珠江口表层沉积物nirS型反硝化微生物多样性

本研究以nirS基因为分子标记,将PCR、克隆文库构建与测序和典范对应分析相结合,对珠江口表层沉积物nirS型反硝化微生物的群落多样性进行了研究。3个站位共获得180个nirS基因克隆子,隶属于62个OTUs,氨基酸序列的相似性在50%—100%之间。各站位OTU分布格局差异明显,范围在19—33之间,表现出高度的多样性。系统进化分析表明,62个OTUs形成了5个类群,分别与河口、海洋沉积物、海岸养殖排放废水、富营养化海湾及海水养殖沉积物等的反硝化微生物聚类在一起,表明珠江口作为海淡水交汇区具有独特的反硝化微生物群落分布格局,同时也指示了珠江口氮污染及富营养化程度。典范对应分析结果表明,盐度、氮相关营养盐水平(PON/TN、NH4-N、NO-N和NO-N)可能是影响其分布格局的重要因素。

离子束抛光仪的维护保养

离子束抛光仪可以快速切割试样,无应力应变层,无外来污染物,暴露试样内部的真实结构信息。Leica EM TIC 3X型三离子束抛光仪是由3个离子源同时加工,具有离子束宽度大、面积大、非聚焦型离子源能量分散、对试样损伤小等优点。对该仪器的日常维护保养内容进行了总结归纳,并列举了若干常见问题及其解决方法,研究结果可为仪器使用者提供参考。

油藏数值模拟技术在复杂断块油藏开发后期的应用

油藏数值模拟技术对于查明已开发油田的油藏潜力、措施制定、调整方案综合设计等有着不可替代的作用。针对河流相多油层复杂断块油藏开发后期的特点,通过油藏数值模拟技术研究确立了港东开发区复杂断块油藏剩余油分布特征,应用该技术进行了油井提液方案及影响因素研究。结果表明,当含水率相同、提液倍数相同、原油粘度不同时,随着原油粘度增大,提液效果变差;当原油粘度一定、含水率一定时,不考虑其他影响因素,累增产油量随提液倍数的增大而增大;当原油粘度一定、提液倍数相同时,含水率越低提液效果越好。正韵律提液累计增产油量高于反韵律提液累计增产油量;压力系数为低、中、高组合的油藏模型提液效果要好于压力系数为高、中、低组合的提液效果。应用该技术还进行了注采井网调整方法研究,从4种井网部署模式累计产油量计算结果看,主体带注水、边部采油模式好于边部注水、边部采油注采模式。该研究对于确定复杂断块油藏开发后期油藏潜力、确定合理的油井提液方案和合理部署注采井网具有一定的指导意义。

Influence of sodium silicate on manganese electrodeposition in sulfate solution

The influences of sodium silicate on manganese electrodeposition in sulfate solution were investigated. Manganese electrodeposition experiments indicate that a certain amount of sodium silicate can improve cathode current efficiency and initial pH 7.0?8.0 is the optimized pH for high cathode current efficiency. The analyses of scanning electron microscopy (SEM) and X-ray diffraction (XRD) indicate the compact morphology and nanocrystalline structure of electrodeposits. X-ray photoelectron spectrometry (XPS) analysis shows that the elements of Mn, Si and O exist in the deposit. The solution chemistry calculations of sulfate electrolyte and sodium silicate solution indicate that species of Mn2+, MnSO4, Mn(SO4)2?2 , Mn2+, MnSiO3, Mn(NH3)2+, SiO32?and HSiO3? are the main active species during the process of manganese electrodeposition. The reaction trend between Mn2+ and Si-containing ions is confirmed by the thermodynamic analysis. In addition, polarization curve tests confirm that sodium silicate can increase the overpotential of hydrogen evolution reaction, and then indirectly improve the cathode current efficiency.

Electrodeposition of Ir on platinum in NaCl-KCl molten salt

The reduction mechanism of Ir in the NaCl-KCl-IrCl3 molten salt was investigated by cyclic voltammetry and chronopotentiometry, and Ir film was deposited effectively on platinum in potentiostatic mode. The morphology and constitution of Ir film were examined by scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS） and X-ray diffraction （XRD）. It is found that the reduction mechanism of Ir（III） is a three-electron step and electro reaction is a reversible diffusion controlled process; the diffusion coefficients of Ir（III） at 1083, 1113, 1143 and 1183 K are 1.56×10-4, 2.23×10-4, 2.77×10-4 and 4.40×10-4 cm2/s, respectively, while the activation energy of the electrode reaction is 102.95 kJ/mol. The compacted Ir film reveals that the applied potential greatly affects the deposition of Ir, the thickness of Ir film deposited at the potential of reduction peak is the highest, the temperature of the molten salt also exerts an influence on deposition, the film formed at a lower temperature is thinner, but more micropores would occur on film when the temperature went too high.

Fabrication of TiN/cBN and TiC/diamond coated particles by titanium deposition process

Cubic boron nitride particles coated by titanium nitride (TiN/cBN) as well as diamond particles coated by titanium carbide (TiC/diamond) were prepared by Ti molten salt deposition followed by heat-treatment process. cBN or diamond particles were mixed separately with Ti powders and molten salts (KCl, NaCl and K2TiF6). The mixture was heated at 900 °C under argon atmosphere. The produced particles were heat-treated under hydrogen at 1000 °C. The morphologies and chemical compositions of the produced particles were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and focused ion beam (FIB). The results show that the cBN and the diamond particles are coated by nano-sized Ti layers. By heat-treatment of the Ti/cBN and TiC/diamond coated particles under hydrogen atmosphere, the deposited Ti layers were interacted by the in-situ transformation reaction with the surfaces of cBN and diamond particles and converted to titanium compounds (TiN and TiC), respectively.

Electrochemical synthesis of catalytic materials for energy catalysis

Electrocatalysis is a process dealing with electrochemical reactions in the interconversion of chemical energy and electrical energy.Precise synthesis of catalytically active nanostructures is one of the key challenges that hinder the practical application of many important energy‐related electrocatalytic reactions.Compared with conventional wet‐chemical,solid‐state and vapor deposition synthesis,electrochemical synthesis is a simple,fast,cost‐effective and precisely controllable method for the preparation of highly efficient catalytic materials.In this review,we summarize recent progress in the electrochemical synthesis of catalytic materials such as single atoms,spherical and shaped nanoparticles,nanosheets,nanowires,core‐shell nanostructures,layered nanomaterials,dendritic nanostructures,hierarchically porous nanostructures as well as composite nanostructures.Fundamental aspects of electrochemical synthesis and several main electrochemical synthesis methods are discussed.Structure‐performance correlations between electrochemically synthesized catalysts and their unique electrocatalytic properties are exemplified using selected examples.We offer the reader with a basic guide to the synthesis of highly efficient catalysts using electrochemical methods,and we propose some research challenges and future opportunities in this field.

Interfacial reactions between Sn-2.5Ag-2.0Ni solder and electroless Ni(P) deposited on SiC_p/Al composites

A novel Sn-2.5Ag-2.0Ni alloy was used for soldering SiCp/Al composites substrate deposited with electroless Ni(5%P) (mass fraction)and Ni(10%P)(mass fraction)layers.It is observed that variation of P contents in the electroless Ni(P)layer results in different types of microstructures of SnAgNi/Ni(P)solder joint.The morphology of Ni3Sn4 intermetallic compounds(IMCs)formed between the solder and Ni(10%P)layer is observed to be needle-like and this shape provides high speed diffusion channels for Ni to diffuse into solder that culminates in high growth rate of Ni3Sn4.The diffusion of Ni into solder furthermore results in the formation of Kirkendall voids at the interface of Ni(P)layer and SiCp/Al composites substrate.It is observed that solder reliability is degraded by the formation of Ni2SnP,P rich Ni layer and Kirkendall voids.The compact Ni3Sn4 IMC layer in Ni(5%P)solder joint prevents Ni element from diffusing into solder,resulting in a low growth rate of Ni3Sn4 layer.Meanwhile,the formation of Ni2SnP that significantly affects the reliability of solder joints is suppressed by the low P content Ni(5%P)layer.Thus,shear strength of Ni(5%P) solder joint is concluded to be higher than that of Ni(10%P)solder joint.Growth of Ni3Sn4 IMC layer and formation of crack are accounted to be the major sources of the failure of Ni(5%P)solder joint.

In situ TiB2/Cu composites fabricated by spray deposition using solid-liquid and liquid-liquid reactions

In situ TiB2/Cu composites were fabricated by both solid-liquid(S-L)and liquid-liquid(L-L)reactive spray deposition in combination with cold rolling and annealing.The microstructure and properties of the fabricated TiB2/Cu composites were investigated.The results show that the reactive mode and rolling treatment are the main factors affecting the microstructure and properties of the TiB2/Cu composite.The in situ reaction in the L-L reaction can be carried out more completely.By controlling the rolling and annealing process,the relative density and the properties of the as-deposited composites are optimized.The comprehensive performance of the deformed TiB2/Cu composite prepared by L-L reactive spray deposition(401 MPa and 83.5%IACS)is better than that by S-L reactive spray deposition(520 MPa and 20.2%IACS).

Spray deposition of FeCrNiMn and high carbon steel coatings by thermite reaction

A novel surface cladding technique was developed to prepare the FeCrNiMn alloy and high carbon steel cladding layers,and the microhardness,bonding strength,abrasion wear and corrosion resistance were investigated.The microstructures of the cladding layers were analyzed by using X-ray diffraction(XRD),scanning electron microscopy(SEM),and energy dispersive spectrometry(EDS).The results show that the bonding strength between the substrate and the two cladding layers were(432.6±21)and(438.3±12)MPa,respectively.Vickers hardness values of the two cladding layers were HV418.5and HV329.6,respectively.The corrosion current densities of the two coatings were2.926×10–6and6.858×10–6A/cm2after electrochemical corrosion test in3.5%NaCl solution,and the wear rate were1.78×10–7and1.46×10–6mm3/mN after sliding wear test,respectively.This indicates that a well metallurgical bonding between the coating and the substrate was achieved,the abrasion wear and corrosion resistance of both coatings had been greatly improved compared with the substrate.The novel cladding technology is promising for preparing wear-and-corrosion resistant coatings.

Denitrification and Nitrate Reduction to Ammoniumin Taihu Lake and Yellow Sea Inter-Tidal MarineSediments

Denitrification and nitrate reduction to ammonium in Taihu Lake and Yellow Sea inter-tidal marinesediments were studied. The sediment samples were made into slurry containing 150 g dry matter per liter.Various amounts of glucose and 5 mmol L-1 of potassium nitrate were added in order to achieve differentratios of glucose-C to nitrate-N. Acetylene inhibition technique was applied to measure denitrification in theslumes. All samples were incubated anaerobically under argon atmosphere. Data showed that Taihu Lakesediment produced more N2O than marine sediment. Denitrification potential was higher in Taihu Lakesediment than in marne one. Glucose added increased denitrification activity but not the denitrification po-tential of the sediments. Dissimilatory nitrate reduction to ammonium seemed to occur in marine sediment,but not in freshwater one. When the marine sediment was treated with 25 mmol L-1 glucose, its denitrification poteatial, as indicated by maximum N2O production by acetylene blockage, was lower than that treatedwith no or 2.5 mmol L-l glucose. Acetylene was suspected to have inhibitory effect on dissimilatory nitratereduction to ammonium.

Chemical Vapor Deposition Mechanism of Copper Films on Silicon Substrates

A versatile metal-organic chemical vapor deposition （MOCVD） system was designed and constructed. Copper films were deposited on silicon （100） substrates by chemical vapor deposition （CVD） using Cu（hfac）2 as a precursor. The growth of Cu nucleus on silicon substrates by H2 reduction of Cu（hfac）2 was studied by atomic force microscopy and scanning electron microscopy. The growth mode of Cu nucleus is initially Volmer-Weber mode （island）, and then transforms to Stranski-Rastanov mode （layer-by-layer plus island）. The mechanism of Cu nucleation on silicon （100） substrates was further investigated by X-ray photoelectron spectroscopy. From Cu2p, O1s, F1s, Si2p patterns, the observed C=O, OH and CF3/CF2 should belong to Cu（hfac） formed by the thermal dissociation of Cu（hfac）2. H2 reacts with hfac on the surface, producing OH. With its accumulation, OH reacts with hfac, forming HO-hfac, and desorbs, meanwhile, the copper oxide is reduced, and thus the redox reaction between Cu（hafc）2 and H2 occurs.

Geoacoustic inversion for sediments in the South China Sea based on a hybrid inversion scheme

We performed a long range acoustic propagation experiment in the South China Sea(SCS) in November 2004.The environment of the experiment was with an isothermal sound speed profile,where influence of water volume fluctuation was small,meaning that bottom parameters can be well estimated from acoustic signals.We inverted the acoustic parameters of sediment by using a hybrid inversion scheme that combines the matched field processing inversion with Hamilton sediment empirical relationship and transmission loss data.The numerical results show excellent agreement with the experiment data,indicating validity of the inverted parameters.

Numerical simulation of chemical vapor deposition reaction in polysilicon reduction furnace

Three-dimensional model of chemical vapor deposition reaction in polysilicon reduction furnace was established by considering mass, momentum and energy transfer simultaneously. Then, CFD software was used to simulate the flow, heat transfer and chemical reaction process in reduction furnace and to analyze the change law of deposition characteristic along with the H_2 mole fraction, silicon rod height and silicon rod diameter. The results show that with the increase of H_2 mole fraction, silicon growth rate increases firstly and then decreases. On the contrary, SiHCl_3 conversion rate and unit energy consumption decrease firstly and then increase. Silicon production rate increases constantly. The optimal H_2 mole fraction is 0.8-0.85. With the growth of silicon rod height, Si HCl3 conversion rate, silicon production rate and silicon growth rate increase, while unit energy consumption decreases. In terms of chemical reaction, the higher the silicon rod is, the better the performance is. In the view of the top-heavy situation, the actual silicon rod height is limited to be below 3 m. With the increase of silicon rod diameter, silicon growth rate decreases firstly and then increases. Besides, SiHCl_3 conversion rate and silicon production rate increase, while unit energy consumption first decreases sharply, then becomes steady. In practice, the bigger silicon rod diameter is more suitable. The optimal silicon rod diameter must be over 120 mm.

Paleo-fluvial sedimentation on the outer shelf of the East China Sea during the last glacial maximum

Evidence from lithology, foraminiferal assemblages, and high-resolution X-ray fluorescence scanning data of core SFK-1 indicates tidally influenced paleo-fluvial sedimentation during the last glacial maximum (LGM) on the outer shelf of the East China Sea. The paleo-fluvial deposits consist of river channel facies and estuarine incised-valley-filling facies. Different reflections on the seismic profile across core SFK-1 suggest that the river channels shifted and overlapped. River channel deposition formed early in the LGM when sea level fell and the estuary extended to the outer shelf. Channel sediments are yellowish- brown in color and rich in foraminifera and shell fragments owing to the strong tidal influence. Following the LGM, the paleo-river mouth retreated and regressive deposition of estuarine and incised-valley-filling facies with an erosion base occurred. The river channel facies and estuarine incised-valley-filling facies have clearly different sedimentary characteristics and provenances. The depositional environment of the paleo-river system on the wide shelf was reconstructed from the foraminiferal assemblages, CaCO3 content and Ca/Ti ratio. The main results of this study provide further substantial constraints on the recognition of late Quaternary stratigraphy and land-sea interactions on the ECS shelf.

EFFECTS OF SIMVASTAIN COMBINED WITH OMEGA-3 FATTY ACIDS ON HIGH SENSITIVE C-REACTIVE PROTEIN, LIPIDEMIA, ANDFIBRINOLYSIS IN PATIENTS WITH MIXED DYSLIPIDEMIA

Objective To evaluate the effects of simvastatin combined with omega-3 fatty acids on high sensitive C-reactive protein(HsCRP), lipidemia, and fibrinolysis in coronary heart disease (CHD) and CHD risk equivalent patients with mixed dyslipi-demia. Methods A randomized, double-blind placebo controlled and parallel group trial was conducted. Patients with CHD and CHD risk equivalents with mixed dyslipidemia were treated with 10 or 20 mg simvastatin for 6-12 weeks. Following with the treatment of patients whose low-density lipoprotein cholesterol (LDL-ch) reaching goal level (< 100 mg/dL) or close to the goal (< 130 mg/dL), while triglyceride (TG) ≥200 mg/dL and < 500 mg/dL, was combined with omega-3 fatty acids (3 g/d) or a placebo for 2 months. The effects of the treatment on HsCRP, total cholesterol (TC), LDL-ch, high-density lipoprotein cholesterol (HDL-ch), TG, lipoprotein (a) [LP (a)], apolipoprotein A1 (apoA1), apolipoprotein B (apoB), plasminogen activator inhibitor-1 (PAI-1), and tissue plasminogen activator (tPA) were investigated. Forty patients finished the study with each group consisting of twenty patients. Results (1) There were significant reductions of HsCRP, TG, TC, and TC/HDL-ch, which decreased by 2.16 ±2.77 mg/L (38.5%), 94.0 ±65.4 mg/dL (31.1%), 13.3 ±22.3 mg/dL (6.3%), 0.78 ±1.60 respectively in the omega-3 fatty acids group (P< 0.01, < 0.001, < 0.05, < 0.05) compared to the baseline. HsCRP and triglyceride reduction were more significant in omega-3 fatty acids group compared to the placebo group (P=0.021 and 0.011 respectively). (2) In the omega-3 fatty acids group, the values and percentage of TG reduction had a significantly positive relation with HsCRP reduction (r=0.51 and 0.45, P=0.021 and 0.047 respectively). Conclusion In CHD and CHD risk equivalent patients with mixed dyslipidemia, dyslipidemia’s therapeutic effect using simvastatin and omega-3 fatty acids may result from not only the combination of lipid adjustment, but also enhancement of their own nonlipid influences.

Impact of redox-stratification on the diversity and distribution of bacterial communities in sandy reef sediments in a microcosm

Relationships between microbial communities and geochemical environments are important in marine microbial ecology and biogeochemistry. Although biogeochemical redox stratification has been well documented in marine sediments, its impact on microbial communities remains largely unknown. In this study, we applied denaturing gradient gel electrophoresis （DGGE） and clone library construction to investigate the diversity and stratification of bacterial communities in redox-stratified sandy reef sediments in a microcosm. A total of 88 Operational Taxonomic Units （OTU） were identified from 16S rRNA clone libraries constructed from sandy reef sediments in a laboratory microcosm. They were members of nine phyla and three candidate divisions, including Proteobacteria （Alphas, Beta-, Gamma-, Delta-, and Epsilonproteobacteria）, Aetinobacteria, Acidobacteria, Bacteroidetes, Chloroflexi, Cyanobacteria, Firmicutes, Verrucomicrobia, Spirochaetes, and the candidate divisions WS3, SO31 and AO19. The vast majority of these phylotypes are related to clone sequences from other marine sediments, but OTUs of Epsilonproteobacteria and WS3 are reported for the first time from permeable marine sediments. Several other OTUs are potential new bacterial phylotypes because of their low similarity with reference sequences. Results from the 16S rRNA, gene clone sequence analyses suggested that bacterial communities exhibit clear stratification across large redox gradients in these sediments, with the highest diversity found in the anoxic layer （15-25 mm） and the least diversity in the suboxic layer （3-5 mm）. Analysis of the nosZ, and amoA gene libraries also indicated the stratification of denitrifiers and nitrifiers, with their highest diversity being in the anoxic and oxic sediment layers, respectively. These results indicated that redox-stratification can affect the distribution of bacterial communities in sandy reef sediments.

Highly effective electrochemical water oxidation by copper oxide film generated in situ from Cu(Ⅱ) tricine complex

Developing highly efficient and stable water oxidation catalysts based on abundant metallic elements is a challenge that must be met to fulfill the promise of water splitting for clean energy production.In this work,we developed an oxygen evolution reaction catalyst consisting of a nanostructured film electrodeposited from a phosphate buffer solution(0.2mol/L,pH=12.0)containing Cu‐tricine complex.A Tafel plot showed that the required overpotential for a current densityof1.0mA/cm2was only395mV and the Tafel slope was46.7mV/decade.In addition,the Cu‐tricine film maintained a stable current density of7.5mA/cm2for the oxygen evolution reaction in phosphate buffer solution for10h,and a Faradaic efficiency of99%was obtained.

Kinetics of Zn cathodic deposition in alkaline zincate solution

Kinetic parameters of the electrode reactions were measured by investigating steady-state current-potential behaviors. The Tafel slopes of cathodic and anodic processes are -0.113 8 V and -0.041 18 V, the anodic and cathodic apparent transfer coefficients are 0.519 3 and 1.435 2, respectively, and the stoichiometric number of rate-deterrnining step is 1. The theoretical kinetics equation of electrode reaction was deduced, from which the dynamic parameters can be calculated as follows： the cathodic and anodic Tafel slopes are -0.118 V and -0.039 4 V, respectively, consisting with the experimental values, Finally, the correctness of the mechanism was further demonstrated using apparent transfer coefficient according to the electrochemical dynamic equation of multi-electron reaction.

Preparation of Ni nanoparticles plating by electrodeposition using reverse microemulsion as template

Ni nanoparticles plating was prepared in reverse microemulsion. The deposition was carried out through the Brownian motion of water pools in the reverse microemulsion and the adsorption of water pools on the electrode surface. Effects of electrolytic parameters on the size of Ni particles were studied. The performances of hydrogen evolution and hydrogen storage of the Ni nanoparticles plating electrode were also investigated. The results indicate that the size of Ni nanoparticles decreases with the increase of Ni2+ concentration and the decrease of current density. The electrochemical activity of Ni nanoparticles plating electrode is much higher than that of bulk Ni electrode.