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61.
AbstractIn this work, an effective method was developed to prepare novel PEO-b-PPO-b-PEO (EPE)/α-cyclodextrin (α-CD) supramolecular hydrogels containing exfoliated graphite nanoplates (xGNPs) by mixing an aqueous solution of α-CD with an aqueous dispersion of xGNPs at the presence of amphiphilic EPE copolymer. The EPE copolymer played three important roles in the preparation process: (1) as an exfoliating agent to break expanded graphites into xGNPs under ultrasonication, (2) as a dispersant to stabilize xGNPs in the aqueous solution, and (3)as a component to form the inclusion complexes with α-CD. The resultant xGNPs/EPE/α-CD hybridized hydrogels were characterized by scanning electron microscopy, wide-angle X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared spectroscopy, which confirmed not only the formation of supramolecular hydrogel structure but also the homogenous dispersion of xGNPs in the hydrogel matrix. It was found that the existence of xGNPs can accelerate the speed of gel formation in comparison with that of the native EPE/α-CD hydrogel. Additionally, the water-retention ability and the release behavior of vancomycin hydrochloride for the xGNPs/EPE/α-CD hybridized hydrogels were investigated. 相似文献
62.
Thressa C. Stadtman 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-2):199-216
Abstract Some enzymes known to contain selenium are enumerated. In four of them which catalyze coupled oxidation-reduction reactions the selenium occurs exclusively in the form of selenocysteine residues. Their structure and function are described in detail. Two other bacterial enzymes which contain selenium in the form of a labile, readily dissociable component are also described. Results on the isolation, identification and structure determination of selenium-containing amino acid transfer ribonucleic acids are presented. These seleno-t RNA's are shown to contain either 5-methyl-aminomethyl-2-selenouridine or other 2-selenouridine derivatives. The role of selenium in a glutamate iso-accepter species is discussed. 相似文献
63.
Bin Wang Zhi-Wei Miao Ru-Yu Chen 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2739-2748
A series of naphthoquinone-fused phosphorus heterocycles was synthesized via a three-component Mannich-type reaction. 2-Chloroethoxylphosphorodichloridite was used as a phosphorus substrate to explore the structure–activity relationships of the 2-position of the heterocycles. One spiral heterocycle compound was structurally characterized by a single-crystal X-ray diffraction analysis. 相似文献
64.
Wu Tang Zhi-Hua Yu De-Qing Shi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2024-2029
Target compounds 3 were synthesized by the condensation of O,O-diethyl α-amino substitutedbenzyl phosphonates 1 and 4-methyl-[1,2,3]thiadiazole-5-carboxylic acid 2 in the presence of dicyclohexylcarbodiimide (DCC) as a dehydration reagent. Their structures were confirmed by spectroscopic data (IR, 1H NMR, 31P NMR, MS) and elemental analysis. The results of a preliminary bioassay (in vitro) indicated that some of the title compounds 3 possessed moderate to good herbicidal activities against dicotyledonous plants (Brassica campestris L) at the concentration of 100 mg/L, and most of these compounds exhibited higher herbicidal activities against dicotyledonous plants (Brassica campestris L) than monocotyledonous plants (Echinochloa crus-galli). Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. 相似文献
65.
The First Mitsunobu Protocol for Efficient Synthesis of α-Acyloxyphosphonates Using 4,4′-Azopyridine
Nasser Iranpoor Habib Firouzabadi Dariush Khalili 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2166-2171
Abstract This is the first report on applying the Mitsunobu protocol for the synthesis of various α-acyloxyphosphonates using 4,4′-azopyridine and PPh3 with diverse aromatic and aliphatic carboxylic acids. Under these conditions, diethyl azodicarboxylate (DEAD) as the traditional reagent for Mitsunobu reaction is not efficient. The insoluble pyridine hydrazine byproduct can be simply isolated and recycled to its azopyridine by an oxidation reaction and reused again. [Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental resource: Characterization data of compounds 3a–3z2 and NMR spectra.] GRAPHICAL ABSTRACT 相似文献
66.
67.
Harika Patnala Hanna S. Abbo Krishna Murthy Potla 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):1035-1039
AbstractAn efficient and eco-friendly protocol has been accomplished for a series of novel α-diaminophosphonates by a one-pot, three-component system via Kabachnik-Fields reaction of 4,4′-methylenedianiline, a variety of aryl/heteroaryl aldehydes and diphenylphosphite employing polyethylene glycol (PEG-400) as a green solvent at 80?°C. All products were obtained in good to excellent yields (80–95%). The identity of the new synthesized compounds was confirmed by IR, 1H, 13C, and 31P NMR, LC-MS and elemental analysis. In vivo anti-viral activity was evaluated against tobacco mosaic virus (TMV). Compounds 4b, 4c, 4j and 4k exhibited the highest anti-viral activities against tobacco mosaic virus (TMV) when compared with the standard drug ningnanmycin. 相似文献
68.
Wagnat W. Wardakhan Hatem M. Gaber Salama A. Ouf Sherif M. Sherif 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):601-618
Abstract Heterocyclic enamines1 reacted with ethyl acetoacetate to afford the corresponding amide derivatives2. Treatment of2 with carbon disulphide yielded the dipotassium salts3which reacted in-situ with a variety of α -haloketones to give the respective substituted thiophenes5,8, and13. The reactivity of the latter products towards various chemical reagents was studied to yield their fused thiophene derivatives7,10,12, and14, respectively. Some representative compounds were tested for antimicrobial activity. 相似文献
69.
M. E. Carlotti S. Sapino M. Gallarate M. Trotta R. Cavalli E. Ugazio 《Journal of Dispersion Science and Technology》2013,34(10):1445-1459
Aescin is an important active substance composed of saponin glucosides topical employed in the treatment of inflammatory and edematous conditions. A particular kind of skin care product called α-gel lamellar phases emulsion was developed, containing β-escin. Detailed knowledge of the lamellar phases behavior has been obtained by DSC, rheological measurements and polarized-light optical microscopy. Moreover the effects of lamellar phases on β-escin release profiles have been studied. 相似文献
70.
A novel [4 + 1] annulation protocol for the synthesis of polysubstituted pyrrole derivatives from β-keto acids and α,β-unsaturated imines via a tandem Michael addition, decarboxylation and TBAI-catalyzed oxidative annulation has been developed. This method provides a new and facile application of β-keto acids as 1,1-nucleophilic/electrophilic type C1 synthons. 相似文献