Fatigue strength improvement of AISI E52100 bearing steel by induction heating and repeated quenching

Martensitic high carbon high strength AISI E52100 steel (JIS SUJ2) is one of the main alloys used in rolling contact applications when high wear and fatigue resistance are required. In this work, repeated induction heating and quenching of AISI E52100 is proposed and the refinement of the martensite structure and consequently improvement of the fatigue properties measured by rotating bending fatigue tests of steel parts is reported.Високовуглецеву високоміцну мартенситну сталь AISI E52100 (JIS SUJ2) найчастіше використовують за умов контактного кочення, де необхідні підвищені зносотривкість та втомна міцність. Запропоновано методи повторного індукційного нагріву та гартування сталі, внаслідок чого подрібнюється структура мартенситу та поліпшуються втомні властивості під час випробувань сталевих зразків за циклічного згину.Высокоуглеродистую высокопрочную мартенситную сталь AISI E52100 (JIS SUJ2) наиболее часто используют в условиях контактного качения, когда необходимы повышенные износостойкость и усталостная прочность. Предложены методы повторного индукционного нагрева и закаливания стали, вследствие чего измельчается структура мартенситна и улучшаются усталостные свойства во время испытаний стальных образцов при циклическом изгибе

Influence of hereditary haemochromatosis on left ventricular wall thickness: does iron overload exacerbate cardiac hypertrophy?

Background: The left ventricular (LV) hypertrophy increases the risk of heart failure. Hypertension and infiltrative cardiomyopathies are the well-known reasons of LV hypertrophy. The growing interest of scientists in this issue affects hereditary haemochromatosis (HH), which is characterised by the excess deposition of iron mostly due to HFE gene mutation. The aim of our study was to investigate the possible influence of HH on LV parameters in patients with early-diagnosed (early HH) and long-lasting and long-treated (old HH) disease. Materials and methods: Thirty nine early HH and 19 old HH patients were prospectively enrolled in the study; age- and sex-matched healthy volunteers constituted the appropriate control groups. All participants had echocardiography performed (including three-dimension volume and mass analysis); the iron turnover parameters were measured at the time of enrolment in every HH patients. Results: Echocardiographic parameters regarding to left atrium (LA), LV thickness, mass and long axis length were significantly higher, whereas LV ejection fraction was lower in early HH in comparison to healthy persons. In old HH patients the differences were similar to those mentioned before, except LV ejection fraction. The presence of hypertension in both HH groups did not influence echo parameters, as well as diabetes in old HH. The strongest correlation in all HH group was found between the time from HH diagnosis and LA, LV thickness and volumes parameters, but the correlations between iron turnover and echo parameters were non-existent. Conclusions: Hereditary haemochromatosis, not only long-lasting, but also early-diagnosed, could lead to exacerbation of LV wall thickness and cardiac hypertrophy. This effect is not simply connected with hypertension and diabetes that are frequent additional diseases in these patients, but with the time from HH diagnosis

Variability in black carbon mass concentration in surface snow at Svalbard

Black carbon (BC) is a significant forcing agent in the Arctic, but substantial uncertainty remains to quantify its climate effects due to the complexity of the different mechanisms involved, in particular related to processes in the snowpack after deposition. In this study, we provide detailed and unique information on the evolution and variability in BC content in the upper surface snow layer during the spring period in Svalbard (Ny-Ålesund). A total of two different snow-sampling strategies were adopted during spring 2014 (from 1 April to 24 June) and during a specific period in 2015 (28 April to 1 May), providing the refractory BC (rBC) mass concentration variability on a seasonal variability with a daily resolution (hereafter seasonal/daily) and daily variability with an hourly sampling resolution (hereafter daily/hourly) timescales. The present work aims to identify which atmospheric variables could interact with and modify the mass concentration of BC in the upper snowpack, which is the snow layer where BC particles affects the snow albedo. Atmospheric, meteorological and snow-related physico-chemical parameters were considered in a multiple linear regression model to identify the factors that could explain the variations in BC mass concentrations during the observation period. Precipitation events were the main drivers of the BC variability during the seasonal experiment; however, in the high-resolution sampling, a negative association has been found. Snow metamorphism and the activation of local sources (Ny-Ålesund was a coal mine settlement) during the snowmelt periods appeared to play a non-negligible role. The statistical analysis suggests that the BC content in the snow is not directly associated to the atmospheric BC load

Radiative impact of an extreme Arctic biomass-burning event

The aim of the presented study was to investigate the impact on the radiation budget of a biomass-burning plume, transported from Alaska to the High Arctic region of Ny-Ålesund, Svalbard, in early July 2015. Since the mean aerosol optical depth increased by the factor of 10 above the average summer background values, this large aerosol load event is considered particularly exceptional in the last 25 years. In situ data with hygroscopic growth equations, as well as remote sensing measurements as inputs to radiative transfer models, were used, in order to estimate biases associated with (i) hygroscopicity, (ii) variability of single-scattering albedo profiles, and (iii) plane-parallel closure of the modelled atmosphere. A chemical weather model with satellite-derived biomass-burning emissions was applied to interpret the transport and transformation pathways. The provided MODTRAN radiative transfer model (RTM) simulations for the smoke event (14:00 9 July–11:30 11 July) resulted in a mean aerosol direct radiative forcing at the levels of −78.9 and −47.0 W m−2 at the surface and at the top of the atmosphere, respectively, for the mean value of aerosol optical depth equal to 0.64 at 550 nm. This corresponded to the average clear-sky direct radiative forcing of −43.3 W m−2, estimated by radiometer and model simulations at the surface. Ultimately, uncertainty associated with the plane-parallel atmosphere approximation altered results by about 2 W m−2. Furthermore, model-derived aerosol direct radiative forcing efficiency reached on average −126 W m−2∕τ550 and −71 W m−2∕τ550 at the surface and at the top of the atmosphere, respectively. The heating rate, estimated at up to 1.8 K day−1 inside the biomass-burning plume, implied vertical mixing with turbulent kinetic energy of 0.3 m2 s−2

Top-quark physics at the CLIC electron-positron linear collider

Abstract The Compact Linear Collider (CLIC) is a proposed future high-luminosity linear electron-positron collider operating at three energy stages, with nominal centre-of-mass energies $$\sqrt{s}$$ s = 380 GeV, 1.5 TeV, and 3 TeV. Its aim is to explore the energy frontier, providing sensitivity to physics beyond the Standard Model (BSM) and precision measurements of Standard Model processes with an emphasis on Higgs boson and top-quark physics. The opportunities for top-quark physics at CLIC are discussed in this paper. The initial stage of operation focuses on top-quark pair production measurements, as well as the search for rare flavour-changing neutral current (FCNC) top-quark decays. It also includes a top-quark pair production threshold scan around 350 GeV which provides a precise measurement of the top-quark mass in a well-defined theoretical framework. At the higher-energy stages, studies are made of top-quark pairs produced in association with other particles. A study of t̄tH production including the extraction of the top Yukawa coupling is presented as well as a study of vector boson fusion (VBF) production, which gives direct access to high-energy electroweak interactions. Operation above 1 TeV leads to more highly collimated jet environments where dedicated methods are used to analyse the jet constituents. These techniques enable studies of the top-quark pair production, and hence the sensitivity to BSM physics, to be extended to higher energies. This paper also includes phenomenological interpretations that may be performed using the results from the extensive top-quark physics programme at CLIC.</jats:p

Top-quark physics at the CLIC electron-positron linear collider

ABSTRACT: The Compact Linear Collider (CLIC) is a proposed future high-luminosity linear electron-positron collider operating at three energy stages, with nominal centre-of-mass energies √s = 380 GeV, 1.5 TeV, and 3 TeV. Its aim is to explore the energy frontier, providing sensitivity to physics beyond the Standard Model (BSM) and precision measurements of Standard Model processes with an emphasis on Higgs boson and top-quark physics. The opportunities for top-quark physics at CLIC are discussed in this paper. The initial stage of operation focuses on top-quark pair production measurements, as well as the search for rare flavour-changing neutral current (FCNC) top-quark decays. It also includes a top-quark pair production threshold scan around 350 GeV which provides a precise measurement of the top-quark mass in a well-defined theoretical framework. At the higher-energy stages, studies are made of top-quark pairs produced in association with other particles. A study of t̄tH production including the extraction of the top Yukawa coupling is presented as well as a study of vector boson fusion (VBF) production, which gives direct access to high-energy electroweak interactions. Operation above 1 TeV leads to more highly collimated jet environments where dedicated methods are used to analyse the jet constituents. These techniques enable studies of the top-quark pair production, and hence the sensitivity to BSM physics, to be extended to higher energies. This paper also includes phenomenological interpretations that may be performed using the results from the extensive top-quark physics programme at CLIC.the Spanish Ministry of Economy, Industry and Competitiveness under projects MINEICO/FEDER-UE, FPA2015-65652-C4-3-R, FPA2015-71292-C2-1-Pand FPA2015-71956-REDT; and the MECD grant FPA2016-78645-P, Spai

Analysis of the contents of selected critical elements in waste from the hard coal cleaning process

Popioły ze spalania węgla od dawna rozpatrywane są jako potencjalne źródło szeregu pierwiastków krytycznych, czego dowodem są prowadzone badania nad odzyskiem germanu, galu oraz wanadu z popiołów powstających w przemysłowej instalacji zgazowania węgla IGCC Puertollano, a także powstała w 2011 roku w Chinach instalacja pilotowa do odzysku glinu i galu z popiołów lotnych z elektrowni węglowej. W tej sytuacji uzasadnionym jest pytanie, czy także odpady z przemysłowego wzbogacania węgla koksowego mogą stanowić potencjalne źródło wybranych pierwiastków krytycznych. W pracy przedstawiono wyniki badań zawartości wybranych pierwiastków, tj.: galu, berylu i kobaltu w takich właśnie odpadach. Przedmiotem analizy były węgle surowe kierowane do wzbogacania, odpady z płuczek zawiesinowych z cieczą ciężką, odpady z płuczek osadzarkowych i odpady z flotowników zakładów przeróbczych sześciu kopalń węgla koksowego. Celem określenia znaczenia tych odpadów jako potencjalnego źródła analizowanych pierwiastków krytycznych wykonano porównawczż analizę zawartości galu, berylu i kobaltu w popiele ze spalania węgla z Lubelskiego Zagłębia Węglowego, który to materiał jest często rozpatrywany jako potencjalne źródło pierwiastków krytycznych. Wyniki przeprowadzonych badań wskazują, że badane odpady ze wzbogacania węgli koksowych nie mogą być traktowane jako potencjalne źródło analizowanych pierwiastków krytycznych. Zawartość galu, berylu i kobaltu w odpadach, choć jest nieco wyższa od średniej zawartości tych pierwiastków w skorupie ziemskiej, to jednak jest zdecydowanie niższa od ich zawartości w analizowanym popiele ze spalania węgla z Lubelskiego Zagłębia Węglowego.Coal ashes have long been regarded as a potential source of a number of critical elements. This is evidenced by studies of the recovery of germanium, gallium, and vanadium from ashes formed at an industrial plant for coal gasification, IGCC Puertollano, and a pilot plant built in 2011 in China for the recovery of aluminumand galliumfromfly ashes emitted by a coal-fired power plant. Given this situation, it is justifiable to consider whether or not waste from the industrial cleaning of coking coal can also constitute a potential source of certain critical elements. This paper presents the results of examinations of the contents of selected elements – i.e. gallium, beryllium, and cobalt – in this kind of waste. The analysis focused on raw coals intended for cleaning, waste from scrubbers with heavy liquid, waste from sedimentation scrubbers, and waste from flotation at the cleaning plants of six coking coal mines. In order to determine the significance of the waste as a potential source of the analysed critical elements, a comparative analysis was conducted of the content of gallium, beryllium, and cobalt in ash from the combustion of coal from the Lublin Coal Basin. This ash is often regarded as a potential source of critical elements. The results of the conducted analyses indicate that the examined waste from the cleaning of coking coals cannot be treated as a potential source of these critical elements. The content of these elements in waste, though slightly higher than their average content in the lithosphere, is significantly lower than their content in the analysed ash from the combustion of coal from the Lublin Coal Basin

Modern materials for rapid prototyping

Niektóre spośród projektów naukowych wymagają nieszablonowego podejścia do problemu oraz nietypowego sprzętu laboratoryjnego. Stworzenie nowych prototypowych urządzeń coraz częściej staje się warunkiem koniecznym dla przeprowadzenia badań. Dzięki szybkiemu rozwojowi technologii projektowania i druku 3D możliwe jest rozbudowanie zaplecza technologicznego placówek badawczych. Podczas prac skupiono się na skonstruowaniu komory ciśnieniowej, która ma wiele zastosowań. Wspomniana komora (Rys. 1) została zaprojektowana przy pomocy oprogramowania CAD Autodesk Inventor Professional 2015. Komora składa się jedynie z kilku elementów, co ułatwia jej późniejsze złożenie przy pomocy prostych powszechnie dostępnych narzędzi. Komora ciśnieniowa jest zbudowana z poliwęglanu zmodyfikowanego różnymi dodatkami zmieniającymi właściwości filamentu. Jedną z możliwych modyfikacji jest dodatek nanokrzemionki, który posiada właściwości antybakteryjne. Umożliwia to wykonanie komory próżniowej wykorzystywanej np.: do sterylizacji narzędzi chirurgicznych. Wszystkie próbki użyte w tym projekcie przeszły testy szczelności wykonane metodą PALS (z ang. Positron Annihilation Lifetime Spectroscopy).Some of the scientific projects require outside the box approach to the problem and non-standard laboratory equipment. Creating a new prototype devices are increasingly becoming a prerequisite to conduct the research. Thanks to the rapid development of technology, design and 3D printing, make it possible to develop the technological facilities of research institutes. During the studies the main focus was on building the pressure chamber, which has various applications. Mentioned pressure chamber (Figure 1) was designed by the use of Autodesk Inventor Professional 2015 CAD software. The chamber consists of only few elements which facilitates the future assembling by using simple and commonly available tools. The pressure chamber is made of polycarbonate modified by various additives which change properties of filament. One of the possible modifications is nanosilicon additive which have antibacterial properties. It allows to use vacuum chamber for sterilization e.g. surgical instruments. All samples used in this project passed the tightness test associated with Positron Annihilation Lifetime Spectroscopy (PALS)