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91.
Viscosity measurements under Newtonian flow conditions had been performed on cetyltrimethylammonium bromide (CTAB) aqueous
solutions in the combined presence of sodium salts of aromatic acids (sodium salicylate, NaSal; sodium benzoate, NaBen; sodium
anthranilate, NaAn) and organic additives (1-hexanol, C6OH; n-hexylamine, C6NH2) at 30°C. On addition of C6OH or C6NH2, the viscosity of 25 mM CTAB solution remained nearly constant without salt as well as with a lower salt concentration. This
is due to low CTAB concentration which is not sufficient to produce structural changes in this concentration range of salts.
However, as the salt concentration was increased further, the effect of C6OH/C6NH2 addition was different with different salts: The viscosity first increased; then a decrease was observed with the former
while with C6NH2 a decrease followed by constancy appeared in plots of relative viscosities (η
r
) vs. organic additive concentrations. At further higher salt concentration, the magnitude of η
r
was much higher. The viscosity increase is explained in terms of micellar growth and the decrease in terms of swollen micelle
formation (due to interior solubilization of organic additive) or micellar disintegration (due to formation of water + additive
pseudophase). 相似文献
92.
M. M. Ahmad S. Al-Hakim A. Adel Y. Shehata 《Journal of the American Oil Chemists' Society》1983,60(4):837-840
Of 27 amino acids studied, most had some antioxidant activity when added in aqueous solution to either safflower oil or a mixture of sunflower and cottonseed oil (active oxygen and storage methods). Cysteine-HCl, glutamic acid-HCl (in the mixture), and glutamic acid-HCl (in safflower oil) behaved as prooxidants. When added as a solid, most amino acids were ineffective. The protection factors of these amino acids were less than 1.3 in safflower oil with methionine, proline, lysine and cysteine providing the highest activ-ity. In the oil mixture (which had a higher metal content) lysine, arginine, glutamic acid, methionine, and hydroxyproline were anti-oxidant with protection factors of up to 1.85. Chelation of metals by amino acids was presumably responsible for the antioxidant activity. The increase in cysteine concentration up to 1% has more than doubled the protection factor in Bint oil (compared with the 0.01% level), whereas with some other amino acids the increase was either small or slight. 相似文献
93.
Sea urchin-like nanostructures of ZnO consisting of ZnO nanowires with blunt faceted ends were grown on Si (100) substrates by oxidation of metallic Zn at 600 °C. ZnO nanowires having a diameter of 30–60 nm and length of 2–4 Μm were in similar shape with uniform diameter along its entire length with well faceted blunt ends. X-ray diffraction and transmission electron microscope analysis showed that the as-grown nanostructures were highly crystalline with wurtzite hexagonal structure having lattice constants of a=b=3.25 å and c=5.21 å. Room temperature photoluminescence (PL) measurements showed a weak near band-edge emission at 380 nm, but a strong green emission at 500–530 nm. A model for vapor-solid (VS) growth mechanism of ZnO nanowires was presented, in which nucleation of ZnO is crucial for the growth of the nanostructures. 相似文献
94.
Performance analysis of support vector machines classifiers in breast cancer mammography recognition
Support vector machine (SVM) is a supervised machine learning approach that was recognized as a statistical learning apotheosis for the small-sample database. SVM has shown its excellent learning and generalization ability and has been extensively employed in many areas. This paper presents a performance analysis of six types of SVMs for the diagnosis of the classical Wisconsin breast cancer problem from a statistical point of view. The classification performance of standard SVM (St-SVM) is analyzed and compared with those of the other modified classifiers such as proximal support vector machine (PSVM) classifiers, Lagrangian support vector machines (LSVM), finite Newton method for Lagrangian support vector machine (NSVM), Linear programming support vector machines (LPSVM), and smooth support vector machine (SSVM). The experimental results reveal that these SVM classifiers achieve very fast, simple, and efficient breast cancer diagnosis. The training results indicated that LSVM has the lowest accuracy of 95.6107 %, while St-SVM performed better than other methods for all performance indices (accuracy = 97.71 %) and is closely followed by LPSVM (accuracy = 97.3282). However, in the validation phase, the overall accuracies of LPSVM achieved 97.1429 %, which was superior to LSVM (95.4286 %), SSVM (96.5714 %), PSVM (96 %), NSVM (96.5714 %), and St-SVM (94.86 %). Value of ROC and MCC for LPSVM achieved 0.9938 and 0.9369, respectively, which outperformed other classifiers. The results strongly suggest that LPSVM can aid in the diagnosis of breast cancer. 相似文献
95.
Summary A new kind of organic-inorganic hybrid composite was prepared by means of the sol-gel process. The polymer employed was a mixed-isomer aromatic polyamide having good solubility and thermal stability. The silica constituting the inorganic phase was produced by the hydrolysis and condensation of tetramethoxysilane. The bonding between the phases involved aminophenyl-trimethoxysilane, in which the amino group can react with the phthaloyl chloride end-capped polymer, and the methoxysilane groups undergo hydrolysis. The composition of these composites was varied by changing the linear polymer chain length and relative amount of tetramethoxysilane. The gelation time was found to range from a few minutes to several days. Thermogravimetric analyses showed that decomposition starts at approximately 450 °C. Thin films cast from materials having a relatively high silica content were opaque and rigid, but those with low silica content were flexible and transparent. 相似文献
96.
Blending of two polymers in solution is a simple and cost‐effective technique to improve upon the physical and mechanical properties of the component polymers through synergism. To obtain maximum synergy in their properties, the component polymers should be miscible with each other on molecular scale. Polymer blends of complex physicomechanical properties are being actively investigated. Poly(methacrylic acid) (PMAA), a commercial polymer, yields transparent, hard, brittle, and water‐sensitive films. It has been blended with natural polymers like dextran, collagen, and gelatin to obtain films with improved physical and mechanical characteristics. Polyesteramides, which are easily synthesized from vegetable seeds oil, a sustainable resource, have found application in surface coatings. These oligomeric products do not make free standing films in the ambient condition. The polyesteramides from vegetable seeds oil can be used to obtain blend with PMMA of improved mechanical and water absorption properties. In this study, linseed oil polyesteramide (LOPEA) and dehydrated castor oil polyesteramide (DCPEA), the source oils with different unsaturation in their fatty acid chains, were blended with PMAA through mixing in solution in the ratio DCPEA/LOPEA: PMAA as 80/20, 70/30, 60/40, 50/50, 40/60, 30/70, and 20/80. In the first instance, the miscibility of the two components was investigated in solution by viscosity and ultrasonic measurements and in solid phase through differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Moisture absorption by the blend was also studied. DCPEA and LOPEA show immiscibility with PMAA in solution phase while LOPEA with more unsaturation in the fatty acid chain of the oil was found more immiscible than DCPEA. DCPEA shows a narrow miscibility window in the solid phase while LOPEA was found immiscible with PMAA in the solid phase too. Uptake of moisture was found to be markedly reduced in the blends of DCPEA/LOPEA with PMAA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1367–1374, 2007: 相似文献
97.
DXF是AutoCAD与其他软件进行数据交换的CAD通用图形文件格式。实现了一种DXF读取方式并自动生成数控加工代码。传统算法的读取结果无序,不适用于实际加工,针对这一问题根据提取结果及位置关系生成图元轮廓树,并利用最近邻插入算法对图元轮廓优化排序,得到全局优化的最短切割路径,并通过实例证实了算法的有效性,能满足实际自动编程数控系统的工作需要。 相似文献
98.
J. Mustafa M. S. Ahmad Jr. A. Rauf S. M. Osman 《Journal of the American Oil Chemists' Society》1990,67(12):937-939
Branched-chain thioethers have been prepared from methyl 4-oxo-trans-2-hexadecenoate and 9,12-dioxo-trans-10-octadecenoic acid. The reagents involved in these preparations were mercaptoacetic and mercaptopropionic acids. The yields
of these thioethers are almost quantitative. 相似文献
99.
Cyclopropene fatty acids are constituents of seed lipids of various plants, including sources of edible fats, such as cottonseed and kapok. Physiological and toxicological properties of lipids containing cyclopropene acyl moieties are reviewed and the difficulties encountered in the elucidation of the structures of triacylglycerols containing cyclopropene acyl moieties are discussed. A novel method for the analysis of such triacylglycerols is presented. 相似文献
100.
Jamal Mustafa M. S. Ahmad A. Rauf S. M. Osman 《Journal of the American Oil Chemists' Society》1984,61(3):555-558
Methyl 4-oxo-trans-2-octadecenoate (II), when treated with excess hydrazoic acid in the presence of BF3-etherate, produced 66% methyl 5-aza-nonadec-trans-2-enoate (4,5-d)-tetrazole (III), 10% methyl 5-aza-nonadec-4-oxo-trans-2-enoate (IV) and 7% pentadecamide (V). Individual products were characterized by spectral and elemental methods. 相似文献