Theoretical study of adsorption and dissociation of NH3 on the Ir{110}（1×2） surface

The adsorption and dissociation of NH3 on Ir{110}（1×2） have been investigated using the density- functional calculations at a coverage of 0.25 ML. The adsorption sites, energy, and geometries were obtained for NH3, NH2, and H adsorptions on the surface. The transition state for NH3 dissociation on Ir{110}（1×2） was also identified. It was found that NH3 is adsorbed preferentially at the ridge atop site, while NH2 and H are adsorbed at the ridge bridge site. The activation barrier of NH3 dissociation is 78.4 kJ/mol, which is very close to the NH3 adsorption energy of 90.0 kJ/mol. This indicates that the desorption and dissociation of NH3 on Ir{110}（1×2） are very competitive, which is consistent with the recent experimental results.     

Late Neoproterozoic to early Cambrian sulphur cycle-An isotopic investigation of sedimentary rocks from the Yangtze Platform

The sulphur cycle responds to changes in seawater chemistry, biological evolution and tectonic activity. We follow an isotopic approach in order to constrain the state of the ocean/atmosphere system during late Neoproterozoic and early Cambrian. For this purpose, a sedimentary succession deposited on the Yangtze Platform, South China, was analysed for its sulphur isotopic composition in different S-bearing phases. Redox changes were defined by the degree of pyritization (DOP) values in order to show variations in the oxygenation of the depositional environment. The sulphur isotopic composition of late Neoproterozoic to early Cambrian seawater sulphate ranges from +30‰ to +35‰ as evident from trace sulphate in unaltered carbonates and phosphorites. The isotopic composition for pyrite and organic sulphur varies between -16‰ and +23‰. The apparent sulphur isotopic fractionation between seawater sulphate and pyrite as well as organically bound sulphur varies between 7‰ and 50‰. This large fractionation, as well as its variability suggests a biological origin for pyrite and organically bound sulphur. The temporal evolution of different geochemical proxy signals is comparable for different successions across the Yangtze Platform.     

Surface modification of wollastonite by the mechano-activated method and its properties

Surface modification of wollastonite particles using titanate as a modification agent incorporated by simultaneous wet ultra-fine grinding in a laboratory stirred mill was investigated. The physical, physic-chemical and application properties of the modified wollastonite were measured and evaluated. The results showed that grinding intensity markedly influences the modification effect because of the mechano chemical effect. The hydrophilic surface of wollastonite was turned into a hydrophobic one after modification. The interaction between titanate and wollastonite under wet grinding circumstances was studied. It was suggested that physical adsorption and chemical adsorption of titanate coexisted on the wollastonite surface. The mechanical properties of polyethylene (PE) filled with the modified wollastonite powder were markedly improved.     

Mo isotopes in the Lower Cambrian formation of southern China and its implications on paleo-ocean environment

Over the past decade, as one of nontraditional stable isotopes, Mo isotope has developed rapidly and now become an important geochemical proxy to trace paleo-oceanic and atmospheric evolution through geological history. In this paper, Early Cambrian formations in southern China are investigated. The results indicate that δ 97/95Mo values of Early Cambrian seawater may have been larger than 1.4‰, values that are close to those of the modern ocean. It was also found that the variations in Mo isotope composition in samples from two sections （Huangjiawan and Gezhongwu in Guizhou） were closely related to changes in redox conditions during sedimentary processes. Combining our results with existing data, a preliminary model for the evolution of seawater Mo isotope composition through geological history was provided. It indicated that Mo isotopic variations were generally consistent with the evolution of atmospheric oxygen.     

Calcium isotope fractionation and its controlling factors over authigenic carbonates in the cold seeps of the northern South China Sea

In this study, we analyzed stable calcium isotope results of authigenic carbonates from two cold seep areas of the Dongsha area and the Baiyun Sag in the northern South China Sea. The stable isotopes of carbon and oxygen as well as the mineral composition of authigenic carbonates were used to investigate control calcium isotope fractionation. The δ44/40Ca ratios of the southwestern Dongsha area samples ranged from 1.21‰ to 1.52‰ and the ratio of the Baiyun Sag sample was 1.55‰ of the SRM915a isotope standard. X-ray diffraction analysis showed that the carbonate samples consisted of dolomite, calcite and aragonite, with small amounts of high-Mg calcite and siderite. The δ13C values of the carbonates of the southwestern Dongsha area varied between δ49.21‰ and δ16.86‰ of the Vienna PeeDee Belemnite (VPDB) standard and the δ18O values ranged from 2.25‰ to 3.72‰ VPDB. The δ13C value of the Baiyun Sag sample was 2.36‰ VPDB and the δ18O value was 0.44‰ VPDB. The δ13C values of the carbonates of the southwestern Dongsha area revealed there is methane seeping into this area, with a variable contribution of methane-derived carbon. The sampled carbonates covered a range of δ13C values suggesting a dominant methane carbon source for the light samples and mixtures of δ13C values for the heavier samples, with possibly an organic or seawater carbon source. The δ18O values indicated that there is enrichment in 18O, which is related to the larger oxygen isotope fractionation in dolomite compared to calcite. The results of the Baiyun Sag sample exhibited normal seawater carbon and oxygen isotopic values, indicating that this sample is not related to methane seepage but instead to precipitation from seawater. The relatively high δ44/40Ca values indicated either precipitation at comparatively high rates in pore-water regimes with high alkalinity, or precipitation from an evolved heavy fluid with high degrees of Ca consumption (Raleigh type fractionation). The dolomite samples from the Dongsha area revealed a clear correlation between the carbon and calcium isotope composition, indicating a link between the amount and/or rate of carbonate precipitation and methane contribution to the bicarbonate source. The results of the three stable isotope systems, mineralogy and petrography, show that mineral composition, the geochemical environment of authigenic carbonates and carbon source can control the calcium isotope fractionation.     

Study on the electronic structure of nickel hydroxide by quantum chemical DV-Xα calculation

The electronic structures of atom clusters NiTO12H12^2＋ and NiTO12H9^- of β-Ni（OH）2 were calculated by quantum chemical DV-Xα method. By analyzing the state densities, orbital populations, net charges and electric charge density differences of the selected clusters, it was indicated that β-Ni（OH）2was not typical ionic crystal, and the bonds between Ni and O atoms had obvious covalent characteristics. The bonds between H atom and other atoms in the crystal structure were weaker, which ensured that H atoms can easily deintercalate and intercalate into β-Ni（OH）2. The structure of β-Ni（OH）2 was not changed by moderate de-intercalation of H atoms. However, with the excessive de-intercalation of H atoms, the structure of β-Ni（OH）2 changed and the electrochemical active properties were reduced.     

Equilibrium,Kinetics and Thermodynamics of the Adsorption of Methylene Blue onto a Metal-Organic Frameworks Material,Copper Coordination Polymer with Dithiooxamide

The equilibrium, kinetics and thermodynamics of the adsorption of methylene blue （MB） from aqueous solution onto copper coordination polymer with dithiooxamide （H2dtoaCu） , one of the metal-organic frameworks （MOFs）, were investigated in a batch adsorption system as a function of initial pH, adsorbent concentration, contact time, initial dye concentration, and temperature. The Langmnir, Freundlich, and Dubinin- Radushkevich （D-R） isotherm models were used for modeling the adsorption equilibrium. It was found that Langmuir model yielded a much better fit than the Freundlich model under different temperatures. The maximum monolayer adsorption capacities of MB were 192.98, 229.86, and 297.38 mg/g at 298, 308, and 318 K, respectively. The calculated mean adsorption energy （8.26- 11.04 kJ/mol） using D-R model indicated that the adsorption process might take place by chemical adsorption mechanism. Otherwise, the kinetic studies revealed that the adsorption process could be well explained by pseudo-second-order rate kinetics and intraparticle diffusion was not the rate-limiting step. Thermodynamic studies indicated that this system was feasible, spontaneous, and endothermic process. Based on these studies, H2dtoaCu can be considered as a potential adsorbent for the removal of MB from aqueous solution.     

Membrane Insertion by Trichosanthin Using the Monolayer Method

A monolayer technique was used to investigate the interaction between the ribosome inactivating protein trichosanthin (TCS) and phospholipid membrane. The adsorption experiments show that the negatively charged 1,2-dipalmitoyl-sn-glycerol-3-phosphoglycerol (DPPG) causes obvious enrichment of TCS beneath the monolayer, indicating electrostatic attraction between TCS and the negatively charged phospholipid. When TCS was incorporated into the DPPG monolayer at low pH, it could not be completely squeezed out until the monolayer collapsed. The results suggest that the electrostatic attraction and the hydrophobic force are involved in the interaction between TCS and phospholipids at different stages. These findings may be correlated with the membrane translocation mechanism of TCS.     

Carbon and sulfur isotopic compositions of basal Datangpo Formation, northeastern Guizhou, South China: implications for depositional environment

Isotopic compositions of Mn-carbonate and organic carbon from the same individual samples and sulfur isotopic compositions of pyrites in the basal Datangpo Formation were analyzed. Highly 34S-enriched pyrites （834Spyrite =31.7-59.4‰） were precipitated in rel- atively occlusive pore water under anoxic condition in sediments, which is consistent with the observation of large and scattered pyrite framboids. The sulfidic deep ocean was not ＂oxidized＂ in the early Datangpo interglacial interval, thus the level of seawater sulfate remained low and marine δ34Ssulphate remained high. Low δ13Ccar （average -7.4‰） and abnormal relationship between δ13Ccar and fractionation （ΔCar-ors） imply that the negative δ13CCar excursion may have resulted from oxidation of part of a large organic carbon reservoir. High Δcar-org （average 25.1‰） implicates high CO2 level in the atmosphere. Small standard deviation （1.0‰） of δ13CCar values indicates the Mn-carbonate was precipitated near the water-sediment interface under dysoxic conditions rather than in occlusive pore water in sediments.     

Large selenium isotopic variations and its implication in the Yutangba Se deposit, Hubei Province, China

The selenium isotopic ratios have been measured in the Yutangba Se deposit, Hubei Province, China. The results show that the δ 82/76SeNIST values vary from -12.77‰ to 4.93‰, which is the largest Se iso- topic variation found so far in natural terrestrial samples. The sample Ytb-5 of high-selenium carbona-ceous shale has the lightest Se isotopic composition with a δ 82/76SeNIST value of -12.77‰. On the basis of variations of Se isotope in the deposit along with other geological and geochemical evidence, the "redox model" is suggested to favor the explanation of the occurrence of native Se in the deposit. The application to the Yutangba Se deposit with the discovery of large Se isotopic fractionation for natural samples indicates the potential of Se isotope as a new geochemical tracer.     

镁铝尖晶石浓悬浮体的制备

制备出固相含量为５５ｖｏｌ％,粘度为６０ｍＰａ．ｓ的镁铝尖晶石悬浮体。镁铝尖晶石的等电点约为ｐＨ６。其悬浮体的反常特性源于本身是一种复合氧化物,在ｐＨ〉６一侧面悬浮体粘度一直径大,是由于Ｍｇ＾２＋离子的屏蔽,在颗粒表面没能形成扩散双电层。     

碱化絮凝法海水脱硼预处理的研究

采用碱化絮凝法对渤海海水进行脱硼预处理,考察了单因素pH、温度、碱化剂种类、絮凝剂种类、絮凝剂用量、慢搅时间对脱硼效果的影响.结果表明,在30,℃,用碱化剂NaOH调节pH=11,加入絮凝剂聚硅酸铝铁(PAFCS)3,mg/L,聚丙烯酰胺(PAM)1,mg/L,慢搅(50,r/min)15,min,静沉3,h效果最佳,脱硼率达到89.24%,余硼含量0.48,mg/L.利用电子显微镜对浆料Mg(OH)2进行观测分析,初步探讨了碱化絮凝机理.     

Sb(Ⅲ)在高岭土表面的吸附及氧化?

研究了Sb(Ⅲ)在高岭土表面的吸附及氧化.研究结果表明Sb(Ⅲ)在高岭土表面的吸附反应为快速反应.吸附在高岭土表面的Sb(Ⅲ)易被氧化为Sb(V),一部分Sb(V)会从高岭土表面解吸进入溶液中.溶液的pH值对Sb(V)的解吸有显著的影响,且pH越高,Sb(V)越容易从高岭土表面解吸.吸附前后高岭土样品的X-射线光电子能谱(XPS)的分析表明,高岭土表面的≡Al—OH、≡Mg—OH及≡Si—OH基团参与了Sb的吸附.     

单斜镁星叶石的晶体结构再测定

通过四圆单晶衍射仪收集衍射数据，精确测定了单斜镁星叶石的晶体结构，其Ｒ因子为０．０６１，确定空间群为Ａ２，Ｔｉ的配位数为５，Ｎａ有两种结晶学位置，一种是呈八次配位位于结构层间，另一种是六次配位位于阳离子八面体层中，使单斜镁星叶石成为大阳离子层状硅酸盐。最终晶体化学式为Ｋ２ＮａＮａ（Ｆｅ，Ｍｎ）４Ｍｇ２Ｔｉ２［Ｓｉ４Ｏ１２］２（ＯＨ）４（ＯＨ，Ｆ）２。     

聚丁二酸丁二醇酯/氢氧化镁生物可降解阻燃复合材料的性能研究

熔融挤出制备了聚丁二酸丁二醇酯/氢氧化镁（PBS/Mg(OH)2）生物可降解阻燃复合材料,并对其熔体流动性、热稳定性、阻燃性能、结晶与熔融行为和力学性能进行研究. 结果表明,加入Mg(OH)2降低了PBS的熔体流动速率,延缓PBS在燃烧过程中的分解,有效提高PBS的极限氧指数和抗滴落性能. Mg(OH)2对PBS结晶具有的异相成核作用,显著提高PBS的结晶温度并改变PBS的熔融行为. 当Mg(OH)2质量分数低于40%时,Mg(OH)2提高PBS的拉伸强度、拉伸模量、弯曲强度和弯曲模量,但降低PBS的断裂伸长率和冲击强度;当Mg(OH)2质量分数大于50%时,由于PBS和Mg(OH)2的相容性较差,PBS/ Mg(OH)2复合材料在拉伸和弯曲过程中均呈现出脆性断裂现象,导致拉伸强度和弯曲强度降低.     

预还原硼铁矿熔化分离铁和硼

在实验室条件下考查了预还原硼铁矿的金属化率、熔化分离温度及时间对硼铁分离的影响,获得了考查因素与熔化分离结果参数(铁中[B],渣中(B_2O_3),(FeO)含量)间的回归方程。结果表明:预还原硼铁矿经熔化可有效地将铁和硼的氧化物分离,B_2O_3和Fe的回收率均大于95％。     

新型二维全无机的多酸化合物Na13H5[Pr(W5O18)2]2·62H2O的合成、晶体结构和荧光性质

在pH值约为6.5的水溶液中,K12[Sb2W22O74(OH)2]·27H2O,PrCl3.7H2O和Na2CO3的反应得到了一个基于[Pr(W5O18)2]9-阴离子和Na+的新型二维全无机的多酸化合物Na13H5[Pr(W5O18)2]2·62H2O.通过单晶X射线衍射、红外光谱、紫外光谱和元素分析对标题化合物的结构进行了表征,并且对标题化合物的荧光性质进行了测试.     

两种金属离子[Ca~(2+),Mg~(2+)]——螯合剂缓冲体系中自由[Ca~(2+)]的计算

在一种金属离子[Ca2+ ]及两种金属离子[Ca2+ ,Mg2+ ]螯合剂缓冲体系中总[Ca2+ ]t 的计算工作基础上,进行了含有两种金属离子[Ca2+ ,Mg2+ ]——螯合剂缓冲体系中自由钙[Ca2+ ]的计算研究.特别是利用微机给出了简单计算公式,编制了计算程序;并给出部分常用数据.只要在所需pH 值、温度、[EDTA]t 或[EGTA]t 浓度条件下,根据实验要求,由[Ca2+ ]t 和[Mg2+ ]t 就可以求出自由[Ca2+ ].     

水热条件下反应介质对Mg(OH)2晶体晶形的影响

以氯化镁和氨水为原料,在室温下制得Mg(OH)2,在不同的反应介质中对Mg(OH)2进行水热处理,制备出了超细、高纯的Mg(OH)2颗粒,利用X射线衍射仪(XRD)和扫描电子显微镜(SEM)对所制得Mg(OH)2颗粒的晶相、形貌和颗粒尺寸进行了表征.研究结果表明,水热条件下反应介质对Mg(OH)2晶体的形成有十分显著的影响,NaOH溶液、乙二胺和乙醇溶液能够显著改善Mg(OH)2晶体的晶形和分散性.初步探讨了水热条件下反应介质对Mg(OH)2晶形的影响机制.     

尿素均相沉淀法制备均分散氧化亚镍粉末(Ⅰ)——前驱体的制备研究

采用尿素均相沉淀法制得了均分散的氧化亚镍前驱体粒子．系统考察了镍离子浓度、尿素浓度、反应温度、反应时间、起始ｐＨ值及分散剂等因素对前驱体粒子形成的影响规律．结果表明,在一定条件下所得的前驱体粒子是一种化学组成为Ｎｉ２（ＣＯ３）（ＯＨ）２的晶态物质,粒子呈球形,且粒度分布均匀．