Leaching of residues of certain pesticides from black tea to brew

Tea is the most commonly consumed beverage in the world. It is prepared after infusing processed black tea in hot water. During the process of brewing, along with flavour and aroma, the residues of plant protection chemicals may also be transferred into the tea brew or infusion. The leaching of certain pesticides, such as ethion, endosulfan, dicofol, chlorpyrifos, deltamethrin, hexaconazole, fenpropathrin, propargite, quinalphos and lambdacyhalothrin from powdered black tea into the brew was studied. The rate of transfer of the pesticide residue from black tea to the hot brew was largely influenced by physicochemical parameters, such as water solubility and octanol-water partition coefficient. Tea brews prepared from untreated black tea samples were fortified with standard solutions of the respective pesticides, extracted and analysed using GC and HPLC by following standardised methods. Results revealed that the rate of leaching of residues of these pesticides into the tea brew was low due to their low solubilities in aqueous medium and high octanol-water partitioning coefficients.     

A numerical study of a plate with a hole for a new class of elastic bodies

It has been shown recently that the class of elastic bodies is much larger than the classical Cauchy and Green elastic bodies, if by an elastic body one means a body incapable of dissipation (converting working into heat). In this paper, we study the boundary value problem of a hole in a finite nonlinear elastic plate that belongs to a subset of this class of the generalization of elastic bodies, subject to a uniaxial state of traction at the boundary (see Fig. 1). We consider several different specific models, including one that exhibits limiting strain. As the plate is finite, we have to solve the problem numerically, and we use the finite element method to solve the problem. In marked contrast to the results for the classical linearized elastic body, we find that the strains grow far slower than the stress.     

Controlled synthesis of MoO3 microcrystals by subsequent calcination of hydrothermally grown pyrazine–MoO3 nanorod hybrids and their photodecomposition properties

We present our results on successful synthesis of pyrazine–MoO₃ nanorod hybrids by using pyrazine and MoO₃ nanorods. On the first stage, MoO₃ nanorods were grown hydrothermally and, on the second stage, their mixture with pyrazine was again involved in a hydrothermal reaction to produce organic–inorganic hybrids. To understand the growth mechanism of the hybrids we varied time and temperature of the hydrothermal process. Intercalation of pyrazine was confirmed through X-ray diffraction analysis, X-ray photoelectron spectroscopy, X-ray emission spectroscopy, scanning electron microscopy methods. Upon calcinations, pyrazine was deintercalated, i.e. removed from the MoO₃ hybrid system, and the MoO₃ nanorods were found to bind together resulting in formation of MoO₃ microslabs with increased surface area. Photodecomposition performance of the MoO₃ nanorods, pyrazine–MoO₃ hybrids and MoO₃ microcrystals was studied against Procion Red MX-5B textile dye. A high photodecomposition performance was found to decrease when going from MoO₃ nanorods to MoO₃ microcrystal and, further, to pyrazine–MoO₃ hybrids.     

Optical and Microstructural Characterisations of Pulsed rf Magnetron Sputtered Alumina Thin Film

Alumina thin films were deposited on fused quartz and SS304 substrate by pulsed rf magnetron sputtering with both direct and reactive methods. The films were characterised by energy dispersive X-ray spectroscopy, X-ray diffraction, scanning electron microscopy, field emission scanning electron microscopy and atomic force microscopy to reveal the microstructure, surface morphology and topography of thin films. Transmittance and reflectance of alumina thin film were evaluated after deposition on the quartz substrate. Transmittance of the quartz remains almost un-altered when alumina was deposited by the reactive sputtering. A marginal decrease of ~4% in the transmittance of quartz was, however, observed after deposition of alumina by direct sputtering. Infrared emittance of the substrate also remains almost constant after deposition of thin alumina film. Further, as-deposited alumina on SS304 obtained by both direct and reactive sputtering process was amorphous in nature. However, after annealing crystalline peaks were observed.     

A thermodynamic framework for the modeling of crystallizable shape memory polymers

Shape memory polymers are a relatively new class of materials that have the ability to retain a temporary shape, which can be reset to the original shape with the use of a suitable trigger, typically an increase in temperature. The temporary shapes can be very complex and the deformations involved large. These materials are finding use in a large variety of important applications; hence the need to model their behavior. In this paper, we develop constitutive equations to model the thermo-mechanical behavior of crystallizable shape memory polymers. Crystallizable shape memory polymers are called crystallizable because the temporary shape is fixed by a crystalline phase, while return to the original shape is due to the transition of this crystalline phase. The modeling is carried out using a framework that was developed recently for studying crystallization in polymers and is based on the theory of multiple natural configurations. In this paper we formulate constitutive equations for the original amorphous phase and the semi-crystalline phase that is formed after the onset of crystallization. In addition we model the transition of the crystalline phase to capture the return of the polymer to its original shape. These models for shape memory effects in polymers have been developed within a full thermodynamic framework, extending our previous work in which the models were developed within a mechanical setting [G. Barot, I.J. Rao, Constitutive modeling of the mechanics associated with crystallizable shape memory polymers, ZAMP 57 (4) (2006) 652-681]. The model is applied to the problem of inflation and extension of a hollow cylinder. The results are consistent with what has been observed in experiments.     

A General Method for the Synthesis of 5H‐Benzo[b]‐, Carbazolo[2,3‐b]‐ and Indolo[2,3‐b]carbazole Derivatives via Copper(II) Triflate‐Catalyzed Heteroannulation

A straightforward approach for the construction of 5H‐benzo[b]‐, carbazolo[2,3‐b]‐ and indolo[2,3‐b]carbazole derivatives has been developed by using copper(II) triflate‐catalyzed heteroannulation.     

用超声波研究不同温度下4-氨基丁酸在硫酸柳丁氨醇水溶液中的性质(英文)

Ultrasonic speeds of 4-aminobutyric acid in 0.0041,0.0125 and 0.0207 mol·kg-1 aqueous salbutamol sulphate(SBS) solutions are measured at 308.15,313.15 and 318.15 K.Isentropic compressibility kS,change in isentropic compressibility△k S,relative change in isentropic compressibility( 0 S S △k /k) ,apparent molal compressibility kφ,limiting apparent molal compressibility k0 φ,transfer limiting apparent molal compressibility k0 φ,hydration number nH,pair and triplet interaction parameters kAS,kASS are estimated.The above parameters are used to interpret the solute-solute and solute-solvent interactions of 4-aminobutyric acid in the aqueous salbutamol sulphate solutions.     

A RHEOMETER FOR MEASURING THE PROPERTIES OF GRANULAR MATERIALS

A great many technological applications such as pneumatic handling of grains and minerals, drying of particles, gasification of solid fuels, require an understanding of the properties of granular solids. Material parameters which can describe the common phenomena exhibited by these granular materials, such as dilatancy, cohesion, adhesion, frictional resistance, etc. need to be incorporated in the model and methods devised for measuring and quantifying them. Reliable experiments are required to measure the properties of these materials. However, this branch of rheology has not been as well studied as the rheology of fluids due to the difficulties inherent to grannular materials in that they exhibit both solid-like and fluid-like properties. Here, we discuss the development of an instrument which can evaluate the material properties of grannular solids. Experimental investigations verify the commonly exhibited phenomena by these materials and estimate the various forces which are generated due to the flow of these materials, thereby enabling their characterization.     

Effects of thermal annealing on the electrical and structural properties of Pt/Mo Schottky contacts on n-type GaN

Thermal annealing temperature effects on the electrical and structural properties of platinum/molybdenum (Pt/Mo) Schottky contacts on n-type GaN have been investigated by current–voltage (I–V), capacitance–voltage (C–V), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques. As-deposited Pt/Mo/n-GaN Schottky diode exhibits barrier height of 0.75 eV (I–V) and 0.82 eV (C–V). Upon annealing at 400 and 500 °C, the barrier height slightly increased to 0.77 eV (I–V) and 0.92 eV (C–V) and 0.82 eV (I–V) and 0.97 eV (C–V), respectively. A maximum barrier height of 0.83 eV (I–V) and 0.99 eV (C–V) is obtained on the Pt/Mo contacts annealed at 600 °C. X-ray photoelectron spectroscopy results shows that the Ga 2p core-level shift towards the low-energy side for the contact annealed at 600 °C as compared to the as-deposited one. Based on the results of XPS and XRD studies, the formation of gallide phases at Pt/Mo/n-GaN interface could be the reason for the increase of Schottky barrier heights upon annealing at elevated temperatures. The atomic force microscopy (AFM) results showed that the Pt/Mo contact does not seriously suffer from thermal degradation during annealing even at 600 °C (RMS roughness of 5.41 nm). These results make Pt/Mo Schottky contacts attractive for high temperature device applications.     

Thermally stable and low-resistance W/Ti/Au contacts to n-type GaN

We report on the formation of thermally stable and low-resistance Ti/Au-based ohmic contacts to n-type GaN (4.0 × 10¹⁸ cm⁻³) by using a W barrier layer. It is shown that the electrical characteristic of the sample is considerably improved upon annealing at 900 °C for 1 min in a N₂ ambient. The contacts produce the specific contact resistance as low as 6.7 × 10⁻⁶ Ω cm² after annealing. The Norde and current–voltage methods are used to determine the effective Schottky barrier heights (SBHs). It is shown that annealing results in a reduction in the SBHs as compared to that of the as-deposited sample. Auger electron spectroscopy (AES), scanning transmission electron microscopy (STEM) and X-ray diffraction (XRD) examinations show that nitride and gallide phases are formed at the contact/GaN interface. Based on the AES, STEM and XRD results, a possible ohmic formation mechanism is described and discussed.