A comparison of lipids from liver and hepatoma subcellular membranes

Subcellular fractions of nuclei, mitochondria, endoplasmic reticulum, plasma membrane and cytosol were prepared from liver and hepatoma 72288CTC. Marker enzyme activities, biochemical compositions and electron microscopy were used to establish purity. Hepatoma NADH: cytochrome C reductase and 5′-nucleotidase exhibited abnormal subcellular distributions. The lipids from the subcellular fractions were examined in detail. Mitochondria and plasma membranes were characterized by elevated percentages of diphosphatidylglycrerol and sphingomyelin, respectively, in both tissues. All hepatoma subcellular fractions contained dramatically elevated levels of sphingomyelin and cholesterol, two components that form preferential strong complexes in vitro. The fatty acid composition of hepatoma sphingomyelin differed markedlg from liver and, unlike liver, did not exhibit organelle specific compositions. Some hepatoma lipid classes contained reduced percentages of palmitate while others contained higher levels. Hepatoma phosphatidylcholine and phosphatidylethanolamine from organelles contained lower percentages of long chain polyunsaturated fatty acids than liver. Generally, unique fatty acid profiles exhibited by individual phospholipid classes of liver subcellular fractions were absent or much reduced in the hepatoma. The ratios of oleate to vaccenate were near one for most of the phospholipid classes of most liver fractions, but all hepatoma classes, with few exceptions, contained a much higher percentage of oleate in all subcellular fractions. The hypothesis is proposed that the origin of some acyl moieties for the biosynthesis of various hepatome lipid classes differs from liver sources. The possible changes in acyl pools, sources and compartments for complex lipid biosynthesis could result in change in the quantities of molecular species that could contribute to the abnormal properties of the hepatoma membranes.     

A semantic approach to a framework for business domain software systems

In enterprise firms, enormous amounts of electronic documents are generated by business analysts and other business domain application users. Applications that use these documents are often driven by business logic that is hard-coded together with application logic. One approach to the separation of business logic from applications is to create and maintain business and information extraction rules in an external, user-friendly format. The drawback of such an externalization is that the business rules, usually, do not have machine interpretable semantics. This situation often leads to misinterpretation of domain analysis documents, which can inhibit the productivity of computer-assisted analytical work and the effectiveness of business solutions. This paper proposes an ontology and rule-based framework for the development of business domain applications, which includes semantic processing of externalized business rules and to some extent externalization of application logic. The creation of external information extraction rules by the business analyst is a cumbersome and time consuming task. In order to overcome this problem, the framework also includes a rule learning system to semi-automate the generation of information extraction rules from source documents with the help of manual annotations. The main idea behind the work presented in this paper is to re-engineer very large enterprise information systems to adapt to Semantic Web computing techniques. The work presented in this paper is inspired by an industrial project.     

Design methodology for configurable analog to digital conversion using support vector machines

We apply a support vector machine (SVM) classifier to the design of analog to digital converters. Each output bit of the converter is the output of a binary classifier, which is a nonlinear SVM. The classifier effectively learns a folding characteristic for each bit, which is realized as the weighted sum of a set of kernel functions. In our proposal, the kernel does not need to be symmetric or positive definite, unlike in the case of a conventional SVM. This makes the approach more amenable to VLSI design, where such constraints are hard to satisfy. The SVM uses a set of binary weights, which allows the folding characteristics to be digitally corrected after fabrication. This facility is of considerable value in analog design in a deep sub micron era, where simulation models do not adequately capture the behavior of devices, or their variations. The proposed methodology reduces design time, can be automated and calibrated for process variations and ageing, by changing a set of digital scaling coefficients.     

Active power filters — Recent advances

Power electronic loads inject harmonic currents into the utility causing overheating of power transformers and neutral wires, the power system, unpredictable performance of protection systems etc. In addition, electric resonances in such loads can also cause other undesirable phenomena like voltage fluctuations, ratio frequency interference (RFI) etc. To mitigate these undesirable effects, a new class of power electronics equipment (Active Filters) is being considered. A review of present-day solutions in the area of active filters is conducted in this paper. Finally, this paper discusses the trends in the design of active filters and the factors influencing them.     

Structural properties of amorphous hydrogenated silicon usingab initio molecular dynamics simulations

We have studied structural properties of amorphous hydrogenated silicon usingab initio molecular dynamics simulations. A sample was generated by simulated annealing using periodic boundary conditions with a supercell containing 64 silicon and 8 hydrogen atoms. The radial pair distribution functions for Si-Si, Si-H and H-H have been studied at 300 K and are found to be in good agreement with experimental data. Our results show that hydrogen saturates the dangling bonds and reduces bond strain. We also report existence of Si-H-Si bridge sites which are likely to play an important role in understanding the light induced metastability in this material.     

Fuel cells for non-automotive uses: Status and prospects

Fuel cells are in varying stages of commercialization for both automotive and non-automotive applications. The fuel cell industry has made substantial progress but still needs to reduce costs and improve performance to compete successfully with established technologies. In just 5 years, costs have been reduced by a factor of two while improving efficiency and durability. Based on interviews with fuel cell manufacturers in the U.S., Japan and the EU and information from published sources, a model of non-automotive fuel cell markets is constructed and used to estimate the impacts of government policies and to project the potential evolution of the industry to 2025. The model includes the effects of learning-by-doing, scale economies and exogenous technological progress on component and system costs, estimates customer choices between fuel cell and competing established technologies, and attempts to measure the impacts of government policies. With continued policy support it appears likely that the industry can become self-sustaining within the next decade.     

A mathematical model for mammary fatty acid synthesis and triglyceride assembly: the role of stearoyl CoA desaturase (SCD)

An increase in the proportion of unsaturated fatty acids in milk is considered desirable for human health. A prerequisite for the manipulation of milk fat composition is a co-ordinated understanding of the complex interactions in its biosynthesis. It has been suggested that an increase in the expression of mammary stearoyl-CoA-desaturase (SCD) would enrich mono-unsaturated fatty acids in milk, and therefore improve its nutritional properties. To investigate the potential effects of changes in expression of mammary enzymes and substrate availability on milk fat composition, we constructed, parameterized and evaluated a mechanistic mathematical model of fatty acid biosynthesis and milk-fat triglyceride assembly. The objective was to describe changes in the amount and composition of milk fat produced by bovine mammary cells due to changes in nutrition. Using the model we found that a 50% up-regulation in SCD activity increased the molar fraction of milk triglyceride 18:1 from 0.30 to 0.33 and 16:1 from 0.04 to 0.06. Up-regulation of SCD therefore did not appear to be the optimal method for increasing the content of unsaturated fatty acids in milk fat. The model was also used to determine the likely rate-limiting processes for the incorporation of unsaturated fatty acids into milk fat. Halving the concentration of glycerol 3-phosphate increased the molar fraction of milk triglyceride 18:1 from 0.30 to 0.35 and decreased the molar fraction of milk triglyceride 16:0 from 0.30 to 0.22. This achieved the desirable outcome of producing more unsaturated low-fat milk. Our model also predicted that a K232A mutation in the bovine mammary DGAT1 gene that is linked with an increase in milk fat yield would be consistent with a 120% increase in the DGAT acylation rate and also would be associated with a decrease in milk mono-unsaturated fatty acids.     

Investigation of N + SiGe Gate Stacked V-TFET Based on Dopingless Charge Plasma for Gas Sensing Application

Silicon - In this paper, a novel n + SiGe pocket layer gate stacked VTFET doping less charge plasma is proposed and analyzed using Silvaco TCAD simulation software. The proposed device...