Theoretical evaluation of the shape of the deformation zone in the press piercing mill

An analysis of metal deformation in the press piercing mill is presented in the paper. Interpenetration of the groove surface and billet surface was the base of the theoretical solution. Bulging of the material in front of the deformation zone was taken into consideration. The analysis resulted in the determination of strains within the deformation zone. Equations which describe the billet surface were derived and the contact interface was determined.     

Extended exact least-weight truss layouts—Part II: Unsymmetric cantilevers

In Part I of this study, the optimal bar layout and adjoint displacement fields were derived for cantilever trusses that are symmetric about a horizontal axis. In this paper, the above results are generalized to unsymmetric trusses and a number of further extensions to other support and load conditions are outlined briefly. Most results are verified by comparisons with discretized optimal layouts of trusses and perforated plates.     

Model for tensile fracture of concrete at high rates of loading

Mechanisms of tensile fracture of concrete are described. A model is developed for an idealized material. The amount of simultaneous cracking and the path of each crack depend on the rate of stressing. The fracture energy and the tensile strength have been determined as functions of the rate of loading. The results of earlier experiments on concrete under impact tensile loading can be explained by this model.     

Shape optimization of a dynamically loaded machine foundation coupled to a semi-infinite inelastic medium

A numerical model of the shape optimization of a rectangular machine foundation embedded in soil when subjected to external dynamic forces and moments is presented. A sequential programming method with move limits is used to obtain the minimum weight (mass) of the block. Numerical examples are given to illustrate the application of the model which takes 3-D dynamic soil-foundation interaction into account.Presented at The First World Congress of Structural and Multidisciplinary Optimization (held in Goslar, Germany, May 28–June, 2, 1995)     

Cellular immunity in patients with non-specific inflammatory bowel disease for an extended period after surgery

The study was aimed at investigating the expression of HLA-DR, CD4, CD8, CD56 surface antigens on peripheral blood lymphocytes in patients with non-specific inflammatory bowel diseases in the period of 1-5 years after the surgical procedure. The percentage of rosette forming T-cells in the theophylline test and skin reaction to mycotic and bacterial antigens were assessed simultaneously. The experiment included group of 12 patients (aged 5-55), treated surgically because of Crohn's disease or ulcerative colitis. The lymphocytes' surface antigens were examined by means of monoclonal antibodies and the APAAP procedure. Significantly increased (p < 0.001) percentage of lymphocytes with HLA-DR surface antigens and significantly decreased (p < 0.002) percentage of lymphocytes with CD8 surface antigens were observed in patients with non-specific inflammatory bowel diseases. In 6 of 12 patients the skin test results were negative. The clinical symptoms, which may suggest the maintaining inflammation of the intestinal mucosa were found in 50% of patients examined after surgical procedure because of Crohn's disease. The results suggest there are significant disturbances of cellular immunoreactivity parameters in patients with non-specific inflammatory bowel diseases. It may be one of the causes, which maintain the chronic inflammation of the intestinal mucosa and favour disease recurrence. The cellular immunoreactivity disturbances demonstrated in this study may be the result of the still persisting intestinal mucosa. Inflammation, in spite of deficiency of synonymous clinical symptoms indicating the disease recurrence.     

Molecular genetic analysis of DNA structure of pFra plasmids in plague pathogen of varying biovar]

OBJECTIVE: To clarify the mechanism of the suppressive effect of 2-buten-4-olide (2-B4O), an endogenous feeding suppressant, on the pulsatile secretion of luteinizing hormone (LH), by studying whether endogenous opioid peptides are involved in this suppressive effect. METHODS: Using ovariectomized (ovx) rats, blood samples were taken every 6 min for 2 h after administration of 2-B4O or saline into the third cerebroventricle (3V) and sequential i.v. injection of naloxone (0. 5 mg/kg per h) or saline. Rats were divided into three experimental groups: group 1: 3V saline + i.v. saline (control); group 2: 3V 2-B4O + i.v. saline; group 3: 3V 2-B4O + i.v. naloxone. Serum LH concentrations were determined by double-antibody RIA. To determine whether 2-B4O affected the biosynthetic activity of the opioidergic neurons within the ovx rat arcuate nucleus, we measured the concentrations of pro-opiomelanocortin (POMC) mRNA, a precursor of beta-endorphin, in the rostral arcuate nucleus using non-radioactive in situ hybridization and a computerized image-analysis system. RESULTS: 2-B4O significantly suppressed the pulse frequency of LH (group 2: 1.5+/-0.33 pulses/2 h, group 1: 2.43+/-0.2 pulses/2 h; P < 0.05), but naloxone blocked its suppressive effect and restored the pulse frequency (group 3: 3.29+/-0.36 pulses/2 h, group 2: 1.5+/-0.33 pulses/2 h: P < 0.01). There were no significant changes in the mean LH concentrations and amplitude. Furthermore, 2-B4O significantly stimulated the expression of POMC mRNA in the rostral arcuate nucleus. CONCLUSION: These results suggest that 2-B4O may impair the pulsatile secretion of LH by activating the opioid pathway within the hypothalamus.     

Conformational investigation of alpha,beta-dehydropeptides. IX. N-Acetyl-(E)-alpha,beta-methylamide: stereoelectronic properties from infrared and theoretical studies

BACKGROUND: Basal folds are slender plications at the basal surface of acinar cells in the salivary glands of many mammalian species. These largely organelle-free folds increase the surface area of the basal plasmalemma manyfold and are unquestionably involved in the translocation of organic and inorganic molecules and water into the acinar cells. METHODS: Specimens of salivary glands were obtained from over 230 species of live-trapped bats from major areas of the globe. Tissues for electron microscopy were fixed and processed by conventional means. RESULTS: A number of the bat species examined had dense material in the intercellular spaces between basal and lateral folds of serous cells in the parotid gland. This intercellular material was particularly prominent in three species of New World bats, viz., Pteronotus parnellii, P quadridens, and Phyllostomus latifolius, and in one species of Old World bats, Chalinolobus argentatus. This dense material, which has a farinaceous texture, appears not to pass through tight junctions, so it is excluded from the lumina of intercellular canaliculi and acini. The dense material originates in the acinar cells--it is carried to the membranes of the folds via coated vesicles, which empty their dense content by exocytosis into the intercellular space. Similar dense material is present in the intercellular spaces of the basal labyrinth of striated ducts in the two species of Pteronotus. The manner in which this material accumulates in the striated duct is unclear. CONCLUSIONS: Although the function of the intracellular dense material is undetermined, it appears to be placed strategically to influence molecular traffic into acinar cells or to modulate the paracellular pathway. From a comparative evolutionary perspective, we hypothesize that, in bats, the combination of basal folds and extracellular densities is associated with insectivory. Similar morphologies appear to be lacking in frugivorous or nectarivorous species.