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81.
Sorption of Th, Pa, U, Np and Pu on silica gel from HNO3, HCl and HCl−ROH solutions was investigated. Equilibrium studies indicated sorption behaviour to vary greatly with the acid
used. In mixtures of HCl with different alcohols, distribution coefficints were found to depend on alcohol percentage as well
as on acidity. Results were discussed and conditions for possible separations were indicated. 相似文献
82.
Luiz G. Farah 《Journal of Evolution Equations》2016,16(1):193-208
We consider the supercritical inhomogeneous nonlinear Schrödinger equationwhere \({(2 - b)/N < \sigma < (2 - b)/(N-2)}\) and \({0 < b < \rm min\{2,N\}}\). We prove a Gagliardo–Nirenberg-type estimate and use it to establish sufficient conditions for global existence and blow-up in \({H^1(\mathbb{R}^N)}\).
相似文献
$$i\partial_t u+\Delta u+|x|^{-b}|u|^{2\sigma}u=0,$$
83.
The thermodynamics of the extraction of Eu3+ by thenoyltrifluoroacetone (HTTA) and by mixtures of HTTA and bidentate amine bases such as 2,2-dipyridyl (Dipy) and 1,10-phenanthroline (Phen) in benzene from an aqueous phase fixed to 0.1M ionic strength (NaClO4), pH 3.9, has been investigated. Phenanthroline forms both the Eu(TTA)3·Phen and Eu(TTA)3·2Phen species, which are much stronger than the dipyridyl complexes. The diluent effect on the extraction is also studied. 相似文献
84.
Corrosion inhibition properties of winged bean (WB) extracts on reinforced steel in 0.5 ?M HCl solution was studied through experimental and theoretical calculation methods. The electrochemical studies suggested that inhibition efficiency increased with increasing concentration of WB extracts up to 95%. Nyquist diagrams revealed an increase in the charge transfer resistance values and a decrease in the constant phase element as the concentration of WB extracts were increased. The potentiodynamic polarization results revealed that WB extracts behave as mixed-type inhibitors, which physically adsorbed onto the reinforced steel surface. Effect of temperature study demonstrated that the corrosion resistance behaviour of WB extracts decreased with an increase in temperature, yielding a corrosion rate of 3.39 mmpy and 4.02 mmpy at 333 ?K with the incorporation of 1000 ?ppm WBW and WBE extracts, respectively. The thermodynamic study implied that the adsorption process follows the Langmuir isotherm with free energy adsorption of ΔGads WBW ?= ?-17.29 ?kJ ?mol-1 and ΔGads WBE ?= ?-16.81 ?kJ ?mol-1. Corresponding to the molecular modelling study, the semi-empirical method and molecular dynamics (MD) simulation investigated the correlation between the inhibitor compounds and the metal surface. One of the phenolic molecule constituents (gallic acid) was chosen to establish the structural and electronic parameters responsible for the high inhibition efficiency. A greater Ebinding of 0.181 (a.u.) indicates that gallic acid in WB extracts can easily bind with the Fe surface, thus projecting a higher inhibitory performance. Surface morphology study affirmed the effective adsorption of WB extracts onto the surface of reinforced steel. 相似文献
85.
86.
Phong Dinh Tran Audrey Allavena-Valette Farah Kamous Pascal Doppelt 《Polyhedron》2009,28(18):4091-4095
Novel fluorine free (β-diketonate)Cu(I)BTMSA precursors (where BTMSA is bis(trimethylsilyl) acetylene) were prepared in good yield (63–80%) by a simple acid–base reaction. The starting β-diketone structure was modified for tailoring physico-chemical properties of synthesized precursors. High volatile, relative thermally stable and low-melting precursors were prepared when asymmetric β-diketones were used. By using the (1-(cyclobutyl)-1,3-butandionate)Cu(I)BTMSA precursor, highly pure, compact and smooth copper films were deposited on Ta/TaN substrates at deposition temperatures as low as 150 °C. 相似文献
87.
Recoverable salen-based macrocyclic chiral complexes; catalysts for enantioselective Henry reactions
Farah Ibrahim Nada Jaber Vincent Guérineau Ali Hachem Ghassan Ibrahim Mohamed Mellah Emmanuelle Schulz 《Tetrahedron: Asymmetry》2013,24(21-22):1395-1401
Cobalt and chromium complexes have been prepared from chiral calix–salen cyclic ligands. The corresponding tetrahydrosalen reduced forms have been used for copper salt complexation. These new chiral catalysts have been tested for their ability to promote asymmetric Henry reactions between various aldehydes and nitromethane under heterogeneous conditions. The best results were obtained by using tetrahydrosalen-based copper macrocycles, in terms of activity, selectivity, and stability during the recycling process. Ten consecutive runs could indeed be performed with the same catalyst batch to produce the target 1-(2-methoxy-phenyl)-2-nitro-ethanol with highly stable values in terms of yield and enantioselectivity (up to 94% ee). 相似文献
88.
Farah Fahma Shinichiro Iwamoto Naruhito Hori Tadahisa Iwata Akio Takemura 《Cellulose (London, England)》2010,17(5):977-985
Cellulose nanofibers were produced by hydrolyzing oil palm empty-fruit-bunches with sulfuric acid. The effect of hydrolysis
time on the structure and properties of the nanofibers was investigated. Fourier transform infrared spectroscopy was employed
to evaluate the change of chemical composition. Atomic force microscope images showed that the average thickness of the nanofibers
ranged from 1 to 3.5 nm as the hydrolysis time was varied. Longer hydrolysis time produced a higher yield of dispersed nanofibers;
whereas the degree of crystallinity and the degree of polymerization decreased with increasing hydrolysis time. The degradation
of nanofibers with higher sulfate group content started at a lower temperature. 相似文献
89.
M. M. Rizzo L. D. B. Machado S. I. Borrely M. H. O. Sampa P. R. Rela J. P. S. Farah R. I. Schumacher 《Radiation Physics and Chemistry》2002,63(3-6):259-262
The subject of this study is a Peruvian painting from the 17th century, which has been recently restored and then contaminated by mould. It received different unsuccessful treatments. Therefore, radiation process was suggested as an alternative once it is an effective technology for decontamination and conservation purposes. The aim of this study is to investigate the influence of irradiation process on the original painting and on the products used in the restoration process. These products were irradiated with 60Co gamma rays applying doses in the range of 6–25 kGy. The polymeric materials were characterized by thermal analysis techniques before and after irradiation. The colour of the pigments irradiated and non-irradiated were compared by spectrophotometric analysis. Small samples removed of the original painting were also irradiated and investigated. The results obtained until now allowed concluding that the irradiation with the appropriated dose of 6.0 kGy, according to the literature, will not damage the restored painting. 相似文献
90.
Dr. Karim Farah Prof. Dr. Florian Müller‐Plathe Prof. Dr. Michael C. Böhm 《Chemphyschem》2012,13(5):1127-1151
Reactive molecular dynamics (RMD) implementations equipped with force field approaches to simulate both the time evolution as well as chemical reactions of a broad class of materials are reviewed herein. We subdivide the RMD approaches developed during the last decade as well as older ones already reviewed in 1995 by Srivastava and Garrison and in 2000 by Brenner into two classes. The methods in the first RMD class rely on the use of a reaction cutoff distance and employ a sudden transition from the educts to the products. Due to their simplicity these methods are well suited to generate equilibrated atomistic or material‐specific coarse‐grained polymer structures. In connection with generic models they offer useful qualitative insight into polymerization reactions. The methods in the second RMD class are based on empirical reactive force fields and implement a smooth and continuous transition from the educts to the products. In this RMD class, the reactive potentials are based on many‐body or bond‐order force fields as well as on empirical standard force fields, such as CHARMM, AMBER or MM3 that are modified to become reactive. The aim with the more sophisticated implementations of the second RMD class is the investigation of the reaction kinetics and mechanisms as well as the evaluation of transition state geometries. Pure or hybrid ab initio, density functional, semi‐empirical, molecular mechanics, and Monte Carlo methods for which no time evolution of the chemical systems is achieved are excluded from the present review. So are molecular dynamics techniques coupled with quantum chemical methods for the treatment of the reactive regions, such as Car–Parinello molecular dynamics. 相似文献