Publications

A method for the solidification of metallic alloys involving spiral self‐organization is presented as a new strategy for producing large‐area chiral patterns with emergent structural and optical properties, with attention to the underlying mechanism and dynamics. This study reports the discovery of a new growth mode for metastable, two‐phase spiral patterns from a liquid metal. Crystallization proceeds via a non‐classical, two‐step pathway consisting of the initial formation of a polytetrahedral seed crystal, followed by ordering of two solid phases that nucleate heterogeneously on the seed and grow in a strongly coupled fashion. Crystallographic defects within the seed provide a template for spiral self‐organization. These observations demonstrate the ubiquity of defect‐mediated growth in multi‐phase materials and establish a pathway toward bottom‐up synthesis of chiral materials with an inter‐phase spacing comparable to the wavelength of infrared light. Given that liquids often possess polytetrahedral short‐range order, our results are applicable to many systems undergoing multi‐step crystallization.

<strong class="journal-contentHeaderColor">Abstract.</strong> <span id="page3610"/>Methane (CH<span class="inline-formula">₄</span>) emissions from natural landscapes constitute roughly half of global CH<span class="inline-formula">₄</span> contributions to the atmosphere, yet large uncertainties remain in the absolute magnitude and the seasonality of emission quantities and drivers. Eddy covariance (EC) measurements of CH<span class="inline-formula">₄</span> flux are ideal for constraining ecosystem-scale CH<span class="inline-formula">₄</span> emissions due to quasi-continuous and high-temporal-resolution CH<span class="inline-formula">₄</span> flux measurements, coincident carbon dioxide, water, and energy flux measurements, lack of ecosystem disturbance, and increased availability of datasets over the last decade. Here, we (1) describe the newly published dataset, FLUXNET-CH<span class="inline-formula">₄</span> Version 1.0, the first open-source global dataset of CH<span class="inline-formula">₄</span> EC measurements (available at <span class="uri">https://fluxnet.org/data/fluxnet-ch4-community-product/</span>, last access: 7 April 2021). FLUXNET-CH<span class="inline-formula">₄</span> includes half-hourly and daily gap-filled and non-gap-filled aggregated CH<span class="inline-formula">₄</span> fluxes and meteorological data from 79 sites globally: 42 freshwater wetlands, 6 brackish and saline wetlands, 7 formerly drained ecosystems, 7 rice paddy sites, 2 lakes, and 15 uplands. Then, we (2) evaluate FLUXNET-CH<span class="inline-formula">₄</span> representativeness for freshwater wetland coverage globally because the majority of sites in FLUXNET-CH<span class="inline-formula">₄</span> Version 1.0 are freshwater wetlands which are a substantial source of total atmospheric CH<span class="inline-formula">₄</span> emissions; and (3) we provide the first global estimates of the seasonal variability and seasonality predictors of freshwater wetland CH<span class="inline-formula">₄</span> fluxes. Our representativeness analysis suggests that the freshwater wetland sites in the dataset cover global wetland bioclimatic attributes (encompassing energy, moisture, and vegetation-related parameters) in arctic, boreal, and temperate regions but only sparsely cover humid tropical regions. Seasonality metrics of wetland CH<span class="inline-formula">₄</span> emissions vary considerably across latitudinal bands. In freshwater wetlands (except those between 20<span class="inline-formula">^∘</span> S to 20<span class="inline-formula">^∘</span> N) the spring onset of elevated CH<span class="inline-formula">₄</span> emissions starts 3 d earlier, and the CH<span class="inline-formula">₄</span> emission season lasts 4 d longer, for each degree Celsius increase in mean annual air temperature. On average, the spring onset of increasing CH<span class="inline-formula">₄</span> emissions lags behind soil warming by 1 month, with very few sites experiencing increased CH<span class="inline-formula">₄</span> emissions prior to the onset of soil warming. In contrast, roughly half of these sites experience the spring onset of rising CH<span class="inline-formula">₄</span> emissions prior to the spring increase in gross primary productivity (GPP). The timing of peak summer CH<span class="inline-formula">₄</span> emissions does not correlate with the timing for either peak summer temperature or peak GPP. Our results provide seasonality parameters for CH<span class="inline-formula">₄</span> modeling and highlight seasonality metrics that cannot be predicted by temperature or GPP (i.e., seasonality of CH<span class="inline-formula">₄</span> peak). FLUXNET-CH<span class="inline-formula">₄</span> is a powerful new resource for diagnosing and understanding the role of terrestrial ecosystems and climate drivers in the global CH<span class="inline-formula">₄</span> cycle, and future additions of sites in tropical ecosystems and site years of data collection will provide added value to this database. All seasonality parameters are available at <a href="https://doi.org/10.5281/zenodo.4672601">https://doi.org/10.5281/zenodo.4672601</a> (Delwiche et al., 2021). Additionally, raw FLUXNET-CH<span class="inline-formula">₄</span> data used to extract seasonality parameters can be downloaded from <span class="uri">https://fluxnet.org/data/fluxnet-ch4-community-product/</span> (last access: 7 April 2021), and a complete list of the 79 individual site data DOIs is provided in Table 2 of this paper.

The catalyst stability for propane dehydrogenation can be improved by adding acidic nanomaterials that serve as coke reservoirs.

The Vehicle Technologies Office (VTO) of the Department of Energy (DOE) conducts research and development (R&amp;D) on advanced transportation technologies that would reduce the nation’s use of imported oil and would also lead to reductions in harmful emissions. Technologies supported by VTO include electric drive components such as advanced energy storage devices (primarily batteries), power electronics and electric drive motors, advanced structural materials, energy efficient mobility systems, advanced combustion engines, and fuels. VTO is focused on funding early-stage high-reward/high-risk research to improve critical components needed for more fuel efficient (and cleaner-operating) vehicles. One of the major VTO objectives is to enable U.S. innovators to rapidly develop the next generation of technologies that achieve the cost, range, and charging infrastructure necessary for the widespread adoption of plug-in electric vehicles (PEVs). An important prerequisite for the electrification of the nation’s light duty transportation sector is development of more cost-effective, longer lasting, and more abuse-tolerant PEV batteries. One of the ultimate goals of this research, consistent with the current vehicle electrification trend, is an EV which can provide the full driving performance, convenience, and price of an internal combustion engine (ICE) vehicle. To achieve this, VTO has established the following overarching goal (Source: FY2021 Congressional Budget Justification1): …identify new battery chemistry and cell technologies with the potential to reduce the cost of electric vehicle battery packs by more than half, to less than $100/kWh (ultimate goal is $60/kWh battery cell cost), increase range to 300 miles, and decrease charge time to 15 minutes or less by 2028. VTO works with key U.S. automakers through the United States Council for Automotive Research (USCAR) – an umbrella organization for collaborative research consisting of Fiat Chrysler Automobiles (FCA), the Ford Motor Company, and General Motors. Collaboration with automakers through the partnership known as U.S. Driving Research and Innovation for Vehicle Efficiency and Energy Sustainability (U.S. DRIVE) attempts to enhance the relevance and the success potential of its research portfolio. VTO competitively selects projects for funding through funding opportunity announcements (FOAs). Directly-funded work at the national laboratories are awarded competitively through a lab-call process. During the past year, VTO continued R&amp;D in support of PEVs. Stakeholders for VTO R&amp;D include universities, national laboratories, other government agencies and industry (including automakers, battery manufacturers, material suppliers, component developers, private research firms, and small businesses). This document summarizes the progress of VTO battery R&amp;D projects supported during the fiscal year 2019 (FY 2019).

Low-fat, high-carbohydrate (LF/HC) diets commonly elevate plasma triglyceride (TG) concentrations, but the kinetic mechanisms responsible for this effect remain uncertain. Subjects with low TG (normolipidemic [NL]) and those with moderately elevated TG (hypertriglyceridemic [HTG]) were studied on both a control and an LF/HC diet. We measured VLDL particle and TG transport rates, plasma nonesterified fatty acid (NEFA) flux, and sources of fatty acids used for the assembly of VLDL-TG. The LF/HC diet resulted in a 60% elevation in TG, a 37% reduction in VLDL-TG clearance, and an 18% reduction in whole-body fat oxidation, but no significant change in VLDL-apo B or VLDL-TG secretion rates. Significant elevations in fasting apo B-48 concentrations were observed on the LF/HC in HTG subjects. In both groups, fasting de novo lipogenesis was low regardless of diet. The NEFA pool contributed the great majority of fatty acids to VLDL-TG in NL subjects on both diets, whereas in HTG subjects, the contribution of NEFA was somewhat lower overall and was reduced further in individuals on the LF/HC diet. Between 13% and 29% of VLDL-TG fatty acids remained unaccounted for by the sum of de novo lipogenesis and plasma NEFA input in HTG subjects. We conclude that (a) whole-food LF/HC diets reduce VLDL-TG clearance and do not increase VLDL-TG secretion or de novo lipogenesis; (b) sources of fatty acids for assembly of VLDL-TG differ between HTG and NL subjects and are further affected by diet composition; (c) the presence of chylomicron remnants in the fasting state on LF/HC diets may contribute to elevated TG levels by competing for VLDL-TG lipolysis and by providing a source of fatty acids for hepatic VLDL-TG synthesis; and (d) the assembly, production, and clearance of elevated plasma VLDL-TG in response to LF/HC diets therefore differ from those for elevated TG on higher-fat diets.

2012In this election year, U.S. national spending on health care will reach $2.8 trillion, or about 18% of total spending on all goods and services.This high level of spending reduces our ability to invest in other important parts of the economy and also adds to our unsustainable national debt.There is wide agreement that we must find ways to bend the health care cost curve.Taking different approaches, the two articles that follow present a range of options, including reducing both the prices and quantity of services for public and private payers, reducing administrative costs, implementing new market-based incentives, and reforming the tax subsidy for employer-sponsored health insurance.It is our hope that these articles will stimulate discussion and debate on the best ways to address the cost problem and to place our health care system on a more sustainable path.