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排序方式: 共有604条查询结果,搜索用时 12 毫秒
531.
Yanzhen Zhang Dege Li Yonghong Liu Gunther Wittstock 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(39)
Despite their specific methodologies, all current noncontact printing techniques such as inkjet printing (IJP), involve the break‐up of a liquid meniscus during the separation of the ink droplet from the bulk ink reservoir. Often, the break‐up of a liquid meniscus results in the formation of one or more satellite droplet whose volumes are several orders of magnitude smaller than the primary droplet. Many attempts are directed to suppress or control the formation of satellite droplets because they blur the printing result. For the first time, a simple mechanism by which a single satellite droplet is exclusively formed and directed to the substrate by a gas stream while the primary droplet remains attached to a metal rod used for controlling the formation and break‐up of the meniscus is reported. High printing resolution is demonstrated by satellite droplets printing (SDP) without the need for small orifices which are prone to clogging. Furthermore, the droplet generation from a large orifice enables SDP to handle viscous inks which has remained challenging for traditional IJP. 相似文献
532.
533.
DC Goodwin MR Gunther LC Hsi BC Crews TE Eling RP Mason LJ Marnett 《Canadian Metallurgical Quarterly》1998,273(15):8903-8909
Tyrosyl radicals have been detected during turnover of prostaglandin endoperoxide H synthase (PGHS), and they are speculated to participate in cyclooxygenase catalysis. Spectroscopic approaches to elucidate the identity of the radicals have not been definitive, so we have attempted to trap the radical(s) with nitric oxide (NO). NO quenched the EPR signal generated by reaction of purified ram seminal vesicle PGHS with arachidonic acid, suggesting that NO coupled with a tyrosyl radical to form inter alia nitrosocyclohexadienone. Subsequent formation of nitrotyrosine was detected by Western blotting of PGHS incubated with NO and arachidonic acid or organic hydroperoxides using an antibody against nitrotyrosine. Both arachidonic acid and NO were required to form nitrotyrosine, and tyrosine nitration was blocked by the PGHS inhibitor indomethacin. The presence of superoxide dismutase had no effect on nitration, indicating that peroxynitrite was not the nitrating agent. To identify which tyrosines were nitrated, PGHS was digested with trypsin, and the resulting peptides were separated by high pressure liquid chromatography and monitored with a diode array detector. A single peptide was detected that exhibited a spectrum consistent with the presence of nitrotyrosine. Consistent with Western blotting results, both NO and arachidonic acid were required to observe nitration of this peptide, and its formation was blocked by the PGHS inhibitor indomethacin. Peptide sequencing indicated that the modified residue was tyrosine 385, the source of the putative catalytically active tyrosyl radical. 相似文献
534.
Alexander D Hoffmann J Munz A Friedrich B Geis-Gerstorfer J Reinert S 《Journal of materials science. Materials in medicine》2008,19(3):965-974
For bone regeneration constructs using human jaw periosteal cells (JPC) the extent of osteoinductive ability of different
three-dimensional scaffolds is not yet established. We analyzed open-cell polylactic acid (OPLA) scaffolds for their suitability
as bone engineering constructs using human JPC. Cell adhesion and spreading was visualized on the surface of scaffolds by
scanning electron microscopy. JPC proliferation within OPLA scaffolds was compared with proliferation within collagen and
calcium phosphate scaffolds. We found a significant increase of proliferation rates in OPLA scaffolds versus Coll/CaP scaffolds
at three time points. Live-measurements of oxygen consumption within the cell-seeded scaffolds indicate that the in vitro
culturing time should not exceed 12–15 days. OPLA scaffolds, which were turned out to be the most beneficial for JPC growth,
were chosen for osteogenic differentiation experiments with or without BMP-2. Gene expression analyses demonstrated induction
of several osteogenic genes (alkaline phosphatase, osterix, Runx-2 and insulin-like growth factor) within the 3D-scaffolds
after 12 days of in vitro culturing. Element analysis by EDX spectrometry of arising nodules during osteogenesis demonstrated
that JPC growing within OPLA scaffolds are able to form CaP particles. We conclude that OPLA scaffolds provide a promising
environment for bone substitutes using human JPC. 相似文献
535.
LJ Gershwin ES Schelegle RA Gunther ML Anderson AR Woolums DR Larochelle GA Boyle KE Friebertshauser RS Singer 《Canadian Metallurgical Quarterly》1998,16(11-12):1225-1236
A critical issue has been the observation that vaccination of children with a formalin-inactivated respiratory syncytial virus (RSV) vaccine is associated with disease enhancement. We have taken advantage of bovine RSV and our experience with this disease in calves to develop a natural model that parallels human disease. Using formalin-inactivated bovine RSV vaccine calves were either sham-vaccinated/infected, vaccinated/infected, or vaccinated/sham-infected and their clinical signs, pulmonary function, and histological lung lesions quantitatively scored. Interestingly there was significantly greater disease in vaccinated/infected calves and histological lesions in calves were similar to those of affected children. Finally, we note that vaccination did not induce neutralizing antibodies, but IgG antibodies were detected by ELISA. Our model of RSV enhanced disease is important because it provides quantifiable evidence of disease severity that can be applied to evaluate the mechanisms of immunopathology and the safety of candidate RSV vaccines. 相似文献
536.
MW Holladay H Bai Y Li NH Lin JF Daanen KB Ryther JT Wasicak JF Kincaid Y He AM Hettinger P Huang DJ Anderson AW Bannon MJ Buckley JE Campbell DL Donnelly-Roberts KL Gunther DJ Kim TA Kuntzweiler JP Sullivan MW Decker SP Arneric 《Canadian Metallurgical Quarterly》1998,8(19):2797-2802
Analogs of A-98593 (1) and its enantiomer ABT-594 (2) with diverse substituents on the pyridine ring were prepared and tested for affinity to nicotinic acetylcholine receptor binding sites in rat brain and for analgesic activity in the mouse hot plate assay. Numerous types of modifications were consistent with high affinity for [3H]cytisine binding sites. By contrast, only selected modifications resulted in retention of analgesic potency in the same range as 1 and 2. Analogs of 2 with one or two methyl substituents at the 3-position of the azetidine ring also were prepared and found to be substantially less active in both assays. 相似文献
537.
F.N. van de Vosse J. de Hart C.H.G.A. van Oijen D. Bessems T.W.M. Gunther A. Segal B.J.B.M. Wolters J.M.A. Stijnen F.P.T. Baaijens 《Journal of Engineering Mathematics》2003,47(3-4):335-368
In this paper a combined arbitrary Lagrange-Euler fictitious domain (ALE-FD) method for fluid-structure interaction problems in cardiovascular biomechanics is derived in terms of a weighted residual finite-element formulation. For both fluid flow of blood and solid mechanics of vascular tissue, the performance of tetrahedral and hexahedral Crouzeix-Raviart elements are evaluated. Comparable convergence results are found, although for the test cases considered the hexahedral elements are more accurate. The possibilities that are offered by the ALE-FD method are illustrated by means of a simulation of valve dynamics in a simplified left ventricular flow model. 相似文献
538.
CA Brandt J Meller L Keweloh K H?schel J Staedt D Munz G Stoppe 《Canadian Metallurgical Quarterly》1998,105(10-12):1325-1333
There are published studies concerning a regionally changed function of GABA-benzodiazepine-receptor-complexes in anxiety disorder. These studies implicate the limbic lobe, the brainstem and the prefrontal cortex. Using 123I-Iomazenil and single photon emission tomography (SPET) we investigated the benzodiazepine receptor density in twelve patients with panic disorder who had never been treated with benzodiazepines before. Nine age- and sex-matched volunteers who were free of mental illness served as controls. Patients with panic disorder showed a significant increase of benzodiazepine receptor binding in the right supraorbital cortex and a trend to an increased uptake in the right temporal cortex. There was no correlation between receptor density and scores on Spielberger's State Trait Anxiety Inventory in the patient group. Since the findings cannot be explained by benzodiazepine exposure we hypothesize an upregulation due to functional or neuroanatomic changes (at least) in the frontotemporal cortex. 相似文献
539.
Wesentliche Voraussetzung für eine kostengünstige Ermittlung von Rißzähigkeitskennwerten ist eine einfache und zuverlässige Bestimmung der stabilen Rißausbreitung. Da die Potentialmethode zur Ermittlung der Rißinitiierung und des Rißwachstums vielfach vorgeschlagen wird, sollte die Leistungsfähigkeit der Methode im durchgeführten Ringversuch ermittelt und das Verfahren durch Vergleich der angewandten Versuchstechniken optimiert werden. 相似文献
540.
To assess the role of metabolic shifts in pathogenesis of excretory renal dysfunction arising in chronic glomerulonephritis (CGN), two groups of patients were considered. Fourteen patients of group 1 had CGN in a preazotemia stage, thirteen patients of group 2 died of CGN-induced uremia. Cortical nephrobiopsies obtained intravitally (group 1) and renal tissue specimens obtained at autopsies during postmortal hours 0-2 (group 2) were investigated. Apical epithelium of proximal canaliculi in group 1 showed higher levels of acid phosphatase (AP), though much lower of succinate dehydrogenase (SDH) and lactate dehydrogenase (LDH) compared to group 2. In basal proximal nephrothelium of group 1 the activity of LDH and AP was inhibited against these values in group 2. The activity of NADPN2-dehydrogenase, SDH and AP in group 1 surpassed that in group 2 in endothelium of renal cortex peritubular capillaries. These structures LDH and AP proved more active in group 1. The authors observed a series of significant multidirectional correlations between the activity of the enzymes studied and renal excretion. The growing activity of NADN2-dehydrogenase and AP was associated with diminution of electrolyte and water excretion, while enhancing LDH activity exhibited the opposite effect. It is concluded that progression of cortical disorders in the kidneys of CGN patients entails serious metabolic derangement reflected by imbalance in aerobic and anaerobic metabolism. These biochemical shifts result in ambiguous functional sequelae and may contribute both to renal retention of fluid, electrolytes and their excretion. The latter is likely a compensatory mechanism involved in maintenance of water-salt homeostasis in relevant patients. 相似文献