An essential fungal growth factor derived from ergosterol: A new end product of sterol biosynthesis in fungi?

Concentrations of ergosterol as low as 1.2 mM are effective in satisfying the essential high specificity microrequirement for C5,6 unsaturated sterol in yeast. In a sterol auxotroph supplemented with saturated sterol (cholestanol), aqueous extracts of yeast provide a growth factor that eliminates the ergosterol microrequirement. The factor is easily differentiated from ergosterol by solubility, thermostability, and thin layer and liquid chromatography and is functional at levels equivalent to those of vitamins, hormones and pheromones.     

Optimal running and planning of a biomass-based energy production process

We propose mathematical programming models for solving problems arising from planning and running an energy production process based on burning biomasses. The models take into account different aspects of the problem: determination of the biomasses to produce and/or buy, transportation decisions to convey the materials to the respective plants, and plant site locations. Whereas the “running model” is linear, we propose two “planning models”, both of which are mixed-integer nonlinear programming problems. We show that a spatial branch-and-bound type algorithm applied to them is guaranteed to converge to an exact optimum in a finite number of steps.     

Abstracts

Journal of the American Oil Chemists' Society -     

The mathematical relation between the impact factor and the uncitedness factor

In a general framework, given a set of articles and their received citations (time periods of publication or citation are not important here) one can define the impact factor (IF) as the total number of received citations divided by the total number of publications (articles). The uncitedness factor (UF) is defined as the fraction of the articles that received no citations. It is intuitively clear that IF should be a decreasing function of UF. This is confirmed by the results in [van Leeuwen & Moed, 2005] but all the given examples show a typical shape, seldom seen in informetrics: a horizontal S-shape (first convex then concave). Adopting a simple model for the publication-citation relation, we prove this horizontal S-shape in this paper, showing that such a general functional relationship can be generally explained.     

Measurement of the Properties of a Plasma Column Used as a Radiating Element

This paper presents two test benches for the characterization of a plasma column used as a radiating element. In particular, the main parameters to be quantified are the efficiency of the plasma antenna, the turn-on time of the column, and the conductivity of the plasma. The first two parameters are evaluated by measuring the field radiated by the plasma antenna compared with that of an equivalent copper antenna. For the conductivity, a reflectometric technique is used, wherein the plasma column is inserted inside a waveguide. The accuracy of the method is limited by the ill-conditioned relationship between the reflection coefficient and the plasma conductivity; nevertheless, it is sufficient to subdivide the range of the conductivity values into three regions (i.e., low, medium, and high conductivities) to determine the best operating conditions of the antenna.     

Uptake and metabolism of lipoproteins from patients with diabetes mellitus type II by glomerular epithelial cells

BACKGROUND: Recent studies suggest that dyslipidaemia accelerates the progression of diabetic nephropathy, but the various pathomechanisms underlying such abnormalities are not completely delineated. METHODS: We isolated, radiolabelled, and characterized very-low-density lipoproteins (VLDL) and low-density lipoproteins (LDL) from eight diabetic patients with moderate impairment of renal function and dyslipidaemia and studied their interaction with LDL receptors in human glomerular epithelial cells. RESULTS: While diabetic VLDL showed no compositional changes, LDL particles contained a higher proportion of triglycerides at the expense of cholesterol in comparison with healthy controls. Despite differences in composition, both VLDL and LDL from patients exhibited reduced receptor affinity and cellular uptake capacity by glomerular epithelial cells. Since LDL composition was altered intracellular cholesterol homeostasis was investigated. Due to reduced cholesterol content and lower uptake capacity, diabetic LDL were less effective in suppressing intracellular sterol synthesis and in activating acylcholesterol acyltransferase than LDL from controls. Electrophoretic mobility of apoB from diabetic patients was enhanced as compared to controls, most probably due to the higher degree of glycation (17 + 1.7 versus 11 + 1%, P < 0.05) but not to oxidation (TBARS 0.5 + 0.2 versus 0.2 + 0.1 mumol/1). Oxidized LDL was not taken up in significant amounts, indicating no scavenger receptor activity in glomerular epithelial cells. CONCLUSION: The receptor-specific uptake of diabetic VLDL and LDL by glomerular epithelial cells is impaired. Compositional changes of the LDL particle and glycation of the protein moiety may contribute to altered glomerular uptake. However, glycation of the protein moiety may be superior to compositional changes. Because glomerular structures like mesangial matrix and endothelial cells are known for preferential binding of modified lipoproteins, further studies are required to elucidate their potential role in the progression of diabetic glomerulosclerosis.     

Micro–macro interactions and effect of section thickness of hpdc AZ91 Mg alloy

This work is aimed to conclude the effect of section thickness of a high pressure die cast (hpdc) Mg alloy on the tensile properties as ambiguous conclusions are presented in the literature. Tensile tests were performed on as-cast hpdc AZ91 alloy and the effect of section thickness on the tensile properties such as yield strength (YS), ultimate tensile strength (UTS), ductility and fracture strain (FS) are explained. Additionally, explanation on the microfailure mode of the material is presented to explain the influence of different microfeatures on the failure process. The average size, area fraction and clustering tendency of pores and Mg₁₇Al₁₂ (β) particles as well as average grain size are quantified and their effects on section thickness are obtained. The results confirm that the UTS, YS, ductility and FS are mainly influenced by the area fraction, size distribution and spatial arrangement of pores and phases.