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排序方式: 共有186条查询结果,搜索用时 15 毫秒
61.
James W. Pavllk Thomas E. Snead James R. Tata 《Journal of heterocyclic chemistry》1981,18(7):1481-1483
Irradiation of aqueous solutions of aikyl substituted 4-pyrones leads to the formation of dihydroxycyclopentenones. These primary products are also photolabile and in certain cases are photochemically converted to furan derivatives. 相似文献
62.
Recent advances in heterogeneous TiO2 photocatalysis 总被引:1,自引:0,他引:1
Current progress in the area of photocatalysis is presented, particularly regarding technological applications. Highly efficient
TiO2 films on different substrates such as tile and glass have been developed for indoor environmental clean-up. TiO2 films coated on SiO2-precoated soda lime glass showed about 80% transparency and high photocatalytic activity towards the decomposition of thin
oil films. A novel phenomenon, superhydrophilicity, has been observed on these transparent TiO2 coatings. In addition, we have made use of a microelectrode system to monitor oxidation and reduction products separately.
The mechanistic and kinetic aspects of TiO2 photocatalysis are discussed. 相似文献
63.
Jacob JA Mahal HS Biswas N Mukherjee T Kapoor S 《Langmuir : the ACS journal of surfaces and colloids》2008,24(2):528-533
We demonstrate that dihydroxy benzenes are excellent reducing agents and may be used to reduce silver ions to synthesize stable silver nanoparticles in air-saturated aqueous solutions. The formation of Ag nanoparticles in deaerated aqueous solution at high pH values suggests that the reduction of silver ions occurs due to oxidation of dihydroxy benzenes and probably on the surface of Ag2O. Pulse radiolysis studies show that the semi-quinone radical does not participate in the reduction of silver ions at short time scales. Nevertheless, results show that primary intermediates undergo slower transformation in the presence of dihydroxy benzenes than in their absence. This slow transformation eventually leads to the formation of silver nanoparticles. The Ag nanoparticles were characterized by UV-vis absorption spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). XRD and TEM techniques showed the presence of Ag nanoparticles with an average size of 30 nm. 相似文献
64.
A statistical approach, response surface methodology (RSM), was used to study the production of extracellular protease fromBacillus sp., which has properties of immense industrial importance. The most influential parameters for protease production obtained
through the method of testing the parameters one at a time were starch, soybean meal, CaCl2, agitation rate, and inoculum density. This method resulted in the production of 2543 U/mL of protease in 48 h fromBacillus sp. Based on these results, face-centered central composite design falling under RSM was employed to further enhance protease
activity. The interactive effect of the most influential parameters resulted in a 1.50-fold increase in protease production,
yielding 3746 U/mL in 48 h. Analysis of variance showed the adequacy of the model and verification experiments confirmed its
validity. On subsequent scale-up in a 30-L bioreactor using conditions optimized through RSM, 3978 U/mL of protease was produced
in 18 h. This clearly indicated that the model remained valid even on a large scale. RSM is a quick process for optimization
of a large number of variables and provides profound insight into the interactive effect of various parameters involved in
protease production. 相似文献
65.
Pal G Dutta A Mitra K Grace MS Amat A Romanczyk TB Wu X Chakrabarti K Anders J Gorman E Waynant RW Tata DB 《Journal of photochemistry and photobiology. B, Biology》2007,86(3):252-261
Over the past forty years, many efforts have been devoted to study low power laser light interactions with biological systems. Some of the investigations were performed in-vitro, on bulk cell populations. Our present work was undertaken to apply specially engineered fiber-optic based nano-probes for the precise delivery of laser light on to a single cell and to observe production of low power laser light induced reactive oxygen species (ROS). A normal human skin fibroblast (NHF) cell line was utilized in this investigation and the cells were irradiated under two different schemes of exposure: (1) an entire NHF cell population within a Petri dish using a fan beam methodology, and (2) through the precise delivery of laser energy on to a single NHF cell using fiber-optic nano-probe. Photobiostimulative studies were conducted through variation of laser intensity, exposure time, and the energy dose of exposure. Laser irradiation induced enhancement in the rate of cell proliferation was observed to be dependent on laser exposure parameters and the method of laser delivery. The total energy dose (fluence) had a greater influence on the enhancement in the rate of cellular proliferation than compared to laser intensity. The enhancement in the growth rate was observed to have a finite life-time of several days after the initial laser exposure. Fluorescent life-time imaging of ROS was performed during the nano-based single cell exposure method. The kinetics of ROS generation was found to depend strongly on the laser fluence and not on the laser intensity. 相似文献
66.
Adeleke A. Oyekanmi N. I. Saharudin Che Mohamad Hazwan Abdul Khalil H. P. S. Niyi G. Olaiya Che K. Abdullah Tata Alfatah Deepu A. Gopakumar Daniel Pasquini 《Molecules (Basel, Switzerland)》2021,26(8)
Hydrophilic behaviour of carrageenan macroalgae biopolymer, due to hydroxyl groups, has limited its applications, especially for packaging. In this study, macroalgae were reinforced with cellulose nanofibrils (CNFs) isolated from kenaf bast fibres. The macroalgae CNF film was after that treated with silane for hydrophobicity enhancement. The wettability and functional properties of unmodified macroalgae CNF films were compared with silane-modified macroalgae CNF films. Characterisation of the unmodified and modified biopolymers films was investigated. The atomic force microscope (AFM), SEM morphology, tensile properties, water contact angle, and thermal behaviour of the biofilms showed that the incorporation of Kenaf bast CNF remarkably increased the strength, moisture resistance, and thermal stability of the macroalgae biopolymer films. Moreover, the films’ modification using a silane coupling agent further enhanced the strength and thermal stability of the films apart from improved water-resistance of the biopolymer films compared to unmodified films. The morphology and AFM showed good interfacial interaction of the components of the biopolymer films. The modified biopolymer films exhibited significantly improved hydrophobic properties compared to the unmodified films due to the enhanced dispersion resulting from the silane treatment. The improved biopolymer films can potentially be utilised as packaging materials. 相似文献
67.
Díaz RI Regourd J Santacroce PV Davis JT Jakeman DL Thompson A 《Chemical communications (Cambridge, England)》2007,(26):2701-2703
A new class of prodigiosenes with stability-enhancing functionalities appended to the C-ring were found to transport chloride anions through liposomal membranes, as well as to induce copper-mediated DNA cleavage. 相似文献
68.
Giovana A. Bataglion Gustavo Henrique Martins Ferreira Souza Gabriel Heerdt Nelson H. Morgon José Diogo Lisboa Dutra Ricardo Oliveira Freire Marcos N. Eberlin Alessandra Tata 《Journal of mass spectrometry : JMS》2015,50(2):336-343
Traveling wave ion mobility mass spectrometry (TWIM‐MS) is shown to be able to separate and characterize several isomeric forms of diterpene glycosides stevioside (Stv) and rebaudioside A (RebA) that are cationized by Na+ and K+ at different sites. Determination and characterization of these coexisting isomeric species, herein termed catiomers, arising from cationization at different and highly competitive coordinating sites, is particularly challenging for glycosides. To achieve this goal, the advantage of using CO2 as a more massive and polarizable drift gas, over N2, was demonstrated. Post‐TWIM‐MS/MS experiments were used to confirm the separation. Optimization of the possible geometries and cross‐sectional calculations for mobility peak assignments were also performed. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
69.
Ryu G Huang J Hofmann O Walshe CA Sze JY McClean GD Mosley A Rattle SJ deMello JC deMello AJ Bradley DD 《Lab on a chip》2011,11(9):1664-1670
We demonstrate a compact, low cost and practical fluorescence detection system for lab-on-a-chip applications. The system comprises a commercially available InGaN light emitting diode (501 nm) as light source, an organic or silicon photodiode detector, absorptive dye coated colour filters and linear and reflective polarisers. An injection moulded polystyrene microfluidic chip is used as the platform for fluorescence immunoassays for cardiac markers myoglobin and CK-MB. The optical limit of detection (LOD) is measured using a TransFluoSphere? suspension at 5.6 × 10(4) beads μl(-1) which can be equated to ~3 nM fluorescein equivalent concentration. The LOD for the human plasma immunoassays is measured as 1.5 ng ml(-1) for both myoglobin and CK-MB. 相似文献
70.
Jennifer Tata Dominique Scalarone Massimo Lazzari Oscar Chiantore 《European Polymer Journal》2009,45(9):2520-2528
One of the main limits in the use of block copolymers for nanotechnological applications lies in the poor control over the alignment of the nanoscopic domains. The self-assembling behavior of polystyrene-block-poly(ethylene oxide) (PS-b-PEO) has been modified by stoichiometric complexation of the ethylene oxide units with resorcinol and a simple procedure to prepare nanostructured films with normally oriented cylinders is reported. By direct spin coating of a series of complexated PS-b-PEO samples with different molecular weight and composition, films with the same morphology and orientation (i.e., normally oriented packed cylinders) have been obtained, also when different nanostructures and alignments were expected on the basis of the volume fraction composition and self-assembling behavior of pure copolymers. Tuning of the cylinder diameters in the range from 20 to 50 nm was possible by varying the length of the PEO block. The effects of resorcinol complexation have been studied by differential scanning calorimetry and X-ray diffraction and the morphologies of PS-b-PEO and PS-b-PEO/resorcinol films have been monitored by atomic force microscopy and electron microscopies. DSC and XRD analyses demonstrate that resorcinol significantly influences the crystallization behavior of the PEO block. The varied interfacial and surface energies of the PEO domains and the overall reduction of the crystalline phase in PS-b-PEO/resorcinol films appear to be strictly related to the morphological changes occurring by complexation. 相似文献