Dietary fat alters biliary lipid secretion in the hamster

Dietary fat has been found to alter the incidence of cholesterol gallstones in hamsters: butterfat intensifies while safflower oil reduces lithiasis. We now report how dietary fat affects bile flow and biliary lipid secretion in this model. Male hamsters were fed one of three experimental diets: a control diet (containing 0.3% cholesterol); control diet +4.0% butterfat; or control diet +4.0% safflower oil. After three weeks, bile samples were collected via an external biliary fistula. The endogenous bile acid pool was depleted for 120 min followed by increasing rates of taurocholate infusion for 160 min. Basal secretion of biliary lipids was measured during the bile acid depletion period. Basal bile flow and bile acid output were not significantly different in the three groups. Dietary butterfat increased basal cholesterol output compared to the control diet (0.037 vs. 0.025 μmol/min·kg, respectively); safflower oil did not change cholesterol output (0.027 μmol/min·kg). Hamsters fed butterfat or safflower oil secreted more phospholipid (0.171 and 0.178 μmol/min·kg, respectively) than controls (0.131 μmol/min·kg). The cholesterol/phospholipid output ratio of the butterfat group was higher than the safflower oil group (0.220 vs. 0.153, respectively). Effects of dietary fat on several relationships between bile flow and biliary lipid secretion were analyzed by linear regression using the data for the entire bile collection period (bile acid depletion and taurocholate infusion). Butterfat and safflower oil did not change either bile acid dependent or bile acid independent bile flow. Hamsters fed butterfat had a higher linkage coefficient (slope) of cholesterol vs. bile acid output than the safflower oil group (0.023 vs. 0.009, respectively). The linkage coefficient of phospholipid vs. bile acid output of the butterfat group was higher than the controls (0.278 vs. 0.185, respectively). In summary, butterfat induced a high cholesterol and phospholipid secretion with a high cholesterol/phospholipid output ratio; safflower oil induced a high phospholipid secretion with a low cholesterol/phospholipid output ratio. Butterfat and safflower oil have different effects on biliary lipid secretion. These differences in biliary lipid secretion may explain, in part, how butterfat and safflower oil differ in affecting gallstone formation in hamsters.     

Characterization of micro-flocs of NOM coagulated by PACl, alum and polysilicate-iron in terms of molecular weight and floc size.

Micro-flocs of NOM coagulated by polyaluminium chloride (PACl), alum and polysilicate-iron (PSI) were characterized by flocs size, HPSEC-based molecular weight and the captured content of coagulants-based aluminium and iron. Changes in floc composition with respect to the mass ratios of captured NOM to Al and Fe were examined. Lowering water pH to optimum levels was found to be capable of removing small NOM constituents that are generally difficult to be precipitated at neutral pH levels. For PACl and PSI, the distribution of micro flocs (0.1-5.0 microm) reached steady stage after rapid mixing for 30 seconds, with NOM being found existent within the non-coagulated fraction (d<0.1 microm) and the coagulated fraction with floc sizes above 5.0 microm (d >5.0 microm). For alum, however, the existence of NOM inside intermediate floc fractions of d = 0.1-1.0 microm, 1.0-3.0microm and 3.0-5.0 microm was confirmed.     

A crystal structure consideration of an orthorhombic BaEu2Mn2O7 phase

The electron microscopic study was performed on an orthorhombic BaEu₂Mn₂O₇ phase. The electron diffraction patterns of this phase showed some series of superlattice spots such as h 0 0 (h = odd), h k 0 (h,k = odd) and h0l (h,l = odd) that were forbidden for face centered cell. A possible space group P112₁/m (11) was derived from the reflection conditions. And then, a superstructure of this phase was discussed in this paper.     

Preparation of pure vaterite by simple mechanical mixing of two aqueous salt solutions

Vaterite-type calcium carbonate particles have some unique properties such as high hydrophilicity, large surface areas, and hierarchical structures consisting of primary vaterite particles in comparison with calcite- or aragonite-type polymorphs. In this paper, preparation conditions of vaterite by mixing treatment of two salt solutions, CaCl₂ and K₂CO₃, were studied in terms of the presence of surfactant, agitation method of the solutions and other conditions. A double-cylinder-type homogenizer or ultrasonic homogenizer was used for agitation of the solutions. When suitable mixing conditions were adopted, pure vaterite was obtained as fine powders quantitatively by mixing the two salt solutions at room temperature without any surfactant using any types of homogenizers. When a polyoxyethylene sorbitan monofatty acid ester was present as a surfactant in the mixing solutions, pure vaterite but different morphologies or particle sizes were obtained, depending on the chemical structure of the surfactant used. The obtained results revealed that homogeneous, high-shear and constant agitation of the mixing solutions around 1 M salt concentration was necessary to prepare pure vaterite under the conditions used in this study.     

Tribology-related space mechanism anomalies and the newly constructed high-vacuum mechanism test facilities in NASDA

In the past many functional anomalies of mechanisms and mechanical components have been experienced on board spacecraft and their launch vehicles. Such anomalies sometimes lead to the total loss of the spacecraft. Among the major causes of mechanical anomalies, vacuum tribology-related malfunctions have received central attention in Japan due to the continued occurrence of spacecraft failures. Phenomena such as the increase of frictional forces between moving parts and the binding of metallic parts in high-vacuum environments are sometimes very difficult to examine in full scale on the ground, and only limited prototype verification is conducted in orbit. Responding to the strong need for the improvement of space mechanism and tribology research work, integrated multiple high-vacuum mechanism test facilities were constructed in NASDA Tsukuba Space Center in 1998. These facilities are intended to provide fundamental data on the performance of mechanical components and materials in high vacuum for validating space mechanism designs. One of the facilities also makes possible the examination of combined environmental factors, such as electron beams, ultraviolet radiation, atomic oxygen and temperature, for mechanisms and materials. This paper introduces typical features of the space-based mechanism functional anomalies and describes the new test facilities.     

Evaluation of liver function by co-administration methodology using 13C-labelled benzoic acid and hippuric acid coupled with nuclear magnetic resonance spectroscopy

The amount of hippuric acid synthesized and excreted in the urine after benzoic acid loading (hippuric acid test) is a useful index of liver function. However, the hippuric acid test gives erroneous results in the event of failure of renal excretory function. A new stable isotope co-administration methodology using nuclear magnetic resonance (NMR) spectroscopy has been developed to overcome this defect. [7-(13)C]Benzoic acid and [glycine carbonyl-13C]hippuric acid ([gly-13C]hippuric acid), each 0.4-0.6 mmol kg(-1) were simultaneously administered intravenously as probes to normal or liver-injured rats and the urine was analysed by 100 MHz 13C NMR spectroscopy. Consequently, urinary excretion of [7-(13)C]hippuric acid formed from [7-(13)C]benzoic acid and [gly-13C]hippuric acid was successfully traced with very simple and convenient procedures. The urinary excretion of [7-(13)C]hippuric acid indicated the combined functions of hippuric acid synthesis and renal excretion, whereas that of [gly-13C]hippuric acid was indicative of renal excretion of hippuric acid only. The heights of resonances for C7 of [7-(13)C]hippuric acid and the glycine carbonyl carbon of [gly-13C]hippuric acid were used to calculate the concentrations of labelled hippuric acids. [7-(13)C]Hippuric acid was excreted more slowly than [gly-13C]hippuric acid by both normal and liver-injured rats. The liver-injured rats excreted the labelled hippuric acids more slowly than the normal rats. The kinetic parameters were computed for the individual rats on the basis of Michaelis-Menten elimination for benzoic acid and first-order elimination for hippuric acid. The maximum rates of metabolism (Vmax) (4.8-5.8 micromol min(-1) kg(-1)) and the renal elimination rate constants of hippuric acid (Kre) (0.010-0.021 min(-1)) in the liver-injured rats were lower than those (Vmax 6.7-11.8 micromol min(-1) kg(-1); Kre 0.026-0.045 min(-1)) in the normal rats. These results have demonstrated that liver function can be evaluated from the Vmax value even though the renal function of hippuric acid excretion (Kre) is impaired. Thus the co-administration methodology is feasible and can remove the defect of the previous hippuric acid test. These results could form the basis for a more convenient and reliable hippuric acid test in man.     

Power-generating performance of alkali metal thermoelectric converter

The alkali metal thermoelectric converter (AMTEC) utilizing the sodium ion conducting β-alumina is a device to convert heat energy to electric energy directly. It is characterized by high conversion efficiencies, high power densities, no moving parts and low maintenance requirements. Because of these merits, AMTEC is one of the most promising candidates for aerospace power systems, remote power stations and dispersed small-scale power stations. In this paper, the experimental results of the series-connected cells and the theoretical considerations about internal resistances have been reported. For the single cell, the open voltage of 1.37 V and the maximum power of 7.89 W and maximum power density of 0.40 W/cm² at the sodium temperature of 1077 K have been obtained. For the two series-connected cells, the open voltage of 2.60 V and the maximum power of 12.3 W at the sodium temperature of 1016 K have been obtained. This power was about 90 percent of the sum power of two cells. This power decrease is due to the resistance of the current-collecting busbar. It is necessary to optimize the current-collecting busbar considering the electrical resistance and heat conductance.