The effect of Rh particle size on the catalytic performance of porous silica supported rhodium catalysts for CO hydrogenation

Silica-supported Rh catalysts with different Rh particle dimensions were investigated for CO hydrogenation. The catalysts were characterized by various techniques such as TEM, H-2-TPR and N-2 adsorption to study the catalyst morphology, the size distributions of Rh particles and the silica pores. It was found that the distribution and the size of Rh particles were affected by the silica pores, and the metal grains were enclosed in the pores of the support, and thereby their growth was limited. The catalytic activity and selectivity to C-2-oxygenates for CO hydrogenation were found to be significantly controlled by the Rh particle sizes, and the higher activity and selectivity to C2-oxygenates were obtained over bigger Rh particles, within the range of the reported particle sizes.

抗癌药长春新碱及其与微管蛋白相互作用的电化学研究

在0.05 mol/L Tris，0.15 mol/L NaCl溶液中，用吸附伏安法研究长春新碱(VCR)，其峰电位在-1.68 V(vs. Ag/AgCl)，峰电流与1.0*10^{-8}～2.0*10^{-7}mol/L VCR浓度成正比，检测限为7.0*l0^{-9} mol/L，用常规脉冲极谱法、线性扫描和循环伏安法等研究该体系的电化学行为，实验表明，电极还原过程为具有吸附特征的不可逆过程。VCR的吸附符合Frumkin吸附等温式。也研究了VCR与微管蛋白的相互作用。实验表明，VCR与微管蛋白形成一电活性的结合物，这一结合物具有吸附性，且还原过程也为不可逆过程。

Quantum and variational monte-carlo interaction potentials for li2 (x1-sigma-g+)

Optimized trial functions are used in quantum Monte Carlo and variational Monte Carlo calculations of the Li₂(X ¹Σ⁺_g) potential curve. The trial functions used are a product of a Slater determinant of molecular orbitals multiplied by correlation functions of electron—nuclear and electron—electron separation. The parameters of the determinant and correlation functions are optimized simultaneously by reducing the deviations of the local energy E_L (E_L  Ψ⁻¹_THΨ_T, where Ψ_T denotes a trial function) over a fixed sample. At the equilibrium separation, the variational Monte Carlo and quantum Monte Carlo methods recover 68% and 98% of the correlation energy, respectively. At other points on the curves, these methods yield similar accuracies.

Direct observation of adsorption sites of protein impurities and their effects on step advancement of protein crystals

We measured noninvasively step velocities of elementary two-dimensional (2D) islands on {110} faces of tetragonal lysozyme crystals, under various supersaturations, by laser confocal microscopy combined with differential interference contrast microscopy. We studied the correlation between the effects of protein impurities on the growth of elementary steps and their adsorption sites on a crystal surface, using three kinds of proteins: fluorescent-labeled lysozyme (F-lysozyme), covalently bonded dimers of lysozyme (dimer), and a 18 kDa polypeptide (18 kDa). These three protein impurities suppressed the advancement of the steps. However, they exhibited different supersaturation dependencies of the suppression of the step velocities. To clarify the cause of this difference, we observed in situ the adsorption sites of individual molecules of F-lysozyme and fluorescent-labeled dimer (F-dimer) on the crystal surface by single-molecule visualization. We found that F-lysozyme adsorbed preferentially on steps (i.e., kinks), whereas F-dimer adsorbed randomly on terraces. Taking into account the different adsorption sites of F-lysozyme and F-dimer, we could successfully explain the different effects of the impurities on the step velocities. These observations strongly suggest that 18 kDa also adsorbs randomly on terraces. Seikagaku lysozyme exhibited a complex effect that could not alone be explained by the two major impurities (dimer and 18 kDa) present in Seikagaku lysozyme, indicating that trace amounts of other impurities significantly affect the step advancement.

A pseudo-spin model for the wall of cytoskeletal microtubule

A pseudo-spin model is intended to describe the physical dynamics of unbound electrons in the wall of cytoskeletal microtubule (MT). Due to the inherent symmetry of the structure and the electric properties in the MT, one may treat it as a one-dimensional ferroelectric system, and describe the nonlinear dynamics of dimer electric dipoles in one protofilament of the MT by virtue of the double-well potential. Consequently, the physical problem has been mapped onto the pseudo-spin system, and the mean-field approximation has been taken to get some physical results.

Quantum information processing in the wall of cytoskeletal microtubules

Microtubules (MT) are composed of 13 protofilaments, each of which is a series of two-state tubulin dimers. In the MT wall, these dimers can be pictured as "lattice" sites similar to crystal lattices. Based on the pseudo-spin model, two different location states of the mobile electron in each dimer are proposed. Accordingly, the MT wall is described as an anisotropic two-dimensional (2D) pseudo-spin system considering a periodic triangular "lattice". Because three different "spin-spin" interactions in each cell exist periodically in the whole MT wall, the system may be shown to be an array of three types of two-pseudo-spin-state dimers. For the above-mentioned condition, the processing of quantum information is presented by using the scheme developed by Lloyd.

Evolution of different oligorneric glycyl-tRNA synthetases

There are two oligomeric types of glycyl-tRNA synthetases (GlyRSs) in genome, the alpha(2)beta(2) tetramer and alpha(2) dimer. Here, we showed that the anticodon-binding domains (ABDs) of dimeric and tetrameric GlyRSs are non-homologous, although their catalytic central domains (CCDs) are homologous. The dimeric GlyRS_ABD is fused to the C-terminal of CCD in alpha-subunit, but the tetrameric GlyRS_ABD is to the C-terminal in beta-subunit during evolution. Generally, one species only contains one oligomeric type of GlyRS, but the both oligomeric GlyRSs with the multiple homologous domains can be observed in Magnetospirillum magnetotacticum genome, nevertheless, these homologous domains are probably from different genomes. (C) 2005 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

SECRETORY MONOCLONAL IGA ANTIBODY TO HUMAN SPERM PRODUCED BY GASTROINTESTINAL IMMUNIZATION INHIBITS HUMAN SPERM ACTIVITY AND MOUSE INVITRO FERTILIZATION

BALB/c mice were immunized intragastrically with human sperm. Cells from the Peyer's patches and spleens of the immunized mice were for the preparation of hybridomas secreting antisperm monoclonal IgA (mcIgA). The specific ratio of IgA-secreting cells in Peyer's patches was much higher than that in spleen. The binding site on human sperm of 9 of 19 mcIgA was in the post-acrosomal region using an immunofluorescent assay. Two of eight selected mcIgA caused strong human sperm agglutination and three of them produced significant inhibition of mouse in vitro fertilization. No mcIgA tested caused obvious human sperm immobilization or inhibited mouse in vivo fertilization. In vitro assembly of selected mcIgA in ascites with mouse secretory component (SC) caused no significant changes in effects on sperm function and in vitro fertilization. By use of Western blotting, dimer or higher polymers were demonstrated in all selected mcIgAs and corresponding protein antigens in 6 of 8 selected mcIgAs. These results suggest that human sperm function may be inhibited and fertilization rate reduced by specific secretory IgA to human sperm and that secretory immunity to protein antigens of human sperm could be induced by intragastrointestinal immunization.

Interaction between human interleukin-16 and CD4 receptor of HIV-1

AIM: To study the interaction between human interleukin-16 (IL-16) and the receptor CD4 (T-lymphocyte differentiation antigen) of human immunodeficiency virus type 1 (HIV-1). METHODS: Two structurally con served regions (SCRs) of human IL-16 were built by the SYBYL/Biopolymer module using the corresponding transmembrane (TM) domain of human interleukin-1 (HIL-4) and HIL-2 as the templates. The coordinates for amino-terminal residue sequence, carboxyl-terminal residue sequences, and cytoplasm loops were generated using Biopolymer's LOOP SEARCH algorithm. RESULTS: HIL-16 first formed a homodimer, then contacted with CD4 dimer further forming a dimeric complex. Subsequently, the dimeric complex constructed the tetrameric complex by two disulfide bridges between the cysteines of HIL-16 (Cys31-Cys31). CONCLUSION: The interaction model is useful to propose the action mechanism of HIL-16 and is beneficial for rational designing of novel anti-HIV drugs.

Identification of novel SINEs from Cyprinidae and their evolutionary significance

Short interspersed nuclear elements (SINEs) are widespread among eukaryotic genomes. They are repetitive DNA sequences that have been amplified by retrotransposition. In this study, a class of SINEs were isolated from the Opsariichthys bidens genome, and named Opsar. Sequence analysis confirmed that Opsar is a new class of typical SINEs derived from tRNA molecules. With the tRNA-derived region of Opsar and through BLASTN search, we further identified Zb-SINEs from the zebrafish genome, which includes two groups: Zb-SINE-A and Zb-SINE-B. The Zb-SINE-A group comprises subfamilies of -Al--A5, and the Zb-SINE-B group is a dimer of the tRNA(Ala)-derived region and shares a similar dimeric composition to Alu. Zb-SINEs are composed of three distinct regions: a 5 end tRNA-derived region, a tRNA-unrelated region and a 3 end AT-rich region. The flanking regions are AT rich. The average length of Zb-SINEs elements is about 340 6p. Zb-SINEs account for as much as 0.1% of the whole zebrafish genome. About 70% of the Zb-SINEs are on chromosomes 11, 18, and 19. These Zb-SINEs were characterized by PCR and dot hybridization. The distribution pattern of Zb-SINEs in genome strongly supports the master genes model. The tRNA-derived regions of Opsar and Zb-SINEs were compared with the tRNA(Ala) gene, and they showed 76% similarity, indicating that Opsar and Zb-SINEs originated from an inactive tRNA(Ala) sequence or a tRNA(Ala)-like sequence. In view of the evolutionary status of zebrafish in the Cyprinidae, we deduced that Zb-SINEs were a very old class of interspersed sequences.

Possible origin of ferromagnetism in undoped anatase TiO2

Using first-principles electronic structure calculations we find that the titanium vacancy and divacancy may be responsible for the unexpected ferromagnetism in undoped anatase TiO2. An isolated titanium vacancy produces a magnetic moment of 3.5 mu(B), and an isolated titanium divacancy produces a magnetic moment of 2.0 mu(B). The origin of the collective magnetic moments is the holes introduced by the titanium vacancy or divacancy in the narrow nonbonding oxygen 2p(pi) band. At the center of the divacancy, an O-2 dimer forms during the relaxation, which lowers the total energy of the system and leads to the decrease in the total magnetic moment due to a hole compensation mechanism. For both the two native defects, the ferromagnetic state is more stable than the antiferromagnetic state.

INVESTIGATION OF THE GROWN DIAMOND (100) SURFACE USING HIGH-RESOLUTION ELECTRON-ENERGY LOSS SPECTROSCOPY

The diamond (100) facets deposited at initial 1.0% CH4 have been investigated using high resolution electron energy loss spectroscopy (HREELS). The diamond (100) facets grown at 800-degrees-C are terminated by CH2 radicals, and there is no detectable frequency shift compared with the characteristic frequencies of molecular subgroup CH2. Beside the CH2 vibration loss, CH bend loss (at 140 meV) of locally monohydrogenated dimer is detected for the diamond (100) facets grown at 1000-degrees-C. Dosing the (100) facets grown at 800-degrees-C with atomic hydrogen at 1*10(-6) mbar, the loss peak at 140 meV appears. It is suggested that there are enough separately vacant sites and uniformly dispersed monohydrogenated dimers on (100) facets. This structure relaxes the steric repulsion between the adjacent hydrogen atoms during the diamond (100) surface growth.

The role of hydrogen in semi-insulating INP

Complexes of vacancy at indium site with one to four hydrogen atoms and isolated hydrogen or hydrogen dimer and other infrared absorption lines, tentatively be assigned to hydrogen related defects were investigated by FTIR. Hydrogen cam passivate imperfections, thereby eliminating detrimental electronic states from the energy bandgap. Incorporated hydrogen can introduce extended defects and generate electrically-active defects. Hydrogen also can acts as an actuator for creating of antistructure defects. Isolated hydrogen related defects(e.. H-2*) may play an important role in the conversion of the annealed wafers from semiconducting to the semi-insulating behavior. H-2* may be a deep donor, whose energy level is very near the iron deep acceptor level in the energy gap.

中药射干的化学成分研究

本学位论文由4章组成。第一章是论文的主体，报道了中药射干的化学成分研究。第二章是中药射干代用品川射干的化学成分研究，并附带报道了西番莲化学成分的研究结果。第三章是射干、川射干及西番莲提取物化学成分串联质谱分析的报道。第四章为综述，概述了射干及鸢尾属植物的化学成分和药理研究进展。 在第一和二章中分别报道了射干（Belamcanda chinensis (L.) DC.）、川射干 （Iris tectorum Maxim.）及西番莲（Passiflora incarnate L.）化学成分的分离纯化与结构鉴定。采用正、反相硅胶柱层析、凝胶柱层析、薄层制备及HPLC等各种分离方法，从三种药用植物中共分离出68个不同的化合物，其中61个的结构得 得以鉴定，另外4个化合物的结构正在鉴定中，3个由于量少且有点杂质未作进一步的鉴定。 中药射干（Rhizoma Belamcandae）为射干植物的干燥根茎，从中共分离出53个化合物，通过红外、质谱及核磁共振等波谱方法鉴定了包括12个新化合物在内的48个，结构类型分别属于iridal型三萜及其新颖的二聚体、异黄酮、黄酮及黄酮醇、香豆素、甾体、芳香酸和脂肪酸及其甘油酯等。新化合物中有两个异黄酮类化合物，其结构分别鉴定为5,7,8,4′-四羟基-6-甲氧基异黄酮和5,6-二羟基-4′-甲氧基异黄酮-7-O-β-D-吡喃葡萄糖苷；八个新的iridal型三萜化合物分别鉴定为鸢尾烯（L）、16-甲氧基鸢尾烯、16-去羟基鸢尾烯、2-(E)-16-去羟基鸢尾烯、16-去羟基鸢尾烯B、3-乙酰基-16-去羟基鸢尾烯、iristectoroneL和iristectoroneM；两个结构骨架新颖的双三萜，分别命名为射干素A和射干素B，其分离纯化的困难以及结构的新颖和复杂突显出该论文的科学意义。除这些新化合物外，还有9个已知化合物为首次从中药射干中分离得到。此外，从中药射干的代用品川射干中分离得到7个已知化合物，主要是黄酮类成分及iridal型三萜化合物，其中1个三萜化合物为从射干中分离鉴定的新成分。另外还从西番莲中分离出8个化合物，鉴定了其中的6个，主要为黄酮碳苷。 第三章是关于射干、川射干及西番莲提取物化学成分的ESI-MS-MS分析，在初步探讨了从这些植物中分离鉴定出的一些异黄酮及黄酮碳苷的质谱裂解规律基础上，通过质谱和串联质谱分析，定性和半定量地检测了射干和川射干中主要的异黄酮成分以及西番莲中的黄酮碳苷成分，为这些药材品质的快速鉴定提供了一种简便方法。 第四章概述了射干及鸢尾属药用植物的化学和药理研究进展，特别是对其中异黄酮及三萜类成分的研究进展进行了深入系统的综述。 This dissertation is composed by four chapters. The first and second chapter reports the phytochemical investigation of three medicine plants, Belamcanda chinensis (L.)DC., Iris tectorum Maxim. and Passiflora incarnate L. Sixty eight different compounds were isolated and sixty one of them were identified. The third chapter described rapid ESI-MS-MS analysis of B. chinensis, I. tectorum, and P. incarnate. The forth part is a review about the progress of studies on the chemical constituents from Belamcanda chinensis and Iris species. Fifty-three compounds were isolated from Rhizoma Belamcandae, the rhizomes of B. chinensis by the methods of column chromatography (normal and reversed phase silica gel, Sephadex LH-20), preparative TLC and HPLC. On the basis of spectroscopic methods including IR, ESI-MS, 1-D and 2-D NMR, forty eight of them were identified as seventeen flavonoids, seventeen tritepenoids, one cumarin, five steroids and some benzene derivative etc. Among them, the structures of twelve new compounds were elucidated as 6-methoxy-5,7,8,4′-tetrahydryoxyisoflavoe, 4′-methoxy-5,6-dihydroxyisoflavone-7-O-β-D-glucopyranoside, iristectorene L, 16-methoxyisoiridogermanal, 16-dehydroxyisoiridogermanal, 2-(E)-16-dehydroxy isoiridogermanal, 16-dehydroxyiristectorene B, 3-acetyl-16-dehydroxyisoiridoger- manal, iristectorone L, iristectorone M, belamcandene A and belamcandene B. Last two new compounds are dimer of triterpenoids with a novel carbon skeleton. Beside the new compounds, nine known ones were isolated from this plant for the first time. Isolation of I. tectorum yielded seven compounds. On the basis of spectroscopic methods including ESI-MS, NMR and the comparison with authentic samples, three of them were determined as isoflavone, two of them were triterpenoids, and other two were β-sitosterol and apocynin. All of them are known compounds except one of iridal type triterpenoid, 16-dehydroxyiristectorene B, which also obtained from B. chinensis as a new compound. Isolation of P. incarnate yielded eight compounds. Six of them were determined on the basis of spectroscopic methods including ESI-MS, NMR and the comparison with authentic samples. Four of them are flavone-C-gluconside, and two are steroids. The third chapter describes the tandem mass spectrometry (ESI-MS-MS) analysis of the isoflavonoids from B. chinensis and I. tectorum, as well as C-glycosyl-flavonoide from P. incarnate, in order to explore the rapid methodology of validating the quality of the herbs. In addition, the fractionation rules of some iosflavonoids and C-glycosyl-flavonoids were discussed. The fourth chapter summarizes the research development on chemistry and pharmacology of medicine plants of B.chinensis and Iris species.

Evidence for perimeter sites over SmOx-modified Rh(100) surface by CO chemisorption

SmOx modified Rh(l 0 0) surfaces have been in-situ prepared by depositing metallic Sin and subsequently oxidizing under controlled conditions, and the interaction between the lanthanide oxide and transition metal has been characterized by means of X-ray photoelectron spectroscopy (XPS) and high-resolution electron-energy-loss spectroscopy (HREELS) as well as thermal desorption spectroscopy (TDS). As evidenced, the adsorption of CO on the modified surfaces shows some different features to the original surface of Rh(l 00). The covering of SmOx blocks some sites on the surface and consequently suppresses adsorption of the typical CO species with an uptake at about 500 K, while a novel desorption peak centered at 260 K emerges in the CO TDS. Correspondingly, the XP spectrum exhibits a new C Is peak at 287.9 eV and 0 Is peak at 532.6 eV. The intensity of the low temperature peak varies with the coverage of SmOx, which shows an actual correlation to the perimeter sites of SmOx particles on the surface. (C) 2004 Elsevier B.V. All rights reserved.