InAs/GaSb strained layer superlattice detectors with nBn design

We have investigated the electrical and optical properties of an nBn based Type-II InAs/GaSb strained layer superlattice detector as a function of absorber region background carrier concentration. Temperature-dependent dark current, responsivity and detectivity were measured. At T = 77 K and V_b = 0.1 V, with two orders of magnitude change in doping concentration, the dark current density increased from ～0.3 mA/cm² to ～0.3 A/cm². We attribute this to a depletion region that exists at the AlGaSb barrier and the SLS absorber interface. The device with non-intentionally doped absorption region demonstrated the lowest dark current density (0.3 mA/cm² at 0.1 V) with a specific detectivity D¹ at zero bias equal to 1.2 × 10¹¹ Jones at 77 K. The D¹ value decreased to 6 × 10¹⁰ cm Hz^1/2/W at 150 K. This temperature dependence is significantly different from conventional PIN diodes, in which the D¹ decreases by over two orders of magnitude from 77 K to 150 K, making nBn devices a promising alternative for higher operating temperatures.     

Preconcentration of valsartan by dispersive liquid–liquid microextraction based on solidification of floating organic drop and its determination in urine sample: Central composite design

In this work, a fast, easy, and efficient dispersive liquid–liquid microextraction method based on solidification of floating organic drop followed by high‐performance liquid chromatography with UV detection was developed for the separation/preconcentration and determination of the drug valsartan. Experimental design was applied for the optimization of the effective variables (such as volume of extracting and dispersing solvents, ionic strength, and pH) on the extraction efficiency of valsartan from urine samples. The optimized values were 250.0 μL ethanol, 65.0 μL 1‐dodecanol, 4.0% w/v NaCl, pH 3.8, 1.0 min extraction time, and 4.0 min centrifugation at 4000 rpm min^?1. The linear response (r² = 0.997) was obtained in the range of 0.013–10.0 μg mL^?1 with a limit of detection of 4.0 ng mL^?1 and relative standard deviations of less than 5.0 % (n = 6).     

A cellulose-supported Mn(salen)Cl complex as an efficient heterogeneous catalyst for the selective oxidation of benzylic alcohols

[Mn(salen)Cl-cellulose] was synthesized by immobilization of homogeneous Mn(salen)Cl complex on cellulose and characterized by FT-IR, TGA and atomic absorption spectroscopy. The resulted catalyst exhibited moderate to high reactivity in the oxidation of benzylic alcohols into carbonyl compounds using oxone as oxidant in ambient conditions. The catalytic activity of Mn(salen)Cl and [Mn(salen)Cl-cellulose] in this reaction was investigated. The heterogeneous catalyst showed higher catalytic activity with respect to neat Mn(salen)Cl complex.     

Preparation of chitosan–silica/PCL composite membrane as wound dressing with enhanced cell attachment

In the present study, the asymmetrical polycaprolactone membranes were synthesized using phase inversion method and modified by addition of Pluronic (F‐127) and sodium hydroxide treatment to improve the cell attachment. The chemical structure, physical properties and mechanical behavior of the membranes as well as cell attachment and proliferation on them were characterized and compared to determine the appropriate membrane used in wound dressing fabrication. Then, a composite membrane as wound dressing capable of drug controlled‐release was prepared composed of two merged layers: an asymmetrical poly(ε‐caprolactone) layer coated with a drug‐loaded chitosan – silica matrix. Drug release behavior and biocompatibility of the final system were evaluated. The results showed that the polycaprolactone modified membrane provides appropriate properties to expand fibroblast cell adhesion and proliferation. This in‐vitro study also showed that the controlled‐release composite wound dressing was developed with approximately 70% cumulative release rate, which provided a porous substrate to support skin cells. Copyright © 2017 John Wiley & Sons, Ltd.     

The magnetic nanostructured natural hydroxyapatite (HAP/Fe3O4 NPs): an efficient,green and recyclable nanocatalyst for the synthesis of biscoumarin derivatives under solvent-free conditions

Research on Chemical Intermediates - The magnetic nanostructured natural hydroxyapatite (HAP/Fe3O4 NPs) as a novel magnetic nanocatalyst was synthesized and fully characterized. The excellent...     

Dispersive solid‐phase extraction adsorbent of methamphetamine using in‐situ synthesized carbon‐based conductive polypyrrole nanocomposite: focus on clinical applications in human urine

Determination of methamphetamine is of great importance in clinical and forensic laboratories because there are low dosages of drugs in the biological media and social problems created due to the methamphetamine consumption. Polymeric carbon based‐nano composites are reasonable candidates for dispersive solid phase extraction method due to facial and affordable synthesis process and high selectivity and sensitivity. Nano graphene oxide polypyrolle composite was synthesized and employed as dispersive solid‐phase extraction adsorbent for methamphetamine extraction from complex urine matrix. Full characterization of the prepared nano graphene oxide polypyrolle composite was completed and the influential extraction parameters were investigated through one‐parameter‐at‐a‐time method. High‐performance liquid chromatography detectors were applied as detection and quantification instrument. The optimized extraction parameters included 300 µL of methanol, 10 min of extraction and desorption time, 6000 stirring rate, urine pH value of 10, 60 mg of adsorbent, and 6 mL of urine volume. After outlining the calibration curve, the linear range of the method was considered as 30–800 ng/mL. The detection limit for the suggested method was 9 ng/mL. The analysis of addicted subjects with the proposed method confirmed the utility of the method in different analytical and clinical laboratories.