碱金属和碱土金属离子在反相高效液相色谱柱上的保留机理

发现以酒石酸和吡啶二甲酸等羧酸水溶液作淋洗剂时，钠，铵，钾，镁和钙等碱金属及碱土金属离子在ＯＤＳ反相高效液相色谱柱上有明显的保留，而且相互之间能达到一定程度的分离。单独用分配或疏水作用等反相高效液相色谱的保留机理难以解释其保留行为。为此，作者提出了动态包固定相机理，即认为羧酸根阴离子因其疏水性在ＯＤＳ固定相有保留，在固定相表面形成具有羧酸基阳离子交换树脂功能的动态包覆固定相。     

液相色谱-串联质谱法同时测定蜂胶中的磺胺及林可胺类药物残留

建立了同时检测蜂胶中16种磺胺及2种林可胺类药物残留的方法,以1.0 mol/L HCl溶液为提取液,经阳离子固相萃取小柱净化富集后,高效液相色谱-串联质谱仪分析。采用Agilent Polaris C18色谱柱(100 mm×2.0 mm,5μm),以甲醇和0.1%甲酸为流动相梯度洗脱,质谱模式为电喷雾正离子监测。该方法前处理简单,分别以13C6-磺胺二甲基嘧啶、13C6-磺胺甲噁唑为磺胺类药物内标、以D3-林可霉素为林可胺类药物内标进行定量,磺胺和林可胺类药物的线性范围均为1.0~50μg/L,相关系数均在0.99以上,方法定量限为10.0μg/kg,在10,20和40μg/kg 3个水平做添加回收,回收率范围为69.5%~114.6%,相对标准偏差小于10%。     

采用CO吸附原位红外光谱研究Pt/TiO2光催化体系中助催化剂作用

采用CO作为探针分子,将原位透射红外光谱应用于研究助催化剂Pt在Pt/TiO2光催化体系中的作用.实验发现,光照条件下,CO的覆盖度及样品温度没有明显变化,CO在Pt/TiO2上的吸附峰红移11 cm–1,在Pt/Al2O3上的吸附峰没有位移,表明CO在Pt/TiO2上的红移来源于TiO2上的光生电子转移到Pt上,这解释了为什么加入Pt助催化剂可提高光催化产氢活性.     

过渡金属替代的CeO2（111）表面上NO+CO反应机理的理论研究（英文）

采用DFT+U方法研究了过渡金属替代的CeO2(111)表面上的NO+CO反应机理,以探求不同过渡金属对N2选择性的影响.结果表明,在反应过程中,反应活性中心由过渡金属单原子与其最近邻的氧空位组成.NO在过渡金属-氧空位上发生N–O断键,不同过渡金属上该还原步骤的难易程度不同.计算发现,右过渡金属Rh,Pd和Pt替代的CeO2(111)表面可以与吸附物之间形成较强的吸附作用,进而可以达到较高的N2选择性.其主要原因是右过渡金属具有较多的d电子,可以与吸附小分子之间形成有效的反馈键.而左过渡金属拥有较少的d电子,难以有效抓住吸附物,最终导致较低的N2选择性.     

CuBr_2催化的三组分反应合成喹啉-2,4-二羧基衍生物

以廉价的CuBr2为催化剂,发展了一种通过芳胺、乙醛酸酯与丙酮酸酯三组分反应制得喹啉-2,4-二羧基衍生物的简便有效方法.该方法具有很好的原子经济性,使用了便宜的催化剂和易得的试剂,在温和的条件下解决了以往喹啉-2,4-二羧基衍生物合成条件苛刻、产率低等问题,在生物活性分子和药物分子合成上有潜在的应用价值.     

Recombination analysis of autosomal short tandem repeats in Chinese Han families

Recombination fractions between forensic STRs can be extrapolated from the International HapMap Project, but the concordance between recombination fractions predicated from genetic maps and derived from observation of STR transmissions in families is still ambiguous for autosomal STRs because of limited family studies. Therefore, the main goal of this study is to compare recombination fractions estimated by pedigree analysis with those derived from HapMap phase SNP data. Genotypes of nine autosomal STR pairs (TPOX‐D2S1772, D5S818‐CSF1PO, D7S3048‐D7S820, D8S1132‐D8S1179, TH01‐D11S2368, vWA‐D12S391, D13S325‐D13S317, D18S51‐D18S1364, and D21S11‐PentaD) from 207 two‐generation families with two to five children (the number of families with five, four, three, and two children was 2, 3, 20, and 182, respectively) were used to analyze the recombination. The linkage analysis showed that significant linkage was observed at six STR pairs (D5S818‐CSF1PO, D8S1132‐D8S1179, TH01‐D11S2368, vWA‐D12S391, D13S325‐D13S317, and D18S51‐D18S1364) with genetic distances <36.22 cM in HapMap. Their recombination fractions calculated from family data were very close to those derived from HapMap. However, three STR pairs of TPOX‐D2S1772, D7S3048‐D7S820, and D21S11‐PentaD showed no significant linkage with genetic distances from 43.38 to 91.49 cM. Our results indicate that recombination fractions extrapolated from HapMap can provide a substitute if empirical data are unavailable for the linkage STR pair with a genetic distance spanned <36.22 cM.     

Design of Enzymatically Cleavable Prodrugs of a Potent Platinum‐Containing Anticancer Agent

Using a versatile synthetic approach, a new class of potential ester prodrugs of highly potent, but systemically too toxic, platinum–acridine anticancer agents was generated. The new hybrids contain a hydroxyl group, which has been masked with a cleavable lipophilic acyl moiety. Both butanoic (butyric) and bulkier 2‐propanepentanoic (valproic) esters were introduced. The goals of this design were to improve the drug‐like properties (e.g., logD) and to reduce the systemic toxicity of the pharmacophore. Two distinct pathways by which the target compounds undergo effective ester hydrolysis, the proposed activating step, have been confirmed: platinum‐assisted, self‐immolative ester cleavage in a low‐chloride environment (LC‐ESMS, NMR spectroscopy) and enzymatic cleavage by human carboxylesterase‐2 (hCES‐2) (LC‐ESMS). The valproic acid ester derivatives are the first example of a metal‐containing agent cleavable by the prodrug‐converting enzyme. They show excellent chemical stability and reduced systemic toxicity. Preliminary results from screening in lung adenocarcinoma cell lines (A549, NCI‐H1435) suggest that the mechanism of the valproic esters may involve intracellular deesterification.     

Revisiting the thermosensitivity of poly(acrylamide-co-diacetone acrylamide)

The lower critical solution temperature （LCST） behavior of poly（acrylamide-co-diacetone acrylamide） （poly（AM-co-DAM）） copolymer in aqueous solutions was studied. The results demonstrate the LCST linearly decreases as the molar fraction of DAM （fDAM） increases. In the range of fDAM 〈 0.36, the transmittance increases as fDAM decreases because the more hydrophilic copolymer chains can form looser aggregates with a lower refractive index. The transmittance exhibits a minimum when fDAM is less than 0.28 as the chains form micelle-like structure with a size smaller than the wavelength. The LCST decreases with the initial polymer concentration, but it levels off when the polymer concentration is high enough. Moreover, no hysteresis can be observed in the change of transmittance during the heating-cooling process because no additional hydrogen bonds are formed in the collapsed state due to the steric hindrance of the large side groups in DAM units.     

Synthesis and characterization of novel blue emitting Na2CaSiO4:Ce3+ phosphor

The blue phosphors Na_(2?x)Ca_(1?x)SiO₄:xCe³⁺ were synthesized by the sol–gel method and their luminescence characteristics were investigated for the first time. Structural information about prepared samples is obtained by analyzing the XRD patterns and SEM micrographs. The photoluminescence (PL) excitation spectra indicate that the Na_(2?x)Ca_(1?x)SiO₄:xCe³⁺ phosphors can be effectively excited by ultraviolet (360 nm) light. The PL emission spectra exhibit tunable blue broadband emission with the dominant wavelength of 427–447 nm under excitation of 360 nm by controlling the doping concentration of Ce³⁺. The concentration quenching effect for Ce³⁺ was found at the optimum doping concentration of 4 mol%. The Commission Internationale de l’Eclairage 1931 chromaticity coordinates of Na_1.96Ca_0.96SiO₄:0.04Ce³⁺ are (0.1447, 0.0787), which are better color purity compared to the commercial Eu²⁺-doped BaMgAl₁₀O₁₇ phosphor. Na_1.96Ca_0.96SiO₄:0.04Ce³⁺ composition shows intense blue emission (peak wavelength, 439 nm) with relative intensity versus commercial BaMgAl₁₀O₁₇:Eu²⁺ blue phosphor (Nichia) 65 and 158 % under 254 and 365 nm excitation, respectively. All the results indicate that Na_(2?x)Ca_(1?x)SiO₄:xCe³⁺ phosphors are potential candidate as a blue emitting phosphor for UV-converting white light-emitting diodes.     

Synthesis of chiral 1,3-bis(1-(diarylphosphoryl)ethyl)-benzenes via Ir-catalyzed double asymmetric hydrogenation of bis(diarylvinylphosphine oxides)

<正>1 General methods Unless otherwise noted, all reactions and manipulations involving air- or moisture-sensitive compounds were performed using standard Schlenk techniques or in a glovebox. All solvents were purified and dried using standard procedures. Melting points were measured on a RY-I apparatus and uncorrected. 1H, 13 C, 31 P and 19 F NMR spectra were recorded on Varian Mercury 300 or 400 MHz spectrometers. Chemical shifts(δ values) were reported in ppm downfield from internal TMS(1H NMR), CDCl3(13C NMR), external 85% H3PO4(31P NMR), and external CF3CO2H(19F NMR), respectively. Optical rotations were determined using a Perkin Elmer 341 MC polarimeter. The IR spectra were measured on a BRUKER TENSOR 27