478 research outputs found

    Evidence for partial quenching of orbital angular momentum upon complex formation in the infrared spectrum of OH-acetylene

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    The entrance channel leading to the addition reaction between the hydroxyl radical and acetylene has been examined by spectroscopic characterization of the asymmetric CH stretching band of the π-hydrogen bonded OH-acetylene reactant complex. The infrared action spectrum observed at 3278.6 cm−1 (origin) consists of seven peaks of various intensities and widths, and is very different from those previously reported for closed-shell HF/HCl-acetylene complexes. The unusual spectrum arises from a partial quenching of the OH orbital angular momentum in the complex, which in turn is caused by a significant splitting of the OH monomer orbital degeneracy into 2A′ and 2A″ electronic states. The magnitude of the 2A′−2A″ splitting as well as the A rotational constant for the OH-acetylene complex are determined from the analysis of this b-type infrared band. The most populated OH product rotational state, jOH = 9/2, is consistent with intramolecular vibrational energy transfer to the ν2 C≡C stretching mode of the departing acetylene fragment. The lifting of the OH orbital degeneracy and partial quenching of its electronic orbital angular momentum indicate that the electronic changes accompanying the evolution of reactants into products have begun to occur in the reactant complex

    Infrared spectrum and stability of a π-type hydrogen-bonded complex between the OH and C2H2 reactants

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    A hydrogen-bonded complex between the hydroxyl radical and acetylene has been stabilized in the reactant channel well leading to the addition reaction and characterized by infrared action spectroscopy in the OH overtone region. Analysis of the rotational band structure associated with the a-type transition observed at 6885.53(1) cm−1 (origin) reveals a T-shaped structure with a 3.327(5) Å separation between the centers of mass of the monomer constituents. The OH (v = 1) product states populated following vibrational predissociation show that dissociation proceeds by two mechanisms: intramolecular vibrational to rotational energy transfer and intermolecular vibrational energy transfer. The highest observed OH product state establishes an upper limit of 956 cm−1 for the stability of the π-type hydrogen-bonded complex. The experimental results are in good accord with the intermolecular distance and well depth at the T-shaped minimum energy configuration obtained from complementary ab initio calculations, which were carried out at the restricted coupled cluster singles, doubles, noniterative triples level of theory with extrapolation to the complete basis set limit

    (2+1) Resonance Enhanced Ionization Spectroscopy of a State Selected Beam of OH Radicals

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    A state-selected beam of hydroxyl radicals is generated using a pulsed discharge source and hexapole field. The OH radicals are characterized by resonance-enhanced multiphoton ionization (REMPI) spectroscopy via the nested D  and 3  Rydberg states. Simplified spectra are observed from the selected ∣MJ∣ = 3/2 component of the upper Λ-doublet level of the lowest rotational state (J = 3/2) in ground (v″ = 0) and excited(v″ = 1–3) vibrational levels of the OH X  state. Two-photon transitions are observed to the D (v′ = 0–3) and 3 (v′ = 0,1) vibronic levels, extending previous studies to higher vibrational levels of the Rydberg states. Spectroscopic constants are derived for the Rydberg states and compared with prior experimental studies. Complementary first-principle theoretical studies of the D  and 3  Rydberg states [see M. P. J. van der Loo and G. C. Groenenboom, J. Chem. Phys. 123, 074310 (2005), following paper ] are used to interpret the experimental findings and examine the utility of the (2+1) REMPI scheme for sensitive detection of OH radicals

    Unimolecular Decay of the Dimethyl-Substituted Criegee Intermediate in Alkene Ozonolysis : Decay Time Scales and the Importance of Tunneling

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    We used the steady-state master equation to model unimolecular decay of the Criegee intermediate formed from ozonolysis of 2,3-dimethyl-2-butene (tetramethylethylene, TME). Our results show the relative importance and time scales for both the prompt and thermal unimolecular decay of the dimethyl-substituted Criegee intermediate, (CH3)(2)COO. Calculated reactive fluxes show the importance of quantum mechanical tunneling for both prompt and thermal decay to OH radical products. We constrained the initial energy distribution of chemically activated (CH3)(2)COO formed in TME ozonolysis by combining microcanonical rates k(E) measured experimentally under collision-free conditions and modeled using semiclassical transition-state theory (SCTST) with pressure dependent yields of stabilized Criegee intermediates measured with scavengers in flow-tube experiments. Thermal decay rates under atmospheric conditions k(298 K, 1 atm) increase by more than 1 order of magnitude when tunneling is included. Accounting for tunneling has important consequences for interpreting pressure dependent yields of stabilized Criegee intermediates, particularly with regard to the fraction of Criegee intermediates formed in the zero-pressure limit.Peer reviewe

    Impact of elosulfase alfa in patients with morquio A syndrome who have limited ambulation: An open-label, phase 2 study.

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    Efficacy and safety of elosulfase alfa enzyme replacement therapy (ERT) were assessed in an open-label, phase 2, multi-national study in Morquio A patients aged ≥5 years unable to walk ≥30 meters in the 6-min walk test. Patients received elosulfase alfa 2.0 mg/kg/week intravenously for 48 weeks. Efficacy measures were functional dexterity, pinch/grip strength, mobility in a modified timed 25-foot walk, pain, quality of life, respiratory function, and urine keratan sulfate (KS). Safety/tolerability was also assessed. Fifteen patients received elosulfase alfa, three patients discontinued ERT due to adverse events (two were grade 3 drug-related adverse events, the other was not drug-related), and two patients missed >20% of planned infusions; 10 completed treatment through 48 weeks and received ≥80% of planned infusions (Modified Per Protocol [MPP] population). The study population had more advanced disease than that enrolled in other trials. From baseline to week 48, MPP data showed biochemical efficacy (urine KS decreased 52.4%). The remaining efficacy results were highly variable due to challenges in test execution because of severe skeletal and joint abnormalities, small sample sizes, and clinical heterogeneity among patients. Eight patients showed improvements in one or more outcome measures; several patients indicated improvements not captured by the study assessments (e.g., increased energy, functional ability). The nature of adverse events was similar to other elosulfase alfa studies. This study illustrates the considerable challenges in objectively measuring impact of ERT in very disabled Morquio A patients and highlights the need to examine results on an individual basis. © 2016 The Authors. American Journal of Medical Genetics Part A Published by Wiley Periodicals, Inc

    HexPak and GradPak: variable-pitch dual-head IFUs for the WIYN 3.5m Telescope Bench Spectrograph

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    We describe the design, construction, and expected performance of two new fiber integral field units (IFUs) --- HexPak and GradPak --- for the WIYN 3.5m Telescope Nasmyth focus and Bench Spectrograph. These are the first IFUs to provide formatted fiber integral field spectroscopy with simultaneous sampling of varying angular scales. HexPak and GradPak are in a single cable with a dual-head design, permitting easy switching between the two different IFU heads on the telescope without changing the spectrograph feed: the two heads feed a variable-width double-slit. Each IFU head is comprised of a fixed arrangement of fibers with a range of fiber diameters. The layout and diameters of the fibers within each array are scientifically-driven for observations of galaxies: HexPak is designed to observe face-on spiral or spheroidal galaxies while GradPak is optimized for edge-on studies of galaxy disks. HexPak is a hexagonal array of 2.9 arcsec fibers subtending a 40.9 arcsec diameter, with a high-resolution circular core of 0.94 arcsec fibers subtending 6 arcsec diameter. GradPak is a 39 by 55 arcsec rectangular array with rows of fibers of increasing diameter from angular scales of 1.9 arcsec to 5.6 arcsec across the array. The variable pitch of these IFU heads allows for adequate sampling of light profile gradients while maintaining the photon limit at different scales.Comment: 10 pages, 4 figures, presented at SPIE, Astronomical Telescopes and Instrumentation, 1 - 6 July 2012, Amsterdam, Netherland

    Photodissociation of the OD radical at 226 and 243 nm

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    The photodissociation dynamics of state selected OD radicals has been examined at 243 and 226 nm using velocity map imaging to probe the angle–speed distributions of theD(2S) and O(3P2) products. Both experiment and complementary first principle calculations demonstrate that photodissociation occurs by promotion of OD from high vibrational levels of the ground X 2Π state to the repulsive 1 2Σ− state

    CARDIAC CEPHALALGIA

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    Cardiac cephalalgia merupakan nyeri kepala seperti migraine, umumnya namun tidak selalu diperberat dengan aktivitas fisik, timbul selama peristiwa myocardial ischaemia, membaik dengan pemberian nitroglycerine. Cardiac cephalalgia merupakan kasus nyeri kepala yang jarang namun dapat mempengaruhi aspek biopsikososial dan kualitas hidup penderita.  Berdasarkan The Internasional Classification of Headache Disorder (ICHD), cardiac cephalalgia digolongkan ke dalam nyeri kepala sekunder yang terkait dengan kelainan homeostasis. Artikel ini membahas pengetahuan terbaru mengenai cardiac cephalalgia terkait definisi, epidemiologi, patofisiologi, gambaran klinis, penegakan diagnosis, diagnosis banding, serta pilihan terapinya dengan melakukan pencarian, review dan telaah serta menyimpulkan berbagai literatur terbaru terkait hal tersebut. Cardiac cephalalgia sering ditemukan pada usia dekade lima. Penegakkan diagnosis berdasarkan nyeri kepala yang berkaiatan dengan adanya myocardial ischaemia, dan berespon baik dengan pemberian nitroglycerine. Penatalaksanaan cardiac cephalalgia menitikberatkan pada penanganan myocardial ischaemia. Nitroglycerine merupakan pilihan utama untuk nyeri kepala Kata Kunci : Cardiac Cephalalgia, Nyeri Kepala Sekunder, Myocardial Ischaemi

    Genetic variation in genes for the xenobiotic-metabolizing enzymes CYP1A1, EPHX1, GSTM1, GSTT1, and GSTP1 and susceptibility to colorectal cancer in Lynch syndrome.

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    Individuals with Lynch syndrome are predisposed to cancer due to an inherited DNA mismatch repair gene mutation. However, there is significant variability observed in disease expression likely due to the influence of other environmental, lifestyle, or genetic factors. Polymorphisms in genes encoding xenobiotic-metabolizing enzymes may modify cancer risk by influencing the metabolism and clearance of potential carcinogens from the body. In this retrospective analysis, we examined key candidate gene polymorphisms in CYP1A1, EPHX1, GSTT1, GSTM1, and GSTP1 as modifiers of age at onset of colorectal cancer among 257 individuals with Lynch syndrome. We found that subjects heterozygous for CYP1A1 I462V (c.1384A\u3eG) developed colorectal cancer 4 years earlier than those with the homozygous wild-type genotype (median ages, 39 and 43 years, respectively; log-rank test P = 0.018). Furthermore, being heterozygous for the CYP1A1 polymorphisms, I462V and Msp1 (g.6235T\u3eC), was associated with an increased risk for developing colorectal cancer [adjusted hazard ratio for AG relative to AA, 1.78; 95% confidence interval, 1.16-2.74; P = 0.008; hazard ratio for TC relative to TT, 1.53; 95% confidence interval, 1.06-2.22; P = 0.02]. Because homozygous variants for both CYP1A1 polymorphisms were rare, risk estimates were imprecise. None of the other gene polymorphisms examined were associated with an earlier onset age for colorectal cancer. Our results suggest that the I462V and Msp1 polymorphisms in CYP1A1 may be an additional susceptibility factor for disease expression in Lynch syndrome because they modify the age of colorectal cancer onset by up to 4 years

    Pengaplikasian Ecoenzym Melalui Penyemprotan di Desa Geluntung, Marga, Tabanan

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    Mitra pelaksana program kerja kali ini adalah Banjar Desa Geluntung, Kecamatan Marga, Kabupaten Tabanan. Metode yang digunakan pada penelitian ini adalah kualitatif dengan teknik analisis deskriptif. Data kualitatif penelitian berupa nama dan alamat obyek penelitian. Penulisan jurnal memfokuskan pada kegiatan pengaplikasian ecoenzym dengan teknik deskriptif disertai dengan gambar kegiatan. Kurangnya pengolahan sampah organik di Desa Geluntung menyebabkan warga sekitar hanya memfokuskan pada sampah non organik padahal sampah organik juga memiliki banyak manfaat salah satunya diolah melalui metode ecoenzym yang dapat diaplikasikan dengan cara penyemprotan. Pengaplikasian dengan cara penyemprotan ecoenzym ini dilakukan ke seluruh banjar yang ada di Desa Geluntung dan pinggiran rumah-rumah warga sepanjang Desa Geluntung. Pratik ini dilakukan dibawah pengawasan setiap klian banjar untuk mewujudkan kepedulian terhadap masyarakat di Desa Geluntung guna menjaga ekosistem alam agar udara tetap bersih dan sehat. Dengan demikian diharapkan warga desa geluntung dapat membuat ecoenzym dan mengaplikasikannya secara rutin sehingga akan menciptkan lingkungan yang bersih dan sehat
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