INVESTIGATION OF ELECTRONIC SPECTRA OF AZOCOMPOUNDS——ABSORPTION AND EMISSION SPECTRA OF β-NAPHTHOL AZOBENZENE DERIVATIVES

Absorption and emission spectra of eight naphtholazobenzene derivatives are investigated.Absorption processes of n→π~* and π→π~* transition and emission processes from the excitedstates are studied separately in each compound. Intra- and inter-molecular energy transfersfrom the excited states of different chromophores are discussed. Effects of the molecularstructure and the pH value of the solution on the electronic spectra are discussed also. On thebasis of quantum chemistry theory, the spectral data are analyzed qualitatively.     

MONTE CARLO SIMULATION ON AQUEOUS SOLUTION OF BIOLOGICAL MOLECULES——ALANINE SOLUTION

The Monte Carlo simulation is performed for a cluster consisting of a neutral alanine molecule surrounded by 56 water molecules. The average water-water and alanine-water interaction energies are found. The space surrounding the alanine molecule is divided into three regions, where the central atoms are C' atom for the earboxyl group region, N atom for the amino group region and C~β atom for the methyl group region. The water-water and water-alanine interaction energies as functions of the distance between the oxygen atom in a water molecule and the central atom in each region are calculated. In each region the orientational correlation function for the dipole moments of water molecules, the radial distribution function for the oxygen and hydrogen atoms of water molecules are evaluated. In addition, the numbers of water molecules in the first solvation shells of each region and of entire alanine molecule are also counted.     

CENOZOIC VOLCANIC ROCK SERIES IN SOUTHEASTERN CHINA——PETROCHEMISTRY

In this paper, the age, spatial distribution and petrochemistry of Cenozoic volcanic rocks of southeastern China are discussed. They are subalkalic and alkalic. Except for the Pleistocene calc-alkalic volcanic rocks of northern Taiwan and the Late Tertiary tholeiitic rocks of Eastern Coastal Range of Taiwan, the alkalic basaltic rocks form the majority. Only alkalic and strongly alkalic basaltic and ultrabasic volcanic rocks occur in the inland to the west of the Haifeng-Zhenghe-Shangyu fracture zone. It follows that the petrochemical nature of the Cenozoic volcanics studied exhibits a marked trend of variation with time and space, implying that their formation was obviously controlled by the geotectonic setting.     

Crystal and Molecular Structure of N—Phenyl 1—Methoxycarbonylmethyl—3—benzyl—1,2,3,4—tetrahydro—4—oxo—1,3,2—benzodiazaphosphorin—2—thiocarboxamide 2—Oxide

1 INTRODUCTIONOrganophosphorus compounds are ubiquitous in nature and they have broad applications in the fields of agriculture and medicine. During the past two decades, (-ketophosphonates and their derivatives containing sulfur have attracted considerable attention because these compounds are endowed with special physical, chemical and pharmacological properties due to the proximity of the carbonyl and the phosphoryl groups[1～8]. In the study on new pharmacenticals and agrochemicals, th…     

STUDIES ON BIO-ANTIOXIDANTS——MICELLAR EFFECTS ON THE REDUCTION OF NITROXIDES BY VITAMIN C

The kinetics of reduction of nitroxides including 4-hydroxy-TEMPO, 4-methoxy-TEMPOand 4-hexanoyloxy-TEMPO, which are of different lipophilicities, by vitamin C in cationic,non-ionic and anionic micelles, i. e. CTAB, Triton X-100 and SDS, respectively, have beenstudied by ESR spectroscopy by a stopped-flow technique. A mechanism for the reactionconducted in micelles is proposed and the rate constants for the elementary reactions areevaluated. It is found that the rates of single electron transfer reactions involving the ni-troxides are dependent on the nature of the micelle and the lipophilicity of the nitroxide.The rates are increased in CTAB, decreased in SDS, whereas unaffected in Triton X-100.And the greater the lipophilicity of the nitroxide, the more pronounced the rate variation.As high as a 3600-fold increase in the rate was observed for 4-hexanoyloxy-TEMPO in CTABover that in SDS. The micellar effects are rationalized on the basis of analysis of parame-ters and line shape of the ESR spectra for     

STUDIES ON STRUCTURAL-OPTICAL MINERALOGY——EFFECTS OF ELECTRON

In this paper, the Gladstone-Dale ionic refractivities (GDIR values) are calculated onthe basis of the K values given by Mandarino and/or the author. The effects of the elec-tron shell configuration of ions on the refractive properties of minerals are discussed. Theconclusions are as follows: (1) The refractive indices of the compounds consisting of Ne-type ions are linearlyrelated with their densities. (2) The ionic refractivities of the inert gas-type ions are different from those of 18electron-type ions in their variation relationship. (3) The ionic refractivities of ⅠA, ⅡA, ⅢA, ⅣA, ⅤA and ⅥA Groups in the periodictable increase linearly with increasing atomic number. (4) The two-humped curves are found for the ionic refractivities of the first transitionelements. (5) Because of the lanthanum series contraction, the ionic refractivities of rare earthelements decrease with increasing atomic number.     

Dispersion state of CuO on CeO_2——An incorporation model for the interaction between metal oxide and oxide support

XRD and XPS are used to study the dispersion state of CuO on ceria surface.The dispersion capacity values of CuO measured by the two methods are consistent,which are of 1.20 mmol CuO/100 m CeO2.In addition,the results reveal that highly dispersed Cu2 + ions are formed at low CuO loadings and that increasing the CuO content to a value higher than its dispersion capacity produces crystalline CuO after the surface vacant sites on CeO2 are filled.The atomic composition of the outermost layer of the CuO/CeO2 samples has been probed by using static secondary ion mass spectroscopy (SSIMS),and the ratios of Cu/Ce are found to be 0.93 and 0.46 for the 1.22 and 0 61 mmol CuO/CeO2 samples respectively.Temperature-programmed reduction (TPR) profile with two reduction peaks at 156 and 16513 suggests that the reduction of highly dispersed Cu2+ ions consists of two steps and is easier than that of CuO crystallites,in which the TPR profile has only one reduction peak at about 249℃.The above experimental results are in     

Selective Transport of Alkali—Metal Cations through Liquid Membranes by Non—Cyclic Carriers

The emission spectra of a series of naphthalene end-labeled oligo-oxyethylene(N-Pn-N) and their facilitated transport of cations across liquid membranes have been investigated.Alkali-metal cations enhance or inhibit the intramolecular excimer formation of N-Pn-N remarkably,suggesting that the polyether chain of N-Pn-N in solution complexes with the cations,and the orientation of the terminal chromophores depends on the cation size and the length of the polyether chain. These compounds are able to act as carriers to facilitate transport of alkali-metal cations through organic liquid membranes.The transport efficiencies are comparable with those of cyclic carriers such as crown ethers,and show remarkable selectivity.     

NUCLEAR TRANSPLANTATION IN TELEOSTS——HYBRID FISH FROM THE NUCLEUS OF CRUCIAN AND THE CYTOPLASM OF CARP

Hybrid fish are obtained from the combination of nucleus and cytoplasm from two generaof fresh-water teleosts using the technique of nuelear transplantation (i.e. the combination ofthe nucleus of erueian (Carassius auratus) and the cytoplasm of carp (Cyprinus carpio)). Morphological characteristics of these hybrid fish that have been examined so far indicatethat some features such as barbs, pharyngeal teeth, the number of scales along the lateral line,and the number of vertebrae are similar to those of crucian. Some of the hybrid fish growto normal adult fish.     

Phase Transition and Micellization of Temperature Responsive Dextran—graft—poly（N—isopropylacrylamide）Polymers

Phase behavior and micellization of dextran-graft-poly(N-isopropylacrylamide)(PNIPAAm)polymers in aqueous solution are investigated in this paper using DSC and AFM methods.It is found that with the increase of grafting(G%) of the copolymers the endothermic enthalpy during the phase transition increases significantly and the transition temperature decreases slightly.The phase transition behavior of the copolymers is scanning rate dependent.Micelles are formed whenever the solution temperature is raised above the LCST of the copolymers.It is proposed that by using this thermal responsive property of the copolymers,drugs could be incorporated into the micelles without employing any organic solvent.     

胺解改性聚L-谷氨酸苄酯引导骨再生膜的制备

以聚L-谷氨酸苄酯(PBLG)为原料, 通过溶剂浇铸与粒子沥滤法分别构建PBLG单层致密和PBLG单层多孔膜, 利用乙醇胺对薄膜表面改性, 构筑双层引导骨再生膜. 研究了不同胺解改性时间对PBLG-s-PHEG双层膜亲水性和力学性能的影响, 结果表明, 随着PBLG分子量的增大, 薄膜的力学性能增强而降解速率减缓. 延长胺解改性时间可提高薄膜亲水性和体内外降解速率. 细胞实验结果表明, 双层薄膜的致密结构能够有效阻隔成纤维细胞的侵入, 多孔结构能够支持细胞贴壁黏附和铺展. 体外生物活性评价结果表明, 表面改性的PBLG基材料可用于体内骨缺损修复. 本文所构建的双层引导骨再生膜在体外具有良好的力学性能和降解性能, 与组织具有一定的贴合性, 同时可有效阻碍成纤维细胞侵入, 具有潜在应用价值.     

An axial periodic fibrillar arrangement of antigenic determinants for fibronectin and procollagen on ascorbate treated human fibroblasts

Fibronectin and collagens are major constituents of the cell matrix of fibroblasts. Fibronectin is a 220,000 dalton glycoprotein that mediates a variety of adhesive functions of cells examined in vitro. Fibronectin is secreted in a soluble form and interacts with collagen to form extracellular filaments. Fibronectin and procollagen type I were localized using the peroxidase anti-peroxidase method. Under standard culture conditions, fibronectin and procollagen were localized to non-periodic 10 nm extracellular fibrils, the cell membrane and plasma membrane vesicles. Ascorbate treatment of cells leads to a new larger fibril with a diameter of approximately 40 nm. Antibodies to fibronectin and procollagen I react to these native collagen fibrils with an axial periodicity of approximately 70 nm. Fibronectin is clearly associated with native collagen fibrils produced by ascorbate treated cells and there is an asymetric distribution or segregation of fibronectin on these collagen fibrils with a 70 nm axial repeat.     

Metal-phenolic networks modified polyurethane as periosteum for bone regeneration

Treatment of bone defects still poses a great challenge in orthopedic clinics, and the vital role of periosteum in such processes has attracted widespread attention. However, studies focusing on the oxidative stress micro-environment with an artificial periosteum at the site of defect have been scarce. The intrinsic anti-oxidative properties and therapeutic potential for bone defects of metal-phenolic networks(MPNs)have provided a potential solution to this. Herein, we have developed a protocate...     

Micro‐Nanostructures of Cellulose‐Collagen for Critical Sized Bone Defect Healing

Bone tissue engineering strategies utilize biodegradable polymeric matrices alone or in combination with cells and factors to provide mechanical support to bone, while promoting cell proliferation, differentiation, and tissue ingrowth. The performance of mechanically competent, micro‐nanostructured polymeric matrices, in combination with bone marrow stromal cells (BMSCs), is evaluated in a critical sized bone defect. Cellulose acetate (CA) is used to fabricate a porous microstructured matrix. Type I collagen is then allowed to self‐assemble on these microstructures to create a natural polymer‐based, micro‐nanostructured matrix (CAc). Poly (lactic‐co‐glycolic acid) matrices with identical microstructures serve as controls. Significantly higher number of implanted host cells are distributed in the natural polymer based micro‐nanostructures with greater bone density and more uniform cell distribution. Additionally, a twofold increase in collagen content is observed with natural polymer based scaffolds. This study establishes the benefits of natural polymer derived micro‐nanostructures in combination with donor derived BMSCs to repair and regenerate critical sized bone defects. Natural polymer based materials with mechanically competent micro‐nanostructures may serve as an alternative material platform for bone regeneration.     

Nanostructured Materials for Skeletal Repair

The treatment of bone and cartilage defects with bioengineered constructs of artificial scaffolds and autogenous cells became the main challenge of contemporary regenerative medicine. Early defect repair may prevent secondary injury. Recent studies could prove that bone and cartilage cells are sensitive to microscale and nanoscale patterns of surface topography and chemical structure. Nanostructured materials provide an environment for tissue regeneration mimicking the physiological range of extracellular matrix. The article reviews several studies substantiating the superiority of nanostructured materials for bone and cartilage repair along with own results on cell attachment.     

Photothermally Induced Local Dissociation of Collagens for Harvesting of Cell Sheets

The local heating of poly(3,4‐ethylenedioxythiophene) (PEDOT) by a photothermal effect directed by near‐infrared (NIR) light induces unfolding of absorbed collagen triple helices, yielding soluble collagen single‐helical structures. This dissociation of collagens allowed the harvesting of a living idiomorphic cell sheet, achieved upon irradiation with NIR light (λ=808 nm). The PEDOT layer was patterned and cells were successfully cultured on the patterned substrate. Cell sheets of various shapes mirroring the PEDOT pattern could be detached after a few minutes of irradiation with NIR light. The PEDOT patterns guided not only the entire shape of the cell sheets but also the spreading direction of the cells in the sheets. This photothermally induced dissociation of collagen provided a fast non‐invasive harvesting method and tailor‐made cell‐sheet patterns.     

Enhanced critical-sized bone defect repair efficiency by combining deproteinized antler cancellous bone and autologous BMSCs

Previously we have demonstrated that calcinated antler cancellous bone(CACB)has great potential for bone defect repair,due to its highly similar composition and architecture to natural extracellular bone matrix.This study is aiming at seeking for an optimal strategy of combined application of CACB and bone marrow mesenchymal stem cells(BMSCs)in bone defect repair.In vitro study demonstrated that CACB promoted the adhesion,spreading and viability of BMSCs.Increased extracellular matrix production and expression of osteogenic markers in BMSCs were observed when seeded on CACB scaffolds.The cells ceased to proliferation in the dual effect of CACB and osteogenic induction at the early stage of incubation. Hence synergistic effect of CACB combined with autologous undifferentiated BMSCs in rabbit mandible critical-sized defect repair was further evaluated.Histological analysis results showed that loading the CACB with autologous BMSCs resulted in enhanced new bone formation and angiogenesis when compared with implanted CACB alone.These findings indicate that the combination of CACB and autologous BMSCs should become potential routes to improve bone repair efficiency     

Osteogenic Effects of VEGF‐Overexpressed Human Adipose‐Derived Stem Cells with Whitlockite Reinforced Cryogel for Bone Regeneration

Bone is a vascularized tissue that is comprised of collagen fibers and calcium phosphate crystals such as hydroxyapatite (HAp) and whitlockite (WH). HAp and WH are known to elicit bone regeneration by stimulating osteoblast activities and osteogenic commitment of stem cells. In addition, vascular endothelial growth factor (VEGF) is shown to promote osteogenesis and angiogenesis which is considered as an essential process in bone repair by providing nutrients. In this study, VEGF‐secreting human adipose‐derived stem cells (VEGF‐ADSCs) are developed by transducing ADSCs with VEGF‐encoded lentivirus. Additionally, WH‐reinforced gelatin/heparin cryogels (WH‐C) are fabricated by loading WH into gelatin/heparin cryogels. VEGF‐ADSC secrete tenfold more VEGF than ADSC and show increased VEGF secretion with cell growth. Also, incorporation of WH into cryogels provides a mineralized environment with ions secreted from WH. When the VEGF‐ADSCs are seeded on WH‐C, sustained release of VEGF is observed due to the specific affinity of VEGF to heparin. Finally, the synergistic effect of VEGF‐ADSC and WH on osteogenesis is successfully confirmed by alkaline phosphatase and real‐time polymerase chain reaction analysis. In vivo bone formation is demonstrated via implantation of VEGF‐ADSC seeded WH‐C into mouse calvarial bone defect model, resulted in enhanced bone development with the highest bone volume/total volume.     

型胶原在聚-L-乳酸(PLLA)表面的化学接枝和涂层及其对软骨细胞生长的促进作用

采用接枝-涂层技术在聚-L-乳酸(PLLA)膜表面接枝聚甲基丙烯酸(PMAA)得到稳定的PLLA-g-PMAA胶原涂层.利用水溶性碳化二亚胺作为缩合剂,使PLLA-g-PMAA表面的羧基和胶原分子中的氨基发生缩合反应,从而将型胶原接枝在PLLA表面;同时保留材料表面物理涂层的胶原溶液,获得了稳定的胶原涂层.XPS谱图证实了接枝反应的发生.分别用比色法和茚三酮法测定了PLLA-g-PMAA表面的羧基密度和PLLA膜表面胶原的接枝量和涂层量.细胞培养结果表明,改性后的PLLA膜表面软骨细胞的铺展性能和增长速度明显改善.     

A Robust Method to Generate Mechanically Anisotropic Vascular Smooth Muscle Cell Sheets for Vascular Tissue Engineering

In arterial tissue engineering, mimicking native structure and mechanical properties is essential because compliance mismatch can lead to graft failure and further disease. With bottom‐up tissue engineering approaches, designing tissue components with proper microscale mechanical properties is crucial to achieve the necessary macroscale properties in the final implant. This study develops a thermoresponsive cell culture platform for growing aligned vascular smooth muscle cell (VSMC) sheets by photografting N‐isopropylacrylamide (NIPAAm) onto micropatterned poly(dimethysiloxane) (PDMS). The grafting process is experimentally and computationally optimized to produce PNIPAAm–PDMS substrates optimal for VSMC attachment. To allow long‐term VSMC sheet culture and increase the rate of VSMC sheet formation, PNIPAAm–PDMS surfaces were further modified with 3‐aminopropyltriethoxysilane yielding a robust, thermoresponsive cell culture platform for culturing VSMC sheets. VSMC cell sheets cultured on patterned thermoresponsive substrates exhibit cellular and collagen alignment in the direction of the micropattern. Mechanical characterization of patterned, single‐layer VSMC sheets reveals increased stiffness in the aligned direction compared to the perpendicular direction whereas nonpatterned cell sheets exhibit no directional dependence. Structural and mechanical anisotropy of aligned, single‐layer VSMC sheets makes this platform an attractive microstructural building block for engineering a vascular graft to match the in vivo mechanical properties of native arterial tissue.