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51.
A. V. Barabanova P. V. Afanas'ev B. G. Kostyuk V. V. Lunin 《Russian Chemical Bulletin》1996,45(12):2698-2702
Phosphates of K and Zr of a layered, microporous structure have been obtained by the molten salt method in a potassium nitrate medium in the temperatures range 573–823 K. Dependences of the product composition on the P/Zr atomic ratio and the temperature of synthesis were studied. The substances obtained have been characterized by XRD,1H and31P NMR, and IR spectroscopy, and scanning electron microscopy.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2847–2851, December, 1996. 相似文献
52.
This article discusses the extraction and characterization of new natural fiber extracted from red coconut empty fruit bunch. The physicochemical, mechanical, and thermal properties of alkali-treated red coconut empty fruit bunch fibers (ARCEFBFs) were reported and compared with other natural fibers for the first time. Cellulose content (65.02 wt%), wax (0.32 wt%), density (1.421 g/cc), and tensile strength (1299.49 MPa) were identified in ARCEFBFs. Fourier transform infrared spectroscopy and X-ray diffraction analysis confirmed that ARCEFBFs are rich in cellulose content with crystallinity index of 53.6%. Thermogravimetric analysis revealed that these fibers are thermally stable until 270.48°C. 相似文献
53.
Filip Ciesielczyk Karolina Szwarc‐Rzepka Teofil Jesionowski 《Surface and interface analysis : SIA》2013,45(6):998-1007
Preparation of a new group of hybrid fillers, of SiO2/silane/oligomeric silsesquioxane type, characterised by specific desirable physicochemical properties, was studied. Synthetic SiO2 was precipitated by the emulsion method. At first, as a result of improved adhesion between SiO2 and selected POSS compound, SiO2 surface was functionalised with alkoxysilanes containing characteristics functional groups. Functionalised SiO2 was used in the process of hybrid filler preparation according to hydrolytic condensation using methacryl POSS® mixture. To evaluate potential application of such fillers, SiO2 systems, bifunctionalised using innovative method, were thoroughly characterised to determine their physicochemical properties as well as the effectiveness of functionalisation with silanes and POSS compound. Proposed method of SiO2 surface modification using selected alkoxysilanes and oligosilsesquioxanes is innovative and gives very promising results. Bifunctionalisation of inorganic fillers with those compounds will substantially extended the range of their applications and probably will lead to improvement of mechanical properties of final polymer composites and reduction in the cost of their production which is the main feature of this research. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
54.
周义仓 《数学建模及其应用》2013,2(1):60-66
根据评卷过程中收集到的信息对2012年全国大学生数学建模竞赛的“葡萄酒的评价”问题进行分析,展示了一些较好的模型和结果,并针对答卷中反映的问题提出一些建议。 相似文献
55.
56.
Buchi N. Nalluri K.P.R. Chowdary K.V.R. Murthy V. Satyanarayana A.R. Hayman G. Becket 《Journal of inclusion phenomena and macrocyclic chemistry》2005,53(1-2):103-110
The purpose of the work is physicochemical characterization of nimesulide (NI) and meloxicam (ME)–hydroxypropyl-β-cyclodextrin
(HP-β-CD) binary systems both in solution and solid states and to improve the pharmaceutical properties of NI and ME via inclusion
complexation with HP-β-CD. Binary systems of NI and ME with HP-β-CD have been characterized both in solution and solid state
by different physicochemical methods. Three types of drug–HP-β-CD binary systems, namely physical mixtures (PM), kneaded systems
(KS) and co evaporated systems (CS) in 1:1 and 1:2 molar ratios (1:1 and 1:2 M) were prepared. Phase solubility and 1H-NMR spectroscopic studies in solution state revealed 1:1 M complexation of NI and ME with HP-β-CD. A partial inclusion of
NI with HP-β-CD at both molar ratios of kneaded and co evaporated systems and a true inclusion of ME with HP-β-CD at both
molar ratios of co evaporated systems in solid state was confirmed by differential scanning calorimetry (DSC), powder X-ray
diffractometry (powder X-RD) and scanning electron microscopy (SEM) studies. Dissolution properties of NI and ME–HP-β-CD binary
systems were superior when compared to corresponding pure drugs. The aqueous solubility and dissolution properties of NI and
ME can be improved by inclusion complexation with HP-β-CD.
Author for correspondence: E-mail: nbnaid2@E-mail.uky.edu 相似文献
57.
仪器设备计量管理的主要内容是通过不确定度、M_(cp)值计算或重复性试验判断仪器设备配备的合理性,开展仪器设备的计量检定、校验和检验,建立标志和技术档案等管理,使仪器设备始终处于正常的工作状态。 相似文献
58.
E. A. Smolenskii G. V. Vlasova D. Yu. Platunov A. N. Ryzhov 《Russian Chemical Bulletin》2006,55(9):1508-1515
Optimal topological indices for particular physicochemical properties can be designed using the chemical structure matrix.
Taking the alkane boiling points as examples, the extrapolation properties of some well-known topological indices were compared
with those of the optimal topological indices designed ad hoc. The advantages of the new indices are shown.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1454–1461, September, 2006. 相似文献
59.
Separation and characterization of products from thermal cracking of individual and mixed polyalkenes 总被引:1,自引:0,他引:1
Low-density polyethylene (LDPE), polypropylene (PP), and their mixture in the mass ratio of 1: 1 (LDPE/PP) were thermally
decomposed in a batch reactor at 450°C. The formed gaseous and oil/wax products were separated and analyzed by gas chromatography.
The oils/waxes underwent both atmospheric and vacuum distillation. Densities, molar masses and bromine numbers of liquid distillates
and distillation residues were determined. The first distillate fraction from the thermally decomposed LDPE contained mostly
linear alkanes and alk-1-enes ranging from C6 to C13 (boiling point up to 180°C). The second distillate fraction was composed mostly of hydrocarbons C11 to C22 (boiling point up to 330°C). 2,4-Dimethylhept-1-ene was the major component of the first distillate fraction obtained from
the product of PP decomposition, while in the 2nd distillate fraction it was 2,4,6,8-tetramethylundec-1-ene. The yields of
some gaseous or liquid hydrocarbons obtained by distillation from thermally degraded LDPE/PP differed from the values corresponding
to the decomposition of individual plastics due to the mutual influence of polyalkenes during their thermal cracking. Similarly,
the yields of propene and methylpropene in the gaseous phase were higher in the case of mixture. Whereas the content of C9 to C17 alkanes and alkenes in the distillates separated from the liquid mixture obtained by the decomposition of LDPE/PP decreased,
the formation of 2,4,6,8,10,12-hexamethylpentadec-1-ene remained unchanged. The corresponding mechanisms of thermal cracking
were discussed. 相似文献
60.
Elżbieta Szczepaniec-Cieciak Małgorzata Krzeczkowska 《Journal of solution chemistry》1999,28(10):1175-1185
The solubilities of solid pentane, 2-methylbutane (isopentane), and cyclopentane in liquid argon at 87.3 K have been measured by the filtration method. The C5 hydrocarbon content in solution was determined using gas chromatography. The solubilities of the C5 hydrocarbons in liquid argon at 87.3K vary from 0.61 × 10–7 mole fraction for cyclopentane, to 1.37 × 10–7 mole fraction for pentane, and 8.83 × 10–6 mole fraction for 2-methylbutane. The Preston–Prausnitz method was used for calculation of the solubilities of solid C5 hydrocarbons in liquid argon in the temperature range 84–110 K and in liquid nitrogen in the range 64–90K. The values of the solvent–solute interaction constant l
12 were also calculated. 相似文献