First principles study of electronic and optical properties and photocatalytic performance of GaN–SiS van der Waals heterostructure

The vertical stacking of two-dimensional materials via van der Waals (vdW) interaction is a promising technique for tailoring the physical properties and fabricating potential devices to be applied in the emerging fields of materials science and nanotechnology. The structural, electronic and optical properties and photocatalytic performance of a GaN–SiS vdW heterostructure were explored using first principles calculations. The most stable stacking configuration found energetically stable, possesses a direct staggered band gap, which is crucial for separating photogenerated charged carriers in different constituents and is efficacious for solar cells. Further, the charge transfer occurred from the SiS to GaN layer, indicating that SiS exhibits p-type doping in the GaN–SiS heterobilayer. Interestingly, a systematic red-shift was observed in the optical absorption spectra of the understudy heterobilayer system. Moreover, the conduction band edge and valence band edge of the monolayers and corresponding heterostructure were located above and below the standard redox potentials for photocatalytic water splitting, making these systems promising for water dissociation for hydrogen fuel production. The results provide a route to design the GaN–SiS vdW heterostructure for the practical realization of next-generation light detection and energy harvesting devices.

The two dimensional GaN–SiS van der Waals heterostructure is a promising candidate for optoelectronic and photocatalytic water splitting.     

Cognitive decline and depressive symptoms: early non-motor presentations of parkinsonism among Egyptian Gaucher patients

neurogenetics - Evidence about the link between glucocerebrosidase (GCase) and parkinsonism is growing. Parkinsonism was described in adult type 1 Gaucher disease (GD); few case reports described...     

Cytotoxic and photocatalytic studies of hexagonal boron nitride nanotubes: a potential candidate for wastewater and air treatment

Boron nitride (BN) nanomaterials are rapidly being investigated for potential applications in biomedical sciences due to their exceptional physico-chemical characteristics. However, their safe use demands a thorough understanding of their possible environmental and toxicological effects. The cytotoxicity of boron nitride nanotubes (BNNTs) was explored to see if they could be used in living cell imaging. It was observed that the cytotoxicity of BNNTs is higher in cancer cells (65 and 80%) than in normal cell lines (40 and 60%) for 24 h and 48 h respectively. The influence of multiple experimental parameters such as pH, time, amount of catalyst, and initial dye concentration on percentage degradation efficiency was also examined for both catalyst and dye. The degradation effectiveness decreases (92 to 25%) as the original concentration of dye increases (5–50 ppm) due to a decrease in the availability of adsorption sites. Similarly, the degradation efficiency improves up to 90% as the concentration of catalyst increases (0.01–0.05 g) due to an increase in the adsorption sites. The influence of pH was also investigated, the highest degradation efficiency for MO dye was observed at pH 4. Our results show that lower concentrations of BNNTs can be employed in biomedical applications. Dye degradation properties of BNNTs suggest that it can be a potential candidate as a wastewater and air treatment material.

Photocatalytic degradation studies of methyl orange using BNNTs.     

Effect of adlay (Coix lachryma‐jobi L. var. ma‐yuen Stapf.) hull extracts on testosterone release from rat Leydig cells

Adlay has been used as a traditional Chinese medicine for the treatment of many diseases. However, few studies have reported the effects of adlay seeds on the endocrine system. In the present study, the effects of methanol extracts of adlay hull (AHM) on testosterone synthesis were studied. Rat Leydig cells were incubated with different reagents including human chorionic gonadotropin, 8‐bromo‐adenosine‐3′,5′‐cyclic monophosphate, forskolin, A23187, progesterone and androstenedione in the presence or absence of AHM. The rat anterior pituitary (AP) gland was treated with gonadotropin‐releasing hormone (GnRH) in vitro in the presence or absence of AHM, and the concentrations of luteinizing hormone (LH) in the media were measured. AHM decreased testosterone release via the inhibition of (1) the PKA and PKC signal transduction pathways, (2) 17β‐HSD enzyme activity in rat Leydig cells, and (3) in vitro GnRH‐induced LH secretion. Copyright © 2008 John Wiley & Sons, Ltd.     

A rare cause of massive rectal bleeding: internal iliac artery aneurysm

Internal iliac artery aneurysm is a rare cause of lower gastro-intestinal tract (GIT) haemorrhage. A fifty-four year old male patient presented with massive rectal bleeding. Sigmoidoscopy was not conclusive and pelvic angiography revealed an aneurysm from a branch off the main trunk of the anterior division of the right internal iliac artery that was located in juxtaposition to the sigmoid colon. The aneurysm was successfully obliterated by transcatheter arterial embolotherapy with acrylic glue. A high index of suspicion of internal iliac artery aneurysm as a possible cause of lower GIT haemorrhage is of paramount importance. Pelvic angiography is essential for the diagnosis, and embolotherapy with acrylic glue was an effective treatment method in this patient.     

The effect of platelet-rich fibrin membrane on the repair of perforated tympanic membrane: an experimental study

Conclusion: Platelet-rich fibrin (PRF) membrane could be used successfully in the repair of tympanic membrane perforation and wound healing.

Objectives: To evaluate the effect of platelet-rich fibrin membrane in the repair of perforated tympanic membrane.

Methods: After otoscopic examination, a 3-mm perforation was made in the posterior quadrant of both tympanic membranes of 50 adult male Sprague-Dawley rats. Venous blood was withdrawn from the rats, then centrifuged. PRF was obtained in membrane form. The membrane was placed on the right tympanic membrane perforation. The perforations on the left side were left to spontaneously heal and, thus, formed the control group. Daily examinations were made of 20 rats and the time to healing of the tympanic membrane was recorded. The remaining 30 rats were separated into five groups of six, and histopathological examination was made. Evaluation was made in respect of the presence of oedema in the lamina propria, neovascularization, fibroblastic reaction, and inflammatory cells.

Results: The healing time of the tympanic membrane perforation was determined as mean 10.3?±?2.18 days in the study group applied with PRF and 17?±?2.40 days in the control group. Higher values in respect of fibrosis and neovascularization were obtained in the study group.