法国吕兹那克滑石矿石的处理

1.概况吕兹那克滑石矿在阿里埃日省(法国),位于图卢兹南面约120公里处的比利牛斯—阿里埃日中心,座落在圣—巴泰勒米高地上。矿床海拔1500～1800米。选矿厂在矿床山脚下,位于吕兹那克的阿里埃日山谷,海     

A comparison of some muscle metabolites in stress susceptible and resistant Landrace gilts after halothane exposure or exercise stress

Sixty-six South African Landrace gilts were used in the experiments. At the age of 21 weeks, 47 of the pigs were challenged with halothane exposure. As a result 17 of the pigs died, and were classified stress susceptible (SS), whereas the 30 survivors were classified stress resistant (SR). The other 19 pigs were subjected to treadmill exercise. Four of the exercised pigs died. The pigs that survived the treadmill exercise were later exposed to halothane. The pigs that died as a result of the halothane exposure (n = 5) or the treadmill exercise (n = 4), were classified SS (n = 9) and the survivors as SR (n = 10). A biopsy of the M. semitendinosus was used for measurement of difference in muscle lactate, ATP, glucose 6-phosphate, phosphocreatine, glucose and glycogen concentrations. The results show that in all pigs exercise resulted in the higher stimulation of glycogenolysis than did halothane exposure. However, SS pigs overall showed a greater stimulation of glycogenolysis and glycolysis and general anaerobic metabolism, compared to SR pigs. Under halothane exposure, glycogenolysis and anaerobic metabolism were stimulated in the SS pigs to a much greater extent than in SR pigs, with significant differences between all the muscle metabolites determined. However, treadmill exercise, although sufficient to cause death in some pigs, resulted only in significantly higher lactate and glucose 6-phosphate concentrations. SR pigs exposed to halothane had significantly higher ATP, phosphocreatine and glycogen concentrations, but a lower glucose concentration than exercised SR pigs, indicating less severe stimulation of glycogenolysis by halothane than exercise. No significant differences were found in the determined muscle metabolites in SS pigs exposed to halothane compared to exercised SS pigs. In conclusion, these differences suggest that different mechanisms of stimulation of metabolism on exposure to halothane and exercise may exist, although both types of stress cause stimulation of glycogenolysis.     

Membrane introduction mass spectrometry: trends and applications

Recent advances in membrane introduction mass spectrometry (MIMS) are reviewed. On-line monitoring is treated by focusing on critical variables, including the nature and dimensions of the membrane, and the analyte vapor pressure, diffusivity, and solubility in the membrane barrier. Sample introduction by MIMS is applied in (i) on-line monitoring of chemical and biological reactors, (ii) analysis of volatile organic compounds in environmental matrices, including air, water and soil, and (iii) in more fundamental studies, such as measurements of thermochemical properties, reaction mechanisms, and kinetics. New semipermeable membranes are discussed, including those consisting of thin polymers, low vapor pressure liquids, and zeolites. These membranes have been used to monitor polar compounds, selectively differentiate compounds through affinity-binding, and provide isomer differentiation based on molecular size. Measurements at high spatial resolution, for example, using silicone-capped hypodermic needle inlets, are also covered, as is electrically driven sampling through microporous membranes. Other variations on the basic MIMS experiment include analyte preconcentration through cryotrapping (CT-MIMS) or trapping in the membrane (trap-and-release), as well as differential thermal release methods and reverse phase (i.e., organic solvent) MIMS. Method limitations center on semivolatile compounds and complex mixture analysis, and novel solutions are discussed. Semivolatile compounds have been monitored with thermally assisted desorption, ultrathin membranes and derivatization techniques. Taking advantage of the differences in time of membrane permeation, mixtures of structurally similar compounds have been differentiated by using sample modulation techniques and by temperature-programmed desorption from a membrane interface. Selective ionization techniques that increase instrument sensitivity towards polar compounds are also described, and comparisons are made with other direct sampling (nonchromatographic) methods that are useful in mixture analysis.     

KrF laser-induced photobleaching effects in O(2) planar laser-induced fluorescence signals: experiment and model

KrF excimer lasers are often employed as high-power excitation sources in planar laser-induced fluorescence (PLIF) imaging experiments to measure the distributions of O(2), OH, and H(2)O-all important species in combustion phenomena. However, due to the predissociative nature of these molecules, the high laser pumping rates typically required in such PLIF experiments may significantly deplete the ground-state population. The proper interpretation of the ground-state number density and/or the temperature from the fluorescence signals then requires the inclusion of photobleaching effects. We compare the results of a five-level rate-equation model incorporating photobleaching effects to the time-resolved PLIF signals from O(2) as obtained in the products of a fuel-lean CH(4) air flame. The results indicate that the fluorescence signals in a typical predissociated PLIF imaging experiment are subject to significant amounts of photobleaching. In an effort to provide a convenient way to account for photobleaching, a simple three-level model is developed. This model provides an analytic solution that describes satisfactorily the time-integrated fluorescence signal when compared with both the five-level model and the measurements. The results also indicate that at the low laser irradiances required to minimize the effects of photobleaching, the correspondingly low fluorescence signal levels make the acquisition of single-shot PLIF images a challenge to currently available camera systems.     

Discrimination of cloud and aerosol in the Stratospheric Aerosol and Gas Experiment III occultation data

The Stratospheric Aerosol and Gas Experiment (SAGE) III, scheduled for a first launch in mid-1998, will be making measurements of the extinction that is due to aerosols and gases at many wavelengths between 385 and 1550 nm. In the troposphere and wintertime polar stratosphere, extinction will also occur because of the presence of cloud along the optical path from the Sun to the satellite instrument. We describe a method for separating the effects of aerosol and cloud using the extinction at 525, 1020, and 1550 nm and present the results of simulation studies. These studies show that the new method will work well under background nonvolcanic aerosol conditions in the upper troposphere and lower stratosphere. Under conditions of severe volcanic contamination, the error rate for the separation of aerosol and cloud may rise as high as 30%.