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排序方式: 共有275条查询结果,搜索用时 343 毫秒
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Christoph Weigel Valeriya Cherkasova Mathias Holz Hai Binh Phi Christian Görner Tenorio Björn Wilbertz Leonard Voßgrag Thomas Fröhlich Steffen Strehle 《Advanced Engineering Materials》2023,25(9):2201873
Ultralow expansion (ULE) glasses are of special interest for temperature stabilized systems for example in precision metrology. Nowadays, ULE materials are mainly used in macroscopic and less in micromechanical systems. Reasons for this are a lack of technologies for parallel fabricating high-quality released microstructures with a high accuracy. As a result, there is a high demand in transferring these materials into miniaturized application examples, realistic system modeling, and the investigation of microscopic material properties. Herein, a technological base for fabricating released micromechanical structures and systems with a structure height above 100 μm in ULE 7972 glass is established. Herein, the main fabrication parameters that are important for the system design and contribute thus to the introduction of titanium silicate as material for glass-based micromechanical systems are discussed. To study the mechanical properties in combination with respective simulation models, microcantilevers are used as basic mechanical elements to evaluate technological parameters and other impact factors. The implemented models allow to predict the micromechanical system properties with a deviation of only ±5% and can thus effectively support the micromechanical system design in an early stage of development. 相似文献
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Wolfgang Sümmermann Hans Rohleder und Friedhelm Korte 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1978,166(3):137-144
Zusammenfassung Im Rahmen eines koordinierten Forschungsprogramms des BMFT wurde eine orientierende Studie an möglichst repräsentativen Stichproben durchgeführt. Trotz relativ großer Streubreiten zeichnen sich die Bereiche der wichtigsten Lebensmittelgruppen deutlich voneinander ab mit Mittelwerten um 0,005 /g für fettarme pflanzliche Grundnahrungsmittel, um 0,05 /g für pflanzliche Nahrungsfette, um 0,3 /g für Milch-, Käse und Butterfette, um 0,15 /g für sonstige Nahrungsfette von Landtieren, um 0,03 /g für Hühnereier und um 10 /g für Fischfett. Wichtet man die Gehalte entsprechend der durchschnittlichen Diät in der BRD, so ergibt sich eine tägliche PCB-Aufnahme von rund 29 aus tierischen Fetten und rund 6 aus den übrigen Lebensmitteln. Die Gesamtaufnahme von ca. 35 g pro Tag und capita entspricht etwa dem Wert, der von der WHO als ADI-Wert für HCB (Hexachlorbenzol) in Aussicht genommen wurde.
Polychlorinated biphenyls (PCB) in foodThe situation in the Federal Republic of Germany
Summary In a coordinated research program of the Federal Ministry of Research and Technology (BMFT), a screening study was carried out with representative samples. In spite of rather large ranges of PCB concentrations, the most important food-stuffs show clearly defined clusters with mean values of approx. 0.005 /g in low fat food components of plant origin such as cereals or potatoes, approx. 0.05 /g in vegetable fats, approx. 0.3 /g in fat from milk, butter and cheese, approx. 0.15 gg/g in animal fat, approx. 0.03 in chicken eggs and approx. 10 /g in fish fat. Considering the mean diet in the FRG, a daily PCB intake of about 29 g from animal fat and of 6 from the other food-stuffs results. The total intake of about 35 g per day and capita is almost the same as the figure conditionally suggested by the WHO as the acceptable daily HCB (hexachlorobenzene) intake.相似文献
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Shibaprasad Sen Mridul Mitra Ankan Bhattacharyya Ram Sarkar Friedhelm Schwenker Kaushik Roy 《Neural Processing Letters》2019,50(3):2281-2304
Feature selection through optimization techniques provides an interesting approach to minimize computational time with enhanced prediction capability, and 相似文献
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加工技术与设备的发展通常会使加工时间缩短.但是新型助剂的应用也可减少加工时间,大大降低成本.随着iFlash系统的应用,漂白温度可降至80℃,活性染料染色后皂洗的时间也大大缩短.因此,织物间歇式染色得到优化,在不增加额外投资的情况下运行更经济. 相似文献
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Solution Structure and Constrained Molecular Dynamics Study of Vitamin B12 Conjugates of the Anorectic Peptide PYY(3–36)
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Dr. Kelly E. Henry Dr. Deborah J. Kerwood Dr. Damian G. Allis Jayme L. Workinger Ron L. Bonaccorso Prof. George G. Holz Prof. Christian L. Roth Prof. Jon Zubieta Prof. Robert P. Doyle 《ChemMedChem》2016,11(9):1015-1021
Vitamin B12–peptide conjugates have considerable therapeutic potential through improved pharmacokinetic and/or pharmacodynamic properties imparted on the peptide upon covalent attachment to vitamin B12 (B12). There remains a lack of structural studies investigating the effects of B12 conjugation on peptide secondary structure. Determining the solution structure of a B12–peptide conjugate or conjugates and measuring functions of the conjugate(s) at the target peptide receptor may offer considerable insight concerning the future design of fully optimized conjugates. This methodology is especially useful in tandem with constrained molecular dynamics (MD) studies, such that predictions may be made about conjugates not yet synthesized. Focusing on two B12 conjugates of the anorectic peptide PYY(3–36), one of which was previously demonstrated to have improved food intake reduction compared with PYY(3–36), we performed NMR structural analyses and used the information to conduct MD simulations. The study provides rare structural insight into vitamin B12 conjugates and validates the fact that B12 can be conjugated to a peptide without markedly affecting peptide secondary structure. 相似文献
8.
Andrey Frolov Kimberly Miller Jeffrey T. Billheimer Tae-Hyeon Cho Friedhelm Schroeder 《Lipids》1997,32(11):1201-1209
Although it was recently recognized that sterol carrier protein-2 (SCP-2) interacts with fatty acids, little is known regarding the specificity of SCP-2 for long-chain fatty acids or branched-chain fatty-acid-like molecules. Likewise the location of the fatty-acid binding site within SCP-2 is unresolved. A fluorescent cis-parinaric acid displacement assay was used to show that SCP-2 optimally interacted with 14–22 carbon chain lipidic molecules: polyunsaturated fatty acids > monounsaturated, saturated > branched-chain isoprenoids > branched-chain phytol-derived fatty acids. In contrast, the other major fatty-acid binding protein in liver, fatty-acid binding protein (L-FABP), displayed a much narrower carbon chain preference in general: polyunsaturated fatty acids > branched-chain phytol-derived fatty acids > 14- and 16-carbon saturated > branched-chain isoprenoids. However, both SCP-2 and l-FABP displayed a very similar unsaturated fatty-acid specificity profile. The presence and location of the SCP-2 lipid binding site were investigated by fluorescence energy transfer. The distance between the SCP-2 Trp50 and bound cis-parinaric acid was determined to be 40 Å. Thus, the SCP-2 fatty-acid binding site appeared to be located on the opposite side of the SCP-2 Trp50. These findings not only contribute to our understanding of the SCP-2 ligand binding site but also provide evidence suggesting a potential role for SCP-2 and/or L-FABP in metabolism of branched-chain fatty acids and isoprenoids. 相似文献
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Reaction-bonded Al2 O3 (RBAO) ceramics were fabricated starting from mechanically alloyed Al2 O3 /Al, Al2 O3 / Al/ZrO2 , and Al2 O3 /Al/ZrO2 /Zr mixtures. Isopressed compacts were heat-treated in air up to 1550°C. Reaction-bonding mechanisms, kinetics, and the influence of ZrO2 and Zr additions are investigated. Independent of additive, oxidation of Al proceeds both as solid/gas and liquid/gas reaction, and the reaction kinetics follow a parabolic rate law. The reaction rate depends strongly on the particle size of Al. The activation energy of the reaction depends essentially on green density. Below the melting temperature of Al, in samples containing 45 vol% Al and 55 vol% Al2 O3 , it is 112 and 152 kJ/mol at ∼64% and ∼74% TD, respectively, while above the melting temperature, it lies in the range ∼ 26–33 kJ/mol. Zr additions reduce the activation energy to some extent. Samples with only ZrO2 additions exhibit nearly the same activation energies as ZrO2 -free samples, though ZrO2 has a very positive effect on the microstructural development in RBAO ceramics. Microstructure evolution and some strength data of RBAO bodies are also reported. 相似文献
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