排序方式: 共有93条查询结果,搜索用时 15 毫秒
61.
Sawant SN Doble M Yakhmi JV Kulshreshtha SK Miyazaki A Enoki T 《The journal of physical chemistry. B》2006,110(48):24530-24540
Langmuir-Blodgett (LB) films of the water-soluble dye phenosafranine (PS) have been prepared by its adsorption from aqueous dye solution to an arachidic acid (AA) monolayer at the air-water interface. Atomic force microscopy (AFM) images of the LB films revealed the effect of change in pH of deposition on the degree of complexation of AA with the PS dye. Well-defined circular islands and holes were observed which disappeared with the increase in pH. Polarized absorption studies indicated that the dye molecules are oriented uniaxially with their long axis titled at a constant angle to the surface normal of the LB film. Within the restricted geometry of the LB film, the PS dye was electropolymerized to form a two-dimensional film of poly(phenosafranine) sandwiched between arachidic acid layers. The film was characterized by IR spectroscopy, cyclic voltammetry, and AFM. X-ray diffraction studies reveal the presence of a layer structure in the AA-PS LB film before and after polymerization. The polymer film showed highly anisotropic electrical conductivity of ca. 10 orders of magnitude. This indicates the formation of two-dimensional polyPS layers between arachidic acid layers resulting in a layered heterostructure film having alternate conducting and insulating regions. Also, the conductivity of the polyPS prepared from LB film was found to be approximately 2.5 times higher than the conductivity of polyPS prepared by solution polymerization method. 相似文献
62.
Saba Kauser Jaweed Shaikh Shilpa M. Somagond Atulkumar A. Kamble Mahadev N. Kumbar 《合成通讯》2018,48(16):2061-2073
Microwave-assisted green approach is developed for an efficient synthesis of thiazol-2-imines under catalyst-free conditions. The desired products are formed by one-pot three-component reaction which is an improvised method for Hantzsch thiazole synthesis. The microwave-assisted protocol gives excellent yields with high purity in just 10–15?min. All the synthesized compounds have been screened for antifungal activity and some of the derivatives show a broad spectrum against fungal pathogens. 相似文献
63.
Tan H Wang M Yang CT Pant S Bhakoo KK Wong SY Chen ZK Li X Wang J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(24):6696-6706
We describe here a facile and benign synthetic strategy to integrate the fluorescent behavior of conjugated polymers and superparamagnetic properties of iron oxide nanocrystals into silica nanocapsules, forming a new type of bifunctional magnetic fluorescent silica nanocapsule (BMFSN). The resultant BMFSNs are uniform, colloidally stable in aqueous medium, and exhibit the desired dual functionality of fluorescence and superparamagnetism in a single entity. Four conjugated polymers with different emissions were used to demonstrate the versatility of employing this class of fluorescent materials for the preparation of BMFSNs. The applicability of BMFSNs in cellular imaging was studied by incubating them with human liver cancer cells, the result of which demonstrated that the cells could be visualized by dual-mode fluorescence and magnetic resonance imaging. Furthermore, the superparamagnetic behavior of the BMFSNs was exploited for in vitro magnetic-guided delivery of the nanocapsules into the cancer cells, thereby highlighting their potential for targeting biomedical applications. 相似文献
64.
Yingfei Xue Prashanth Ravishankar M. Alejandra Zeballos Vinayak Sant Kartik Balachandran Shilpa Sant 《先进技术聚合物》2020,31(1):94-106
Fibrous scaffolds, which can mimic the elastic and anisotropic mechanical properties of native tissues, hold great promise in recapitulating the native tissue microenvironment. We previously fabricated electrospun fibrous scaffolds made of hybrid synthetic elastomers (poly(1,3‐diamino‐2‐hydroxypropane‐co‐glycerol sebacate)‐co‐poly (ethylene glycol) (APS‐co‐PEG) and polycaprolactone (PCL)) to obtain uniaxial mechanical properties similar to those of human aortic valve leaflets. However, conventional electrospinning process often yields scaffolds with random alignment, which fails to recreate the anisotropic nature of most of the soft tissues such as native heart valves. Inspired by the structure of native valve leaflet, we designed a novel valve leaflet‐inspired ring‐shaped collector to modulate the electrospun fiber alignment and studied the effect of polymer formulation (PEG amount [mole %] in APS‐co‐PEG; ratio between APS‐co‐PEG and PCL; and total polymer concentration) in tuning the biaxial mechanical properties of the fibrous scaffolds. The fibrous scaffolds collected on the ring‐shaped collector displayed anisotropic biaxial mechanical properties, suggesting that their biaxial mechanical properties are closely associated with the fiber alignment in the scaffold. Additionally, the scaffold stiffness was easily tuned by changing the composition and concentration of the polymer blend. Human valvular interstitial cells (hVICs) cultured on these anisotropic scaffolds displayed aligned morphology as instructed by the fiber alignment. Overall, we generated a library of biologically relevant fibrous scaffolds with tunable mechanical properties, which will guide the cellular alignment. 相似文献
65.
66.
Shilpa M Nagababu P Kumar YP Latha JN Reddy MR Karthikeyan KS Gabra NM Satyanarayana S 《Journal of fluorescence》2011,21(3):1155-1164
Three symmetric ligands 7-methyl dipyrido-[3,2-a;2′,3′-c]phenazine (dppz-CH3), 7-nitro dipyrido-[3,2-a;2′,3′-c]phenazine (dppz-NO2) and benzo[i]dipyrido-[3,2-a;2′,3′-c]phenazine (dppn) and their ruthenium(II) complexes [Ru(en)2(L)][ClO4]2 (en= ethylenediamine), L= dppz-CH3, dppz-NO2 and dppn have been synthesized and characterized by IR, 1H, 13C NMR and Mass spectra. The interactions of these complexes with calf thymus DNA have been investigated by spectrophotometric,
spectrofluorimetric, circular dichroism, viscosity and thermal denaturation studies. As the planar extension of the intercalative
ligand increases, the interaction of the complex with DNA increases, indicating that the size and shape of the intercalalative
ligand has a marked effect on the strength of interaction. The plot of log K versus log [Na+] yield a slope of -1.26, -1.53, -1.60 for the complexes 1, 2 and 3 respectively. These three complexes have been found to
promote the cleavage of plasmid pBR 322 DNA upon irradiation. 相似文献
67.
Multisite and multivalent binding between cyanovirin-N and branched oligomannosides: calorimetric and NMR characterization 总被引:5,自引:0,他引:5
Shenoy SR Barrientos LG Ratner DM O'Keefe BR Seeberger PH Gronenborn AM Boyd MR 《Chemistry & biology》2002,9(10):1109-1118
Binding of the protein cyanovirin-N to oligomannose-8 and oligomannose-9 of gp120 is crucially involved in its potent virucidal activity against the human immunodeficiency virus (HIV). The interaction between cyanovirin-N and these oligosaccharides has not been thoroughly characterized due to aggregation of the oligosaccharide-protein complexes. Here, cyanovirin-N's interaction with a nonamannoside, a structural analog of oligomannose-9, has been studied by nuclear magnetic resonance and isothermal titration calorimetry. The nonamannoside interacts with cyanovirin-N in a multivalent fashion, resulting in tight complexes with an average 1:1 stoichiometry. Like the nonamannoside, an alpha1-->2-linked trimannoside substructure interacts with cyanovirin-N at two distinct protein subsites. The chitobiose and internal core trimannoside substructures of oligomannose-9 are not recognized by cyanovirin-N, and binding of the core hexamannoside occurs at only one of the sites on the protein. This is the first detailed analysis of a biologically relevant interaction between cyanovirin-N and high-mannose oligosaccharides of HIV-1 gp120. 相似文献
68.
The biodegradation of fluoranthene, a high molecular weight polycyclic aromatic hydrocarbon (PAH), was investigated in submerged
culture using the wood decaying fungus isolated from forest locality in Gujarat, India. The basidiomycete fungal isolate was
found to have an ability to grow on sabaroud dextrose agar containing 50 mgl−1 of each naphthalene, anthracene, acenaphthene, benzo (a) anthracene, pyrene, flouranthene, carbazole, and biphenyl. The involvement
of extracellular fungal peroxidases such as manganese peroxidase (MnP) and laccase (Phenol oxidase) in the degradation of
fluoranthene was studied. On the eighth day of incubation 54.09% of 70 mg l−1 fluoranthene was removed. There after no PAHs removal was observed till the 20th day of the incubation period. The isolate
was identified as Pleurotus ostreatus by 18S rRNA, 5.8S rRNA, and partial 28S rRNA gene sequencing. To the best of our knowledge this is the first time Pleurotus ostreatus have been reported to degrade such a high concentration of fluoranthene within much lower time period of incubation. Depletion
in the residual fluoranthene in the culture medium was determined by HPLC. Attempts were made to identify the degradation
product in the culture medium with the help of FT-IR, NMR, and HPTLC analysis. In the present study positive correlation between
fluoranthene degradation and the ligninolytic enzyme (MnP and laccase) production is observed, thus this isolate can play
an effective role for bioremediation of PAHs contaminated sites. 相似文献
69.
A simple and convergent synthesis of the title compounds has been achieved involving Zn-Cu couple catalysed conjugate addition of allylic halides to alpha,beta-unsaturated carbonyl compounds promoted by ultrasonic waves in aqueous medium as a key step in good overall yields. 相似文献
70.
Vital properties (structural and thermo-elastic) of materials are affected on the application of pressure and temperature. These properties play a key role in understanding the thermodynamic behavior and equation of state. Thus, we have formulated a realistic interaction potential model to study the structural and thermo-elastic of US and ThS including the temperature effects. This model is used for the present compounds in a high-pressure study including temperature effects. We have computed phase transition pressures, volume drop, elastic and thermal properties at different pressures, and elevated temperatures. Our results are in agreement with available experimental and theoretical data. 相似文献