Exploring the Absorption Spectra of an Ultra-Wideband Metamaterial Absorber in the Visible and Near-Infrared Regions.

This paper investigates the absorption spectra of a plasmonic metamaterial absorber in the visible and near-infrared regimes by utilizing a metal-dielectric-metal (MDM) functional stack. A periodic metal-dielectric cap is introduced on top of a metallic substrate to excite surface plasmon modes. The shape of this cap and the glass coating modifies the absorbance bandwidth. Although the circular cap exhibits less broadening in the absorbance than the square one, the circular cap's glass coating boosts the bandwidth's expansion in the near-infrared region to about 1.65 µm. In the visible and near-infrared regimes, absorption bandwidth and spectral ratio can be tailored by modifying four distinct structural parameters. The finding shows that one can achieve an ultra-broad bandwidth that extends from 0.3 µm to 1.65 µm at 90% absorbance. The thickness of the top titanium layer, the silicon dioxide spacer thickness, the Ti-SiO2 cap diameter, and the sliver substrate pitch are selected to be 20 nm, 60 nm, 215 nm, and 235 nm, respectively. Furthermore, the influence of using various metals on absorption spectra has been explored in the visible and near-infrared regimes. The d metals considered for the top layer are titanium, nickel, chromium, silver, copper, gold, aluminum, and gold.

Vitamin E rescues valproic acid-induced testicular injury in rats: Role of autophagy.

AIMS: Valproic acid (VPA), a commonly used antiepileptic drug, can induce testicular oxidative stress and injury. Altered autophagic response usually follows testicular injury. The study aims to evaluate the role of autophagy in the protective effect of the antioxidant vitamin E (Vit E) against VPA-induced testicular injury. MATERIALS AND METHODS: VPA (100, 300, and 500 mg/kg/day) was administered for 8 days. The protective group received both Vit E (50 mg/kg) and VPA (500 mg/kg). The testicular weight, sperm analysis, and serum testosterone concentration, as well as testicular histopathology, steroidogenic gene expression, and oxidative stress markers were evaluated. The mRNA or protein expression of autophagy-related proteins [adenosine monophosphate-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR), microtubule-associated protein light chain 3 (LC3), Beclin1, and p62] were measured using RT-PCR or immunohistochemistry. KEY FINDINGS: VPA resulted in lower testes weight and sperm quality with aberrant morphology. VPA dose-dependently induced testicular oxidative stress, which was associated with decreased steroidogenic gene expression and serum testosterone levels, as well as deteriorated histopathology. These biochemical and histological changes were also associated with autophagy induction (higher LC3 and Beclin1, and lower p62) that was lost with the highest toxic dose (500 mg/kg). The attenuated autophagy with the highest dose was accompanied by AMPK downregulation and mTOR upregulation. Vit E protected against VPA-mediated oxidative stress and toxicity while also restoring autophagic response and AMPK/mTOR levels. SIGNIFICANCE: The study highlights vitamin E as a valuable protective asset against VPA-induced testicular injury, possibly through AMPK-mTOR-dependent autophagy induction.

Plasmon-Enhanced Sunlight Harvesting in Thin-Film Solar Cell by Randomly Distributed Nanoparticle Array.

In this paper, a randomly distributed plasmonic aluminum nanoparticle array is introduced on the top surface of conventional GaAs thin-film solar cells to improve sunlight harvesting. The performance of such photovoltaic structures is determined through monitoring the modification of its absorbance due to changing its structural parameters. A single Al nanoparticle array is integrated over the antireflective layer to boost the absorption spectra in both visible and near-infra-red regimes. Furthermore, the planar density of the plasmonic layer is presented as a crucial parameter in studying and investigating the performance of the solar cells. Then, we have introduced a double Al nanoparticle array as an imperfection from the regular uniform single array as it has different size particles and various spatial distributions. The comparison of performances was established using the enhancement percentage in the absorption. The findings illustrate that the structural parameters of the reported solar cell, especially the planar density of the plasmonic layer, have significant impacts on tuning solar energy harvesting. Additionally, increasing the plasmonic planar density enhances the absorption in the visible region. On the other hand, the absorption in the near-infrared regime becomes worse, and vice versa.

Ultra-Sensitive Nano Optical Sensor Samarium-Doxycycline Doped in Sol Gel Matrix for Assessment of Glucose Oxidase Activity in Diabetics Disease.

A low cost and very sensitive method for the determination of the activity of glucose oxidase enzyme in different diabetics serum samples was developed. The method based on the assessment of the H2O2 concentration produced from the reaction of the glucose oxidase (GOx) enzyme with glucose as substrate in the serum of diabetics patients by nano optical sensor Sm-doxycycline doped in sol gel matrix. H2O2 enhances the luminescence intensity of all bands of the nano Sm-doxycycline complex [Sm-(DC)2]+ doped in sol-gel matrix, especially the 645 nm band at λex = 400 nm and pH 7.0 in water. The influence of the different analytical parameters that affect the luminescence intensity of the nano optical sensor, e.g. pH, H2O2 concentration and foreign ions concentrations were studied. The remarkable enhancement of the luminescence intensity of nano optical sensor [Sm-(DC)2]+ complex in water at 645 nm by the addition of various concentrations of H2O2 was successfully used as an optical sensor for the assessment of the activity of the glucose oxidase enzyme in different diabetics serum samples. The calibration plot was achieved over the activity range 0.1-240 U/L with a correlation coefficient of 0.999 and a detection limit of 0.05 U/L.

The relation between coronary tortuosity and calcium score in patients with chronic stable angina and normal coronaries by CT angiography.

PURPOSE: Coronary tortuosity (CorT) is a phenomenon often noticed by cardiologists and may be associated with stable angina even without significant lesion. We aim to determine the relationship between CorT and coronary artery calcium (CAC) scoring in patients with chronic stable angina and normal or near normal coronaries detected by computed tomography (CT) angiography. METHODS: This is a cross sectional retrospective study included all patients with stable angina underwent CT coronary angiography and calcium scoring that reveals normal or non-significant coronary artery lesion. The presence of CorT was revised. CorT is defined as a fixed ≥ 3 bends during both systole and diastole, with each bend ≥ 45°. RESULTS: The study involved 83 patients. CT angiography revealed 31 patients (37.3%) with tortuous one or more coronary arteries and 52 patients (62.7%) without any CorT. The patients were divided into 2 groups; those patients with tortuous coronary arteries (CorT group) and those without coronary tortuosity (N CorT group). There was no significant difference between both groups regarding age, presence of DM, and dyslipidemia. However, there was a highly significant difference between both groups regarding hypertension with more hypertension among the CorT group (p value < 0.001). There was a significant difference between both groups in CAC score with high CAC score in the CorT group (p value < 0.05). There was significant correlation between CorT and CAC score (unadjusted p = 0.06); if adjusted for co-variated affecting CorT (p = 0.022). CONCLUSION: CorT is associated with subclinical atherosclerosis and increased CAC score even in the absence of significant obstructive lesion.

Investigating the characteristics of TM-pass/TE-stop polarizer designed using plasmonic nanostructures.

Plasmonics-based polarizers are important for many photonic devices and applications. In this paper, we design and investigate the characteristics of a new TM-pass/TE-stop polarizer using silver nanograting of exponentially tapered slit sidewalls. Performance of the designed polarizer is determined through monitoring the modification of its insertion loss, return loss, extinction ratio, and far-field transform due to changing its structural parameters. We find that the structural parameters of the reported polarizer such as a slit sidewall tapering coefficient and slit opening widths have a significant impact on tuning the polarizer characteristics.