916 research outputs found
Constant time imaging approaches to NMR microscopy
No full textThe resolution in nuclear magnetic resonance (NMR) microscopy is limited by a combination of the inherent low sensitivity of NMR, the destruction of spin magnetization gratings by molecular diffusion, and variations in the local magnetic field strength introduced by spatial variations of the bulk susceptibility. While none of these may be completely overcome, constant time imaging methods are the optimal approach to recording images when the above factors are important. This method aims to instantaneously create a spin magnetization grating and then to efficiently sample the spatially invariant portion of this - corresponding to a selected Fourier component of the sample distribution. The method is introduced, analyzed in the presence of molecular diffusion, and demonstrated to yield high-resolution images. To implement the method, a microscopy probe was constructed for a standard-bore 400-MHz NMR spectrometer (the latter was also implemented at 600 MHz), which is described. (C) 1997 John Wiley & Sons, Inc
Isolation and Characterization of a Biosurfactant Producing Strain Planococcus sp. XW-1 from the Cold Marine Environment
No full textOne cold-adapted strain, named Planococcus sp. XW-1, was isolated from the Yellow Sea. The strain can produce biosurfactant with petroleum as sole source of carbon at low temperature (4 °C). The biosurfactant was identified as glycolipid-type biosurfactant species by thin-layer chromatography (TLC) and Fourier transform infrared spectroscopy (FTIR). It reduced the surface tension of water to 26.8 mN/m with a critical micelle concentration measurement of 60 mg/L. The produced biosurfactant possesses high surface activity at wide ranges of temperature (−18–105 °C), pH values (2–12), and salt concentrations (1–18%). The biosurfactant exhibited higher surface activity and higher growth rate of cells with hexadecane and diesel as carbon source. The strain Planococcus sp. XW-1 was also effective in degrading crude oil, after 21 days of growth at 4 °C in medium with 1% crude oil and 1% (v/v) bacteria broth, 54% of crude oil was degraded. The results suggest that Planococcus sp. XW-1 is a promising candidate for use in the bioremediation of petroleum-contaminated seawater in the Yellow Sea during winter. This study reported for the first time that Planococcus isolated from the Yellow Sea can produce biosurfactant using petroleum as the sole carbon source at low temperature (4 °C), showing its ecological role in the remediation of marine petroleum pollution
Acidic residues on the N-terminus of proinsulin C-peptide are important for the folding of insulin precursor
No full textTo investigate the role of C-peptide in the folding of insulin precursor, a series of C-peptide mutant proinsulin genes were constructed, overexpressed in Escherichia coli and the proteins purified. Correct disulfide linkages of these proteins were confirmed by both tryptic peptide mapping and insulin receptor binding analyses. In vitro refolding experiments were performed with the purified proteins and showed that mutations on the glycine-rich middle segment of C-peptide, GGGPGAG, and deletion of the C-terminal pentapeptide, EGSLQ, as well as mutations on the two pairs of dibasic residues at the two ends of C-peptide did not significantly affect the refolding yields. However, both alanine replacement mutation and deletion of three highly conserved acidic residues (EAED) at the N-terminus of the C-peptide resulted in serious aggregation during refolding. The results indicate that the highly conserved acidic N-terminal part of C-peptide is very important for insulin precursor folding, and that C-peptide may have some intramolecular chaperone-like function in the folding of insulin precursor.Biochemistry & Molecular BiologySCI(E)PubMed22ARTICLE6855-85913
The D1-triangulation in simplicial variable dimension algorithms for computing solutions of nonlinear equations
No full textDevelopment of phyllanthin containing microcapsules and their improved biological activity towards skin cells and Staphylococcus aureus
No full textChitosan based microcapsule which encapsulated with phyllanthin was developed by simple coacervation. The composition and surface morphology of phyllanthin containing microcapsules were analyzed by Fourier Transform Infrared spectroscopy and Scanning Electron Microscopy, respectively. The release of phyllanthin from the microcapsules was found to be more than 60% after 120 h. In vitro biological assays demonstrated that these phyllanthin containing microcapsules showed a stronger anti-oxidation potential on both human fibroblasts and keratinocytes as well as a better growth inhibitory activity towards Staphylococcus aureus
Geogrid wrapped around and vegetated reinforced wall applications in the village of Olympic Games in Universiade 2005 Izmir Turkey
No full text4th Asian Regional Conference on Geosynthetics -- JUN 17-20, 2008 -- Shanghai, PEOPLES R CHINA23(rd) University Olympic Games had been hold in Izmir in August 2005. This organization which is accepted as an important opportunity in most of the countries is achieved after great efforts of Izmir Municipality. As a part of this organization, a village for the athletes is constructed in a valley of Uzundere, Izmir. The apartment buildings, which are sold to individual buyers after the completion of the games, are spread out in a very wide area. In the slopes of the valley, green walls with geogrid reinforcements are used as a solution to form stable sides, prevent slope flows during precipitations, and other kinds of slides. Also, an aesthetical presentation of the village was a target to be attained. In order to achieve the goals of the project, geological, geophysical and geotechnical investigations are carried out. The heights of the geogrid reinforced retaining walls in the area are between 5.0 and 10.0 meters and they are constructed using uniaxial and biaxial geogrids with reinforced earth technique by a wrapping system and the geogrids are vegetated to get the green walls or in other words living walls. In this study the mentioned geogrid walls are explained both in the scope of construction and the costs. These applications are also accepted as interesting and cost effective by the Izmir municipality administrators.Int Geosynthet Soc, Chinese Chapter, Chinese Tech Assoc Geosynthet, Int Geosynthet Soc, Chinese Hydraul Engn Soc, Shanghai Invest Design & Res Inst, Zhejiang Univ, Shanghai Hejie Tech & Trading Co Lt
Circular photogalvanic effect of the two-dimensional electron gas in AlXGa1-XN/GaN heterostructures under uniaxial strain
No full textThe circular photogalvanic effect (CPGE) of the two-dimensional electron gas (2DEG) in Al0.25Ga0.75N/GaN heterostructures induced by infrared radiation has been investigated under uniaxial strain. The observed photocurrent consists of the superposition of the CPGE and the linear photogalvanic effect currents, both of which are up to 10(-2) nA. The amplitude of the CPGE current increases linearly with additional strain and is enhanced by 18.6% with a strain of 2.2x10(-3). Based on the experimental results, the contribution of bulk-inversion asymmetry (BIA) and structure-inversion asymmetry (SIA) spin splitting of the 2DEG to the CPGE current in the heterostructures is separated, and the ratio of SIA and BIA terms is estimated to be about 13.2, indicating that the SIA is the dominant mechanism to induce the k-linear spin splitting of the subbands in the triangular quantum well at AlxGa1-xN/GaN heterointerfaces. (C) 2007 American Institute of Physics
High level synthesis for loop-based BIST
No full textArea and test time are two major overheads encountered during data path high level synthesis for BIST. This paper presents an approach to behavioral synthesis for loop-based BIST. By taking into account the requirements of the BIST scheme during behavioral synthesis processes, an area optimal BIST solution can be obtained. This approach is based on the use of test resources reusability that results in a fewer number of registers being modified to be test registers. This is achieved by incorporating self-testability constraints during register assignment operations. Experimental results on benchmarks are presented to demonstrate the effectiveness of the approach.link_to_subscribed_fulltex
Development of a 1-km landcover dataset of China using AVHRR data
No full textThis paper describes the development of a 1-km landcover dataset of China by using monthly NDVI data spanning April 1992 through,March 1993. The method used combined unsupervised and supervised classification of NDVI data from AVHRR. It is composed of five steps: (a) unsupervised clustering of monthly AVHRR NDVI maximum value composites is performed using the ISOCLASS algorithm; (b) preliminary identification is carried our with the addition of digital elevation models, eco-region data and a collection of other landcover/vegetation reference data to identify the clusters with single landcover classes; (c) re-clustering is performed of clusters with size greater than a given threshold value and containing two or more disparate landcover classes: (d) cluster combining is performed to combine all clusters with a single landcover class in one cluster, and all other clusters into one mixed cluster; and (e) supervised classification is used to carry out post-classification of the mixed cluster generated in the previous step by using the maximum likelihood algorithm and the identified single landcover classes of the previous step as training data. The classification is based on extensive use of computer-assisted image processing and tools, as well as the skills of the human interpreter to take the final decisions regarding the relationship between spectral classes defined using unsupervised methods and landscape characteristics that are used to define landcover classes, (C) 1999 Elsevier Science B.V. All rights reserved.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000085252600002&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Geography, PhysicalGeosciences, MultidisciplinaryRemote SensingImaging Science & Photographic TechnologySCI(E)EI6ARTICLE5-6305-3165
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