Mechanical Behavior of Diamond-Sawn Multi-Crystalline Silicon Wafers and its Improvement

Poor mechanical property is identified as a potential barrier to commercial development of diamond wire sawn multi-crystalline silicon wafers. 3-point bending tests of the diamond-sawn multi-crystalline silicon wafer samples, along with those of mono-crystalline silicon and of the slurry-sawn wafers for references, were carried out. The bending in two orthogonal orientations relative to the cutting marks was tested respectively. Critical strain at breakage is chosen to indicate the wafer’s strength against breakage in bending. Effective elastic moduli of the different wafer samples in bending were also measured. The results show that, compared to slurry-sawn silicon wafers, diamond-sawn silicon wafers, either of mono-crystalline or multi-crystalline, are stronger in the direction parallel to the cutting marks, and weaker in the direction vertical to the cutting marks; more importantly, for diamond-sawn multi-crystalline silicon wafers, a very low critical strain level, ～57 % of the slurry-sawn multi-crystalline silicon wafers, is identified, in their direction vertical to the cutting marks. In view of the relevance of the critical strain to the breakage rate for the main stream slurry-sawn wafers, this would cause an unacceptably high breakage rate in industrial production and application of the diamond-sawn multi-crystalline silicon wafers. Annealing was found to significantly raise the critical strains of various wafers, and encouragingly, annealing at temperature as low as 400 °C can raise the critical strain of the diamond-sawn multi-crystalline silicon wafers to a level similar to that of the slurry-sawn multi-crystalline silicon wafers.     

Determination of Fexofenadine in Tablets by Capillary Electrophoresis in Free Solution and in Solution with Cyclodextrins as Analyte Carriers

ABSTRACT

Capillary electrophoresis (CE) methods for the determination of fexofenadine (FEX) in commercial pharmaceuticals were developed. It was demonstrated that FEX could be effectively analyzed in free solution cationic CE at low pH. Another analytical approach studied was based on cyclodextrin (CD) modified CE where highly charged CD derivatives served as analyte carriers. In this way, the separation range was spread to physiological pH region and a CE analysis of FEX, present actually in its zwitterionic form, could be accomplished. Several parameters affecting the separations were studied, including the type and concentration of carrier ion, counterion, analyte carrier, and pH of the buffer. The methods based on the free solution CE and CD-modified CE were compared each other, validated, and applied for the determination of FEX in tablets.     

The compressibility and compactibility of different types of lactose

Objective: The purpose of this study was to investigate and quantify flow properties, compressibility, and compactibility of various pharmaceutical lactose powders found on the market today (DCL-11, DCL-21, M‐200, Flowlac-100, and Tablettose 70, 80, and 100). Methods: Flow properties were estimated by measuring flow time, angle of repose, and the Hausner ratio. Particle rearrangement was studied using Kawakita's linear model. Compressibility was studied using two ‘out-of-die’ methods: (i) the Heckel model and (ii) a modified Walker model. Compactibility was quantified using two methods: (i) the tensile strength profile (Cp) and (ii) the compactibility factor (Pr). Statistical approach was used to analyze the results. Results: Flow properties of all materials were passable or better, except for M-200, which has very poor flowability. Compressibility results demonstrated that the most compressible lactose is spray-dried grade of lactose (Flowlac-100) and the least compressible is milled lactose (M-200). Compactibility studies showed that β‐lactose (DCL-21) forms tablets with superior tensile strength in comparison with α-lactose. Conclusion: Results of the compressibility study showed that the discriminative power of modified Walker model is greater in comparison with Heckel model. Compactibility methods yield similar and comparable results.     

Raising chickens for increased egg consumption in a rural highland Bolivian population

In highland Bolivia a three-year nutrition-sensitive agricultural intervention was carried out with rural families in which chicken rearing was promoted in order to increase egg consumption. Here we report on the impact of the intervention on participants’ diets. The non-randomized intervention took place in 21 rural communities in the province of Tapacarí in the department of Cochabamba, Bolivia. Intervention communities had staggered start times, with two communities starting in 2013, three communities starting in 2014 and sixteen communities starting in 2015. Twenty-four hour dietary recall data were collected from all individuals in 22 households in two communities in February/March 2013, 33 households in three communities in February/March 2014, and 66 households in fourteen communities in February/March 2015. We tested for changes from 2013 to 2014 to 2015 in consumption of 10 food groups in children under 6 years, adult men and adult women. By endline, egg production was established in ~80% of the intervention households. From baseline to endline egg consumption increased to approximately one-half egg/person/day: in children from 7 to 33 g/day, in women from 6 to 33 g/day, and in men from 6 to 39 g/day. Despite the increased intake in eggs, intake of most nutrients did not change. Higher egg consumption would be required to produce observable average increases in nutrient intake.     

Topic detection and tracking on heterogeneous information

Given the proliferation of social media and the abundance of news feeds, a substantial amount of real-time content is distributed through disparate sources, which makes it increasingly difficult to glean and distill useful information. Although combining heterogeneous sources for topic detection has gained attention from several research communities, most of them fail to consider the interaction among different sources and their intertwined temporal dynamics. To address this concern, we studied the dynamics of topics from heterogeneous sources by exploiting both their individual properties (including temporal features) and their inter-relationships. We first implemented a heterogeneous topic model that enables topic–topic correspondence between the sources by iteratively updating its topic–word distribution. To capture temporal dynamics, the topics are then correlated with a time-dependent function that can characterise its social response and popularity over time. We extensively evaluate the proposed approach and compare to the state-of-the-art techniques on heterogeneous collection. Experimental results demonstrate that our approach can significantly outperform the existing ones.     

A circular inhomogeneity with mixed-type imperfect interface under in-plane deformations

We investigate the in-plane deformations of a circular inhomogeneity bonded to an infinite matrix through a mixed-type imperfect interface when the matrix is subjected to remote uniform stresses. The inhomogeneity and the matrix are endowed with separate and distinct Gurtin–Murdoch surface elasticities yet bonded together through a spring-type imperfect interface. This arrangement in which a soft interface (represented by the spring model) is bounded by two stiff interfaces (from the surface elasticities) is referred to as a ‘mixed-type imperfect interface’. A closed-form solution to the corresponding deformation problem is obtained via the use of complex variable methods, in particular, analytic continuation. We show that the introduction of the mixed-type imperfect interface leads to stress distributions in the composite which depend on six size-dependent parameters. In particular, the stress distribution inside the inhomogeneity is shown to be generally non-uniform except when a particular condition (which we identify explicitly) is satisfied by the material parameters, in which case the internal (size-dependent) stress distribution is uniform for any uniform remote loading. Finally, our solution is used to study the design of neutral and harmonic elastic inhomogeneities.     

High‐performance porous lead/graphite composite electrode for bipolar lead‐acid batteries

In general, thicker active material bipolar electrode's specific capacity and cycle life are very poor owing to its low bonding strength between the active material and the substrate and the diffusion rate of the sulfuric acid electrolyte inside the active material. In this paper, we synthesize a novel attached and porous lead/graphite composite electrode for bipolar lead‐acid battery and can effectively solve these problems. The graphite/polytetrafluoroethylene emulsion is employed to improve the bonding strength and conductivity and the porous can provide electrolyte diffusion channels. The specific capacities of 2‐mm thick positive active material at 0.25, 0.5, 1 and 2 C can attain 75.99, 58.98, 47.97, and 33.36 mAh·g^?1. The discharge voltage platform is also relatively high and no rapid decline with increasing discharge rate. Furthermore, after 80 cycles, the specific capacity does not drop evidently. Copyright © 2017 John Wiley & Sons, Ltd.     

Saccharopine Dehydrogenase Activity in the High-Lysine Opaque and Floury Maize Mutants

Lysine is an essential amino acid normally present in very low concentration in cereal seeds. In previous reports we have studied the metabolism of lysine in several distinct high-lysine maize mutants and observed drastic variations in the activity of saccharopine dehydrogenase (SDH), a key enzyme involved in lysine degradation. We have now analyzed the activity of SDH using non-denaturing polyacrylamide gel electrophoresis (PAGE) to identify possible isoenzymes that could explain the patterns of activity previously observed. The results indicated the presence of at least two SDH isoenzymes, one contributing to approximately 90% of the total enzyme activity and a minor form only present in the wild type lines and the opaque-1 mutant. The results suggest that the differences in total SDH activity among the genotypes tested are due to alterations in the predominant SDH isoenzymic form, which is likely to be the bifunctional polypeptide containing lysine 2-oxoglutarate reductase.     

Policy options towards an energy efficient residential building stock in the EU-27

The EU-27 residential building stock offers high potential for energy efficiency gains. The policies already in place or proposed to improve the energy efficiency and thus the environmental performance focus on new buildings and major renovations of existing buildings. However, there might be additional measures that could lead to further energy efficiency improvements. In particular, the installation of roofs or windows that show a high thermal efficiency outside major renovations offer a large improvement potential. In this study, the potential environmental and economic impacts of two types of such policy options were analysed: first, measures that require high energy efficiency standards when roofs or windows have to be replaced; and, second, measures that accelerate the replacement of building elements. The results suggest that the two policies offer the potential for substantial additional energy savings. In addition, the installation of energy efficient building elements comes at negative net cost. When the replacement of building elements is accelerated, however, the additional costs do not outweigh the energy cost savings.