Synthesis of carbon coated nanocrystalline porous α-LiFeO2 composite and its application as anode for the lithium ion battery

In this work, we describe for the first time a high surface area nanocrystalline porous α-LiFeO₂-C composite anode material synthesized by a simple molten salt method, followed by a carbon coating process. The synthesized nanocomposite presents an interconnected porous architecture, as was confirmed by field emission scanning electron microscope observations. Transmission electron microscope investigations revealed that amorphous carbon was incorporated into the pores among the nanoparticles and that some nanoparticles were covered by a thin layer of amorphous carbon as well. Electrochemical measurements showed that the carbon played an important role, as it affected both the cycle life and the rate capability of the electrode. The α-LiFeO₂-C nanocomposite electrode delivered a higher reversible capacity and good cycle stability (540 mAh g⁻¹ at 1 C after 200 cycles) compared to the pure α-LiFeO₂ electrode. Good electrochemical performance of the α-LiFeO₂-C nanocomposite electrode could be attributed to the porous conductive architecture among the nanoparticles, which not only has benefits in terms of decreasing the absolute volume changes and increasing the mobility of lithium ions, but also offers conductive pathways along the whole interconnected wall in the structure, which is favourable for the transport of electrons, promotes liquid electrolyte diffusion into the bulk material, and acts as a buffer zone to absorb the volume changes. Our results indicate that α-LiFeO₂-C nanocomposite could be considered as a potential anode material for lithium-ion batteries.     

Electrokinetic potential of kaolinite clay in the presence of polystyrene sulfonate

The determination of the electrokinetic potential of clay is very important in many applications. Therefore, this work was aimed at studying the effect of poly(4‐ sodium styrene sulfonate) on the electrokinetic potential and the sedimentation behavior of kaolinite clays at different pH values and/or in the presence of sodium or calcium chlorides. At pH values lower than the point of zero charge (PZC) of the kaolinite clay, the zeta potential of Na‐ or Ca‐kaolinite in CaCl₂ solutions was higher than that in NaCl solutions at the same concentration. Above the PZC, the zeta potential of Na‐ or Ca‐kaolinite in NaCl solution was higher than that in CaCl₂ at the same electrolyte concentration. These results reflect the ability of calcium cations to compress the double layer of the kaolinite clay better than sodium cations. Also, below the PZC and at low concentrations of poly(4‐sodium styrene sulfonate), the zeta potential of the kaolinite clay suspensions had low value, while the sediment volumes had higher values. On the other hand, above the PZC at increasing polymer concentrations, the zeta potentials increased but the sediment volumes had lower values compared to those produced below the PZC. The data showed the zeta potential of Na‐kaolinite suspensions are higher than Ca‐kaolinite, producing lower sediment volumes of Na‐kaolinite compared to Ca‐kaolinite at the same concentrations of polymer and/or pHs. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1705–1711, 2006     

Thermal doping of rare-earth ions in gallium nitride

Doping of rare-earth ions in epitaxial gallium nitride material has been performed through a thermal diffusion process. The technique involves a brief photolytic etching of the surface followed by heating with a melt of rare-earth salt under reducing conditions. Europium-doped GaN pumped with above gap UV radiation showed strong red emission which was insensitive to a moderately strong magnetic field. The temperature dependence of the intensity of this red emission is also described. Neodymium caused surface pitting, through an unknown chemical mechanism, and consequent enhancement of defect-generated yellow luminescence.     

Preservation of fruits and vegetables using solar drier: a comparative study of natural and solar drying, III; chemical analysis and sensory evaluation data of the dried samples (grapes, figs, tomatoes and onions)

In spite of the detailed studies which have proved the superiority of the quality attributes for solar dried fruits and vegetable over that of naturally dried [1, 2, 3, 4 and 5], we have chosen in our investigation some parameters to be used as a guide to test the changes occurring for some nutrients like sugars. Another indicator has been used which was the percent ash to test the extent of contamination with sand from the surroundings. Consequently we can compare the properties and qualities of natural and solar dried fruits and vegetables to arrive at the preferred drying method.From the project results obtained for the dried fruits and vegetables using natural and solar drying, we can conclude that the mixed and indirect modes of drying were more effective than natural drying, since the final moisture contents for grapes were 12.5, 20.05 and 68.45%, respectively. The figs moisture was reduced to 23.5% using mixed mode drying and 46.9% in case of natural drying for the same period. No significant difference was noted in the case of tomatoes, while there was little significant difference between the two drying methods for onions, but the drying was higher for slices than lobes.There was a highly significant difference for percent ash between the solar dried grapes and naturally dried samples (2.95 and 12.1%, respectively).In sugar determination, the solar drying was found to alter the sugars more than natural drying. This is not surprising because the temperature inside the drying chamber was far higher (80.5°C).This study included also the sensory evaluation of the quality attributes (color, flavor and texture) of the dried samples. The fruits were presented to untrained panelists (consisting of engineers, employees, Ph.D. holders and workers from the Center for Solar Studies) who were asked to evaluate the fruits by scoring the attributes with grades ranged from 2 to 12, where 2=weakly accepted and 12=excellent quality.The data represent the relative frequency distribution ×100 (for color, flavor and texture) reported by the panelists using a hedonic scale from (1–12). Lower scores indicate poor quality (unacceptable) while higher scores indicate much better quality or highly acceptable.These data clearly indicate that the solar drying technique is much better from the sensory quality viewpoint when compared with the natural sun drying technique. Such conclusions are completely true for all samples except tomatoes, and both direct methods of drying as well as mixed mode approach of solar drying. Since negative findings were reported using the indirect approach.     

Laser pumped light emitting diodes as broad area sources of coherent radiation

This paper describes the use of large area light emitting diodes, pumped with various laser sources, as extended area emitters of coherent radiation. The photon recycling takes place through the intermediary of electron–hole pair formation and subsequent stimulated recombination. It is possible to generate both spontaneous and stimulated emission together and the two channels are then independent of each other. This allows the generation of a mixture of coherent and non-coherent radiation in any desired proportion. The technique described is a broad-band resonant process with diffusive feedback and can be used for generating non-collimated laser radiation for a variety of applications.     

Sign Language to Sentence Formation: A Real Time Solution for Deaf People

Communication is a basic need of every human being to exchange thoughts and interact with the society. Acute peoples usually confab through different spoken languages, whereas deaf people cannot do so. Therefore, the Sign Language (SL) is the communication medium of such people for their conversation and interaction with the society. The SL is expressed in terms of specific gesture for every word and a gesture is consisted in a sequence of performed signs. The acute people normally observe these signs to understand the difference between single and multiple gestures for singular and plural words respectively. The signs for singular words such as I, eat, drink, home are unalike the plural words as school, cars, players. A special training is required to gain the sufficient knowledge and practice so that people can differentiate and understand every gesture/sign appropriately. Innumerable researches have been performed to articulate the computer-based solution to understand the single gesture with the help of a single hand enumeration. The complete understanding of such communications are possible only with the help of this differentiation of gestures in computer-based solution of SL to cope with the real world environment. Hence, there is still a demand for specific environment to automate such a communication solution to interact with such type of special people. This research focuses on facilitating the deaf community by capturing the gestures in video format and then mapping and differentiating as single or multiple gestures used in words. Finally, these are converted into the respective words/sentences within a reasonable time. This provide a real time solution for the deaf people to communicate and interact with the society.     

A Framework for Systematic Classification of Assets for Security Testing

Over the last decade, a significant increase has been observed in the use of web-based Information systems that process sensitive information, e.g., personal, financial, medical. With this increased use, the security of such systems became a crucial aspect to ensure safety, integrity and authenticity of the data. To achieve the objectives of data safety, security testing is performed. However, with growth and diversity of information systems, it is challenging to apply security testing for each and every system. Therefore, it is important to classify the assets based on their required level of security using an appropriate technique. In this paper, we propose an asset security classification technique to classify the System Under Test (SUT) based on various factors such as system exposure, data criticality and security requirements. We perform an extensive evaluation of our technique on a sample of 451 information systems. Further, we use security testing on a sample extracted from the resulting prioritized systems to investigate the presence of vulnerabilities. Our technique achieved promising results of successfully assigning security levels to various assets in the tested environments and also found several vulnerabilities in them.     

Reciprocating flux-concentrated induction generator for free-piston generator

This paper presents and examines a self-excited tubular induction generator for a free-piston generator system. The induction generator utilizes flux concentration by eddy currents. The paper shows that leakage flux is thereby reduced in the proposed generator and its performance is greatly improved. A three-dimensional finite-element method is employed to investigate its performance. A comparison of the calculated and measured results for standstill thrust force confirms the validity of the model.