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261.
We introduce a version of logic for metric structures suitable for applications to C*-algebras and tracial von Neumann algebras. We also prove a purely model-theoretic result to the effect that the theory of a separable metric structure is stable if and only if all of its ultrapowers associated with nonprincipal ultrafilters on ? are isomorphic even when the Continuum Hypothesis fails. 相似文献
262.
The kinetics of the oxidation of [Ni(II)(H2L1)](ClO4)2, (H2L1 = 3,8-dimethyl-4,7-diaza-3,7-decadiene-2,9-dione dioxime) and [Ni(II)(HL2)]ClO4, (H2L2 = 3,9-dimethyl-4,8-diaza-3,8-undecadiene-2,10-dione dioxime) by peroxodisulfate anion (PDS) in aqueous media at 298.0 K have been studied. The kinetics of oxidation of both Ni(II) complexes was found to be first order in the complex concentration. The dependence of the pseudo-first-order rate constant, k obs, for both complexes showed first-order dependence on PDS concentration. The kinetics of oxidation of [Ni(II)(H2L1)]2+ complex showed a complex dependence on [H+] over the pH range of 4.98–7.50, whereas that of [Ni(II)(HL2)]+ is independent of pH over the pH range of 5.02–7.76. The value of k obs, for both complexes, decreased with increasing ionic strength consistent with the involvement of oppositely charged ions in the rate-determining step. The effect of ionic strength is more pronounced for [Ni(II)(H2L1)]2+–PDS reaction than for [Ni(II)(HL2)]+–PDS reaction, confirming the higher charges of the latter. 相似文献
263.
Hidayat Hussain Natalia Root Farah Jabeen Ahmed Al-Harrasi Ahmed Al-Rawahi Manzoor Ahmad Zahid Hassan Ghulam Abbas Fazal Mabood Afzal Shah Amin Badshah Amjad Khan Riaz Ahmad Ivan R. Green Siegfried Draeger Barbara Schul Karsten Krohn 《中国化学快报》2014,25(12):1577-1579
A new metabolite,named seimatoric acid(1),representing a new oxobutanoic acid derivative has been isolated from Seimatosporium sp., in addition to four known compounds viz.,2-hydroxymethyl-4β,5α,6β-trihydroxycyclohex-2-enone(2),(-)-phyllostine(3),(+)-epiepoxydon(4) and(+)-epoxydon monoacetate(5).Similarly one new benzoic acid derivative,named colletonoic acid(6) was isolated from the ethyl acetate fraction of Colletotrichum sp.The structures of the new compounds were elucidated by detailed ~1 H NMR,~(13)C NMR,COSY,HMQC.HMBC spectroscopic analysis,and HR-E1-MS.Seimatoric acid(1)was also isolated from another taxonomical unidentified fungal strain 4295 in ourgroup.The structures of the known compounds were elucidated by their spectral data comparison to literature data.Preliminary studies showed that colletonoic acid(6) showed good antibacterial,antifungal,and antialgal activities. 相似文献
264.
Stabilization of metal nanoparticles (MNP) is a prerequisite for any application in sensor design, optoelectronics, catalysis, spectroscopic labeling, and nanomedicine. However, MNPs produced by most currently available synthetic approaches tend to undergo aggregation into large clusters, thus reducing their accessibility and compromising properties associated with their nanoscale dimensions. To circumvent the agglomeration problem and enhance their chemical and physical stability, we developed an efficient strategy for the preparation of MNP/polymer composites in which silver nanoparticles coated with 4-mercaptomethylstyrene act as crosslinkers in a suspension polymerization. The resulting microspheres were characterized by Raman, SERS and XPS spectroscopies, DSC, SEM and TEM. Their chemical and physical stability was also established. 相似文献
265.
Substituted 3-formylchromones react with 2-phenyl-4-dimethylamino-1-thia-3-azabuta-1,3-diene (4) or thio-benzamide (7) by heating their toluene solution in a sealed tube to give novel substituted 3-(5-phenyl-3H-[1,2,4]dithiazol-3-yl)chromen-4-ones (6a-e) in high yields. 相似文献
266.
Saiful Izwan Abd Razak Farah Nuruljannah Dahli Izzati Fatimah Wahab Mohammed Rafiq Abdul Kadir Ida Idayu Muhamad Abdul Halim Mohd Yusof 《Soft Materials》2016,14(2):78-86
This paper reports for the first time a simple yet effective method for fabricating a conductive and highly porous scaffold material made up of polylactic acid (PLA) and conducting polyaniline (PANI). The electrical percolation state was successfully obtained at 3 wt% of PANI inclusions and reached a conductivity level of useable tissue engineering applications at 4 wt%. In addition, preliminary bioactivity test results indicated that the protonating agent could form a chelate at the scaffold surface leading to good in-vitro apatite forming ability during biomimetic immersion. This new conductive scaffold has potential as a suitable biomedical material that requires electrical conductivity. 相似文献
267.
Farah J. Hashim Sukanda Vichitphan Jaehong Han Kanit Vichitphan 《Molecules (Basel, Switzerland)》2021,26(15)
Tyrosinase (TYR) is a type III copper oxidase present in fungi, plants and animals. The inhibitor of human TYR plays a vital role in pharmaceutical and cosmetic fields by preventing synthesis of melanin in the skin. To search for an effective TYR inhibitor from various plant extracts, a kinetic study of TYR inhibition was performed with mushroom TYR. Among Panax ginseng, Alpinia galanga, Vitis vinifera and Moringa oleifera, the extracts of V. vinifera seed, A. galanga rhizome and M. oleifera leaf reversibly inhibited TYR diphenolase activity with IC50 values of 94.8 ± 0.2 µg/mL, 105.4 ± 0.2 µg/mL and 121.3 ± 0.4 µg/mL, respectively. Under the same conditions, the IC50 values of the representative TYR inhibitors of ascorbic acid and kojic acid were found at 235.7 ± 1.0 and 192.3 ± 0.4 µg/mL, respectively. An inhibition kinetics study demonstrated mixed-type inhibition of TYR diphenolase by A. galanga and V. vinifera, whereas a rare uncompetitive inhibition pattern was found from M. oleifera with an inhibition constant of Kii 73 µg/mL. Phytochemical investigation by HPLC-MS proposed luteolin as a specific TYR diphenolase ES complex inhibitor, which was confirmed by the inhibition kinetics of luteolin. The results clearly showed that studying TYR inhibition kinetics with plant extract mixtures can be utilized for the screening of specific TYR inhibitors. 相似文献
268.
N Muhammad LB Din I Sahidin SF Hashim N Ibrahim Z Zakaria WA Yaacob 《Molecules (Basel, Switzerland)》2012,17(8):9043-9055
A new resveratrol dimer, acuminatol (1), was isolated along with five known compounds from the acetone extract of the stem bark of Shorea acuminata. Their structures and stereochemistry were determined by spectroscopic methods, which included the extensive use of 2D NMR techniques. All isolated compounds were evaluated for their antioxidant activity using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (RSA) and the β-carotene-linoleic acid (BCLA) assays, and compared with those of the standards of ascorbic acid (AscA) and butylated hydroxytoluene (BHT). All compounds tested exhibited good to moderate antioxidant activity in the DPPH assay (IC50s 0.84 to 10.06 mM) and displayed strong inhibition of β-carotene oxidation (IC50s 0.10 to 0.22 mM). The isolated compounds were evaluated on the Vero cell line and were found to be non-cytotoxic with LC50 values between 161 to 830 μM. 相似文献
269.
270.
Umme S. Siddiqui Farah Khan Iqrar A. Khan Kabir-ud-Din 《Journal of solution chemistry》2012,41(7):1133-1143
The effect of adding aliphatic alcohols (C4OH, C5OH, C6OH) and corresponding amines (C4NH2, C5NH2, C6NH2) on a series of dicationic gemini surfactants with the general formula C14H29(CH3)2N+?C(CH2)s?CN+(CH3)2C14H29, 2Br? (14-s-14; s=4,5,6), in the absence and presence of KNO3, has been studied by viscosity measurements at 303.15?K. As the chain length of the additive increased, the viscosity increased with increasing additive concentration and the extent of the effect followed the sequence: C6OH>C5OH>C4OH; C6NH2>C5NH2>C4NH2. The simultaneous presence of salt and additives showed an increase in ?? r values due to a synergistic effect. However, for equal chain lengths in the additives, the effect was greater for the n-alcohols. The tendency for the micelles to grow from spherical to rod-like structures is mainly influenced by the spacer chain length. At 303.15?K, the micellar growth was more pronounced for the shorter spacer, i.e. s being 4, which can be interpreted in terms of the short spacer having a higher tendency for micellar growth. Contrary to the cationic geminis, no effect was observed with a conventional surfactant of equal chain length, TTAB, even in the presence of KNO3 at the same concentration used for the geminis. 相似文献