Tests of biocompatibility of α-tocopherol with respect to the use as a stabilizer in ultrahigh molecular weight polyethylene for articulating surfaces in joint endoprostheses

To inhibit the oxidation in vivo of hip-cups made of ultrahigh molecular weight polyethylene (UHMW-PE), the natural antioxidant -tocopherol was added to the polymer. The added -tocopherol may however undergo chemical transformations during manufacturing and sterilization by -irradiation of hip-cups which may differ from human metabolism. Therefore, the question of the biocompatibility of the respective transformation products was investigated on test samples, which were prepared under the same conditions as applied for the production and sterilization of hip-cups. Thin plates (25×18×2 mm³) were fabricated out of test samples to investigate the cytotoxic activity according to EN 30993-5. In cytotoxicity testing, proliferation, mitochondrial activity and membrane integrity were not influenced by the material. In contrast, cell adhesion and cell spreading were diminished as shown with hemalum staining. In order to investigate the genotoxicity, the -tocopherol and its transformation products were extracted from test specimens by n-heptane at 185 °C under nitrogen atmosphere. Then the n-heptane was evaporated in vacuo and the remaining -tocopherol and its transformation products were dissolved in DMSO. The genotoxicity of this extract was then tested by the Ames-test according to DIN UA 12 (1995), which showed no indication for genotoxic activity.     

The kinetics of surface craze growth in polycarbonate exposed to normal heptane

A variable radius of curvature strain-bending apparatus has been used to investigate the propagation of surface crazes in polycarbonate exposed to n-heptane. It was found that for crazes growing in a zone free of other crazes, the growth rate was linear at constant temperature and exponentially dependent upon temperature. An activated-state theory was developed to describe the kinetics of growth in terms of two parameters,B ^–1, a characteristic strain constant that was independent of test variables, andA, a characteristic growth-rate parameter that varied exponentially with temperature. A strain-temperature equivalence principle was adopted to predict the crazing behaviour over a range of temperatures and strains. A critical strain was defined in terms of a maximum allowable craze growth rate.     

Synthesis of spherical NiO nanoparticles through a novel biosurfactant mediated emulsion technique

Spherical nickel oxide nanoparticles were synthesized by microemulsion technique using rhamnolipids as the surfactant along with n-heptane and water. Nickel hydroxide (Ni(OH)₂) particles were first formed which were then calcined to obtain nickel oxide (NiO) particles. Scanning Electron Microscopy (SEM) studies revealed that the synthesized nickel hydroxide particles were spherical in shape with stacked lamellar sheets. Nickel hydroxide was converted to nickel oxide by calcinations at 600 °C for 3 h and was confirmed by X-ray Diffraction (XRD) analysis. Transmission Electron Microscopy (TEM) showed that the nickel oxide particles were crystalline and of uniform size. The effect of pH on particle size was investigated and it was found that the particle size decreased from 86 ± 8 nm at pH 11.6 to 47 ± 5 nm at pH 12.5. A novel method using rhamnolipid biosurfactant for microemulsion synthesis has been demonstrated which offers an eco-friendly alternative to conventional microemulsion technique based on organic surfactants.     

Synthesis of metal nitrides and carbide powders by a spark discharge method in liquid media

Metal nitrides and carbides powders were synthesized by the spark discharge method in liquid ammonia at 100 °C and 11 kV of the spark discharge voltage and in n-heptane at 25 °C and 7.5 kV using the pellets of aluminum, titanium, iron and chromium as the starting material. The main products were AlN, TiN_0.51, -Fe, -Cr₂N in liquid ammonia, and Al₄C₃, TiC, -Fe, Fe₂C and Cr₇C₃ in n-heptane. The agglomerated particle size decreased with increasing melting point of the metal used as the starting material.     

Solvent induced crystallization in poly(aryl-ether-ether-ketone)

Sorptions of methylene chloride and methylene chloride/n-heptane liquid solutions in poly(aryl-ether-ether-ketone) (PEEK) are analysed and interpreted assuming multiple transport mechanisms. The presence of the highly interacting methylene chloride is responsible for anomalous sorption behaviours. PEEK films immersed in methylene chloride poor n-heptane solutions sorb by non-ideal Fickian diffusion, while limiting Case II and diffusion controlled swelling accompany equilibration in progressively richer methylene chloride solutions. The optical microscopy observation of cryogenically fractured samples conditioned in pure liquid methylene chloride at 5, 20 and 36 ° C for different times, revealed the presence of a sharp moving front. Differential scanning calorimetry (DSC) indicates that the glass transition temperature of the penetrated shells was always lower than the treatment temperature. The high levels of solvent swelling and plasticization were probably responsible for the crystallinity detected in DSC thermograms and wide angle X-ray scattering (WAXS) diffractograms of the solvent treated and initially amorphous samples. The differences of WAXS diffractograms of samples crystallized by immersion in methylene chloride at 5 and 36 ° C for various times and by thermal treatment are discussed. Increasing levels of crystallinity were induced in the samples equilibrated in progressively richer methylene chloride solutions.     

The preparation of iron (III) oxide nanoparticles using W/O microemulsion

Iron (III) oxide, Fe₂O₃, nanoparticles were prepared using W/O microemulsion as the reactor. W/O microemulsion was formed using n-heptane as oil phase, water and AOT as the surfactant under the specific composition. Iron (III) Chloride was used as a starting material and Ammonium hydroxide was a precipitating agent. Fe₂O₃, nanoparticles were then produced in situ the water core. Size of particles could be adjusted by the water content of the mixtures. The higher the water content, the bigger the particle size. The average size of the nanoparticles obtained was smaller than 100 nm. Moreover, Fe₂O₃ produced by this method was hematite with hexagonal in structure.     

An apparatus for study of liquid specific heat at high state parameters in the monotonic heating regime

Experimental apparatus is described and results of a study of thermal conductivity of n-heptane are presented.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 37, No. 4, pp. 677–683, October, 1979.     

Evaluation of commercial adsorbents and their application for desulfurization of model fuel

The removal of dibenzothiophene from model fuel was carried out by adsorption on commercially available adsorbents including an activated carbon, aluminum oxide, 13X and Y zeolite. Activated carbon was SOLCARB^TM C3 which was grinded from its original particle size 1.0–2.0 mm to the 0.40–0.80 mm, while aluminum oxide Selexsorb CDX, 13X zeolite MSE 13X and Y zeolite HSZ-320NAA were used in their as delivered particle size ranges of 2.7–3.0, 1.6, and 300–600 nm, respectively. Adsorption experiments were carried out in batch mode at 24.5 ± 0.7°C using model fuel comprising cyclo-hexane, n-heptane, n-octane and dibenzothiophene in the concentration range of 0.48–42.91 mg/g. The experimental data was used to compare applied adsorbents and to carry out equilibrium characterization and kinetic analysis of the adsorption process. The evaluation of the tested adsorbents showed that the best adsorptive performance was achieved by the Y zeolite. The analysis of the adsorption equilibrium data and the kinetic analysis showed that of the applied models the best fits to the experimental data were achieved by the Sips and Ritchie models, respectively.     

W/O型微乳液碳化法制备超细Al(OH)3与Al2O3粉体的研究

PEG+正丁醇/正庚烷/水溶液(NaAlO2)体系W/O微乳液中通入CO2,焙烧后制备出了纯度>99.9%、粒度<80nm的Al(OH)3与Al2O3纳米粉体,实验结果表明,乳化温度、表面活性剂与助表面活性剂之比及水相的浓度是决定粉体粒度的主要影响因素.     

Characteristics of self-excited thermoacoustic oscillations in heat transfer to n-heptane

The speed of sound and wavelength are determined experimentally for thermoacoustic oscillations self-excited in connection with heat transfer to a flow of n-heptane under supercritical pressure conditions.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 33, No. 1, pp. 21–25, July, 1977.     

Development of high-frequency pressure oscillations during heat transfer with forced liquid motion

This article presents the results of an experimental investigation of high-frequency pressure pulsations developing during heat transfer to n-heptane with different flow speeds and pres-sures.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 17, No. 3, pp. 486–490, September, 1969.     

Some thermodynamic properties of n-heptane on the saturation line

The results of measurements of the speed of sound in n-heptane on the saturation line are presented. The values obtained are used to calculate a series of thermodynamic quantities.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 15, No. 5, pp, 890–892, November, 1968.     

Oxygen-sensing properties of ormosil hybrid materials doped with ruthenium(II) complexes via a sol-gel process

Organically modified silicate (ormosil) materials doped with [4,4′-dimethyl-2,2′-bipyridine-bis(2,2′-bipyridine)] ruthenium(II) dichloride ([Ru-mbpy]²⁺) and [4,4′-dimethylformate-2,2′-bipyridine-bis(2,2′-bipyridine)] ruthenium(II) dichloride ([Ru-dmfbpy]²⁺) were prepared by a sol-gel procedure for oxygen-sensing applications. The results indicated that the concentrations of the Ru(II) diimine complexes obviously influenced the linearity of Stern-Volmer plots (I₀ /I vs. O₂%). The best suitable concentrations of [Ru-mbpy]²⁺ and [Ru-dmfbpy]²⁺ in the sol for oxygen sensors were found to be 1.0 × 10^− 3 M and 2.5 × 10^− 3 M, respectively. The fluorescence quenching time and recovery time of oxygen sensor doped with [Ru-mbpy]²⁺ (1.0 × 10^− 3 M) were 18 s and 38 s and those doped with [Ru-dmfbpy]²⁺ (1.0 × 10^− 3 M) were 13 s and 32 s, respectively. The oxygen sensor based on Ru(II) complex modified by esterification demonstrated excellent linear calibration relationship and improved long-term stability.     

Optical and electroluminescent properties of samarium complex-based organic light-emitting diodes

The optical and electroluminescent (EL) properties of newly synthesized tris(hexafluoroacethylacetonato)(phenanthroline)samarium(III)mono-methanol [Sm(hfa)₃(phen)₂MeOH]-based organic light-emitting diodes (OLEDs) were investigated. The as-prepared photoluminescence (PL) spectrum of Sm(hfa)₃(phen)₂MeOH-doped PMMA film exhibits the peaks at the wavelength around 564, 598, 645 and 710 nm which correspond to the ⁴G_5/2 → ⁷H5_/2, ⁴G_7/2 → ⁷H_7/2, ⁴G_5/2 → ⁷H_9/2 and ⁴G_5/2 → ⁷H_11/2 transitions of the Sm³⁺ ion, respectively. The best organic light-emitting device performance is obtained for a device using 8 wt.% Sm(hfa)₃(phen)₂MeOH and 40 wt.% 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4,-oxadiazole doped in poly(N-vinylcarbazole) as a emitting layer. The optimal device exhibits maximum luminance of 135 candela (cd)/m² at the current density of 0.16 A/cm², with current efficiency of 0.1 cd/A at the current density of 0.08 A/cm². The EL spectrum from optimal device has the Commission Internationale De L'Eclairage (CIE) coordinate of (0.60, 0.36).     

Co (II) phthalocyanine - amine functionalized graphene oxide as a solid base catalyst for the oxidation of thiols

A noncovalent attachment of propylamine (PA), butylamine (BA), ethylenediamine (EDA) and tetramethylenediamine (TMD) - functionalized Graphene oxide (GO) to cobalt (II) phthalocyanine (CoPc) as a novel solid base catalyst was synthesized by mixing method. The synthesized catalysts were characterized using UV-vis, XRD, FTIR, FESEM, EDAX, MAP and HRTEM analyses. The catalytic performances of the synthesized catalyst were evaluated for the oxidation of various thiols in n-heptane under alkali free condition, and were in the following order: EDAGO-CoPc > TMDGO-CoPc > PAGO-CoPc > BAGO-CoPc. For better investigation, the potential of EDAGO-CoPc catalyst was investigated for thiols oxidation in real gasoline. According to the results, 96.55% thiols were removed from real gasoline over the EDAGO-CoPc catalyst. After eight runs of experiment, no significant change was observed in the activity of EDAGO-CoPc catalyst for thiols oxidation in real gasoline.     

Kinetics and Mechanism of Np(IV) Oxidation with Nitric Acid

Neptunium (IV) is oxidized to Np(V) with nitric acid in the presence of U(VI) under conditions of low acidity (<∼0.1 M). The reaction rate is described by the equation d[Np(V)]/dt = k ₁[Np(IV)]/[H⁺]² + k ₂[Np(IV)]²[U(VI)]/[H⁺]³, in which k ₁ = (2.0±0.3) × 10⁻⁵ mol² l⁻² min⁻¹ and k ₂ = (5.50±0.47) × 10⁻² mol l⁻¹ min⁻¹ at 50°C and solution ionic strength μ = 0.5. The activation energies of the two pathways are 148±31 and 122±12 kJ mol⁻¹. The reaction along the main pathway (with the rate constant k ₂) is limited by disproportionation of Np(IV) involving NpOH³⁺ and Np(OH)₂UO ₂ ⁴⁺ complex ions.__________Translated from Radiokhimiya, Vol. 47, No. 3, 2005, pp. 228–233.Original Russian Text Copyright © 2005 by Koltunov, Taylor, Marchenko, Savilova, Dvoeglazov, Zhuravleva.     

Coprecipitation of microamounts of radionuclides on chitosans of various molecular weights in solutions

Coprecipitation of ²³³U, ²³⁹Pu, ²⁴¹Am, ¹⁵²Eu, ⁹⁰Sr, ⁹⁰Y, and ⁶⁰Co on chitosans of various molecular weights (MW) was studied. Low-molecular-weight chitosan (LMWC) with MW of 5 kDa (5 × 10³ g mol⁻¹) proved to be a more effective coprecipitant than high-molecular-weight chitosan (HMWC) with MW of 700 kDa (7 × 10⁵ g mol⁻¹). With HMWC, the degree of coprecipitation (α) was 80% for ¹⁵²Eu and ⁹⁰Y, 99% for ²³³U and ²⁴¹Am, and 85% for ²³⁹Pu. For ⁶⁰Co, α monotonically increased with an increase in the chitosan concentration in solution and reached 40% at [HMWC] = 5 g l⁻¹. For ⁹⁰Sr, α did not exceed 3% in the entire examined range of chitosan concentrations. With LMWC, the α values for An, ¹⁵²Eu, and ⁹⁰Y differed insignificantly (92–99%). For ⁶⁰Co and ⁹⁰Sr, α increased to 40% in the range of chitosan concentrations from 0 to 1 g l⁻¹. The presence of inorganic salts in solution considerably decreases α of UO₂²⁺ with chitosans but does not noticeably affect the behavior of Am, Pu, and Eu. The effect of salts on the efficiency of ²³³UO^2/2+ coprecipitation on HMWC decreases in the order Na₂SO₄ > NaCl > Na₂CO₃ > NaNO₃ > Na₃PO₄. Based on the results obtained, a procedure suitable for expedition conditions was developed for preconcentration of Pu from seawater on chitosan, with simultaneous separation of Pu from U, for radioecological monitoring of natural waters. The specific activity of Pu in samples of near-bottom seawater of gulfs of the Novaya Zemlya archipelago was (150–170) ± 20 mBq m⁻³. The results are well consistent with the published data.     

Synthesis of Si-C nanostructures by laser ablation of silicon target in n-heptane vapor

Controllable synthesis of Si-C nanostructures was realized in a laser ablation system by adopting solid silicon target and n-heptane vapor as starting materials. Ultrafine SiC nanocrystals and graphite-coated SiC nanocrystals were synthesized with the laser frequency of 1 Hz and 20 Hz, respectively. According to the real-time observation on the plasma evolvement, we proposed a formation mechanism of Si-C nanostructure related to vapor-phase reaction. Our method can be extended to other material systems for diverse novel nanostructures.     

Preparation and upconversion property of TeO2:Er/Yb nanoparticles

Different crystal structure of TeO₂ nanoparticles were used as the host materials to prepare the Er³⁺/Yb³⁺ ions co-doped upconversion luminescent materials. The TeO₂ nanoparticles mainly kept the original morphology and phase after having been co-doped the Er³⁺/Yb³⁺ ions. All the as-prepared TeO₂:Er³⁺/Yb³⁺ nanoparticles showed the green emissions (525 nm, 545 nm) and red emission (667 nm) under 980 nm excitation. The green emissions at 525 nm, 545 nm and red emission at 667 nm were attributed to the ²H_11/2 → ⁴I_15/2, ⁴S_3/2 → ⁴I_15/2 and ⁴F_9/2 → ⁴I_15/2 transitions of the Er³⁺ ions, respectively. For the α-TeO₂:Er³⁺/Yb³⁺ (3/10 mol%) nanoparticles, three-photon process involved in the green (²H_11/2 → ⁴I_15/2) emission, while two-photon process involved in the green (⁴S_3/2→⁴I_15/2) and red (⁴F_9/2 → ⁴I_15/2) emissions. For the β-TeO₂:Er³⁺/Yb³⁺ (3/10 mol%) nanoparticles, two-photon process involved in the green (²H_11/2 → ⁴I_15/2), green (⁴S_3/2 → ⁴I_15/2) and red (⁴F_9/2 → ⁴I_15/2) emissions. It suggested that the crystal structure of TeO₂ nanoparticles had an effect on transition processes of the Er³⁺/Yb³⁺ ions. The emission intensities of the α-TeO₂:Er³⁺/Yb³⁺ (3/10 mol%) nanoparticles and β-TeO₂:Er³⁺/Yb³⁺ (3/10 mol%) nanoparticles were much stronger than those of the (α + β)-TeO₂:Er³⁺/Yb³⁺ (3/10 mol%) nanoparticles.     

A Spectrophotometric Study of the Interaction of Np(VI) with Orthosilicic Acid and Polymeric Silicic Acids in Aqueous Solutions

The interaction of NpO ₂ ²⁺ ions with orthosilicic acid Si(OH)₄ and polymeric silicic acids (PSAs) in aqueous solutions was studied spectrophotometrically. The interaction at pH ≤ 4.5 is described by the equation NpO ₂ ²⁺ + Si(OH)₄ = NpO₂OSi(OH) ₃ ⁺ + H⁺ with the equilibrium constant log K = − 2.88±0.12 at the ionic strength I = 0.1–0.2 (log K ⁰ = −2.61±0.12 recalculated to I = 0); the stability constant of the complex NpO₂OSi(OH) ₃ ⁺ (I = 0) is log β⁰ = 7.20± 0.12. At pH > 5, a second complex of NpO ₂ ²⁺ with PSAs of the presumed composition NpO₂(≡ SiO)₂(≡SiOH) _{m − 2}, where (≡SiOH)_m denotes a PSA molecule with surface Si-OH groups, is formed. The absorption spectra of the complexes NpO₂OSi(OH) ₃ ⁺ and NpO₂(≡ SiO)₂(≡SiOH) _{m − 2} were obtained. In contrast to the hydroxo complexes, they have pronounced maxima at 560 – 600 nm with the molar extinction coefficients of about 25–30 l mol⁻¹ cm⁻¹, which is several times higher compared to the Np(VI) aqua ion.__________Translated from Radiokhimiya, Vol. 47, No. 4, 2005, pp. 322–327.Original Russian Text Copyright © 2005 by Yusov, Shilov, Fedoseev, Astafurova, Delegard.