Hydrogen Motion in Magnesium Hydride by NMR

In coarse-grained MgH2, the diffusive motion of hydrogen remains too slow (<10^5 hops s^−1) to narrow the H NMR line up to 400 °C. Slow-motion dipolar relaxation time T1D measurements reveal the motion, with hopping rate ωH from 0.1 to 430 s^−1 over the range of 260 to 400 °C, the first direct measurement of H hopping in MgH2. The ωH data are described by an activation energy of 1.72 eV (166 kJ/mol) and attempt frequency of 2.5 × 10^15 s^−1. In ball-milled MgH2 with 0.5 mol % added Nb2O5 catalyst, line-narrowing is evident already at 50 °C. The line shape shows distinct broad and narrow components corresponding to immobile and mobile H, respectively. The fraction of mobile H grows continuously with temperature, reaching ∼30% at 400 °C. This demonstrates that this material’s superior reaction kinetics are due to an increased rate of H motion, in addition to the shorter diffusion paths from ball-milling. In ball-milled MgH2 without additives, the line-narrowed component is weaker and is due, at least in part, to trapped H2 gas. The spin−lattice relaxation rates T1^−1 of all materials are compared, with ball-milling markedly increasing T1^−1. The weak temperature dependence of T1^−1 suggests a mechanism with paramagnetic relaxation centers arising from the mechanical milling

Adjusted prognostic association of post-myocardial infarction depression withmortality and cardiovascular events: an individual patient data meta-analysis

Background: The association between depression after myocardial infarction (post-MI) and increased risk of mortality and cardiac morbidity may be due to cardiac disease severity. Aims: To combine original data from studies on the association between post-MI depression and prognosis into one database. To investigate to what extent post-MI depression predicts prognosis independently of disease severity. Method: Individual patient data meta-analysis of studies, using multilevel, multivariable Cox regression analyses. Results:Sixteen studies participated, creating a database of 10,175 post-MI patients. HRs for post-MI depression were 1.32 (95%CI 1.26-1.38, p Conclusions: The association between post-MI depression and prognosis is attenuated after adjustment for cardiac disease severity. Still, depression remains independently associated with prognosis, with a 22% increased risk of all-cause mortality and a 13% increased risk of cardiovascular events per standard deviation in depression z-score. Declaration of interest: None

GrassPlot - a database of multi-scale plant diversity in Palaearctic grasslands

GrassPlot is a collaborative vegetation-plot database organised by the Eurasian Dry Grassland Group (EDGG) and listed in the Global Index of Vegetation-Plot Databases (GIVD ID EU-00-003). GrassPlot collects plot records (releves) from grasslands and other open habitats of the Palaearctic biogeographic realm. It focuses on precisely delimited plots of eight standard grain sizes (0.0001; 0.001;... 1,000 m(2)) and on nested-plot series with at least four different grain sizes. The usage of GrassPlot is regulated through Bylaws that intend to balance the interests of data contributors and data users. The current version (v. 1.00) contains data for approximately 170,000 plots of different sizes and 2,800 nested-plot series. The key components are richness data and metadata. However, most included datasets also encompass compositional data. About 14,000 plots have near-complete records of terricolous bryophytes and lichens in addition to vascular plants. At present, GrassPlot contains data from 36 countries throughout the Palaearctic, spread across elevational gradients and major grassland types. GrassPlot with its multi-scale and multi-taxon focus complements the larger international vegetationplot databases, such as the European Vegetation Archive (EVA) and the global database " sPlot". Its main aim is to facilitate studies on the scale-and taxon-dependency of biodiversity patterns and drivers along macroecological gradients. GrassPlot is a dynamic database and will expand through new data collection coordinated by the elected Governing Board. We invite researchers with suitable data to join GrassPlot. Researchers with project ideas addressable with GrassPlot data are welcome to submit proposals to the Governing Board

C.Morris, “Membrane array characterization of 80 chemokines, cytokines, and growth factors in open- and closed-eye tears: angiogenin and other defense system constituents,” Investigative Ophthalmology and

PURPOSE. To adapt membrane-bound antibody array (MA) technology to characterize the distribution of a wide range of bioactive trace proteins in reflex (RTF) and open-eye (OTF) and closed-eye (CTF) tear samples. METHODS. Tears were collected by capillary tube and centrifuged. A commercially available standard MA and a custom array were modified to maximize the sensitivity of detection and the signal-to-noise ratio, to assay RTF and individually pooled CTF and OTF samples for 80 chemokines, growth factors, cytokines, and angiogenic modulators. The reliability of data was assessed by Western blot and other methods. RESULTS. Coupling an ultrasensitive chemiluminescence substrate system to an MA and optimizing conditions enhanced the sensitivity several hundredfold, allowing the detection of ϳ40 of the 79 probed proteins on the standard array, most of which were shown to be elevated in CTF. Identified entities include the known constituents epidermal growth factor (EGF), monocyte chemoattractant protein (MCP)-1, IL-8, tissue inhibitor of metalloproteinase (TIMP)-1 and -2, and numerous previously undetected tear components, such as angiogenin (ANG), growth factors, and the CXC and CC chemokines IFN-␥ inducible protein (IP)-10, growth-related oncogene (GRO), epithelial neutrophil-activating protein (ENA)-78, and macrophage inflammatory protein (MIP)-3␣. Identification of other proteins was hindered by high background on the negative control array. Using a less complex custom array dramatically reduced background and allowed the visualization in CTF of proteins, such as VEGF, that were not detected with the standard array. CONCLUSIONS. MAs are powerful tools for differential screening of tears for large numbers of trace proteins. Analysis allowed the identification of previously undetected proteins that may participate in the host defense system as well as demonstrated the profound change in tear composition associated with prolonged eye closure in a manner reflective of physiological function. (Invest Ophthalmol Vis Sci. 2005;45:1228 -1238) DOI:10.1167/iovs.04-0760 T he preocular tear layer plays a critical role in the innate and adaptive host defense systems and participates in many other processes that are central to the maintenance of the integrity of the ocular surface tissues. This complex mixture has been only partially characterized. 1-3 Mass spectrometric (MS) analysis of open-eye tear fluid, 3 for example, yields an incomplete listing of more than 100 low-abundance proteins, including dozens of cytokines, chemokines, growth factors, angiogenic modulators, and other proteins, such as enzymes and inhibitors, that are bioactive in very low concentrations. These substances are of heterogeneous origins derived from cellular debris, lacrimal gland and accessory gland secretions, ocular surface tissue products, serum exudate, and transient or resident inflammatory and immune cells recruited into the local environment. 1,2,4 -6 As such, the concentrations and relative distribution of these entities in tear fluid is likely to be reflective of and contribute to a wide range of homeostatic processes. Understanding this relationship has been the subject of considerable attention, with much of the work particularly focused on the distribution of cytokines, chemokines, angiogenic modulators, and growth factors. The scope of the work is vast and is only partially referenced herein Most of these studies have used microwell plate ELISA protocols to obtain data. Sample size, assay sensitivity limits, and time and cost constraints have usually limited analysis to the measurement of one or a few proteins in individual or pooled tear samples. Integration of the accumulated data has been hindered by many interstudy variables, including differences in the methods of tear collection 1 and differences in the sensitivities among commercially available kits. Given the complexity of biological processes, it has long been recognized that it would be of great value if one could obtain differential data on a broad range of proteins in tear samples. Several methods of proteomics analysis have been explored with this objective in mind. These have included use of twodimensional (2-D) gel electrophoresis, coupled with matrixassisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), 30,31 MALDI analysis, 32 trypsin digestion with differential labeling followed by tandem mass spectrometry (MS-MS), and/or quadrupole time-of-flight (MALDI QqTOF-MS) analysis, 33 use of biochips coupled with surface-enhanced laser desorption/ionization-time of flight mass spectrometry (SELDI-TOF-MS) (Kitagawa K, et al. IOVS 2004;45:ARVO E-Abstract 83; Wirthlin A, et al. IOVS 2004;45: ARVO E-Abstract 3456) and HPLC separation using electrospray ionization-(ESI)-MS as the detector

A Molecular Rotor Possessing an H–M–H “Spoke” on a P–M–P “Axle”: A Platinum(II) <i>trans</i>-Dihydride Spins Rapidly Even at 75 K

A new class of low-barrier molecular rotors, metal <i>trans</i>-dihydrides, is suggested here. To test whether rapid rotation can be achieved, the known complex <i>trans</i>-H₂Pt­(P^<i>t</i>Bu₃)₂ was experimentally studied by ²H and ¹⁹⁵Pt solid-state NMR spectroscopy (powder pattern changes with temperature) and computationally modeled as a ^<i>t</i>Bu₃P–Pt–P^<i>t</i>Bu₃ stator with a spinning H–Pt–H rotator. Whereas the related chloro-hydride complex, <i>trans</i>-H­(Cl)­Pt­(P^<i>t</i>Bu₃)₂, does not show rotational behavior at room temperature, the dihydride <i>trans</i>-H₂Pt­(P^<i>t</i>Bu₃)₂ rotates fast on the NMR time scale, even at low temperatures down to at least 75 K. The highest barrier to rotation is estimated to be ∼3 kcal mol^–1, for the roughly 3 Å long rotator in <i>trans</i>-H₂Pt­(P^<i>t</i>Bu₃)₂