Preparation and Properties of Biodegradable Spent Tea Leaf Powder/Poly(Propylene Carbonate) Composite Films

The aim of the present work is to develop novel bio-based lightweight material with improved tensile and thermal properties. Spent tea leaf powder (STLP) was used as a filler to improve the tensile and thermal properties of polypropylene carbonate (PPC). Tea is an important material used in hotels and households, and spent tea leaf is a resulting solid waste. Composite films with STLP were obtained by the solution casting method. These films were characterized by optical and scanning electron microscopy, Fourier transform-infrared spectroscopy, thermogravimetric analysis, and tensile testing to examine the effect of filler content on the properties of the composites. The results showed that composite films have increased tensile strength due to enhanced interfacial adhesion between the filler and the matrix. In addition, the composite films also exhibited higher thermal degradation temperatures than pure polypropylene carbonate. The morphology results indicate that there is a good interface interaction between STLP and PPC. Results of the study reveal STLP to be a promising green filler for polymer plastics.     

Catalytic oxidative conversion of alcohols, aldehydes and amines into nitriles using KI/I2-TBHP system

The oxidative conversion of alcohols, aldehydes and amines to give corresponding nitriles in excellent yields was easily achieved by the catalytic amount of KI or I₂ in combination with TBHP as an external oxidant. This non-transition metal catalyst is cost effective and provides easy work-up and separation of the product.     

Nanostructured ZnO thin film for hydrogen peroxide sensing

A thin film of zinc oxide (ZnO) was deposited over the surface of a glass substrate by spray pyrolysis technique. To obtain ZnO thin film with nano-grains in this process, the substrate temperature was optimized and fixed at 503 K. Zinc acetate dihydrate was used as a precursor at an optimal concentration of 0.05 M. The structural and morphological properties of the film were investigated using X-ray Diffraction (XRD) and Field Emission–Scanning Electron Microscopy (FE–SEM), respectively. The peaks in the XRD pattern, confirmed the polycrystalline nature of the film with hexagonal wurtzite structure. Purity of the film has been confirmed through Energy Dispersive X-ray analysis (EDAX). Further the sensing behavior of the film was studied for various concentrations of hydrogen peroxide (H₂O₂) at optimized operating temperatures of 323 and 373 K. The nanostructured ZnO film exhibited good sensitivity in the range of 500 and rapid response–recovery time of 30–60 s, respectively, towards lower concentrations of H₂O₂.     

Optical properties of melamine based materials

The melamine based crystalline materials are synthesized. To determine the optical properties the transmittance and reflectance spectra are recorded. The absorption coefficient of the materials is calculated using the recorded transmittance values. From the absorption coefficient values the insulating behavior of all our studied materials is identified. In addition the direct bandgap transition nature of the materials is recognized from the absorption coefficient value. Tauc relation is used to determine the bandgap energy. The bandgap energy values suggest the dielectric nature of the materials and interpretation is given for high dielectric constant values.     

Solvent-free protocol for amide bond formation via trapping of nascent phosphazenes with carboxylic acids

A solvent-free synthesis of amides via the coupling of phosphazenes with carboxylic acids is reported. Increasing the rate of heating either by microwave irradiation or conventional heating results in multifold increase in the rate of amide bond formation. Synthesis of a library of amides including a potent antitumour candidate has been accomplished.     

A unique control strategy to improve the life cycle of the battery and to reduce the thermal runaway for electric vehicle applications

This paper presents a unique thermal control strategy to improve the ageing of the battery and to maintain the internal temperature of the battery within the optimum limit of 20 °C–40 °C for electric vehicle (EV) applications. The hybrid EV system encompasses photovoltaic (PV) module, high power density device supercapacitor (SC) and high energy density Li-ion battery (LIB) as an energy storage element. The vehicle dynamics encounter frequent voltage fluctuations in the direct current (DC) bus, which ultimately reduces the lifecycle of the battery and also the heat is generated inside the battery when it is connected in parallel to the DC bus. The frequent charging/discharging of LIB is controlled by the unique thermal control strategy of the hybrid EV system. The DC bus voltage is controlled by the SC bi-directional converter (BDC) where, the battery BDC delivers the essential constant current from the main source (PV) to the DC bus. This unique thermal control strategy supports the distribution of power from the PV/LIB/SC hybrid source system to the EV and also improves the battery life cycle. Due to constant charging/discharging of battery the thermal runaway (TR) problem such as leak, smoke, gas venting, rapid disassembly, flames etc., can be eliminated. Decoupling of load power and battery power comprises the growth in the battery lifecycle and to maintain the optimum internal temperature of the LIB by conditional flow of current through hybrid thermal management system (HTMS). To certify the thermal control strategy and to estimate the performance of HTMS, a simulation of a hybrid source system with vehicle dynamics is performed in MATLAB/Simulink. Numerical analysis of the LIB during constant charging/discharging is performed using ANSYS fluent software to validate the temperature effect of HTMS.

     

Observation of subcellular structures of neurons by an illumination mode near-field optical microscope under an optical feedback control

We propose an illumination mode near-field optical microscope operated under an optical feedback for imaging biological specimens in their natural environment. For feedback control, rapidly varying evanescent signal has been generated over the sample surface. It has been found that evanescent signal can be profitably used as a control signal by utilizing its sample feature dependent discrimination sensitivity. Neurons have been successfully observed both in air and in liquid with a resolution well beyond the diffraction limit.