Microbial Decontamination of Tea (Camellia sinensis) by Gamma Radiation

ABSTRACT:  Processed dry tea leaves are prone to microbial contamination during post-processing handling and storage. The dry tea leaves may thus carry bacteria and fungi of potential health risk to consumers. Also, during storage under high humidity, absorption of moisture may encourage fungal growth and result in caking of the product. Gamma radiation processing was tried as a method for microbial decontamination. A radiation dose of 5 kGy was found to be effective for this purpose. No significant effect was observed on total phenolics in radiation-processed tea leaves. The antioxidant and biological properties of tea such as free radical scavenging activity, inhibition of xanthine oxidase and lipid peroxidation, and superoxide and nitrite scavenging activities were not affected due to radiation treatment within a dose of 10 kGy. The antimicrobial and sensory properties were also unaffected by the radiation treatment.     

Generation of solar spicules and subsequent atmospheric heating

Science China Technological Sciences -     

Dielectric behavior of perovskite glass ceramics

The recent developments of energy storage devices are concerned with larger energy storage ability, low loss and good temperature stability. It has a great technological importance in engineering science. The dielectric materials like ceramics and glass ceramics have great interest in electronic ceramic industry due to above concern. The ceramic dielectrics are used as a capacitive element in electronic circuits. The perovskite glass ceramics have very high dielectric constant and low dielectric loss. The high dielectric constant in glass ceramics is attributed to space charge polarization. In order to produce glass ceramics of high dielectric constant, barium titanate glass ceramics is the first discovered ferroelectric perovskite. In this review article, we are summarizing the dielectric behavior of perovskite glass ceramics such as BaTiO₃, SrTiO₃, PbTiO₃, (Ba,Sr)TiO₃ and (Pb,Sr)TiO₃.     

Effect of stabilizer on structural, optical and electrochemical properties of sol–gel derived spin coated TiO2 films

Thin films of TiO₂ were prepared using two different sol–gel routes. The two routes employed diethanolamine (DEA) and acetylacetone as stabilizing agents with titanium isopropoxide (Ti(OPrⁱ)₄) in ethanol as the deposition solution. The densification at 500 °C achieved the nanophase TiO₂ films, which were investigated by performing structural, optical and electrochemical studies. Ion storage capacity and transmission measurements showed superior response of the films derived from DEA. Between the films obtained from the two routes, the appearance of the rutile phase at lower temperature for the film synthesized using DEA was predicted on the basis of the thermal analysis of the corresponding xerogel. The nanocrystalline nature of the films was evident from the X-ray diffraction, atomic force microscopy, and scanning electron microscopy. The films deposited from both the stabilizers exhibited electrochromism in 1 M LiClO₄-propylene carbonate electrolyte on cathodic polarization.     

Sol–gel derived nanocrystalline CeO2–TiO2 coatings for electrochromic windows

Mixed CeO₂–TiO₂ coatings synthesized by sol–gel spin coating process using mixed organic–inorganic Ti(OC₃H₇)₄ and CeCl₃·7H₂O precursors with different Ce/Ti mole ratios were investigated by a wide range of characterization techniques. The attempts were directed towards achieving coatings with high transparency in the visible region and good electrochemical properties. Elucidation of the structural and optical features of the films yielded information on the aspects relevant to their usage in transmissive electrochromic devices. The films have been found to exhibit properties for counter electrode in electrochromic smart windows in which they are able to retain their transparency under charge insertion, high enough for practical uses. The high optical modulation and fastest switching for WO₃ film in the device configuration with the Ce/Ti (1:1) film is interpreted in terms of conducive microstructural changes induced by addition of TiO₂ in an amount equivalent to CeO₂.     

Simulation model for sizing of stand-alone solar PV system with interconnected array

Solar PV arrays made of interconnected modules are comparatively less susceptible to shadow problem and power degradation resulting from the aging of solar cells. This paper presents a simulation model for the sizing of stand-alone solar PV systems with interconnected arrays. It considers the electricity generation in the array and its storage in the battery bank serving the fluctuating load demand. The loss of power supply probability (LPSP) is used to connote the risk of not satisfying the load demand. The non-tracking (e.g., fixed and tilted) and single-axis tracking aperture arrays having cross-connected modules of single crystalline silicon solar cells in a (6×6) modular configuration are considered. The simulation results are illustrated with the help of a numerical example wherein the load demand is assumed to follow uniform probabilistic distribution. For a given load, the numbers of solar PV modules and batteries corresponding to zero values of LPSP on diurnal basis during the year round cycle of operation are presented. The results corresponding to the surplus and deficit of energy as a function of LPSP are also presented and discussed to assess the engineering design trade offs in the system components.Furthermore, a simple cost analysis has also been carried out, which indicates that for Delhi the stand-alone solar PV systems with fixed and tilted aperture arrays are better option than those with single-axis tracking aperture (with north–south oriented tracking axis) arrays.     

Crystal structure and magnetic property of Nd doped BiFeO3 nanocrytallites

Bi_1-xNd_xFeO₃ (BNFO_x, x = 0-0.15) nano-crystallites were successfully synthesised by solution combustion technique. Neodymium substitution has changed the rhombohedral symmetry of BiFeO₃ to the triclinic and reduced the impurity phase. The average particle size found to vary from 74 to 26 nm when Nd concentration was increased from x = 0 to 0.15. The change in the symmetry is also confirmed by Raman spectra of nanocrystallite samples. The value of remnant magnetization has improved due to the continuing collapse of the space-modulated spin structure of BNFO_x. Long-range ferromagnetic ordering in BNFO_x at room temperature was also confirmed from Mössbauer spectra.     

Synthesis of satellite footprint patterns from rectangular planar array antenna by using swarm‐based optimization algorithms

A pattern synthesis method based on Firefly Algorithm (FA) and Artificial Bee Colony (ABC) optimization has been presented to generate satellite footprint patterns from a rectangular planar array of isotropic antennas by modifying the amplitude, phase, and the state of the array elements. Three cases comprising three different footprints of rectangular, square, and circular boundary are generated from the same array by using two different swarm‐based optimization algorithms FA and ABC. Both the algorithms, following the proposed procedures are able to generate the three different footprint patterns while maintaining a satisfactory lower peak side lobe level and ripple. A comparative analysis has been carried out between FA, ABC, and Genetic Algorithm (GA) for the presented problem in terms of fitness value for the three different cases. The superiority of FA and ABC over GA has been established in terms of finding better solutions for all the three cases of the proposed problem. Copyright © 2013 John Wiley & Sons, Ltd.