Biliary and fecal steroid excretion in rats fed partially hydrogenated soybean oil

Male Wistar rats were fed cholesterol-free or cholesterol-enriched diets containing partially hydrogenated soybean oil with different levels of trans-fatty acids or unhydrogenated soybean oil at the 10% level. The linoleic acid content of hydrogenated fat diets was adjusted to 3.6% of the total energy. Hydrogenated fat diets contained 29% and 41% trans-acids, mainly as t-18:1. Trans-fats exerted no untoward effects on growth parameters, but increased liver weight. Dietary hydrogenated fats influenced neither the concentration nor composition of biliary steroids, irrespective of the presence or absence of cholesterol in the diet. In rats fed a cholesterol-free diet, daily fecal output of neutral and acidic steroids was enhanced by hydrogenated fats and the magnitude of augmentation was proportional to the dietary level of trans-fatty acids. The increased fecal steroid excretion corresponded to an increase in total excreta. Hydrogenated fats also tended to enhance bile acid excretion when feeding a cholesterol-enriched diet. The results suggest that dietary trans-fatty acids, in relation to cis-polyunsaturated fatty acids, provoke demonstrable change in steroid homeodynamics.     

Characterization of Na+/H+-antiporter gene closely related to the salt-tolerance of yeast Zygosaccharomyces rouxii

In order to clarify the relationship between salt-tolerance of Zygosaccharomyces rouxii and the function of Na⁺/H⁺-antiporter, a gene was isolated from Z. rouxii which exhibited homology to the Na⁺/H⁺-antiporter gene (sod2) from Schizosaccharomyces pombe. This newly isolated gene (Z-SOD2) encoded a product of 791 amino acids, which was larger than the product encoded by its Sz. pombe homologue. The predicted amino-acid sequence of Z-Sod2p was highly homologous to that of the Sz. pombe protein, but included an extra-hydrophilic stretch in the C-terminal region. The expression of Z-SOD2 was constitutive and independent of NaCl-shock. Z-SOD2-disruptants of Z. rouxii did not grow in media supplemented with 3 M -NaCl, but grew well in the presence of 50% sorbitol, indicating that the function of Z-SOD2 was closely related to the salt-tolerance of Z. rouxii. Several genes are also compared and discussed in relation to the salt-tolerance of Z. rouxii. The nucleotide sequence data reported in this paper will appear in the GSDB, DDBJ, EMBL and NCBI nucleotide sequence databases with the following accession number: D43629.     

Long-term characteristics of XLPE cables

To study the long-term characteristics of XLPE cables installed in free air and in water, aging tests were conducted under various testing conditions using XLPE cables with both 3.5 mm and 6 mm insulation. From the Weibull plots of lifetime distribution under the voltage stress E_L as the minimum breakdown strength, the minimum value of time to breakdown t_L under the constant voltage was estimated. The results of accelerated aging tests of XLPE cables installed in free air demonstrated that the V-t characteristics of XLPE cables could not be described by the conventional inverse power law (t ∝ V⁻ⁿ) with a single constant life exponent n. Based on the microscopic observation of a sliced insulation removed from XLPE cables, it was concluded that bow-tie trees with longer tree length observed in cables tested in water were caused by the moisture from outside, whereas the trees in cables tested in free air were caused by the residual moisture originally existing in the insulation. The breakdown strength of the aged cables tested in water increases through cable drying. However, it does not recover to the original values.     

Chemical etching of ZnSe crystals

Our report describes a newly developed chemical etchant suitable for producing mirror-like ZnSe surfaces. A mirror surface without any scratch obtained through lapping and polishing was produced by etching in a KMnO₄(100 mg)/ H₂SO₄(10 ml)/H₂O(40 ml) solution. The etching rate of ZnSe used in this case was about 1 um/min. The etchant could be applied to crystals with (lll)A, (lll)B, and (100) faces and the etching rate similar for each face. The value of the full width at half maximum in the x-ray rocking curve decreased by half after etching with the KMnO₄-system etchant.     

Sensor diagnosis system combining immune network and learning vector quantization

A distributed diagnosis system combining Immune Network (IN) and Learning Vector Quantization (LVQ) for detecting fault sensors accurately in industrial plants is proposed. It has two execution modes, namely, its training mode where LVQ extracts correlation between each two sensors from their outputs when they work properly, and its diagnosis mode, where LVQ contributes to testing each two sensors using the extracted correlation, while IN contributes to determining fault sensors by integrating these local testing results obtained from LVQ. Discussed here is how to improve diagnosis capability of the developed system. It is shown that the thresholds can be determined effectively by the constraint that the hyperregion corresponding to the normal sensor outputs in each quantization vector space is a single region. Diagnosis capability of the developed system is evaluated using a prototype system for detecting fault sensors of a reheating furnace plant. With the proposed method, abnormal sensors, such as aged deteriorated ones, which have been difficult to be detected only by checking each output of sensor independently, are possible to be specified.     

Classification and analysis of voltage stabilities in power systems

The voltage stability problem has long been studied by many researchers mainly by means of two approaches: the static approach in which voltage stability is considered as a load-flow problem; and the dynamic approach in which it is dealt with as a stability problem in dynamic systems. However, up to now, these separate approaches have not clarified sufficiently the overall aspect of the voltage problem. In fact, there are no proper criteria to determine which approach is suited to analyze voltage stability. Thus, a basic study seems to be needed under such a situation. This paper investigates the voltage stability problem from the viewpoint of mechanism causing voltage instability. Various dynamic factors which affect voltages are studied as much as possible. First, possible voltage instability patterns are classified based on singular perturbation theory. That is, four categories of instabilities are defined mathematically. Second, a method of stability assessment for each instability is presented. It is clarified that the determinant of the load-flow Jacobian is an effective index to approximately assess two types of instabilities. On the other hand, the remaining instabilities require eigenvalue analyses or direct nonlinear analyses. The validity of these results is verified through numerical simulations and eigenvalue analyses in which dynamic characteristics of generating units, loads and tap-changing transformers are taken into account.     

Application of high-field,high-resolution 13C CP/MAS n.m.r. spectroscopy to the structural analysis of Yallourn coal

High-field, high-resolution ¹³C cross-polarization and magic angle spinning nuclear magnetic resonance experiments are reported on Yallourn brown coal and on products obtained from the coal by heat treatment. The spectral resolution at 75 MHz is much improved over that previously reported for lower frequencies. A comparison of experimental and simulated spectra allowed the distribution of carbon types in Yallourn coal to be determined; the carbon aromaticity is 42%, and 30% of the carbon is present in methylene groups. The method was also used to determine structural changes during pyrolysis. At 773 K, aliphatic carbon structures are lost, but higher temperatures are necessary to decompose phenolic structures.