Macrolide-Peptide Conjugates as Probes of the Path of Travel of the Nascent Peptides through the Ribosome
Abstract not provided
Washington, Arren Z.↗
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Mechanism of Cellulose Hydrolysis by a Two-Step, Retaining Cellobiohydrolase Elucidated by Structural and Transition Path Sampling Studies
Abstract not provided
09 BIOMASS FUELS↗
The Molecular Path Approaching the Active Site in Catalytic Metal–Organic Frameworks
How molecules approach, bind at, and release from catalytic sites is key to heterogeneous catalysis, including for emerging metal-organic framework (MOF)-based catalysts. Here, we use in situ synchrotron X-ray scattering analysis to evaluate the dominant binding sites for reagent and product molecules in the vicinity of catalytic Ni-oxo clusters in NU-1000 with different surface functionalization under conditions approaching those used in catalysis. The locations of the reagent and product molecules within the pores can be linked to the activity for ethylene hydrogenation. For the most active catalyst, ethylene reagent molecules bind close to the catalytic clusters, but only at temperatures approaching experimentally observed onset of catalysis. The ethane product molecules favor a different binding location suggesting that the product is readily released from the active site. An unusual guest-dependence of the framework negative thermal expansion is documented. We hypothesize that reagent and product binding sites reflect the pathway through the MOF to the active site and can be used to identify key factors that impact the catalytic activity.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
New Paths in Geoengineering
National Center for Atmospheric Research Fifth Annual Geoengineering Model Intercomparison Workshop and Early Career Summer School; Boulder, Colorado, 20–24 July 2015
54 ENVIRONMENTAL SCIENCES↗
RNA degradation paths in a 12-subunit nuclear exosome complex
Abstract not provided
Makino, Debora Lika↗
The path towards sustainable energy
Civilization continues to be transformed by our ability to harness energy beyond human and animal power. A series of industrial and agricultural revolutions have allowed an increasing fraction of the world population to heat and light their homes, fertilize and irrigate their crops, connect to one another and travel around the world. All of this progress is fuelled by our ability to find, extract and use energy with ever increasing dexterity. Lastly, research in materials science is contributing to progress towards a sustainable future based on clean energy generation, transmission and distribution, the storage of electrical and chemical energy, energy efficiency, and better energy management systems.
29 ENERGY PLANNING, POLICY, AND ECONOMY↗
Integrative genomics reveals paths to sex dimorphism in Salix purpurea L
Sex dimorphism and gene expression were studied in developing catkins in 159 F 2 individuals from the bioenergy crop Salix purpurea , and potential mechanisms and pathways for regulating sex development were explored. Differential expression, eQTL, bisulfite sequencing, and network analysis were used to characterize sex dimorphism, detect candidate master regulator genes, and identify pathways through which the sex determination region (SDR) may mediate sex dimorphism. Eleven genes are presented as candidates for master regulators of sex, supported by gene expression and network analyses. These include genes putatively involved in hormone signaling, epigenetic modification, and regulation of transcription. eQTL analysis revealed a suite of transcription factors and genes involved in secondary metabolism and floral development that were predicted to be under direct control of the sex determination region. Furthermore, data from bisulfite sequencing and small RNA sequencing revealed strong differences in expression between males and females that would implicate both of these processes in sex dimorphism pathways. These data indicate that the mechanism of sex determination in Salix purpurea is likely different from that observed in the related genus Populus . This further demonstrates the dynamic nature of SDRs in plants, which involves a multitude of mechanisms of sex determination and a high rate of turnover.
59 BASIC BIOLOGICAL SCIENCES↗
Atomic order of rare earth ions in a complex oxide: a path to magnetotaxial anisotropy
Abstract Complex oxides offer rich magnetic and electronic behavior intimately tied to the composition and arrangement of cations within the structure. Rare earth iron garnet films exhibit an anisotropy along the growth direction which has long been theorized to originate from the ordering of different cations on the same crystallographic site. Here, we directly demonstrate the three-dimensional ordering of rare earth ions in pulsed laser deposited (Eu x Tm 1-x ) 3 Fe 5 O 12 garnet thin films using both atomically-resolved elemental mapping to visualize cation ordering and X-ray diffraction to detect the resulting order superlattice reflection. We quantify the resulting ordering-induced ‘magnetotaxial’ anisotropy as a function of Eu:Tm ratio using transport measurements, showing an overwhelmingly dominant contribution from magnetotaxial anisotropy that reaches 30 kJ m −3 for garnets with x = 0.5. Control of cation ordering on inequivalent sites provides a strategy to control matter on the atomic level and to engineer the magnetic properties of complex oxides.
Science & Technology - Other Topics↗
An improved symmetry-based approach to reciprocal space path selection in band structure calculations
Not Available
36 MATERIALS SCIENCE↗
Photonic curing of solution-deposited ZrO 2 dielectric on PEN: a path towards high-throughput processing of oxide electronics
High-throughput manufacturing of oxide electronics will enable new applications ranging from large-area displays to flexible medical devices and low-cost solar panels. However, high quality oxide films from solution-based precursors typically require 20 minutes or more of thermal annealing at high temperature (> 250 °C) for each layer, severely limiting both the throughput and substrate choice. Here, we report high speed photonic curing of ZrO 2 dielectric thin films on flexible plastic substrates. The curing and patterning processes can be achieved simultaneously by using shadow mask patterning or adjusting conditions to convert oxide only on top of underlying metal contacts, i.e. self-aligned patterning. Metal-insulator-metal capacitors using two layers of ZrO 2 films photonically cured in just 100 seconds per layer show non-dispersive capacitance-frequency behavior from 10 2 to 10 6 Hz, high areal capacitance of 200 nF/cm 2 and low dissipation factor of 0.03 at 10 5 Hz, leakage current density of ~ 10 -7 A/cm 2 at an applied field of 2 MV/cm, and a breakdown field of nearly 8 MV/cm. Using an upgraded tool, similar dielectric properties are achieved in as short as 100 milliseconds using a single pulse of light, revealing a pathway to oxide film processing beyond 30 m/min.
14 SOLAR ENERGY↗
The path to 1.5 °C requires ratcheting of climate pledges
Using model simulations of high-ambition emissions pathways, we show that ratcheting—or increasing—climate ambition through 2030 will be crucial to limiting global peak temperature changes this century. Although updated pledges offered in advance of the Glasgow climate conference in 2021 meaningfully strengthened global ambition in 2030 compared to the 2015 Paris pledges, here, our study underscores the importance of countries ratcheting their 2030 pledges further to reduce the magnitude of temperature overshoot and consequently reduce the risks of irreversible and adverse consequences to natural and human systems.
54 ENVIRONMENTAL SCIENCES↗
A direct thin-film path towards low-cost large-area III-V photovoltaics
III-V photovoltaics (PVs) have demonstrated the highest power conversion efficiencies for both single- and multi-junction cells. However, expensive epitaxial growth substrates, low precursor utilization rates, long growth times, and large equipment investments restrict applications to concentrated and space photovoltaics (PVs). Here, we demonstrate the first vapor-liquid-solid (VLS) growth of high-quality III-V thin-films on metal foils as a promising platform for large-area terrestrial PVs overcoming the above obstacles. We demonstrate 1–3 mm thick InP thin-films on Mo foils with ultra-large grain size up to 100 mm, which is ,100 times larger than those obtained by conventional growth processes. The films exhibit electron mobilities as high as 500 cm2 /V-s and minority carrier lifetimes as long as 2.5 ns. Furthermore, under 1-sun equivalent illumination, photoluminescence efficiency measurements indicate that an open circuit voltage of up to 930 mV can be achieved, only 40 mV lower than measured on a single crystal reference wafer.
14 SOLAR ENERGY↗
A path to practical Solar Pumped Lasers via Radiative Energy Transfer
The optical conversion of incoherent solar radiation into a bright, coherent laser beam enables the application of nonlinear optics to solar energy conversion and storage. Here, we present an architecture for solar pumped lasers that uses a luminescent solar concentrator to decouple the conventional trade-off between solar absorption efficiency and the mode volume of the optical gain material. We report a 750-μm-thick Nd 3+ -doped YAG planar waveguide sensitized by a luminescent CdSe/CdZnS (core/shell) colloidal nanocrystal, yielding a peak cascade energy transfer of 14%, a broad spectral response in the visible portion of the solar spectrum, and an equivalent quasi-CW solar lasing threshold of 23 W-cm -2 , or approximately 230 suns. The efficient coupling of incoherent, spectrally broad sunlight in small gain volumes should allow the generation of coherent laser light from intensities of less than 100 suns.
14 SOLAR ENERGY↗
Multi-path variational transition state theory for chiral molecules: the site-dependent kinetics for abstraction of hydrogen from 2-butanol by hydroperoxyl radical, analysis of hydrogen bonding in the transition state, and dramatic temperature dependence of the activation energy
A hydrogen bond at the transition state can lower the enthalpy of activation, but raise the free energy of activation.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
A beam path-based method for attenuation correction of confocal micro-X-ray fluorescence imaging data
The attenuated intensity was corrected using the Beer–Lambert law for each pixel by considering sample heterogeneity and confocal setup geometry.
Liu, Peng↗
Blocking like it's hot: a synthetic chemists’ path to high-temperature lanthanide single molecule magnets
Progress in the synthesis, design, and characterisation of single-molecule magnets (SMMs) has expanded dramatically from curiosity driven beginnings to molecules that retain magnetization above the boiling point of liquid nitrogen. This is in no small part due to the increasingly collaborative nature of this research where synthetic targets are guided by theoretical design criteria. This article aims to summarize these efforts and progress from the perspective of a synthetic chemist with a focus on how chemistry can modulate physical properties. Here, a simple overview is presented of lanthanide electronic structure in order to contextualize the synthetic advances that have led to drastic improvements in the performance of lanthanide-based SMMs from the early 2000s to the late 2010s.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Machine learning to tame divergent density functional approximations: a new path to consensus materials design principles
Machine learning (ML)-based feature analysis reveals universal design rules regardless of density functional choices. Using the consensus among multiple functionals, we identify robust lead complexes in ML-accelerated chemical discovery.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗