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41.
Thomas?ZolperEmail author Zhi?Li Manfred?Jungk Andreas?Stammer Herbert?Stoegbauer Tobin?Marks Yip-Wah?Chung Qian?Wang 《Tribology Letters》2013,49(2):301-311
The molecular structures, rheological properties, and friction coefficients of several new siloxane-based polymers were studied to explore their traction characteristics. The molecular structures including branch content were established by nuclear magnetic resonance spectroscopy, while the molecular mass distributions were determined by gel permeation chromatography. Density, viscosity, elastohydrodynamic film formation, and friction were investigated over a temperature range of 303–398 K. Film thickness and friction measurements were studied under the conditions that are representative of boundary, mixed, and full-film lubrication regimes, aiming at maximizing traction performance and temperature stability by simultaneous optimization of the size and content of ring-shaped branch structures. This study provides quantitative insight into the effect of siloxane molecular structure on the tribological performance for traction drive applications such as continuously variable transmissions. 相似文献
42.
Nobuhiko Hayashi Yusuke Kato Manfred Sigrist 《Journal of Low Temperature Physics》2005,139(1-2):79-96
The low-temperature shrinking of the vortex core (Kramer-Pesch effect) is studied for an isolated single vortex for chiral
p-wave and s-wave superconducting phases. The effect of nonmagnetic impurities on the vortex core radius is numerically investigated
in the Born limit by means of a quasiclassical approach. It is shown that in the chiral p-wave phase the Kramer-Pesch effect
displays a certain robustness against impurities owing to a specific quantum effect, while the s-wave phase reacts more sensitively
to impurity scattering. This suggests chiral p-wave superconductors as promising candidates for the experimental observation
of the Kramer-Pesch effect. 相似文献
43.
An analysis of the parametrization by data driven local coordinates for multivariable linear systems
Thomas Ribarits Author Vitae Manfred Deistler Author Vitae Tomas McKelvey Author Vitae 《Automatica》2004,40(5):789-803
In this paper, we study a novel parametrization for state-space systems, namely data driven local coordinates (DDLC) which have recently been introduced and applied. Even though DDLC has meanwhile become the default parametrization used in the system identification toolbox of the software package MATLAB, an analysis of properties of DDLC, which are relevant to identification, has not been performed up to now. In this paper, we provide insights into the geometry and topology of the DDLC construction and show a number of results which are important for actual identification such as maximum likelihood-type estimation. 相似文献
44.
Negro Catherine Del; Kreutzer Michel; Gahr Manfred 《Canadian Metallurgical Quarterly》2000,114(3):526
During the breeding season under long-day conditions, male canaries sing sexually attractive songs and females respond behaviorally to such songs. This study assessed whether auditory response properties of neurons in nucleus HVc of female and male canaries are tuned to sexually salient song features: special song phrases and canary song segmentation. In sexually receptive female canaries, neurons responded to special song phrases with a decreased spike rate and were sensitive to canary song segmentation. The nonreceptive females showed no clear response to special song phrases. In females on short days, neurons responded to song phrases with an increase in activity. In males on long days, they exhibited phasic responses after the phrase onset, whatever the song phrase and song segmentation. This study demonstrates both a plasticity in relation to females' sexual responsiveness and a sexual dimorphism in the auditory processing performed in the HVc. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
45.
We study the problem of parallel computation of a schedule for a system of n unit-length tasks on m identical machines, when the tasks are related by a set of precedence constraints. We present NC algorithms for computing an optimal schedule in the case where m, the number of available machines, does not vary with time and the precedence constraints are represented by a collection of outtrees. The algorithms run on an exclusive read, exclusive write (EREW) PRAM. Their complexities are O(log n) and O((log n)2) parallel time using O(n2) and O(n) processors, respectively. The schedule computed by our algorithms is a height-priority schedule. As a complementary result we show that it is very unlikely that computing such a schedule is in NC when any of the above conditions is significantly relaxed. We prove that the problem is P-complete under logspace reductions when the precedence constraints are a collection of intrees and outtrees, or for a collection of outtrees when the number of available machines is allowed to increase with time. The time span of a height-priority schedule for an arbitrary precedence constraints graph is at most 2 − 1/(m − 1) times longer than the optimal (N. E Chen and C. L. Liu, Proc. 1974 Sagamore Computer Conference on Parallel Processing, T. Fend (Ed.), Springer-Verlag, Berlin, 1975, pp. 1–16). Whereas it is P-complete to produce the classical height-priority schedules even for very restricted precedence constraints graphs, we present a simple NC parallel algorithm which produces a different schedule that is only 2 − 1/m times the optimal. 相似文献
46.
Dario Van Meenen Annika Doege Emily Alefeld Andr Haase Manfred Beier Tobias Kiefer Eva Biewald Klaus Metz Oliver Drger Maike Anna Busch Nicole Dünker 《International journal of molecular sciences》2022,23(20)
A disintegrin and metalloproteinase (ADAM) family proteins, acting as sheddases, are important factors in a number of pathologies, including cancer, and have been suggested as promising therapeutic targets. The study presented focuses on the involvement of ADAM10 and ADAM17 in retinoblastoma (RB), the most common malignant intraocular childhood tumor. A significant correlation between ADAM17 expression levels and RB laterality and RB staging was observed. Levels of ADAM10 or ADAM17 regulating miRNAs miR-145, -152, and -365 were significantly downregulated in RB cell lines, and reduced miR levels with simultaneously upregulated ADAM10 and ADAM17 expression were found in RB patients. The involvement of both ADAMs analyzed in ectodomain shedding of the neuronal cell adhesion molecule L1 (L1CAM), shown to induce pro-tumorigenic effects in RB, was confirmed. Lentiviral ADAM10 and ADAM17 single or ADAM10/17 double knockdown (KD) induced caspase-dependent apoptosis and reduced cell viability, proliferation, growth, and colony formation capacity of RB cells. Moreover, differential phosphorylation of the serine/threonine kinase AKT was observed following ADAM17 KD in RB cells. Chicken chorioallantoic membrane (CAM) assays revealed that ADAM17 and ADAM10/17 depletion decreases the tumorigenic and migration potential of RB cells in vivo. Thus, ADAMs are potential novel targets for future therapeutic RB approaches. 相似文献
47.
Daniel Alexander Bizjak Lucas John Lynn Matits Alisa Uhl Sebastian Victor Waldemar Schulz Jana Schellenberg Johannes Peifer Wilhelm Bloch Manfred Weiß Beate Grüner Hendrik Bracht Jürgen Michael Steinacker Marijke Grau 《International journal of molecular sciences》2022,23(23)
Hematological and hemorheological parameters are known to be altered in COVID-19; however, the value of combined monitoring in order to deduce disease severity is only scarcely examined. A total of 44 acute SARS-CoV-2-infected patients (aCOV) and 44 age-matched healthy controls (Con) were included. Blood of aCOV was sampled at admission (T0), and at day 2 (T2), day 5 (T5), day 10 (T10), and day 30 (T30) while blood of Con was only sampled once. Inter- and intra-group differences were calculated for hematological and hemorheological parameters. Except for mean cellular volume and mean cellular hemoglobin, all blood cell parameters were significantly different between aCOV and Con. During the acute disease state (T0–T5), hematological and hemorheological parameters were highly altered in aCOV; in particular, anemic conditions and increased immune cell response/inflammation, oxidative/nitrosative stress, decreased deformability, as well as increased aggregation, were observed. During treatment and convalescence until T30, almost all abnormal values of aCOV improved towards Con values. During the acute state of the COVID-19 disease, the hematological, as well as the hemorheological system, show fast and potentially pathological changes that might contribute to the progression of the disease, but changes appear to be largely reversible after four weeks. Measuring RBC deformability and aggregation, as well as oxidative stress induction, may be helpful in monitoring critically ill COVID-19 patients. 相似文献
48.
Jeremy Rott Eva Teresa Toepfer Maria Bartosova Ana Kolevica Alexander Heuser Michael Rabe Geert Behets Patrick C. DHaese Viktoria Eichwald Manfred Jugold Ivan Damgov Sotirios G. Zarogiannis Rukshana Shroff Anton Eisenhauer Claus Peter Schmitt 《International journal of molecular sciences》2022,23(14)
Serum calcium isotopes (δ44/42Ca) have been suggested as a non-invasive and sensitive Ca balance marker. Quantitative δ44/42Ca changes associated with Ca flux across body compartment barriers relative to the dietary Ca and the correlation of δ44/42CaSerum with bone histology are unknown. We analyzed Ca and δ44/42Ca by mass-spectrometry in rats after two weeks of standard-Ca-diet (0.5%) and after four subsequent weeks of standard- and of low-Ca-diet (0.25%). In animals on a low-Ca-diet net Ca gain was 61 ± 3% and femur Ca content 68 ± 41% of standard-Ca-diet, bone mineralized area per section area was 68 ± 15% compared to standard-Ca-diet. δ44/42Ca was similar in the diets, and decreased in feces and urine and increased in serum in animals on low-Ca-diet. δ44/42CaBone was higher in animals on low-Ca-diet, lower in the diaphysis than the metaphysis and epiphysis, and unaffected by gender. Independent of diet, δ44/42CaBone was similar in the femora and ribs. At the time of sacrifice, δ44/42CaSerum inversely correlated with intestinal Ca uptake and histological bone mineralization markers, but not with Ca content and bone mineral density by µCT. In conclusion, δ44/42CaBone was bone site specific, but mechanical stress and gender independent. Low-Ca-diet induced marked changes in feces, serum and urine δ44/42Ca in growing rats. δ44/42CaSerum inversely correlated with markers of bone mineralization. 相似文献
49.
The Alternaria toxins alternariol (AOH; 3,7,9-trihydroxy-1-methyl-6H-benzo[c]chromen-6-one) and alternariol methyl ether (AME, 3,7-dihydroxy-9-methoxy-1-methyl-6H-benzo[c]chromen-6-one) are common contaminants of food and feed, but their oxidative metabolism in mammals is as yet unknown. We have therefore incubated AME and AOH with microsomes from rat, human, and porcine liver and analyzed the microsomal metabolites with HPLC and GC-MS/MS. Seven oxidative metabolites of AME and five of AOH were detected. Their chemical structures were derived from their mass spectra using deuterated trimethylsilyl (TMS) derivatives, and from the information obtained from enzymatic methylation. Several of the metabolites were identified by comparison with synthetic reference compounds. AME as well as AOH were monohydroxylated at each of the four possible aromatic carbon atoms and also at the methyl group. In addition, AME was demethylated to AOH and dihydroxylated to a small extent. As the four metabolites arising through aromatic hydroxylation of AME and AOH are either catechols or hydroquinones, the oxidative metabolism of these mycotoxins may be of toxicological significance. 相似文献
50.
Manfred Schulz Gerd West Sakum Ourk Ingo Strunz 《Advanced Synthesis \u0026amp; Catalysis》1980,322(2):295-304
Azoperoxides. VI. Selective Decomposition of β-Azoacylperoxides The selective decomposition of the O O-Groups in the azoperoxides 1 and 2 is possible by reaction with dimethylaniline at 35°C. Rate constants were measured and the decomposition products were analyzed. Intermediates are azoalkyl radicals. The radical yield of the amine induced decomposition of 2 in ethylbenzene is 8.2% at 35°C. UV irradiation of the azoperoxides 1 and 2 at 20°C in ethylbenzene results in a quantitative and selective decomposition of the azo groups. Intermediates are C-radicals with intact peroxide groups. The reaction of 1 and 2 with triethylstannane yields reduction products of the O O-groups and the NN-groups, respectively. 相似文献