甲基丙烯酸异冰片酯与甲基丙烯酸甲酯共聚合及聚合物表观性能

研究了甲基丙烯酸异冰片酯与甲基丙烯酸甲酯在 BPO 引发下的共聚合。竞聚率 r_1和 r_2分别为0.91±0.02和0.46±0.01。测试了不同组成共聚物的热、光、力学等性能。     

M_2M'AlB_4(M = Mn,Fe, Co,M' = Cr,Mo, W): Theoretical predicted ordered MAB phases with Cr_3AlB_4 crystal structure

The nanolaminated MAB phases have attracted great research interests due to their unusual combination of metal-like and ceramic-like properties, which is similar to MAX phases. Recently, ordered quaternary MAX phases have been discovered, which enriches the family of MAX phases, and opens a new window to tailor the properties of MAX phases and to develop new MXenes. In the present work, we explored possible ordered quaternary MAB phases with Cr_3AlB_4 structure(space group: Pmmm) by first-principles calculations. The predictions show that M_2M'AlB_4 phases with M = Mn, Fe, Co and M' = Cr, Mo, W exhibit strong tendency of ordering, where M locates at 2t site(0.5, 0.5, z_(2t)) and M' locates at 1 g site(0, 0.5,0.5). The main driving force of ordering may be the differences in bonding strengths between Al and M elements. Analyses on chemical bonds reveal that bonding strengths increase following the order:Al-Mn Al-Fe Al-Co, which is consistent with the prediction that ordering tendency increases when M changes from Mn to Co, as derived from enthalpy differences. The ordered M_2M'AlB_4 phases with M =Mn or Fe are predicted ferromagnetic and ordered M_2M'AlB_4 phases display lower shear resistance and possibly better ductility in comparison to Cr_3AlB_4.     

Coextraction and successive selective stripping of cerium(IV) and thorium from monazite leach solutions with tributyl phosphate (TBP)

Solvent extraction of Ce(IV) and Th(IV) from 8 M HNO₃ with TBP in kerosene was studied. The dependence of the extraction on the TBP concentration, kind of diluent, O/A phase ratio, and contact time was examined. The extraction efficiency reaches 99.3 and 97.7% for Ce and Th, respectively, at 5% TBP in kerosene, 1/1 O/A phase ratio, and 5 min contact time. Successive selective stripping of Ce(III) and Th(IV) from the loaded organic phase was reached at 1.1 M H₂O₂ concentration, 10 min contact time, 3/1 O/A phase ratio, and room temperature (25 ± 2°C). After stripping of cerium, the remaining organic was contacted with H₂O for thorium stripping at 5 min contact time, 2/1 O/A phase ratio, and room temperature (25 ± 2°C).     

A Thermodynamic Equation of State for Pentafluoroethane (R-125)

We developed a fundamental equation of state for pentafluoroethane (R-125, CHF₂CF₃) which is represented in terms of a non-dimensional Helmholtz free energy. The equation has been established on the basis of selected measurements of the pressure-density-temperature relation, speed of sound, heat capacities, and saturation properties. Linear and non-linear regression analysis was employed to determine the functional form and the numerical parameters. The equation represents all the thermodynamic properties of R-125 in the liquid and gaseous phases for temperatures between the triple point and 470 K, and pressures up to 35 MPa. The uncertainties are estimated to be about ±0.05% or 0.1 kPa for the vapor pressure, ± 0.05 % for the liquid and vapor densities, about ± 1 % for the isobaric and isochoric heat capacities in the liquid, and ± 0.5 % or ± 0.02 % for the speed of sound in the liquid and vapor, respectively.     

A Vibrating Plate Fabricated by the Methods of Microelectromechanical Systems (MEMS) for the Simultaneous Measurement of Density and Viscosity: Results for Argon at Temperatures Between 323 and 423K at Pressures up to 68 MPa

In the petroleum industry, measurements of the density and viscosity of petroleum reservoir fluids are required to determine the value of the produced fluid and the production strategy. Measurements of the density and viscosity of petroleum fluids require a transducer that can operate at reservoir conditions, and results with an uncertainty of about ±1% in density and ±10% in viscosity are needed to guide value and exploitation calculations with sufficient rigor. Necessarily, these specifications place robustness as a superior priority to accuracy for the design. A vibrating plate, with dimensions of the order of 1 mm and a mass of about 0.12 mg, clamped along one edge, has been fabricated, with the methods of Microelectromechanical (MEMS) technology, to provide measurements of both density and viscosity of fluids in which it is immersed. The resonance frequency (at pressure p = 0 is about 12 kHz) and quality factor (at p = 0 is about 2800) of the first order bending (flexural) mode of the plate are combined with semi-empirical working equations, coefficients obtained by calibration, and the mechanical properties of the plate to provide the density and viscosity of the fluid into which it is immersed. When the device was surrounded by argon at temperatures between 348 and 423 K and at pressures between 20 and 68 MPa, the density and viscosity were determined with an expanded (k = 2) uncertainty, including the calibration, of about ±0.35% and ±3%, respectively. These results, when compared with accepted correlations for argon reported in the literature, were found to lie within ±0.8% for density and less than ±5% for viscosity of literature values, which are within a reasonable multiple of the relative combined expanded (k = 2) uncertainty.     

Kinetics of Technetium Reactions: XV. Tc(IV) Oxidation with Persulfate Ions in HClO<Subscript>4</Subscript> Solution

Tc(IV) is oxidized with persulfate ions in HClO₄ solution by reactions with both S₂O ₈ ²⁻ ion and product of its thermal decomposition, Caro acid, H₂SO⁵. The reaction rate at 35°C and solution ionic strength μ = 1 is described by the equation d[Tc(IV)]/dt = k ₁[Tc(IV)][S₂O ₈ ²⁻ ] + k ₃[Tc(IV)][HSO ₅ ⁻ ]/[H⁺], where k ₁ = 0.88±0.04 l mol⁻¹ min⁻¹ and k ₃ = 110±5 min⁻¹. With increasing ionic strength to μ = 2, both rate constants decrease (k ₁ = 0.58±0.08 l mol⁻¹ min⁻¹ and k ₃ = 52±2 min⁻¹ at 35°C). The activation energy of the overall reaction is 77.7±8.1 kJ mol⁻¹. The mechanisms of both reactions are discussed. __________ Translated from Radiokhimiya, Vol. 47, No. 2, 2005, pp. 145–149. Original Russian Text Copyright ? 2005 by V. Koltunov, Gomonova, G. Koltunov.     

Übergangsformen zwischen zintlphasen und echten salzen: Die verbindungen A3BO (MIT A = Ca,Sr, Ba und B = Sn,Pb)

The new compounds A₃BO (with A = Ca, Sr, Ba and B = Sn, Pb) crystallize in the cubic system (space group Pm3m) with the following constants:Ca₃SnO: a = 483.4 ± 1 pm, Ca₃PbO: a = 484.7 ± 1 pmSr₃SnO: a = 512.0 ± 1 pm, Sr₃PbO: a = 515.0 ± 1 pmBa₃SnO: a = 544.8 ± 1 pm, Ba₃PbO: a = 545.9 ± 1 pmThe compounds from the perovskite-type structure.     

不同聚合方法对AM/MADQUAT共聚物序列分布的影响

采用溶液聚合和反相微乳液聚合两种方法对丙烯酰胺(AM)、(2-甲基丙烯酰氧乙基)三甲基氯化铵(MADQUAT)在较低单体浓度下进行共聚合。计算得出两种方法中单体AM、MADQUAT的竞聚率,溶液中rAM=0.30,rMADQUAT=1.31;微乳液中rAM=0.63,rMADQUAT=1.12。并用测得的竞聚率数据,通过计算机程序计算了共聚物的瞬时组成、平均组成,在研究溶液和微乳液中共聚物的组成及序列分布的差异时,发现微乳液聚合得到的聚合物的平均组成更均一。     

Higgs Bosons in Particle Physics and in Condensed Matter

Higgs bosons—the amplitude modes—have been experimentally investigated in condensed matter for many years. An example is superfluid ³He-B, where the broken symmetry leads to 4 Goldstone modes and at least 14 Higgs modes, which are characterized by angular momentum quantum number J and parity (Zeeman splitting of Higgs modes with J=2⁺ and J=2^? in magnetic field has been observed in 80’s). Based on the relation $E_{J+}^{2}+E_{J-}^{2}=4\varDelta^{2}$ for the energy spectrum of these modes, Yoichiro Nambu proposed the general sum rule, which relates masses of Higgs bosons and masses of fermions. If this rule is applicable to Standard Model, one may expect that the observed Higgs boson with mass M _H1=125 GeV has a Nambu partner—the second Higgs boson with mass M _H2=325 GeV. Together they satisfy the Nambu relation $M_{\mathrm{H}1}^{2} + M_{\mathrm{H}2}^{2} = 4 M_{\mathrm{top}}^{2}$ , where M _top is the top quark mass. Also the properties of the Higgs modes in superfluid ³He-A, where the symmetry breaking is similar to that of the Standard Model, suggest the possible existence of two electrically charged Higgs particles with masses M _H+=M _H?～245 GeV, which together obey the Nambu rule $M_{\mathrm{H}+}^{2} + M_{\mathrm{H}-}^{2} = 4 M_{\mathrm{top}}^{2}$ . A certain excess of events at 325 GeV and at 245 GeV has been reported in 2011, though not confirmed in 2012 experiments. Besides, we consider the particular relativistic model of top—quark condensation that suggests the possibility that two twice degenerated Higgs bosons contribute to the Nambu sum rule. This gives the mass around 210 GeV for the Nambu partner of the 125 GeV Higgs boson. We also discuss the other possible lessons from the condensed matter to Standard Model, such as hidden symmetry, where light Higgs emerges as quasi Nambu-Goldstone mode, and the role of broken time reversal symmetry.     

Kinetics of Reactions of Np and Pu Ions with Hydrazine Derivatives: XVIII. Reaction between Np(V) and Hydroxyethylhydrazine

The Np(V) reduction with hydroxyethylhydrazine is described by the equation −d[Np(V)]/dt = k ₁[Np(V)][HOC₂H₄N₂H ₄ ⁺ ] + k ₂[Np(V)][Np(IV][H⁺]^1.8, reflecting its main and autocatalytic pathways. The rate constants are k ₁ = 0.31±0.04 l mol⁻¹ min⁻¹ and k ₂ = 4.04±0.11 l^2.8 mol^−2.8 min⁻¹ at 80°C and ionic strength μ = 4. The activation energies are E ₁ = 90±6 and E ₂ = 116±4 kJ mol⁻¹, respectively. The autocatalytic pathway is limited by the reaction between hydroxyethyldiazenium ions, HOC₂H₄N₂H ₂ ⁺ and protonated Np(V) ions. __________ Translated from Radiokhimiya, Vol. 47, No. 2, 2005, pp. 150–153. Original Russian Text Copyright ? 2005 by V. Koltunov, Baranov, G. Koltunov.     

Effect of substrate temperature and precursor ratio on properties of thin ZnS films sprayed by improved method

Zinc sulphide (ZnS) thin films were prepared by improved spray pyrolysis (ISP) method. The ISP parameters, such as carrier gas flow rate, solution flow rate and substrate temperature, were controlled with an accuracy of ±0.25 lpm, ±1 ml/h and ±1 °C, respectively. The solution was sprayed in a pulsed mode. The substrate temperature was optimized by analyzing substrate temperature dependent properties of thin films. The thin film deposited at a temperature of 450 °C was dense and fairly smooth with satisfactory crystallinity and very small impurity content. The effect of precursor ratio in the solution on structural, compositional and optical properties of thin ZnS films, deposited at a temperature of 450 °C, was studied. A gradual increase in band gap energy from 3.524 eV to 3.634 eV, refractive index from 2.5 to 2.9 and dielectric constant from 6.6 to 8.7 were observed with the variation of solution precursor (Zn:S) ratio from (1:2) to (1:6). The structural and compositional studies support this kind of enhancement in optical properties. The results show that the thin ZnS film prepared by ISP at the substrate temperature of 450 °C from a solution with specific precursor ratio can be used for optoelectronic and photovoltaic applications.     

Preparation and properties of the (TlInSe2)0.96Se0.04 solid solution

TlInSe₂-rich TlInSe₂-Se alloys (0?C10 mol % Se) have been studied by X-ray diffraction. In the composition range 2.0?C6.0 mol % Se, the TlInSe₂-based ??-solid solutions decompose by a peritectoid reaction at 363 K. The space group of the (TlInSe₂)_0.96Se_0.04 solid solution is P222, and its lattice parameters are a = 6.575 ± 0.001 ?, b = 10.080 ± 0.001 ?, and c = 11.280 ± 0.001 ?. The electrical conductivity of singlecrystal samples of this solid solution is (0.5?C3.0) × 10^?3 S/cm at room temperature and varies little at temperatures from 85 to 280 K.     

Comparative strengths of fresh water ice

In order to gain a quantitative comparison among the various mechanical properties of ice, a series of tests was performed on fresh water ice in which several of the mechanical properties were tested under identical experimental conditions. In particular, the tests were standardized with respect to ice growth conditions, ice type, grain size and orientation, sample size, test temperature and strain rate. The average results of the test were: flexural strength ? cantilever beam = 770 ± 150 kPa; flexural strength ? simple beam (top tension) = 2200 ± 320 kPa; flexural strength ? simple beam (bottom tension) = 1770 ± 190 kPa; $\text{fracture toughness}\text{= 83 ± 7}\text{kPa m}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$; shear strength = 500 ± 220 kPa; compressive strength (horizontal loading) = 4400 ± 700 kPa and strain modulus ? cantilever beam = 1.6 ± 0.4 GPa. Since most of the tests were performed using a portable compression test machine, the strength values can serve as baseline values for comparison with field results.     

Interaction of tetravalent actinides and Np(V) with some hydroxy carboxylic acids

Interaction of actinides(IV) with hydroxyisobutyric acid (HHIB) in aqueous solutions and in the course of crystallization of solid compounds was studied. The complexes ML _n ^(4-n)+ (M = U, Np, Pu; L^? is hydroxyisobutyrate anion; n = 1, 2, 3) exist in solution. Their apparent stepwise stability constants K?? _i were measured, and the overall concentration stability constants ??₃ of the complexes ML ₃ ⁺ were calculated. For U(IV) and Np(IV), log??₃ is close to 13.3?C13.4, and for Pu(IV), log??₃ = 14.5 ± 0.9 (ionic strength I = 0.1?C0.3). In the course of crystallization in air, complexes of U(IV) with hydroxyisobutyric acid, as well as those with citric acid, undergo oxidative degradation, which can be accompanied by complete oxidation of U(IV). The crystalline compounds formed in the process are oxalates of U(IV) or U(VI). The complexation of Np(V) with HHIB was studied. NpO ₂ ⁺ forms with HHIB the complexes NpO₂L and NpO₂L ₂ ^? . Their concentration stability constants are logK ₁ = 2.04 ± 0.15 and logK ₂ = 0.71 ± 0.10 (I = 0.4), i.e., log??₂ = 2.75 ± 0.25.     

聚乙二醇改性聚乳酸的合成与性能表征

以外消旋乳酸(D,L-LA)和不同数均分子量(Mn)的聚乙二醇(PEG)为原料,通过熔融缩聚法,合成了系列聚乳酸聚乙二醇(PLEG)。最佳工艺条件为:以(Sn(Oct)2)为催化剂,m(Sn(Oct)2)为0.8%,n(PEG)∶n(D,L-LA)=1∶600,聚合温度170℃,压力0.096 MPa条件下,反应8h。用特性粘度测试、FT-IR、XRD、接触角等对其进行表征,实验结果表明系列PLEG中PLEG-800接触角为63°,表明其亲水性能最好;PEG-800和乳酸共聚合成的PLEG的粘均分子量最大,可达48997,与PDLLA相比,结晶度有较大提高,亲水性得到改善。     

Monte Carlo Study of the Phase Diagrams of a Ferrimagnetic Nanowire with Alternate Layers

A Monte Carlo simulation based on Metropolis algorithm has been used to investigate the magnetic properties of an Ising ferrimagnetic nanowire on a hexagonal structure, which is made up with L alternate layers of spins σ = ±3/2, ±1/2 and S = ±1, 0. The critical behaviors are studied, in the absence as well as in the presence of crystal field interactions. The obtained results show the existence of some interesting phenomena, such as the appearance of different types of phase diagrams. Furthermore, tricritical point, isolated critical point, critical end point, and compensation behavior are found for appropriate values of the system parameters.     

Hot-pressed ceramic SiC–YAG materials

Dense SiC-based ceramic materials containing yttrium aluminum garnet (YAG) as an oxide sintering aid have been prepared by hot pressing in the temperature range 1750–1850°C. As a result of melting, the oxides fill spaces between the SiC particles, contributing to the densification of the material and mass transport during the hot pressing process. The present results demonstrate that relatively small amounts of the oxides (≤5 wt %) are needed to ensure a high degree of densification of the SiC–YAG materials. The best physicomechanical properties are offered by the SiC + 3 wt % YAG material sintered at a temperature of 1850°C: ρ = 3.24 ± 0.01 g/cm³, П = 1.1 ± 0.1%, σ_b = 640 ± 10 MPa; K_Ic = 6.4 ± 0.2 MPa m^1/2, Еel = 410 ± 20 GPa, and HV = 26.0 ± 0.2 GPa. This material experiences predominantly intercrystalline fracture.     

Thermoelectric Characterization of （Na1-yMy）1.6Co2O4 （M=K, Ca, Sr）

Oxide materials NaCo2O4 and (Na1-yMy)1.6Co2O4 (M=K, 0.05≤y≤0.35; M=Ca, Sr, 0.10≤y≤0.40) were prepared by a sol-gel method. Experimental results indicated that the Seebeck coefficient and the Powerfactor of NaCo2O4 were improved by doping Ca and Sr but not by K. The Power-factor of NaCo2O4 is in its maximum, 1.68×10-4 W·m-1·K-2 and 11% bigger than that of the original one when the dopant fraction of Ca was 0.1. Doping Sr makes NaCo2O4 have the biggest Power-factor, 1.68×10-4 W·m-1·K-2 that is 50% bigger than the non-doping oxide. The experimental results indicate that suitable dopants and addition amounts could improve the thermoelectric properties of NaCo2O4 greatly.     

Thermodynamic properties of HFO-1336mzz(E) (trans-1,1,1,4,4,4-hexafluoro-2-butene) at saturation conditions

The thermodynamic properties of HFO-1336mzz(E) (trans-1,1,1,4,4,4-hexafluoro-2-butene) were determined. The critical point was ascertained by visual observation of the meniscus disappearance within an optical cell. The critical temperature, critical density, and critical pressure were determined to be 403.37 ± 0.03 K, 515.3 ± 5.0 kg m⁻³, and 2766.4 ± 4.5 kPa, respectively. Vapor pressures were also measured at temperatures ranging from 323 K (50 °C) to the critical temperature, and were correlated using the Wagner-type equation. The acentric factor and normal boiling point were determined to be 0.4053 and 280.58 K (7.43 °C), respectively, using the vapor pressure correlation. Based on the critical parameters and the acentric factor, saturated vapor densities and liquid densities were estimated using the Peng–Robinson equation and the Hankinson–Thomson equation, respectively. The heat of vaporization was also calculated from the Clausius–Clapeyron equation.     

Growth reproducibility of the bubble properties of (YSmLuCa)3 (FeGe)5 O12 films

Reproducibility of CaGe garnet films grown by LPE is discussed in comparison with that of Ga garnet films. The influence of growth temperature deviation on the properties of CaGe garnet films is not compensated by the adjustment of the substrate rotation rate, although it is effective for Ga garnet film growth. On the other hand, the bubble collapse field of CaGe garnet films is less sensitive to the growth temperature than that of Ga garnet films. Therefore by determining the growth time accurately the bubble collapse field of as-grown films has been controlled within ±1%, even if the growth temperature deviates from the desired value by ±1°C.