Initial clinical experience with a new heparin-coated chronic hemodialysis catheter

In this paper we wish to report our clinical experience with a new heparin-coated dialysis catheter with a symmetric tip. Over a 16-month period, 60 heparin-coated Tal Palindrome^™ catheters were placed in 57 patients. Catheter patency, catheter-related complications, and reasons for catheter removal were recorded. The patient's initial cause of end-stage renal disease, underlying diseases, and site of access were recorded as well. Patients were specifically followed for development of heparin-induced thrombocytopenia. Patient ages were 34–91 (average 66). Fifty-four percent of patients had a history of diabetes. Sixty catheters were placed for a total of 5353 catheter-days. The average catheter indwell time was 107 days (range of 2–381 days). Catheter-related infection occurred in 6 patients over the study period, with a rate of 1.12/1000 catheter-days. Bacteremia occurred in 3 patients with a rate of 0.56/1000 catheter-days. Six catheters were removed or exchanged due to malfunction. There was no incidence of heparin-induced thrombocytopenia. Initial clinical experience with the heparin-coated Tal Palindrome^™ hemodialysis catheter demonstrated safe, reliable use, and low infection rates.     

Dynamic behavior analysis of drill-threading process when machining AISI Al-Si-Cu4 alloy

Conventional threading operations involve two distinct machining processes: drilling and threading. Therefore, it is time consuming for the tools must be changed and the workpiece has to be moved to another machine. This paper presents an analysis of the combined process (drilling followed by threading) using a single tool for both operations: the tap-milling tool. Before presenting the methodology used to evaluate this hybrid tool, the ODS (operating deflection shapes) basics is shortly described. ODS and finite element modeling (FEM) were used during this research to optimize the process aiming to achieve higher stable machining conditions and increasing the tool life. Both methods allowed the determination of the natural frequencies and displacements of the machining center and optimize the workpiece fixture system. The results showed that there is an excellent correlation between the dynamic stability of the machining center-tool holder and the tool life, avoiding a tool premature catastrophic failure. Nevertheless, evidence showed that the tool is very sensitive to work conditions. Undoubtedly, the use of ODS and FEM eliminate empiric decisions concerning the optimization of machining conditions and increase drastically the tool life. After the ODS and FEM studies, it was possible to optimize the process and work material fixture system and machine more than 30,000 threaded holes without reaching the tool life limit and catastrophic fail.     

Ochratoxin A in coffee beans (Coffea arabica L.) processed by dry and wet methods

The incidence of ochratoxin A was studied in different coffee (Coffea arabica L.) samples. A higher incidence of filamentous fungi was observed in the coffee swept from ground and floating coffee samples. The species Aspergillus ochraceus, Aspergillus sulphureus and Aspergillus sclerotiorum were ochratoxin A producing. In 128 (44%) samples ochratoxin A was not detected; however, in 89 samples (31%), ochratoxin A was detected at 0.1–5.0 μg/Kg levels. Other 25% samples presented contamination above 5.0 μg/Kg. This study showed that the fractions coffee swept from ground and floating coffee represents a serious risk of ochratoxin A contamination.     

Systemic or intrahippocampal delivery of histone deacetylase inhibitors facilitates fear extinction.

Several recent studies have shown that chromatin, the DNA-protein complex that packages genomic DNA, has an important function in learning and memory. Dynamic chromatin modification via histone deacetylase (HDAC) inhibitors and histone acetyltransferases may enhance hippocampal synaptic plasticity and hippocampus-dependent memory. Little is known about the effects of HDAC inhibitors on extinction, a learning process through which the ability of a previously conditioned stimulus, such as a conditioning context, to evoke a conditioned response is diminished. The authors demonstrate that administration of the HDAC inhibitors sodium butyrate (NaB) systemically or trichostatin A (TSA) intrahippocampally prior to a brief (3-min) contextual extinction session causes context-evoked fear to decrease to levels observed with a long (24-min) extinction session. These results suggest that HDAC inhibitors may enhance learning during extinction and are consistent with other studies demonstrating a role for the hippocampus in contextual extinction. Molecular and behavioral mechanisms through which this enhanced extinction effect may occur are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the construction of free algebras for equational systems

The purpose of this paper is threefold: to present a general abstract, yet practical, notion of equational system; to investigate and develop the finitary and transfinite construction of free algebras for equational systems; and to illustrate the use of equational systems as needed in modern applications.     

Optical monitoring of polypropylene crystallization during injection molding

The nonisothermal crystallization of polypropylene resins, i‐PP, during injection molding, using an optical device inserted in the injection mold cavity was monitored. The device detected the change of optical properties which occurs in polymers during their crystallization process; thus the intensity of a laser beam after it passed through the crystallizing polymer was measured during an injection molding cycle. The collected light intensity after the end of the cycle was correlated with the morphologies and final crystallinity degree of the samples. The influence of nucleating agents and the change of the parameters of the injection molding process on the morphology and optical signals were also investigated. The morphologies were analyzed by polarized light optical microscopy, PLOM. The % of crystallinity of the samples was measured by wide angle X‐rays diffraction, WAXS. It was concluded that the optical device was sensible to different polymer crystallization kinetics, morphology type, and changes in the injection molding parameters. It was also found that the mold temperature and packing pressure and time were the factors that affected most the kinetics of crystallization of these polymers in this particular disk geometry. The WAXS results showed that the lower the final light intensity the higher the % of crystallinity in the samples. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers     

Cryogenic operation of graded-channel silicon-on-insulator nMOSFETs for high performance analog applications

We present in this work an analysis of the low temperature operation of Graded-Channel fully depleted Silicon-On-Insulator (SOI) nMOSFETs for analog applications, in the range of 100-300 K. This analysis is supported by a comparison between the results obtained by two-dimensional numerical simulations and measurements in the whole temperature range under study. The Graded-Channel transistor presents higher Early voltage if compared to the conventional fully depleted SOI nMOSFET, without degrading the transconductance over drain current, at all studied temperatures, leading to a gain larger than 20 dB compared to the conventional SOI. The resulting higher gain lies in the improvement of the electric field distribution and impact ionization rate by the graded-channel structure.     

Surface hydrolysis of postconsumer polyethylene terephthalate to produce adsorbents for cationic contaminants

In this work, the surface hydrolysis of postconsumer polyethylene terephthalate (PET) was used to produce an ion exchange material to adsorb cationic contaminants from water. The PET surface hydrolyses were carried out in neutral, alkaline, and acid media (NaOH or HNO₃ at 7, 10, and 15 mol L^?1) under reflux producing surface carboxylic acid sites (? COOH) characterized by ATR‐IR, pyridine adsorption, titration, TG, and DSC analyses. Acid hydrolysis produced high concentrations of ? COOH (up to 0.5 mmol g^?1_PET), whereas no significant concentration of carboxylic acid sites was obtained by neutral and alkaline hydrolysis. SEM analyses suggest that the acid sites are likely located at the cracks and defects produced on the PET surface by acid hydrolysis. Neutral or alkaline hydrolysis produced a very regular and smooth PET surface with very low acid site concentrations. The adsorption isotherms of Cd⁺² as a model of heavy metal and the dye methylene blue as a model of large organic cationic molecules showed high adsorption capacities for the HNO₃‐hydrolyzed PET, whereas no adsorption takes place on the neutral‐ or alkaline‐hydrolyzed polymer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5284–5291, 2006     

Simulation of turbulent impinging jet into a cylindrical chamber with and without a porous layer at the bottom

Turbulent impinging jets on heated surfaces are widely used in industry to modify local heat transfer coefficients. The addition of a porous substrate covering the surface contributes to a better flow distribution, which favors many engineering applications. Motivated by this, this work shows numerical results for a turbulent impinging jet into a cylindrical enclosure with and without a porous layer at the bottom. The macroscopic time-averaged equations for mass and momentum are obtained based on a concept called double decomposition, which considers spatial deviations and temporal fluctuations of flow properties. Turbulence is handled with a macroscopic k–ε model, which uses the same set of equations for both the fluid layer and the porous matrix. The numerical technique employed is the control volume method in conjunction with a boundary-fitted coordinate system. One unique computational grid is used to compute the entire heterogeneous medium. The SIMPLE algorithm is applied to relax the system of algebraic equations. Results indicate that the permeability of the porous layer and the height of the fluid layer significantly affect the flow pattern. The effect of the porous layer thickness was less pronounced in affecting the flow behavior in the fluid layer.     

On a cellular division method for topology optimization

This paper concerns a comparative analysis of a novel biologically inspired method for topology optimization. The proposed methodology develops each individual topology according to a set of rules that regulate a ‘cellular division’ process. These rules are then evolved using a genetic algorithm to minimize objective functions while satisfying a set of constraints. The results reported in this work show that the methodology suits engineering design and represents an improvement over existing topology optimization methods based on evolutionary algorithms. Copyright © 2011 John Wiley & Sons, Ltd.