HPLC study of the physicochemical characteristics of reverse-osmosis separation on a polyamide membrane material

Summary The fundamental characteristics of reverse osmosis on a polymer membrane have been correlated with HPLC experimental conditions by using the membrane material as a column packing. Twelve formulas were used to calculate the physicochemical characteristics of the reverse-osmosis separation process and it was found that these characteristics can be determined on the basis of retention (t _R, V_R) and partition coefficient (K) of the solute in HPLC. It seems that HPLC is an effective tool for studying the physicochemical nature of reverse-osmosis separations and the characteristics of the polymer membrane.     

Methods of production,structure, and physicochemical characteristics of phosphorylated carbon adsorbents

The paper presents a review of methods for the production of phosphorylated carbon adsorbents, their structure, and their physicochemical characteristics. It was shown that the phosphorylated carbons contain phosphoric acid residues (condensed phosphates) attached to the carbon matrix mainly by a C—O—P bond and, to a lesser degree, by a C—P bond. The presence of the condensed phosphates in the structure of the carbon determines the hydrophilicity and the acidic characteristics and also the ability to absorb cations. The acidic characteristics of the surface of the phosphorylated carbons gives rise to their high catalytic activity in acid catalysis. The presence of the phosphates/polyphosphates improves the electrochemical characteristics of carbon materials for use as electrodes in supercapacitors. Potential fields for the practical application of phosphorylated carbons are the purification of water from heavy metal ions, the acceleration of reactions of the acid–base type, and the accumulation and storage of energy in double-layer capacitors.     

Structure,mechanical, and tribological characteristics of polyurethane modified with nanodiamonds

The effect of modifying additives based on detonation nanodiamonds on the tribological characteristics of polyurethane rubber is studied. Introduction of modifying additives based on detonation nanodiamonds (0.5 wt %) leads to a marked improvement in the antifriction and wear-resistance characteristics under conditions of boundary sliding friction for steel and for lubrication with water. The attained tribological characteristics (total energy loss for friction, weight loss of polymer during tribological contact, maximum admissible working pressure) are well (∼300%) above the corresponding characteristics of foreign analogs. Changes in the tribological characteristics of the formed nanocomposite material are observed, but the elastic and strength characteristics remain unchanged.     

Thermochemistry of Solution and Solvation of CuCl2 in Water-Hexamethylphosphoric Triamide Mixtures at 298 K

The thermochemical characteristics of solution of copper(II) chloride in the mixed solvent waterhexamethylphosphoric triamide were obtained from calorimetric data, and corresponding solvation characteristics were calculated. The enthalpy characteristics of solvation of the Cu^{2 +} ion in this solvent were obtained and discussed.     

Enthalpy Characteristics of Solution and Solvation of CuCl2 in Water-Acetonitrile Mixtures at 298.15 K

Thermochemical characteristics of solution of copper(II) chloride were found from calorimetricdata, values describing solvation processes in a water-acetonitrile mixed solvent were calculated for theentire range of compositions. Enthalpy characteristics of solvation of individual Cu^{2 +} ions in water-aceto-nitrile mixtures were found and analyzed.     

Determination of thermodynamic characteristics of heteromolecular association process,freed of contribution of specific solvation

The problem of considering separately the contributions of the universal and specific solvation of components of a system to the thermodynamic characteristics of a heteromolecular association process are discussed. An expression is presented for calculating the equilibrium constants of the process of formation of addition products under universal solvation conditions, where the change in all of the thermodynamic characteristics of the process is determined by only a change in the dielectric constant of the medium.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 22, No. 2, pp. 248–252, March–April, 1986.     

Derivation of donor and acceptor characteristics of addends from spectral data

The donor and acceptor characteristics of addend orbitals are discussed via MO localized largely on the metal atom in groups of ML₆ type in which M has open electron shells. The energy characteristics of these MO are derived from the tetragonal splitting of the T_1g and T_2g terms in groups of MX₄L₂ or MX₅L types for Cr³⁺ and Ni²⁺, taken in conjunction with the overlap integrals for the corresponding orbitals and the spectrochemical parameters (10Dq) for groups of ML₆ type. The spatial characteristics (delocalization coefficients) of the MO may be deduced from the nepheloxetic effects and also from the energy characteristics. The corresponding characteristics have been calculated for halides, amines, water, urea, oxalate, etc.     

Effect of fullerene C60 as a branching center on molecular and polarization properties of star-shaped polystyrenes

The behavior of molecules of a star-shaped six-arm polystyrene with a covalently bound fullerene C₆₀ as a branching center was studied by viscometry and by measuring the electrooptical Kerr effect and the dielectric polarization in solutions. It was shown that polarization and electrooptical characteristics of a fullerene-containing polystyrene (C₆₀ ～ 3 wt %) differ by an order of magnitude or even greater from the corresponding characteristics of the parent polymer. A comparison of the above properties with the analogous characteristics of the model hexaadduct (the products of reaction between octyllithium and fullerene C₆₀) demonstrated that a difference in the behavior of the star-shaped polystyrene and its parent analog is associated with the structural features of the branching center, among which is the occurrence of six proton addends that are bonded rather weakly to the fullerene cage in the hexaadducts under study.     

Effect of salts on local mobility and rheological properties of micelles of new long-chain surfactant

The effects of organic (sodium salicylate) and inorganic (KCl) salts on the rheological properties of micellar solutions and the local characteristics (local mobility and ordering) of micelle cores is studied for a cationic surfactant containing a long (C₁₈) unsaturated alkyl radical. The polar head of the surfactant contains two hydroxyl groups. The local characteristics are determined employing spin probe ESR spectroscopy. It is shown that the incorporation of a salt into a micellar solution reduces the local mobility of radicals of surfactant molecules in micelle cores and increases their local Lordering and the viscosity of the solution. Sodium salicylate has a stronger influence on the solution viscosity and the local characteristics of micelle cores than KCl does. Variations in the local characteristics of micelle cores under the action of the salts are in close correlation with variations in the rheological properties of the micellar solutions.     

Liquid crystal alignment on a ZrO2 thin film as a function of ion beam incident angle

Nematic liquid crystal alignment capabilities and electro-optical performance characteristics have first been embodied in a ZrO₂ layer using ion-beam irradiation. The study demonstrates that liquid crystal layers can be aligned homogeneously as a function of the incident angle of the ion beam device, which causes a uniform dense plasma. X-ray photoelectron spectroscopy indicated that full oxidation of the ZrO₂ thin-film surfaces was produced by ion irradiation, shifting the Zr 3d spectra to lower binding energies. In addition, the electro-optical performance characteristics of twisted nematic cells on a ZrO₂ thin-film layer after ion beam irradiation showed similar characteristics to those of a rubbed polyimide cell.     

The effect of irregularity on the dielectric dispersion characteristics of spherical cellular suspension

The dielectric dispersion characteristics of cellular suspensions are fundamentally determined based on the analogy to composite dielectric materials when periodically and discrete arrangement of cells is assumed. However, under native physiological conditions, when flocculation and clamping events usually occur, those assumptions are usually not valid. In the framework of this study, an examination of irregularity effect on the dispersion characteristics of spherical cellular suspensions is presented. Here, the permittivity spectra of the suspensions have been determined by both measurements of living K562 cell suspensions and finite numerical simulations. Based on the measured and simulated spectra, the dispersion characteristics of the suspensions, for several destinies and arrangements of cells, have been quantitatively analyzed using the Havriliak–Negami empirical formula. Generally, a strong correlation between the low dispersion characteristics was observed as the concentration and density of the cells was increased. In addition, all characteristics found to be significantly deviated in comparison to the characteristics of a periodically arrayed suspension. However, when low-dense arrangement was assumed, the correlation found to be much lower when all characteristics found to be less perturbated. Based on a simple model of interacting cells, it is suggested that those deviations are related to intercellular interactions between adjacent cells.     

A study of dosimetry characteristics of GAF DM-1260 radiochromic films

The dosimetric characteristics of gamma-ray, x-ray and electron irradiated GAF-DM-1260 radiochromic film have been studied, and the dependence of radiation-induced film absorbance on irradiation temperature and reading temperature and the changes of the absorption spectrum peaks at different reading temperatures and absorbed doses (3×10¹ to 5×10⁴ Gy) are reported. It is shown that the responses are independent of the gamma-ray dose rate in the dose rate range considered in the experiment. The film response characteristics as a function of the absorbed dose to ⁶⁰Co gamma irradiation at the spectrophotometric reading wavelengths of 400, 580, 600, 650 and 670 nm and two absorption peaks are determined as well as the response characteristics to the electron beam at the reading wavelength of 400 nm. The results demonstrate that the film responses to gamma rays, x-rays and a 3.8 MeV electron beam are equivalent, over the absorbed dose rate range of about 0.8 Gy·s⁻¹ to 5×10⁸ Gy·s⁻¹. Some advice and points of view about the dosimetric characteristics of the film and some problems in usage are provided according to the experimental results.     

Influence of the nature of contacts on the dark and photovoltaic characteristics of the Schottky junction between n-doped silicon and poly(4,4′-dipentoxy-2,2′-bithiophene)

The dark and photovoltaic characteristics of the Schottky junction between n-doped silicon and a conducting polymer in its oxidised form, poly(4,4′-dipentoxy-2,2′-bithiophene), have been determined as a function of the nature of the electrical contact on the polymer side. It was found that the dark and photovoltaic performances of the device depended strongly on this contact. An aluminium contact is oxidised by the polymer and an aluminium oxide film forms between the polymer and the contact through which the forward current is controlled by charge injection. The devices assembled with indium tin oxide, platinum and gold contacts show better characteristics than the ones with aluminium contact; in the last three cases, however, a faradic charge transfer reaction on the contact, probably the oxidation of some amount of water contained in the polymer, affects the characteristics of the junction. Received: 27 December 1997 / Accepted: 24 April 1998     

The applicability of radiotracers for the investigation of the distillation of hydrocarbons

The use of radioactive tracers provide valuable methods for the investigation of distillation processes and have been applied to determine the characteristics of material streams, the dynamics of flowing phases and the compositions in various parts of the distillation equipment. A method is proposed for testing individual radiotracers employed for the investigation of the distillation of hydrocarbons. The method consists in laboratory-scale distillation of a tracer together with a multicomponent hydrocarbon mixture, namely a gasoline fraction. The purification efficiency, distillation characteristics, and effective radiochemical purity of several tracers (reactor activated bromobenzene and synthesized C₃H₇ ⁸²Br, C₄H₉ ⁸²Br, C₅H₁₁ ⁸²Br) have been investigated. The distillation characteristics of bromohydrocarbons labelled with⁸²Br and selected hydrocarbons tagged with¹⁴C (benzene and cumene) have been compared. The radiotracers investigated were employed for the determination of the hydrodynamic parameters of hydrocarbon distillation in laboratory packed columns and a commercial distillation tower.     

Contribution to the Achievement of a New Type of Electrochemical Sensor for Oxygen,Based on Electrolyte in Non-Aqueous Medium

Abstract

A new type of amperometric sensor for oxygen, having a O. 1M solution of LiCl in ethanol as internal electrolyte, was developed

The response characteristics of this sensor have been improved in comparison with similer sensors based on internal electrolyte in aqueous media, reported in literature. Preliminary results on the response characteristics of the new sensor are reported.     

Rapid Isolation of the Trichoderma Strain with Higher Degrading Ability of a Filter Paper and Superior Proliferation Characteristics Using Avicel Plates and the Double-Layer Selection Medium

The cost of cellulase is still a problem for bioethanol production. As the cellulase of Trichoderma reesei is applicable for producing ethanol from cellulosic materials, the cellulase productivity of this fungus should be increased. Therefore, we attempted to develop a system to isolate the strain with higher degrading ability of a filter paper and superior proliferation characteristics among the conidia treated with the mitotic arrester, colchicine. When green mature conidia of T. reesei RUT C-30 were swollen, autopolyploidized, and incubated in the double-layer selection medium containing Avicel, colonies appeared on the surface earlier than the original strain. When such colonies and the original colony were incubated on the Avicel plates, strain B5, one of the colonies derived from the colchicine-treated conidia, showed superior proliferation characteristics. Moreover, when strain B5 and the original strain were compared in the filter paper degrading ability and the cellulose hydrolyzing activity, strain B5 was also superior to the original strain. It was suspected that superior proliferation characteristics of strain B5 reflects higher filter paper degrading ability. Thus, we concluded that the Trichoderma strain with higher degrading ability of a filter paper and superior proliferation characteristics can be isolated using Avicel plates and the double-layer selection medium.     

Cetane number and thermal properties of vegetable oil,biodiesel, 1-butanol and diesel blends

Vegetable oil derived fuels for diesel engines are becoming important as alternative to petroleum diesel fuels due to their environmental friendliness and availability. Ignition quality in compression ignition (CI) engines is influenced by thermal characteristics and fuel properties. In this study, the effects of vegetable oil transesterification and vegetable oil–1-butanol-diesel blends on fuel properties, cetane number (CN) and thermal characteristics were experimentally investigated. Methyl esters (biodiesel) and 10% vegetable oil–10% 1-butanol–80% diesel blends were prepared from croton oil (CRO), coconut oil (COO) and jatropha oil (JAO). CN was measured in a CFR F-5 engine, and a thermogravimetric analysis (TG), as well as the determination of fuel properties of vegetable oils, biodiesels and blends was carried out. It can be observed for vegetable oils that they possess low volatility characteristics, low CN and high viscosity different from those of biodiesels, blends and diesel fuel. It was observed that biodiesels and blends exhibit similarities with diesel in the fuel characteristics, CN and TG curves.     

Fabrication of core-shell structured nanoparticle layer substrate for excitation of localized surface plasmon resonance and its optical response for DNA in aqueous conditions

LSPR from nanostructured noble metals such as gold and silver offers great potential for biosensing applications. In this study, a core-shell structured nanoparticle layer substrate was fabricated and the localized surface plasmon resonance (LSPR) optical characteristics were investigated for DNA in aqueous conditions. Factors such as DNA length dependence, concentration dependence, and the monitoring of DNA aspects (ssDNA or dsDNA) were measured. Different lengths and concentrations of DNA solutions were introduced onto the surface of the substrate and the changes in the LSPR optical characteristics were measured. In addition, to monitor the changes in LSPR optical characteristics for different DNA aspects, a DNA solutions denatured by means of heat or alkali were introduced onto the surface, after which optical characterization of the core-shell structured nanoparticle substrate was carried out. With this core-shell structured nanoparticle layer for the excitation of LSPR, the dependence upon specific DNA conditions (length, concentration, and aspect) could be monitored. In particular, the core-shell structured nanoparticle layer substrate could detect DNA of length 100-5000 bp and 400-bp DNA at a concentration of 4.08 ng mL⁻¹ (1 × 10⁷ DNA molecules mL⁻¹). Furthermore, the changes in LSPR optical characteristics with DNA aspect could be monitored. Thus, LSPR-based optical detection using a core-shell structured nanoparticle layer substrate can be used to determine the kinetics of biomolecular interactions in a wide range of practical applications such as medicine, drug delivery, and food control.     

Electrochemical Characteristics of Negative Electrodes Made of Ozone-Treated Graphite for Lithium-Ion Batteries

Electrochemical characteristics of negative electrodes made of graphite treated in ozone–oxygen environment are studied in an operating lithium-ion battery. Successively treating graphite with ozone and then with a sec-butyllithium solution in cyclohexane dramatically reduces the irreversible capacity and stabilizes discharge characteristics of graphite electrodes cycled in a propylene carbonate-based electrolyte. An ozone–oxygen gaseous mixture containing 5 vol % O₃is most effective for the stabilization. According to IR spectroscopy, the treatment gives rise largely to –COLi groups, which ex situform a passivating solid-electrolyte film on the graphite surface. The film hampers the electroreduction of the organic solvent and reduces the irreversible lithium consumption.