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1.
Siriporn Angkanasiriporn Wuttipong Singsung Amorn Petsom Thumnoon Nhujak 《Electrophoresis》2010,31(4):695-701
Retention index (I), rather than retention factor (k), was found to be a more reasonable parameter for comparison of the relative affinity of disubstituted benzenes in MEEKC and MEKC, due to independent of I with the SDS surfactant concentration. MEKC and MEEKC may give similar or different I values, depending on types of moieties. With known I and Kow for alkylbenzenes as references in MEKC and MEEKC, the values of Kow for disubstituted benzenes can be estimated from the observed I values, where Kow is the octanol–water distribution constant. In addition, a group additive approach can be used to predict I for disubstituted benzenes with different moieties from the average observed I for the disubstituted benzenes with same moieties. However, electronic effects and/or intramolecular interaction may result in the different observed I from prediction. 相似文献
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Synthesis of dehydrorotenoid (1) was successfully achieved via an intramolecular aldol reaction of the corresponding 1,2-diaryl diketone intermediate. The 1,2-diaryl diketone was prepared using a ruthenium-catalyzed oxidation of the corresponding substituted diaryl acetylene. Treatment of this 1,2-diketone with l-proline induced a selective intramolecular aldol condensation reaction, forming the desired benzopyranone over the alternative benzofuran. Deprotection, cyclization, and dehydration gave the target compound in good overall yield. 相似文献
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Sophon Roegsumran Nongnuj Jaiboon Narongsak Chaichit Damrong Sommit Duangpen Pattamadilok Chaiyo Chaichantipyuth Amorn Petsom 《Journal of chemical crystallography》2002,32(12):511-517
Two labdane diterpenoids, labda-7,12(E),14-triene-17-oic acid (1) and labda-12(Z),14,17-triene-18-oic acid (2), C20H30O2, have been isolated from Croton oblongifolius. Both 1 and 2 crystallized in the monoclinic system, space group C2, with cell dimensions of a = 21.912(1) Å, b = 7.4002(4) Å, c = 11.5079(7) Å, = 101.999(1)o and a = 21.308(2) Å, b = 11.9067(9) Å, c = 7.5606(6) Å, = 100.763(1)o, respectively. Compound 1, a rare example of carboxylic group bound to a cyclohexene ring, forms an infinite intermolecular hydrogen-bonded polymer [O1 O2(–x + 1/2, y + 1/2, –z + 2) 2.697(2) Å], whereas molecules of compound 2 are linked to form an asymmetric hydrogen-bonded dimer [O1 O2(–x, y, –z) 2.657(3) Å]. 相似文献
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Siriluk Namwong Md. Zahidul Islam Sayrung Noppalit Pramuan Tangboriboonrat Preeyaporn Chaiyasat 《高分子科学杂志,A辑:纯化学与应用化学》2016,53(1):11-17
Octadecane (OD), a heat storage material, was encapsulated into poly(divinylbenzene-co-methyl methacrylate) or P(DVB-co-MMA) matrix via the microsuspension polymerization. The oil droplets were first generated by using the phase inversion emulsification, i.e., adding a sodium dodecyl sulphate (SDS) aqueous solution into an oil phase (monomers:OD = 1:1) containing various concentrations of poly(vinyl alcohol) (PVA). Results showed that 0.1 wt% of SDS in aqueous medium with the additional rate of 2 mL/min and 3 wt% of PVA in oil phase were the optimal conditions for the formation of nonspherical microcapsules. The smallest number- (dn) and weight- (dw) average diameters of P(DVB-co-MMA)/OD were, respectively, 3.1 and 3.2 µm with a narrow particle size distribution (dw/dn) of 1.02. The latent heats of the encapsulated OD increased with increasing MMA content of microcapsules. The heat of melting (ΔHm; 223 J/g-OD) and crystallization (ΔHc; 230 J/g-OD) of the OD encapsulated in microcapsules using DVB:MMA of 30:70 were higher than those using only PDVB (189 and 193 J g-OD for ΔHm and ΔHc, respectively) and comparable to those of bulk OD (233 and 234 J/g-OD for ΔHm and ΔHc, respectively). The obtained P(DVB-co-MMA)/OD microcapsules would be useful as high performance heat storage material. 相似文献
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Amorn Slosse Filip Van Durme Nele Samyn Debby Mangelings Yvan Vander Heyden 《Molecules (Basel, Switzerland)》2021,26(21)
Cannabis sativa L. is widely used as recreational illegal drugs. Illicit Cannabis profiling, comparing seized samples, is challenging due to natural Cannabis heterogeneity. The aim of this study was to use GC–FID and GC–MS herbal fingerprints for intra (within)- and inter (between)-location variability evaluation. This study focused on finding an acceptable threshold to link seized samples. Through Pearson correlation-coefficient calculations between intra-location samples, ‘linked’ thresholds were derived using 95% and 99% confidence limits. False negative (FN) and false positive (FP) error rate calculations, aiming at obtaining the lowest possible FP value, were performed for different data pre-treatments. Fingerprint-alignment parameters were optimized using Automated Correlation-Optimized Warping (ACOW) or Design of Experiments (DoE), which presented similar results. Hence, ACOW data, as reference, showed 54% and 65% FP values (95 and 99% confidence, respectively). An additional fourth root normalization pre-treatment provided the best results for both the GC–FID and GC–MS datasets. For GC–FID, which showed the best improved FP error rate, 54 and 65% FP for the reference data decreased to 24 and 32%, respectively, after fourth root transformation. Cross-validation showed FP values similar as the entire calibration set, indicating the representativeness of the thresholds. A noteworthy improvement in discrimination between seized Cannabis samples could be concluded. 相似文献
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Simple equations and theoretical models, related to enantioselectivity (kappa) and C, have been developed for prediction of electrophoretic mobility difference (Deltamu) and separation selectivity (alpha) for enantiomers in CE using dual CDs, where alpha and kappa are defined as the ratio of mu and the ratio of binding constant (K) for enantiomers to each CD, respectively, C the CD concentration, and the average K for enantiomers and each CD. Experiments were carried out using dual CDs as beta-CD and dimethyl-beta-cyclodextrin (DM-beta-CD) and test analytes as five pairs of amphetamine drug enantiomers. A change in observed Deltamu and alpha of enantiomers in dual CDs was found to be in excellent agreement with the theoretical models. For example, in comparison with single CD1, dual CDs can enhance Deltamu and alpha up to the maximum value when enantiomers migrate with the same order in CD1 and CD2, and have the value of rho > 1.0, where rho is the enantioselectivity ratio for CD2 to CD1, while worse Deltamu and alpha are obtained for enantiomers with rho < 1.0. 相似文献
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Preeyaporn Chaiyasat Yumiko Ogino Toyoko Suzuki Masayoshi Okubo 《Colloid and polymer science》2008,286(6-7):753-759
The influence of a water domain formed in n-hexadecane (HD) core in cross-linked polymer capsule particles on the thermal properties of encapsulated HD was studied from the view point of heat storage application. The capsule particles were prepared by micro-suspension polymerization of divinylbenzene at 70 °C utilizing the Self-assembling of Phase-Separated Polymer (SaPSeP) method that the authors proposed. The water domain was not observed for particles taken just after the polymerization and kept at 70 °C, but it was gradually formed with an increase of the size during cooling process from 70 °C to room temperature. In differential scanning calorimetric thermograms, pure HD had a single peak because of solidification (T s) at 15 °C, and the encapsulated HD containing the water domain had two peaks of T s1 and T s2, at 6 and 1 °C, respectively. That is, the encapsulated HD containing the water domain required longer time and lower temperature to complete the solidification than the pure HD, which is negative for its application. However, the lower temperature-side peak at T s2 gradually disappeared with an increase of capsule particle diameter, which seems to be based on the decrease of total interfacial area between the water domains and encapsulated HD in the capsule particles. 相似文献
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Richard S. Glass Massoud Hojjatie Amorn Petsom George S. Wilson Manfred Göbl Sabine Mahling 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):143-168
Abstract Oxidation of thioethers is greatly facilitated by neighboring group participation by carboxylate, alcohol, and thioether moieties. 相似文献