Determination of alkaline-earth metals in foetus bones by inductively-coupled plasma atomic-emission spectrometry

Alkaline-earth metals in human bone samples have been determined simultaneously by inductively-coupled plasma atomic-emission spectrometry (ICP-AES). Results obtained by atomic-absorption spectrometry for Mg, Sr and Ba, and complexometry for Ca, have been compared with those by ICP-AES for a laboratory-control bone sample. Accuracy and precision were examined by analysing the IAEA animal bone standard (H-5). Agreement with the certified values to within 5% was obtained. The concentrations of the elements in foetal bone have also been determined.     

A model of a dust-loaded filter with asymmetric deposit of particles on fibers

Results of numerical simulation have been reported for the flow field and diffusion deposition of nanoparticles in a model dust-loaded fibrous filter, i.e., a row of parallel fibers coated with porous permeable shells shifted toward an incident flow. The flow field and point particle collection efficiency on fibers coated with the shells have been calculated by combining the Stokes, Brinkman, and convective diffusion equations. It has been shown that the pressure drops and efficiencies of nanoparticle deposition in the filters composed by fibers with coaxial and asymmetric porous shells are almost identical.     

Water Diffusion in Glassy Polymers and their Silica Hybrids: an Analysis of State of Water Molecules and of the Effect of Tensile Stress

In-situ, time-resolved FTIR spectroscopy along with gravimetric analysis have been used to investigate water sorption and transport in several glassy polymeric matrices, characterized by different levels of interaction with water, as well as on polymer-silica hybrids. This technique has also been coupled to a dynamical-mechanical analyser to gather information on the water sorption kinetics and thermodynamics in a polymer sample submitted to stretching deformation and load. Results have been modelled by coupling the mass balance and momentum balance, using a theoretical approach developed for elastic matrices and low sorbed amounts by Larché and Cahn.     

Resonances in the elastic electron-SF6 molecule scattering

In agreement with previous calculations by the authors, three definite resonances in the elastic electron-SF₆ molecule scattering in the energy range 5–40 eV have been obtained with a multiple scattering method, elaborated originally for molecular bound states and modified here for scattering states. Results with various more-reliable one-electron potentials have been compared with previous calculations and available experimental data.     

Positronium scattering from ions, atoms and molecules

Elastic and inelastic scattering of positronium (Ps) by H, He, He⁺ and H₂ have been studied using coupled-channel calculations with a regularised nonlocal model exchange potential. Suitability and reliability of the theoretical scheme have been demonstrated by studying scattering cross-sections in various systems and also by addressing critical dynamic features like binding and resonances of Ps to open-shell-atoms. Results are found to be in good agreement with variational predictions and experimental observations.     

Roothaan INDO CI spin density calculation

Spin densities have been calculated by the Roothaan INDO CI method in the parametrization of Pople and Kaufman. The dependence of the spin densities on both the type and the number of configurations in CI has been followed. Results have been compared with the UHF and spin-projected UHF methods.     

Phosphinates and layered silicates in charring polymers: The flame retardancy action in polyurethane foams

Nanocomposites of a charring polymer (like polyurethane foam) filled with aluminum phosphinate (AlPi) with or without melamine cyanurate (MelCy) have been prepared by microwave processing and their thermal stability and fire behavior have been studied. Results on the interaction between flame retardants and layered silicates were provided as well as detailed investigation of the char strength, which has been carried out using a suitably developed method based on dynamic-mechanic analysis.     

Volumetric and refractive properties of binary mixtures containing 1,3-dioxolane and isomeric chlorobutanes

The relation between refractive index deviations and excess volumes for binary mixtures formed by a cyclic ether and a haloalkane has been tested using several methods: refractive index mixing rules and equations of state. Refractive index deviations, excess volumes and molar refractions have been calculated from experimental data of refractive indices and densities at two temperatures 298.15 and 313.15 K. Results obtained have been discussed in terms of intermolecular interactions. Refractive indices were compared with those predicted by several mixing rules. Excess volumes have also been correlated using several cubic equations of state and finally a relation between parameter b from equations of state and molar refraction has been provided.     

The error in absorption measurements, caused by the use of non-monochromatic light-II Gaussian functions

The errors in absorption measurements in spectrophotometry, caused by the use of non-monochromatic light, have been calculated. Gaussian functions have been assumed for the wavelength-dependence of the intensity of the incident light falling on the cell and the absorbance of the compound measured. Results found are similar to those found with parabolic functions. Experiments have been made to compare the results of the calculations with experimental values. The agreement is fairly good in most cases.     

聚甲基丙烯酸甲酯型高分子染料的合成

高分子染料的合成研究起于６０年代初［１］．１９７３年，Ｍａｒｅｃｈａｌ等实现了无色高分子材料与有色染料分子的化学键合［２～３］．目前，高分子染料已广泛应用于化妆品、涂料、填料、食品等领域并开始探索在液晶显示、半导体材料、激光记录、非线性光学材料、亲和...     

High Temperature Stability of Sol-Gel-Derived SiOC Glasses

The high temperature stability of sol-gel-derived SiOC glasses has been investigated in order to understand the role played by the presence of a free-carbon phase in the amorphous oxycarbide network. Therefore, pure and excess free-carbon containing SiOC glasses have been prepared from hybrid gels and used for the high temperature stability experiments. Moreover, the possible effects of the sample size with respect to local kinetics and thermodynamics and of the testing environment have also been investigated. Results show that all these parameters play a crucial role in defining the high temperature behavior of SiOC glasses.     

Nanotexturing of polystyrene surface in fluorocarbon plasmas: from sticky to slippery superhydrophobicity

In this work plasma etching processes have been studied to roughen and fluorinate polystyrene surface as an easy method to achieve a superhydrophobic slippery character. Radiofrequency discharges have been fed with CF(4)/O(2) mixtures and the effect of the O(2):CF(4) ratio, the input power, and the treatment duration have been investigated in terms of wettability, with focus on sliding performances. For this purpose, surface morphological variations, evaluated by means of scanning electron microscopy and atomic force microscopy, together with the chemical assessment by X-ray photoelectron spectroscopy, have been correlated with water contact angle hysteresis and volume resolved sliding angle measurements. Results indicate that by increasing the height and decreasing the density of the structures formed by etching, within a tailored range, a transition from sticky to slippery superhydrophobicity occurs. A short treatment time (5 min) is sufficient to obtain such an effect, provided that a high power input is utilized. Optimized surfaces show a unaltered transparency to visible light according to the low roughness produced.     

Effect of substituent of terpyridines on the DNA-interaction of polypyridyl ruthenium(II) complexes

An octahedral complexes of ruthenium with 2,9-dimethyl-1,10-phenanthroline (dmphen) and substituted terpyridine have been synthesized. The Ru(II) complexes have been characterized by elemental analyses, thermogravimetric analyses, magnetic moment measurements, FT-IR, electronic, (1)H NMR and FAB mass spectra. The binding strength and mode of interaction of the complexes with Herring Sperm DNA has been investigated using absorption titration and viscosity measurement studies. Results suggest that the substituent on terpyridine ligand affects the binding mode and binding ability of the complexes. Effect of time and ionic strength on DNA cleavage ability of complex has also been studied by gel electrophoresis. Results suggest that more than 200 mM concentration of NaCl decreases the cleavage ability of complex.     

Electrolytic conductivity: a reference system for aqueous solutions

To establish a system for the measurement of electrolytic conductivity in aqueous solutions with traceability to the SI, a cell has been developed with a removable central section providing an accurate determination of the geometrical constant. As the concentration unit mass/mass, based and referred to the amount of substance in the SI, is recommended by international organisations, 0.1 molal KCl samples have been prepared and analysed. Results over a temperature range from 20 degrees C to 35 degrees C are presented. The main sources of error have been estimated and relative uncertainty has been assessed to remain at the level of 0.6%. Satisfactory agreement is observed when the results are compared with the reference values available from literature.     

Propeller-like hydrogen-bonded banana-melamine complexes inducing helical supramolecular organizations

The results of the study presented here show a new example of the use of liquid crystals and the interactions involved in the mesomorphic state to build up complex molecular organizations. We have pursued a design strategy in which hydrogen bonding allows the combination of the pi-stacking tendency of melamine and the lateral interaction capability of V-shaped molecules, which has been extensively demonstrated through nematic, smectic, or columnar mesophases. This combination addresses the formation of columnar arrangements with inherent helical organization. In this work, nonmesomorphic as well as mesomorphic V-shaped acids, with a structure similar to banana liquid crystals, have been complexed to a 2,4,6-triamino-1,3,5-triazine derivative in a proportion 3 to 1, respectively. Hydrogen-bonded supramolecules whose formation and stability in solution have been proven by infrared and NMR techniques have been thus obtained. DOSY experiments have allowed us to assess in solution the presence of the complexes and their tetrameric composition. All the complexes display mesogenic ability, and their mesomorphic organization has been studied by X-ray diffraction and CD spectroscopy. Results allow us to propose a helical columnar model for the mesophase originated from a propeller-like conformation of the supramolecular complexes.     

Extended ab initio calculations on cyclopropane,cyclopropene and cyclopropenone

The three-membered ring systems, cyclopropane, cyclopropene and cyclopropenone, have been investigated using a (9,5,1 ) Gaussian basis set. A detailed study of the chemical binding in these systems has been of particular interest. Results for the molecular ground states have been compared with predictions made previously using smaller basis sets and also with pertinent experimental findings.     

1,4,7-三氮杂环癸烷过渡金属配合物的合成与结构表征

以十元环大环三胺配体1,4,7-三氮杂环癸烷(tacd)为主配体,分别与钴、镍、铜和锌的顺丁烯二酸盐和己二酸盐进行反应,得到了8种含有双大环的单核配合物,利用元素分析,红外光谱以及热重分析等手段对它们的结构进行了表征.结果表明这八种配合物具有类似的配位结构.     

The synthesis and properties of bis-1,1'-(porphyrinyl)ferrocenes

Ferrocene-bridged bisporphyrins have been synthesized by the condensation of corresponding dipyrromethane-derived diols with a bisdipyrromethane. Purification of the final compounds has been achieved without chromatography. The specific geometry of these bisporphyrins makes them valuable starting points for building complex molecular and supramolecular structures. In particular it provides a core to which multiple sites of attractive intermolecular interactions can be attached thereby creating compounds predisposed to form complex networks by association. We have studied the structure of bis-1,1'-(porphyrinyl)ferrocenes by 1H NMR, UV-Vis and electrochemistry. Results have shown that complex dynamic processes occur in these molecules (which may involve conformers, formation of H-aggregates and tautomers) and that they have non-typical electrochemical behaviour.     

An investigation of complexes of some model tripeptides containing phenylalanine and tyrosine residues with DNA by Fourier1H NMR spectroscopy

Complexes of native and denatured DNA with model tripeptides containing phenylalanine or tyrosine residues flanked by lysine or arginine residues, respectively have been investigated by pulsed Fourier¹H NMR spectroscopy. The existence of shifts into the strong-field region of the signals of aromatic protons of the model tripeptides in the complexes both with native and with denatured DNA has been shown. Results have been obtained that indicate the possibility of the intercalation of the side chains of aromatic amino acid residues into the DNA double helix.