STRUCTURAL STUDIES ON CRYSTALLINE 3,4—POLYISOPRENE

In the paper,the structures of the crystalline 3,4-polyisoprene(3,4-PI) which was first synthesized in our institute,were investigated by using Wide Angle X-ray Diffraction(WAXD);Small Angle X-ray Scattering(SAXS)and Laue photography in various polymerization conditions and elongate ratios.It was found that reducing reaction velocity was favourable for crystalline capacity.The polymeric structures were dependent mainly on nitrogen electron donor.The degree of crystallinity and long period were increased with elongate ratio,but crystalline size was decreased.The polymers used in the work belong to inhomogeneous particulate system.The particulate radii were between 35-164A.

STRUCTURAL STUDIES OF AN ARABINOGALACTAN——A WATER SOLUBLE POLYSACCHARIDE FROM THE POLLEN OF PAPAVER SOMNIFERUM

A polysaccharide,PS(1),has been isolated from the pollen of papaver somniferum.PS(1)is a highly branched arabinogalactan,which,mainly contains α—L—arabinofuranosyl(1→)and(3,6→1)— β—D—galactopyranosyl residues.We also studied the circular dichroism and immunoactivity of PS(1).

The synthesis and structural studies of mixed ligand complex,tris(1-phenyl-3-methyl-4-trifluoroacetylpyrazol-5-one)mono(1-phenyl-3-methyl-pyrazol5-one)neodymium(Ⅲ)monohydrate

A mixed ligand neodymium complex containing 1-phenyl-3-methyl-4-trifluoroacetyl- pyrazol-5-one(HPMTFP)and 1-phenyl-3-methyl-pyrazol-5-one(PMP),with molecular formula Nd(PMTFP)_3·PMP·H_2O was synthesized.Its crystal and molecular structure has been determined by single crystal X-ray diffraction method.The complex crystallizes in monoclinic system with space group C_2~5h-P2_(1/n).There are four formula units in a cell of dimensions a=12.837(3),b=23.763(5),c=16.810(4) ,β=109.58(2)°.The structure has been refined by full-matrix least-squares techniques to a final R value of 0.0487 and Rw value of 0.432.The neodymium atom is coordinated to eight oxygen atoms with the average Nd-O bond length 2.439,Its thermostability,and mass spectrum have been discussed.

Studies on Structural Changes of Collagen in Silicosis

In order to provide scientific information on the prevention and treatment of silicosis,studies about changes of silicotic collagen in lungs were carried out. In this paper, we present experiments about the structural changes of collagen in silicotic lungs of rats and patients. These included electron microscopy, circular dichroism and infrared spectroscopy studies of collagen fibers. The results indicated that fibers of silicotic collagen were shorter in length, smaller in diameter and decreased in α-helix content. The -Si-O-R- group and -OH group were found increased and -C-C- backbone shortened. The increase of -Si-O-R-group indicated that silica formed linking bridges between collagens which may be the cause of progressive enlargement of nodules

Using of Key Stratum Theory to Study the Structural Development of Roof Aquifer

During the underground mining of coal resources,overlying rocks on the roof of excavated tunnels will be destroyed due to ground pressure,and as a result,part of them will break and fall into the tunnels.How to determine the distribution of fractured areas and fissures presents a major problem for preserving the overlying aquifer.

Microstructure studies of air-plasma-spray-deposited CoNiCrAlY coatings before and after thermal cyclic loading for high-temperature application

In the present study, bond-coats for thermal barrier coatings were deposited via air plasma spraying（APS） techniques onto Inconel 800 and Hastelloy C-276 alloy substrates. Scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, X-ray diffraction（XRD）, and atomic force microscopy（AFM） were used to investigate the phases and microstructure of the as-sprayed, APS-deposited Co Ni Cr Al Y bond-coatings. The aim of this work was to study the suitability of the bond-coat materials for high temperature applications. Confirmation of nanoscale grains of the γ/γ′-phase was obtained by TEM, high-resolution TEM, and AFM. We concluded that these changes result from the plastic deformation of the bond-coat during the deposition, resulting in Co Ni Cr Al Y bond-coatings with excellent thermal cyclic resistance suitable for use in high-temperature applications. Cyclic oxidative stability was observed to also depend on the underlying metallic alloy substrate.

Structure Studies on Host-Guest Recognition Sensory Systems

Rhodamine B-ethylenediamine-beta-cyclodextrins (RhB-beta-CDen) and rhodamine B-beta-cyclodextrins (RhB-beta-CD) form inclusion complexes with many guest molecules, which can be used as nucleic acid probe. In this paper we determined the most stable conformations of RhB-beta-CDen and RhB-beta-CD by molecular mechanics and dynamics simulation. The interaction between RhB-beta-CDen and two guest molecules, 1-borneol and cyclohexanol, have been investigated both theoretically and experimentally. The results show that the interaction between borneol and RhB-beta-CDen is stronger than that between cyclohexanol and RhB-beta-CDen.

PARACRYSTAL STRUCTURE PARAMETERS STUDIES IN LDPE/EPO BLENDS WITH VARIANCE-RANGE FUNCTION METHOD

X-ray diffraction line profiles of low density polyethylene(LDPE)/ (ethylene-propylene-octene-1)copolymer(EPO)blends have been analyzed with variance range function method.Theories for determining the microparacrystallite size and the distortion parameter from single reflection have been described,and the value of these two parameters at (110)and(200)directions have been determined.

Studies of Structure Evolution of Nanostructured Hf_(11)Ni_(89) Alloy

A nanostructured Hf11Ni89 ribbon sample was prepared by melt-spinning. It was found that the as-quenched sample is composed of a major HfNi5 compound nanophase and an interfacial magnetic Ni(Hf) solid solution phase. The structure evolution of the sample was studied by using X-ray difFraction (XRD), transmission electron microscopy (TEM), difFerential scanning calorimetry (DSC), resistivity and magnetothermal analysis. Upon heating, a second precipitation process of the Ni(Hf) phase prior to grain growth wa5 detected by means of both structural analysis and physical property measurements. The measurement results are discussed based on the relationship between microstructure and physical properties.

LOCALIZED STUDIES ON ELECTRONIC STRUCTURE AND CHEMICAL BOND FOR [NCCuS_2MoS_2]^(2-) CLUSTER

The canonical and locatized molecutar orbiters of [NCCuS_2NoS_2]^(2-) cluster were calculated by means of CNDO quantum chemistry method. Then the energy and properties of corresponding chemicat bonds were discussed, especially, Cu-Sb-No three center conjugated π bonds and No-St-No conjugated π bonds were accounted for.

Studies of Atomic Structure and Physical Properties of Metal Clusters in MgO by HREM and Nano-probe Methods

Nanometer-sized metal clusters were prepared inside single crystalline MgO films by vacuum co-deposition of metals and MgO. The atomic structure was studied by high-resolution electron microscopy (HREM) and nm-area electron diffraction. The size of the clusters is ranging from 1 nm to 3 nm without those larger than 5 nm, and most of them have definite epitaxial orientations with the MgO matrix films. The character of the composite films is very much useful for the studies of various kinds of physical properties with anisotroPy. The physical properties such as electric transport, magnetic, optical absorption, sintering and catalytic ones were thus measured on the same samples analyzed by HREM by using high sensitivity apparatus with interest of clarifying the retationship between the atomic structure and physical properties

A STUDY ON THE STRUCTURAL EFFECT OF DOUBLE BRIDGES CONJUGATED SYSTEMS I.CARBONYL-IMINO SYSTEM

The struetural effect of the conjugative system(C)with carbonyl-imino bridges has been studied.The results show that:In the conjugated system(C),there is no electronic absorption peak attributable to the whole system,but there are three π-π* bands each nt which displays chacactecistics of its own independently.These indicate that the two bridges-carbonyl-and-imino-can block the tlanSmlSSion of the conjngative polarization of the whole system,so as to form three segments,this is verified by means of chemical synthesis and degradation.

Inorganic Crystal Structure Data to be Presented in a Form More Useful for Further Studies

To make inorganic structure data more useful for further studies a five-point list of simple procedures to be followed by authors of crystal structure papers is proposed. 1. A crystal structure should be described with the space group corresponding to its true symmetry. 2. A new structure proposal should be tested, if it is realistic in principle. 3. A structure should be described with a space group in a setting given in the International Tables. 4. For a comparison with other structures the structure data should be standardized with the program STRUCTURE TIDY. 5. 揘ew?structure data should be checked in the databases, Chemical Abstracts or on-line internet resources, if they are really new. The list is supplemented with many explanations, commentaries, examples and references.

Study of GaAs/GaAlAs Multilayer Structural Materials by Electrolyte Electroreflectance

Electrolyte electroreflectance (EER) has been widely employed to investigate the electronic energy band structure and related physical properties of semiconductors. The electrolyte electroreflectance (EER) method combined with electrochemical anodic dissolution was used to study GaAs/GaAlAs multilayer structural materials. According to variation of the EER spectra during anodic dissolution the characteristics of GaAs/GaAlAs multilayer structural materials such as properties of the interface, p-n junction positions and Al content profiles were obtained.

Synthesis,Structure,and Spectroscopic Studies of a Chiral Supramolecular Complex with Excellent Semiconductor Property

A novel chiral copper（Ⅱ） complex with racemic 1,2-diaminocyclohexane and iodide,[Cu（Ⅱ）（1,2-diaminocyclohexane）_3]（I）_2·3H_2O（1） has been synthesized and structurally characterized by X-ray single-crystal diffraction,elemental analysis,infrared spectroscopy,Raman spectroscopy and thermogravimetric analysis. In complex 1,the CuⅡ ion was coordinated by six nitrogen atoms of three 1,2-diaminocyclohexane molecules. The structure of complex 1 can be described as a supramolecular 3D-like structure which was formed by intermolecular hydrogen-bonding interactions between mononuclear molecules,uncoordinated water molecules and two iodide anions. UV-vis absorption spectrum and surface photovoltage properties of complex 1 have also been studied.

INDO STUDIES ON THE ELECTRONIC STRUCTURE OF[Ln(CCl_3COO)_3·phen·C_2H_5OH]_2(Ln=Pr,Sm)

The electronic structure and chemical bonding of the title comp- lexes have been studied by an unrestricted INDO program made applicable for the lanthanoid compounds.The results indicated:(1)In coordinated bonds O-Ln and N-Ln,5d orbitals of Ln have large contribution in all valence orbitals of Ln and 4f orbitals have very small contribution.(2)The covalent chara- cter and ionic character are almost equal in the chemical bond which is comparatively weak between phen,C_2H_5OH and Ln are mainly ionic with some covalent character.

Studies on the Relationship between the Helical Structure and Optical Activity of Some Chiral Cyclic Esters Ⅱ

A method for the analysis of the relationship between the helical structure and optical activity was proposed by the study of the conformations and X-ray diffraction structures of some cyclic esters prepared by esterification of L-(-)-2.3-O-methylidene threitol and L-(+)-2,3-O-isopropplidene threitol with alkanedioyl dichlorides and o-,m-,and p-phthaloyl dichlorides.

Ab Initio Studies of Radicals HBX(X=H, F, Cl, Br): Molecular Structure,Vibrational Frequencies and Potential Energy

We describe high-level ab initio calculations on the BH_2, HBF, HBCl and HBBr radicals. Molecular structure,vibrational frequencies and potential energy curves of the ground state and the first excited state, which are two Renner-Teller components for a^2Π state at linearity, are studied using the basis sets aug-cc-pVTZ and icMRCI＋Q technique. On the basis of the potential energy curves, a reliable potential energy barrier to dissociation HB＋X（X=F, Cl, Br） fragments and to linearity are given. The ab initio results will add some understanding on the spectrum and the photo-dissociation dynamics of the series of radicals.

Numerical study on three-dimensional flow field of continuously rotating detonation in a toroidal chamber

Gaseous detonation propagating in a toroidal chamber was numerically studied for hydrogen/oxygen/nitrogen mixtures. The numerical method used is based on the three-dimensional Euler equations with detailed finiterate chemistry. The results show that the calculated streak picture is in qualitative agreement with the picture recorded by a high speed streak camera from published literature. The three-dimensional flow field induced by a continuously rotating detonation was visualized and distinctive features of the rotating detonations were clearly depicted. Owing to the unconfined character of detonation wavelet, a deficit of detonation parameters was observed. Due to the effects of wall geometries, the strength of the outside detonation front is stronger than that of the inside portion. The detonation thus propagates with a constant circular velocity. Numerical simulation also shows three-dimensional rotating detonation structures, which display specific feature of the detonation- shock combined wave. Discrete burning gas pockets are formed due to instability of the discontinuity. It is believed that the present study could give an insight into the interest- ing properties of the continuously rotating detonation, and is thus beneficial to the design of continuous detonation propulsion systems.

Synthesis, Characterization and X-ray Structure of N-(4-bromobutanoyl-N'-(2-3-and 4-methylphenyl)thiourea

N-4-（bromobutanoyl）-N＇-（o-, m- and p-tolyl）thioureas 3a, 3b and 3c respectively, were synthesized by the reaction of 4-bromobutanoylisothiocyanate with p-, m- and o-toludine. The products were characterized by IR, and NMR spectroscopic techniques. The two carbonoylthiourea isomers N-（4-bromobutanoyl）-N＇-（3-methylphenyl）thiourea （3b） and N-（4-bromobutanoyl）-N＇-（4- methylphenyl）thiourea （3c） were obtained in crystalline form by recrystallization from DMSO. X- ray crystallographic studies showed that both compounds 3b and 3c crystallize in triclinic system with space group ofPi. The molecules adopt trans-cis configuration with respect to the positions of 4-bromobutanoyl and tolyl groups respectively, against the thiono C=S bond across their C-N bonds The configuration is attributed by the intrahydrogen bond between the carbonyl oxygen and amide hydrogen atoms. Both crystal structures are stabilized by N-H…S intermolecular hydrogen bonds to form dimers and arranged along the b axis.