Developing the QSPR model for predicting the storage lipid/water distribution coefficient of organic compounds

The distribution of organic compounds in stored lipids affects their migration,transformation,bioaccumulation,and toxicity in organisms.The storage lipid/water distribution coefficient(log K_(lip/w))of organic chemicals,which quantitatively determines such distribution,has become a key parameter to assist their ecological security and health risk.Due to the impossibility to measure K_(lip/w)values for a huge amount of chemicals,it is necessary to develop predictive approaches.In this work,a quantitative structure-property relationship(QSPR)model for estimating log K_(lip/w)values of small organic compounds was constructed based on 305 experimental log K_(lip/w)values.Quantum chemical descriptors and n-octanol/water partitioning coefficient were employed to characterize the intermolecular interactions that dominate log K_(lip/w)values.The hydrophobic and electrostatic interactions and molecular size have been found to play important roles in governing the distribution of chemicals between lipids and aqueous phases.The regression(R2=0.959)and validation(Q2=0.960)results indicate good fitting performance and robustness of the developed model.A comparison with the predictive performance of other commercial software further proves the higher accuracy and stronger predictive ability of the developed K_(lip/w)predictive model.Thus,it can be used to predict the K_(lip/w)values of cycloalkanes,long-chain alkanes,halides(with fluorine,chlorine,and bromine as substituents),esters(without phosphate groups),alcohols(without methoxy groups),and aromatic compounds.

Study on Pressure Coefficient Distribution of the Airship Zhiyuan-1

A wind tunnel tests with different configurations,pitch and yaw angles were performed to study the wind load characteristics of the rigid model of the airship Zhiyuan-1. The rigid model was aimed to simulate a technical demonstrating stratospheric airship named Zhiyuan-1 according to the similarity principle of geometric and Reynolds number. Based on the results of wind tunnel test,the features of pressure coefficient distributions on the surface of the airship were described. It was indicated that the fins and the gondola of airship hardly have the effect on the pressure distribution on the surface of airship,but have obviously effect on the local areas near the fins and the gondola.

CLASSICAL LIMITS FOR THE COEFFICIENT OF VARIATION FOR THE NORMAL DISTRIBUTION

The exact classical limits for the coefficient of variation c for the normal distribution are derived. The hand-calculating approximated classical limits for c having high accuracy are given to meet practical engineering needs. Using Odeh and Owen's computational method and Brent's algorithm, the tables for the r-upper exact classical limits of coefficient of variation for normal distribution are calculated for the different confidence coefficient y, the sample size n=1(1)30,40,60,120, the sample coefficient of variation c=0.01(0.01)0.20. It is shown that if n<8,c<0.20, then the V -upper exact classical limits cu for c are slightly higher than the exact fiducial limits cu,F for c if. n>8, c<0.02,then cu-cu,f<5x10-6

Distribution and deposition of polycyclic aromatic hydrocarbons in precipitation in Guangzhou, South China

Polycyclic aromatic hydrocarbons （PAHs） were measured in precipitation from March to August 2005 in Guangzhou, South China. Fourteen PAHs were studied, and their total concentrations varied from 616.6 to 3486.7 ng/L in dissolved phase and from 403.8 to 3125.5 ng/L in particulate phase. The estimated deposition loading of PAHs was 3568 ug/m^2 during the monitoring period. The deposition of PAHs was a potential source for Pearl River comparing with the contents of surface water. In addition, the high concentration in precipitation here implied that PAHs pollution was a potential environmental problem in Guangzhou. Most precipitation concentrations of PAHs in March （the last month in winter in Guangzhou） were higher than in the other months （in rainy season）. PAHs inclined to be adsorbed to particulate phase with the increase of molecular weight in rainwater. Combustion of fossil fuel and biomass might be the major source of PAHs, while the direct leakage or volatilization from petroleum products might be insignificant.

Distribution and release of 2,4,5-trichlorobiphenyl in ice

The distribution of persistent organic pollutants（POPs） in ice and the release of POPs from ice during ice melting have an important influence on the eco-environment and water quality of a river. Through laboratory simulation experiments, the distribution and release of 2,4,5-trichlorobiphenyl（PCB29） in ice and the partition coefficients of PCB29 in ice water at different temperatures, concentrations, and p H levels were studied. The results showed that, at different temperatures and concentrations, the concentration of PCB29 in ice increased progressively with depth. The modes of release of different concentrations of PCB29 from ice were obtained. A large amount of PCB29 was released rapidly in the first melting period, and then the remaining PCB29 was released uniformly. The p H value dominated both the distribution and late release of PCB29 in ice. In ice water, at different temperatures, concentrations, and p H levels, the majority of PCB29 entered the water, and a lesser amount remained in the ice. Finally, laboratory experiment results were verified with field investigations. A theoretical framework is provided by this research of the behavior of POPs in ice under different environmental conditions, but a more quantitative understanding of the behavior of POPs in ice will need to be developed through further laboratory studies combined with field investigations.

Temperature field model in surface grinding: a comparative assessment

Grinding is a crucial process in machining workpieces because it plays a vital role in achieving the desired precision and surface quality.However,a significant technical challenge in grinding is the potential increase in temperature due to high specific energy,which can lead to surface thermal damage.Therefore,ensuring control over the surface integrity of workpieces during grinding becomes a critical concern.This necessitates the development of temperature field models that consider various parameters,such as workpiece materials,grinding wheels,grinding parameters,cooling methods,and media,to guide industrial production.This study thoroughly analyzes and summarizes grinding temperature field models.First,the theory of the grinding temperature field is investigated,classifying it into traditional models based on a continuous belt heat source and those based on a discrete heat source,depending on whether the heat source is uniform and continuous.Through this examination,a more accurate grinding temperature model that closely aligns with practical grinding conditions is derived.Subsequently,various grinding thermal models are summarized,including models for the heat source distribution,energy distribution proportional coefficient,and convective heat transfer coefficient.Through comprehensive research,the most widely recognized,utilized,and accurate model for each category is identified.The application of these grinding thermal models is reviewed,shedding light on the governing laws that dictate the influence of the heat source distribution,heat distribution,and convective heat transfer in the grinding arc zone on the grinding temperature field.Finally,considering the current issues in the field of grinding temperature,potential future research directions are proposed.The aim of this study is to provide theoretical guidance and technical support for predicting workpiece temperature and improving surface integrity.

Phosphate removal from wastewater by model-La(Ⅲ)zeolite adsorbents

Phosphorus is one of the primary nutrients which leads to eutrophication and accelerates aging process in enclosed water bodies. Because of the poor phosphorus selectivity of other adsorbents, the novel La（Ⅲ）-modified zeolite adsorbent （LZA） was prepared by modifying 90 nm zeolite with lanthanide to selectively remove phosphate in the presence of various omnipresent anions, such as sulfates, bicarbonates, and chlorides. Through batch and fixed bed operation, the following optimum conditions were obtained： concentration of lanthanum chloride solution 0.05 mol/L; solid/liquor ratio 1/25; pH 10; calcination temperature 550℃; time 1 h. The value of the Freundlich model constants Kf and 1/n were found to be 16.76 mg/L and 0.2209, respectively. In addition, when calculated at pH 6.0, distribution coefficient KD could be as high as 36.6. Furthermore, in the alkaline pH range, solution of 0.8 mol/L NaCl was used to regenerate the saturated LZA, which could reach the high regeneration efficiency as high as 100%. Because of the good selectivity and regenerability of LZA, it might serve as a potential way for advanced phosphate removal from the sewage containing other anions.

Study on Adsorption of Rare Earth Elements by Kaolinite

For better understanding the adsorption of rare earth elements (REEs) by clay minerals and its controlling factors, the experiments on adsorption of REEs in solutions with 1 g·L-1 kaolinite were performed at different conditions. The results are as follows: the REEs reach equilibrium in the adsorption-desorption process for 24; Langmuir′s adsorption curve is used for modeling the adsorption of REEs by kaolinite; a general trend is that the higher the contents of REEs are, the less obvious the fractionation is. Furthermore, there is significant effect of pH on the adsorption and fractionation of REEs by kaolinite, and the REEs distribution coefficient increases with increasing pH. When pH is nearly neutral, as reaches 7, heavy REEs are more adsorbed than light REEs.

Thermodynamics Behavior of Titanium for BOF Smelting Bearing Steel

When titanium element appears in bearing steel, it is very easy to create titanium nitride inclusion, which reduces the fatigue life of bearing steel. Based on the production data of bearing steel produced by BOF, it is found that the titanium takes its source in bearing steel; the factors-affecting titanium content, and the thermodynamics behavior of titanium under smelting condition were studied. The results show that the prime reasons of titanium content increment are the soluble aluminum content and the titanium oxide of slag. The comparison between the experimental data and theoretical ones shows that there is a big declination when the soluble aluminum content of steel is higher, which is caused by the nonequilibrium reaction of slag and steel. The apparent equilibrium distribution coefficient of titanium between slag and steel is Obtained by use of experimental data.

Process parameters influence on zone refining and thermodynamics analysis of 1,2-diphenylethane

Effective distribution coefficients of 9 impurities in 1,2-diphenylethane have been calculated by directional crystallization under different ambient frozen temperature.The effect of varied zone size,temperature difference between the melt and ambient frozen environment,number of zone on purity of 1,2-diphenylethane have been also investigated during the process of zone refining.The results indicate that the product purity in the intermediate purified region with varied zone size is higher 0.04%–0.2%than that with constant zone size.The product purity increases with temperature difference between the melt and ambient frozen environment.The appropriate temperature difference is adopted 50°C.The product purity in the intermediate region of sample bar with 2 molten zones is higher 0.05%–0.43%than that with 1 molten zone.In addition,the change of enthalpy and entropy between impurities and 1,2-diphenylethane have been determined.

Reaction between basaltic melt and orthopyroxene at 3.0–4.5 GPa:Implications for the evolution of ocean island basalts in the mantle

Interactions between basaltic melt and orthopyroxenite(Opx)were investigated to gain a better understanding of the consequences of the residence and transport of ocean island basalts(OIBs)within the mantle.The experiments were conducted using a DS-3600 six-anvil apparatus at 3.0–4.5 GPa and 1300–1450℃.The basaltic melt and Opx coexisted at local equilibrium at these pressures and temperatures;the initial melts dissolved Opx,which modified their chemical composition,and clinopyroxene(Cpx)precipitated with or without garnet(Grt).The trace-element contents of Grt,Cpx,and melt were measured and the mineral–melt distribution coefficients(D)of Cpx–melt and Grt–melt were calculated,which can be used to assess the distribution of trace elements between basalt and minerals in the mantle.Two types of reaction rim were found in the experimental products,Cpx,and Cpx+Grt;this result indicates that residual rocks within the mantle should be pyroxenite or garnet pyroxenite.Both rock types are found in mantle xenoliths from Hawaii,and the rare-earth-element(REE)pattern of Cpx in these mantle pyroxenites matches those of Cpx in the experimental reaction rims.Furthermore,residual melts in the experimental products plot in similar positions to Hawaiian high-SiO_(2)OIBs on major-element Harker diagrams,and their trace-element patterns show the signature of residual Grt,particularly in runs at1350℃ and 4.0–4.5 GPa.Trace-element concentrations of the experimental residual melts plot in similar positions to the Hawaiian OIBs on commonly used discrimination diagrams(Ti vs.Zr,Cr vs.Y,Cr vs.V,Zr/Y vs.Zr,and Ti/Y vs.Nb/Y).These results indicate that reaction between basaltic melt and pyroxenite might contribute to the generation of Hawaiian high-SiO2 OIBs and account for their chemical variability.

Synthesis and Adsorption Properties of Chelating Resins Containing Sulfoxide and Heterocyclic Functional Groups

Several of new chelating resins containing sulfoxide and heterocyclic functional groups （3-aminopyridine and 2-mercaptobenzothiazole） based on macroporous chloromethylated polystyrene were synthesized and characterized by elemental analysis and infrared spectra. Their adsorption capacities towards Zn^2＋, Cu^2＋, Pb^2＋, Hg^2＋ and Ag^＋ at pH 3.0 and 6.0 were investigated in detail. It was found that the adsorption capacities of the resins containing bis[（3-pyridylaminoethyl）sulfoxide or （2-benzothiazolylthioethyl）sulfoxide for the above ions were higher than that on ones containing single above-mentioned groups.

Wellbore drift flow relation suitable for full flow pattern domain and full dip range

Aiming at the simulation of multi-phase flow in the wellbore during the processes of gas kick and well killing of complex-structure wells(e.g.,directional wells,extended reach wells,etc.),a database including 3561 groups of experimental data from 32 different data sources is established.Considering the effects of fluid viscosity,pipe size,interfacial tension,fluid density,pipe inclination and other factors on multi-phase flow parameters,a new gas-liquid two-phase drift flow relation suitable for the full flow pattern and full dip range is established.The distribution coefficient and gas drift velocity models with a pipe inclination range of-90°–90°are established by means of theoretical analysis and data-driven.Compared with three existing models,the proposed models have the highest prediction accuracy and most stable performance.Using a well killing case with the backpressure method in the field,the applicability of the proposed model under the flow conditions with a pipe inclination range of-90°–80°is verified.The errors of the calculated shut in casing pressure,initial back casing pressure and casing pressure when adjusting the displacement are 2.58%,3.43%,5.35%,respectively.The calculated results of the model are in good agreement with the field backpressure data.

Oxidation of Solid Phase and Ionic Strength Effect to the Cesium Adsorption on Pumice Tuff

In-situ oxidation of solid phase was considered to investigate adsorption behavior under different geochemical parameters like pH, initial concentration and ionic strength. Pumice tuff, a potential host rock for low and intermediate radioactive wastes, has been affected by the redox zone. The characterization of the fresh and oxidized tuff was performed by X-ray diffractometer, scanning electron microscope and mercury intrusion porosimetry. In order to compare the difference of distribution coefficient (Kd) in fresh and oxidized pumice tuffs, a batch adsorption study was carried out at the range of pH (4 - 12), ionic strength (0.003, 0.1, 1.0 and 3.0 mol/dm3) and initial cesium concentration (10dž, 10LJ, 10Lj and 10lj mol/dm3). Based on experimental Kd values, ionic strength was found to be the most influential factor, whereas the effects of pH, initial Cs concentration and weathering condition of pumice tuff were negligible. The recalculated Kd values suggest that the existing surface complexation model is applicable to explain the sorption coefficients through the wide range of solution conditions.

Growth and Characterization of AIGaAsSb by MOCVD

The growth of AlGaAsSb quatornary alloys is described. In order to control the epimxial growth ofAIGaAsSb, emphasis is given on the deposition rates, growth temperatures and the relationship between growthconditions and the distribution coefficients of Al and As. Whether the growth of AlGaAsSb epilayers is con-trolled by chemical reactions or by mass diffusion depends on the growth temperatures. This argument is veri-fied by kinetic considerations. Specular surfaces of AlGaAsSb on GaSb substrates were obtained. The composi-tional nonuniformities measured by electron probe micro-analysis (EPMA) are less than 0. 6% on area of 15× 15 mm￣2. The crystallinity is measured by double crystal X-ray diffraction (DCXD). The lattice mismatchbetween AlGaAsSb epilayer and GaSb subetrato is estimated to be less than 5. 5 × 10￣(-4).

Preparation of Ga_(1-x)In_xAs_(1-y)Sb_y by MOCVD

The GalnAsSb quaternary alloys for 2～4 μm long wavelength optoelectronics have been prepared by MOCVD.The growth of buffer layers and the employment of GaSb/GaAs and GaSb/GaSb hybrid substrates are mentioned,which effectively improve the properties of GalnAsSb epilayers.In order to control the epitaxial growth of GaSb and GalnAsSb,emphasis is given on the deposition rates,growth temperatures and the relationship between growth conditions and the distribution coefficients of In and Sb.The experimen- tal solid compositions in this work are predicted by the thermodynamic calculations.Whether the growth of GalnAsSb epilayers is controlled by chemical reactions or by mass diffusions depends on growth temperatures. This argument is verified by kinetic considerations.The FWHMs of the DCXD (double crystal X-ray diffraction)spectra of GalnAsSb epilayers grown on GaSb/GaSb and GaSb/GaAs hybrid substrates are about 200～300 arcsec and 800 arcsec respectively.The unintentionally doped GalnAsSb epilayers have the mobilities of μp=100～240 cm^2/V·s at 300 K.The corresponding wavelength ofMOCVD GaInAsSb alloys is calculated from EPMA(electronic probe microanalysis)data and determined by FTIR(Fourier transformed infrared spectroscopy)measurement.

Study on the Migration Mechanism of Typical Characteristic Pollutants in Coking Enterprises

Groundwater pollution in north China is serious, which is mostly caused by complex factors. Aiming at the problems such as the unknown reasons for the differences in the migration characteristics of typical characteristic pollutants in the same medium and the unknown migration rules of complex pollutants in soil and groundwater, this paper selected a single sample and a mixed sample of typical characteristic pollutants in coking enterprises to carry out the static adsorption test. The results showed that the distribution coefficients of benzene series and aromatic hydrocarbon pollutants in soil-water were K_(d)benzene >K_(d)toluene >K_(d)ethylbenzene >K_(d)pyrene >K_(d)anthracene >K_(d)naphthene, and the distribution coefficients of ammonia nitrogen, phenols and cyanogen were K_(d)ammonia nitrogen >K_(d)phenols >K_(d)cyanogen. The overall distribution coefficient of benzene series was higher than that of PAHs, and it was easier to be adsorbed by silty loam. Different carbon and hydrogen mass and even electron distribution of typical characteristic pollutants led to differences in the migration characteristics of benzene and aromatic pollutants. The more carbon and hydrogen there were, the more even the electron distribution was, and the more difficult it was to migrate in the soil. Among the same kind of pollutants, the migration of complex pollutants was weaker than that of single pollutants. The research could provide the parameter basis for establishing the solute transport model of groundwater and the design basis for developing the related risk control and pollution prevention strategies.

Preparation of Heavily Te-doped GaSb Single Crystal

Based on comparison of the single crystal growth from several Czochralski techniques,it showed that the most advantageous method for GaSb growth seems to be LEC pulling method.Highly Te doped GaSb single crystals can be prepared on small scale with good reproducibility by using special filtering technology.Using the Te concentrations calculated from the Hall measurement,the distribution coefficient of tellurium in GaSb was estimated to be about 0.38 under our growth conditions.The etch pit density (EPD) examination in <100> GaSb showed that the profile of EPD is of W shape in growth plane and the value of average EPD is about 1.0×10 -3 cm -2 along growth direction.

Particularities in the Design of Underwater Lighting Systems

The light propagation medium determines the way in which the light is perceived by the observer’s eye.As water is a good transmitter and diffuser,when designing an underwater lighting system there are features in addition to be analyzed,which complement the common considerations for usual artificial lighting systems.The paper aims to present in detail a luminaire calculation method for 4 different types of pools with clear and transparent water(three recreational swimming pools of same size and depth,situated in interior and exterior and one small training interior swimming pool having the size of a quarter of professional competition type).There is a proposed formula for determining the number of floodlights,depending on water surface,immersion depth,average illumination on surface,uniformity,luminous flux of the light source and a water light distribution coefficient.There are highlighted specific variable parameters to be taken into account to meet the visual requirements mentioned in regulations.Depending on the application,visual comfort can be easily disturbed by the changing criteria of ambiance or surroundings,thus diminishing the visual performance.

Development of the ^(137)Cs,^(90)Sr and ^(3)H Concentrations in the Hydrosphere in the Vicinity of NPP Temelín(South Bohemia)

The paperfocuses on an analysis of the results of long-term monitoring of the concentrations of 137Cs, 90Sr and 3H in hydrosphere in the vicinity of Temelín Nuclear Power Plant (Temelín plant). The radionuclides were monitored in surface water, river sediments, aquatic flora and fish species. The main objective of the study was to analyze and integrate all of the knowledge on concentrations and behaviour of these radionuclides, which originate mainly from residual contamination, in order to assess the impacts of Temelín Nuclear Power Plant on hydrosphere in these indicators during its standard operation and possible accidents. The radionuclides were analyzed in terms of spatial and temporal variability in their concentrations and their inflows and outflows, mainly into and from Orlík Reservoir. The analysis included standard radioecological characteristics, which were applicable for assessing long-term development and behavior of radionuclides in the environment affected by their possible accidental releases on the territory of the Czech Republic or outside this territory. For all of the components of the environment, the concentrations of 137Cs and 90Sr which were used for calculation of their effective and ecological half-time, were decreasing. For 137Cs in surface water and fish, the rates of the decrease in the first and second monitoring period were different. The rate of the decrease in 90Sr concentration was invariable. The results of the monitoring showed that 86% of suspended solids and 62% of 137Cs inflowing into Orlík Reservoir accumulated in the reservoir while accumulation of 90Sr was not substantiated. Outflows of 137Cs and 90Sr activities were assessed in relation to their concentrations that were accumulated in individual basins until 1986 consequently to Chernobyl accident and tests of atmospheric nuclear weapons. The results for the whole area of the Vltava, Luznice and Otava River basins upstream from the Vltava River at Solenice showed that during the period 1986-2013 only 0.49% of 137Cs activity and 3.6% of 90Sr activity that accumulated in the basins were washed and flowed out from the area. Distribution coefficients derived from summary analysis of sediments and concentration factors for biota were calculated. Concentrations of 3H in river sites not affected by Temelín plant were slowly decreasing and their values were substantially below those from the sites affected by the plant.