Multiple charge density wave transitions in Gd2Te5

Diffraction measurements performed via transmission electron microscopy and high resolution X-ray scattering reveal two distinct charge density wave transitions in Gd{sub 2}Te{sub 5} at T{sub c1} = 410(3) and T{sub c2} = 532(3) K, associated with the on-axis incommensurate lattice modulation and off-axis commensurate lattice modulation respectively. Analysis of the temperature dependence of the order parameters indicates a non-vanishing coupling between these two distinct CDW states

Pressure-induced quenching of the charge-density-wave state observed by x-ray diffraction

We report an x-ray diffraction study on the charge-density-wave (CDW) LaTe$_3$ and CeTe$_3$ compounds as a function of pressure. We extract the lattice constants and the CDW modulation wave-vector, and provide direct evidence for a pressure-induced quenching of the CDW phase. We observe subtle differences between the chemical and mechanical compression of the lattice. We account for these with a scenario where the effective dimensionality in these CDW systems is dependent on the type of lattice compression and has a direct impact on the degree of Fermi surface nesting and on the strength of fluctuation effects

Spectroscopic and Mechanistic Studies of Heterodimetallic Forms of Metallo-β-lactamase NDM-1

In an effort to characterize the roles of each metal ion in metallo-β-lactamase NDM-1, heterodimetallic analogues (CoCo-, ZnCo-, and CoCd-) of the enzyme were generated and characterized. UV–vis, 1H NMR, EPR, and EXAFS spectroscopies were used to confirm the fidelity of the metal substitutions, including the presence of a homogeneous, heterodimetallic cluster, with a single-atom bridge. This marks the first preparation of a metallo-β-lactamase selectively substituted with a paramagnetic metal ion, Co(II), either in the Zn1 (CoCd-NDM-1) or in the Zn2 site (ZnCo-NDM-1), as well as both (CoCo-NDM-1). We then used these metal-substituted forms of the enzyme to probe the reaction mechanism, using steady-state and stopped-flow kinetics, stopped-flow fluorescence, and rapid-freeze-quench EPR. Both metal sites show significant effects on the kinetic constants, and both paramagnetic variants (CoCd- and ZnCo-NDM-1) showed significant structural changes on reaction with substrate. These changes are discussed in terms of a minimal kinetic mechanism that incorporates all of the data

Characterization of surface Ag nanoparticles in nanocomposite a-C:Ag coatings by grazing incidence X-ray diffraction at sub-critical angles of incidence

Silver diffusion within nanocomposite films and/or toward the film surface is often observed during annealing of the silver-based nanocomposite films. In order to control and/or minimize this process, it is crucial to characterize the aggregated silver nanoparticles on the films surface. In this paper grazing incidence X-ray diffraction (GIXRD) with both sub-critical and supra-critical angles of incidence is used to characterize the Ag nanoparticles distribution, shape and structure both inside the matrix and on the nanocomposite film surface. The nanocomposite carbon coating containing Ag nanoparticles (a-C:Ag) was deposited by dc magnetron sputtering. The coatings were analyzed by GIXRD using fixed incident angles both below and above the critical angle for total reflection. By using sub-critical angles it was possible to eliminate diffraction from the bulk material allowing to estimate the size distribution of the nanoparticles sitting on the surface. The results obtained by GIXRD analysis were checked through comparison with the observations made by both TEM and SEM analysis. The proposed methodology can be used to characterized nanoparticles deposition on a surface and/or island formation during film growth as long an adequate substrate with high critical angle for total reflection is used.We gratefully acknowledge the financial support provided by the FCT—Fundação para a Ciência e Tecnologia and FSE for the grant SFRH/BD/82472/2011. This research is sponsored by the FEDER funds through the program COMPETE—Programa Operacional Factores de Competitividade and by the national funds through FCT—Fundação para a Ciência e Tecnologia in the framework of the Strategic Projects PEST C/EME/UIO0285/2011

Assay platform for clinically relevant metallo-beta-lactamases

Metallo-β-lactamases (MBLs) are a growing threat to the use of almost all clinically used β-lactam antibiotics. The identification of broad-spectrum MBL inhibitors is hampered by the lack of a suitable screening platform, consisting of appropriate substrates and a set of clinically relevant MBLs. We report procedures for the preparation of a set of clinically relevant metallo-β-lactamases (i.e., NDM-1 (New Delhi MBL), IMP-1 (Imipenemase), SPM-1 (São Paulo MBL), and VIM-2 (Verona integron-encoded MBL)) and the identification of suitable fluorogenic substrates (umbelliferone-derived cephalosporins). The fluorogenic substrates were compared to chromogenic substrates (CENTA, nitrocefin, and imipenem), showing improved sensitivity and kinetic parameters. The efficiency of the fluorogenic substrates was exemplified by inhibitor screening, identifying 4-chloroisoquinolinols as potential pan MBL inhibitors

Efficacy of different strategies to treat anemia in children: a randomized clinical trial

<p>Abstract</p> <p>Background</p> <p>Anemia continues to be a major public health problem among children in many regions of the world, and it is still not clear which strategy to treat it is most effective.</p> <p>Objective</p> <p>To evaluate the efficacy and children's acceptance of several recognized strategies to treat anemia.</p> <p>Methods</p> <p>Non-breastfed children (n = 577), 6 to 43 mo of age, were screened for the trial; 267 were anemic (hemoglobin < 11.7 g/dL), and 266 of those were randomized into 1 of 5 treatments to received daily either: an iron supplement (IS), an iron+folic acid supplement (IFS), a multiple micronutrient supplement (MMS), a micronutrient-fortified complementary food as porridge powder (FCF), or zinc+iron+ascorbic acid fortified water (FW). The iron content of each daily dose was 20, 12.5, 10, 10 and 6.7 mg respectively. Hemoglobin (Hb), ferritin, total iron, weight and height were measured at baseline and after 4 months of treatment. Morbidity, treatment acceptability and adherence were recorded during the intervention.</p> <p>Results</p> <p>All treatments significantly increased Hb and total iron concentration; ferritin did not change significantly. Groups MMS, IS and IFS increased Hb (g/dL) [1.50 (95%CI: 1.17, 1.83), 1.48 [(1.18, 1.78) and 1.57 (1.26, 1.88), respectively] and total iron ((μg/dL) [0.15 (0.01, 0.29), 0.19 (0.06, 0.31) and 0.12(-0.01, 0.25), respectively] significantly more than FCF [0.92 (0.64, 1.20)] but not to FW group [0.14 (0.04, 0.24)]. The prevalence of anemia was reduced to a greater extent in the MMS and IFS groups (72% and 69%, respectively) than in the FCF group (45%) (p < 0.05). There were no significant differences in anthropometry or in the number of episodes of diarrhea and respiratory infections among treatment groups. The supplements MMS and IS were less acceptable to children, than IFS, FCF and FW.</p> <p>Conclusion</p> <p>The three supplements IS, ISF and MMS increased Hb more than the FCF; the supplements that contained micronutrients (IFS and MMS) were more effective for reducing the prevalence of anemia. In general, fortified foods were better accepted by the study participants than supplements.</p> <p>ClinicalTrial.gov Identifier</p> <p>NCT00822380</p

Density Distribution in the Liquid Hg-Sapphire Interface

We present the results of a computer simulation study of the liquid density distribution normal to the interface between liquid Hg and the reconstructed (0001) face of sapphire. The simulations are based on an extension of the self-consistent quantum Monte Carlo scheme previously used to study the structure of the liquid metal-vapor interface. The calculated density distribution is in very good agreement with that inferred from the recent experimental data of Tamam et al (J. Phys. Chem. Lett. 1, 1041-1045 (2010)). We conclude that, to account for the difference in structure between the liquid Hg-vapor and liquid-Hg-reconstructed (0001) Al2O3 interfaces, it is not necessary assume there is charge transfer from the Hg to the Al2O3. Rather, the available experimental data are adequately reproduced when the van der Waals interactions of the Al and O atoms with Hg atoms and the exclusion of electron density from Al2O3 via repulsion of the electrons from the closed shells of the ions in the solid are accounted for.Comment: 26 pages, 11 figure