Copper matrix composites reinforced with volcanic tuff

This paper presents a manufacturing method, properties and possible use of copper matrix composites reinforced with particles of volcanic tuff. The composites were obtained by powder metallurgy and reinforced with Filipowice tuff mined near Cracow, Poland. The influence of tuff particles content on the properties of the copper matrix composites such as conductivity, durability and microstructure was assessed. Tuff was introduced into a copper matrix in an amount of 5, 15 and 30 % by volume. The composites were used to prepare the nozzle tips of resistance welding electrodes, and initial tests were performed of the behavior and stability of the materials during the welding process of steel sheet

Enhancement of Blackbody Friction due to the Finite Lifetime of Atomic Levels

The thermal friction force acting on an atom moving relative to a thermal photon bath is known to be proportional to an integral over the imaginary part of the frequency-dependent atomic (dipole) polarizability. Using a numerical approach, we find that blackbody friction on atoms either in dilute environments or in hot ovens is larger than previously thought by orders of magnitude. This enhancement is due to far off-resonant driving of transitions by low-frequency thermal radiation. At typical temperatures, the blackbody radiation maximum lies far below the atomic transition wavelengths. Surprisingly, due to the finite lifetime of atomic levels, which gives rise to Lorentzian line profiles, far off-resonant excitation leads to the dominant contribution to the blackbody friction.Comment: 4 pages; RevTe

Elastic and inelastic SU(3)-breaking final-state interactions in B decays to pseudoscalar mesons

We discuss all contributions from Zweig-rule-satisfying SU(3)-breaking final state interactions (FSIs)in the B -> PP decays (neglecting charmed intermediate states), where PP=pi pi, pi K, KK, pi eta (eta'), and K eta (eta'). First, effects of SU(3) breaking in rescattering through Pomeron exchange are studied. Then, after making a plausible assumption concerning the pattern of SU(3) breaking in non-Pomeron FSIs, we give general formulas for how the latter modify short-distance (SD) amplitudes. In the SU(3) limit, these formulas depend on three effective parameters characterizing the strength of all non-Pomeron rescattering effects. We point out that the experimental bounds on the B -> K^+K^- branching ratio may limit the value of only one of these FSI parameters. Thus, the smallness of the B -> K^+K^- decay rate does not imply negligible rescattering effects in other decays. Assuming a vanishing value of this parameter, we perform various fits to the available B -> PP branching ratios. The fits determine the quark-diagram SD amplitudes, the two remaining FSI parameters and the weak angle gamma. While the set of all B -> PP branching ratios is well described with gamma around its expected SM value, the fits permit other values of gamma as well. For a couple of such good fits, we predict asymmetries for the B -> K pi, pi^+ eta (eta'), K^+ eta (eta') decays as well as the values of the CP-violating parameters S_{pi pi} and C_{pi pi} for the time-dependent rate of B^0(t) -> pi^+ pi^-. Apart from a problem with the recent B^+ -> pi^+ eta asymmetry measurement, comparison with the data seems to favour the values of gamma in accordance with SM expectations.Comment: 27 pages, 5 figure

Mild therapeutic hypothermia after out-of-hospital cardiac arrest: What does really matter?

Background: Mild therapeutic hypothermia (MTH) is a recommended treatment of comatose patients after out-of-hospital cardiac arrest (OHCA). The aim of the study was to examine determinants of clinical outcome in OHCA survivors treated with MTH and variables associated with MTH induction time.Methods: Presented herein is an analysis of combined results from a retrospective and a prospective observational study which included 90 OHCA survivors treated with MTH from January 2010 to March 2018. Multivariate regression analysis was performed to determine variables associated with poor neurologic outcome (Cerebral Performance Category 3–5), mortality, and prolonged induction time.Results: At hospital discharge, 59 (65.6%) patients were alive, of whom 36 (61%) had a good neurologic outcome. Older patients (odds ratio [OR] 1.07, 95% confidence interval [CI] 1.03–1.12) with lower Glasgow Coma Scale (GCS) (OR 0.49, 95% CI 0.30–0.80) were at higher risk of poor neurological outcome. The predictors of in-hospital death included: older age (OR 1.08, 95% CI 1.02–1.13), lower GCS score (OR 0.47, 95% CI 0.25–0.85), presence of cardiogenic shock (OR 3.43, 95% CI 1.11–10.53), and higher doses of adrenaline (OR 1.27, 95% CI 1.04–1.56). Longer induction was associated with shorter cardio-pulmonary resuscitation (CPR) (unstandardized coefficient –3.95, 95% CI –7.09 to –0.81) and lower lactate level (unstandardized coefficient –18.55, 95% CI –36.10 to –1.01).Conclusions: Unfavorable neurologic outcome in OHCA patients treated with MTH is associated with age and lower GCS score. Risk factors for in-hospital mortality include age, high-dose adrenaline administration, lower GCS score and presence of cardiogenic shock. CPR duration and lactate level were predictive of prolonged MTH induction time

Comparison of temperature measurements in esophagus and urinary bladder in comatose patients after cardiac arrest undergoing mild therapeutic hypothermia

Background: Mild therapeutic hypothermia (MTH) is a recommended method of treatment for comatose out-of-hospital cardiac arrest (OHCA) survivors. However, the proper site of temperature measurement in MTH is still not defined. The aim of this study was to compare temperature measurements in the esophagus and urinary bladder in comatose post-OHCA patients treated with MTH.Methods: This temperature comparison protocol was a part of a prospective, observational, multicenter cohort study. The study population included 36 unconscious patients after resuscitation for OHCA. The patient’s core temperature was independently measured every hour during MTH in the urinary bladder and in the esophagus.Results: The mean temperature was lower in the esophagus (differences during induction phase: 1.04 ± 0.92°C, p < 0.0001; stabilization phase: 0.54 ± 0.39°C, p < 0.0001; rewarming phase: 0.40 ± 0.47°C, p < 0.0001). Nevertheless, a strong correlation between both sites was found (R2 = 0.83, p < 0.001). The decrease in temperature observed in the esophagus during the induction phase was faster when compared with the urinary bladder (1.09 ± 0.71°C/h vs. 0.83 ± 0.41°C/h; p = 0.002). As a consequence, time to reach temperature < 34.0°C was longer when temperature was measured in the urinary bladder (the difference between medians of the time 1.0 [0–1.5] h, p < 0.001).Conclusions: Urinary bladder temperature measurements may lag behind temperature changes measured in the esophagus. Monitoring temperature simultaneously in the esophagus and in the urinary bladder is an accessible and reliable combination, although esophageal measurements seem to better reflect the dynamics of temperature changes, thus it seems to be more appropriate for MTH control. ClinicalTrials.gov Identifier: NCT0261193

a comparative study of mechanical properties of fly ash based geopolymer made by casted and 3d printing methods

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The 42nd Symposium Chromatographic Methods of Investigating Organic Compounds : Book of abstracts

The 42nd Symposium Chromatographic Methods of Investigating Organic Compounds : Book of abstracts. June 4-7, 2019, Szczyrk, Polan

Volcanic ceramics in sintered metal matrix composites - microstructure research

This paper describes metal matrix composites reinforced with particles and with dispersion, and presents the most important materials used as a reinforcement of the metal matrix. A new material, called volcanic tuff, that could be used as a strengthening of metal composites has been characterized. The methods of producing metal matrix composites, reinforced of volcanic tuff have been presented. The matrix was made of such materials like copper, iron and stainless steel 316L. The paper presents the microstructure of sintered metal composites with varying degrees of tuff participation. The volume of tuff composites was 5, 15 and 30%. The results of X-ray microanalysis of connections of tuff particles with matrix have also been shown. The results have shown that a suitable tuff processing method and inserting it in an optimal amount results in improvement of some properties of the material such as, softening temperature or porosity. This is shown in the example of copper and tuff composites. Tuff is a material that could be used for reinforcement of metal composites. It has been shown A very good connection of metal matrix and tuff particles has been shown. At the border tuff - metal matrix there were no discontinuities. By using powder metallurgy technology, it is possible to obtain a uniform distribution of ceramic particles in the metal

Evaluation of products after alkaline activation of metakaolin and halloysite by SEM study

The paper presents a brief description of clay materials such as kaolinite and halloysite. In order to improve their sorption properties their properties and methods of activation are presented. The results of alkaline activation of two minerals: metakaolin and halloysite are shown. Alkaline activation process is performed with different parameters. The paper presents the results of the morphology obtained by the synthesis of the materials and the results of their chemical composition. As a result of the processes of alkaline activation of tested materials different phases in chemical composition and morphology were obtained. The best results were obtained for metakaolin with activation with a solution of 10M, for halloysite with activation of 5M solution. The results testify to obtain fraction of zeolite in the materials tested

Alkaline activation of ash and slags from waste incineration plants

The paper concerns testing and treatment of post-process waste from waste incineration plants with alkaline activation. The paper presents research results on ash and slag from thermal waste treatment processes, which were exposed to alkaline solutions. The results of the research of waste which solidified by geopolymerization and the research results of the hydrothermal activation in order to obtain the zeolites, are presented. For ash and slag treated with geopolymerization we present the results of compressive strength and selected results of leaching. For the waste which were treated with hydrothermal synthesis, we present the particle morphology (SEM) of the obtained zeolites. The research confirmed the possibility of immobilization of ash and slag in geopolymers and the possibility of obtaining zeolites from certain types of waste generated in waste incineration plants