LC–QTOF–MS-based metabolite profiling and evaluation of α-glucosidase inhibitory kinetics of Coccinia grandis fruit

Coccinia grandis is an important food crop of the Cucurbitaceae family, widely used for culinary purposes in India. It is reported to possess hypoglycemic, hypolipidemic and antioxidant activities. The current study was aimed to explore the inhibition kinetics as well as major constituents of the active fraction of C. grandis against α-glucosidase. The kinetic study was performed through spectrophotometric assay, with p-nitrophenyl-α-d -glucopyranoside as a substrate with varying concentrations. An in vitro antioxidant study was performed by DPPH assay. In addition, UPLC–QTOF–MS analysis was carried out for metabolite profiling of the bioactive fraction of C. grandis. The results showed that the difference between the α-glucosidase inhibitory activity of the ethyl acetate fraction of C. grandis (EFCG) (IC₅₀ 2.43 ± 0.27 mg/ml), and standard inhibitor, acarbose (2.08 ± 0.19 mg/ml), was not statistically significant at a P-value of 0.05. The enzyme kinetics confirmed the inhibition mode in a mixed manner. The EFCG also showed the highest antioxidant activity (101.74 ± 1.95 μg/ml) among all of the fractions. A significant correlation between antioxidant and α-glucosidase inhibitory activity of EFCG was observed. The LC–QTOF–MS study of the EFCG putatively identified 35 metabolites, which may be responsible for its antioxidant and α-glucosidase inhibitory properties. Thus, C. grandis fruits can serve as a functional food to address diabetes-related disorders associated with α-glucosidase.     

Monolithically integrated bacteriorhodopsin-GaAs field-effect transistor photoreceiver

We have applied the large photovoltage developed across a layer of selectively deposited bacteriorhodopsin to the gate terminal of a monolithically integrated GaAs-based modulation-doped field-effect transistor, which delivers an amplified photoinduced current signal. The integrated biophotoreceiver device exhibits a responsivity of 3.8 A/W. The optoelectronic integrated circuit is achieved by molecular-beam epitaxy of the field-effect transistor's heterostructure, photolithography, and selective-area bacteriorhodopsin electrodeposition.     

Cellular interactions of lauric acid and dextran-coated magnetite nanoparticles

In vitro cytocompatibility and cellular interactions of lauric acid and dextran-coated magnetite nanoparticles were evaluated with two different cell lines (mouse fibroblast and human cervical carcinoma). Lauric acid-coated magnetite nanoparticles were less cytocompatible than dextran-coated magnetite nanoparticles and cellular uptake of lauric acid-coated magnetic nanoparticles was more than that of dextran-coated magnetite nanoparticles. Lesser cytocompatibility and higher uptake of lauric acid-coated magnetite nanoparticles as compared to dextran-coated magnetic nanoparticles may be due to different cellular interactions by coating material. Thus, coating plays an important role in modulation of biocompatibility and cellular interaction of magnetic nanoparticles.     

Improved optimal variational method to analyze optical rib waveguides

We present an improved optimal variational method (Vopt) to overcome the assumption of field separability in the two orthogonal directions. The improved Vopt method is shown to give accurate results with less computational effort. The method is applied to rib waveguides and the results are compared with those obtained using the computationally intensive finite-element method.     

Diversified Synthesis of Furans by Coupling between Enols/1,3‐Dicarbonyl Compounds and Nitroolefins: Direct Access to Dioxa[5]helicenes

A versatile method for the diversified synthesis of furans and arenofurans has been developed that proceeds through K₂CO₃‐promoted cyclization between enols/1,3‐dicarbonyl compounds and nitroolefins at reflux in EtOH. This facile method has been successfully employed in the synthesis of benzotrifuran derivatives, which are useful hole‐transporting materials. This procedure also provides direct access to dioxa[5]helicenes. This reaction offers a broad substrate scope, uses an inexpensive base and environmentally benign solvent, and is operationally simple.     

The competition of grain size and porosity in the viscoplastic response of nanocrystalline solids

Many important processing techniques for nanocrystalline solids, such as ball milling and compaction, are frequently accompanied by the presence of voids in the end products. These voids can apparently lower the yield strength of the material. In order to address the issue of competition between grain size and porosity, we develop an explicit, analytical composite model that allows us to determine the viscoplastic response of a porous, nanocrystalline solid. The development made use of the concept of a three-phase composite comprising of the plastically harder grain interior, plastically softer grain-boundary affected zone (GBAZ), and porosity. A homogenization theory that accounts for the evolution of porosity during plastic flow is established. This establishment is built upon the extension of a linear viscoelastic composite to a non-linear viscoplastic one, in which the viscoplastic behavior of the constituent phases is represented by a unified constitutive law. Then by means of a field fluctuation method, the local strain rates are linked to the applied total strain rate. Such a linkage in turn provides the secant viscosity of the constituent phases at every stage of deformation. In order to test the applicability of the developed theory, we have applied it to model the viscoplastic response of an iron and an iron–copper mixture tested by Khan et al. [Khan, A.S., Zhang, H., Takacs, L., 2000. Mechanical response and modeling of fully compacted nanocrystalline iron and copper. Int. J. Plasticity 16, 1459–1476] and Khan and Zhang [Khan, A.S., Zhang, H., 2000. Mechanically alloyed nanocrystalline iron and copper mixture: behavior and constitutive modeling over a wide range of strain rates. Int. J. Plasticity 16, 1477–1492]. It is demonstrated that the theory is capable of capturing the major features of the tested results at various grain sizes and porosities. Our calculations further point to the change of yield strength in the Hall–Petch plot from an initial increase to level off, and then to decline, at various porosities under a constant strain-rate loading. This in turn brings about the existence of a critical grain size in the nano-meter range at which the material exhibits maximum yield strength. Moreover, this critical grain size tends to move to the left in the Hall–Petch plot as the GBAZ becomes softer.     

Transport and mechanical behavior in PEO-LLZO composite electrolytes

Journal of Solid State Electrochemistry - Composite solid electrolytes (CEs), wherein ion-conducting polymer and ceramic/glass is mixed, are promising candidates for all-solid-state batteries due...     

Microstructural evaluation of boron free and boron containing heat-treated Ti-35Nb-7.2Zr-5.7Ta alloy

The microstructure of Ti-35Nb-7.2Zr-5.7Ta (TNZT) and Ti-35Nb-7.2Zr-5.7Ta-0.5B (TNZTB) alloys under different heat treatment conditions has been analyzed. The solution-treated and water-quenched TNZT sample consists mainly of β phase with a very small amount of fine athermal ω precipitate. Precipitation of α can be observed when solution-treated samples are directly aged at 580°C for 8 h. The microstructure of the samples subjected to single-stage aging at 300°C or 400°C consists of ω precipitates in equiaxed β grains. Second stage aging at 580°C for 8 h after first stage of aging at 300°C or 400°C results in the replacement of ω precipitates by secondary α. In all of these samples, the amount of ω or α phase was very small, and therefore they could not be detected by X-ray diffraction studies. However, analysis of selected area diffraction patterns obtained from transmission electron microscopy studies confirms their presence. The addition of boron leads to the formation of dispersed precipitates of TiB in the β matrix of the TNZT alloy and also refines the β grains in the microstructure. However, other microstructural features of the TNZTB alloy are similar to those of the TNZT alloy.