Huazhong University of Science and Technology(H.U.S.T)

1.Origins and DevelopmentHuazhong University of Science andTechnology(H.U.S.T.)is one of the leadinguniversities in China directly under the StateCommission for Education.H.U.S.T.was founded by gathering thefaculty and students as well as the equip-     

Redox equilibrium U(IV) + 2Fe(CN) 63? ? U(VI) + 2Fe(CN) 64? in solutions of unsaturated heteropoly anions: Potentials of redox couples, stability of U(IV) complexes, reaction mechanism

The kinetics and equilibria of the reactions UO₂²⁺ + 2L + 2Fe(CN)₆⁴⁻ ⇄ UL₀ + 2Fe(CN)₆³⁻ in 0.1–1.0 M HCl solutions (ionic strength 1.0), where L is heteropoly anion of the composition P₂W₁₇O₆₁¹⁰⁻ or SiW₁₁O₃₉⁸⁻, were studied speelrophotometrically. Measurement of the redox potential of the ferri/rerrocyanide couple in acid solutions allowed estimation of the stability constants of the complxes U^IV(P₂W₁₇O₆₁)₂¹⁶⁻ and U^IV(SiW₁₁O₃₉)₂¹²⁻, equal in 1 M H⁺ solutions to 10^18.6 and 10^21.O, respectively. Accumulation of U^IVL₂ formed by reduction of UO₂²⁺ follows a first-order rate law, i.e., it involves the formation of UO₂⁺ which slowly reacts with L. The arising complex rapidly reacts with UO₂⁺. The loss of UL₂ occurs via formation of the complex of nonoxygenated U(V) with the heleropoly anion. Original Russian Text ? V.P. Shihv, A.B. Yusov. M.N. Sokolova, A.M. Fedoseev, 2008, published in Radiokhimiya, 2008, Vol. 50, No. 3, pp. 209–214.     

Influence of the Structure of (О-Phenylenoxymethylene)diphosphine Dioxides on Their Extraction Ability to U(VI), Th(IV), and REE(III) in Nitric Acid Media

Radiochemistry - Extraction of microquantites of U(VI), Th(IV), and REE(III) from nitric acid solutions with solutions of (o-phenyleneoxymethylene)diphosphine dioxides with phenyl and butyl...     

测量误差(error of measurement)

测量结果与被测量真值之差。测量结果是量的实验表现,通常只是对测量所得被测量值的近似或估计。真值是量的定义的完整体现,只有通过完善的测量才能求得,它反映了人们力求接近的理想、目标或客观真理,本质上是不能确定的,实际上用的是约定真值,须以测量不确定度来表征其所处的范围。所以,作为测量结果与真值之差的测量误差,也是不能确定或确切获知的,随着科学技术水平和人们认识水平的提高,可以尽量减小或对它进行控制,但不可能完全消除。从理论上和实践上研究测量误差,分析其来源、表现形式及性质,正确处理测量的数据,目的是…     

T(U)V南德意志集团大中华区获表彰

因积极参与浙江省质量技术监督局在2009年组织开展的"百家认证机构自律,万家认证企业帮扶"活动,且因认真组织开展对浙江省认证企业的自查和帮扶工作并取得了明显成效,在近日召开的浙江省认证工作会议上,T(U)V南德意志集团大中华区被评为此次活动的先进单位.     

Localization of U(VI) on nickel hydroxide from aqueous solution in the presence of complexing anions at 25°C

Sorption and coprecipitation of U(VI) from aqueous solution containing various complexing anions (CO₃^25-, SO₄²⁻, H₂EDTA²⁻) with the Ni(OH)₂ solid phase at 25°C was studied. Uranium(VI) is not noticeably sorbed on the Ni(OH)₂ solid phase from aqueous solutions containing CO₃²⁻ and SO₄²⁻. The distribution coefficients K _d are less than 1.0 ml g⁻¹ throughout the examined range of [U(VI)]: [L] ratios (L = CO₃²⁻, SO₄²⁻) at V/m ≥ 100 ml g⁻¹ and contact time of the solid and liquid phases of 60 min. In the presence and in the absence of H₂EDTA²⁻, the degree of the U(VI) sorption is essentially the same (K _d ∼90–140 ml g⁻¹ at V/m ≥ 100 ml g⁻¹). Uranium(VI) does not coprecipitate with Ni(OH)₂ from aqueous solutions containing SO₄²⁻ and H₂EDTA²⁻. The distribution coefficients K _d are less than 0.001 ml g⁻¹ at V/m ≥ 200 ml g⁻¹ and contact time of the solid and liquid phases of 60 min. In solutions containing CO₃²⁻, the U(VI) capture by the Ni(OH)₂ precipitate depends on the [CO₃²⁻]: [U(VI)] ratio. The higher the [CO₃²⁻]: [U(VI)] ratio, the more strongly U(VI) coprecipitates with Ni(OH)₂.     

Studies of Structure Evolution of Nanostructured Hf_(11)Ni_(89) Alloy

A nanostructured Hf11Ni89 ribbon sample was prepared by melt-spinning. It was found that the as-quenched sample is composed of a major HfNi5 compound nanophase and an interfacial magnetic Ni(Hf) solid solution phase. The structure evolution of the sample was studied by using X-ray difFraction (XRD), transmission electron microscopy (TEM), difFerential scanning calorimetry (DSC), resistivity and magnetothermal analysis. Upon heating, a second precipitation process of the Ni(Hf) phase prior to grain growth wa5 detected by means of both structural analysis and physical property measurements. The measurement results are discussed based on the relationship between microstructure and physical properties.     

浅谈高精度U型深槽类零件加工(二)

高精度U型深槽零件因其加工工艺性差、加工应力变形、装夹困难等原因,一直困扰着机加工企业。本文结合实例从工艺结构优化、稳定处理、装夹方法三各方面对高精度U型深槽零件的加工方案进行了有益探索。     

浅谈高精度U型深槽类零件加工(一)

高精度U型深槽零件因其加工工艺性差、加工应力变形、装夹困难等原因,一直困扰着机加工企业。本文结合实例从工艺结构优化、稳定处理、装夹方法三各方面对高精度U型深槽零件的加工方案进行了有益探索。     

Effects of Pressure on the Solidification Microstructure of Mg_(65)Cu_(25)Y_(10) Alloy

The Mg65Cu25Y10 melts were quenched at a temperature of 973 K under various pressures in the range of 2-5 GPa and ambient pressure. The microstructure of the solidified specimens has been investigated by X-ray diffraction, transmission electron microscope and electron probe microanalysis. Experimental results show that the pressure has a great influence on the solidification microstructure of the Mg65Cu25Y10. At ambient pressure, the solidification products are Mg2(Cu,Y) and a very small amount of Y2O3 inclusion. As the pressure is above 2 GPa, a new Cu2(Y,Mg) phase appears, while Y2O3 is not observed at the pressure of 3, 4 and 5 GPa. When the pressure increases from 2 GPa to 5 GPa, the grain sizes of Mg2(Cu,Y) and Cu2(Y,Mg) decrease from 125, 96 nm to 80, 7 nm, respectively. The mechanisms for the effects of the pressure on the phase evolution and microstructure during solidification process of Mg65Cu25Y10 alloy have been discussed.     

Strong Vortex Pinning in the Low–Temperature Superconducting Phase of (U1−xThx)Be13

We have found a sharp transition at T _c2 = 350 mK in the vortex creep rate of a single crystal of (U _1–x Th _x )Be ₁₃ with T _c = 523 mK (x = 0.0275). For T T _c2 , no creep of vortices is observed in a time scale of 10⁵ s, while for T _c2 < T < T _c , vortices creep at very high rates (30% of decay from a metastable configuration in the first 10⁵ s at T = 400 mK). The sharp transition occurs at the same temperature at which the second jump in the specific heat appears in these samples. Similar low levels of creep rates have been reported by us in the low–T superconducting phase of UPt ₃.¹     

Ellipsometric study of dielectric functions of Mg(1-y)Ca(y)H(x) thin films (0.03≤y≤0.17)

Mg(1-y)Ca(y)H(x) (0.03≤y≤0.17) alloy thin films covered with thin Pd were hydrogenated using 4% H(2) in Ar under atmospheric pressure at room temperature. The complex dielectric functions (ε=ε(1) + iε(2)) in the range of 0.75 to 5.0 eV of these hydrides were evaluated with spectroscopic ellipsometry. The imaginary part of the dielectric function ε(2) was composed of one Drude and three Lorentz oscillator terms whose peak positions were about 1.2 eV (L(1)), 2.8 eV (L(2)), and 5.2 eV (L(3)). The L(3) term observed in all hydrides is attributed to optical absorption of MgH(2) with E(g)=5.16 eV. The Drude term, which may be due to unhydrogenated Mg-metal, was observed in the hydrides with a low Ca composition y of less than 0.04. The L(1) term was observed in the hydrides with a Ca composition of more than 0.05, while the L(2) term was observed for more than 0.11. These L(1) and L(2) terms were estimated from a variation with hydrogenation of ellipsometric angle Ψ which is due to optical absorption of CaH(2-α) (L(1)) and MgCaH(3.72) (L(2)).     

测量结果(result of ameasurement)

由测量所得到的被测量值,即通过测量而得到的属于被测量或认作被测量的值。使用这一术语时,应表明它所指的是承值,还是未修正结果,或是已修正结果。示值是由计量器具所指示的被测量值;未修正或已修正结果是考虑到有系统误差存在,而未作修正或已作修正的测量结果。当计量器具只有单个示值时,该承值就是未修正结果;当有几个示值时,宋修正结果可由这几个承值的算术平均值求得。系统误差中的已定或表面系统误差,其大小与符号均为已知,从而可以修正。修正后剩余的是只能估计其界限的未定系统误差,常归纳到测量不确定度中去。测量结果…     

Surface Layer of Ni_(68)P_(18)Cr_(14) Amorphous Alloy

In Ni_(68)P_(18)Cr_(14) amorphous alloy, the dominant component elements Ni and P were in lower contentin the surface layer, while Cr was enriched. There was a P enrichment region just below the surfaceoxide layer, which was supposed to enhance the surface segregation of Cr. Nickel was less oxidizedthan Cr.     

量值(value of a quantity)

由数值和计量单位的乘积所表示的量的大小。量值是量的表示形式。一般说来，任何可测的量都是由数值和计量单位两部分组成，如5．Mm或534cm，15kg或15000g等。没有计董单位的纯数不能表示量，就计量学而言，毫无意义，数值大不等于量大，反之，数值小也不等于星小。表示量值时要采用法定计量单位，所选用的单位大小也要适中，使数值的位数不宜太多。量值(value of a quantity)     

Work Functions of Pd_(83.5)Si_(16.5)and Cu_(70)Ti_(30)Glassy Alloys

The work functions before and aftercrystallization of two glassy alloys,Pd_(83.5)Si_(16.5) andCu_(70)Ti_(30) have been measured by means of the con-tact potential difference method in the secondaryelectron field at room temperature under 10~(-5) Pavacuum.The results show that the work functionsof both glassy alloys are higher than those of thecorresponding crystalline alloys.     

Intercalation of n-alkylamines into α-tin(IV) bis(hydrogenphosphate)

The intercalation reaction of n-alkylamines from methyl- to hexadecylamine into -tin(IV) bis(hydrogenphosphate) has been investigated. The reaction was conducted by mixing the phosphate and solutions of the amines dissolved in water or benzene. The amine/ phosphate molar ratios in the reaction mixtures were 0.43, 0.85, 1.71 and 3.41. The nitrogen/phosphorus atomic ratio in the intercalation compound was not changed by the amine/phosphate molar ratio. The interlayer distances of the intercalates obtained in the reaction mixtures with molar ratios of 3.41 and 1.71 increased with an increase in the number of carbon atoms in the alkyl chain of the amine. The slope of the straight line obtained in plot of interlayer distance versus number of carbon atoms in the alkyl chain of the amine indicates that the amine molecules form a double layer in the interlayer space of the phosphate and are inclined at an approximate angle of 67.7° to the phosphate layer. The interlayer distances of the intercalates of butyl- to nonylamines obtained at the molar ratio of 0.85 are smaller than those of the corresponding compounds from the molar ratios of 3.41 and 1.71, while those of decyl- to hexadecylamine intercalates lie on the previously discussed line. This behaviour is interpreted by assuming kink formation in the short alkyl chains between the phosphate layers.     

ZnO/g-C_(3)N_(4)复合光催化剂的制备及光催化还原U(Ⅵ)EI北大核心CSCD

以ZnO和三聚氰胺为原料,采用热聚合法制备ZnO/g-C_(3)N_(4)复合型光催化剂,并将其用于光催化还原U(Ⅵ)。通过SEM,XRD,XPS,PL,UV-Vis测试手段对样品的表面形貌、晶格结构、元素组成、光催化性能进行分析。结果表明:ZnO的掺杂降低光生电子与空穴的复合率,扩大材料对可见光的响应范围,使复合材料具有更高的光催化活性。在pH=5、投加量为0.5 g/L时,经过暗反应30 min和光反应30 min,对U(Ⅵ)的最高去除率可达97%。U(Ⅵ)可被还原为U(Ⅳ),光生电子e-是实现将U(Ⅵ)还原为U(Ⅳ)的主要因素。