Enhanced solar-driven photoelectrochemical water splitting using nanoflower Au/CuO/GaN hybrid photoanodes.

Harnessing solar energy for large-scale hydrogen fuel (H2) production shows promise in addressing the energy crisis and ecological degradation. This study focuses on the development of GaN-based photoelectrodes for efficient photoelectrochemical (PEC) water splitting, enabling environmentally friendly H2 production. Herein, a novel nanoflower Au/CuO/GaN hybrid structure was successfully synthesized using a combination of methods including successive ionic layer adsorption and reaction (SILAR), RF/DC sputtering, and metal-organic chemical vapour deposition (MOCVD) techniques. Structural, morphological, and optical characteristics and elemental composition of the prepared samples were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis spectroscopy, and energy-dispersive X-ray (EDX) spectroscopy, respectively. PEC and electrochemical impedance measurements were performed for all samples. The nanoflower Au/CuO/GaN hybrid structure exhibited the highest photocurrent density of ∼4 mA cm-2 at 1.5 V vs. RHE in a Na2SO4 electrolyte with recorded moles of H2 of about 3246 µmol h-1 cm-2. By combining these three materials in a unique structure, we achieved improved performance in the conversion of solar energy into chemical energy. The nanoflower structure provides a large surface area and promotes light absorption while the Au, CuO, and GaN components contribute to efficient charge separation and transfer. This study presents a promising strategy for advancing sustainable H2 production via efficient solar-driven water splitting.

Outcomes of Left Main Revascularization in Patients with Anemia: Gulf Left Main Registry.

INTRODUCTION: The aim of this study was to evaluate the effects of baseline anemia and anemia following revascularization on outcomes in patients with unprotected left main coronary artery (ULMCA) disease. METHODS: This was a retrospective, multicenter, observational study conducted between January 2015 and December 2019. The data on patients with ULMCA who underwent revascularization through percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) were stratified by the hemoglobin level at baseline into anemic and non-anemic groups to compare in-hospital events. The pre-discharge hemoglobin following revascularization was categorized into very low (<80 g/L for men and women), low (≥80 and ≤119 g/L for women and ≤129 g/L for men), and normal (≥130 g/L for men and ≥120 g/L for women) to assess impact on follow-up outcomes. RESULTS: A total of 2,138 patients were included, 796 (37.2%) of whom had anemia at baseline. A total of 319 developed anemia after revascularization and moved from being non-anemic at baseline to anemic at discharge. There was no difference in hospital major adverse cardiac and cerebrovascular event (MACCE) and mortality between CABG and PCI in anemic patients. At a median follow-up time of 20 months (interquartile range [IQR]: 27), patients with pre-discharge anemia who underwent PCI had a higher incidence of congestive heart failure (CHF) (p < 0.0001), and those who underwent CABG had significantly higher follow-up mortality (HR: 9.85 (95% CI: 2.53-38.43), p = 0.001). CONCLUSION: In this Gulf LM study, baseline anemia had no impact upon in-hospital MACCE and total mortality following revascularization (PCI or CABG). However, pre-discharge anemia is associated with worse outcomes after ULMCA disease revascularization, with significantly higher all-cause mortality in patients who had CABG, and a higher incidence of CHF in PCI patients, at a median follow-up time of 20 months (IQR: 27).

Enhanced and tunable femtosecond nonlinear optical properties of pure and nickel-doped zinc oxide films.

The nonlinear optical properties of pure ZnO and Ni-doped ZnO thin films are explored using the Z-scan technique at different input laser intensities and an excitation wavelength of 750 nm by 100 fs laser pulses. The pure ZnO and Ni-doped ZnO thin films were prepared by radio frequency magnetron sputtering at room temperature. A scanning electron microscope equipped with energy-dispersive x-ray spectroscopy was used to measure the thickness and composition of the thin films, while a UV-visible spectrophotometer was used to measure the linear optical properties. The structure of the thin films was measured using x-ray diffraction. Saturable absorption (SA) was observed in the pure ZnO thin film, while Ni-doped ZnO illustrated a combination of SA and reverse SA (RSA). The nonlinear absorption coefficient (ß) and nonlinear refractive index (n2) of both pure ZnO and Ni-doped ZnO thin films were found to be input laser intensity dependent. As the input laser intensity increased, the nonlinear absorption coefficient and the nonlinear refractive index of both samples increased. An enhancement of two times in the nonlinear refractive index was observed for the Ni-doped ZnO thin film compared to the pure ZnO thin film. The optical limiting behavior of pure ZnO and Ni-doped ZnO thin films was investigated, and the data demonstrated that Ni-doped ZnO thin film is a good candidate for optical limiter applications due to the presence of strong RSA.

Optimized Aluminum Reflector for Enhancement of UVC Cathodoluminescence Based-AlGaN Materials with Carbon Nanotube Field Emitters.

The far ultraviolet C (UVC) light sources based on carbon nanotube (CNT) field emitters as excitation sources have become promising light sources for sterilization, disinfection, and water purification. However, the low light extraction efficiency of UVC-CNT light sources still hinders the practical application of these structures. Herein, we report an optimized aluminum (Al) reflector to enhance the light extraction efficiency of UVC-CNT light sources. Optical analysis of UVC-CNT light sources covered by the Al reflectors with various thicknesses ranging from 30 to 150 nm was performed to realize the optimized reflector. The UVC-CNT light sources exhibit the highest light extraction efficiency when the Al reflector layer has an optimized thickness of 100 nm. For comparison, the cathodoluminescence (CL) spectra were recorded for UVC-CNT light sources with and without the optimized Al reflector. The measured light output power and the estimated power efficiency of the UVC-CNT light-source-tube with Al reflector were enhanced by about 27 times over the reference. This enhancement is mainly attributed to the outstanding reflection effect of the Al reflector.

STEMI and COVID-19 Pandemic in Saudi Arabia.

The COVID-19 pandemic had significant impact on health care worldwide which has led to a reduction in all elective admissions and management of patients through virtual care. The purpose of this study is to assess changes in STEMI volumes, door to reperfusion, and the time from the onset of symptoms until reperfusion therapy, and in-hospital events between the pre-COVID-19 (PC) and after COVID-19 (AC) period. All acute ST-segment elevation myocardial infarction (STEMI) cases were retrospectively identified from 16 centers in the Kingdom of Saudi Arabia during the COVID-19 period from January 01 to April 30, 2020. These cases were compared to a pre-COVID period from January 01 to April 30, 2018 and 2019. One thousand seven hundred and eighty-five patients with a mean age 56.3 (SD ± 12.4) years, 88.3% were male. During COVID-19 Pandemic the total STEMI volumes was reduced (28%, n = 500), STEMI volumes for those treated with reperfusion therapy was reduced too (27.6%, n= 450). Door to balloon time < 90 minutes was achieved in (73.1%, no = 307) during 2020. Timing from the onset of symptoms to the balloon of more than 12 hours was higher during 2020 comparing to pre-COVID 19 years (17.2% vs <3%, respectively). There were no differences between the AC and PC period with respect to in-hospital events and the length of hospital stay. There was a reduction in the STEMI volumes during 2020. Our data reflected the standard of care for STEMI patients continued during the COVID-19 pandemic while demonstrating patients delayed presenting to the hospital.

Impact of global longitudinal strain on left ventricular remodeling and clinical outcome in patients with ST-segment elevation myocardial infarction (STEMI).

BACKGROUND: Predicting left ventricle (LV) remodeling is important for outcome prediction in patients with ST-segment elevation myocardial infarction (STEMI). Novel echocardiographic techniques may be beneficial for those patients. OBJECTIVES: We hypothesized that the semiautomated calculation of baseline global longitudinal strain (GLS) can predict LV remodeling and 6-month clinical outcomes in these patients. METHODS: During the period from March to December 2018, 130 patients with successful reperfusion of STEMI were prospectively included. Within 48 hours, patients underwent a baseline GLS study with follow-up study at 6 months. Patients were divided into two groups: group I: patients who showed adverse LV remodeling and group II: patients who did not. The endpoint was a composite of cardiovascular mortality, readmission due to heart failure, and urgent revascularization. RESULTS: The mean baseline GLS changed from -13.1 ± 3.5% for group I and -16.8 ± 3.1% for group II, to -10.2 ± 4.7% and -12.6 ± 3.1%, respectively, at 6-month follow-up. ROC analysis demonstrated a cutoff value of baseline GLS > -12.5% predicted LV remodeling with 64.5% sensitivity and 89% specificity (AUC 0.797, 95% CI 0.690-0.904). Multivariate logistic regression analysis model using 6-month MACEs occurrence as a dependent factor showed baseline GLS value> -12.5% to be the only significant independent predictor MACEs occurrence (OR 0.704, 95% CI 0.597-0.829, P < .001). Linear regression analysis showed that for every point estimate deterioration of baseline GLS, there was a significant corresponding 2.55 mL increase in LVEDV at 6-month follow-up (CI -4.501 to -0.612, P = .01). CONCLUSION: GLS measurement can predict remodeling and adverse clinical events in STEMI patients.

The predictive value of global longitudinal strain on late infarct size in patients with anterior ST-segment elevation myocardial infarction treated with a primary percutaneous coronary intervention.

Late infarct size (IS) after ST segment elevation myocardial infarction (STEMI) is a determinant of subsequent mortality. Late Gadolinium enhancement in cardiac magnetic resonance imaging (LGE-CMRI) is the gold standard for IS measurement, however, it is not readily accessible in many areas. We aimed to evaluate the value of early baseline 2D-echocardiographic global longitudinal strain (GLS) for the prediction of late IS after STEMI. From October 2017 to July 2018, we studied 100 patients with their 1st anterior STEMI treated with primary percutaneous coronary intervention. Baseline GLS calculation was performed within 48 h of admission. In addition, the average value of the nine segments supplied by the LAD was assessed separately (anterior GLS). Infarct size was assessed 3 months later using LGE-CMRI, and large infarcts were defined as ≥ 20% LV myocardium covered by scar. Based on CMRI, we defined two groups; 57 patients with large infarcts (group I) and 43 patients with small infarcts (group II). Both groups were matched in all baseline demographics and risk factors. There was a good and significant correlation between GLS and late IS (r = - 0.840, P < 0.001). This correlation was even higher for anterior GLS (r = - 0.867, P < 0.001). ROC analysis showed a cut-off point of GLS (- 13%) that identified large late IS with a sensitivity and specificity of 66.7% and 88.4% respectively (AUC = 0.85). For anterior GLS, the cut-off point was - 9.6% (Sensitivity 94%, specificity 86%, AUC = 0.9). We concluded that baseline GLS significantly predicts late IS after anterior STEMI.

Outstanding features of Cu-doped ZnS nanoclusters.

ZnS and their Cu-doped nanoclusters (NCs) were synthesized successfully using the wet chemical route with different Cu content. The crystalline structure was investigated using x-ray powder diffraction which assured the single-phase formation in cubic symmetry. High-resolution transmission electron microscope indicated the microstructure of NCs with a size ranging from 2-4 nm. A butterfly hysteresis (M-H) loop was observed at room temperature with large values of coercivity for the Cu content of x = 0.05. Photoluminescence emission spectra were recorded from 500-615 nm for pure and Cu-doped ZnS NCs at a 350 nm excitation wavelength. The sample exhibited green fluorescence bands peaking at 535, 544, 552.5, 558.2, and 560.6 nm, which confirmed the characteristic feature of Zn2+ as luminescent centers in the lattice. The additional yellow and orange emissions are due to defect levels or/and impurity centers. The dielectric constant as well as the conductivity values increased with increasing Cu content.

Numerical Analysis of the Temperature Impact on Performance of GaN-Based 460-nm Light-Emitting Diode.

The influence of temperature on the characteristics of a GaN-based 460-nm light-emitting diode (LED) prepared on sapphire substrate was simulated using the SiLENSe and SpeCLED software programs. High temperatures impose negative effects on the performance of GaN-based LEDs. As the temperature increases, electrons acquire higher thermal energies, and therefore LEDs may suffer more from high-current loss mechanisms, which in turn causes a reduction in the radiative recombination rate in the active region. The internal quantum efficiency was reduced by about 24% at a current density of 35 A/cm2, and the electroluminescence spectral peak wavelength was redshifted. The LED operated at 260 K and exhibited its highest light output power of ~317.5 mW at a maximum injection current of 350 mA, compared to 212.2 mW for an LED operated at 400 K. However, increasing temperature does not cause a droop in efficiency under high injection conditions. The peak efficiency at 1 mA of injection current decreases more rapidly by ~15% with increasing temperature from 260 to 400 K than the efficiency at high injection current of 350 mA by ~11%.

CdO nanorods and Cd(OH)2/Ag core/satellite nanorods: Rapid and efficient sonochemical synthesis, characterization and their magnetic properties.

We have designed an efficient and direct sonochemical method for the facile synthesis of Cd(OH)2, CdO, and Cd(OH)2/Ag core/satellite nanorods. A Cd(OH)2 nanorod was synthesized with a one-pot, environmentally-friendly aqueous sonochemical reaction, followed by calcination at 500°C to produce CdO nanorods. Thirty minutes of re-ultrasonicated CdO nanorods in the presence of the Ag precursor was sufficient for phase transformation from the cubic structure of CdO to the monoclinic crystalline structure of Cd(OH)2, accompanied by deposition of Ag nanodots on the surface to form Cd(OH)2/Ag core/satellite nanorods. X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, energy-dispersive spectroscopy, N2 Brunauer-Emmett-Teller adsorption-desorption, and Fourier-transform infrared spectroscopy measurements confirmed the successful formation of the various phases and the unique morphology of the nanorods/satellites. We also measured the magnetic properties using a vibrating sample magnetometer at room temperature, and the produced nanorods showed weak unsaturated ferromagnetic properties with a magnetic moment values of 0.105 and 0.076emu/g for CdO and Cd(OH)2/Ag NRs, respectively. In conclusion, our one-pot, cost-effective, sonochemical approach holds promise for the synthesis of various oxides and core/satellite nanoparticles.

Fibrinolytic therapy in patients with ST-segment elevation myocardial infarction: Accelerated versus standard Streptokinase infusion regimen.

Introduction: Timely fibrinolysis for acute ST-segment elevation myocardial infarction (STEMI) reduces infarct size and hence preserves LV function and reduces mortality. Optimal regimen of streptokinase (SK) infusion in such patients is a matter of interest. The current study aimed to compare efficacy and safety of accelerated SK infusion regimen in patients with STEMI versus the standard one. Methods: One hundred consecutive STEMI patients were randomly allocated into one of 2 groups: group I (50 patients) who received accelerated SK regimen (1.5 million units over 30 minutes) and group II (50 patients) received standard SK regimen (1.5 million units over 60 minutes). Efficacy was evaluated non-invasively using clinical (chest pain), ECG (resolution of ST segment) and laboratory tests (earlier and higher peaking of cardiac troponin I). Safety was evaluated by assessment of multiple in-hospital adverse events. Results: Both groups were statistically matched in all baseline criteria. There was a significant difference between both groups regarding each parameter of successful reperfusion in favor of accelerated regimen. When all these parameters were combined, 31 patients (62%) had successful reperfusion in group I versus 19 patients (38%) in group II (P = 0.016). We did not report any significant difference between both groups regarding in-hospital mortality, in-hospital heart failure, major bleeding, hypotension or allergic reaction to SK. Mean pre-discharge ejection fraction was higher in group I than group II (50.9 ±â€…6.6% versus 47.3 ±â€…4.6%, P = 0.002). Conclusion: Accelerated regimen of SK infusion is safe and effective method of reperfusion in patients with STEMI.

Effect of Sapphire Substrate Thickness on the Characteristics of 450 nm InGaN/GaN Multi-Quantum Well Light-Emitting Diodes.

450 nm InGaN/GaN multi-quantum well (MQW) ligth-emitting diodes (LEDs) prepared on sapphire substrate with different thicknesses were fabricated and characterized. By thinning the sapphire substrate to 50 µm, it was found that the LED exhibited the highest light output power of ~48 mW under high injection current of 50 mA, improved by about 35% compared to that with 200 µm-thick sapphire without increasing the operating voltage. The electroluminescence intensity was increased and the spectral peak wavelength was blue-shifted, because the wafer bowing-induced mechanical stress alters the piezoelectric field in the InGaN/GaN MQW active region of the LED. The internal quantum efficiency was also improved by about 10% at an injection current of 50 mA. Moreover, the external quantum efficiency and light extraction efficiency were optimized because of enhanced light output intensity. The results confirmed that sapphire substrate thinning effectively alters the piezoelectric field in the InGaN/GaN active region, and hence increases both of the effective band gap and the probability of radiative recombination.

Nano-scale SiO2 patterned n-type GaN substrate for 380 nm ultra violet light emitting diodes.

380 nm Ultraviolet (UV) light emitting diodes (LEDs) were grown on patterned n-type GaN substrate (PNS). Wet etched self-assembled indium tin oxide (ITO) nano clusters serves as dry etching mask for converting the SiO2 layer grown on n-GaN template into SiO2 nano dots by inductively coupled plasma etching. In the pre-experiment, crystal quality and optical properties of n-GaN were greatly improved by applying PNS process. In this work, etch-pits density (EPD) method confirmed that PNS with SiO2 nano dots have superior crystalline properties. Thus Reference LED without PNS, 1-step PNS LEDs with SiO2 nano dots size were 200 nm, 250 nm, 300 nm and 300 nm 2-step PNS LED were fabricated. LEDs show almost the same operating voltage of about 3.4 V at an injection current of 50 mA. Light intensity was enhanced by ~2.1 times and 3.2 times for 300 nm 1-step and 300 nm 2-step PNS, respectively. FDTD simulation results show a similar tendency. As a result, PNS promotes epitaxial lateral overgrowth (ELOG) for defect reduction as well as act as a light scattering point.

Improvement in crystal quality and optical properties of n-type GaN employing nano-scale SiO2 patterned n-type GaN substrate.

n-type GaN epitaxial layers were regrown on the patterned n-type GaN substrate (PNS) with different size of silicon dioxide (SiO2) nano dots to improve the crystal quality and optical properties. PNS with SiO2 nano dots promotes epitaxial lateral overgrowth (ELOG) for defect reduction and also acts as a light scattering point. Transmission electron microscopy (TEM) analysis suggested that PNS with SiO2 nano dots have superior crystalline properties. Hall measurements indicated that incrementing values in electron mobility were clear indication of reduction in threading dislocation and it was confirmed by TEM analysis. Photoluminescence (PL) intensity was enhanced by 2.0 times and 3.1 times for 1-step and 2-step PNS, respectively.

Cytotoxicity, genotoxicity, and metal release in patients with fixed orthodontic appliances: a longitudinal in-vivo study.

INTRODUCTION: Treatment with fixed orthodontic appliances in the corrosive environment of the oral cavity warrants in-vivo investigations of biocompatibility. METHODS: Eighteen control and 28 treated subjects were evaluated longitudinally. Four combinations of brackets and archwires were tested. Buccal mucosa cell samples were collected before treatment, and 3 and 6 months after appliance placement. The cells were processed for cytotoxicity, genotoxicity, and nickel and chromium contents. RESULTS: In the treatment group, buccal mucosa cell viability values were 8.1% at pretreatment, and 6.4% and 4.5% at 3 and 6 months, respectively. The composite score, a calculated DNA damage value, decreased from 125.6 to 98.8 at 6 months. Nickel cellular content increased from 0.52 to 0.68 and 0.78 ng per milliliter, and chromium increased from 0.31 to 0.41 and 0.78 ng per milliliter at 3 and 6 months, respectively. Compared with the control group, the treated subjects showed significant differences for DNA damage and chromium content at 3 months only. CONCLUSIONS: Fixed orthodontic appliances decreased cellular viability, induced DNA damage, and increased the nickel and chromium contents of the buccal mucosa cells. Compared to the control group, these changes were not evident at 6 months, possibly indicating tolerance for or repair of the cells and the DNA.

Use of 3-dimensional surface acquisition to study facial morphology in 5 populations.

INTRODUCTION: The aim of this study was to assess the use of 3-dimensional facial averages for determining morphologic differences from various population groups. METHODS: We recruited 473 subjects from 5 populations. Three-dimensional images of the subjects were obtained in a reproducible and controlled environment with a commercially available stereo-photogrammetric camera capture system. Minolta VI-900 (Konica Minolta, Tokyo, Japan) and 3dMDface (3dMD LLC, Atlanta, Ga) systems were used. Each image was obtained as a facial mesh and orientated along a triangulated axis. All faces were overlaid, one on top of the other, and a complex mathematical algorithm was performed until average composite faces of 1 man and 1 woman were achieved for each subgroup. These average facial composites were superimposed based on a previously validated superimposition method, and the facial differences were quantified. RESULTS: Distinct facial differences were observed among the groups. The linear differences between surface shells ranged from 0.37 to 1.00 mm for the male groups. The linear differences ranged from 0.28 and 0.87 mm for the women. The color histograms showed that the similarities in facial shells between the subgroups by sex ranged from 26.70% to 70.39% for men and 36.09% to 79.83% for women. The average linear distance from the signed color histograms for the male subgroups ranged from -6.30 to 4.44 mm. The female subgroups ranged from -6.32 to 4.25 mm. CONCLUSIONS: Average faces can be efficiently and effectively created from a sample of 3-dimensional faces. Average faces can be used to compare differences in facial morphologies for various populations and sexes. Facial morphologic differences were greatest when totally different ethnic variations were compared. Facial morphologic similarities were present in comparable groups, but there were large variations in concentrated areas of the face.

Facial morphologies of an adult Egyptian population and an adult Houstonian white population compared using 3D imaging.

OBJECTIVE: To compare the facial morphologies of an adult Egyptian population with those of a Houstonian white population. MATERIALS AND METHODS: The three-dimensional (3D) images were acquired via a commercially available stereophotogrammetric camera capture system. The 3dMDface System photographed 186 subjects from two population groups (Egypt and Houston). All of the participants from both population groups were between 18 and 30 years of age and had no apparent facial anomalies. All facial images were overlaid and superimposed, and a complex mathematical algorithm was performed to generate a composite facial average (one male and one female) for each subgroup (EGY-M: Egyptian male subjects; EGY-F: Egyptian female subjects; HOU-M: Houstonian male subjects; and HOU-F: Houstonian female subjects). The computer-generated facial averages were superimposed based on a previously validated superimposition method, and the facial differences were evaluated and quantified. RESULTS: Distinct facial differences were evident between the subgroups evaluated, involving various regions of the face including the slant of the forehead, and the nasal, malar, and labial regions. Overall, the mean facial differences between the Egyptian and Houstonian female subjects were 1.33 +/- 0.93 mm, while the differences in Egyptian and Houstonian male subjects were 2.32 +/- 2.23 mm. The range of differences for the female population pairings and the male population pairings were 14.34 mm and 13.71 mm, respectively. CONCLUSIONS: The average adult Egyptian and white Houstonian face possess distinct differences. Different populations and ethnicities have different facial features and averages.

Use of FT-Raman Spectroscopy to Determine the Degree of Polymerization of Dental Composite Resin Cured with a New Light Source.

OBJECTIVES: To use the FT-Raman spectroscopy for evaluation the degree of polymerization of dental composite as a result of photo curing with a new light source in comparison to the conventional halogen light. MATERIALS AND METHODS: In this study a new light source, based on a metal-halide lamp (TOPSPOT G12) was developed at NRC-Egypt for curing dental composites. Two groups of 108 composite samples each were cured using both the new light source and a conventional halogen source, as a control source. Different samples' sizes (2x2, 3x3 and 6x3 mm(2)) were cured for different periods of time (2, 4, 8, 12, 20, and 40 seconds). The spectroscopic data were analyzed statistically by ANOVA and Duncan's multiple range test (P< .05). RESULTS: The results showed that the samples cured by the new metal-halide source produced higher polymerization rates than those cured by the halogen source. The polymerization rate was directly proportional to the exposure time and inversely proportional to the sample size, irrespective to the light source used. The results also showed that 12 seconds of metal-halide light curing produced polymerization rate comparable to or even higher than that produced by 40 seconds halogen light curing. CONCLUSIONS: The new light source produced a satisfactory degree of polymerization in a remarkable shorter curing time and it can be recommended for clinical use.