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51.
Paradossi G Cavalieri F Chiessi E Spagnoli C Cowman MK 《Journal of materials science. Materials in medicine》2003,14(8):687-691
In this paper, we present some new case examples where the chemical versatility of poly (vinyl alcohol) (PVA) can be used for potential biomedical applications. PVA, the polymeric material used for designing new nanostructured devices, is water soluble, biocompatible and has excellent physical properties. We point out the possibility of obtaining wall-to-wall chemical hydrogels as well as microgels without diminishing the biocompatibility available in the starting PVA material. Injectability is another important factor to take into account in controlled drug delivery for gene therapy. In this respect, in this paper, established and more innovative methods are prospected in order to obtain particles with dimensions suitable for these applications. 相似文献
52.
Choi MK Chi C Lee D Kang M Brock JR 《Journal of the Optical Society of America. A, Optics, image science, and vision》2003,20(2):312-316
We investigate the feasibility of numerically calculating morphology-dependent resonance (MDR) peaks. To do so, one has to calculate the scattering intensities numerically and determine how difficult it is to numerically predict the position and the magnitude of the MDR peaks. However, at present, in practice it is impossible to calculate MDR peaks with a personal computer because so much computing time is required. Therefore the surface values of the Debye potential and its derivative for a homogeneous sphere are obtained from Mie's analytical solution and then used in integral equations to give the scattering intensities at a specific position of infinity by numerical integrations. It is shown that if a sufficient number of surface elements are used, the MDR peaks are exactly calculated for a homogeneous sphere with refractive index of 1.5, 1.4, and 1.3 up to a size parameter of 20. One can conjecture the number of finite and boundary elements necessary to numerically compute accurate scattering intensities. It should be also noted that the number of surface elements necessary for exact integration shows peaks similar to MDR peaks with respect to the size parameter. Therefore one will need many more elements at the size parameter at which the MDR occurs. 相似文献
53.
Organic photovoltaic cells, similar to Gr?tzel type, have been widely investigated in recent years. In the case of Gr?tzel-type cells, TiO2 colloids are usually spin-coated onto an electrode and then sintered. Later, such electrodes are immersed in dye solution to sensitize the TiO2 layer for fabrication of photovoltaic cells. In the current study, an attempt was made to fabricate photovoltaic cells using a layer-by-layer technique. Based on such a method, ordered substituted phthalocyanine or conducting polythiophene-sensitized TiO2 multilayers were fabricated at the molecular level. Buildup of multilayer films of copper phthalocyanine-capped TiO2 and poly(thiophene-3-acetic acid)/TiO2 was monitored by increments in the UV-visible absorption and the frequency decrease of quartz crystal microbalance. The ordered multilayers were further characterized by infrared spectroscopy, and electrochemical and photoelectrochemical measurements. 相似文献
54.
In situ polychlorophenol bioremediation potential of the indigenous bacterial community of boreal groundwater 总被引:3,自引:0,他引:3
The composition and chlorophenol-degrading potential of groundwater bacterial community in a permanently cold, oxygen-deficient chlorophenol contaminated aquifer at K?rk?l?, Finland was studied with the aim of evaluating in situ bioremediation potential. The groundwater contained from 10(4) to 10(7) microscopically counted cells/ml and up to 10(5) CFU/ml heterotrophic bacteria cultivable at 8 and 20 degrees C. Of the 102 pure cultures, of which 86% Gram-negative, from the plume area (10,000 microg of chlorophenols/l), 57% degraded 2, 3, 4, 6-tetrachlorophenol (TeCP), the main component of the wood preservative which was the source of contamination: 17% also degraded pentachlorophenol (PCP). The degraders were scattered among 16 different clusters of Gram-negatives mainly proteobacteria and members of Cytophaga/Flexibacter/Bacteroides phylum judged by the composition of whole-cell fatty acids. Only one Gram-positive degrading cluster was found containing seven actinobacteria closest to Nocardioides. Of the 88 pure cultures isolated from outside the plume (< 10 microg of chlorophenols/l) 67% were Gram-negative. Seven percent of the isolates degraded 2, 3. 4, 6-TeCP and/or PCP. Five of the Gram-positive isolates from outside the plume were Mycobacterium/Rhodococcus-related actinobacteria and O-methylated 2, 3, 4, 6-TeCP and PCP. The results show that chlorophenol degrading bacterial flora had been enriched as a result of contamination of the aquifer. This suggests significant in situ bioremediation potential of the site. 相似文献
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56.
Baller MK Lang HP Fritz J Gerber C Gimzewsk JK Drechsler U Rothuizen H Despont M Vettiger P Battiston FM Ramseyer JP Fornaro P Meyer E Guntherodt HJ 《Ultramicroscopy》2000,82(1-4):1-9
We present quantitative and qualitative detection of analyte vapors using a microfabricated silicon cantilever array. To observe transduction of physical and chemical processes into nanomechanical motion of the cantilever, swelling of a polymer layer on the cantilever is monitored during exposure to the analyte. This motion is tracked by a beam-deflection technique using a time multiplexing scheme. The response pattern of eight cantilevers is analyzed via principal component analysis (PCA) and artificial neural network (ANN) techniques, which facilitates the application of the device as an artificial chemical nose. Analytes tested comprise chemical solvents, a homologous series of primary alcohols, and natural flavors. First differential measurements of surface stress change due to protein adsorption on a cantilever array are shown using a liquid cell. 相似文献
57.
Cho HW Kim SB Jeong MK Park Y Ziegler TR Jones DP 《Expert systems with applications》2008,35(3):967-975
High-resolution nuclear magnetic resonance (NMR) spectroscopy has provided a new means for detection and recognition of metabolic changes in biological systems in response to pathophysiological stimuli and to the intake of toxins or nutrition. To identify meaningful patterns from NMR spectra, various statistical pattern recognition methods have been applied to reduce their complexity and uncover implicit metabolic patterns. In this paper, we present a genetic algorithm (GA)-based feature selection method to determine major metabolite features to play a significant role in discrimination of samples among different conditions in high-resolution NMR spectra. In addition, an orthogonal signal filter was employed as a preprocessor of NMR spectra in order to remove any unwanted variation of the data that is unrelated to the discrimination of different conditions. The results of k-nearest neighbors and the partial least squares discriminant analysis of the experimental NMR spectra from human plasma showed the potential advantage of the features obtained from GA-based feature selection combined with an orthogonal signal filter. 相似文献
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The objectives of this research were to characterize the mechanical and barrier properties of sweetpotato starch (SPS)-based film (SPSF) and to investigate the antimicrobial activity of SPSF containing origanum oil (OG) against foodborne pathogenic bacteria. The SPSF was fabricated with the SPS extracted from commercial sweetpotato roots. Tensile strength (TS), percent elongation at break (E), and water vapor permeability (WVP) were determined to characterize the SPSF fabricated with selected SPS concentrations, plasticizers, and the concentrations of plasticizers. The agar diffusion assay was used to determine the antimicrobial activity of SPSF containing selective concentrations of OG against Salmonella Enteritidis, Escherichia coli O157:H7, and Listeria monocytogenes. The SPSF fabricated with 2.5% SPS exhibited the greatest TS (4.58 MPa). The TS, E, and WVP of SPSF plasticized with 40% sorbitol exhibited 7.96 MPa, 77.92%, 0.212 ng m/m(2) S Pa, respectively. Therefore, the SPSF fabricated with 2.5% SPS and 40% sorbitol was determined as the optimum film. The antimicrobial activity of the SPSF containing OG increased as the concentration of OG increased. And the SPSF containing OG exhibited greater inhibitory effects against the gram-negative bacteria such as S. Enteritidis and E. coli O157:H7 than the gram-positive L. monocytogenes. The greatest antimicrobial activity was observed against S. Enteritidis when the SPSF containing 2% OG was applied, and the maximum square of zone width was 18.43 mm(2). 相似文献