Right intra-atrial catheter placement for hemodialysis in patients with multiple venous failure

The purpose of this study is to evaluate the efficacy and safety of direct right atrial catheter insertion for hemodialysis in patients with multiple venous access failure. We retrospectively evaluated the charts of 27 patients with multiple venous access failure who had intra-atrial dialysis catheter placement between October 2005 and October 2010 in our clinic. Permanent right atrial dialysis catheters were placed through a right anterior mini-thoracotomy under intratracheal general anesthesia in all patients. Demographics of the cases, the patency rates of hemodialysis via atrial catheterization, existence of any catheter thrombosis, and catheter-related infections were documented and used in statistical analysis. Seventeen women (63%) and 10 men (37%) with the mean age of 59.0 ± 7.1 years (47-71) were enrolled in this study. Chronic renal failure was diagnosed for the mean of 78.9 ± 24.3 months (33-130). Five patients (18.5%) died. Ventricular fibrillation and myocardial infarction were the causes of death in the early postoperative period in two patients. Two of the remaining three patients died because of cerebrovascular events, and one patient died because of an unknown cause. Ten patients (37%) had been using anticoagulate agents (warfarin) because of concomitant disorders such as deep vein thrombosis, operated valve disease, and arrhythmias. Catheter thrombosis and malfunction was determined in three cases (11.1%). Intra-atrial hemodialysis catheterization is a safe and effective life-saving measure for the patients with multiple venous failure and without any possibility of peritoneal dialysis or renal transplantation.     

Atomic layer deposition (ALD) of nanoscale coatings on SrAl2O4-based phosphor powders to prevent aqueous degradation

The aqueous degradation of Eu²⁺-activated and Dy³⁺-codoped strontium aluminate (SrAl₂O₄:Eu²⁺, Dy³⁺, SA2-Green) long afterglow phosphors synthesized from solid-state reaction and coated with nanoscale metal oxide protective layers (≤12 nm) via atomic layer deposition (ALD) is investigated. Uncoated phosphor powders degrade rapidly upon water immersion and lose their green phosphorescence within 48 hours of water exposure. Postmortem investigations reveal hydration and decomposition of the SrAl₂O₄ phase. ALD of ~10 nm Al₂O₃ or ~12 nm TiO₂ is found to significantly improve the powder's resistance to aqueous degradation. All ALD-coated powders show minimal structural and chemical degradation and retain phosphoresence after 48 hours of water immersion. This enhanced durability offers a new pathway for applying long afterglow phosphors to outdoor applications like roadway markings or safety signage and for their incorporation into more eco-friendly waterborne coatings.     

CAD techniques for microwave circuits

In little more than 10 years computer-aided design (CAD) of microwave circuits has moved from dumb terminals on mainframe computers to PCs, and now to powerful RISC workstations. Commercial CAD software now integrates the various stages of microwave circuit design: schematic capture, simulation and layout. This paper reviews the different CAD packages that are available for microwave circuit design. The basic principles employed in the modelling of microstrip circuits are introduced and the reasons for the extensive use of frequency-domain simulations are explored. The developments in nonlinear, electromagnetic and system-level simulation methods are described     

CAD techniques for the electromagnetic design of monolithic millimetre-wave integrated circuits

It is well known that mm-waves have an important role to play in the rapid expansion of mobile and personal communications, mmic technology is an important factor since it can provide a means of mass producing the user terminal rf subsystems. Millimetre-wave integrated circuits do not yet however offer the high packing density and functionality which is now possible for lower frequency applications where lumped elements are used. This problem is influenced most of all by the extreme modelling difficulties encountered at frequencies above 30 GHz. This paper reviews the current state-of-the-art for cad techniques used in mmic design. It describes some limitations of the standard Smarttm library approach and looks at the application of commercial electromagnetic simulators in the design of both microstrip and cpw circuits.     

Enhancement of Curie temperature and photoluminescent properties of Nd2Mo2O7, Ho2Mo2O7, and Gd2Mo2O7

For Nd_1.90Er_0.10Mo₂O₇, Ho_1.90Er_0.10Mo₂O₇, and Gd_1.98Eu_0.02Mo₂O₇ nominal compositions, oxide compounds were prepared by solid-state reaction method. X-ray diffraction measurements show that molybdenum oxides formed cubic phase except for Nd_1.90Er_0.10Mo₂O₇. Scanning electron microscopy was used to observe their microstructure and elemental analysis. The photoluminescence properties of the materials, the excitation and emission spectra and the decay curve, were investigated using photoluminescence spectrophotometer. Dielectric and piezoelectric properties of the ptoluminescent materials, the dielectric constant, dielectric loss, piezoelectric constant, and Curie temperature, were measured for electrical characterization. Nd_1.90Er_0.10Mo₂O₇, Ho_1.90Er_0.10Mo₂O₇, and Gd_1.98Eu_0.02Mo₂O₇ materials show both photoluminescence and piezoelectric properties.     

Effect of Al/Sr ratio on the luminescence properties of SrAl2O4:Eu2+, Dy3+ phosphors

Recent studies have brought out many phosphors like Eu²⁺, Dy³⁺-doped alkaline earth aluminates. The trivalent Dy³⁺ ions as co-dopants greatly enhance the duration and intensity of persistent luminescence. These phosphors show excellent properties, such as high quantum efficiency, long persistence of phosphorescence, good stability and suitable color emission.In this work the effect of Al/Sr ratio on the afterglow and phosphorescence decay properties of Eu²⁺ and Dy³⁺ co-activated strontium aluminates synthesized by a solid-state process has been investigated. The luminescence properties of samples were investigated by means of excitation spectra, emission spectra and X-ray diffraction analysis.A variety of strontium aluminates, such as SrAl₂O₄, Sr₄Al₂O₇, Sr₃Al₂O₆, Sr₃Al₂(Eu, Dy, Y)O_7.5, Al₅(Eu, Dy, Y)O₁₂, Sr₄Al₁₄O₂₅, SrAl₁₂O₁₉ and (Eu, Dy, Y)AlO₃ have been identified in the samples prepared from starting precursors with Al/Sr mole ratios ranging from 0.44 to 5. The afterglow decay rate was found to be the fastest for sample with Al/Sr ratio of 4.18, in which SrAl₄O₇ phase was dominant. The afterglow decay rate for phosphor with Al/Sr ratio of 2, in which SrAl₂O₄ phase was dominant, was detected to be slow. Moreover, the emission spectra of the samples shift to yellow-green long wavelength from bluish-green-ultraviolet short wave with the increase of Al/Sr ratios resulting from the change in the composition.     

Biohydrogen production by extracted fermentation from sugar beet

In the study, the production of biohydrogen by extracted fermentation from sugar beet was evaluated. Effects of initial amount of sugar beet, biomass and particle size of sugar beet on biohydrogen formation were investigated. The hydrogen (H₂) gas was predicted to be 78.6 mL at initial dry weight of sugar beet 24.6 g L^?1 and H₂ yield was calculated as 81.9 mLH₂ g^?1TOC while biomass concentration (1 g L^?1) and particle size (0.3 cm) were constant. The peak H₂ gas volume was predicted to be 139.9 mL at the low particle size of 0.1 cm. Hydrogen gas production potential was predicted as 143.6 mL h^?1. The peak value of 197.9 mLH₂ g^?1TOC was obtained with particle size of 0.1 cm when dry weight of sugar beet and initial amount of biomass was kept constant at 24.6 g L^?1 and 1 g L^?1, respectively.