Filling hemodialysis catheters in the interdialytic period: heparin versus citrate versus polygeline: a prospective randomized study

Heparin and saline are commonly used to fill hemodialysis central venous catheters to prevent their thrombosis during the interdialytic period. The purpose of this prospective clinical study was to evaluate whether replacing heparin with citrate or polygeline could ensure satisfactory catheter function without exposing patients to the risk of systemic heparinization. Thirty end-stage renal disease (ESRD) patients with subclavian or jugular single lumen catheters as temporary vascular access for hemodialysis were enrolled. After the insertion of the catheters, the patients were randomly assigned to one of the following three filling groups: Group A, heparin; Group B, citrate; Group C, polygeline. Before each dialysis, the filling solution was aspirated and clot volume, if present, was measured. The catheter usage time and the clot volume were 23 +/- 24 days and 0.052 +/- 0.035 ml in Group A, 51 +/- 36 days and 0.059 +/- 0.032 ml in Group B, and 32 +/- 10 days and 0.056 +/- 0.038 ml in Group C, respectively. Our results indicate that citrate or polygeline can replace heparin effectively as a filling solution for single lumen temporary hemodialysis catheters.     

Effect of silver nanoparticles on the microstructure and mechanical properties of alumina ceramics

In this work, the effect of additions of silver nanoparticles on the microstructure and mechanical properties of alumina-based ceramic was studied. The processing method for the manufacturing of alumina/silver composites imply high energy mechanical milling in a planetary type mill, cold uniaxial compaction and pressureless sintering in an inert atmosphere at 1500°C for 2?h. From the results after the milling step, approximately 45% of the powders have a particle size less than 1?μm. The microstructure observed by SEM is very fine and homogenous; the presence of silver apparently inhibits the grain growth of the alumina. With respect to mechanical properties, increases of the silver content in the matrix causes decrease of Young’s modulus and flexural strength of the composite obtained in 1.5 and 4.6%, respectively. On the other hand, the presence of silver greatly enhances the fracture toughness of alumina, from an increase of 4.2?MPa?m^?0.5 for monolithic alumina to 10?MPa?m^?0.5 for alumina with silver additions of 2?wt- %, representing an improvement of 138% in toughness of alumina. Lastly, hardness for this same sample was incremented in 12%.     

Hyperbaric oxygenation, plasma exchange, and hemodialysis for treatment of acute liver failure in a 3-year-old child

A girl aged 3 years and 4 months weighing 16 kg was treated with plasma exchange (PE), hemodialysis (HD), and hyperbaric oxygenation (HBO) for acute hepatic failure and coma. She was given a total of 13 PEs, 13 HD sessions, and 9 HBO treatments over a period of 1 month. The initial 4 PEs were followed by HD sessions while the other 8 PE treatments were given simultaneously with HD. There was no renal failure; HD was instituted to improve ammonia elimination. In 1 HD session, 20% human albumin (370 ml) was used as the dialysate to enhance bilirubin elimination. Three volumes of plasma (2,000 ml) per PE were exchanged and replaced with fresh frozen plasma (FFP). The Bellco BL 791 plasmapheresis monitor and Gambro PF1000 and PF2000 plasma filters were used. Heparin was added to prevent clotting. A dual lumen pediatric HD catheter (7 Fr) placed percutaneously into the femoral vein was used as a blood access. The Fresenius 2008 C HD monitor and the Filtral 10 dialyzer were used for HD. PE and HD were instituted simultaneously to prevent the tetanic (hypocalcemic) cramps observed with 2 previous PEs due to citrate in the FFP. The extracorporeal circuit was primed with a mixture of concentrated red cells, human albumin, and saline solution and was discarded at the end of the procedure. The average blood flow rate in PE and/or HD circuits was 80 ml/min. During HBO, the girl breathed 100% oxygen at 2.5 atm for 90 min. Throughout the treatment, the patient was in good clinical, physical, and mental condition, but she was dependent on blood purification procedures. She was referred to a liver transplant center and successfully transplanted. The etiology of liver failure has not been clarified.     

Investigation of the Y<Subscript>2</Subscript>O<Subscript>3</Subscript> distribution in the weld joints of dispersion-hardened steel cladding of fast-reactor fuel elements

The results of investigations of the yttrium oxide distribution in the weld joints of dispersion-hardened steel cladding, manufactured by the powder metallurgy method, are presented. It is shown that when using the methods of fusing welding of thin-walled fuel-element cladding, the content and uniformity of the yttrium oxide distribution in the metal of a seam changes as compared with the cladding metal. The concentration and uniformity of the yttrium oxide distribution in the section of a weld joint obtained by pulsed laser welding is higher than that obtained with argon-arc welding. __________ Translated from Atomnaya énergiya, Vol. 102, No. 6, pp. 348–351, June, 2007.     

Technological special features of fusion welding thin-wall shells from aluminium alloys with remote control

The results of processing the data on high-speed recording of tracks of plasma heated particles of Al₂O₃, Ti and Mo are used to determine the local and mean (in the cross section) values of the speed and temperature of the particles, and also the variation of the speed of these particles along the axis of the plasma jet in relation to different technological parameters of an experimental plasma torch. These data are then used to select the optimum spraying conditions in which the particles collide with the substrate surface in the molten state, and the fields of the speeds and temperature of the particles are homogeneous.     

Nano-Materials and Composition on the Basis of Cobalt Nano-Particles and Fine Humic Acids as Stimulators of New Generation Growth

The aim of the investigations is to study growth stimulators increasing crop yield and quality, for example the sunflower. Nano-cobalt, humic acids in nano-dispersed state and their combination have been chosen as stimulators. The work has taken place both in the lab and in the field. Field emergence, leaf-area duration, the plants＇ height and mass in different phases of vegetation, the yield and chemical composition of the sunflower seeds have been determined when meteorology of 2013. The seeds have been treated with stimulators having the concentration from 0.01 to 10.0 g per hectare, and in the field conditions with that of 0.5 g/ha, 1.0 g/ha, 5.0 g/ha. In a case with nano-cobalt the field emergence has increased per 11.6%,in a case with humic acids, 11.2% higher than that of the control. The case with these substances complex has increased the datum per 17.8%. Cobalt nano-particles have increased the green material per 19%, the humic acids, per 22% and their combination, per 30%. The yield increase in a case with different stimulators has been 24%, 19%, 31% correspondingly. The protein increase in a case with the combination ofhumic acids and cobalt nano-particles has comprised 7.24%. This research is important for understanding the mechanism of action nanostructures in biologycal objects.     

Production and properties of Al2O3 layers on silicon substrates

A method for preparation of thin Al2O3 films using pyrolytic reactions is proposed and some electrical and optical properties of the films are investigated. The applicability of the films as an active dielectric in m.o.s. structures is discussed.     

Changes in the picture of chronic diseases on long-term hemodialysis treatment

New data published in the literature provided evidence for appearance of an unknown variant of amyloidosis recorded in patients with a 5-15-year history of hemodialysis. Such amyloidosis may result from high blood levels of beta-2-microglobulin unremovable at standard hemodialysis. Even highly permeable membranes which permit beta-2-microglobulin penetration fail to produce negative balance of this metabolite as the procedure stimulates leukocyte activity and, consequently, beta-2-microglobulin production. In spite of the fact that contact of the blood with synthetic materials during hemodialysis is not longer than 3-5 hours, blood elements and endothelial cell metabolism, homeostasis undergo serious alterations. These effects of biocompatibility provoke the condition of enhanced activation similar to chronic inflammation. Thus, we deal with a new phenomenon in the field of hemodialysis. The efforts of investigators should be aimed at studying long-term adaptation of the body which rings atypical picture of chronic diseases.     

A study of deadlock models for a multiservice medium accessprotocol employing a slotted Aloha signalling channel

Medium access protocols for HFC and wireless ATM networks often use a collision based capacity request signalling channel which may rely on the slotted Aloha multiaccess principle. This paper studies the performance of a p-persistence slotted Aloha contention resolution algorithm (CRA), subject to extreme interstation correlation, by means of a discrete-time Markov chain analysis. We examine in detail the conditions leading to a deadlock-a situation where the time to collision resolution becomes unacceptably high and the system is practically unstable. We analyze two disaster scenario deadlock models, and study the effect of channel error probability, signalling traffic load, and the contention resolution algorithm used. We show that the key factor of the CRA is the collision rate and not channel errors. We propose and test three signalling channel capacity allocation schemes. We identify the best-performing of these three schemes as the cyclic contention mini-slot (CMS) sharing employing multiple CMSs per data slot. Finally, we demonstrate the need for implementation of an added scheme, which dynamically adjusts the p-persistence parameter