Evaluation of braze materials used for automotive liquid hydrogen tanks with special respect to hydrogen embrittlement and low temperature toughness

Copper (CU 104 and CW021A), Nickel (NI 102 and MBF51) and Silver (AG102) braze joints with stainless steel 1.4401/1.4404 were investigated with respect to hydrogen embrittlement and cryogenic toughness. CW021A and MBF51 with different braze thicknesses and temperatures were Charpy V tested at 20 °C and ‐196 °C. Neither the seam thickness nor the test temperature had a significant influence on the Charpy V toughness. All toughness values were below 15 J/cm². The reason is the low thickness of the braze seam and therefore the low volume of deformable material. CU 104, CW021A, NI 102, MBF51 and AG102 braze joints were tensile tested in hydrogen of different pressures and temperatures. Neither of the soldering showed any kind of hydrogen embrittlement.     

Electrode processes during Fe-Pt electrodeposition studied by electrochemical quartz crystal microbalance

An electrochemical quartz crystal microbalance study has been performed in order to understand the alloy electrodeposition process and especially the mechanism of oxygen incorporation during Fe-Pt electrodeposition. It reveals that the presence of Pt leads to an enhanced hydrogen evolution reaction. In comparison to the single metal depositions, an additional current and an anomalous mass increase are observed when depositing from the complete electrolyte. The corresponding films exhibit a high O content and a needle-like morphology. These characteristics are altered by nitrogen gas stirring. Fe hydroxide formation due to a pH rise at the cathode and underpotential deposition of Fe deposition due to Fe-Pt alloy formation are discussed to interpret the results.     

The role of isochorismate hydroxymutase genes entC and menF in enterobactin and menaquinone biosynthesis in Escherichia coli

PURPOSE: At a time both when late complications and second malignancies have become a growing concern and when staging laparotomy has been largely abandoned and comparative studies for staging Hodgkin's disease by state of the art computed tomography (CT) vs. lymphangiography have revealed minimal differences in results for these procedures, our purpose for undertaking this study was twofold. Our initial reason was to determine and compare probabilities for negative abdominal findings for patients with Stage I presentations with those for patients with Stage II as determined by lymphangiography and subsequently by laparotomy for those patients who had negative lymphangiograms. Our second reason, being an extension of the first, was to create a resource that can be used in conjunction with other information for arriving at appropriate treatment decisions including giving either more or particularly less than standard institutional therapy and especially with respect to the abdomen. METHODS AND MATERIALS: Data on 714 patients with prelymphangiogram Stage I-II upper torso presentations of Hodgkin's disease were entered prospectively in our database between 1968 and 1987. Twenty-eight with lymphocyte predominant disease, who had both negative lymphangiogram and negative laparotomy findings and 17 with questionable diagnoses of lymphocyte-depleted or unclassified disease were excluded from subsequent analyses of 669 patients with nodular sclerosis (NS) and mixed cellularity (MC) diagnoses. RESULTS: Stage I: in final logistic models, negative lymphangiogram findings were associated strongly with a combination of no constitutional symptoms and nodular sclerosis histology, whereas negative laparotomy findings correlated strongly with a combination of no constitutional symptoms and female sex. Predicted probabilities depended on the ratios of favorable to unfavorable characteristics. Stage II: in final logistic models, negative lymphangiogram findings were associated strongly with a combination of no constitutional symptoms, nodular sclerosis histology, age <40 years, and <4 involved sites, whereas negative laparotomy findings correlated strongly with a combination of <4 involved sites and mediastinal disease. Predicted probabilities again depended on the ratios of favorable to unfavorable characteristics. CONCLUSION: This study demonstrated that probabilities for negative abdominal findings for patients with supradiaphragmatic presentations of NS and MC Hodgkin's disease depended on: 1) whether the disease presented as Stage I or as Stage II; 2) whether staging was limited to a lymphangiogram or whether it included a laparotomy; and 3) or whether the clinical features associated with the presenting stage and methods of staging were favorable or unfavorable.     

Efficient p-type Si IMPATT diodes for V-band frequencies

p-type single-drift IMPATT diodes for V-band frequencies were fabricated by a single diffusion process. The diodes were packaged on a copper heatsink using quartz standoffs and investigated in a resonant cap waveguide structure. The maximum CW output power is 0.5 at 68 GHz with an efficiency of 8.7%     

Penicillium commune, P. camembertii, the origin of white cheese moulds, and the production of cyclopiazonic acid

The taxonomy of Penicillia producing the mycotoxin cyclopiazonic acid, including isolates classified as Penicillium aurantiogriseum and P. puberulum, is reviewed on the basis of morphology, physiology, mycotoxin production and isoenzyme profiles. It is concluded that P. puberulum, as neotypified by Pitt in his 1979 monograph, is a synonym of P. aurantiogriseum. The correct name for saprophytic Penicillia producing cyclopiazonic acid is P. commune with P. palitans as a synonym. The moulds used in the manufacture of white cheeses, which are all classified in P. camembertii, and which also produce cyclopiazonic acid, are domesticated fungi derived from P. commune.     

Pseudodeficiency of arylsulphatase A: strategy for clarification of genotype in families of subjects with low ASA activity and neurological symptoms

A benign deficiency (pseudodeficiency) of the lysosomal enzyme arylsulphatase A (ASA) (EC 3.1.6.8) towards synthetic substrates complicates the diagnosis of metachromatic leukodystrophy (MLD). The pseudodeficiency is due to a single base substitution in the 3'-untranslated region of the ASA gene (1524+95 A-->G) and it has been reported that this mutation (PD2) always occurs on a chromosome carrying a second mutation in the ASA gene (PD1), which abolishes an N-glycosylation site (N350S). Analysis of the two PD mutations in the ASA gene separately was carried out in a large group of subjects with neurological symptoms and low ASA activity, including close relatives and MLD patients. The relationship between ASA enzyme activity and the different genotypes identified is presented. Evidence for the existence of an allele containing the PD2 mutation alone is presented. A strategy for cases with low ASA activity and neurological symptoms in families carrying a PD allele or both PD and MLD alleles is proposed.     

Mykotoxine in Fleischwaren

Zusammenfassung Die bei Fleischwaren vorkommenden Schimmelpilze, es handelt sich dabei vor allem um Vertreter der GattungenPenicillium undAspergillus, können erwünscht oder unerwünscht sein.Die bei der Reifung von Fleischwaren, z. B. Rohwurst nach ungarischer oder italienischer Art, eingesetzten Penicillien bildeten auf dem Substrat Fleisch keine chemisch erfaßbaren Mykotoxine, während in künstlichen Nährsubstraten Penicillinsäure, Ochratoxin A, Tremortin A, Citrinin und Patulin nachweisbar waren. Bei Anwendung des Hühnerembryotests ist jedoch bei zahlreichen Stämmen, bei denen mit chemisch-analytischen Methoden eine Toxinbildung nicht nachweisbar war, eine deutliche Toxicität beobachtet worden. Daher sollten als Starterkulturen für schimmelpilzgereifte Fleischwaren nur toxikologisch geprüftePenicillium-Stämme Verwendung finden.Schimmelpilze, die während einer Lagerung ohne Kühlung bei Fleischwaren mit einem relativ hohen Abtrocknungsgrad auftreten, sind häufig Vertreter der GattungAspergillus, die ebenfalls zahlreiche toxinogene Arten umfaßt.A. flavus undA. parasiticus bildeten in experimentell beimpften Fleischwaren große Mengen von Aflatoxinen, allerdings kommen diese Schimmelpilz-Arten bei Fleisch und Fleischwaren nur relativ selten vor. Ebenso konnte das vonA. versicolor gebildete Mykotoxin Sterigmatocystin von beimpften Fleischwaren isoliert werden. Folglich muß man mit zulässigen Methoden unerwünschtes Schimmelpilzwachstum auf Fleischwaren möglichst verhindern.

---

Myeotoxins in meats

Summary Molds occurring on meats predominantly represent the generaPenicillium andAspergillus. Some of these molds are desirable, others are undesirable.Penicillia isolated from mold fermented meats, such as Hungarian or Italian type salami, produced no mycotoxins in meats, but penicillic acid, ochratoxin A, tremortin A, citrinin, and patulin were detectable in YES broth. However, with the chick embryo test many penicillia strains proved toxic which produced no chemically defined mycotoxins in broth culture. Therefore, as starter cultures for mold fermented meats penicillic strains only should be employed, which have been tested toxicologically.Molds which are of importance for the spoilage of meats stored without refrigeration are frequently aspergilli.Aspergillus flavus andA. parasiticus may produce large amounts of aflatoxins in meats, however these species rarely occur on these products. Sterigmatocystin which is produced byA. versicolor, a mold quite frequently recovered from meats, was detected in fermented sausages inoculated with toxinogennc strains. Therefore, mold growth on meat products during storage should be avoided by permitted means.

     

FM noise measurement of w-band impatt diodes with a quasi-optical direct detection system

A simple and accurate method for determining the FM noise of negative-resistance regenerative oscillators in the microwave region is the so-called direct detection system, where the FM-AM noise conversion is achieved with a discriminator, usually a high Q-factor cavity. With increasing oscillator frequency (above 30 GHz), however, it becomes increasingly difficult to obtain reliable discriminators with high Q-factors. This difficulty can be overcome by applying high-quality quasi-optical resonators for the FM-AM noise conversion.     

Fabrication and measurement of optics for the laser interferometer gravitational wave observatory

The manufacture and testing of high-precision optical surfaces for the Laser Interferometer Gravitational Wave Observatory is described. Through the use of carefully shaped polishing laps made of a nondeformable polymer material coated on a rigid base, surfaces 250 mm in diameter with radii of curvature between 7 and 15 km were polished to an accuracy of several hundred meters in the curvature and with low values of waviness and microroughness. Metrology instrumentation used to measure the optical finish included a large-aperture digital interferometer calibrated to nanometer-level accuracy for measurements of curvature, astigmatism, and waviness and an interference microscope for measurements of microroughness. The power spectra of the data from both instruments were in good agreement.     

Recycling of solution spaces in multipreconditioned FETI methods applied to structural dynamics

This article presents a new method to recycle the solution space of an adaptive multipreconditioned finite element tearing and interconnecting algorithm in the case where the same operator is solved for multiple right‐hand sides like in linear structural dynamics. It accelerates the computation from the second time step on by applying a coarse space that is generated from Ritz approximations of local eigenproblems, using the solution space of the first time step. These eigenproblems are known to provide very efficient coarse spaces but must usually be solved a priori at high computational cost. Their Ritz approximations are much smaller and less expensive to solve. Recycling methods based on Ritz approximations of global eigenproblems have been published for classical finite element tearing and interconnecting algorithms, but their efficient application to multipreconditioned variants is not possible. This article also presents the application of a simpler recycling procedure, which reuses plain solution spaces, to adaptive multipreconditioned finite element tearing and interconnecting. Numerical results of the application of the presented methods to four test cases are shown. The new Ritz approximation method leads to coarse spaces, which turn out to be as efficient as those obtained from solving the unreduced eigenproblems. It is the most efficient recycling method currently available for multipreconditioned dual domain decomposition techniques.