Gluon saturation and net-proton spectra in relativistic nucleus-nucleus collisions

By means of the AKK08 fragmentation function, the net-proton transverse momentum (pT) spectra in A+A collisions are studied with two phenomenological models based on the Color Glass Condensate formalism. After a χ² analysis of the experimental data from BRAHMS, the normalization constant C is extracted at RHIC energies of √sNN=62.4 and 200 GeV, and the theoretical results of the net-proton pT spectra at selected rapidities are also given. It is shown that the theoretical results are in good agreement with the experimental data. Finally, assuming the constant C should have an exponent dependence of √sNN, we also predict the theoretical results of net-proton pT spectra at LHC energies of √sNN=2.76, 3.94, and 5.52 TeV.     

Bioreduction of methyl o-chlorobenzoylformate at 500 g L without external cofactors for efficient production of enantiopure clopidogrel intermediate

Biocatalytic reduction of methyl o-chlorobenzoylformate (CBFM) provides a green and direct access to methyl (R)-o-chloromandelate [(R)-CMM], an intermediate for a platelet aggregation inhibitor named clopidogrel. As much as 500 g L⁻¹ of CBFM was stoichiometrically converted into enantiopure (R)-CMM at 20 °C by using a whole-cell catalyst coexpressing an aldo-keto reductase from Bacillus sp. and a glucose dehydrogenase (GDH). In addition to the high productivity of 812 g L⁻¹ d⁻¹, this new whole-cell reduction is attractive by eliminating the need of an added external cofactor.     

丙醇-硫酸铵-1-（2-吡啶偶氮）-2-萘酚双水相萃取铅（Ⅱ）

研究了丙醇-硫酸铵双水相体系中Pb（Ⅱ）的萃取行为.实验表明：铅-碘化钾-PAN形成的离子缔合物容易被萃取到丙醇相中,在pH 4.4且无PAN时,双水相体系对[PbI4]2-络阴离子的萃取率为0;加入PAN后,该体系几乎能完全萃取体系中的离子缔合物.该稳定缔合物的最大吸收波长为486nm,表观摩尔吸光系数为1.47×105L·mol-1·cm-1,相关系数r为0.9989,铅（Ⅱ）的质量浓度在0-1.4μtg/10mL呈线性关系.     

一种基于DAD二极管阵列检测器技术的中药指纹图谱方法

用HPLC/DAD分别建立血府逐瘀口服液单波长指纹图谱和最大吸收指纹图谱, 对比两者峰数量和面积的变化情况, 采用药典委员会2004A版相似度软件评价两种方法的差异. 结果表明, 最大吸收指纹图谱比单波长指纹图谱或多波长指纹图谱更能全面地反映血府逐瘀口服液的色谱峰信息, 并且相似度结果差异明显. 该方法信息量大, 中药的整体性、宏观性及复杂性分析相适应.     

Metal-free synthesis of 1,2-amino alcohols by one-pot olefin aziridination and acid ring-opening

A one-pot, two-step reaction comprising olefin aziridination and ring-opening of an aziridine intermediate to synthesize 1,2-amino alcohols has been developed. This reaction is suitable for several types of olefin. This methodology allows an efficient and highly stereoselective approach to various 1,2-amino alcohols, readily providing an alternative route to conventional vicinal amino alcohols.     

Stereoselective synthesis of 2,2-bis(C-branched-chain) glucopyranosid-3-ulose via autoxidation reaction

Many different approaches for synthesis of branched chain sugars have beenestablished,1 because they are very useful intermediates for synthesis of other non-sugar chiralmolecules, and usually occur in nature. Branched chain glycosidulose can be used for construction offive- and six-membered carbocyclic rings to which two chiral carbons of sugar are incorporated byintramolecular aldol condensation and Robinson annulation,2 Therefore they are useful in thesynthesis of natural products which consist of annulated carbohydrates or where a highlyfunctionalised enantiomerically pure cyclopentane or cyclohexane is required. Also, this type ofbranched chain sugar can be considered as the synthons of monoterpenoid natural products of theiridoid class which have the cyclopentan-(c)-pyran structure. In view of the importance of branchedchain glycosiduloses, it is desirable to have a general, convenient methodology to their synthesis.However, none of the literature methods was reported on their synthesis by a nuclephilic addition toa partially protected glycosidulose, due to the fact that these glycosiduloses are very difficult tosynthesize selectively and unstable;3 and what is more, one-step synthesis branched chainglycosidulose using this method is almost impossible.In this paper, we report on a general, convenient method for stereoselective syntheses of2,2-bis(C-branched-chain)glucopyranosid-3-uloses by the new reaction of 1 with various activemethylene compounds. The generality of this method was examined in detail. The optimumtemperature was 18-25℃. The solvent DMF was better than the others. In all cases he yields werehigher than 60%.All the 2,2-bis(C-branched-chain)glucopyranosid-3-uloses were characterized by X-raycrystallographic analyses. In addition, the important iintermediate in this reaction was isolated,which is the product of autoxidation of 1 at C-3 position. Thus the reaction mechanism for thesynthesis of 2,2-bis(C-branched-chain) glucopyranosid-3-uloses can be rationalized by autoxidationof 1 followed by 1,4-Michael addition of various carbanions as the main steps.     

冬凌草甲素葡萄糖苷的合成

为研究冬凌草甲素的构效关系,合成生物活性更高的化合物,以冬凌草甲素为先导化合物,通过对其进行选择性保护,再进行糖苷化,最后脱保护,经五步反应,以23.0%的总收率,合成了冬凌草甲素-6-O-β-D-葡萄糖苷,并得到一系列冬凌草甲素衍生物,它们的结构经IR,1H NMR,MS和元素分析确证.     

A New Autoxidation-Michael Addition of a Glycoside Lactone Derivative

C-branched chain glycopyranosiduloses are very efficient chiral building blocks for synthesis of biologically active substances, containing carbocyclic ring systems. Synthesis of such type of structural units has accordingly gained importance in recent years.[1]     

电导研究贵金属Pt在Co3O4还原过程中的作用

通过考察Co3O4在还原过程中电导率的变化, 并结合程序升温还原方法, 对贵金属Pt的作用进行了研究. 另外, 研究了Co3O4在氢气、氧气和合成气气氛中电导率的连续变化过程, 以便进一步了解Co3O4在实际费-托合成反应条件下的氧化-还原历程, 以及贵金属Pt在该过程中的作用.     

Molecular recognition triggered aptazyme cascade for ultrasensitive detection of exosomes in clinical serum samples

Exosomes have attracted widespread interest due to their inherent advantages in tumor diagnosis and treatment monitoring. However, it is still a big challenge for highly sensitive and specific detection of exosome in real complexed samples. Herein, a molecular recognition triggered aptazyme cascade strategy was developed for ultrasensitive detection of cancer exosomes in clinical serum samples. In this design, one target exosome could capture a large quantity of aptazymes for the first-step signal amplification. And then the captured aptazyme was activated and recycled to release the fluorophore-labelled substrate strand for a cascaded signal amplification. Notably, the activation of aptazyme only occurs when it has bound with target exosome, ensuring a low background. The experimental results show that the limit of detection (LOD) and the limit of quantification (LOQ) are 3.5 × 10³ particles/μL and 1.7 × 10⁴ particles/μL, respectively, which is comparable to the results of most existed fluorescence-based exosome probes. Moreover, this assay possesses high specificity to distinguish exosomes derived from other cell lines. Furthermore, this fluorescence probe was utilized in cancer patient and healthy serum samples successfully, suggesting its great potential for clinical diagnosis and biological studies.