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71.
Mostafa M. Hamed S. M. Yakout H. S. Hassan 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(1):697-708
Radioactive waste contains nitrate and nitrite as well as radioactive fission products. Nitrate and nitrite anions are two of the major components of nuclear waste streams and contribute to environmental release hazards. The removal of nitrate and nitrite is a necessary step for the further treatment low-level radioactive wastes. The focus of the research is to evaluate the adsorption potential of solid phase derived from rice straw for nitrate and nitrite anions in single- and binary-component systems due to the fact that the rice straw is a very abundant and by-product material. The removal was accomplished under the optimize conditions of temperature, concentration, pH, contact time and quantity of adsorbent as these parameters are some of the main factors influencing the uptake of two solutes at the solid–solution interface. Batch-mode kinetic and equilibrium studies have been carried out. The experimental data was analyzed using equilibrium isotherm and kinetic models. The thermodynamic parameters (?G°, ?H°, and ?S°) were also determined using the equilibrium constant value obtained at different temperatures. Results show that this adsorbent is effective and much better or even superior than many sorbents for removal of nitrate and nitrite. The prepared sorbent as solid-phase extractant was successfully applied for the extraction of nitrate from actual water samples. 相似文献
72.
73.
Clobutinol (Cb) ion-selective plastic-membrane electrodes based on ion associates of clobutinolium phosphotungstate (Cb-PTA),
clobutinolium phosphomolybdate (Cb-PMA), or a mixture of both Cb-PTA and PMA were prepared. The electrodes were fully characterized
in terms of membrane composition, life span, pH, and temperature. The electrodes were applied to the potentiometric determination
of clobutinol in pure form and pharmaceutical preparations under batch and flow-injection conditions. Also, conductimetric
titrations were applied to the assay of clobutinol in its pure form and pharmaceutical preparations. The selectivity of the
electrodes towards a large number of inorganic cations, amino acids, and sugars was tested. The solubility product of ion-associates
and the formation constant of the precipitation reactions leading to the ion-associate formation were determined conductimetrically.
The text was submitted by the authors in English. 相似文献
74.
Shrinkage microporosity in cast aluminum was characterized utilizing the frequency dependence of ultrasonic attenuation caused by scattering from the pores. Measurements were made with the plate specimen immersed in water, and, by using a focused transducer, spatial resolution of about 2 mm was obtained. An accurate measure of attenuation was obtained by comparing the specimen’s ultrasonic signal with that from a pore-free reference specimen. Although the attenuation could be fitted using a single spherical pore size, better fits were obtained by assuming a lognormal distribution of spheres. Pore volume fraction inferred from the lognormal fits overestimates the actual volume fraction, determined from density measurements, by the same factor for all volume fractions. The actual volume fraction is overestimated by more than 100%, due to the complicated, nonspherical pore shapes, and must be taken into account to obtain accurate values of porosity. The strong correlation (r2=0.97) between ultrasonic and density-derived volume fractions permits reliable, nondestructive laboratory measurements of porosity. 相似文献
75.
Dr. Hamed Shaykhalishahi Dr. Aziz Gauhar Michael M. Wördehoff Dr. Clara S. R. Grüning Antonia N. Klein Dr. Oliver Bannach Dr. Matthias Stoldt Prof. Dr. Dieter Willbold Prof. Dr. Torleif Härd Dr. Wolfgang Hoyer 《Angewandte Chemie (International ed. in English)》2015,54(30):8837-8840
Conversion of the intrinsically disordered protein α‐synuclein (α‐syn) into amyloid aggregates is a key process in Parkinson’s disease. The sequence region 35–59 contains β‐strand segments β1 and β2 of α‐syn amyloid fibril models and most disease‐related mutations. β1 and β2 frequently engage in transient interactions in monomeric α‐syn. The consequences of β1–β2 contacts are evaluated by disulfide engineering, biophysical techniques, and cell viability assays. The double‐cysteine mutant α‐synCC, with a disulfide linking β1 and β2, is aggregation‐incompetent and inhibits aggregation and toxicity of wild‐type α‐syn. We show that α‐syn delays the aggregation of amyloid‐β peptide and islet amyloid polypeptide involved in Alzheimer’s disease and type 2 diabetes, an effect enhanced in the α‐synCC mutant. Tertiary interactions in the β1–β2 region of α‐syn interfere with the nucleation of amyloid formation, suggesting promotion of such interactions as a potential therapeutic approach. 相似文献
76.
77.
Farzaneh Ahmadi Jahan Bakhsh Raoof Reza Ojani Mehdi Baghayeri Moslem Mansour Lakouraj Hamed Tashakkorian 《催化学报》2015,(3)
Ag nanoparticles were synthesized on the surface of a glassy carbon electrode modified with p‐tert‐butylcalix[4]arene and p‐tert‐butylcalix[6]arene by the deposition of Ag+at an open circuit potential ... 相似文献
78.
An efficient mixed reagent for direct synthesis of symmetrical carboxylic anhydrides from carboxylic acids has been prepared. Carboxylic acids are converted to anhydrides using triphenylphosphine/trichloroisocyanuric acid under mild reaction conditions at room temperature. Short reaction time, excellent yields of products, low cost, availability of reagents, simple experimental procedure, and easy work-up of the products are the main advantages of the presented method. 相似文献
79.
Shaabani Ahmad Nosrati Hamed Seyyedhamzeh Mozhdeh 《Research on Chemical Intermediates》2015,41(6):3719-3727
Research on Chemical Intermediates - 3-Aminoimidazo[1,2-a]pyridines have been synthesized through a condensation reaction of 2-aminopyridine, an aldehyde and an alkyl or aryl isocyanide in high... 相似文献
80.
Mohsen Padervand Solmaz Ghaffari Mahdieh Mohammad Nejad 《Journal of Analytical Chemistry》2017,72(5):567-574
Sunitinib malate, as an anticancer compound and a multi-targeted tyrosine-kinase inhibitor for treatment of glioma, was comprehensively studied by using different liquid chromatography methods. Since sunitinib malate shows Z-E isomerism, various reverse phase high performance liquid chromatography (RP-HPLC) programs were designed to access quantitative determination and good separation of Z-E stereoisomers. Moreover, some impurities including N-oxide and impurity B were to be separated from the main isomer with acceptable resolution. In the present work, different RP-HPLC programs were developed in which the type of mobile phase, flow rate, pH, and temperature were optimized to reach the best analysis conditions and control the rate of Z to E conversion. In addition, the effect of some operational parameters during the solution preparation including initial concentration of the analyte, temperature, pH, and type of solvent on the stability of Z isomer were investigated. The opted conditions for quantitative analysis were C8-Hector column as stationary phase, methanol as solvent, ammonium acetate buffer containing triethylamine as mobile phase, the pH of mobile phase of 8.5, the flow rate of 1.0 mL/min, and detection at 425 nm. In this situation the peaks of E and Z isomers were at 16.3 and 19.7 min. Full validation of the designed method was done based on ICH guidelines. 相似文献