The test freezing temperature of C_2―C_6 dicarboxylic acid: The important indicator for ice nucleation processes

The importance of organic compounds as significant constituents of atmospheric aerosols, and cloud condensation nuclei (CCN), as well as players influencing the tropospheric oxidation and atmospheric energy budget, have been increasingly recognized. Low molecular weight dicarboxylic acids (LMW-DCAs) are significant identified portions of atmospheric condensed matter including aerosols, fog and clouds. Besides the photochemical transformation of DCA, the implication of organic matter in ice nucleation processes has been considered. In this study, we investigated the freezing temperature of pure and mixed (C2―C6) DCA solutions in ultra-pure water and tap water solution droplets using a freezing nucleus counter at different pH, and in different water ionic conditions. The mean freezing temperature of different mixture of LMW-DCA in ultra-pure and tap water solution droplets ranged from ?24.1±2.8 to ?21.3±3.9℃ and ?10.2±2.2 to ?9.5±2.2℃, respectively. The mean freezing temperature of the control (ultra-pure and tap) water droplets (?22.6±3.5℃, 11.2±2.4℃) was also measured. The results, and their implications in atmospheric chemistry and physics of the atmosphere will be discussed.     

热处理对CaO-Al2O3-SiO2系烧结微晶玻璃吸水率的影响

By means of measuring the changes of the water absorbance of glass particles in sintering with different starting size and the observation by scanning electron microscopy, the effect of heat treatment on the water absorbance of CaO-Al₂O₃-SiO₂ sintered glass-ceramics was studied in order to decrease the water absorbance of glass-ceramics. Results show that the glass-ceramics has higher water absorbance while sintering at lower temperature (900　℃). The water absorbance decreases greatly as temperature goes up. However, it increases slightly during longer stay at higher temperature (1　050～1　100　℃). The starting particle size of the glass has minor effect on the water absorbance of glass-ceramics sintering at higher temperature.     

Application of C5—C13 light hydrocarbons in depositional environment diagnosis

Based on the geological background and Gammacerane/C31H（S ＋ R） ratios, source rock depositional environments of the studied oil samples （194） from 13 oilfields were classified into three groups according to salinity： saline-lacustrine facies, fresh to brackish lacustrine facies （including limnetic facies）, and semi-saline to saline facies （including marine facies of the Tarim Basin）. C5-C13 compound groups in the crude oils were separated by GC, and about 286 compounds were qualitatively analyzed. The geochemical application of the C6- C13 compound groups and their ratios between each group with individual carbon number was investigated. Our studies show that （1） C6-C13 compound groups and their ratios in the crude oils could serve as new reliable parameters for oil-oil correlation because the C6- C13 light fractions are the major oil component, especially in light oil or condensate, in which they account for almost 90% of the whole oil; （2） the compound groups of C7 light hydrocarbons in oils derived from different depositional environments with different salinity have different characteristics; （3） C6-C13 compound groups and ratios may be affected by other factors such as maturity, but they are mainly controlled by salinity of depositional waters.     

Pervaporation of organic liquid/ water mixtures through a novel silicone copolymer membrane

Polydimethylsiloxane-ladder like phenylsilsesquioxane copolymer as a novel membrane material has good film-forming ability, high mechanical properties and low swelling capacity. The copolymer membrane displays the permselectivity of organic liquid for the pervaporation of organic liquid/water mixtures. The pervaporation of aqueous solution of ethanol through the membrane has been investigated. High separation factor can be obtained in the range of low ethanol concentration. The flux of ethanol increases and the flux of water keeps constant as the concentration of ethanol in feed increases. The membrane shows good stability of separation at room temperature to 70℃. The comparison of the pervaporation behavior of the aqueous solutions of methanol, ethanol, 2-propanol, acetone, THF reveals that the magnitude of the separation factors and the fluxes increases in the following order: methanol相似文献   

Degradation of organic matter in the sediments of Hongfeng Reservoir

In this work, the distribution of organic carbon, DNA and lipids in the sediments of Hongfeng Reservoir were described in addition to SO4^2- profile in pore water. The contents of organic carbon in the sediments range from 23.3 to 76.8 mg·g^-1, with the peak value appearing at the depth of 8 cm bellow the sediments water interface （SWI）, and tend to decrease gradually with sedimentation depth. The concentrations of SO4^2- decreased from 40.50 mg·L^-1 to 12.00 mg·L^-1 at SWI in top 4 cm sediment, and was kept at 12.0 mg·L^-1 bellow that depth. Newly produced organic carbon can be conserved as long as 14 years in the sediments. The contents of DNA were relatively high in top 9 cm surface sediments, as revealed by agarose gel images, close to those of organic carbon and sulphate reduction index （SRI）. This study shows that bacteria played an important role in organic matter degradation; SO4^2- is the primary electron acceptor under anaerobic condition in this reservoir; DNA in the lake sediments can provide important information for the study of cycling of nutrient elements in the lake.     

Reaction of Silane Alkoxide with Acid Anhydride as a Novel Synthetic Method for Organic-Inorganic Hybrid Materials

Sol-gel method is a potent method to produce new inorganic and organic-inorganic hybrid materials. The key step of this methodology is the hydrolysis of a metal alkoxide or other metal substrates such as acetylacetonates to form hydroxyl metal species, followed by their condensation to metal-oxygen-metal （M - O - M） bonds. In this process, the utilization of water, generally in excess, is essential and alcoholic solvents such as ethanol are often required to homogenize the solution when organic compounds coexist. As the common sol-gel method using water allows for limited uses of organic substrates due to their low solubility and stability in aqueous solution, modified variations of sol-gel method are reauired.     

Study on temperature characteristics of organic light-emitting diodes based on tris-（8-hydroxylquinoline）-aluminum

Both single-layer and double-layer organic light-emitting devices based on tris-（8-hydroxylquino- line）-aluminum （AIq3） as emitter are fabricated by thermal vacuum deposition. The electroluminescent characteristica of these devices at various temperatures are measured, and the temperature characteristics of device performance are studied. The effect of temperature on device current conduction regime is analyzed in detail. The results show that the current-voltage （I-V） characteristics of devices are in good agreement with the theoretical prediction of trapped charge limited current （TCLC）. In addition, both the charge carrier mobility and charge carrier concentration in the organic layer increase with the rise of temperature, which results in the monotonous increase of AIq3 device current. The current conduction mechanisms of two devices at different temperatures are identical, but the exponent m in current-voltage equation changes randomly with temperature. The device luminance increases slightly and the efficiency decreases monotonously due to the aging of AIq3 luminescent properties caused by high temperature. A tiny blue shift can be observed in the electroluminescent （EL） spectra as the temperature increases, and the reduction of device monochromaticity is caused by the intrinsic characteristics of organic semiconductor energy levels.     

The spatial distribution and sedimentary processes of organic matter in surface sediments of Nam Co, Central Tibetan Plateau

In this study,67 surface sediment samples collected from Nam Co in central Tibet were analyzed for total carbon,total organic carbon and total nitrogen,and 51 of these samples were also analyzed for n-alkanes.The origin and spatial distribution of organic matter were then investigated using these proxies,and the control factors responsible for the spatial distribution patterns and paleolimnological significance were discussed.The results indicated that the origin of organic matter in surface sediment of Nam Co is consistent with the sources of n-alkanes,which were primarily submerged plants,followed by terrestrial plants,and then aquatic algae and bacteria.The organic matter in surface sediments of the lake showed typical spatial variability.Because of the great influence of underwater topography,river inputs and water quality,the spatial distribution of organic matter is enriched from the source to the deposit center.This spatial variability of organic matter in the lake indicates that the sediments in different areas have different sensitivities to environmental changes,which is important to reconstruction of paleoenvironments and paleoclimate using lake sediment cores.     

Influence of solution concentration and temperature on the dissolution process and the internal structure of glauberite

Although transport in porous media under the influence of chemistry and temperature is a common phenomenon, the dissolution and internal structure evolution of glauberite during in-situ mining have been unique and challenging. This uniqueness indicates the complexity of mineral dissolutions, whereas the challenge represents the characterization of pore development and evolution during the dissolution processes. To investigate the microstructure development of glauberite under the influence of chemistry and temperature, experimental studies were performed with fine cuboid specimens of 4 mm×4 mm×9 mm soaked in solutions of different concentrations (fresh water, half-saturated, and saturated brine). The evolutions of internal structures were monitored through a micro computed tomography system. The statistical analysis indicated that the concentration and temperature of solutions significantly influenced the evolutions of pore size, porosity, and specific surface area of glauberite. The results showed that the increase in the rates of pore size, porosity, and specific surface area declined with time when glauberite was saturated in fresh water. The main reason for pore parameter variation is the differential concentration of solution. However, in the half-saturated and saturated solutions, the increase in rate increased with time. These observations suggest that the chloride ions contained in the saline solution could facilitate the dissolution of glauberite, whereas the existence of salt effect could contribute to the dissolution of calcium sulfate. Compared with the results at 20℃ and 65℃, the studied parameters of glauberite have dramatically decreased when the mineral was soaked in the solutions at high temperature (95℃). This function was most striking in fresh water. The dissolution of glauberite soaked in fresh water or half-saturated brine solution was conditioned by the temperature and solution concentration. However, the dissolution of glauberite was less influenced by temperature at high concentrations. These findings may feature significant implication for the effective recovery of mineral resources by in-situ solution mining method.     

Temporal-spatial dynamics of distribution patterns of microorganism relating to biological soil crusts in the Gurbantunggut Desert

Biological soil crusts serve as an important biological factor contributing to the sand fixation. This study was conducted to investigate the temporal-spatial variability of microorganism in crusts relating to locations, soil layers of sand dunes and seasons. At moss-dominated inter-dune areas, higher soil nutrient and water concentrations were likely to maintain the microbial activities. Bacteria showed the highest capabilities of settlement and growth in inter-dunes in both spring and autumn. Soil water content reached the highest value in soil crusts in the inter-dune areas, especially in spring. Variations of quantities of actinomyces and fungi basically showed the consistent trend in different locations of sand dunes. With the deepening of soil layers, vertical distribution of quantities of each microorganism group showed different characteristics because environmental factors fluctuated in both spring and autumn. Among different microorganism groups, bacteria were predominant, actinomyces the next and fungi the least in both spring and autumn in all soil layers （0-20 cm）. The proportion of bacteria and soil water content were higher in spring than those in autumn in all soil layers （0-20 cm）. No consistent trends were found in actinomyces and fungi. The results showed that the quantities of microorganisms were significantly positive correlated with organic matter content, soil water content, total N, total P, available P, available K, pH, electrical conductivity, total salt content,catalase, urease, phosphatase and alkaline phosphatase.     

Distribution characteristics of soil organic matter and total nitrogen on the Yajiageng vertical belt,Gongga Mountain around the Dadu River banks

Distribution characteristics of soil organic matter（SOM） and total nitrogen（TN） were studied in different plant communities of the Yajiageng vertical belt in Gongga Mountain around the Dadu River banks. The results show： （1） the contents of SOM and TN of the plant communities gradually decreased with the following order： subalpine coniferous forest （3 027 m）, subalpine meadow （3 873 m）, coniferous broadleaved mixed forest（2 737 m）, subalpine shrub（3 565 m） and treeline（3 564 m）. （2） With soil profile depth increasing, the contents of SOM and TN gradually decreased. For different vegetation types, the contents of SOM and TN in sub-alpine coniferous forest were higher than that of other vegetational types. （3）The ratio of the content of carbon to the content of total nitrogen （Cc/CTN）WaS 13.5-27.6, which was relatively lower than the appropriate Cc/CTN of 25-30, and indicated that the soil in favor of the organic matter decomposed and nutrients released. Cc/CTN in the soil had no correlation with sea level altitude. However, its distribution in the soil x, aried with different vegetation types. （4） Nitrogen in SOM existed mainly in the form of organic nitrogen, and Cc/CTN in the soil was not obvious correlated with SOM and TN.     

A new route of ferric ions rejection in a synthetic nickel leach solution

A new route of impurity rejection to remove ferric iron from a synthetic nickel leach solution was introduced, which simulated the chemical composition of a typical acid leach solution of nickel laterites under atmospheric pressure. The synthetic solution underwent a stepwise neutralization process, with each step adopting different pH value-temperature combinations. In a conventional nickel atmospheric leach (AL) process, the nickel loss could be as high as 10wt%, which was a longstanding issue and prevented this process from commercialization. The new impurity rejection route is the first step towards resolving this issue. The results show that, the best neutralization performance is achieved at the nickel loss of 3.4wt% in the neutralization scheme that employs ethylenediaminetetraacetic acid as a nickel stabilizer (pH: 1.3–3.5; temperature: 95–70℃)     

Kinetics of non-catalyzed hydrolysis of tannin in high temperature liquid water

High temperature liquid water （HTLW） has drawn increasing attention as an environmentally benign medium for organic chemical reactions, especially acid-/base-catalyzed reactions. Non-catalyzed hydrolyses of gallotannin and tara tannin in HTLW for the simultaneous preparation of gallic acid （GA） and pyrogallol （PY） are under investigation in our laboratory. In this study, the hydrolysis kinetics of gallotannin and tara tannin were determined. The reaction is indicated to be a typical consecutive first-order one in which GA has formed as a main intermediate and PY as the final product. Selective decomposition of tannin in HTLW was proved to be possible by adjusting reaction temperature and time. The present results provide an important basic data and reference for the green preparation of GA and PY.     

Acrylonitrile-methyl Methacrylate Copolymer Films Containing Microencapsulated n-Octadecane

Acryionitrilv-methyi mcthacrylate copolymer was synthesized in aqueous solution by Redox. The copolymer was mixed with 10 - 40 wt% of microencapsulated n-octadecane （MieroPCMs） in water. Copolymer films containing Mi- eroPCMs were cast at room temperature in N, N- imethyiformamide solution. The copolymer of acrylonitrile-methyl methacrylate and the copolymer films containing MicroPC- Ms were characterized by using Fourier Transform Infrared Spectroscopy （FTIR）, Differential Scanning Calorimetry （DSC）, Thermosravimetrlc Analyzer （TG）, X-ray Diffraction （XRD） and Scanning Electron Microscopy （SEM）, etc. The mierocapsules in the films are evenly distributed in the copolymer matrix. The heat-absorbing temperatures and heat-evolving temperatures of the films are almost the same as that of the MieroPCMs, respectively, and fluctuate in a slight range. In addition, the enthalpy efficiency of MieroPCMs rises with the contents of MicroPCMs increasing. The crystallirdty of the film increases with the contents of MicroPOMs increasing.     

Corrosion-wear behavior of nanocrystalline Fe88Si12 alloy in acid and alkaline solutions

The corrosion-wear behavior of a nanocrystalline Fe₈₈Si₁₂ alloy disc coupled with a Si₃N₄ ball was investigated in acid (pH 3) and alkaline (pH 9) aqueous solutions. The dry wear was also measured for reference. The average friction coefficient of Fe₈₈Si₁₂ alloy in the pH 9 solution was approximately 0.2, which was lower than those observed for Fe₈₈Si₁₂ alloy in the pH 3 solution and in the case of dry wear. The fluctuation of the friction coefficient of samples subjected to the pH 9 solution also showed similar characteristics. The wear rate in the pH 9 solution slightly increased with increasing applied load. The wear rate was approximately one order of magnitude less than that in the pH 3 solution and was far lower than that in the case of dry wear, especially at high applied load. The wear traces of Fe₈₈Si₁₂ alloy under different wear conditions were examined and analyzed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The results indicated that the tribo-chemical reactions that involve oxidation of the worn surface and hydrolysis of the Si₃N₄ ball in the acid solution were restricted in the pH 9 aqueous solution. Thus, water lubrication can effectively improve the wear resistance of nanocrystalline Fe₈₈Si₁₂ alloy in the pH 9 aqueous solution.     

Slime coating of kaolinite on chalcopyrite in saline water flotation

In saline water flotation, the salinity can cause a distinguishable slime coating of clay minerals on chalcopyrite particles through its effect on their electrical double layers in aqueous solutions. In this work, kaolinite was used as a representative clay mineral for studying slime coating during chalcopyrite flotation. The flotation of chalcopyrite in the presence and absence of kaolinite in tap water, seawater, and gypsum-saturated water and the stability of chalcopyrite and kaolinite particles in slurries are presented. Zeta-potential distributions and scanning electron microscopy images were used to characterize and explain the different slime coating degrees and the different flotation performances. Kaolinite particles induced slime coating on chalcopyrite surfaces and reduced chalcopyrite floatability to the greatest extent when the pH value was in the alkaline range. At 0.24wt% of kaolinite, the chalcopyrite floatability was depressed by more than 10% at alkaline pH levels in tap water. Salinity in seawater and gypsum-saturated water compressed the electrical double layers and resulted in extensive slime coating.     

The equilibrium between diagenetic calcites and dolomites and its impact on reservoir quality in the sandstone reservoir of Kela 2 gas field

Based on the equilibrium theory of chemical reactions between water and rocks,this paper establishes a thermodynamic phase relationship diagram among calcites,dolomites and water solution under the condition of diagenesis based on the thermodynamic database of related minerals and fluids and dolomite's degree of order parameters.It has been discovered that the equilibrium between calcites and dolomites in the diagenetic environment is strongly impacted by temperature and the Ca/Mg ratios in groundwater,and that the dolomite's degree of order in the diagenetic environment is a function of crystallization temperature and time,not controlled by water solution.Hereby,the authors make a further analysis of the close relationship of chemical reaction between carbonate cements and pore water in the sandstone reservoirs of Kala 2 gas field in Kuche sag.It can be seen that there are different impacts on sandstone reservoir quality among the equilibrium system of calcites,dolomites and pore water at different depths of reservoirs.     

Biomineralization process occurring in iron mud of coastal seepage area of Zhoushan Island, Zhejiang province

The biomineralization process of iron oxidizing bacteria and its influence on accumulation of metals were investigated by modern biological observation techniques （i.e., SEM and TEM） and geochemical methods, in coastal area of Zhoushan Island, Zhejiang province where a thick ancient wood layers were buried, Results show that the iron mud samples mainly contain Leptothrix-like sheaths and Gallionella-like stalks, which are known as neutrophilic iron-oxidizing bacteria. These two bacteria are present as obviously different abundance in two sampling sites, which may be regulated by the geochemistry of seepage water. The biomineralization product of iron oxidizing bacteria is ferrihydrite, a poorly ordered iron oxide, and formation of amorphous mineral is affected by the factors of bacteria, minor Si and temperature preventing any further transformation into more crystalline phases. Organic functional groups, extracellular polymers and surface charges can provide favorable nucleation sites or template for formation of iron precipitates on the bacterial surface. The mineralization process of the iron oxidizing bacteria is divided into different stages, i.e., extracellular mineralization, intracellular mineralization and the whole cell mineralization. Furthermore, due to BIOS containing the bacterial organic matter, the accumulation capacity of metals specially Fe and Co is highly increased, suggesting that BIOS exert a degree of controlling in the cycling of metal elements in seepage area.     

Effect of Al2O3 and Y2O3 on the corrosion behavior of ZrO2-benzotriazole nanostructured coatings applied on AA2024 via a sol-gel method

zirconia-based nanostructured coatings were deposited on AA2024 to improve the corrosion resistance properties. Three different nanostructured coatings, namely, zirconia-benzotriazole, zirconia-alumina-benzotriazole, and zirconia-yttria-benzotriazole, were applied on AA2024 via a sol-gel method using the dip-coating technique. Next, the coatings were annealed at 150℃ after each dipping period. The phases and morphologies of the coatings were investigated using grazing incidence X-ray diffraction (GIXRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), and atomic force microscopy (AFM). The corrosion properties were evaluated using electrochemical methods, including polarization and electrochemical impedance techniques in 3.5wt% NaCl solution. The obtained results confirm the formation of homogeneous and crack free zirconia-benzotriazole-based nanostructured coatings. The average roughness values for zirconia-benzotriazole, zirconia-alumina-benzotriazole, and zirconia-yttria-benzotriazole nanostructured coatings were 30, 8, and 6 nm, respectively. The presence of alumina as a stabilizer on zirconia coating was found to have a beneficial impact on the stability of the corrosion resistance for different immersion times. In fact, the addition of alumina resulted in the dominance of the healing behavior in competition with the corrosion process of zirconia-benzotriazole nanostructured coating.     

Climate as the dominant control on C3 and C4 plant abundance in the Loess Plateau： Organic carbon isotope evidence from the last glacial-interglacial loess-soil sequences

Abundance of C3 and C4 photosynthesis plants can be inferred relatively from stable carbon isotopic composition of organic matter in soils. The samples from five sequences of the last glacial-interglacial loess-soil in the Chinese Loess Plateau have been measured for organic carbon isotopic ratios (613Corg). The organic carbon isotope data show that relative abundance (or biomass) of C4 plants was increased ca. 40% for each sampling site from the last glacial maximum (LGM) to Holocene optimum, and increased southeastward on the Loess Plateau during both periods of LGM and Holocene. Statistic analyses on the steady maximum δ^13Corg values of Holocene soils and modern climatic data from the Loess Plateau and Inner Mongolia indicate that the C4 plant abundance increases with increasing temperature and decreasing precipitation. The C4 plant abundance is related much closer with mean April temperature and precipitation than annual. These results lead us to deduce following conclusions. First, temperature is the major factor for control on variations in C4 plant abundance in the Loess Plateau from the last glacial to interglacial. In the absence of favorable temperature condition, both of low moisture and low atmospheric CO2 concentration are insufficient to drive an expansion of the C4 plants in the plateau. Second,δ^13Corg in the loess-paleosol sequences, as a proxy of the relative abundance of C4 plants in the Loess Plateau, could not be used as an indicator of changes in the summer monsoon intensity unless the temperature had changed without great amplitude. Since all C4 plants are grasses, finally, the increase of the C4 plants supports that forest has not been dominant in the ecosystem on the Loess Plateau during Holocene although precipitation and atmospheric CO2 were largely increased relative to those during LGM.