Transient and steady state crack growth kinetics for stress corrosion cracking of a cold worked 316L stainless steel in oxygenated pure water at different temperatures

The stress corrosion cracking (SCC) growth kinetics for a cold worked 316L stainless steel was continuously monitored in high purity water at different temperatures and dissolved oxygen (DO) levels under a K (or K_max) of 30 MPa m^0.5. The total SCC test time was more than 8000 h to make sure the steady state crack growth rate under each test condition could be reached. Crack growth rate (CGR) increases with increasing temperature in the range 110-288 °C. A typical intergranular-cracking mode is identified. Depending on the previous test condition, especially the temperature, three kinds of crack growth kinetics, i.e., increasing with testing time then becoming steady, being constant during the whole period, or decreasing with test time then becoming steady, are identified and discussed. Time-dependent and testing history-dependent crack growth modes were confirmed in two series of tests in 2 ppm DO and 7.5 ppm DO pure water. The apparent activation energies are calculated and compared with other data in different environments under different applied loading levels for understanding the cracking mechanism.     

裂解汽油在镍基催化剂上的加氢行为研究

采用微分反应器对裂解汽油在镍基催化剂06-Ni-25上的加氢动力学进行了研究,考察了反应温度、反应压力、液体空速等条件对裂解汽油加氢效果的影响.结果表明,反应温度和液体空速是影响裂解汽油加氢转化率和选择性的2个重要参数,反应压力的影响则比较小.以双烯和单烯2个集总为模型,分别建立了裂解汽油在镍基催化剂06-Ni-25上的双烯和单烯动力学方程.由所建方程可得,双烯、单烯加氢反应活化能分别为83.000,97.384 kJ/mol.     

Electrochemical recovery of silver from waste aqueous Ag(I)/Ag(II) redox mediator solution used in mediated electro oxidation process

The paper presents a process for the electrochemical recovery of silver(Ag) by electro deposition on the electrode surface from the waste solutions of Ag(I)/Ag(II) redox system in nitric acid medium used for the mediated electrochemical process. Electrochemical recovery was carried out in an undivided cell with DSA-O₂ electrodes at room temperature condition. At an optimized current density of 12 A/dm², 99% of Ag recovery efficiency was achieved with high yield and low energy consumption. Experimental runs were made in order to observe the performance of the Ag recovery process. The operating conditions like current density, temperature and Ag(I) concentration of the electrolyte, the acid concentrations, agitation rate and inter-electrode distance were optimized.     

Infrared multiphoton dissociation in quadrupole ion traps

The development of new ion activation techniques continues to be a dynamic area of scientific discovery, in part to complement the tremendous innovations in ionization methods that have allowed the mass spectrometric analysis of an enormous array of molecules. Ion activation/dissociation provides key information about ion structures, binding energies, and differentiation of isomers, as well as affording a primary means of identifying compounds in mixtures. Numerous new activation methods have emerged over the past two decades in an effort to develop alternatives to collisional activated dissociation, the gold standard for providing structurally diagnostic fragmentation patterns. Collisional activated dissociation does not always offer sufficiently high or controllable energy deposition, thus rendering it less useful for certain classes of molecules, such as large proteins or macromolecular complexes. Photodissociation is one of the most promising alternatives and is readily implemented in ion trapping and time‐of‐flight mass spectrometers. Photodissociation generally entails using a laser to irradiate ions with UV, visible, or IR photons, thus resulting in internal energy deposition based on the number and wavelengths of the photons. The activation process can be extremely rapid and efficient, as well as having the potential for high total energy deposition. This review describes infrared multiphoton dissociation in quadrupole ion trap mass spectrometry. A comparison of photodissociation and collisional activated dissociation is covered, in addition to some of the methods to increase photodissociation efficiency. Numerous applications of IRMPD are discussed as well, including ones related to the analysis of drugs, peptides, nucleic acids, and oligosaccharides. © 2009 Wiley Periodicals, Inc., Mass Spec Rev 28:390–424, 2009     

Catalytic activity of polymer-bound Ru(III)-EDTA complex

Chloromethylated styrene-divinylbenzene copolymer was chemically modified with ethylenediaminetetraacetic acid ligand. Catalytically active polymer containing Ru(III) moieties were synthesized from this polymeric ligand. They were characterized using FTIR, UV-vis, SEM, ESR and TGA. Other physico-chemical properties such as bulk density, surface area, moisture content and swelling behaviour in different solvents were also studied. The polymer bound complex was used to study hydrogenation of 1-hexene ton-hexane under mild conditions. Influence of [1-hexene], [catalyst], temperature and nature of the solvent on the rate of the reaction was investigated. A rate expression is proposed based on the observed initial rate data. Recycling efficiency of the catalyst has also been studied.     

Removal of Nickel and Boron from Plating Rinse Effluent by Electrochemical and Chemical Techniques

In this work, electrotreatment of nickel and boron containing plating rinse effluents was studied with mild steel and aluminum electrodes. Industrial effluent treatment directly by an electrochemical technique is capable of removing 80–85 % nickel. The residual nickel interfered with boron determination by curcumin method. The pH fall during electrotreatment in industrial effluent is due to electrodeposition of nickel at the cathode surface, evidenced by simulated effluent treatment. Nickel concentration can be reduced below the discharge limit from the industrial plating effluent by chemical precipitation and coagulation at pH above 8. Chemical precipitation showed maximum boron removal of about 50 %. Boron removal was 29.3–41.9 % and 20.6–33.1 % with ferric chloride and aluminum sulfate, respectively. A combination of chemical precipitation at pH 8.7 followed by electrotreatment reduces nickel to the discharge limit and also maximizes boron removal up to 59 %.     

]Electrical conductivity measurements on gel grown KDP crystals added with some ammonium compounds

Pure and impurity added [with NH₄CI, NH₄NO₃, NH4₄H₂PO₄, (NH₄)₂CO₃ and (NH₄)₂SO₄] KDP single crystals were grown by the gel method using silica gels. Electrical conductivity measurements were carried out along both the unique axis and perpendicular directions at various temperatures ranging from 28 to 140°C by the conventional two-probe method. The present study shows that the conductivity in KDP crystals, for all the five dopants considered, increases with the increase in impurity concentration and temperature. Activation energies were also determined and reported.     

Plasma processes at atmospheric and low pressures

In the last few decades there has been an intense development in non-equilibrium (“cold”) plasma surface processing systems at atmospheric pressure. This new trend is stimulated mainly to decrease equipment costs by avoiding expensive pumping systems of conventional low-pressure plasma devices. This work summarizes physical and practical limitations where atmospheric plasmas cannot compete with low-pressure plasma and vice-versa. As the processing conditions for atmospheric plasma are rather different from reduced pressure systems in many cases these conditions may increase final equipment costs substantially. In this work we briefly review the main principles, advantages and drawbacks of atmospheric plasma for a better understanding of the capabilities and limitations of the atmospheric plasma processing technology compared with conventional low-pressure plasma processing.     

Rheological behaviour of acorn starch dispersions: effects of concentration and temperature

Rheological properties of acorn starch dispersions at different concentrations (4%, 5%, 6% and 7%) were evaluated under steady and dynamic shear conditions. The flow behaviours of the acorn starch dispersions at different temperatures (25, 40, 55 and 70 °C) were determined from the rheological parameters provided by the power law model. The acorn starch dispersions at 25 °C exhibited high shear-thinning fluid characteristics ( n  = 0.23–0.36). Consistency index (K) and apparent viscosity (η_a,100) increased with an increase in starch concentration, and were also reduced with increasing temperature. Within the temperature range of 25–70 °C, the η_a,100 obeyed the Arrhenius temperature relationship with a high determination coefficient ( R ² = 0.97–0.99), with activation energies (E_a) ranging between 16.5 and 19.0 kJ mol⁻¹. Both the power law and exponential type models were employed in order to establish the relationship between concentration and apparent viscosity (η_a,100) in the temperature range of 25–70 °C. Magnitudes of storage ( G' ) and loss ( G ") moduli increased with an increase in the starch concentration and frequency (ω). The magnitudes of G ' were higher than those of G " over most of the frequency range (0.63–62.8 rad s⁻¹). The dynamic (η*) and steady shear (η_a) viscosities of acorn starch dispersion at 7% concentration follow the Cox–Merz superposition rule.     

添加元素对贮氢电极材料 MlNi3.8(CoMn)1.2电化学及高温性能的影响

研究了微量元素Ti,Zr,Al对MlNi3 .8(CoMn) 1.2 合金电化学性能及高温性能的影响。添加少量铝虽然使合金在室温的放电容量和高倍率放电容量降低 ,但可显著提高高温下的容量 ,并有效抑制自放电 ,提高循环稳定性 ;添加少量钛或锆均降低合金的放电容量 ,但可改善高倍率放电性能。锆还可提高合金的循环稳定性 ,延长电极寿命。