Liquid-phase microextraction combined with gas chromatography mass spectrometry for rapid determination of nicotine in one-drop of nightshades vegetables and commercial food products

A simple, rapid and sensitive ultrasound-assisted hollow fibre liquid-phase microextraction (UA-HF-LPME) is evaluated for the determination of nicotine in one-drop of nightshade vegetables and some of the commercial food products. The optimum extraction of nicotine was obtained by using 1.5 μL as an extracting solvent in 1.0 cm of hollow fibre for 10 min extraction time with addition of salt. The calculated calibration curves showed a high level of linearity in the range 2–100 ng g⁻¹ with correlation coefficients >0.998. The limit of detection (LOD) for the target analyte was found to be in the range of 0.2–0.5 ng g⁻¹ and the relative standard deviations (RSD) of 2.3–4.5% were obtained. The results showed that under the optimised experimental conditions, the method showed good sensitivity and relative recoveries, as well as advantages such as linearity, simplicity, low cost and high feasibility. The extraction performance of present method to the target compound was also compared with drop-to-drop solvent microextraction (DDSME) and we found that the present approach showed better extraction efficiency of target molecule from sample solution. Finally, the proposed method was successfully applied for the determination of nicotine in nightshade vegetables (potatoes, tomatoes, peppers and eggplants) and commercial food products (tomato sauce, tomato juice, and pepper sauce).     

A β-galactosidase from chick pea (Cicer arietinum) seeds: Its purification,biochemical properties and industrial applications

A β-galactosidase from Cicer arietinum seeds has been purified to apparent electrophoretic homogeneity using a combination of various fractionation and chromatographic techniques, giving a final specific activity of 220 units mg⁻¹, with approximately 1840 fold purification. Analysis of the protein by SDS–PAGE revealed two subunits with molecular masses of 48 and 38 kDa, respectively. These bands were further confirmed with LC–MS/MS, indicating that Chick pea β-galactosidase (CpGAL) is a heterodimer. Molecular mass was determined to be 85 kDa by Superose-12 FPLC column, which is in agreement with the molecular mass suggested by mass spectroscopy to be 83 kDa. The optimum pH of the enzyme was 2.8 and it hydrolysed o-nitrophenyl β-d galactopyranoside (ONPG) with a K_m value of 1.73 mM at 37 °C. The energy of activation (E_a) calculated in the range of 35 to 60 °C, using Arrhenius equation, was determined to be 11.32 kcal mol⁻¹. The enzyme could also hydrolyse lactose, with an optimum pH of 4.0 at 40 °C. K_m and E_a for lactose hydrolysis was found to be 10 mM and 10.57 kcal mol⁻¹, respectively. The enzyme was found to be comparatively thermostable showing maximum activity at 60 °C for both ONPG and lactose. Galactose was found to be the competitive inhibitor. β-Galactosidase also exhibited glycoproteineous properties when applied on Con-A Sepharose column. The enzyme was localised in germinated seeds with X-gal activity staining and shown to be expressed prominently at grown radical tip and seed coat. Sequence alignment of CpGAL with other known plant β-galactosidase showed high amino acid sequence homology.     

Laser Melting Deposition of CP-Ti/Ti–0.4Ni Graded Material for Structural Applications

Metallurgical and Materials Transactions A - In this study, microstructural evolution and strengthening of commercial purity Ti (CP-Ti)/Ti–0.4Ni graded material (GM) fabricated by laser...     

Nucleation Analysis of Variant Transformed from Austenite with Σ_3 Boundary in High-Strength Low-Alloy Steel

We elucidate here the effects of annealing twins on phase transformation products based on electron back-scatter diffraction analysis and corresponding microstructure visualization and quantification methods.Martensite and bainite were obtained by rapid continuous cooling and isothermal processing at different temperatures,respectively,which were designed to study variants formed in austenite with Σ_3 boundary.The isothermal transformation near martensite start(M_s) temperature was most conducive in obtaining the highest content of twin-related V_1/V_2 variant pair.Based on the classical nucleation theory of martensite and bainite,respectively,the role of austenite Σ_3 boundary in martensite and bainite transformation is illustrated.     

Liquid-Crystal-Elastomer-Based Dissipative Structures by Digital Light Processing 3D Printing

Digital Light Processing (DLP) 3D printing enables the creation of hierarchical complex structures with specific micro- and macroscopic architectures that are impossible to achieve through traditional manufacturing methods. Here, this hierarchy is extended to the mesoscopic length scale for optimized devices that dissipate mechanical energy. A photocurable, thus DLP-printable main-chain liquid crystal elastomer (LCE) resin is reported and used to print a variety of complex, high-resolution energy-dissipative devices. Using compressive mechanical testing, the stress–strain responses of 3D-printed LCE lattice structures are shown to have 12 times greater rate-dependence and up to 27 times greater strain–energy dissipation compared to those printed from a commercially available photocurable elastomer resin. The reported behaviors of these structures provide further insight into the much-overlooked energy-dissipation properties of LCEs and can inspire the development of high-energy-absorbing device applications.     

Pulsed electric field mediated in vitro cellular response of fibroblast and osteoblast-like cells on conducting austenitic stainless steel substrate

This article reports the intermittent pulse electric field stimulus mediated in vitro cellular response of L929 mouse fibroblast/SaOS2 osteoblast-like cells on austenitic steel substrates in reference to the field strength dependent behavior. The cellular density and morphometric analyses revealed that the optimal electric (E) fields for the maximum cell density of adhered L929 (~270 % to that of untreated sample) and SaOS2 (~280 % to that of untreated sample) cells are 1 V (0.33 V/cm) and 2 V (0.67 V/cm), respectively. The trend in aspect ratio of elongated SaOS2 cells did not indicate any significant difference among the untreated and treated (up to 3.33 V/cm) cells. The average cell and nucleus areas (for SaOS2 cells) were increased with an increase in the applied voltage up to 8 V (2.67 V/cm) and reduced thereafter. However, the ratio of nucleus to total cell area was increased significantly on the application of higher voltages (2–10 V), indicating the possible influence of E-field on cell growth. Further, the cell density results were compared with earlier results obtained with sintered Hydroxyapatite (HA) and HA-BaTiO₃ composites and such comparison revealed that the enhanced cell density on steel sample occurs upon application of much lower field strength and stimulation time. This indicates the possible role of substrate conductivity towards cell growth in pulsed E-field mediated culture conditions.