Conformal GaP layers on Si wire arrays for solar energy applications

We report conformal, epitaxial growth of GaP layers on arrays of Si microwires. Silicon wires grown using chlorosilane chemical vapor deposition were coated with GaP grown by metal-organic chemical vapor deposition. The crystalline quality of conformal, epitaxial GaP/Si wire arrays was assessed by transmission electron microscopy and x-ray diffraction. Hall measurements and photoluminescence show p- and n-type doping with high electron mobility and bright optical emission. GaP pn homojunction diodes on planar reference samples show photovoltaic response with an open circuit voltage of 660 mV

GaP/Si wire array solar cells

Si wire arrays have recently demonstrated their potential as photovoltaic devices [1-3]. Using these arrays as a base, we consider a next generation, multijunction wire array architecture consisting of Si wire arrays with a conformal GaN_xP_(1-x-y)As_y coating. Optical absorption and device physics simulations provide insight into the design of such devices. In particular, the simulations show that much of the solar spectrum can be absorbed as the angle of illumination is varied and that an appropriate choice of coating thickness and composition will lead to current matching conditions and hence provide a realistic path to high efficiencies. We have previously demonstrated high fidelity, high aspect ratio Si wire arrays grown by vapor-liquid-solid techniques, and we have now successfully grown conformal GaP coatings on these wires as a precursor to considering quaternary compound growth. Structural, optical, and electrical characterization of these GaP/Si wire array heterostructures, including x-ray diffraction, Hall measurements, and optical absorption of polymer-embedded wire arrays using an integrating sphere were performed. The GaP epilayers have high structural and electrical quality and the ability to absorb a significant amount of the solar spectrum, making them promising for future multijunction wire array solar cells

New oxadiazole derivatives of isonicotinohydrazide in the search for antimicrobial agents: Synthesis and in vitro evaluation

Structural modification of the front line antitubercular drug isoniazid provide a lipophilic adaptations of the drug in which hydrazide moiety of isoniazid is replaced by 1,3,4-oxadiazole heterocycles to eliminate in-vivo acetylation by arylamine N-acetyltransferase which results to form inactive acetylated drug. In the present study a series of sixteen oxadiazole derivatives were synthesized and characterized by (IR, 1H NMR, 13C NMR and Mass spectral) studies. All the synthesized compounds were evaluated for their antimicrobial activity by broth dilution method against two Gram positive strains (Bacillus subtilis and Staphylococcus aureus), two Gram negative strains (Pseudomonas aeruginosa and Escherichia coli) and fungal strain (Candida albicans and Aspergillus niger). The minimum inhibitory concentration of the compounds was in the range of 1.56-50 μg ml-1 against bacterial and fungal strain. The results revealed that all synthesized compounds have a significant biological activity against the tested microorganisms. Among the synthesized derivatives 4g, 4h, 4m and 4p were found to be most effective antimicrobial compounds

Dalfampridine: Review on its recent development for symptomatic improvement in patients with multiple sclerosis

Multiple sclerosis (MS) is a neurodegenerative disease of the central nervous system (CNS), causes irreversible disability in young adults but the cause and cure were unknown and it involves two arms: and causes demyelination and neurodegeneration. In the case of MS the massive activation of the immune system against putative CNS antigen leads to the loss of oligodendrocyte/myelin complex which slows down the impulse conduction in denuded axons. In demyelination diseases (e.g. MS) denuded axons frequently occur without axonal loss that is so characteristic of radiation injury. Since, the treatment strategies for MS have increased rapidly but still proper knowledge regarding the nature of MS cleared the way for several more specific, more effective, and more comfortable therapies. Here, because of the stimulating recent developments about oral treatment for MS, the current state of approved and future therapy options were summarized here. In particular, we highlight oral treatment options in MS and dalfampridine (4-aminopyridine) is an oral potassium channel blocker, which was recently approved by FDA (Food and Drug Administration) for symptomatic treatment of MS, it acts at the central and peripheral nervous systems, enhances conduction in demyelinated axons, and improves the walking ability of MS patients. Moreover number of clinical trials has evaluated the safety and efficacy of fampridine in MS patients and it represents a major advance in symptomatic therapy for MS. The objective of this manuscript is to provide an overview of the Chemistry, mechanism of action, pharmacodynamics, pharmacokinetics, preclinical and clinical studies, dosage and administration, side effects, contraindication, proper usage, and drug interaction of dalfampridine used in the treatment of MS patients

Synthesis, characterization and pharmacological evaluation of (Z)-2-(5-(biphenyl-4-yl)-3-(1-(imino)ethyl)-2,3-dihydro-1,3,4-oxadiazol-2-yl)phenol derivatives as potent antimicrobial and antioxidant agents

The oxadiazole pharmacophore is considered a viable lead structure for the synthesis of more efficacious and broad spectrum antimicrobial agents. The significance of this study was to prepare various oxadiazole derivatives by introducing the 1,3,4 oxadiazole core into several molecules to explore the possibilities of some altered biological activities. Therefore, the study presents the synthesis, antimicrobial and antioxidant evaluation of a series of 1,3,4 substituted oxadiazole derivatives. Antimicrobial evaluation revealed that eighteen compounds were able to display variable growth inhibitory effects on the tested Gram-positive bacteria Bacillus subtilis and Staphylococcus aureus, Gram-negative bacteria Pseudomonas aeruginosa and Escherichia coli and fungal strains Candida albicans and Aspergillus niger. Among the synthesized derivative analogues 6f, 6l and 6r were found to be the most effective antibacterial agents. While the compounds 6c, 6l and 6q were found to be the most promising antifungal agents. On the other hand, all the synthesized compounds 6a–6r were subjected to antioxidant activity but only analogues 6l and 6q were found to exhibit potent antioxidant activity. Further compound 6l containing p-nitro phenyl moiety along with oxadiazole pharmacophore proved to be the most active antimicrobial and antioxidant agent

In silico analysis of the inhibitory activities of GABA derivatives on 4-aminobutyrate transaminase

Reduced levels of γ-aminobutyric acid (GABA) are cause of quite a many diseases, and it cannot be directly introduced into the body to enhance its level because of the blood–brain barrier. Thus the technique used for the purpose involves the inhibition of aminobutyrate transaminase (ABAT), the enzyme catalyzing its degradation. The structure of human ABAT is not currently known experimentally, thus, it was predicted by homology modeling using pig ABAT as template due to high level of sequence similarity and conservation. A series of new γ-aminobutyric acid (GABA) derivatives obtained from 4-(1,3-dioxoisoindolin-2-yl)butanoic acid are used in this study. These γ -aminobutyric acid (GABA) derivatives were used as ligand dockings against human ABAT as well as pig ABAT receptors

Target Based Designing of Anthracenone Derivatives as Tubulin Polymerization Inhibiting Agents: 3D QSAR and Docking Approach

Novel anthracenone derivatives were designed through in silico studies including 3D QSAR, pharmacophore mapping, and molecular docking approaches. Tubulin protein was explored for the residues imperative for activity by analyzing the binding pattern of colchicine and selected compounds of anthracenone derivatives in the active domain. The docking methodology applied in the study was first validated by comparative evaluation of the predicted and experimental inhibitory activity. Furthermore, the essential features responsible for the activity were established by carrying out pharmacophore mapping studies. 3D QSAR studies were carried out for a series of 1,5- and 1,8-disubstituted10-benzylidene-10H-anthracen-9-ones and 10-(2-oxo-2-phenylethylidene)-10H-anthracen-9-one derivatives for their antiproliferation activity. Based on the pattern recognition studies obtained from QSAR results, ten novel compounds were designed and docked in the active domain of tubulin protein. One of the novel designed compounds “N1” exhibited binding energy −9.69 kcal/mol and predicted Ki 78.32 nM which was found to be better than colchicine