342 research outputs found

    Influence of alkaline modification on adsorption properties of alumina

    Get PDF
    The kinetics of water vapor adsorption on alumina adsorbents at a temperature of 25 °C was studied. It was shown that modification by cations of alkali metals (K, Na) of the adsorbent based on alumina allows increasing its efficiency in the process of water vapor adsorption. The mathematical treatment of the experimental data by the dependence of water vapor adsorption on the time with the help of the Linear Driving Force (LDF) model and the dependence of adsorbent's adsorption capacity on the water vapor concentration (adsorption isotherm) by Dubinin-Astakhov equation was carried out. Constants included in the equations were defined

    Effect of particle size on adsorption kinetics of water vapor on porous aluminium oxide material

    Get PDF
    Influence of the grain size of aluminium oxide material, being a product of centrifugal thermal activation of hydrargillite, on adsorption kinetics of water vapors was studied. The material was characterized by the BET method and X-ray phase analysis (XRD). Influence of gas flow rate on adsorption dynamics was studied on a laboratory installation using McBain-Bakr quartz balance. It was shown that with the fraction size greater than 0.5-1.0 mm, the rate of water vapor adsorption on this adsorbent decreased, which was connected with the influence of internal diffusion resistance. On the base of the first-order kinetic equation for the water adsorption mathematical modeling was carried out. The kinetic parameters of the equation for the various grain size samples (0.25-0.5 mm and 0.5-1.0 mm and 3.7 x 6 mm granule) were determined

    Theoretical optimization of the shape and size of adsorbent grains for associated petroleum gas drying

    Get PDF
    The shape of adsorbent grains used for drying hydrocarbon gas flows at a reduced hydraulic resistance of their beds are theoretically optimized. A two-velocity model of gas flow in fixed beds consisting of differently shaped holed particles is used for calculations at typical parameters of the associated petroleum gas drying process. It is shown that the optimum shape of a grain is a four-spoke ring. At an equivalent diameter of 3 mm, such a grain is 6.154 × 6.154 mm in size, and its walls and baffles are 1.026 mm thick

    No Sommerfeld resummation factor in e+e- -> ppbar ?

    Get PDF
    The Sommerfeld rescattering formula is compared to the e+e- -> ppbar BaBar data at threshold and above. While there is the expected Coulomb enhancement at threshold, two unexpected outcomes have been found: |G^p (4M_p^2)|= 1, like for a pointlike fermion, and moreover data show that the resummation factor in the Sommerfeld formula is not needed. Other e+e- -> baryon-antibaryon cross sections show a similar behavior near threshold.Comment: 9 pages, 6 figure

    Crossover and rechallenge with pembrolizumab in recurrent patients from the EORTC 1325-MG/Keynote-054 phase III trial, pembrolizumab versus placebo after complete resection of high-risk stage III melanoma

    Get PDF
    Background: In the phase III double-blind European Organisation for Research and Treatment of Cancer 1325/KEYNOTE-054 trial, pembrolizumab improved recurrence-free and distant metastasis-free survival in patients with stage III cutaneous melanoma with complete resection of lymph nodes. In the pembrolizumab group, the incidence of grade I–V and of grade III–V immune-related adverse events (irAEs) was 37% and 7%, respectively. Methods: Patients were randomised to receive intravenous (i.v.) pembrolizumab 200 mg (N = 514) or placebo (N = 505) every 3 weeks, up to 1 year. On recurrence, patients could enter part 2 of the study: pembrolizumab 200 mg i.v. every 3 weeks up to 2 years, for crossover (those who received placebo) or rechallenge (those who had recurrence ≥6 months after completing 1-year adjuvant pembrolizumab therapy). For these patients, we present the safety profile and efficacy outcomes. Results: At the clinical cut-off (16-Oct-2020), in the placebo group, 298 patients had a disease recurrence, in which 155 (52%) crossed over (‘crossover’). In the pembrolizumab group, 297 patients completed the 1-year treatment period; 47 had a recurrence ≥6 months later, in which 20 (43%) entered the rechallenge part 2 (‘rechallenge’). In the crossover group, the median progression-free survival (PFS) was 8.5 months (95% confidence interval [CI] 5.7–15.2) and the 3-year PFS rate was 32% (95% CI 25–40%). Among 80 patients with stage IV evaluable disease, 31 (39%) had an objective response: 14 (18%) patients with complete response (CR) and 17 (21%) patients with partial response. The 2-year PFS rate from response was 69% (95% CI 48–83%). In the rechallenge group, the median PFS was 4.1 months (95% CI 2.6–NE). Among 9 patients with stage IV evaluable disease, 1 had an objective response (CR). Among the 175 patients, 51 (29%) had a grade I–IV irAE and 11 (6%) had a grade III–IV irAE. Conclusions: Pembrolizumab treatment after crossover yielded an overall 3-year PFS rate of 32% and a 39% ORR in evaluable patients, but the efficacy (11% ORR) was lower in those rechallenged

    Респираторная поддержка с ограничением дыхательного объёма и пикового давления у больных с острым респираторным дистресс-синдромом

    Get PDF
    The paper presents the results of a study, which prove the advantages of artificial ventilation with a descending air flow on inspiration, tidal volume 6 ml/kg body weight; P peak < 30 cm H2O in showing its efficiency, by optimizing the parameters of the respiratory pattern, by improving gas exchange in the lung, by reducing the time of respiratory support, the length of stay in an intensive care unit, and mortality rates as compared with artificial square-wave air flow on inspiration, TV 12—15 ml/kg body weight; Ppeak tracheal >35 cm H2°.В работе представлены результаты исследования, доказывающие преимущества искусственной вентиляции легких с нисходящей формой инспираторного потока, ДО 6—8 мл/кг массы тела; Ртр.пик. 30 см вод. ст. в отношении эффективности оптимизации параметров респираторного паттерна, улучшения газообмена в легких, сокращения сроков респираторной поддержки, пребывания в отделении реанимации и летальности у взрослых больных с острым респираторным дистресс-синдромом различного генеза по сравнению с искусственной вентиляцией легких с прямоугольной формой инспираторного потока, ДО 12—15 мл/кг массы тела, Ртр.пик. 35 см вод. ст

    Longitudinal double spin asymmetries in single hadron quasi-real photoproduction at high pTp_T

    Get PDF
    We measured the longitudinal double spin asymmetries ALLA_{LL} for single hadron muo-production off protons and deuterons at photon virtuality Q2Q^2 < 1(GeV/c\it c)2^2 for transverse hadron momenta pTp_T in the range 0.7 GeV/c\it c to 4 GeV/c\it c . They were determined using COMPASS data taken with a polarised muon beam of 160 GeV/c\it c or 200 GeV/c\it c impinging on polarised 6LiD\mathrm{{}^6LiD} or NH3\mathrm{NH_3} targets. The experimental asymmetries are compared to next-to-leading order pQCD calculations, and are sensitive to the gluon polarisation ΔG\Delta G inside the nucleon in the range of the nucleon momentum fraction carried by gluons 0.05<xg<0.20.05 < x_g < 0.2

    Interplay among transversity induced asymmetries in hadron leptoproduction

    Get PDF
    In the fragmentation of a transversely polarized quark several left-right asymmetries are possible for the hadrons in the jet. When only one unpolarized hadron is selected, it exhibits an azimuthal modulation known as Collins effect. When a pair of oppositely charged hadrons is observed, three asymmetries can be considered, a di-hadron asymmetry and two single hadron asymmetries. In lepton deep inelastic scattering on transversely polarized nucleons all these asymmetries are coupled with the transversity distribution. From the high statistics COMPASS data on oppositely charged hadron-pair production we have investigated for the first time the dependence of these three asymmetries on the difference of the azimuthal angles of the two hadrons. The similarity of transversity induced single and di-hadron asymmetries is discussed. A new analysis of the data allows to establish quantitative relationships among them, providing for the first time strong experimental indication that the underlying fragmentation mechanisms are all driven by a common physical process.Comment: 6 figure
    corecore