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Probe Technology (probe + technology)

Distribution by Scientific Domains
Medical Sciences50%

Selected Abstracts

Ribosomal RNA-targeted nucleic acid probes for studies in microbial ecology

FEMS MICROBIOLOGY REVIEWS, Issue 5 2000
Rudolf Amann
Abstract With readily applicable hybridization assays, mainly based on rRNA-targeted nucleic acid probes, and direct, cultivation-independent sequence retrieval, microbiologists can for the first time determine the true composition of microbial communities. Phylogenetic identification and exact spatiotemporal quantification of microorganisms will in the future become prerequisites for high quality studies in microbial ecology just as good taxonomy and solid quantification have always been for macroecology. This review is intended to give a short history of the development of rRNA-targeted nucleic acid probes and probe technologies, as well as of their application in microbial ecology. The current state of the art is described, and we will try to look into the future. Over the last decade, rRNA-targeted probes have become a handy tool for microbial ecologists. In order to speed up the transformation of microbial ecology from a mostly descriptive to a hypothesis-driven, experimental science more intense use must be made of the taxonomic precision and quantitativeness of rRNA-targeted probes. [source]

Using pulsed gradient spin echo NMR for chemical mixture analysis: How to obtain optimum results

CONCEPTS IN MAGNETIC RESONANCE, Issue 4 2002
Brian Antalek
Abstract Pulsed gradient spin echo NMR is a powerful technique for measuring diffusion coefficients. When coupled with appropriate data processing schemes, the technique becomes an exceptionally valuable tool for mixture analysis, the separation of which is based on the molecular size. Extremely fine differentiation may be possible in the diffusion dimension but only with high-quality data. For fully resolved resonances, components with diffusion coefficients that differ by less than 2% may be distinguished in mixtures. For highly overlapped resonances, the resolved spectra of pure components with diffusion coefficients that differ by less than 30% may be obtained. In order to achieve the best possible data quality one must be aware of the primary sources of artifacts and incorporate the necessary means to alleviate them. The origin of these artifacts are described, along with the methods necessary to observe them. Practical solutions are presented. Examples are shown that demonstrate the effects of the artifacts on the acquired data set. Many mixture analysis problems may be addressed with conventional high resolution pulsed field gradient probe technology delivering less than 0.5 T m,1 (50 G cm,1). © 2002 Wiley Periodicals, Inc. Concepts Magn Reson 14: 225,258, 2002. [source]

Video-rate scanning probe control challenges: setting the stage for a microscopy revolution

ASIAN JOURNAL OF CONTROL, Issue 2 2009
M. J. Rost
Abstract Scanning probe microscopy is at the verge of revolutionizing microscopy once again. Video-rate scanning tunneling microscope (STM) and video-rate atomic force microscope (AFM) technology will enable the direct observation of many dynamic processes that are impossible to observe today, such as atom or molecule diffusion, real time film growth, or catalytic reactions. In this paper we discuss the critical aspects that have to be taken into account when working on increasing the imaging speed of scanning probe microscopes. We highlight the state-of-the-art developments in the control of the piezoelectric scanning elements and describe the latest innovations regarding the design and construction of the whole mechanical loop including new scanner geometries. We identify critical aspects for which no obvious solution exists and aspects where advanced control engineering can help, like piezo non-linearities, the acceleration limit and the challenging technical requirements for the preamplifiers that are needed for measuring a tunneling current. Finally, we provide an overview of a number of new directions that are being pursued to solve the problems currently encountered in scanning probe technology. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source]

Real-time PCR quantification of haematopoietic chimerism after transplantation: a comparison between TaqMan and hybridization probes technologies

INTERNATIONAL JOURNAL OF LABORATORY HEMATOLOGY, Issue 1p1 2010
J. MARTINEZ-LOPEZ
Summary This study aimed to compare the sensitivity and accuracy of two methods of quantitative real-time polymerase chain reaction (qrt-PCR), in order to determine haematopoietic chimerism (CH): single nucleotide polymorphisms using TaqMan (TM) probes and insertion/deletion polymorphisms using Hybridization (Hyb) probes. A total of 106 samples from 20 patients who underwent allogenic stem cell transplantation (n = 14) or live-donor liver transplantation (n = 6) were studied. The mean level of chimerism was 8.37% for the TM method and 7.73% in the Hyb method, which was not significantly different (P = 0.69). The Pearson correlation coefficient between the two methods was r = 0.91 (P < 0.001). The estimation of the regression line, using the Passing and Balbock method was Intercept A ,0.0381 [95% confidence interval (CI) ,0.1265 to 0.0296) and Slope B: 1.04609(95% CI 0.9349,1.161). Bland,Altman data showed that the standard deviations, which differed between the two methods (%Hyb,%TM), were 0.98 and ,1.28. The accuracy and sensitivity of qrt-PCR chimerism is independent of the method used if the optimization is adequate and satisfies the criteria for adequate study. Real-time PCR, independent of the method adopted, is a very good tool for study levels of CH. [source]