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排序方式: 共有185条查询结果,搜索用时 15 毫秒
141.
Duncan Phillips John Taylor Rajesh Lakhanpal Robin Hall John Bailey Geoff Bevan John Lloyd Juergen Hoffmeister Derek McKelvey 《Coloration Technology》2000,116(7-8):229-234
This study uses previously proposed spectrophotometric pass/fail criteria for the assessment of oxidative-bleach fading of cellulosic dyes on cotton during repeated washing. A high level of correlation (88%) has been obtained between the fading exhibited by optionally aftertreated direct dyes in the UK-TO test and that after 20 domestic machine washes in the presence of a detergent containing an oxidative-bleach system. The correlation, and ultimate utility of the test method, is further improved when preceded by an ISO 105 C06/C2S wash fastness test to screen out dyes having a low intrinsic fastness to washing. 相似文献
142.
Active‐Site Engineering Expands the Substrate Profile of the Basidiomycete l‐Tryptophan Decarboxylase CsTDC
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Daniel Kalb Julia Gressler Prof. Dr. Dirk Hoffmeister 《Chembiochem : a European journal of chemical biology》2016,17(2):132-136
Aromatic l ‐amino acid decarboxylases (AADCs) catalyze the release of CO2 from proteinogenic and non‐proteinogenic l ‐amino acid substrates and are involved in pathways that biosynthesize neurotransmitters or bioactive natural products. In contrast to AADCs from animals and plants, fungal AADCs have received very little attention. Here, we report on the in vitro characterization of heterologously produced Ceriporiopsis subvermispora AADC, now referred to as CsTDC, which is the first characterized basidiomycete AADC. This study identified the enzyme as a decarboxylase that is strictly specific for l ‐tryptophan and 5‐hydroxy‐l ‐tryptophan. The tdc gene was subjected to saturation mutagenesis so as to vary the key active site residue, Gly351. Aliphatic amino acid residues, l ‐serine, or l ‐threonine at position 351 added l ‐tyrosine and 3,4‐dihydroxy‐l ‐phenylalanine (l ‐DOPA) decarboxylase activity while retaining stereospecificity and l ‐tryptophan decarboxylase activity. 相似文献
143.
144.
Gerhard Sedlacek Winfried Dahl Benno Hoffmeister Bertram Kühn Markus Feldmann Thomas Pinger Peter Langenberg Helena Eichenmüller Dietmar Grotmann Marc Blum 《Stahlbau》2004,73(6):427-437
Reliable application of hot dip zinc coated steel beams. Hot dip zinc coated steel beams as used e.g. for parking houses may be susceptible to cracking, with cracks along the beam axis starting from welds of partial end plate connections, in some cases also cracks at the bottom flange transverse to the beam axis occurred which propagated from local plastic deformations e.g. from cold forming for pre‐cambering the beams. The report describes the various causes interacting in the formation of the cracks according to the present state of knowledge and also gives tentative recommendations for the choice of material, structural detailing, fabrication and the hot dip coating process to avoid cracks in the future. 相似文献
145.
Hans-Werner Fenzke 《国际钢铁研究》1993,64(1):45-47
The report deals with investigations of the sulfur behaviour in the Fe–CaO-Al2O3 – H2S-H2 system at 1600°C and at very low values for the partial pressure of oxygen and sulfur. Results of the equilibrium in the iron-gas system, of the sulfide and sulfur capacities, of the solubility and activity of CaS in CaO-Al2O3 slags are represented. 相似文献
146.
Grimm S Giesa R Sklarek K Langner A Gösele U Schmidt HW Steinhart M 《Nano letters》2008,8(7):1954-1959
Ordered nanofiber arrays are a promising material platform for artificial adhesive structures, tissue engineering, wound dressing, sensor arrays, and self-cleaning surfaces. Their production via self-ordered porous alumina hard templates serving as shape-defining molds is well-established. However, their release requires the destruction of the hard templates, the fabrication of which is costly and time-consuming, by wet-chemical etching steps with acids or bases. We report the nondestructive mechanical extraction of arrays of cross-linked polyacrylate nanofibers from thus recyclable self-ordered nanoporous alumina hard templates. Silica replicas of the latter were synthesized using the extricated nanofiber arrays as secondary molds that could be mechanically detached from the molded material. The approach reported here, which can be combined with microstructuring, may pave the way for the high-throughput production of both functional nanofiber arrays and ordered nanoporous membranes consisting of a broad range of material systems. 相似文献
147.
Chengsong Cui Alwin Schulz Volker Uhlenwinkel Hans-Werner Zoch 《Metallurgical and Materials Transactions A》2011,42(8):2442-2455
In order to develop new types of wear-resistant and corrosion-resistant materials, TiC and VC particles were injected into
martensitic stainless steel X46Cr13 during spray forming, respectively. The microstructures of the spray-formed steel matrix
composites under different processing conditions were investigated. The mechanisms of interactions between the injected particles
and the matrix materials during spray forming and their effects on the microstructures of the composites were discussed and
clarified based on experimental and theoretical investigations. The current results show that the injected particles may penetrate
into the metallic droplets or adhere to the surface of the droplets and, therefore, are incorporated into the deposits to
form metal matrix composites. Substantial heat transfer from superheated metallic melts to the room temperature carbide particles
takes place as they are incorporated into the matrix material. The matrix steel solidifies in the vicinity of the carbides
due to their chilling effect, and thus, the carbides may be engulfed in the matrix or pushed to the grain boundaries by the
solidification fronts. TiC particles essentially retain their shape and size in the steel composites, while VC particles dissolve
at least partially in the matrix and reprecipitate or form new phases in the final solidification and cooling stage. The porosity
in the deposits increases with the gas to melt ratio (GMR) and the powder to melt ratio (PMR) by increasing atomizing gas
pressure and powder feeding rate. Carbide type also affects the porosity of the deposits, because different thermodynamic
properties of carbides change the heat dissipation and local solidification behavior of the mixture of matrix material and
dissolved carbides. Moreover, the microstructure of the matrix material X46Cr13 is refined considerably with increasing GMR
and PMR. 相似文献
148.
Dipl.-Ing. Reinhard Lohmeier Hans-Werner Schröder Jens-Uwe Repke Hado Heckmann 《BHM Berg- und Hüttenm?nnische Monatshefte》2013,158(11):451-452
COREX®/FINEX® smelting reduction processes require lumpy coal for stable operation. The screened-off coal fines must be briquetted by means of binders to be utilizable for the COREX®/FINEX® processes. Optimal binder types, their amount, and briquetting conditions are identified by systematic experimental analyses. Experimental work is based on a critical review of literature to get knowledge about the theoretical background of hard coal briquetting, established hard coal briquetting technologies, and typical tests for metallurgical carbon carriers. Binder briquetting of hard coal is known to produce briquettes for heating. Compared to metallurgical use, briquettes quality and process behavior requirements are differing, but basic mechanisms like coal-binder-interaction are similar. 相似文献
149.
150.
Tim Rauert Hetty Bigelow Benno Hoffmeister Markus Feldmann Rüdiger Patz Peter Lippert 《Bautechnik》2010,87(12):751-760
Die Weiterentwicklung des europäischen Eisenbahnnetzes ist unter anderem durch den vermehrten Einsatz von Hochgeschwindigkeitszügen und eine signifikante Anhebung der Betriebsgeschwindigkeiten gekennzeichnet. Um die Auswirkungen von Zugbeanspruchungen auf Eisenbahnbrücken im Rahmen einer dynamischen Bemessung hinreichend genau vorhersagen zu können, ist die Kenntnis der wesentlichen dynamischen Systemeigenschaften erforderlich. Nur so können bemessungsrelevante Resonanzeffekte, die bei hohen Geschwindigkeiten grundsätzlich nicht auszuschließen sind, rechnerisch auf zuverlässige Weise erfasst werden. Messungen insbesondere an WIB‐Überbauten zeigen jedoch, dass eine realistische rechnerische Abschätzung von Brückeneigenfrequenzen schwierig ist. Tatsächliche und rechnerische Werte weichen in vielen Fällen erheblich voneinander ab. Als ursächlich wird hierfür unter anderem eine unzureichende Berücksichtigung baulicher Randbedingungen angesehen, die teilweise erheblichen Einfluss auf die Steifigkeits‐ und Dämpfungseigenschaften der Brücke haben. Der erste Teil des Beitrags führte in die Problematik ein und präsentierte Ergebnisse aus Messuntersuchungen an WIB‐Brücken. Im vorliegenden zweiten Teil des Beitrags wird nun auf Grundlage numerischer Studien gezeigt, wie sich bauliche Randbedingungen auf das dynamische Verhalten von WIB‐Überbauten auswirken. Abschließend werden die Untersuchungsergebnisse dazu genutzt, Vorschläge für eine genauere dynamische Bemessung abzuleiten. On the influence of constructional elements on the dynamic behaviour of filler beam railway bridges. Enhancements of the European railway system are amongst other things mainly characterized by increased usage of high speed trains and significantly raised operating speeds. To predict effects of train loading on railway bridges for a dynamic design adequately, knowledge of the system’s significant dynamic characteristics is required. Only this ensures that resonance effects, which generally cannot be screened out for high speeds, can be covered analytically by reliable values. Measurements especially carried out on filler beam bridges have shown though that a realistic estimation of eigenfrequencies of bridges is difficult. Actual values and measured ones differ significantly in many cases. In particular non‐consideration of structural constraints is seen as reason for this, given that they have an immense effect on a bridge’s stiffness and damping characteristics. The first part of the contribution gave a brief survey on the dynamics of high‐speed railway bridges. Furthermore results from measurements on filler beam railway decks were presented. In this second part of the contribution the influence of particular constructional elements on the dynamic behaviour of filler beam bridges is investigated, supported by numerical studies. Finally the main outcomes are discussed and proposals for an improved dynamic bridge design are made. 相似文献