Influence of Liquid Phase Additives on Structural and Sintering Behaviour of Samarium Modified Lead Titanate Ceramics

The combination of metal oxides Bi₂O₃:Li₂O in a ratio 89:11 gives a eutectic with a melting point of ～680°C. Such a low melting point oxide combination creates a working liquid phase at a highly favorable temperature for use as a densification aid. A liquid—phase sintering aid incorporating Bi₂O₃ and Li₂O is presented which demonstrates not only a reduction in the required sintering temperature but also shows relatively higher ‘c/a’ ratio (tetragonality) of PbTiO₃ ceramics with no fragility of the samples. Detailed dilatometric investigations have been performed in order to study the dominant shrinkage mechanism in the present system. Besides acting as a liquid phase fluxing agent, Bi₂O₃/Li₂O also behave as Curie shifter, which decreases Curie temperature in lead titanate system. The Curie temperature has also been verified from the thermal expansion behavior of sintered specimens. The value of dielectric constant increases after poling which may be due to the dominance of 180° domain wall over 90°.     

Modeling Compression Behavior of Structured Geomaterials

The influence of the natural (or artificially induced) structure of a geomaterial on its compression behavior is investigated. An approach for modeling this influence for various structured geomaterials is proposed by using the disturbed state concept. An isotropic compression model is formulated on three basic assumptions. A special version of the proposed model is also described for situations where the compression is one-dimensional. The proposed compression model is used to simulate the behavior of a variety of structured geomaterials such as clays, sands, calcareous soils, clay-shale, soft rock, unsaturated soils, and soils artificially treated by adding chemical agents or mechanical reinforcement, and the model is evaluated on the basis of these simulations. A general discussion on the influence of the structure of geomaterials on their mechanical properties is also presented.     

Biological and health implications of toxic heavy metal and essential trace element interactions

Human civilization and a concomitant increase in industrial activity has gradually redistributed many toxic metals from the earth's crust to the environment and increased the possibility of human exposure. Among the various toxic elements, heavy metals cadmium, lead, and mercury are specially prevalent in nature due to their high industrial use. These metals serve no biological function and their presence in tissues reflects contact of the organism with its environment. They are cumulative poison, and are toxic even at low dose. Studies of metabolism and toxicity of these elements have revealed important interactions between them and some essential dietary elements like calcium, zinc, iron, selenium, copper, chromium, and manganese. In general, a deficiency of these essential elements increases toxicity of heavy metals, whereas an excess appears to be protective. While most of the observations are on laboratory animals, limited human data are in agreement with the results of animal experiments. These suggest that the dietary presence of the essential elements may contribute to the protection of man and animal from the effects of heavy metal exposure, while their deficiency may increase toxicity. Appropriate dietary manipulation thus may be valuable in the prevention and treatment of heavy metal toxicity.     

Mechanical,morphological, and thermogravimetric analysis of alkali-treated Cordia-Dichotoma natural fiber composites

ABSTRACT

Usage of composites with natural fiber reinforcement is drastically increasing in recent times because of their low density, biodegradable nature, and low cost. However, natural fibers have certain core problems such as poor adhesion between the fiber and matrix and a relatively high degree of moisture absorption. Alkaline treatment of natural fibers is aimed at improving the adhesive strength so that effective stress transferability takes place in the composite. In the present work, Cordia-Dichotoma fibers were treated with sodium hydroxide (NaOH) and composites were prepared with different weight ratios of these fibers reinforced with epoxy. The prepared composites were tested for their tensile and flexural strengths (mechanical properties). Besides, for a comprehensive material characterization, IR spectroscopy (FT-IR), scanning electron microscope, and thermogravimetric analysis were carried out. This work investigates the influence of aforementioned NaOH treatment on thermal, mechanical, and morphological properties of the composite material.     

Effect of machining parameters in ultrasonic vibration cutting

The ultrasonic vibration cutting (UVC) method is an efficient cutting technique for difficult-to-machine materials. It is found that the UVC mechanism is influenced by three important parameters: tool vibration frequency, tool vibration amplitude and workpiece cutting speed that determine the cutting force. However, the relation between the cutting force and these three parameters in the UVC is not clearly established. This paper presents firstly the mechanism how these parameters effect the UVC. With theoretical studies, it is established that the tool–workpiece contact ratio (TWCR) plays a key role in the UVC process where the increase in both the tool vibration parameters and the decrease in the cutting speed reduce the TWCR, which in turn reduces both cutting force and tool wear, improves surface quality and prolongs tool life. This paper also experimentally investigates the effect of cutting parameters on cutting performances in the cutting of Inconel 718 by applying both the UVC and the conventional turning (CT) methods. It is observed that the UVC method promises better surface finish and improves tool life in hard cutting at low cutting speed as compared to the CT method. The experiments also show that the TWCR, when investigating the effect of cutting speed, has a significant effect on both the cutting force and the tool wear in the UVC method, which substantiates the theoretical findings.     

Sensory evaluation of black pigmented rice (Oryza sativa cv. Poireton) wine fortified with probiotic Lactobacillus acidophilus ATCC 4356 and Lactobacillus sakei ATCC 15521 using fuzzy logic

Rice wine was prepared in the laboratory from a black pigmented rice (cv. Poireton) using standardized methodology. The wine was fortified with the probiotic strains Lactobacillus acidophilus ATCC 4356 and Lactobacillus sakei ATCC 15521 and allowed to undergo a storage period of 28 days at 4°C. These rice wines were compared with a commercial wine used as a standard reference wine. A panel consisting of 30 judges performed the sensory evaluation. The scores obtained were based on the quality attributes of colour, taste, aroma and alcoholic strength. Analysis of the sensory scores and ranking of the different samples were performed using fuzzy analysis. The quality attributes were also ranked according to their importance in the overall acceptability. Colour and alcoholic strength were accorded the highest importance, compared with aroma and taste, as quality attributes. The rice wines were rated as ‘not satisfactory’, ‘fair’, ‘medium’, ‘good’ and ‘excellent’ on the sensory scale. Out of the wines prepared, black pigmented rice wine fortified with L. acidophilus was the most acceptable and was ranked as ‘good’, which was also at par with the commercial wine. On the other hand, black pigmented rice wine fortified with L. sakei and black pigmented rice wine fortified with L. acidophilus and L. sakei were ranked in the ‘satisfactory’ category followed by the unfortified wine ranked in the ‘fair’ category. Copyright © 2015 The Institute of Brewing & Distilling     

Autonomous clustering using rough set theory

This paper proposes a clustering technique that minimizes the need for subjective human intervention and is based on elements of rough set theory （RST）. The proposed algorithm is unified in its approach to clustering and makes use of both local and global data properties to obtain clustering solutions. It handles single-type and mixed attribute data sets with ease. The results from three data sets of single and mixed attribute types are used to illustrate the technique and establish its efficiency.     

Evaluation of hydrogen metabolism by Escherichia coli strains possessing only a single hydrogenase in the genome

The four hydrogenase isozymes; hydrogenase 1 (Hyd-1), hydrogenase 2 (Hyd-2), hydrogenase 3 (Hyd-3) and hydrogenase 4 (Hyd-4) of Escherichia coli have been reported for their crucial functions in the hydrogen metabolism; however, their distinctive roles could not be completely understood. In this study, four ideal hydrogenase operon mutants, Δhyb hyc hyf, Δhya hyc hyf, Δhya hyb hyf, and Δhya hyb hyc, in which only a single hydrogenase is intact in the genome, were constructed as well as one quadruple mutant (Δhya hyb hyc hyf) that all four hydrogenase operons were deleted. First, single operon mutants and single-gene mutants for each hydrogenase showed different hydrogen productivity and growth in the anaerobic fermentation, indicating that bacterial phenotype regarding the hydrogen metabolism via the deletion of each operon is different with that of each single gene. Then, 4 triple hydrogenase operon mutants and one quadruple mutant were investigated to evaluate the hydrogen metabolism (hydrogen production and uptake) using glucose or glycerol as a substrate of hydrogen fermentation. With both the carbon sources, only Hyd-2 and Hyd-3 were able to produce hydrogen. Furthermore, all the hydrogenases showed hydrogen uptake activity. In addition, no hydrogen production and hydrogen uptake were detected in the quadruple mutant which does not have all 4 hydrogenases. Hydrogen production from Hyd-2 and Hyd-3 was further confirmed by complementing their operons in the cloning vector pBR322.     

Tunable Terahertz Circularly Polarized Dielectric Resonator Antenna with the Higher Order Modes

Silicon - A tunable terahertz (THz) dielectric resonator (DR) antenna (DRA) with circular polarization operating with multiple higher order modes is numerically studied and implemented. A...     

Synthesis of trideuteratedO-alkyl platelet activating factor and lyso derivatives

Racemic heavy isotope analogs of 1-O-alkyl-sn-glycero-3-phosphocholine (lysoPAF) and 1-O-alkyl-2-O-acetyl-sn-glycero-3-phosphocholine (PAF) were prepared for use as internal standards to facilitate quantitative studies based on mass spectrometry. Starting from pentadencane-1,15-diol andrac-glycerol-1,2-acetonide, a convergent synthesis of 1-O-[16′-²H₃]hexadecyl and 1-O-[18′-²H₃]octadecylrac-glycero-3-phosphocholine and their acetyl derivatives is described. Three deuterium atoms were introduced at the terminal position of the 1-O-alkyl group by displacement of thep-toluensulfonyl group from 1-O-alkyl-15′-p-toluensulfonate and 1-O-alkyl-17′-p-toluensulfonate with [²H₃]-methylmagnesium iodide. The 1-O-alkyl-17′-p-toluensulfonate was obtained by reaction of the 1-O-alkyl-15′-p-toluensulfonate with allylmagnesium bromide, followed by reductive ozonolysis and treatment withp-toluenesulfonyl chloride. The hydroxyl group at C-2 was protected by a benzyl group and removed at a late stage in the synthesis. This provided the corresponding lysoderivatives or allowed preparation of racemic PAF by subsequent acetylation of the free hydroxy group. The phosphocholine moiety was introduced at glycerol C-3 by reaction with bromoethyldichlorophosphate and trimethylamine. The synthetic compounds were analyzed by FAB/MS and GC/NICIMS. They were shown to contain less than 0.6% protium impurity.