Sulfur K-Edge XAS and DFT Calculations on [Fe4S4]2+Clusters: Effects of H-bonding and Structural Distortion on Covalency and SpinTopology

Sulfur K-edge X-ray absorption spectroscopy of a hydrogen-bonded elongated [Fe{sub 4}S{sub 4}]{sup 2+} cube is reported. The data show that this synthetic cube is less covalent than a normal compressed cube with no hydrogen bonding. DFT calculations reveal that the observed difference in electronic structure has significant contributions from both the cluster distortion and from hydrogen bonding. The elongated and compressed Fe{sub 4}S{sub 4} structures are found to have different spin topologies (i.e., orientation of the delocalized Fe{sub 2}S{sub 2} subclusters which are antiferromagnetically coupled to each other). It is suggested that the H-bonding interaction with the counterion does not contribute to the cluster elongation. A magneto-structural correlation is developed for the Fe{sub 4}S{sub 4} cube that is used to identify the redoxactive Fe{sub 2}S{sub 2} subclusters in active sites of HiPIP and ferredoxin proteins involving these clusters

Technical Challenges for the Head-on Collisions and Extraction at the ILC

An interaction region with head-on collisions is considered as an alternative to the baseline ILC configuration. Progress in the final focus optics design includes engineered large bore superconducting final doublet magnets and their 3D magnetic integration in the detector solenoids. Progress on the beam separation optics is based on technical designs of electrostatic separator and special extraction quadrupoles. The spent beam extraction is realized by a staged collimation scheme relying on realistic collimators

Use of Gold Nanoparticles To Enhance Capillary Electrophoresis

We describe here the use of gold nanoparticles to manipulate the selectivity between solutes in capillary electrophoresis. Two different gold-based nanoparticles were added to the run buffer. In one case, the nanoparticles were stabilized with citrate ions, but in another study, the gold nanoparticles were capped with mercaptopropionate ions (thiol-stablized). Citrate-stabilized gold nanoparticles were used in conjunction with capillaries treated with poly(diallyldimethylammonium chloride) (PDADMAC). The positively charged PDADMAC layer on the capillary walls adsorbs the negatively charged gold nanoparticles. The model solutes that were used to study the effect of the presence of the citrate-stabilized gold nanoparticles are structural isomers of aromatic acids and bases. The presence of the PDADMAC layer and the PDADMAC plus the gold nanoparticles changes both the electroosmotic mobility and the observed mobility of the solutes. These changes in the mobilities influence the observed selectivities and the separations of the system. Thiol-stabilized gold nanoparticles were used without PDADMAC in the capillary. The model solutes studied in this part are various aromatic amines. In this case as well, the presence of the gold nanoparticles modifies the electroosmotic mobility and the observed mobility of the solutes. These changes in the mobilities are manifested in selectivity alterations. The largest change in the selectivities occurs at low concentrations of the gold nanoparticles in the run buffer. The presence of nanoparticles improves the precision of the analysis and increases the separation efficiency. Nanodispersions have attracted extensive attention in various fields of physics, biology, and chemistry. [1][2][3][4][5] Physicists and chemists are intrigued by the gradual transition of the nanomaterial properties from molecule-like to those of solid-state properties by a change of a single variable, the particle size. This property has practical and future applications for nonlinear optics and electronics. The large surface area of nanomaterials intrigues chemical engineers and catalysis scientists. Surprisingly, very little research has been devoted to the application of nanoparticles for chemical separation. In this work, we demonstrate the utility and versatility of organically modified gold nanoparticles in capillary electrophoresis (CE) separations. The nanoparticles serve as large surface area platforms for organofunctional groups that interact with the capillary surface, the analytes, or both. Thus, the apparent mobilities of target analytes, as well as the electroosmotic flow, can be altered leading to enhanced selectivities. Separation of various benzene derivatives demonstrates these capabilities. Metallic nanodispersions can be prepared in aqueous and organic solvents using diverse procedures. 1,2,6-9 Nanodispersions can be stabilized in organic solvents by the solvent itself, 10 by the addition of long chain surfactants, 11,12 or by specific ligands. 13 Stabilization of metal nanodispersions in aqueous solutions is somewhat more complicated. Several successful stabilization methods are available that are based on capping of the metal nanoparticles (e.g., citrate, 6 3-mercaptopropionate, 1

Broadband Coupling into a Single-Mode, Electroactive Integrated Optical Waveguide for Spectroelectrochemical Analysis of Surface-Confined Redox Couples

Pushing the sensitivity of spectroelectrochemical techniques to routinely monitor changes in spectral properties of thin molecular films (i.e., monolayer or submonolayer) adsorbed on an electrode surface has been a goal of many investigators since the earliest developments in this field. 1 It was initially recognized that exploiting the evanescent field generated by total internal reflection at the interface of an optically transparent electrode (such as a thin film of tin oxide or indium tin oxide (ITO) on glass or quartz) has the inherent advantage of selectively probing only the near-surface region, as opposed to bulk sampling with transmission based techniques. Furthermore, by utilizing the multiple reflections in an attenuated total reflectance (ATR) geometry, an enhancement in sensitivity can be realized, and as the thickness of the ATR element is decreased, the number of reflections increases, yielding a substantial sensitivity enhancement. [2][3][4][5][6] Itoh and Fujishima were the first to show the advantages of reducing the thickness of an ATR element overcoated with a transparent conductive oxide to the integrated optical waveguide (IOW) regime. Using a four-mode, gradient index waveguide coated with a transparent, conductive tin oxide layer, they demonstrated large sensitivity enhancements, relative to a single pass transmission experiment, for spectroelectrochemical measurements of methylene blue. 7,8 Other research groups subsequently described similar gradient index, multilayer, electroactive waveguide structures, but they did not make use of the technology to explore the spectroelectrochemistry of (sub)monolayer coverage films. [9][10][11][12][13] We recently described a single-mode, electroactive planar IOW (the EA-IOW) having a step refractive index profile. It was fabricated by sputtering a Corning 7059 glass layer (400 nm) over soda lime glass or quartz, followed by a 200-nm layer of SiO 2

Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990-2017: a systematic analysis for the Global Burden of Disease Study 2017

Background The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2017 comparative risk assessment (CRA) is a comprehensive approach to risk factor quantification that offers a useful tool for synthesising evidence on risks and risk–outcome associations. With each annual GBD study, we update the GBD CRA to incorporate improved methods, new risks and risk–outcome pairs, and new data on risk exposure levels and risk–outcome associations. Methods We used the CRA framework developed for previous iterations of GBD to estimate levels and trends in exposure, attributable deaths, and attributable disability-adjusted life-years (DALYs), by age group, sex, year, and location for 84 behavioural, environmental and occupational, and metabolic risks or groups of risks from 1990 to 2017. This study included 476 risk–outcome pairs that met the GBD study criteria for convincing or probable evidence of causation. We extracted relative risk and exposure estimates from 46 749 randomised controlled trials, cohort studies, household surveys, census data, satellite data, and other sources. We used statistical models to pool data, adjust for bias, and incorporate covariates. Using the counterfactual scenario of theoretical minimum risk exposure level (TMREL), we estimated the portion of deaths and DALYs that could be attributed to a given risk. We explored the relationship between development and risk exposure by modelling the relationship between the Socio-demographic Index (SDI) and risk-weighted exposure prevalence and estimated expected levels of exposure and risk-attributable burden by SDI. Finally, we explored temporal changes in risk-attributable DALYs by decomposing those changes into six main component drivers of change as follows: (1) population growth; (2) changes in population age structures; (3) changes in exposure to environmental and occupational risks; (4) changes in exposure to behavioural risks; (5) changes in exposure to metabolic risks; and (6) changes due to all other factors, approximated as the risk-deleted death and DALY rates, where the risk-deleted rate is the rate that would be observed had we reduced the exposure levels to the TMREL for all risk factors included in GBD 2017. Findings In 2017, 34·1 million (95% uncertainty interval [UI] 33·3–35·0) deaths and 1·21 billion (1·14–1·28) DALYs were attributable to GBD risk factors. Globally, 61·0% (59·6–62·4) of deaths and 48·3% (46·3–50·2) of DALYs were attributed to the GBD 2017 risk factors. When ranked by risk-attributable DALYs, high systolic blood pressure (SBP) was the leading risk factor, accounting for 10·4 million (9·39–11·5) deaths and 218 million (198–237) DALYs, followed by smoking (7·10 million [6·83–7·37] deaths and 182 million [173–193] DALYs), high fasting plasma glucose (6·53 million [5·23–8·23] deaths and 171 million [144–201] DALYs), high body-mass index (BMI; 4·72 million [2·99–6·70] deaths and 148 million [98·6–202] DALYs), and short gestation for birthweight (1·43 million [1·36–1·51] deaths and 139 million [131–147] DALYs). In total, risk-attributable DALYs declined by 4·9% (3·3–6·5) between 2007 and 2017. In the absence of demographic changes (ie, population growth and ageing), changes in risk exposure and risk-deleted DALYs would have led to a 23·5% decline in DALYs during that period. Conversely, in the absence of changes in risk exposure and risk-deleted DALYs, demographic changes would have led to an 18·6% increase in DALYs during that period. The ratios of observed risk exposure levels to exposure levels expected based on SDI (O/E ratios) increased globally for unsafe drinking water and household air pollution between 1990 and 2017. This result suggests that development is occurring more rapidly than are changes in the underlying risk structure in a population. Conversely, nearly universal declines in O/E ratios for smoking and alcohol use indicate that, for a given SDI, exposure to these risks is declining. In 2017, the leading Level 4 risk factor for age-standardised DALY rates was high SBP in four super-regions: central Europe, eastern Europe, and central Asia; north Africa and Middle East; south Asia; and southeast Asia, east Asia, and Oceania. The leading risk factor in the high-income super-region was smoking, in Latin America and Caribbean was high BMI, and in sub-Saharan Africa was unsafe sex. O/E ratios for unsafe sex in sub-Saharan Africa were notably high, and those for alcohol use in north Africa and the Middle East were notably low. Interpretation By quantifying levels and trends in exposures to risk factors and the resulting disease burden, this assessment offers insight into where past policy and programme efforts might have been successful and highlights current priorities for public health action. Decreases in behavioural, environmental, and occupational risks have largely offset the effects of population growth and ageing, in relation to trends in absolute burden. Conversely, the combination of increasing metabolic risks and population ageing will probably continue to drive the increasing trends in non-communicable diseases at the global level, which presents both a public health challenge and opportunity. We see considerable spatiotemporal heterogeneity in levels of risk exposure and risk-attributable burden. Although levels of development underlie some of this heterogeneity, O/E ratios show risks for which countries are overperforming or underperforming relative to their level of development. As such, these ratios provide a benchmarking tool to help to focus local decision making. Our findings reinforce the importance of both risk exposure monitoring and epidemiological research to assess causal connections between risks and health outcomes, and they highlight the usefulness of the GBD study in synthesising data to draw comprehensive and robust conclusions that help to inform good policy and strategic health planning

DNA cleavage function of seryl-histidine dipeptide and its application

The double-stranded DNA or circular plasmid DNA can be cleaved by the Ser-His dipeptide by hydrolysis of the DNA-phospho-diester bond. The proper sequential order of the amino acids serine and histidine is apparently crucial in its unique cleavage activity as compared to the other di- or tri-peptides containing one of these amino acids. An inverted sequence of this dipeptide to a His-Ser linkage renders the peptide ineffective in the cleavage of DNA. In addition to the DNA cleavage function, Ser-His is also capable of cleaving other molecules, e.g., proteins, esters and RNAs. The cooperative actions of the hydroxyl group and the basic groups in the serine and histidine or related amino acids can be found in contemporary enzymes, such as DNase, serine proteases, lipases, esterases, chymotrypsin, trypsin, and elastase, etc. The Ser-His and related oligopeptides might have played important roles in the evolution of enzyme functions.National Natural Science Foundation of China [20132020, 20572061]; Tsinghua University ; Xiamen Universit