Reaction kinetics of muonium with the halogen gases (F2, Cl2, and Br2)

Copyright @ 1989 American Institute of PhysicsBimolecular rate constants for the thermal chemical reactions of muonium (Mu) with the halogen gases—Mu+X2→MuX+X—are reported over the temperature ranges from 500 down to 100, 160, and 200 K for X2=F2,Cl2, and Br2, respectively. The Arrhenius plots for both the chlorine and fluorine reactions show positive activation energies Ea over the whole temperature ranges studied, but which decrease to near zero at low temperature, indicative of the dominant role played by quantum tunneling of the ultralight muonium atom. In the case of Mu+F2, the bimolecular rate constant k(T) is essentially independent of temperature below 150 K, likely the first observation of Wigner threshold tunneling in gas phase (H atom) kinetics. A similar trend is seen in the Mu+Cl2 reaction. The Br2 data exhibit an apparent negative activation energy [Ea=(−0.095±0.020) kcal mol−1], constant over the temperature range of ∼200–400 K, but which decreases at higher temperatures, indicative of a highly attractive potential energy surface. This result is consistent with the energy dependence in the reactive cross section found some years ago in the atomic beam data of Hepburn et al. [J. Chem. Phys. 69, 4311 (1978)]. In comparing the present Mu data with the corresponding H atom kinetic data, it is found that Mu invariably reacts considerably faster than H at all temperatures, but particularly so at low temperatures in the cases of F2 and Cl2. The current transition state calculations of Steckler, Garrett, and Truhlar [Hyperfine Interact. 32, 779 (986)] for Mu+X2 account reasonably well for the rate constants for F2 and Cl2 near room temperature, but their calculated value for Mu+Br2 is much too high. Moreover, these calculations seemingly fail to account for the trend in the Mu+F2 and Mu+Cl2 data toward pronounced quantum tunneling at low temperatures. It is noted that the Mu kinetics provide a crucial test of the accuracy of transition state treatments of tunneling on these early barrier HX2 potential energy surfaces.NSERC (Canada), Donors of the Petroleum Research Fund, administered by the American Chemical Society, for their partial support of this research and the Canada Council

The Design of the W. M. Keck Observatory Archive

The Michelson Science Center (MSC) and the W. M. Keck Observatory are building an archive that will serve data obtained at the Keck Observatory. The archive has begun operations and is ingesting Level 0 (uncalibrated) observations made with the recently upgraded High Resolution Echelle Spectrometer (HIRES); these observations will be publicly accessible after expiration of a proprietary period. Observatory staff have begun using the archived data to determine the long-term performance of the HIRES instrument. The archive is housed at the Michelson Science Center (MSC) and employs a modular design with the following components: (1) Data Evaluation and Preparation: images from the telescope are evaluated and native FITS headers are converted to metadata that will support archiving; (2) Trans Pacific Data Transfer: metadata are sent daily by e-mail and ingested into the archive in a highly fault tolerant fashion, and FITS images are written to DVDs and sent to MSC each week; (3) Science Information System: inherited from the NASA/IPAC Infrared Science Archive, it provides all the functionality needed to support database inquiries and processing of requests; and a Web-based (4) User Interface, a thin layer above the information system that accepts user requests and returns results. The design offers two major cost-saving benefits: it overcomes the geographical separation between the telescope and the archive and enables development at Keck and at MSC to proceed independently; and it permits direct inheritance of the IRSA architecture

Oxidation of Reduced Sulfur Species: Carbon Disulfide

Article on the oxidation of reduced sulfur species and carbon disulfide

Оценка эффективности лечебно-профилактического комплекса по динамике иммунобиохимических маркеров ротовой жидкости, системы интерферона и клеточного иммунитета у больных хронической герпетической инфекцией при планировании дентальной имплантации

У статті представлені результати оцінки ефективності використання лікувально-профілактичного комплексу шляхом визначення динаміки імунобіохімічних маркерів ротової рідини, системи інтерферону та клітинного імунітету у хворих на хронічну герпетичну інфекцію які потребують дентальної імплантації. Застосування лікувально-профілактичного комплексу сприяє усуненню порушень, що відбуваються в системі антиоксидантного захисту, в системі інтерферону та з боку показників клітинного імунітету, що в свою чергу призводить до раннього купірування запальної відповіді організму у післяопераційному періоді у пацієнтів із ХГІ після дентальної імплантації. Лікувально-профілактичний комплекс – ефективний захід щодо ки розвитку можливих рецидивів ХГІ та периімплантитів у цієї категорії пацієнтів при плануванні дентальної імплантації.Examination of immune biochemical, interferon status and state of cellular immunity in patients with chronic herpetic infection (ChHI), which need the dental implantation for development of the proper specific therapy is actual nowadays. Purpose and object of research – estimation of efficiency of treatment and prophylaxis complex (TPC) by determination of dynamics of immune biochemical markers of oral fluid, system of interferon and cellular immunity in patients with ChHI, which need dental implantation. 105 patents were examined in dynamics, the following groups were formed: control – practcally healthy (n = 35) and two groups of patents with ChHI: № 1 – basic (n = 35), № 2 – group of comparison (n = 35). TPC efcacy (“Amicsin® IS” administraton before implantaton according to the scheme of prophylaxis and afer implantaton – antdisbiotc drug “Qwertulin” afer the scheme of treatment) was estmated according to the immune biochemical level of oral cavity, state of cellular immunity and interferon status. A standard medical treatment for dental implantaton was used in group 2.В статье представлены результаты оценки эффективности применения лечебно-профилактического комплекса путем определения динамики иммунобиохимических маркеров ротовой жидкости, системы интерферона и клеточного иммунитета у больных хронической герпетической инфекцией требующих дентальной имплантации. Применение лечебно-профилактического комплекса способствует устранению нарушений, происходящих в системе антиоксидантной защиты, в системе интерферона и со стороны показателей клеточного иммунитета, что в свою очередь приводит к раннему купированию воспалительного ответа организма в послеоперационном периоде у пациентов с ХГИ после дентальной имплантации. Лечебно-профилактический комплекс – эффективная мера по профилактике развития возможных рецидивов ХГИ и периимплантита в этой категории пациентов при планировании дентальной имплантации

IP-FCM detects antigen-induced transient increase in ZAP70 association with TCR/CD3.

<p>OT1 TCR transgenic T cells were co-incubated with peptide-loaded T2Kb APCs for up to two hours. The APCs had been pulsed with either FARL or OVA peptides presented in H-2K^b. Following stimulation, cells were lysed and subjected to IP-FCM analysis. (<b>A</b>) ZAP70 association with TCR/CD3 increased in OVA- and Q4H7-stimulated cells (OVA: dark brown, open histogram; Q4H7: aqua, open histogram), when compared with FARL (blue, filled histograms). This difference was maintained by 30 minutes, but disappeared by 120 minutes. (<b>B</b>) For the ZAP70 recruitment data in each of 3 independent experiments, normalized values were calculated as described in Materials and Methods in order to assess the difference in fluorescence of each experimental group from the mean (set to 1) of all three experimental groups. This normalization manipulation allowed the data from the 3 independent experiments to be considered on a single scale while subjected together to one-way ANOVA followed by Newman-Keuls post-hoc tests. A significant difference was observed between OVA and FARL, OVA and Q4H7, and Q4H7 and FARL-induced ZAP70 association with TCR/CD3 (ANOVA: F_2,9 = 55.8, p<0.0001; **p<0.01, ***p<0.005).</p

IP-FCM detects physiologic PPIs associated with the TCR/CD3 complex.

<p>(<b>A</b>) IP antibodies to TCRα (green) are covalently coupled to CML microspheres, which are incubated with T cell lysates to immunoprecipitate the multiprotein complex (TCR/CD3 subunits plus ZAP70, as indicated). Fluorescently labeled probe antibodies specific for different components of the complex (in this case Zap70, red), can be used to detect the association between the primary target and associated proteins. (<b>B</b>) Anti-TCRα-conjugated CML beads were used to immunoprecipitate TCR/CD3 complexes from Tot1.1 cells. These complexes were negative when probed with irrelevant IgG (green), or with anti-Thy1.2 (yellow), the latter being specific for a highly expressed membrane protein that is not part of the complex. However, TCRα was present in shared complexes with TCRβ (black) and CD3ζ (blue). ZAP70 (red) also showed a lower but measurable association.</p

IP-FCM detects the specific inhibition of CD25:IL-2 interaction by the first-generation SMIPPI, Ro-26-4550.

<p>(<b>A</b>) Recombinant human CD25 (rhCD25) was immunoprecipitated with anti-CD25 antibody-conjugated CML beads. Recombinant human IL-2 (1000 U/ml) and one of several small-molecules were mixed with the beads for one hour, followed by probing with an anti-IL-2 antibody. Inhibition of the IL2:CD25 interaction was observed only upon addition of 10 mM R0-26-4550 (R26, blue shaded histogram). (<b>B</b>) Median fluorescence intensity from three experiments shows R26 significantly reduced IL-2:CD25 binding compared to either vehicle (DMSO) or PP2 negative controls (ANOVA: F_3,10 = 10.82, p = 0.0051; **p<0.01, *p,0.05) (<b>C</b>) Endogenous CD25 was immunoprecipitated from lysates from PMA/Ionomycin-stimulated human PBMCs, and analyzed as in (A) using 10,000 U/ml IL-2. (<b>D</b>) Median fluorescence intensity from four experiments including (C) shows R26 significantly reduced IL-2:CD25 binding compared to either vehicle (DMSO) or PP2 negative controls (ANOVA: F_3,15 = 10.07, p = 0.0013; **p<0.01) (<b>E</b>) Experiments for (C–D) included IL-2 and CD25 ELISAs that were performed. Compared to negative controls, R26 did not change the amount of IL2 or CD25 detected (N.S, not significant by Student’s T-test, p>>0.05), indicating that the difference in (C–D) was due altered IL-2:CD25 interaction.</p