J/psi production in Indium-Indium collisions at 158 GeV/nucleon

The NA60 experiment studies muon pair production at the CERN Super Proton Synchrotron. In this Letter we report on a precision measurement of J/psi in In-In collisions. We have studied the J/psi centrality distribution, and we have compared it with the one expected if absorption in cold nuclear matter were the only active suppression mechanism. For collisions involving more than approximately 80 participant nucleons, we find that an extra suppression is present. This result is in qualitative agreement with previous Pb-Pb measurements by the NA50 experiment, but no theoretical explanation is presently able to coherently describe both results.     

HPLC-MS/MS法联合分析环境水体中喹诺酮类抗生素和雌激素

建立了环境水体中15种喹诺酮类抗生素和6种雌激素的HPLC-MS/MS分析方法.该方法统一了两类物质的前处理过程,运用固相萃取技术进行富集及净化,有效降低了基质的干扰.质谱采用SRM监测模式,喹诺酮采用正离子扫描模式,雌激素采用负离子扫描模式.目标化合物在水体中的回收率范围为62.0％～108.3％,RSD在1.1％ ...     

微波辐射法制备水溶性CdTe/ZnS量子点及其与司帕沙星的作用

以巯基乙酸为稳定剂,通过微波加热在水溶液中制备了CdTe/znS量子点.研究了pH值、反应时间、反应温度和cdTe/s<'2->浓度比等合成条件对cdTe量子点荧光光谱的影响.以CdTe/ZnS量子点为探针,探讨了喹诺酮类抗生素司帕沙星与量子点的荧光猝灭作用,结果表明,在最佳实验条件下,其线性范围为0.05～3.00μg/mL,线性相关系数为0.9954,检出限为0.01μg/mL,可将CdTe/ZnS量子点荧光探针用于司帕沙星的测定.     

缺位的Wells-Dawson型磷钨酸盐和Eu(Ⅲ)构筑的一维链状多金属氧酸盐化合物

在水溶液条件下以六缺位的[H2P2W12O48)]12-和Eu髥为反应前躯体得到了1个新的多金属氧酸盐化合物[Eu3(H2O)17(α2-HP2W17O61)].5H2O(1),对其进行了元素分析、红外光谱、热重、荧光等表征,并用X-射线单晶衍射测定了它的晶体结构。化合物1含有双支撑的多阴离子簇[{Eu(H2O)7}2{Eu(H2O)3(α2-P2W17)}2]8-,并进一步通过Eu髥连接形成了延c轴方向的一维链。室温条件下的荧光光谱研究表明:化合物1显示了强的红光发射。     

Effects of Hydroxyapatite Nanoparticles on Apoptosis and Invasion of Human Renal Cell Carcinoma 786-0 Cells

Renal cell carcinoma is the most common cancer of the kidney, and resistant to traditional therapies. The aim of this study is to investigate the effects of hydroxyapatite nanoparticles on human renal cell carcinoma 786-0 cells. Cell proliferation was assessed with an 3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyltetrazolium bromide(MTT) staining kit. The apoptosis assay was assessed with an FITC Annexin V Apoptosis Detection Kit. Caspase-3 and caspase-12 were detected by immunocytochemical staining and semi-qua...     

Effect of substituent distribution on water solubility of O-methylcellulose

The effect of substituent distribution on the water solubility of O-methylcellulose (MC) was re-examined to elucidate the lower limit of the degree of substitution (DS) in water-soluble MC. To this end, a series of 2,3-MCs which are regioselectively substituted at the C-2 and C-3 hydroxyl groups were prepared by homogeneous methylation. It was found that the lower limit for the DS value of water-soluble 2,3-MC was almost the same as that for MCs having even distributions of substituents along the cellulose chain as well as in the anhydroglucose units. This revised version was published online in August 2006 with corrections to the Cover Date.     

Angular distributions in the dimuon hadronic production at 150 GeV/c

From π^- interactions at 150 GeV/c on a heavy target, we present the final analysis of the dimuon decay angular distribution in the mass interval 4.5–8.5 GeV/c². Results are presented and discussed in various reference frames and are also given in terms of the density matrix elements. Finally the possible contribution of higher-twist effects at largex ₁ is discussed; we find that our data are not compatible with higher twist contributions as proposed by the Berger and Brodsky Model.     

A study of π andK production in proton-uranium and oxygen-uranium interactions at 22 GeV/A using decay muons

The like-sign dimuons copiously recorded in the NA 38 experiment both inp-U and O?U reactions at 200 GeV/nucleon are interpreted as resulting from decays of π andK mesons in comparable proportions. The ++/?? ratio is large (?1.7) and ascribed to theK ⁺ being more copiously produced than theK ^?. Both the average transverse momentum and the ++/?? ratio are comparable forp-U and O?U reactions, and both increase only slightly with the transverse energyE _T .     

需求可变性降低对均值CVaR约束销售努力决策库存系统的影响

本文运用Levy提出的变换研究需求可变性降低对风险偏好零售商的库存决策、销售努力决策和期望效用的影响,用均值CVaR刻画零售商的风险偏好特性,它包括风险厌恶、风险追求,也具有损失规避的特性。首先,运用该变换定量刻画需求可变性的降低,证明该变换蕴含经典随机占优中的割准则序和二阶随机占优等。其次,给出系统的最优订货量、最优期望效用和最优销售努力水平,得到它们关于风险偏好系数的单调性,并给出降低需求可变性对期望效用的影响。第三,针对风险中性、风险厌恶(最大化CVaR)和风险追求(最小化CVaR)这三种特殊情况得到相应的结果,并给出企业在库存决策和促销决策的管理启示。最后,通过数值例子验证了得到的研究结果并给出相应的管理启示。     

不同助剂对CuO-ZnO/SBA-15催化CO_2加氢制甲醇性能影响的研究

以硅质骨架结构介孔分子筛SBA-15为载体,采用浸渍法合成CuO-ZnO/SBA-15(CZ/SBA-15)、CuO-ZnO-MnO_2/SBA-15(CZM/SBA-15)、CuO-ZnO-ZrO_2/SBA-15(CZZ/SBA-15)三组多孔催化剂,在固定床反应器上评价了各组催化剂催化CO_2加氢合成甲醇的性能,同时结合N_2吸附-脱附(BET)、X射线衍射(XRD)、H_2程序升温还原(H_2-TPR)、程序升温脱附(H_2-TPD、CO_2-TPD)、N_2O滴定、X射线光电子能谱(XPS)、透射电子显微镜(TEM)等表征研究了不同助剂对CO_2催化加氢制甲醇的影响。结果表明,催化剂中的金属氧化物改变了SBA-15分子筛载体的孔径大小和比表面积;催化剂CuO-ZnO-MnO_2/SBA-15、CuO-Zn O-ZrO_2/SBA-15中铜的分散度(D_(Cu))和比表面积(A_(Cu))更大,表面CuO粒径更小,更易被还原;相比Mn-O簇,Zr-O簇为增强了碱性位点,提高了甲醇选择性。此外,CuO-ZnO-ZrO_2/SBA-15具有更高的氧空位浓度,催化活性更好,其甲醇选择性为25.02%,与CuO-ZnO/SBA-15、CuO-ZnO-Mn O_2/SBA-15相比分别提高了28%和136.9%,催化效果最好。