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  • 1
    Electronic Resource
    Electronic Resource
    Feedback regulation of an Agrobacterium catalase gene katA involved in Agrobacterium–plant interaction (2001)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 42 (2001), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Catalases are known to detoxify H2O2, a major component of oxidative stress imposed on a cell. An Agrobacterium tumefaciens catalase encoded by a chromosomal gene katA has been implicated as an important virulence factor as it is involved in detoxification of H2O2 released during Agrobacterium–plant interaction. In this paper, we report a feedback regulation pathway that controls the expression of katA in A. tumefaciens cells. We observed that katA could be induced by plant tissue sections and by acidic pH on a minimal medium, which resembles the plant environment that the bacteria encounter during the course of infection. This represents a new regulatory factor for catalase induction in bacteria. More importantly, a feedback regulation was observed when the katA–gfp expression was studied in different genetic backgrounds. We found that introduction of a wild-type katA gene encoding a functional catalase into A. tumefaciens cells could repress the katA–gfp expression over 60-fold. The katA gene could be induced by H2O2 and the encoded catalase could detoxify H2O2. In addition, the katA-gfp expression of one bacterial cell could be repressed by other surrounding catalase-proficient bacterial cells. Furthermore, mutation at katA caused a 10-fold increase of the intracellular H2O2 concentration in the bacteria grown on an acidic pH medium. These results suggest that the endogenous H2O2 generated during A. tumefaciens cell growth could serve as the intracellular and intercellular inducer for the katA gene expression and that the acidic pH could pose an oxidative stress on the bacteria. Surprisingly, one mutated KatA protein, exhibiting no significant catalase activity as a result of the alteration of two important residues at the putative active site, could partially repress the katA–gfp expression. The feedback regulation of the katA gene by both catalase activity and KatA protein could presumably maintain an appropriated level of catalase activity and H2O2 inside A. tumefaciens cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2001.02653.x
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  • 2
    Electronic Resource
    Electronic Resource
    Electrochemical behaviour of chromium, molybdenum and manganese in liquid ammonia
    Amsterdam : Elsevier
    Electrochimica Acta 39 (1994), S. 2795-2797 
    Details
    ISSN: 0013-4686
    Keywords: chromium ; corrosion ; electrochemical kinetics ; liquid ammonia ; manganese ; molybdenum.
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0013-4686(94)00225-8
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  • 3
    Electronic Resource
    Electronic Resource
    Comparison of metallic electrodes for constant-potential amperometric detection of carbohydrates, amino acids and related compounds in flow systems
    Amsterdam : Elsevier
    Analytica Chimica Acta 244 (1991), S. 169-178 
    Details
    ISSN: 0003-2670
    Keywords: Amino acids ; Amperometry ; Carbohydrates ; Cyclic voltammetry ; Flow system ; Liquid chromatography
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0003-2670(00)82494-0
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  • 4
    Electronic Resource
    Electronic Resource
    Production and cytogenetics of intergeneric hybrids between Brassica napus and Orychophragmus violaceus (1995)
    Springer
    Theoretical and applied genetics 91 (1995), S. 131-136 
    Details
    ISSN: 1432-2242
    Keywords: Brassica napus, Orychophragmus violaceus ; Intergeneric hybrid ; Somatic separation of genome ; Mixoploid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The intergeneric hybrid between Brassica napus and Orychophragmus violaceus was obtained by means of embryo culture technique with the latter as the pollen parent. The hybrid was morphologically intermediate between its parents, but could produce a lot of seeds when selfed. Somatic separation of the genomes from the two parental species was observed during the mitotic divisions of some of the hybrid cells. Thus, the hybrid became the mixoploid in nature, consisting of haploid and diploid cells of B. napus, and a nuclear — cytoplasmic hybrid, with the cytoplasm of B. napus and the nuclei of O. violaceus, and the hybrid cells. Pollen mother cells with 19, 12 and 6 bivalents, respectively, were produced by the hybrid. From the selfed progeny of the hybrid, mainly two kinds of plants, B. napus and the hybrid, were found. The hybrid plants of the selfed progeny again produced two kinds of plants, B. napus and the hybrid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220869
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  • 5
    Electronic Resource
    Electronic Resource
    Giemsa N-banding pattern in cabbage and Chinese kale (1989)
    Springer
    Euphytica 41 (1989), S. 17-21 
    Details
    ISSN: 1573-5060
    Keywords: Brassica oleracea capitata ; cabbage ; Brassica oleracea alboglabra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In cabbage (Brassica oleracea var. capitata) and Chinese kale (B. oleracea alboglabra) four types of N-bands can be distinguished: pericentromeric, telomeric (terminal), intercalary and satellite bands. Typical NOR bands were not observed. The pericentromeric bands appear at the pericentric regions, possibly even at the centromeres of all chromosomes. Telomeric bands are observed on the short arms of chromosomes 1,5 and 6 in cabbage and chromosomes 1 and 5 in Chinese kale. Intercalary bands stained weakly in the long arms of chromosome 3 in cabbage and chromosome 2 in Chinese kale. Satellite bands cover the entire satellites in both Brassica species. The N-banding pattern is very similar in appearance to the C-banding pattern in both species and much more convenient to apply.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00022406
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  • 6
    Electronic Resource
    Electronic Resource
    Thermochemical synthesis and characterization of nanostructured chromium suicide and silicon carbide composite materials (1995)
    Springer
    Journal of materials science 30 (1995), S. 3475-3482 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Nanostructured chromium suicide/silicon carbide in the form of composite powders have been synthesized from water-soluble precursors by a spray-dry and thermal conversion process. Two materials compositions were investigated to provide insight into the relation between the initial precursor composition and the composition of the synthesized nanostructured materials. The multiphase materials that were produced contain (i) cubic β-SiC and hexagonal Cr5−x Si3−y C x+y (Cr5Si3C x ). A systematic study of the chemical and structured nature of these materials during and after processing was carried out using thermogravimetric analysis, differential thermal analysis, inductively coupled plasma spectrometry, Fourier transform-infrared spectroscopy, and X-ray diffractometry analysis. The calculated average grain size is around 20–80 nm. Microstructure observation using scanning electron microscopy and transmission electronmicroscopy revealed a distribution of nanoparticles with dimensions in the range 10–100 nm. This is in agreement with the precalculation from an analysis of X-ray line broadening.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349898
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  • 7
    Electronic Resource
    Electronic Resource
    A new forage genetic resource Orychophragmus violaceus (L.) O.E. Schulz (1998)
    Springer
    Genetic resources and crop evolution 45 (1998), S. 491-494 
    Details
    ISSN: 1573-5109
    Keywords: forage ; genetic resource ; O. violaceus ; protein content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract O. violaceus is a species of Brassicaceae, which is mainly found in China. Its shoots are rich in protein, iron, calcium and vitamins A and C. Hence it is a valuable forage. Its shoot yield is high, about 36,400 kg/ha, when cultivated in Chengdu. This plant species is adaptable to grassland, barren hills, roadsides, gardens, etc. Its protein content is higher than most other forage plants. Therefore, O. violaceus is a new forage genetic resource.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008668225306
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  • 8
    Electronic Resource
    Electronic Resource
    Accurate measurement of three-dimensional deformations in deformable and rigid bodies using computer vision (1993)
    Springer
    Experimental mechanics 33 (1993), S. 123-132 
    Details
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Recently, digital-image-correlation techniques have been used to accurately determine two-dimensional in-plane displacements and strains. An extension of the two-dimensional method to the acquisition of accurate, three-dimensional surfacedisplacement data from a stereo pair of CCD cameras is presented in this paper. A pin-hole camera model is used to express the transformation relating three-dimensional world coordinates to two-dimensional computer-image coordinates by the use of camera extrinsic and intrinsic parameters. Accurate camera model parameters are obtained for each camera independently by (a) using several points which have three-dimensional world coordinates that are accurate within 0.001 mm and (b) using two-dimensional image-correlation methods that are accurate to within 0.05 pixels to obtain the computer-image coordinates of various object positions. A nonlinear, least-squares method is used to select the optimal camera parameters such that the deviations between the measured and estimated image positions are minimized. Using multiple orientations of the cameras, the accuracy of the methodology is tested by performing translation tests. Using theoretical error estimates, error analyses are presented. To verify the methodology for actual tests both the displacement field for a cantilever beam and also the surface, three-dimensional displacement and strain fields for a 304L stainless-steel compact-tension specimen were experimentally obtained using stereo vision. Results indicate that the three-dimensional measurement methodology, when combined with two-dimensional digital correlation for subpixel accuracy, is a viable tool for the accurate measurement of surface displacements and strains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02322488
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  • 9
    Electronic Resource
    Electronic Resource
    Measurement of curved-surface deformation in cylindrical coordinates (2000)
    Springer
    Experimental mechanics 40 (2000), S. 345-350 
    Details
    ISSN: 1741-2765
    Keywords: Strain fields ; cylindrical coordinate ; computer vision/digital image processing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Stereo vision is used to measure the strain field of a round tension test specimen in a cylindrical coordinate system. Initially, the displacement fields of the specimen are measured relative to a world coordinate system erected by the stereo vision. Through coordinate transformations, the measured displacement fields expressed in world coordinates are then converted to the displacement fields expressed in cylindrical coordinates. By differentiating the axial and circumferential displacements in the axial and circumferential directions, the axial, circumferential and shear strains are determined. Results indicate that the measured mean value of the axial strains is in good agreement with the measurements of the extensometer and the strain gage. The Poisson's ratio obtained by the circumferential and axial strains is close to .33 in the elastic state. The mean error of the computed shear strain is approximately .03 percent in the smaller elastic deformation and .08 percent in the larger plastic deformation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02326479
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  • 10
    Electronic Resource
    Electronic Resource
    An experimental study of the deformation fields around a propagating crack tip (1998)
    Springer
    Experimental mechanics 38 (1998), S. 79-85 
    Details
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Digital image processing was used to obtain the deformation fields around a propagating crack tip from photographic films recorded by a high-speed Cranz-Schardin camera. The in-plane displacements and strains determined from the process were then used to compute the dynamic stress intensity factor and the remote stress component parallel to the crack face.K dominance is discussed using the experimental data. Surface roughness of the fractured surface is also examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02321648
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