Development and validation of a simple analytical method for the determination of 2,4,6-trichloroanisole in wine by GC–MS

A novel method for the residue analysis of wine spoilage compound 2,4,6-trichloroanisole is reported. Wine (60 ml) was extracted with 2 ml toluene in presence of 24 g MgSO₄ and 6 g NaCl. Cleanup of the toluene phase by dispersive solid phase extraction with mixture of 100 mg CaCl₂, 25 mg primary secondary amine and 50 mg MgSO₄ was effective in minimising co-extractives and matrix effects. Time-of-flight and tandem mass spectrometric parameters were optimised to achieve linearity over 0.25–500 ng ml⁻¹ and method detection limit 0.0083 ng ml⁻¹ which is well below the odour threshold of 0.04 ng ml⁻¹. Recoveries at 0.04, 0.2 and 0.8 ng ml⁻¹ were within 80–110% (±8%). The method was reproducible when tested for Argentinean wines with intra-laboratory Horwitz ratios being <0.20 in white and red wines at both the laboratories of India and Argentina. The method could be successfully applied for incurred wine samples.     

Cathodic titania nanotube arrays as anode material for lithium-ion batteries

The titanium dioxide nanotube arrays (TNAs) have been synthesized at cathode and anode via standard electrochemical method for their subsequent use as anode material for lithium-ion batteries (LIBs). The TNAs fabricated at cathode have higher Ti³⁺ in comparison to TNAs at anode, which was confirmed using X-ray photoelectron spectroscopy and Raman spectrometry. Moreover, the lattice parameters of cathodic TNAs are estimated via Rietveld refinement of X-ray diffraction, which also conform to Ti³⁺ doping and insertion of protons (H⁺). The electrochemical impedance spectroscopy hints an increment in the electronic conductivity of TNAs fabricated at cathode. As a result, high reversible areal–specific capacity (~385.5 µAh cm^?2 at 100 µA cm^?2) with excellent rate capability is acquired by utilizing TNAs fabricated at cathode as anode material in LIBs.     

Investigation of Stress and Temperature Effect on the Longitudinal Ultrasonic Waves in Polymers

This work aims at establishing the effect of stress and temperature on the velocity of ultrasonic longitudinal waves in typical engineering polymers, and evaluating the potential of ultrasonic stress measurement in the evaluation of residual stresses in polymer parts. In order to estimate the effect of material morphology, two amorphous and two semicrystalline polymers have been considered. A series of tests are implemented, to determine the acoustoelastic constants and temperature constant of materials, by using the designed transducer fixtures for in situ measurement of longitudinal wave velocity. As expected, the velocity changes linearly with stress and temperature, and the temperature effect is as important as the acoustoelastic effect. It shows that this kind of nondestructive method is a valuable quantitative tool to estimate the residual stress in polymer products, but the material temperature influence must be considered during the estimation.     

Hydrogen peroxide-induced oxidation of mixtures of alkanethiols and their quantitative detection as alkanesulfonates by electrospray ionization mass spectrometry

Finding optimal experimental conditions for generating stable negative ion electrospray ionization ion trap mass spectra (ESI-IT-MS) of alkanethiol-derived species is critical for quantitatively characterizing multicomponent alkanethiol-based self-assembled monolayers by this technique. Since alkanethiolates slowly oxidize in solution, purposeful oxidation of alkanethiols to their fully oxidized form (alkanesulfonates) is advantageous: sulfonates are chemically stable and have little affinity for covalent binding to metal surfaces. We have used ESI-IT-MS to characterize the products of H(2)O(2) oxidation of simple n-alkanethiols in solution and have observed monomeric alkanesulfonate species as well as alkanesulfonic acid/alkanesulfonate adducts, yielding gas-phase dimers and trimers. MS intensities of both monomers and adducts exhibit a dependence on the ion transfer capillary temperature that is alkyl-chain-length-dependent and that appears to be correlated with C-S bond cleavage. The trend in optimal capillary temperatures indicates that entropic effects lead to lower thermal decomposition temperatures for short-chain species relative to the longer-chain homologues. MS calibration data from alkanesulfonate mixtures are characterized by large linear dynamic ranges (10(-6)-10(-3) M) and detection limits influenced by their thermal decomposition. The high degree of precision in the calibration data should facilitate distinguishing among mixed SAMs having similar compositions.     

Sol–gel synthesis of Cr substituted Li0.5Fe2.5O4: Cation distribution,structural and magnetic properties

Li_0.5Cr_xFe_2.5−xO₄ powders with fine sized particles were successfully synthesized by sol–gel auto combustion, using lithium nitrate, ferric nitrate, chromium nitrate, and citric acid as the starting materials. The process takes only a few minutes to obtain as-prepared Cr-substituted lithium ferrite powders. The resultant powders were annealed at 600 °C for 4 h and investigated by thermogravimeter/differential thermal analyzer (TG/DTA), X-ray diffractometer (XRD) and vibrating sample magnetometer (VSM). Lattice parameter, bulk density and particle size are found to decrease with increasing Cr concentration, whereas X-ray density and porosity showed an increasing trend with the Cr content. Cation distribution indicates that the chromium ion occupy octahedral B-site. The magnetic moments calculated from Neel's molecular field model are in agreement in the experiment result, which indicates that the saturation magnetization decreases linearly from 37.36 to 4.27 emu/g with increasing Cr³⁺ content. However, coercivity, it increases with the Cr³⁺ substitution.     

Thermally stable electromagnetic interference shielding material from polysulfone nanocomposites: Comparison on carbon nanotube and nanofiber reinforcement

The present investigation aims to develop thermally stable electromagnetic interference shielding materials from polysulfone (PSU) nanocomposites filled with multiwall carbon nanotubes (MWCNT) or carbon nanofibers (CNF). The effect of filler type and their structural features such as aspect ratio (length/diameter) and wall integrity on the different properties of nanocomposites has been investigated. Nanocomposite filled with MWCNT/CNF exhibits higher thermal stability compared with the neat PSU matrix. The onset degradation temperature of PSU at 532°C enhances to 537 and 538°C at 3 wt% MWCNT and 3 wt% CNF loading, respectively. CNFs filled nanocomposite shows higher electromagnetic interference shielding effectiveness (EMISE) compared with MWCNT filled one at the same filler loading. Compared with MWCNT, CNF imparts lower electrical percolation threshold. Nanocomposite filled with MWCNTs possesses percolation threshold at 1.5 wt%, whereas nanocomposite filled with CNFs possesses the same at 0.9 wt%. The EMISE of 20–45 dB are obtained from only 1 mm thick CNF filled nanocomposites from the filler loading 3 to 10 wt%. This value of EMISE above 40 dB suggests that the prepared nanocomposite can be used as an effective lightweight EMI shielding material for high frequency (8.2–12.4 GHz) applications, where high thermal stability is required. POLYM. COMPOS. 36:566–575, 2015. © 2014 Society of Plastics Engineers     

The interplay of cell–cell and cell–substrate adhesion in collective cell migration

Collective cell migration often involves notable cell–cell and cell–substrate adhesions and highly coordinated motion of touching cells. We focus on the interplay between cell–substrate adhesion and cell–cell adhesion. We show that the loss of cell-surface contact does not significantly alter the dynamic pattern of protrusions and retractions of fast migrating amoeboid cells (Dictyostelium discoideum), but significantly changes their ability to adhere to other cells. Analysis of the dynamics of cell shapes reveals that cells that are adherent to a surface may coordinate their motion with neighbouring cells through protrusion waves that travel across cell–cell contacts. However, while shape waves exist if cells are detached from surfaces, they do not couple cell to cell. In addition, our investigation of actin polymerization indicates that loss of cell-surface adhesion changes actin polymerization at cell–cell contacts. To further investigate cell–cell/cell–substrate interactions, we used optical micromanipulation to form cell–substrate contact at controlled locations. We find that both cell-shape dynamics and cytoskeletal activity respond rapidly to the formation of cell–substrate contact.