Effect of dialyzer reprocessing on glucose homeostasis

While dialyzer manufacturers only provide information about their products as a black box, this study aimed at optimizing dialyzer geometry by looking in detail at transport processes and fluid properties inside the dialyzer using numerical modeling. A three‐dimensional computer model of a single hollow fiber with its surrounding membrane and dialysate compartment was developed. Different equations govern blood and dialysate flow (Navier‐Stokes), radial filtration flow (Darcy), and solute transport (convection‐diffusion). Blood was modeled as a non‐ Newtonian fluid with a viscosity varying in radial and axial direction because of the influence of local hematocrit, diameter of the capillaries, and local shear rate. Dialysate flow was assumed as an incompressible, laminar Newtonian flow with a constant viscosity. The permeability characteristics of the asymmetrical polysulphone membrane were calculated from laboratory tests for forward and backfiltration. The influence of the oncotic pressure induced by the plasma proteins was implemented as well as the reduction of the overall permeability caused by the adhesion of a protein layer on the membrane. Urea (MW60) was used as a marker to simulate small molecule removal, while middle molecule transport was modeled using vitamin B12 (MW1355) and inulin (MW5200). The corresponding diffusion coefficients were determined by counting for the fluid and membrane characteristics. Fiber diameter and length were changed in a wide range for evaluation of solute removal efficiency. The presented model allowed us to investigate the impact of flow, hematocrit, and capillary dimensions on the presence and localization of backfiltration. Furthermore, mass transfer was found enhanced for increased fiber lengths and/or smaller diameters, most pronounced for the middle molecules compared to urea.     

A comparison of two Nextel 440 Fibre reinforced aluminium composites using acoustic emission

The acoustic emission (AE) response and mechanical behaviour of two Nextel 440 fibre reinforced aluminium composites were compared. The total cumulative AE events were found to occur in two regions. The first region occurred at smaller strains and had a large exponential rise in events for the reinforced 6061 composite and few events for the high purity aluminium matrix composite. The difference was attributed to the alloy constituents of the 6061 aluminium matrix. The events were attributed to a dislocation release mechanism that occurred prior to yielding of the matrix. In the second region of events in the reinforced 6061 composite the event rate was constant and continued to failure. The second region of events in the high purity aluminium (HPAL) composite had a steady increase in the event rate until a constant rate was reached prior to failure. The events in the reinforced HPAL composite were attributed to the fracturing of fibres and the associated plastic deformation of the matrix that accompanies fibre failure. Thus failure in the materials occurs due to the propagation of fracturing fibres. The propagation was rapid in the reinforced 6061 aluminium composite. The reinforced HPAL composite had a slower propagation due to the high ductility of the HPAL.     

Damping controller design for power system oscillations usingglobal signals

This paper describes a new power system stabilizer (PSS) design for damping power system oscillations focusing on interarea modes. The input to the PSS consists of two signals. The first signal is mainly to damp the local mode in the area where PSS is located using the generator rotor speed as an input signal. The second is an additional global signal for damping interarea modes. Two global signals are suggested; the tie-line active power and speed difference signals. The choice of PSS location, input signals and tuning is based on modal analysis and frequency response information. These two signals can also be used to enhance damping of interarea modes using SVC located in the middle of the transmission circuit connecting the two oscillating groups. The effectiveness and robustness of the new design are tested on a 19-generator system having characteristics and structure similar to the Western North American grid     

Detection of T lymphocytes and T lymphocyte subsets in lichen planus: in situ and in peripheral blood

BACKGROUND: Abnormal immune mechanisms are thought to be important in the pathogenesis of lichen planus (LP). This is a study to clarify the changes that occur in T lymphocytes and T lymphocyte subsets, both in situ and in peripheral blood. METHODS: A group of 100 patients with LP were included in this study. T lymphocytes and T lymphocyte subsets were detected in lesional skin by immunoperoxidase cell surface staining using monoclonal antibodies. Peripheral T lymphocytes and T lymphocyte subsets were also detected by indirect immunofluorescence using monoclonal antibodies. A group of 10 normal healthy subjects were used as controls. RESULTS: The study of the lesional T lymphocytes and T lymphocyte subsets demonstrated that helper T cells was the predominant subset in LP lesions in most of the patients. This predominance was evident irrespective of the duration of the disease and was more evident in late than in early lesions. The percentage of both total T lymphocytes and helper T cells in peripheral blood was decreased significantly in patients compared with controls. A significant decrease in helper T cells and the helper/cytotoxic T cell ratio was detected in patients with a longer duration of the disease. CONCLUSION: Activation of helper T lymphocytes that were found to be the predominant subsets in LP lesions may be responsible for epidermotropic cellular infiltrates leading to damage and destruction of epidermal cells.     

Bioequivalence study of two capsule formulations of omeprazole

Congestive heart failure is associated with high morbidity and mortality. Modification of neurohormonal activation by use of angiotensin converting enzyme inhibitors has been shown to decrease symptoms and prolong survival. More recent evidence has suggested that beta-adrenoceptor blocking agent therapy may be also beneficial in patients with congestive heart failure, possibly by down-regulating the activation of the adrenergic system. A large number of randomized trials of beta-adrenoceptor blocking agents in heart failure have been performed. These studies demonstrated improvement in symptoms of congestive heart failure, functional classification, and reduction in the number of patients requiring cardiac transplantation. beta-adrenoceptor blocking agents have not been shown to decrease mortality, however, the current trials have been too small to be conclusive in this regard.     

A tentative tracking model based on energy balance criteria

A tentative mathematical model is described for estimating the time required for tracking to occur in rotating wheel water-spray or dip tests on polymeric insulating materials. The model is based on the energy balance criterion. In the derivation of the model, the required time for tracking to occur is treated as a function of the geometrical dimensions, the thermal characteristics and the volume and surface conductivities of the specimen. It is also considered to be dependent upon the applied voltage, wheel speed as well as the time required for arcing to occur, the discharge activity and the number of dry bands formed upon the surface of the specimen. The validity of the model is assessed, using experimental data obtained with epoxy fibre glass composite specimens; reasonable agreement is found between the experimental results and the calculated values     

Effect of marinating process on the microbiological quality of Pacific saury (Cololabis saira) during vacuum-packaged storage at 4 °C

This study was carried out to evaluate the microbiological quality of Pacific saury ( Cololabis saira ) treated with marinating solutions containing either 12% NaCl + 2% acetic acid or 12% NaCl + 3% acetic acid, followed by vacuum packaging and storage at 4 °C for 90 days. The fish-to-marinating-solution ratio was 1:1.5. The growth rate of aerobic, halophilic, lactic acid bacteria and Pseudomonas spp. were significantly ( P  < 0.05) reduced in marinated vs. brined (12% NaCl + 0% acetic acid) fillets. Complete inhibition in the growth of both Enterobacteriaceae and Staphylococcus aureus was detected in fillets marinated in 3% and 2% acetic acid by the days 30 and 50 of storage, respectively. Both marinating conditions resulted in shelf life extension of the product to more than 90 vs. 60 days only for the brined fillets. Listeria monocytogenes , Vibrio parahaemolyticus and Salmonella spp. could not be detected in any of the analysed raw or treated samples.     

Antimicrobial and antioxidant effects of sodium acetate, sodium lactate, and sodium citrate in refrigerated sliced salmon

This study was carried out to evaluate the microbiological quality and lipid oxidation of fresh salmon slices treated by dipping in 2.5% (w/v) aqueous solution of sodium acetate (NaA), sodium lactate (NaL), or sodium citrate (NaC) and stored at 1 degrees C. The results revealed that these salts were efficient (P < 0.05) against the proliferation of various categories of spoilage microorganisms; including aerobic and psychrotrophic populations, Pseudomonas spp., H(2)S-producing bacteria, lactic acid bacteria, and Enterobacteriaceae. The general order of antibacterial activity of the different organic salts used was; sodium acetate > sodium lactate > sodium citrate. Lipid oxidation, as expressed by peroxide value (PV) and thiobarbituric acid (TBA) value, was significantly (P < 0.05) delayed in NaA- and NaC-treated samples. The antioxidant activity followed the order: NaC > NaA > NaL. The shelf life of the treated products was extended by 4-7 days more than that of the control. Therefore, sodium acetate, sodium lactate, and sodium citrate can be utilized as safe organic preservatives for fish under refrigerated storage.     

Delamination buckling of cylindrical laminates

Models for predicting delamination buckling of laminated complete thin cylindrical shells and cylindrical panels are presented. The load cases are uniform axial compression and uniform pressure, applied individually. The models are different for the two load cases and by design they are kept as simple as possible, to keep the mathematical representation of the model and the associated solution simple enough to permit extensive parametric studies. Through these studies one can identify important structural parameters and fully assess their effect on the critical load. Among the general conclusions are the following: (a) the most influential parameters for a given laminated geometry are the size of the delamination and its through-the-thickness position for both load cases; and (b) the effect of boundary conditions (along the straight edges) is important for the case of pressure, whereas for axial compression the effect of boundary conditions (ends) is small for large delaminations.     

Mode II stress intensity factors for central slant cracks with frictional surfaces in uniaxially compressed plates

The effect of crack surface friction on mode II stress intensity factor (SIF) of a central slant crack in a plate uniformly loaded in uniaxial compression is quantified. A previously developed two-dimensional finite element analysis was utilised after its modification to accommodate the friction between the crack surfaces. The plane strain state was assumed. A new numerical technique was devised to avoid the iteration procedures, which had to be employed due to the existence of frictional forces.

The crack inclination angle varied between zero and 75° measured from the horizontal direction. The coefficient of friction of the crack surfaces changed from zero to 1. In case of relatively sliding crack surfaces, mode II SIF existed. As is well known, the resulting mode II SIF decreased with increasing the coefficient of friction of the crack surfaces. Further, mode II SIF increased with increasing crack line inclination angle and then decreased after reaching a maximum value. The angle corresponding to that maximum SIF increased as the coefficient of friction of the crack surfaces increased.