Preparation and Characterization of Silver Selenide Thin Film

Silver selenide, a phase-changing chalcogenide material, is prepared using electro deposition method for various molarities. X-ray diffraction studies show the cubic lattice of the material. The micro-structural properties such as grain size, strain, dislocation density, and texture coefficient are examined. The lattice constant is calculated using Nelson-Relay function. Morphological studies are done and uniform distributions of grains are observed. High purities of thin films are confirmed by energy dispersive X-ray analysis. The band gap is calculated using UV-vis spectroscopy and photoluminescence technique, and hence, the Stokes’s effect is observed in silver selenide thin films. It is the first time that the lattice constant and the Urbach energy for various molarities in the case of silver selenide thin films are reported.     

Synthesis,Photophysical Properties and Computational Studies of beta‐Substituted Porphyrin Dyads

Beta‐pyrrole‐substituted porphyrin dyads connected by ethynyl linkage to N‐butylcarbazole or triphenylamine donors are reported. Donor‐π‐acceptor type beta‐substituted porphyrin dyads and their Zn(II) and Pd(II) complexes were characterized by MALDI‐MS, NMR, UV‐vis absorption, fluorescence and cyclic voltammetry techniques. The S₁ emission dynamics were analyzed by time‐resolved spectroscopy (TCSPC); dyads exhibited efficient energy transfer up to 93% from beta‐donors (N‐butylcarbazole or triphenylamine group) to the porphyrin core. The efficiency of energy transfer for the beta‐substituted porphyrin dyads were much higher than those of the corresponding meso‐substituted porphyrin dyads, reflecting enhanced communications between the beta‐donors and the porphyrin core. The Pd(II) dyads, showed characteristic phosphorescence in the near IR region and very efficient singlet oxygen quantum yields (53–60%); these dyads are promising candidates for photocatalytic oxidations of organic compounds. The donor‐acceptor interaction between the porphyrin core and the beta‐donors was supported by the DFT studies in the porphyrin dyads.     

Biomolecules and Nutritional Quality of Soymilk Fermented with Probiotic Yeast and Bacteria

Soymilk was fermented with five isolates of probiotic lactic acid bacteria and in combination with probiotic yeast Saccharomyces boulardii. Nutritional profile like fat, protein, ash, pH, acidity, polyphenol, and protein hydrolysis were analyzed. Polyphenol content decreased from 265.88 to 119 microg/ml with different cultures. Protein hydrolysis ranged from 2.46 to 2.83 mmol l(-1) with different cultures. The antioxidant activity was assessed using different methods like 1, 1-diphenyl-2-picrylhydrazyl free radical-scavenging assay, inhibition of ascorbate autoxidation, and measurement of reducing activity. The activities varied with the starters used but, nevertheless, were significantly higher than those found in unfermented soymilk. Bioconversion of the isoflavone glucosides (daidzin + genistin) into their corresponding bioactive aglycones (daidzein + genistein) was observed during soymilk fermentation. Total glucosides in soyamilk were 26.35 mg/100 ml. In contrast, aglycones genistein and daidzein were quantitatively lesser accounting 2.91 mg/100 ml (genistein 1.17 mg/100 ml and daidzein 1.19 mg/100 ml). Soymilk fermented with probiotic cultures resulted in the reduction of glycosides ranging from 0.40 mg to 1.36 mg/100 ml and increase in aglycones ranging from 6.32 mg to 13.66 mg/100 ml.     

β-Sitosterol Circumvents Obesity Induced Inflammation and Insulin Resistance by down-Regulating IKKβ/NF-κB and JNK Signaling Pathway in Adipocytes of Type 2 Diabetic Rats

β-sitosterol (SIT), the most abundant bioactive component of vegetable oil and other plants, is a highly potent antidiabetic drug. Our previous studies show that SIT controls hyperglycemia and insulin resistance by activating insulin receptor and glucose transporter 4 (GLUT-4) in the adipocytes of obesity induced type 2 diabetic rats. The current research was undertaken to investigate if SIT could also exert its antidiabetic effects by circumventing adipocyte induced inflammation, a key driving factor for insulin resistance in obese individuals. Effective dose of SIT (20 mg/kg b.wt) was administered orally for 30 days to high fat diet and sucrose induced type-2 diabetic rats. Metformin, the conventionally used antidiabetic drug was used as a positive control. Interestingly, SIT treatment restores the elevated serum levels of proinflammatory cytokines including leptin, resistin, tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) to normalcy and increases anti-inflammatory adipocytokines including adiponectin in type 2 diabetic rats. Furthermore, SIT decreases sterol regulatory element binding protein-1c (SREBP-1c) and enhances Peroxisome Proliferator–activated receptor-γ (PPAR-γ) gene expression in adipocytes of diabetic rats. The gene and protein expression of c-Jun-N-terminal kinase-1 (JNK1), inhibitor of nuclear factor kappa-B kinase subunit beta (IKKβ) and nuclear factor kappa B (NF-κB) were also significantly attenuated in SIT treated groups. More importantly, SIT acts very effectively as metformin to circumvent inflammation and insulin resistance in diabetic rats. Our results clearly show that SIT inhibits obesity induced insulin resistance by ameliorating the inflammatory events in the adipose tissue through the downregulation of IKKβ/NF-κB and c-Jun-N-terminal kinase (JNK) signaling pathway.     

Mechanism of epoxide hydrolysis in microsolvated nucleotide bases adenine, guanine and cytosine: a DFT study

Six water molecules have been used for microsolvation to outline a hydrogen bonded network around complexes of ethylene epoxide with nucleotide bases adenine (EAw), guanine (EGw) and cytosine (ECw). These models have been developed with the MPWB1K-PCM/6-311++G(3df,2p)//MPWB1K/6-31+G(d,p) level of DFT method and calculated S(N)2 type ring opening of the epoxide due to amino group of the nucleotide bases, viz. the N6 position of adenine, N2 position of guanine and N4 position of cytosine. Activation energy (E(act)) for the ring opening was found to be 28.06, 28.64, and 28.37 kcal mol(-1) respectively for EAw, EGw and ECw. If water molecules were not used, the reactions occurred at considerably high value of E(act), viz. 53.51 kcal mol(-1) for EA, 55.76 kcal mol(-1) for EG and 56.93 kcal mol(-1) for EC. The ring opening led to accumulation of negative charge on the developing alkoxide moiety and the water molecules around the charge localized regions showed strong hydrogen bond interactions to provide stability to the intermediate systems EAw-1, EGw-1 and ECw-1. This led to an easy migration of a proton from an activated water molecule to the alkoxide moiety to generate a hydroxide. Almost simultaneously, a proton transfer chain reaction occurred through the hydrogen bonded network of water molecules and resulted in the rupture of one of the N-H bonds of the quaternized amino group. The highest value of E(act) for the proton transfer step of the reaction was 2.17 kcal mol(-1) for EAw, 2.93 kcal mol(-1) for EGw and 0.02 kcal mol(-1) for ECw. Further, the overall reaction was exothermic by 17.99, 22.49 and 13.18 kcal mol(-1) for EAw, EGw and ECw, respectively, suggesting that the reaction is irreversible. Based on geometric features of the epoxide-nucleotide base complexes and the energetics, the highest reactivity is assigned for adenine followed by cytosine and guanine. Epoxide-mediated damage of DNA is reported in the literature and the present results suggest that hydrated DNA bases become highly S(N)2 active on epoxide systems and the occurrence of such reactions can inflict permanent damage to the DNA.     

Microstructural evolution and dielectric properties of 1D AlN powders synthesized by microwave technique

Low temperature synthesis of Aluminum nitride (AlN) powders through NH₄Cl assisted nitridation have been studied by microwave technique. The effect of processing time on the synthesis of AlN powders has been investigated. The optimum processing time was determined to be 120 min at 630 W, 200 °C. The powders were characterized by X-ray diffraction method (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray analyzer (EDS), Fourier transform infrared spectrometer (FTIR) and Impedance analyzer. XRD results revealed that the product has wurtzite phase of AlN. SEM micrographs show a 1D nanorod of AlN with a granular morphology. FTIR spectra exhibit A1 (TO) and E1 (LO) modes of wurtzite AlN. Dielectric properties of the powders were investigated by means of C–V and C–f and ε′–f characteristics. The reported results indicate a reasonable quality of the obtained AlN powders with high dielectric constant, suitable for application in the fabrication of specific electronic devices.     

Effect of nickel sulphate hexahydrate addition on crystal growth,structural, optical and biological applications of glycine single crystals

In the present study, single crystals of α- and γ-glycine have been successfully grown in the presence of nickel sulphate hexahydrate as an additive for the first time by using slow solvent evaporation method. The analytical grade chemicals of glycine and nickel sulphate hexahydrate were taken in five different molar ratios: 1:0.2, 1:0.4, 1:0.6, 1:0.8 and 1:1 respectively to find out the α, and γ-polymorph of glycine. The lower molar proportion of nickel sulphate hexahydrate yield only α-polymorph whereas the higher molar proportion of nickel sulphate hexahydrate yields only γ-polymorph of glycine which was confirmed by powder XRD studies. UV–Visible–NIR transmittance spectra were recorded for the samples to analyze the transparency in visible and near infrared region (NIR). The optical band gap Eg was estimated for grown nickel sulphate hexahydrate (NSH) added glycine crystals using UV–Visible–Transmission study. Functional groups present in the sample were identified by FTIR spectroscopic analysis. The in vitro antimicrobial activities of the synthesized nickel sulphate added glycine single crystals were investigated against gram positive, gram negative bacterial strains using the agar disk diffusion method.     

Study of [Fe(pyim)3] complexes: dynamic spin equilibrium on encapsulation in zeolite Y

Tris complex of Fe^II2(2′-pyridyl)imidazole has been encapsulated in the supercages of zeolite Y and characterized by using powder XRD, FTIR, Mössbauer spectroscopy, variable temperature magnetization and MAS NMR techniques and results have been compared with those obtained for this complex with ClO₄⁻ and SO₄²⁻ as anions. At room temperature, the [Fe(pyim)₃](ClO₄)₂ complex exhibited low spin state, while [Fe^II(pyim)₃]SO₄ exhibited the existence of both low and high spin states. The encapsulated [Fe^II(pyim)₃]²⁺ complex exhibited a broad quadrupole doublet characterized by isomer shift, δ=+0.55 mm/s and quadrupole splitting ΔE_q=1.26 mm/s. The magnetization measurements carried out for the encapsulated [Fe^II(pyim)₃]²⁺ complex showed a systematic decrease in its values with decreasing temperature down to 75 K with no indication of thermal hysteresis effects. These results suggest the existence of a dynamic spin state equilibrium between the high and low spin states for the encapsulated [Fe^II(pyim)₃]²⁺ complex with time constant comparable to the characteristic Mössbauer time scale of ⁵⁷Fe nuclei.