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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 2490-2493 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Recent experimental results show a linear energy response in high quality Nb-Al-AlOx-Nb superconducting tunnel junction detectors for photon energies between 1.5 and 6.4 keV. The experimental data are based on both direct x-ray illumination and on the escape and re-absorption of fluorescent photons created in the junction electrodes and in the silicon substrate. The observed linearity of the energy response raises questions on the validity of some theoretical models which describe the relaxation process occurring in a superconducting thin film after x-ray photoabsorption. Such models generally predict nonlinear effects due to large quasiparticle number densities and short recombination times.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Plasmid p15B is a bacteriophage P1-related resident of Escherichia coli 15T−. Both genomes contain a segment in which DNA inversion occurs, although this part of their genomes is not identical. This DNA segment of p15B was cloned in a multicopy vector plasmid. Like its parent, the resulting plasmid, pAW800, undergoes complex multiple DNA inversions: this DNA inversion system is therefore called Min. The min gene, which codes for the p15B Min DNA invertase, can complement the P1 cin recombinase gene. The Min inversion system is thus a new member of the Din family of site-specific recombinases to which Cin belongs. The DNA sequence of the min gene revealed that Min is most closely related to the Pin recombinase of the e14 defective viral element on the E. coli K12 chromosome. Like other members of the Din family, the min gene contains a recombinational enhancer element which stimulates site-specific DNA inversion 300-fold.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physica B: Physics of Condensed Matter 194-196 (1994), S. 1663-1664 
    ISSN: 0921-4526
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1438-2385
    Keywords: Key words Cauliflower mosaic virus ; 35S promoter ; Genetically modified organisms ; Food analysis ; Polymerase chain reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Today DNA-based techniques are very common for the detection of genetically modified organisms (GMOs) in food products. For fast and easy detection of GMOs, polymerase chain reaction (PCR) screening methods, which amplify common transgenic elements, are applied in routine analysis. These techniques do not allow differentiation between GMOs and the natural occurrence of transgenic elements, such as the 35S-promoter of cauliflower mosaic virus (CaMV) or the NOS-terminator of Agrobacterium tumefaciens, and thus may result in false-positive detection of GMOs. In this study we evaluated three different existing 35S screening systems and report the development of two new CaMV-specific PCR systems. These PCR systems based on CaMV-specific genes allow the identification of positively screened 35S food samples as naturally virus-infected products or plants. Seven food samples tested positive in routine 35S screening analysis and negative in GMO specific systems were investigated using the new virus-specific PCR systems. In all seven samples CaMV was detected.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 348-349 (Sept. 2007), p. 857-860 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The paper presents numerical and experimental results of continued studies of curvedfatigue crack growth in arbitrarily pre-cracked isotropic sheets under biaxial proportional planeloading. The predictor-corrector method (PCM) was extended in order to analyse the growth ofmultiple crack systems. As a result, the program PCCS-2D was written to run within ANSYS withoutany user interaction. In order to check the accuracy and efficiency of the method biaxial crackgrowth simulations were carried out for a fracture mechanics cruciform specimen. The results arecompared with experimental findings obtained by specimens made of 6061 aluminium alloy inT651 condition using a 250kN biaxial servohydraulic testing machine. From the numerical and experimentalresults, we conclude, that the proposed predictor-corrector method can be used in curvedcrack growth simulation also under biaxial proportional loading conditions
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0517
    Keywords: Key words GMO detection ; PCR ; Food labelling ; Quality assurance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  The detection of genetically modified organisms (GMOs) by the polymerase chain reaction (PCR) is a complex multiparameter problem. Therefore, a number of critical issues in respect to quality control need to be considered. For practical purposes, the PCR process itself can be divided into three subprocesses: template isolation and reaction setup (pre-PCR), PCR reaction and detection of amplification products, and data evaluation (post-PCR). Crucial factors for the pre-PCR process are the following: homogeneity of the sample to be analysed, performance of template isolation and purification in terms of yield and purity, standardized process for the estimation of concentrations of genomic DNA and all reagents used in the reaction. For the PCR itself, crucial factors to be controlled are: setup of reactions, batch to batch variations of reagents, temperature-time programs used for the PCR amplification, and the performance of different types of hardware (e.g. different brands of thermocyclers). The crucial factor for the post-PCR process is the detection of the amplification products of the PCR. The tremendous sensitivity of PCR methods requires a careful and consequent separation of the three processes in terms of hardware, laboratory space and sample handling. The avoidance of contamination is one of the most critical factors. The goal of quality assurance measures must be to ensure appropriate results at maximum sensitivity. The complexity of any PCR system used for the detection of GMOs leads to the requirement of a careful validation process for any laboratory using such methods. For qualitative analyses crucial validation parameters are: specificity, selectivity, repeatability, intermediate precision, reproducibility, limit of detection and robustness.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Zeitschrift für Lebensmittel-Untersuchung und -Forschung 206 (1998), S. 399-403 
    ISSN: 1431-4630
    Keywords: Key words Coeliac disease ; ELISA ; PCR ; Wheat prolamins ; Oats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  It is well established that the consumption of wheat prolamins causes the characteristic symptoms of coeliac disease (CD) in subjects who are predisposed to it. There is currently much discussion about the role of oats in the pathogenesis of CD. Evidently, it is important that oats used for clinical studies are not contaminated with wheat. In this study, 38 oat samples were investigated by polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA): 30 samples consisted of flakes or grains and 8 probes were industrially processed oat diets. Wheat prolamin (gliadin) detection by ELISA showed that 16 of these samples contained less than the detection limit of 0.2 mg gliadin/100 g dry weight; 21 samples contained less than 2.8 mg gliadin/100 g dry weight and 1 sample reached 38 mg gliadin/100 g dry weight, clearly exceeding the allowed Swiss limit of 10 mg gliadin/100 g dry weight for gluten-free products. Spiking experiments showed that the wheat PCR system is about ten times more sensitive than the ELISA system, provided that the isolated DNA is fully amplifiable. Thus, wheat DNA could be detected by the wheat PCR system in ten samples with gliadin contents below the detection limit of the ELISA system used. Applying a eukaryote-specific 18S-PCR system the presence of amplifiable DNA was verified. Only two of eight samples of industrially processed oat products contained amplifiable DNA, the other six samples had no detectable DNA left. One sample was wheat-PCR positive. However, all eight samples contained detectable amounts of gliadin in the ELISA.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Zeitschrift für Lebensmittel-Untersuchung und -Forschung 207 (1998), S. 261-263 
    ISSN: 1431-4630
    Keywords: Key words Mitochondrial DNA ; Polymerase chain reaction ; Species identification ; Evolutionary analysis ; Food authenticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Nucleic acid-based species identification often targets the mitochondrial encoded cytb gene. However, polymerase chain reaction (PCR)- restriction fragment length polymorphism (RFLP) analysis using universal primers sometimes leads to ambiguous results, which are due to the presence of nuclear encoded pseudo-cytb genes. Such ambiguities were succesfully avoided using a newly developed method for the enrichment of mitochondrial DNA. In addition, a mitochondrial cytb-specific PCR system was designed allowing the unambiguous identification of game meat.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Zeitschrift für Lebensmittel-Untersuchung und -Forschung 207 (1998), S. 207-213 
    ISSN: 1431-4630
    Keywords: Key words Quantitative competitive PCR ; Roundup Ready soybean ; Maximizer maize ; GMO ; Food analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  The surveillance of food labelling concerning genetically modified organisms (GMOs) requires DNA-based analytical techniques. Present assay systems allow the detection of GMO in food; however, they do not permit their quantitation. In this study, we report the development of quantitative competitive polymerase chain reaction (QC-PCR) systems for the detection and quantitation of the Roundup Ready soybean (RRS) and the Maximizer maize (MM) in food samples. Three DNA fragments that differ from the GMO-specific sequences by an insertion were constructed and used as internal standards in the PCR. These standards were calibrated by co-amplifying with mixtures containing RRS DNA and MM DNA, respectively. The calibrated QC-PCR systems were applied to nine commercial food samples containing RRS DNA and to three certified RRS flour mixtures in order to elucidate whether these food samples contain more or less than 1% RRS DNA. Finally, the GMO contents of four samples that were found to contain more than 1% RRS were determined by QC-PCR using various amounts of standard DNA.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 100 (2000), S. 271-279 
    ISSN: 1432-2242
    Keywords: Key words Spelt ; Wheat ; γ-Gliadins ; PCR ; Molecular markers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Polymerase chain reaction (PCR) primers GAG5 and GAG6 were designed based on published γ-gliadin gene sequences and applied to 35 cultivars of closely related spelt (Triticum spelta L.) and hexaploid wheat (T. aestivum L.). Eight tetraploid durum wheat (T. durum Desf.) cultivars were included in the analysis. The obtained PCR products originated from two γ-gliadin genes which were mapped to homeologous chromosomes 1B and 1D and termed GAG56B and GAG56D, respectively. Two alleles of GAG56D differing in a 9-bp deletion/duplication and single nucleotide polymorphism were found. The 18 spelts tested and wheat cultivar ’Chinese Spring’ were discovered to carry a previously unknown γ-gliadin gene, while 16 wheat cultivars possessed its longer, already published allele. Two PCR-based detection systems for the diagnostic alleles were developed and applied. The occurrence of two alleles of GAG56B among the investigated durum wheats correlated with their expression of gluten quality markers γ-gliadins 42 or 45.
    Type of Medium: Electronic Resource
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