**3.10. Activity scheduling**

Another technique found in CBT programs planned for the treatment of childhood depression is technical activity planning. In this strategy, therapist finds the pleasing activities that will increase the functionality of child and enable him/her to receive the natural reinforcers in life, and encourages the child to perform them. The main behavior pattern that is frequently observed in depressive children is avoidance. Along with the avoidance behavior, depressive symptoms such as withdrawal, inertia, immobility increase further, and thus a reduction is observed in child's self-confidence and self-efficacy perceptions. Therefore, activity planning has become the primary technique in CBT manuals on childhood depression.

At activity planning stage, the child is first asked to keep an activity diary to understand his/her daily routine better, and the list is examined together with the child in the next session. Then, the current joys of the child and interests in his/her life before depression are researched. This might be done with the child or help of parents might be asked. All these activities are listed, and child is encouraged to take action by including rewarding into the process. The point to take into consideration here is avoiding establishing very high targets for the child considering the current state, developmental characteristics and social skill level of the child, and forcing him/her at this direction [43, 46]. The activities that can be performed must be gradually included in the daily routine of child, and some new activities to be performed at certain times of the week must be targeted for the next session.

Activity scheduling and homework as well as putting these into practice are techniques that can be applied throughout the whole therapy program. For this reason, activity records kept by the child, and proving that there is always something that can make him/her feel good by this way will positively affect the emotions related to depression such as despair, self-esteem, and self-sufficiency [46, 89, 98].


**4. Conclusions**

The experiments carried out in this work have confirmed that the properties of photocatalysts based on mixed oxides strongly depend on the starting materials and the way the binary- and mixedoxides are prepared. Even their real composition depends on the technique used for their preparation. Careful analyses are necessary to confirm their composition that can or cannot match the stoichiometric ratio used in their preparation. The surface composition can be different from bulk and this can influence the reactions, should they occur on the surface or into channels in the bulk.

The electronic properties of the photo-materials change with their composition and mode of synthesis. Using two different techniques (HEM and CP), the fundamental properties of the photocatalysts have been measured, including the band-gap and electrochemical potential. Some of the catalysts prepared, based on their band gap and value of E, have been tested in the gas-phase photoreduction of CO2 + H2O. The experimental results show that the synthetic technique influences the photoactivity of the materials that can correctly be foreseen on the basis of bandgap experimentally derived. Of the mixed oxides prepared and described in this work, only Cu2O@In2O3 prepared by co-precipitation from synthesized binary oxides have shown positive results in CO2–H2O photo-co-processing. Preliminary results show that the composition and synthetic methodologies of mixed-oxides, the reactor geometry, the way of dispersing the photocatalyst sample, play a key role in the light driven reaction of CO2–H2O. Hydrogen plus reduced species of CO2 (in lower amount) have been observed, depending on the geometry of the reactor used and the photocatalyst used. In order to observe the formation of reduction products it is necessary that the catalyst is finely dispersed

(thin film) and well illuminated. Massive amounts of photocatalyst are not active, at least under the illumination technique used in this work, most likely because the number of photons that reach the photoactive centers is quite low.

This work is a rare case of full characterization of photo-materials, using UV-Visible DRS, XPS, XRD, TEM, and EDX for the surface and bulk analytical characterization. We show that surface composition may not be the same of the bulk composition and plays a key role in photocatalysts behavior and a full material knowledge is necessary for the correct forecast of their photocatalytic behavior, inferred from experimentally determined bandgaps. Coupling UV-Vis DRS and XPS with EDX is necessary for getting the correct information about the composition of the materials and their surface-bulk characterization. Further studies are planned in order to discover the most active species and the best performing reactor geometry under best illumination conditions, using the systems which gave positive results so far. All of the systems described above are even under evaluation for discovering how their properties are changed with addition of partners such as noble metals or hole scavengers and attribute the correct role to each component of the photomaterial.

**Supplementary Materials:** The followings are available online at http://www.mdpi.com/2073-4344/10/9/980/s1, Figure S1: Comparison of CP-Fe2O3 XRD patterns with HEM-Cu/Fe-1 (a) and CP-Cu/Fe-1 (b) along with peak positions for reference diffraction patterns. Figure S2: High resolution XP spectra of all the samples. (a) C-Cu2O sample: (a1) Cu 2p3/2 spectral region, (a2) Cu LMM Auger transition and (a3) O1s spectral region. (b) S-Cu2O sample: (b1) Cu2p3/2 spectral region, (b2) Cu-LMM Auger transition and (b3) O1s spectral region. (c) C-In2O3 sample: (c1) In3d spectral region, (c2) In MNN Auger transition and (c3) O1s spectral region. (d) S-In2O3 sample: (d1) In3d spectral region, (d2) In MNN Auger transition and (d3) O1s spectral region. Fe2p spectral region for (e1) C-Fe2O3 and (e2) S-Fe2O3. Figure S3: H2 evolution with time by using CP-Cu/In mixed oxides under VIS light irradiation.

**Author Contributions:** Conceptualization, M.A. and A.D.; synthesis methodology and GC analytical techniques, F.N.; synthesis and spectroscopic characterization of photomaterials, D.M.S.M.; XPS analysis, N.D.; writing—original draft preparation, D.M.S.M.; writing—review and editing, M.A. and A.D.; supervision, A.D.; project administration, A.D.; funding acquisition, A.D. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received MIUR-IT funding. It was executed within the frame of a preliminary work of an international collaboration that has brought to a common EU-Project application.

**Acknowledgments:** The authors thank Roberto Comparelli (Istituto per i Processi Chimico-Fisici, Consiglio Nazionale delle Ricerche, c/o Dipartimento di Chimica, Università di Bari) and Teresa Sibillano (Istituto di Cristallografia, Consiglio Nazionale delle Ricerche, Bari) for performing and interpreting preliminary TEM and powder XRD measurements, respectively.

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


*5.7. Effect of Cold Fluid Temperature on First and Second Law Characteristics*

The variation in first and second law characteristics of hybrid nanofluid with OSshaped nanoparticles for various volume fractions and cold fluid temperatures is depicted in Figure 16. The cold fluid temperature is varied as 10 ◦C, 20 ◦C and 30 ◦C. The cold fluid at the lower temperature absorbs more heat and presents the higher temperature gradient and heat transfer rate. The pressure drop is not significantly affected by change in the cold fluid temperature. Therefore, the performance index increases as the cold fluid temperature decreases. With the increase in volume fraction, the dominance of the increase in heat transfer is superior to the increase in the pressure drop; therefore, the performance index increases with the increase in the volume fraction. The performance index of the Al2O3/Cu nanofluid with OS-shaped nanoparticles decreases by 12.5% and 24.99% when

the cold fluid temperature increases from 10 ◦C to 20 ◦C and 10 ◦C to 30 ◦C, respectively, for all volume fractions. With an increase in the volume fraction from 0.5% to 2.0%, the performance index increases by 9.43% for all cold fluid temperatures. The thermal entropy generation increases with the increase in volume fraction and decrease in the cold fluid temperature because the heat transfer rate increases with the increase in volume fraction and decrease in the cold fluid temperature. The friction entropy generation rate decreases with the increase in volume fraction despite an increase in pressure drop, because the increase in the average temperature with an increase in the volume fraction is dominant compared to an increase in pressure drop. Similar to the hot fluid temperature, the lower cold fluid temperature presents higher values of the friction entropy generation rate, and vice versa. The higher Bejan number is obtained at the lower cold fluid temperature because the dominance of the thermal entropy generation increase is higher than the friction entropy generation increase with a decrease in the cold fluid temperature. The thermal entropy generation increases and the friction entropy generation decreases with an increase in the volume fraction, which results in an increase in the Bejan number. The Bejan number of the Al2O3/Cu nanofluid with OS-shaped nanoparticles decreases by 1.16%, 1.12% and 1.07% as the cold fluid temperature increases from 10 ◦C to 20 ◦C, and that decreases by 2.66%, 2.59% and 2.45% as the cold fluid temperature increases from 10 ◦C to 30 ◦C for volume fractions of 0.5%, 1.0% and 2.0%, respectively. With the increase in volume fraction from 0.5% to 2.0%, the Bejan number of Al2O3/Cu nanofluid with OS-shaped nanoparticles increases by 0.63%, 0.73% and 0.85% for cold fluid temperatures of 10 ◦C, 20 ◦C and 30 ◦C, respectively. Garud et al. have proved that the performance of the heat exchanger is optimum for the lower mass flow rate of cold fluid [66]. The contributions of thermal and friction entropy generation rates for Al2O3/Cu with OS-shaped nanoparticles at various cold fluid temperatures are depicted in Figure 17. trend becomes steeper with the volume fraction at the higher mass flow rates. On the other side, with the increase in the hot fluid mass flow rate, the increase in the pressure drop is dominating compared to the increase in average temperature; therefore, the friction entropy generation rate is high at a higher mass flow rate and vice versa for all volume fractions. Based on the trends for the thermal and friction entropy generation rates with volume fractions and hot fluid mass flow rate, the Bejan number is evaluated. The Bejan number increases with the increase in volume fraction and decrease in the hot fluid mass flow rate. The thermal entropy generation increases, and the friction entropy generation decreases with the increase in volume fraction, which results in an increase in the Bejan number with an increase in the volume fraction. The thermal and friction entropy generation rates have both increased with the increase in the hot fluid mass flow rate but the increasing rate of the friction entropy generation rate is significantly higher than the thermal entropy generation rate. Therefore, the Bejan number decreases with the increase in the hot fluid mass flow rate for each volume fraction. The Bejan number of the Al2O3/Cu nanofluid with OS-shaped nanoparticles increases by 0.21%, 0.73% and 1.74% for hot fluid mass flow rates of 10 kg/h, 20 kg/h and 30 kg/h, respectively, as the volume fraction increases from 0.5% to 2.0%. The Bejan number of Al2O3/Cu with OS-shaped nanoparticles decreases by 3.06%, 2.89% and 2.57% as the hot fluid mass flow rate increases from 10 kg/h to 20 kg/h, and that decreases by 10.72%, 10.24% and 9.37% as the hot fluid mass flow rate increases from 10 kg/h to 30 kg/h for volume fractions of 0.5%, 1.0% and 2.0%, respectively. Soroush and Chamkha have also shown that the first and second law characteristics of single-particle nanofluids enhances as the volume fraction increases for all nanoparticle shapes [30]. The contributions of thermal and friction entropy generation rates for Al2O3/Cu with OS-shaped nanoparticles at various hot fluid mass flow rates are depicted in Figure 15.

dominant than the increase in pressure drop, hence the friction entropy generation rate decreases as the volume fraction increases for all hot fluid mass flow rates. This decreasing

*Symmetry* **2021**, *13*, x FOR PEER REVIEW 24 of 33

**Figure 14.** Effect of hot fluid mass flow rate and volume fraction on first and second law characteristics of hybrid nanofluid with OS-shaped nanoparticles. **Figure 14.** Effect of hot fluid mass flow rate and volume fraction on first and second law characteristics of hybrid nanofluid with OS-shaped nanoparticles.