Safety and efficacy of hydrogen peroxide plasma sterilization for repeated use of electrophysiology catheters

OBJECTIVES: The purpose of this study was to evaluate a new technique for sterilizing nonlumen electrophysiology catheters that uses hydrogen peroxide gas plasma. BACKGROUND: The reuse of electrophysiology catheters may potentially result in a significant cost savings. While ethylene oxide sterilization appears to be safe and effective from a clinical standpoint, toxic ethylene oxide residuals, which exceed Food and Drug Administration standards, have been reported. METHODS: Ten nonlumen electrophysiology catheters were extensively evaluated. Each catheter was used five times and resterilized after each use with hydrogen peroxide gas plasma. Tests for sterility, mechanical and electrical integrity, chemical residuals and standard and electron microscopic inspection were performed. RESULTS: Loss of electrical integrity or mechanical integrity was not observed in any catheter. No evidence of microbial contamination was found. Surface integrity was preserved except for one ablation catheter that exhibited fraying of the insulation at the insulation-electrode interface. Surface inspection using standard magnification and electron microscopy revealed no significant change in surface characteristics associated with the sterilization process. Hydrogen peroxide was the only chemical residual noted, with an average concentration of 0.22% by weight, which is within accepted American Association for the Advancement of Medical Instrumentation limits. The cost for a standard electrophysiology catheter ranges from $200 to $800, and one sterilization cycle costs $10. If electrophysiology catheters are used five times, resterilization could potentially result in a savings of $2,000 per catheter, or $9,000 for five ablation procedures. CONCLUSIONS: Hydrogen peroxide gas plasma sterilization may provide a cost-effective means of sterilizing nonlumen electrophysiology catheters without the problem of potentially harmful chemical residuals. However, careful visual inspection of catheters, particularly at the insulation-electrode interface, is required if catheter reuse is performed.     

Hydrogen peroxide gas plasma sterilization is effective against Cryptosporidium parvum oocysts

Moyamoya disease is an occlusive intracranial arteriopathy with abnormal cerebral vascular collateral networks. Although this disease is known to be associated with stenosis of extracranial arteries, such as the renal artery, a case associated with stenoses of the coronary and renal arteries has not been reported. We described here a 23-year-old man who had effort angina, renovascular hypertension, and asymptomatic moyamoya disease. Arterioangiography revealed bilateral occlusion of the intracranial carotid arteries and stenoses in the left coronary artery and the left renal artery.     

Direct reduction of iron in low temperature hydrogen plasma

Abstract

This paper describes the effects of various parameters on the reduction of hematite in the presence of microwave assisted non-thermal hydrogen plasma. The parameters include microwave power, hydrogen flowrate, pressure, microwave power density and temperature. It has been shown that hydrogen flowrate, pressure and microwave power are interrelated to effect the microwave power density that controls the plasma temperature. The experimental conditions encounter three temperatures: surrounding the sample, associated with the plasma and at the plasma/substrate interface. It has been deduced that the third one is the most effective in determining the rate of the reaction, and in the present case, activation energy of 20 kJ mol^?1 is reported.     

Efficacy of a one-step hydrogen peroxide system for disinfection of soft contact lenses

Ten N/cm torque has been proposed as the optimum level for the tightening of implant retaining gold screws in order to preload the implant components to limit loosening and fracture. The purpose of this study was to determine the influence of instrumentation and operator experience on the torque generated during manual tightening of slotted gold screws. Sixteen subjects, divided into four groups based on experience, were instructed to tighten five screws into implant analogs with 20-mm and 37-mm slotted screwdrivers. The screws were then removed with a torque gauge. All of the groups of subjects were able to generate significantly greater torque with the 37-mm screwdriver. Dentists with no implant treatment experience generated significantly less torque than the other three groups. Of the 12 dentist subjects, only 3 generated the optimal amount of torque when using the 20-mm screwdriver. Operators who had little experience dealing with implant prostheses were not able to provide the recommended torque and experienced operators tended to generate more than the recommended amount. None of the subjects were able to generate consistent torque values.     

Dissolution of hydrogen from the gas in steel at room temperature

The purpose of this paper is to show that embrittlement of steel deformed in a hydrogen atmosphere is caused by hydrogen entering the crystal lattice. Tensile tests are made under pure compressed hydrogen gas. It is shown that the hydrogen penetrates steel before any fissures develop. The penetration depends on the time of exposure of fresh surface produced by straining but does not depend directly on the strain rate. The hydrogen distribution vs depth was measured. It agrees with a transient distribution calculated with an apparent solubility (1 cu cm per 100 g at 150 kp per sq cm) and an apparent diffusivity (1.3·10^?7 sq cm per sec).     

The diffusivity of hydrogen in the noble metals at low temperature

An electrolytic method has been used to measure the diffusivity of hydrogen in the noble metals Pt, Au, and Ag in the low-temperature range 280–330 K. The data obtained have been considered in conjunction with those for other noble metals (Pd and Cu) in order to draw conclusions concerning the interactions between dissolved H-atoms and lattice vacancies. It has been concluded that, at least in Pd, Cu, and Au, the H-vacancy interaction energy is too low to render diffusion anomalies observable at high temperatures. This is in accord with theoretical calculations based on the effective medium technique.     

小高炉顶温偏低问题的分析

沙钢9号500m3级小高炉2014年顶温平均为130℃,低时只有102℃。干法布袋除尘高炉顶温的合理区间为120～250℃,因此9号炉顶温偏下限。经分析,目前操作条件下风温、燃料比对顶温影响明显。高炉热负荷对顶温影响较大,适当发展中心气流、减弱边缘气流有利于降低冷却强度、提高顶温。但是9号炉常用布料矩阵的粒度偏析较严重,不利于发展中心气流。通过适当增大40mm以上大粒度焦炭所占比例,降低焦炭反应性,以及适当增加焦丁用量等可以发展中心气流,提高顶温。     

Effect of stress on hydrogen solubility and the low temperature deformation characteristics in vanadium containing hydrogen

The effect of applied stress near the yield stress on the dissolution temperature of hydrides in vanadium has been investigated by transmission electron microscopy (TEM) and by resistivity measurements.

• 1.(1) The dissolution temperature of hydrides in thin foil TEM specimens increases by 5 (0.036at.%) to 16 K (0.5 at.%) by the external tensile stress.
• 2.(2) In wire specimens, the change in the dissolution temperature by the external stress is within the accuracy of experiments (~ 1 K).

Although the estimate by the conventional theory is in apparent agreement with the resistivity result on wire specimens, it is suggested that the TEM result on thin foil specimens should be regarded as better representing the effect of the external stress. In order to clarify the role of hydrides in the mechanical strength at low-temperatures, the elastic limit and the resistivity of wire specimens have been measured simultaneously. It is concluded that the hardening is due to hydrogen clustering along moving dislocations.     

过氧化氢-甲基橙动力学光度法测定亚硝酸根

研究了硫酸介质中,痕量亚硝酸根催化过氧化氢氧化甲基橙褪色反应及其动力学条件,建立了动力学光度法测定亚硝酸根的简便方法。在25mL溶液中亚硝酸根测定的线性范围为0～0.8μg,方法的检出限为6.55×10-9g/mL。测定1×10-8g/mLNO-4,Cr3+,F-,Cl-;2,以相对于NO-2量的倍数计,1000倍的Na+,K+,Mg2+,Ca2+;500倍的Pb2+,Al3+,NH+100倍的Ni2+,I-,Zn2+,Cd2+,Mo(Ⅵ),Fe3+和20倍的Cu2+不干扰。方法已用于自来水、雨水和池塘水     

effects of hydrogen on low temperature hardening and embrittlement of V-Cr alloys

The effects of H on the strength and ductility of V-Cr alloys were investigated from 78 to 300 K. Alloy softening which was observed at low temperatures for a V-2.5Cr alloy was mitigated by the addition of H. Hydrogen embrittlement, as measured by reduction of area, was observed in both hydride forming and nonhydride forming alloys. Analysis of the strengthening in hydrogenated V-Cr alloys showed that the predominate effect of H was to increase the thermally activated component of the yield stress. Comparison of the solid solution hardening effect caused by Cr or Ti in V showed that Ti produces greater strengthening, atom for atom, than does Cr, but that the difference cannot be explained solely by larger size and modulus misfits of solute and solvent atoms.     

Accommodation effects during room temperature hydrogen transformations in the niobium-hydrogen system

The free energy loss has been theoretically evaluated in the model NbH system at 313 K for the solid solution → monohydride and monohydride → dihydride transformations. The origin for this hysteresis loss has been explained by considering the elasto-plastic accommodation processes that occur in the NbH system during these hydrogen transformations. The calculated free energy loss for the solid solution → monohydride transformation shows excellent agreement with experimental results. Possible sources of error in the calculations have been elucidated. The present elasto-plastic approach is compared with previous theories of hysteresis. It is found that the elasto-plastic accommodation theory offers the best explanation for the hysteresis phenomenon observed in metal-hydrogen systems.     

Particle melting in high temperature supersonic low pressure plasma jets

A numerical model has been developed to predict the temperature history of particles injected into a low pressure dc plasma jet. The temperature and velocity fields of the plasma jet are predicted as a free jet by solving the parabolized compressible Navier-Stokes equations using a spatial marching scheme. Particle trajectories and heat transfer characteristics are calculated using the predicted plasma jet temperature and velocity fields. Correction factors have been introduced to take into account noncontinuum effects encountered in the low pressure environment. The exchange of energy and momentum between the injected particles and plasma flow was treated by considering the source terms in the governing equations. The plasma jet profiles as well as the particle/plasma interactions with different jet pressure ratios (from underexpanded to overexpanded) have been investigated. The effect of particle loading on the resulting jet profiles, particle trajectories, and temperature profiles is presented and discussed. This paper is based on a presentation made in the T.B. King Memorial Symposium on “Physical Chemistry in Metals Processing” presented at the Annual Meeting of The Metallurgical Society, Denver, CO, February, 1987, under the auspices of the Physical Chemistry Committee and the PTD/ISS.     

Continuous precipitation of uranium with hydrogen peroxide

Three different continuous processes were developed for the recovery of uranium from sulfate-containing simulated mill solutions. In all cases, a high-quality product, low in molybdenum and vanadium, which could be filtered and dried easily, was obtained. The presence of sulfate slows the precipitation rate and results in larger precipitated particles, which is an advantage in filtering and drying the precipitate. The morphologies of the large particles produced in the processes described in this report suggest that crystal growth predominated over nucleation in the precipitator. At 60 °C, the uranium peroxide precipitated as the dihydrate, but below 50 °C to 60 °C, the tetrahydrate was formed, and this knowledge led to important conclusions regarding the rate of the precipitation. A variety of particle morphologies was found, the most unusual being spherulitic aggregates consisting of needles radiating from a common point at the center of the particle. Formerly Senior Engineer and Professor, Ames Laboratory and Department of Chemical Engineering, respectively, Iowa State University, is deceased.     

A low temperature flotation method to rapidly isolate lipoproteins from plasma

To minimize oxidative modification, a low temperature, sequential flotation method was developed to isolate plasma lipoproteins in 18 h using a benchtop ultracentrifuge. The protein distributions were characterized using agarose and SDS-polyacrylamide gel electrophoresis, and an SDS-Lowry protein assay. The lipid distributions were assessed using a gas chromatography-mass spectrometric assay for cholesterol and an enzymatic assay for triglycerides. To validate the rapid flotation method, lipoproteins were also isolated from the same plasma samples using a modified Havel et al. flotation method (J. Clin. Invest. 34: 1345-1353, 1955). The same lipoproteins and apolipoproteins were present in fractions of comparable density, and the summed recoveries of protein, cholesterol, and triglyceride were also identical for the Havel et al. and rapid flotation procedures. Likewise, the amount of cholesterol and triglyceride in corresponding very low, intermediate, and low density lipoprotein (VLDL/IDL and LDL) fractions was the same for the two flotation procedures. The triglyceride and cholesterol levels in high density lipoprotein (HDL) isolated by rapid flotations, however, were 9-12% higher than in the HDL as isolated by Havel et al. Because a 9-12% increase in the HDL fraction reflects only 1-4% of the total triglyceride and cholesterol in plasma, we conclude that, while maintained at 4 degrees C, lipoproteins were quantitatively isolated from human plasma in 1 day.