Control of ferroelectric phase transition in nano particulate NBT–BT based ceramics

Lead free relaxor NBT–BT based ceramic compositions were prepared using sol–gel method. The samples were sintered around 1140 °C for 3–4 h in the air. The characterization was done using X-ray diffraction (XRD), filed emission scanning electron microscope (FESEM), energy dispersive spectrometry (EDS), Raman, Fourier transform infrared (FTIR), dielectric and P–E loop measurements. The XRD patterns recorded at room temperature confirmed the phase formation of the samples. From FESEM micrographs, the particle sizes were estimated for calcined powders and are found to be in the range of 50–70 nm. The analysis of both Raman and FTIR spectral data of the samples also indicated the distortion of NBT lattice with the addition of Ba²⁺ and Nd³⁺ ions. It was found that the dielectric and piezoelectric properties of NBT–BT compositions beyond the morphotrophic phase boundary (MPB) are rather sensitive to the presence of tetragonal phase in addition to the rhombohedral phase. NBT ceramics exhibit a decrease in diffusive factor with increasing BT content, implying a degradation of relaxor feature leading to the normal ferroelectric nature. The ceramic samples employed in the present study exhibited variation in P–E hysteresis loops.     

Nano‐encapsulated Tinospora cordifolia (Willd.) using poly (D,L‐lactide) nanoparticles educe effective control in streptozotocin‐induced type 2 diabetic rats

The therapeutics for type 2 diabetes mellitus has emerged in the current century towards nanomedicine incorporated with plant active compounds. In this study, Tinospora cordifolia loaded poly (D, L‐lactide) (PLA) nanoparticles (NPs) were evaluated in vivo for their anti‐hyperglycemic potency towards streptozotocin‐induced type 2 diabetic rats. T. cordifolia loaded PLA NPs were synthesised by the double solvent evaporation method using PLA polymer. The NPs were then characterised and administrated orally for 28 successive days to streptozotocin‐induced diabetic rats. The PLA NPs had significant anti‐diabetic effects which were equal to the existing anti‐diabetic drug glibenclamide. The antidiabetic activity is due to the synergism of compounds present in stem extract of the plant which reduced the side effects and anti‐diabetic.Inspec keywords: blood, nanofabrication, drug delivery systems, biochemistry, evaporation, nanoparticles, nanomedicine, drugs, diseases, polymers, biomedical materialsOther keywords: PLA nanoparticles, antidiabetic effects, nanoencapsulated Tinospora cordifolia, streptozotocin‐induced type 2 diabetic rats, type 2 diabetes mellitus, poly(d, l‐lactide) nanoparticles, diabetic drug glibenclamide, nanomedicine, antihyperglycemic potency, double‐solvent evaporation     

Electrochemical lithium insertion behavior of FeNbO4: Structural relations and in situ conversion into FeNb2O6 during carbon coating

Electrochemical properties of FeNbO₄ as a lithium insertion anode material were studied with a view to understand structure–property relationships. Orthorhombic and monoclinic polymorphs of FeNbO₄ were synthesized and characterized by powder X-ray diffraction and laser Raman spectroscopy. Possible redox reactions, as deciphered from cyclic voltammograms, suggest the structural similarity between orthorhombic and monoclinic polymorphs upon lithium insertion. A coating of carbon led to a remarkable improvement in the electrochemical performance of monoclinic FeNbO₄. The coated material exhibited an average reversible capacity of 125.5 mAh g⁻¹. The material also sustained hundreds of charge/discharge cycles and exhibited good rate capability. Upon coating with carbon, the monoclinic FeNbO₄ transformed into FeNb₂O₆. The conversion and stability were confirmed by powder XRD and laser Raman studies of carbon-coated material before and after 450 cycles. The in situ conversion of FeNbO₄ into FeNb₂O₆ during carbon coating was further supported by EPR studies in which the absence of signal for the carbon-coated material indicated conversion of Fe³⁺ to Fe²⁺. Our study reveals the possibility of exploring potential materials in the Fe–Nb–O system and enhancing their performance as anode materials for lithium-ion batteries.     

Dielectric and Magnetodielectric Properties of R2NiMnO6 (R = Nd,Eu, Gd,Dy, and Y)

We have prepared polycrystalline R₂NiMnO₆ (R = Nd, Eu, Gd, Dy, and Y) samples by conventional solid‐state reaction and all the samples have shown monoclinic structure with P2₁/n space group. With the decrease in rare‐earth ionic size (<r_R>), the <Ni–O–Mn> bond angle decreases, correspondingly a decrease in ferromagnetic (FM) Curie temperature is noticed. In the dielectric measurement, the dielectric anomaly shifts to high temperature with the decrease in the <r_R> and shows no correlation with the FM Curie temperature and hints the absence of apparent magnetodielectric (MD) coupling. Appearance of multiple relaxations in the dielectric study suggests the electrical heterogeneity of the system. The dielectric/impedance analysis has revealed a close correlation between dc conductivity and the dielectrics; in fact, both dc resistivity and the grain relaxations follow the variable range hopping mechanism. The thermal activation of charge carriers at the grain boundary led to Maxwell–Wagner interfacial polarization. Finally, dielectric study under magnetic field showed no effect, it implies that not only the intrinsic MD is absent, but also the extrinsic MD due to the lack of magnetoresistance.     

Development of cobalt–copper nanoparticles as catalysts for higher alcohol synthesis from syngas

The synthesis of higher alcohols from syngas has been studied over different types of Cu-based catalysts. In order to provide control over the catalyst composition at the scale of a few nanometers, we have synthesized two sets of Co–Cu nanoparticles with novel structures by wet chemical methods, namely, (a) cobalt core–copper shell (Co@Cu) and (b) cobalt–copper mixed (synthesized by simultaneous reduction of metal precursors) nanoparticles. These catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (TPR). The catalysts were tested for CO hydrogenation at temperatures ranging from 230 °C to 300 °C, 20 bar and 18,000 scc/(hr.gcat). It was observed that the Co–Cu mixed nanoparticles with higher Cu concentration exhibit a greater selectivity towards ethanol and C₂₊ oxygenates. The highest ethanol selectivity achieved was 11.4% with corresponding methane selectivity of 17.2% at 270 °C and 20 bar.     

Effects of Amelanchier fruit isolates on cyclooxygenase enzymes and lipid peroxidation

Bioassay-directed isolation and purification of the ethyl acetate and methanol extracts of Amelanchier canadensis resulted in 1,3-dilinoleoyl 2-olein (1), 1,3-dioleoyl 2-linolein (2), 5-hydroxymethyl-2-furfural (3), 5-(sorbitoloxymethyl)-furan-2-carboxaldehyde (4), 5-(mannitoloxymethyl)-furan-2-carboxaldehyde (5), and 5-(α-d-glucopyranosyloxymethyl) furan-2-carboxaldehyde (6). Four compounds, oleanolic acid (7), ursolic acid (8), kaempferol-3-O-α-l-rhamnopyranosyl (1 ← 2) rhamnopyranoside (9), and kaempferol-3-O-α-l-rhamnopyranoside (10) were isolated from the ethyl acetate extract of fresh fruits of Amelanchier arborea. The compounds were isolated and purified by various chromatographic techniques and characterized by NMR and GC/MS methods. The isolated compounds inhibited lipid peroxidation (by 85%) at 100 ppm when compared to 89%, 87%, and 98% for the commercial antioxidants butylated hydroxy anisole (BHA), butylated hydroxytoluene (BHT), and tert-butylhydroxyquinone (TBHQ) at 1.67, 2.2, and 1.67 ppm, respectively. Although not selective, some of these compounds inhibited cyclooxygenase (COX)-1 and -2 enzymes. Compounds 3–6 were isolated for the first time from A. canadensis and compounds 7–10 were isolated for the first time from A. arborea fruits.     

Immobilization of pepsin on an acrylamide/2‐hydroxyethyl methacrylate copolymer and its use in casein hydrolysis

Pepsin was immobilized through covalent bonding on a copolymer of acrylamide and 2‐hydroxyethyl methacrylate via the individual and simultaneous activation of both groups. The extent of enzyme coupling upon the activation of both the amino and hydroxyl groups of the copolymer resulted in a synergistic effect. However, the order of activation of the support was critical. The covalently bound enzyme retained more than 50% of its activity even after six cycles. The storage stability of the covalently bound enzyme was 60% after storage for 1 month, whereas the free enzyme lost all of its activity within 10 days of storage at 35°C. The Michaelis constant (K_m) and maximum reaction velocity (V_max) were 1.1 × 10^?6 and 0.87 for the free enzyme and 1.2 × 10^?6 and 0.98 for the covalently bound enzyme when the enzyme concentration was kept constant and the substrate concentration was varied. Similarly, K_m and V_max were 6.73 × 10^?11 and 0.47 for the free enzyme and 7.59 × 10^?11 and 0.545 for the covalently bound enzyme when the substrate concentration was kept constant and the enzyme concentration was varied; this indicated no conformational change during coupling, but the reaction was concentration‐dependent. The hydrolysis of casein was carried out with a fixed‐bed reactor (17 cm × 1 cm). Maximum hydrolysis (90%) was obtained at a 2 cm³/min flow rate at 35°C with a 1 mM casein solution. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1544–1549, 2005     

Behavior and drug measurements in Long-Evans and Sprague-Dawley rats after ethanol-cocaine exposure

Long-Evans and Sprague-Dawley rats show differential behavioral responses to cocaethylene, a metabolite derived from the simultaneous ingestion of ethanol and cocaine. Such differences may also be manifested when these outbred strains are exposed to ethanol and cocaine. To test this hypothesis, both strains were fed an ethanol-diet (8.7% v/v) in conjunction with cocaine (15 mg/kg) injections for 15 days. The following parameters were evaluated: (a) ethanol consumption, (b) cocaine-induced behavioral activity, (c) blood ethanol levels, (d) blood, liver, or brain cocaine and cocaethylene levels, and (e) liver catalase and esterase activity. We found that Long-Evans rats drank significantly more of the ethanol diet relative to the Sprague-Dawley line during the first few days of the test session. This rat phenotype also differed significantly from the Sprague-Dawley line in terms of behavioral activity after cocaine administration. Blood ethanol levels did not differ between strains. Similarly, we failed to detect strain-dependent differences in blood, liver, or brain cocaine levels as measured by gas chromatography/mass spectrometry. Cocaethylene levels, however, were higher in blood and brain of Long-Evans relative to Sprague-Dawley cohorts. Although the ethanol-cocaine regimen produced a marked suppression of catalase and esterase activity compared with control-fed rats, this suppression was roughly equivalent in both rat phenotypes. These data are discussed in the context of genotypic background and vulnerability to polysubstance abuse.     

Protective role of biosynthesised zinc oxide nanoparticles on pancreatic beta cells: an in vitro and in vivo approach

Sulphonylureas are extensively used in the treatment of type II diabetes; however, these drugs have complications of hypoglycaemia and weight gain. The current study aims at developing a potent antidiabetic drug that has lesser side effects and better management of its associated conditions. Zinc oxide nanoparticles (ZnO NPs) were synthesised using Syzygium cumini seed extract with an average size of 18.92 nm. In vitro studies on rat insulinoma (RIN‐5F) cells revealed that cells treated with synthesised ZnO NPs showed a dose‐dependent increase in insulin secretion. Streptozotocin‐fructose‐induced type II diabetic rats treated with ZnO NPS exhibited a significant reduction (p  < 0.01) in the blood glucose levels, total cholesterol, triglycerides, and low‐density lipoprotein levels and increase (p  < 0.01) in serum insulin and liver antioxidant enzyme levels proclaiming its role as a hypoglycaemic and hypolipidaemic drug. Treatment of ZnO NPs in diabetic rats exhibited an increased number of beta cells which was responsible for its increased insulin levels and reduced glucose levels. From the overall observations, biosynthesised ZnO NPs exhibited an efficacious hypoglycaemic effect in diabetic rats, so it can be suggested as a potent antidiabetic drug.Inspec keywords: biochemistry, II‐VI semiconductors, drug delivery systems, drugs, patient treatment, blood, enzymes, zinc compounds, molecular biophysics, sugar, cellular biophysics, nanofabrication, liver, nanoparticles, diseases, biomedical materials, nanomedicineOther keywords: protective role, biosynthesised zinc oxide nanoparticles, pancreatic beta cells, vivo approach, type II diabetes, drugs, hypoglycaemia, weight gain, potent antidiabetic drug, lesser side effects, associated conditions, Syzygium cumini seed, rat insulinoma, synthesised ZnO NPs, dose‐dependent increase, insulin secretion, streptozotocin‐fructose‐induced type II diabetic rats, blood glucose levels, low‐density lipoprotein levels, serum insulin, liver antioxidant enzyme levels, hypoglycaemic drug, hypolipidaemic drug, increased insulin levels, reduced glucose levels, biosynthesised ZnO NPs, efficacious hypoglycaemic effect, size 18.92 nm, temperature 5.0 F, ZnO