NaY分子筛的类固相合成及其晶化机理初探

采用具有液相和固相双向转化机理为主导的类固相体系合成方法,合成了NaY分子筛。采用X射线衍射(XRD)、扫描电镜(SEM)和低温氮气吸附-脱附技术对合成样品进行了表征。结果表明,合成的NaY分子筛结晶好、无杂晶、晶粒规整。与普通水热合成体系相比,类固相体系合成方法具有投入产出比高、硅/铝比高、单釜产率可提高200%的优点。结合合成过程中的影响因素,初步探索了类固相体系合成NaY分子筛的晶化机理。

类固相法快速合成小颗粒方沸石的研究

为解决传统水热法合成方沸石工艺存在晶化时间长、体系水含量大等弊端,采用类固相法以硅铝干凝胶为硅源和铝源、氢氧化钠为碱源,进行了快速合成小颗粒方沸石的研究,并通过X射线衍射(XRD)、扫描电镜(SEM)、红外光谱分析(FRIR)、激光粒度分析等手段对合成产品进行了表征分析。结果表明,当晶化时间t=8 h,晶化温度T=150℃,硅铝干凝胶的摩尔组成n(SiO2)/n(Al2O3)=5,晶化体系物料摩尔组成n(Na2O)/n(SiO2)=0.26,n(H2O)/n(SiO2)=11.10时,可合成出形貌均一、结晶良好的小颗粒方沸石,其粒径大小主要集中在0.1~20mm。与传统水热法相比,该方法极大地减少了合成过程的用水量,缩短了晶化时间,缩小了产品粒度,从整体上优化了方沸石的合成工艺。

吸附在活性炭上的二氧六环类固相和类液相性质的NMR研究

物理吸附在活性炭上的有机分子的性质,一直是人们感兴趣的问题。近年来,人们开始用NMR梯度场和核弛豫的方法,研究活性炭上吸附分子的扩散运动和分子交换运动.由于吸附分子在活性炭上处于不同的状态,其核弛豫表现出快、慢两个过程。通过拟合磁化矢量随时间变化的曲线,可以得到不同状态分子的百分含量。本文采用核弛豫的方法,研究活性炭的表面酸性基团及孔径对被吸附的二氧六环(DO)类固相和类液相形成的影响.并对不同吸附量下,DO在活性炭上的吸附行为进行讨论。

类固相法快速合成高钙镁离子交换性能的P型分子筛

以硅铝干凝胶为硅源和铝源,氢氧化钠为碱源,采用类固相法快速合成了P型分子筛,并通过X射线衍射(XRD)、扫描电镜(SEM)等手段对产品进行了表征分析。结果表明,硅铝干凝胶的组成nSiO2/nAl2O3=5,晶化时间和晶化温度分别为3 h、140℃,原料的组成nNa2O/nSiO2=0.26、nH2O/nSiO2=18.51时,可制备形貌均一、结晶良好的P型分子筛产品。与传统水热法相比,该方法极大地减少了合成过程的用水量,缩短了晶化时间,提高了产品的钙镁离子交换性能,从整体上优化了P型分子筛的合成工艺。

ZSM-5分子筛的类固相体系合成及其晶化机理初探

采用具有液相和固相双相转化机理为主导的类固相体系分子筛合成方法，合成了ZSM-5分子筛。采用X射线衍射（XRD）、扫描电镜（SEM）和低温氮气吸附-脱附技术对合成样品进行了表征，结果表明，该体系合成的ZSM-5分子筛相对结晶度高，无杂晶，晶粒规整，具有高的比表面积和孔容，并呈现多级分布的孔道结构。与常规方法合成样品相比，具有合成周期短、投入产出比高、单釜产率可提高300％的优点。结合实验过程对类固相体系合成ZSM-5沸石的晶化机理进行了初步探索。

类固相法合成具有片状形貌的ZSM-5分子筛

采用类固相合成法,在H_2O/SiO_2摩尔比为0.5~1.0的条件下,采用高压喷雾混合技术,合成了具有片状结构形貌的ZSM-5分子筛,解决了类固相合成体系中,由于水含量较低,固、液两相混合不均匀的问题。结果表明,在形貌方面,ZSM-5分子筛晶粒形状不规则,表面粗糙,具有片层结构形貌;在孔结构方面,ZSM-5分子筛比表面积为405m^2/g,孔体积为0.37cm^3/g,具有多级孔分布的特点。研究了合成条件对ZSM-5分子筛性能的影响,Na_2O/SiO_2摩尔比为0.03~0.13时均能合成出ZSM-5分子筛,当复合表面活性剂P与SiO_2摩尔比为0.036、晶化时间为20h时,ZSM-5分子筛结晶度最高达到112%。研究了晶化过程中水的作用,水主要以水蒸气形态存在,水蒸气主要起到传热作用。合成的ZSM-5分子筛具有较好的柴油加氢异构降凝性能,当柴油凝点降至-35℃时,柴油收率达到95.50%,具有较高的柴油收率,同时产品性质较好。

类固相法合成ZSM-22沸石及其结构特点

以固体硅胶为硅源,采用类固相法合成了ZSM-22沸石,考察了硅源、晶种、碱硅比、晶化温度、晶化转速等合成条件对ZSM-22沸石的影响,并对晶化过程进行表征分析。结果表明:在原料摩尔比n(KOH):n(Al_(2)O_(3)):n(SiO_(2)):n(H_(2)O):n(DAH):n(seed)=(0.150~0.180):0.012 5 000:1 000:(5.100~7.900):0.300:0.068、晶化温度为443 K、时间为16 h、晶化转速为20 r/min的条件下,可以获得具有高结晶度的ZSM-22沸石。与传统水热法相比,类固相合成法的水硅比,晶化时间大幅减低,投料固含量、单釜收率显著提高,类固相法合成的样品在酸分布和孔结构方面明显不同。

人类线粒体肌酸激酶的固定化及酶学性质研究

目的人源肌酸激酶uMtCK具有良好的催化肌酸生成磷酸肌酸的活性,开发固定化uMtCK酶法生成磷酸肌酸,实现其工业化应用价值。方法将异源表达的uMtCK固定在纳米磁性材料Fe3O4@Histidine-Ni上,制备固定化酶Fe3O4@Histidine-Ni/uMtCK,并进行催化反应。与游离酶uMtCK比对酶学性质和动力学参数,测定固定化酶Fe3O4@Histidine-Ni/uMtCK的重复使用次数。结果与游离酶uMtCK相比,固定化酶Fe3O4@Histidine-Ni/uMtCK的最适反应温度提高5℃,最适pH降低0.5个单位,在50℃、pH7.5下孵育2h,残余酶活为51%,而游离酶仅为27%;uMtCK的KmCr为10.7mmol/L,为Fe3O4@Histidine-Ni/uMtCK的1.1倍;Fe3O4@Histidine-Ni/uMtCK的kcat/KmCr值是5.3L/(mmols),是uMtCK的1.3倍;Fe3O4@Histidine-Ni/uMtCK在经历9次循环使用后,活力还能保持50%以上,显示了良好的稳定性和重复使用性。结论与uMtCK相比,Fe3O4@Histidine-Ni/uMtCK具有良好的热稳定性和重复使用性,具有一定的工业化价值。

固定无花果蛋白酶制备可溶性肽的研究

将 Sephadex G-200与β-硫酸酯乙砜基苯胺(SESA)首先醚化制备对氨基苯砜乙基交联葡聚糖(ABSE-Sephadex G-200),然后经重氮化固定无花果蛋白酶。固定化酶的活力回收达69%。苯甲酰-DL-精氨酰-β-蓁胺(BANA)对该酶固定化过程中的活性变化有保护作用。天然酶与固定化酶都具有良好的耐热性,在59～60℃,80min,活性均无明显下降;在69～70℃,80min 固定化酶较天然酶更稳定。用 BANA 为底物,在半胱氨酸存在下,测定了两种形式酶的动力学性质。在 pH7.7的磷酸盐缓冲系统中,37℃天然无花果蛋白酶的 Km=0.32m-mol/L;在间歇振摇下固定化酶的表观 Km′=1.02mmol/L。最适 pH 无明显改变,均为7.7。

固相肽类合成的发明者:梅里菲尔德

固相肽类合成(SPPS)是一个在固体支持物上进行化学转化以合成肽类和蛋白质的化学过程。固相肽类合成最早由罗伯特.梅里菲尔德1959年构思,1963年开始应用,1965年设计出自动肽类合成仪原型。应用固相肽类合成法,梅里菲尔德先后合成了缓激肽、血管紧张素、催产素和胰岛素等大量蛋白质,尤其是1969年完成了核糖核酸酶A(124氨基酸构成)的化学全合成。固相肽类合成法还被广泛应用于寡聚核苷酸和多糖的合成,成为遗传学和生物化学研究的基本技术之一。由于在固相化学合成方法学发展方面的贡献,梅里菲尔德获得了1984年诺贝尔化学奖。本文介绍了梅里菲尔德的生平和SPPS的发明以理解梅里菲尔德的原创性贡献。

基于粒子吸附层的纳米流体有效导热系数模型

基于纳米粒子表面吸附层的分析,构建包含纳米粒子、分散剂层、类固相层和分散基液的导热单元,利用最小热阻法建立纳米流体的有效导热系数模型,推导出其表达式,并分别讨论纳米粒子粒径、分散剂层和类固相层对纳米流体的有效导热系数的影响。结果表明,考虑类固相层的影响得到的纳米流体的有效导热系数比不考虑其影响得到的数值大;添加分散剂后,纳米流体的有效导热系数随着分散剂导热系数的增大而增大,当纳米粒子较小时分散剂在纳米粒子表面的吸附层对纳米流体导热系数的影响更大。

同构为美——中国古代美学关于美的心理本质的界说

中国古代美学资料说:“同声相应,同气相求。”“物固以类相召。”人性“爱同憎异”,“会己则嗟讽,异我则沮弃。”这些是异质同构为美思想的明确注脚;也是中国古代关于美的心理本质的固有思想。它与西方美学异质同构为美的思想异曲同工。究其成因,渊源于中国古代“天人合一”的文化模式。

气、阴阳学说与天人感应

谈天人感应者必谈董仲舒,而论董仲舒者亦往往要说及天人感应的问题,久而久之,天人感应的思想,几为董仲舒专有。其实,这种联系过于简单,使人忽略了天人感应思想在中国古代思想史中的重要理论价值。有人认为,由“天人合一”、“情景合一”、“知行合一”三个命题可推衍出中国古代哲学的完整范畴体系。这种观点能否成立尚待进一步讨论,但其中提及的两个重要命题——“天人合一”、“情景合一”,却都与天人感应有密切关系。

Evaluation of 5 versus 10 granulocyteaphaeresis sessions in steroid-dependent ulcerative colitis: A pilot, prospective, multicenter, randomized study

AIM： To evaluate the efficacy of 5 compared to ：tO granulocyteaphaeresis sessions in patients with active steroid-dependent ulcerative colitis. METHODS： In this pilot, prospective, multicenter randomized trial, 20 patients with moderately active steroid-dependent ulcerative colitis were randomized to 5 or 10 granulocyteaphaeresis sessions. The primary objective was clinical remission at wk 17. Secondary measures included endoscopic remission and steroid consumption.RESULTS： Nine patients were randomized to 5 granulocyteaphaeresis sessions （group 1） and 11 patients to 10 granulocyteaphaeresis sessions （group 2）. At wk 17, 37.5% of patients in group 1 and 45.45% of patients in group 2 were in clinical remission. Clinical remission was accompanied by endoscopic remission in all cases. Eighty-six percent of patients achieving remission were steroid-free at wk 17. Daily steroid requirements were significantly lower in group 2. Eighty-nine per cent of patients remained in remission during a one year follow-up. One serious adverse event, not related to the study therapy, was reported. CONCLUSION： Granulocyteaphaeresis is safe and effective for the treatment of steroid-dependent ulcerative colitis. In this population, increasing the number of aphaeresis sessions is not associated with higher remission rates, but affords a significant steroid-sparing effect.

Microwave Extraction Followed by Solid-phase Extraction for the Determination of Phthalate Esters in Fish Samples by Gas Chromatography

A new analytical procedure based on solid-phase extraction method coupled to GC-FID has been developed and validated for the determination of five phthalate esters （PAEs） （dimethyl-（DMP）, diethyl-（DEP）, di-n-butyl-（DBP）, di-2-ethylhexyl- （DEHP）, di-n-octyl-（DOP）） in fish samples. There was a good linear relationship in the range of 0.05-10μg with the detection limits of 0.09-0.16ng .The recoveries obtained for PAEs ranged from 88.6% to 96.4%with RSD of 4.2%-10.2%.The applicability of the developed method was demonstrated for real fish samples.

Measurement and Correlation for Solubility of Adipic Acid in Several Solvents

Using a laser detecting system, solubility data were measured for adipic acid dissolved in six pure solvents, namely, cyclohexanone, cyclohexanol, acetic acid, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethylsulfoxide at the temperature range from 293.15K to 353.15K. All these data were regressed by 2h, NRTL, Wilson, and the modified Wilson models. For the study of six, 2h, NRTL, and the modified Wilson models were found to provide an accurate mathematical representation of the experimental results, with overall average absolute relative deviations between measured and calculated values as 1.74%, 2.06%, and 3.06%, respectively. The results showed that the λh model is the most suitable for description of the solid-liquid equilibrium containing adipic acid.

Association between polycyclic aromatic hydrocarbons and human rectal tumor or liver cancer

Objective: The aim of this study was to investigate the effect of polycyclic aromatic hydrocarbons (PAHs) in rectal carcinoma and hepatocarcinoma genesis. Methods: The PAHs in the human rectal cancer and liver cancer tissues, the adjacent tissues and homologous tissues without rectal cancer or liver cancer were extracted by ultrasonic wave. The extracts were then cleaned up and enriched by solid phase extraction, analyzed by high performance liquid chromatography (HPLC) with fluorescence spectroscopy. Results: Four kinds of PAHs were detected in human rectal and hepatic tissues. The contents of pyrene, 2-methylanthracene and benzo (a) pyrene in both rectal cancer tissues and adjacent homologous tissues were higher than rectal tissues without rectal cancer, the differences were statistically significant (P < 0.05). The contents of phenanthrene in the three kind of tissue were not significant (P > 0.05). The differences of the content of each PAHs between rectal cancer and adjacent tissue were not significant (P > 0.05). The contents of the four PAHs in the three kinds of liver tissues were not statistically significant (P > 0.05). Conclusion: PAHs are found in human rectal tissues or hepatic tissues. The contents of PAHs in human rectal tissue may have an effect on the occurrence of human rectal cancer while the contents of PAHs in human hepatic tissues may have not ones.

Chemical synthesis of a cyclotide via intramolecular cyclization of peptide O-esters

Cyclotides constitute a fascinating family of circular proteins containing ca.30 amino acid residues.They have a unique cyclic cysteine knot topology and exhibit remarkable thermal,chemical and enzymatic stabilities.These characteristics enable them to have a range of biological activities and promising pharmaceutical and agricultural applications.Here,we present a practical strategy for the chemical synthesis of cyclotides through the intramolecular ligation of fully unprotected peptide O-esters.This strategy involves the mild Fmoc solid-phase peptide synthesis of the peptide O-ester backbone,the head-to-tail cyclization of the cyclotide backbone by native chemical ligation,and the oxidative refolding to yield the natural knot protein.The simplicity and high efficiency of the strategy can be employed in the synthesis of artificial cyclotides for pharmaceutical applications.

Synthesis of two substrate mimics of thioesterase in the biosynthesis of cyclic depsipeptide WS9326A

WS9326 A is a tachykinin receptor antagonist and quorum sensing inhibitor discovered from several Streptomyces strains.The structure of WS9326 A features a(Z)-pentenylcinnamoyl moiety attached on a cyclic depsipeptide skeleton,which is biosynthesized by nonribosomal peptide synthetases(NRPS).The regioselective cyclization in the last step of NRPS catalysis,which is proposed to be catalyzed by a thioesterase(TE)domain in the last module,has not been experimentally characterized.We here report the synthesis of two substrate mimics(1 and 2)of the TE(WS9326 A-TE)in WS9326 A biosynthesis,by using Fmoc-based solid-phase peptide synthesis(SPPS)method.Compounds 1 and 2 are new compounds whose structures have been elucidated based on NMR and HRESIMS analyses.The N-terminal cinnamoyl moiety and C-terminal methylated L-Ser moiety in 2 were incorporated under the mild SPPS conditions.Given the isolation difficulties of substrate of WS9326 A-TE from the Streptomyces producers of WS9326 A,our synthesis of 1 and 2 set the stage for the reconstitution of WS9326 A-TE’s catalytic reaction in vitro in the future.

A new class of HIV-1 inhibitors and the target identification via proteomic profiling

Anti-HIV screening with the MT-4/MTT assay on a focused library of structurally diverse natural products has led to the discovery of a group of steroids with potent activities, which include four new ergostane-type steroids, named amotsterols A-D （1-4）, together with two known analogs. Among them, the most potent amotsterol D （4） exhibited anti-HIV activity against wild- type and some clinically relevant multidrug resistant HIV-I strains. Subsequent studies on its target identification through a proteomic approach found that compound 4 might target PKM2, a rate limiting enzyme ofglycolysis, in host cells to restrict HIV replication. The docking model of compound 4 to PKM2 showed that the two hydroxyl groups of 4 form hydrogen bonds with the two parallel Y390 in each subunit of PKM2 separately, and the ring C of 4 is sandwiched between the two parallel aromatic rings ofF26. The identified hit compound may have the potential to be further developed as a novel anti-HIVagent. These results demonstrated that an integrated approach, which combines new chemical structures and phenotypic screening with a proteomic approach, could not only identify novel HIV-1 inhibitors, but also elucidate the unknown targets of compound interactions in antiviral drug discovery.