Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

CO₂ Reduction on Cu at Low Overpotentials with Surface-Enhanced in Situ Spectroscopy

In situ surface-enhanced spectroscopic and reactivity investigations of the electrochemical reduction of CO₂ at low overpotentials (<0.7 V) was conducted on Cu surfaces. Vibrational bands corresponding to adsorbed hydrogen (H_ad) and carbon monoxide (CO_ad) on Cu have been identified at 2090 and 2060 cm^–1, respectively. Spectroscopic investigations show that H_ad is capable of partially displacing CO_ad; however, CO_ad is unable to displace H_ad to any detectable level. The preferential adsorption of H over CO on Cu is consistent with the high selectivity toward the hydrogen evolution reaction at potentials >−0.8 V versus reversible hydrogen electrode

In Situ Infrared Spectroscopic Investigations of Pyridine-Mediated CO₂ Reduction on Pt Electrocatalysts

Pyridine-mediated electrochemical reduction of CO₂ has attracted much attention owing to the promise of producing valuable oxygenates with high yields. However, no detectable level of methanol was observed in the pyridine-mediated CO₂ electrolysis on Pt over the entire potential range investigated (−0.2 to −0.8 V vs RHE) in this study. Formate was observed at a potential below −0.6 V vs RHE in the absence and presence of pyridine, but the presence of pyridine does accelerate the rate of formate production. Numerous reaction mechanisms have been proposed on the basis of reactivity measurements, cyclic voltammetry, or computational methods; however, a direct experimental mechanistic investigation has been lacking. By employing surface-enhanced infrared absorption spectroscopy, we identified an adsorbed unidentate COOH_L intermediate on Pt regardless of the presence of pyridine. Surface coverage of the COOH_L intermediate relative to that of adsorbed CO appears to increase with the concentration of pyridine in the electrolyte, which is consistent with the observed production rates for formate and CO. We propose that adsorbed COOH_L is a common intermediate in the formation of both formate and CO, and the presence of pyridinium promotes the formate pathway

Examination of Near-Electrode Concentration Gradients and Kinetic Impacts on the Electrochemical Reduction of CO₂ using Surface-Enhanced Infrared Spectroscopy

Localized concentration gradients within the electrochemical double layer during various electrochemical processes can have wide-ranging impacts; however, experimental investigation to quantitatively correlate the rate of surface-mediated electrochemical reaction with the interfacial species concentrations has historically been lacking. In this work, we demonstrate a spectroscopic method for the in situ determination of the surface pH using the CO₂ reduction reaction as a model system. Attenuated total reflectance surface-enhanced infrared absorption spectroscopy is employed to monitor the ratio of vibrational bands of carbonate and bicarbonate as a function of electrode potential. Integrated areas of vibrational bands are then compared with those obtained from calibration spectra collected in electrolytes with known pH values to determine near-electrode proton concentrations. Experimentally determined interfacial proton concentrations are then related to the resultant concentration overpotentials to examine their impact on electrokinetics. We show that, in CO₂-saturated sodium bicarbonate solutions, a concentration overpotential of over 150 mV can be induced during electrolysis at −1.0 V vs RHE, leading to substantial losses in energy efficiency. We also show that increases in both convection and buffering capacity of the electrolyte can mitigate interfacial concentration gradients. On the basis of these results, we further discuss how increases in concentration overpotential affect the mechanistic interpretations of the CO₂ reduction electrocatalysis, particularly in terms of Tafel slopes and reaction orders

The Central Role of Bicarbonate in the Electrochemical Reduction of Carbon Dioxide on Gold

Much effort has been devoted in the development of efficient catalysts for electrochemical reduction of CO₂. Molecular level understanding of electrode-mediated process, particularly the role of bicarbonate in increasing CO₂ reduction rates, is still lacking due to the difficulty of directly probing the electrochemical interface. We developed a protocol to observe normally invisible reaction intermediates with a surface enhanced spectroscopy by applying square-wave potential profiles. Further, we demonstrate that bicarbonate, through equilibrium exchange with dissolved CO₂, rather than the supplied CO₂, is the primary source of carbon in the CO formed at the Au electrode by a combination of in situ spectroscopic, isotopic labeling, and mass spectroscopic investigations. We propose that bicarbonate enhances the rate of CO production on Au by increasing the effective concentration of dissolved CO₂ near the electrode surface through rapid equilibrium between bicarbonate and dissolved CO₂

High Capacity MoO₂/Graphite Oxide Composite Anode for Lithium-Ion Batteries

Nanostructured MoO₂/graphite oxide (GO) composites are synthesized by a simple solvothermal method. X-ray diffraction and transmission electron microscopy analyses show that with the addition of GO and the increase in GO content in the precursor solutions, MoO₃ rods change to MoO₂ nanorods and then further to MoO₂ nanoparticles, and the nanorods or nanoparticles are uniformly distributed on the surface of the GO sheets in the composites. The MoO₂/GO composite with 10 wt % GO exhibits a reversible capacity of 720 mAh/g at a current density of 100 mA/g and 560 mAh/g at a high current density of 800 mA/g after 30 cycles. The improved reversible capacity, rate capacity, and cycling performance of the composites are attributed to synergistic reaction between MoO₂ and GO