50Mn2V钢再加热奥氏体化温度对晶粒粗化钒化物溶解及硬度的影响

含钒钢再加热温度不同,可得出极不相同的显微结构和微合金溶解度,从而影响到钢的最终力学性能。对含0.16%钒的50Mn2V钢再加热奥氏体化温度对晶粒粗化、钒化物溶解及硬度的影响进行了探讨。得出该钢种的奥氏体粗化温度为950℃,随着加热温度的提高,晶粒粗化行为的特征分为三个区域,并且硬度随之降低。

钢中钒化物的电化学分离(第Ⅱ报)

钢中钒化物的分离和测定,目前多用化学浸溶分离法分离各钒化物后再予测定,本文就近年钢中钒化物的电化学分离法及测定法作了初步的归纳和评述。

钒化合物对作业工人肺功能的影响

随着国民经济的发展,钒及其化合物的生产与使用也日益普遍,近年来钒的毒性及对工人健康的影响也已逐渐为人们所重视。钒及其化合物在工业生产中主要以尘和烟的形式污染车间环境,经呼吸道和肺进入人体而产生一系列毒作用。为了进一步了解其对工人肺功能的影响和为职业性慢性钒中毒早期诊断提供依据,对102名接钒工人肺功能状态进行了测定,报告如下。

钒:一种具有非典型生物学意义的元素

过渡元素钒的生物学表现引起很大矛盾—从毒性到必要性。作为微量营养素,钒的重要性还有待明确地被生物学家和生物医学家所接受,尽管有毒性分析这种元素不同的生物学作用似乎很有兴趣。钒化物已被证明与人类一些疾病的发病机制有关,也与维持正常的机体功能有关。钒盐干扰诸如不同的三磷酸腺苷酶、蛋白激酶、核糖核酸酶和磷酸酶等酶系统的基本排列。钒缺乏可导致包括甲状腺、葡萄糖和脂类代谢等的一些生理学功能障碍,因为一些基因是通过这种元素或它的化合物调节的,这些基因包括肿瘤坏死因子α-、白细胞介素-8、激活蛋白-1、ras、C-raf-1、细胞分裂素活化蛋白激酶、p53、核因子-kB等。所有这些接近于形成一种认识,即钒是药理学和营养学意义上的一种元素,但这一点通过它在糖尿病中逐渐增加的治疗作用上表现出来。钒也是一种新出现的有效的抗致癌物的代表。通过对钒的一般生物化学功能的分析,全面总结了与钒生物学有关的进展。

二氧化钒镀膜玻璃参数测量与模拟

二氧化钒镀膜玻璃(下称VO2玻璃)是一种有前景的热致变色玻璃,具有相变机能,可以通过自身光学透过率的变化,调节进入建筑室内的太阳光,达到节能的目的。根据国家对建筑玻璃的测量标准,测量了VO2玻璃的可见光透射率、太阳光直接透射率、相变温度、发射率、可见光反射率等参数,计算出了VO2玻璃的遮阳系数Sc值。通过建立传热模型,模拟计算出了传热系数K值。最后将所有关于VO2玻璃的参数汇总并与目前常用节能玻璃进行性能的比较和分析,得出VO2玻璃优于部分目前常用节能玻璃,略弱于Low-E玻璃。VO2玻璃优势在其相变机能和对光污染的控制,缺点是采光性能一般,隔热性能不足,相变前后的透射率变化范围窄。对其性能不足的改进是未来的发展方向。

联麦氧钒对糖尿病大鼠心肌脂蛋白脂酶mRNA表达的影响

目的 探讨糖尿病大鼠应用联麦氧钒 (BMOV)心肌脂蛋白脂酶 m RNA表达的变化规律。方法 采用逆转录聚合酶链式反应的方法。观察 BMOV治疗前后糖尿病大鼠心肌细胞脂蛋白脂酶 m RNA水平的变化。结果 糖尿病大鼠心肌脂蛋白脂酶 m RNA是升高的 ,经 BMOV治疗后心肌细胞脂蛋白脂酶 m RNA表达可降低 ,基本恢复到正常对照水平。结论 BMOV可恢复糖尿病大鼠心肌细胞升高的脂蛋白脂酶 m RNA表达 ,调整脂代谢 ,改善心肌细胞能量物质的供给及利用。

HRB400螺纹钢中钒的强化作用研究

通过对含钒螺纹钢的性能进行研究,发现钒在细化晶粒方面效果较好.由各种强化机制对屈服强度的贡献计算结果不难发现钒能够加强析出强化的作用.文章对HRB400螺纹钢中钒的析出情况进行热力学计算,并分析了不同钒含量对析出温度的影响.

Classification of VxOy^q Clusters by △=2y＋q-5x

Vanadium oxide clusters VxOy^q（x≤8, q=0, ±1） are classified according to the oxidation index （△=2y＋q-5x） of each cluster. Density functional calculations indicate that clusters with the same oxidation index tend to have similar bonding characters, electronic structures, and reactivities. This general rule leads to the findings of new possible ground state struc- tures for V206 and V3O6＋ clusters. This successful application of the classification method on vanadium oxide clusters proves that this method is very effective in studying the bonding properties of early transition metal oxide clusters.

Relationship and effect of redox potential,jarosites and extracellular polymeric substances in bioleaching chalcopyrite by acidithiobacillus ferrooxidans

The changes of pH,redox potential,concentrations of soluble iron ions and Cu^2＋ with the time of bioleaching chalcopyrite concentrates by acidithiobacillus ferrooxidans were investigated under the different conditions of initial total-iron amount as well as mole ratio of Fe（III） to Fe（II） in the solutions containing synthetic extracellular polymeric substances （EPS）.When the solution potential is lower than 650 mV （vs SHE）,the inhibition of jarosites to bioleaching chalcopyrite is not vital as EPS produced by bacteria can retard the contamination through flocculating jarosites even if concentration of Fe（III） ions is up to 20 g/L but increases with increasing the concentration of Fe（III） ions;jarosites formed by bio-oxidized Fe3＋ ions are more easy to adhere to outside surface of EPS space on chalcopyrite;the EPS layer with jarosites acts as a weak diffusion barrier to further rapidly create a high redox potential of more than 650 mV by bio-oxidizing Fe^2＋ ions inside and outside EPS space into Fe^3＋ ions,resulting in a rapid deterioration of ion diffusion performance of the EPS layer to inhibit bioleaching chalcopyrite severely and irreversibly.

[(2,2'-bipy)_2VO_2](H_2BO_3)·3H_2O的水热合成和晶体结构

A hydrothermal reaction of NaVO3, Ce(NO3)3, H3BO3, 2,2′ bipyridine and water in a molar of 1∶2∶3∶2∶333 gives a yellow crystal [(C10H8N2)2VO2](H2BO3)·3H2O. It crystallizes in a triclinic with space group and unit cell parameters a=0.6643(1)nm, b=1.1794(2)nm, c=1.4822(3)nm, α=101.39(3)°, β=101.59(3)°, γ=97.15(3)°, Z=2, Dc=1.542g·cm-3, μ=0.508mm-1, F(000)=528, R1=0.0736, wR2=0.1998,Goof=1.071. X ray crystallographic study showed that the VN4O2 octahedron unit is distorted, in which the V1 atom is coordinated by two terminal O1 and O2 atoms, and N1, N2, N3 and N4 atoms from two 2,2′ bipy ligands. The hydrogen bonding are observed between 2,2′ bipy and adjacent terminal oxygen atom. It is noteworthy that π πstacking interaction between adjacent 2,2′ bipy groups plays an significant role in stabilization of the structure of crystal. CCDC: 194327.

Resistance to SO_2 poisoning of V_2O_5/TiO_2-PILC catalyst for the selective catalytic reduction of NO by NH_3

A titania pillared interlayered clay（Ti-PILC） supported vanadia catalyst（V2O5/TiO2-PILC） was prepared by wet impregnation for the selective catalytic reduction（SCR） of NO with ammonia. Compared to the traditional V2O5/TiO2 and V2O5-MoO3/TiO2 catalysts, the V2O5/TiO2-PILC catalyst exhibited a higher activity and better SO2 and H2O resistance in the NH3-SCR reaction. Characterization using TPD, in situ DRIFT and XPS showed that surface sulfate and/or sulfite species and ionic SO4^（2-）species were formed on the catalyst in the presence of SO2. The ionic SO4^（2-） species on the catalyst surface was one reason for deactivation of the catalyst in SCR. The formation of the ionic SO4^（2-） species was correlated with the amount of surface adsorbed oxygen species. Less adsorbed oxygen species gave less ionic SO4^（2-） species on the catalyst.

Removal of vanadate anion by calcined Mg/Al-CO_3 layered double hydroxide in aqueous solution

Mg/Al-CO3 layered double hydroxide （LDH2） with Mg（II）：Al（III） molar ratio of 2：1 was synthesized by co-precipitation method and its calcined product Mg2Al-CLDH（CLDH2） was prepared by heating Mg2Al-LDH at 773 K for 6 h. Removal of vanadate anion （ 3-4VO ） from aqueous solution on CLDH2 was studied. Batch studies were carried out to address various experimental parameters such as Mg/Al molar ratio, adsorbent dosage, initial concentration of solution, contact time and temperature. Vanadate was removed effectively at the optimized experimental conditions. The adsorption kinetics data fitted the pseudo-first-order model. Isotherms for adsorption vanadate by CLDH2 at different solution temperatures were well described using the Langmuir and Freundlich equations, and the isotherm parameters were calculated using linear regression analysis. The adsorption data fitted the langmuir model with good values of the correlation coefficient （R2〉0.999）. The negative value ofΔGΘand the positive value ofΔHΘindicate that the adsorption processes are spontaneous endothermic in nature. The mechanism of adsorption suggests that the surface adsorption is the main process.

Characterization of V_2O_5/MoO_3 composite photocatalysts prepared via electrospinning and their photodegradation activity for dimethyl phthalate

Vanadium pentoxide（V2O5）/molybdenum trioxide（MoO 3） composites with different molar ratios of vanadium（V） to molybdenum（Mo） were synthesized via a simple electrospinning technique. The photocatalytic activity of the composites were evaluated by their ability to photodegrade methylene blue and dimethyl phthalate（DMP） under visible-light irradiation. Compared with pure V2O5 and MoO 3,the V2O5/MoO 3 composites showed enhanced visible-light photocatalytic activity because of a V 3d impurity energy level and the formation of heterostructures at the interface between V2O5 and MoO 3. The optimal molar ratio of V to Mo in the V2O5/MoO 3 composites was found to be around 1/2. Furthermore,high-performance liquid chromatographic monitoring revealed that phthalic acid was the main intermediate in the photocatalytic degradation process of DMP.

Thermodynamic analysis on the direct preparation of metallic vanadium from NaVO_3 by molten salt electrolysis

A novel and environmentally friendly route to directly prepare metallic vanadium from NaV03 by molten salt electrolysis is proposed. The feasibility about the direct electro-reduction of NaV03 to metallic vanadi- um is analyzed based on the thermodynamic calculations and experimental verifications. The theoretical decomposition voltage of NaV03 to metallic vanadium is only 0.47 V at 800 ℃ and much lower than that of the alkali and alkali earth metal chloride salts. The value is slightly higher than that of low-valence vanadium oxides such as V203, V305 and VO. However, the low-valence vanadium oxides can he further electro-reduced to metallic vanadium thermodynamically. The thermodynamic analysis is verified by the experimental results. The direct preparation of metallic vanadium from NaV03 by molten salt electrolysis is feasible.

Preparation and catalytic properties of mesoporous nV ‐MCM‐41 for propane oxidative dehydrogenation in the presence of CO_2

The nV‐MCM‐41 catalysts were prepared by one‐step hydrothermal synthesis and applied to the oxidative dehydrogenation of propane（ODHP） in the presence of CO2. Several state‐of‐the‐art char‐acterization methods were performed to explore the correlation between catalytic performance and the physicochemical characterizations of the catalysts. Because moderate amounts of V species were introduced into the framework of MCM‐41, the catalyst maintained a large specific surface area, a highly ordered mesoporous structure, and highly dispersed V active sites（monomeric and dimeric V oxide species）, while the high‐vanadium‐doping catalysts caused an enhancement in the number of acidic sites and V2O5 crystallites. The ODHP reaction showed that the 6.8 V‐MCM‐41（V content 6.8 wt%） catalyst exhibits high activity and stability, and the C3H8/CO2 molar ratio（1：4） was suitable. The promoting effect of CO2 on the oxidative dehydrogenation of ODHP was demonstrated as the reaction coupling mechanism and ＂lattice oxygen＂ mechanism.

Mass Spectrometric Studies of Selective Oxidation of n-Butane over a Vanadium Phosphorus Oxide Catalyst

The selective oxidation of n-butane to maleic anhydride (MA) on a vanadium-phosphorus oxide (VPO) catalyst was studied using on-line gas-chromatography combined with mass spectrometry(GC-MS) and transient response technique. The reaction intermediates, buterie and furan, were found in the reaction effluent under near industrial feed condition (3% butane+15%O2), while dihydrofuran was detected at high butane concentration (12% butane, 5%O2). Some intermediates of MA decomposition were also identified. Detection of these intermediates shows that the vanadium phosphorus oxides are able to dehydrogenate butane to butene, and butene further to form MA. Based on these observations, a modified scheme of reaction network is proposed. The transient experiments show that butane in the gas phase may directly react with oxygen both on the surface and from the metal oxide lattice, without a proceeding adsorption step. Gas phase oxygen can be adsorbed and transformed to surface lattice oxygen but it can not participate in selective oxidation. Adsorbed oxygen leads to deep oxidation, while lattice oxygen leads to selective oxidation.

First-principles investigation of cohesive energy and electronic structure in vanadium phosphides

First-principles calculations based on the density-functional theory were employed to study the crystal structure of vanadium phosphide compounds,such as V3P,V2P,VP,VP2 and VP4. Cohesive energy of five types of vanadium phosphide compounds was calculated to assess their structural stability. The charge density distribution and densities of states of vanadium phosphides were discussed to study further their electronic structures. The results show that the structure of metal-rich compounds is considerably more stable than the phosphorus-rich compositions,and covalent bond exists between the V and P atoms of V3P,V2P,VP,VP2 and VP4.

Molecular Simulation Study on Interaction of Thiophene Sulfides with Transition Metals

The computer molecular simulation technique was applied to study the chemisorption of thiophene and tetramethylthiophene as the model sulfides on the simple oxides and complex oxides of some transition metals as the catalytic materials. The study disclosed that the thiophene sulfides could enter into chemisorption with metal oxides such as VO, ZnO, NiO and Zn-Al-spinel. This interaction could lead to thiophene molecular structure deformation to be in an activated adsorption state, which could help to promote the conversion of thiophene sulfides in the course of catalytic cracking. The VO with a valence of 2 could provide relatively strong selective adsorption sites for the conversion of thiophene sulfides to apparently transform the molecular structures and electron cloud states of such heterocyclic sulfur compounds such as thiophene and tetramethylthiophene into an activated adsorption state. The effect of this interaction was more pronounced with respect to tetramethylthiophene.

A Novel Mo-Doped Compound with Graphite-Like Structure: [H_3O]_2V_3O_8

The hydrothermal reaction of Na2MoO4 . 2H(2)O, V2O5 and en in water gave rise to a graphite-shaped vanadate [H3O](2)V3O8 1, which is doped with molybdenum. Compound 1 crystallizes in tetragonal system, space group P4bm, H6O10V2.9Mo0.1, M-r = 323.37, a = 8.904(1), c = 5.573(1)Angstrom, V = 441.8(1)Angstrom (3), Z = 2, D-c = 2.431 g.cm(-3), mu = 3.137 mm(-1), F(000) = 314, the final R = 0.0477, wR = 0.0993 for 260 observed reflections. Its two-dimensional framework is built up by corner-shared ((VO4)-O-V) tetrahedra and ((VO5)-O-IV) square pyramids with all of the terminal oxygen atoms toward the same orientation and further connected inta three-dimensional framework through hydrogen bonding between the protoned water molecules.