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Digitale Medien

Flextensional Barium Strontium Titanate Actuators (2003)

Meyer, Richard J. ; Newnham, Robert E. ; Amin, Ahmed ; [weitere]

Westerville, Ohio : American Ceramics Society

Journal of the American Ceramic Society 86 (2003), S. 0

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ISSN: 1551-2916

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Maschinenbau , Physik

Notizen: This paper describes the performance of the cymbal flextensional transducer using Dy-doped barium strontium titanate (BST) as the driver material. BST was first characterized for its dielectric and loss behavior as a function of temperature and electrical bias field. With no electrical bias, the transition temperature was measured to be near 20°C and have a dielectric constant 〉20 000. The strain of a BST disk was then measured and compared with other ceramics. At room temperature the strain and average effective piezoelectric d33 of this non-lead composition was slightly larger than Navy type I lead zirconate titanate (PZT-4) ceramic. The strain/field behavior was also measured as a function of temperature. Cymbal capped BST ceramic was found to have an amplified displacement of 28×, also very similar to type I ceramic. The stiffness of BST was found to be tunable by dc voltage and 2 to 3 times larger than that of PZT. This material has promise for applications in actuators and transducers with large generative force.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1151-2916.2003.tb03400.x

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2

Digitale Medien

Classical Behavior of the Dirac Bispinor (2000)

Bell, Sarah B. M. ; Cullerne, John P. ; Diaz, Bernard M.

Springer

Foundations of physics 30 (2000), S. 35-57

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ISSN: 1572-9516

Quelle: Springer Online Journal Archives 1860-2000

Thema: Physik

Notizen: Abstract It is usually supposed that the Dirac and radiation equations predict that the phase of a fermion will rotate through half the angle through which the fermion is rotated, which means, via the measured dynamical and geometrical phase factors, that the fermion must have a half-integral spin. We demonstrate that this is not the case and that the identical relativistic quantum mechanics can also be derived with the phase of the fermion rotating through the same angle as does the fermion itself. Under spatial rotation and Lorentz transformation the bispinor transforms as a four-vector like the potential and Dirac current. Previous attempts to provide this form of transformational behavior have foundered because a satisfactory current could not be derived.(14)

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1003686924816

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3

Digitale Medien

Location and mapping of the powdery mildew resistance gene MlRE and detection of a resistance QTL by bulked segregant analysis (BSA) with microsatellites in wheat (2000)

Chantret, N. ; Sourdille, P. ; Röder, M. ; [weitere]

Springer

Theoretical and applied genetics 100 (2000), S. 1217-1224

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ISSN: 1432-2242

Schlagwort(e): Key words Triticum aestivum ; Blumeria graminis f. sp. tritici ; QTL mapping ; Molecular markers ; Disease resistance

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract Powdery mildew (Blumeria graminis f. sp. tritici) is one of the most damaging diseases of wheat (Triticum aestivum). The objective of this study was to locate and map a recently identified powdery mildew resistance gene, MlRE, carried by the resistant line RE714 using microsatellites uniformly distributed among the whole genome together with a bulked segregant analysis (BSA). The bulks consisted of individuals with an extreme phenotype taken from a population of 140 F3 families issued from the cross between RE714 (resistant) and Hardi (susceptible). The population had been tested with three powdery mildew isolates at the seedling stage. Qualitative interpretation of the resistance tests located the MlRE gene on the distal part of the long arm of chromosome 6A. A subsequent quantitative interpretation of the resistance permitted us to detect another resistance factor on a linkage group assigned to chromosome 5D, which was constructed with microsatellites for which a polymorphism of intensity between bulks was observed. This quantitative trait locus (QTL) explained 16.8– 25.34% of the total variation. An interaction between both the resistant factor (MlRE and the QTL) was found for only one of the isolates tested. This study shows the advantage of making a quantitative interpretation of resistant tests and that the use of microsatellites combined with BSA is a powerful strategy to locate resistance genes in wheat.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s001220051427

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4

Digitale Medien

Fluorogenic Probes Applied to the Study of Induced Oxidative Stress in the Human Leukemic HL60 Cell Line (2000)

Plantin-Carrenard, E. ; Braut-Boucher, F. ; Bernard, M. ; [weitere]

Springer

Journal of fluorescence 10 (2000), S. 167-167

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ISSN: 1573-4994

Schlagwort(e): Fluorogenic probes ; microspectrofluorometry ; HL60 cell line ; oxidative stress ; thiol status

Quelle: Springer Online Journal Archives 1860-2000

Thema: Physik

Notizen: Abstract Development of microspectrofluorometric methods using specific fluorogenic probes has provided precious help in studying in situ oxidative stress and cellular protective systems. The aim of this study was to determine ROS production concomitantly with a modification of the intracellular thiol pool after applying an oxidative stress to a nonadherent cell model represented by the HL60 cell line. The dichlorodihydrofluorescein diacetate (H2DCFDA) probe assessed the kinetic production of ROS by cells submitted to the chemical oxidant t-butylhydroperoxide with a high signal/noise ratio. The probe sensitivity permitted us to detect endogenous ROS production in HL60 cells and the protective effect of N-acetyl cysteine against ROS. The chloromethylfluorescein diacetate probe (CMFDA) permitted us to evaluate the thiol depleting effect of N-ethyl maleimide. Complete thiol depletion was associated with a moderate increase in ROS production. The cell viability was determined with calcein-AM, which gave results similar to those with the tetrazolium dye. This probe was not affected by intracellular pH and did not required an extraction step, unlike tetrazolium dye. In conclusion, cell-permeant fluorogenic probes are useful and sensitive tools to determine in situ ROS production concomitantly with consecutive change in the thiol system in a living and non-adherent cell model.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009499210857

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5

Digitale Medien

Location of genes involved in ear compactness in wheat (Triticum aestivum) by means of molecular markers (2000)

Sourdille, P. ; Tixier, M.H. ; Charmet, G. ; [weitere]

Springer

Molecular breeding 6 (2000), S. 247-255

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ISSN: 1572-9788

Schlagwort(e): mapping ; morphology ; QTL ; RFLP ; spike density ; Triticeae

Quelle: Springer Online Journal Archives 1860-2000

Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft

Notizen: Abstract Quantitative trait loci (QTLs) for three traits related to ear morphology (spike length, number of spikelets, and compactness as the ratio between number of spikelets and spike length) in wheat (Triticum aestivum L.) were mapped in a doubled-haploid (DH) population derived from the cross between the cultivars Courtot and Chinese Spring. A molecular marker linkage map of this cross that had previously been constructed based on 187 DH lines and 380 markers was used for QTL mapping. The genome was well covered (85%) except chromosomes 1D and 4D and a set of anchor loci regularly spaced (one marker each 15.5 cM) were chosen for marker regression analysis. The presence of a QTL was declared at a significance threshold α = 0.001. The population was grown in one location under field conditions during three years (1994, 1995 and 1998). For each trait, 4 to 6 QTLs were identified with individual effects ranging between 6.9% and 21.8% of total phenotypic variation. Several QTLs were detected that affected more than one trait. Of the QTLs 50% were detected in more than one year and two of them (number of spikelets on chromosome 2B, and compactness on chromosome 2D) emerged from the data from the three years. Only one QTL co-segregated with the gene Q known to be involved in ear morphology, namely the speltoid phenotype. However, this chromosome region explained only a minor part of the variation (7.5–11%). Other regions had a stronger effect, especially two previously unidentified regions located on chromosomes 1A and 2B. The region on the long arm of chromosome 1A was close to the locus XksuG34-1A and explained 12% of variation in spike length and 10% for compactness. On chromosome 2B, the QTL was detected for the three traits near the locus Xfbb121-2B. This QTL explained 9% to 22% of variation for the traits and was located in the same region as the gene involved in photoperiod response (Ppd2). Other regions were located at homoeologous positions on chromosomes 2A and 2D.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009688011563

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6

Digitale Medien

The Penaeus monodon Chitinase 1 Gene Is Differentially Expressed in the Hepatopancreas During the Molt Cycle (2000)

Tan, Siok Hwee ; Degnan, Bernard M. ; Lehnert, Sigrid A.

Springer

Marine biotechnology 2 (2000), S. 126-135

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ISSN: 1436-2236

Schlagwort(e): Key words:Penaeus monodon, shrimp, chitinase, gene expression

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Abstract: We have isolated a full-length chitinase complementary DNA from the tiger shrimp Penaeus monodon that encodes a 621 amino acid protein possessing the functional domains of the chitinase protein family. The Penaeus monodon chitinase 1 (PmChi-1) gene product is 81.8% identical to a chitinase 1 protein expressed in the hepatopancreas of Penaeus japonicus. Analysis by reverse transcription–polymerase chain reaction (RT-PCR) indicates that PmChi-1 messenger RNA is detectable in the hepatopancreas and the gut. PmChi-1 expression during the molt cycle fluctuates markedly, with lowest mRNA levels at stages A1, C, and D3; there is a dramatic increase in transcript abundance at the D2 stage. Using the same tissues and molt stages, RT-PCR analyses of genes encoding other digestive enzymes (trypsin, chymotrypsin, and cathepsin L), a muscle structural protein (tropomyosin II), and housekeeping proteins (elongation factor II and GTP-binding protein) indicate that PmChi-1 is expressed in a distinct tissue-specific and stage-specific manner. The other digestive enzyme genes are expressed in a similar spatiotemporal pattern, but none exhibited a dramatic increase in transcript abundance at stage D2. Increased expression of PmChi-1 at D2 suggests that hepatopancreas-expressed chitinase is involved in the degradation of endogenous chitin in the gut peritrophic membrane prior to molting.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s101269900016

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7

Digitale Medien

Expression of POU, Sox, and Pax Genes in the Brain Ganglia of the Tropical Abalone Haliotis asinina (2000)

O'Brien, Elizabeth K. ; Degnan, Bernard M.

Springer

Marine biotechnology 2 (2000), S. 545-557

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ISSN: 1436-2236

Schlagwort(e): Key words:POU, Sox, Pax, ganglia, mollusk, lophotrochozoan.

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Abstract: In gastropod mollusks, neuroendocrine cells in the anterior ganglia have been shown to regulate growth and reproduction. As a first step toward understanding the molecular mechanisms underlying the regulation of these physiological processes in the tropical abalone Haliotis asinina, we have identified sets of POU, Sox, and Pax transcription factor genes that are expressed in these ganglia. Using highly degenerate oligonucleotide primers designed to anneal to conserved codons in each of these gene families, we have amplified by reverse transcriptase polymerase chain reaction 2 POU genes (HasPOU-III and HasPOU-IV), 2 Sox genes (HasSox-B and HasSox-C), and two Pax genes (HasPax-258 and HasPax-6). Analyses with gene-specific primers indicated that the 6 genes are expressed in the cerebral and pleuropedal ganglia of both reproductively active and spent adults, in a number of sensory structures, and in a subset of other adult tissues.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s101260000039

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