Conclusions 4. Conclusions**

**References**

By studying the influence of flap geometric parameters on the aerodynamic characteristics of two-element wingsail under steady and unsteady conditions, two-dimensional and three-dimensional related parameters were simulated using the same Reynolds number (*Re* =5×105). By studying the influence of flap geometric parameters on the aerodynamic characteristics of two-element wingsail under steady and unsteady conditions, two-dimensional and three-dimensional related parameters were simulated using the same Reynolds number (*Re* = 5 × 105 ).

The 2D simulation results show that, when the rotating axis position of the flap is located at 85% of the wing chord, the thickening flap leads to an increase of the leading-edge radius which decreases the pressure coefficient suction peak and has postponed the stall of the wingsail for high camber. It reflects the nonlinear coupling effect between wingsail camber and flap thickness. When the rotating axis of the flap is located at the 75% of the wing chord, the stall angle is delayed with the increase of the flap deflection angle at low camber. When selecting the geometric parameters of the flap, factors such as the position of the flap rotation axis, the flap deflection angle, and the flap thickness need to be considered comprehensively. The 2D simulation results show that, when the rotating axis position of the flap is located at 85% of the wing chord, the thickening flap leads to an increase of the leading-edge radius which decreases the pressure coefficient suction peak and has postponed the stall of the wingsail for high camber. It reflects the nonlinear coupling effect between wingsail camber and flap thickness. When the rotating axis of the flap is located at the 75% of the wing chord, the stall angle is delayed with the increase of the flap deflection angle at low camber. When selecting the geometric parameters of the flap, factors such as the position of the flap rotation axis, the flap deflection angle, and the flap thickness need to be considered comprehensively.

The 3D simulation mainly studies the influence of the flap rotating axis position and the flap deflection angle on the stall characteristics of the wingsail. When stall has not yet occurred with low camber, the rotating axis position of the flap has little effect on the lift coefficient, while stall has occurred, the lift coefficient increases first and then reduces with the rotating axis position of the flap moving backward. The flow separation of the suction surface of the wing expands from the root to the top and the return area becomes larger, especially from the 80% to the 85%, the lift coefficient drops suddenly. This is caused by the flow separation between the wing wake and the flap suction surface. At high camber with AOA=6°, the lift coefficient always increases with the position of the flap rotation axis, especially from 85% to 95%, the lift coefficient suddenly rises, which is caused by the disappearance of large-scale flow separation of the flap suction surface. The 3D simulation mainly studies the influence of the flap rotating axis position and the flap deflection angle on the stall characteristics of the wingsail. When stall has not yet occurred with low camber, the rotating axis position of the flap has little effect on the lift coefficient, while stall has occurred, the lift coefficient increases first and then reduces with the rotating axis position of the flap moving backward. The flow separation of the suction surface of the wing expands from the root to the top and the return area becomes larger, especially from the 80% to the 85%, the lift coefficient drops suddenly. This is caused by the flow separation between the wing wake and the flap suction surface. At high camber with AOA = 6 ◦ , the lift coefficient always increases with the position of the flap rotation axis, especially from 85% to 95%, the lift coefficient suddenly rises, which is caused by the disappearance of large-scale flow separation of the flap suction surface.

Therefore, the slot width is an important factor affecting the flow separation of the wing wake and the suction surface of the flap, where size is affected by the rotating axis position of the flap and the flap deflection angle. When the flap deflection angle is adjusted to obtain a large lift coefficient, the restriction of the rotating axis position of the flap must be considered to ensure a reasonable stall angle range. Therefore, the slot width is an important factor affecting the flow separation of the wing wake and the suction surface of the flap, where size is affected by the rotating axis position of the flap and the flap deflection angle. When the flap deflection angle is adjusted to obtain a large lift coefficient, the restriction of the rotating axis position of the flap must be considered to ensure a reasonable stall angle range.

**Author Contributions:** conceptualization, C.L. and H.W.; investigation, C.L. and H.W.; methodology, C.L. and P.S.; software, C.L.; writing—original draft preparation, C.L.; writing—review and editing, H.W.; supervision, P.S. **Author Contributions:** Conceptualization, C.L. and H.W.; investigation, C.L. and H.W.; methodology, C.L. and P.S.; software, C.L.; writing—original draft preparation, C.L.; writing—review and editing, H.W.; supervision, P.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by National Natural Science Foundation of China,51709165, Research **Funding:** This research was funded by National Natural Science Foundation of China, 51709165, Research Funds of Jiangsu Maritime Institute, 014070, kjcx-1907.

Funds of Jiangsu Maritime Institute,014070, kjcx-1907. **Conflicts of Interest:** The authors declare no conflict of interest. **Conflicts of Interest:** The authors declare no conflict of interest.

2. Available online: http://www.sohu.com/a/275284498\_100091571 (accessed on 14 November 2018).

1. Ishihara, M., Watanabe, T., Shimizu, K. Yoshimi, K., Namura, H. Prospect of sailequipped motor ship as assessed from experimental ship Daioh. *Proceedings of the Shipboard Energy Conservation Symposium*; Society

of Naval Architects and Marine Engineers, New York, America 1980; pp. 181–198.

*J. Mar. Sci. Eng.* **2020**, *8*, 333


**4. Supporting teachers to evaluate pedagogy**

The discussion so far, supported by the work of Bourdieu and Giddens has identified the stability of classroom practices. Teachers tend to maintain their practice from 1 year to the next and from one class to the next, unaware of the unintended consequences of their actions and institutional routines. Supporting the evaluation of their pedagogy is essential if teachers are to become reflective practitioners.

It is the interaction of the five factors described; habitus, teacher motivation, ontological security, routinization, and time and place that either promote or inhibit teachers' to reflectively evaluate and select approaches that will be most useful for their students. For example, a teacher may be motivated to change teaching practice to more effectively engage his or her students in their learning. However, if the teacher is unaware of routinization or is ontologically insecure, it is unlikely that the changes to pedagogy required will be identified. The capacity of teachers to critically evaluate the pedagogy they use in their classrooms is linked to their knowledgeability.

Giddens suggests that knowledgeability is a person's understanding of the rules and norms that make up social structures. In the case of teachers this will be both the rules and norms of the community and also at a professional level the rules and norms of teaching and the school in which they work. In schools, many of these will be implicit and only understood through experience and interaction with others. A teacher, student or parents' knowledgeability about a school will be their understanding of the conditions in the school and how these influences the way people act. For example, if a school has a long history or being involved in the arts, students' involvement in the annual school drama production is highly valued. Awareness of this school norm would help a new teacher to the school understand the enthusiasm of student participation in the performing arts. In contrast teachers can be puzzled and frustrated due to a lack of knowledge about conditions in the school. For example, if the local community the school serves is experiencing economic and social hardship students may be dealing with many stresses in their home life that is reflected in off task behaviour in the classroom. If teachers are unaware of these situation actions in class that would normally support student engagement may prove ineffective.

It is the difference between what is known and not known that can lead to unintended consequences of action by teachers. Expanding teachers' knowledgeability occurs when a person becomes aware of the conditions that lead to unintended consequences. This means that expanding teachers' knowledgeability has the potential to uncover routines supported by the tacit knowledge that undermined student achievement.

Burridge, Hooley and Neil have proposed that knowledgeability is linked to the concept, 'frames of practice'.  Teachers' frames of practice develop through experience, reflection and study where novice teachers will have less complex and established frames compared to an experienced teacher. As frames of practice become established and stable they become part of the tacit knowledge of the practical conscious. Experienced teachers will draw on these reflexively to manage their classrooms. This allows the discursive conscious to be attentive to students learning needs and unexpected or unusual happenings in the classroom. As teachers understanding of teaching grows so does the complexity of their frames of practice and with more complex frames, teachers become more competent to deal with new problems or situations. **Figure 1** illustrates this growth of new frames of practice, with more frames being developed and becoming stable in the practical consciousness as the teacher's understanding grows. These new frames are developed through reflection on teaching experience identifying previously unacknowledged conditions that led to unintended consequences of action.

In the centre of **Figure 1** are examples of frames of practice that a teacher may draw on when managing a class. The frames are connected as different frames interacted to inform a

**Figure 1.** Development of frames of practice.

pedagogy. They choose an approach they have found effective in one situation and research how it might apply to different subject areas. Being provided time and space for these discussions

The discussion so far, supported by the work of Bourdieu and Giddens has identified the stability of classroom practices. Teachers tend to maintain their practice from 1 year to the next and from one class to the next, unaware of the unintended consequences of their actions and institutional routines. Supporting the evaluation of their pedagogy is essential if teachers are

It is the interaction of the five factors described; habitus, teacher motivation, ontological security, routinization, and time and place that either promote or inhibit teachers' to reflectively evaluate and select approaches that will be most useful for their students. For example, a teacher may be motivated to change teaching practice to more effectively engage his or her students in their learning. However, if the teacher is unaware of routinization or is ontologically insecure, it is unlikely that the changes to pedagogy required will be identified. The capacity of teachers to critically evaluate the pedagogy they use in their classrooms is linked to their knowledgeability. Giddens suggests that knowledgeability is a person's understanding of the rules and norms that make up social structures. In the case of teachers this will be both the rules and norms of the community and also at a professional level the rules and norms of teaching and the school in which they work. In schools, many of these will be implicit and only understood through experience and interaction with others. A teacher, student or parents' knowledgeability about a school will be their understanding of the conditions in the school and how these influences the way people act. For example, if a school has a long history or being involved in the arts, students' involvement in the annual school drama production is highly valued. Awareness of this school norm would help a new teacher to the school understand the enthusiasm of student participation in the performing arts. In contrast teachers can be puzzled and frustrated due to a lack of knowledge about conditions in the school. For example, if the local community the school serves is experiencing economic and social hardship students may be dealing with many stresses in their home life that is reflected in off task behaviour in the classroom. If teachers are unaware of these situation actions in class that would normally support student

It is the difference between what is known and not known that can lead to unintended consequences of action by teachers. Expanding teachers' knowledgeability occurs when a person becomes aware of the conditions that lead to unintended consequences. This means that expanding teachers' knowledgeability has the potential to uncover routines supported by the

Burridge, Hooley and Neil have proposed that knowledgeability is linked to the concept, 'frames of practice'.  Teachers' frames of practice develop through experience, reflection

promotes reflection and critique, which encourage teachers to trial different approaches.

**4. Supporting teachers to evaluate pedagogy**

150 New Pedagogical Challenges in the 21st Century - Contributions of Research in Education

to become reflective practitioners.

engagement may prove ineffective.

tacit knowledge that undermined student achievement.

teacher's action. This occurs reflexively through the practical consciousness. New frames start to develop through the awareness of the discursive consciousness identifying the conditions leading to unintended consequences. This new awareness can lead to new approaches and procedures being used that over time can become stable and added to the established frames within the practical consciousness. In this way teachers build their tacit knowledge of teaching practice, and their capacity to reflexively monitor and manage classrooms.

can harmonise their plans of action on the basis of a common situation and definitions [20]. In essence, the focus of communicative action is towards understanding, learning and enlightenment [21]. Strategic action, in contrast, is where a group is focused on a predetermine outcome that maintains their position or power with in a setting. Such action will undermine the focus on understanding and whether done openly or covertly, will compromise the reflectively

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153

http://dx.doi.org/10.5772/intechopen.73201

The interaction of the elements identified in this process supports teachers to take purposeful action. Development of public sphere for reflective discussions is the essential factor for the process to occur. Without open conversations about teaching practice unacknowledged conditions that lead to unintended consequences will not be identified and effective change

discursive process, summarised in **Figure 2**.

to pedagogy unlikely.

**Figure 2.** The reflective discursive process.

Problems occur when these established frames of practice are not attending to the needs of students, but the teacher unknowingly relies on this practice. This may come about through a change in circumstances or the influence of professional habitus clouding pedagogic judgement. Whichever the reason, it highlights the need to regularly examine practices to reveal unacknowledged conditions that may be leading to unintended consequences.

Collaborative discussions with peers as illustrated by Trimble Secondary College teachers' professional learning teams are an example of how practices can be examined. When teachers openly reflect on their teaching practices, describing and critiquing specific actions, unacknowledged conditions that lead to unintended consequences can be uncovered.

#### *Case snippet*

In Year 8, English classes studying how to write a biography, involved students researching and writing about a famous Australian. The level of student engagement was quite low, with only half the students completing the assignment. Although the approach was ineffective it had been the standard approach for years. Through discussions with colleagues, the teachers reviewed their practice and came to the conclusion that stories of famous Australians did not connect with the students' lives and their local community. This observation led to a change of approach by asking students to write a biography about a significant adult in their lives, which they would then present to family and community members.

*They learnt about skinny and fat questions and eventually, they had to find someone to interview and taped their interview and wrote their books. Then we had a night where they could bring their families and the person that they wrote about to a presentation night. The books were great, and I was really proud of them (the students). The kids had to get up in front of everyone. We had about 70 people at each night which is a better proportion than parent teacher interview nights, because their kid was going to present something. (*Tony year 7 teacher*).*

Connecting the curriculum directly to students lives combined with the authentic assessment of presenting the biography to an audience required a change in pedagogy. This only occurred when teachers identified the unacknowledged conditions of action of an assessment task that lack relevance to the students. The change to the task then altered the skills being taught and the pedagogy being used with a corresponding change in student engagement and learning.

For discussions such as the one described, that critiqued teaching practice, to occur, a trust environment must be present. Habermas' refers to this environment of trust as the 'public sphere' [18]. Within the public sphere, all opinions are given equal merit, and the discussion is an inclusive process with the goal of purposeful action that Habermas identifies as communicative action [19]. In communicative action participants are not primarily oriented to their own individual successes; they pursue their individual goals under the condition that they can harmonise their plans of action on the basis of a common situation and definitions [20]. In essence, the focus of communicative action is towards understanding, learning and enlightenment [21]. Strategic action, in contrast, is where a group is focused on a predetermine outcome that maintains their position or power with in a setting. Such action will undermine the focus on understanding and whether done openly or covertly, will compromise the reflectively discursive process, summarised in **Figure 2**.

The interaction of the elements identified in this process supports teachers to take purposeful action. Development of public sphere for reflective discussions is the essential factor for the process to occur. Without open conversations about teaching practice unacknowledged conditions that lead to unintended consequences will not be identified and effective change to pedagogy unlikely.

**Figure 2.** The reflective discursive process.

teacher's action. This occurs reflexively through the practical consciousness. New frames start to develop through the awareness of the discursive consciousness identifying the conditions leading to unintended consequences. This new awareness can lead to new approaches and procedures being used that over time can become stable and added to the established frames within the practical consciousness. In this way teachers build their tacit knowledge of teach-

Problems occur when these established frames of practice are not attending to the needs of students, but the teacher unknowingly relies on this practice. This may come about through a change in circumstances or the influence of professional habitus clouding pedagogic judgement. Whichever the reason, it highlights the need to regularly examine practices to reveal

Collaborative discussions with peers as illustrated by Trimble Secondary College teachers' professional learning teams are an example of how practices can be examined. When teachers openly reflect on their teaching practices, describing and critiquing specific actions, unac-

In Year 8, English classes studying how to write a biography, involved students researching and writing about a famous Australian. The level of student engagement was quite low, with only half the students completing the assignment. Although the approach was ineffective it had been the standard approach for years. Through discussions with colleagues, the teachers reviewed their practice and came to the conclusion that stories of famous Australians did not connect with the students' lives and their local community. This observation led to a change of approach by asking students to write a biography about a significant adult in their lives,

*They learnt about skinny and fat questions and eventually, they had to find someone to interview and taped their interview and wrote their books. Then we had a night where they could bring their families and the person that they wrote about to a presentation night. The books were great, and I was really proud of them (the students). The kids had to get up in front of everyone. We had about 70 people at each night which is a better proportion than parent teacher interview nights, because their kid was going to*

Connecting the curriculum directly to students lives combined with the authentic assessment of presenting the biography to an audience required a change in pedagogy. This only occurred when teachers identified the unacknowledged conditions of action of an assessment task that lack relevance to the students. The change to the task then altered the skills being taught and the pedagogy being used with a corresponding change in student engagement and learning.

For discussions such as the one described, that critiqued teaching practice, to occur, a trust environment must be present. Habermas' refers to this environment of trust as the 'public sphere' [18]. Within the public sphere, all opinions are given equal merit, and the discussion is an inclusive process with the goal of purposeful action that Habermas identifies as communicative action [19]. In communicative action participants are not primarily oriented to their own individual successes; they pursue their individual goals under the condition that they

ing practice, and their capacity to reflexively monitor and manage classrooms.

152 New Pedagogical Challenges in the 21st Century - Contributions of Research in Education

unacknowledged conditions that may be leading to unintended consequences.

knowledged conditions that lead to unintended consequences can be uncovered.

which they would then present to family and community members.

*present something. (*Tony year 7 teacher*).*

*Case snippet*

The public sphere and development of trust will require an acknowledgement of different professional habitus and frames of practice. Supporting teachers to share their perspectives on teaching and learning will lead to richer reflective discussions uncovering the unintended consequences of practice, with an expansion of knowledgeability and frames of practice. This deeper understanding of teaching leads to more complex frames of practice that strengthens ontological security. The strength comes from teachers being able to manage anxiety, as anxiety is linked to the unknown outcome of choice [9]. Where there is a choice there is always the risk of choosing a course of action that will not result in the desired outcome. With more complex frames of practice, teachers are more able to see the range of possible outcomes, with an associated confidence in choosing a positive course of action.

*There was no one particular person leading it and that was the other powerful thing. It was like a team. There was Jimmy Hills and myself and another couple pretty interested in this idea, but no one was really running it. Each week we would come along discuss and report back and it gathered its own*

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Ken and Trevor's comments highlight the stability of schools and the difficulty of change. Ken described the student behaviour and the difficulties at the school as serious that provided a strong motivation for change. Even in this situation, teachers were hesitant with fear of the unknown, high levels of anxiety were present that the situation might become more difficult. Trevor's reflections on moving to the table group approach in classrooms and cooperative learning was a significant change for teachers. It challenged not only the current structures of

A number of ontologically secure teachers led discussions about pedagogy that was the catalyst to reflect on current practices. The teachers came together to discuss approaches with all opinions being valued. It was this reflection in the trust environment of the public sphere that led to an expansion of teachers understanding and frames of practice. Only then were teach-

Such action highlights the teacher as the agent of pedagogical change, and it is the teachers' ability to, "rethink their social relationships and pedagogical practices within and outside of school…questioning and shedding previously cherished values and beliefs" [22], which provides the conditions to change pedagogy. It is this type of critical questioning that occurs through reflectively discursive activities which expand teacher frames of practice, developing the ontological security required for teachers to take purposeful action

Teachers make a difference to student learning when they choose pedagogies that meet the needs of the students they teach. Indications that these choices have been effective will be seen in the students' level of engagement with the learning activities, development of the students understanding of the concepts taught and their ability to apply these concepts to settings beyond the classroom. However, too often teachers become reliant on routine and are drawn into a reproduction of teaching practice rather than an evolution of their teaching practice that

To support teachers in making pedagogic decisions that are appropriate for their students, a number of conditions need to be met. First, space and time are required. Space refers to a cognitive environment different to the norms of their practice. Gathering together people from across teaching disciplines provides such an environment, as teachers from different subject

Time is needed for the development of trust which results in deeper reflective discussions. In the trust environment of the public sphere, all opinions are given equal merit and the critique

areas bring a range of perspectives to evaluate pedagogies being used.

*momentum. (*Trevor, classroom teacher and program coordinator*).*

the school, but also the teachers' ontological security and professional habitus.

ers able to take creative risks and implement cooperative learning pedagogy.

around pedagogy.

**5. Conclusion**

is responsive to the students being taught [9].

Even with a more sophisticated understanding of teaching practice and awareness of possible outcomes, change will only occur when teachers take action. This may seem obvious, but routinization, a desire to maintain ontological security and the influence of professional habitus supporting personal identity can be significant barriers to change. As discussed, the rules and norms of social structures although created by people also influence people's actions. In schools, as with all social structures, norms and rules exist because teachers have maintained the practices over time. This duality is the both a strength of social structures and a weakness. It is strong through providing a sense of security and weak when ineffective practices are perpetuated.

Because of the duality within social structures it is difficult for the action of one person to have an effect on the institution's structures or practices. Social structures develop through people reproducing the practice over time, leading to routinization. If the actions of many people are required to reproduce the practices the action of one person can be easily absorbed without a change to structures or practices.

This is seen in schools where ontologically secure teachers may transform the learning of the students in their classrooms, but other classrooms remain unaffected. For ontological secure teachers to have an effect on the structure of schools, they must assemble the social and cultural capital required for other teachers to view their actions as legitimate. If the actions are seen as legitimate, there is a greater likelihood of widespread change, but this will not occur without teachers involved in the process developing the levels of ontological security required to take creative risks for change.

#### *Case snippet*

*No, personally I thought people wouldn't be game enough to make the change, it doesn't sound like a big change, but for a secondary school it was… (*Trevor, classroom teacher and program coordinator*).*

*Mind you, the way we were operating at one stage here, on this campus; you probably wouldn't have wanted your kid to come to the school…Things have changed that much…if the kids have a disagreement, you can sort things out as people rather than just power. (*Ken, Year 8 classroom teacher*).*

*To change every classroom, every teacher had to accept it; it was no good if one person didn't, every classroom had to teach in that way. We knew that it meant a change in pedagogy… I really thought people would say, "no, this is too big", some said that, others were nervous but we went ahead anyway, and it's the best thing we ever did.*

*There was no one particular person leading it and that was the other powerful thing. It was like a team. There was Jimmy Hills and myself and another couple pretty interested in this idea, but no one was really running it. Each week we would come along discuss and report back and it gathered its own momentum. (*Trevor, classroom teacher and program coordinator*).*

Ken and Trevor's comments highlight the stability of schools and the difficulty of change. Ken described the student behaviour and the difficulties at the school as serious that provided a strong motivation for change. Even in this situation, teachers were hesitant with fear of the unknown, high levels of anxiety were present that the situation might become more difficult. Trevor's reflections on moving to the table group approach in classrooms and cooperative learning was a significant change for teachers. It challenged not only the current structures of the school, but also the teachers' ontological security and professional habitus.

A number of ontologically secure teachers led discussions about pedagogy that was the catalyst to reflect on current practices. The teachers came together to discuss approaches with all opinions being valued. It was this reflection in the trust environment of the public sphere that led to an expansion of teachers understanding and frames of practice. Only then were teachers able to take creative risks and implement cooperative learning pedagogy.

Such action highlights the teacher as the agent of pedagogical change, and it is the teachers' ability to, "rethink their social relationships and pedagogical practices within and outside of school…questioning and shedding previously cherished values and beliefs" [22], which provides the conditions to change pedagogy. It is this type of critical questioning that occurs through reflectively discursive activities which expand teacher frames of practice, developing the ontological security required for teachers to take purposeful action around pedagogy.


**1. Introduction**

Limpets are marine gastropods. They distribute at different intertidal zones of most oceans, from the upper littoral to the shallow subtidal on the rocky coasts. They feed by grazing on macroalgae, benthic diatom growing on rocky substrate because they attach themselves to rocks, and/or any substratum using pedal mucus and a muscular "foot," which also enables them to go against dangerous wave action, desiccation, and predator.

*Cellana* genus is a marine gastropod mollusk in the family Nacellidae [1]. This genus distributes in the temperate and tropical Indo-Pacific Oceans, Hawaii,

Australia, and New Zealand. Species are also found around the coasts of Japan, the Red Sea, Madagascar, South Africa, and the subantarctic island. There are more than 58 species of this genus. Among of those, many of them are of high economic value and aquaculture, for example, the two species *Cellana talcosa* and *Cellana sandwicensis* are expensive in Hawaii.

In Hawaii, there are three main endemic Hawaiian limpet species, called "opihi," including black foot or makaiauli (*Cellana exarata*), yellow foot or ālinalina (*C. sandwicensis*), and the largest species, giant limpet or kōʻele (*C. talcosa*) [2]. Natural ecological distribution of Hawaiian limpet is different intertidal zones of habitation on rocky shores. *C. exarata* is commonly found at higher intertidal zones, and *C. sandwicensis* is at low intertidal zones and rarely exposed by tide, whereas *C. talcosa* distributes in deep water [3–6]. These species are herbivorous grazers that feed on benthic microalgae, diatoms that growing hard substrates such as rocky substrates, death coral reef, and so on. They use teeth in their radula to graze on the toughest crustose coralline algae [3]. They are considered as highvalue food market and high-potential candidate species for commercial aquaculture. High commercial catch reduced significantly from 150,000 pounds in the 1900s to about 10,000 pounds in 1978 [7]. The scarcity has boost up prices to about \$200/gallon with shell on [8].

In addition to important food sources, these Hawaiian limpet species are also culturally important in Hawaiian society. Many people (opihi pickers) were asked to collect these opihi for parties or family gathering with high prices. Besides that limpet's shell also continue to be used as tools for scraping skin off taro plant and sweet potato and grating coconut meat before eating [9] and as decorative elements in jewelry.

The success of any aquaculture species depends on seed production in captivity. Understanding the completion of the life cycle of limpet would make limpet aquaculture sustainable. The first priority is to understand some reproductive characteristics of the limpet species. This would also provide us with better knowledge for breeding limpet in the hatchery. In this chapter, we describe the current finding on reproductive biology, seed production, nutrient requirement, and culture techniques for the Hawaiian limpet *Cellana sandwicensis*.

## **2. Some reproductive characteristics of Hawaiian limpet** *C. sandwicensis*

Reproductive characteristics of Hawaiian limpet *C. sandwicensis* have been reported by several studies [10–12]. The main focused reproductive criteria were spawning season, gonad development stage, fecundity, and maturity size.

#### **2.1 Spawning season**

A total of 266 specimens (**Table 1**) were sampled for a 1-year cycle (November 2011–December 2012) in Hawaii Island, and gonadal somatic index (GSI) was determined. The GSI was calculated according to equation GSI = (GW/BW) × 100, where GW is gonad weight and BW is body weight or soft body tissue. Gonad development stage was also evaluated by using histological examination. The result showed that the highest average GSI of *C. sandwicensis* was noticed between November and January. This suggests that spawning seasons of *C. sandwicensis* may occur right after this period, whereas the lowest GSI was found from March to August, this could probably be the resting season of the species. Similarly, the same GSI pattern (**Figure 1**) of males and females *C. sandwicensis* suggested synchronized spawning of male and female *C. sandwicensis* in the wild [10].

**85**

**2.2 Gonad development stage**

*data values from n individuals are presented as mean ± SD.*

male gonad (**Figure 2F**).

**2.3 Sexual determination**

The maturity stages of gonad development of Hawaiian limpet *C. sandwicensis* were reported and classified in **Table 2** and **Figure 2**. Multiple development stages (**Figure 2A**) were observed in the same ovary of female during the final maturation season. **Figure 2D** showed resting stages (April to August), because oocytes were not of clear formation from the ovary cell wall. Similar observation was made for gonad of the male (**Figure 2E**). The testes were densely packed with spermatozoa which appeared as dark blue stained by hematoxylin. Sperm were less densely in the

*Average size and GSI of sampled opihi for the reproductive cycle study from November 2011 to December 2012;*

Sexual determination of all limpet species is not known from external morphology. Render and maturation status of any limpet species could only be sexed after killing and dissecting. Our efforts were trying to examine ripeness of live animal

*Reproductive Biology, Seed Production, and Culture of the Hawaiian Limpet* Cellana*…*

**Total weight (g)** **Body weight (g)**

13 4.26 ± 0.59 15.3 ± 5.49 5.93 ± 2.43 1.68 ± 0.92 26.8 ± 6.27

30 3.46 ± 0.51 7.67 ± 3.63 2.54 ± 1.39 0.31 ± 0.22 11.7 ± 5.22

17 3.55 ± 0.96 9.31 ± 5.74 2.97 ± 2.40 0.93 ± 1.06 22.9 ± 12.4

27 3.11 ± 0.31 4.83 ± 1.74 1.86 ± 0.66 0.17 ± 0.09 9.05 ± 3.65

16 2.86 ± 0.48 4.68 ± 2.62 1.64 ± 0.71 0.20 ± 0.09 12.0 ± 5.41

12 3.26 ± 0.58 5.20 ± 2.47 1.81 ± 1.03 0.15 ± 0.14 8.73 ± 5.31

12 3.27 ± 0.56 5.20 ± 2.47 2.90 ± 3.50 0.14 ± 0.13 8.10 ± 5.25

17 3.17 ± 0.16 5.88 ± 0.91 2.19 ± 0.55 0.17 ± 0.11 7.25 ± 3.69

23 3.25 ± 0.43 5.98 ± 1.67 2.21 ± 0.78 0.16 ± 0.11 7.19 ± 4.51

12 3.95 ± 0.50 9.49 ± 3.91 3.47 ± 1.50 0.30 ± 0.28 7.56 ± 5.37

20 3.43 ± 0.44 5.43 ± 2.19 1.89 ± 0.91 0.28 ± 0.29 11.5 ± 7.43

21 3.71 ± 0.92 7.07 ± 5.38 2.86 ± 2.01 0.65 ± 0.73 18.7 ± 8.77

27 3.96 ± 0.49 8.75 ± 3.21 3.73 ± 1.47 1.31 ± 0.73 31.8 ± 7.72

19 3.96 ± 0.83 10.2 ± 8.64 4.10 ± 3.77 1.52 ± 1.94 28.4 ± 3.75

**Gonad weight (g)** **GSI (%)**

*DOI: http://dx.doi.org/10.5772/intechopen.87128*

**n Shell length (cm)**

**Date of sampling**

November 12, 2011

December 04, 2011

January 31, 2012

February 28, 2012

March 28, 2012

April 24, 2012

May 28, 2012

June 28, 2012

July 21, 2012

August 03, 2012

September 11, 2012

October 05, 2012

November 25, 2012

December 30, 2012

**Table 1.**

*Reproductive Biology, Seed Production, and Culture of the Hawaiian Limpet* Cellana*… DOI: http://dx.doi.org/10.5772/intechopen.87128*

#### **Table 1.**

*Invertebrates - Ecophysiology and Management*

*sandwicensis* are expensive in Hawaii.

\$200/gallon with shell on [8].

niques for the Hawaiian limpet *Cellana sandwicensis*.

in jewelry.

**2.1 Spawning season**

Australia, and New Zealand. Species are also found around the coasts of Japan, the Red Sea, Madagascar, South Africa, and the subantarctic island. There are more than 58 species of this genus. Among of those, many of them are of high economic value and aquaculture, for example, the two species *Cellana talcosa* and *Cellana*

In Hawaii, there are three main endemic Hawaiian limpet species, called "opihi,"

In addition to important food sources, these Hawaiian limpet species are also culturally important in Hawaiian society. Many people (opihi pickers) were asked to collect these opihi for parties or family gathering with high prices. Besides that limpet's shell also continue to be used as tools for scraping skin off taro plant and sweet potato and grating coconut meat before eating [9] and as decorative elements

The success of any aquaculture species depends on seed production in captivity. Understanding the completion of the life cycle of limpet would make limpet aquaculture sustainable. The first priority is to understand some reproductive characteristics of the limpet species. This would also provide us with better knowledge for breeding limpet in the hatchery. In this chapter, we describe the current finding on reproductive biology, seed production, nutrient requirement, and culture tech-

**2. Some reproductive characteristics of Hawaiian limpet** *C. sandwicensis*

Reproductive characteristics of Hawaiian limpet *C. sandwicensis* have been reported by several studies [10–12]. The main focused reproductive criteria were spawning season, gonad development stage, fecundity, and maturity size.

A total of 266 specimens (**Table 1**) were sampled for a 1-year cycle (November

2011–December 2012) in Hawaii Island, and gonadal somatic index (GSI) was determined. The GSI was calculated according to equation GSI = (GW/BW) × 100, where GW is gonad weight and BW is body weight or soft body tissue. Gonad development stage was also evaluated by using histological examination. The result showed that the highest average GSI of *C. sandwicensis* was noticed between November and January. This suggests that spawning seasons of *C. sandwicensis* may occur right after this period, whereas the lowest GSI was found from March to August, this could probably be the resting season of the species. Similarly, the same GSI pattern (**Figure 1**) of males and females *C. sandwicensis* suggested synchronized

spawning of male and female *C. sandwicensis* in the wild [10].

including black foot or makaiauli (*Cellana exarata*), yellow foot or ālinalina (*C. sandwicensis*), and the largest species, giant limpet or kōʻele (*C. talcosa*) [2]. Natural ecological distribution of Hawaiian limpet is different intertidal zones of habitation on rocky shores. *C. exarata* is commonly found at higher intertidal zones, and *C. sandwicensis* is at low intertidal zones and rarely exposed by tide, whereas *C. talcosa* distributes in deep water [3–6]. These species are herbivorous grazers that feed on benthic microalgae, diatoms that growing hard substrates such as rocky substrates, death coral reef, and so on. They use teeth in their radula to graze on the toughest crustose coralline algae [3]. They are considered as highvalue food market and high-potential candidate species for commercial aquaculture. High commercial catch reduced significantly from 150,000 pounds in the 1900s to about 10,000 pounds in 1978 [7]. The scarcity has boost up prices to about

**84**

*Average size and GSI of sampled opihi for the reproductive cycle study from November 2011 to December 2012; data values from n individuals are presented as mean ± SD.*

#### **2.2 Gonad development stage**

The maturity stages of gonad development of Hawaiian limpet *C. sandwicensis* were reported and classified in **Table 2** and **Figure 2**. Multiple development stages (**Figure 2A**) were observed in the same ovary of female during the final maturation season. **Figure 2D** showed resting stages (April to August), because oocytes were not of clear formation from the ovary cell wall. Similar observation was made for gonad of the male (**Figure 2E**). The testes were densely packed with spermatozoa which appeared as dark blue stained by hematoxylin. Sperm were less densely in the male gonad (**Figure 2F**).

#### **2.3 Sexual determination**

Sexual determination of all limpet species is not known from external morphology. Render and maturation status of any limpet species could only be sexed after killing and dissecting. Our efforts were trying to examine ripeness of live animal

#### **Figure 1.**

*Seasonal changes in GSI of males and females limpet* C. sandwicensis*.*

#### **Table 2.**

*Maturation stages of gonad of limpets [10–12].*

without killing them. We eventually found a way to assess the gonad, by placing them upside down on a table or putting them close to the edge of a substrate. When they try to attach to the substrate, they move their foot toward the substrate, and sometimes the gonads may be seen from the top of their head. Males were identified if the animals had milky white gonad near the edge of the shell, as shown by the arrow in **Figure 3A**. The gonad of the ripe female was dark brown or dark green in color (**Figure 3C**). It is noticed that this way, it can only be conducted when the animal reaches maturity stage or during the spawning season. Ultrasound was also an option method, but it's inconvenient and is not a practical way.

#### **2.4 Fecundity and maturity size**

Absolute fecundity (F) of mature female (n = 5) limpet *C. sandwicensis* is varied, and related maturity stage and body weight of animal found that total

**87**

77.3 (R2

**Figure 3.**

*with shell removal.*

**Figure 2.**

larger [2].

*Reproductive Biology, Seed Production, and Culture of the Hawaiian Limpet* Cellana*…*

*Cross sections showing stages of limpet* C. sandwicensis *gonad development. (A) Most oocytes in early development stages in ovary of female, (B) oocytes deforming shape in the ovary, (C) ripe stage and some oocytes were still in late development stage, (D) resting development stages of female, (E) mature male gonad*

*with dark blue stained by hematoxylin, and (F) spermatic in gonad of male.*

eggs counted ranged from 42.080 to 157.000 eggs per g body weight (BW). Fecundity was plotted against body weight with linearly correlated to body weight (*P* = 0.019), and the best is described by the equations F = 28.4 BW −

*Determination of sexually mature male and female limpet. (A) Live limpet before dissecting, the arrow shows a sign where mature male gonad could be identified; (B) soft body tissue was removed off the shell, the mature male gonad (milky white) took up all the space around the digestive gland (dark color). This supports the location of mature gonad where it was seen as pointed in picture A; (C) live female limpet before dissecting, the arrow points where mature female's gonad would be seen; (D) showing a dark brown mature female gonad*

 = 0.96). The monthly recorded GSI data combined with histology analysis showed that the Hawaiian limpet *C. sandwicensis* would attain sexual maturity size about 1.5–2.0 cm in shell length. Other studies also found that *C. sandwicensis* attained reproductive stage at shell length of 2.3–2.5 cm or

*DOI: http://dx.doi.org/10.5772/intechopen.87128*

*Reproductive Biology, Seed Production, and Culture of the Hawaiian Limpet* Cellana*… DOI: http://dx.doi.org/10.5772/intechopen.87128*

#### **Figure 2.**

*Invertebrates - Ecophysiology and Management*

**Stage Description**

**Figure 1.**

5 Spawning and reabsorbing

*Maturation stages of gonad of limpets [10–12].*

**2.4 Fecundity and maturity size**

**Table 2.**

1 Resting stage The gonad is characterized by little or germinal epithelium, unclear

2 Early development Nucleus enlarged, oocyte diameter about 7–10 μm. The male gonad is

3 Late development The ovaries are swollen laterally and some oocytes in the final stages of

4 Ripe Ovaries are swollen with dark brown color. Oocytes diameter ranging

without killing them. We eventually found a way to assess the gonad, by placing them upside down on a table or putting them close to the edge of a substrate. When they try to attach to the substrate, they move their foot toward the substrate, and sometimes the gonads may be seen from the top of their head. Males were identified if the animals had milky white gonad near the edge of the shell, as shown by the arrow in **Figure 3A**. The gonad of the ripe female was dark brown or dark green in color (**Figure 3C**). It is noticed that this way, it can only be conducted when the animal reaches maturity stage or during the spawning season. Ultrasound was also

Absolute fecundity (F) of mature female (n = 5) limpet *C. sandwicensis* is varied, and related maturity stage and body weight of animal found that total

and/or dark blue stained by hematoxylin

less densities of mature oocytes relative to ripe gonads.

oocytes about 2 μm

of the testes lobes

to 100 μm

*Seasonal changes in GSI of males and females limpet* C. sandwicensis*.*

an option method, but it's inconvenient and is not a practical way.

distinguishable from ovary wall cells and also for spermatid, the initial

shaped like around tubule and a thick germinal epithelium lines the edges

vitellogenesis. Cytoplasm granular, the oocytes diameter ranging from 50

from 110 to 130 μm. The testis is dense with spermatozoa, milky white

Spawning testis contained about 80% mature sperm; the ovary contains

**86**

*Cross sections showing stages of limpet* C. sandwicensis *gonad development. (A) Most oocytes in early development stages in ovary of female, (B) oocytes deforming shape in the ovary, (C) ripe stage and some oocytes were still in late development stage, (D) resting development stages of female, (E) mature male gonad with dark blue stained by hematoxylin, and (F) spermatic in gonad of male.*

#### **Figure 3.**

*Determination of sexually mature male and female limpet. (A) Live limpet before dissecting, the arrow shows a sign where mature male gonad could be identified; (B) soft body tissue was removed off the shell, the mature male gonad (milky white) took up all the space around the digestive gland (dark color). This supports the location of mature gonad where it was seen as pointed in picture A; (C) live female limpet before dissecting, the arrow points where mature female's gonad would be seen; (D) showing a dark brown mature female gonad with shell removal.*

eggs counted ranged from 42.080 to 157.000 eggs per g body weight (BW). Fecundity was plotted against body weight with linearly correlated to body weight (*P* = 0.019), and the best is described by the equations F = 28.4 BW − 77.3 (R2 = 0.96). The monthly recorded GSI data combined with histology analysis showed that the Hawaiian limpet *C. sandwicensis* would attain sexual maturity size about 1.5–2.0 cm in shell length. Other studies also found that *C. sandwicensis* attained reproductive stage at shell length of 2.3–2.5 cm or larger [2].


*2.3. Assessment of the Risk of Bias in Included Studies*

Two authors independently assessed the methodological quality of each included clinical trial, according to the Cochrane risk of bias tool for randomized controlled trials (RoB 2.0) [18]. RoB 2.0 is composed of five domains, including bias arising from the randomization process (allocation), bias due to deviations from the intended interventions (performance), bias due to missing outcome data (follow-up), bias in the outcome measurement (measurement), and bias in the selection of the reported results (reporting). The authors rated each domain as either low risk, some concerns (uncertain risk of bias), or high risk. Discrepancies were resolved by the third reviewer.


**4. Redox alterations in hepatotoxicity**

The role played by the cellular redox state in the hepatic pathophysiological mechanisms is not well defined. Indeed, hepatotoxicity has been much linked to the oxidative status and deficiencies in the liver antioxidant system. For instance, in the case of the alcoholic liver disease (ALD) mainly represented by a chronic stage of alcoholic steatohepatitis (ASH), alter‐ ations in the cell redox state have been implicated in injured hepatocytes [40]. Ethanol is metabolized via alcohol dehydrogenase (ADH), the microsomal ethanol oxidizing system, and by catalase in the liver peroxisomes, although the activity of ADH is responsible for most of the ethanol catabolism. In this pathway, NAD+ is reduced by a transfer of hydrogen (and one electron, e**−** ) to NADH, with the concomitant production of acetaldehyde. The NADP+ can be also reduced, and hydrogen equivalents from ethanol, but not NADH, are transferred from the cytosol to the mitochondria via a shuttle mechanism such as the malate shuttle, the fatty acid elongation cycle, and/or the α‐glycerophosphate cycle; therefore, mitochondria become more reduced [41, 42].

Lately, the nonalcoholic steatohepatitis (NASH) is becoming a pathological entity gaining a significant public health concern [43]. NASH is a progressive form of nonalcoholic fatty liver disease (NAFLD) and features of NASH include steatosis, inflammation and varying degrees of fibrosis, and seems to follow a 2‐hit model, where the "1st Hit" involves excess of lipid accumulation in the liver, which sensitizes the liver to the "2nd Hit". This "2nd Hit" involves inflammation, oxidative stress, liver damage and fibrosis [44]. Here, multiple cellu‐ lar processes play important roles in maintaining the NAD+ /NADH ratio. For example, dur‐ ing glycolysis, β‐oxidation, and the TCA activity, NAD+ is reduced to NADH. Within the mitochondria, NADH is oxidized by the electron transport chain enzymes during oxidative phosphorylation.

Laboratory animals exposed to high fat diet exhibit impaired oxidative metabolism through reduced electron transport chain activity [45]. Then, it is possible that those animals exposed to high fat during late gestation and early postnatal life present a state of redox imbalance, and although their livers are able to readily reduce NADH during catabolic redox reactions (in response to increased fat intake), the ability to replenish NAD+ reserves is reduced due to impaired oxidative capacity [46]. High fat feeding is associated with depleted NAD+ reserves and reduced SIRTs abundance, both established hallmarks of metabolic aging, and supple‐ mentation with factors reversing the effects of depleted NAD+ reserves, and/or SIRT1 and SIRT3 abundance rescue the increased susceptibility to develop severe fatty liver disease in the adult life [47].

Liver steatosis induces a reduced state in cytosol and mitochondria of hepatocytes, as dem‐ onstrated by alterations in the NADH/NAD+ ratio calculated from the β‐hydroxybutyrate dehydrogenase and lactate dehydrogenase reactions [48]. The increased formation of reduc‐ ing equivalents could impair fatty acids oxidation and the TCA cycle [49], but it could also enhance the formation of glycerol‐3‐phosphate and thus lipogenesis [50]. Saturation of lipids may also modify cellular redox status. Among free fatty acids, monounsaturated fatty acids, such as oleic acids, are less toxic than palmitate, a saturated acid, because the latter increases the NADH/NAD+ ratio and promotes uncoupling between glycolysis and TCA cycle fluxes, leading to increased ROS production [51]. The hepatic accumulation of saturated fatty acids can promote redox imbalance and the formation of reactive oxygen intermediates, mainly inducing endoplasmic reticulum (ER) stress and apoptosis [52].

**4. Redox alterations in hepatotoxicity**

164 Redox - Principles and Advanced Applications

of the ethanol catabolism. In this pathway, NAD+

lar processes play important roles in maintaining the NAD+

(in response to increased fat intake), the ability to replenish NAD+

mentation with factors reversing the effects of depleted NAD+

onstrated by alterations in the NADH/NAD+

ing glycolysis, β‐oxidation, and the TCA activity, NAD+

one electron, e**−**

more reduced [41, 42].

phosphorylation.

the adult life [47].

The role played by the cellular redox state in the hepatic pathophysiological mechanisms is not well defined. Indeed, hepatotoxicity has been much linked to the oxidative status and deficiencies in the liver antioxidant system. For instance, in the case of the alcoholic liver disease (ALD) mainly represented by a chronic stage of alcoholic steatohepatitis (ASH), alter‐ ations in the cell redox state have been implicated in injured hepatocytes [40]. Ethanol is metabolized via alcohol dehydrogenase (ADH), the microsomal ethanol oxidizing system, and by catalase in the liver peroxisomes, although the activity of ADH is responsible for most

be also reduced, and hydrogen equivalents from ethanol, but not NADH, are transferred from the cytosol to the mitochondria via a shuttle mechanism such as the malate shuttle, the fatty acid elongation cycle, and/or the α‐glycerophosphate cycle; therefore, mitochondria become

Lately, the nonalcoholic steatohepatitis (NASH) is becoming a pathological entity gaining a significant public health concern [43]. NASH is a progressive form of nonalcoholic fatty liver disease (NAFLD) and features of NASH include steatosis, inflammation and varying degrees of fibrosis, and seems to follow a 2‐hit model, where the "1st Hit" involves excess of lipid accumulation in the liver, which sensitizes the liver to the "2nd Hit". This "2nd Hit" involves inflammation, oxidative stress, liver damage and fibrosis [44]. Here, multiple cellu‐

mitochondria, NADH is oxidized by the electron transport chain enzymes during oxidative

Laboratory animals exposed to high fat diet exhibit impaired oxidative metabolism through reduced electron transport chain activity [45]. Then, it is possible that those animals exposed to high fat during late gestation and early postnatal life present a state of redox imbalance, and although their livers are able to readily reduce NADH during catabolic redox reactions

and reduced SIRTs abundance, both established hallmarks of metabolic aging, and supple‐

SIRT3 abundance rescue the increased susceptibility to develop severe fatty liver disease in

Liver steatosis induces a reduced state in cytosol and mitochondria of hepatocytes, as dem‐

dehydrogenase and lactate dehydrogenase reactions [48]. The increased formation of reduc‐ ing equivalents could impair fatty acids oxidation and the TCA cycle [49], but it could also enhance the formation of glycerol‐3‐phosphate and thus lipogenesis [50]. Saturation of lipids may also modify cellular redox status. Among free fatty acids, monounsaturated fatty acids, such as oleic acids, are less toxic than palmitate, a saturated acid, because the latter increases

impaired oxidative capacity [46]. High fat feeding is associated with depleted NAD+

) to NADH, with the concomitant production of acetaldehyde. The NADP+

is reduced by a transfer of hydrogen (and

/NADH ratio. For example, dur‐

reserves is reduced due to

reserves, and/or SIRT1 and

ratio calculated from the β‐hydroxybutyrate

reserves

is reduced to NADH. Within the

can

Moreover, the pathogenesis of early‐stage NASH is characterized by hyperinsulinemia and *de novo* synthesis of fatty acids and nascent triacylglycerides, which are deposited as lipid drop‐ lets within the hepatocytes. Hyperinsulinemia shifts the energy supply from glucose to ketone bodies, and the high ketone body concentration induces the overexpression of cytochrome P450 2E1 (CYP2E1), resulting in unsaturated fatty acids peroxidation and aldehydes produc‐ tion [53]. The NADPH oxidase‐derived ROS from arachidonic acid peroxidation can induce the nuclear translocation of *EGR1*, which in turn can stimulate the expression of the downstream genes *ATF3* and *GADD45G*. ATF3 is a transcription factor involved in cell proliferation, apop‐ tosis, and invasion [54]. The increased redox signaling plays a central role in promoting insulin resistance in the liver in early NASH, followed by fibrogenesis through activation of protein kinase R (PKR), protein kinase R‐like endoplasmic reticulum kinase (PERK) key stress kinases [55]. There is evidence that activation of the purinergic receptor P2X7 can give rise to NADPH oxidase activation, leading to Kupffer cell activation, a key event in NASH progression [56].

Peroxisomal oxidation of fatty acids is the normal route of metabolism of very long chain fatty acids and dicarboxylic acids, where electrons from FADH2 and NADH are transferred directly to O2 [57]. Moreover, fatty acids not oxidized by mitochondria are mainly oxidized by CYP2E1; a process that further increases ROS production [58]. Therefore, many cellular systems are important sources of ROS, including the mitochondrial respiratory chain [59], the cytochrome P450s [60], oxidative enzymes (xanthine oxidase, aldehyde oxidase, cyclooxy‐ genase, monoamine oxidase (MAO), and the NADPH oxidase complex) [61]. The uncoupling protein 2 (UCP‐2) may also enhance the reoxidation of NADH into NAD+ , which is required for both β‐oxidation and the TCA [62]; UCP‐2 oxidation might be considered an attempt to prevent steatosis by increasing hepatic fatty acid oxidation [63].

Moreover, it is accepted that in the NAFLD, depletion of hepatic antioxidants may contribute to the progression of steatosis to NASH by increasing oxidative stress that produces lipid peroxidation, inflammation, and fibrosis. Indeed, metabolic adaptations resulting from severe GSH deficiency seem to protect against the development of steatohepatitis [64]. In summary, all the redox alterations seem to be deeply implicated in the onset of NASH and in its progres‐ sion to liver fibrosis and a putative installation of a cirrhotic process.

However, a possible role of a disturbed cell redox state is much less known in cirrhosis. Nonetheless, it has been suggested that collagen metabolism could be influenced by changes in redox state. It has been postulated that conversion of glutamic acid to proline [65], a decreased NAD+ /NADH ratio [66], as well as impediment of proline transport and oxidation, could increase the liver proline pool, as a fundamental collagen component in the onset of liver fibrosis [67].

In experimental models of rat liver fibrosis/cirrhosis, mitochondrial function and structure show a variety of alterations. ATP synthesis is reduced in rats treated with CCl4 or thioacet‐ amide, as well as in rats with secondary biliary cirrhosis. These alterations are compensated by increasing mitochondrial volume per hepatocyte and possible augmentation of extrahe‐ patic ATP production, as an effort for maintaining mitochondrial function in the cirrhotic liver [68]. These reports agree with the statement that in perfused cirrhotic livers, a reduced cytoplasmic and mitochondrial redox states occur accompanied by a diminished activity in the mitochondrial electron‐transport chain [69].


*3.3. Catalytic Activity of Ag2O, CeO2, and Ag-doped CeO2 catalysts*

The evaluation of the catalytic activity of Ag2O, CeO2, and Ag doped CeO2 thin films deposited at 200 ◦C on stainless steel foil was carried out to show the effectiveness of the catalysts for soot combustion applications. The annealing tests of carbon soot, which was generated from diesel fuel, was carried out under ambient air environment inside an oven in the temperature range 300–490 ◦C for 2 h.

Figure 12 shows histograms of soot conversion vs. annealing temperature for catalytic and non-catalytic combustion. The conversion is defined as:

$$\mathbb{C}(\%) = \frac{M\_0 - M}{M\_0} \times 100\% \tag{1}$$

where is *M*0 is the initial soot mass, and *M* is the amount of soot left on the catalyst after burning by heating up to a given *T* value. Weight loss values were obtained by weighing the samples before and after the annealing test which continued for 2 h.

**Figure 12.** Conversion of oxidized soot on silver oxide, cerium oxide, and silver doped cerium oxide in ratio CeO2:Ag 10:1, 20:1, 30:1 thin films deposited on stainless steel foil at 200 ◦C vs. annealing temperature over 2 h. The measurement uncertainty is approximately 5%.

The conversion of oxidized soot was demonstrated on non-catalysed reference steel foil, and on cerium oxide, silver oxide, and Ag doped CeO2 thin films deposited on stainless steel foil at 200 ◦C in loose contact mode (Figure 12). As expected, complete soot conversion on the uncoated reference sample was only achieved at 600 ◦C. All the catalysts were effective in promoting combustion at temperatures below 490 ◦C. Although the soot was well oxidized on pure CeO2 and Ag2O thin films themselves, Ag loading into CeO2 thin films caused a significant enhancement of soot oxidation rate, in accordance with previous reports [28]. It is noteworthy that the soot oxidation activity of Ag doped CeO2 was different depending on the dopant concentration. The sample having the maximum silver loading CeO2:Ag 10:1 and pure Ag2O showed the lowest oxidation temperature of 300 ◦C and complete combustion of the soot was achieved below 390 and 410 ◦C under real-world loose contact conditions, respectively. Table 4 lists the characteristic temperatures, where the ignition temperature (*T*i) is the temperature at which the combustion began, and the final temperature (*T*f) is the temperature at which the soot was completely oxidized.

**Table 4.** Catalytic performance for soot oxidation.

The catalysts with silver doping concentration of Ce2O:Ag 20:1 and 30:1 showed lower performance for 100% soot oxidation at *T*f = 490 ◦C. This indicates that the highest concentration of Ag+ ions, which is contained mostly in CeO2:Ag 10:1 catalyst, can effectively promote 100% soot oxidation at *T*f = 390 ◦C due to the oxygen species formed on Ag+ sites. Zou et al. [46] proposed that during silver oxide decomposition, its released oxygen migrates to soot surfaces to form carbon–oxygen intermediates, which are subsequently oxidized further. Finally, the adsorbed oxygen on the silver promotes the regeneration process. The redox reaction of Ag+ and the active oxygen species prevail in the reaction at low combustion temperatures. In addition, the silver oxide contributes to the adsorption of reactants to form complex π bonds that are significant for the formation of peroxide and superoxide species [47]. It is worth mentioning that higher concentration of Ce3+ contained in CeO2:Ag 10:1 catalyst can also form more active oxygen vacancies, which promote the activation of adsorbed oxygen to form superoxides in the lattice. These types of oxygen react with soot efficiently [48].

Because the melting point of Ag2O oxides is relatively low, compared with CeO2 (2400 ◦C), the stability of Ag/CeO2 catalysts during the soot oxidation is an important factor from the practical point of view. In order to gain information on the stability of Ag/CeO2, repetitive activity tests were carried out in loose contact mode at annealing temperature 430 ◦C. Figure 13 shows the conversion of oxidized soot after five replicate trials, and the observed results showed acceptable reproducibility with relative standard deviation of less than 5%. The pure Ag2O catalyst lost its catalytic activity immediately after the first trial from 100% to 50% of oxidized soot. Further use of Ag2O catalyst (in the third, fourth, and fifth trials) led to significant restructuring of the film and total loss of catalytic properties. For this reason, bulk Ag2O cannot be used in catalytic systems operating at higher temperature (above 300 ◦C).

**Figure 13.** Repetitive soot oxidation in the presence of silver oxide, cerium oxide, and silver doped cerium oxide in ratio CeO2:Ag 10:1, 20:1, and 30:1 thin films deposited on stainless steel foil at 200 ◦C vs. annealing temperature over 2 h at 430 ◦C.

It appears that CeO2/Ag 10:1 lost 10% of its activity in the third combustion test, indicating the deactivation of Ag/CeO2. However, during further trials this catalyst showed stable results of 90% oxidized soot. We can assume that Ag ions have a strong interaction with the CeO2 catalyst and remain stable after durability tests. Other catalysts such as CeO2:Ag 20:1, 30:1 and pure CeO2 do not lose activity, since the combustion curves obtained from the first to the fifth tests were very similar.


**6. Conclusions**

In this paper, we discussed the preimage problem in the space where the relationship between objects is determined by closeness. We showed that any metric can be transformed into closeness and therefore, the latter is weaker than the former. We interlaced closeness with fuzzy partition and characterized both by the closeness matrix.

We expressed similarity between functions based on their images (coinciding with vectors of scaled F-transform components) computed using the closeness matrix. By that (and by setting the basic structure of the space without metric, or norm), we contributed to the mathematical theory in the field of functional analysis. We formulated the preimage problem using the language of matrix calculus. The preimage problem solution is given by (i) a weighted arithmetic mean, (ii) any right inverse of the closeness matrix or (iii) any element of a certain affine subspace. Singular value decomposition was applied to describe the problem and its solution.

We defined the notion of compatible set of basic functions and found conditions under which the inverse F-transform with respect to the given and compatible set of basic functions forms a solution to the preimage problem.

Theoretical results were illustrated by numerical examples. They demonstrate, e.g., that requiring reflexivity of closeness can be counterproductive.

The future research will be focused on imposing further conditions on both collections of basic functions (*At*'s and *Bt*'s) to reveal stronger connections between the spaces *A* and *B*.

**Author Contributions:** Investigation, J.J. and I.P.; resources, J.J. and I.P.; writing—original draft preparation, J.J.; writing—review and editing, J.J. and I.P.; supervision, I.P. All authors have read and agreed to the published version of the manuscript.

**Funding:** The support of the project SGS20/PˇrF-MF/2022 of the University of Ostrava is greatly appreciated.

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

**Data Availability Statement:** Not applicable.

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

## **Symbols and Abbreviations**

The following symbols and abbreviations are used in this manuscript: