临床厌氧菌感染的病原学探讨

临床厌氧菌感染的病原学探讨解放军第一六九医院陆秀荣，李本连，唐银，何学贤，黄金元厌氧菌感染为正常菌群所引起的内源性感染，日益受到重视（１）。我们采集疑有厌氧菌感染者的标本４２１份进行培养，以探讨其病原学诊断问题。１材料与方法１．１培养基改良ＧＡＭ羊血...

Responses of Filtration Rate of Freshwater Mussel Anodonta woodiana to Ambient Ammonia Concentration

By using one static water system,the filtration rates of one kind of freshwater mussel Anodonta woodiana with different body weight(accounted by dry weight of soft tissue)were studied under semi-field conditions.During the experiments,the water temperature and the suspended particulate matters concentration were kept relative invariable and there were four ambient ammonia concentration levels.The ambient water ammonia concentration was obtained by the excretion of the freshwater mussel and the accession of ...

Method of oxygen-enriched two-stage underground coal gasification

Two-stage underground coal gasification was studied to improve the caloric value of the syngas and to extend gas production times.A model test using the oxygen-enriched two-stage coal gasification method was carried out.The composition of the gas produced,the time ratio of the two stages,and the role of the temperature field were analysed.The results show that oxygen-enriched two-stage gasification shortens the time of the first stage and prolongs the time of the second stage.Feed oxygen concentrations of 30%, 35%,40%,45%.60%,or 80%gave time ratios（first stage to second stage） of 1：0.12,1：0.21.1：0.51,1：0.64, 1：0.90.and 1：4.0 respectively.Cooling rates of the temperature field after steam injection decreased with time from about 19.1-27.4℃/min to 2.3-6.8℃/min.But this rate increased with increasing oxygen concentrations in the first stage.The caloric value of the syngas improves with increased oxygen concentration in the first stage.Injection of 80%oxygen-enriched air gave gas with the highest caloric value and also gave the longest production time.The caloric value of the gas obtained from the oxygenenriched two-stage gasification method lies in the range from 5.31 MJ/Nm^3 to 10.54 MJ/Nm^3.

Serum magnesium concentration in children with functional constipation treated with magnesium oxide

AIM:To determine whether hypermagnesemia recently reported in adult patients possibly develops in children with functional constipation taking daily magnesium oxide.METHODS:We enrolled 120 patients (57 male and 63 female) aged 1-14 years old (median:4.7 years) with functional constipation from 13 hospitals and two private clinics.All patients fulfilled the Rome Ⅲ criteria for functional constipation and were treated with daily oral magnesium oxide for at least 1 mo.The median treatment dose was 600 (500-800) mg/d.Patients were assessed by an interview and laboratory examination to determine possible hypermagnesemia.Serum magnesium concentration was also measured in sex-and agematched control subjects (n=38).RESULTS:In the constipation group,serum magnesium concentration [2.4 (2.3-2.5) mg/dL,median and interquartile range] was significantly greater than that of the control group [2.2 (2.0-2.2) mg/dL] (P < 0.001).The highest value was 3.2 mg/dL.Renal magnesium clearance was significantly increased in the constipation group.Serum magnesium concentration in the constipation group decreased significantly with age (P < 0.01).There was no significant correlation between the serum level of magnesium and the duration of treatment with magnesium oxide or the daily dose.None of the patients had side effects associated with hypermagnesemia.CONCLUSION:Serum magnesium concentration increased significantly,but not critically,after daily treatment with magnesium oxide in constipated children with normal renal function.

A contrast study on different gasifying agents of underground coal gasification at Huating Coal Mine

To optimize the technological parameter of underground coal gasification （UCG）, the experimental results of air gasification, air-steam gasification, oxygen-enrichment steam gasification, pure oxygen steam gasification and two-stage gasification were studied contrastively based on field trial at the Huating UCG project. The results indicate that the average low heat value of gas from air experiment is the lowest （4.1 MJ/Nm3） and the water gas from two-stage gasification experiment is the highest （10.72 MJ/Nm3）. The gas productivity of air gasification is the highest and the pure oxygen steam gasification is the lowest. The gasification efficiency of air gasification, air-steam gasification, oxygen-enriched steam gasification, pure oxygen steam gasification and two-stage gasification is listed in ascending order, ranging from 69.88% to 84.81%. Described a contract study on results of a field test using steam and various levels of oxygen enrichment of 21%, 32%, 42% and 100%. The results show that, with the increasing of O2 content in gasifying agents, the gas caloricity rises, and the optimal O2 concentration range to increase the gas caloricity is 30%-40%. Meanwhile, the consumption of O2 and steam increase, and the air consumption and steam decomposition efficiency fall.

Optimization and mechanism of surfactant accelerating leaching test

To solve the problem of slow leaching speed of copper,surfactant was added into lixivium as leaching agent in the experiment.Based on physical chemistry and seepage flow mechanics,the leaching mechanics of surfactant was analyzed.The solution surface tension and surfactant adsorbing on the surface of ore have a significant impact on the surface wetting effect.With leaching rate for response,the study screened out three main factors by Plackett-Burman design method:the sulfuric acid concentration,surfactant concentration and temperature.Among these three factors,the surfactant concentration is the most important contributor to leaching rate.After obtaining the experiment center by the steepest ascent experiment,a continuous variable surface model was built by response surface methodology.By solving quadratic polynomial equation,optimal conditions for leaching were finally obtained as follows:the sulfuric acid concentration was 60 g/L,the surfactant concentration was 0.00914 mol/L,and the temperature was 45 °C.The leaching rate was 66.81% in the optimized leaching conditions,which was close to the predicted value,showing that regression result was good.

Experiment and simulation of diffusion of micron-particle in porous ceramic vessel

The general behavior of micron-particles in the inner domain of porous ceramic vessel was simulated by computational fluid dynamics software in terms of sampling experimental data.The results show that there is an optimum porosity of 0.32 to get a higher efficiency and lower pressure drop during filtration.According to the results of simulation and experiment,it is evident that lower inlet velocity can maintain lower pressure drop and obtain higher collection efficiency and inlet concentration also has a crucial influence on the collection efficiency.The collection efficiency of equipment increases significantly with the increase of inlet concentration when the inlet concentration is less than 6.3 g/m3,but it gradually tends to be stable in the range of 97.3%-99.7%when the inlet concentration is over this concentration.

Prediction of Distillation Column Performance by Computational Mass Transfer Method

A computational mass transfer model is proposed for predicting the concentration profile and Murphree efficiency of sieve tray distillation column. The proposed model is based on using modified c＇2 -εc＇ two equations formulation for closing the differential turbulent mass transfer equation with improvement by considering the vapor injected from the sieve hole to be three dimensional. The predicted concentration distributions by using proposed model were checked by experimental work conducted on a sieve tray simulator of 1.2 meters in diameter for desorbing the dissolved oxygen in the feed water by blowing air. The model predictions were confirmed by the experimental measurement. The validation of the proposed model was further tested by comparing the simulated result with the performance of an industrial scale sieve tray distillation column reported by Kunesh et al. for the stripping of toluene from its water solution. The predicted outlet concentration of each tray and the Murphree tray efficiencies under different operating conditions were in agreement with the published data. The simulated turbulent mass transfer diffusivity on each tray was within the range of the experimental result in the same sieve column reported by Cai et al. In addition, the prediction of the influence of sieve tray structure on the tray efficiency by using the proposed model was demonstrated.

Effect of CO_2 Elevation on Root Growth and Its Relationship with Indole Acetic Acid and Ethylene in Tomato Seedlings

A hydroponic experiment was carried out to study the effect of elevated carbon dioxide(CO2) on root growth of tomato seedlings.Compared with the control(350 μL L-1),CO2 enrichment(800 μL L-1) significantly increased the dry matter of both shoot and root,the ratio of root to shoot,total root length,root surface area,root diameter,root volume,and root tip numbers,which are important for forming a strong root system.The elevated CO2 treatment also significantly improved root hair development and elongation,thus enhancing nutrient uptake.Increased indole acetic acid concentration in plant tissues and ethylene release in the elevated CO2 treatment might have resulted in root growth enhancement and root hair development and elongation.

Removal of Pesticides from Water Using Anaerobic-Aerobic Biological Treatment

The biodegradability of wastewater containing priority pollutant pesticideVydine or triadimenol（C14H18CLN3O2） in different bio-reactor configurations was investigated.Two laboratory scale biological reactors were employed：one reactor under aerobic condition and the other under anaerobic condition.The aerobic reactor was operated at an ambient temperature（22±2） °C,while the anaerobic reactor was run in the lower mesophilic range（30±2） °C.The effect of pesticide concentration,hydraulic retention time（HRT） ,and co-substrate on the treatment process was explored,using glucose as a supplemental carbon substrate.More than 96%pesticide was removed after an acclimation period of approximately 172 d（aerobic） and 230 d（anaerobic） .The aerobic reactor achieved complete Vydine utilization at feed concentrations up to 25 mg·L^-1 .On the other hand,the anaerobic reactor was able to degrade 25 mg·L^-1 of Vydine.Moreover,glucose was consumed first throughout the experiment in a sequential utilization pattern.The combination of anaerobic and aerobic biological processes yielded higher biomass concentration and lower retention time than individual units.The biomass in the combined reactors was first acclimated with the corresponding pesticide.Then,the target pesticide,at a concentration of 25 mg·L^-1,was sequentially treated in a semi batch mode in the reactors.HRT studies showed that 24 h HRT of aerobic and 12 h HRT of anaerobic were the optimum combination for the treatment of simulated wastewater containing Vydine,which produced Vydine effluent at concentration below 0.1 mg·L^-1 .The optimum ratio of substrate（Vydine） to co-substrate（glucose） was 1︰100.

Effect of solution conditions on depression of chlorite using CMC as depressant

The effect of solution conditions on the depression of chlorite using CMC (carboxymethyl cellulose) as depressant was studied through flotation tests and adsorption measurements. Flotation and adsorption tests were first studied as a function of initial solution conditions. The results show that electrostatic repulsion between CMC molecules and chlorite surface hinders the approach of the CMC molecules to the chlorite surface and CMC adsorbs to a great extent at high ionic concentration (10-4 mol/L ions as opposed to 0 mol/L ions) or low pH (3 as opposed to 9). The enhanced adsorption density is attributed to the decreased electrostatic repulsion between CMC and mineral surface. The solution condition that yielded the lowest initial adsorbed amount (0 mol/L ions, pH 9) was used as a reference to investigate the response of the adsorbed CMC layer to a switch in solution conditions after adsorption. The two kinds of solution switches (reducing the solution pH or increasing ionic concentration) result in an increased depression effect of CMC on chlorite flotation, as a result of conformational change of CMC pre-adsorbed layer. The change in the flotation recovery of the CMC-coated chlorite following the solution switches is reversible.

Experimental Study on Refinery Gas Desulfurization Using Gas-Liquid Membrane Contactor

Gas-liquid contactors equipped with polytetrafluoroethylene （PTFE） or polypropylene （PP） hydrophobic membranes were applied for removal of sulfur dioxide from refinery gas. Pure water, NaOH solution and MDEA were adopted as the absorbents. The performance of the two kinds of membranes for separation of SO2 was evaluated in terms of the concentration of absorbent solution, the concentration of SO2, and the feed flow rate. The efficiency for removal of SO2 increased with an increasing absorbent concentration. Upon increasing the concentration of SO2 and the feed flow rate, the desulfurization efficiency was decreased.

Experimental study of enhancing coalbed methane recovery by carbon dioxide injection driving methane

In order to enhance coalbed methane recovery, taking a self-developed largecalesimulation system for the platform, a modeling experiment of driving CH_4 by CO_2 gasinjection was studied.The results of experiment indicates that there is a significant lag effectof adsorption and desorption on gas, the gas pressure is changed more rapidly in theprocess of carbon dioxide adsorption of coal than methane adsorption of coal; After theinjection of carbon dioxide, compare with methane single desorption.In an early stage,speed and amount of methane single desorption are greater than the speed and amountof displacement desorption, the speed and amount of displacement desorption becamegreater.In the process of replacement, CH_4 concentration constantly declined, while CO_2concentration constantly rose.In the process of CO_2 gas injection, the temperature of coalhave been significantly increased, it is more beneficial to make CH_4 gas molecules becomefree from the adsorbed state when temperature is increased.Under the pressurestep-down at the same rate, using the method of CO_2 driving CH_4, compared with themethod of conventional pressure step-down, the desorption rate of CH_4 in coal can beraised about 2.13 times, at the same time, a lot of greenhouse gas CO_2 will also be buriedin the ground, there is a very significant environmental benefit.

Effect of water on extractive desulfurization of fuel oils using ionic liquids： A COSMO-RS and experimental study

When evaluating ionic liquids （ILs） for extractive desulfurization （EDS） of fuel oils, the inevitable presence of water in the system may have a significant and in many cases strongly negative effect. However, few studies have considered this particular issue and a promoted water effect on EDS is scarcely reported. In this work, COSMO-RS was firstly employed to calculate the capacity and selectivity for EDS of various IL/H20 mixtures, which cover different IL characters and a wide water concentration range. Experiments were then conducted with a representative IL [C4MIM]IH2P04], whose stable and even promoted extraction performance with a small amount of water was suggested by COSMO-RS. Through analyses of the desulfurization ratio, the cross- solubility and the water content in the desulfurized fuel, the promoted effect of water within a certain range （〈 10 wt%） was experimentally demonstrated. Moreover, such effect of water was explained combining the viscosity, the solvent-solute interactions and the COSMO-RS based analysis.

Effects of different conditions on Pb^(2+) adsorption from soil by irrigation of sewage in South China

Pb2＋ adsorption onto a soil by irrigation of sewage in the Pearl River Delta of South China was examined as a function of the reaction time, solution pH, initial lead concentration, organic matter （humic acid） and competitive ions （Cu2＋）. The adsorption of Pb2＋ onto the soil was investigated on batch equilibrium adsorption experiments. Results show that the Pb2＋ adsorption on the soil is relatively rapid in the first 30 min and reaches equilibrium at 2 h, and the kinetics of the adsorption process on the soil is well characterized by the pseudo-second order reaction rate. Langmuir, Freundlich and Temkin isothermal models are fit for the adsorption of Pb2＋ onto the soil, and the maximum amount of Pb2＋ adsorption （Qm） is 7.47 mg/g. The amount of Pb2＋ adsorption increases with increasing the pH at the range of 1.2-4.5 and reaches a plateau at the range of 4.5-12. The presence of humic acid in soil decreases the adsorption of Pb2＋ onto the soil at solution pH of 8 since the negatively charged humic acid with Pb2＋ is difficult to be adsorbed on the negatively charged soil surface. The adsorption of Pb2＋ onto the soil also decreases in the presence of Cu2＋ due to file competition adsorption between Pb2＋ and Cu2＋.

Secretion of melatonin and 6-sulfatoxymelatonin urinary excretion in functional dyspepsia

To evaluate blood concentration of melatonin and urinary excretion of its metabolite, 6-sulfatoxymelatonin （6-OHMS）, in functional dyspepsia （FD）. METHODS： Ninety individuals were enrolled in the study： 30 in each study group： patients with postprandial distress syndrome （PDS）, epigastric pain syndrome （EPS）, and controls. Blood samples were drawn at 02：00 and 09：00 h and 24-h urine collection was performed. Serum melatonin and urinary 6-OHMS concentrations were measured by enzyme-linked immunosorbent assay. RESULTS： Serum melatonin concentration at night and in the morning was significantly （P 〈 0.001） higher inPDS patients [at 02：00 h-93.3 pg/mL, quartile range （QR）： 79.8-116.2; at 09.00 h-14.3 pg/mL, QR： 7.06-19.0] than in EPS （57.2 pg/mL, QR： 42.6-73.1, 8.1 pg/mL, QR： 4.2-9.3） and control patients （57.7 pg/mL, QR： 51.2-62.5; 8.1 pg/mL, QR： 5.4-10.3）. A similar relationship was observed for urinary 6-OHMS excretion. Patients with severe PDS symptoms had a higher melatonin concentration than these with moderate syndromes, whereas patients with severe EPS had a lower urinary 6-OHMS excretion than patients with moderate symptoms.CONCLUSION： Evaluation of melatonin serum concentrations and 24-h urinary 6-OHMS excretion are useful methods for differential diagnosis of various clinical forms of FD.

Experimental Study of Dissolved Oxygen Transport by Regular Waves Through a Perforated Breakwater

The perforated breakwater is an environmentally friendly coastal structure, and dissolved oxygen concentration levels are an important index to denote water quality. In this paper, oxygen transport experiments with regular waves through a vertical perforated breakwater were conducted. The oxygen scavenger method was used to reduce the dissolved oxygen concentration of inner water body with the chemicals Na2SO3 and COC12. The dissolved oxygen concentration and wave parameters of 36 experimental scenarios were measured with different perforated arrangements and wave conditions. It was found that the oxygen transfer coefficient through wave surface, K1α1, is much lower than the oxygen transport coefficient through the perforated breakwater, K2α2. If the effect of K1α1 is not considered, the dissolved oxygen concentration computation for inner water body will not be greatly affected. Considering the effect of a permeable area ratio a, relative location parameter of perforations 6 and wave period T, the aforementioned data of 30 experimental scenarios, the dimensional analysis and the least squares method were used to derive an equation of K2α2 （K2α2=0.0042aσ56δ2T1）. It was validated with 6 other experimental scenarios data, which indicates an approximate agreement. Therefore, this equation can be used to compute the DO concentration caused by the water transport through perforated breakwater.

CFD Modeling of Turbidity Current Deposition

Simulation of the flow and deposition from a laboratory turbidity current, in which dense mixtures of sediment move down a narrow, sloping channel and flow into a large tank. SSIIM CFD software is used to model 3-D flow and deposition. SSIIM predicts the height of the accumulated mound to within 25% of experimental values, and the volume of the mound to 20%-50%, depending on the concentration of sediment and slope of the channel. The SSIIM predictions were consistently lower than experimental values. In simulations with initial sediment volumetric concentrations greater than 14%, SSIIM dumped some of the sediment load at the entry gate into the channel, which was not the case with the experimental runs. This is likely due to the fact that the fall velocity of sediment particles in SSIIM does not vary with sediment concentration. Further simulations of deposition from turbidity currents should be attempted when more complete experimental results are available, but it appears for now that SSIIM can be used to give approximate estimates of turbidity current deposition.

Experimental study and numerical simulation of the sludge concentration in a sedimentation tank

Sedimentation tanks and clarifiers play a significant role in an active sludge system, and the efficiency of the whole system is closely related with the design and operation of the sedimentation tanks. This paper focuses on the sludge concentration in each cross-section of the sedimentation tank. We measured the sludge concentration to explore its distribution inside the tank, carried in-situ tests to research the fluid pattern and real operational rules of the sedimentation tank. We also used the computational fluid dynamics (CFD) software, PHOENICS 3.5, to simulate the solid-liquid two-phase fluid inside the tank and describe the sludge concentration distribution. The numerical results indicate obviously a sludge-water interface and a compression interface inside the sedimentation tank, a stratified sedimentary region with uniform concentration and a compression region with high concentration at the bottom of the tank. Although the simulated concentrations deviated slightly from those of in-situ tests, they were still acceptable for identifying the sludge interfaces and fluid pattern inside a sedimentation tank, which are important parameters for optimizing the tank size and improving the settling efficiency.

A study on Cr(Ⅵ)reduction from aqueous solutions by bauxite

The reduction of Cr（Ⅵ） in aqueous solution by using bauxite ore was investigated.Experimental results for Cr（Ⅵ）reduction in aqueous solution depending on some factors such as time,sulfuric acid amount,bauxite dosage,initial Cr（Ⅵ）concentration,formic acid concentration,daylight and temperature were presented.The obtained results show that sulfuric acid amount,bauxite dosage and initial Cr（Ⅵ） concentration of solution are most effective parameters on the reduction process.Also,it has been found that the 60 g/L of bauxite dosage is sufficient to reduce up to 100% of Cr（Ⅵ） from acidic solution under the condition of low initial Cr（Ⅵ） mass concentrations such as 10 mg/L.The reduction reaction is completed within 30 min at 25 ℃ under the experimental conditions：bauxite dosage of 60 g/L,amount of sulfuric acid 40-60 stoichiometric and initial mass concentration of Cr（Ⅵ）,10 mg/L.It was determined that reduction percentage is decreasing with increasing initial Cr（Ⅵ） concentration.The chemical oxygen demand of bauxite ore was found to be 26 mg COD/g.