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21.
Light metal compound casting 总被引:1,自引:0,他引:1
‘Compound casting’simplifies joining processes by directly casting a metallic melt onto a solid metal substrate. A continuously metallurgic transition is very important for industrial applications, such as joint structures of spaceframe constructions in transport industry. In this project, ‘compound casting’ of light metals is investigated, aiming at weight-saving. The substrate used is a wrought aluminium alloy of type AA5xxx, containing magnesium as main alloying element. The melts are aluminium alloys, containing various alloying elements (Cu, Si, Zn), and magnesium. By replacing the natural oxygen layer with a zinc layer, the inherent wetting difficulties were avoided, and compounds with flawless interfaces were successfully produced (no contraction defects, cracks or oxides). Electron microscopy and EDX investigations as well as optical micrographs of the interfacial areas revealed their continu- ously metallic constitution. Diffusion of alloying elements leads to heat-treatable microstructures in the vicinity of the joining interfaces in Al-Al couples. This permits significant variability of mechanical properties. Without significantly cutting down on wettability, the formation of low-melting intermetallic phases (Al3Mg2 and Al12Mg17 IMPs) at the interface of Al-Mg couples was avoided by applying a protective coating to the substrate. 相似文献
22.
磁悬浮无轴承电动机发展、应用和前景 总被引:3,自引:0,他引:3
综述了磁悬浮无轴承电动机起源及发展历史,介绍了磁悬浮无轴承电动机的基本原理,详细论述了磁悬浮无轴承电动机在半导体工业、化工工业及生物工程等领域的应用特点和意义,展望了我国研究和应用磁悬浮无轴承电动机前景。 相似文献
23.
Object Involvement of distinct subcortical structures during sexual arousal was shown in animals and functional imaging studies gave
coarse evidence for a similar organisation in humans. In contrast to previous imaging studies at lower field strengths, we
tried to investigate activation in distinguishable subcortical structures at high spatial resolution during a short stimulating
paradigm to further account for potential effects of attenuation or adaptation.
Materials and methods Seven healthy subjects were investigated using functional magnetic resonance imaging (fMRI) on a 7 T scanner. High resolution
EPI images of 1.4 × 1.4 mm2 inplane resolution were acquired in a single functional session of 13.6 minutes. During the session erotic and non-erotic
pictures were presented in an event-related design.
Results In the unsmoothed data with preserved high spatial resolution significant effects were detected in relevant structures, including
anterior caudate and mediodorsal thalamus. These effects were restricted to subcortical target structures and their anatomical
boundaries.
Conclusion This study demonstrates that fMRI at high fields provides an ideal tool to investigate functional anatomy of subcortical structures.
Due to an increased signal-to-noise ratio, functional scans of short duration can be acquired at high resolution without the
need for further spatial smoothing. 相似文献
24.
Transitory starch granules result from complex carbon turnover and display specific situations during starch synthesis and degradation. The fundamental mechanisms that specify starch granule characteristics, such as granule size, morphology, and the number per chloroplast, are largely unknown. However, transitory starch is found in the various cells of the leaves of Arabidopsis thaliana, but comparative analyses are lacking. Here, we adopted a fast method of laser confocal scanning microscopy to analyze the starch granules in a series of Arabidopsis mutants with altered starch metabolism. This allowed us to separately analyze the starch particles in the mesophyll and in guard cells. In all mutants, the guard cells were always found to contain more but smaller plastidial starch granules than mesophyll cells. The morphological properties of the starch granules, however, were indiscernible or identical in both types of leaf cells. 相似文献
25.
Montasser Hijazi Esra Türkmen Prof. Joerg C. Tiller 《Chembiochem : a European journal of chemical biology》2020,21(6):874-882
Poly(2-oxazoline)s (POxs) with 2,2′-iminodiacetate (IDA) end groups were investigated as inhibitors for laccase. The polymers with the IDA end groups are reversible, competitive inhibitors for this enzyme. The IC50 values were found to be in a range of 1–3 mm . Compared with IDA alone, the activity was increased by a factor of more than 30; thus indicating that attaching a polymer chain to an inhibitor can already improve the activity of the former. The enzyme activity drops to practically zero upon increasing the concentration of the most active telechelic inhibitor, IDA-PEtOx30-IDA (PEtOx: poly(2-ethyl-2-oxazoline)), from 5 to 8 mm . This unusual behavior was investigated by means of dynamic light scattering, which showed specific aggregation above 5 mm . Furthermore, the laccase could be stabilized in the presence of POx-IDA, upon addition at a concentration of 20 mm and higher. Whereas laccase becomes completely inactive at room temperature after one week, the stabilized laccase is fully active for at least a month in aqueous solution. 相似文献
26.
Karlheinz Grotz Joerg U. Mayer Georg K. Suessmeier 《Signal Processing: Image Communication》1989,1(2):103-115
A new combination of coding methods for a 64 kbit/s transmission system for typical videophone situations is investigated. The codec structure is based on a standard hybrid discrete cosine transform (DCT) codec with temporal prediction. The picture is divided blockwise into changed and unchanged areas. One motion vector with subpel accuracy is computed and transmitted for each block of the changed area. For the forward analysis, the prediction error is calculated in the whole picture. Only the blocks with the highest prediction errors are updated by a DCT with a perception adaptive quantization. The number of DCT update blocks depends on the remaining bits after the transmission of the overhead information. The codec is controlled by a forward analysis of the prediction error and is not based on a buffer control. The spatial resolution of the source signal is reduced in two steps to prevent a codec overload caused by too much activity between two frames. 相似文献
27.
Kandukuri Rama Krishna Achterhold Jan Moeller Michael Stueckler Joerg 《International Journal of Computer Vision》2022,130(1):3-16
International Journal of Computer Vision - Representation learning for video is increasingly gaining attention in the field of computer vision. For instance, video prediction models enable activity... 相似文献
28.
Sarah A. Berger Dr. Christopher Grimm Jonathan Nyenhuis Dr. Stefan E. Payer Dr. Isabel Oroz-Guinea Dr. Joerg H. Schrittwieser Prof. Dr. Wolfgang Kroutil 《Chembiochem : a European journal of chemical biology》2023,24(11):e202300170
Mass spectrometry-based high-throughput screening methods combine the advantages of photometric or fluorometric assays and analytical chromatography, as they are reasonably fast (throughput ≥1 sample/min) and broadly applicable, with no need for labelled substrates or products. However, the established MS-based screening approaches require specialised and expensive hardware, which limits their broad use throughout the research community. We show that a more common instrumental platform, a single-quadrupole HPLC-MS, can be used to rapidly analyse diverse biotransformations by flow-injection mass spectrometry (FIA-MS), that is, by automated infusion of samples to the ESI-MS detector without prior chromatographic separation. Common organic buffers can be employed as internal standard for quantification, and the method provides readily validated activity and selectivity information with an analytical run time of one minute per sample. We report four application examples that cover a broad range of analyte structures and concentrations (0.1–50 mM before dilution) and diverse biocatalyst preparations (crude cell lysates and whole microbial cells). Our results establish FIA-MS as a versatile and reliable alternative to more traditional methods for screening enzymatic reactions. 相似文献
29.
Thiol–Ene Clickable Gelatin: A Platform Bioink for Multiple 3D Biofabrication Technologies 下载免费PDF全文
Sarah Bertlein Gabriella Brown Khoon S. Lim Tomasz Jungst Thomas Boeck Torsten Blunk Joerg Tessmar Gary J. Hooper Tim B. F. Woodfield Juergen Groll 《Advanced materials (Deerfield Beach, Fla.)》2017,29(44)
Bioprinting can be defined as the art of combining materials and cells to fabricate designed, hierarchical 3D hybrid constructs. Suitable materials, so called bioinks, have to comply with challenging rheological processing demands and rapidly form a stable hydrogel postprinting in a cytocompatible manner. Gelatin is often adopted for this purpose, usually modified with (meth‐)acryloyl functionalities for postfabrication curing by free radical photopolymerization, resulting in a hydrogel that is cross‐linked via nondegradable polymer chains of uncontrolled length. The application of allylated gelatin (GelAGE) as a thiol–ene clickable bioink for distinct biofabrication applications is reported. Curing of this system occurs via dimerization and yields a network with flexible properties that offer a wider biofabrication window than (meth‐)acryloyl chemistry, and without additional nondegradable components. An in‐depth analysis of GelAGE synthesis is conducted, and standard UV‐initiation is further compared with a recently described visible‐light‐initiator system for GelAGE hydrogel formation. It is demonstrated that GelAGE may serve as a platform bioink for several biofabrication technologies by fabricating constructs with high shape fidelity via lithography‐based (digital light processing) 3D printing and extrusion‐based 3D bioprinting, the latter supporting long‐term viability postprinting of encapsulated chondrocytes. 相似文献
30.