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81.
The suitability of Syrian Portland cement for disposal of solidified low-level radioactive waste was assessed by measuring the leaching rate of 134Cs. In ordinary cement concrete, a leaching rate of 1.309 × 10?3 g/cm2 per day was measured. Mixing this concrete with microsilica reduced significantly the leaching rate to 3.106 × 10?4 g/cm2 per day for 1% mixing, and to 9.645 × 10?5 g/cm2 per day for 3% mixing. It was also found that the application of a latex paint reduced these leaching rates by about 10%. These results, along with mechanical strength tests (under radiation exposure, high temperature, long water immersion and freeze–thaw cycling) indicate that Syrian Portland cement is suited for the disposal of low-level radioactive waste. 相似文献
82.
83.
Design and Synthesis of 2,2′‐Diindolylmethanes to Selectively Target Certain G‐Quadruplex DNA Structures
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Dr. Madeleine Livendahl Dr. Jan Jamroskovic Svetlana Ivanova Peter Demirel Dr. Nasim Sabouri Dr. Erik Chorell 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(37):13004-13009
G‐quadruplex (G4) structures carry vital biological functions, and compounds that selectively target certain G4 structures have both therapeutic potential and value as research tools. Along this line, 2,2′‐diindolylmethanes have been designed and synthesized in this work based on the condensation of 3,6‐ or 3,7‐disubstituted indoles with aldehydes. The developed class of compounds efficiently stabilizes G4 structures without inducing conformational changes in such structures. Furthermore, the 2,2′‐diindolylmethanes target certain G4 structures more efficiently than others and this G4 selectivity can be altered by chemical modifications of the compounds. 相似文献
84.
Mohammad Hossein Mosslemin Nasim Shams Hossein Esteghamat Hossein Anaraki-Ardakani 《中国化学快报》2013,24(12):1095-1098
A reaction between 1,3-dioxo-N-aryl-2,3-dihydro-lH-indene-2-carboxamides, dialkyl acetylenedicar- boxylates, and triphenylphosphine or trimethylphosphite is described as a simple and efficient method for the synthesis of 5-hydroxy-4-aryl-2,5-dihydrofuran-2,3-dicarboxylate derivatives. 相似文献
85.
M. Nasim D. Selvakumar Rajendra Singh G. N. Mathur 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4):1011-1017
Abstract Complexes of gallium bound to chalcogen elements recently have found importance in synthesis and as single molecular precursors for preparing thin films of gallium chalcogenides for their applications as photo-receivers for visible and near IR region. Herein we report the synthesis and characterization of some Lewis base (LB) stabilized gallium-telluride complexes. Gallium tellurolate complexes of formula, [LB] · [Ga(TePh)3] x , [x = 1, LB = 4-dimethylaminopyridine; x = 2, LB = 4,4′-methylene bis(N,N′-dimethylaniline] were prepared by reacting the corresponding Lewis base adduct of gallium(III) iodide and phenyllithium tellurolate. The complexes have been characterized by elemental analyses, ICP-MS, multinuclear NMR, and thermal and mass spectrometry. Such complexes may be potential single-molecular precursors for III–VI electronic materials. 相似文献
86.
A new diimide-diacid, (4-(4-(2,6-diphenylpyridin-4yl)phenoxy)phenyl)-1,3-bis(trimellitimidobenzene) (PPMIB), was synthesized from the condensation reaction of a new diamine, (4-(4-(2,6-diphenylpyridin-4yl)phenoxy)phenyl)-3,5-diaminobezamide (PPDA), and trimellitic anhydride carboxylic acid (TMAA) in glacial acetic acid. The diimide-diacid (PPMIB) was characterized by FT-IR, 1H-NMR and elemental analysis. A series of novel aromatic poly(amide-imide)s (PAIs) was synthesized by using direct polycondensation of PPMIB with various diamines in NMP in the presence of triphenylposphite and pyridine as condensing agents. The resulting PAIs were amorphous, readily soluble in many polar aprotic solvents and showed inherent viscosities of 0.35–0.50 dL/g. According to thermal analysis, these polymers exhibited glass transition temperatures (Tgs) in the range of 202–280°C and temperature of 10% weight loss (T10) varied from 400 to 545°C in N2. These polymers in NMP solution exhibited strong UV-Vis absorption maxima at 320°C nm and their fluorescence emission peaks appeared around 410–565 nm. 相似文献
87.
Solmaz Ghaffari Nasim Sadri Alamdari Zahra Jafari Azar Ali Reza Dabir Siaghi Farzad Kobarfard Sanaz Ghaffari 《Journal of Dispersion Science and Technology》2013,34(9):1332-1335
Preparation of sustained release dosage forms is one of the main objectives in drug formulation. Theophylline that has a narrow therapeutic index, making it a good choice to prepare a sustained release dosage form. Theophylline sustained release microcapsules were prepared by applying the coacervation method. The effect of the type and ratio of polymers, as well as the type of washing solvents, was studied on particle size, drug loading efficiency, and in vitro drug release profile. Results showed that Eudragit RS and RL could be more suitable polymers for preparation of sustained release microcapsules of theophylline when used in ratio of 1:1 and when the washing solvent was hexane. 相似文献
88.
Nasim Farahbakhsh Richard A. Venditti Jesse S. Jur 《Cellulose (London, England)》2014,21(4):2743-2755
The thermal and mechanical performance of composites with nano-sized cotton fillers embedded in low-density polyethylene (LDPE) is investigated. Microfibrillated cotton was prepared by microgrinding mechanical treatment of pulverized cotton (pCot) derived from waste T-shirts, resulting in nano-sized fibrils of the cellulose that retain high crystallinity. Film composites of LDPE with pCot before and after microgrinding were fabricated through melt extrusion and the effect of filler size on mechanical, thermal and morphological properties of the composite was investigated. Compounding microfibrillated cotton with LDPE resulted in well-dispersed nanocomposites with no discoloration after 10 min of melt extrusion at 170 °C. At concentrations up to 10 % by weight, the composites showed increased modulus, increased tensile strength and a slight decrease in elongation to break. Further improvement in the dispersion and mechanical properties of the cotton-based fillers was realized by the use of LDPE powder instead of polymer pellets fed to the extruder. This research demonstrates the processing and applicability of the use of recycled cotton-based nano-sized fillers in melt-processing. 相似文献
89.
Ahmad Shaabani Mozhdeh Seyyedhamzeh Nasim Ganji Seik Weng Ng 《Journal of the Iranian Chemical Society》2014,11(2):481-487
A new class of fused tricyclic benzo[4,5]imidazo[1,2-a]-pyrimidine-3-carboxamide derivatives was synthesized via an environmentally benign one pot sequential four-component condensation reaction of an amine, 2,2,6-trimethyl-4H-1,3-dioxin-4-one, an aldehyde and 1H-benzo[d]imidazol-2-amine without using catalyst in good yields. 相似文献
90.
Unveiling the impact of regioisomerism defects in the glass transition temperature of PVDF by the mean of the activation energy
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Nasim Anousheh François Godey Armand Soldera 《Journal of polymer science. Part A, Polymer chemistry》2017,55(3):419-426
Alternating two groups, CH2 and CF2, of very different polarities along the backbone chain of polyvinylidene fluoride (PVDF) leads to very interesting properties, such as ferroelectricity. However, these properties are affected by the presence of regioisomerism defects (monomer inversion) that appear during the synthesis. In this study, the influence of these defects on the glass transition temperature (T g) is regarded. Using molecular simulation, we investigated their plasticizer effect. To highlight their role in modifying polymer chain relaxation, the activation energy (E a) related with conformational transitions is computed. We show that a clear linear relationship can be established between E a and T g. E a is then separated into different contributions associated with each type of bond. Mobility of individual segments can thus be accounted separately from the mobility of the whole chain. As a consequence, T g of the alternate copolymer ethylene‐tetrafluoroethylene (E‐TFE), an isomeric polymer of PVDF, can be deduced. T g of this copolymer is still source of discussion in the literature. The resulting value, ?97 °C, is found in good agreement with some experimental data, and also with T g extracted from simulated dilatometry. Consequently, local mobility of a polymer chain can be retrieved from the whole mobility, and vice versa. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 419–426 相似文献