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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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At least 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Experimental observation of spin-dependent electron many-body effects in CdTe

In semiconductors, the spin degree of freedom is usually disregarded in the theoretical treatment of electron many-body effects such as band-gap renormalization and screening of the Coulomb enhancement factor. Nevertheless, as was observed experimentally in GaAs, not only the single-particle phase-space filling but also many-body effects are spin sensitive. In this paper, we report on time- and polarization-resolved differential transmission pump-probe measurements in CdTe, which has the same zincblende crystal structure but different material parameters compared to that of GaAs. We show experimentally that at room temperature in CdTe—unlike in GaAs—the pump-induced decrease of transmission due to the band-gap renormalization can even exceed the transmission increase due to the phase-space filling, which enables to measure directly the spin-sensitivity of the band-gap renormalization. We also observed that the influence of the band-gap renormalization is more prominent at low temperatures.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS2012

Analysis of Screen Channel LAD Bubble Point Tests in Liquid Methane at Elevated Temperature

This paper examines the effect of varying the liquid temperature and pressure on the bubble point pressure for screen channel Liquid Acquisition Devices in cryogenic liquid methane using gaseous helium across a wide range of elevated pressures and temperatures. Testing of a 325 x 2300 Dutch Twill screen sample was conducted in the Cryogenic Components Lab 7 facility at the NASA Glenn Research Center in Cleveland, Ohio. Test conditions ranged from 105 to 160K and 0.0965 - 1.78 MPa. Bubble point is shown to be a strong function of the liquid temperature and a weak function of the amount of subcooling at the LAD screen. The model predicts well for saturated liquid but under predicts the subcooled data.

Hartwig, Jason↗
DOE OSTI2013

Crucial role of Toll-like receptors in the zinc/nickel-induced inflammatory response in vascular endothelial cells

Our previous studies indicated that zinc induced inflammatory response in both vascular endothelial cells and promonocytes. Here, we asked if other metals could cause the similar effect on vascular endothelial cells and tried to determine its underlying mechanism. Following screening of fifteen metals, zinc and nickel were identified with a marked proinflammatory effect, as determined by ICAM-1 and IL-8 induction, on human umbilical vein endothelial cells (HUVECs). Inhibiting protein expression of myeloid differentiation primary response protein-88 (MyD88), a Toll-like receptor (TLR) adaptor acting as a TLR-signaling transducer, significantly attenuated the zinc/nickel-induced inflammatory response, suggesting the critical roles of TLRs in the inflammatory response. Blockage of TLR-4 signaling by CLI-095, a TLR-4 inhibitor, completely inhibited the nickel-induced ICAM-1 and IL-8 expression and NFκB activation. The same CLI-095 treatment significantly blocked the zinc-induced IL-8 expression, however with no significant effect on the ICAM-1 expression and a minor inhibitory effect on the NFκB activation. The finding demonstrated the differential role of TLR-4 in regulation of the zinc/nickel-induced inflammatory response, where TLR-4 played a dominant role in NFκB activation by nickel, but not by zinc. Moreover, inhibition of NFκB by adenovirus-mediated IκBα expression and Bay 11-7025, an inhibitor of cytokine-induced IκB-α phosphorylation, significantly attenuated the zinc/nickel-induced inflammatory responses, indicating the critical of NFκB in the process. The study demonstrates the crucial role of TLRs in the zinc/nickel-induced inflammatory response in vascular endothelial cells and herein deciphers a potential important difference in NFκB activation via TLRs. The study provides a molecular basis for linkage between zinc/nickel exposure and pathogenesis of the metal-related inflammatory vascular disease. - Highlights: • Both zinc and nickel cause ICAM-1/IL‑8 expression in endothelial cells via TLRs. • Nickel induces the inflammatory responses via a TLR-4/NF-κB pathway. • Zinc causes the inflammatory responses via a broader TLRs/NF-κB signaling. • Nickel shows a significantly higher inflammatory effect than zinc. • NF-κB activation is the primary mechanism involved in the inflammatory responses.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Non-invasive toluene sensor for early diagnosis of lung cancer

Here we present, quantification of volatile organic compounds in human breath for early detection of lung cancer to increase survival probability. Graphene oxide nanosheets synthesized by modified Hummer’s method were employed as a sensing element to detect the presence of toluene in the sample. Optical and morphological characterization of synthesized nanomaterial was performed by UV-Visible spectroscopy and scanning electron microscopy (SEM) respectively. Spectroscopic assay shows a linearly decreasing intensity of GO absorption peak with increasing toluene concentration with a linear range from 0-200 pM. While impedimetric sensor developed on a graphene oxide nanosheetsmodified screen printed electrodes displayed a decreasing electron transfer resistance increasing toluene with much larger linear range of 0-1000 pM. Reported techniques are advantageous as these are simple, sensitive and cost effective, which can easily be extended for primary screening of other VOCs.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

The charmonium dissociation in an ''anomalous wind''

We study the charmonium dissociation in a strongly coupled chiral plasma in the presence of magnetic field and axial charge imbalance. This type of plasma carries "anomalous flow" induced by the chiral anomaly and exhibits novel transport phenomena such as chiral magnetic effect. We found that the "anomalous flow" would modify the charmonium color screening length by using the gauge/gravity correspondence. We derive an analytical expression quantifying the "anomalous flow" experienced by a charmonium for a large class of chiral plasma with a gravity dual. We elaborate on the similarity and it qualitative difference between anomalous effects on the charmonium color screening length which are model-dependent and those on the heavy quark drag force which are fixed by the second law of thermodynamics. As a result, we speculate on the possible charmonium dissociation induced by the chiral anomaly in heavy ion collisions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

First-principles coupled cluster theory of the electronic spectrum of transition metal dichalcogenides

The electronic properties of two-dimensional transition metal dichalcogenides (2D TMDs) have attracted much attention during the last decade. Here we show how a diagrammatic ab initio coupled cluster singles and doubles (CCSD) treatment paired with a careful thermodynamic limit extrapolation in two dimensions can be used to obtain converged band gaps for monolayer materials in the MoS 2 family. We find CCSD gaps to lie in the upper range of the spread of $\textit{GW}$ approximation based on density functional theory (DFT) simulations, and also find slightly higher effective hole masses compared to previous reports. We also investigate the ability of CCSD to describe trion states, finding a reasonable qualitative structure, but poor excitation energies due to the lack of screening of three-particle excitations in the effective Hamiltonian. Our study provides an independent high-level benchmark of the role of many-body effects in 2D TMDs and showcases the potential strengths and weaknesses of diagrammatic coupled cluster approaches for realistic materials.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

DPC Cement Filler Development (Progress Report)

The fillers research and development (R&D) program, mostly experimental, is part of a broader R&D program that includes new process modeling and performance assessment of criticality effects and the overall importance of criticality to repository performance (consequence screening). A literature research and consultation effort with experts by Hardin and Brady (2018) identified several potentially effective and workable filler materials including cements (primarily phosphate based), moltenmetal alloys, and low-temperature glasses. Filler attributes were defined, and the preliminary lists were compared qualitatively. Further comparative analysis will be done (e.g., cost estimates) after experimental screening has narrowed the list of alternatives. The following cement filler compositions were selected for experimental development work and accelerated testing in FY20: Aluminum phosphate cements (APCs); more specifically aluminum oxide / aluminum phosphate (Al 2 O 3 / AlPO 4 ) cements in which Al 2 O 3 serves as the filler material bound by an AlPO 4 binder formed by the reaction of Al 2 O 3 with H 3 PO 4 ; Calcium phosphate cements (CPCs); more specifically composed of pure or nearly pure hydroxyapatite or HAP (Ca 5 (PO 4 ) 3 (OH)); Wollastonite phosphate cements (WPC), specifically wollastonite and aluminum or calcium aluminum phosphates in which CaSiO 3 serves as the filler material and the phosphate serves as the binder. The FY20 effort focused on the optimization of compositions and subsequent processing of these three materials to achieve dense and well-consolidated monolithic samples with 30 to 40% porosity and permeabilities of 1 millidarcy. At the close of this progress report the aluminum phosphate cements (APCs) and the wollastonite phosphate cements (WPCs) appear to show the most promise for continued development. Less progress has been made with the calcium phosphate cements (CPCs); their slurry viscosities are high (and difficult to measure) and they exhibit relatively short cure times of 2 to 3 hours with concomitant and excessive volatile (e.g. CO 2 ) generation.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Development and Advanced Testing of DPC Cement Fillers

The fillers research and development (R&D) program, mostly experimental, is part of a broader R&D program that includes new process modeling and performance assessment of criticality effects and the overall importance of criticality to repository performance (consequence screening). A literature research and consultation effort with experts by Hardin and Brady (2018) identified several potentially effective and workable filler materials including cements (primarily phosphate based), moltenmetal alloys, and low-temperature glasses. Filler attributes were defined, and the preliminary lists were compared qualitatively. Further comparative analysis will be done (e.g., cost estimates) after experimental screening has narrowed the list of alternatives. The research presented here is focused Sandia’s efforts for the development of phosphate-based cement fillers. Molten metal filler research is an ongoing activity at Oak Ridge National Laboratories and is not discussed herein. After the completion of the FY20 research effort the following cement filler compositions were selected for further experimental development work and advanced testing in FY21: 1. Aluminum phosphate cements (APCs); more specifically aluminum oxide / aluminum phosphate (Al 2 O 3 / AlPO 4 ) cements in which Al 2 O 3 serves as the filler material bound by an AlPO 4 binder formed by the reaction of Al 2 O 3 with various phosphate sources; 2. Wollastonite phosphate cements (WPCs), specifically wollastonite and aluminum or calcium aluminum phosphates in which CaSiO 3 serves as the filler material bound by a calcium phosphate that serves as the binder; and 3. Calcium aluminate phosphate cements (CAPCs) specifically grossite (CaAl 4 O 7 ) and hibonite (CaAl 11 O 18 ) fillers bound by an aluminum phosphate that serves as the binder. This effort focused on the optimization and subsequent processing of these three cements to achieve dense and well-consolidated monolithic samples. Upon completion of the FY21 effort the aluminum phosphate cements (APCs) and the calcium aluminate phosphate cements (CAPCs) show the most promise for advanced testing and scale up. We will begin the work in FY22 focused on testing the performance of these two cements in small scale DPCs as well as advanced materials testing to evaluate cement performance under expected radiation doses and representative post-closure geochemical environments.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Effects of defined mixtures of persistent organic pollutants (POPs) on multiple cellular responses in the human hepatocarcinoma cell line, HepG2, using high content analysis screening

Persistent organic pollutants (POPs) are toxic substances, highly resistant to environmental degradation, which can bio-accumulate and have long-range atmospheric transport potential. Most studies focus on single compound effects, however as humans are exposed to several POPs simultaneously, investigating exposure effects of real life POP mixtures on human health is necessary. A defined mixture of POPs was used, where the compound concentration reflected its contribution to the levels seen in Scandinavian human serum (total mix). Several sub mixtures representing different classes of POPs were also constructed. The perfluorinated (PFC) mixture contained six perfluorinated compounds, brominated (Br) mixture contained seven brominated compounds, chlorinated (Cl) mixture contained polychlorinated biphenyls and also p,p’-dichlorodiphenyldichloroethylene, hexachlorobenzene, three chlordanes, three hexachlorocyclohexanes and dieldrin. Human hepatocarcinoma (HepG2) cells were used for 2 h and 48 h exposures to the seven mixtures and analysis on a CellInsight™ NXT High Content Screening platform. Multiple cytotoxic endpoints were investigated: cell number, nuclear intensity and area, mitochondrial mass and membrane potential (MMP) and reactive oxygen species (ROS). Both the Br and Cl mixtures induced ROS production but did not lead to apoptosis. The PFC mixture induced ROS production and likely induced cell apoptosis accompanied by the dissipation of MMP. Synergistic effects were evident for ROS induction when cells were exposed to the PFC + Br mixture in comparison to the effects of the individual mixtures. No significant effects were detected in the Br + Cl, PFC + Cl or total mixtures, which contain the same concentrations of chlorinated compounds as the Cl mixture plus additional compounds; highlighting the need for further exploration of POP mixtures in risk assessment. - Highlights: • High content analysis (HCA) is a novel approach for determining toxicity of complex mixtures. • Multiple cytotoxic endpoints were investigated for defined mixtures of persistent organic pollutants (POPs). • POP mixtures are based on levels relevant to human exposure. • POP mixtures can increase ROS induction and impact mitochondrial health, which could result in apoptosis. • HCA can detect pre-lethal and reversible signs of cellular stress.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Accelerated Testing of Selected Filler Compositions

The fillers R&D program, mostly experimental, is part of a broader R&D program that includes new process modeling and performance assessment of criticality effects and the overall importance of criticality to repository performance (consequence screening). A literature research and consultation effort with experts by Hardin and Brady (2018) identified several potentially effective and workable filler materials including cements (primarily phosphate based), molten-metal alloys, and low-temperature glasses. Filler attributes were defined and the preliminary lists were compared qualitatively. Further comparative analysis will be done (e.g., cost estimates) after experimental screening has narrowed the list of alternatives. The following cement filler compositions were selected for experimental development work and accelerated testing in FY19: Aluminum phosphate cements (APCs); more specifically aluminum oxide / aluminum phosphate (Al 2 O 3 / AlPO 4 ) cements in which Al 2 O 3 serves as the filler material bound by an AlPO 4 binder formed by the reaction of Al 2 O 3 with H 3 PO 4 ; Calcium phosphate cements (CPCs); more specifically composed of pure or nearly pure hydroxyapatite (Ca 5 (PO 4 ) 3 (OH)); Magnesium potassium phosphate cements (MKPs) composed of magnesium oxide / magnesium potassium phosphate (MgO / MgKPO 4 ) cements in which MgO serves as the filler and MgKPO 4 serves as the binder formed by the reaction of MgO with monopotassium phosphate (KH 2 PO 4 ) and tricalcium phosphate ((Ca 3 (PO 4 ) 2 ); Two additional potential cement materials were explored preliminarily as the result of: (1) continued literature investigations into other filler candidates (wollastonite-based phosphate ceramic) and (2) the experimental discovery of a well-consolidated fly ash phosphate cement during the evaluation of fly ash as a potential filler material with Al 2 O 3 in APCs. Fly ash phosphate cements, more specifically in which a fly ash material composed primarily of mullite and quartz serves as the filler and is reacted with H 3 PO 4 to form amorphous phosphate phase(s) as the binder; Wollastonite aluminum phosphate cements (WAPC), specifically wollastonite / aluminum phosphate (CaSiO 3 / AlPO 4 ) in which CaSiO 3 serves as the filler material and AlPO 4 serves as the binder formed by Al(OH) 3 or metakaolin as Al sources and H 3 PO 4 or ammonium dihydrogen phosphate (ADP) (NH 4 H 2 PO 4 ) as phosphate sources. The FY19 effort focused on the optimization of compositions and subsequent processing of these five materials to achieve dense and well-consolidated monolithic samples with relatively low porosity. Once these goals were met basic material properties screening evaluations were performed including an assessment of dissolution resistance in water at elevated temperature (200 °C) and mechanical testing including unconfined compressive strength (UCS) testing. To date, the aluminum phosphate cements (APCs) appear to show the most promise for continued development. They are easily prepared and form smooth pourable slurries that remain stable for days with relatively low viscosities of several thousand centipoise (cP). They are then set at elevated temperatures (e.g., 170 °C) under ambient (0.1 MPa) or elevated pressure (~1MPa). Overall, they demonstrate the best dissolution resistance in water at elevated temperature (200 °C) and good compressive strengths. However, additional effort is required to optimize the APC slurry formulations and the process used for thermal curing these materials. The calcium phosphate cements (CPCs) can be formed at room temperature to produce a well-consolidated body. However, their slurry viscosities are very high (and difficult to measure) and they exhibit relatively short cure times of 2 to 3 hours. Also, dissolution resistance is very poor, the poorest of all the cements examined The same is the case for the small number of MKP cements fabricated; they cure very quickly (10 minutes or less) and disintegrate within a few hours upon immersion in distilled water. Surprisingly, fly ash reacts with phosphoric acid to form dense and well-consolidated cements but the mixture rapidly sets at room temperature (less than 30 minutes) and the subsequent conversion of the binder to an amorphous phosphate phase(s) as a function of temperature is complicated. Finally, the wollastonite aluminum phosphate cements (WAPC) are easily prepared and form smooth pourable slurries that remain stable for several hours. They are then set at 130 °C. A WAPC sample exhibited the highest compressive strengths of all the materials we evaluated but in general their dissolution resistance to water is poor.

36 MATERIALS SCIENCE↗
NASA NTRS1991

Improvement of program to calculate electronic properties of narrow band gap materials

The program was improved by reprogramming it so it will run on both a SUN and a VAX. Also it is easily transportable as it is on a disk for use on a SUN. A computer literature search resulted in some improved parameters for Hg(1-x)Cd(x)Te and a table of parameters for Hg(1-x)Zn(x)Te. The effects of neutral defects were added to the program, and it was found, as expected, that they contribute very little to the mobility at temperatures of interest. The effect were added of varying the following parameters: dielectric constants, screening parameters, disorder energies, donor and acceptor concentrations, momentum matrix element, different expressions for energy gap, and transverse effective charge.

Patterson, James D.↗
DOE OSTI2018

X-ray transparent microfluidic platforms for membrane protein crystallization with microseeds

Crystallization of membrane proteins is a critical step for uncovering atomic resolution 3-D structures and elucidating structure–function relationships. Microseeding, the process of transferring sub-microscopic crystal nuclei from initial screens into new crystallization experiments, is an effective, yet underutilized approach to grow crystals suitable for X-ray crystallography. In this work, we report simplified methods for crystallization of membrane proteins that utilize microseeding in X-ray transparent microfluidic chips. First, a microfluidic method for introduction of microseed dilutions into metastable crystallization experiments is demonstrated for photoactive yellow protein and cytochrome bo3 oxidase. As microseed concentration decreased, the number of crystals decreased while the average size increased. Second, we demonstrate a microfluidic chip for microseed screening, where many crystallization conditions were formulated on-chip prior to mixing with microseeds. Crystallization composition, crystal size, and diffraction data were collected and mapped on phase diagrams, which revealed that crystals of similar diffraction quality and size typically grow in distinct regions of the phase diagram.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

The Effect of Prostate-Specific Antigen (PSA) Test on Radiation Risk Estimate for Prostate Cancer Incidence among Atomic-Bomb Survivors

Following our previous report on the radiation doseresponse for prostate cancer incidence rates in the Life Span Study (LSS) cohort of atomic bomb survivors, we reevaluated the radiation-related risk adjusting for differences in baseline cancer incidence rates among three subsets of the LSS cohort defined by the timing of their first participation in biennial health examinations offered to the Adult Health Study (AHS) sub-cohort members and prostate-specificantigen (PSA) testing status for AHS participants: 1. nonAHS participants, 2. AHS participants before receiving PSA test, and 3. AHS participants after receiving PSA test. We found a 2.9-fold increase in the baseline incidence rates among AHS participants after receiving PSA test. After adjusting for the PSA-testing-status effects on the baseline rates the estimated excess relative risk (ERR) per Gy was 0.54 (95% CI: 0.15, 1.05), which was almost identical to the previously reported unadjusted ERR estimate (0.57, 95% CI: 0.21, 1.00). The current results confirmed that, while the PSA testing among AHS participants increased the baseline incidence rates, it did not impact the radiation risk estimate, strengthening the previously reported dose-response relationship for prostate cancer incidence in the LSS. As the use of PSA tests continue in screening and medical settings, analyses of possible effects of PSA testing should be an important aspect of future epidemiological studies of the association between radiation exposure and prostate cancer.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
NASA NTRS2017

Degradation and ESR Failures in MnO2 Chip Tantalum Capacitors

Equivalent series resistance (ESR) of chip tantalum capacitors determines the rate of energy delivery and power dissipation thus affecting temperature and reliability of the parts. Employment of advanced capacitors with reduced ESR decreases power losses and improves efficiency in power systems. Stability of ESR is essential for correct operations of power units and might cause malfunctioning and failures when ESR becomes too high or too low. Several cases with ESR values in CWR29 capacitors exceeding the specified limit that were observed recently raised concerns regarding environmental factors affecting ESR and the adequacy of the existing screening and qualification testing. In this work, results of stress testing of various types of military and commercial capacitors obtained over years by GSFC test lab and NEPP projects that involved ESR measurements are described. Environmental stress tests include testing in humidity and vacuum chambers, temperature cycling, long-term storage at high temperatures, and various soldering simulation tests. Note that in many cases parts failed due to excessive leakage currents or reduced breakdown voltages. However, only ESR-related degradation and failures are discussed. Mechanisms of moisture effect are discussed and recommendations to improve screening and qualification system are suggested.

Equivalent Series Resistance (ESR)↗
DOE OSTI2016

Zebrafish embryos as a screen for DNA methylation modifications after compound exposure

Modified epigenetic programming early in life is proposed to underlie the development of an adverse adult phenotype, known as the Developmental Origins of Health and Disease (DOHaD) concept. Several environmental contaminants have been implicated as modifying factors of the developing epigenome. This underlines the need to investigate this newly recognized toxicological risk and systematically screen for the epigenome modifying potential of compounds. In this study, we examined the applicability of the zebrafish embryo as a screening model for DNA methylation modifications. Embryos were exposed from 0 to 72 h post fertilization (hpf) to bisphenol-A (BPA), diethylstilbestrol, 17α-ethynylestradiol, nickel, cadmium, tributyltin, arsenite, perfluoroctanoic acid, valproic acid, flusilazole, 5-azacytidine (5AC) in subtoxic concentrations. Both global and site-specific methylation was examined. Global methylation was only affected by 5AC. Genome wide locus-specific analysis was performed for BPA exposed embryos using Digital Restriction Enzyme Analysis of Methylation (DREAM), which showed minimal wide scale effects on the genome, whereas potential informative markers were not confirmed by pyrosequencing. Site-specific methylation was examined in the promoter regions of three selected genes vasa, vtg1 and cyp19a2, of which vasa (ddx4) was the most responsive. This analysis distinguished estrogenic compounds from metals by direction and sensitivity of the effect compared to embryotoxicity. In conclusion, the zebrafish embryo is a potential screening tool to examine DNA methylation modifications after xenobiotic exposure. The next step is to examine the adult phenotype of exposed embryos and to analyze molecular mechanisms that potentially link epigenetic effects and altered phenotypes, to support the DOHaD hypothesis. - Highlights: • Compound induced effects on DNA methylation in zebrafish embryos • Global methylation not an informative biomarker • Minimal genome wide site specific changes as detected with DREAM • Compound/class specific effects suggested by pyrosequence of specific targets • Zebrafish embryo may be a screening model for epigenetic effects.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

THE LOW-FREQUENCY CHARACTERISTICS OF PSR J0437–4715 OBSERVED WITH THE MURCHISON WIDE-FIELD ARRAY

We report on the detection of the millisecond pulsar PSR J0437–4715 with the Murchison Wide-field Array (MWA) at a frequency of 192 MHz. Our observations show rapid modulations of pulse intensity in time and frequency that arise from diffractive scintillation effects in the interstellar medium (ISM), as well as prominent drifts of intensity maxima in the time-frequency plane that arise from refractive effects. Our analysis suggests that the scattering screen is located at a distance of ∼80-120 pc from the Sun, in disagreement with a recent claim that the screen is closer (∼10 pc). Comparisons with higher frequency data from Parkes reveal a dramatic evolution of the pulse profile with frequency, with the outer conal emission becoming comparable in strength to that from the core and inner conal regions. As well as demonstrating the high time resolution science capabilities currently possible with the MWA, our observations underscore the potential to conduct low-frequency investigations of timing-array millisecond pulsars, which may lead to increased sensitivity in the detection of nanoHertz gravitational waves via the accurate characterization of ISM effects.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

Effect of dust particle polarization on scattering processes in complex plasmas

Screened interaction potentials in dusty plasmas taking into account the polarization of dust particles have been obtained. On the basis of screened potentials scattering processes for ion-dust particle and dust particle-dust particle pairs have been studied. In particular, the scattering cross section is considered. The scattering processes for which the dust grain polarization is unimportant have been found. The effect of zero angle dust particle-dust particle scattering is predicted.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS2006

Protein Crystallization Using Room Temperature Ionic Fluids

The ionic liquids (ILs) 1-butyl-3-methylimidizolium chloride (C4mim-C1), 1-butyl-3- methylimidizolium diethyleneglycol monomethylethersulfate ([C4mim]DEMGS), and 1-butyl-1 -methylpyrollidinium dihydrogenphosphate ([p1,4]dhp) were tested for their effects on the crystallization of the proteins canavalin, beta-lactoglobulin B, xylanase, and glucose isomerase, using a standard high throughput screen. The crystallization experiments were set up with the ILs added to the protein solutions at 0.2 and 0.4 M final concentrations. Crystallization droplets were set up at three proteixprecipitant ratios (1:1, 2:1, and 4:l), which served to progressively dilute the effects of the screen components while increasing the equilibrium protein and IL concentrations. Crystals were obtained for all four proteins at a number of conditions where they were not obtained from the IL-free control experiment. Over half of the protein-IL combinations tested had more successful outcomes than negative, where the IL-free crystallization was better than the corresponding IL-containing outcome, relative to the control. One of the most common causes of a negative outcome was solubilization of the protein by the IL, resulting in a clear drop. In one instance, we were able to use the IL-induced solubilizing to obtain beta-lactoglobulin B crystals from conditions that gave precipitated protein in the absence of IL. The results suggest that it may be feasible to develop ILs specifically for the task of macromolecule crystallization.

Pusey, Marc L.↗