Protective and water-repellent properties of alkylcarboxylic and alkylphosphonic acid films on technically pure magnesium

The formation of superhydrophobic coatings using low-toxicity corrosion inhibitors is a promising method for corrosion protection of metals and alloys. In this study, the effects of surface roughness and the of the adsorbed substance structure on wettability and corrosion resistance of commercially pure magnesium were investigated. Surface roughness was created by three different methods: paper grinding,etching in nitric acid solution and laser treatment. Oleic, stearic and octadecylphosphonic acids were investigated as potential surface modifiers for the formation of corrosion resistant superhydrophobic coatings. It has been shown that the protective and hydrophobic properties of acid films on magnesium, as well as their stability, are determined by both the initial surface morphology and the nature of the inhibitors.Experimentally, the laser treatment was found to be preferable to mechanical and chemical surface preparation and the best hydrophobic agent among the studied acids is phosphonic acid. The most stable films with excellent superhydrophobic and protective properties in atmospheres of high humidity and salt spray clamber are formed in a solution of 0.001 M octadecylphosphonic acid on the surface of magnesium with high roughness. In addition, the effect of vinyltrimethoxysilane on the protective and hydrophobic properties of stearic acid and octadecylphosphonic acid films was investigated. The results of direct corrosion tests and wetting contact angle degradation kinetics studies showed that the protective and hydrophobic properties of stearic acid can be enhanced by its layer-by-layer adsorption with silane.They practically reach the parameters of octadecylphosphonic acid.

Preparation and hydrogen permeation properties of BaCe_(0.95)Nd_(0.05)O_(3-δ) membranes

Dense mixed proton and electron conducting membrane made of BaCe0.95Nd0.05O3-δ （BCNd5） was prepared by pressing followed by sintering. X-ray diffraction （XRD） was used to characterize the phase structure of both the powder and the sintered membranes. The microstructure of the sintered membranes was studied by scanning electron microscopy （SEM）. Hydrogen permeation through the BCNd5 membrane was studied using a high temperature permeator. The hydrogen permeation fluxes under wet conditions are higher than those under dry conditions, which is due to H^＋ hopping via surface OH groups. At 925℃, a hydrogen permeation flux of 0.02 mL/min cm^2 was obtained under wet condition, which recommends BCNd5 as a potential material for hydrogen-selective membranes.

Nanoparticles of Palladium, Platinum and Silver:Incoporation into Perfluoro-Sulfonated Membrane MF-4SK and Ionic Nafion

The purpose of the investigation is the study of the physico-chemical properties and electro-catalytic characteristics of the Nafion and MF-4SK membranes with the author’s nanoparticles (A. Revina, 2008) incorporated into the perfluoro- sulphonated cationic membranes. An important advance in the creation of new nano-composite materials with poly-functional activity is the inclusion of nanoparticles of various metals (Pd, Pt, Ag) in these membranes. Polymer ion exchange membranes represent widely applicable materials in various areas of modern nanotechnologies. The obtained nanocomposites on the base of included nanoparticles have the perspective properties and polyfunctional activity for the applications.

Change in the Pore Structure of Carbon-Carbon Composites during Successive Stages of High-Pressure Impregnation and Heat Treatment

Pore structure of C/C （Carbon-Carbon） composite after several stages of pitch impregnation under the high pressure and heat treatment was investigated by means of low temperature nitrogen adsorption and the standard contact porosimetry. Total pore volume, pore size distribution and specific surface area were calculated for samples of composite after several successive stages of treatment. The radius of pores presented in the material changes from 1 nm to 90 tam. Total pore volume and specific surface area both decrease after successive stages of pitch impregnation under the pressure, whereas heat treatment up to 1,750 ℃ and 2,000 ℃ leads to creation of some porous space and pore volume expansion. The bulk porosity of C/C composite comes down from 33.7% to 13.7% after the serial stages of treatment and the specific surface area is reduced by half compared to the initial material.

Clearing of the Radioactive Liquid Waste from Oils and Oil Products by UV-Radiation at NPPs

The basic methods of concentration and purification of liquid radioactive waste on the nuclear power plant are distillation and ionic exchange. During vaporization of oil waste products and the fulfilled washing solutions the part of oil passes into a condensate. Clearing of such condensate on ion-exchanged filters results to oiling of ion-exchanged materials and to decrease number of filter cycles. Due to the often regeneration of ion-exchanged filters additional volumes of waste products as the fulfilled reclaiming solutions, washing and loosening waters are formed. The attention of scientists was involved with methods of clearing of water environments from the organic substances, based on deep oxidizing transformations of hydrocarbons into carbonic gas and water. From processes of oxidation of hydrocarbons up to CO2 and H2O, sold at moderate conditions, our attention has involved photochemical oxidation with the help of UV-radiation.

Non-Local and Memory Character of Frictional Energy Dissipation on Atomic Scale

The traditional description of atomic-scale friction, as investigated in Friction force microscopy, in terms of mechanical stick-slip instabilities appears so successful that it obscures the actual mechanisms of frictional energy dissipation. More sophisticated theoretical approach, which takes into account damping explicitly, reveals the existence of some hidden, unexplained problems, like the universal nearly-critical damping and unexpectedly high value of the dissipation rate. In this paper, we combine analysis in the framework of nonequilibrium statistical mechanics with simple atomistic modeling to show that the hidden problems of atomic scale friction find their origin in the nontrivial character of energy dissipation that is non-local and dominated by memory effects, which have not been addressed before in the context of dry, atomic-scale friction.

Gas-Phase Conversion of the U(VI), Sr, Mo, and Zr Oxides in Nitrating Atmosphere

The gas-phase conversion of U3O8, MoO3, SrO, and their mechanical mixtures, and also of ZrO2 into water-soluble compounds in the atmosphere of (NOx + vapor H2O) or HNO3 (vapor) was studied. In the course of gas-phase conversion, U3O8 and SrO transform into water-soluble compounds (nitrates, hydroxonitrates), whereas MoO3 and ZrO2 undergo no changes. The principal possibility of separating U from Mo and Zr by gas-phase conversion of the oxides in the atmosphere of (NOx + vapor H2O) or HNO3 (vapor) was demonstrated.

Advancing oxygen separation:insights from experimental and computational analysis of La_(0.7)Ca_(0.3)Co_(0.3)Fe_(0.6)M_(0.1)O_(3-δ)(M=Cu,Zn)oxygen transport membranes

In this study,perovskite-type La_(0.7)Ca_(0.3)Co_(0.3)Fe_(0.6)M_(0.1)O_(3-δ)(M=Cu,Zn)powders were synthesized using a scalable reverse co-precipitation method,presenting them as novel materials for oxygen transport membranes.The comprehensive study covered various aspects including oxygen permeability,crystal structure,conductivity,morphology,CO_(2) tolerance,and long-term regenerative durability with a focus on phase structure and composition.The membrane La_(0.7)Ca_(0.3)Co_(0.3)Fe_(0.6)M_(0.1)O_(3-δ)exhibited high oxygen permeation fluxes,reaching up to 0.88 and 0.64 mL·min^(−1)·cm^(−2) under air/He and air/CO_(2) gradients at 1173 K,respectively.After 1600 h of CO_(2) exposure,the perovskite structure remained intact,showcasing superior CO_(2) resistance.A combination of first principles simulations and experimental measurements was employed to deepen the understanding of Cu/Zn substitution effects on the structure,oxygen vacancy formation,and transport behavior of the membranes.These findings underscore the potential of this highly CO_(2)-tolerant membrane for applications in high-temperature oxygen separation.The enhanced insights into the oxygen transport mechanism contribute to the advancement of next-generation membrane materials.

Electrical Excitation of Long-Range Surface Plasmons in PC/OLED Structure with Two Metal Nanolayers

A current-driven source of long-range surface plasmons(LRSPs)on a duplex metal nanolayer is reported.Electrical excitation of LRSPs was experimentally observed in a planar structure,where an organic light-emitting film was sandwiched between two metal nanolayers that served as electrodes.To achieve the LRSP propagation in these metal nanolayers at the interface with air,the light-emitting structure was bordered by a one-dimensional photonic crystal(PC)on the other side.The dispersion of the light emitted by such a hybrid PC/organic-light-emitting-diode structure(PC/OLED)comprising two thin metal electrodes was obtained,with a clearly identified LRSP resonance peak.

Molecular Dynamics Simulations of Perovskites: The Effect of Potential Function Representation on Equilibrium Structural Properties

The perovskites with general formula ABX3 have been widely used as for materials with their unique properties (ferroelectric, piezoelectric, dielectric, catalytic and so on). Hybrid organolead halide perovskites are a class of semiconductors with ABX3 (X = Cl, Br, and I) structures consisting of lead cations in 6-fold coordination (B site), surrounded by an octahedron of halide anions (X site, face centered) together with the organic components in 12-fold cub octahedral coordination. These hybrid perovskites have a direct band gap, a large absorption coefficient as well as high charge carrier mobility that represent a very attractive characteristic of cost-effective solar cells. Basically, these crystals are inorganic solids of CaTiO3 type held together by bonds that are either ionic or partially ionic and partially covalent. In spite of the partially covalent character of the Ti-O bond, the system is modeled by a two-body central force interatomic potential (the form of the Vashishta and Rahman interatomic potential), which has been used successfully for many materials with a perovskite structure. In the present work using molecular dynamics (MD) simulation method we investigate the dynamical and structural behavior of CaTiO3 perovskite at normal pressure and temperature conditions. The MD calculations were performed on a system of 16,000 particles (3200Ca + 3200Ti + 96,00O), initially in an orthorhombic-Pbnm structure. The orthorhombic MD box had edges Lx = 53.4 &Aring, Ly = 53.4 &Aring and Lz = 61.12 &Aring, which provided a density matching the experimental value of ρ = 4 g/cm3. Starting with this structure and using proposed interatomic potentials the MD system stabilizes at room temperature in its initial configuration. The aim of the present study to explore the effect of potential function representations on structural equilibrium properties for the perovskite models including hybrid halide ones outlined above. Concerning the perovskite equilibrium state we elucidate the role of potential function modification on the atomic pair correlation and structural re-organization. The details of the interatomic potential representation have to be crucially important for obtaining of correct analysis data in crystallic, liquid and amorphous phases including perovskite systems.

Granular Sorbents for Passive Environment Protection System during Severe Accidents with Total Loss of Power Supply at NPPs

Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences has developed some novel sorbents designed for the filter units of the passive filtration system for radioactive discharge from the intercontainment space during heavy accidents with a complete loss of electricity supply at nuclear power plants. These are granulated sorbents based on large-pore silica gel containing nanometric particles of Ag or Ag-Ni compounds (trademark Fizkhimin). The sorbents allow to remove various radioactive iodine species (inorganic ones and methyl iodide) from a steam-gas phase with at least 104 decontamination factor. The high sorption properties of Fizkhimin sorbent with Ag particles were confirmed during tests at a test facility of the TUV Sudwest company (Karlsruhe, Germany). This passive filtration system is installed at the 1st and 2nd units of the Kudankulam nuclear power plant (India) and it is unique in the world practice.

Thermodynamic Modeling of Uranium (VI) Reductive Immobilization in Groundwater of NPCC Sludge Storages (Novosibirsk, Russia)

The Biochemical Reduction Of Both Nitrate And Sulfate In U-Containing Aquifers Of The Novosibirsk Plant Of Chemical Concentrates (NPCC) Was Investigated Experimentally And Thermodynamically. It Was Observed That Decrease In Eh Up To -397 Mv Has A Distinct Effect On The Denitrification And Uranium Precipitation As UO2(S). Nitrate Was Denitrified With A Temporary Accumulation Of The Intermediate Nitrite On The Day 4th. According To The X-Ray Fluorescence Analysis And Thermodynamic Calculations, More Than Half Of The Uranium Is Deposited In The First Stage As UO2+X oxides, And The Rest, Together With The Sulfides In The Reducing Environment. Findings Suggest That Accurately Thermodynamic Predicting Of Groundwater NO3-;?And SO42- Fate Is Primarily Limited By Failing To Account For A Kinetic Of Redox Fluctuations In The Experiment: 1) Measured Eh +190 Mv Is Low Despite The High Amount Of Nitrates (1124 Mg/L), But NH4+ Predominates In Solution According To Calculations, 2) Sulfate Reduction Lagged Behind Nitrate Reduction By Approximately 50 Days Unlike Model Simulation.

The Localization of Finely Dispersed Caesium Radioaerosols from Off-Gases

Based on fundamental research, we developed the basic scheme of a decontamination setup to remove acid gases (HCl, SO2, NOx) from steam-air flows with simultaneous localization of radioactive aerosols, including aerosols with a particle size of less than 0.1 μm and volatile radioactive iodine compounds. The decontamination process is based on the method of the agglomeration cocrystallization of finely dispersed and other aerosols in the gas phase by including the aerosols in the inner structure of large-particle non-radioactive aerosols of ammonium salts, for example, NH4Cl or (NH4)2SO3. For 137Cs, the most ecologically dangerous long-lived radionuclide, the setup ensures a decontamination factor of 102 to 103 in one decontamination stage. Because the setup consists of three consecutive stages of the same type, the cumulative decontamination factor can reach to 106 - 107. To localize radioactive iodine as I2, HI, HOI, HIO3, and CH3I from vapor-air flows, the setup uses a unit containing special granulated sorbents based on inorganic compounds. Developed at the Institute of Physical Chemistry, Russian Academy of Sciences, these sorbents effectively remove various radioactive iodine species (inorganic species and methyl iodide) from steam-air flows, ensuring decontamination factors of at least 104. The proposed technological scheme will allow vapor-gas flows to be cleaned of radioaerosols and all volatile radioactive iodine species at decontamination factors of not less than 104.

A Study of the Thermal Decomposition of CH3131I in a Gas Flow in the Presence of “Fizkhmin”TM Granulated Materials

Thermal decomposition of a volatile organic compound of radioactive iodine, methyl iodide CH3131I, in a gas flow in the presence of various modifications of “Fizkhmin”TM granulated materials based on silica gel impregnated with d-elements was studied. Under comparable experimental conditions, 97% - 99% decomposition of CH3131I is achieved at ~770?C without sorbents and at ~540?C and ~465?C in the presence of straight silica gel and of the material based on it, impregnated with compounds of Ni or its mixture with Cu (8 - 10 wt%), respectively.

Express Screening of Biological Objects Using Multisensor Stripping Voltamperometry with Pattern Recognition

Express diagnostics of biological objects is necessary for operational preliminary assessment of the condition of the patient. A method of recognition of differences between the norm and pathology is based on analysis of multidimensional patterns of the voltamperogram electrochemical test systems in Electronic formats “language”, “electronic nose”. The basis of such systems is the use of a set (matrix) sensor with completely different characteristics. A. N. Frumkin Institute of Physical Chemistry and Electrochemistry RAS (IPCE) developed a method for multidimensional stripping voltammetry, which allowed you to provide information on biological matter being investigated not as a number, as a response to a single dimension, and in the form of N-dimensional image. Formats are implemented in the process of electrochemical studies of liquid or gaseous phase. Evaluating the closeness of the resulting image object under test with known samples is collected in a database. Examples of express diagnostics of glaucoma are with accordance of the results of the electrochemical research of blood serum.

膜接触破乳——用于油包水乳液分离的超疏水ZIF-8@rGO膜

水-油界面不平衡是实现油水乳液破乳的关键。传统膜通常是依赖较高的跨膜压力破坏界面平衡而实现破乳。本文提出了可自然、快速地破坏水-油界面平衡的“接触破乳”的概念,开发了一种对有机组分具有高通量的新型破乳分离膜。具体制备过程分为两步,首先通过真空辅助抽滤法在聚四氟乙烯(PTFE)基底上组装ZIF-8@rGO微球(ZGS)层,再采用聚二甲基硅氧烷(PDMS)交联溶液中进行固定化处理。由于ZGS表面为微纳米阶层结构,所制备的ZIF-8@rGO@PDMS/PTFE(ZGPP)膜表面展现出超疏水性特性,当表面活性剂稳定的油包水乳液接触到膜表面时,微纳结构的超疏水膜表面会引起水-油界面不平衡。ZGPP膜对油包水乳液具有良好的分离破乳性能,在0.15 bar(15 kPa)的低跨膜压力下,分离效率可以达到99.57%,通量可达到2254 L·m^(-2)·h^(-1),且对于表面活性剂稳定的纳米级甲苯-水乳剂(平均液滴尺寸为57 nm)的体系也可以实现破乳分离。“接触破乳”概念的提出有望为开发新一代油包水乳液分离的破乳膜提供新的思路。

Novel Ba_(0.5)Sr_(0.5)Fe_(0.8)Zn_(0.2)O_(3-δ) membranes for POM

A novel cobalt-free perovskite based on Ba0.5Sr0.5Fe0.8Zn0.2O3-δ （BSFZ） were prepared by EDTA-citric acid method. The lattice constants of the BSFZ perovskite were characterized by in situ high-temperature X-ray diffraction （HTXRD）. The thermal expansion coefficient of BSFZ is 10.5×10^-6 K^-1, which is lower than that of cobalt-based perovskite materials. The BSFZ membrane was also used to construct reactors for the partial oxidation of methane （POM） to syngas. Results show that the BSFZ membrane can be operated for the POM reaction for more than 100 h without any fractures. The CO selectivity of 97% is obtained. The steady oxygen permeation flux reaches around 2.5 mL/min cm^2 during POM reaction.

Anomalous Laterally Stressed Kinetically Trapped DNA Surface Conformations

Up to now,the DNA molecule adsorbed on a surface was believed to always preserve its native structure.This belief implies a negligible contribution of lateral surface forces during and after DNA adsorption although their impact has never been elucidated.High-resolution atomic force microscopy was used to observe that stiff DNA molecules kinetically trapped on monomolecular films comprising one-dimensional periodically charged lamellar templates as a single layer or as a sublayer are oversaturated by sharp discontinuous kinks and can also be locally melted and supercoiled.We argue that kink/anti-kink pairs are induced by an overcritical lateral bending stress(>30 pNnm)inevitable for the highly anisotropic 1D-1D electrostatic interaction of DNA and underlying rows of positive surface charges.In addition,the unexpected kink-inducing mechanical instability in the shape of the template-directed DNA confined between the positively charged lamellar sides is observed indicating the strong impact of helicity.The previously reported anomalously low values of the persistence length of the surface-adsorbed DNA are explained by the impact of the surface-induced low-scale bending.The sites of the local melting and supercoiling are convincingly introduced as other lateral stress-induced structural DNA anomalies by establishing a link with DNA high-force mechanics.The results open up the study in the completely unexplored area of the principally anomalous kinetically trapped DNA surface conformations in which the DNA local mechanical response to the surface-induced spatially modulated lateral electrostatic stress is essentially nonlinear.The underlying rich and complex in-plane nonlinear physics acts at the nanoscale beyond the scope of applicability of the worm-like chain approximation.

Some Technical Solutions for Environmental Protection System during Accidents at Nuclear Power Plants

The paper reports some technical solutions, which suggested or used for increasing of environmental protection during accidents at NPPs. For NNPs with two protective shells and pressure release system such as WWER-1000 a comprehensive, passive-mode environmental protection system of decontamination of the radioactive steam-air mixture from the containment and the intercontainment area was suggested. This system includes the “wet” stage (scrubbers, etc.), the “dry” stage (sorption module), and also an ejector, which in a passive mode is capable of solving the multi-purpose task of decontamination of the air-steam mixture. For WWER-440/230 NPPs three protection levels: 1) a jet-vortex condenser;2) the spray system;3) a sorption module were suggested and installed. For modern designs of new generation NPPs, which do not provide for pressure release systems, a new passive filtering system together with the passive heat-removal system, which can be used during severe accidents in case all power supply units become unavailable, was proposed and after modernization was installed at the KudanKulam NPP (India).

Microstructure,hardening and deuterium retention in CVD tungsten irradiated with neutrons at temperatures of defect recovery stagesⅡandⅢ

Samples of ultra-high-purity tungsten prepared using chemical vapour deposition(CVD)technique were irradiated with neutrons at temperatures T_(irr)=373-483 K(stage Ⅱ of defect recovery)and T_(irr)=573-673 K(stage Ⅲ)up to 0.15 displacements per atom(dpa)in the Belgian reactor(BR2).The study of the microstructure of neutron-damaged samples using transmission electron microscopy(TEM)revealed visible defects with a predominance of dislocation loops.With an increase in the neutron irradiation temperature,the spatial distribution of the loops acquired pronounced inhomogeneity,and their average size moderately increased.Cavities and voids were not observed.Irradiation-induced hardening was found and a linear correlation was obtained between Vickers microhardness and nanohardness for undamaged and neutron-irradiated CVD-W samples.Irradiation of tungsten with neutrons led to a significant increase in the retention of deuterium,which accumulated mainly in vacancy-type traps.Furthermore,the influence of the columnar grain structure in low-dose neutron-irradiated tungsten seemed to be non-trivial upon deuterium retention.