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61.
Maggy?Manguian Maud?SaveEmail author Christophe?Chassenieux Bernadette?Charleux 《Colloid and polymer science》2005,284(2):142-150
Well-defined, positively charged, amphiphilic copolymers containing long alkyl side chains were used as stabilizers in the miniemulsion polymerization of styrene. The copolymers were prepared by controlled free-radical copolymerization of styrene and vinyl benzyl chloride using either the reversible addition-fragmentation chain transfer method or TEMPO-mediated polymerization. The benzyl chloride moities were modified by two different long alkyl chain tertiary amines (N,N-dimethyldodecyl amine and N,N-dimethylhexadecyl amine) to yield the amphiphilic copolymers with vinylbenzyl dimethyl alkyl ammonium chloride units. Owing to their high structural quality, only a small amount of these copolymers was required to stabilize the latex particles (0.5–2 wt% vs styrene). Moreover, in the absence of any hydrophobic agent, the amphiphilic comblike copolymer preserved the colloidal stability of both the initial liquid miniemulsion and the final latex. Ill-defined, analogous copolymers were synthesized by conventional free-radical polymerization and in comparison, exhibited poor stabilization properties. 相似文献
62.
Summary Minimum-weight designs of a perfectly plastic continuous sandwich beam with two equal spans are obtained analytically for a variety of movable loads, on the basis of the condition of constant integrated specific dissipation rate.
Text of a lecture given by the senior author at the Politecnico di Milano and at the Facoltà di Ingegneria dell'Università di Roma in May 1970. 相似文献
Sommario Mediante la condizione di costanza dell'integrale della velocità di dissipazione specifica si decudono per via analitica e per una varietà di carichi mobili, progetti di minimo peso di una trave continua a due luci uguali perfettamente plastica e di tipo sandwich.
Text of a lecture given by the senior author at the Politecnico di Milano and at the Facoltà di Ingegneria dell'Università di Roma in May 1970. 相似文献
63.
Use of indigenous microwave system for dissolution and treatment of waste from nuclear materials 总被引:1,自引:0,他引:1
R. K. Malav Neeta D. Save Amrit Prakash Md. Afzal J. P. Panakkal 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(1):425-430
Microwave heating technique has the unique advantages of low processing time, less consumption of reagents, homogeneous heating and maintenance-free adaptability to glove box. Dissolution of thorium and plutonium containing fuel viz sintered thorium oxide, thorium-uranium oxide and thorium-plutonium oxide pellets is one of the most difficult step for their analysis and characterization. Complete dissolution of the fuel samples is a pre-requisite for the analysis of fuel material in the solution form. Even a trace level of un-dissolved particle may interfere with the accurate and precise determination in the analysis. Large volumes of liquid and solid wastes are generated during the processing and analysis of samples. These wastes being radioactive can’t be disposed directly to sea or soil. They have to be segregated and categorised and all possibilities are explored to see the feasibility of retrieving the precious nuclear material. The present paper describes an overview of all the efforts made at AFFF for rapid dissolution of nuclear materials using an indigenous microwave digestion system as well as its use for the treatment of waste being generated. 相似文献
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66.
A method has been developed for the determination of copper, lead, cadmium and zinc in high purity uranium metal. Conditions are described for the separation of these elements from uranium(VI) and iron(III) by ion-exchange on cellulose phosphate and for their determination by square wave polarography using orthophosphoric acid as base electrolyte.The procedure has been shown to be applicable to metal containing less than 5 p.p.m, of each impurity and results are compared with those obtained by other methods. 相似文献
67.
The synthesis of conveniently substituted 2'-amino-alpha,beta-epoxychalcones is described. They were obtained through Darzens condensation of 2'-amino-3',5'-dimethoxy-alpha-chloroacetophenone with benzaldehydes. The latter can undergo different cyclization possibilities and afford a variety of flavonoid analogs with biological potential. 相似文献
68.
The crystal structure of 2NaPF6·dibenzo-36-crown-12 was determined by X-ray diffraction methods. The 2:1 (metal:ligand) complex crystallises in the monoclinic system, space group P21/n with cell constants of a = 14.189(2), b = 9.372(1), c = 16.750(3) Å, and β = 108.98(1)°. The two NaPF6 units are each coordinated through five oxygen atoms to opposite faces of the macrocycle in a centrosymmetric manner. 相似文献
69.
Maud Brink 《Magnetic resonance in chemistry : MRC》1976,8(4):177-179
The barriers to rotation about the pivot bonds in with n = 8 or 10 and R = CH2C6H5, CH2COOH, CH2COOCH3 or CH(CH3)2 were studied. ΔG≠ values were found to be > 24 kcal. mol?1. The solvent, the temperature, and the concentration dependence of the double magnetically non-equivalent methylenic protons and methyl groups were studied. 相似文献
70.
Gaborieau M Nicolas J Save M Charleux B Vairon JP Gilbert RG Castignolles P 《Journal of chromatography. A》2008,1190(1-2):215-223
Size-exclusion chromatography (SEC) separates polymers by hydrodynamic volume (the universal calibration principle). Molecular weights can be determined using viscometry (relying on universal calibration) and light scattering (independent of universal calibration). In the case of complex branched polyacrylates with tetrahydrofuran as eluent, universal calibration is valid, although the separation in term of molecular weight is incomplete: a given elution slice contains a range of molecular weights, described in terms of a 'local polydispersity'. The local polydispersity index decreases when the number of branches per chain increases and complete separation is reached for highly branched chains. 相似文献