Effect of annealing temperature on the electrical properties of Au/Ta2O5/n-GaN metal–insulator–semiconductor (MIS) structure

We report on the effect of an annealing temperature on the electrical properties of Au/Ta₂O₅/n-GaN metal–insulator–semiconductor (MIS) structure by current–voltage (I–V) and capacitance–voltage (C–V) measurements. The measured Schottky barrier height (Φ _bo) and ideality factor n values of the as-deposited Au/Ta₂O₅/n-GaN MIS structure are 0.93 eV (I–V) and 1.19. The barrier height (BH) increases to 1.03 eV and ideality factor decreases to 1.13 upon annealing at 500 ^°C for 1 min under nitrogen ambient. When the contact is annealed at 600 ^°C, the barrier height decreases and the ideality factor increases to 0.99 eV and 1.15. The barrier heights obtained from the C–V measurements are higher than those obtained from I–V measurements, and this indicates the existence of spatial inhomogeneity at the interface. Cheung’s functions are also used to calculate the barrier height (Φ _bo), ideality factor (n), and series resistance (R _s ) of the Au/Ta₂O₅/n-GaN MIS structure. Investigations reveal that the Schottky emission is the dominant mechanism and the Poole–Frenkel emission occurs only in the high voltage region. The energy distribution of interface states is determined from the forward bias I–V characteristics by taking into account the bias dependence of the effective barrier height. It is observed that the density value of interface states for the annealed samples with interfacial layer is lower than that of the density value of interface states of the as-deposited sample.     

A Comprehensive Review on Therapeutic Perspectives of Phytosterols in Insulin Resistance: A Mechanistic Approach

Natural products in the form of functional foods have become increasingly popular due to their protective effects against life-threatening diseases, low risk of adverse effects, affordability, and accessibility. Plant components such as phytosterol, in particular, have drawn a lot of press recently due to a link between their consumption and a modest incidence of global problems, such as Type 2 Diabetes mellitus (T2DM), cancer, and cardiovascular disease. In the management of diet-related metabolic diseases, such as T2DM and cardiovascular disorders, these plant-based functional foods and nutritional supplements have unquestionably led the market in terms of cost-effectiveness, therapeutic efficacy, and safety. Diabetes mellitus is a metabolic disorder categoriszed by high blood sugar and insulin resistance, which influence major metabolic organs, such as the liver, adipose tissue, and skeletal muscle. These chronic hyperglycemia fallouts result in decreased glucose consumption by body cells, increased fat mobilisation from fat storage cells, and protein depletion in human tissues, keeping the tissues in a state of crisis. In addition, functional foods such as phytosterols improve the body’s healing process from these crises by promoting a proper physiological metabolism and cellular activities. They are plant-derived steroid molecules having structure and function similar to cholesterol, which is found in vegetables, grains, nuts, olive oil, wood pulp, legumes, cereals, and leaves, and are abundant in nature, along with phytosterol derivatives. The most copious phytosterols seen in the human diet are sitosterol, stigmasterol, and campesterol, which can be found in free form, as fatty acid/cinnamic acid esters or as glycosides processed by pancreatic enzymes. Accumulating evidence reveals that phytosterols and diets enriched with them can control glucose and lipid metabolism, as well as insulin resistance. Despite this, few studies on the advantages of sterol control in diabetes care have been published. As a basis, the primary objective of this review is to convey extensive updated information on the possibility of managing diabetes and associated complications with sterol-rich foods in molecular aspects.     

Ruthenium(II)/(III) and oxovanadium(IV) complexes of highly conjugated β-diketones and their macrocyclic Schiff base binuclear copper(II) complexes

Ruthenium(II) complexes of the general formula [Ru(PPh3)2(L)(L)]ClO4 [L=2,2-bipyridine or 1,10-phenanthroline;L=2-hydroxy--4-X-phenylcinnamoylacetophenone] have been prepared by reacting L and L with Ru(PPh3)3Cl2 in CH2Cl2. The complexes are diamagnetic and absorb intensely in the visible region, owing to the MLCT transition. Hexacoordinated ruthenium(III) complexes, [RuCl2(PPh3)2(L)], have also been prepared by reacting Ru(PPh3)3Cl3 with -diketones. Solutions of ruthenium(III) complexes show rhombic e.s.r. spectra at 77 K, and distortion from the octahedral symmetry has been identified from the line spacings. The conjugation in diketones favours reversibility in RuII/III and RuIII/IV and stabilize ruthenium in different oxidation states owing to d–* interaction. Oxovanadyl(IV) complexes of the -diketones with a metal-to-ligand ratio of 1:2 and square pyramidal geometry were also prepared. The e.s.r spectra of these complexes show the presence of an unpaired electron in the dxy orbital and the hyperfine splitting constants are sensitive to solvent change. ¶ A new class of highly conjugated Schiff bases obtained from the above diketones and 2-aminothiophenol behave as dibasic, tridentate ligands in their copper(II) complexes. The subnormal magnetic moments and hyperfine splittings of these complexes are ascribed to an antiferromagnetic exchange interaction arising from dimerization. Cyclic voltammograms show that the electron transfer occurs in two steps corresponding to CuII–CuI and CuI–CuI redox states.     

Triazine interlinked covalent organic polymer as an efficient anti-bacterial agent

Herein, we report the synthesis of new covalent organic polymer comprising triazine and o-tolidine by solvothermal method. The formation of polymer was confirmed by Fourier transform infra red spectroscopy (FT-IR), cross polarization–magic angle spinning nuclear magnetic resonance (NMR), transmission electron microscopy, and scanning electron microscopy. Their antibacterial activity toward S. aureus (gram-positive) and P. aeruginosa (gram-negative) was assessed by the optical density measurements and direct contact method. These results have great significance toward the design of new porous polymers for antibacterial applications.     

Enhanced Electrocatalytic Activity of Ni‐CNT Nanocomposites for Simultaneous Determination of Epinephrine and Dopamine

A promising electrochemical sensor based nickel‐carbon nanotube (Ni‐CNT) modified on glassy carbon (GC) electrode had been developed and the properties of the modified electrode were characterized by multispectroscopic analysis. The fabricated sensor (GC/Ni‐CNT) electrode was utilized to determine the catecholamines such as epinephrine and dopamine simultaneously. Differential pulse voltammetry and amperometry were used to verify the electrochemical behavior of the studied compounds. The GC/Ni‐CNT based amperometric sensor showed a wide linear range and low detection limit with high analytical sensitivity of 8.31 and 6.61 μA μM^?1 for EP and DA, respectively which demonstrates better characteristics compared to other electrodes reported in the literature. Further, no significant change in amperometric current response was observed in presence of biological interference species such as glucose, cysteine, citric acid, uric acid and ascorbic acid in the detection of EP and DA. The utility of this GC/Ni‐CNT electrode was well established for the determination of EP and DA in human urine samples.     

Regioselective side-chain as well as nuclear monobromination of aromatic substrates with N-bromosuccinimide using phosphotungstic acid supported on zirconia as a heterogeneous catalyst

Regioselective monobromination of aromatic substrates with N-bromosuccinimide has been achieved in excellent isolated yields (84–98%) using phosphotungstic acid supported on zirconia as a novel heterogeneous catalyst. The catalyst has been characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), surface area and acidity measurements. Remarkably, the new catalyst system described brought about the side-chain bromination of aromatics to afford bromomethyl arenes in excellent yields (86–98%) without the need for a radical initiator. Recovery and recylability of the catalyst have been well established.     

Development and validation of an LC-MS/MS-ESI method for the determination of lorglumide, a CCK-1 antagonist in mouse plasma: application to a pharmacokinetic study

A highly sensitive, rapid assay method was developed and validated for the estimation of lorglumide in mouse plasma using liquid chromatography coupled to tandem mass spectrometry with electrospray ionization in positive‐ion mode. The assay procedure involves extraction of lorglumide and phenacetin (internal standard, IS) from mouse plasma with simple protein precipitation. Chromatographic separation was achieved using an isocratic mobile (0.2% formic acid solution–acetonitrile, 20:80, v/v) at a flow‐rate of 0.5 mL/min on an Atlantis dC₁₈ column maintained at 40 °C with a total run time of 4.0 min. The MS/MS ion transitions monitored were 459.2 → 158.4 for lorglumide and 180.1 → 110.1 for IS. Method validation was performed as per FDA guidelines and the results met the acceptance criteria. The lower limit of quantitation achieved was 0.42 ng/mL and the linearity range extended from 0.42 to 500 ng/mL. The intra‐ and inter‐day precisions were in the ranges of 1.47–10.9 and 3.56–7.53, respectively. Copyright © 2011 John Wiley & Sons, Ltd.     

Biomolecular docking,antimicrobial and cytotoxic studies on new bidentate schiff base ligand derived metal (II) complexes

Three new metal complexes [Cu(L)₂] (1), [Co(L)₂] (2) and [Zn(L)₂] (3) have been prepared by the reaction of hydrated salts of metal (II) acetate with new Schiff base ligand HL, [2‐((4‐(dimethylamino)phenylimino)methyl)‐4,6‐di‐t‐butylphenol] and characterized by different physico‐chemical analyses such as elemental analysis, single XRD, ¹H NMR, FTIR and UV–Vis spectroscopic techniques. Their biomolecular docking, antimicrobial and cytotoxicity studies have also been demonstrated. The proposed structure of Schiff base ligand HL and complex 2 are confirmed by Single crystal X‐ray crystallography study. This analysis revealed that metal (II) complexes remain in distorted tetrahedral coordination environments. The electronic properties such as HOMO and LUMO energies are carried out by gaseous phase DFT/B3LYP calculations using Gaussian 09 program. Complex 1 showed a good binding propensity to the DNA and HSA, during the assessment of docking studies. Schiff base ligand HL and its metal (II) complexes, 1–3 screened for their in vitro antimicrobial activities using the disc diffusion method against selected microbes. Complex 1 shows higher antimicrobial activity than complexes 2, 3 and Schiff base ligand HL. According to the results obtained from the cytotoxic studies, Schiff base ligand HL and its metal (II) complexes 1–3 have better cytotoxicity against MCF‐7 cell lines with potency higher than the currently used chemotherapeutic agent cyclophosphamide.     

Ruthenium(II)/(III) complexes of bidentate acetyl hydrazide Schiff bases

A series of octahedral Ru^II/Ru^III complexes of the type [Ru(Y)(CO)(BAX)(PPh₃)₂] and [RuCl₂(BAX)(PPh₃)₂] (Y = H or Cl; BAX = benzaldehydeacetylhydrazone anion; X = H, Me, OMe, OH, Cl or NO₂) have been prepared and characterised by spectral, magnetic and cyclic voltammetric studies. The Ru^II complexes are low spin diamagnetic (S = 0) whereas the Ru^III complexes are low spin and paramagnetic (S = 1/2). These Ru^II and Ru^III complexes absorb in the visible region respectively at ca. 16,000 and 28,000 cm^–1 which bands are assigned to the MLCT. The correlation of the _max values of the Ru^III complexes with the ⁺ Hammett parameter, is linear, indicating the profound effect of substituents on the electron density of the central metal. I.r. spectral data reveals that the hydrazone is chelated to ruthenium through the hydrazinic nitrogen and the deprotonated enolic oxygen. The rhombic nature of the e.s.r. spectra of the Ru^III complexes indicates an asymmetry in the electronic environment around the Ru atom. Ru^II complexes in CH₂Cl₂ show an irreversible Ru^II/III redox couple at ca. 0.9–0.5 V, while the Ru^III complexes show two reversible redox couples in the –0.1–0.1 and 0.8–0.6 V range, indicating that the higher oxidation state of ruthenium is stabilised by hydrazones.     

A Linear Ion Trap with an Expanded Inscribed Diameter to Improve Optical Access for Fluorescence Spectroscopy

We report a custom-geometry linear ion trap designed for fluorescence spectroscopy of gas-phase ions at ambient to cryogenic temperatures. Laser-induced fluorescence from trapped ions is collected from between the trapping rods, orthogonal to the excitation laser that runs along the axis of the linear ion trap. To increase optical access to the ion cloud, the diameter of the round trapping rods is 80% of the inscribed diameter, rather than the roughly 110% used to approximate purely quadrupolar electric fields. To encompass as much of the ion cloud as possible, the first collection optic has a 25.4 mm diameter and a numerical aperture of 0.6. The choice of geometry and collection optics yields 10⁷ detected photons/s from trapped rhodamine 6G ions. The trap is coupled to a closed-cycle helium refrigerator, which in combination with two 50 Ohm heaters enables temperature control to below 25 K on the rod electrodes. The purpose of the instrument is to broaden the applicability of fluorescence spectroscopy of gas-phase ions to cases where photon emission is a minority relaxation pathway. Such studies are important to understand how the microenvironment of a chromophore influences excited state charge transfer processes.

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