Spectroscopic Studies of the Reactions of π-Electron Acceptors with the Cyclic Polyamine 1,4,8,11-Tetraazacyclotetradecane

The reactions of π-electron acceptors such as 1-chloro-2,4,6-trinitrobenzene (picryl chloride), 7,7′,8,8′-tetracyanoquino-dimethane (TCNQ), tetrachloro-p-benzoquinone (chloranil) and tetra-cyanoethylene (TCNE) with the cyclic polyamine base 1,4,8,11-tetraazacyclotetradecane (TACTD) have been investigated in CHCl₃ solvent. The data indicate the formation of the CT-complexes with the general formula [(TACTD) (acceptor)₂]. The 1: 2 stoichiometry of the (TACTD)-acceptor was based on elemental analysis and infrared spectra of the solid CT-complexes along with the photometric titration curves for the reactions in CHCl₃. The formation constants (K) for the CT-complexes are shown to be strongly dependent on the type and structure of the acceptor.     

II. “Spectroscopic Investigation of Charge Transfer Complexes of Osazone Intermediates Prepared From certain monosaccharides”

Monosaccharide osazones are utilized in the spectrophotometric determination of their parent compounds through charge transfer complexes (CTC) formation with three-electron acceptor reagents. These acceptors indlude iodine (as -π-acceptor) and chloranil (tetrachloro P-benzoquinone) & TCNE (tetracyano ethylene) as π-acceptors. The presence of two phenylhydrazone moieties in the osazone molecule imparts electron-donating properties toward electron-accepting reagents, yielding spectrophotometrically measurable complexes. However, the reaction of osazone intermediates with TCNE reagent gave tricyanovinyl derivative rather than CTC formation. The above complexes together with their corresponding intermediates were subjected to structure elucidation studies to confirm the results and conclusions obtained. These studies include IR, Raman spectra, H¹, C¹³-NMR, MS, ESR (electron spin resonance spectra) and microanalysis.     

Effects of Charge Transfer Agents on the Holographic Parameters of a Photopolymer

The principle of charge transfer agents was investigated experimentally.There is a compensation effect between triethanolamine (TEA) and diphenyliodonium hexafluorophosphate (DPI) in the polymerization process of a photopolymer.The experimental results illustrate that TEA has a stronger effect in the initial stage of exposure,and DPI has a stronger effect during the propagation stage of the polymerization process.We explain the main contributions of DPI in the superadditive photopolymer kinetics that results in an obvious increase of sensitivity.     

Spectroscopic Investigation of the Adsorption of Nitrophenol Isomers on Ammonium Zeolite of Type “Y”

In this study, nitrophenol isomers were adsorbed on synthetic ammonium Y zeolite and the samples acquired were examined with infrared spectroscopy and scanning electron microscopy. The aim of the work is to investigate whether isomeric effects can be monitored after adsorption process. Theoretical calculations of isomers had been performed and the data acquired show that adsorption occurred via bonding from the sites of zeolite.     

Conformational Changes of the Troponin—Tropomyosin Complex on F-Actin Observed by Fluorescence Resonance Energy Transfer Measurements

Contraction of vertebrate striated muscle is regulated by the strong Ca²⁺-dependent interaction among troponin (Tn), tropomyosin (Tm), and actin on the thin filament. Using fluorescence resonance energy transfer (FRET), the interactions between Tm and the Tn complex or between Tm and the Tn subunit, TnI or TnC, with or without other troponin subunits, were characterized in the presence or absence of F-actin and Ca²⁺ ions. Cys-190 of Tm was selectively labeled with the acceptor probe, 4-dimethylaminophenylazophenyl 4-maleimide. Troponin was selectively labeled at position 9 or 133 of TnI and position 98 of TnC with a donor probe, 5-(2-iodoacetylaminoethyl)aminonaphtha lene 1-sulfonic acid. FRET measurements indicate that the interaction between TnI and Tm alone is very weak, but that in the presence of F-actin, TnI binds to the proper binding site on Tm even in the absence of TnT. The distances between Cys-190 of Tm on F-actin and Cys-9 or Cys-133 of Tnl or Cys-98 of TnC in the reconstituted Tn were determined to be 52.8, 53.7, Å and 56.5 Å, respectively, in the absence of Ca²⁺, indicating that the Tnl—TnC complex, the globular portion of Tn, is located near Cys-190 of Tm on the reconstituted thin filaments. Upon binding of Ca²⁺ to TnC, these distances increased by 5.6 and 1.4 Å or decreased by 5.4 Å, respectively. These Ca²⁺-induced changes in Tn—Tm seem to occur only when F-actin is present, suggesting that the stable complex formation of TnI with the outer domain of F-actin upon removal of Ca²⁺ is a very important event during inhibition.     

Investigation on Third-order Optical Nonlinearity of Ni-Azo Metal Complex by the Z-scan Technique

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｏｒｇａｎｉｃｍａｔｅｒｉａｌｓｗｉｔｈπｅｌｅｃｔｒｏｎｄｅｌｏｃａｌｉｚａｔｉｏｎｈａｖｅｂｅｅｎｅｘｔｅｎｓｉｖｅｌｙｓｔｕｄｉｅｄａｓａｎｉｍｐｏｒｔａｎｔｃｌａｓｓｏｆｎｏｎｌｉｎｅａｒｏｐｔｉｃａｌｍａｔｅｒｉａｌｓｂｅｃａｕｓｅｏｆｔｈｅｉｒｌａｒｇｅａｎｄｆａｓｔｎｏｎｌｉｎｅａｒｏｐｔｉｃａｌｒｅｓｐｏｎｓｅ[1,2].Ｔｏｄａｔｅ,ｈｏｗｅｖｅｒ,ｏｒｇａｎｏｍｅｔａｌｌｉｃａｎｄｃｏｏｒｄｉｎａｔｉｏｎｃｏｍｐｌｅｘｅｓｒｅｃｅｉｖｅｄｌｅｓｓａｔｔ…     

Spectral and Quantum‐Chemical Investigation of the Influence of the Spatial Structure of a Polymeric Complex on the Mechanism of Catalytic Oxidation of Sulfur Dioxide with Oxygen

Based on the calculations carried out by the ZINDO/S method, we suggest interpretation of the electronic absorption spectra of solvate complexes of cobalt with polyethyleneimine and sulfite ion. The quantumchemical analysis of the spectrophotometric data has shown that the change in a concentration of cobalt ions in a solution leads to conformation changes in a polymeric chain. The kinetic and quantumchemical investigation of the mechanism of catalytic oxidation of SO₃ ^2– to SO₄ ^2– is carried out. We suggest a spatial structure of the transient state that provides optimum conditions for the oxygenation reaction. The kinetic data indicate that the catalytic activity of cobalt ions fixed on a polymeric matrix is by three orders of magnitude higher than of their monomeric analogs. Using calculations performed by the RM3 method, we show that the oxygenation process is of exothermal nature and that there is a direct correlation between the reactionrate constant and the energy released in the process of oxygenation (E). On substituting ammonia molecules by a polyethyleneimine fragment, E increases by 39.39 kcal/mole.     

Ionization Energies in Dithiocarbamate Derivatives of α-Amino Acids: A Spectroscopic Investigation on the Effect of the Side Chain

Ionization energies of dithiocarbamate derivatives of α-amino acids (glycine, alanine, valine, leucine) have been determined by X-Ray Photoelectron Spectroscopy. The values determined increase as the side chain in these amino acids becomes longer, a fact probably related to the different donor ability of these radicals. A parallel effect has been also observed in the precise positions of the IR absorption bands for these compounds.     

Investigation of the First Mirror on Tokamak

The study progress of NNSF in 2006 has been presented in this paper. The aim and plan of this item have been described briefly. Three test mirror exposure experiments have been done in this year. The main components of the deposited materials on the first mirror are carbon and iron analyzed by AES. The first mirror is polluted easier during glow discharge and wall processing than omhic discharge.     

Spectroscopic analysis of the riboflavin—serum albumins interaction on silver nanoparticles

Metallic nanoparticles (NPs) supported on oxides thin films are commonly used as model catalysts for studies of heterogeneous catalysis. Several 4d and 5d metal NPs (for example, Pd, Pt and Au) grown on alumina, ceria and titania have shown strong metal support interaction (SMSI), for instance the encapsulation of the NPs by the oxide. The SMSI plays an important role in catalysis and is very dependent on the support oxide used. The present work investigates the growth mechanism and atomic structure of Rh NPs supported on epitaxial magnetite Fe₃O₄(111) ultrathin films prepared on Pd(111) using the Molecular Beam Epitaxy (MBE) technique. The iron oxide and the Rh NPs were characterized using X-ray photoelectron spectroscopy (XPS), low-energy electron diffraction and photoelectron diffraction (PED). The combined XPS and PED results indicate that Rh NPs are metallic, cover approximately 20 % of the iron oxide surface and show height distribution ranging 3–5 ML (monolayers) with essentially a bulk fcc structure.     

Structural and Spectroscopic Investigation of Biomimetic Composites—Promising Agents for the Remineralization of Native Dental Tissue

Biomimetic materials (biocomposites) with an organic-mineral composition related to natural dental tissues (enamel and dentin) are obtained for the first time and their structural and optical characteristics are studied. It is demonstrated by a complex of structural and spectroscopic methods that in the formation of biocomposites, the introduced organic component, bearing a number of amino acids, does not affect the structure of the inorganic component (carbonate-substituted calcium hydroxyapatite) of the sample. The carbonate-substituted calcium hydroxyapatite synthesized using a biogenic source of calcium, which forms the basis of the biocomposite, has a luminescence spectrum similar to that of apatite tooth enamel. The spectrum of the intact dentin of a human tooth has a broader luminescence band than that for the enamel spectrum. It is determined that both organic and inorganic components contribute to the dentin luminescence band. The features found in the luminescence spectra of intact tissues and in simulating biocomposites can be used to develop a procedure for effective early diagnosis of the demineralization of hard dental tissues and general dental examination.     

Investigation on the power broadening of uranium transition

By making the power broadening experiments,we have observed and analyzedthe phenomena of power broadening and the central frequency shif of fluorescence for the ura-nium transition 0-169000.38cm~(-1) for the first time.     

Investigation on the Fabrication of Photonic Crystal Fibre

Effects of draw parameters, such as drawing temperature and feed speed, on the capillaries and the geometry of the final photonic crystal fibre （PCF） are investigated. Inert gas pressurization is introduced in the preform during the fibre drawing process to finely control the geometry of the PCF so that good uniform in transversal and longitudinal of the final PCF can be realized. Due to the introduction of a special method, the drawing temperature is increased over 1900℃ and the strength of the PCF is enhanced.     

Spectroscopic factors of resonance states with the Gamow shell model

We provide an investigation of the spectroscopic factor of resonance states in A=5-8 nuclei, utilizing the Gamow shell model(GSM). Within the GSM, the configuration mixing is taken into account exactly with the shell model framework, and the continuum coupling is addressed via the complex-energy Berggren ensemble, which treats bound, resonance, and non-resonant continuum single-particle states on an equal footing. As a result, both the configuration mixing and continuum coupling are meticulously...     

Experimental Investigation of the Velocity Effect on Adhesion Forces with an Atomic Force Microscope

Capillary forces are significantly dominant in adhesive forces measured with an atomic force microscope (AFM) in ambient air, which are always thought to be dependent on water film thickness, relative humidity, and the free energy of water film. We study the nature of the pull-off force on a variety of surfaces as a function of tip velocity. It is found that the capillary forces are of relatively strong dependence on tip velocity. The present experiment is expected to provide a better understanding of the work mechanism of AFM in ambient air.     

Spectroscopic study of polyphenylquinolines—materials with efficient intramolecular charge transfer

The energy structure and nature of intramolecular charge transfer have been determined for a series of synthesized 2,6-polyphenylquinolines (PPQs) containing resorcinol, oxygen, and phenylamine bridging groups between phenylquinoline cycles and possessing an arylene radical in the form of alkylated derivatives of carbazole or indolo[3,2-b]carbazole, as well as arylated derivatives of carbazole with nitro- and fluorine substituents. The analysis was based on data on their absorption spectra, photosensitivity, carrier photogeneration quantum efficiency, and luminescence. It is shown that the PPQ monomeric unit is a composite intramolecular charge-transfer complex (ICTC) between the donor arylene fragment and the acceptor quinoline cycle; the latter, in turn, is an ICTC between the donor bridging group and quinoline ring (when acceptor fluorine or nitro substituents are introduced into the carbazole structure, the complex becomes ternary), and the narrowest band gap (2.3 eV) corresponds to the PPQ having a phenylamine bridging group and a fragment of indolo[3,2-b]carbazole.     

Coupled—Channel Investigation of the Collision of Protons and Antiprotons with hydrogen—Like Atoms in the 2s States

The influence of the electric charge of both the projectile and the target nucleus on the cross section of the inelastic collision of protons and antiprotons with atoms is investigated at energies ranging from 1 to 2500Kev,The impact parameter method is used to analyse the cross sections of the excitation of the n=3 states of H atom and He^ ,Li^2 ions being initially in the excited 2s states.The calculated cross sections for hydrogen atome are compared with the other theoretical results based on coupled-channels methods.     

Spectroscopic study on the interaction of Bacillus subtilis α-amylase with cetyltrimethylammonium bromide

The interaction between α‐amylase from Bacillus subtilis and cetyltrimethylammonium bromide (CTAB) has been investigated at various temperature conditions using fluorescence and circular dichroism (CD) spectroscopic methods. Fluorescence data revealed that the fluorescence quenching of α‐amylase by CTAB is the result of complex formation between CTAB and α‐amylase. The thermodynamic analysis on the binding interaction data shows that the interactions are strongly exothermic (ΔH°=−17.92 kJ mol⁻¹) accompanied with increase in entropy (ΔS° between 109 to 135 J mol⁻¹ K⁻¹). Thus the binding of CTAB to α-amylase is both enthalpic and entropic driven, which represent the predominate role of both electrostatic and hydrophobic interactions in complex formation process. The values of 2.17×10⁻³ M⁻¹ and 1.30 have been obtained from associative binding constant (K_a) and stoichiometry of binding number (n), from analysis of fluorescence data, respectively. Circular dichroism spectra showed the substantial conformational changes in secondary structure of α‐amylase due to binding of CTAB, which represents the complete destruction of both secondary and tertiary structure of α-amylase by CTAB.