Application and modelling of flow forming manufacturing processes for internally geared wheels

The production of internally geared wheels by flow forming is a new process developed at the PtU Darmstadt. The technology enables manufacturing in one-piece design without additional machining operation. In this process, an externally geared mandrel is fitted into a cup-like work piece. By reducing the cup's outside diameter, the inner wall of the cup is rolled into the mandrel's teeth, thereby producing the gear's profile. Three tooling concepts with different kinematics and numbers of rolls were analyzed using experimental methods. Numerical analyses revealed several shortcomings of available finite-element codes to handle complex flow forming processes. The first step of an efficient computation is the development of a parameterized process model. This is able to act as a starting basis for a virtual product and process design.     

Behavior of the lipid and carbohydrate metabolism in patients with hypertriglyceridemia during exertion

In pateints with hypertriglyceridaemia in rest and during ergometer load an increased rate of lipolysis with increased metabolism of free fatty acids could be proved. This led to a disturbance of the glucose tolerance with hyperinsulinism and during muscle work to a limitation of the capacity of the oxidative glucose metabolism in musculature.     

Determination of anthropogenic input of Ru, Rh, Pd, Re, Os, Ir and Pt in soils along Austrian motorways by isotope dilution ICP-MS

A joint study with the Federal Environment Agency of Austria was carried out to determine the distribution of Ru, Rh, Pd, Os, Ir and Pt (PGE) and Re in soils along major motorways. Emphasis was put on Ir as to date little is known about its anthropogenic input as this metal is now also used in automobile catalytic converters. Soil samples were analysed by ICP-MS through online-coupling of a chromatographic column to separate the PGEs from interfering matrix constituents. At all sampled sites not only Rh, Pd and Pt but also Ir and Re significantly exceed natural background values; concentrations reached 13 ng/g, 25 ng/g, 134 ng/g, 1.1 ng/g and 9.8 ng/g, respectively. The analytical procedure proved to be very selective and sensitive and, therefore applicable to routine soil analysis.     

Morning to evening changes of intramyocellular lipid content in dependence on nutrition and physical activity during one single day: a volume selective 1H-MRS study

Object  

Intramyocellular lipids (IMCL) were shown to be metabolically highly active. In order to get insight into short-term regulation of IMCL and to reveal related problems with standardization in metabolic studies using the common signal ratio IMCL/Cr3, relative concentration changes from morning to evening in the same day were examined under four different nutritional and exercise conditions.     

Hydrogeochemische Hintergrundwerte der Grundw?sser Deutschlands als Web Map Service

One of the main objectives of the EC water framework directive is to ensure good chemical status for all groundwater bodies. For this reason the geological surveys of Germany have produced a nationwide map of the background values of groundwater. Only naturally occurring inorganic parameters were taken into account, including the relevant major and trace elements. Based on the hydrogeological map of Germany at the scale of 1:200,000 (HüK 200), and its delimited hydrogeological regions, a total of 186 hydrogeochemical units were defined and mapped geochemically. This involved collection of more than 52,000 groundwater samples in a database and allocation to their appropriate hydrogeochemical units. In order to separate anomalies within the data-sets from the underlying normal population, probability nets were used as a statistical tool. The procedure allowed to determine the normal populations of the investigated parameters within the hydrogeochemical units and to quantify them in the form of percentiles. The resulting hydrogeochemical background values are accessible through an internet web map service that includes an online map application. The main intention of this technical note is to inform the reader about the existing internet service, which necessitates some web-site content duplication.     

Effect of hypoglycemia on beta-adrenergic sensitivity in normal and type 1 diabetic subjects

OBJECTIVE: The purpose of this study was to assess the potential role of reduced tissue sensitivity to catecholamines in the pathogenesis of hypoglycemia unawareness in patients with type 1 diabetes. RESEARCH DESIGN AND METHODS: The effect of a single episode of hypoglycemia on beta-adrenergic sensitivity was studied in 10 type 1 diabetic patients with apparently normal awareness of hypoglycemia (age 29 +/- 5 years, diabetes duration 13 +/- 8 years, HbA1c 7.3 +/- 0.9%) and 10 age-matched healthy control subjects. Beta-adrenergic sensitivity was measured with the isoproterenol test after a hyperinsulinemic euglycemic clamp and after a hyperinsulinemic hypoglycemic clamp. Beta-adrenergic sensitivity was expressed as the dose of intravenous isoproterenol that increased the heart rate by 25 beats/min (IC25). RESULTS: During hypoglycemia, diabetic subjects had an impaired plasma epinephrine response compared with that of the control subjects (16.7 +/- 5.0 vs. 40.1 +/- 6.8 ng/ml, P = 0.02). In control subjects, the IC25 was lower after hypoglycemia than after euglycemia (0.83 +/- 0.22 vs. 1.13 +/- 0.21 microg, P = 0.02) indicating an increase in beta-adrenergic sensitivity. In diabetic subjects, on the other hand, the IC25 was greater after hypoglycemia than after euglycemia (1.00 +/- 0.26 vs. 0.65 +/- 0.14 microg, P = 0.04), indicating a decrease in beta-adrenergic sensitivity. CONCLUSIONS: In normal subjects, a single episode of hypoglycemia increases beta-adrenergic sensitivity. In diabetic subjects, in contrast, hypoglycemia reduces beta-adrenergic sensitivity. These results provide evidence that in type 1 diabetic patients, some maladaptation of tissue sensitivity to catecholamines contributes to the development of hypoglycemia unawareness. A unifying hypothesis is presented for the pathogenesis of hypoglycemia unawareness in type 1 diabetic patients incorporating the concepts of both a reduced catecholamine response and reduced adrenergic sensitivity     

Modulation of eicosanoid production and cell-mediated cytotoxicity by dietary α-linolenic acid in BALB/c mice

The effects of dietary α-linolenic acid (18∶3n−3) on fatty acid composition, eicosanoid production, and cell-mediated cytotoxic activity of immune cells before and after challenge with virus or poly I-C from BALB/c mice were studied. Weanling BALB/c mice were fed purified diets containing either 10%-by-weight corn oil or linseed oil providing a ratio of 18∶3n−3 to 18∶2n−6 of 1/32 or 2/1, respectively, for 6–10 weeks. Fatty acid analysis of splenocyte phospholipids showed an appreciable increase in the percentage of n−3, and a decrease in n−6, fatty acids in splenocytes from mice fed the linseed oil diet. Splenocyte prostaglandin E and peritoneal exudate cell leukotriene C production was significantly lower in the linseed oilfed mice. In general, cell-mediated cytotoxic activity was similar for immune cells from linseed oil and corn oil-fed mice. However, 6 days after the viral challenge, splenocyte cell-mediated cytotoxic activity was significantly higher in linseed oil mice. This higher activity was associated with nonspecific cytotoxicity rather than that of viral-specific cytotoxic T-lymphocytes. Cell yields from the spleen and peritoneum were frequently significantly higher in linseed oil mice. Interactions between dietary 18∶3n−3, eicosanoid production, and immune cell proliferation and/or migration are discussed. In summary, feeding mice a diet rich in 18∶3n−3 elevates immune cell n−3 fatty acid content, reduces eicosanoid synthesis and, to a limited extent, enhances the cell-mediated cytotoxic response to a viral challenge. Part of a dissertation submitted by Kevin L. Fritsche in partial fulfillment of the requirements for the Ph.D. degree in Nutritional Sciences     

Association between the angiotensin-converting enzyme-insertion/deletion polymorphism and diabetic nephropathy: a methodologic appraisal and systematic review

Recent studies have implicated a variant of the angiotensin-converting enzyme gene (ACE), associated with increased activity of this enzyme, in the development and progression of diabetic nephropathy. This study provides a systematic review of all cross-sectional, case-control, and cohort studies in patients with insulin-dependent (IDDM) or non-insulin-dependent (NIDDM) diabetes mellitus of any race, examining the relationship between the ACE-insertion/deletion polymorphism and nephropathy. Nineteen studies in 21 populations published between 1994 and 1997 presenting data on 5336 patients were reviewed. Two investigators independently assessed the studies on methodologic quality, performance of study, and association between the ACE-insertion/deletion polymorphism and nephropathy. Separate analyses of the relationship between genotype and allele frequencies were performed for patients with IDDM and NIDDM by race, using Peto's odds ratio. In Caucasians with IDDM, pooling was not performed due to heterogeneity of the studies, but among the homogeneous studies, no association was detected. Likewise, no association was observed in Caucasian patients with NIDDM (odds ratio [OR], 1.10; 95% confidence interval [95% CI], 0.83 to 1.45). In Asian patients with NIDDM, the risk of nephropathy was increased in the presence of the DD or ID genotype (OR, 1.88; 95% CI, 1.42 to 2.85). Although this analysis fails to confirm an association between the ACE-insertion/deletion genotype and nephropathy in Caucasians with NIDDM or IDDM, a role for this genetic marker in Asian patients cannot be ruled out. However, due to methodologic limitations of individual studies, no definite conclusions can be drawn from this analysis. Clearly, more rigorous methodology needs to be applied in future studies.     

Screening of fungi for the biological modification of hard coal and coal derivatives

A biotechnological depolymerization of hard coal is being attempted with basidiomycetous fungi native to timber, plant residues, and soil, and with microfungi of lignite sources and contaminated soil. The coal materials such as powdered or hydrogenated hard coal (asphaltene) were aseptically exposed to fungal pure cultures in a four-step screening system. Agar surface cultures were examined for softening and erosion of the coal particles, and for alterations in the asphaltene films fixed to plastic chips and silica gel. From the shake cultures, both the culture fluid and the coal or asphaltene sediments were separately collected and processed by photospectrometry, gel permeation chromatography, combined gas chromatography-mass spectrometry, and IR spectrometry.

Of the 243 fungal strains tested to date, four were reactive on coal materials and asphaltene. Two basidiomycetes (Coriolus hirsutus [Wulf.] Quel.; Coprinus sclerotiger Watl.) eroded hard coal particles, while another basidiomycetous strain (Agrocybe semiorbicularis [Bull.:Fr.]) separated the asphaltene film from its plastic carrier. The hyphomycete Trichoderma spec. strain AB2 caused alterations in the IR spectrum of asphaltene.