Nanomaterials Design and Fabrication for Solar Energy Conversion and Photocatalysis Applications

The use of nanomaterials in solar energy conversion and photocatalytic degradation of environmental pollutants represents an opportunity to improve the performance, density, and ease of transportation in renewable resources. Among renewables resources, solar energy is considered as the largest exploitable resource, supplying the earth with energy in 1 hour equivalent to mankind’s total energy consumption in an entire year. Collecting and storing sunlight in chemical bonds (solar fuel) using photoelectrochemical water splitting (PEC) is a promising, a clean and sustainable way for hydrogen generation. Moreover, the photocatalytic process has great potential and high efficiency for removal of organic pollutants from water under direct natural sunlight irradiation. The aim of this project is to design, fabricate, characterize and performance enhancement of novel semiconductor materials that could efficiently harvest and store solar energy by splitting water to produce hydrogen and to perform dye degradation as well. The lack of suitable p-type photocathode has been considered and the focus of this work was to design and develop the new stable visible light absorbing photocathode materials. In pursuit of the stable photocathode, in this work YFeO3, which is a cheap and abundant material, with promising properties, and so was chosen as the photocathode in the development of the PEC cell. YFeO3 thin films were produced by spray pyrolysis technique onto fluorine-doped tin oxide film on glass. Results showed that YFeO3 photoelectrode has achieved a photocurrent of 0.6 mA cm-2 at 0.5 V vs. RHE and maximum of 0.41 μmol/cm2 of hydrogen has obtained as well. Similarly, to look for suitable and cheap materials for environmental remediation, Bi2WO6 thin films were produced by spray pyrolysis and aerosol-assisted chemical vapour deposition techniques. Results showed that the nanostructure and texture of the films can be controlled by controlling the deposition parameters. Moreover, photocatalytic degradation of rhodamine B (RhB) and methylene blue (MB) dyes have been successfully achieved. Finally, α-Fe2O3 films were fabricated as counter electrodes for dye-sensitized solar cells in order to compete for platinum counter electrode. These films were fabricated using aerosol-assisted chemical vapour deposition and spray pyrolysis techniques. The results showed that the performance of the samples prepared by aerosol-assisted chemical vapour deposition as a counter electrodes is higher than of the samples prepared by spray pyrolysis

Ketamine-based sedation use in mechanically ventilated critically ill patients with COVID-19: A multicenter cohort study

Backgrounds: Ketamine possesses analgesia, anti-inflammation, anticonvulsant, and neuroprotection properties. However, the evidence that supports its use in mechanically ventilated critically ill patients with COVID-19 is insufficient. The study's goal was to assess ketamine's effectiveness and safety in critically ill, mechanically ventilated (MV) patients with COVID-19. Methods: Adult critically ill patients with COVID-19 were included in a multicenter retrospective-prospective cohort study. Patients admitted between March 1, 2020, and July 31, 2021, to five ICUs in Saudi Arabia were included. Eligible patients who required MV within 24 hours of ICU admission were divided into two sub-cohort groups based on their use of ketamine (Control vs. Ketamine). The primary outcome was the length of stay (LOS) in the hospital. P/F ratio differences, lactic acid normalization, MV duration, and mortality were considered secondary outcomes. Propensity score (PS) matching was used (1:2 ratio) based on the selected criteria. Results: In total, 1,130 patients met the eligibility criteria. Among these, 1036 patients (91.7 %) were in the control group, whereas 94 patients (8.3 %) received ketamine. The total number of patients after PS matching, was 264 patients, including 88 patients (33.3 %) who received ketamine. The ketamine group's LOS was significantly lower (beta coefficient (95 % CI): −0.26 (−0.45, −0.07), P = 0.008). Furthermore, the PaO2/FiO2 ratio significantly improved 24 hours after the start of ketamine treatment compared to the pre-treatment period (6 hours) (124.9 (92.1, 184.5) vs. 106 (73.1, 129.3; P = 0.002). Additionally, the ketamine group had a substantially shorter mean time for lactic acid normalization (beta coefficient (95 % CI): −1.55 (−2.42, −0.69), P 0.01). However, there were no significant differences in the duration of MV or mortality. Conclusions: Ketamine-based sedation was associated with lower hospital LOS and faster lactic acid normalization but no mortality benefits in critically ill patients with COVID-19. Thus, larger prospective studies are recommended to assess the safety and effectiveness of ketamine as a sedative in critically ill adult patients

Fracture Resistance of Primary Zirconia Crowns: An In Vitro Study

In this study, we evaluated the fracture resistance of three commercially available prefabricated primary zirconia crowns and their correlation with dimensional variance. Methods: a total of 42 zirconia crowns were selected from three companies, (1) NuSmile primary zirconia crowns, (2) Cheng Crowns zirconia, and (3) Sprig EZ crowns. The crowns were divided into two groups based on their location in the oral cavity and further divided into subgroups based on the brand. All of the samples were subjected to fracture tests using a universal testing machine. Results: the mean load observed was highest with Cheng Crowns zirconia anterior crowns (1355 ± 484) and the least load was seen with Sprig EZ anterior crowns with a mean load of 339 ± 94. The mean load observed was highest with Cheng Crowns zirconia posterior crowns (1990 ± 485) followed by NuSmile posterior crowns and the least load was seen with Sprig EZ posterior crowns with a mean load of 661 ± 184. Conclusion: the Cheng crowns showed the highest fracture resistance amongst all three groups. Overall, the zirconia crowns (anterior and posterior) tested showed optimum mechanical properties to withstand the masticatory forces

Effect of inadequate ferrule segment location on fracture resistance of endodontically treated teeth

Introduction: The circumferential 2 mm ferrule during the fabrication of the crown is strongly advocated for the long-term clinical success. During the routine clinical practice, the dentist encounters the endodontically treated tooth (ETT) with inadequacy of the ferrule in some segment due to caries, abrasion, and erosions. The aim of this in vitro study was to investigate the consequence of inadequate segmental ferrule location on fracture strength of the root canal-treated anterior and posterior teeth. Materials and Methods: Fifty each maxillary canine and mandibular premolar intact human teeth were root canal treated and sectioned at 2 mm above the cementum-enamel junction. The teeth samples were divided into 5 groups of 10 each. The G-I and G-V samples had the 360° ferrule and complete absence of the ferrule, respectively. The G-II had the inadequate ferrule on the palatal surface, while G-III and G-IV had inadequate ferrule at buccal and proximal area. Teeth samples were subsequently restored with glass-reinforced fiber post, composite core, and full veneer metal crown. The samples were tested with universal testing machine under static load to record the fracture resistance. The acquired data were subjected to ANOVA and Tukey's post hoc statistical analysis. Results: The G-I with circumferential ferrule showed the higher fracture resistance. The teeth samples with lack of the ferrule had the least fracture resistance. Among the segmental absence of ferrule, teeth samples with lack of the proximal ferrule were least affected. Deficiency of a ferrule on the lingual wall significantly affected the fracture strength in both anterior and posterior ETT. Conclusions: The ETT with sectional inadequacy of the ferrule is significantly more effective in resisting the fracture in comparison to the complete absence of the ferrule

Investigation of thermoelectric properties of novel cubic phase SnSe: a promising material for thermoelectric applications

The novel cubic structured SnSe (π-SnSe), with narrow band-gap and substantial phonon restraining effect, is considered a perspective energy storage material for futuristic applications. In this study, we explore the thermoelectric properties of π-SnSe in the framework of density functional theory and is therefore believed to be the first report of its kind. As a prerequisite for the calculations of thermoelectric properties, the electronic structure of π-SnSe was determined at the level of modified Becke-Johnson potential. The calculated bandgap of magnitude 0.97 eV is found to be in good agreement with recently reported experimental results of energy band-gap. Our calculations for electrical conductivity (σ/τ) show that the highest values occur at modest doping level magnitude to 3.6 × 1019/Ωms for p-type doping and 1.54 × 1020/Ωms for n-type doping and was found to be decreasing linearly with increasing temperature. Similarly, it is found that π-SnSe exhibit high Seebeck coefficient at low temperature, observing a drastic degradation in the span of 2292 μK/V to 444.3 μK/V with increasing temperature ranging from 200 to 900 K, respectively. In consequence, a notable reduction in the values of thermoelectric power factor (PF) and figure of merit (ZT) has also been observed with increase in temperature. The maximum value of PF was documented to be 8.77 × 1010 W/mK2s at 200 K. An exceptionally high and record ZT value of ∼1 was obtained at 200 K which is superior to orthorhombic structure SnSe (polycrystalline and bulk). Thus our study point to cubic phase SnSe as an avenue for the next generation thermoelectric materials for a wide range of operational temperature devices

COVID-19 Linked Social Stigma Among Arab Survivors: A Cross-Sectional Experiences from the Active Phase of the Pandemic

Norah Abdullah Bazek Madkhali,1 AbdulRahman Ameri,2 Zakariya Yaqoob Al-Naamani,3 Bushra Alshammari,4 Mohammed Abdullah Bazek Madkhali,5 Arshad Jawed,1 Faten Alfaifi,1 Amani Ali Kappi,1 Shafiul Haque6 1Department of Nursing, College of Nursing, Jazan University, Jazan, 45142, Saudi Arabia; 2Mohammed bin Nasser Hospital, MOH, Jazan, Saudi Arabia; 3Armed Forces Medical Services School (AFMSS), Muscat, Oman; 4Department of Medical-Surgical Nursing, College of Nursing, University of Hail, Hail, Saudi Arabia; 5Al Tuwal General Hospital, MOH, Jazan, Saudi Arabia; 6Research and Scientific Studies Unit, College of Nursing, Jazan University, Jazan, 45142, Saudi ArabiaCorrespondence: Norah Abdullah Bazek Madkhali, Department of Nursing, College of Nursing, Jazan University, Jazan, 45142, Saudi Arabia, Email [email protected]; [email protected]: This study aimed to explore the magnitude and variability of the disease-linked stigma among COVID-19 survivors and their experiences of social stigma, coping strategies, contextual challenges, and preferences for support.Methods: An Arabic version of the social stigma survey questionnaire was designed and validated to obtain socio-demographic characteristics and quantitative measures of stigma encountered by the survivors. 482 COVID-19 survivors completed the survey, and the data were analyzed using descriptive statistics and thematic analysis.Results: The results of this study revealed the prevalence of high levels of both perceived external stigma and enacted stigma among participants. Enacted and Internalized stigma were associated with survivors’ educational background/ status. The participants suggested three levels of support: organizational, social, and personal. Establishing an online stigma reduction program and national psychological crisis interventions at the organizational level. It is crucial to assist coping mechanisms and societal reintegration techniques at the social level.Conclusion: These results provide valuable insights for holistic health policy formation and preparedness strategies for future pandemics, helping survivors promote health and reintegrate into society, where stigma reduction and psychological crisis interventions are underdeveloped.Keywords: COVID-19, survivor, stigma, SARS-CoV-2, pandemic, Saudi Arabi

Investigations of electronic and thermoelectric properties of half-Heusler alloys XMgN (X = Li, Na, K) by first-principles calculations

The rapid depletion of the fossil fuels and their environment repercussion can be resolved wisely by exploring the efficient and sustainable materials which have the ability to convert waste heat into electricity. Half-Heusler materials are also considered one of the promising class for the thermoelectric applications. In this paper, the investigations on the thermoelectric properties of half-Heusler compounds, XMgN (X = Li, Na, K) are reported. The study is carried out within full potential linearised augmented plane wave plus local orbital approach (FP-LAPW + lo) in conjunction with the semi-empirical Boltzmann theory. To incorporate exchange-correlation energy/potential part, Perdew and Wang (PW) suggested local density approximation (LDA), parameterized generalized gradient approximation (GGA) by Perdew-Berke-Ernzerhof (PBE) and the modified Becke-Johnson (mBJ) exchange potential by Trans-Blaha are used. Our electronic band structure calculations show that the KMgN is indirect band gap material, whereas LiMgN and NaMgN demonstrate their direct electronic band gap structure. To comprehend their thermoelectric character, the calculations of the Seebeck coefficient, electrical conductivity, thermal conductivity, power factor and figure of merit (ZT) are carried out at temperatures of values 300 K, 600 K, and 900 K. From our calculations, the optimal value of Seebeck coefficient for the all three materials although was found at 300 K, the results of the Seebeck coefficient for the LiMgN were found more good as compared to NaMgN and KMgN and in coordination with the Lee et al. study as well. Similarly, electrical conductivity results endorse the Wiedemann-Franz law. The calculated results of the ZT parameter (ZT ~ 1) for the all three materials (LiMgN, NaMgN, and KMgN) revealing that the investigated materials have a potential to be used for thermoelectric applications

Rupture characteristics of a small-sized earthquake (M W 4.2), onshore the south Red Sea, Saudi Arabia

The present study is based on the use of Empirical Green's Function (EGF) deconvolution technique to retrieve the slip distribution of the 2014 M w 4.2 Jizan earthquake, Saudi Arabia. Two datasets of complex Source Time Functions (STFs) were retrieved using two appropriate EGF events. We inverted the STF datasets to recover the slip distribution over both nodal planes, using the Bayesian modeling followed by a linear least-squares method. The inversion was performed assuming both planes as the fault plane and examined the goodness of fit for each nodal plane. Based on a series of finite-source inversions using different rupture velocities, we resolved the rupture velocity at 2.7–2.8 km/s and the fault plane of NNW trending; paralleling the Red Sea rift. Using the estimated rupture velocities and the preferred fault plane, we imaged quite similar slip models, exhibiting two slip patches located to the updip and downdip directions from the hypocentre. The spatiotemporal slip distributions revealed a complex rupture history of such small-sized earthquake is likely to that reported for large-sized earthquakes. A seismic moment of 2.8–3.2E+15 NM and a corresponding moment magnitude of 4.2-4-3 are inferred. The stress drops obtained from the slip distribution models were 2.2–2.5 MPa; indicating a typical value that characterized the plate-boundary earthquakes

Encapsulation of Lovastatin in Zein Nanoparticles Exhibits Enhanced Apoptotic Activity in HepG2 Cells

Research on statins highlights their potent cytotoxicity against cancer cells and their potential for cancer prevention. The aim of the current study was to examine whether loading lovastatin (LVS) in zein (ZN) nanoparticles (NPs) would potentiate the anti-proliferative effects of LVS and enhance its proliferation-inhibiting activity in HepG2 cells. LVS-ZN NPs were prepared and showed excellent characteristics, with respect to their particle size, zeta potential, diffusion, and entrapment efficiency. In addition, they showed the most potent anti-proliferative activity against HepG2 cells. ZN alone showed an observable anti-proliferative that was significantly higher than that of raw LVS. Furthermore, LVS uptake by HepG2 cells was greatly enhanced by the formulation in ZN. A cell cycle analysis indicated that LVS induced a significant cell accumulation in the G2/M and pre-G phases. In this regard, the LVS–ZN NPs exhibited the highest potency. The accumulation in the pre-G phase indicated an enhanced pro-apoptotic activity of the prepared formula. The cells incubated with the LVS-ZN NPs showed the highest percentage of cells with annexin-V positive staining. In addition, the same incubations showed the highest content of caspase-3 enzyme in comparison to raw LVS or ZN. Thus, the loading of LVS in ZN nanoparticles enhances its anti-proliferative activity against HepG2 cells, which is attributed, at least partly, to the enhanced cellular uptake and the induction of apoptosis