Electrochemical Insertion/extraction of Lithium in Multiwall Carbon Nanotube/Sb and SnSb₀.₅ Nanocomposites

Multiwall carbon nanotubes (CNTs) were synthesized by catalytic chemical vapor deposition of acetylene and used as templates to prepare CNT-Sb and CNT-SnSb₀.₅ nanocomposites via the chemical reduction of SnCl₂ and SbCl₃ precursors. SEM and TEM imagings show that the Sb and SnSb₀.₅ particles were uniformly dispersed in the CNT web and on the outside surface of CNTs. These CNT-metal composites are active anode materials for lithium ion batteries, showing improved cyclability compared to unsupported Sb and SnSb particles; and higher reversible specific capacities than CNTs. The improvement in cyclability may be attributed to the nanoscale dimensions of the metal particles and CNT’s role as a buffer in containing the mechanical stress arising from the volume changes in electrochemical lithium insertion and extraction reactions.Singapore-MIT Alliance (SMA

Preparation of PtNi Nanoparticles for the Electrocatalytic Oxidation of Methanol

Carbon supported PtNi nanoparticles were prepared by hydrazine reduction of Pt and Ni precursor salts under different conditions, namely by conventional heating (PtNi-1), by prolonged reaction at room temperature (PtNi-2) and by microwave assisted reduction (PtNi-3). The nanocomposites were characterized by XRD, EDX, XPS and TEM and used as electrocatalysts in direct methanol fuel cell (DMFC) reactions. Investigations into the mechanism of PtNi nanoparticle formation revealed that platinum nanoparticle seeding was essential for the formation of the bimetallic nanoparticles. The average particle size of PtNi prepared by microwave irradiation was the lowest, in the range of 2.9 – 5.8 nm. The relative rates of electrooxidation of methanol at room temperature as measured by cyclic voltammetry showed an inverse relationship between catalytic activity and particle size in the following order PtNi-1 < PtNi-2 < PtNi-3.Singapore-MIT Alliance (SMA

Identifying Protein-Protein Interactions of DDX41 by BioID

Helicases are known as enzymes that separate double-stranded(ds) nucleic acids to single-strand(ss) nucleic acids by hydrolysis ATP; and some of them also can anneal ss nucleic acids to ds nucleic acids in an ATP-independent manner. DEAD-box helicases are characterized by containing an Asp-Glu-Ala-Asp (DEAD) sequence in their motif II that is required for ATP binding and hydrolysis. DEAD-box helicase 41 (DDX41) is a member of DEAD-box helicases with multiple functions, including acting as a sensor for intracellular DNA in myeloid dendritic cells1 and for bacterial secondary messengers (c-di-GMP or c-di-AMP) to trigger type 1 interferon production2. Recently, the Dr. Wu’s lab discovered that DDX41 modulates the balance of dsDNA and ssDNA, in which regulates the activation of the cyclic GMP–AMP synthase (cGAS)3. Mutations in DDX41 are linked with myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML)4, two blood caners. The most recurring mutation in DDX41 that lead to AML or MDS is c.1574G>A (p.R525H). Despite concrete evidence suggests that DDX41 acts as a DNA sensor in innate immunity5,6; no innate immunity-related protein has been identified as a DDX41-binding partner. Therefore, we established a BioID system to identify DDX41-biniding proteins under virus infections

Cardiac Toxicity of HER2-Directed Therapy in Women with Breast Cancer: Epidemiology, Etiology, Risk Factors, and Management

The HER2-targeted therapy have profoundly changed the outcomes of women with HER2-positive breast cancers. Trastuzumab and pertuzumab, HER2-targeting monoclonal antibodies, lapatinib and Neratinib, small molecule inhibitors of HER2 and the epidermal growth factor receptor, and ado-trastuzumab emtansine, a HER2-positive directed antibody drug conjugate, are approved for the treatment of HER2-positive breast cancer

A Dual Spring Modeling Approach for Static and Fatigue Failure Assessments of Carbon/Epoxy Composite Sub-Elements

A dual spring model is developed for the static and fatigue damage predictions of laminates interface in composite structures. Stress concentrations can be induced by the defects formed in the fabrication or service process. A conventional S-N based fatigue damage model may not be accurate to predict the fatigue life of a structure with high stress concentration. With the dual spring model, static delamination failure can be simulated using springs of cohesive type material model while fatigue delamination development can be predicted using linear springs, where the crack driving force is computed based on virtual crack closure technique (VCCT). A Paris law type fatigue growth law with its mode mixity is applied for fatigue crack growth prediction. After verified using benchmark examples, including Double Cantilever Beam (DCB), End-Notched Flexure (ENF) and Mix-Mode Bending (MMB), the proposed dual spring model is applied in the static and fatigue damage prediction of NASA/Boeing sub-elements and UTC sub-elements

Two-dimensional silk

The ability to form silk films on semiconductors, metals, and oxides or as free-standing membranes has motivated research into silk-based electronic, optical, and biomedical devices. However, the inherent disorder of native silk limits device performance. Here we report the creation of highly ordered two-dimensional (2D) silk fibroin (SF) layers on van der Waals solids. Using in situ atomic force microscopy, synchrotron-based infrared spectroscopy, and molecular dynamics simulations, we develop a mechanistic understanding of the assembly process. We show that the films consist of lamellae having an epitaxial relationship with the underlying lattice and that the SF molecules exhibit the same Beta-sheet secondary structure seen in the crystallites of the native form. By increasing the SF concentration, multilayer films form via layer-by-layer growth, either along a classical pathway in which SF molecules assemble directly into the lamellae or, at sufficiently high concentrations, along a two-step pathway beginning with formation of a disordered monolayer that subsequently converts into the crystalline phase. Kelvin probe measurements show that these 2D SF layers substantially alter the surface potential. Moreover, the ability to assemble 2D silk on both graphite and MoS2 suggests that it may provide a general platform for silk-based electronics on vdW solids

Halide-guided active site exposure in bismuth electrocatalysts for selective CO2 conversion into formic acid

It remains a challenge to identify the active sites of bismuth catalysts in the electrochemical CO2 reduction reaction. Here we show through in situ characterization that the activation of bismuth oxyhalide electrocatalysts to metallic bismuth is guided by the halides. In situ X-ray diffraction results show that bromide promotes the selective exposure of planar bismuth surfaces, whereas chloride and iodide result in more disordered active sites. Furthermore, we find that bromide-activated bismuth catalysts outperform the chloride and iodide counterparts, achieving high current density (>100 mA cm–2) and formic acid selectivity (>90%), suggesting that planar bismuth surfaces are more active for the electrochemical CO2 reduction reaction. In addition, in situ X-ray absorption spectroscopy measurements reveal that the reconstruction proceeds rapidly in chloride-activated bismuth and gradually when bromide is present, facilitating the formation of ordered planar surfaces. These findings show the pivotal role of halogens on selective facet exposure in activated bismuth-based electrocatalysts during the electrochemical CO2 reduction reaction. [Figure not available: see fulltext.

An integrative view of the regulatory and transcriptional landscapes in mouse hematopoiesis.

Thousands of epigenomic data sets have been generated in the past decade, but it is difficult for researchers to effectively use all the data relevant to their projects. Systematic integrative analysis can help meet this need, and the VISION project was established for validated systematic integration of epigenomic data in hematopoiesis. Here, we systematically integrated extensive data recording epigenetic features and transcriptomes from many sources, including individual laboratories and consortia, to produce a comprehensive view of the regulatory landscape of differentiating hematopoietic cell types in mouse. By using IDEAS as our integrative and discriminative epigenome annotation system, we identified and assigned epigenetic states simultaneously along chromosomes and across cell types, precisely and comprehensively. Combining nuclease accessibility and epigenetic states produced a set of more than 200,000 candidate cis-regulatory elements (cCREs) that efficiently capture enhancers and promoters. The transitions in epigenetic states of these cCREs across cell types provided insights into mechanisms of regulation, including decreases in numbers of active cCREs during differentiation of most lineages, transitions from poised to active or inactive states, and shifts in nuclease accessibility of CTCF-bound elements. Regression modeling of epigenetic states at cCREs and gene expression produced a versatile resource to improve selection of cCREs potentially regulating target genes. These resources are available from our VISION website to aid research in genomics and hematopoiesis.National Institute of Diabetes and Digestive and Kidney Diseases (grant number R24DK106766-01A1), the National Human Genome Research Institute (grant number U54HG006998

Integrated rocksalt–polyanion cathodes with excess lithium and stabilized cycling

Co- and Ni-free disordered rocksalt cathodes utilize oxygen redox to increase the energy density of lithium-ion batteries, but it is challenging to achieve good cycle life at high voltages &gt;4.5 V (versus Li/Li+). Here we report a family of Li-excess Mn-rich cathodes that integrates rocksalt- and polyanion-type structures. Following design rules for cation filling and ordering, we demonstrate the bulk incorporation of polyanion groups into the rocksalt lattice. This integration bridges the two primary families of lithium-ion battery cathodes—layered/spinel and phosphate oxides—dramatically enhancing the cycling stability of disordered rocksalt cathodes with 4.8 V upper cut-off voltage. The cathode exhibits high gravimetric energy densities above 1,100 Wh kg−1 and &gt;70% retention over 100 cycles. This study opens up a broad compositional space for developing battery cathodes using earth-abundant elements such as Mn and Fe

Volume-based solvation models out-perform area-based models in combined studies of wild-type and mutated protein-protein interfaces

<p>Abstract</p> <p>Background</p> <p>Empirical binding models have previously been investigated for the energetics of protein complexation (ΔG models) and for the influence of mutations on complexation (i.e. differences between wild-type and mutant complexes, ΔΔG models). We construct binding models to directly compare these processes, which have generally been studied separately.</p> <p>Results</p> <p>Although reasonable fit models were found for both ΔG and ΔΔG cases, they differ substantially. In a dataset curated for the absence of mainchain rearrangement upon binding, non-polar area burial is a major determinant of ΔG models. However this ΔG model does not fit well to the data for binding differences upon mutation. Burial of non-polar area is weighted down in fitting of ΔΔG models. These calculations were made with no repacking of sidechains upon complexation, and only minimal packing upon mutation. We investigated the consequences of more extensive packing changes with a modified mean-field packing scheme. Rather than emphasising solvent exposure with relatively extended sidechains, rotamers are selected that exhibit maximal packing with protein. This provides solvent accessible areas for proteins that are much closer to those of experimental structures than the more extended sidechain regime. The new packing scheme increases changes in non-polar burial for mutants compared to wild-type proteins, but does not substantially improve agreement between ΔG and ΔΔG binding models.</p> <p>Conclusion</p> <p>We conclude that solvent accessible area, based on modelled mutant structures, is a poor correlate for ΔΔG upon mutation. A simple volume-based, rather than solvent accessibility-based, model is constructed for ΔG and ΔΔG systems. This shows a more consistent behaviour. We discuss the efficacy of volume, as opposed to area, approaches to describe the energetic consequences of mutations at interfaces. This knowledge can be used to develop simple computational screens for binding in comparative modelled interfaces.</p