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31.
32.
The microstructure of films of ternary graft copolymers of aromatic polyimide, ?-caprolactam, and ω-dodecanelactam has been studied by atomic force microscopy. It is shown that an increase in the content of ω-dodecanelactam units in copolymers leads to an increase in the diameter of spherulites composed of fibrils. Simultaneously, water absorption decreases and the mechanical properties and crystallinity of copolymer films change.  相似文献   
33.
Transport properties and crystallochemical features of lithium-containing lanthanum metaniobates La2/3 – x Li3x4/3 – 2x Nb2O6 with the structure of fault perovskite are studied. The materials studied have high conductivity by lithium ions. A correlation between the conductivity magnitude, chemical composition, and crystallographic parameters is found.  相似文献   
34.
Russian Journal of Organic Chemistry - A new synthesis of N-(5-hydroxynicotinoyl)-L-glutamic acid via a 5-hydroxynicotinic acid imidazolide intermediate has been developed. Its calcium salt...  相似文献   
35.
The economical and environmentally benign synthesis of SSZ-13 zeolite was possible due to the mechanochemical activation of dry reagents by planetary mill. Contrary to manual grinding in a mortar, the proposed automatized approach is scalable and reproducible. This solvent-free process provided a huge gain in product/gel ratios, significantly minimized reaction space and organic structure-directing agent use, and allowed for the elimination of agitation. Obtained materials were comparable to the product of “classical” syntheses. The use of different silica sources resulted in SSZ-13 zeolites with various characteristics: different Si/Al ratio and crystal size.  相似文献   
36.
A new procedure was developed for the simultaneous determination of water- and fat-soluble vitamins by microemulsion electrokinetic chromatography. Using microemulsions based on sodium dodecyl sulfate, Brij 35, 1-butanol, and heptane, 10 vitamins were separated (4 water-soluble and 6 fat-soluble) within 35 min. The efficiency of the separation was 800000 theoretical plates (effective capillary length, 40 cm). To enhance the selectivity, 2-propanol was used as a hydrophobizing addition into the microemulsion. The procedure was used for analyzing a kaolin-based vitamin premix. The use of microemulsion as an agent for extracting vitamins from the support considerably simplifies the sample preparation.  相似文献   
37.
Polycrystalline indium antimonide samples codoped with manganese (0.8–1 at %) and cadmium (3.9 at %) are prepared by quenching from melt. Despite the high contents of these dopants, only InSb maxima are observed in X-ray diffraction patterns of these samples. As probed by magnetic studies, the samples are ferrimagnets having Curie points of about 577 K and room-temperature specific magnetizations of σ ≈ 0.5 G cm3/g (H = 6 kOe). We suggest that the magnetic properties of the samples are dictated by InSb〈Mn,Cd〉 microinclusions, which are located in grain boundaries and dislocations.  相似文献   
38.
The methods of gas-liquid chromatography and mass-selective detection were used to determine the composition of the volatile fraction of plant extracts included in herb mixtures used for treating parodontal disease. The following marker substances were found: naphthalene derivatives for pot marigold, furan derivatives for trifid bur-marigold and burnet, and the specific terpenoids for licorice, milfoil, and wild marjoram. All the plants used in the herb mixture, except for pot marigold and cinquefoil, were analyzed (ion-exclusion chromatography) for the content of lower carboxylic acids. It was established that the specific acids for the wild marjoram and licorice are ascorbic and the succinic acids, respectively.  相似文献   
39.
A technique for the quantitative determination of capsaicin in liniments by the microemulsion liquid chromatography method is proposed. Due to the absence of the homogenization, extraction and filtration stages, the procedure of sample pretreatment takes 5 minutes, which is much more rapid in comparison with the variants described in the literature (from 30 minutes to 12 hours). The full time of the analysis (including the procedure for sample pretreatment) is 20 minutes. The graduation curve is linear in the range from 0.02 to 240 mg/l. The limit of determination of capsaicin was 8 μg/I.  相似文献   
40.
The limits of neodymium substitution for yttrium in (Y, Nd)Al3(BO3)4 crystals in preparation from solutions in molten potassium trimolybdate have been studied. The maximum neodymium concentration in the crystals was 72 at.%, this corresponding to the ratio Nd:Y = 1 in the solution. When this ratio exceeds unity, only potassium-neodymium molybdate is formed. The distribution coefficient for neodymium is greater than unity and decreases both with the increasing Nd/Y ratio in the melt and with decreasing growth rate of the crystals. The unit cell parameters change in the series YAl3(BO3)4 NdAl3(BO3)4 in a non-steady manner, this indicating that the structure is inclined to disordering.  相似文献   
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