DNA methylation and socioeconomic status in a Mexican-American birth cohort.

Background: Maternal social environmental stressors during pregnancy are associated with adverse birth and child developmental outcomes, and epigenetics has been proposed as a possible mechanism for such relationships. Methods: In a Mexican-American birth cohort of 241 maternal-infant pairs, cord blood samples were measured for repeat element DNA methylation (LINE-1 and Alu). Linear mixed effects regression was used to model associations between indicators of the social environment (low household income and education, neighborhood-level characteristics) and repeat element methylation. Results from a dietary questionnaire were also used to assess the interaction between maternal diet quality and the social environment on markers of repeat element DNA methylation. Results: After adjusting for confounders, living in the most impoverished neighborhoods was associated with higher cord blood LINE-1 methylation (β = 0.78, 95%CI 0.06, 1.50, p = 0.03). No other neighborhood-, household-, or individual-level socioeconomic indicators were significantly associated with repeat element methylation. We observed a statistical trend showing that positive association between neighborhood poverty and LINE-1 methylation was strongest in cord blood of infants whose mothers reported better diet quality during pregnancy (pinteraction = 0.12). Conclusion: Our findings indicate a small yet unexpected positive association between neighborhood-level poverty during pregnancy and methylation of repetitive element DNA in infant cord blood and that this association is possibly modified by diet quality during pregnancy. However, our null findings for other adverse SES indicators do not provide strong evidence for an adverse association between early-life socioeconomic environment and repeat element DNA methylation in infants

Metal oxides with ionic-electronic conductivity for thermochemical energy storage

One of the key approaches to developing a supply of renewable energy is Concentrating Solar Power (CSP). However, the diurnal and intermittent nature of the solar resource necessitates efficient energy storage solutions if a reliable energy supply is to be expected. By increasing the temperature and energy density of thermal storage, improvements in power cycle efficiency and energy storage cost are possible and can result in increased economic competitiveness. Thermochemical energy storage (TCES) holds promise for enabling this goal. Metal oxides (MOs), with their elegantly simple reduction/re-oxidation (redox) chemistry, approach an ideal medium for TCES in many respects. For instance, the chemistry is typically highly selective, reversible, and the only gas phase species required for the reaction is oxygen. Also, metal oxides are generally robust, stable at high temperatures, and compatible with advanced falling particle receiver concepts. In fact, MO TCES can be envisioned as an augmentation to particle receiver concepts wherein the reduction enthalpy adds to the sensible energy being stored in the particle. We seek to systematically develop, characterize, and demonstrate a robust and innovative energy storage cycle based on novel metal oxides with mixed ionic-electronic conductivity (MIEC) that can be directly integrated with Air Brayton power cycles. MIECs differ from more conventional oxides in that they exhibit a continuum of redox states over a large range of thermodynamic conditions (temperature and oxygen potential) rather than a single and discrete transition. Furthermore, the high atomic-scale conductivity of oxygen and electrons within these materials facilitates rapid reaction kinetics and full utilization of the redox capacity. Finally, MIECs are exceptionally tunable in composition, which allows optimization of the thermodynamics and the cost of the material. In our system concept, particles are reduced in a solar receiver reduction reactor (SR3) and then flow into a hot storage bin. The particles flow out of the hot bin on demand into a re-oxidation reactor (ROx) where they are contacted counter-currently with compressed air flowing from the compression cycle of the Brayton system. The compressed air acts as both oxidant and heat transfer fluid. The heated air exits the ROx and flows to the turbine while the spent particles flow to cold storage pending recycle to the SR3. MIECS comprised of earth-abundant materials such as calcium and manganese have been developed and characterized. Reaction enthalpies of up to 390 kJ/kg were realized over conditions of interest (Figure 1) and stability was demonstrated for up to 100 cycles. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000. This work is supported by the U.S. Department of Energy, SunShot Initiative, under Award Number DE-FOA-0000805

Ultrathin coatings of nanoporous materials as property enhancements for advanced functional materials.

This report summarizes the findings of a five-month LDRD project funded through Sandia's NTM Investment Area. The project was aimed at providing the foundation for the development of advanced functional materials through the application of ultrathin coatings of microporous or mesoporous materials onto the surface of substrates such as silicon wafers. Prior art teaches that layers of microporous materials such as zeolites may be applied as, e.g., sensor platforms or gas separation membranes. These layers, however, are typically several microns to several hundred microns thick. For many potential applications, vast improvements in the response of a device could be realized if the thickness of the porous layer were reduced to tens of nanometers. However, a basic understanding of how to synthesize or fabricate such ultra-thin layers is lacking. This report describes traditional and novel approaches to the growth of layers of microporous materials on silicon wafers. The novel approaches include reduction of the quantity of nutrients available to grow the zeolite layer through minimization of solution volume, and reaction of organic base (template) with thermally-oxidized silicon wafers under a steam atmosphere to generate ultra-thin layers of zeolite MFI

The oxidation of aluminum at high temperature studied by Thermogravimetric Analysis and Differential Scanning Calorimetry.

The oxidation in air of high-purity Al foil was studied as a function of temperature using Thermogravimetric Analysis with Differential Scanning Calorimetry (TGA/DSC). The rate and/or extent of oxidation was found to be a non-linear function of the temperature. Between 650 and 750 %C2%B0C very little oxidation took place; at 850 %C2%B0C oxidation occurred after an induction period, while at 950 %C2%B0C oxidation occurred without an induction period. At oxidation temperatures between 1050 and 1150 %C2%B0C rapid passivation of the surface of the aluminum foil occurred, while at 1250 %C2%B0C and above, an initial rapid mass increase was observed, followed by a more gradual increase in mass. The initial rapid increase was accompanied by a significant exotherm. Cross-sections of oxidized specimens were characterized by scanning electron microscopy (SEM); the observed alumina skin thicknesses correlated qualitatively with the observed mass increases

Examination of Multiple Air Pollutant Exposure, the Food Environment, and Low Birth Weight in Los Angeles, County

Exposure to urban outdoor air pollution is ubiquitous and low birth weight represents an important health disparity in the United States. While previous research suggests that exposure to outdoor air pollutants are associated with term low birth weight, few studies have evaluated the effects of multipollutant outdoor air exposures or whether there is a spatial patterning to such associations. In addition, populations living in neighborhoods with poor air quality and high neighborhood deprivation may be more likely to reside in neighborhoods that are also characterized by adverse food environments. The first study investigated the overall association between fine particulate matter (PM₂.₅) air pollution with term low birth weight (TLBW) in urban Los Angeles County. This first study also applies spatial multilevel modeling to explore spatial patterns in the exposure response relationship between PM₂.₅ and TLBW. The results from the first study indicates that higher exposure to PM₂.₅ is associated with a higher odds of TLBW and that the exposure response exhibits spatial dependence. The second study examines joint exposure to multiple outdoor air pollutants in Los Angeles County, including PM₂.₅, nitrogen dioxide [NO₂], and nitrogen oxide [NO]. The second study showed that multipollutant profiles with elevated exposure to NO₂, NO, and PM₂.₅ are associated with increased log odds of TLBW, and that multipollutant profiles characteristic of primary traffic emissions impart the greatest increased odds of TLBW. In the third study I examine the association between the neighborhood food environment and TLBW, and explore whether this relationship may be modified by air pollution exposure. In this study I also explore how the food environment clusters with other area-level TLBW risk factors, including income and greenness, and how exposure profiles for these area-level factors combine to impart risk of TLBW. This study found a higher odds of TLBW among mothers who resided in neighborhoods with reduced availability of more healthy food stores and increased availability of less healthy food stores. This study did not find that the food environment works as an effect modifier of PM₂.₅, however, the data provided evidence to suggest that the food environment may influence the magnitude of the association between PM₂.₅ and TLBW (but not the strength of the relationship). Furthermore, I identify neighborhoods with clustering of poor food environments, low socioeconomic status, and low greenness, which are associated with an elevated prevalence of TLBW

Sunshine to petrol: Thermochemistry for solar fuels

Sandia National Laboratories has for many years been engaged in investigating and developing the science and technology of solar thermochemistry for application to production of solar fuels (“Sunshine to Petrol”), and thermochemical energy storage. The vision of Sunshine to Petrol is captured in one deceptively simple chemical equation: Solar Energy + xCO2 + (x+1) H2O → CxH2x+2 (liquid fuel) + (1.5x+0.5) O2 Practical implementation of this equation may seem far-fetched, since it effectively describes the use of solar energy to reverse combustion. However, it is also representative of the photosynthetic processes responsible for much of life on earth and, as such, summarizes the biomass approach to fuels production. Our analysis indicates that any such solar-driven conversion process must operate at a relatively high efficiency, at least 10% solar-to-fuel, to meet the dictates of economics and scale. Thus, it is our contention that an alternative that is not limited by the efficiency of photosynthesis and that more directly leads to a liquid fuel is required. The approach we have pursued is the direct application of solar thermal energy to split carbon dioxide and water to obtain carbon monoxide and hydrogen, the basic precursors to synthetic fuels. These conversions are accomplished via two-step metal-oxide based thermochemical cycles (Figure 1.) In one step of the thermochemical cycle, a metal oxide (MOx) is thermally reduced (oxygen is evolved) at high temperatures driven by concentrating solar power; in the other step the oxygen-deficient (MOx-d) material is reoxidized with carbon dioxide (or water) at a lower temperature to restore the material to its original state and to yield carbon monoxide (or hydrogen). As shown in the figure, heat may be recuperated between the high and low temperature steps. Figure 1 – Schematic depiction of a two-step metal-oxide thermochemical cycle with internal recuperation for carbon dioxide and water splitting. Thermochemistry promises to provide the high efficiencies that we believe are required for solar fuels. However, the continuous chemical and thermal cycling occurring in these cyclic processes poses numerous chemistry, materials, and engineering challenges. Improvements in both the metal oxides that facilitate the conversion, and the reactors and systems in which they are implemented, are needed to realize high efficiency and reliable operation. The properties that define an ideal material for an efficient process, e.g. the thermodynamics of the redox reaction, and key materials traits for implementation will be discussed. Advances in characterizing and understanding the remarkably dynamic behavior of some of the known active materials will also be presented. Requirements and constraints for efficient design and operation of solar thermochemical reactors will likewise be introduced. Results for an established material, i.e. ceria, in a first-of-kind continuous reactor for on-sun conversion of carbon dioxide to carbon monoxide over a period of days will be presented. Next-generation approaches to materials and reactors will be briefly discussed. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000

Implementing Good Practices Programs to Encourage Production of High-Quality, Safer Produce in Mississippi

Fifty-four growers/producers attended four 1-day good agricultural practices (GAP) and good handling practices (GHP) workshops at four locations in Mississippi. Pre- and postworkshop survey data indicated that the participants\u27 food safety knowledge increased by 15%. Furthermore, the workshops helped producers develop their own food safety plans. The workshops also trained the producers to be prepared for U.S. Department of Agriculture (USDA) GAP and GHP audits. To assist producers in preparing for these audits, two mock audits were conducted after the workshops. As a result of the program, several producers became ready to be audited, and at least one producer became USDA GAP certified

High Entropy Rare Earth A2b2o7 Type Zirconates

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Heisenberg characters, unitriangular groups, and Fibonacci numbers

Let \UT_n(\FF_q) denote the group of unipotent $n\times n$ upper triangular matrices over a finite field with $q$ elements. We show that the Heisenberg characters of \UT_{n+1}(\FF_q) are indexed by lattice paths from the origin to the line $x+y=n$ using the steps $(1,0), (1,1), (0,1), (1,1)$, which are labeled in a certain way by nonzero elements of \FF_q. In particular, we prove for $n\geq 1$ that the number of Heisenberg characters of \UT_{n+1}(\FF_q) is a polynomial in $q-1$ with nonnegative integer coefficients and degree $n$, whose leading coefficient is the $n$th Fibonacci number. Similarly, we find that the number of Heisenberg supercharacters of \UT_n(\FF_q) is a polynomial in $q-1$ whose coefficients are Delannoy numbers and whose values give a $q$-analogue for the Pell numbers. By counting the fixed points of the action of a certain group of linear characters, we prove that the numbers of supercharacters, irreducible supercharacters, Heisenberg supercharacters, and Heisenberg characters of the subgroup of \UT_n(\FF_q) consisting of matrices whose superdiagonal entries sum to zero are likewise all polynomials in $q-1$ with nonnegative integer coefficients.Comment: 25 pages; v2: material significantly revised and condensed; v3: minor corrections, final versio

Novel catalysts for hydrogen fuel cell applications:Final report (FY03-FY05).

The goal of this project was to develop novel hydrogen-oxidation electrocatalyst materials that contain reduced platinum content compared to traditional catalysts by developing flexible synthesis techniques to fabricate supported catalyst structures, and by verifying electrochemical performance in half cells and ultimately laboratory fuel cells. Synthesis methods were developed for making small, well-defined platinum clusters using zeolite hosts, ion exchange, and controlled calcination/reduction processes. Several factors influence cluster size, and clusters below 1 nm with narrow size distribution have been prepared. To enable electrochemical application, the zeolite pores were filled with electrically-conductive carbon via infiltration with carbon precursors, polymerization/cross-linking, and pyrolysis under inert conditions. The zeolite host was then removed by acid washing, to leave a Pt/C electrocatalyst possessing quasi-zeolitic porosity and Pt clusters of well-controlled size. Plotting electrochemical activity versus pyrolysis temperature typically produces a Gaussian curve, with a peak at ca. 800 C. The poorer relative performances at low and high temperature are due to low electrical conductivity of the carbon matrix, and loss of zeolitic structure combined with Pt sintering, respectively. Cluster sizes measured via adsorption-based methods were consistently larger than those observed by TEM and EXAFS, suggesting , that a fraction of the clusters were inaccessible to the fluid phase. Detailed EXAFS analysis has been performed on selected catalysts and catalyst precursors to monitor trends in cluster size evolution, as well as oxidation states of Pt. Experiments were conducted to probe the electroactive surface area of the Pt clusters. These Pt/C materials had as much as 110 m{sup 2}/g{sub pt} electroactive surface area, an almost 30% improvement over what is commercially (mfg. by ETEK) available (86 m{sup 2}/g{sub pt}). These Pt/C materials also perform qualitatively as well as the ETEK material for the ORR, a non-trivial achievement. A fuel cell test showed that Pt/C outperformed the ETEK material by an average of 50% for a 300 hour test. Increasing surface area decreases the amount of Pt needed in a fuel cell, which translates into cost savings. Furthermore, the increased performance realized in the fuel cell test might ultimately mean less Pt is needed in a fuel cell; this again translates into cost savings. Finally, enhanced long-term stability is a key driver within the fuel cell community as improvements in this area must be realized before fuel cells find their way into the marketplace; these Pt/C materials hold great promise of enhanced stability over time. An external laser desorption ion source was successfully installed on the existing Fourier transform ion-cyclotron resonance (FT-ICR) mass spectrometer. However, operation of this laser ablation source has only generated metal atom ions, no clusters have been found to date. It is believed that this is due to the design of the pulsed-nozzle/laser vaporization chamber. The final experimental configuration and design of the two source housings are described