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1.
The growing interest in the use of graphite as a material for chemical equipment is occasioned by the highly corrosion resistant properties of this low-cost material. Economic and safety specifications require a thorough knowledge of the material's properties and performance and also of the effect of these factors on a particular unit. It is to be considered for instance that the material's compressive strength is 3 to 5 times higher than its tensile strength. Another important characteristic is its static strength: the smaller the stressed volume, the higher the breaking strength. This comparatively good performance is of advantage in cases of high voltage gradients as encountered as edge stresses at the openings of tube plates and nozzles. In such cases the breaking strength may reach twice the value of the rupturing strength. A third characteristic to be mentioned is the high dependence of strength on the parameters of production; the strength decreases, for technological reasons, with increasing size. The following design principles are based on the specific properties and performance of the material:
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The active DC glow discharge sustained in pure oxygen has been studied in a Silica discharge tube by means of optical emission spectroscopy and double-probe diagnostics for pressures 600, 750 and 1000 Pa and for discharge currents up to 40 mA. Two different forms of positive column of the discharge (high-gradient H form and low-gradient T form) were observed. Our investigation was focused on the variations of the rotational temperature Trot determined from emission spectra of molecular oxygen (atmospheric A-band at 760 nm) in the dependence on the discharge current and on the pressure with respect to the existence of the two forms of the discharge. An increase of the rotational temperature with increasing discharge current has been observed. Moreover, higher values of Trot were found in the H form compared with the T form. 相似文献
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Hannelore T. Koller Torsten Klade Adolf Ellinger Michael Breitenbach 《Yeast (Chichester, England)》1996,12(1):53-65
We isolated the Saccharomyces cerevisiae GRC5 (gr owth control) gene by functional complementation in vivo of a ts (t emperature s ensitive) mutation. Phenotypic analysis suggested involvement of GRC5 in cell growth and proliferation. Mutant cells arrest their cell cycles after one to three cell divisions predominantly as mother cells with a large bud. In the region of the septum, a massive accumulation of cell wall material is observed. The mother and daughter nuclei are well separated and spindles are no longer present, while the cytoskeleton is of aberrant appearance. Arrested cells do not perform protein synthesis and are unable to mate. Furthermore, grc5-1ts cells rapidly lose viability at the restrictive temperature (37°C) only on full media, but not under nitrogen-starvation conditions, indicating that proper response to this nutrient limitation is still intact in mutant cells after cell cycle arrest. The sequence of GRC5 translates into a basic protein of 221 amino acids with a corresponding Mr of 25·4 kDa. GRC5 is a member of the highly conserved QM gene family, members of which have been reported from plants, invertebrates and vertebrates. The amino acid sequence of GRC5 over its entire length is more than 60% identical to the human QM protein, expression of which is associated with loss of the tumorigenic phenotype in a cell line derived from Wilms' tumor, a malignancy of the embyronic kidney. Here, we show that GRC5 is an essential yeast gene, the function of which as inferred from analysis of the grc5-1ts mutant is crucial for establishment of proper cytoskeletal structure and regulation of growth in yeast cells. 相似文献
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Napkin ring adhesion tests over a broad range of experimental conditions suggested a de-bonding mechanism for glassy thermosets associated with “run-away” nonlinear viscoelasticity. Finite element analyses of these tests using a high fidelity, nonlinear constitutive equation were used to identify a single, scalar metric that consistently predicted the initiation of de-bonding, a critical value of the maximum principal strain in the “interphase” zone. In principle, such a de-bonding metric enables evaluation of design margins in practical components. 相似文献
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Detlef Ulrich Adolf Rapp und Edelgard Hoberg 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1995,200(3):217-220
Zusammenfassung Die flüchtigen Aromakomponenten von dreizehn Kulturerdbeersorten und von Walderdbeeren wurden im Freon-Extrakt von frischen und gefrosteten Früchten untersucht. Mit Hilfe der GC/MS konnten etwa 120 flüchtige Verbindungen identifiziert werden. Über eine Aromaextrakt-Verdünnungsanalyse (AEVA) erfolgte mittels Schnüffeltechnik die Bestimmung der wesentlichen sensorischen Qualitäten, denen 17 Schlüsselverbindungen zugeordnet werden konnten. Die Analyse der Schlüsselverbindungen im Erdbeersortiment zeigt deutliche Sortenunterschiede.
Analysis of strawberry flavour — Quantification of the volatile components of varieties of cultivated and wild strawberries
The volatile components of thirteen strawberry varieties and of a wild strawberry were evaluated in the freon-extract of fresh and frozen fruits. With the aid of GC/MS about 120 volatile substances could be identified. The determination of the substantial sensory qualities resulted from AEDA with sniffing technique. In this way 17 key compounds could be attached. The analysis of the key compounds point out significient variety differences.相似文献
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Unter welchen Voraussetzungen bewähren sich Korrosionsschutzauskleidungen aus Fluorkunststoff-Folien
Under what conditions are anticorrosion liners made from fluorinated plastic film effective ? Equipment lined with fluorinated plastics is nowadays making a major contribution to the solution of difficult materials problems. If such equipment is to be used successfully, it is essential that its manufacturer is familiar with the specific properties of the lining materials and takes them into account in the design and production of the equipment. However, it is just as important for the operator to adjust to the material when operating the plant. On the basis of many years of experience, the most important problems associated with loose liners made from polytetrafluoroethylene (PTFE) – viz. leakproofness and permeability of the liner, flange system, dimensional stability towards vacuum, handling, and installation – are indicated and possible solutions stated. 相似文献
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Toussaint Adolf 《Bulletin of Engineering Geology and the Environment》1984,30(1):137-139
For highway construction and maintenance, between 200 and 300 million tons of mineral aggregates are used in the Federal Republic of Germany per year. Most of the regionally occurring rocks, gravels and sands are sources of road materials of very good quality. However, depending on the locale, aggregates of minor quality may also have to be used for highway construction and maintenance for economic reasons and in order to protect the environment by avoiding greater haulage distances. For this purpose it has been necessary to adapt aggregate treatment and pavement design techniques to the rock materials available in each case. A number of different tentative approaches to solving this problem have been put forward. 相似文献