209 research outputs found

    Visible photodissociation spectroscopy of PAH cations and derivatives in the PIRENEA experiment

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    The electronic spectra of gas-phase cationic polycyclic aromatic hydrocarbons (PAHs), trapped in the Fourier Transform Ion Cyclotron Resonance cell of the PIRENEA experiment, have been measured by multiphoton dissociation spectroscopy in the 430-480 nm spectral range using the radiation of a mid-band optical parametric oscillator laser. We present here the spectra recorded for different species of increasing size, namely the pyrene cation (C16H10+), the 1-methylpyrene cation (CH3-C16H9+), the coronene cation (C24H12+), and its dehydrogenated derivative C24H10+. The experimental results are interpreted with the help of time-dependent density functional theory calculations and analysed using spectral information on the same species obtained from matrix isolation spectroscopy data. A kinetic Monte Carlo code has also been used, in the case of pyrene and coronene cations, to estimate the absorption cross-sections of the measured electronic transitions. Gas-phase spectra of highly reactive species such as dehydrogenated PAH cations are reported for the first time

    Flocculation of Reactive Blue 19 (RB19) using Alum and the Effects of Catalysts Addition

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    There are a variety of primary coagulants which can be used in a water treatment plant. One of the earliest, and still the most extensively used, is aluminum sulfate, also known as alum. Aluminum Sulfate (Alum) is one of the most commonly used flocculent in waste water treatment processes. Effectiveness of Alum in flocculation process is determined by many factors such as the effluents pH, flocculent dose as well as the use of catalyst to improve efficiency rate of flocculation. Hence special attention to these factors especially the use of catalyst has been brought about by this study. Experiments were carried out using Reactive Blue 19 Dye as the contaminant of waste water and two catalysts namely Calcium Hydroxide (CaOH2) and Poly Aluminum Chloride (PACl) were evaluated. The results obtained proved that indeed after addition of catalysts, removal efficiency rates of Alum can be increased up to 25% using Calcium Hydroxide and up to 35% using Poly Aluminum Chloride compared to Alum alone. The optimum conditions for this study were at pH 5.5 ~7.5, 300 mg/L of Alum 30seconds of rapid mixing time with 300 rpm , 30rpm of mixing rate for 5 minutes and 30 minutes of settling time. Moreover, Alum showed the highest performance under these conditions and using 50 mg/L PACl as catalyst with 98.52% of COD reduction and 90.60% of color reduction. In conclusion, Alum with the support of PACl as catalyst is an effective coagulant, which can reduce the level of COD and Dye Color in Reactive Blue 19 contaminated wastewater

    Effects of a simple cardiac rehabilitation program on improvement of self-reported physical activity in atrial fibrillation - Data from the RACE 3 study

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    Background and aim: Physical inactivity is associated with an increased prevalence of atrial fibrillation (AF). We aim to evaluate whether cardiac rehabilitation (CR) motivates patients to become and stay physical active, and whether CR affects sinus rhythm maintenance and quality of life (QoL) in patients with persistent AF and moderate heart failure. Methods: In the Routine versus Aggressive risk factor driven upstream rhythm Control for prevention of Early atrial fibrillation in heart failure study patients were randomized to conventional or targeted therapy. Targeted therapy contained next to optimal risk factor management a 3-month CR program, including self-reported physical activity and counseling. Successful physical activity was assessed in the targeted group, defined as activity of moderate intensity >= 150 min/week, or >= 75 min/week of vigorous intensity. AF was assessed at 1 year on 7-days Holter monitoring, QoL using general health, fatigue and AF symptom questionnaires. Results: All 119 patients within the targeted group participated in the CR program, 106 (89%) completed it. At baseline 80 (67%) patients were successfully physical active, 39 (33%) were not. NTproBNP was lower in active patients. During 1-year follow-up physical active patients stayed active: 72 (90%) at 12 weeks, 72 (90%) at 1 year. Inactive patients became active: at 12 weeks 25 (64%) patients and 30 (77%) at 1 year. No benefits were seen on sinus rhythm maintenance and QoL for successful physical active patients. Conclusion: In patients with persistent AF and moderate heart failure participation in CR contributes to improve and to maintain physical activity. (C) 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)

    Laser Spectroscopic Studies of the E 1ÂŁ+ State of the MgO Molecule

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    The E1ÎŁ+ ‘Rydberg' state of 24Mg16O has been characterized by two-color resonance-enhanced two-photon ionization (R2PI) spectroscopy in the 36 000–40 000 cm−1 region. Several rotationally resolved bands, assigned consistently to 24Mg16O(E1ÎŁ+←X1ÎŁ+) vibronic transitions, have been analyzed. The effective Bvâ€Č(vâ€Č=0−8) constants determined exhibit an unusual variation with vâ€Č. Possible causes of this variation are discussed. Estimated spectroscopic constants for the E1ÎŁ+ state are reported

    Electromagnetic form factor of pion from N_f=2+1 dynamical flavor QCD

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    We present a calculation of the electromagnetic form factor of the pion in Nf=2+1N_f=2+1 flavor lattice QCD. Calculations are made on the PACS-CS gauge field configurations generated using Iwasaki gauge action and Wilson-clover quark action on a 323×6432^3\times64 lattice volume with the lattice spacing estimated as a=0.0907(13)a=0.0907(13) fm at the physical point. Measurements of the form factor are made using the technique of partially twisted boundary condition to reach small momentum transfer as well as periodic boundary condition with integer momenta. Additional improvements including random wall source techniques and a judicious choice of momenta carried by the incoming and outgoing quarks are employed for error reduction. Analyzing the form factor data for the pion mass at Mπ≈411M_\pi \approx 411 MeV and 296 MeV, we find that the NNLO SU(2) chiral perturbation theory fit yields =0.441±0.046fm2=0.441 \pm 0.046 {\rm fm}^2 for the pion charge radius at the physical pion mass. Albeit the error is quite large, this is consistent with the experimental value of 0.452±0.011fm20.452\pm 0.011 {\rm fm}^2. Below Mπ≈300M_\pi\approx 300 MeV, we find that statistical fluctuations in the pion two- and three-point functions become too large to extract statistically meaningful averages on a 32332^3 spatial volume. We carry out a sample calculation on a 64464^4 lattice with the quark masses close to the physical point, which suggests that form factor calculations at the physical point become feasible by enlarging lattice sizes to MπL≈4M_\pi L\approx 4.Comment: 28 pages, 14 figure

    Formation and destruction of polycyclic aromatic hydrocarbon clusters in the interstellar medium

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    The competition between the formation and destruction of coronene clusters under interstellar conditions is investigated theoretically. The unimolecular nucleation of neutral clusters is simulated with an atomic model combining an explicit classical force field and a quantum tight-binding approach. Evaporation rates are calculated in the framework of the phase space theory and are inserted in an infrared emission model and compared with the growth rate constants. It is found that, in interstellar conditions, most collisions lead to cluster growth. The time evolution of small clusters (containing up to 312 carbon atoms) was specifically investigated under the physical conditions of the northern photodissociation region of NGC 7023. These clusters are found to be thermally photoevaporated much faster than they are reformed, thus providing an interpretation for the lowest limit of the interstellar cluster size distribution inferred from observations. The effects of ionizing the clusters and density heterogeneities are also considered. Based on our results, the possibility that PAH clusters could be formed in PDRs is critically discussed.Comment: 14 pages, 14 figures. Astronomy & Astrophysics, accepted for publicatio

    Abandonment and rapid infilling of a tide-dominated distributary channel at 0.7 ka in the Mekong River Delta

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    The Ba Lai distributary channel of the Mekong River Delta was abandoned and infilled with sediment during the Late Holocene, providing a unique opportunity to investigate the sediment fill, timing and mechanisms of channel abandonment in tide-dominated deltaic systems. Based on analysis and age dating of four sediment cores, we show that the channel was active since 2.6 ka and was abandoned at 0.7 ka as marked by the abrupt disappearance of the sand fraction and increase in organic matter and sediment accumulation rate. We estimate that the channel might have been filled in a time range of 45–263 years after detachment from the deltaic network, with sediment accumulation rates of centimetres to decimetres per year, rapidly storing approximately 600 Mt of organic-rich mud. We suggest that the channel was abandoned due to a sediment buildup favoured by an increase in regional sediment supply to the delta. This study highlights that mechanisms for abandonment and infilling of tide-dominated deltaic channels do not entirely fit widely used models developed for fluvial-dominated environments. Their abandonment might be driven by autogenic factors related to the river-tidal and deltaic dynamics and favoured by allogenic factors (e.g., human impact and/or climate change).</jats:p

    Discussing Depression with Vietnamese American Patients

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    Background Asian patients preferentially seek mental health care from their primary care providers but are unlikely to receive it. Primary care providers need culturally-informed strategies for addressing stigmatizing illnesses. Methods 11 Vietnamese American community members participated in semi-structured interviews. Interviews were audio-taped and transcribed. The grounded theory approach was used for qualitative coding and thematic analysis. Results Vietnamese community members describe experiences with depression under four themes: (1) Stigma and face; (2) Social functioning and the role of the family; (3) Traditional healing and beliefs about medications; and (4) Language and culture. Based on this data, we offer suggestions for improving culturally-informed care for Vietnamese Americans. Disucssion Our study adds to the research aimed at improving communication and health care relationships between physicians and Vietnamese American patients. Physicians should learn to tailor their interviewing style to the increasingly diverse patient population
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