同位素稀释超高效液相色谱-串联质谱法测定人血清中孕酮

建立了超高效液相色谱-串联质谱(UPLC-MS/MS)测定人血清中孕酮的分析方法。血清样品经乙酸乙酯、正己烷液液萃取(LLE)后,采用Acquity UPLC BEH C_(18)色谱柱(2.1 mm×100 mm,1.7μm)进行梯度分离,色谱运行时间为5 min,采用电喷雾(ESI)正离子电离模式和多反应监测(MRM)扫描模式,同位素内标法定量。考察了两步萃取法对孕酮的提取效果,不同流动相的分离效果以及样品稳定性,结果表明以甲醇-0.1%氨水溶液为流动相时分离效果较好。优化条件下,孕酮在10～10 000pg/mL范围内线性关系良好(r~2=0.999 8),方法检出限和定量下限分别为5、10 pg/mL;平均加标回收率为91.5%～106%,日内相对标准偏差(RSD)为1.2%～8.2%,日间RSD为4.1%～9.1%。采用该方法对30个真实血清样品进行测定,孕酮质量浓度为0.050 2～1.363 5 ng/mL,均在正常生理范围内。该方法灵敏度高、准确可靠,可用于临床血清样品中孕酮生理水平的检测。     

Comparison of thermodynamic and kinetic aspects of oxidative addition of PhE-EPh (E = S, Se, Te) to Mo(CO)3(PR3)2, W(CO)3(PR3)2, and Mo(N[tBu]Ar)3 complexes. The role of oxidation state and ancillary ligands in metal complex induced chalcogenyl radical generation

Enthalpies of oxidative addition of PhE-EPh (E = S, Se, Te) to the M(0) complexes M(PiPr3)2(CO)3 (M = Mo, W) to form stable complexes M(*EPh)(PiPr3)2(CO)3 are reported and compared to analogous data for addition to the Mo(III) complexes Mo(N[tBu]Ar)3 (Ar = 3,5-C6H3Me2) to form diamagnetic Mo(IV) phenyl chalcogenide complexes Mo(N[tBu]Ar)3(EPh). Reactions are increasingly exothermic based on metal complex, Mo(PiPr3)2(CO)3 < W(PiPr3)2(CO)3 < Mo(N[tBu]Ar)3, and in terms of chalcogenide, PhTe-TePh < PhSe-SePh < PhS-SPh. These data are used to calculate LnM-EPh bond strengths, which are used to estimate the energetics of production of a free *EPh radical when a dichalcogenide interacts with a specific metal complex. To test these data, reactions of Mo(N[tBu]Ar)3 and Mo(PiPr3)2(CO)3 with PhSe-SePh were studied by stopped-flow kinetics. First- and second-order dependence on metal ion concentration was determined for these two complexes, respectively, in keeping with predictions based on thermochemical data. ESR data are reported for the full set of bound chalcogenyl radical complexes (PhE*)M(PiPr3)2(CO)3; g values increase on going from S to Se, to Te, and from Mo to W. Calculations of electron densities of the SOMO show increasing electron density on the chalcogen atom on going from S to Se to Te. The crystal structure of W(*TePh)(PiPr3)2(CO)3 is reported.     

产学研合作创新方式下政府补贴策略选择

创新补贴策略是政府鼓励企业创新的一种常见政策,考虑到企业内在的吸收能力与外部不同政府补贴策略方式的存在,本文以产学研合作创新方式为基础,通过建立三阶段博弈模型,利用模型解析与仿真分析讨论吸收能力与创新投入分配比例系数对政府补贴策略选择的影响。研究结果表明:无论政府采取哪一种补贴方式,均可以有效激励企业加大创新投入规模,并且企业的吸收能力与R&D投入、产量及社会福利均呈正相关关系;但是,吸收能力对利润及政府补贴的影响受限于补贴方式和企业的创新投入分配比例系数;此外,在创新产品补贴下,创新难度系数对政府补贴额度的影响并不明显,而创新产品补贴总体优于创新投入补贴。     

Metallization of fluid hydrogen at 140 GPa (1.4 Mbar) by shock compression

Shock compression was used to produce the first observation of a metallic state of condensed hydrogen. The conditions of metallization are a pressure of 140 GPa (1.4 Mbar), 0.6 g/cm (ninefold compression of initial liquid-H density), and 3000 K. The relatively modest temperature generated by a reverberating shock wave produced the metallic state in a warm fluid at a lower pressure than expected previously for the crystallographically ordered solid at low temperatures. The relatively large sample diameter of 25 mm permitted measurement of electrical conductivity. The experimental technique and data analysis are described. Received 12 November 1997 / Accepted 10 November 1998     

Reactions of hydroxyl radicals with polystyrene

The reaction of polystyrene with hydroxyl radicals, generated by the photolysis (λ > 300 nm) of H₂O₂, has been studied at 25° in dichloromethane solution, both under vacuum conditions and in presence of O₂. Spectroscopic analyses suggest the presence of phenols and hydroxymucondialdehydes (when O₂ is present) among the reaction products, indicating that OH addition occurs at the phenyl groups of the polymer. By comparison with initiated oxidation reactions under the same conditions, it is concluded that the OH radicals undergo mainly addition reactions. A mechanism has been produced to account for the products. The significance of OH addition reactions in the oxidation of polystyrene is considered, the OH radicals being produced by hydroperoxide decomposition during oxidation, and the products having been previously identified as containing mucondialdehydes.     

Photolysis of poly(o-acetylstyrene) in solution

Dilute solutions of poly(o-acetylstyrene) (POAS) were exposed to long-wave (λ ≥ 300 nm) UV radiation under high vacuum at 25 ± 1°C. Methane and much smaller amounts of ethane were formed, indicating α-cleavage (Norrish Type I). The quantum yield for CH₄ formation (5 × 10^?5 mol einstein^?1) was an order of magnitude lower than that observed for similar studies of POAS films. Molecular weight ( M _n) measurements indicate that chain scission occurs, and this is attributed to β-scission of the macroradicals formed by H-abstraction at the α-C atoms by the carbonyl triplet, and to a lesser extent, by the CH₃ radicals. Quenching by both naphthalene and cyclooctadiene conformed to Stern–Volmer kinetics. The effects on chain scission of a number of additives with varying transfer activities were found to be complex and unexpected. Rates of scission not only increased, even when substances with high transfer activity (e.g., cumene) were present, but also varied with the concentration of additive, being higher at lower additive concentrations. It would appear that solvent quality has a dominant influence (these additives are poor solvents). Tighter coiling of the polymer in the solutions containing poorer solvents results in more segment-segment contacts and with them more photoreduction and chain scission. However, at higher nonsolvent concentrations, diffusive separation of the fragments (and chain scission) becomes more difficult, and the balance is shifted in favor of cyclization (and perhaps also intermolecular crosslinking). The relative high photostability of POAS in solution (cf. thin film) has been interpreted in terms of increased competition from photoisomerization. © 1992 John Wiley & Sons, Inc.     

Photochemistry of ring substituted polystyrenes—Part III: Photolysis of poly(para-methoxystyrene)

The photodegradation of films (4 × 10^?4 cm thick) of poly(p-methoxystyrene) with 254 nm radiation under high vacuum at 25°C has been studied. The principal gaseous product is hydrogen, but smaller quantities (in decreasing yield) of methane, methyl alcohol and ethane are also formed, indicating that fission of bonds in the para methoxy group is also involved. Ultraviolet and visible spectra of degraded films indicate the presence of unsaturated groups and of coloured species. Solubility data indicate that crosslinking and chain scission occur simultaneously. Rates of chain scission of a number of p-substituted styrenes are compared and a reasonable correlation between these and the electron donating character of the para group is observed, explainable in terms of the stabilising effect of such groups on the radicals formed during chain scission. Rates of crosslinking are greater than those for polystyrene and this is attributable to the participation of the substituted phenoxy radicals (formed by CH₃O fission) in addition reactions. Quantum yields for the gaseous products and for chain scission and crosslinking have been determined and a mechanism has been advanced to account for the experimental data.     

A modified kinematic model for the discharge of a granular-like material from long vertical cylinders

The rapid and uncontrolled discharge of a large-sized granular-like material from a vertical cylinder is modelled assuming a modified kinematic relationship exists between granular pressure, speed and density. Discharge is driven by the initial Janssen pressure, and a Beverloo-type equation is derived for the initial discharge. A shock occurs at the bottom of the cylinder, and another upwards travelling shock separates static and moving material. The initial discharge is non-constant, with the constant density and discharge case violating the 'entropy' condition. Two sets of characteristics are found : one travelling upwards, associated with the motion of voids; and the other travelling downwards, associated with work performed by the particle pressure. Contrary to hopper models, a low density of solids is predicted about the cylinder exit. The modified kinematic model allows density waves to travel either up or down through the cylinder, but the frequency and speed of the waves is not fixed uniquely by the model. The waves exhibit a saw-tooth behaviour, with a continuously increasing magnitude in flux at the orifice, interspersed with discontinuous decreases.     

C_(18)膜萃取/液相色谱-质谱联用法测定极地水体中有机磷酸酯

建立了C_(18)膜萃取/液相色谱-质谱联用技术测定极地水体中10种有机磷酸酯(OPEs)的方法。根据优化后的样品前处理及仪器方法,利用C_(18)膜富集4 L水体中的10种OPEs,经二氯甲烷超声提取,在电喷雾正离子模式下,采用选择反应监测(SRM)模式进行分析,线性相关系数为0.994 4~0.999 9。10种OPEs的加标回收率为64.1%~115%,方法检出限为0.08~0.55 ng/L。该方法适用于极地水体中10种OPEs的分析,利用该方法对北极水体样品中的10种OPEs进行检测,测得冰川融水中∑OPEs的质量浓度为0.64~6.64 ng/L,海水中∑OPEs的质量浓度为0.09~2.03 ng/L。     

碳化铁催化剂的制备及其对CO加氢的催化活性

 以Fe2O3为原料,采用两种预处理方法制备了碳化铁催化剂. 结果表明,直接在CO气氛下进行碳化处理,或者以H2预还原后再用CO进行碳化处理均可以制备出碳化铁催化剂. 碳化温度是制备过程中的关键因素. 对于Fe2O3样品,较适宜的碳化温度是350 ℃,而对于添加了K助剂的样品,只有经H2预还原处理后再于350 ℃用CO碳化处理4 h才能将样品完全转化为Fe5C2. 在CO加氢的评价实验中,碳化铁催化剂表现出很高的催化活性,生成的烃类产物中主要是饱和烷 烃,未检测到乙烯的生成. 而在K改性的催化剂上反应产物中烯烃的含量明显提高.