18,260 research outputs found

    First-principles kinetic modeling in heterogeneous catalysis: an industrial perspective on best-practice, gaps and needs

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    Electronic structure calculations have emerged as a key contributor in modern heterogeneous catalysis research, though their application in chemical reaction engineering remains largely limited to academia. This perspective aims at encouraging the judicious use of first-principles kinetic models in industrial settings based on a critical discussion of present-day best practices, identifying existing gaps, and defining where further progress is needed

    Evaluation of Stress Corrosion Cracking Susceptibility Using Fracture Mechanics Techniques, Part 1

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    Stress corrosion cracking (SSC) tests were performed on 13 aluminum alloys, 13 precipitation hardening stainless steels, and two titanium 6Al-4V alloy forgings to compare fracture mechanics techniques with the conventional smooth specimen procedures. Commercially fabricated plate and rolled or forged bars 2 to 2.5-in. thick were tested. Exposures were conducted outdoors in a seacoast atmosphere and in an inland industrial atmosphere to relate the accelerated tests with service type environments. With the fracture mechanics technique tests were made chiefly on bolt loaded fatigue precracked compact tension specimens of the type used for plane-strain fracture toughness tests. Additional tests of the aluminum alloy were performed on ring loaded compact tension specimens and on bolt loaded double cantilever beams. For the smooth specimen procedure 0.125-in. dia. tensile specimens were loaded axially in constant deformation type frames. For both aluminum and steel alloys comparative SCC growth rates obtained from tests of precracked specimens provide an additional useful characterization of the SCC behavior of an alloy

    Tricarbonyl M(I) (M = Re, 99mTc) complexes bearing acridine fluorophores : synthesis, characterization, DNA interaction studies and nuclear targeting

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    © The Royal Society of Chemistry 2010New pyrazolyl-diamine ligands with acridine derivatives at the 4-position of the pyrazolyl ring were synthesized and characterized (L1 and L2). Coordination towards the fac-[M(CO)3]+ (M = Re, 99mTc) led to complexes fac-[M(CO)3(κ3-L)] (L = L1: M = Re1, Tc1; L = L2: M = Re2, Tc2). The interaction of the novel pyrazolyl-diamine ligands (L1 and L2) and rhenium(I) complexes (Re1 and Re2) with calf thymus DNA (CT-DNA) was investigated by a variety of techniques, namely UV-visible , fluorescence spectroscopy and circular and linear dichroism . Compounds L1 and Re1 have moderate affinity to CT-DNA and bind to DNA by intercalation, while L2 and Re2 have a poor affinity for CT-DNA. Moreover, LD measurements showed that L1 and Re1 act as perfect intercalators . By confocal fluorescence microscopy we found that L1 and Re1 internalize and localize in the nucleus of B16F1 murine melanoma cells . The congener Tc1 complex also targets the cell nucleus exhibiting a time-dependent cellular uptake and a fast and high nuclear internalization (67.2% of activity after 30 min). Plasmid DNA studies have shown that Tc1 converts supercoiled (sc) puc19 DNA to the open circular (oc) form.Teresa Esteves and Sofia Gama thank the FCT for a doctoral and postdoctoral research grants (SFRH/BD/29154/2006 and SFRH/BPD/29564/2006, respectively). COST Action D39 is also acknowledge. The QITMS instrument was acquired with the support of the Programa Nacional de Reequipamento Científico (Contract>REDE/1503/REM/2005-ITN) of Fundação para a Ciência e a Tecnologia and is part of RNEM - Rede Nacional de Espectrometria de Massa

    F-15 inlet/engine test techniques and distortion methodologies studies. Volume 7: Cross correlation functions.

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    Cross correlation function plots were used to determine if peak distortion data taken from a subscale inlet model can be used to predict peak distortion levels for a full scale flight test vehicle

    Systemic inflammation, body composition, and physical performance in old community-dwellers

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    Background Chronic inflammation, changes in body composition, and declining physical function are hallmarks of the ageing process. The aim of the present study was to provide a preliminary characterisation of the relationship among these age-related phenomena via multivariate modelling. Methods Thirty-five old adults (OAs) and 17 young adults (YAs) were enrolled. The volume of skeletal muscle, subcutaneous adipose tissue (SAT), and intermuscular adipose tissue (IMAT) of the thigh was quantified by three-dimensional magnetic resonance imaging. Muscle strength was measured by knee extension strength testing. In OAs, physical performance was further assessed via the Short Physical Performance Battery (SPPB). Multi-block partial least squares-discriminant analysis (PLS-DA) was employed to explore the relationship among inflammatory profiles and functional and imaging parameters. Double cross-validation procedures were used to validate the predictive ability of the PLS-DA model. Results The optimal complexity of the PLS-DA model was found to be two latent variables. The proportion of correct classification was 92.3% in calibration (94.1% in YAs and 91.4% in OAs), 84.6% in internal validation (95.3% in YAs and 78.5% in OAs), and 82.6% in external validation (94% in YAs and 76.9% in OAs). Relative to YAs, OAs were characterised by smaller muscle volume, greater IMAT volume, lower muscle strength, and higher levels of myeloperoxidase, P-selectin, soluble intercellular adhesion molecule 1, and vascular cell adhesion molecule 1. Compared with OAs with SPPB >8, those scoring 8 were characterised by smaller muscle volume, greater SAT volume, lower muscle strength, and higher levels of interleukin 1 beta, 6, 10, 12, 13, tumour necrosis factor alpha, and granulocyte-macrophage colony-stimulating factor. Conclusions Multi-block PLS-DA identified distinct patterns of relationships among circulating cytokines and functional and imaging parameters in persons of different ages and varying levels of physical performance. The longitudinal implementation of such an innovative strategy could allow for the tracking of health status over time, the early detection of deviations in health trajectories, and the monitoring of response to treatments

    A Novel Ayurvedic treatment - Arthrothermia® for Osteoarthritis

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    Purpose: The purpose of this study was to report promising data revealed by a novel Ayurvedic treatment; Arthothermia® for patients with knee osteoarthritis (OA). Method: We enrolled 30 patients with OA who received Arthothermia® treatment. The Knee injury and Osteoarthritis Outcome Score (KOOS) was used to evaluate the treatment outcome. The five subscales of KOOS: Pain, Other Symptoms, Function in daily living (ADL), Function in Sport and Recreation (Sport/Rec), and knee-related Quality of Life (QOL) were scored separately. The KOOS data was calculated for the 30 patients before and after Arthothermia® treatment. Results: The KOOS before Arthothermia® ranged from 3.37 to 31.3. The KOOS was significantly improved after Arthothermia® and it ranged from 83.67 to 98.53. The difference in KOOS between before and after Arthothermia® treatment was calculated for the 30 patients as a group (unpaired t-test) as well as for each patient individually (paired t-test). The difference in KOOS was highly significant (p<0.0001) for both; unpaired and paired t-test analysis. Conclusion: The present study documented that the “Arthothermia®” – a unique Ayurveda treatment approach (combination of alkaline cautery and indirect micro thermal cautery) brought significant changes in KOOS in the OA patients in very short time duration. The promising data hold a ray of hope for better management of OA and needs wide explorations to bring magnificent outcome for patients suffering with OA

    Flavouring Group Evaluation 21 Revision 6 (FGE.21Rev6): thiazoles, thiophenes, thiazoline and thienyl derivatives from chemical groups 29 and 30

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    The Panel on Food additives and Flavourings (FAF) was requested to evaluate the flavouring substances 2,4-dimethyl-3-thiazoline [FL-no: 15.060] and 2-isobutyl-3-thiazoline [FL-no: 15.119] in Flavouring Group Evaluation 21 revision 6 (FGE.21Rev6). FGE.21Rev6 deals with 41 flavouring substances of which 39 have been already evaluated to be of no safety concern when based on the MSDI approach. For [FL-no: 15.060 and 15.119], a concern for genotoxicity was raised in FGE.21. Genotoxicity data have been submitted for the supporting substance 4,5-dimethyl-2-isobutyl-3-thiazoline [FL-no: 15.032] evaluated in FGE.76Rev2. The concerns for gene mutations and clastogenicity are ruled out for [FL-no: 15.032] and for the structurally related substances [FL-no: 15.060 and 15.119], but not for aneugenicity. Therefore, the aneugenic potential of [FL-no: 15.060 and 15.119] should be investigated in studies with the individual substances. For [FL-no: 15.054, 15.055, 15.057, 15.079 and 15.135], (more reliable) information on uses and use levels is needed to (re)calculate the mTAMDIs in order to finalise their evaluation. Provided that information is submitted for [FL-no: 15.060 and 15.119] with respect to potential aneugenicity, that would allow evaluation of these substances through the Procedure, also for these two substances, more reliable data on uses and use levels would be required. Upon submission of such data, additional data on toxicity may become necessary for all seven substances. For [FL-no: 15.054, 15.057, 15.079 and 15.135], information on the actual percentages of stereoisomers in the material of commerce based on analytical data should be provided

    A method for determining groups in cumulative incidence curves in competing risk data

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    The cumulative incidence function is the standard method for estimating the marginal probability of a given event in the presence of competing risks. One basic but important goal in the analysis of competing risk data is the comparison of these curves, for which limited literature exists. We proposed a new procedure that lets us not only test the equality of these curves but also group them if they are not equal. The proposed method allows determining the composition of the groups as well as an automatic selection of their number. Simulation studies show the good numerical behavior of the proposed methods for finite sample size. The applicability of the proposed method is illustrated using real data.Fundação para a Ciência e a Tecnologia | Ref. UIDB/00013/2020Fundação para a Ciência e a Tecnologia | Ref. UIDP/00013/2020Agencia Estatal de Investigación | Ref. PID2020‐118101GB‐I0

    Nonlinear Transmission of Financial Shocks: Some New Evidence

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    Financial shocks generate a protracted and quantitatively important effect on real economic activity and financial markets only if the shocks are both negative and large. Otherwise, their role is quite modest. Financial shocks have become more important for economic fluctuations after 2000 and have contributed substantially to deepening the recessions of 2001 and 2008. The evidence is obtained using a new econometric procedure based on a Vector Moving Average representation that includes a nonlinear function of the financial shock. This method is a contribution of the present work
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