Structural concepts for large solar concentrators

NASA Technical Reports Server (NTRS)

Hedgepeth, John M.; Miller, Richard K.

1987-01-01

The Sunflower large solar concentrator, developed in the early 1970's, is a salient example of a high-efficiency concentrator. The newly emphasized needs for solar dynamic power on the Space Station and for large, lightweight thermal sources are outlined. Existing concepts for high efficiency reflector surfaces are examined with attention to accuracy needs for concentration rates of 1000 to 3000. Concepts using stiff reflector panels are deemed most likely to exhibit the long-term consistent accuracy necessary for low-orbit operation, particularly for the higher concentration ratios. Quantitative results are shown of the effects of surface errors for various concentration and focal-length diameter ratios. Cost effectiveness is discussed. Principal sources of high cost include the need for various dished panels for paraboloidal reflectors and the expense of ground testing and adjustment. A new configuration is presented addressing both problems, i.e., a deployable Pactruss backup structure with identical panels installed on the structure after deployment in space. Analytical results show that with reasonable pointing errors, this new concept is capable of concentration ratios greater than 2000.

Structural concepts for large solar concentrators

NASA Technical Reports Server (NTRS)

Hedgepeth, J. M.; Miller, R. K.

1986-01-01

Solar collectors for space use are examined, including both early designs and current concepts. In particular, attention is given to stiff sandwich panels and aluminum dishes as well as inflated and umbrella-type membrane configurations. The Sunflower concentrator is described as an example of a high-efficiency collector. It is concluded that stiff reflector panels are most likely to provide the long-term consistent accuracy necessary for low-orbit operation. A new configuration consisting of a Pactruss backup structure, with identical panels installed after deployment in space, is presented. It is estimated that concentration ratios in excess of 2000 can be achieved with this concept.

A Fast and Easily-Realized Concentration Sensor for Binary Gas Mixtures and Its Design Analysis.

PubMed

Guan, Yu; Lu, Song; Zhang, Dan; Hu, Yang; Yuan, Wei

2018-04-19

A low-cost and easily-realized sensing device used for the detection of gas mixtures at different concentrations is presented. Its sensing part includes a small critical nozzle, a laminar structure, and a differential pressure sensor. When gas flows through the laminar structure, there is a pressure drop between both ends of it, and for different components of gas, the pressure drop is different. Based on this feature, the concentration detection is achieved. Concentration tests for two types of fire extinguishing agents CBrF₃ and C₃HF₇ are presented. The results show the characteristics of fast response/recovery time, high accuracy, and good repeatability. Based on the theoretical analysis, the effects of the design parameters on the sensing performance to concentration detection are discussed in detail.

Support apparatus for semiconductor wafer processing

DOEpatents

Griffiths, Stewart K.; Nilson, Robert H.; Torres, Kenneth J.

2003-06-10

A support apparatus for minimizing gravitational stress in semiconductor wafers, and particularly silicon wafers, during thermal processing. The support apparatus comprises two concentric circular support structures disposed on a common support fixture. The two concentric circular support structures, located generally at between 10 and 70% and 70 and 100% and preferably at 35 and 82.3% of the semiconductor wafer radius, can be either solid rings or a plurality of spaced support points spaced apart from each other in a substantially uniform manner. Further, the support structures can have segments removed to facilitate wafer loading and unloading. In order to withstand the elevated temperatures encountered during semiconductor wafer processing, the support apparatus, including the concentric circular support structures and support fixture can be fabricated from refractory materials, such as silicon carbide, quartz and graphite. The claimed wafer support apparatus can be readily adapted for use in either batch or single-wafer processors.

Dying Star Creates Fantasy-like Sculpture of Gas and Dust

NASA Image and Video Library

2004-09-09

This detailed view of NGC 6543, the Cat Eye Nebula, from NASA Hubble Space Telescope includes intricate structures, including concentric gas shells, jets of high-speed gas, and unusual shock-induced knots of gas.

Design for inadvertent damage in composite laminates

NASA Technical Reports Server (NTRS)

Singhal, Surendra N.; Chamis, Christos C.

1992-01-01

Simplified predictive methods and models to computationally simulate durability and damage in polymer matrix composite materials/structures are described. The models include (1) progressive fracture, (2) progressively damaged structural behavior, (3) progressive fracture in aggressive environments, (4) stress concentrations, and (5) impact resistance. Several examples are included to illustrate applications of the models and to identify significant parameters and sensitivities. Comparisons with limited experimental data are made.

Effects of pulp mill effluent on benthic assemblages in mesocosms along the Saint John River, Canada.

PubMed

Culp, Joseph M; Cash, Kevin J; Glozier, Nancy E; Brua, Robert B

2003-12-01

We used mesocosms to examine the impact of different concentrations of pulp mill effluent (PME) on structural and functional endpoints of a benthic assemblage in the Saint John River (NB, Canada) during 1999 and 2000. Previous studies on this effluent's effects produced conflicting results, with field surveys suggesting a pattern of mild nutrient enrichment, while laboratory toxicity tests linked effluent exposure to moderate contaminant effects. Experimental treatments included three concentrations of sulfite pulp mill effluent (0, 5, 10% v/v PME). Endpoints for the assessment included algal biomass and taxonomic composition, benthic invertebrate abundance and composition, and insect emergence. Low concentrations of PME increased periphyton biomass and caused changes in community structure within the diatom-dominated community. Pulp mill effluent addition had little effect on several structural endpoints measured for benthic invertebrates, including abundance and taxonomic richness, but significantly changed community composition. For both periphyton and benthic invertebrates, community composition endpoints were more sensitive indicators of PME exposure. Insect emergence was a highly relevant functional endpoint. When benthic and emerged insects were combined, total abundance increased with PME addition. Results from two trophic levels, which provided multiple lines of evidence, indicated that the main impact of these PME concentrations is nutrient enrichment rather than effluent toxicity. Our findings also suggest that benthic invertebrate and periphyton assemblages, algal biomass production, and insect emergence are sensitive response measures. Future studies may confirm this observation. The consideration of both functional and structural endpoints at different trophic levels can greatly improve our understanding the effects of discharges to rivers. Such an understanding could not have been obtained using standard assessment techniques and illustrates the value of mesocosms and the benthic community assemblage approach in environmental assessment.

Meta-structure and tunable optical device including the same

DOEpatents

Han, Seunghoon; Papadakis, Georgia Theano; Atwater, Harry

2017-12-26

A meta-structure and a tunable optical device including the same are provided. The meta-structure includes a plurality of metal layers spaced apart from one another, an active layer spaced apart from the plurality of metal layers and having a carrier concentration that is tuned according to an electric signal applied to the active layer and the plurality of metal layers, and a plurality of dielectric layers spaced apart from one another and each having one surface contacting a metal layer among the plurality of metal layers and another surface contacting the active layer.

Airborne contaminants during controlled residential fires.

PubMed

Fent, Kenneth W; Evans, Douglas E; Babik, Kelsey; Striley, Cynthia; Bertke, Stephen; Kerber, Steve; Smith, Denise; Horn, Gavin P

2018-05-01

In this study, we characterize the area and personal air concentrations of combustion byproducts produced during controlled residential fires with furnishings common in 21 st century single family structures. Area air measurements were collected from the structure during active fire and overhaul (post suppression) and on the fireground where personnel were operating without any respiratory protection. Personal air measurements were collected from firefighters assigned to fire attack, victim search, overhaul, outside ventilation, and command/pump operator positions. Two different fire attack tactics were conducted for the fires (6 interior and 6 transitional) and exposures were compared between the tactics. For each of the 12 fires, firefighters were paired up to conduct each job assignment, except for overhaul that was conducted by 4 firefighters. Sampled compounds included polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs, e.g., benzene), hydrogen cyanide (HCN), and particulate (area air sampling only). Median personal air concentrations for the attack and search firefighters were generally well above applicable short-term occupational exposure limits, with the exception of HCN measured from search firefighters. Area air concentrations of all measured compounds decreased after suppression. Personal air concentrations of total PAHs and benzene measured from some overhaul firefighters exceeded exposure limits. Median personal air concentrations of HCN (16,300 ppb) exceeded the exposure limit for outside vent firefighters, with maximum levels (72,900 ppb) higher than the immediately dangerous to life and health (IDLH) level. Median air concentrations on the fireground (including particle count) were above background levels and highest when collected downwind of the structure and when ground-level smoke was the heaviest. No statistically significant differences in personal air concentrations were found between the 2 attack tactics. The results underscore the importance of wearing self-contained breathing apparatus when conducting overhaul or outside ventilation activities. Firefighters should also try to establish command upwind of the structure fire, and if this cannot be done, respiratory protection should be considered.

Influence of lyophilization factors and gelatin concentration on pore structures of atelocollagen/gelatin sponge biomaterial.

PubMed

Yang, Longqiang; Tanabe, Koji; Miura, Tadashi; Yoshinari, Masao; Takemoto, Shinji; Shintani, Seikou; Kasahara, Masataka

2017-07-26

This study aimed to investigate influences of lyophilization factors and gelatin concentration on pore structures of ACG sponge. ACG sponges of different freezing temperatures (-30, -80 and -196 o C), freezing times (1, 2 and 24 h), gelatin concentrations (0.6%AC+0.15%G, 0.6%AC+0.6%G and 0.6%AC+2.4%G), and with 500 μM fluvastatin were fabricated. Pore structures including porosity and pore size were analyzed by scanning electron microscopy and ImageJ. The cytotoxic effects of ACG sponges were evaluated in vitro. Freezing temperature did not affect porosity while high freezing temperature (-30 o C) increased pore size. The high gelatin concentration group (0.6%AC+2.4%G) had decreased porosity and pore size. Freezing time and 500 μM fluvastatin did not affect pore structures. The cytotoxicity and cell proliferation assays revealed that ACG sponges had no cytotoxic effects on human mesenchymal stromal cell growth and proliferation. These results indicate that ACG sponge may be a good biomaterial scaffold for bone regeneration.

Kinetics and mechanism of catalytic hydroprocessing of components of coal-derived liquids. Sixteenth quarterly report, February 16, 1983-May 15, 1983.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gates, B. C.; Olson, H. H.; Schuit, G. C.A.

1983-08-22

A new method of structural analysis is applied to a group of hydroliquefied coal samples. The method uses elemental analysis and NMR data to estimate the concentrations of functional groups in the samples. The samples include oil and asphaltene fractions obtained in a series of hydroliquefaction experiments, and a set of 9 fractions separated from a coal-derived oil. The structural characterization of these samples demonstrates that estimates of functional group concentrations can be used to provide detailed structural profiles of complex mixtures and to obtain limited information about reaction pathways. 11 references, 1 figure, 7 tables.

Exotensioned structural members with energy-absorbing effects

DOEpatents

Brockwell, Michael Ian

2014-01-07

Structural members having enhanced load bearing capacity per unit mass include a skeleton structure formed from strips of material. Notches may be placed on the strips and a weave of tensile material placed in the notches and woven around the skeleton structure. At least one pair of structural members can be jointed together to provide very strong joints due to a weave patterns of tensile material, such as Kevlar, that distributes stress throughout the structure, preventing stress from concentrating in one area. Methods of manufacturing such structural members include molding material into skeletons of desired cross section using a matrix of molding segments. Total catastrophic failures in composite materials are substantially avoided and the strength to weight ratio of structures can be increased.

Exotensioned structural members with energy-absorbing effects

DOEpatents

Brockwell, Michael Ian

2017-08-22

Structural members having enhanced load bearing capacity per unit mass include a skeleton structure formed from strips of material. Notches may be placed on the strips and a weave of tensile material placed in the notches and woven around the skeleton structure. At least one pair of structural members can be jointed together to provide very strong joints due to a weave patterns of tensile material, such as Kevlar, that distributes stress throughout the structure, preventing stress from concentrating in one area. Methods of manufacturing such structural members include molding material into skeletons of desired cross section using a matrix of molding segments. Total catastrophic failures in composite materials are substantially avoided and the strength to weight ratio of structures can be increased.

Exotensioned structural members with energy-absorbing effects

DOEpatents

Brockwell, Michael Ian

2015-08-11

Structural members having enhanced load bearing capacity per unit mass include a skeleton structure formed from strips of material. Notches may be placed on the strips and a weave of tensile material placed in the notches and woven around the skeleton structure. At least one pair of structural members can be jointed together to provide very strong joints due to a weave patterns of tensile material, such as Kevlar, that distributes stress throughout the structure, preventing stress from concentrating in one area. Methods of manufacturing such structural members include molding material into skeletons of desired cross section using a matrix of molding segments. Total catastrophic failures in composite materials are substantially avoided and the strength to weight ratio of structures can be increased.

Holliday Junction Thermodynamics and Structure: Coarse-Grained Simulations and Experiments

NASA Astrophysics Data System (ADS)

Wang, Wujie; Nocka, Laura M.; Wiemann, Brianne Z.; Hinckley, Daniel M.; Mukerji, Ishita; Starr, Francis W.

2016-03-01

Holliday junctions play a central role in genetic recombination, DNA repair and other cellular processes. We combine simulations and experiments to evaluate the ability of the 3SPN.2 model, a coarse-grained representation designed to mimic B-DNA, to predict the properties of DNA Holliday junctions. The model reproduces many experimentally determined aspects of junction structure and stability, including the temperature dependence of melting on salt concentration, the bias between open and stacked conformations, the relative populations of conformers at high salt concentration, and the inter-duplex angle (IDA) between arms. We also obtain a close correspondence between the junction structure evaluated by all-atom and coarse-grained simulations. We predict that, for salt concentrations at physiological and higher levels, the populations of the stacked conformers are independent of salt concentration, and directly observe proposed tetrahedral intermediate sub-states implicated in conformational transitions. Our findings demonstrate that the 3SPN.2 model captures junction properties that are inaccessible to all-atom studies, opening the possibility to simulate complex aspects of junction behavior.

Flame Radiation, Structure, and Scalar Properties in Microgravity Laminar Fires

NASA Technical Reports Server (NTRS)

Feikema, Douglas; Lim, Jongmook; Sivathanu, Yudaya

2007-01-01

Results from microgravity combustion experiments conducted in the Zero Gravity Research Facility (ZGF) 5.18 second drop facility are reported. The results quantify flame radiation, structure, and scalar properties during the early phase of a microgravity fire. Emission mid-infrared spectroscopy measurements have been completed to quantitatively determine the flame temperature, water and carbon dioxide vapor concentrations, radiative emissive power, and soot concentrations in microgravity laminar methane/air, ethylene/nitrogen/air and ethylene/air jet flames. The measured peak mole fractions for water vapor and carbon dioxide are found to be in agreement with state relationship predictions for hydrocarbon/air combustion. The ethylene/air laminar flame conditions are similar to previously reported results including those from the flight project, Laminar Soot Processes (LSP). Soot concentrations and gas temperatures are in reasonable agreement with similar results available in the literature. However, soot concentrations and flame structure dramatically change in long-duration microgravity laminar diffusion flames as demonstrated in this report.

Binary colloidal structures assembled through Ising interactions

NASA Astrophysics Data System (ADS)

Khalil, Karim S.; Sagastegui, Amanda; Li, Yu; Tahir, Mukarram A.; Socolar, Joshua E. S.; Wiley, Benjamin J.; Yellen, Benjamin B.

2012-04-01

New methods for inducing microscopic particles to assemble into useful macroscopic structures could open pathways for fabricating complex materials that cannot be produced by lithographic methods. Here we demonstrate a colloidal assembly technique that uses two parameters to tune the assembly of over 20 different pre-programmed structures, including kagome, honeycomb and square lattices, as well as various chain and ring configurations. We programme the assembled structures by controlling the relative concentrations and interaction strengths between spherical magnetic and non-magnetic beads, which behave as paramagnetic or diamagnetic dipoles when immersed in a ferrofluid. A comparison of our experimental observations with potential energy calculations suggests that the lowest energy configuration within binary mixtures is determined entirely by the relative dipole strengths and their relative concentrations.

Neighborhood and School Ethnic Structuring and Cultural Adaptations among Mexican-Origin Adolescents

ERIC Educational Resources Information Center

White, Rebecca M. B.; Updegraff, Kimberly A.; Umaña-Taylor, Adriana J.; Zeiders, Katharine H.; Perez-Brena, Norma; Burleson, Elizabeth

2017-01-01

The ethnic and racial structuring of U.S. neighborhoods may have important implications for developmental competencies during adolescence, including the development of heritage and mainstream cultural orientations. In particular, living in highly concentrated Latino neighborhoods during early adolescence--which channels adolescents into related…

Nitrate removal in stream ecosystems measured by 15N addition experiments: Total uptake

USGS Publications Warehouse

Hall, R.O.; Tank, J.L.; Sobota, D.J.; Mulholland, P.J.; O'Brien, J. M.; Dodds, W.K.; Webster, J.R.; Valett, H.M.; Poole, G.C.; Peterson, B.J.; Meyer, J.L.; McDowell, W.H.; Johnson, S.L.; Hamilton, S.K.; Grimm, N. B.; Gregory, S.V.; Dahm, Clifford N.; Cooper, L.W.; Ashkenas, L.R.; Thomas, S.M.; Sheibley, R.W.; Potter, J.D.; Niederlehner, B.R.; Johnson, L.T.; Helton, A.M.; Crenshaw, C.M.; Burgin, A.J.; Bernot, M.J.; Beaulieu, J.J.; Arangob, C.P.

2009-01-01

We measured uptake length of 15NO-3 in 72 streams in eight regions across the United States and Puerto Rico to develop quantitative predictive models on controls of NO-3 uptake length. As part of the Lotic Intersite Nitrogen eXperiment II project, we chose nine streams in each region corresponding to natural (reference), suburban-urban, and agricultural land uses. Study streams spanned a range of human land use to maximize variation in NO-3 concentration, geomorphology, and metabolism. We tested a causal model predicting controls on NO-3 uptake length using structural equation modeling. The model included concomitant measurements of ecosystem metabolism, hydraulic parameters, and nitrogen concentration. We compared this structural equation model to multiple regression models which included additional biotic, catchment, and riparian variables. The structural equation model explained 79% of the variation in log uptake length (S Wtot). Uptake length increased with specific discharge (Q/w) and increasing NO-3 concentrations, showing a loss in removal efficiency in streams with high NO-3 concentration. Uptake lengths shortened with increasing gross primary production, suggesting autotrophic assimilation dominated NO-3 removal. The fraction of catchment area as agriculture and suburban-urban land use weakly predicted NO-3 uptake in bivariate regression, and did improve prediction in a set of multiple regression models. Adding land use to the structural equation model showed that land use indirectly affected NO-3 uptake lengths via directly increasing both gross primary production and NO-3 concentration. Gross primary production shortened SWtot, while increasing NO-3 lengthened SWtot resulting in no net effect of land use on NO- 3 removal. ?? 2009.

Ecohydrological Responses of Dense Canopies to Environmental Variability Part 1: Interplay Between Vertical Structure and Photosynthetic Pathway

USDA-ARS?s Scientific Manuscript database

Vegetation acclimation to changing climate, in particular elevated atmospheric concentrations of carbon dioxide (CO2), has been observed to include modifications to the biochemical and eco physiological functioning of leaves and the structural components of the canopy. These responses have the poten...

Biosensing based on magnetically induced self-assembly of particles in magnetic colloids.

PubMed

Yang, Ye; Morimoto, Yoshitaka; Takamura, Tsukasa; Sandhu, Adarsh

2012-03-01

Superparamagnetic beads and nonmagnetic beads of different sizes were assembled to form a "ring-structure" in a magnetorheological (MR) fluid solution by the application of external magnetic fields. For superparamagnetic beads and non-magnetic beads functionalized with probe and target molecules, respectively, the ring-structure was maintained even after removing the external magnetic field due to biomolecular bonding. Several experiments are described, including the formation process of ring-structures with and without molecular interactions, the accelerating effect of external magnetic fields, and the effect of biotin concentration on the structures of the rings. We define the small nonmagnetic particles as "petals" because the whole structure looks like a flower. The number of remnant ring petals was a function of the concentration of target molecules in the concentration range of 0.0768 ng/ml-3.8419 ng/ml which makes this protocol a promising method for biosensing. Not only was the formation process rapid, but the resulting two-dimensional colloidal system also offers a simple method for reducing reagent consumption and waste generation.

ANTI-ADHESIVE AND ANTI-BIOFILM ACTIVITIES IN VITRO OF LINEZOLID, VANCOMYCIN, TIGECYCLINE AND DAPTOMYCIN AGAINST STAPHYLOCOCCUS HAEMOLYTICUS.

PubMed

Juda, Marek; Helon, Pawel; Malm, Anna

2016-11-01

Biofilm may be formed on wide variety of surfaces, including indwelling medical devices, leading to several infectious diseases, e.g., bacteremia and sepsis. The most,important pathogens related with infections associated with medical devices are coagulase-negative staphylococci, including Staphylococcus haeinolyticus - bacterial species which express quite often the multidrug resistance. The four clinical multiresistant and methicillin-resistant S. haenzolyticus were included in the present study. The evaluation of drug susceptibility was performed by using disc-diffusion method and broth microdilution method according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines. The biofilm formation on the Nelaton catheter and the effect of linezolid, vancomycin, tigecycline and daptomycin on the biofilm formation and disruption of mature structure was based on the method with TTC (2,3,5-triphenyltetrazolium chloride). The adhesion process of S. haenzolyticus to the Nelaton catheter was inhibited by antibiotics, as follows: line-zolid at concentration 0.25-0.5 x MIC, vancomycin - concentration 0.5 x MIC, tigecycline - concentration 0.25-4 x MIC and daptomycin - concentration 0.06-1 x MIC, depending on the isolate. Linezolid inhibited the biofilm formation at concentration between 0.5-1 x MIC, vancomycin - 1-2 x MIC, tigecycline - 0.5-4 x MIC and daptomycin - 0.06-2 x MIC. The concentration of linezolid eradicating the mature biofilm was found to be 1-2 x MIC, vancomycin - 2-8 x MIC, tigecycline - 2-4 x MIC and daptomycin - 0.06-2 x MIC. The most active antibiotic against S. haentolyticus biofilm formation and disruption of mature structure seems to be daptomycin.

Biocatalytic induction of supramolecular order

NASA Astrophysics Data System (ADS)

Hirst, Andrew R.; Roy, Sangita; Arora, Meenakshi; Das, Apurba K.; Hodson, Nigel; Murray, Paul; Marshall, Stephen; Javid, Nadeem; Sefcik, Jan; Boekhoven, Job; van Esch, Jan H.; Santabarbara, Stefano; Hunt, Neil T.; Ulijn, Rein V.

2010-12-01

Supramolecular gels, which demonstrate tunable functionalities, have attracted much interest in a range of areas, including healthcare, environmental protection and energy-related technologies. Preparing these materials in a reliable manner is challenging, with an increased level of kinetic defects observed at higher self-assembly rates. Here, by combining biocatalysis and molecular self-assembly, we have shown the ability to more quickly access higher-ordered structures. By simply increasing enzyme concentration, supramolecular order expressed at molecular, nano- and micro-levels is dramatically enhanced, and, importantly, the gelator concentrations remain identical. Amphiphile molecules were prepared by attaching an aromatic moiety to a dipeptide backbone capped with a methyl ester. Their self-assembly was induced by an enzyme that hydrolysed the ester. Different enzyme concentrations altered the catalytic activity and size of the enzyme clusters, affecting their mobility. This allowed structurally diverse materials that represent local minima in the free energy landscape to be accessed based on a single gelator structure.

Osmium-Isotope and Platinum-Group-Element Systematics of Impact-Melt Rocks, Chesapeake Bay Impact Structure, Virginia, USA

NASA Technical Reports Server (NTRS)

Lee, Seung Ryeol; Wright Horton, J., Jr.; Walker, Richard J.

2005-01-01

Osmium (Os) isotopes and platinum-group elements (PGEs) are useful for geochemically identifying a meteoritic component within impact structures, because meteorites are typically characterized by low (187)Os/(188)Os ratios and high PGE concentrations. In contrast, most types of crustal target rocks have high radiogenic Os and very low PGE concentrations. We have examined Os isotope and PGE systematics of impact-melt rocks and pre-impact target rocks from a 2004 test hole in the late Eocene Chesapeake Bay impact structure and from nearby coreholes. Our goal is to determine the proportion of the projectile component in the melt rock Additional information is included in the original extended abstract.

Treatment of high ethanol concentration wastewater by biological sand filters: enhanced COD removal and bacterial community dynamics.

PubMed

Rodriguez-Caballero, A; Ramond, J-B; Welz, P J; Cowan, D A; Odlare, M; Burton, S G

2012-10-30

Winery wastewater is characterized by its high chemical oxygen demand (COD), seasonal occurrence and variable composition, including periodic high ethanol concentrations. In addition, winery wastewater may contain insufficient inorganic nutrients for optimal biodegradation of organic constituents. Two pilot-scale biological sand filters (BSFs) were used to treat artificial wastewater: the first was amended with ethanol and the second with ethanol, inorganic nitrogen (N) and phosphorus (P). A number of biochemical parameters involved in the removal of pollutants through BSF systems were monitored, including effluent chemistry and bacterial community structures. The nutrient supplemented BSF showed efficient COD, N and P removal. Comparison of the COD removal efficiencies of the two BSFs showed that N and P addition enhanced COD removal efficiency by up to 16%. Molecular fingerprinting of BSF sediment samples using denaturing gradient gel electrophoresis (DGGE) showed that amendment with high concentrations of ethanol destabilized the microbial community structure, but that nutrient supplementation countered this effect. Copyright © 2012 Elsevier Ltd. All rights reserved.

Development of a dome Fresnel lens/gallium arsenide photovoltaic concentrator for space applications

NASA Technical Reports Server (NTRS)

O'Neill, Mark J.; Piszczor, Michael F.

1987-01-01

A novel photovoltaic concentrator system is currently being developed. Phase I of the program, completed in late 1986, produced a conceptual design for the concentrator system, including an array weight and performance estimates based on optical, electrical, and thermal analyses. Phase II of the program, just underway, concerns the fabrication and testing of prototype concentrator panels of the design. The concentrator system uses dome Fresnel lenses for optical concentration; gallium arsenide concentrator cells for power generation; prismatic cell covers to eliminate gridline obscuration losses; a backplane radiator for heat rejection; and a honeycomb structure for the deployable panel assembly. The conceptual design of the system, its anticipated performance, and its estimated weight are reported.

Hierarchical structure and physicochemical properties of plasticized chitosan.

PubMed

Meng, Qingkai; Heuzey, Marie-Claude; Carreau, Pierre J

2014-04-14

Plasticized chitosan with hierarchical structure, including multiple length scale structural units, was prepared by a "melt"-based method, that is, thermomechanical mixing, as opposed to the usual casting-evaporation procedure. Chitosan was successfully plasticized by thermomechanical mixing in the presence of concentrated lactic acid and glycerol using a batch mixer. Different plasticization formulations were compared in this study, in which concentrated lactic acid was used as protonation agent as well as plasticizer. The microstructure of thermomechanically plasticized chitosan was investigated by X-ray diffraction, scanning electron microscopy, and optical microscopy. With increasing amount of additional plasticizers (glycerol or water), the crystallinity of the plasticized chitosan decreased from 63.7% for the original chitosan powder to almost zero for the sample plasticized with additional water. Salt linkage between lactic acid molecules and amino side chains of chitosan was confirmed by FTIR spectroscopy: the lactic acid molecules expanded the space between the chitosan molecules of the crystalline phase. In the presence of other plasticizers (glycerol and water), various levels of structural units including an amorphous phase, nanofibrils, nanofibril clusters, and microfibers were produced under mechanical shear and thermal energy and identified for the first time. The thermal and thermomechanical properties of the plasticized chitosan were measured by thermogravimetric analysis, differential scanning calorimetric, and DMA. These properties were correlated with the different levels of microstructure, including multiple structural units.

Design for progressive fracture in composite shell structures

NASA Technical Reports Server (NTRS)

Minnetyan, Levon; Murthy, Pappu L. N.

1992-01-01

The load carrying capability and structural behavior of composite shell structures and stiffened curved panels are investigated to provide accurate early design loads. An integrated computer code is utilized for the computational simulation of composite structural degradation under practical loading for realistic design. Damage initiation, growth, accumulation, and propagation to structural fracture are included in the simulation. Progressive fracture investigations providing design insight for several classes of composite shells are presented. Results demonstrate the significance of local defects, interfacial regions, and stress concentrations on the structural durability of composite shells.

Market Structure, Financial Dependence and Industrial Growth: Evidence from the Banking Industry in Emerging Asian Economies.

PubMed

Khan, Habib Hussain; Ahmad, Rubi Binit; Gee, Chan Sok

2016-01-01

In this study, we examine the role of market structure for growth in financially dependent industries from 10 emerging Asian economies over the period of 1995-2011. Our approach departs from existing studies in that we apply four alternative measures of market structure based on structural and non-structural approaches and compare their outcomes. Results indicate that higher bank concentration may slow down the growth of financially dependent industries. Bank competition on the other hand, allows financially dependent industries to grow faster. These findings are consistent across a number of sensitivity checks such as alternative measures of financial dependence, institutional factors (including property rights, quality of accounting standards and bank ownership), and endogeneity consideration. In sum, our study suggests that financially dependent industries grow more in more competitive/less concentrated banking systems. Therefore, regulatory authorities need to be careful while pursuing a consolidation policy for banking sector in emerging Asian economies.

Static ferroelectric memory transistor having improved data retention

DOEpatents

Evans, Jr., Joseph T.; Warren, William L.; Tuttle, Bruce A.

1996-01-01

An improved ferroelectric FET structure in which the ferroelectric layer is doped to reduce retention loss. A ferroelectric FET according to the present invention includes a semiconductor layer having first and second contacts thereon, the first and second contacts being separated from one another. The ferroelectric FET also includes a bottom electrode and a ferroelectric layer which is sandwiched between the semiconductor layer and the bottom electrode. The ferroelectric layer is constructed from a perovskite structure of the chemical composition ABO.sub.3 wherein the B site comprises first and second elements and a dopant element that has an oxidation state greater than +4 in sufficient concentration to impede shifts in the resistance measured between the first and second contacts with time. The ferroelectric FET structure preferably comprises Pb in the A-site. The first and second elements are preferably Zr and Ti, respectively. The preferred B-site dopants are Niobium, Tantalum, and Tungsten at concentrations between 1% and 8%.

Determinants of Market Structure and the Airline Industry

NASA Technical Reports Server (NTRS)

Raduchel, W.

1972-01-01

The general economic determinants of market structure are outlined with special reference to the airline industry. Included are the following facets: absolute size of firms; distributions of firms by size; concentration; entry barriers; product and service differentiation; diversification; degrees of competition; vertical integration; market boundaries; and economies of scale. Also examined are the static and dynamic properties of market structure in terms of mergers, government policies, and economic growth conditions.

Pilot Intervention Study of Household Ventilation and Fine Particulate Matter Concentrations in a Low-Income Urban Area, Dhaka, Bangladesh.

PubMed

Weaver, Anne M; Parveen, Shahana; Goswami, Doli; Crabtree-Ide, Christina; Rudra, Carole; Yu, Jihnhee; Mu, Lina; Fry, Alicia M; Sharmin, Iffat; Luby, Stephen P; Ram, Pavani K

2017-08-01

Fine particulate matter (PM 2.5 ) is a risk factor for pneumonia; ventilation may be protective. We tested behavioral and structural ventilation interventions on indoor PM 2.5 in Dhaka, Bangladesh. We recruited 59 good ventilation (window or door in ≥ 3 walls) and 29 poor ventilation (no window, one door) homes. We monitored baseline indoor and outdoor PM 2.5 for 48 hours. We asked all participants to increase ventilation behavior, including opening windows and doors, and operating fans. Where permitted, we installed windows in nine poor ventilation homes, then repeated PM 2.5 monitoring. We estimated effects using linear mixed-effects models and conducted qualitative interviews regarding motivators and barriers to ventilation. Compared with poor ventilation homes, good ventilation homes were larger, their residents wealthier and less likely to use biomass fuel. In multivariable linear mixed-effects models, ventilation structures and opening a door or window were inversely associated with the number of hours PM 2.5 concentrations exceeded 100 and 250 μg/m 3 . Outdoor air pollution was positively associated with the number of hours PM 2.5 concentrations exceeded 100 and 250 μg/m 3 . Few homes accepted window installation, due to landlord refusal and fear of theft. Motivators for ventilation behavior included cooling of the home and sunlight; barriers included rain, outdoor odors or noise, theft risk, mosquito entry, and, for fan use, perceptions of wasting electricity or unavailability of electricity. We concluded that ventilation may reduce indoor PM 2.5 concentrations but, there are barriers to increasing ventilation and, in areas with high ambient PM 2.5 concentrations, indoor concentrations may remain above recommended levels.

Necessary Conditions for Intraplate Seismic Zones in North America

NASA Astrophysics Data System (ADS)

Thomas, William A.; Powell, Christine A.

2017-12-01

The cause of intraplate seismic zones persists as an important scientific and societal question. Most intraplate earthquakes are concentrated in specific seismic zones along or adjacent to large-scale basement structures (e.g., rifts or sutures at ancient plate boundaries) within continental crust. The major intraplate seismic zones are limited to specific segments and are not distributed along the lengths of the ancient structures. We present a new hypothesis that major intraplate seismic zones are restricted to places where concentrated crustal deformation (CCD) is overprinted on large-scale basement structures. Examples where CCD affects the stability of specific parts of large-scale structures in response to present-day stress conditions include the most active seismic zones in central and eastern North America: Charlevoix, Eastern Tennessee, and New Madrid. Our hypothesis has important implications for the assessment of seismic hazards.

Anatomic and physiologic changes of the aging kidney.

PubMed

Karam, Zeina; Tuazon, Jennifer

2013-08-01

Aging is associated with structural and functional changes in the kidney. Structural changes include glomerulosclerosis, thickening of the basement membrane, increase in mesangial matrix, tubulointerstitial fibrosis and arteriosclerosis. Glomerular filtration rate is maintained until the fourth decade of life, after which it declines. Parallel reductions in renal blood flow occur with redistribution of blood flow from the cortex to the medulla. Other functional changes include an increase in glomerular basement permeability and decreased ability to dilute or concentrate urine. Copyright © 2013 Elsevier Inc. All rights reserved.

Solving the Problems of Iowa Food Deserts: Food Insecurity and Civic Structure

ERIC Educational Resources Information Center

Morton, Lois Wright; Bitto, Ella Annette; Oakland, Mary Jane; Sand, Mary

2005-01-01

Rural regions include places where food sources are not evenly distributed, leading to areas of concentration and food desert--places where few or no grocery stores exist. Individuals are hypothesized to depend on personal connections and the civic structure of where they live to help them solve the problem of food insecurity. We find that…

A Carbon Nanotube Pillar Array Ionizer for Miniature Ion Thruster Applications

DTIC Science & Technology

2008-12-01

interest in using argon as a propellant. The advantages of argon go beyond its low cost to include its inertness, which makes it safe to handle and...They can be formed either as single- walled structures (SWCNTs), as shown in Figure 5, or as multi-walled structures ( MWCNTs ), as shown in Figure 6...The structure in Figure 6 is known as a Russian Doll MWCNT due to its structure of concentric individual CNTs. There is another type of MWCNT known

Spatial and seasonal variations in mercury methylation and microbial community structure in a historic mercury mining area, Yolo County, California

USGS Publications Warehouse

Holloway, J.M.; Goldhaber, M.B.; Scow, K.M.; Drenovsky, R.E.

2009-01-01

The relationships between soil parent lithology, nutrient concentrations, microbial biomass and community structure were evaluated in soils from a small watershed impacted by historic Hg mining. Upland and wetland soils, stream sediments and tailings were collected and analyzed for nutrients (DOC, SO4=, NO3-), Hg, MeHg, and phospholipid fatty acids (PLFA). Stream sediment was derived from serpentinite, siltstone, volcanic rocks and mineralized serpentine with cinnabar, metacinnabar and other Hg phases. Soils from different parent materials had distinct PLFA biomass and community structures that are related to nutrient concentrations and toxicity effects of trace metals including Hg. The formation of MeHg appears to be most strongly linked to soil moisture, which in turn has a correlative relationship with PLFA biomass in wetland soils. The greatest concentrations of MeHg (> 0.5??ng g- 1 MeHg) were measured in wetland soils and soil with a volcanic parent (9.5-37????g g- 1 Hg). Mercury methylation was associated with sulfate-reducing bacteria, including Desulfobacter sp. and Desulfovibrio sp., although these organisms are not exclusively responsible for Hg methylation. Statistical models of the data demonstrated that soil microbial communities varied more with soil type than with season.

Concentration-Discharge Relations in the Critical Zone: Implications for Resolving Critical Zone Structure, Function, and Evolution

NASA Astrophysics Data System (ADS)

Chorover, Jon; Derry, Louis A.; McDowell, William H.

2017-11-01

Critical zone science seeks to develop mechanistic theories that describe critical zone structure, function, and long-term evolution. One postulate is that hydrogeochemical controls on critical zone evolution can be inferred from solute discharges measured down-gradient of reactive flow paths. These flow paths have variable lengths, interfacial compositions, and residence times, and their mixing is reflected in concentration-discharge (C-Q) relations. Motivation for this special section originates from a U.S. Critical Zone Observatories workshop that was held at the University of New Hampshire, 20-22 July 2015. The workshop focused on resolving mechanistic CZ controls over surface water chemical dynamics across the full range of lithogenic (e.g., nonhydrolyzing and hydrolyzing cations and oxyanions) and bioactive solutes (e.g., organic and inorganic forms of C, N, P, and S), including dissolved and colloidal species that may cooccur for a given element. Papers submitted to this special section on "concentration-discharge relations in the critical zone" include those from authors who attended the workshop, as well as others who responded to the open solicitation. Submissions were invited that utilized information pertaining to internal, integrated catchment function (relations between hydrology, biogeochemistry, and landscape structure) to help illuminate controls on observed C-Q relations.

The Effect of Complex Solvents on the Structure and Dynamics of Protein Solutions: the case of Lysozyme in Trehalose/Water Mixtures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghattyvenkatakrishna, Pavan K; Carri, Gustavo A.

We present a Molecular Dynamics simulation study of the effect of trehalose concentration on the structure and dynamics of individual proteins immersed in trehalose/water mixtures. Hen Egg White Lysozyme is used in this study and trehalose concentrations of 0%, 10%, 20%, 30% and 100% by weight are explored. Surprisingly, we have found that changes in trehalose concentration do not change the global structural characteristics of the protein as measured by standard quantities like the mean square deviation, radius of gyration, solvent accessible surface area, inertia tensor and asphericity. Only in the limit of pure trehalose these metrics change significantly. Specifically,more » we found that the protein is compressed by 2% when immersed in pure trehalose. At the amino acid level there is noticeable rearrangement of the surface residues due to the change in polarity of the surrounding environment with the addition of trehalose. From a dynamic perspective, our computation of the Incoherent Intermediate Scattering Function shows that the protein slows down with increasing trehalose concentration; however, this slowdown is not monotonic. Finally, we also report in-depth results for the hydration layer around the protein including its structure, hydrogen- bonding characteristics and dynamic behavior at different length scales.« less

Micro-photoluminescence of GaAs/AlGaAs triple concentric quantum rings.

PubMed

Abbarchi, Marco; Cavigli, Lucia; Somaschini, Claudio; Bietti, Sergio; Gurioli, Massimo; Vinattieri, Anna; Sanguinetti, Stefano

2011-10-31

A systematic optical study, including micro, ensemble and time resolved photoluminescence of GaAs/AlGaAs triple concentric quantum rings, self-assembled via droplet epitaxy, is presented. Clear emission from localized states belonging to the ring structures is reported. The triple rings show a fast decay dynamics, around 40 ps, which is expected to be useful for ultrafast optical switching applications.

Quantifying Mass Transfer Processes in Groundwater as a Function of Molecular Structure Variation for Multicomponent NAPL Sources

NASA Astrophysics Data System (ADS)

Abbott, J. B., III; Tick, G. R.; Greenberg, R. R.; Carroll, K. C.

2017-12-01

The remediation of nonaqueous liquid (NAPL) contamination sources in groundwater has been shown to be challenging and have limited success in the field. The presence of multicomponent NAPL sources further complicates the remediation due to variability of mass-transfer (dissolution) behavior as a result of compositional and molecular structure variations between the different compounds within the NAPL phase. This study investigates the effects of the contaminant of concern (COC) composition and the bulk-NAPL components molecular structure (i.e. carbon chain length, aliphatic and aromatic) on dissolution and aqueous phase concentrations in groundwater. The specific COCs tested include trichloroethene (TCE), toluene (TOL), and perfluorooctanoic acid (PFOA). Each COC was tested in a series of binary batch experiments using insoluble bulk NAPL including n-hexane (HEX), n-decane (DEC), and n-hexadecane (HEXDEC). These equilibrium batch tests were performed to understand how different carbon-chain-length (NAPL) systems affect resulting COC aqueous phase concentrations. The experiments were conducted with four different COC mole fractions mixed within the bulk-NAPL derivatives (0.1:0.9, 0.05:0.95, 0.01:0.99, 0.001:0.999). Raoult's Law was used to assess the relative ideality of the mass transfer processes for each binary equilibrium dissolution experiment. Preliminary results indicate that as mole fraction of the COC decreases (composition effects), greater deviance from dissolution ideality occurs. It was also shown that greater variation in molecular structure (i.e. greater carbon chain length of bulk-NAPL with COC and aromatic COC presence) exhibited greater dissolution nonideality via Raoult's Law analysis. For instance, TOL (aromatic structure) showed greater nonideality than TCE (aliphatic structure) in the presence of the different bulk-NAPL derivatives (i.e. of various aliphatic carbon chains lengths). The results suggest that the prediction of aqueous phase concentration, from complex multicomponent NAPL sources, is highly dependent upon both composition and molecular structure variations of COC-NAPL mixtures, and such impacts should be taken into account when designing and evaluating a remediation strategy and/or predicting COC concentrations from a source zone region.

Applications of the Cambridge Structural Database in organic chemistry and crystal chemistry.

PubMed

Allen, Frank H; Motherwell, W D Samuel

2002-06-01

The Cambridge Structural Database (CSD) and its associated software systems have formed the basis for more than 800 research applications in structural chemistry, crystallography and the life sciences. Relevant references, dating from the mid-1970s, and brief synopses of these papers are collected in a database, DBUse, which is freely available via the CCDC website. This database has been used to review research applications of the CSD in organic chemistry, including supramolecular applications, and in organic crystal chemistry. The review concentrates on applications that have been published since 1990 and covers a wide range of topics, including structure correlation, conformational analysis, hydrogen bonding and other intermolecular interactions, studies of crystal packing, extended structural motifs, crystal engineering and polymorphism, and crystal structure prediction. Applications of CSD information in studies of crystal structure precision, the determination of crystal structures from powder diffraction data, together with applications in chemical informatics, are also discussed.

Characterization of iron-phosphate-silicate chemical garden structures.

PubMed

Barge, Laura M; Doloboff, Ivria J; White, Lauren M; Stucky, Galen D; Russell, Michael J; Kanik, Isik

2012-02-28

Chemical gardens form when ferrous chloride hydrate seed crystals are added or concentrated solutions are injected into solutions of sodium silicate and potassium phosphate. Various precipitation morphologies are observed depending on silicate and phosphate concentrations, including hollow plumes, bulbs, and tubes. The growth of precipitates is controlled by the internal osmotic pressure, fluid buoyancy, and membrane strength. Additionally, rapid bubble-led growth is observed when silicate concentrations are high. ESEM/EDX analysis confirms compositional gradients within the membranes, and voltage measurements across the membranes during growth show a final potential of around 150-200 mV, indicating that electrochemical gradients are maintained across the membranes as growth proceeds. The characterization of chemical gardens formed with iron, silicate, and phosphate, three important components of an early earth prebiotic hydrothermal system, can help us understand the properties of analogous structures that likely formed at submarine alkaline hydrothermal vents in the Hadean-structures offering themselves as the hatchery of life. © 2011 American Chemical Society

[Effects of alien species Robinia pseudoacacia on plant community functional structure in hilly-gully region of Loess Plateau, China.

PubMed

Zhu, Duo Ju; Wen, Zhong Ming; Zhang, Jing; Tao, Yu; Zeng, Hong Wen; Tang, Yang

2018-02-01

To investigate the effects of the introduction of Robinia pseudoacacia on the functional structure of plant communities, we selected paired-plots of R. pseudoacacia communities and native plant communities across different vegetation zones, i.e., steppe zone, forest-steppe zone, forest zone in hilly-gully region of Loess Plateau, China. We measured several functional characteristics and then compared the functional structures of R. pseudoacacia and native plant communities in different vegetation zones. The results showed that the variation of the functional traits across different vegetation zones were consistent in R. pseudoacacia community and native plant community, including leaf carbon concentration, leaf nitrogen concentration, leaf phosphorus concentration, specific leaf area, and leaf tissue density. The leaf carbon concentration, leaf nitrogen concentration, and specific leaf area of the R. pseudoacacia community were significantly higher than those of the native plant community. The trend of change that the functional diversity indices, i.e., FR ic , FE ve , FD iv , FD is , Rao of the R. pseudoacacia community and the native plant community with vegetation zones were different. The introduction of R. pseudoacacia enhanced the plant community functional diversity in the forest zone but reduced community functional diversity in the steppe zone.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

The Performance Prototype Trough (PPT) Concentrating Collector consists of four 80-foot modules in a 320-foot row. The collector was analyzed, including cost estimates and manufacturing processes to produce collectors in volumes from 100 to 100,000 modules per year. The four different reflector concepts considered were the sandwich reflector structure, sheet metal reflector structure, molded reflector structure, and glass laminate structure. The sheet metal and glass laminate structures are emphasized with their related structure concepts. A preliminary manufacturing plan is offered that includes: documentation of the manufacturing process with production flow diagrams; labor and material costs at various production levels; machinerymore » and equipment requirements including preliminary design specifications; and capital investment costs for a new plant. Of five reflector designs considered, the two judged best and considered at length are thin annealed glass and steel laminate on steel frame panel and thermally sagged glass. Also discussed are market considerations, costing and selling price estimates, design cost analysis and make/buy analysis. (LEW)« less

Advanced composite structures. [metal matrix composites - structural design criteria for spacecraft construction materials

NASA Technical Reports Server (NTRS)

1974-01-01

A monograph is presented which establishes structural design criteria and recommends practices to ensure the design of sound composite structures, including composite-reinforced metal structures. (It does not discuss design criteria for fiber-glass composites and such advanced composite materials as beryllium wire or sapphire whiskers in a matrix material.) Although the criteria were developed for aircraft applications, they are general enough to be applicable to space vehicles and missiles as well. The monograph covers four broad areas: (1) materials, (2) design, (3) fracture control, and (4) design verification. The materials portion deals with such subjects as material system design, material design levels, and material characterization. The design portion includes panel, shell, and joint design, applied loads, internal loads, design factors, reliability, and maintainability. Fracture control includes such items as stress concentrations, service-life philosophy, and the management plan for control of fracture-related aspects of structural design using composite materials. Design verification discusses ways to prove flightworthiness.

Introducing improved structural properties and salt dependence into a coarse-grained model of DNA

NASA Astrophysics Data System (ADS)

Snodin, Benedict E. K.; Randisi, Ferdinando; Mosayebi, Majid; Šulc, Petr; Schreck, John S.; Romano, Flavio; Ouldridge, Thomas E.; Tsukanov, Roman; Nir, Eyal; Louis, Ard A.; Doye, Jonathan P. K.

2015-06-01

We introduce an extended version of oxDNA, a coarse-grained model of deoxyribonucleic acid (DNA) designed to capture the thermodynamic, structural, and mechanical properties of single- and double-stranded DNA. By including explicit major and minor grooves and by slightly modifying the coaxial stacking and backbone-backbone interactions, we improve the ability of the model to treat large (kilobase-pair) structures, such as DNA origami, which are sensitive to these geometric features. Further, we extend the model, which was previously parameterised to just one salt concentration ([Na+] = 0.5M), so that it can be used for a range of salt concentrations including those corresponding to physiological conditions. Finally, we use new experimental data to parameterise the oxDNA potential so that consecutive adenine bases stack with a different strength to consecutive thymine bases, a feature which allows a more accurate treatment of systems where the flexibility of single-stranded regions is important. We illustrate the new possibilities opened up by the updated model, oxDNA2, by presenting results from simulations of the structure of large DNA objects and by using the model to investigate some salt-dependent properties of DNA.

Introducing improved structural properties and salt dependence into a coarse-grained model of DNA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Snodin, Benedict E. K., E-mail: benedict.snodin@chem.ox.ac.uk; Mosayebi, Majid; Schreck, John S.

2015-06-21

We introduce an extended version of oxDNA, a coarse-grained model of deoxyribonucleic acid (DNA) designed to capture the thermodynamic, structural, and mechanical properties of single- and double-stranded DNA. By including explicit major and minor grooves and by slightly modifying the coaxial stacking and backbone-backbone interactions, we improve the ability of the model to treat large (kilobase-pair) structures, such as DNA origami, which are sensitive to these geometric features. Further, we extend the model, which was previously parameterised to just one salt concentration ([Na{sup +}] = 0.5M), so that it can be used for a range of salt concentrations including thosemore » corresponding to physiological conditions. Finally, we use new experimental data to parameterise the oxDNA potential so that consecutive adenine bases stack with a different strength to consecutive thymine bases, a feature which allows a more accurate treatment of systems where the flexibility of single-stranded regions is important. We illustrate the new possibilities opened up by the updated model, oxDNA2, by presenting results from simulations of the structure of large DNA objects and by using the model to investigate some salt-dependent properties of DNA.« less

Design and analysis of composite structures with stress concentrations

NASA Technical Reports Server (NTRS)

Garbo, S. P.

1983-01-01

An overview of an analytic procedure which can be used to provide comprehensive stress and strength analysis of composite structures with stress concentrations is given. The methodology provides designer/analysts with a user-oriented procedure which, within acceptable engineering accuracy, accounts for the effects of a wide range of application design variables. The procedure permits the strength of arbitrary laminate constructions under general bearing/bypass load conditions to be predicted with only unnotched unidirectional strength and stiffness input data required. Included is a brief discussion of the relevancy of this analysis to the design of primary aircraft structure; an overview of the analytic procedure with theory/test correlations; and an example of the use and interaction of this strength analysis relative to the design of high-load transfer bolted composite joints.

High-Solids Polyimide Precursor Solutions

NASA Technical Reports Server (NTRS)

Chuang, Chun-Hua (Inventor)

2004-01-01

The invention is a highly concentrated stable solution of polymide precursors (monometers) having a solids content ranging from about 80 to 98 percent by weight in lower aliphatic alcohols i.e. methyl and/or ethylalcohol. the concentrated polyimide precursos solution comparisons effective amounts of at least one aromatic diamine, at least one aromatic dianhydride, and a monofunctional endcap including monoamines, monoanhydrides and lower alkyl esters of said monoanhydrides. These concentrated polyimide precursor solutions are particularly useful for the preparation of fibrous prepregs and composites for use in structural materials for military and civil applications.

Course of serum amyloid A (SAA) plasma concentrations in horses undergoing surgery for injuries penetrating synovial structures, an observational clinical study.

PubMed

Haltmayer, Eva; Schwendenwein, Ilse; Licka, Theresia F

2017-05-22

Injuries penetrating synovial structures are common in equine practice and often result in septic synovitis. Significantly increased plasma levels of serum amyloid A (SAA) have been found in various infectious conditions in horses including wounds and septic arthritis. Plasma SAA levels were found to decrease rapidly once the infectious stimulus was eliminated. The purpose of the current study was to investigate the usefulness of serial measurements of plasma SAA as a monitoring tool for the response to treatment of horses presented with injuries penetrating synovial structures. In the current study plasma SAA concentrations were measured every 48 hours (h) during the course of treatment. A total of 19 horses with a wound penetrating a synovial structure were included in the current study. Horses in Group 1 (n = 12) (injuries older than 24 h) only needed one surgical intervention. Patients in this group had significantly lower median plasma SAA levels (P = 0.001) between 48 h (median 776 mg/L) and 96 h (median 202 mg/L) after surgery. A significant decrease (P = 0.004) in plasma SAA levels was also observed between 96 h after surgery (median 270 mg/L) and 6 days (d) after surgery (median 3 mg/L). Four horses (Group 2) required more than one surgical intervention. In contrast to Group 1 patients in Group 2 had either very high initial plasma concentrations (3378 mg/L), an increase or persistently high concentrations of plasma SAA after the first surgery (median 2525 mg/L). A small group of patients (n = 3) (Group 3) were admitted less than 24 h after sustaining a wound. In this group low SAA values at admission (median 23 mg/L) and peak concentrations at 48 h after surgery (median 1016 mg/L) were observed followed by a decrease in plasma SAA concentration over time. A decrease in plasma SAA concentrations between two consecutive time points could be associated with positive response to treatment in the current study. Therefore, serial measurements of plasma SAA could potentially be used as an additional inexpensive, quick and easy tool for monitoring the treatment response in otherwise healthy horses presented with injuries penetrating synovial structures. However further studies will be necessary to ascertain its clinical utility.

Micro-photoluminescence of GaAs/AlGaAs triple concentric quantum rings

PubMed Central

2011-01-01

A systematic optical study, including micro, ensemble and time resolved photoluminescence of GaAs/AlGaAs triple concentric quantum rings, self-assembled via droplet epitaxy, is presented. Clear emission from localized states belonging to the ring structures is reported. The triple rings show a fast decay dynamics, around 40 ps, which is expected to be useful for ultrafast optical switching applications. PMID:22039893

Polydopamine-based concentric nanoshells with programmable architectures and plasmonic properties.

PubMed

Choi, Chun Kit K; Zhuo, Xiaolu; Chiu, Yee Ting Elaine; Yang, Hongrong; Wang, Jianfang; Choi, Chung Hang Jonathan

2017-11-09

Nanoshells, classically comprising gold as the metallic component and silica as the dielectric material, are important for fundamental studies in nanoplasmonics. They also empower a myriad of applications, including sensing, energy harvesting, and cancer therapy. Yet, laborious preparation precludes the development of next-generation nanoshells with structural complexity, compositional diversity, and tailorable plasmonic behaviors. This work presents an efficient approach to the bottom-up assembly of concentric nanoshells. By employing polydopamine as the dielectric material and exploiting its intrinsic adhesiveness and pH-tunable surface charge, the growth of each shell only takes 3-4 hours at room temperature. A series of polydopamine-based concentric nanoshells with programmable nanogap thickness, elemental composition (gold and silver), and geometrical configuration (number of layers) is prepared, followed by extensive structural characterization. Four of the silver-containing nanostructures are newly reported. Systematic investigations into the plasmonic properties of concentric nanoshells as a function of their structural parameters further reveal multiple Fano resonances and local-field "hot spots", infrequently reported plasmonic features for individual nanostructures fabricated using bottom-up wet chemistry. These results establish materials design rules for engineering complex plasmon-based systems originating from the integration of multiple plasmonic elements into defined locations within a compact nanostructure.

Interaction of chromatin with NaCl and MgCl2. Solubility and binding studies, transition to and characterization of the higher-order structure.

PubMed

Ausio, J; Borochov, N; Seger, D; Eisenberg, H

1984-08-15

Chicken erythrocyte chromatin containing histones H1 and H5 was carefully separated into a number of well-characterized fractions. A distinction could be made between chromatin insoluble in NaCl above about 80 mM, and chromatin soluble at all NaCl concentrations. Both chromatin forms were indistinguishable electrophoretically and both underwent the transition from the low salt "10 nm" coil to the "30 nm" higher-order structure solenoid by either raising the MgCl2 concentration to about 0.3 mM or the NaCl concentration to about 75 mM. The transitions were examined in detail by elastic light-scattering procedures. It could be shown that the 10 nm form is a flexible coil. For the 30 nm solenoid, the assumption of a rigid cylindrical structure was in good agreement with 5.7 nucleosomes per helical turn. However, disagreement of calculated frictional parameters with values derived from quasielastic light-scattering and sedimentation introduced the possibility that the higher-order structure, under these conditions, is more extended, flexible, or perhaps a mixture of structures. Values for density and refractive index increments of chromatin are also given. To understand the interaction of chromatin with NaCl and with MgCl2, a number of experiments were undertaken to study solubility, precipitation, conformational transitions and binding of ions over a wide range of experimental conditions, including chromatin concentration.

Market Structure, Financial Dependence and Industrial Growth: Evidence from the Banking Industry in Emerging Asian Economies

PubMed Central

Khan, Habib Hussain; Ahmad, Rubi Binit; Gee, Chan Sok

2016-01-01

In this study, we examine the role of market structure for growth in financially dependent industries from 10 emerging Asian economies over the period of 1995–2011. Our approach departs from existing studies in that we apply four alternative measures of market structure based on structural and non-structural approaches and compare their outcomes. Results indicate that higher bank concentration may slow down the growth of financially dependent industries. Bank competition on the other hand, allows financially dependent industries to grow faster. These findings are consistent across a number of sensitivity checks such as alternative measures of financial dependence, institutional factors (including property rights, quality of accounting standards and bank ownership), and endogeneity consideration. In sum, our study suggests that financially dependent industries grow more in more competitive/less concentrated banking systems. Therefore, regulatory authorities need to be careful while pursuing a consolidation policy for banking sector in emerging Asian economies. PMID:27490847

Dispersion in Fractures with Ramified Dissolution Patterns

NASA Astrophysics Data System (ADS)

Xu, Le; Marks, Benjy; Toussaint, Renaud; Flekkøy, Eirik G.; Måløy, Knut J.

2018-04-01

The injection of a reactive fluid into an open fracture may modify the fracture surface locally and create a ramified structure around the injection point. This structure will have a significant impact on the dispersion of the injected fluid due to increased permeability, which will introduce large velocity fluctuations into the fluid. Here, we have injected a fluorescent tracer fluid into a transparent artificial fracture with such a ramified structure. The transparency of the model makes it possible to follow the detailed dispersion of the tracer concentration. The experiments have been compared to two dimensional (2D) computer simulations which include both convective motion and molecular diffusion. A comparison was also performed between the dispersion from an initially ramified dissolution structure and the dispersion from an initially circular region. A significant difference was seen both at small and large length scales. At large length scales, the persistence of the anisotropy of the concentration distribution far from the ramified structure is discussed with reference to some theoretical considerations and comparison with simulations.

Supersaturation-Limited and Unlimited Phase Spaces Compete to Produce Maximal Amyloid Fibrillation near the Critical Micelle Concentration of Sodium Dodecyl Sulfate.

PubMed

So, Masatomo; Ishii, Akira; Hata, Yasuko; Yagi, Hisashi; Naiki, Hironobu; Goto, Yuji

2015-09-15

Although various natural and synthetic compounds have been shown to accelerate or inhibit the formation of amyloid fibrils, the mechanisms by which they achieve these adverse effects in a concentration-dependent manner currently remain unclear. Sodium dodecyl sulfate (SDS), one of the compounds that has adverse effects on fibrillation, is the most intensively studied. Here we examined the effects of a series of detergents including SDS on the amyloid fibrillation of β2-microglobulin at pH 7.0, a protein responsible for dialysis-related amyloidosis. In all the detergents examined (i.e., SDS, sodium decyl sulfate, sodium octyl sulfate, and sodium deoxycholate), amyloid fibrillation was accelerated and inhibited at concentrations near the critical micelle concentration (CMC) and higher than CMC, respectively. The most stable conformation changed from monomers with a β-structure to amyloid fibrils with a β-structure and then to α-helical complexes with micelles with an increase in detergent concentrations. These results suggest that competition between supersaturation-limited fibrillation and unlimited mixed micelle formation between proteins and micelles underlies the detergent concentration-dependent complexity of amyloid fibrillation.

Panel Flutter Emulation Using a Few Concentrated Forces

NASA Astrophysics Data System (ADS)

Dhital, Kailash; Han, Jae-Hung

2018-04-01

The objective of this paper is to study the feasibility of panel flutter emulation using a few concentrated forces. The concentrated forces are considered to be equivalent to aerodynamic forces. The equivalence is carried out using surface spline method and principle of virtual work. The structural modeling of the plate is based on the classical plate theory and the aerodynamic modeling is based on the piston theory. The present approach differs from the linear panel flutter analysis in scheming the modal aerodynamics forces with unchanged structural properties. The solutions for the flutter problem are obtained numerically using the standard eigenvalue procedure. A few concentrated forces were considered with an optimization effort to decide their optimal locations. The optimization process is based on minimizing the error between the flutter bounds from emulated and linear flutter analysis method. The emulated flutter results for the square plate of four different boundary conditions using six concentrated forces are obtained with minimal error to the reference value. The results demonstrated the workability and viability of using concentrated forces in emulating real panel flutter. In addition, the paper includes the parametric studies of linear panel flutter whose proper literatures are not available.

Evaluation of Maximum Radionuclide Groundwater Concentrations for Basement Fill Model. Zion Station Restoration Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sullivan, T.

2016-05-20

ZionSolutions is in the process of decommissioning the Zion Nuclear Power Station (ZNPS). After decommissioning is completed, the site will contain two reactor Containment Buildings, the Fuel Handling Building and Transfer Canals, Auxiliary Building, Turbine Building, Crib House/Forebay, and a Waste Water Treatment Facility that have been demolished to a depth of 3 feet below grade. Additional below ground structures remaining will include the Main Steam Tunnels and large diameter intake and discharge pipes. These additional structures are not included in the modeling described in this report, but the inventory remaining (expected to be very low) will be included withmore » one of the structures that are modeled as designated in the Zion Station Restoration Project (ZSRP) License Termination Plan (LTP). The remaining underground structures will be backfilled with clean material. The final selection of fill material has not been made.« less

Heavy Oil Detection (Prototypes)

DTIC Science & Technology

2009-06-01

accomplish a variety of tasks to be successful. These include detecting the oil, possibly concentrating/ corralling the oil for collection, and...structures (e.g., reefs , cables, and pipelines). Other non-contact seafloor survey techniques such as ROV video surveys pose the additional

Selected water-quality and biological characteristics of streams in some forested basins of North Carolina, 1985-88

USGS Publications Warehouse

Caldwell, W.S.

1992-01-01

Selected physical, chemical and biological components of streams draining undeveloped, forested basins in North Carolina were characterized on the basis of samples collected at nine sites on streams in basins that ranged in size from 0.67 to 11.2 sq mi. Water analysis included specific conductance, dissolved oxygen, water temperature, suspended sediment, pH, major dissolved constituents, nutrients, minor constituents, organochlorine insecticides, and biochemical oxygen demand. Biological characteristics included fish tissue analysis for minor constituents and synthetic organic compounds, fish community structure, and benthic macroinvertebrates. Precipitation is the source of 10 to 40% of the chloride concentration and 20 to 30% of the sulfate concentration in stormflow. Mean total nitrogen concentrations ranged from 0.16 mg/L during low-flow conditions to 1.2 mg/L during stormflow. Organic nitrogen was 60 to 85% of the total nitrogen concentration. Stream water was free of organochlorine insecticides. DDD, DDE, DDT, Lindane, and Mirex were detected in 18 of 60 samples of streambed material. About 35% of fish tissue analyses showed detectable concentrations of copper, lead, mercury and nickel. Synthetic organic chemicals were not detected in fish tissue. Fish community structure data were rated using Karr's Index of Biotic Integrity. Streams rated poor to good because of natural stresses on fish communities. Five streams in the Piedmont and mountains received excellent bioclassification ratings based on benthic macroinvertebrtate data. Two streams in the Coastal Plain rated good to fair because of natural stresses.

Spatial analysis of trace elements in a moss bio-monitoring data over France by accounting for source, protocol and environmental parameters.

PubMed

Lequy, Emeline; Saby, Nicolas P A; Ilyin, Ilia; Bourin, Aude; Sauvage, Stéphane; Leblond, Sébastien

2017-07-15

Air pollution in trace elements (TE) remains a concern for public health in Europe. For this reasons, networks of air pollution concentrations or exposure are deployed, including a moss bio-monitoring programme in Europe. Spatial determinants of TE concentrations in mosses remain unclear. In this study, the French dataset of TE in mosses is analyzed by spatial autoregressive model to account for spatial structure of the data and several variables proven or suspected to affect TE concentrations in mosses. Such variables include source (atmospheric deposition and soil concentrations), protocol (sampling month, collector, and moss species), and environment (forest type and canopy density, distance to the coast or the highway, and elevation). Modeled atmospheric deposition was only available for Cd and Pb and was one of the main explanatory variables of the concentrations in mosses. Predicted soil content was also an important explanatory variable except for Cr, Ni, and Zn. However, the moss species was the main factor for all the studied TE. The other environmental variables affected differently the TE. In particular, the forest type and canopy density were important in most cases. These results stress the need for further research on the effect of the moss species on the capture and retention of TE, as well as for accounting for several variables and the spatial structure of the data in statistical analyses. Copyright © 2017 Elsevier B.V. All rights reserved.

Modelling of flow processes of the structured two-phase disperse systems (solid phase-liquid medium).

PubMed

Uriev, N B; Kuchin, I V

2007-10-31

A review of the basic theories and models of shear flow of suspensions is presented and the results of modeling of structured suspensions under flow conditions. The physical backgrounds and conditions of macroscopic discontinuity in the behaviour of high-concentrated systems are analyzed. The use of surfactants and imposed vibration for regulation of rheological properties of suspensions are considered. A review of the recent approaches and methods of computer simulation of concentrated suspensions is undertaken and results of computer simulation of suspensions are presented. Formation and destruction of the structure of suspension under static and dynamic conditions (including imposed combined shear and orthogonal oscillations) are discussed. The influence of interaction of particles as well as of some parameters characterizing a type and intensity of external perturbations on suspensions behavior is demonstrated.

Structural changes induced by high-pressure processing in micellar casein and milk protein concentrates.

PubMed

Cadesky, Lee; Walkling-Ribeiro, Markus; Kriner, Kyle T; Karwe, Mukund V; Moraru, Carmen I

2017-09-01

Reconstituted micellar casein concentrates and milk protein concentrates of 2.5 and 10% (wt/vol) protein concentration were subjected to high-pressure processing at pressures from 150 to 450 MPa, for 15 min, at ambient temperature. The structural changes induced in milk proteins by high-pressure processing were investigated using a range of physical, physicochemical, and chemical methods, including dynamic light scattering, rheology, mid-infrared spectroscopy, scanning electron microscopy, proteomics, and soluble mineral analyses. The experimental data clearly indicate pressure-induced changes of casein micelles, as well as denaturation of serum proteins. Calcium-binding α S1 - and α S2 -casein levels increased in the soluble phase after all pressure treatments. Pressurization up to 350 MPa also increased levels of soluble calcium and phosphorus, in all samples and concentrations, whereas treatment at 450 MPa reduced the levels of soluble Ca and P. Experimental data suggest dissociation of calcium phosphate and subsequent casein micelle destabilization as a result of pressure treatment. Treatment of 10% micellar casein concentrate and 10% milk protein concentrate samples at 450 MPa resulted in weak, physical gels, which featured aggregates of uniformly distributed, casein substructures of 15 to 20 nm in diameter. Serum proteins were significantly denatured by pressures above 250 MPa. These results provide information on pressure-induced changes in high-concentration protein systems, and may inform the development on new milk protein-based foods with novel textures and potentially high nutritional quality, of particular interest being the soft gel structures formed at high pressure levels. The Authors. Published by the Federation of Animal Science Societies and Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

Therapeutic Antibody Engineering To Improve Viscosity and Phase Separation Guided by Crystal Structure.

PubMed

Chow, Chi-Kin; Allan, Barrett W; Chai, Qing; Atwell, Shane; Lu, Jirong

2016-03-07

Antibodies at high concentrations often reveal unanticipated biophysical properties suboptimal for therapeutic development. The purpose of this work was to explore the use of point mutations based on crystal structure information to improve antibody physical properties such as viscosity and phase separation (LLPS) at high concentrations. An IgG4 monoclonal antibody (Mab4) that exhibited high viscosity and phase separation at high concentration was used as a model system. Guided by the crystal structure, four CDR point mutants were made to evaluate the role of hydrophobic and charge interactions on solution behavior. Surprisingly and unpredictably, two of the charge mutants, R33G and N35E, showed a reduction in viscosity and a lower propensity to form LLPS at high concentration compared to the wild-type (WT), while a third charge mutant S28K showed an increased propensity to form LLPS compared to the WT. A fourth mutant, F102H, had reduced hydrophobicity, but unchanged viscosity and phase separation behavior. We further evaluated the correlation of various biophysical measurements including second virial coefficient (A2), interaction parameter (kD), weight-average molecular weight (WAMW), and hydrodynamic diameters (DH), at relatively low protein concentration (4 to 15 mg/mL) to physical properties, such as viscosity and liquid-liquid phase separation (LLPS), at high concentration. Surprisingly, kD measured using dynamic light scattering (DLS) at low antibody concentration correlated better with viscosity and phase separation than did A2 for Mab4. Our results suggest that the high viscosity and phase separation observed at high concentration for Mab4 are mainly driven by charge and not hydrophobicity.

A study of building structural features associated with high indoor air concentrations of organochlorine termiticides.

PubMed

Pisaniello, D L; Gun, R T; Tkaczuk, M N; Hann, C; Crea, J

1993-09-01

As part of a two-year study of post-treatment residential exposure to the termiticide, aldrin, the building structural features of ten houses with crawl-space-type floors were assessed by an independent inspector. Building attributes recorded on a checklist included the age of the dwelling, room characteristics, floor details and the nature of subfloor ventilation. At the end of each inspection, the inspector, who was blinded to data on airborne aldrin concentrations, provided a rating of expected indoor air contamination. Several of the building attributes, including the age of the house, the area of exterior subfloor vents, as well as the inspector's rating, were significantly correlated with airborne aldrin values. No single building variable, however, was highly correlated with every measure of aldrin concentration over a 12-month period. The observed data are consistent with poor subfloor ventilation and a 'leaky' floor being important contributors to indoor air pollution. It is recommended that pest control companies advise householders about any obvious floor and ventilation deficiencies before soil treatment work is undertaken. Pesticide exposure (by analogy with geological radon exposure) may be reduced by sealing gaps in floors and/or by improving subfloor ventilation.

The impact of adding organic carbon on the concentrations of total residual oxidants and disinfection by-products in approval tests for ballast water management systems.

PubMed

Lee, Jihyun; Shon, Myung-Baek; Cha, Hyung-Gon; Choi, Keun-Hyung

2017-12-15

In the G8 and G9 approval tests for ballast water management systems, organic carbon additives are frequently supplemented into test water to satisfy the water quality requirements. Because organic additives can affect the approval test, the additive selected, and its use and validation should be included in the test report. This study assessed the effects of organic carbon additives on the concentration of total residual oxidants (TROs) and the formation of disinfection by-products (DBPs). The concentration of dissolved organic carbon (DOC) in test water containing additives varied depending on the type of additive, but all additives, except for methylcellulose, had concentrations similar to or higher than the theoretical values. There was a low concentration of particulate organic carbon (POC) compared to the amount of corn starch added. Over the course of the five-day holding time, TRO concentrations tended to decrease. In general, substances with a large molecular size had a higher DBP concentration than their counterparts with a smaller molecular size, some of which, however produced the highest DBP concentrations due to their molecular structure. The results suggest that the formation of DBPs is affected by the reaction with TROs, molecular size, and molecular structure in a complex manner. Copyright © 2017 Elsevier B.V. All rights reserved.

Morphology and characterization of 3D micro-porous structured chitosan scaffolds for tissue engineering.

PubMed

Hsieh, Wen-Chuan; Chang, Chih-Pong; Lin, Shang-Ming

2007-06-15

This research studies the morphology and characterization of three-dimensional (3D) micro-porous structures produced from biodegradable chitosan for use as scaffolds for cells culture. The chitosan 3D micro-porous structures were produced by a simple liquid hardening method, which includes the processes of foaming by mechanical stirring without any chemical foaming agent added, and hardening by NaOH cross linking. The pore size and porosity were controlled with mechanical stirring strength. This study includes the morphology of chitosan scaffolds, the characterization of mechanical properties, water absorption properties and in vitro enzymatic degradation of the 3D micro-porous structures. The results show that chitosan 3D micro-porous structures were successfully produced. Better formation samples were obtained when chitosan concentration is at 1-3%, and concentration of NaOH is at 5%. Faster stirring rate would produce samples of smaller pore diameter, but when rotation speed reaches 4000 rpm and higher the changes in pore size is minimal. Water absorption would reduce along with the decrease of chitosan scaffolds' pore diameter. From stress-strain analysis, chitosan scaffolds' mechanical properties are improved when it has smaller pore diameter. From in vitro enzymatic degradation results, it shows that the disintegration rate of chitosan scaffolds would increase along with the processing time increase, but approaching equilibrium when the disintegration rate reaches about 20%.

Design and economics of a photovoltaic concentrator array for off-grid applications

NASA Astrophysics Data System (ADS)

Maish, A. B.; Rios, M., Jr.

1982-09-01

The array design and expected operation of a photovoltaic concentrator are discussed. A second generation stand alone 680 W/sub p/ photovoltaic (PV) concentrating array for low power, nongrid connected applications was designed. The array consists of six passive cooled point focus Fresnel lens concentrating modules on a two axis polar mount tracking structure. The new array design incorporates several major improvements to the first generation design. These include 50% more array area and a control system which allows unattended, fully automatic operation. The life cycle energy costs are calculated and compared to the equivalent energy costs of a 3 kW diesel electric generator set and an equivalent flat panel PV system.

Cryopreservation of Proteins Using Ionic Liquids: A Case Study of Cytochrome c.

PubMed

Takekiyo, Takahiro; Ishikawa, Yuka; Yoshimura, Yukihiro

2017-08-17

Aqueous ionic liquid (IL) solutions form a glassy state at 77 K over a wide concentration of ILs. They have potential as novel cryopreservation/refolding solvents for proteins. However, even if proteins in glass-forming concentrations of ILs are preserved at 77 K, the recovery of activity and the structure of the proteins after cryopreservation are still unclear. To achieve high recovery of protein activity and structure by removal of ILs after cryopreservation at 77 K, we studied the recovery of activity and structural stability after cryopreservation of bovine heart cytochrome c in aqueous solutions with ILs, including ethylammonium nitrate (EAN) and 1-butyl-3-methylimidazolium thiocyanate ([bmim][SCN]) over wide IL concentrations using UV-vis, Fourier transform infrared (FTIR), and circular dichroism (CD) spectroscopy. On the whole, although the addition of both ILs induced a decrease of activity and unfolding of the secondary structure of cytochrome c before and after cooling to 77 K, EAN, a weak denaturant, showed a reduction in protein damage (decrease of activity and unfolding of secondary structure) during the reheating process from 77 K (protection ability). In contrast, [bmim][SCN], a strong denaturant, did not have this protective ability. A remarkable result is that although the addition of both ILs caused cytochrome c denaturation, > 90% of activity and structure after cryopreservation (X > 10 mol %IL) was recovered after the removal of both ILs by dialysis. These recoveries after the removal of ILs are slightly higher than the results for dimethyl disulfide (DMSO), another cryoprotectant. The present results indicate that concentrated aqueous IL solutions have potential as one-pot (i.e., solubilization/preservation/refolding) solvents for proteins, which easily aggregate after purification, with comparable results to DMSO.

Aspartame and Its Analogues

NASA Astrophysics Data System (ADS)

Pavlova, L. A.; Komarova, T. V.; Davidovich, Yurii A.; Rogozhin, S. V.

1981-04-01

The results of studies on the biochemistry of the sweet taste are briefly reviewed. The methods of synthesis of "aspartame" — a sweet dipeptide — are considered, its structural analogues are described, and quantitative estimates are made of the degree of sweetness relative to sucrose. Attention is concentrated mainly on problems of the relation between the structure of the substance and its taste in the series of aspartyl derivatives. The bibliography includes 118 references.

Effect of Thermal and Shear Stressors on the Physical Properties, Structural Integrity and Biological Activity of the Anti-TNF-alpha Monoclonal Antibody, Infliximab.

PubMed

Alsaddique, Jihad A; Pabari, Ritesh M; Ramtoola, Zebunnissa

The influence of thermal and shear stressors on the stability of the anti-TNF-α monoclonal antibody (mAb), Infliximab® (INF) was investigated. INF at concentrations of 1, 4 and 10 mg/ml was subjected to thermal stress at temperatures of 25-65°C and to shear force by sonication for 1 and 3 minutes. The stressed samples were analysed for physical properties by particle size, zeta potential, for structural integrity by gel electrophoresis (SDS-PAGE) and circular dichroism, INF content by UV spectroscopy and for biological activity by ELISA. Results show no change in physical properties or structural integrity of INF at any concentration tested, when subjected to a temperature of up to 50°C. At 65°C, aggregation and precipitation of INF was observed. When subjected to shear stress, higher concentrations of INF at 4 and 10mg/ml maintained their physical properties and structural integrity. However, the biological activity of INF was found to decrease with increasing temperature and sonication time, and was concentration dependent (ANOVA; p<0.05). Interestingly, lyophilisation of INF at 1mg/ml did not affect its physical properties, structural integrity or its biological activity. These findings have important implications with respect to pharmaceutical processing of INF and mAbs including formulation as polymeric micro and nanoparticle systems for sustained or targeted delivery. These findings also have important implications with respect to the handling and storage of INF and mAbs for clinical use.

[Cognitive Function and Calcium. Structures and functions of Ca2+-permeable channels].

PubMed

Kaneko, Shuji

2015-02-01

Calcium is essential for living organisms where the increase in intracellular Ca2+ concentration functions as a second messenger for many cellular processes including synaptic transmission and neural plasticity. The cytosolic concentration of Ca2+ is finely controlled by many Ca2+-permeable ion channels and transporters. The comprehensive view of their expression, function, and regulation will advance our understanding of neural and cognitive functions of Ca2+, which leads to the future drug discovery.

Short-time dynamics of lysozyme solutions with competing short-range attraction and long-range repulsion: Experiment and theory

NASA Astrophysics Data System (ADS)

Riest, Jonas; Nägele, Gerhard; Liu, Yun; Wagner, Norman J.; Godfrin, P. Douglas

2018-02-01

Recently, atypical static features of microstructural ordering in low-salinity lysozyme protein solutions have been extensively explored experimentally and explained theoretically based on a short-range attractive plus long-range repulsive (SALR) interaction potential. However, the protein dynamics and the relationship to the atypical SALR structure remain to be demonstrated. Here, the applicability of semi-analytic theoretical methods predicting diffusion properties and viscosity in isotropic particle suspensions to low-salinity lysozyme protein solutions is tested. Using the interaction potential parameters previously obtained from static structure factor measurements, our results of Monte Carlo simulations representing seven experimental lysoyzme samples indicate that they exist either in dispersed fluid or random percolated states. The self-consistent Zerah-Hansen scheme is used to describe the static structure factor, S(q), which is the input to our calculation schemes for the short-time hydrodynamic function, H(q), and the zero-frequency viscosity η. The schemes account for hydrodynamic interactions included on an approximate level. Theoretical predictions for H(q) as a function of the wavenumber q quantitatively agree with experimental results at small protein concentrations obtained using neutron spin echo measurements. At higher concentrations, qualitative agreement is preserved although the calculated hydrodynamic functions are overestimated. We attribute the differences for higher concentrations and lower temperatures to translational-rotational diffusion coupling induced by the shape and interaction anisotropy of particles and clusters, patchiness of the lysozyme particle surfaces, and the intra-cluster dynamics, features not included in our simple globular particle model. The theoretical results for the solution viscosity, η, are in qualitative agreement with our experimental data even at higher concentrations. We demonstrate that semi-quantitative predictions of diffusion properties and viscosity of solutions of globular proteins are possible given only the equilibrium structure factor of proteins. Furthermore, we explore the effects of changing the attraction strength on H(q) and η.

The impact of lignin source on its self-assembly in solution

DOE PAGES

Ratnaweera, Dilru R.; Saha, Dipendu; Pingali, Sai Venkatesh; ...

2015-07-30

Recently, there has been a growing interest in developing value added uses for lignin, including the utilization of lignins as a precursor for carbon materials. Proper understanding of the association behavior of lignins during solution processing provides important structural information that is needed to rationally optimize the use of lignins in industry in a range of value added applications. In this paper, we follow the assembly of lignin molecules from a variety of sources in dimethyl sulfoxide, a good solvent for lignins, using small angle neutron scattering. In order to mimic industrial processing conditions, concentrations of lignins were kept abovemore » the overlap concentration. At small length scales, short lignin segments with ~4–10 monolignol units associate to form rigid rod-like/cylindrical building blocks, where the number of repeat units in a cylindrical segment decreases with increasing lignin concentration. These cylindrical building blocks associate to form aggregates with low cross-linking densities and a random coil or network like structures from highly branched lignin structures. The degree of branching of the base lignin molecule, which varies with source, plays a crucial role in determining their association behavior. Finally, the overall sizes of the aggregates decrease with increasing concentration at low cross-linking densities, whereas the opposite trend is observed for highly branched lignins.« less

Conceptual design studies for large free-flying solar-reflector spacecraft

NASA Technical Reports Server (NTRS)

Hedgepeth, J. M.; Miller, R. K.; Knapp, K. P. W.

1981-01-01

The 1 km diameter reflecting film surface is supported by a lightweight structure which may be automatically deployed after launch in the Space Shuttle. A twin rotor, control moment gyroscope, with deployable rotors, is included as a primary control actuator. The vehicle has a total specific mass of less than 12 g/sq m including allowances for all required subsystems. The structural elements were sized to accommodate the loads of a typical SOLARES type mission where a swam of these free flying satellites is employed to concentrate sunlight on a number of energy conversion stations on the ground.

Preliminary structural design of a lunar transfer vehicle aerobrake. M.S. Thesis

NASA Technical Reports Server (NTRS)

Bush, Lance B.

1992-01-01

An aerobrake concept for a Lunar transfer vehicle was weight optimized through the use of the Taguchi design method, structural finite element analyses and structural sizing routines. Six design parameters were chosen to represent the aerobrake structural configuration. The design parameters included honeycomb core thickness, diameter to depth ratio, shape, material, number of concentric ring frames, and number of radial frames. Each parameter was assigned three levels. The minimum weight aerobrake configuration resulting from the study was approx. half the weight of the average of all twenty seven experimental configurations. The parameters having the most significant impact on the aerobrake structural weight were identified.

Mercury bioaccumulation assessment for the St. Louis River Area of Concern (poster)

EPA Science Inventory

Elevated mercury concentrations have been documented in fish and invertebrates within the St. Louis River Area of Concern (AOC). Mercury bioavailability is affected by multiple factors, including mercury sources, sediment and water geochemistry, food web structure, individual fis...

Sediment Contaminants and Infauna Associated with Recreational Boating Structures in a Multi-Use Marine Park.

PubMed

Sim, Vivian X Y; Dafforn, Katherine A; Simpson, Stuart L; Kelaher, Brendan P; Johnston, Emma L

2015-01-01

Multi-use marine parks achieve conservation through spatial management of activities. Zoning of marine parks in New South Wales, Australia, includes high conservation areas and special purpose zones (SPZ) where maritime activities are concentrated. Although such measures geographically constrain anthropogenic impacts, we have limited understanding of potential ecological effects. We assessed sediment communities and contaminants adjacent to boating infrastructure (boat ramps, jetties and a marina) in a SPZ from the Clyde Estuary in Batemans Marine Park. Metal concentrations and fines content were elevated at boating structures compared to reference sites. Species richness was higher at sites with boating structures, where capitellid polychaetes and nematodes dominated the communities. Changes associated with boating structures were localised and did not extend beyond breakwalls or to reference sites outside the SPZ. The study highlights the benefits of appropriate zoning in a multi-use marine park and the potential to minimise stress on pristine areas through the application of spatial management.

A graphically oriented specification language for automatic code generation. GRASP/Ada: A Graphical Representation of Algorithms, Structure, and Processes for Ada, phase 1

NASA Technical Reports Server (NTRS)

Cross, James H., II; Morrison, Kelly I.; May, Charles H., Jr.; Waddel, Kathryn C.

1989-01-01

The first phase of a three-phase effort to develop a new graphically oriented specification language which will facilitate the reverse engineering of Ada source code into graphical representations (GRs) as well as the automatic generation of Ada source code is described. A simplified view of the three phases of Graphical Representations for Algorithms, Structure, and Processes for Ada (GRASP/Ada) with respect to three basic classes of GRs is presented. Phase 1 concentrated on the derivation of an algorithmic diagram, the control structure diagram (CSD) (CRO88a) from Ada source code or Ada PDL. Phase 2 includes the generation of architectural and system level diagrams such as structure charts and data flow diagrams and should result in a requirements specification for a graphically oriented language able to support automatic code generation. Phase 3 will concentrate on the development of a prototype to demonstrate the feasibility of this new specification language.

Sediment Contaminants and Infauna Associated with Recreational Boating Structures in a Multi-Use Marine Park

PubMed Central

Sim, Vivian X. Y.; Dafforn, Katherine A.; Simpson, Stuart L.; Kelaher, Brendan P.; Johnston, Emma L.

2015-01-01

Multi-use marine parks achieve conservation through spatial management of activities. Zoning of marine parks in New South Wales, Australia, includes high conservation areas and special purpose zones (SPZ) where maritime activities are concentrated. Although such measures geographically constrain anthropogenic impacts, we have limited understanding of potential ecological effects. We assessed sediment communities and contaminants adjacent to boating infrastructure (boat ramps, jetties and a marina) in a SPZ from the Clyde Estuary in Batemans Marine Park. Metal concentrations and fines content were elevated at boating structures compared to reference sites. Species richness was higher at sites with boating structures, where capitellid polychaetes and nematodes dominated the communities. Changes associated with boating structures were localised and did not extend beyond breakwalls or to reference sites outside the SPZ. The study highlights the benefits of appropriate zoning in a multi-use marine park and the potential to minimise stress on pristine areas through the application of spatial management. PMID:26086427

The effect of boron concentration on the structure and elastic properties of Ru-Ir alloys: first-principles calculations

NASA Astrophysics Data System (ADS)

Li, Xiaolong; Zhou, Zhaobo; Hu, Riming; Zhou, Xiaolong; Yu, Jie; Liu, Manmen

2018-04-01

The Phase stability, electronic structure, elastic properties and hardness of Ru-Ir alloys with different B concentration were investigated by first principles calculations. The calculated formation enthaplies and cohesive energies show that these compounds are all thermodynamically stable. Information on electronic structure indicates that they possess metallic characteristic and Ru-Ir-B alloys were composed of the Ru-B and Ir-B covalent bond. The elastic properties were calculated, which included bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio and hardness. The calculated results reveal that the plastic of Ru-Ir-B alloys increase with the increase of the content of B atoms, but the hardness of Ru-Ir-B alloys have no substantial progress with the increase of the content of B atoms. However, it is interesting that the hardness of the Ru-Ir-B compound was improved obviously as the B content was higher than 18 atoms because of a phase structure transition.

Interspecific variation in mitochondrial serine transfer RNA (UCN) in Euptychiina butterflies (Lepidoptera: Satyrinae): structure and alignment.

PubMed

Marín, Mario Alejandro; López, Andrés; Uribe, Sandra Inés

2012-06-01

The nucleotide variation and structural patterns of mitochondrial RNA molecule have been proposed as useful tools in molecular systematics; however, their usefulness is always subject to a proper assessment of homology in the sequence alignment. The present study describes the secondary structure of mitochondrial tRNA for the amino acid serine (UCN) on 13 Euptychiina species and the evaluation of its potential use for evolutionary studies in this group of butterflies. The secondary structure of tRNAs showed variation among the included species except between Hermeuptychia sp1 and sp2. Variation was concentrated in the ribotimidina-pseudouridine-cystosine (TψC), dihydrouridine (DHU) and variable loops and in the DHU and TψC arms. These results suggest this region as a potential marker useful for taxonomic differentiation of species in this group and also confirm the importance of including information from the secondary structure of tRNA to optimize the alignments.

Two-stage preconcentrator for vapor/particle detection

DOEpatents

Linker, Kevin L.; Brusseau, Charles A.

2002-01-01

A device for concentrating particles from a high volume gas stream and delivering the particles for detection in a low volume gas stream includes first and second preconcentrators. The first preconcentrator has a first structure for retaining particles in a first gas flow path through which a first gas flows at a relatively high volume, valves for selectively stopping the first gas flow; and a second gas flow path through which gas flows at an intermediate flow volume for moving particles from the first structure. The second preconcentrator includes a second structure for retaining particles in the second gas flow path; a valve for selectively stopping the second gas flow; and a third gas flow path through which gas flows at a low volume for moving particles from the second structure to a detector. Each of the particle retaining structures is preferably a metal screen that may be resistively heated by application of an electric potential to release the particles.

Neighborhood and school ethnic structuring and cultural adaptations among Mexican-origin adolescents.

PubMed

White, Rebecca M B; Updegraff, Kimberly A; Umaña-Taylor, Adriana J; Zeiders, Katharine H; Perez-Brena, Norma; Burleson, Elizabeth

2017-03-01

The ethnic and racial structuring of U.S. neighborhoods may have important implications for developmental competencies during adolescence, including the development of heritage and mainstream cultural orientations. In particular, living in highly concentrated Latino neighborhoods during early adolescence-which channels adolescents into related school environments-may promote retention of the ethnic or heritage culture, but it also may constrain adaptation to the mainstream U.S. culture. We tested these hypotheses longitudinally in a sample of 246 Mexican origin adolescents (50.8% girls) and their parents. Data were collected 4 times over 8 years, with adolescents averaging 12.5 (SD = .58) to 19.6 (SD = .66) years of age across the period of the study. Latino ethnic concentration in early adolescents' neighborhoods promoted the retention of Mexican cultural orientations; Latino ethnic concentration in middle schools undermined the development of mainstream U.S cultural orientations. Findings are discussed in terms of integrating cultural-developmental theory with mainstream neighborhood theory to improve understandings of neighborhood and school ethnic concentration effects on adolescent development. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Neighborhood and School Ethnic Structuring and Cultural Adaptations Among Mexican-Origin Adolescents

PubMed Central

White, Rebecca M. B.; Updegraff, Kimberly A.; Umaña-Taylor, Adriana J.; Zeiders, Katharine H.; Perez-Brena, Norma; Burleson, Elizabeth

2016-01-01

The ethnic and racial structuring of U.S. neighborhoods may have important implications for developmental competencies during adolescence, including the development of heritage and mainstream cultural orientations. In particular, living in highly concentrated Latino neighborhoods during early adolescence – which channels adolescents into related school environments – may promote retention of the ethnic or heritage culture, but it also may constrain adaptation to the mainstream U.S. culture. We tested these hypotheses longitudinally in a sample of 246 Mexican origin adolescents (50.8% girls) and their parents. Data were collected four times over eight years, with adolescents averaging 12.5 (SD = .58) to 19.6 (SD = .66) years of age across the period of the study. Latino ethnic concentration in early adolescents' neighborhoods promoted the retention of Mexican cultural orientations; Latino ethnic concentration in middle schools undermined the development of mainstream U.S cultural orientations. Findings are discussed in terms of integrating cultural-developmental theory with mainstream neighborhood theory to improve understandings of neighborhood and school ethnic concentration effects on adolescent development. PMID:27936822

In vitro trypanocidal activities of new S-adenosylmethionine decarboxylase inhibitors.

PubMed Central

Brun, R; Bühler, Y; Sandmeier, U; Kaminsky, R; Bacchi, C J; Rattendi, D; Lane, S; Croft, S L; Snowdon, D; Yardley, V; Caravatti, G; Frei, J; Stanek, J; Mett, H

1996-01-01

A series of novel aromatic derivatives based on the structure of methylglyoxal bis(guanylhydrazone) (MGBG) was examined for in vitro antitrypanosomal activities and cytotoxicities for human cells. One-third of the compounds tested showed trypanocidal activity at concentrations below 0.5 microM after an incubation period of 72 h. Structure-activity analysis revealed that bicyclic compounds with homocyclic rings and unmodified termini were the most active compounds. Results obtained in three laboratories employing different methods and trypanosome populations consistently ranked compound CGP 40215A highest. This compound had a 50% inhibitory concentration of 0.0045 microM for Trypanosoma brucei rhodesiense, was also active against other trypanosome species, including a multidrug-resistant Trypanosoma brucei brucei, and was significantly less toxic than other compounds tested for a human adenocarcinoma cell line, with a 50% inhibitory concentration of 1.14 mM. The effect of CGP 40215A was time and dose dependent, and low concentrations of the compound required exposure times of > 2 days to exert trypanocidal activity. Compounds were inactive against Leishmania donovani and Trypanosoma cruzi amastigotes in murine macrophages in vitro. PMID:8726017

TRPC Channel Structure and Properties.

PubMed

Feng, Shengjie

2017-01-01

TRPC channels are the first identified members in the TRP family. They function as either homo- or heterotetramers regulating intracellular Ca 2+ concentration in response to numerous physiological or pathological stimuli. TRPC channels are nonselective cation channels permeable to Ca 2+ . The properties and the functional domains of TRPC channels have been identified by electrophysiological and biochemical methods. However, due to the large size, instability, and flexibility of their complexes, the structures of the members in TRPC family remain unrevealed. More efforts should be made on structure analysis and generating good tools, including specific antibodies, agonist, and antagonist.

The Hazard of an Explosion of the ARIANE 5 Launcher- The Risks for the Astronauts Sitting on the Ejector Seats

DTIC Science & Technology

1990-08-30

velocities (a first approach). In a first step, we <<construct>> the launcher. A launcher is composed of structures (propellant reservoirs for example... structures and the unburnt propellant included in the cone C, are all part of the fragments’ <<environment>> (Fig. 3). Its D mass W,is concentrated on the...dynamic fluid- structure interactions*. Computer Methods in Applied Mechanics And Engineering 33 (1982) 689-723. 1151 M. ECK, M.MUKUNDA : <<Predicting

Probing the cross-effect of strains in non-linear elasticity of nearly regular polymer networks by pure shear deformation.

PubMed

Katashima, Takuya; Urayama, Kenji; Chung, Ung-il; Sakai, Takamasa

2015-05-07

The pure shear deformation of the Tetra-polyethylene glycol gels reveals the presence of an explicit cross-effect of strains in the strain energy density function even for the polymer networks with nearly regular structure including no appreciable amount of structural defect such as trapped entanglement. This result is in contrast to the expectation of the classical Gaussian network model (Neo Hookean model), i.e., the vanishing of the cross effect in regular networks with no trapped entanglement. The results show that (1) the cross effect of strains is not dependent on the network-strand length; (2) the cross effect is not affected by the presence of non-network strands; (3) the cross effect is proportional to the network polymer concentration including both elastically effective and ineffective strands; (4) no cross effect is expected exclusively in zero limit of network concentration in real polymer networks. These features indicate that the real polymer networks with regular network structures have an explicit cross-effect of strains, which originates from some interaction between network strands (other than entanglement effect) such as nematic interaction, topological interaction, and excluded volume interaction.

Mixing efficiency inside micro-droplets coalesced by two components in cross-structure

NASA Astrophysics Data System (ADS)

Ren, Yanlin; Liu, Zhaomiao; Pang, Yan

2017-11-01

The mixing of micro-droplets is used in analytical chemistry, medicine production and material synthesis owing to its advantages including the encapsulation and narrow time residence distribution. In this work, droplets are coalesced by two dispersed phase with different flow rates, generated in cross-structure and mixed in planar serpentine structure. The mixing efficiency of micro-droplets under control characters including the width of entrance and the flow rate of dispersed phases have been investigated by experiments and numerical simulations. The UDS (user-defined scalar) as dimensionless concentration of the solution is adopted in simulation, and is used to calculate the concentration and the mixing effect. By changing the flow rates and the entrances` width, the changing rules of the mixing characters have been obtained. The asymmetry distributions of components make rapid mixing process in half part of each droplet when travel through a straight channel. Increasing of the ratio of entrance width result into larger droplet and weaken the chaotic mixing effect. Meanwhile, the coalesced mechanism can be performed by ranging the ratio of flow rates, the ranges are also determined by the widths of entrances. The authors gratefully acknowledge the support of National Natural Science Foundation of China (Grant No. 11572013).

Antioxidant activity of taxifolin: an activity-structure relationship.

PubMed

Topal, Fevzi; Nar, Meryem; Gocer, Hulya; Kalin, Pınar; Kocyigit, Umit M; Gülçin, İlhami; Alwasel, Saleh H

2016-08-01

Taxifolin is a kind of flavanonol, whose biological ability. The objectives of this study were to investigate the antioxidants and antiradical activities of taxifolin by using different in vitro bioanalytical antioxidant methods including DMPD√(+), ABTS√(+), [Formula: see text], and DPPH√-scavenging effects, the total antioxidant influence, reducing capabilities, and Fe(2+)-chelating activities. Taxifolin demonstrated 81.02% inhibition of linoleic acid emulsion peroxidation at 30 µg/mL concentration. At the same concentration, standard antioxidants including trolox, α-tocopherol, BHT, and BHA exhibited inhibitions of linoleic acid emulsion as 88.57, 73.88, 94.29, and 90.12%, respectively. Also, taxifolin exhibited effective DMPD√(+), ABTS√(+), [Formula: see text], and DPPH√-scavenging effects, reducing capabilities, and Fe(2+)-chelating effects. The results obtained from this study clearly showed that taxifolin had marked antioxidant, reducing ability, radical scavenging and metal-chelating activities. Also, this study exhibits a scientific shore for the significant antioxidant activity of taxifolin and its structure-activity insight.

Modeling of Noise and Resistance of Semimetal Hg1-xCdxTe Quantum Well used as a Channel for THz Hot-Electron Bolometer.

PubMed

Melezhik, E O; Gumenjuk-Sichevska, J V; Sizov, F F

2016-12-01

Noise characteristics and resistance of semimetal-type mercury-cadmium-telluride quantum wells (QWs) at the liquid nitrogen temperature are studied numerically, and their dependence on the QW parameters and on the electron concentration is established. The QW band structure calculations are based on the full 8-band k.p Hamiltonian. The electron mobility is simulated by the direct iterative solution of the Boltzmann transport equation, which allows us to include correctly all the principal scattering mechanisms, elastic as well as inelastic.We find that the generation-recombination noise is strongly suppressed due to the very fast recombination processes in semimetal QWs. Hence, the thermal noise should be considered as a main THz sensitivity-limiting mechanism in those structures. Optimization of a semimetal Hg1-xCdxTe QW to make it an efficient THz bolometer channel should include the increase of electron concentration in the well and tuning the molar composition x close to the gapless regime.

The Influence of the Ufimian Tectonic Concentric Structure on the Hydrocarbon Migration and Ore Genesis

NASA Astrophysics Data System (ADS)

Filippov, V. A.

2018-01-01

The Ufimian tectonic concentric structure (UTC) is a regional structure with concentric and zonal structure of the internal gravity field. In the Neoproterozoic this structure was at higher hypsometric level relative to the Bashkir Meganticlinorium. The most significant uplift of this tectonic concentric structure happened at the beginning of the Karatau time ( 825 Ma) and was accompanied by the formation of a ring fractured zone, favorable for hydrocarbon migration from the Lower Riphean black shales. Due to this, bitumens with higher Mo content in the Neoproterozoic and Paleozoic deposits are confined spatially to this zone. The bitumenosity of the Neoproterozoic deposits on the southern slope of the Ufimian tectonic concentric structure could have contributed to the formation of complex Cu-Ag-Mo-Re ores (copper sands) at the upper boundary of terrigenous red deposits of the Zilmerdak Formation. Positive structures identified in the Neoproterozoic deposits near the margin of the Ufimian tectonic concentric structure are considered to be promising for searching for hydrocarbon fields.

Observations on using inside air concentrations as a predictor of outside air concentrations

DOE PAGES

Hawkley, Gavin; Whicker, Jeffrey; Harris, Jason

2015-04-01

Here, excavations of radiological material were performed within confined structures with known operational parameters, such as a filtered exhaust system with known filtration efficiency. Given the known efficiency, the assumption could be made that the air concentrations of radioactivity measured outside the structure would be proportional to the air concentrations measured inside the structure. To investigate this assumption, the inside concentration data was compared with the outside concentration data. The correlation of the data suggested that the inside concentrations were not a good predictor of the outside concentrations. This poor correlation was deemed to be a result of operational unknownsmore » within the structures.« less

Satellite power systems (SPS) concept definition study. Volume 2, part 1: System engineering

NASA Technical Reports Server (NTRS)

Hanley, G. M.

1980-01-01

Top level trade studies are presented, including comparison of solid state and klystron concepts, higher concentration on the solar cells, composite and aluminum structure, and several variations to the reference concept. Detailed trade studies are presented in each of the subsystem areas (solar array, power distribution, structures, thermal control, attitude control and stationkeeping, microwave transmission, and ground receiving station). A description of the selected point design is also presented.

Root chemistry and soil fauna, but not soil abiotic conditions explain the effects of plant diversity on root decomposition.

PubMed

Chen, Hongmei; Oram, Natalie J; Barry, Kathryn E; Mommer, Liesje; van Ruijven, Jasper; de Kroon, Hans; Ebeling, Anne; Eisenhauer, Nico; Fischer, Christine; Gleixner, Gerd; Gessler, Arthur; González Macé, Odette; Hacker, Nina; Hildebrandt, Anke; Lange, Markus; Scherer-Lorenzen, Michael; Scheu, Stefan; Oelmann, Yvonne; Wagg, Cameron; Wilcke, Wolfgang; Wirth, Christian; Weigelt, Alexandra

2017-11-01

Plant diversity influences many ecosystem functions including root decomposition. However, due to the presence of multiple pathways via which plant diversity may affect root decomposition, our mechanistic understanding of their relationships is limited. In a grassland biodiversity experiment, we simultaneously assessed the effects of three pathways-root litter quality, soil biota, and soil abiotic conditions-on the relationships between plant diversity (in terms of species richness and the presence/absence of grasses and legumes) and root decomposition using structural equation modeling. Our final structural equation model explained 70% of the variation in root mass loss. However, different measures of plant diversity included in our model operated via different pathways to alter root mass loss. Plant species richness had a negative effect on root mass loss. This was partially due to increased Oribatida abundance, but was weakened by enhanced root potassium (K) concentration in more diverse mixtures. Equally, grass presence negatively affected root mass loss. This effect of grasses was mostly mediated via increased root lignin concentration and supported via increased Oribatida abundance and decreased root K concentration. In contrast, legume presence showed a net positive effect on root mass loss via decreased root lignin concentration and increased root magnesium concentration, both of which led to enhanced root mass loss. Overall, the different measures of plant diversity had contrasting effects on root decomposition. Furthermore, we found that root chemistry and soil biota but not root morphology or soil abiotic conditions mediated these effects of plant diversity on root decomposition.

Effect of salt and surfactant concentration on the structure of polyacrylate gel/surfactant complexes.

PubMed

Nilsson, Peter; Unga, Johan; Hansson, Per

2007-09-20

Small-angle X-ray scattering was used to elucidate the structure of crosslinked polyacrylate gel/dodecyltrimethylammonium bromide complexes equilibrated in solutions of varying concentrations of surfactant and sodium bromide (NaBr). Samples were swollen with no ordering (micelle free), or they were collapsed with either several distinct peaks (cubic Pm3n) or one broad correlation peak (disordered micellar). The main factor determining the structure of the collapsed complexes was found to be the NaBr concentration, with the cubic structure existing up to approximately 150 mM NaBr and above which only the disordered micellar structure was found. Increasing the salt concentration decreases the polyion mediated attractive forces holding the micelles together causing swelling of the gel. At sufficiently high salt concentration the micelle-micelle distance in the gel becomes too large for the cubic structure to be retained, and it melts into a disordered micellar structure. As most samples were above the critical micelle concentration, the bulk of the surfactant was in the form of micelles in the solution and the surfactant concentration thereby had only a minor influence on the structure. However, in the region around 150 mM NaBr, increasing the surfactant concentration, at constant NaBr concentration, was found to change the structure from disordered micellar to ordered cubic and back to disordered again.

Glycerophospholipid Supplementation as a Potential Intervention for Supporting Cerebral Structure in Older Adults

PubMed Central

Reddan, Jeffery M.; White, David J.; Macpherson, Helen; Scholey, Andrew; Pipingas, Andrew

2018-01-01

Modifying nutritional intake through supplementation may be efficacious for altering the trajectory of cerebral structural decline evident with increasing age. To date, there have been a number of clinical trials in older adults whereby chronic supplementation with B vitamins, omega-3 fatty acids, or resveratrol, has been observed to either slow the rate of decline or repair cerebral tissue. There is also some evidence from animal studies indicating that supplementation with glycerophospholipids (GPL) may benefit cerebral structure, though these effects have not yet been investigated in adult humans. Despite this paucity of research, there are a number of factors predicting poorer cerebral structure in older humans, which GPL supplementation appears to beneficially modify or protect against. These include elevated concentrations of homocysteine, unbalanced activity of reactive oxygen species both increasing the risk of oxidative stress, increased concentrations of pro-inflammatory messengers, as well as poorer cardio- and cerebrovascular function. As such, it is hypothesized that GPL supplementation will support cerebral structure in older adults. These cerebral effects may influence cognitive function. The current review aims to provide a theoretical basis for future clinical trials investigating the effects of GPL supplementation on cerebral structural integrity in older adults. PMID:29563868

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hawkley, Gavin; Whicker, Jeffrey; Harris, Jason

Here, excavations of radiological material were performed within confined structures with known operational parameters, such as a filtered exhaust system with known filtration efficiency. Given the known efficiency, the assumption could be made that the air concentrations of radioactivity measured outside the structure would be proportional to the air concentrations measured inside the structure. To investigate this assumption, the inside concentration data was compared with the outside concentration data. The correlation of the data suggested that the inside concentrations were not a good predictor of the outside concentrations. This poor correlation was deemed to be a result of operational unknownsmore » within the structures.« less

A Data Repository and Visualization Toolbox for Metabolic Pathways and PBPK parameter prediction

EPA Science Inventory

NHANES is an extensive, well-structured collection of data about hundreds chemicals products of human metabolism and their concentration in human biomarkers, which includes parent to product mapping where known. Together, these data can be used to test the efficacy of application...

[The infectious diseases experiments conducted on human guinea pigs by Nazis in concentration camps].

PubMed

Sabbatani, Sergio

2013-06-01

The author systematically examined all available publications and web documents, with regard to scientifically documented experiments carried out by Nazi physicians in their concentration camps during World War II. This research focused on human experiments dealing with: malaria, tuberculosis, petechial typhus, viral hepatitis, and those regarding sulphonamides as antimicrobial agents. The concentration camps involved by experimental programmes on human guinea pigs were: Natzweiler Struthof, Dachau, Mauthausen, Buchenwald, Neuengamme, Ravensbrück, Sachsenhausen and Auschwitz. Overall, around 7,200 deported prisoners went to their deaths during or because of these experiments (also considering human trials other than previously quoted ones). At the end of the war several physicians were charged with war crimes in two trials (Nuremberg and Dachau), and those found guilty were sentenced to death, or years of imprisonment. Some of them, including the notorious Josef Mengele, succeeded in escaping capture and being brought to justice. Thanks to these trials, partial light has been shed on these crimes, which not infrequently had children as designated victims, selected with excruciating cruelty in special segregation sections. The SS was the key structure which ensured maximum efficiency for these experimental programmes, from both logistic planning through to an operative control system carried out in concentration camps, and thanks to an autonomous, dedicated medical structure, which included a rigid hierarchy of physicians directly dependent on the head of SS forces (Reichsführer), i.e. Dr. Heinrich Himmler. Moreover, it is worth noting that also physicians who were not part of the SS corps collaborated in the above experiments on human guinea pigs: these included military personnel belonging to the Wehrmacht, academic physicians from German universities, and researchers who worked in some German pharmaceutical industries, such as IG Farben, Bayer and Boehring.

Studying Structural, Optical, Electrical, and Sensing Properties of Nanocrystalline SnO2:Cu Films Prepared by Sol-Gel Method for CO Gas Sensor Application at Low Temperature

NASA Astrophysics Data System (ADS)

Al-Jawad, Selma M. H.; Elttayf, Abdulhussain K.; Saber, Amel S.

Nanocrystalline SnO2 and SnO2:Cu thin films derived from SnCl2ṡ2H2O precursors have been prepared on glass substrates using sol-gel dip-coating technique. The deposited film was 300±20nm thick and the films were annealed in air at 500∘C for 1h. Structural, optical and sensing properties of the films were studied under different preparation conditions, such as Cu-doping concentration of 2%, 4% and 6wt.%. X-ray diffraction studies show the polycrystalline nature with tetragonal rutile structure of SnO2 and Cu:SnO2 thin films. The films have highly preferred orientation along (110). The crystallite size of the prepared samples reduced with increasing Cu-doping concentrations and the addition of Cu as dopants changed the structural properties of the thin films. Surface morphology was determined through scanning electron microscopy and atomic force microscopy. Results show that the particle size decreased as doping concentration increased. The films have moderate optical transmission (up to 82.4% at 800nm), and the transmittance, absorption coefficient and energy gap at different Cu-doping concentration were measured and calculated. Results show that Cu-doping decreased the transmittance and energy gap whereas it increased the absorption coefficient. Two peaks were noted with Cu-doping concentration of 0-6wt.%; the first peak was positioned exactly at 320nm ultraviolet emission and the second was positioned at 430-480nm. Moreover, emission bands were noticed in the photoluminescence spectra of Cu:SnO2. The electrical properties of SnO2 films include DC electrical conductivity, showing that the films have two activation energies, namely, Ea1 and Ea2, which increase as Cu-doping concentration increases. Cudoped nanocrystalline SnO2 gas-sensing material has better sensitivity to CO gas compared with pure SnO2.

Nanotube Dispersions Made With Charged Surfactant

NASA Technical Reports Server (NTRS)

Kuper, Cynthia; Kuzma, Mike

2006-01-01

Dispersions (including monodispersions) of nanotubes in water at relatively high concentrations have been formulated as prototypes of reagents for use in making fibers, films, and membranes based on single-walled carbon nanotubes (SWNTs). Other than water, the ingredients of a dispersion of this type include one or more charged surfactant(s) and carbon nanotubes derived from the HiPco(TradeMark) (or equivalent) process. Among reagents known to be made from HiPco(TradeMark)(or equivalent) SWNTs, these are the most concentrated and are expected to be usable in processing of bulk structures and materials. Test data indicate that small bundles of SWNTs and single SWNTs at concentrations up to 1.1 weight percent have been present in water plus surfactant. This development is expected to contribute to the growth of an industry based on applied carbon nanotechnology. There are expected to be commercial applications in aerospace, avionics, sporting goods, automotive products, biotechnology, and medicine.

Noble Gas Signatures in Snow: a New Experimental Investigation.

NASA Astrophysics Data System (ADS)

Amalberti, J.; Hall, C. M.; Castro, C.

2016-12-01

Dissolved noble gases in groundwater (He, Ne, Ar, Kr, and Xe) have been widely used to improve our knowledge of surface and groundwater dynamics. However, a recent rainwater study [1] recorded noble gas concentration anomalies originating from conditions at high altitude. Potential anomaly sources might include fog, orographic rain, synoptic rain and snow, depending on the region considered. Here, we outline a methodology for measuring noble gases in freshly collected snow samples. Their fine-grained nature leads to significant experimental challenges. Overall, our results (Fig. 1) show that snow has elevated He concentrations with depleted concentrations of all other noble gases. Similar results have been recorded in ice [2, 3]. In addition, our results show relatively homogeneous (< 14%) He and Ne concentrations while Ar, Kr and Xe display large concentration variability (> 80%). These observations led us to investigate the structure of snow and potential host-sites (available empty space) within the crystal structure. Noble gases are chemically inert and do not form bonds that could affect the ice crystal structure. Therefore, host-sites control the solubility of each noble gas. Our results show that He and Ne, which are known to have small atomic radii, are likely dissolved into the ice/snow crystal lattice, while heavy noble gas (Ar, Kr and Xe) are likely accommodated into defects. Consequently, smaller variability recorded in light noble gases, may result from He and Ne being hosted within the crystal lattice, whereas heavy noble gases rely on the presence of defects, which may randomly appear within the structure during snow formation. These new results can be used to better constrain the source of ground ice [3], groundwater systems and to investigate the structural transition mechanisms from snow to firn and ice. Figure 1: Noble gas concentrations (C) in snow (filled circles symbols) and ice (half-filled square symbols) normalized to air saturated water (ASW). [1] Warrier, et al., (2013), Geophys. Res. Lett., 40, 3248-3252. [2] Malone et al., (2010), EPSL, 289, 112-122. [3] Utting et a., (2016), Quat. Res., 85, 117-184.

Constriction model of actomyosin ring for cytokinesis by fission yeast using a two-state sliding filament mechanism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jung, Yong-Woon; Mascagni, Michael, E-mail: Mascagni@fsu.edu

2014-09-28

We developed a model describing the structure and contractile mechanism of the actomyosin ring in fission yeast, Schizosaccharomyces pombe. The proposed ring includes actin, myosin, and α-actinin, and is organized into a structure similar to that of muscle sarcomeres. This structure justifies the use of the sliding-filament mechanism developed by Huxley and Hill, but it is probably less organized relative to that of muscle sarcomeres. Ring contraction tension was generated via the same fundamental mechanism used to generate muscle tension, but some physicochemical parameters were adjusted to be consistent with the proposed ring structure. Simulations allowed an estimate of ringmore » constriction tension that reproduced the observed ring constriction velocity using a physiologically possible, self-consistent set of parameters. Proposed molecular-level properties responsible for the thousand-fold slower constriction velocity of the ring relative to that of muscle sarcomeres include fewer myosin molecules involved, a less organized contractile configuration, a low α-actinin concentration, and a high resistance membrane tension. Ring constriction velocity is demonstrated as an exponential function of time despite a near linear appearance. We proposed a hypothesis to explain why excess myosin heads inhibit constriction velocity rather than enhance it. The model revealed how myosin concentration and elastic resistance tension are balanced during cytokinesis in S. pombe.« less

Optimization of extraction process by response surface methodology and preliminary structural analysis of polysaccharides from defatted peanut (Arachis hypogaea) cakes.

PubMed

Song, Yi; Du, Bingjian; Zhou, Ting; Han, Bing; Yu, Fei; Yang, Rui; Hu, Xiaosong; Ni, Yuanying; Li, Quanhong

2011-02-01

In this work, response surface methodology was used to determine optimum conditions for extraction of polysaccharides from defatted peanut cake. A central composite design including independent variables, such as extraction temperature (x(1)), extraction time (x(2)), and ethanol concentration (x(3)) was used. Selected response which evaluates the extraction process was polysaccharide yield, and the second-order model obtained for polysaccharide yield revealed coefficient of determination of 97.81%. The independent variable with the largest effect on response was ethanol concentration (x(3)). The optimum extraction conditions were found to be extraction temperature 48.7°C, extraction time 1.52 h, and ethanol concentration of 61.9% (v/v), respectively. Under these conditions, the extraction efficiency of polysaccharide can increase to 25.89%. The results of structural analysis showed that the main composition of defatted peanut cake polysaccharide was α-galactose. 2010 Elsevier Ltd. All rights reserved.

Structural stability of DNA origami nanostructures in the presence of chaotropic agents

NASA Astrophysics Data System (ADS)

Ramakrishnan, Saminathan; Krainer, Georg; Grundmeier, Guido; Schlierf, Michael; Keller, Adrian

2016-05-01

DNA origami represent powerful platforms for single-molecule investigations of biomolecular processes. The required structural integrity of the DNA origami may, however, pose significant limitations regarding their applicability, for instance in protein folding studies that require strongly denaturing conditions. Here, we therefore report a detailed study on the stability of 2D DNA origami triangles in the presence of the strong chaotropic denaturing agents urea and guanidinium chloride (GdmCl) and its dependence on concentration and temperature. At room temperature, the DNA origami triangles are stable up to at least 24 h in both denaturants at concentrations as high as 6 M. At elevated temperatures, however, structural stability is governed by variations in the melting temperature of the individual staple strands. Therefore, the global melting temperature of the DNA origami does not represent an accurate measure of their structural stability. Although GdmCl has a stronger effect on the global melting temperature, its attack results in less structural damage than observed for urea under equivalent conditions. This enhanced structural stability most likely originates from the ionic nature of GdmCl. By rational design of the arrangement and lengths of the individual staple strands used for the folding of a particular shape, however, the structural stability of DNA origami may be enhanced even further to meet individual experimental requirements. Overall, their high stability renders DNA origami promising platforms for biomolecular studies in the presence of chaotropic agents, including single-molecule protein folding or structural switching.DNA origami represent powerful platforms for single-molecule investigations of biomolecular processes. The required structural integrity of the DNA origami may, however, pose significant limitations regarding their applicability, for instance in protein folding studies that require strongly denaturing conditions. Here, we therefore report a detailed study on the stability of 2D DNA origami triangles in the presence of the strong chaotropic denaturing agents urea and guanidinium chloride (GdmCl) and its dependence on concentration and temperature. At room temperature, the DNA origami triangles are stable up to at least 24 h in both denaturants at concentrations as high as 6 M. At elevated temperatures, however, structural stability is governed by variations in the melting temperature of the individual staple strands. Therefore, the global melting temperature of the DNA origami does not represent an accurate measure of their structural stability. Although GdmCl has a stronger effect on the global melting temperature, its attack results in less structural damage than observed for urea under equivalent conditions. This enhanced structural stability most likely originates from the ionic nature of GdmCl. By rational design of the arrangement and lengths of the individual staple strands used for the folding of a particular shape, however, the structural stability of DNA origami may be enhanced even further to meet individual experimental requirements. Overall, their high stability renders DNA origami promising platforms for biomolecular studies in the presence of chaotropic agents, including single-molecule protein folding or structural switching. Electronic supplementary information (ESI) available: Melting curves without baseline subtraction, AFM images of DNA origami after 24 h incubation, calculated melting temperatures of all staple strands. See DOI: 10.1039/c6nr00835f

Understanding Market Concentration: Internet-Based Applications from the Banking Industry

ERIC Educational Resources Information Center

Hays, Fred H.; Ward, Sidne Gail

2011-01-01

Market structure is an essential topic in economics and finance courses, including bank management as well as many other business school courses, for example marketing, human resources and strategic management. Instructors explain the virtues of perfect competition and the evils of monopoly along with alternative market models. Often conversations…

KABAM Version 1.0 User's Guide and Technical Documentation - Appendix C - Explanation of Default Values Representing Biotic Characteristics of Aquatic Ecosystem, Including Food Web Structure

EPA Pesticide Factsheets

Information relevant to KABAM and explanations of default parameters used to define the 7 trophic levels. KABAM is a simulation model used to predict pesticide concentrations in aquatic regions for use in exposure assessments.

Lasting effect of soil warming on organic matter decomposition depends on tillage practices

USDA-ARS?s Scientific Manuscript database

Global warming affects various parts of carbon (C) cycle including acceleration of soil organic matter (SOM) decomposition with strong feedback to atmospheric CO2 concentration. Despite many soil warming studies showed changes of microbial community structure, very few were focused on the effect of ...

Modeling Emissions and Vertical Plume Transport of Crop Residue Burning Experiments in the Pacific Northwest

EPA Science Inventory

A study in eastern Washington (Walla Walla) and north Idaho (Nez Perce) in August 2013 consisted of multiple burns of well characterized fuels with nearby surface and aerial measurements including trace species concentrations, plume rise height and boundary layer structure. Detai...

High performance, durable polymers including poly(phenylene)

DOEpatents

Fujimoto, Cy; Pratt, Harry; Anderson, Travis Mark

2017-02-28

The present invention relates to functionalized polymers including a poly(phenylene) structure. In some embodiments, the polymers and copolymers of the invention include a highly localized concentration of acidic moieties, which facilitate proton transport and conduction through networks formed from these polymers. In addition, the polymers can include functional moieties, such as electron-withdrawing moieties, to protect the polymeric backbone, thereby extending its durability. Such enhanced proton transport and durability can be beneficial for any high performance platform that employs proton exchange polymeric membranes, such as in fuel cells or flow batteries.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hunter, C.; Simpson, J.; Kovats, Z.

Sediments from Soda Creek were evaluated using the Sediment Quality Triad as part of investigations being conducted at the Monsanto Company plant in Soda Springs, Idaho. Information collected by an ecological assessment included metal concentrations (arsenic, cadmium, copper, molybdenum, nickel, selenium, silver, and vanadium), benthic fauna community structure, and sediment toxicity. The collected sediments were composed of sandy-silt sized particles, with 2.4% to 9.1% organic carbon. Metal concentrations at sample stations were elevated relative to sediments collected from reference stations. For example, average cadmium concentrations ranged from 13 to 48 mg/kg at sample stations and 0.72 to 3.2 mg/kg atmore » reference stations; selenium concentrations ranged from 4.7 to 91 mg/kg at sample stations and 0.82 to 2.7 mg/kg at reference stations. Soda Creek has a relatively low flow gradient and the benthic fauna at both reference and sample stations was dominated by oligochaete worms and chironomid midge larvae. Taxonomic richness at individual sites ranged from 4.3 to 6.7 and 6 to 10.3 at reference and sample sites, respectively. There was no significant evidence of toxicity at any location sampled. Cluster analysis showed that the benthic community structure of many of the sample stations could not be distinguished from the reference stations. Canonical correlation analysis showed there was a significant relationship between benthic fauna and metal concentration, but there was not a consistent difference between sample and reference stations. For Soda Creek, local phenomena were more significant to benthic community structure than large-scale patterns of metal accumulation. Using the Triad approach, the authors concluded there has been no adverse effect of metal concentrations on the benthic community of Soda Creek.« less

Crystal structure of a concentrative nucleoside transporter from Vibrio cholerae at 2.4;#8201;Å

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Zachary Lee; Cheong, Cheom-Gil; Lee, Seok-Yong

2012-07-11

Nucleosides are required for DNA and RNA synthesis, and the nucleoside adenosine has a function in a variety of signalling processes. Transport of nucleosides across cell membranes provides the major source of nucleosides in many cell types and is also responsible for the termination of adenosine signalling. As a result of their hydrophilic nature, nucleosides require a specialized class of integral membrane proteins, known as nucleoside transporters (NTs), for specific transport across cell membranes. In addition to nucleosides, NTs are important determinants for the transport of nucleoside-derived drugs across cell membranes. A wide range of nucleoside-derived drugs, including anticancer drugsmore » (such as Ara-C and gemcitabine) and antiviral drugs (such as zidovudine and ribavirin), have been shown to depend, at least in part, on NTs for transport across cell membranes. Concentrative nucleoside transporters, members of the solute carrier transporter superfamily SLC28, use an ion gradient in the active transport of both nucleosides and nucleoside-derived drugs against their chemical gradients. The structural basis for selective ion-coupled nucleoside transport by concentrative nucleoside transporters is unknown. Here we present the crystal structure of a concentrative nucleoside transporter from Vibrio cholerae in complex with uridine at 2.4 {angstrom}. Our functional data show that, like its human orthologues, the transporter uses a sodium-ion gradient for nucleoside transport. The structure reveals the overall architecture of this class of transporter, unravels the molecular determinants for nucleoside and sodium binding, and provides a framework for understanding the mechanism of nucleoside and nucleoside drug transport across cell membranes.« less

Deep Structure of the Earth and Concentration of Metals in the Lithosphere: A Geodynamic Approach

NASA Technical Reports Server (NTRS)

Taylor, Patrick T.; Kutina, J.; Pei, R.

2004-01-01

A discussion of and introduction to satellite-altitude geopotential fields studies and their interpretation with emphasis on results from metalliferous regions will be given. The magnetic and gravimetric measurements from satellite altitudes show heterogeneity in deeper parts of the lithosphere. These patterns of magnetic anomalies do not only reveal the largest iron ore deposits such as Kiruna, Sweden and Kursk, Russia, but also linear features indicating structural discontinuities. Changes of magnetic amplitude of these patterns are caused by intersecting transverse fractures localizing magmatism and concentration of metals. The role of trans-regional mantle-rooted structural discontinuities in the concentration of metals will be discussed and a new type of mineral prognosis map will be presented. Deep-rooted structural discontinuities, defined by combination of geological and geophysical criteria, with spacing of several hundred kilometers, reveal a quite uniform pattern in the deeper parts of the lithosphere. As these structures provide favorable pathways for the ascent of heat, magmas and ore-forming fluids, their recognition is of crucial importance and can be used in the compilation of a new type of mineral prognosis map. Examples are shown from the United States, Canada, China, Burma, South America, Europe and Australia. The European example includes a pattern of east west trending structural discontinuities or belts and their junction with the NW-trending Tornqvist-Teisseyre Line. The Upper Silesian-Cracovian Zn-Pb district occurs along one of the latitudinal belts. Leslaw Teper of the University of Silesia has been invited to show the fractures in crystalline basement beneath the sediments hosting the Zn-Pb ores.

Probe-And-Socket Fasteners For Robotic Assembly

NASA Technical Reports Server (NTRS)

Nyberg, Karen

1995-01-01

Self-alignment and simplicity of actuation make mechanism amenable to robotic assembly. Includes socket, mounted on structure at worksite, and probe, mounted on piece of equipment to be attached to structure at socket. Probe-and-socket mechanism used in conjunction with fixed target aiding in placement of end effector of robot during grasping, and with handle or handles on structure. Intended to enable robot to set up workstation in hostile environment. Workstation then used by astronaut, aquanaut, or other human, spending minimum time in environment. Human concentrates on performing quality work rather than on setting up equipment, with consequent reduction of risk.

Relationship Study on Land Use Spatial Distribution Structure and Energy-Related Carbon Emission Intensity in Different Land Use Types of Guangdong, China, 1996–2008

PubMed Central

Huang, Yi; Yang, Lei

2013-01-01

This study attempts to discuss the relationship between land use spatial distribution structure and energy-related carbon emission intensity in Guangdong during 1996–2008. We quantized the spatial distribution structure of five land use types including agricultural land, industrial land, residential and commercial land, traffic land, and other land through applying spatial Lorenz curve and Gini coefficient. Then the corresponding energy-related carbon emissions in each type of land were calculated in the study period. Through building the reasonable regression models, we found that the concentration degree of industrial land is negatively correlated with carbon emission intensity in the long term, whereas the concentration degree is positively correlated with carbon emission intensity in agricultural land, residential and commercial land, traffic land, and other land. The results also indicate that land use spatial distribution structure affects carbon emission intensity more intensively than energy efficiency and production efficiency do. These conclusions provide valuable reference to develop comprehensive policies for energy conservation and carbon emission reduction in a new perspective. PMID:23476128

Relationship study on land use spatial distribution structure and energy-related carbon emission intensity in different land use types of Guangdong, China, 1996-2008.

PubMed

Huang, Yi; Xia, Bin; Yang, Lei

2013-01-01

This study attempts to discuss the relationship between land use spatial distribution structure and energy-related carbon emission intensity in Guangdong during 1996-2008. We quantized the spatial distribution structure of five land use types including agricultural land, industrial land, residential and commercial land, traffic land, and other land through applying spatial Lorenz curve and Gini coefficient. Then the corresponding energy-related carbon emissions in each type of land were calculated in the study period. Through building the reasonable regression models, we found that the concentration degree of industrial land is negatively correlated with carbon emission intensity in the long term, whereas the concentration degree is positively correlated with carbon emission intensity in agricultural land, residential and commercial land, traffic land, and other land. The results also indicate that land use spatial distribution structure affects carbon emission intensity more intensively than energy efficiency and production efficiency do. These conclusions provide valuable reference to develop comprehensive policies for energy conservation and carbon emission reduction in a new perspective.

Can fisheries management make substantial progress towards further reductions in sport fish PCB concentrations?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jackson, L.J.

1995-12-31

Great Lakes managers continue to be concerned by PCB concentrations in Great Lakes sport fish. A reduction in sport fish consumption advisory levels would heighten public concern and increase pressure on managers to reduce contaminant levels in sport fish. PCB concentrations in Great Lakes sediments remain high and exchange with the water column is significant. Atmospheric inputs help maintain PCB availability in the Great Lakes. However, it is not technically feasible to control sediment and atmospheric inputs. Here the author uses a detailed age-structured simulation model of chinook salmon, alewife and rainbow smelt to examine the potential for fish managementmore » actions to make progress towards reducing PCB concentrations of sport fish consumed by humans. Chinook salmon PCB concentrations were found to be more affected by prey PCB concentrations than chinook salmon growth rates. Salmonid predators selectively attack the largest prey, but these prey are likely the oldest and most contaminated. The interaction between size selective predation by chinook salmon and their growth rates suggests that there is an ideal stocking level of sport fish that should keep the average prey fish small, and therefore have relatively low PCE concentrations, but not reduce the age structure of the alewife population to include few reproductive individuals. These results are applicable to other stocked salmonids too, (e.g., lake trout, brown trout, coho salmon, steelhead) because they also exhibit size selective predation and their recruitment is primarily by stocking.« less

Multiscale modeling of thermal conductivity of high burnup structures in UO 2 fuels

DOE PAGES

Bai, Xian -Ming; Tonks, Michael R.; Zhang, Yongfeng; ...

2015-12-22

The high burnup structure forming at the rim region in UO 2 based nuclear fuel pellets has interesting physical properties such as improved thermal conductivity, even though it contains a high density of grain boundaries and micron-size gas bubbles. To understand this counterintuitive phenomenon, mesoscale heat conduction simulations with inputs from atomistic simulations and experiments were conducted to study the thermal conductivities of a small-grain high burnup microstructure and two large-grain unrestructured microstructures. We concluded that the phonon scattering effects caused by small point defects such as dispersed Xe atoms in the grain interior must be included in order tomore » correctly predict the thermal transport properties of these microstructures. In extreme cases, even a small concentration of dispersed Xe atoms such as 10 -5 can result in a lower thermal conductivity in the large-grain unrestructured microstructures than in the small-grain high burnup structure. The high-density grain boundaries in a high burnup structure act as defect sinks and can reduce the concentration of point defects in its grain interior and improve its thermal conductivity in comparison with its large-grain counterparts. Furthermore, an analytical model was developed to describe the thermal conductivity at different concentrations of dispersed Xe, bubble porosities, and grain sizes. Upon calibration, the model is robust and agrees well with independent heat conduction modeling over a wide range of microstructural parameters.« less

Structure of Laminar Permanently Blue, Opposed-Jet Ethylene-Fueled Diffusion Flames

NASA Technical Reports Server (NTRS)

Lin, K.-C.; Faeth, G. M.; Urban, D. L. (Technical Monitor)

2000-01-01

The structure and state relationships of laminar soot-free (permanently blue) ethylene-fueled diffusion flames at various strain rates were studied both experimentally and computationally using an opposed-jet configuration. Measurements of gas velocities, temperatures, and compositions were carried out along the stagnation stream line. Corresponding predictions of flame structure were obtained, based on numerical simulations using several contemporary reaction mechanisms for methane oxidation. Flame conditions studied included ethylene-fueled opposed-jet diffusion flames having stoichiometric mixture fractions of 0.7 with measurements involving strain rates of 60-240/s and predictions involving strain rates of 0-1140/s at normal temperature and pressure. It was found that measured major gas species concentrations and temperature distributions were in reasonably good agreement with predictions using mechanisms due to GRI-Mech and Peters and that effects of preferential diffusion significantly influence flame structure even when reactant mass diffusivities are similar. Oxygen leakage to fuel-rich conditions and carbon monoxide leakage to fuel-lean conditions both increased as strain rates increased. Furthermore, increased strain rates caused increased fuel concentrations near the flame sheet, decreased peak gas temperatures, and decreased concentrations of carbon dioxide and water vapor throughout the flames. State relationships for major gas species and gas temperatures were found to exist over a broad range of strain rates, providing potential for significant computational simplifications for modeling purposes in some instances.

Structure of Laminar Permanently Blue, Opposed-Jet Ethylene-Fueled Diffusion Flames. Appendix E

NASA Technical Reports Server (NTRS)

Lin, K.-C.; Faeth, G. M.; Urban, D. L. (Technical Monitor)

2000-01-01

The structure and state relationships of laminar soot-free (permanently blue) ethylene-fueled diffusion flames at various strain rates were studied both experimentally and computationally using an opposed-jet configuration. Measurements of gas velocities, temperatures, and compositions were carried out along the stagnation stream line. Corresponding predictions of flame structure were obtained, based on numerical simulations using several contemporary reaction mechanisms for methane oxidation. Flame conditions studied included ethylene-fueled opposed-jet diffusion flames having stoichiometric mixture fractions of 0.7 with measurements involving strain rates of 60-240/s and predictions involving strain rates of 0-1140/s at normal temperature and pressure. It was found that measured major gas species concentrations and temperature distributions were in reasonably good agreement with predictions using mechanisms due to GRI-Mech and Peters and that effects of preferential diffusion significantly influence flame structure even when reactant mass diffusivities are similar. Oxygen leakage to fuel-rich conditions and carbon monoxide leakage to fuel-lean conditions both increased as strain rates increased. Furthermore, increased strain rates caused increased fuel concentrations near the flame sheet, decreased peak gas temperatures, and decreased concentrations of carbon dioxide and water vapor throughout the flames. State relationships for major gas species and gas temperatures were found to exist over a broad range of strain rates, providing potential for significant computational simplifications for modeling purposes in some instances.

Solar concentrator advanced development project

NASA Technical Reports Server (NTRS)

Corrigan, Robert D.; Ehresman, Derik T.

1987-01-01

A solar dynamic concentrator design developed for use with a solar-thermodynamic power generation module intended for the Space Station is considered. The truss hexagonal panel reflector uses a modular design approach and is flexible in attainable flux profiles and assembly techniques. Preliminary structural, thermal, and optical analysis results are discussed. Accuracy of the surface reflectors should be within 5 mrad rms slope error, resulting in the need for close fabrication tolerances. Significant fabrication issues to be addressed include the facet reflective and protective coating processes and the surface specularity requirements.

Positive ion densities and mobilities in the upper stratosphere and mesosphere

NASA Technical Reports Server (NTRS)

Leiden, S.

1976-01-01

A brief sketch of the theory concerning the use of the Gerdien condenser as a mobility spectrometer is presented. Data reduction of three parachute borne Gerdien condenser probes is given, as well as that of one blunt conductivity probe. Comparisons of concentrations calculated by two different methods indicate consistency of results. Mobility profiles demonstrating remarkable fine structure are discussed in detail. Finally, theoretical implications of the results on ionospheric structure, including possible night-day differences and latitudinal variations, are considered.

Characterization of the structure, clean-sand percentage, dissolved-solids concentrations, and estimated quantity of groundwater in the Upper Cretaceous Nacatoch Sand and Tokio Formation, Arkansas

USGS Publications Warehouse

Gillip, Jonathan A.

2014-01-01

The West Gulf Coastal Plain, Mississippi embayment, and underlying Cretaceous aquifers are rich in water resources; however, large parts of the aquifers are largely unusable because of large concentrations of dissolved solids. Cretaceous aquifers are known to have large concentrations of salinity in some parts of Arkansas. The Nacatoch Sand and the Tokio Formation of Upper Cretaceous age were chosen for investigation because these aquifers produce groundwater to wells near their outcrops and have large salinity concentrations away from their outcrop areas. Previous investigations have indicated that dissolved-solids concentrations of groundwater within the Nacatoch Sand, 2–20 miles downdip from the outcrop, render the groundwater as unusable for purposes requiring freshwater. Groundwater within the Tokio Formation also exhibits large concentrations of dissolved solids downdip. Water-quality data showing elevated dissolved-solids concentrations are limited for these Cretaceous aquifers because other shallower aquifers are used for water supply. Although not suitable for many uses, large, unused amounts of saline groundwater are present in these aquifers. Historical borehole geophysical logs were used to determine the geologic and hydrogeologic properties of these Cretaceous aquifers, as well as the quality of the groundwater within the aquifers. Based on the interpretation of borehole geophysical logs, in Arkansas, the altitude of the top of the Nacatoch Sand ranges from more than 200 to less than -4,000 feet; the structural high occurs in the outcrop area and the structural low occurs in southeastern Arkansas near the Desha Basin structural feature. The thickness of the Nacatoch Sand ranges from 0 to over 550 feet. The minimum thickness occurs where the formation pinches out in the outcrop area, and the maximum thickness occurs in the southwestern corner of Arkansas. Other areas of large thickness include the area of the Desha Basin structural feature in southeastern Arkansas and in an area on the border of Cross and St. Francis Counties in eastern Arkansas. The clean-sand percentage of the total Nacatoch Sand thickness ranges from less than 20 percent to more than 60 percent and generally decreases downdip. The Nacatoch Sand contains more than 120.5 million acre-feet of water with a dissolved-solids concentration between 1,000 and 10,000 milligrams per liter (mg/L), more than 57.5 million acre-feet of water with a dissolved-solids concentration between 10,000 and 35,000 mg/L, and more than 122.5 million acre-feet of water with a dissolved-solids concentration more than 35,000 mg/L. The altitude of the top of the Tokio Formation, in Arkansas, ranges from more than 200 feet to less than -4,400 feet; the structural high occurs in the outcrop area and the structural low occurs in southeastern Arkansas near the Desha Basin structural feature. The thickness of the Tokio Formation, in Arkansas, ranges from 0 to over 400 feet. The minimum thickness occurs where the formation pinches out in the outcrop area, and the maximum thickness occurs in the southwestern corner of Arkansas. The clean-sand percentage of the total Tokio Formation thickness ranges from less than 20 percent to more than 60 percent and generally decreases away from the outcrop area. The Tokio Formation contains more than 2.5 million acre-feet of water with a dissolved-solids concentration between 1,000 and 10,000 mg/L, more than 12.5 million acre-feet of water with a dissolved-solids concentration between 10,000 and 35,000 mg/L, and nearly 43.5 million acre-feet of water with a dissolved-solids concentration more than 35,000 mg/L.

Integrated field emission array for ion desorption

DOEpatents

Resnick, Paul J; Hertz, Kristin L.; Holland, Christopher; Chichester, David

2016-08-23

An integrated field emission array for ion desorption includes an electrically conductive substrate; a dielectric layer lying over the electrically conductive substrate comprising a plurality of laterally separated cavities extending through the dielectric layer; a like plurality of conically-shaped emitter tips on posts, each emitter tip/post disposed concentrically within a laterally separated cavity and electrically contacting the substrate; and a gate electrode structure lying over the dielectric layer, including a like plurality of circular gate apertures, each gate aperture disposed concentrically above an emitter tip/post to provide a like plurality of annular gate electrodes and wherein the lower edge of each annular gate electrode proximate the like emitter tip/post is rounded. Also disclosed herein are methods for fabricating an integrated field emission array.

Integrated field emission array for ion desorption

DOEpatents

Resnick, Paul J; Hertz, Kristin L; Holland, Christopher; Chichester, David; Schwoebel, Paul

2013-09-17

An integrated field emission array for ion desorption includes an electrically conductive substrate; a dielectric layer lying over the electrically conductive substrate comprising a plurality of laterally separated cavities extending through the dielectric layer; a like plurality of conically-shaped emitter tips on posts, each emitter tip/post disposed concentrically within a laterally separated cavity and electrically contacting the substrate; and a gate electrode structure lying over the dielectric layer, including a like plurality of circular gate apertures, each gate aperture disposed concentrically above an emitter tip/post to provide a like plurality of annular gate electrodes and wherein the lower edge of each annular gate electrode proximate the like emitter tip/post is rounded. Also disclosed herein are methods for fabricating an integrated field emission array.

Solar concentrator with integrated tracking and light delivery system with summation

DOEpatents

Maxey, Lonnie Curt

2015-05-05

A solar light distribution system includes a solar light concentrator that is affixed externally to a light transfer tube. Solar light waves are processed by the concentrator into a collimated beam of light, which is then transferred through a light receiving port and into the light transfer tube. A reflector redirects the collimated beam of light through the tube to a light distribution port. The interior surface of the light transfer tube is highly reflective so that the light transfers through the tube with minimal losses. An interchangeable luminaire is attached to the light distribution port and provides light inside of a structure. A sun tracking device rotates the concentrator and the light transfer tube to optimize the receiving of solar light by the concentrator throughout the day. The system provides interior lighting that uses only renewable energy sources, and releases no carbon dioxide emissions into the atmosphere.

Solar concentrator with integrated tracking and light delivery system with collimation

DOEpatents

Maxey, Lonnie Curt

2015-06-09

A solar light distribution system includes a solar light concentrator that is affixed externally to a light transfer tube. Solar light waves are processed by the concentrator into a collimated beam of light, which is then transferred through a light receiving port and into the light transfer tube. A reflector directs the collimated beam of light through the tube to a light distribution port. The interior surface of the light transfer tube is highly reflective so that the light transfers through the tube with minimal losses. An interchangeable luminaire is attached to the light distribution port and distributes light inside of a structure. A sun tracking device rotates the concentrator and the light transfer tube to optimize the receiving of solar light by the concentrator throughout the day. The system provides interior lighting, uses only renewable energy sources, and releases no carbon dioxide emissions into the atmosphere.

No association between hair cortisol or cortisone and brain morphology in children.

PubMed

Chen, Ruoqing; Muetzel, Ryan L; El Marroun, Hanan; Noppe, Gerard; van Rossum, Elisabeth F C; Jaddoe, Vincent W; Verhulst, Frank C; White, Tonya; Fang, Fang; Tiemeier, Henning

2016-12-01

Little is known about the relationship between the long-term hypothalamic-pituitary-adrenal (HPA) axis functioning and brain structure in children. Glucocorticoid in hair has emerged as an important biomarker of HPA activity. In this study, we investigated the associations of hair cortisol and cortisone concentrations with brain morphology in young children. We included 219 children aged 6-10 years from the Generation R Study in Rotterdam, the Netherlands. We examined cortisol and cortisone concentrations by hair analysis using liquid chromatography-tandem mass spectrometry, and assessed brain morphometric measures with structural magnetic resonance imaging. The relationships of hair cortisol and cortisone concentrations with brain volumetrics, cortical thickness, cortical surface area and gyrification were analyzed separately after adjustment for several potential confounding factors. We observed a positive association between cortisol concentrations and cortical surface area in the parietal lobe, positive associations of cortisone concentrations with thalamus volume, occipital lobe volume and cortical surface area in the parietal lobe, and a negative association between cortisone concentrations and cortical surface area in the temporal lobe in the regions of interest analyses. A negative association between cortisol or cortisone concentrations and hippocampal volume was observed in children with behavioral problems. The whole brain vertex-wise analyses did however not show any association between cortisol or cortisone concentration and brain morphometric measures after correction for multiple testing. Although some associations are noted in region of interest analyses, we do not observe clear association of hair cortisol or cortisone with brain morphometric measures in typically developing young children. Copyright © 2016 Elsevier Ltd. All rights reserved.

CO2 capture by means of an enzyme-based reactor

NASA Technical Reports Server (NTRS)

Cowan, R. M.; Ge, J-J; Qin, Y-J; McGregor, M. L.; Trachtenberg, M. C.

2003-01-01

We report a means for efficient and selective extraction of carbon dioxide (CO(2)) at low to medium concentration from mixed gas streams. CO(2) capture was accomplished by use of a novel enzyme-based, facilitated transport contained liquid membrane (EBCLM) reactor. The parametric studies we report explore both structural and operational parameters of this design. The structural parameters include carbonic anhydrase (CA) concentration, buffer concentration and pH, and liquid membrane thickness. The operational parameters are temperature, humidity of the inlet gas stream, and CO(2) concentration in the feed stream. The data show that this system effectively captures CO(2) over the range 400 ppm to at least 100,000 ppm, at or around ambient temperature and pressure. In a single pass across this homogeneous catalyst design, given a feed of 0.1% CO(2), the selectivity of CO(2) versus N(2) is 1,090 : 1 and CO(2) versus O(2) is 790 :1. CO(2) permeance is 4.71 x 10(-8) molm(-2) Pa(-1) sec(-1). The CLM design results in a system that is very stable even in the presence of dry feed and sweep gases.

The Structure-Activity Relationship between Marine Algae Polysaccharides and Anti-Complement Activity

PubMed Central

Jin, Weihua; Zhang, Wenjing; Liang, Hongze; Zhang, Quanbin

2015-01-01

In this study, 33 different polysaccharides were prepared to investigate the structure-activity relationships between the polysaccharides, mainly from marine algae, and anti-complement activity in the classical pathway. Factors considered included extraction methods, fractionations, molecular weight, molar ratio of galactose to fucose, sulfate, uronic acid (UA) content, linkage, branching, and the type of monosaccharide. It was shown that the larger the molecular weights, the better the activities. The molar ratio of galactose (Gal) to fucose (Fuc) was a positive factor at a concentration lower than 10 µg/mL, while it had no effect at a concentration more than 10 µg/mL. In addition, sulfate was necessary; however, the sulfate content, the sulfate pattern, linkage and branching had no effect at a concentration of more than 10 µg/mL. Moreover, the type of monosaccharide had no effect. Laminaran and UA fractions had no activity; however, they could reduce the activity by decreasing the effective concentration of the active composition when they were mixed with the active compositions. The effect of the extraction methods could not be determined. Finally, it was observed that sulfated galactofucan showed good anti-complement activity after separation. PMID:26712768

A Balloon-Borne Cloud Condensation Nuclei Counter

NASA Technical Reports Server (NTRS)

Delene, David J.; Deshler, Terry; Wechsler, Perry; Vali, Gabor A.

1997-01-01

A balloon-borne instrument was constructed for observations of vertical profiles of cloud condensation nucleus (CCN) concentrations, active at 1% supersaturation. Droplet concentration in the static thermal-gradient diffusion chamber is deduced from the amount of scattered laser light detected by a photodetector. The photodetector is calibrated using a video camera and computer system to count the number of droplets produced from NaCl aerosol. Preliminary data are available from nine early morning profiles obtained at Laramie, Wyoming, between June 1995 and January 1997. To complement the CCN measurements, instruments that measure condensation nuclei (CN) and aerosols with diameter greater than 0.30 micrometers (D(sub 0.3) were also included on the balloon package. CCN concentrations exhibited a general decrease from the surface to the top of the boundary layers, were generally uniform through well-mixed layers, and show variability above well-mixed layers. In general, the structure of the CCN profile appears to be closely related to the structure in the CN and D(sub 0.3) profiles. Summer profiles generally have CCN concentration greater than 200/cu cm up to 500 mbar, whereas winter profiles are less than 200/cu cm at all levels.

Silicon drift detectors as a tool for time-resolved fluorescence XAFS on low-concentrated samples in catalysis.

PubMed

Kappen, Peter; Tröger, Larc; Materlik, Gerhard; Reckleben, Christian; Hansen, Karsten; Grunwaldt, Jan-Dierk; Clausen, Bjerne S

2002-07-01

A silicon drift detector (SDD) was used for ex situ and time-resolved in situ fluorescence X-ray absorption fine structure (XAFS) on low-concentrated catalyst samples. For a single-element and a seven-element SDD the energy resolution and the peak-to-background ratio were verified at high count rates, sufficient for fluorescence XAFS. An experimental set-up including the seven-element SDD without any cooling and an in situ cell with gas supply and on-line gas analysis was developed. With this set-up the reduction and oxidation of a zeolite supported catalyst containing 0.3 wt% platinum was followed by fluorescence near-edge scans with a time resolution of 10 min each. From ex situ experiments on low-concentrated platinum- and gold-based catalysts fluorescence XAFS scans could be obtained with sufficient statistical quality for a quantitative analysis. Structural information on the gold and platinum particles could be extracted by both the Fourier transforms and the near-edge region of the XAFS spectra. Moreover, it was found that with the seven-element SDD concentrations of the element of interest as low as 100 ppm can be examined by fluorescence XAFS.

The effects of multi-walled carbon nanotubes on soil microbial community functional and structural diversity

USDA-ARS?s Scientific Manuscript database

Applications of nanomaterials, including carbon nanotubes (CNTs), are increasing; however, their impact on the environment is still not well understood. A semi-arid soil was treated with multi-walled carbon nanotubes (MWCNTs) at four different concentrations (10-10000 mgMWCNTs kg-1soil), and incubat...

Effect of hemin, baicalein and heme oxygenase-1 (HO-1) enzyme activity inhibitors on Cd-induced accumulation of HO-1, HSPs and aggresome-like structures in Xenopus kidney epithelial cells.

PubMed

Campbell, James H; Heikkila, John J

2018-04-23

Cadmium is a highly toxic environmental pollutant that can cause many adverse effects including cancer, neurological disease and kidney damage. Aquatic amphibians are particularly susceptible to this toxicant as it was shown to cause developmental abnormalities and genotoxic effects. In mammalian cells, the accumulation of heme oxygenase-1 (HO-1), which catalyzes the breakdown of heme into CO, free iron and biliverdin, was reported to protect cells against potentially lethal concentrations of CdCl 2 . In the present study, CdCl 2 treatment of A6 kidney epithelial cells, derived from the frog, Xenopus laevis, induced the accumulation of HO-1, heat shock protein 70 (HSP70) and HSP30 as well as an increase in the production of aggregated protein and aggresome-like structures. Treatment of cells with inhibitors of HO-1 enzyme activity, tin protoporphyrin (SnPP) and zinc protoporphyrin (ZnPP), enhanced CdCl 2 -induced actin cytoskeletal disorganization and the accumulation of HO-1, HSP70, aggregated protein and aggresome-like structures. Treatment of cells with hemin and baicalein, which were previously shown to provide cytoprotection against various stresses, induced HO-1 accumulation in a concentration-dependent manner. Also, treatment of cells with hemin and baicalein suppressed CdCl 2 -induced actin dysregulation and the accumulation of aggregated protein and aggresome-like structures. This cytoprotective effect was inhibited by SnPP. These results suggest that HO-1-mediated protection against CdCl 2 toxicity includes the maintenance of actin cytoskeletal and microtubular structure and the suppression of aggregated protein and aggresome-like structures. Copyright © 2018 Elsevier Inc. All rights reserved.

Prokaryotic Community Structure Driven by Salinity and Ionic Concentrations in Plateau Lakes of the Tibetan Plateau

PubMed Central

Zhong, Zhi-Ping; Liu, Ying; Miao, Li-Li; Wang, Fang; Chu, Li-Min; Wang, Jia-Li

2016-01-01

The prokaryotic community composition and diversity and the distribution patterns at various taxonomic levels across gradients of salinity and physiochemical properties in the surface waters of seven plateau lakes in the Qaidam Basin, Tibetan Plateau, were evaluated using Illumina MiSeq sequencing. These lakes included Lakes Keluke (salinity, <1 g/liter), Qing (salinity, 5.5 to 6.6 g/liter), Tuosu (salinity, 24 to 35 g/liter), Dasugan (salinity, 30 to 33 g/liter), Gahai (salinity, 92 to 96 g/liter), Xiaochaidan (salinity, 94 to 99 g/liter), and Gasikule (salinity, 317 to 344 g/liter). The communities were dominated by Bacteria in lakes with salinities of <100 g/liter and by Archaea in Lake Gasikule. The clades At12OctB3 and Salinibacter, previously reported only in hypersaline environments, were found in a hyposaline lake (salinity, 5.5 to 6.6 g/liter) at an abundance of ∼1.0%, indicating their ecological plasticity. Salinity and the concentrations of the chemical ions whose concentrations covary with salinity (Mg2+, K+, Cl−, Na+, SO42−, and Ca2+) were found to be the primary environmental factors that directly or indirectly determined the composition and diversity at the level of individual clades as well as entire prokaryotic communities. The distribution patterns of two phyla, five classes, five orders, five families, and three genera were well predicted by salinity. The variation of the prokaryotic community structure also significantly correlated with the dissolved oxygen concentration, pH, the total nitrogen concentration, and the PO43− concentration. Such correlations varied depending on the taxonomic level, demonstrating the importance of comprehensive correlation analyses at various taxonomic levels in evaluating the effects of environmental variable factors on prokaryotic community structures. Our findings clarify the distribution patterns of the prokaryotic community composition in plateau lakes at the levels of individual clades as well as whole communities along gradients of salinity and ionic concentrations. PMID:26746713

Assessing impacts of land-applied manure from concentrated animal feeding operations on fish populations and communities.

PubMed

Leet, Jessica K; Lee, Linda S; Gall, Heather E; Goforth, Reuben R; Sassman, Stephen; Gordon, Denise A; Lazorchak, James M; Smith, Mark E; Jafvert, Chad T; Javfert, Chad T; Sepúlveda, Maria S

2012-12-18

Concentrated animal feeding operation (CAFO) manure is a cost-effective fertilizer. In the Midwest, networks of subsurface tile-drains expedite transport of animal hormones and nutrients from land-applied CAFO manure to adjacent waterways. The objective of this study was to evaluate impacts of land-applied CAFO manure on fish populations and communities. Water chemistry including hormone, pesticide, and nutrient concentrations was characterized from study sites along with fish assemblage structure, growth, and endocrine disruption assessed in selected fish species. Although most CAFO water samples had hormone concentrations <1 ng/L, equivalent concentrations for 17β-E2 and 17α-TB peaked at >30 ng/L each during the period of spawning, hatching, and development for resident fishes. CAFO sites had lower fish species richness, and fishes exhibited faster somatic growth and lower reproductive condition compared to individuals from the reference site. Fathead minnows (Pimephales promelas) exposed to CAFO ditchwater during early developmental stages exhibited significantly skewed sex ratios toward males. Maximum observed hormone concentrations were well above the lowest observable effect concentrations for these hormones; however, complexities at the field scale make it difficult to directly relate hormone concentration and impacts on fish. Complicating factors include the consistent presence of pesticides and nutrients, and the difference in temperature and stream architecture of the CAFO-impacted ditches compared to the reference site (e.g., channelization, bottom substrate, shallow pools, and riparian cover).

Secondary and compound concentrators for parabolic dish solar thermal power systems

NASA Technical Reports Server (NTRS)

Jaffe, L. D.; Poon, P. T.

1981-01-01

A secondary optical element may be added to a parabolic dish solar concentrator to increase the geometric concentration ratio attainable at a given intercept factor. This secondary may be a Fresnel lens or a mirror, such as a compound elliptic concentrator or a hyperbolic trumpet. At a fixed intercept factor, higher overall geometric concentration may be obtainable with a long focal length primary and a suitable secondary matched to it. Use of a secondary to increase the geometric concentration ratio is more likely to e worthwhile if the receiver temperature is high and if errors in the primary are large. Folding the optical path with a secondary may reduce cost by locating the receiver and power conversion equipment closer to the ground and by eliminating the heavy structure needed to support this equipment at the primary focus. Promising folded-path configurations include the Ritchey-Chretien and perhaps some three element geometries. Folding the optical path may be most useful in systems that provide process heat.

Synthesis of platinum nanowheels using a bicellar template.

PubMed

Song, Yujiang; Dorin, Rachel M; Garcia, Robert M; Jiang, Ying-Bing; Wang, Haorong; Li, Peng; Qiu, Yan; van Swol, Frank; Miller, James E; Shelnutt, John A

2008-09-24

Disk-like surfactant bicelles provide a unique meso-structured reaction environment for templating the wet-chemical reduction of platinum(II) salt by ascorbic acid to produce platinum nanowheels. The Pt wheels are 496 +/-55 nm in diameter and possess thickened centers and radial dendritic nanosheets (about 2-nm in thickness) culminating in flared dendritic rims. The structural features of the platinum wheels arise from confined growth of platinum within the bilayer that is also limited at edges of the bicelles. The size of CTAB/FC7 bicelles is observed to evolve with the addition of Pt(II) complex and ascorbic acid. Synthetic control is demonstrated by varying the reaction parameters including metal salt concentration, temperature, and total surfactant concentration. This study opens up opportunities for the use of other inhomogeneous soft templates for synthesizing metals, metal alloys, and possibly semiconductors with complex nanostructures.

High-Flux, High-Temperature Thermal Vacuum Qualification Testing of a Solar Receiver Aperture Shield

NASA Technical Reports Server (NTRS)

Kerslake, Thomas W.; Mason, Lee S.; Strumpf, Hal J.

1997-01-01

As part of the International Space Station (ISS) Phase 1 program, NASA Lewis Research Center (LERC) and the Russian Space Agency (RSA) teamed together to design, build and flight test the world's first orbital Solar Dynamic Power System (SDPS) on the Russian space station Mir. The Solar Dynamic Flight Demonstration (SDFD) program was to operate a nominal 2 kWe SDPS on Mir for a period up to 1-year starting in late 1997. Unfortunately, the SDFD mission was demanifested from the ISS phase 1 shuttle program in early 1996. However, substantial flight hardware and prototypical flight hardware was built including a heat receiver and aperture shield. The aperture shield comprises the front face of the cylindrical cavity heat receiver and is located at the focal plane of the solar concentrator. It is constructed of a stainless steel plate with a 1-m outside diameter, a 0.24-m inside diameter and covered with high-temperature, refractory metal Multi-Foil Insulation (MFI). The aperture shield must minimize heat loss from the receiver cavity, provide a stiff, high strength structure to accommodate shuttle launch loads and protect receiver structures from highly concentrated solar fluxes during concentrator off-pointing events. To satisfy Mir operational safety protocols, the aperture shield was required to accommodate direct impingement of the intensely concentrated solar image for a 1-hour period. To verify thermal-structural durability under the anticipated high-flux, high-temperature loading, an aperture shield test article was constructed and underwent a series of two tests in a large thermal vacuum chamber configured with a reflective, point-focus solar concentrator and a solar simulator. The test article was positioned near the focal plane and exposed to concentrated solar flux for a period of 1-hour. In the first test, a near equilibrium temperature of 1862 K was attained in the center of the shield hot spot. In the second test, with increased incident flux, a near equilibrium temperature of 2072 K was achieved. The aperture shield sustained no visible damage as a result of the exposures. This paper describes the aperture shield thermal-vacuum qualification test program including the test article, test facility, procedures, data collection, test success criteria, results and conclusions.

Induction of chlamydospore formation in fusarium by cyclic lipopeptide antibiotics from Bacillus subtilis C2.

PubMed

Li, Lei; Ma, Mingchuan; Huang, Rong; Qu, Qing; Li, Guohong; Zhou, Jinwei; Zhang, Keqin; Lu, Kaiping; Niu, Xuemei; Luo, Jun

2012-08-01

The culture filtrate of Bacillus subtilis strain C2 showed strong activity against the pathogenic fungus Fusarium solani f. sp. radicicola. A partially purified fraction (PPF) from the extract induced chlamydospore formation in Fusarium. Reverse-phase high performance liquid chromatography yielded 8 different fractions, six of which had chlamydospore-inducing activity. Mass spectrometry and nuclear magnetic resonance analyses identified the main active constituent as C(17) fengycin A (FA17), a cyclic lipopeptide. The effect of FA17 on morphology and physiology of two Fusarium species was dependent on the lipopeptide concentration. When challenged with FA17 at concentrations (0.5, 8, 64 μg ml(-1)) below the minimum inhibitory concentration (MIC) (128 μg ml(-1)), two species of Fusarium formed chlamydospores from hyphae, germ tubes, or inside the conidia within 2 days. At concentrations close to the MIC, FA17 caused Fusarium to form sparse and swollen hyphae or lysed conidia. The other five fractions were identified as fengycin A homologues. The homologues could also induce chlamydospore-like structures in 17 species of filamentous fungi including some specimens that do not normally produce chlamydospores, according to their taxonomic descriptions. Like other chlamydospores, these structures contained nuclei and lipid bodies as revealed by DAPI and Nile Red staining, and could germinate. This is the first study to demonstrate that under laboratory conditions fengycin, an antifungal lipopeptide produced by B. subtilis, can induce chlamydospore formation in Fusarium and chlamydospore-like structures in many filamentous fungi.

Light funnel concentrator panel for solar power

NASA Technical Reports Server (NTRS)

1987-01-01

The solar concentrator design concept provides a theoretical concentration efficiency of 96 percent with power-to-weight ratios as high as 50 W/kg. Further, it eliminates the need for fragile reflective coatings and is very tolerant to pointing inaccuracies. The concept differs from conventional reflective mirrors and lens design in that is uses the principle of total internal reflection in order to funnel incident sunlight into a concentrator photovoltaic cell. The feasibility of the light funnel concentrator concept was determined through a balanced approach of analysis, development, and fabrication of prototypes, and testing of components. A three-dimensional optical model of the light funnel concentrator and photovoltaic cell was developed in order to assess the ultimate performance of such systems. In addition, a thermal and structural analysis of a typical unit was made. Techniques of fabricating the light funnel cones, optically coupling them to GaAs concentrator cells, bonding the funnels to GaAs cells, making electrical interconnects, and bonding substrates was explored and a prototype light funnel concentrator unit was fabricated and tested. Testing of the system included measurements of optical concentrating efficiency, optical concentrator to cell coupling efficiency, and electrical efficiency.

Larkspur (Delphinium spp.) poisoning in livestock.

PubMed

Pfister, J A; Gardner, D R; Panter, K E; Manners, G D; Ralphs, M H; Stegelmeier, B L; Schoch, T K

1999-02-01

Larkspurs (Delphinium spp.) are toxic plants that contain numerous diterpenoid alkaloids which occur as one of two structural types: (1) lycotonine, and (2) 7,8-methylenedioxylycoctonine (MDL-type). Among the lycoctonine type alkaloids are three N-(methylsuccinimido) anthranoyllycoctonine (MSAL-type) alkaloids which appear to be most toxic: methyllycaconitine (MLA), 14-deacetylnudicauline (DAN), and nudicauline. An ester function at C-18 is an important structural requirement for toxicity. Intoxication results from neuromuscular paralysis, as nicotinic acetylcholine receptors in the muscle and brain are blocked by toxic alkaloids. Clinical signs include labored breathing, rapid and irregular heartbeat, muscular weakness, and collapse. Toxic alkaloid concentration generally declines in tall larkspurs with maturation, but alkaloid concentration varies over years and from plant to plant, and is of little use for predicting consumption by cattle. Knowledge of toxic alkaloid concentration is valuable for management purposes when cattle begin to eat larkspur. Cattle generally begin consuming tall larkspur after flowering racemes are elongated, and consumption increases as larkspur matures. Weather is also a major factor in cattle consumption, as cattle tend to eat more larkspur during or just after summer storms. Management options that may be useful for livestock producers include conditioning cattle to avoid larkspur (food aversion learning), grazing tall larkspur ranges before flowering (early grazing) and after seed shatter (late grazing), grazing sheep before cattle, herbicidal control of larkspur plants, and drug therapy for intoxicated animals. Some potentially fruitful research avenues include examining alkaloid chemistry in low and plains larkspurs, developing immunologic methods for analyzing larkspur alkaloids, developing drug therapy, and devising grazing regimes specifically for low and plains larkspur.

Profiling of the Tox21 Chemical Collection for Mitochondrial ...

EPA Pesticide Factsheets

Mitochondrial dysfunction has been implicated in the pathogenesis of a variety of disorders including cancer, diabetes, and neurodegenerative and cardiovascular diseases. Understanding how different environmental chemicals and drug-like molecules impact mitochondrial function represents an initial step in predicting exposure-related toxic effects and defining a possible role for such compounds in the onset of various diseases. OBJECTIVES: To identify individual chemicals and general structural features associated with the disruption of mitochondrial membrane potential (MMP). METHODS: We used a multiplexed quantitative high throughput screening (qHTS) approach combined with informatics tools to screen the Tox21 10,000 compound library (~8300 unique chemicals) at 15 concentrations in triplicate to identify chemicals and structural features that are associated with changes in MMP in HepG2 cells. RESULTS: In the primary screening, approximately 11% of the compounds (913 unique compounds) decreased the MMP after 1 h of treatment without affecting cell viability. Additionally, 309 compounds decreased MMP over a concentration range that also produced measurable cytotoxicity [half maximal inhibitory concentration (IC50) in MMP assay/IC50 in viability assay) ≤ 3, p<0.05]. Over 11% of the structural clusters that constitute the Tox21 library (76 of 651 clusters) were significantly enriched for compounds that decreased the MMP. CONCLUSIONS: Our multiplexed qHTS approach

Impact of monovalent cations on soil structure. Part II. Results of two Swiss soils

NASA Astrophysics Data System (ADS)

Farahani, Elham; Emami, Hojat; Keller, Thomas

2018-01-01

In this study, we investigated the impact of adding solutions with different potassium and sodium concentrations on dispersible clay, water retention characteristics, air permeability, and soil shrinkage behaviour using two agricultural soils from Switzerland with different clay content but similar organic carbon to clay ratio. Three different solutions (including only Na, only K, and the combination of both) were added to soil samples at three different cation ratio of soil structural stability levels, and the soil samples were incubated for one month. Our findings showed that the amount of readily dispersible clay increased with increasing Na concentrations and with increasing cation ratio of soil structural stability. The treatment with the maximum Na concentration resulted in the highest water retention and in the lowest shrinkage capacity. This was was associated with high amounts of readily dispersible clay. Air permeability generally increased during incubation due to moderate wetting and drying cycles, but the increase was negatively correlated with readily dispersible clay. Readily dispersible clay decreased with increasing K, while readily dispersible clay increased with increasing K in Iranian soil (Part I of our study). This can be attributed to the different clay mineralogy of the studied soils (muscovite in Part I and illite in Part II).

Human hemoglobin structural and functional alterations and heme degradation upon interaction with benzene: A spectroscopic study.

PubMed

Hosseinzadeh, Reza; Moosavi-Movahedi, Ali Akbar

2016-03-15

Here, the effect of benzene on hemoglobin structure, stability and heme prosthetic group integrity was studied by different methods. These included UV-vis absorption spectrophotometry, normal and synchronous fluorescence techniques, and differential scanning calorimetry (DSC). Our results indicated that benzene has high hemolytic potential even at low concentrations. The UV-vis spectroscopic results demonstrated that benzene altered both the globin chain and the heme prosthetic group of hemoglobin increasing met- and deoxy-Hb, while decreasing oxy-Hb. However, with increasing benzene the concentration of all species decreased due to heme destruction. The spectrophotometric results show that benzene has a high potential for penetrating the hydrophobic pocket of hemoglobin. These results were consistent with the molecular docking simulation results of benzene-hHb. Aggregation and thermal denaturation studies show that the increased benzene concentration induced hemoglobin aggregation with a decrease in stability, which is consistent with the DSC results. Conventional fluorescence spectroscopy revealed that the heme degradation species were produced in the presence of benzene. The results of constant wavelength synchronous fluorescence spectroscopy (CWSFS) indicated that at least five heme-degraded species were produced. Together, our results indicated that benzene has adverse effects on hemoglobin structure and function, and heme degradation. Copyright © 2015 Elsevier B.V. All rights reserved.

Ultrastructural changes in the hepatocytes of juvenile rainbow trout and mature brown trout exposed to copper or zinc

USGS Publications Warehouse

Leland, H.V.

1983-01-01

Morphological changes in hepatocytes of mature brown trout (Salmo trutta Linnaeus) and juvenile rainbow trout (Salmo gairdneri Richardson), accompanying chronic exposures to copper and zinc, were examined by transmission electron microscopy. At a concentration of copper not inhibitory to the final stages of gonadal development or spawning of brown trout, structural alterations included contraction of mitochondria and a tendency for nuclei to be slightly enlarged. Concentrations of copper or zinc lethal to a small fraction (10% and 4%, respectively) of a population of juvenile rainbow trout exposed for 42 d during larval and early juvenile development caused hepatocyte changes in survivors indicative of a reduction in ability to maintain intracellular water and cation balance and possible intranuclear metal sequestering. Specific structural alterations included increased vesiculation of rough endoplasmic reticulum, an increase in the abundance of electron-dense particles in the nucleus, increases in the numbers of multilaminar and globular inclusions, pooling of glycogen, increased autophagocytic activity and an increase in the number of necrotic cells. At advanced stages of toxicosis (concentrations of copper or zinc lethal to approximately 50% of the juveniles exposed for 42 d during development), loss in integrity of mitochondrial membranes, rupturing of plasma and nuclear membranes, separation of granular and fibrillar nuclear components, fragmentation of endoplasmic reticulum, and extensive autophagic vacuolization were significant features of hepatocytes of surviving juvenile rainbow trout. ?? 1983.

Structure of the Stern layer in Phospholipid Systems

NASA Astrophysics Data System (ADS)

Vangaveti, Sweta; Travesset, Alex

2011-03-01

The structure of the Stern layer in Phospholipid Systems results from a subtle competition of salt concentration, ionic valence, specific ionic-phospolipid interactions and pH. It becomes very challenging to develop a rigorous theory that encompasses all these effects, yet its understanding is extremely relevant for both model and biological systems, as the structure of the Stern layer determines the interactions of phospholipids with proteins or electrostatic phase separation (rafts). In this talk we will present our theoretical model for the Stern Layer and discuss how all these effects are included. Particularly emphasis is made to Phosphoinositides and Phosphatidic acid. This work is supported by grant NSF DMR-0748475.

Solid-state reaction synthesis for mixed-phase Eu3+-doped bismuth molybdate and its luminescence properties

NASA Astrophysics Data System (ADS)

Liang, Danyang; Ding, Yu; Wang, Nan; Cai, Xiaomeng; Li, Jia; Han, Linyu; Wang, Shiqi; Han, Yuanyuan; Jia, Guang; Wang, Liyong

2017-09-01

A method for mixed-phase bismuth molybdate doped with Eu3+ ions was developed by solid-state reaction assisting with polyvinyl alcohol (PVA). The results of powder X-ray diffraction showed a mixed-phase structure and the microscopical characterization technology revealed the formation process with the addition of PVA. As a structure inducer, the PVA molecules played a vital role in the formation of phase structure. The as-obtained Eu3+-doped bismuth molybdates were also characterized by using different spectroscopic techniques including FTIR and photoluminescence (PL). The results show that doping concentration, PVA addition and calcination temperature affect photoluminescence properties remarkably.

Device for passive flow control around vertical axis marine turbine

NASA Astrophysics Data System (ADS)

Coşoiu, C. I.; Georgescu, A. M.; Degeratu, M.; Haşegan, L.; Hlevca, D.

2012-11-01

The power supplied by a turbine with the rotor placed in a free stream flow may be increased by augmenting the velocity in the rotor area. The energy of the free flow is dispersed and it may be concentrated by placing a profiled structure around the bare turbine in order to concentrate more energy in the rotor zone. At the Aerodynamic and Wind Engineering Laboratory (LAIV) of the Technical University of Civil Engineering of Bucharest (UTCB) it was developed a concentrating housing to be used for hydro or aeolian horizontal axis wind turbines, in order to increase the available energy in the active section of turbine rotor. The shape of the concentrating housing results by superposing several aero/hydro dynamic effects, the most important being the one generated by the passive flow control devices that were included in the housing structure. Those concentrating housings may be also adapted for hydro or aeolian turbines with vertical axis. The present paper details the numerical research effectuated at the LAIV to determine the performances of a vertical axis marine turbine equipped with such a concentrating device, in order to increase the energy quantity extracted from the main flow. The turbine is a Darrieus type one with three vertical straight blades, symmetric with respect to the axis of rotation, generated using a NACA4518 airfoil. The global performances of the turbine equipped with the concentrating housing were compared to the same characteristics of the bare turbine. In order to validate the numerical approach used in this paper, test cases from the literature resulting from experimental and numerical simulations for similar situations, were used.

The concentration of no toxicologic concern (CoNTC) and airborne mycotoxins.

PubMed

Hardin, Bryan D; Robbins, Coreen A; Fallah, Payam; Kelman, Bruce J

2009-01-01

The threshold of toxicologic concern (TTC) concept was developed as a method to identify a chemical intake level that is predicted to be without adverse human health effects assuming daily intake over the course of a 70-yr life span. The TTC values are based on known structure-activity relationships and do not require chemical-specific toxicity data. This allows safety assessment (or prioritization for testing) of chemicals with known molecular structure but little or no toxicity data. Recently, the TTC concept was extended to inhaled substances by converting a TTC expressed in micrograms per person per day to an airborne concentration (ng/m(3)), making allowance for intake by routes in addition to inhalation and implicitly assuming 100% bioavailability of inhaled toxicants. The resulting concentration of no toxicologic concern (CoNTC), 30 ng/m(3), represents a generic airborne concentration that is expected to pose no hazard to humans exposed continuously throughout a 70-yr lifetime. Published data on the levels of mycotoxins in agricultural dusts or in fungal spores, along with measured levels of airborne mycotoxins, spores, or dust in various environments, were used to identify conditions under which mycotoxin exposures might reach the CoNTC. Data demonstrate that airborne concentrations of dusts and mold spores sometimes encountered in agricultural environments have the potential to produce mycotoxin concentrations greater than the CoNTC. On the other hand, these data suggest that common exposures to mycotoxins from airborne molds in daily life, including in the built indoor environment, are below the concentration of no toxicologic concern.

Current advancements and challenges in soil-root interactions modelling

NASA Astrophysics Data System (ADS)

Schnepf, Andrea; Huber, Katrin; Abesha, Betiglu; Meunier, Felicien; Leitner, Daniel; Roose, Tiina; Javaux, Mathieu; Vanderborght, Jan; Vereecken, Harry

2015-04-01

Roots change their surrounding soil chemically, physically and biologically. This includes changes in soil moisture and solute concentration, the exudation of organic substances into the rhizosphere, increased growth of soil microorganisms, or changes in soil structure. The fate of water and solutes in the root zone is highly determined by these root-soil interactions. Mathematical models of soil-root systems in combination with non-invasive techniques able to characterize root systems are a promising tool to understand and predict the behaviour of water and solutes in the root zone. With respect to different fields of applications, predictive mathematical models can contribute to the solution of optimal control problems in plant recourse efficiency. This may result in significant gains in productivity, efficiency and environmental sustainability in various land use activities. Major challenges include the coupling of model parameters of the relevant processes with the surrounding environment such as temperature, nutrient concentration or soil water content. A further challenge is the mathematical description of the different spatial and temporal scales involved. This includes in particular the branched structures formed by root systems or the external mycelium of mycorrhizal fungi. Here, reducing complexity as well as bridging between spatial scales is required. Furthermore, the combination of experimental and mathematical techniques may advance the field enormously. Here, the use of root system, soil and rhizosphere models is presented through a number of modelling case studies, including image based modelling of phosphate uptake by a root with hairs, model-based optimization of root architecture for phosphate uptake from soil, upscaling of rhizosphere models, modelling root growth in structured soil, and the effect of root hydraulic architecture on plant water uptake efficiency and drought resistance.

Current Advancements and Challenges in Soil-Root Interactions Modelling

NASA Astrophysics Data System (ADS)

Schnepf, A.; Huber, K.; Abesha, B.; Meunier, F.; Leitner, D.; Roose, T.; Javaux, M.; Vanderborght, J.; Vereecken, H.

2014-12-01

Roots change their surrounding soil chemically, physically and biologically. This includes changes in soil moisture and solute concentration, the exudation of organic substances into the rhizosphere, increased growth of soil microorganisms, or changes in soil structure. The fate of water and solutes in the root zone is highly determined by these root-soil interactions. Mathematical models of soil-root systems in combination with non-invasive techniques able to characterize root systems are a promising tool to understand and predict the behaviour of water and solutes in the root zone. With respect to different fields of applications, predictive mathematical models can contribute to the solution of optimal control problems in plant recourse efficiency. This may result in significant gains in productivity, efficiency and environmental sustainability in various land use activities. Major challenges include the coupling of model parameters of the relevant processes with the surrounding environment such as temperature, nutrient concentration or soil water content. A further challenge is the mathematical description of the different spatial and temporal scales involved. This includes in particular the branched structures formed by root systems or the external mycelium of mycorrhizal fungi. Here, reducing complexity as well as bridging between spatial scales is required. Furthermore, the combination of experimental and mathematical techniques may advance the field enormously. Here, the use of root system, soil and rhizosphere models is presented through a number of modelling case studies, including image based modelling of phosphate uptake by a root with hairs, model-based optimization of root architecture for phosphate uptake from soil, upscaling of rhizosphere models, modelling root growth in structured soil, and the effect of root hydraulic architecture on plant water uptake efficiency and drought resistance.

Removal of high concentration p-nitrophenol in aqueous solution by zero valent iron with ultrasonic irradiation (US-ZVI).

PubMed

Lai, Bo; Chen, Zhaoyu; Zhou, Yuexi; Yang, Ping; Wang, Juling; Chen, Zhiqiang

2013-04-15

In this study, the US-ZVI system was used to produce the strong reductants including H and nascent Fe(2+) ions to eliminate the toxicity of the high concentration p-nitrophenol (PNP) wastewater. The effect of the reactor structure, initial pH, ZVI dosage, ultrasonic power and initial PNP concentration on the removal efficiency of PNP from water was investigated intensively. The results show that a higher removal rate can be obtained by using a conical structure reactor, and the lower initial pH can aid the acceleration of PNP removal rate by using US-ZVI system. Furthermore, the removal efficiencies of PNP increased obviously with the increase of initial ZVI concentration from 0 to 15 gL(-1). Also, the treatment capacity of ZVI was enhanced remarkably by the ultrasonic irradiation, and the US-ZVI system can maintain high treatment efficiency for the high concentration PNP wastewater (500-10,000 mgL(-1)). Meanwhile, the high removal efficiency of PNP was mainly resulted from the synergistic reaction of ZVI and US. At last, the main degradation product (i.e., p-aminophenol) was detected by gas chromatography-mass spectrum (GC-MS). Thus, the reaction pathway of PNP in the US-ZVI system is proposed as a reducing process by the H and nascent Fe(2+) ions. Copyright © 2013 Elsevier B.V. All rights reserved.

The cubicon method for concentrating membrane proteins in the cubic mesophase.

PubMed

Ma, Pikyee; Weichert, Dietmar; Aleksandrov, Luba A; Jensen, Timothy J; Riordan, John R; Liu, Xiangyu; Kobilka, Brian K; Caffrey, Martin

2017-09-01

The lipid cubic phase (in meso) method is an important approach for generating crystals and high-resolution X-ray structures of integral membrane proteins. However, as a consequence of instability, it can be impossible-using traditional methods-to concentrate certain membrane proteins and complexes to values suitable for in meso crystallization and structure determination. The cubicon method described here exploits the amphiphilic nature of membrane proteins and their natural tendency to partition preferentially into lipid bilayers from aqueous solution. Using several rounds of reconstitution, the protein concentration in the bilayer of the cubic mesophase can be ramped up stepwise from less than a milligram per milliliter to tens of milligrams per milliliter for crystallogenesis. The general applicability of the method is demonstrated with five integral membrane proteins: the β 2 -adrenergic G protein-coupled receptor (β 2 AR), the peptide transporter (PepT St ), diacylglycerol kinase (DgkA), the alginate transporter (AlgE) and the cystic fibrosis transmembrane conductance regulator (CFTR). In the cases of β 2 AR, PepT St , DgkA and AlgE, an effective 20- to 45-fold concentration was realized, resulting in a protein-laden mesophase that allowed the formation of crystals using the in meso method and structure determination to resolutions ranging from 2.4 Å to 3.2 Å. In addition to opening up in meso crystallization to a broader range of integral membrane protein targets, the cubicon method should find application in situations that require membrane protein reconstitution in a lipid bilayer at high concentrations. These applications include functional and biophysical characterization studies for ligand screening, drug delivery, antibody production and protein complex formation. A typical cubicon experiment can be completed in 3-5 h.

COMPARISON OF FUNCTIONAL ACTIVITIES ON STRUCTURAL CHANGES OF THE INFERIOR PATELLAR POLE

PubMed Central

Wallmann, Harvey; Stalcup, Patrick; DiTommaso, Katie

2017-01-01

Background It is well known that eccentric and concentric exercise produce varied amounts of stress on the connective tissues. Diagnostic ultrasound has been used to measure these structural changes by observing fascicle length, angle, and thickness; however, there is a lack of evidence comparing the structural changes as it relates to eccentric, concentric, and stretching protocols. Purpose The purpose of this study was to compare the acute effects of static stretching, eccentric, concentric, and a combination of eccentric/concentric exercises on structural changes of the muscle tendon unit at the inferior patellar pole utilizing the diagnostic ultrasound. Study Design A repeated measures 2 × 4 within factorial study design with repeated measures on both factors was used to determine the differences in patellar tendon thickness within and between groups. Methods Forty-seven healthy subjects were screened for any lower extremity deficits or orthopaedic pathology. Forty-four (N=44) subjects completed all four protocols; the attrition was due to injuries to the lower extremity, occurring unrelated to the study. A baseline measurement of the anterior inferior patellar tendon was performed with the diagnostic ultrasound prior to each participant completing one of the four interventions per week over a four-week period. Interventions completed by each participant included static stretching, concentric, eccentric, and combined concentric and eccentric exercises. Immediately following each intervention, a post-intervention inferior patellar tendon measurement was recorded using the diagnostic ultrasound. Results Significant differences in anterior to posterior tendon thickness of the inferior patellar tendon were observed between pre (4.983 ± 0.041mm) and post (5.198 ± 0.055mm) measurements (p<0.0005) for the main effect of time. However, no differences in tendon thickness were noted comparing each intervention to one another (p=0.351). Conclusion Differences in tendon thickness were noted acutely for pre- to post measurements across all interventions. Further research is needed to determine if differences in tendon thickness exist with a longer duration of exercise over time and with different types of intervention. PMID:29234561

Changes in the structure and function of soil ecosystems in soils contaminated with heavy metals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuperman, R.; Parmelee, R.; Carreiro, M.

1995-09-01

The structure and function of soil communities in an area with a wide range of concentrations of heavy metals was studied in portions of the U.S. Army`s Aberdeen Proving Ground, Maryland. The study included survey of soil macro- and microinvertebrate communities, soil microorganisms, enzyme activities and the rates of nutrient dynamics in soil. Soil macroinvertebrate communities showed significant reductions in the adundance of several taxonomic and functional groups in contaminated areas. The total numbers of nematodes and numbers of fungivore, bacterivore and omnivore-predator nematodes were lower in the more contaminated areas. The numbers of active bacteria and fungi were lowermore » in areas of soil contamination. Significant reduction in the activities of all enzymes closely paralleled the increase in heavy metal concentrations. Ten-to-fifty fold reductions in enzyme activities were observed as heavy metal concentrations increased. These results suggest that soil contamination with heavy metals may have detrimental effects on soil biota and the rates of organic matter degradation and subsequent release of nutrients to aboveground communities in the area.« less

Changes in the structure and function of soil ecosystems in soils contaminated with heavy metals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuperman, R.; Parmelee, R.; Carreiro, M.

1995-06-01

The structure and function of soil communities in an area with a wide range of concentrations of heavy metals was studied in portions of the U.S. Army`s Aberdeen Proving Ground, Maryland. The study included survey of soil macro- and microinvertebrate communities, soil microorganisms, enzyme activities and the rates of nutrient dynamics in soil. Soil macroinvertebrate communities showed significant reductions in the abundance of several taxonomic and functional groups in contaminated areas. The total numbers of nematodes and numbers of fungivore, bacterivore and omnivore-predator nematodes were lower in the more contaminated areas. The numbers of active bacteria and fungi were lowermore » in areas of soil contamination. Significant reduction in the activities of all enzymes closely paralleled the increase in heavy metal concentrations. Ten-to-fifty fold reductions in enzyme activities were observed as heavy metal concentrations increased. These results suggest that soil contamination with heavy metals may have detrimental effects on soil biota and the rates of organic matter degradation and subsequent release of nutrients to aboveground communities in the area.« less

Machine-Learned Data Structures of Lipid Marker Serum Concentrations in Multiple Sclerosis Patients Differ from Those in Healthy Subjects.

PubMed

Lötsch, Jörn; Thrun, Michael; Lerch, Florian; Brunkhorst, Robert; Schiffmann, Susanne; Thomas, Dominique; Tegder, Irmgard; Geisslinger, Gerd; Ultsch, Alfred

2017-06-07

Lipid metabolism has been suggested to be a major pathophysiological mechanism of multiple sclerosis (MS). With the increasing knowledge about lipid signaling, acquired data become increasingly complex making bioinformatics necessary in lipid research. We used unsupervised machine-learning to analyze lipid marker serum concentrations, pursuing the hypothesis that for the most relevant markers the emerging data structures will coincide with the diagnosis of MS. Machine learning was implemented as emergent self-organizing feature maps (ESOM) combined with the U*-matrix visualization technique. The data space consisted of serum concentrations of three main classes of lipid markers comprising eicosanoids ( d = 11 markers), ceramides ( d = 10), and lyosophosphatidic acids ( d = 6). They were analyzed in cohorts of MS patients ( n = 102) and healthy subjects ( n = 301). Clear data structures in the high-dimensional data space were observed in eicosanoid and ceramides serum concentrations whereas no clear structure could be found in lysophosphatidic acid concentrations. With ceramide concentrations, the structures that had emerged from unsupervised machine-learning almost completely overlapped with the known grouping of MS patients versus healthy subjects. This was only partly provided by eicosanoid serum concentrations. Thus, unsupervised machine-learning identified distinct data structures of bioactive lipid serum concentrations. These structures could be superimposed with the known grouping of MS patients versus healthy subjects, which was almost completely possible with ceramides. Therefore, based on the present analysis, ceramides are first-line candidates for further exploration as drug-gable targets or biomarkers in MS.

Structural properties of fracture haematoma: current status and future clinical implications.

PubMed

Wang, Xin; Friis, Thor; Glatt, Vaida; Crawford, Ross; Xiao, Yin

2017-10-01

Blood clots (haematomas) that form immediately following a bone fracture have been shown to be vital for the subsequent healing process. During the clotting process, a number of factors can influence the fibrin clot structure, such as fibrin polymerization, growth factor binding, cellular infiltration (including platelet retraction), protein concentrations and cytokines. The modulation of the fibrin clot structure within the fracture site has important clinical implications and could result in the development of multifunctional scaffolds that mimic the natural structure of a haematoma. Artificial haematoma structures such as these can be created from the patient's own blood and can therefore act as an ideal bone defect filling material for potential clinical application to accelerate bone regeneration. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Effect of europium ion concentration on the structural and photoluminescence properties of novel Li2BaZrO4: Eu3+ nanocrystals

NASA Astrophysics Data System (ADS)

Ahemen, I.; Dejene, F. B.; Kroon, R. E.; Swart, H. C.

2017-12-01

This work reports the influence of Eu3+ ion concentration on the structure and photoluminescence properties of Li2BaZrO4 nanocrystals including its intrinsic quantum efficiency (IQE). Chemical bath method was employed in the synthesis procedure. X-ray diffraction results showed tetragonal phase for Eu3+ ion concentration in the range 1 and 7 mol% and cubic phase at 8 mol%. The presence of barium oxide (BaO) was confirmed from selected area electron diffraction (SAED). The excitation spectra for these phosphors consisted of broad charge transfer (CT) bands due to the combination of Zr4+ - O2- and Eu3+-O2- charge transfer states. Superimposed on the CT band were direct excitation levels of Eu3+ and Ba2+ ions, in the range 320-450 nm. At high Eu3+ ions concentrations, the intensities of CT bands decreased because some of the ions were coordinated with Ba2+ ions. Photoluminescence emissions for all the doped samples at room temperature appeared to be entirely from intraconfigurational Eu3+ emissions and depended both on the site symmetry as well as the ion concentration. The quadrupole-quadrupole multipolar process was found to be solely responsible for the luminescence quenching. The intensity parameters (Ω2 ,Ω4), asymmetry ratio, R0 and the average decay lifetime of the nanocrystals showed dependence on concentration. High internal quantum efficiency (IQE) values were obtained at low Eu3+ ion concentrations, but efficiency decreased with increasing ion concentration. The CIE coordinates values were comparable to existing red phosphors and in combination with the high IQE make this phosphor a good candidate for red light emitting applications.

Solar Thermal Power Systems parabolic dish project

NASA Technical Reports Server (NTRS)

Truscello, V. C.

1981-01-01

The status of the Solar Thermal Power Systems Project for FY 1980 is summarized. Included is: a discussion of the project's goals, program structure, and progress in parabolic dish technology. Analyses and test results of concentrators, receivers, and power converters are discussed. Progress toward the objectives of technology feasibility, technology readiness, system feasibility, and system readiness are covered.

Theoretical studies on band structure and optical gain of GaInAsN/GaAs /GaAs cylindrical quantum dot

NASA Astrophysics Data System (ADS)

Mal, Indranil; Samajdar, Dip Prakash; John Peter, A.

2018-07-01

Electronic band structure, effective masses, band offsets and optical gain of Ga0.661In0.339N0.0554As0.9446/GaAs quantum dot systems are investigated using 10 band k·p Hamiltonian for various nitrogen and indium concentrations. The calculations include the effects of strain generated due to the lattice mismatch and the effective band gap of GaInAsN/GaAs heterostructures. The variation of conduction band, light hole and heavy hole band offsets with indium and nitrogen compositions in the alloy are obtained. The band structure of Ga0.661In0.339N0.0554As0.9446/GaAs quantum dot is found in the crystal directions Δ (100) and Λ (111) using 10 band k·p Hamiltonian. The optical gain of the cylindrical quantum dot structures as functions of surface carrier concentration and the dot radius is investigated. Our results show that the tensile strain of 1.34% generates a band gap of 0.59 eV and the compressive strain of 2.2% produces a band gap of 1.28 eV and the introduction of N atoms has no effect on the spin orbit split off band. The variation of optical gain with the dot size and the carrier concentration indicates that the optical gain increases with the decrease in the radius of the quantum dot. The results may be useful for the potential applications in optical devices.

Preoperative urinary tract obstruction in scoliosis patients.

PubMed

Suzuki, Shigeru; Kotani, Toshiaki; Mori, Kazuetsu; Kawamura, Ken; Ohtake, Akira

2017-01-01

While the association between scoliosis and cardiac and respiratory function impairments has been well characterized in clinical practice and research, the potential effect of scoliosis on urinary tract structure and renal function has received little attention. Therefore, the purpose of this study was to evaluate the preoperative clinical characteristics of urinary tract structure and renal function in pediatric patients with idiopathic scoliosis, using a combination of blood tests, urinalysis, and imaging. Preoperative measures of urinary tract structure and renal function were obtained for 16 patients, 13-17 years old, scheduled for corrective surgery for idiopathic scoliosis. Preoperative assessment included blood test and urinalysis, combined with structural imaging on ultrasound (US), magnetic resonance imaging (MRI), magnetic resonance urography (MRU), and radioisotope tracing (RI), using technetium-99 m mercaptoacetyltriglycine ( 99m Tc-MAG3). Differences in blood and urine tests between patients with and without urinary tract obstruction (UTO) were evaluated for significance using Mann-Whitney U test. For all 16 patients, blood tests and MRU were within normal limits. Dilatation of the renal pelvis was identified on US in eight patients (50.0%). UTO was identified on RI in six patients (37.5%). UTO was associated with elevated β2-microglobulin concentration. Urinary β2-microglobulin concentration >0.7 μg/mg Cr differentiated patients with UTO from those without UTO, with a sensitivity of 100% and specificity of 70%. β2-Microglobulin concentration may be a useful marker to screen for asymptomatic UTO in patients with idiopathic scoliosis. © 2016 Japan Pediatric Society.

Fatigue Analysis of the Piston Rod in a Kaplan Turbine Based on Crack Propagation under Unsteady Hydraulic Loads

NASA Astrophysics Data System (ADS)

Liu, X.; Y Luo, Y.; Wang, Z. W.

2014-03-01

As an important component of the blade-control system in Kaplan turbines, piston rods are subjected to fluctuating forces transferred by the turbines blades from hydraulic pressure oscillations. Damage due to unsteady hydraulic loads might generate unexpected down time and high repair cost. In one running hydropower plant, the fracture failure of the piston rod was found twice at the same location. With the transient dynamic analysis, the retainer ring structure of the piston rod existed a relative high stress concentration. This predicted position of the stress concentration agreed well with the actual fracture position in the plant. However, the local strain approach was not able to explain why this position broke frequently. Since traditional structural fatigue analyses use a local stress strain approach to assess structural integrity, do not consider the effect of flaws which can significantly degrade structural life. Using linear elastic fracture mechanism (LEFM) approaches that include the effect of flaws is becoming common practice in many industries. In this research, a case involving a small semi-ellipse crack was taken into account at the stress concentration area, crack growth progress was calculated by FEM. The relationship between crack length and remaining life was obtained. The crack propagation path approximately agreed with the actual fracture section. The results showed that presence of the crack had significantly changed the local stress and strain distributions of the piston rod compared with non-flaw assumption.

Effect of Concentration on the Interfacial and Bulk Structure of Ionic Liquids in Aqueous Solution.

PubMed

Cheng, H-W; Weiss, H; Stock, P; Chen, Y-J; Reinecke, C R; Dienemann, J-N; Mezger, M; Valtiner, M

2018-02-27

Bio and aqueous applications of ionic liquids (IL) such as catalysis in micelles formed in aqueous IL solutions or extraction of chemicals from biologic materials rely on surface-active and self-assembly properties of ILs. Here, we discuss qualitative relations of the interfacial and bulk structuring of a water-soluble surface-active IL ([C 8 MIm][Cl]) on chemically controlled surfaces over a wide range of water concentrations using both force probe and X-ray scattering experiments. Our data indicate that IL structuring evolves from surfactant-like surface adsorption at low IL concentrations, to micellar bulk structure adsorption above the critical micelle concentration, to planar bilayer formation in ILs with <1 wt % of water and at high charging of the surface. Interfacial structuring is controlled by mesoscopic bulk structuring at high water concentrations. Surface chemistry and surface charges decisively steer interfacial ordering of ions if the water concentration is low and/or the surface charge is high. We also demonstrate that controlling the interfacial forces by using self-assembled monolayer chemistry allows tuning of interfacial structures. Both the ratio of the head group size to the hydrophobic tail volume as well as the surface charging trigger the bulk structure and offer a tool for predicting interfacial structures. Based on the applied techniques and analyses, a qualitative prediction of molecular layering of ILs in aqueous systems is possible.

AB INITIO Molecular Dynamics Simulations on Local Structure and Electronic Properties in Liquid MgxBi1-x Alloys

NASA Astrophysics Data System (ADS)

Hao, Qing-Hai; You, Yu-Wei; Kong, Xiang-Shan; Liu, C. S.

2013-03-01

The microscopic structure and dynamics of liquid MgxBi1-x(x = 0.5, 0.6, 0.7) alloys together with pure liquid Mg and Bi metals were investigated by means of ab initio molecular dynamics simulations. We present results of structure properties including pair correlation function, structural factor, bond-angle distribution function and bond order parameter, and their composition dependence. The dynamical and electronic properties have also been studied. The structure factor and pair correlation function are in agreement with the available experimental data. The calculated bond-angle distribution function and bond order parameter suggest that the stoichiometric composition Mg3Bi2 exhibits a different local structure order compared with other concentrations, which help us understand the appearance of the minimum electronic conductivity at this composition observed in previous experiments.

The Geographic Concentration of Enterprise in Developing Countries

PubMed Central

Felkner, John S.; Townsend, Robert M.

2011-01-01

A nation’s economic geography can have an enormous impact on its development. In Thailand, we show that a high concentration of enterprise in an area predicts high subsequent growth in and around that area. We also find spatially contiguous convergence of enterprise with stagnant areas left behind. Exogenous physiographic conditions are correlated with enterprise location and growth. We fit a structural, micro-founded model of occupation transitions with fine-tuned geographic capabilities to village data and replicate these salient facts. Key elements of the model include costs, credit constraints on occupation choice, and spatially varying expansion of financial service providers. PMID:22844158

Exact travelling wave solutions for a diffusion-convection equation in two and three spatial dimensions

NASA Astrophysics Data System (ADS)

Elwakil, S. A.; El-Labany, S. K.; Zahran, M. A.; Sabry, R.

2004-04-01

The modified extended tanh-function method were applied to the general class of nonlinear diffusion-convection equations where the concentration-dependent diffusivity, D( u), was taken to be a constant while the concentration-dependent hydraulic conductivity, K( u) were taken to be in a power law. The obtained solutions include rational-type, triangular-type, singular-type, and solitary wave solutions. In fact, the profile of the obtained solitary wave solutions resemble the characteristics of a shock-wave like structure for an arbitrary m (where m>1 is the power of the nonlinear convection term).

Polyaspartic Acid Concentration Controls the Rate of Calcium Phosphate Nanorod Formation in High Concentration Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krogstad, Daniel V.; Wang, Dongbo; Lin-Gibson, Sheng

Polyelectrolytes are known to greatly affect calcium phosphate (CaP) mineralization. The reaction kinetics as well as the CaP phase, morphology and aggregation state depend on the relative concentrations of the polyelectrolyte and the inorganic ions in a complex, nonlinear manner. This study examines the structural evolution and kinetics of polyaspartic acid (pAsp) directed CaP mineralization at high concentrations of polyelectrolytes, calcium, and total phosphate (19–30 mg/mL pAsp, 50–100 mM Ca2+, Ca/P = 2). Using a novel combination of characterization techniques including cryogenic transmission electron microscopy (cryo-TEM), spectrophotometry, X-ray total scattering pair distribution function analysis, and attenuated total reflectance Fourier transformmore » infrared spectroscopy (ATR-FTIR), it was determined that the CaP mineralization occurred over four transition steps. The steps include the formation of aggregates of pAsp stabilized CaP spherical nanoparticles (sNP), crystallization of sNP, oriented attachment of the sNP into nanorods, and further crystallization of the nanorods. The intermediate aggregate sizes and the reaction kinetics were found to be highly polymer concentration dependent while the sizes of the particles were not concentration dependent. This study demonstrates the complex role of pAsp in controlling the mechanism as well as the kinetics of CaP mineralization.« less

Effect of precursors condition on the structural morphology of synthesized GaN

NASA Astrophysics Data System (ADS)

Muzammil, P.; Basha, S. Munawar; Muhammad, G. Shakil

2018-05-01

GaN nanostructures were synthesized using different mole concentration of precursor composing of gallium nitrate and PVP by sol-gel method. The structural analysis using X-ray diffraction shows the wurtzite form of GaN nanostructure, also it observed that the concentration of precursor play a vital role in structural quality as FWHM increase for higher concentration. From the SEM image it observed that for 0.25 and 0.5 M concentration the honey bee and nanorod structure were obtained. The micro-Raman analysis shows a strong E2H peak of GaN nanostructure.

Structural stability of DNA origami nanostructures in the presence of chaotropic agents.

PubMed

Ramakrishnan, Saminathan; Krainer, Georg; Grundmeier, Guido; Schlierf, Michael; Keller, Adrian

2016-05-21

DNA origami represent powerful platforms for single-molecule investigations of biomolecular processes. The required structural integrity of the DNA origami may, however, pose significant limitations regarding their applicability, for instance in protein folding studies that require strongly denaturing conditions. Here, we therefore report a detailed study on the stability of 2D DNA origami triangles in the presence of the strong chaotropic denaturing agents urea and guanidinium chloride (GdmCl) and its dependence on concentration and temperature. At room temperature, the DNA origami triangles are stable up to at least 24 h in both denaturants at concentrations as high as 6 M. At elevated temperatures, however, structural stability is governed by variations in the melting temperature of the individual staple strands. Therefore, the global melting temperature of the DNA origami does not represent an accurate measure of their structural stability. Although GdmCl has a stronger effect on the global melting temperature, its attack results in less structural damage than observed for urea under equivalent conditions. This enhanced structural stability most likely originates from the ionic nature of GdmCl. By rational design of the arrangement and lengths of the individual staple strands used for the folding of a particular shape, however, the structural stability of DNA origami may be enhanced even further to meet individual experimental requirements. Overall, their high stability renders DNA origami promising platforms for biomolecular studies in the presence of chaotropic agents, including single-molecule protein folding or structural switching.

USAXS analysis of concentration-dependent self-assembling of polymer-brush-modified nanoparticles in ionic liquid: [I] concentrated-brush regime

NASA Astrophysics Data System (ADS)

Nakanishi, Yohei; Ishige, Ryohei; Ogawa, Hiroki; Sakakibara, Keita; Ohno, Kohji; Morinaga, Takashi; Sato, Takaya; Kanaya, Toshiji; Tsujii, Yoshinobu

2018-03-01

Using ultra-small angle X-ray scattering (USAXS), we analyzed the higher-order structures of nanoparticles with a concentrated brush of an ionic liquid (IL)-type polymer (concentrated-polymer-brush-modified silica particle; PSiP) in an IL and the structure of the swollen shell layer of PSiP. Homogeneous mixtures of PSiP and IL were successfully prepared by the solvent-casting method involving the slow evaporation of a volatile solvent, which enabled a systematic study over an exceptionally wide range of compositions. Different diffraction patterns as a function of PSiP concentration were observed in the USAXS images of the mixtures. At suitably low PSiP concentrations, the USAXS intensity profile was analyzed using the Percus-Yevick model by matching the contrast between the shell layer and IL, and the swollen structure of the shell and "effective diameter" of the PSiP were evaluated. This result confirms that under sufficiently low pressures below and near the liquid/crystal-threshold concentration, the studied PSiP can be well described using the "hard sphere" model in colloidal science. Above the threshold concentration, the PSiP forms higher-order structures. The analysis of diffraction patterns revealed structural changes from disorder to random hexagonal-closed-packing and then face-centered-cubic as the PSiP concentration increased. These results are discussed in terms of thermodynamically stable "hard" and/or "semi-soft" colloidal crystals, wherein the swollen layer of the concentrated polymer brush and its structure play an important role.

Development of structure in natural silk spinning and poly(vinyl alcohol) hydrogel formation

NASA Astrophysics Data System (ADS)

Willcox, Patricia Jeanene

This research involves the characterization of structure and structure formation in aqueous systems. Particularly, these studies investigate the effect of various processing variables on the structure formation that occurs upon conversion from aqueous solution to fiber or hydrogel. The two processes studied include natural silk fiber spinning and physical gelation of poly(vinyl alcohol), PVOH, in water. The techniques employed combine cryogenic technology for sample preparation and direct observation by transmission electron microscopy with electron diffraction, atomic force microscopy, optical rheometry, X-ray scattering and optical microscopy. In order to explore the full range of structure formation in natural silk spinning, studies are conducted in vivo and in vitro. In vivo structural investigations are accomplished through the cryogenic quenching and subsequent microtoming of live silk-spinning animals, Nephila clavipes (spider) and Bombyx mori (silkworm). Observations made using transmission electron microscopy, electron diffraction and atomic force microscopy indicate a cholesteric liquid crystalline mesophase of aqueous silk fibroin in both species. The mechanism of structure formation in solution is studied in vitro using optical rheometry on aqueous solutions made from regenerated Bombyx mori cocoon silk. Concentrated solutions exhibit birefringence under flow, with a wormlike conformation of the silk molecules in concentrated salt solution. Changes in salt concentration and pH of the aqueous silk solutions result in differing degrees of alignment and aggregation. These results suggest that structural control in the natural silk spinning process is accomplished by chemical manipulation of the electrostatic interactions and hydrogen bonding between chains. Application of cryogenic methods in transmission electron microscopy also provides a unique look at hydration-dependent structures in gels of poly(vinyl alcohol) produced by freeze-thaw processing. Morphologies ranging from circular pores to fibrillar networks are observed in gels formed from aqueous PVOH solutions subjected to cycles of freezing and thawing. These morphologies can be directly associated with the progressive nature of the mechanism of gelation as it proceeds from liquid-liquid phase separation to crystallization with increased cycling. A comparison of the structures produced by cycling and by aging suggests that there is a similarity in structural changes, but a superposition of the effects of cycling and aging is not possible.

The Evolving Market Structure of the U.S. Residential Solar PV Installation Industry, 2000-2016

DOE Office of Scientific and Technical Information (OSTI.GOV)

OShaughnessy, Eric J.

This study uses data on over 900,000 solar PV installations to summarize the evolving market structure of the U.S. residential solar PV installation industry. Over 8,000 companies have installed residential PV systems in the United States. The vast majority of these installers are small local companies. At the same time, a subset of national-scale high-volume PV installation companies hold high market shares. This study examines the factors behind these trends in market concentration, including the role of customer financing options.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schaeffel, J.A.; Mullinix, B.R.; Ranson, W.F.

An experimental technique to simulate and evaluate the effects of high concentrations of x-rays resulting from a nuclear detonation on missile structures is presented. Data from 34 tests are included to demonstrate the technique. The effects of variations in the foil thickness, capacitor voltage, and plate thickness on the total impulse and maximum strain in the structure were determined. The experimental technique utilizes a high energy capacitor discharge unit to explode an aluminum foil on the surface of the structure. The structural response is evaluated by optical methods using the grid slope deflection method. The fringe patterns were recorded usingmore » a high-speed framing camera. The data were digitized using an optical comparator with an x-y table. The analysis was performed on a CDC 6600 computer.« less

Quantitative methods for structural characterization of proteins based on deep UV resonance Raman spectroscopy.

PubMed

Shashilov, Victor A; Sikirzhytski, Vitali; Popova, Ludmila A; Lednev, Igor K

2010-09-01

Here we report on novel quantitative approaches for protein structural characterization using deep UV resonance Raman (DUVRR) spectroscopy. Specifically, we propose a new method combining hydrogen-deuterium (HD) exchange and Bayesian source separation for extracting the DUVRR signatures of various structural elements of aggregated proteins including the cross-beta core and unordered parts of amyloid fibrils. The proposed method is demonstrated using the set of DUVRR spectra of hen egg white lysozyme acquired at various stages of HD exchange. Prior information about the concentration matrix and the spectral features of the individual components was incorporated into the Bayesian equation to eliminate the ill-conditioning of the problem caused by 100% correlation of the concentration profiles of protonated and deuterated species. Secondary structure fractions obtained by partial least squares (PLS) and least squares support vector machines (LS-SVMs) were used as the initial guess for the Bayessian source separation. Advantages of the PLS and LS-SVMs methods over the classical least squares calibration (CLSC) are discussed and illustrated using the DUVRR data of the prion protein in its native and aggregated forms. Copyright (c) 2010 Elsevier Inc. All rights reserved.

In-Space Structural Validation Plan for a Stretched-Lens Solar Array Flight Experiment

NASA Technical Reports Server (NTRS)

Pappa, Richard S.; Woods-Vedeler, Jessica A.; Jones, Thomas W.

2001-01-01

This paper summarizes in-space structural validation plans for a proposed Space Shuttle-based flight experiment. The test article is an innovative, lightweight solar array concept that uses pop-up, refractive stretched-lens concentrators to achieve a power/mass density of at least 175 W/kg, which is more than three times greater than current capabilities. The flight experiment will validate this new technology to retire the risk associated with its first use in space. The experiment includes structural diagnostic instrumentation to measure the deployment dynamics, static shape, and modes of vibration of the 8-meter-long solar array and several of its lenses. These data will be obtained by photogrammetry using the Shuttle payload-bay video cameras and miniature video cameras on the array. Six accelerometers are also included in the experiment to measure base excitations and small-amplitude tip motions.

Structure and dynamics in low-dimensional guest host solids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fischer, J.

1991-04-01

This progress report presents results from work during the period of June 1, 1990 through May 31st, 1991. Topics discussed include instrumentation, publications, and personnel. Work areas discussed include: pressure-induced transitions in Li- and Ag-TiS{sub 2}, hyper-dense superconducting GIC's, temperature-dependent x-ray structure of (CH){sub x} and (CH){sub 2{sup x}}:analogies to rotator phases in short-chain alkanes, trans-(CH){sub x} at high'' pressure, broken symmetries'' in polymer intercalation channel lattices, high-resolution study of conductivity and cell potential vs. concentration in K-doped (CH){sub x}, new'' doped (CH){sub x} phases: ternary compounds and amorphous'' intercalation compounds, and vibrational density states from inelastic neutron scattering. (JF).

Deployment, Foam Rigidization, and Structural Characterization of Inflatable Thin-Film Booms

NASA Technical Reports Server (NTRS)

Schnell, Andrew R.; Leigh, Larry M., Jr.; Tinker, Michael L.; McConnaughey, Paul R. (Technical Monitor)

2002-01-01

Detailed investigation of the construction, packaging/deployment, foam rigidization, and structural characterization of polyimide film inflatable booms is described. These structures have considerable potential for use in space with solar concentrators, solar sails, space power systems including solar arrays, and other future missions. Numerous thin-film booms or struts were successfully constructed, inflated, injected with foam, and rigidized. Both solid-section and annular test articles were fabricated, using Kapton polyimide film, various adhesives, Styrofoam end plugs, and polyurethane pressurized foam. Numerous inflation/deployment experiments were conducted and compared to computer simulations using the MSC/DYTRAN code. Finite element models were developed for several foam-rigidized struts and compared to model test results. Several problems encountered in the construction, deployment, and foam injection/rigidization process are described. Areas of difficulty included inadequate adhesive strength, cracking of the film arid leakage, excessive bending of the structure during deployment, problems with foam distribution and curing properties, and control of foam leakage following injection into the structure. Many of these problems were overcome in the course of the research.

Effect of white tea and xylitol on structure and properties of demineralized enamel and jawbone

NASA Astrophysics Data System (ADS)

Auerkari, EI; Kiranahayu, R.; Emerita, D.; Sumariningsih, P.; Sarita, D.; Adiwirya, MS; Suhartono, AW

2018-05-01

White tea and xylitol have been suggested as potential agents to combat dental caries and osteoporosis through enhanced remineralization. This investigation aimed to determine the effects of exposure to white tea with and without xylitol on the structure, composition and hardness of demineralized human dental enamel. For control, samples of untreated and demineralized enamel and samples of untreated rat jawbone were subjected to similar measurements. For demineralization, the enamel samples were immersed for two days at 50°C in an acetate solution (pH 4.0). All samples were then soaked for two weeks at 37°C in a solution containing three different concentrations of white tea, xylitol or both, and an optional addition of the remineralization ingredients including Ca, P and F. For enamel samples without preceding demineralization and without added remineralization ingredients, the results showed highest mean hardness after immersion in a solution containing both white tea and xylitol, practically independently of their applied concentration level. However, for demineralized enamel samples with added remineralization ingredients, the resulting mean hardness was also dependent on concentration of white tea and xylitol. With sufficient concentration, hardness was again higher for combined white tea and xylitol than for either of these used alone.

Electronic structure and shearing in nanolaminated ternary carbides

NASA Astrophysics Data System (ADS)

Music, Denis; Sun, Zhimei; Voevodin, Andrey A.; Schneider, Jochen M.

2006-07-01

We have studied shearing in M 2AlC phases (M=Sc,Y,La,Ti,Zr,Hf,V,Nb,Ta,Cr,Mo,W) using ab initio calculations. We propose that these phases can be classified into two groups based on the valence electron concentration induced changes in C 44. One group comprises M=V B and VIB, where the C 44 values are approximately 170 GPa and independent of the corresponding MC. The other group includes M=IIIB and IVB, where the C 44 shows a linear dependency with the corresponding MC. This may be understood based on the electronic structure: shear resistant bands are filled in M 2AlC phases with M=V B and VIB, while they are not completely filled when M=IIIB and IVB. This notion is also consistent with our stress-strain analysis. These valence electron concentration induced changes in shear behaviour were compared to previously published valence electron concentration induced changes in compression behaviour [Z. Sun, D. Music, R. Ahuja, S. Li, J.M. Schneider, Phys. Rev. B 70 (2004) 092102]. These classification proposals exhibit identical critical valence electron concentration values for the group boundary. However, the physical mechanisms are not identical: the classification proposal for the bulk modulus is based on MC-A coupling, while shearing is based on MC-MC coupling.

Antibiofilm potential of synthetic 2-amino-5-chlorobenzophenone Schiff bases and its confirmation through fluorescence microscopy.

PubMed

Arshia; Khan, Anum Khalid; Khan, Khalid Mohammed; Ahmed, Ayaz; Taha, Muhammad; Perveen, Shahnaz

2017-09-01

Antibacterial/antibiofilm potential of microwave-assisted synthetic thirty-three 2-amino-5-chloro benzophenone Schiff bases have been carried out against four bacterial strains i.e. Klebsiella pneumoniae, Proteus mirabilis, Staphylococcus aureus and Streptococcus mutans. Among them compounds 5, 6, 8, 9, 14, 16, 22, 24, 26, and 30-32 showed antibiofilm activities against isolates at less than 100 μg/ml concentrations. These compounds showed enhanced antibiofilm activity against S. aureus as compared to cefixime used as control. However, remaining compounds were found to be active but at higher concentration. Fluorescence microscopy has been employed for confirmation of antibiofilm results. The structures of all synthetic molecules have been characterized on the basis of spectroscopic techniques including 1 H NMR, 13 C NMR, EI-MS, HREI-MS, and IR spectroscopy and their structure-activity relationship have been established. Copyright © 2017 Elsevier Ltd. All rights reserved.

Controlling Thermodynamic Properties of Ferromagnetic Group-IV Graphene-Like Nanosheets by Dilute Charged Impurity

NASA Astrophysics Data System (ADS)

Yarmohammadi, Mohsen; Mirabbaszadeh, Kavoos

2017-05-01

Using the Kane-Mele Hamiltonian, Dirac theory and self-consistent Born approximation, we investigate the effect of dilute charged impurity on the electronic heat capacity and magnetic susceptibility of two-dimensional ferromagnetic honeycomb structure of group-IV elements including silicene, germanene and stanene within the Green’s function approach. We also find these quantities in the presence of applied external electric field. Our results show that the silicene (stanene) has the maximum (minimum) heat capacity and magnetic susceptibility at uniform electric fields. From the behavior of theses quantities, the band gap has been changed with impurity concentration, impurity scattering strength and electric field. The analysis on the impurity-dependent magnetic susceptibility curves shows a phase transition from ferromagnetic to paramagnetic and antiferromagnetic phases. Interestingly, electronic heat capacity increases (decreases) with impurity concentration in silicene (germanene and stanene) structure.

Molecular Mechanics of the Moisture Effect on Epoxy/Carbon Nanotube Nanocomposites.

PubMed

Tam, Lik-Ho; Wu, Chao

2017-10-13

The strong structural integrity of polymer nanocomposite is influenced in the moist environment; but the fundamental mechanism is unclear, including the basis for the interactions between the absorbed water molecules and the structure, which prevents us from predicting the durability of its applications across multiple scales. In this research, a molecular dynamics model of the epoxy/single-walled carbon nanotube (SWCNT) nanocomposite is constructed to explore the mechanism of the moisture effect, and an analysis of the molecular interactions is provided by focusing on the hydrogen bond (H-bond) network inside the nanocomposite structure. The simulations show that at low moisture concentration, the water molecules affect the molecular interactions by favorably forming the water-nanocomposite H-bonds and the small cluster, while at high concentration the water molecules predominantly form the water-water H-bonds and the large cluster. The water molecules in the epoxy matrix and the epoxy-SWCNT interface disrupt the molecular interactions and deteriorate the mechanical properties. Through identifying the link between the water molecules and the nanocomposite structure and properties, it is shown that the free volume in the nanocomposite is crucial for its structural integrity, which facilitates the moisture accumulation and the distinct material deteriorations. This study provides insights into the moisture-affected structure and properties of the nanocomposite from the nanoscale perspective, which contributes to the understanding of the nanocomposite long-term performance under the moisture effect.

Molecular Mechanics of the Moisture Effect on Epoxy/Carbon Nanotube Nanocomposites

PubMed Central

2017-01-01

The strong structural integrity of polymer nanocomposite is influenced in the moist environment; but the fundamental mechanism is unclear, including the basis for the interactions between the absorbed water molecules and the structure, which prevents us from predicting the durability of its applications across multiple scales. In this research, a molecular dynamics model of the epoxy/single-walled carbon nanotube (SWCNT) nanocomposite is constructed to explore the mechanism of the moisture effect, and an analysis of the molecular interactions is provided by focusing on the hydrogen bond (H-bond) network inside the nanocomposite structure. The simulations show that at low moisture concentration, the water molecules affect the molecular interactions by favorably forming the water-nanocomposite H-bonds and the small cluster, while at high concentration the water molecules predominantly form the water-water H-bonds and the large cluster. The water molecules in the epoxy matrix and the epoxy-SWCNT interface disrupt the molecular interactions and deteriorate the mechanical properties. Through identifying the link between the water molecules and the nanocomposite structure and properties, it is shown that the free volume in the nanocomposite is crucial for its structural integrity, which facilitates the moisture accumulation and the distinct material deteriorations. This study provides insights into the moisture-affected structure and properties of the nanocomposite from the nanoscale perspective, which contributes to the understanding of the nanocomposite long-term performance under the moisture effect. PMID:29027979

Preparation and characterization of multi-layer biodegradable nanofibers by coaxial electrospinning and their potential for tissue engineering

NASA Astrophysics Data System (ADS)

Liu, Wenwen

As an evolution of conventional electrospinning, coaxial electrospinning became popular soon after its debut as a novel way to develop nanofibers with special structures, such as core-shell and hollow interior. In recent years, there has been an increasing interest in a modified coaxial electrospinning, tri-layer coaxial electrospinning, to develop more complex structures, such as multi-layer and nanowire-in-microtube. Previous studies have primarily concentrated on the fabrication of tri-layered inorganic fibers while studies on tri-layered coaxial polymeric fibers has not been reported until very recently. Our research focuses on the fabrication of core-shell and tri-layer structured biodegradable polymeric nanofibers with coaxial electrospinning. Different characterization methods have been applied to observe the internal structure in single nanofibers and the potential application of tri-layer coaxial electrospinning has been discussed. The material system consists of biodegradable natural polymer gelatin, synthetic polymers poly (epsilon-caprolactone) (PCL) and poly (lactic-co-glycolic acid) (PLGA). A uniquely designed three-needle concentric spinneret is developed to perform tri-layer coaxial electrospinning. Different kinds of core-shell structured nanofibers, including gelatin/PCL, PCL/gelatin, gelatin/PLGA and PCL/PLGA, have been fabricated with a customized coaxial electrospinning apparatus. Two kinds of tri-layer coaxial nanofibers, two-component ABA structured gelatin/PCL/gelatin biodegradable nanofibers and tri-component ABC structured gelatin/PCL/PLGA biodegradable nanofibers, have been developed with the customized three needle coaxial electrospinning setup. The core-shell and tri-layered structures of electrospun nanofibers have been characterized by several commonly used techniques, such as laser scanning confocal microscopy (LSCM) and transmission electron microscopy (TEM). Besides the conventional methods, other newer techniques, including focused ion beam-scanning electron microscopy (FIB-SEM), super-resolution structured illumination microscopy (SR-SIM) and nanoscale-infrared spectroscopy (nano-IR), have been explored to investigate the internal structure in singles fibers. Additionally, the potential application of coaxial electrospinning in the fabrication of bioactive scaffolds for tissue engineering has been studied. Different kinds of coaxial nanofibers were fabricated and studied to determine the potential for BSA and growth factor release and some preliminary results were obtained.

Thermal response of solar receiver aperture plates during sun walk-off

NASA Technical Reports Server (NTRS)

Wen, L.; Roschke, J.

1982-01-01

The tracking mechanism for a point-focusing concentrator may be subject to failure. If this should occur, the solar image will travel across the aperture plate, and it may also impinge on the adjacent support structure. Such an event is called 'sun walk-off'. The present investigation is concerned with the transient response of different aperture plate materials to the intense heating produced in a typical walk-off situation for parabolic dish concentrators. Receivers for two solar module systems are considered, including a high-temperature receiver that utilizes a 2-milliradian (mrad) concentrator, and a lower-temperature receiver which is coupled with a 4-mrad concentrator. It is found that during a walk-off situation the solar image travels in a straight line in the radial direction. The results obtained for a copper aperture plate were disappointing. It appears that passive metallic plates without cooling or other protective support cannot withstand the intense heating.

Architectural and Mechanical Cues Direct Mesenchymal Stem Cell Interactions with Crosslinked Gelatin Scaffolds

PubMed Central

McAndrews, Kathleen M.; Kim, Min Jeong; Lam, Tuyet Y.; McGrail, Daniel J.

2014-01-01

Naturally derived biomaterials have emerged as modulators of cell function and tissue substitutes. Here, we developed crosslinked glutaraldehyde (GTA) scaffolds for the expansion and differentiation of mesenchymal stem cells (MSCs). The mechanical and architectural properties of the scaffolds were altered by varying the concentration of gelatin and GTA. Higher GTA concentrations were associated with an increase in more confined pores and osteogenic differentiation. In addition, myogenic potential varied with crosslinking degree, although bulk mechanical properties were unaltered. Correlation analysis revealed that ALP activity of differentiated MSCs on higher gelatin concentration scaffolds was dependent on traditional effectors, including environment elasticity and spread area. In contrast, the differentiation capacity of cells cultured on lower gelatin concentration scaffolds did not correlate with these factors, instead it was dependent on the hydrated pore structure. These results suggest that scaffold composition can determine what factors direct differentiation and may have critical implications for biomaterial design. PMID:24873687

Machine-Learned Data Structures of Lipid Marker Serum Concentrations in Multiple Sclerosis Patients Differ from Those in Healthy Subjects

PubMed Central

Lötsch, Jörn; Thrun, Michael; Lerch, Florian; Brunkhorst, Robert; Schiffmann, Susanne; Thomas, Dominique; Tegder, Irmgard; Geisslinger, Gerd; Ultsch, Alfred

2017-01-01

Lipid signaling has been suggested to be a major pathophysiological mechanism of multiple sclerosis (MS). With the increasing knowledge about lipid signaling, acquired data become increasingly complex making bioinformatics necessary in lipid research. We used unsupervised machine-learning to analyze lipid marker serum concentrations, pursuing the hypothesis that for the most relevant markers the emerging data structures will coincide with the diagnosis of MS. Machine learning was implemented as emergent self-organizing feature maps (ESOM) combined with the U*-matrix visualization technique. The data space consisted of serum concentrations of three main classes of lipid markers comprising eicosanoids (d = 11 markers), ceramides (d = 10), and lyosophosphatidic acids (d = 6). They were analyzed in cohorts of MS patients (n = 102) and healthy subjects (n = 301). Clear data structures in the high-dimensional data space were observed in eicosanoid and ceramides serum concentrations whereas no clear structure could be found in lysophosphatidic acid concentrations. With ceramide concentrations, the structures that had emerged from unsupervised machine-learning almost completely overlapped with the known grouping of MS patients versus healthy subjects. This was only partly provided by eicosanoid serum concentrations. Thus, unsupervised machine-learning identified distinct data structures of bioactive lipid serum concentrations. These structures could be superimposed with the known grouping of MS patients versus healthy subjects, which was almost completely possible with ceramides. Therefore, based on the present analysis, ceramides are first-line candidates for further exploration as drug-gable targets or biomarkers in MS. PMID:28590455

Mercury exposure may influence fluctuating asymmetry in waterbirds

USGS Publications Warehouse

Herring, Garth; Eagles-Smith, Collin A.; Ackerman, Joshua T.

2017-01-01

Variation in avian bilateral symmetry can be an indicator of developmental instability in response to a variety of stressors, including environmental contaminants. The authors used composite measures of fluctuating asymmetry to examine the influence of mercury concentrations in 2 tissues on fluctuating asymmetry within 4 waterbird species. Fluctuating asymmetry increased with mercury concentrations in whole blood and breast feathers of Forster's terns (Sterna forsteri), a species with elevated mercury concentrations. Specifically, fluctuating asymmetry in rectrix feather 1 was the most strongly correlated structural variable of those tested (wing chord, tarsus, primary feather 10, rectrix feather 6) with mercury concentrations in Forster's terns. However, for American avocets (Recurvirostra americana), black-necked stilts (Himantopus mexicanus), and Caspian terns (Hydroprogne caspia), the authors found no relationship between fluctuating asymmetry and either whole-blood or breast feather mercury concentrations, even though these species had moderate to elevated mercury exposure. The results indicate that mercury contamination may act as an environmental stressor during development and feather growth and contribute to fluctuating asymmetry of some species of highly contaminated waterbirds.

Year-to-year variations in annual average indoor 222Rn concentrations.

PubMed

Martz, D E; Rood, A S; George, J L; Pearson, M D; Langner, G H

1991-09-01

Annual average indoor 222Rn concentrations in 40 residences in and around Grand Junction, CO, have been measured repeatedly since 1984 using commercial alpha-track monitors (ATM) deployed for successive 12-mo time periods. Data obtained provide a quantitative measure of the year-to-year variations in the annual average Rn concentrations in these structures over this 6-y period. A mean coefficient of variation of 25% was observed for the year-to-year variability of the measurements at 25 sampling stations for which complete data were available. Individual coefficients of variation at the various stations ranged from a low of 7.7% to a high of 51%. The observed mean coefficient of variation includes contributions due to the variability in detector response as well as the true year-to-year variation in the annual average Rn concentrations. Factoring out the contributions from the measured variability in the response of the detectors used, the actual year-to-year variability of the annual average Rn concentrations was approximately 22%.

Enzyme-triggered self-assembly of a small molecule: a supramolecular hydrogel with leaf-like structures and an ultra-low minimum gelation concentration

NASA Astrophysics Data System (ADS)

Wang, Huaimin; Ren, Chunhua; Song, Zhijian; Wang, Ling; Chen, Xuemei; Yang, Zhimou

2010-06-01

We report on the use of a phosphatase to assist the formation of leaf-like structures and a supramolecular hydrogel with an ultra-low minimum gelation concentration. The compound can gel water at a minimum gelation concentration of 0.01 wt%, which is the lowest gelation concentration reported up to now. The images obtained by transmission electron microscopy (TEM) reveal the existence of leaf-like structures serving as the matrix of the hydrogels. The stability of the hydrogels was studied and emission spectra were used to get information about the molecular packing in the leaf-like structures. Since lowering the concentration of the gelator decreases the toxicity of the resulting hydrogels, ultra-low concentration gels have potential uses as biocompatible biomaterials for, e.g., cell cultures, tissue engineering, and drug delivery.

Use of a macroinvertebrate based biotic index to estimate critical metal concentrations for good ecological water quality.

PubMed

Van Ael, Evy; De Cooman, Ward; Blust, Ronny; Bervoets, Lieven

2015-01-01

Large datasets from total and dissolved metal concentrations in Flemish (Belgium) fresh water systems and the associated macroinvertebrate-based biotic index MMIF (Multimetric Macroinvertebrate Index Flanders) were used to estimate critical metal concentrations for good ecological water quality, as imposed by the European Water Framework Directive (2000). The contribution of different stressors (metals and water characteristics) to the MMIF were studied by constructing generalized linear mixed effect models. Comparison between estimated critical concentrations and the European and Flemish EQS, shows that the EQS for As, Cd, Cu and Zn seem to be sufficient to reach a good ecological quality status as expressed by the invertebrate-based biotic index. In contrast, the EQS for Cr, Hg and Pb are higher than the estimated critical concentrations, which suggests that when environmental concentrations are at the same level as the EQS a good quality status might not be reached. The construction of mixed models that included metal concentrations in their structure did not lead to a significant outcome. However, mixed models showed the primary importance of water characteristics (oxygen level, temperature, ammonium concentration and conductivity) for the MMIF. Copyright © 2014 Elsevier Ltd. All rights reserved.

Composition, structure and functional properties of protein concentrates and isolates produced from walnut (Juglans regia L.).

PubMed

Mao, Xiaoying; Hua, Yufei

2012-01-01

In this study, composition, structure and the functional properties of protein concentrate (WPC) and protein isolate (WPI) produced from defatted walnut flour (DFWF) were investigated. The results showed that the composition and structure of walnut protein concentrate (WPC) and walnut protein isolate (WPI) were significantly different. The molecular weight distribution of WPI was uniform and the protein composition of DFWF and WPC was complex with the protein aggregation. H(0) of WPC was significantly higher (p < 0.05) than those of DFWF and WPI, whilst WPI had a higher H(0) compared to DFWF. The secondary structure of WPI was similar to WPC. WPI showed big flaky plate like structures; whereas WPC appeared as a small flaky and more compact structure. The most functional properties of WPI were better than WPC. In comparing most functional properties of WPI and WPC with soybean protein concentrate and isolate, WPI and WPC showed higher fat absorption capacity (FAC). Emulsifying properties and foam properties of WPC and WPI in alkaline pH were comparable with that of soybean protein concentrate and isolate. Walnut protein concentrates and isolates can be considered as potential functional food ingredients.

Impact of Tropopause Structures on Deep Convective Transport Observed during MACPEX

NASA Astrophysics Data System (ADS)

Mullendore, G. L.; Bigelbach, B. C.; Christensen, L. E.; Maddox, E.; Pinkney, K.; Wagner, S.

2016-12-01

Deep convection is the most efficient method of transporting boundary layer mass to the upper troposphere and stratosphere (UTLS). The Mid-latitude Airborne Cirrus Properties Experiment (MACPEX) was conducted during April of 2011 over the central U.S. With a focus on cirrus clouds, the campaign flights often sampled large cirrus anvils downstream from deep convection and included an extensive observational suite of chemical measurements on a high altitude aircraft. As double-tropopause structures are a common feature in the central U.S. during the springtime, the MACPEX campaign provides a good opportunity to gather cases of deep convective transport in the context of both single and double tropopause structures. Sampling of chemical plumes well downstream from convection allows for sampling in relatively quiescent conditions and analysis of irreversible transport. The analysis presented includes multiple methods to assess air mass source and possible convective processing, including back trajectories and ratios of chemical concentrations. Although missions were flown downstream of deep convection, recent processing by convection does not seem likely in all cases that high altitude carbon monoxide plumes were observed. Additionally, the impact of single and double tropopause structures on deep convective transport is shown to be strongly dependent on high stability layers.

A Model of the Chicxulub Impact Basin Based on Evaluation of Geophysical Data, Well Logs, and Drill Core Samples

NASA Technical Reports Server (NTRS)

Sharpton, Virgil L.; Marin, Luis E.; Carney, John D.; Lee, Scott; Ryder, Graham; Schuraytz, Benjamin C.; Sikora, Paul; Spudis, Paul D.

1996-01-01

Abundant evidence now shows that the buried Chicxulub structure in northern Yucatan, Mexico, is indeed the intensely sought-after source of the ejecta found world-wide at the Cretaceous-Tertiary (K/T) boundary. In addition to large-scale concentric patterns in gravity and magnetic data over the structure, recent analyses of drill-core samples reveal a lithological assemblage similar to that observed at other terrestrial craters. This assemblage comprises suevite breccias, ejecta deposit breccias (Bunte Breccia equivalents), fine-grained impact melt rocks, and melt-matrix breccias. All these impact-produced lithologies contain diagnostic evidence of shock metamorphism, including planar deformation features in quartz, feldspar, and zircons; diaplectic glasses of quartz and feldspar; and fused mineral melts and whole-rock melts. In addition, elevated concentrations of Ir, Re, and Os, in meteoritic relative proportions, have been detected in some melt-rock samples from the center of the structure. Isotopic analyses, magnetization of melt-rock samples, and local stratigraphic constraints identify this crater as the source of K/T boundary deposits.

Maturation of limbic regions in Asperger syndrome: a preliminary study using proton magnetic resonance spectroscopy and structural magnetic resonance imaging.

PubMed

O'Brien, Finian M; Page, Lisa; O'Gorman, Ruth L; Bolton, Patrick; Sharma, Ajay; Baird, Gillian; Daly, Eileen; Hallahan, Brian; Conroy, Ronán M; Foy, Catherine; Curran, Sarah; Robertson, Dene; Murphy, Kieran C; Murphy, Declan G M

2010-11-30

People with autistic spectrum disorders (ASD, including Asperger syndrome) may have developmental abnormalities in the amygdala-hippocampal complex (AHC). However, in vivo, age-related comparisons of both volume and neuronal integrity of the AHC have not yet been carried out in people with Asperger syndrome (AS) versus controls. We compared structure and metabolic activity of the right AHC of 22 individuals with AS and 22 healthy controls aged 10-50 years and examined the effects of age between groups. We used structural magnetic resonance imaging (sMRI) to measure the volume of the AHC, and magnetic resonance spectroscopy ((1)H-MRS) to measure concentrations of N-acetyl aspartate (NAA), creatine+phosphocreatine (Cr+PCr), myo-inositol (mI) and choline (Cho). The bulk volume of the amygdala and the hippocampus did not differ significantly between groups, but there was a significant difference in the effect of age on the hippocampus in controls. Compared with controls, young (but not older) people with AS had a significantly higher AHC concentration of NAA and a significantly higher NAA/Cr ratio. People with AS, but not controls, had a significant age-related reduction in NAA and the NAA/Cr ratio. Also, in people with AS, but not controls, there was a significant relationship between concentrations of choline and age so that choline concentrations reduced with age. We therefore suggest that people with AS have significant differences in neuronal and lipid membrane integrity and maturation of the AHC. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Short-Time Glassy Dynamics in Viscous Protein Solutions with Competing Interactions

DOE PAGES

Godfrin, P. Douglas; Hudson, Steven; Hong, Kunlun; ...

2015-11-24

Although there have been numerous investigations of the glass transition for colloidal dispersions with only a short-ranged attraction, less is understood for systems interacting with a long-ranged repulsion in addition to this attraction, which is ubiquitous in aqueous protein solutions at low ionic strength. Highly puri ed concentrated lysozyme solutions are used as a model system and investigated over a large range of protein concentrations at very low ionic strength. Newtonian liquid behavior is observed at all concentrations, even up to 480 mg/mL, where the zero shear viscosity increases by more than three orders of magnitude with increasing concentration. Remarkably,more » despite this macroscopic liquid-like behavior, the measurements of the dynamics in the short-time limit shows features typical of glassy colloidal systems. Investigation of the inter-protein structure indicates that the reduced short-time mobility of the protein is caused by localized regions of high density within a heterogeneous density distribution. This structural heterogeneity occurs on intermediate range length scale, driven by the competing potential features, and is distinct from commonly studied colloidal gel systems in which a heterogeneous density distribution tends to extend to the whole system. The presence of long-ranged repulsion also allows for more mobility over large length and long time scales resulting in the macroscopic relaxation of the structure. The experimental results provide evidence for the need to explicitly include intermediate range order in theories for the macroscopic properties of protein solutions interacting via competing potential features.« less

In vitro reconstruction of branched tubular structures from lung epithelial cells in high cell concentration gradient environment.

PubMed

Hagiwara, Masaya; Peng, Fei; Ho, Chih-Ming

2015-01-27

We have succeeded in developing hollow branching structure in vitro commonly observed in lung airway using primary lung airway epithelial cells. Cell concentration gradient is the key factor that determines production of the branching cellular structures, as optimization of this component removes the need for heterotypic culture. The higher cell concentration leads to the more production of morphogens and increases the growth rate of cells. However, homogeneous high cell concentration does not make a branching structure. Branching requires sufficient space in which cells can grow from a high concentration toward a low concentration. Simulation performed using a reaction-diffusion model revealed that long-range inhibition prevents cells from branching when they are homogeneously spread in culture environments, while short-range activation from neighboring cells leads to positive feedback. Thus, a high cell concentration gradient is required to make branching structures. Spatial distributions of morphogens, such as BMP-4, play important roles in the pattern formation. This simple yet robust system provides an optimal platform for the further study and understanding of branching mechanisms in the lung airway, and will facilitate chemical and genetic studies of lung morphogenesis programs.

Prediction of Intensity Change Subsequent to Concentric Eyewall Events

NASA Astrophysics Data System (ADS)

Mauk, Rachel Grant

Concentric eyewall events have been documented numerous times in intense tropical cyclones over the last two decades. During a concentric eyewall event, an outer (secondary) eyewall forms around the inner (primary) eyewall. Improved instrumentation on aircraft and satellites greatly increases the likelihood of detecting an event. Despite the increased ability to detect such events, forecasts of intensity changes during and after these events remain poor. When concentric eyewall events occur near land, accurate intensity change predictions are especially critical to ensure proper emergency preparations and staging of recovery assets. A nineteen-year (1997-2015) database of concentric eyewall events is developed by analyzing microwave satellite imagery, aircraft- and land-based radar, and other published documents. Events are identified in both the North Atlantic and eastern North Pacific basins. TCs are categorized as single (1 event), serial (>= 2 events) and super-serial (>= 3 events). Key findings here include distinct spatial patterns for single and serial Atlantic TCs, a broad seasonal distribution for eastern North Pacific TCs, and apparent ENSO-related variability in both basins. The intensity change subsequent to the concentric eyewall event is calculated from the HURDAT2 database at time points relative to the start and to the end of the event. Intensity change is then categorized as Weaken (≤ -10 kt), Maintain (+/- 5 kt), and Strengthen (≥ 10 kt). Environmental conditions in which each event occurred are analyzed based on the SHIPS diagnostic files. Oceanic, dynamic, thermodynamic, and TC status predictors are selected for testing in a multiple discriminant analysis procedure to determine which variables successfully discriminate the intensity change category and the occurrence of additional concentric eyewall events. Intensity models are created for 12 h, 24 h, 36 h, and 48 h after the concentric eyewall events end. Leave-one-out cross validation is performed on each set of discriminators to generate classifications, which are then compared to observations. For each model, the top combinations achieve 80-95% overall accuracy in classifying TCs based on the environmental characteristics, although Maintain systems are frequently misclassified. The third part of this dissertation employs the Weather Research and Forecasting model to further investigate concentric eyewall events. Two serial Atlantic concentric eyewall cases (Katrina 2005 and Wilma 2005) are selected from the original study set, and WRF simulations performed using several model designs. Despite strong evidence from multiple sources that serial concentric eyewalls formed in both hurricanes, the WRF simulations did not produce identifiable concentric eyewall structures for Katrina, and only transient structures for Wilma. Possible reasons for the lack of concentric eyewall formation are discussed, including model resolution, microphysics, and data sources.

Transport Of Passive Scalars In A Turbulent Channel Flow

NASA Technical Reports Server (NTRS)

Kim, John; Moin, Parviz

1990-01-01

Computer simulation of transport of passive scalars in turbulent channel flow described in report. Shows flow structures and statistical properties. As used here, "passive scalars" means scalar quantities like fluctuations in temperature or concentrations of contaminants that do not disturb flow appreciably. Examples include transport of heat in heat exchangers, gas turbines, and nuclear reactors and dispersal of pollution in atmosphere.

Certification and verification for Northrup Model NSC-01-0732 Fresnel lens concentrating solar collector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1979-03-01

The certification and verification of the Northrup Model NSC-01-0732 Fresnel lens tracking solar collector are presented. A certification statement is included with signatures and a separate report on the structural analysis of the collector system. System verification against the Interim Performance Criteria are indicated by matrices with verification discussion, analysis, and enclosed test results.

The molecular refractive function of lens γ-crystallins

PubMed Central

Zhao, Huaying; Brown, Patrick H.; Magone, M. Teresa; Schuck, Peter

2011-01-01

γ-crystallins constitute the major protein component in the nucleus of the vertebrate eye lens. Present at very high concentrations, they exhibit extreme solubility and thermodynamic stability to prevent scattering of light and the formation of cataracts. However, functions beyond this structural role have remained mostly unclear. Here, we calculate molecular refractive index increments of crystallins. We show that all lens γ-crystallins have evolved a significantly elevated molecular refractive index increment, which is far above those of most proteins, including non-lens members of the βγ-crystallin family from different species. The same trait has evolved in parallel in crystallins of different phyla, including in the S-crystallins of cephalopods. A high refractive index increment can lower the crystallin concentration required to achieve a suitable refractive power of the lens, and thereby reduce their propensity to aggregate and form cataract. To produce a significant increase of the refractive index increment, a substantial global shift in the amino acid composition is required, which can naturally explain the highly unusual amino acid composition of γ-crystallins and their functional homologues. This function provides a new perspective for interpreting their molecular structure. PMID:21684289

The molecular refractive function of lens γ-Crystallins.

PubMed

Zhao, Huaying; Brown, Patrick H; Magone, M Teresa; Schuck, Peter

2011-08-19

γ-Crystallins constitute the major protein component in the nucleus of the vertebrate eye lens. Present at very high concentrations, they exhibit extreme solubility and thermodynamic stability to prevent scattering of light and formation of cataracts. However, functions beyond this structural role have remained mostly unclear. Here, we calculate molecular refractive index increments of crystallins. We show that all lens γ-crystallins have evolved a significantly elevated molecular refractive index increment, which is far above those of most proteins, including nonlens members of the βγ-crystallin family from different species. The same trait has evolved in parallel in crystallins of different phyla, including S-crystallins of cephalopods. A high refractive index increment can lower the crystallin concentration required to achieve a suitable refractive power of the lens and thereby reduce their propensity to aggregate and form cataracts. To produce a significant increase in the refractive index increment, a substantial global shift in amino acid composition is required, which can naturally explain the highly unusual amino acid composition of γ-crystallins and their functional homologues. This function provides a new perspective for interpreting their molecular structure. Copyright © 2011. Published by Elsevier Ltd.

Effects of triclosan on bacterial community composition and ...

EPA Pesticide Factsheets

Pharmaceuticals and personal care products, including antimicrobials, can be found at trace levels in treated wastewater effluent. Impacts of chemical contaminants on coastal aquatic microbial community structure and pathogen abundance are unknown despite the potential for selection through antimicrobial resistance. In particular, Vibrio, a marine bacterial genus that includes several human pathogens, displays resistance to the ubiquitous antimicrobial compound triclosan. Here we demonstrated through use of natural seawater microcosms that triclosan (at a concentration of ~5 ppm) can induce a significant Vibrio growth response (68–1,700 fold increases) in comparison with no treatment controls for three distinct coastal ecosystems: Looe Key Reef (Florida Keys National Marine Sanctuary), Doctors Arm Canal (Big Pine Key, FL), and Clam Bank Landing (North Inlet Estuary, Georgetown, SC). Additionally, microbial community analysis by 16 S rRNA gene sequencing for Looe Key Reef showed distinct changes in microbial community structure with exposure to 5 ppm triclosan, with increases observed in the relative abundance of Vibrionaceae (17-fold), Pseudoalteromonadaceae (65-fold), Alteromonadaceae (108-fold), Colwelliaceae (430-fold), and Oceanospirillaceae (1,494-fold). While the triclosan doses tested were above concentrations typically observed in coastal surface waters, results identify bacterial families that are potentially resistant to triclosan and/or adapted to u

Littoral zone fish assemblages of northern Cayuga Lake.

USGS Publications Warehouse

McKenna, James E.

2001-01-01

Fish assemblages from northern Cayuga Lake were examined for patterns in temporal structure. Fish assemblages changed significantly between seasons. Bluegill (Lepomis macrochirus), bluntnose minnow (Pimephales notatus), and smallmouth bass (Micropterus dolomieu) formed the basis for most assemblages, but the spring assemblage was dominated by common carp (Cyprinus carpio). Correlations between community structure and abiotic factors were identified. Ten abiotic factors strongly influenced species assemblages, including phosphorus concentration, but could not fully explain differences between assemblages. Results indicate that the seasonal pattern of fish assemblage structure and abundance of fish that tend to feed in the water column were related to the annual cycle of productivity in the lake and behavioral adaptations of the fish.

Convergent evolution of adenosine aptamers spanning bacterial, human, and random sequences revealed by structure-based bioinformatics and genomic SELEX

PubMed Central

Vu, Michael M. K.; Jameson, Nora E.; Masuda, Stuart J.; Lin, Dana; Larralde-Ridaura, Rosa; Lupták, Andrej

2012-01-01

SUMMARY Aptamers are structured macromolecules in vitro evolved to bind molecular targets, whereas in nature they form the ligand-binding domains of riboswitches. Adenosine aptamers of a single structural family were isolated several times from random pools but they have not been identified in genomic sequences. We used two unbiased methods, structure-based bioinformatics and human genome-based in vitro selection, to identify aptamers that form the same adenosine-binding structure in a bacterium, and several vertebrates, including humans. Two of the human aptamers map to introns of RAB3C and FGD3 genes. The RAB3C aptamer binds ATP with dissociation constants about ten times lower than physiological ATP concentration, while the minimal FGD3 aptamer binds ATP only co-transcriptionally. PMID:23102219

Three-dimensional structure of dominant instabilities in turbulent flow over smooth and rough boundaries

NASA Astrophysics Data System (ADS)

Grass, A. J.; Stuart, R. J.; Mansour-Tehrani, M.

1991-01-01

The current status of knowledge regarding coherent vortical structures in turbulent boundary layers and their role in turbulence generation are reviewed. The investigations reported in the study concentrate attention on rough-wall flows prevailing in the geophysical environment and include an experiment determining the three-dimensional form of the turbulence structures linked to the ejection and inrush events observed over rough walls and an experiment concerned with measuring the actual spanwise scale of the near-wall structures for boundary conditions ranging from hydrodynamically smooth to fully rough. It is demonstrated that horseshoe vortical structures are present and play an important role in rough-wall flows and they increase in scale with increasing wall distance, while a dominant spanwise wavelength occurs in the instantaneous cross-flow distribution of streamwise velocity close to the rough wall.

Electrochemical characterization of p(+)n and n(+)p diffused InP structures

NASA Technical Reports Server (NTRS)

Wilt, David M.; Faur, Maria; Faur, Mircea; Goradia, M.; Vargas-Aburto, Carlos

1993-01-01

The relatively well documented and widely used electrolytes for characterization and processing of Si and GaAs-related materials and structures by electrochemical methods are of little or no use with InP because the electrolytes presently used either dissolve the surface preferentially at the defect areas or form residual oxides and introduce a large density of surface states. Using an electrolyte which was newly developed for anodic dissolution of InP, and was named the 'FAP' electrolyte, accurate characterization of InP related structures including nature and density of surface states, defect density, and net majority carrier concentration, all as functions of depth was performed. A step-by-step optimization of n(+)p and p(+)n InP structures made by thermal diffusion was done using the electrochemical techniques, and resulted in high performance homojunction InP structures.

Phenolic compositions of 50 and 30 year sequences of Australian red wines: the impact of wine age.

PubMed

McRae, Jacqui M; Dambergs, Robert G; Kassara, Stella; Parker, Mango; Jeffery, David W; Herderich, Markus J; Smith, Paul A

2012-10-10

The phenolic composition of red wine impacts upon the color and mouthfeel and thus quality of the wine. Both of these characteristics differ depending on the age of a wine, with the purple of young wines changing to brick red and the puckering or aggressive astringency softening in older wines. This study investigated the color parameters, tannin concentrations and tannin composition of a 50 year series of Cabernet Sauvignon wines from a commercial label as well as 30 year series of Cabernet Sauvignon and Shiraz wines from a separate commercial label to assess the impact of wine age on phenolic composition and concentration. The wine color density in wines of 40 to 50 years old was around 5 AU compared with 16 AU of wine less than 12 months old, which correlated well with the concentration of non-bleachable pigments and pigmented polymers. Conversely, the anthocyanin concentrations in 10 year old wines were substantially lower than that of recently bottled wines (around 100 mg/L compared with 627 mg/L, respectively), adding further evidence that non-bleachable pigments including pigmented polymers play a much larger role in long-term wine color than anthocyanins. No age-related trend was observed for tannin concentration, indicating that the widely noted softer astringency of older red wines cannot necessarily be directly related to lower concentrations of soluble wine tannin and is potentially a consequence of changes in tannin structure. Wine tannins from older wines were generally larger than tannins from younger wines and showed structural changes consistent with oxidation.

Development of a NIR-based blend uniformity method for a drug product containing multiple structurally similar actives by using the quality by design principles.

PubMed

Lin, Yiqing; Li, Weiyong; Xu, Jin; Boulas, Pierre

2015-07-05

The aim of this study is to develop an at-line near infrared (NIR) method for the rapid and simultaneous determination of four structurally similar active pharmaceutical ingredients (APIs) in powder blends intended for the manufacturing of tablets. Two of the four APIs in the formula are present in relatively small amounts, one at 0.95% and the other at 0.57%. Such small amounts in addition to the similarity in structures add significant complexity to the blend uniformity analysis. The NIR method is developed using spectra from six laboratory-created calibration samples augmented by a small set of spectra from a large-scale blending sample. Applying the quality by design (QbD) principles, the calibration design included concentration variations of the four APIs and a main excipient, microcrystalline cellulose. A bench-top FT-NIR instrument was used to acquire the spectra. The obtained NIR spectra were analyzed by applying principal component analysis (PCA) before calibration model development. Score patterns from the PCA were analyzed to reveal relationship between latent variables and concentration variations of the APIs. In calibration model development, both PLS-1 and PLS-2 models were created and evaluated for their effectiveness in predicting API concentrations in the blending samples. The final NIR method shows satisfactory specificity and accuracy. Copyright © 2015 Elsevier B.V. All rights reserved.

Population Pharmacokinetic Model of Doxycycline Plasma Concentrations Using Pooled Study Data

PubMed Central

Wojciechowski, Jessica; Mudge, Stuart; Upton, Richard N.; Foster, David J. R.

2017-01-01

ABSTRACT The literature presently lacks a population pharmacokinetic analysis of doxycycline. This study aimed to develop a population pharmacokinetic model of doxycycline plasma concentrations that could be used to assess the power of bioequivalence between Doryx delayed-release tablets and Doryx MPC. Doxycycline pharmacokinetic data were available from eight phase 1 clinical trials following single/multiple doses of conventional-release doxycycline capsules, Doryx delayed-release tablets, and Doryx MPC under fed and fasted conditions. A population pharmacokinetic model was developed in a stepwise manner using NONMEM, version 7.3. The final covariate model was developed according to a forward inclusion (P < 0.01) and then backward deletion (P < 0.001) procedure. The final model was a two-compartment model with two-transit absorption compartments. Structural covariates in the base model included formulation effects on relative bioavailability (F), absorption lag (ALAG), and the transit absorption rate (KTR) under the fed status. An absorption delay (lag) for the fed status (FTLAG2 = 0.203 h) was also included in the model as a structural covariate. The fed status was observed to decrease F by 10.5%, and the effect of female sex was a 14.4% increase in clearance. The manuscript presents the first population pharmacokinetic model of doxycycline plasma concentrations following oral doxycycline administration. The model was used to assess the power of bioequivalence between Doryx delayed-release tablets and Doryx MPC, and it could potentially be used to critically examine and optimize doxycycline dose regimens. PMID:28052851

Population Pharmacokinetic Model of Doxycycline Plasma Concentrations Using Pooled Study Data.

PubMed

Hopkins, Ashley M; Wojciechowski, Jessica; Abuhelwa, Ahmad Y; Mudge, Stuart; Upton, Richard N; Foster, David J R

2017-03-01

The literature presently lacks a population pharmacokinetic analysis of doxycycline. This study aimed to develop a population pharmacokinetic model of doxycycline plasma concentrations that could be used to assess the power of bioequivalence between Doryx delayed-release tablets and Doryx MPC. Doxycycline pharmacokinetic data were available from eight phase 1 clinical trials following single/multiple doses of conventional-release doxycycline capsules, Doryx delayed-release tablets, and Doryx MPC under fed and fasted conditions. A population pharmacokinetic model was developed in a stepwise manner using NONMEM, version 7.3. The final covariate model was developed according to a forward inclusion ( P < 0.01) and then backward deletion ( P < 0.001) procedure. The final model was a two-compartment model with two-transit absorption compartments. Structural covariates in the base model included formulation effects on relative bioavailability ( F ), absorption lag (ALAG), and the transit absorption rate (KTR) under the fed status. An absorption delay (lag) for the fed status (FTLAG2 = 0.203 h) was also included in the model as a structural covariate. The fed status was observed to decrease F by 10.5%, and the effect of female sex was a 14.4% increase in clearance. The manuscript presents the first population pharmacokinetic model of doxycycline plasma concentrations following oral doxycycline administration. The model was used to assess the power of bioequivalence between Doryx delayed-release tablets and Doryx MPC, and it could potentially be used to critically examine and optimize doxycycline dose regimens. Copyright © 2017 American Society for Microbiology.

Engineering and characterizing nanoscale multilayered structures for magnetic tunnel junctions

NASA Astrophysics Data System (ADS)

Yang, J. Joshua

Magnetic tunnel junction (MTJ) has generated considerable attention due to its potential applications in improved magnetic sensors, read heads in HDDs and nonvolatile RAM. The materials issues play a crucial role in the performance of MTJs. In the work described in this thesis, we have engineered some interesting nanoscale multilayered structures mainly via thermodynamics considerations for MTJs. The insulator is usually an ultra-thin (<2nm) oxide, formed by oxidizing a pre-deposited metal, such as Al etc. We have developed novel fabrication approaches for obtaining clean and smooth interfaces between the insulator and the ferromagnets. These approaches include selectively oxidizing the pre-deposited tunnel barrier precursor metal, amorphizing the tunnel barrier precursor metal by alloying it with other elements, and in-situ annealing the bottom ferromagnetic layer. About 72% tunneling magnetoresistance (TMR) has been achieved at room temperature with AlOx and CoFe based MTJs. We have made a systemic study of the TMR vs. the Co1-xFe x electrode composition for AlOx based MTJs. A significant variation of TMR with Fe concentration has been observed. It is well known that the crystal structure of Co1-xFex changes from fcc to bcc with increasing Fe concentration. The concomitant composition change cast doubts on the role played by the crystal structure of the Co1-x Fex electrode on the TMR. By introducing different strains to an epitaxial Co1-xFex layer, we were able to fix its composition but alter its crystalline structure from fcc to bcc and found that the bcc structure resulted in much higher TMR values than found for the fcc structure. This is one of the few direct experimental confirmatory results showing the role of the FM electronic structure on the MTJ properties. Using Ag as a template, different 3d ferromagnets have been epitaxially grown on the Si substrate with hcp, fcc and bcc crystalline structures, respectively. By combining the selective oxidation method with the epitaxial growth technique, we have successfully created a single-crystal-like layer on top of an amorphous layer, which may have broad applications in thin film devices including MTJs.

Concentrating Solar Power Projects - Dish/Engine Projects | Concentrating

Science.gov Websites

together to form a dish-shaped structure. The receiver is supported above the panels by an arm-like structure and glows as it is heated by concentrated sunlight. A technician sits below the dish, in the shade

Effect of borax concentration on the structure of Poly(Vinyl Alcohol) gels

NASA Astrophysics Data System (ADS)

Lawrence, Mathias B.; Desa, J. A. E.; Aswal, V. K.

2012-06-01

Poly(Vinyl Alcohol) hydrogels cross-linked with varying concentrations of borax have been studied using Small-Angle Neutron Scattering and X-Ray Diffraction. The intensity of scattering increases with borax concentration from 1 mg/ml up to 2 mg/ml and falls thereafter for 4 mg/ml, increasing again for a concentration of 10 mg/ml. The mesoscopic structural changes that cause these trends in the SANS data are in keeping with the variations in the X-ray diffraction patterns pertaining to structures within the PVA chains.

Crystal structure and phase stability of tungsten borides

NASA Astrophysics Data System (ADS)

Li, Quan; Zhou, Dan; Ma, Yanming; Chen, Changfeng

2013-03-01

We address the longstanding and controversial issue of ground-state structures of technically important tungsten borides using a first-principles structural search method via a particle-swarm optimization (PSO) algorithm. We have explored a large set of stable chemical compositions (convex hull) and clarified the ground-state structures for a wide range of boron concentrations, including W2B, W3B2,WB,W2B3, WB2,W2B5, WB3, and WB4. We further assessed relative stability of various tungsten borides and compared the calculated results with previously reported experimental data. The phase diagram predicted by the presented calculations may serve as a useful guide for synthesis of a variety of tungsten borides. This work was supported by DOE Grant No. DE-FC52-06NA26274.

Weight optimization of an aerobrake structural concept for a lunar transfer vehicle

NASA Technical Reports Server (NTRS)

Bush, Lance B.; Unal, Resit; Rowell, Lawrence F.; Rehder, John J.

1992-01-01

An aerobrake structural concept for a lunar transfer vehicle was weight optimized through the use of the Taguchi design method, finite element analyses, and element sizing routines. Six design parameters were chosen to represent the aerobrake structural configuration. The design parameters included honeycomb core thickness, diameter-depth ratio, shape, material, number of concentric ring frames, and number of radial frames. Each parameter was assigned three levels. The aerobrake structural configuration with the minimum weight was 44 percent less than the average weight of all the remaining satisfactory experimental configurations. In addition, the results of this study have served to bolster the advocacy of the Taguchi method for aerospace vehicle design. Both reduced analysis time and an optimized design demonstrated the applicability of the Taguchi method to aerospace vehicle design.

Anomalous transport regimes and asymptotic concentration distributions in the presence of advection and diffusion on a comb structure

NASA Astrophysics Data System (ADS)

Dvoretskaya, Olga A.; Kondratenko, Peter S.

2009-04-01

We study the transport of impurity particles on a comb structure in the presence of advection. The main body concentration and asymptotic concentration distributions are obtained. Seven different transport regimes occur on the comb structure with finite teeth: classical diffusion, advection, quasidiffusion, subdiffusion, slow classical diffusion, and two kinds of slow advection. Quasidiffusion deserves special attention. It is characterized by a linear growth of the mean-square displacement. However, quasidiffusion is an anomalous transport regime. We established that a change in transport regimes in time leads to a change in regimes in space. Concentration tails have a cascade structure, namely, consisting of several parts.

Fabrication of Silica Nanospheres Coated Membranes: towards the Effective Separation of Oil-in-Water Emulsion in Extremely Acidic and Concentrated Salty Environments

PubMed Central

Chen, Yuning; Liu, Na; Cao, Yingze; Lin, Xin; Xu, Liangxin; Zhang, Weifeng; Wei, Yen; Feng, Lin

2016-01-01

A superhydrophilic and underwater superoleophobic surface is fabricated by simply coating silica nanospheres onto a glass fiber membrane through a sol-gel process. Such membrane has a complex framework with micro and nano structures covering and presents a high efficiency (more than 98%) of oil-in-water emulsion separation under harsh environments including strong acidic and concentrated salty conditions. This membrane also possesses outstanding stability since no obvious decline in efficiency is observed after different kinds of oil-in-water emulsions separation, which provides it candidate for comprehensive applicability. PMID:27597570

Effect of breed and sperm concentration on the changes in structural, functional and motility parameters of ram-lamb spermatozoa during storage at 4 degrees C.

PubMed

Kasimanickam, Ramanathan; Kasimanickam, Vanmathy; Pelzer, Kevin D; Dascanio, John J

2007-09-01

The objectives of this study were (1) to determine the changes in structural, functional and motility parameters of ram-lamb semen stored at two different concentrations at 4 degrees C for 8 days in egg-yolk based extender and (2) to determine the effect of breed of ram-lambs on the changes in structural, functional and motility parameters of ram-lamb semen from different breeds stored at two different concentrations at 4 degrees C for 8 days in egg-yolk based extender. Two different concentrations suitable for laparoscopic and cervical insemination were employed in this experiment. A total of 14 ram-lambs (Polled Dorset-5, Suffolk-5, Katahdin-4) with satisfactory breeding potential were selected. Semen samples were collected by electro-ejaculation. Semen samples were extended to 50 and 200 million sperm per ml with a commercial egg yolk based extender (Triladyl, Minitube of America, Verona, WI, USA) at room temperature and were stored at 4 degrees C. The sperm DNA fragmentation index (DFI), percentages of high mitochondrial membrane potential (hMMP) and plasma membrane integrity (PMI) were assessed using flow cytometry as part of structural and functional parameters on Days 0, 1, 4, 6, and 8. A computer assisted sperm analyser (HTM-IVOS, Version 10.8, Hamilton Thorne Research, Beverly, MA, USA) was used to assess the sperm motility parameters on Days 0, 1, 4, 6, and 8. PROC MIXED procedure was used to determine the effect of days of storage, concentration and breed. The concentration and days of storage significantly affected the sperm structural, functional and motility parameters (P<0.0001). Significant concentration x days of storage interaction was found for all structural and functional parameters. There was a significant concentration x days of storage interaction for average path velocity, curvilinear velocity, straightness and linearity. Overall changes in the sperm structural, functional and sperm motility parameters over the storage period were less dramatic in the 200 x 10(6) ml(-1) concentration when compared to 50 x 10(6) ml(-1) concentration. The hMMP and total progressive motility were influenced by breed. In conclusion, the quality of structural, functional and motility parameters declined as days of storage were increased and the magnitude of changes in the parameters was less dramatic at the higher concentration.

X-Ray Diffraction (XRD) Characterization Methods for Sigma=3 Twin Defects in Cubic Semiconductor (100) Wafers

NASA Technical Reports Server (NTRS)

Park, Yeonjoon (Inventor); Kim, Hyun Jung (Inventor); Skuza, Jonathan R. (Inventor); Lee, Kunik (Inventor); Choi, Sang Hyouk (Inventor); King, Glen C. (Inventor)

2017-01-01

An X-ray defraction (XRD) characterization method for sigma=3 twin defects in cubic semiconductor (100) wafers includes a concentration measurement method and a wafer mapping method for any cubic tetrahedral semiconductor wafers including GaAs (100) wafers and Si (100) wafers. The methods use the cubic semiconductor's (004) pole figure in order to detect sigma=3/{111} twin defects. The XRD methods are applicable to any (100) wafers of tetrahedral cubic semiconductors in the diamond structure (Si, Ge, C) and cubic zinc-blend structure (InP, InGaAs, CdTe, ZnSe, and so on) with various growth methods such as Liquid Encapsulated Czochralski (LEC) growth, Molecular Beam Epitaxy (MBE), Organometallic Vapor Phase Epitaxy (OMVPE), Czochralski growth and Metal Organic Chemical Vapor Deposition (MOCVD) growth.

Estimating risk of foreign exchange portfolio: Using VaR and CVaR based on GARCH-EVT-Copula model

NASA Astrophysics Data System (ADS)

Wang, Zong-Run; Chen, Xiao-Hong; Jin, Yan-Bo; Zhou, Yan-Ju

2010-11-01

This paper introduces GARCH-EVT-Copula model and applies it to study the risk of foreign exchange portfolio. Multivariate Copulas, including Gaussian, t and Clayton ones, were used to describe a portfolio risk structure, and to extend the analysis from a bivariate to an n-dimensional asset allocation problem. We apply this methodology to study the returns of a portfolio of four major foreign currencies in China, including USD, EUR, JPY and HKD. Our results suggest that the optimal investment allocations are similar across different Copulas and confidence levels. In addition, we find that the optimal investment concentrates on the USD investment. Generally speaking, t Copula and Clayton Copula better portray the correlation structure of multiple assets than Normal Copula.

Network structure and concentration fluctuations in a series of elemental, binary, and tertiary liquids and glasses.

PubMed

Soper, Alan K

2010-10-13

Liquids and glasses continue to produce a lively debate about the nature of the disordered structure in these materials, and whether it is driven by longer range concentration or density fluctuations. One factor often lacking in these studies is an overview of a wide range of structures from which common features of and differences between materials can be identified. Here I examine the structure of a wide range of chain and network, elemental, binary and tertiary liquids and glasses, using available x-ray and neutron diffraction data and combining them with empirical potential structure refinement. Calculation of the Bhatia-Thornton number-number and concentration-concentration structure factors and distribution functions highlights common structural motifs that run through many of the series. It is found that the greatest structural overlap occurs where the nearest-neighbour and second-neighbour coordination numbers are similar for different materials. As these coordination numbers increase, so the structures undergo a sequence of characteristic changes involving increasingly bent bond angle distributions and increased packing fractions. In these regards liquid and amorphous phosphorus appear to be in a structural class of their own, combining both chain-like and network-like characteristics.

Tundra fire alters stream water chemistry and benthic invertebrate communities, North Slope, Alaska

NASA Astrophysics Data System (ADS)

Allen, A. R.; Bowden, W. B.; Kling, G. W.; Schuett, E.; Kostrzewski, J. M.; Kolden Abatzoglou, C.; Findlay, R. H.

2010-12-01

Increased fire frequency and severity are potentially important consequences of climate change in high latitude ecosystems. The 2007 Anaktuvuk River fire, which burned from July until October, is the largest recorded tundra fire from Alaska's north slope (≈1,000 km2). The immediate effects of wildfire on water chemistry and biotic assemblages in tundra streams are heretofore unknown. We hypothesized that a tundra fire would increase inorganic nutrient inputs to P-limited tundra streams, increasing primary production and altering benthic macroinvertebrate community structure. We examined linkages among: 1) percentage of riparian zone and overall watershed vegetation burned, 2) physical, chemical and biological stream characteristics, and 3) macroinvertebrate communities in streams draining burned and unburned watersheds during the summers of 2008 and 2009. Streams in burned watersheds contained higher mean concentrations of soluble reactive phosphorus (SRP), ammonium (NH4+), and dissolved organic carbon (DOC). In contrast, stream nitrate (NO3-) concentrations were lower in burned watersheds. The net result was that the tundra fire did not affect concentrations of dissolved inorganic nitrogen (NH4+ + NO3-). In spite of increased SRP, benthic chlorophyll-a biomass was not elevated. Macroinvertebrate abundances were 1.5 times higher in streams draining burned watersheds; Chironomidae midges, Nematodes, and Nemoura stoneflies showed the greatest increases in abundance. Multivariate multiple regression identified environmental parameters associated with the observed changes in the macroinvertebrate communities. Since we identified stream latitude as a significant predictor variable, latitude was included in the model as a covariate. After removing the variation associated with latitude, 67.3 % of the variance in macroinvertebrate community structure was explained by a subset of 7 predictor variables; DOC, conductivity, mean temperature, NO3-, mean discharge, SRP and NH4+. The percentage of riparian vegetation burned, the percentage of watershed vegetation burned and total suspended solids were not included in the model as these parameters correlated with DOC concentration at r > 0.90. These results indicate that tundra fire not only alters stream water chemistry, it also affects benthic macroinvertebrate community structure.

XAS Studies of Arsenic in the Environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Charnock, J. M.; School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Oxford Road, Manchester, M13 9PL; Polya, D. A.

2007-02-02

Arsenic is present in low concentrations in much of the Earth's crust and changes in its speciation are vital to understanding its transport and toxicity in the environment. We have used X-ray absorption spectroscopy to investigate the coordination sites of arsenic in a wide variety of samples, including soil and earthworm tissues from arsenic-contaminated land, and human hair and nail samples from people exposed to arsenic in Cambodia. Our results confirm the effectiveness of using X-ray absorption near edge structure (XANES) and X-ray absorption fine structure (EXAFS) spectroscopy to determine speciation changes in environmental samples.

Analysis of Yb3+/Er3+-codoped microring resonator cross-grid matrices

NASA Astrophysics Data System (ADS)

Vallés, Juan A.; Gǎlǎtuş, Ramona

2014-09-01

An analytic model of the scattering response of a highly Yb3+/Er3+-codoped phosphate glass microring resonator matrix is considered to obtain the transfer functions of an M x N cross-grid microring resonator structure. Then a detailed model is used to calculate the pump and signal propagation, including a microscopic statistical formalism to describe the high-concentration induced energy-transfer mechanisms and passive and active features are combined to realistically simulate the performance as a wavelength-selective amplifier or laser. This analysis allows the optimization of these structures for telecom or sensing applications.

Fracture modes in notched angleplied composite laminates

NASA Technical Reports Server (NTRS)

Irvine, T. B.; Ginty, C. A.

1984-01-01

The Composite Durability Structural Analysis (CODSTRAN) computer code is used to determine composite fracture. Fracture modes in solid and notched, unidirectional and angleplied graphite/epoxy composites were determined by using CODSTRAN. Experimental verification included both nondestructive (ultrasonic C-Scanning) and destructive (scanning electron microscopy) techniques. The fracture modes were found to be a function of ply orientations and whether the composite is notched or unnotched. Delaminations caused by stress concentrations around notch tips were also determined. Results indicate that the composite mechanics, structural analysis, laminate analysis, and fracture criteria modules embedded in CODSTRAN are valid for determining composite fracture modes.

Modeling Fission Product Sorption in Graphite Structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szlufarska, Izabela; Morgan, Dane; Allen, Todd

2013-04-08

The goal of this project is to determine changes in adsorption and desorption of fission products to/from nuclear-grade graphite in response to a changing chemical environment. First, the project team will employ principle calculations and thermodynamic analysis to predict stability of fission products on graphite in the presence of structural defects commonly observed in very high- temperature reactor (VHTR) graphites. Desorption rates will be determined as a function of partial pressure of oxygen and iodine, relative humidity, and temperature. They will then carry out experimental characterization to determine the statistical distribution of structural features. This structural information will yield distributionsmore » of binding sites to be used as an input for a sorption model. Sorption isotherms calculated under this project will contribute to understanding of the physical bases of the source terms that are used in higher-level codes that model fission product transport and retention in graphite. The project will include the following tasks: Perform structural characterization of the VHTR graphite to determine crystallographic phases, defect structures and their distribution, volume fraction of coke, and amount of sp2 versus sp3 bonding. This information will be used as guidance for ab initio modeling and as input for sorptivity models; Perform ab initio calculations of binding energies to determine stability of fission products on the different sorption sites present in nuclear graphite microstructures. The project will use density functional theory (DFT) methods to calculate binding energies in vacuum and in oxidizing environments. The team will also calculate stability of iodine complexes with fission products on graphite sorption sites; Model graphite sorption isotherms to quantify concentration of fission products in graphite. The binding energies will be combined with a Langmuir isotherm statistical model to predict the sorbed concentration of fission products on each type of graphite site. The model will include multiple simultaneous adsorbing species, which will allow for competitive adsorption effects between different fission product species and O and OH (for modeling accident conditions).« less

Cinetica de oxidacion de polimeros conductores: poli-3,4- etilendioxitiofeno

NASA Astrophysics Data System (ADS)

Caballero Romero, Maria

Films of poly-3,4-ethylenedioxythiophene (PEDOT) perchlorate used as electrodes in liquid electrolytes incorporate anions and solvent during oxidation for charge and osmotic balance: the film swells. During reduction the film shrinks, closes its structure trapping counterions getting then rising conformational packed states by expulsion of counterions and solvent. Here by potential step from the same reduced initial state to the same oxidized final state the rate coefficient, the activation energy and reaction orders related to the counterion concentration in solution and to the concentration of active centers in the polymer film, were attained following the usual methodology used for chemical and electrochemical kinetics. Now the full methodology was repeated using different reduced-shrunk or reduced-conformational compacted initial states every time. Those initial states were attained by reduction of the oxidized film at rising cathodic potentials for the same reduction time each. Rising reduced and conformational compacted states give slower subsequent oxidation rates by potential step to the same anodic potential every time. The activation energy, the reaction coefficient and reaction orders change for rising conformational compacted initial states. Decreasing rate constants and increasing activation energies are obtained for the PEDOT oxidation from increasing conformational compacted initial states. The experimental activation energy presents two linear ranges as a function of the initial reduced-compacted state. Using as initial states for the oxidation open structures attained by reduction at low cathodic potentials, activation energies attained were constant: namely the chemical activation energy. Using as initial states for the oxidation deeper reduced, closed and packed conformational structures, the activation energy includes two components: the constant chemical energy plus the conformational energy required to relax the conformational structure generating free volume which allows the entrance of the balancing counterions required for the reaction. The conformational energy increases linearly as a function of the reduction-compaction potential. The kinetic magnitudes include conformational and structural information. The Chemical Kinetics becomes Structural (or conformational) Chemical Kinetics.

Evaluating Transport and Attenuation of Inorganic Contaminants in the Vadose Zone for Aqueous Waste Disposal Sites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Truex, Michael J.; Oostrom, Martinus; Tartakovsky, Guzel D.

An approach was developed for evaluating vadose zone transport and attenuation of aqueous wastes containing inorganic (non-volatile) contaminants that were disposed of at the land surface (i.e., directly to the ground in cribs, trenches, tile fields, etc.) and their effect on the underlying groundwater. The approach provides a structured method for estimating transport of contaminants through the vadose zone and the resulting temporal profile of groundwater contaminant concentrations. The intent of the approach is also to provide a means for presenting and explaining the results of the transport analysis in the context of the site-specific waste disposal conditions and sitemore » properties, including heterogeneities and other complexities. The document includes considerations related to identifying appropriate monitoring to verify the estimated contaminant transport and associated predictions of groundwater contaminant concentrations. While primarily intended for evaluating contaminant transport under natural attenuation conditions, the approach can also be applied to identify types of, and targets for, mitigation approaches in the vadose zone that would reduce the temporal profile of contaminant concentrations in groundwater, if needed.« less

An exonuclease I-based label-free fluorometric aptasensor for adenosine triphosphate (ATP) detection with a wide concentration range.

PubMed

Wei, Yanli; Chen, Yanxia; Li, Huanhuan; Shuang, Shaomin; Dong, Chuan; Wang, Gufeng

2015-01-15

A novel aptamer-based label-free assay for sensitive and selective detection of ATP was developed. This assay employs a new aptamer/fluorescent probe system that shows resistance to exonuclease I (Exo I) digestion upon binding to ATP molecules. In the absence of ATP, the complex between the ATP-binding aptamer (ATP-aptamer) and a DNA binding dye, berberine, is digested upon the addition of exonuclease I, leading to the release of berberine into solution and consequently, quenched berberine fluorescence. In the presence of ATP, the ATP-binding aptamer folds into a G-quadruplex structure that is resistant to Exo I digestion. Accordingly, berberine is protected in the G-quadruplex structure and high fluorescence intensity is observed. As such, based on the fluorescence signal change, a label-free fluorescence assay for ATP was developed. Factors affecting the analysis of ATP including the concentration of ATP-binding aptamer, reaction time, temperature and the concentration of Exo I were comprehensively investigated. Under optimal conditions, the fluorescence intensity of the sensing system displayed a response for ATP in a wide range up to 17.5 mM with a detection limit of 140 nM.

The mushroom ribosome-inactivating protein lyophyllin exerts deleterious effects on mouse embryonic development in vitro.

PubMed

Chan, W Y; Ng, T B; Lam, Joyce S Y; Wong, Jack H; Chu, K T; Ngai, P H K; Lam, S K; Wang, H X

2010-01-01

Earlier investigations disclose that some plant ribosome-inactivating proteins (RIPs) adversely affect mouse embryonic development. In the present study, a mushroom RIP, namely lyophyllin from Lyophyllum shimeji, was isolated, partially sequenced, and its translation inhibitory activity determined. Its teratogenicity was studied by using a technique entailing microinjection and postimplantation whole-embryo culture. It was found that embryonic abnormalities during the period of organogenesis from E8.5 to E9.5 were induced by lyophyllin at a concentration as low as 50 microg/ml, and when the lyophyllin concentration was raised, the number of abnormal embryos increased, the final somite number decreased, and the abnormalities increased in severity. The affected embryonic structures included the cranial neural tube, forelimb buds, branchial arches, and body axis, while optic and otic placodes were more resistant. Lyophyllin at a concentration higher than 500 microg/ml also induced forebrain blisters within the cranial mesenchyme. When the abnormal embryos were examined histologically, an increase of cell death was found to be associated with abnormal structures, indicating that cell death may be one of the underlying causes of teratogenicity of the mushroom RIP. This constitutes the first report on the teratogenicity of a mushroom RIP.

Mechanistic Effects of Porosity on Structural Composite Materials

NASA Astrophysics Data System (ADS)

Siver, Andrew

As fiber reinforced composites continue to gain popularity as primary structures in aerospace, automotive, and powersports industries, quality control becomes an extremely important aspect of materials and mechanical engineering. The ability to recognize and control manufacturing induced defects can greatly reduce the likelihood of unexpected catastrophic failure. Porosity is the result of trapped volatiles or air bubbles during the layup process and can significantly compromise the strength of fiber reinforced composites. A comprehensive study was performed on an AS4C-UF3352 TCR carbon fiber-epoxy prepreg system to determine the effect of porosity on flexural, shear, low-velocity impact, and damage residual strength properties. Autoclave cure pressure was controlled to induce varying levels of porosity to construct six laminates with porosity concentrations between 0-40%. Porosity concentrations were measured using several destructive and nondestructive techniques including resin burnoff, sectioning and optical analysis, and X-ray computed tomography (CT) scanning. Ultrasonic transmission, thermography, and CT scanning provided nondestructive imaging to evaluate impact damage. A bilinear relationship accurately characterizes the change in mechanical properties with increasing porosity. Strength properties are relatively unaffected when porosity concentrations are below approximately 2.25% and decrease linearly by up to 40% in high porosity specimens.

Systematic review of the concentrations of oligosaccharides in human milk

PubMed Central

Thurl, Stephan; Munzert, Manfred; Boehm, Günther; Matthews, Catherine; Stahl, Bernd

2017-01-01

Context Oligosaccharides are the third largest solid component in human milk. These diverse compounds are thought to have numerous beneficial functions in infants, including protection against infectious diseases. The structures of more than 100 oligosaccharides in human milk have been elucidated so far. Objective The aim of this review was to identify the main factors that affect the concentrations of oligosaccharides in human milk and to determine whether it is possible to calculate representative and reliable mean concentrations. Data Sources A comprehensive literature search on oligosaccharide concentrations in human milk was performed in 6 electronic databases: BIOSIS, Current Contents Search, Embase, Lancet Titles, MEDLINE and PubMed. Study Selection The initial search resulted in 1363 hits. After the elimination of duplicates, the literature was screened. The application of strict inclusion criteria resulted in 21 articles selected. Data Extraction Oligosaccharide concentrations, both mean values and single values, reported in the literature were sorted by gestational age, secretor status of mothers, and defined lactation periods. Results Mean concentrations, including confidence limits, of 33 neutral and acidic oligosaccharides reported could be calculated. Concentrations of oligosaccharides in human milk show variations that are dependent on both the secretor type of the mother and the lactation period as examined by analyses of variance. In addition, large interlaboratory variations in the data were observed. Conclusions Worldwide interlaboratory quantitative analyses of identical milk samples would be required to identify the most reliable methods of determining concentrations of oligosaccharides in human milk. The data presented here contribute to the current knowledge about the composition and quantities of oligosaccharides in human milk and may foster greater understanding of the biological functions of these compounds. PMID:29053807

Systematic review of the concentrations of oligosaccharides in human milk.

PubMed

Thurl, Stephan; Munzert, Manfred; Boehm, Günther; Matthews, Catherine; Stahl, Bernd

2017-11-01

Oligosaccharides are the third largest solid component in human milk. These diverse compounds are thought to have numerous beneficial functions in infants, including protection against infectious diseases. The structures of more than 100 oligosaccharides in human milk have been elucidated so far. The aim of this review was to identify the main factors that affect the concentrations of oligosaccharides in human milk and to determine whether it is possible to calculate representative and reliable mean concentrations. A comprehensive literature search on oligosaccharide concentrations in human milk was performed in 6 electronic databases: BIOSIS, Current Contents Search, Embase, Lancet Titles, MEDLINE and PubMed. The initial search resulted in 1363 hits. After the elimination of duplicates, the literature was screened. The application of strict inclusion criteria resulted in 21 articles selected. Oligosaccharide concentrations, both mean values and single values, reported in the literature were sorted by gestational age, secretor status of mothers, and defined lactation periods. Mean concentrations, including confidence limits, of 33 neutral and acidic oligosaccharides reported could be calculated. Concentrations of oligosaccharides in human milk show variations that are dependent on both the secretor type of the mother and the lactation period as examined by analyses of variance. In addition, large interlaboratory variations in the data were observed. Worldwide interlaboratory quantitative analyses of identical milk samples would be required to identify the most reliable methods of determining concentrations of oligosaccharides in human milk. The data presented here contribute to the current knowledge about the composition and quantities of oligosaccharides in human milk and may foster greater understanding of the biological functions of these compounds. © The Author(s) 2017. Published by Oxford University Press on behalf of the International Life Sciences Institute.

Terminal-oriented computer-communication networks.

NASA Technical Reports Server (NTRS)

Schwartz, M.; Boorstyn, R. R.; Pickholtz, R. L.

1972-01-01

Four examples of currently operating computer-communication networks are described in this tutorial paper. They include the TYMNET network, the GE Information Services network, the NASDAQ over-the-counter stock-quotation system, and the Computer Sciences Infonet. These networks all use programmable concentrators for combining a multiplicity of terminals. Included in the discussion for each network is a description of the overall network structure, the handling and transmission of messages, communication requirements, routing and reliability consideration where applicable, operating data and design specifications where available, and unique design features in the area of computer communications.

Rare Earth Element and Trace Element Data Associated with Hydrothermal Spring Reservoir Rock, Idaho

DOE Data Explorer

Quillinan, Scott; Bagdonas, Davin

2017-06-22

These data represent rock samples collected in Idaho that correspond with naturally occurring hydrothermal samples that were collected and analyzed by INL (Idaho Falls, ID). Representative samples of type rocks were selected to best represent the various regions of Idaho in which naturally occurring hydrothermal waters occur. This includes the Snake River Plain (SRP), Basin and Range type structures east of the SRP, and large scale/deep seated orogenic uplift of the Sawtooth Mountains, ID. Analysis includes ICP-OES and ICP-MS methods for Major, Trace, and REE concentrations.

Metabolism of organic acids, nitrogen and amino acids in chlorotic leaves of 'Honeycrisp' apple (Malus domestica Borkh) with excessive accumulation of carbohydrates.

PubMed

Wang, Huicong; Ma, Fangfang; Cheng, Lailiang

2010-07-01

Metabolite profiles and activities of key enzymes in the metabolism of organic acids, nitrogen and amino acids were compared between chlorotic leaves and normal leaves of 'Honeycrisp' apple to understand how accumulation of non-structural carbohydrates affects the metabolism of organic acids, nitrogen and amino acids. Excessive accumulation of non-structural carbohydrates and much lower CO(2) assimilation were found in chlorotic leaves than in normal leaves, confirming feedback inhibition of photosynthesis in chlorotic leaves. Dark respiration and activities of several key enzymes in glycolysis and tricarboxylic acid (TCA) cycle, ATP-phosphofructokinase, pyruvate kinase, citrate synthase, aconitase and isocitrate dehydrogenase were significantly higher in chlorotic leaves than in normal leaves. However, concentrations of most organic acids including phosphoenolpyruvate (PEP), pyruvate, oxaloacetate, 2-oxoglutarate, malate and fumarate, and activities of key enzymes involved in the anapleurotic pathway including PEP carboxylase, NAD-malate dehydrogenase and NAD-malic enzyme were significantly lower in chlorotic leaves than in normal leaves. Concentrations of soluble proteins and most free amino acids were significantly lower in chlorotic leaves than in normal leaves. Activities of key enzymes in nitrogen assimilation and amino acid synthesis, including nitrate reductase, glutamine synthetase, ferredoxin and NADH-dependent glutamate synthase, and glutamate pyruvate transaminase were significantly lower in chlorotic leaves than in normal leaves. It was concluded that, in response to excessive accumulation of non-structural carbohydrates, glycolysis and TCA cycle were up-regulated to "consume" the excess carbon available, whereas the anapleurotic pathway, nitrogen assimilation and amino acid synthesis were down-regulated to reduce the overall rate of amino acid and protein synthesis.

Optimal condition for fabricating superhydrophobic Aluminum surfaces with controlled anodizing processes

NASA Astrophysics Data System (ADS)

Saffari, Hamid; Sohrabi, Beheshteh; Noori, Mohammad Reza; Bahrami, Hamid Reza Talesh

2018-03-01

A single step anodizing process is used to produce micro-nano structures on Aluminum (1050) substrates with sulfuric acid as electrolyte. Therefore, surface energy of the anodized layer is reduced using stearic acid modification. Undoubtedly, effects of different parameters including anodizing time, electrical current, and type and concentration of electrolyte on the final contact angle are systemically studied and optimized. Results show that anodizing current of 0.41 A, electrolyte (sulfuric acid) concentration of 15 wt.% and anodizing time of 90 min are optimal conditions which give contact angle as high as 159.2° and sliding angle lower than 5°. Moreover, the study reveals that adding oxalic acid to the sulfuric acid cannot enhance superhydrophobicity of the samples. Also, scanning electron microscopy images of samples show that irregular (bird's nest) structures present on the surface instead of high-ordered honeycomb structures expecting from normal anodizing process. Additionally, X-ray diffraction analysis of the samples shows that only amorphous structures present on the surface. The Brunauer-Emmett-Teller (BET) specific surface area of the anodized layer is 2.55 m2 g-1 in optimal condition. Ultimately, the surface keeps its hydrophobicity in air and deionized water (DIW) after one week and 12 weeks, respectively.

STUDIES OF METABOLITE-PROTEIN INTERACTIONS: A REVIEW

PubMed Central

Matsuda, Ryan; Bi, Cong; Anguizola, Jeanethe; Sobansky, Matthew; Rodriquez, Elliot; Badilla, John Vargas; Zheng, Xiwei; Hage, Benjamin; Hage, David S.

2014-01-01

The study of metabolomics can provide valuable information about biochemical pathways and processes at the molecular level. There have been many reports that have examined the structure, identity and concentrations of metabolites in biological systems. However, the binding of metabolites with proteins is also of growing interest. This review examines past reports that have looked at the binding of various types of metabolites with proteins. An overview of the techniques that have been used to characterize and study metabolite-protein binding is first provided. This is followed by examples of studies that have investigated the binding of hormones, fatty acids, drugs or other xenobiotics, and their metabolites with transport proteins and receptors. These examples include reports that have considered the structure of the resulting solute-protein complexes, the nature of the binding sites, the strength of these interactions, the variations in these interactions with solute structure, and the kinetics of these reactions. The possible effects of metabolic diseases on these processes, including the impact of alterations in the structure and function of proteins, are also considered. PMID:24321277

Life extension of Structural Repairs – A statistical approach towards efficiency improvement

NASA Astrophysics Data System (ADS)

Deepashri, N. V.; Kalaiyappan, Mohan

2018-05-01

The life extension program of aircraft is taken up whenever aircraft’s intended life reaches close to its DSG (Design Service Goal). The Extended Service Goal (ESG) of an aircraft, in general, and structural repairs, in particular, is arrived at on the basis of F&DT (Fatigue & Damage Tolerance) analysis. Life extension program of aircraft consists of assessment of remaining life of all parts of the aircrafts including structural, mechanical, and electrical and avionics equipment and structural repairs. For life extension of stringer repair, as an example, it is required to re-assess the fatigue life of stringer in the presence of coupling under modified load spectrum. This is achieved by assessing the fatigue life of Web and Outer Flange (OF) part of stringers separately as per F&DT justification philosophy. Assessment of the fatigue life requires determination of stress concentration factor (Kt) for different combination of width, pitch, stringer thickness, coupling thickness and pad-up thickness of all stringer profiles available in different sections of fuselage. Determination of stress concentration factor for Web and Outer Flange of stringer profile covering entire ranges involves substantial number of Finite Element (FE) analysis. In order to optimise the number of FE runs, stress concentration factor is determined under worst repair factors combination (max. plate width; max. thickness; max. pitch; min. rivet dia.; and min. No. of rivets) resulting in conservative value. A parametric study of Web and Outer Flange data across stringer profiles were carried out and proven statistical techniques were used to find the optimal equation to predict stress concentration factor. This in turn reduced number of FE runs substantially for a given range of width, pitch, stringer thickness and so on. The use of optimal equation obtained through regression analysis is able to predict Kt within reasonable accuracy for a given range of inputs.

Fluid density and concentration measurement using noninvasive in situ ultrasonic resonance interferometry

DOEpatents

Pope, Noah G.; Veirs, Douglas K.; Claytor, Thomas N.

1994-01-01

The specific gravity or solute concentration of a process fluid solution located in a selected structure is determined by obtaining a resonance response spectrum of the fluid/structure over a range of frequencies that are outside the response of the structure itself. A fast fourier transform (FFT) of the resonance response spectrum is performed to form a set of FFT values. A peak value for the FFT values is determined, e.g., by curve fitting, to output a process parameter that is functionally related to the specific gravity and solute concentration of the process fluid solution. Calibration curves are required to correlate the peak FFT value over the range of expected specific gravities and solute concentrations in the selected structure.

Fluid density and concentration measurement using noninvasive in situ ultrasonic resonance interferometry

DOEpatents

Pope, N.G.; Veirs, D.K.; Claytor, T.N.

1994-10-25

The specific gravity or solute concentration of a process fluid solution located in a selected structure is determined by obtaining a resonance response spectrum of the fluid/structure over a range of frequencies that are outside the response of the structure itself. A fast Fourier transform (FFT) of the resonance response spectrum is performed to form a set of FFT values. A peak value for the FFT values is determined, e.g., by curve fitting, to output a process parameter that is functionally related to the specific gravity and solute concentration of the process fluid solution. Calibration curves are required to correlate the peak FFT value over the range of expected specific gravities and solute concentrations in the selected structure. 7 figs.

Blue phase liquid crystal phase transition for cyano compound chiral nematic liquid crystal mixtures with three two-ring core structures and chiral dopant concentrations

NASA Astrophysics Data System (ADS)

Shin, Jaesun; Kim, Beomjong; Jung, Wansu; Fahad, Mateen; Park, SangJin; Hong, Sung-Kyu

2017-05-01

Blue phase (BP) temperature range of a chiral nematic liquid crystal (LC) mixture is dependent upon the host nematic LC chemical structure and chiral dopant concentration. In this study, we investigated BP phase transition behaviour and helical twisting power (HTP) using three chiral dopant concentrations of cyano compound chiral nematic LC mixtures incorporating three two-ring core structures in the host nematic LCs. The effect of the host nematic LC core structure, HTP and chiral dopant concentrations were considered on BP temperature ranges, for two types of complete BPI and BPII without isotropic phase (Iso) and two types of coexistence state of BPI+Iso and BPII+Iso.

Dynamics from Seconds to Hours in Hodgkin-Huxley Model with Time-Dependent Ion Concentrations and Buffer Reservoirs

PubMed Central

Hübel, Niklas; Dahlem, Markus A.

2014-01-01

The classical Hodgkin-Huxley (HH) model neglects the time-dependence of ion concentrations in spiking dynamics. The dynamics is therefore limited to a time scale of milliseconds, which is determined by the membrane capacitance multiplied by the resistance of the ion channels, and by the gating time constants. We study slow dynamics in an extended HH framework that includes time-dependent ion concentrations, pumps, and buffers. Fluxes across the neuronal membrane change intra- and extracellular ion concentrations, whereby the latter can also change through contact to reservoirs in the surroundings. Ion gain and loss of the system is identified as a bifurcation parameter whose essential importance was not realized in earlier studies. Our systematic study of the bifurcation structure and thus the phase space structure helps to understand activation and inhibition of a new excitability in ion homeostasis which emerges in such extended models. Also modulatory mechanisms that regulate the spiking rate can be explained by bifurcations. The dynamics on three distinct slow times scales is determined by the cell volume-to-surface-area ratio and the membrane permeability (seconds), the buffer time constants (tens of seconds), and the slower backward buffering (minutes to hours). The modulatory dynamics and the newly emerging excitable dynamics corresponds to pathological conditions observed in epileptiform burst activity, and spreading depression in migraine aura and stroke, respectively. PMID:25474648

Numerical Analysis of Stress Concentration in Isotropic and Laminated Plates with Inclined Elliptical Holes

NASA Astrophysics Data System (ADS)

Khechai, Abdelhak; Tati, Abdelouahab; Belarbi, Mohamed Ouejdi; Guettala, Abdelhamid

2018-03-01

The design of high-performance composite structures frequently includes discontinuities to reduce the weight and fastener holes for joining. Understanding the behavior of perforated laminates is necessary for structural design. In the current work, stress concentrations taking place in laminated and isotropic plates subjected to tensile load are investigated. The stress concentrations are obtained using a recent quadrilateral finite element of four nodes with 32 DOFs. The present finite element (PE) is a combination of two finite elements. The first finite element is a linear isoparametric membrane element and the second is a high precision Hermitian element. One of the essential objectives of the current investigation is to confirm the capability and efficiency of the PE for stress determination in perforated laminates. Different geometric parameters, such as the cutout form, sizes and cutout orientations, which have a considerable effect on the stress values, are studied. Using the present finite element formulation, the obtained results are found to be in good agreement with the analytical findings, which validates the capability and the efficiency of the proposed formulation. Finally, to understand the material parameters effect such as the orientation of fibers and degree of orthotropy ratio on the stress values, many figures are presented using different ellipse major to minor axis ratio. The stress concentration values are considerably affected by increasing the orientation angle of the fibers and degree of orthotropy.

Hairy and Slippery Polyoxazoline-Based Copolymers on Model and Cartilage Surfaces.

PubMed

Morgese, Giulia; Ramakrishna, Shivaprakash N; Simic, Rok; Zenobi-Wong, Marcy; Benetti, Edmondo M

2018-02-12

Comb-like polymers presenting a hydroxybenzaldehyde (HBA)-functionalized poly(glutamic acid) (PGA) backbone and poly(2-methyl-2-oxazoline) (PMOXA) side chains chemisorb on aminolized substrates, including cartilage surfaces, forming layers that reduce protein contamination and provide lubrication. The structure, physicochemical, biopassive, and tribological properties of PGA-PMOXA-HBA films are finely determined by the copolymer architecture, its reactivity toward the surface, i.e. PMOXA side-chain crowding and HBA density, and by the copolymer solution concentration during assembly. Highly reactive species with low PMOXA content form inhomogeneous layers due to the limited possibility of surface rearrangements by strongly anchored copolymers, just partially protecting the functionalized surface from protein contamination and providing a relatively weak lubrication on cartilage. Biopassivity and lubrication can be improved by increasing copolymer concentration during assembly, leading to a progressive saturation of surface defects across the films. In a different way, less reactive copolymers presenting high PMOXA side-chain densities form uniform, biopassive, and lubricious films, both on model aminolized silicon oxide surfaces, as well as on cartilage substrates. When assembled at low concentrations these copolymers adopt a "lying down" conformation, i.e. adhering via their backbones onto the substrates, while at high concentrations they undergo a conformational transition, assuming a more densely packed, "standing up" structure, where they stretch perpendicularly from the substrate. This specific arrangement reduces protein contamination and improves lubrication both on model as well as on cartilage surfaces.

Structural transition of glucagon in the concentrated solution observed by electrophoretic and spectroscopic techniques.

PubMed

Onoue, Satomi; Iwasa, Sumiko; Kojima, Takashi; Katoh, Fumie; Debari, Kazuhiro; Koh, Keitatsu; Matsuda, Yoshihisa; Yajima, Takehiko

2006-03-24

Glucagon, a polypeptide hormone consisting of 29 amino acid residues, tends to form gel-like fibrillar aggregates, and the glucagon fibril, as well as other pathologically related fibrils including prion, amylin, and beta-amyloid, have been found to be cytotoxic through the activation of apoptotic signaling pathways. To understand the aggregation properties of glucagon fibril, we have characterized and compared the physicochemical properties of glucagon, secretin, a member of the glucagon superfamily, and amylin using analytical techniques including capillary electrophoresis (CE), circular dichroism (CD), FT-IR, FT-Raman, transmission electron microscopy (TEM), and beta-sheet-imaging probe. Aging treatment of glucagon resulted in the formation of fibrillar aggregates in time- and concentration-dependent manner, and FT-IR and FT-Raman analyses showed the spectral shift of amide I band, suggesting the conformational changes from alpha-helix to beta-sheet structure. Interestingly, secretin, having high sequential and secondary structural homology with glucagon, did not generate the fibrillar aggregates at the conditions tested. In addition, we evaluated the association state of glucagon at various pHs raging from pH 2.0 to 3.5 using CE. Based on the CE data, the rate constants of glucagon aggregation were calculated to be 0.002 +/- 0.004/h and 0.080 +/- 0.011/h for aging at pH 2.0 and 3.5, respectively, suggesting the pH dependence of self-association. CE showed the potential to separate and detect the glucagon aggregates and intermediates during aging process.

Protocols for self-assembly and imaging of DNA nanostructures.

PubMed

Sobey, Thomas L; Simmel, Friedrich C

2011-01-01

Programed molecular structures allow us to research and make use of physical, chemical, and biological effects at the nanoscale. They are an example of the "bottom-up" approach to nanotechnology, with structures forming through self-assembly. DNA is a particularly useful molecule for this purpose, and some of its advantages include parallel (as opposed to serial) assembly, naturally occurring "tools," such as enzymes and proteins for making modifications and attachments, and structural dependence on base sequence. This allows us to develop one, two, and three dimensional structures that are interesting for their fundamental physical and chemical behavior, and for potential applications such as biosensors, medical diagnostics, molecular electronics, and efficient light-harvesting systems. We describe five techniques that allow one to assemble and image such structures: concentration measurement by ultraviolet absorption, titration gel electrophoresis, thermal annealing, fluorescence microscopy, and atomic force microscopy in fluids.

Validating bioindicators of PAH effects in fish: Evaluating responsiveness to creosote exposure in aquatic mesocosms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Munro, K.A.; Solomon, K.R.; Gensemer, R.W.

1994-12-31

While studies involving controlled exposures to PAHs have typically studied the effects of exposure to individual compounds, PAHs are usually present in the environment in complex mixtures. Some of these (eg. creosote) have been widely used and present potential risks to aquatic ecosystems. The objective of the current research is to evaluate whether population effects visible in fish at high creosote concentrations would be reflected in biomarker responses at lower concentrations. Goldfish (Carassius auratus) were exposed to five levels of creosote contamination in microcosms containing a simple community structure (including macroinvertebrates and macrophytes). Preliminary results have shown that changes inmore » P450 induction, bile fluorescence, and levels of reproductive hormones are visible at lower concentrations than population effects such as increased mortality, reduced secondary sexual characteristics, and reduced fecundity.« less

Structural and phase transition changes of sodium dodecyl sulfate micellar solution in alcohols probed by small-angle neutron scattering (SANS)

NASA Astrophysics Data System (ADS)

Putra, Edy Giri Rachman; Patriati, Arum

2015-04-01

Small-angle neutron scattering (SANS) measurements on 0.3M sodium dodecyl sulfate (SDS) micellar solutions have been performed in the presence of n-alcohols, from ethanol to decanol at different alcohol concentrations, 2-10 wt%. The ellipsoid micellar structure which occurred in the 0.3M SDS in aqueous solution with the size range of 30-50 Å has different behavior at various hydrocarbon chain length and concentration of alcohols. At low concentration and short chain-length of alcohols, such as ethanol, propanol, and butanol, the size of micelles reduced and had a spherical-like structure. The opposite effect occurred as medium to long chain alcohols, such as hexanol, octanol and decanol was added into the 0.3M SDS micellar solutions. The micelles structure changed to be more elongated in major axis and then crossed the critical phase transition from micellar solution into liquid crystal phase as lamellar structure emerged by further addition of alcohols. The inter-lamellar distances were also depending on the hydrocarbon chain length and concentration of alcohols. In the meantime, the persistent micellar structures occurred in addition of medium chain of n-alcohol, pentanol at all concentrations.

Miniature Tunable Laser Spectrometer for Detection of a Trace Gas

NASA Technical Reports Server (NTRS)

Christensen, Lance E. (Inventor)

2017-01-01

An open-path laser spectrometer (OPLS) for measuring a concentration of a trace gas, the OPLS including an open-path multi-pass analysis region including a first mirror, a second mirror at a distance and orientation from the first mirror, and a support structure for locating the mirrors, a laser coupled to the analysis region and configured to emit light of a wavelength range and to enable a plurality of reflections of the emitted light between the mirrors, a detector coupled to the analysis region and configured to detect a portion of the emitted light impinging on the detector and to generate a corresponding signal, and an electronic system coupled to the laser and the detector, and configured to adjust the wavelength range of the emitted light from the laser based on the generated signal, and to measure the concentration of the trace gas based on the generated signal.

Effects of molecular composition of natural organic matter on ferric iron complexation at circumneutral pH.

PubMed

Fujii, Manabu; Imaoka, Akira; Yoshimura, Chihiro; Waite, T D

2014-04-15

Thermodynamic and kinetic parameters for ferric iron (Fe[III]) complexation by well-characterized humic substances (HS) from various origins were determined by a competitive ligand method with 5-sulfosalicylic acid at circumneutral pH (6.0-8.0) and an ionic strength of ∼0.06 M. The measured Fe binding properties including conditional stability constants and complexation capacities ranged over more than 2 orders of magnitude, depending on the origin and the particular operationally defined fraction of HS examined. Statistical comparison of the complexation parameters to a range of chemical properties of the HS indicated a strong positive correlation between Fe(III) complexation capacity and aromatic carbon content in the HS at all pHs examined. In contrast, the complexation capacity was determined to be up to a few orders of magnitude smaller than the concentration of carboxylic and phenolic groups present. Therefore, specific functional groups including those resident in the proximity of aromatic structures within the HS are likely preferable for Fe(III) coordination under the conditions examined. Overall, our results suggest that the concentration of dissolved Fe(III) complexes in natural waters is substantially influenced by variation in HS characteristics in addition to other well-known factors such as HS concentration and nature and concentration of competing cations present.

The Myszkow porphyry copper-molybdenum deposit, Poland

USGS Publications Warehouse

Chaffee, M.A.; Eppinger, R.G.; Lason, K.; Slosarz, J.; Podemski, M.

1994-01-01

The porphyry copper-molybdenum deposit at Myszkow, south-central Poland, lies in the Cracow-Silesian orogenic belt, in the vicinity of a Paleozoic boundary between two tectonic plates. The deposit is hosted in a complex that includes early Paleozoic metasedimentary rocks intruded in the late Paleozoic by a predominantly granodioritic pluton. This deposit exhibits many features that are typical of porphyry copper deposits associated with calc-alkaline intrusive rocks, including ore- and alteration-mineral suites, zoning of ore and alteration minerals, fluid-inclusion chemistry, tectonic setting, and structural style of veining. Unusual features of the Myszkow deposit include high concentrations of tungsten and the late Paleozoic (Variscan) age. -Authors

Advanced technology commercial fuselage structure

NASA Technical Reports Server (NTRS)

Ilcewicz, L. B.; Smith, P. J.; Walker, T. H.; Johnson, R. W.

1991-01-01

Boeing's program for Advanced Technology Composite Aircraft Structure (ATCAS) has focused on the manufacturing and performance issues associated with a wide body commercial transport fuselage. The primary goal of ATCAS is to demonstrate cost and weight savings over a 1995 aluminum benchmark. A 31 foot section of fuselage directly behind the wing to body intersection was selected for study purposes. This paper summarizes ATCAS contract plans and review progress to date. The six year ATCAS program will study technical issues for crown, side, and keel areas of the fuselage. All structural details in these areas will be included in design studies that incorporate a design build team (DBT) approach. Manufacturing technologies will be developed for concepts deemed by the DBT to have the greatest potential for cost and weight savings. Assembly issues for large, stiff, quadrant panels will receive special attention. Supporting technologies and mechanical tests will concentrate on the major issues identified for fuselage. These include damage tolerance, pressure containment, splices, load redistribution, post-buckled structure, and durability/life. Progress to date includes DBT selection of baseline fuselage concepts; cost and weight comparisons for crown panel designs; initial panel fabrication for manufacturing and structural mechanics research; and toughened material studies related to keel panels. Initial ATCAS studies have shown that NASA's Advanced Composite Technology program goals for cost and weight savings are attainable for composite fuselage.

Zero torque gear head wrench

NASA Technical Reports Server (NTRS)

Mcdougal, A. R.; Norman, R. M. (Inventor)

1976-01-01

A gear head wrench particularly suited for use in applying torque to bolts without transferring torsional stress to bolt-receiving structures is introduced. The wrench is characterized by a coupling including a socket, for connecting a bolt head with a torque multiplying gear train, provided within a housing having an annulus concentrically related to the socket and adapted to be coupled with a spacer interposed between the bolt head and the juxtaposed surface of the bolt-receiving structure for applying a balancing counter-torque to the spacer as torque is applied to the bolt head whereby the bolt-receiving structure is substantially isolated from torsional stress. As a result of the foregoing, the operator of the wrench is substantially isolated from any forces which may be imposed.

Micromechanics of Sea Urchin spines.

PubMed

Tsafnat, Naomi; Fitz Gerald, John D; Le, Hai N; Stachurski, Zbigniew H

2012-01-01

The endoskeletal structure of the Sea Urchin, Centrostephanus rodgersii, has numerous long spines whose known functions include locomotion, sensing, and protection against predators. These spines have a remarkable internal microstructure and are made of single-crystal calcite. A finite-element model of the spine's unique porous structure, based on micro-computed tomography (microCT) and incorporating anisotropic material properties, was developed to study its response to mechanical loading. Simulations show that high stress concentrations occur at certain points in the spine's architecture; brittle cracking would likely initiate in these regions. These analyses demonstrate that the organization of single-crystal calcite in the unique, intricate morphology of the sea urchin spine results in a strong, stiff and lightweight structure that enhances its strength despite the brittleness of its constituent material.

Structural and viscoelastic characterization of ternary mixtures of sunflower oil, saturated monoglycerides and aqueous phases containing different bases.

PubMed

Valoppi, Fabio; Calligaris, Sonia; Barba, Luisa; Nicoli, Maria Cristina

2015-08-01

The structure at different length scales and the viscoelastic properties of ternary mixtures composed of saturated monoglycerides, sunflower oil and aqueous solutions of weak bases (KHCO 3 , NaHCO 3 , and NH 4 HCO 3 ) or strong bases (NaOH and KOH) were investigated. The characteristics of ternary mixtures were studied systematically by using polarized light microscopy, differential scanning calorimetry (DSC), synchrotron X-ray diffraction (XRD) and rheological analysis. Results showed that the base type and concentration greatly affected the structure of the mixtures. The use of strong bases allowed gelled systems to be obtained only at low concentrations (<10mM). On the contrary, the presence of weak bases induced gelling at all concentrations considered (from 1 to 1000mM). The increase of base concentration led to a reduction of the mean droplet diameter and melting temperature. At the same time, the viscoelastic characteristics as a function of base concentration followed a more complex behavior: G' and G″ progressively decreased as the salt concentration increased in a concentration range from 1 to 100mM, while the rheological parameters increased when salt concentration increased from 100 to 1000mM. The structural and viscoelastic behavior of systems prepared with different salts were commonly independent of the cation present in the medium. Results highlight that it is possible to tailor the structure of these gels by using specific bases. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fabrication of Graded Porous and Skin-Core Structure RDX-Based Propellants via Supercritical CO2 Concentration Profile

NASA Astrophysics Data System (ADS)

Yang, Weitao; Li, Yuxiang; Ying, Sanjiu

2015-04-01

A fabrication process to produce graded porous and skin-core structure propellants via supercritical CO2 concentration profile is reported in this article. It utilizes a partial gas saturation technique to obtain nonequilibrium gas concentration profiles in propellants. Once foamed, the propellant obtains a graded porous or skin-pore structure. This fabrication method was studied with RDX(Hexogen)-based propellant under an SC-CO2 saturation condition. The principle was analyzed and the one-dimensional diffusion model was employed to estimate the gas diffusion coefficient and to predict the gas concentration profiles inside the propellant. Scanning electron microscopy images were used to analyze the effects of partial saturation on the inner structure. The results also suggested that the sorption time and desorption time played an important role in gas profile generation and controlled the inner structure of propellants.

Effect of BaTiO3 Nanopowder Concentration on Rheological Behaviour of Ceramic Inkjet Inks

NASA Astrophysics Data System (ADS)

Kyrpal, R.; Dulina, I.; Ragulya, A.

2015-04-01

The relationship between rheological properties of ceramic inkjet inks based on BaTiO3 nanopowder and solid phase concentration has been investigated. In the ink volume takes place the formation periodic colloidal structures (PCS). The determining factor of structure formation is powder-dispersant ratio. Structural constitution of in the system with the low pigment concentration represented as PCS2, that contains solid particles in deflocculated that stabilized by the presence of adsorption-solvate layers. Dilatant structure formation for such inks explained by constrained conditions of the interaction. Samples with high BaTiO3 concentration have been classified as PKS1. Dilatant properties of the PKS1 resulted in particles rearrangement under the influence of the flow. In the region of some values powder-dispersant ratio take place conversation PKS2 to PKS1 and ink structure transformation from monodisperse to aggregate state.

Evaluation of Antioxidant Activity and Growth Control Properties of Nonoscale Structure Produced from Aloe vera var. littoralis Extract on Clinical Isolates of Salmonella.

PubMed

Ranjbar, Reza; Arjomandzadegan, Mohammad; Hosseiny, Hossein

2017-07-31

The aim of the study was to examine antibacterial properties of microemulsion structure produced from Aloe vera var. littoralis extract as a new tool of nanoscale drug-like materials. Aloe vera var. littoralis ( A. littoralis ) extract was prepared by distillation method. A nonocarrier structure in the microemulsion system was prepared from the extract. Serial concentrations were prepared from 8 mg/mL extract and the nonocarrier containing 0.1 mg/mL pure extract and were evaluated by a disk diffusion method for 35 Salmonella clinical isolates. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by microbroth dilution assay using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method by an enzyme-linked immunosorbent assay(ELISA) Microplate Reader apparatus. Antioxidant activity of the extract was determined by measuring the ferric reducing ability of plasma (FRAP) assay. From 35 clinical isolates of Salmonella , 17 isolates-including resistant isolates of S.E.1103 and S.E.49-had a zone of inhibition (ZI) of 7 to 32 mm in 0.007 mg/mL of the extract. S.E.76 isolate exposed to 30 µg/mL ceftazidime disk had a ZI of 12 mm but had 10 mm in 7µg/mL of A. littoralis extract. The inhibitory effect of a nanocarrier at a concentration of 25 µg/mL by 20 mm ZI was comparable by the ceftazidime (30 µg/mL) effect. MIC 50 was 0.25 mg/mL and MBC 50 was 0.5 mg/mL by MTT method for the extract. It was shown that A.littoralis extract had antioxidant activity of 31.67 µM/mg that could be increased based on concentration. It was concluded that the nanocarrier had a significant effect on the studied isolates in comparison with ordinary antibiotics and had potential for use as a natural antioxidant and antimicrobial material in complementary medicine.

Anatomy of Old Faithful From Subsurface Seismic Imaging of the Yellowstone Upper Geyser Basin

NASA Astrophysics Data System (ADS)

Wu, Sin-Mei; Ward, Kevin M.; Farrell, Jamie; Lin, Fan-Chi; Karplus, Marianne; Smith, Robert B.

2017-10-01

The Upper Geyser Basin in Yellowstone National Park contains one of the highest concentrations of hydrothermal features on Earth including the iconic Old Faithful geyser. Although this system has been the focus of many geological, geochemical, and geophysical studies for decades, the shallow (<200 m) subsurface structure remains poorly characterized. To investigate the detailed subsurface geologic structure including the hydrothermal plumbing of the Upper Geyser Basin, we deployed an array of densely spaced three-component nodal seismographs in November of 2015. In this study, we extract Rayleigh wave seismic signals between 1 and 10 Hz utilizing nondiffusive seismic waves excited by nearby active hydrothermal features with the following results: (1) imaging the shallow subsurface structure by utilizing stationary hydrothermal activity as a seismic source, (2) characterizing how local geologic conditions control the formation and location of the Old Faithful hydrothermal system, and (3) resolving a relatively shallow (10-60 m) and large reservoir located 100 m southwest of Old Faithful geyser.

Probe for contamination detection in recyclable materials

DOEpatents

Taleyarkhan, Rusi

2003-08-05

A neutron detection system for detection of contaminants contained within a bulk material during recycling includes at least one neutron generator for neutron bombardment of the bulk material, and at least one gamma ray detector for detection of gamma rays emitted by contaminants within the bulk material. A structure for analyzing gamma ray data is communicably connected to the gamma ray detector, the structure for analyzing gamma ray data adapted. The identity and concentration of contaminants in a bulk material can also be determined. By scanning the neutron beam, discrete locations within the bulk material having contaminants can be identified. A method for recycling bulk material having unknown levels of contaminants includes the steps of providing at least one neutron generator, at least one gamma ray detector, and structure for analyzing gamma ray data, irradiating the bulk material with neutrons, and then determining the presence of at least one contaminant in the bulk material from gamma rays emitted from the bulk material.

Structure and Soot Properties of Nonbuoyant Ethylene/Air Laminar Jet Diffusion Flames. Appendix I

NASA Technical Reports Server (NTRS)

Urban, D. L.; Yuan, Z.-G.; Sunderland, P. B.; Linteris, G. T.; Voss, J. E.; Lin, K.-C.; Dai, Z.; Sun, K.; Faeth, G. M.; Ross, Howard D. (Technical Monitor)

2000-01-01

The structure and soot properties of round, soot-emitting, nonbuoyant, laminar jet diffusion flames are described, based on long-duration (175-230/s) experiments at microgravity carried out on orbit In the Space Shuttle Columbia. Experiments] conditions included ethylene-fueled flames burning in still air at nominal pressures of 50 and 100 kPa and an ambient temperature of 300 K with luminous Annie lengths of 49-64 mm. Measurements included luminous flame shapes using color video imaging, soot concentration (volume fraction) distributions using deconvoluted laser extinction imaging, soot temperature distributions using deconvoluted multiline emission imaging, gas temperature distributions at fuel-lean (plume) conditions using thermocouple probes, not structure distributions using thermophoretic sampling and analysis by transmission electron microscopy, and flame radiation using a radiometer. The present flames were larger, and emitted soot men readily, than comparable observed during ground-based microgravity experiments due to closer approach to steady conditions resulting from the longer test times and the reduced gravitational disturbances of the space-based experiments.

QSAR studies of macrocyclic diterpenes with P-glycoprotein inhibitory activity.

PubMed

Sousa, Inês J; Ferreira, Maria-José U; Molnár, Joseph; Fernandes, Miguel X

2013-02-14

Multidrug resistance (MDR) represents a major limitation for cancer chemotherapy. There are several mechanisms of MDR but the most important is associated with P-glycoprotein (P-gp) overexpression. The development of modulators of P-gp that are able to re-establish drug sensitivity of resistant cells has been considered a promising approach for overcoming MDR. Macrocyclic lathyrane and jatrophane-type diterpenes from Euphorbia species were found to be strong MDR reversing agents. In this study we applied quantitative structure-activity relationship (QSAR) methodology in order to identify the most relevant molecular features of macrocyclic diterpenes with P-gp inhibitory activity and to determine which structural modifications can be performed to improve their activity. Using experimental biological data at two concentrations (4 and 40 μg/ml), we developed a QSAR model for a set of 51 bioactive diterpenic compounds which includes lathyrane and jatrophane-type diterpenes and another model just for jatrophanes. The cross-validation correlation values for all diterpenes QSAR models developed for biological activities at compound concentrations of 4 and 40 μg/ml were 0.758 and 0.729, respectively. Regarding the prediction ability, we get R²(pred) values of 0.765 and 0.534 for biological activities at compound concentrations of 4 and 40 μg/ml, respectively. Applying the cross-validation test to jatrophanes QSAR models, we obtained 0.680 and 0.787 for biological activities at compound concentrations of 4 and 40 μg/ml concentrations, respectively. For the same concentrations, the obtained R²(pred) values for jatrophanes models were 0.541 and 0.534, respectively. The obtained models were statistically valid and showed high prediction ability. Copyright © 2012 Elsevier B.V. All rights reserved.

Quantification of Human Cortical Bone Bound and Free Water in Vivo with Ultrashort Echo Time MR Imaging: A Model-based Approach.

PubMed

Abbasi-Rad, Shahrokh; Saligheh Rad, Hamidreza

2017-06-01

Purpose To quantify free and bound water components of cortical bone with a model-based numeric approach with use of ultrashort echo time (UTE) magnetic resonance (MR) imaging in vivo in order to introduce a new predictor for age-related deterioration of cortical bone structure. Materials and Methods Human studies were compliant with HIPAA and approved by the institutional review board. Dual-repetition time three-dimensional hybrid-radial UTE imaging was performed, followed by the application of postprocessing algorithms, to quantify free and bound water parameters (concentration [ρ] and longitudinal relaxation time [T1]) of human cortical bone in vivo. The postprocessing algorithms included the decomposition of bulk equations into free- and bound-associated equations and solving resulted inverse problem by using evolutionary strategy methods. To test the validity of the introduced biomarker, it was measured in 40 healthy women by using the proposed method, and associations among parameters were evaluated with the Pearson correlation coefficient. Results The mean free water concentration, bound water concentration, free water T1, and bound water T1 in the recruited population were 5.9%, 19.6%, 306.79 msec, and 162.47 msec, respectively. All reported values were in good agreement with those in the literature. Cortical bone free water T1 (R 2 = 0.72) and cortical bone free water concentration (R 2 = 0.62) showed strong positive correlations with age. Conclusion The cortical bone free water concentration and free water T1 derived with UTE imaging are good predictors of age-related deterioration of cortical bone structure and are potentially superior to previously introduced measures such as bone water concentration and suppression ratio. © RSNA, 2017.

Soot Formation in Laminar Acetylene/Air Diffusion Flames at Atmospheric Pressure. Appendix C

NASA Technical Reports Server (NTRS)

Xu, F.; Faeth, G. M.; Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

2000-01-01

The flame structure and soot-formation (soot nucleation and growth) properties of axisymmetric laminar coflowing jet diffusion flames were studied experimentally. Test conditions involved acetylene-nitrogen jets burning in coflowing air at atmospheric pressure. Measurements were limited to the axes of the flames and included soot concentrations, soot temperatures, soot structure, major gas species concentrations, radical species (H, OH, and O) concentrations, and gas velocities. The results show that as distance increases along the axes of the flames, detectable soot formation begins when significant H concentrations are present, and ends when acetylene concentrations become small. Species potentially associated with soot oxidation-O2, CO2, H2O, O, and OH-are present throughout the soot-formation region so that soot formation and oxidation proceed at the same time. Strong rates of soot growth compared to soot nucleation early in the soot-formation process, combined with increased rates of soot nucleation and oxidation as soot formation proceeds, causes primary soot particle diameters to reach a maximum relatively early in the soot-formation process. Aggregation of primary soot particles proceeds, however, until the final stages of soot oxidation. Present measurements of soot growth (corrected for soot oxidation) in laminar diffusion flames were consistent with earlier measurements of soot growth in laminar premixed flames and exhibited encouraging agreement with existing hydrogen-abstraction/carbon-addition (HACA) soot growth mechanisms in the literature that were developed based on measurements within laminar premixed flames. Measured primary soot particle nucleation rates in the present laminar diffusion flames also were consistent with corresponding rates measured in laminar premixed flames and yielded a crude correlation in terms of acetylene and H concentrations and the temperature.

Soot Formation in Laminar Acetylene/Air Diffusion Flames at Atmospheric Pressure. Appendix H

NASA Technical Reports Server (NTRS)

Xu, F.; Faeth, G. M.; Yuan, Z.-G. (Technical Monitor); Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

2001-01-01

The flame structure and soot-formation (soot nucleation and growth) properties of axisymmetric laminar coflowing jet diffusion flames were studied experimentally. Test conditions involved acetylene-nitrogen jets burning in coflowing air at atmospheric pressure. Measurements were limited to the axes of the flames and included soot concentrations, soot temperatures, soot structure, major gas species concentrations, radical species (H, OH, and O) concentrations, and gas velocities. The results show that as distance increases along the axes of the flames, detectable soot formation begins when significant H concentrations are present, and ends when acetylene concentrations become small. Species potentially associated with soot oxidation-O2, CO2, H2O, O, and OH-are present throughout the soot-formation region so that soot formation and oxidation proceed at the same time. Strong rates of soot growth compared to soot nucleation early in the soot-formation process, combined with increased rates of soot nucleation and oxidation as soot formation proceeds, causes primary soot particle diameters to reach a maximum relatively early in the soot-formation process. Aggregation of primary soot particles proceeds, however, until the final stages of soot oxidation. Present measurements of soot growth (corrected for soot oxidation) in laminar diffusion flames were consistent with earlier measurements of soot growth in laminar premixed flames and exhibited encouraging agreement with existing hydrogen-abstraction/carbon-addition (HACA) soot growth mechanisms in the literature that were developed based on measurements within laminar premixed flames. Measured primary soot particle nucleation rates in the present laminar diffusion flames also were consistent with corresponding rates measured in laminar premixed flames and yielded a crude correlation in terms of acetylene and H concentrations and the temperature.

Soot Formation in Laminar Acetylene/Air Diffusion Flames at Atmospheric Pressure. Appendix J

NASA Technical Reports Server (NTRS)

Xu, F.; Faeth, G. M.; Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

2001-01-01

The flame structure and soot-formation (soot nucleation and growth) properties of axisymmetric laminar coflowing jet diffusion flames were studied experimentally. Test conditions involved acetylene-nitrogen jets burning in coflowing air at atmospheric pressure. Measurements were limited to the axes of the flames and included soot concentrations, soot temperatures, soot structure, major gas species concentrations, radical species (H, OH, and O) concentrations, and gas velocities. The results show that as distance increases along the axes of the flames, detectable soot formation begins when significant H concentrations are present, and ends when acetylene concentrations become small. Species potentially associated with soot oxidation--O2, CO2, H2O, O, and OH-are present throughout the soot-formation region so that soot formation and oxidation proceed at the same time. Strong rates of soot growth compared to soot nucleation early in the soot-formation process, combined with increased rates of soot nucleation and oxidation as soot formation proceeds, causes primary soot particle diameters to reach a maximum relatively early in the soot-formation process. Aggregation of primary soot particles proceeds, however, until the final stages of soot oxidation. Present measurements of soot growth (corrected for soot oxidation) in laminar diffusion flames were consistent with earlier measurements of soot growth in laminar premixed flames and exhibited encouraging agreement with existing hydrogen-abstraction/carbon-addition (HACA) soot growth mechanisms in the literature that were developed based on measurements within laminar premixed flames. Measured primary soot particle nucleation rates in the present laminar diffusion flames also were consistent with corresponding rates measured in laminar premixed flames and yielded a crude correlation in terms of acetylene and H concentrations and the temperature.

Beyond topology: coevolution of structure and flux in metabolic networks.

PubMed

Morrison, E S; Badyaev, A V

2017-10-01

Interactions between the structure of a metabolic network and its functional properties underlie its evolutionary diversification, but the mechanism by which such interactions arise remains elusive. Particularly unclear is whether metabolic fluxes that determine the concentrations of compounds produced by a metabolic network, are causally linked to a network's structure or emerge independently of it. A direct empirical study of populations where both structural and functional properties vary among individuals' metabolic networks is required to establish whether changes in structure affect the distribution of metabolic flux. In a population of house finches (Haemorhous mexicanus), we reconstructed full carotenoid metabolic networks for 442 individuals and uncovered 11 structural variants of this network with different compounds and reactions. We examined the consequences of this structural diversity for the concentrations of plumage-bound carotenoids produced by flux in these networks. We found that concentrations of metabolically derived, but not dietary carotenoids, depended on network structure. Flux was partitioned similarly among compounds in individuals of the same network structure: within each network, compound concentrations were closely correlated. The highest among-individual variation in flux occurred in networks with the strongest among-compound correlations, suggesting that changes in the magnitude, but not the distribution of flux, underlie individual differences in compound concentrations on a static network structure. These findings indicate that the distribution of flux in carotenoid metabolism closely follows network structure. Thus, evolutionary diversification and local adaptations in carotenoid metabolism may depend more on the gain or loss of enzymatic reactions than on changes in flux within a network structure. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

Morphological and ultrastructural changes in tobacco BY-2 cells exposed to microcystin-RR.

PubMed

Huang, Wenmin; Xing, Wei; Li, Dunhai; Liu, Yongding

2009-08-01

Tobacco BY-2 cells were exposed to microcystin-RR (MC-RR) at two concentrations, 60 microg mL(-1) and 120 microg mL(-1), to study the changes in morphology and ultrastructure of cells as a result of the exposure. Exposure to the lower concentration for 5 d led to typical apoptotic morphological changes including condensation of nuclear chromatin, creation of a characteristic 'half moon' structure, and cytoplasm shrinkage and decreased cell volume, as revealed through light microscopy, fluorescence microscopy, and transmission electron microscopy, respectively. Exposure to the higher concentration, on the other hand, led to morphological and ultrastructural changes typical of necrosis, such as rupture of the plasma membrane and the nuclear membrane and a marked swelling of cells. The presence of many vacuoles containing unusual deposits points to the involvement of vacuoles in detoxifying MC-RR. Results of the present study indicate that exposure of tobacco BY-2 cells to MC-RR at a lower concentration (60 microg mL(-1)) results in apoptosis and that to a higher concentration (120 microg mL(-1)), in necrosis.

Structural and electrical properties of In-implanted Ge

DOE PAGES

Feng, R.; Kremer, F.; Sprouster, D. J.; ...

2015-10-22

Here, we report on the effects of dopant concentration on the structural and electrical properties of In-implanted Ge. For In concentrations of ≤ 0.2 at. %, extended x-ray absorption fine structure and x-ray absorption near-edge structure measurements demonstrate that all In atoms occupy a substitutional lattice site while metallic In precipitates are apparent in transmission electron micrographs for In concentrations ≥0.6 at. %. Evidence of the formation of In-vacancy complexes deduced from extended x-ray absorption fine structure measurements is complimented by density functional theory simulations. Hall effect measurements of the conductivity, carrier density, and carrier mobility are then correlated withmore » the substitutional In fraction.« less

The Stretched Lens Array (SLA): An Ultra-Light Photovoltaic Concentrator

NASA Technical Reports Server (NTRS)

ONeill, Mark J.; Pisczor, Michael F.; Eskenazi, Michael I.; McDanal, A. J.; George, Patrick J.; Botke, Matthew M.; Brandhorst, Henry W.; Edwards, David L.; Jaster, Paul A.

2002-01-01

A high-performance, ultralight, photovoltaic concentrator array is being developed for space power. The stretched lens array (SLA) uses stretched-membrane, silicone Fresnel lenses to concentrate sunlight onto triple-junction photovoltaic cells. The cells are mounted to a composite radiator structure. The entire solar array wing, including lenses, photovoltaic cell flex circuits, composite panels, hinges, yoke, wiring harness, and deployment mechanisms, has a mass density of 1.6 kg/sq.m. NASA Glenn has measured 27.4% net SLA panel efficiency, or 375 W/sq.m. power density, at room temperature. At GEO operating cell temperature (80 C), this power density will be 300 W/sq.m., resulting in more than 180 W/kg specific power at the full wing level. SLA is a direct ultralight descendent of the successful SCARLET array on NASA's Deep Space 1 spacecraft. This paper describes the evolution from SCARLET to SLA, summarizes the SLA's key features, and provides performance and mass data for this new concentrator array.

Combined scanning transmission X-ray and electron microscopy for the characterization of bacterial endospores.

PubMed

Jamroskovic, Jan; Shao, Paul P; Suvorova, Elena; Barak, Imrich; Bernier-Latmani, Rizlan

2014-09-01

Endospores (also referred to as bacterial spores) are bacterial structures formed by several bacterial species of the phylum Firmicutes. Spores form as a response to environmental stress. These structures exhibit remarkable resistance to harsh environmental conditions such as exposure to heat, desiccation, and chemical oxidants. The spores include several layers of protein and peptidoglycan that surround a core harboring DNA as well as high concentrations of calcium and dipicolinic acid (DPA). A combination of scanning transmission X-ray microscopy, scanning transmission electron microscopy, and energy dispersive spectroscopy was used for the direct quantitative characterization of bacterial spores. The concentration and localization of DPA, Ca(2+) , and other elements were determined and compared for the core and cortex of spores from two distinct genera: Bacillus subtilis and Desulfotomaculum reducens. This micro-spectroscopic approach is uniquely suited for the direct study of individual bacterial spores, while classical molecular and biochemical methods access only bulk characteristics. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

High flux nanofiltration membranes based on layer-by-layer assembly modified electrospun nanofibrous substrate

NASA Astrophysics Data System (ADS)

Xu, Guo-Rong; Liu, Xiao-Yu; Xu, Jian-Mei; Li, Lu; Su, Hui-Chao; Zhao, He-Li; Feng, Hou-Jun

2018-03-01

Herein, high flux nanofiltration (NF) membranes were fabricated by combined procedures of electrospinning, layer-by-layer (LBL) assembly, and phase inversion. The membranes displayed three-dual structure constituted polyether sulfone (PES) coating layer, LBL assembly modified electrospun polyester (PET) nanofibrous mats, and non-woven supports. High flux NF membranes thus prepared are characterized by ultrathin phase inversion layer (∼10 μm) while that of conventional membranes are 100-150 μm, implying that very high flux could be expected. Various factors including electrospinning conditions, chitosan (CHI)/alginate (ALG) concentration, PES concentration, exposed time, coagulating temperature, thermal treatment, and sulfonated poly ether ketone (SPEEK) content were systematically investigated. Structures of the membranes were characterized by field emission scanning electron microscopy (FESEM), mechanical properties test, Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and static contact angle measurements. The separation experiments indicated that thus prepared membranes exhibited high flux of as high as ∼75 L m-2 h-1 with Mg SO4 rejection of ∼80%.

Assembly of one-dimensional supramolecular objects: From monomers to networks

NASA Astrophysics Data System (ADS)

Sayar, Mehmet; Stupp, Samuel I.

2005-07-01

One-dimensional supramolecular aggregates can form networks at exceedingly low concentrations. Recent experiments in several laboratories, including our own, have demonstrated the formation of gels by these systems at concentrations well under 1% by weight. The systems of interest in our laboratory form either cylindrical nanofibers or ribbons as a result of strong noncovalent interactions among monomers. The stiffness and interaction energies among these thread-like objects can vary significantly depending on the chemical structure of the monomers used. We have used Monte Carlo simulations to study the structure of the threads and their ability to form networks through bundle formation. The persistence length of the threads was found to be strongly affected not only by stiffness, but also by the strength of attractive two-body interactions among thread segments. The relative values of stiffness and attractive two-body interaction strength determine if threads collapse or create bundles. Only in the presence of sufficiently long threads and bundle formation can these systems assemble into networks of high connectivity.

Role of Hydrogen and Structure on CMSX-2

NASA Technical Reports Server (NTRS)

Baker, C. L.; Chene, J.; Kromp, W.; Pinczolitis, H.; Bernstein, S. M.; Williams, J. C.

1985-01-01

The goal was to characterize and understand the detailed effect of hydrogen on the tensile and fatigue behavior of single crystals of CMSX-2. Specimens were solutionized, air cooled, and then aged in one of two ways. The resultant macro and microstructure included a pronounced dendritic structure with numerous low angle boundaries in the interdendritic region and on the average a high level of porosity with a large variation in size and distribution. Hydrogen permeability and diffusivity in this material was found to be very low at room temperature. Hydrogen concentration studies on thin samples yielded values significantly higher than found for similar charging conditions in nickel and stainless steels. The tensile mechanical properties were found to depend on hydrogen concentration. SEM observations of the brittle subsurface zone revealed a strong correlation between crack initiation sites and voids just beneath the surface. The hollow and solid samples were compared to better understand the influence of increased charged volume on the fatigue behavior.

Structural perturbation of proteins in low denaturant concentrations.

PubMed

Basak, S; Debnath, D; Haque, E; Ray, S; Chakrabarti, A

2001-01-01

The presence of very low concentrations of the widely used chemical denaturants, guanidinium chloride and urea, induce changes in the tertiary structure of proteins. We have presented results on such changes in four structurally unrelated proteins to show that such structural perturbations are common irrespective of their origin. Data representative of such structural changes are shown for the monomeric globular proteins such as horseradish peroxidase (HRP) from a plant, human serum albumin (HSA) and prothrombin from ovine blood serum, and for the membrane-associated, worm-like elongated protein, spectrin, from ovine erythrocytes. Structural alterations in these proteins were reflected in quenching studies of tryptophan fluorescence using the widely used quencher acrylamide. Stern-Volmer quenching constants measured in presence of the denaturants, even at concentrations below 100 mM, were higher than those measured in absence of the denaturants. Both steady-state and time-resolved fluorescence emission properties of tryptophan and of the extrinsic probe PRODAN were used for monitoring conformational changes in the proteins in presence of different low concentrations of the denaturants. These results are consistent with earlier studies from our laboratory indicating structural perturbations in proteins at the tertiary level, keeping their native-like secondary structure and their biological activity more or less intact.

Impacts of leguminous shrub encroachment on neighboring grasses include transfer of fixed nitrogen.

PubMed

Zhang, Hai-Yang; Yu, Qiang; Lü, Xiao-Tao; Trumbore, Susan E; Yang, Jun-Jie; Han, Xing-Guo

2016-04-01

Shrub encroachment induced by global change and human disturbance strongly affects ecosystem structure and function. In this study, we explore the degree to which invading leguminous shrubs affected neighboring grasses, including via the transfer of fixed nitrogen (N). We measured N concentrations and natural abundance (15)N of shoot tissues from three dominant grasses from different plant functional groups across seven distances along a local transect (up to 500 cm) to the leguminous shrub, Caragana microphylla. C. microphylla did transfer fixed N to neighboring grasses, but the amount and distance of N transferred were strongly species-specific. Shoot N concentrations decreased significantly with distance from C. microphylla, for a rhizomatous grass, Leymus chinensis, and a bunchgrass, Achnatherum sibiricum. However, N concentrations of another bunchgrass, Stipa grandis, were higher only directly underneath the shrub canopy. Shoot δ(15)N values of L. chinensis were enriched up to 500 cm from the shrub, but for S. grandis were enriched only below the shrub canopy. In contrast, δ(15)N of A. sibiricum did not change along the 500-cm transect. Our results indicated the rhizomatous grass transferred fixed N over long distances while bunchgrasses did not. The presence of C. microphylla increased the shoot biomass of L. chinensis but decreased that of S. grandis and A. sibiricum. These findings highlight the potential role of nutrient-acquisition strategies of neighboring grasses in moderating the interspecific variation of fixed N transfer from the leguminous shrub. Overall, leguminous shrubs have either positive or negative effects on the neighboring grasses and dramatically affect plant community composition and structure.

Magneto-transport and magneto-optical studies on SnO2 transparent semiconducting thin films alloyed with Mn over a wide range of concentration

NASA Astrophysics Data System (ADS)

Bagheri Mohagheghi, M. M.; Tabatabai Yazdi, Sh.; Mousavi, M.

2018-03-01

In this work, Mn-alloyed tin oxide transparent thin films with different Mn concentrations up to 60 at% were prepared via the spray pyrolysis method, and their structural, magneto-optical, and magneto-transport properties were studied. The results show that all the deposited films are polycrystalline with the tetragonal rutile structure. The unit cell volume of Sn1- x Mn x O2 films was found to be minimum at the Mn concentration of x = 0.15 indicating to two different mechanisms for Mn addition in the crystal lattice of tin oxide. For the films with Mn concentrations less than 15%, substitutional doping is the working mechanism, while for more Mn concentrations, interstitial one is predominant. A critical Mn concentration about that observed for the structural properties of the films (i.e., x = 0.15) was revealed for their magnetoresistance and magneto-optical properties, as well. This suggests a correlation between the structural and magnetic behaviors of the deposited SnO2:Mn films.

External cavity-quantum cascade laser infrared spectroscopy for secondary structure analysis of proteins at low concentrations

PubMed Central

Schwaighofer, Andreas; Alcaráz, Mirta R.; Araman, Can; Goicoechea, Héctor; Lendl, Bernhard

2016-01-01

Fourier transform infrared (FTIR) and circular dichroism (CD) spectroscopy are analytical techniques employed for the analysis of protein secondary structure. The use of CD spectroscopy is limited to low protein concentrations (<2 mg ml−1), while FTIR spectroscopy is commonly used in a higher concentration range (>5 mg ml−1). Here we introduce a quantum cascade laser (QCL)-based IR transmission setup for analysis of protein and polypeptide secondary structure at concentrations as low as 0.25 mg ml−1 in deuterated buffer solution. We present dynamic QCL-IR spectra of the temperature-induced α-helix to β-sheet transition of poly-L-lysine. The concentration dependence of the α-β transition temperature between 0.25 and 10 mg ml−1 was investigated by QCL-IR, FTIR and CD spectroscopy. By using QCL-IR spectroscopy it is possible to perform IR spectroscopic analysis in the same concentration range as CD spectroscopy, thus enabling a combined analysis of biomolecules secondary structure by CD and IR spectroscopy. PMID:27633337

External cavity-quantum cascade laser infrared spectroscopy for secondary structure analysis of proteins at low concentrations.

PubMed

Schwaighofer, Andreas; Alcaráz, Mirta R; Araman, Can; Goicoechea, Héctor; Lendl, Bernhard

2016-09-16

Fourier transform infrared (FTIR) and circular dichroism (CD) spectroscopy are analytical techniques employed for the analysis of protein secondary structure. The use of CD spectroscopy is limited to low protein concentrations (<2 mg ml(-1)), while FTIR spectroscopy is commonly used in a higher concentration range (>5 mg ml(-1)). Here we introduce a quantum cascade laser (QCL)-based IR transmission setup for analysis of protein and polypeptide secondary structure at concentrations as low as 0.25 mg ml(-1) in deuterated buffer solution. We present dynamic QCL-IR spectra of the temperature-induced α-helix to β-sheet transition of poly-L-lysine. The concentration dependence of the α-β transition temperature between 0.25 and 10 mg ml(-1) was investigated by QCL-IR, FTIR and CD spectroscopy. By using QCL-IR spectroscopy it is possible to perform IR spectroscopic analysis in the same concentration range as CD spectroscopy, thus enabling a combined analysis of biomolecules secondary structure by CD and IR spectroscopy.

Controlled assembly of nanoparticle structures: spherical and toroidal superlattices and nanoparticle-coated polymeric beads.

PubMed

Isojima, Tatsushi; Suh, Su Kyung; Vander Sande, John B; Hatton, T Alan

2009-07-21

The emulsion droplet solvent evaporation method has been used to prepare nanoclusters of monodisperse magnetite nanoparticles of varying morphologies depending on the temperature and rate of solvent evaporation and on the composition (solvent, presence of polymer, nanoparticle concentration, etc.) of the emulsion droplets. In the absence of a polymer, and with increasing solvent evaporation temperatures, the nanoparticles formed single- or multidomain crystalline superlattices, amorphous spherical aggregates, or toroidal clusters, as determined by the energetics and dynamics of the solvent evaporation process. When polymers that are incompatible with the nanoparticle coatings were included in the emulsion formulation, monolayer- and multilayer-coated polymer beads and partially coated Janus beads were prepared; the nanoparticles were expelled by the polymer as its concentration increased on evaporation of the solvent and accumulated on the surfaces of the beads in a well-ordered structure. The precise number of nanoparticle layers depended on the polymer/magnetic nanoparticle ratio in the oil droplet phase parent emulsion. The magnetic nanoparticle superstructures responded to the application of a modest magnetic field by forming regular chains with alignment of nonuniform structures (e.g., toroids and Janus beads) that are in accord with theoretical predictions and with observations in other systems.

Quantification of the Thermodynamically Linked Quaternary and Tertiary Structural Stabilities of Transthyretin and its Disease-Associated Variants–the Relationship between Stability and Amyloidosis†

PubMed Central

Hurshman Babbes, Amy R.; Powers, Evan T.; Kelly, Jeffery W.

2009-01-01

Urea denaturation studies were carried out as a function of transthyretin (TTR) concentration to quantify the thermodynamically linked quaternary and tertiary structural stability and to better understand the relationship between mutant folding energetics and amyloid disease phenotype. Urea denaturation of TTR involves at least two equilibria—dissociation of tetramers into folded monomers, and monomer unfolding. To deal with the thermodynamic linkage of these equilibria, we analyzed concentration-dependent denaturation data by global fitting to an equation that simultaneously accounts for the two-step denaturation process. Using this method, the quaternary and tertiary structural stabilities of well-behaved TTR sequences, wild type (WT) TTR and the disease-associated variant V122I, were scrutinized. The V122I variant is linked to late onset familial amyloid cardiomyopathy, the most common familial TTR amyloid disease. V122I TTR exhibits a destabilized quaternary structure and a stable tertiary structure relative to WT TTR. Three other variants of TTR were also examined, L55P, V30M, and A25T TTR. The L55P mutation is associated with the most aggressive familial TTR amyloid disease. L55P TTR has a complicated denaturation pathway that includes dimers and trimers, and so globally fitting its concentration-dependent urea denaturation data yielded error-laden estimates of stability parameters. Nevertheless, it is clear that L55P TTR is substantially less stable than WT TTR, primarily because its tertiary structure is unstable, although its quaternary structure is destabilized as well. V30M is the most common mutation associated with neuropathic forms of TTR amyloid disease. V30M TTR is certainly destabilized relative to WT TTR, but like L55P TTR it has a complex denaturation pathway that cannot be fit to the aforementioned two-step denaturation model. Literature data suggest that V30M TTR has stable quaternary structure but unstable tertiary structure. The A25T mutant, associated with central nervous system amyloidosis, is highly aggregation-prone and exhibits drastically reduced quaternary and tertiary structural stability. The observed differences in stability amongst the disease-associated TTR variants highlight the complexity and the heterogeneity of TTR amyloid disease, an observation having important implications for the treatment of these diseases. PMID:18537267

Aquatic concentrations of chemical analytes compared to ...

EPA Pesticide Factsheets

We describe screening level estimates of potential aquatic toxicity posed by 227 chemical analytes that were measured in 25 ambient water samples collected as part of a joint USGS/USEPA drinking water plant study. Measured concentrations were compared to biological effect concentration (EC) estimates, including USEPA aquatic life criteria, effective plasma concentrations of pharmaceuticals, published toxicity data summarized in the USEPA ECOTOX database, and chemical structure-based predictions. Potential dietary exposures were estimated using a generic 3-tiered food web accumulation scenario. For many analytes, few or no measured effect data were found, and for some analytes, reporting limits exceeded EC estimates, limiting the scope of conclusions. Results suggest occasional occurrence above ECs for copper, aluminum, strontium, lead, uranium, and nitrate. Sparse effect data for manganese, antimony, and vanadium suggest that these analytes may occur above ECs, but additional effect data would be desirable to corroborate EC estimates. These conclusions were not affected by bioaccumulation estimates. No organic analyte concentrations were found to exceed EC estimates, but ten analytes had concentrations in excess of 1/10th of their respective EC: triclocarban, norverapamil, progesterone, atrazine, metolachlor, triclosan, para-nonylphenol, ibuprofen, venlafaxine, and amitriptyline, suggesting more detailed characterization of these analytes. Purpose: to provide sc

Aquatic concentrations of chemical analytes compared to ecotoxicity estimates

USGS Publications Warehouse

Kostich, Mitchell S.; Flick, Robert W.; Angela L. Batt,; Mash, Heath E.; Boone, J. Scott; Furlong, Edward T.; Kolpin, Dana W.; Glassmeyer, Susan T.

2017-01-01

We describe screening level estimates of potential aquatic toxicity posed by 227 chemical analytes that were measured in 25 ambient water samples collected as part of a joint USGS/USEPA drinking water plant study. Measured concentrations were compared to biological effect concentration (EC) estimates, including USEPA aquatic life criteria, effective plasma concentrations of pharmaceuticals, published toxicity data summarized in the USEPA ECOTOX database, and chemical structure-based predictions. Potential dietary exposures were estimated using a generic 3-tiered food web accumulation scenario. For many analytes, few or no measured effect data were found, and for some analytes, reporting limits exceeded EC estimates, limiting the scope of conclusions. Results suggest occasional occurrence above ECs for copper, aluminum, strontium, lead, uranium, and nitrate. Sparse effect data for manganese, antimony, and vanadium suggest that these analytes may occur above ECs, but additional effect data would be desirable to corroborate EC estimates. These conclusions were not affected by bioaccumulation estimates. No organic analyte concentrations were found to exceed EC estimates, but ten analytes had concentrations in excess of 1/10th of their respective EC: triclocarban, norverapamil, progesterone, atrazine, metolachlor, triclosan, para-nonylphenol, ibuprofen, venlafaxine, and amitriptyline, suggesting more detailed characterization of these analytes.

Aquatic concentrations of chemical analytes compared to ecotoxicity estimates.

PubMed

Kostich, Mitchell S; Flick, Robert W; Batt, Angela L; Mash, Heath E; Boone, J Scott; Furlong, Edward T; Kolpin, Dana W; Glassmeyer, Susan T

2017-02-01

We describe screening level estimates of potential aquatic toxicity posed by 227 chemical analytes that were measured in 25 ambient water samples collected as part of a joint USGS/USEPA drinking water plant study. Measured concentrations were compared to biological effect concentration (EC) estimates, including USEPA aquatic life criteria, effective plasma concentrations of pharmaceuticals, published toxicity data summarized in the USEPA ECOTOX database, and chemical structure-based predictions. Potential dietary exposures were estimated using a generic 3-tiered food web accumulation scenario. For many analytes, few or no measured effect data were found, and for some analytes, reporting limits exceeded EC estimates, limiting the scope of conclusions. Results suggest occasional occurrence above ECs for copper, aluminum, strontium, lead, uranium, and nitrate. Sparse effect data for manganese, antimony, and vanadium suggest that these analytes may occur above ECs, but additional effect data would be desirable to corroborate EC estimates. These conclusions were not affected by bioaccumulation estimates. No organic analyte concentrations were found to exceed EC estimates, but ten analytes had concentrations in excess of 1/10th of their respective EC: triclocarban, norverapamil, progesterone, atrazine, metolachlor, triclosan, para-nonylphenol, ibuprofen, venlafaxine, and amitriptyline, suggesting more detailed characterization of these analytes. Published by Elsevier B.V.

Evaluation of four structural best management practices for highway runoff in Beaufort and Colleton Counties, South Carolina, 2005–2006

USGS Publications Warehouse

Conlon, Kevin J.; Journey, Celeste A.

2008-01-01

In general, the four BMPs were not successful at significantly reducing fecal bacteria, nutrients, and total organic carbon (including associated properties of biochemical oxygen demand and chemical oxygen demand). Three of the four BMPs significantly lowered oil and grease concentrations before the stormwater discharged from the outlet. Additionally, only one BMP was effective at reducing all total and particulate

Water clusters in amorphous pharmaceuticals.

PubMed

Authelin, Jean-Rene; MacKenzie, Alan P; Rasmussen, Don H; Shalaev, Evgenyi Y

2014-09-01

Amorphous materials, although lacking the long-range translational and rotational order of crystalline and liquid crystalline materials, possess certain local (short-range) structure. This paper reviews the distribution of one particular component present in all amorphous pharmaceuticals, that is, water. Based on the current understanding of the structure of water, water molecules can exist in either unclustered form or as aggregates (clusters) of different sizes and geometries. Water clusters are reported in a range of amorphous systems including carbohydrates and their aqueous solutions, synthetic polymers, and proteins. Evidence of water clustering is obtained by various methods that include neutron and X-ray scattering, molecular dynamics simulation, water sorption isotherm, concentration dependence of the calorimetric Tg , dielectric relaxation, and nuclear magnetic resonance. A review of the published data suggests that clustering depends on water concentration, with unclustered water molecules existing at low water contents, whereas clusters form at intermediate water contents. The transition from water clusters to unclustered water molecules can be expected to change water dependence of pharmaceutical properties, such as rates of degradation. We conclude that a mechanistic understanding of the impact of water on the stability of amorphous pharmaceuticals would require systematic studies of water distribution and clustering, while such investigations are lacking. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

Indolo[3,2-a]carbazoles from a deep-water sponge of the genus Asteropus.

PubMed

Russell, Floyd; Harmody, Dedra; McCarthy, Peter J; Pomponi, Shirley A; Wright, Amy E

2013-10-25

Two new indolo[3,2-a]carbazoles (1, 2) were isolated from a deep-water collection of a sponge of the genus Asteropus. The structures of 1 and 2 were determined through the analysis of spectroscopic data including mass spectrometry and 2D-NMR. Compound 1 showed minimum inhibitory concentrations of 25 μg/mL against the fungal pathogen Candida albicans and 50 μg/mL against methicillin-resistant Staphylococcus aureus (MRSA). Compounds 1 and 2 showed no cytotoxicity against the PANC1 human pancreatic carcinoma and NCI/ADR-RES ovarian adenocarcinoma cell lines at our standard test concentration of 5 μg/mL.

Indolo[3,2-a]carbazoles from a Deep-Water Sponge of the Genus Asteropus

PubMed Central

2013-01-01

Two new indolo[3,2-a]carbazoles (1, 2) were isolated from a deep-water collection of a sponge of the genus Asteropus. The structures of 1 and 2 were determined through the analysis of spectroscopic data including mass spectrometry and 2D-NMR. Compound 1 showed minimum inhibitory concentrations of 25 μg/mL against the fungal pathogen Candida albicans and 50 μg/mL against methicillin-resistant Staphylococcus aureus (MRSA). Compounds 1 and 2 showed no cytotoxicity against the PANC1 human pancreatic carcinoma and NCI/ADR-RES ovarian adenocarcinoma cell lines at our standard test concentration of 5 μg/mL. PMID:24063539

Biosolubilization of coal by Candida in glucose limited cultures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mitter, J.; Guillory, L.; Bose, N.K.

1990-01-01

Coal biodegradation is attracting the attention of many workers because of its significance for efficient bioconversion of coal into useful chemicals. The authors work is based upon the beneficiation of a fungus (candida) on subbituminous coal. Candida was grown on both solid and liquid sabouraud medium and the coal solubilizing activity was studied at varying glucose concentration and temperature. Lower glucose concentration and higher temperature enhanced coal solubilizing activity by this fungus. Preliminary work has begun on analyzing organic extractions (alumina chromatography) of the liquid produced after microbial solubilization, including elemental analysis, solubility, molecular weights and chemical structure. This preliminarymore » work suggests that the candida could metabolize naturally occurring coal as substrate.« less

Role of artesian groundwater in forming Martian permafrost features

NASA Technical Reports Server (NTRS)

Howard, Alan D.

1991-01-01

Various landforms possibly related to formation (growth), movement, or decay of ground ice have been identified on Mars, including fretted terrain (ft) and associated lobate debris aprons (lda), the chaotic terrain, concentric crater fills (ccf), polygonal ground, softened terrain, small domes that are possibly pingos, and curvilinear (fingerprint) features (cuf). Glaciers may also have been present. Some of these may involve ice derived from artesian groundwater. Topical areas of discussion are: Mars groundwater and the location of permafrost features; the ft, lda, ccf, and cuf; role of artesian groundwater in formation of fretted terrain, lobate debris blankets, and concentric crater fills; sources of glacial ice; and pingos and other pseudovolcanic structures.

Landscape patterns in rainforest phylogenetic signal: isolated islands of refugia or structured continental distributions?

PubMed

Kooyman, Robert M; Rossetto, Maurizio; Sauquet, Hervé; Laffan, Shawn W

2013-01-01

Identify patterns of change in species distributions, diversity, concentrations of evolutionary history, and assembly of Australian rainforests. We used the distribution records of all known rainforest woody species in Australia across their full continental extent. These were analysed using measures of species richness, phylogenetic diversity (PD), phylogenetic endemism (PE) and phylogenetic structure (net relatedness index; NRI). Phylogenetic structure was assessed using both continental and regional species pools. To test the influence of growth-form, freestanding and climbing plants were analysed independently, and in combination. Species richness decreased along two generally orthogonal continental axes, corresponding with wet to seasonally dry and tropical to temperate habitats. The PE analyses identified four main areas of substantially restricted phylogenetic diversity, including parts of Cape York, Wet Tropics, Border Ranges, and Tasmania. The continental pool NRI results showed evenness (species less related than expected by chance) in groups of grid cells in coastally aligned areas of species rich tropical and sub-tropical rainforest, and in low diversity moist forest areas in the south-east of the Great Dividing Range and in Tasmania. Monsoon and drier vine forests, and moist forests inland from upland refugia showed phylogenetic clustering, reflecting lower diversity and more relatedness. Signals for evenness in Tasmania and clustering in northern monsoon forests weakened in analyses using regional species pools. For climbing plants, values for NRI by grid cell showed strong spatial structuring, with high diversity and PE concentrated in moist tropical and subtropical regions. Concentrations of rainforest evolutionary history (phylo-diversity) were patchily distributed within a continuum of species distributions. Contrasting with previous concepts of rainforest community distribution, our findings of continuous distributions and continental connectivity have significant implications for interpreting rainforest evolutionary history and current day ecological processes, and for managing rainforest diversity in changing circumstances.

Near-field receiving water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in south San Francisco Bay, California; 2009

USGS Publications Warehouse

Dyke, Jessica; Parchaso, Janet K.; Thompson, Janet K.; Cain, Daniel J.; Luoma, Samuel N.; Hornberger, Michelle I.

2010-01-01

Results reported herein include trace element concentrations in sediment and in the clam Macoma petalum (formerly reported as Macoma balthica (Cohen and Carlton, 1995)), clam reproductive activity, and benthic macroinvertebrate community structure for a mudflat one kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in South San Francisco Bay. This report includes data collected for the period January 2009 to December 2009 and extends a critical long-term biogeochemical record dating back to 1974. These data serve as the basis for the City of Palo Alto's Near-Field Receiving Water Monitoring Program, initiated in 1994. In 2009, metal concentrations in both sediments and clam tissue were among the lowest concentrations on record and consistent with results observed since 1991. Following significant reductions in the late 1980s, silver (Ag) and copper (Cu) concentrations appeared to have stabilized. Annual mean concentrations have fluctuated modestly (2-4 fold) in a nondirectional manner. Data for other metals, including chromium, mercury, nickel, selenium, vanadium, and zinc, have been collected since 1994. Over this period, concentrations of these elements, which more likely reflect regional inputs and systemwide processes, have remained relatively constant, aside from typical seasonal variation that is common to all elements. Within years, the winter months (January-March) generally exhibit maximum concentrations, with a decline to annual minima in spring through fall. Mercury (Hg) in sediments and M. petalum were comparable to concentrations observed in 2008 and were generally consistent with data from previous years. Selenium (Se) concentrations in sediment varied among years and showed no sustained temporal trend. In 2009, sedimentary Se concentrations declined from the record high concentrations observed in 2008 to concentrations that were among the lowest on record. Selenium in M. petalum was unchanged from 2008. Overall, Cu and Ag concentrations in sediments and soft tissues of the clam, M. petalum, remained representative of the concentrations observed since 1991 following significant reductions in the discharge of these elements from the PARWQCP. This suggests that, as with other elements of regulatory interest, regional-scale factors now largely influence sedimentary and bioavailable concentrations of Ag and Cu. Analyses of the benthic community structure of a mudflat in South San Francisco Bay over a 36-year period show that changes in the community have occurred concurrent with reduced concentrations of metals in the sediment and in the tissues of the biosentinel clam, M. petalum, from the same area. Analysis of the reproductive activity of M. petalum shows increases in reproductive activity concurrent with the decline in metal concentrations in the tissues of this organism. Reproductive activity is presently stable, with almost all animals initiating reproduction in the fall and spawning the following spring of most years. The community has shifted from being dominated by several opportunistic species to a community where the species are more similar in abundance, a pattern that suggests a more stable community that is subjected to fewer stressors. In addition, two of the opportunistic species (Ampelisca abdita and Streblospio benedicti) that brood their young and live on the surface of the sediment in tubes have shown a continual decline in dominance coincident with the decline in metals; both species had short-lived rebounds in abundance in 2008 and 2009. Heteromastus filiformis (a subsurface polychaete worm that lives in the sediment, consumes sediment and organic particles residing in the sediment, and reproduces by laying its eggs on or in the sediment) showed a concurrent increase in dominance, with the last several years prior to 2008 showing a stable population. An unidentified disturbance occurred on the mudflat in early 2008 that resulted in the loss o

Concentration-dependent and configuration-dependent interactions of monovalent ions with an RNA tetraloop

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miner, Jacob Carlson; Garcia, Angel Enrique

Monovalent salt solutions have strongly coupled interactions with biopolymers, from large polyelectrolytes to small RNA oligomers. High salt concentrations have been known to induce transitions in the structure of RNA, producing non-canonical configurations and even driving RNA to precipitate out of solution. Using all-atom molecular dynamics simulations, we model a monovalent salt species (KCL) at high concentrations (0.1–3m) and calculate the equilibrium distributions of water and ions around a small tetraloop-forming RNA oligomer in a variety of structural arrangements: folded A-RNA (canonical) and Z-RNA (non-canonical) tetraloops and unfolded configurations. From these data, we calculate the ion preferential binding coefficients andmore » Donnan coefficients for the RNA oligomer as a function of concentration and structure. We find that cation accumulation is highest around non-canonical Z-RNA configurations at concentrations below 0.5m, while unfolded configurations accumulate the most co-ions in all concentrations. By contrast, canonical A-RNA structures consistently show the lowest accumulations for all ion species. Water distributions vary markedly with RNA configuration but show little dependency on KCL concentration. Based on Donnan coefficient calculations, the net charge of the solution at the surface of the RNA decreases linearly as a function of salt concentration and becomes net-neutral near 2.5–3m KCL for folded configurations, while unfolded configurations still show a positive solution charge. Our findings show that all-atom molecular dynamics can describe the equilibrium distributions of monovalent salt in the presence of small RNA oligomers at KCL concentrations where ion correlation effects become important. Furthermore, these results provide valuable insights into the distributions of water and ions near the RNA oligomer surface as a function of structural configuration.« less

Concentration-dependent and configuration-dependent interactions of monovalent ions with an RNA tetraloop

DOE PAGES

Miner, Jacob Carlson; Garcia, Angel Enrique

2018-05-29

Monovalent salt solutions have strongly coupled interactions with biopolymers, from large polyelectrolytes to small RNA oligomers. High salt concentrations have been known to induce transitions in the structure of RNA, producing non-canonical configurations and even driving RNA to precipitate out of solution. Using all-atom molecular dynamics simulations, we model a monovalent salt species (KCL) at high concentrations (0.1–3m) and calculate the equilibrium distributions of water and ions around a small tetraloop-forming RNA oligomer in a variety of structural arrangements: folded A-RNA (canonical) and Z-RNA (non-canonical) tetraloops and unfolded configurations. From these data, we calculate the ion preferential binding coefficients andmore » Donnan coefficients for the RNA oligomer as a function of concentration and structure. We find that cation accumulation is highest around non-canonical Z-RNA configurations at concentrations below 0.5m, while unfolded configurations accumulate the most co-ions in all concentrations. By contrast, canonical A-RNA structures consistently show the lowest accumulations for all ion species. Water distributions vary markedly with RNA configuration but show little dependency on KCL concentration. Based on Donnan coefficient calculations, the net charge of the solution at the surface of the RNA decreases linearly as a function of salt concentration and becomes net-neutral near 2.5–3m KCL for folded configurations, while unfolded configurations still show a positive solution charge. Our findings show that all-atom molecular dynamics can describe the equilibrium distributions of monovalent salt in the presence of small RNA oligomers at KCL concentrations where ion correlation effects become important. Furthermore, these results provide valuable insights into the distributions of water and ions near the RNA oligomer surface as a function of structural configuration.« less

Concentration-dependent and configuration-dependent interactions of monovalent ions with an RNA tetraloop

NASA Astrophysics Data System (ADS)

Miner, Jacob Carlson; García, Angel Enrique

2018-06-01

Monovalent salt solutions have strongly coupled interactions with biopolymers, from large polyelectrolytes to small RNA oligomers. High salt concentrations have been known to induce transitions in the structure of RNA, producing non-canonical configurations and even driving RNA to precipitate out of solution. Using all-atom molecular dynamics simulations, we model a monovalent salt species (KCL) at high concentrations (0.1-3m) and calculate the equilibrium distributions of water and ions around a small tetraloop-forming RNA oligomer in a variety of structural arrangements: folded A-RNA (canonical) and Z-RNA (non-canonical) tetraloops and unfolded configurations. From these data, we calculate the ion preferential binding coefficients and Donnan coefficients for the RNA oligomer as a function of concentration and structure. We find that cation accumulation is highest around non-canonical Z-RNA configurations at concentrations below 0.5m, while unfolded configurations accumulate the most co-ions in all concentrations. By contrast, canonical A-RNA structures consistently show the lowest accumulations for all ion species. Water distributions vary markedly with RNA configuration but show little dependency on KCL concentration. Based on Donnan coefficient calculations, the net charge of the solution at the surface of the RNA decreases linearly as a function of salt concentration and becomes net-neutral near 2.5-3m KCL for folded configurations, while unfolded configurations still show a positive solution charge. Our findings show that all-atom molecular dynamics can describe the equilibrium distributions of monovalent salt in the presence of small RNA oligomers at KCL concentrations where ion correlation effects become important. Furthermore, these results provide valuable insights into the distributions of water and ions near the RNA oligomer surface as a function of structural configuration.

Concentration-dependent and configuration-dependent interactions of monovalent ions with an RNA tetraloop.

PubMed

Miner, Jacob Carlson; García, Angel Enrique

2018-06-14

Monovalent salt solutions have strongly coupled interactions with biopolymers, from large polyelectrolytes to small RNA oligomers. High salt concentrations have been known to induce transitions in the structure of RNA, producing non-canonical configurations and even driving RNA to precipitate out of solution. Using all-atom molecular dynamics simulations, we model a monovalent salt species (KCL) at high concentrations (0.1-3m) and calculate the equilibrium distributions of water and ions around a small tetraloop-forming RNA oligomer in a variety of structural arrangements: folded A-RNA (canonical) and Z-RNA (non-canonical) tetraloops and unfolded configurations. From these data, we calculate the ion preferential binding coefficients and Donnan coefficients for the RNA oligomer as a function of concentration and structure. We find that cation accumulation is highest around non-canonical Z-RNA configurations at concentrations below 0.5m, while unfolded configurations accumulate the most co-ions in all concentrations. By contrast, canonical A-RNA structures consistently show the lowest accumulations for all ion species. Water distributions vary markedly with RNA configuration but show little dependency on KCL concentration. Based on Donnan coefficient calculations, the net charge of the solution at the surface of the RNA decreases linearly as a function of salt concentration and becomes net-neutral near 2.5-3m KCL for folded configurations, while unfolded configurations still show a positive solution charge. Our findings show that all-atom molecular dynamics can describe the equilibrium distributions of monovalent salt in the presence of small RNA oligomers at KCL concentrations where ion correlation effects become important. Furthermore, these results provide valuable insights into the distributions of water and ions near the RNA oligomer surface as a function of structural configuration.

Impact of model perfume molecules on the self-assembly of anionic surfactant sodium dodecyl 6-benzene sulfonate.

PubMed

Bradbury, Robert; Penfold, Jeffrey; Thomas, Robert K; Tucker, Ian M; Petkov, Jordan T; Jones, Craig; Grillo, Isabelle

2013-03-12

The impact of two model perfumes with differing degrees of hydrophobicity/hydrophilicity, linalool (LL) and phenylethanol (PE), on the solution structure of anionic surfactant sodium dodecyl 6-benzene sulfonate, LAS-6, has been studied by small angle neutron scattering, SANS. For both types of perfume molecules, complex phase behavior is observed. The phase behavior depends upon the concentration, surfactant/perfume composition, and type of perfume. The more hydrophilic perfume PE promotes the formation of more highly curved structures. At relatively low surfactant concentrations, small globular micelles, L1, are formed. These become perfume droplets, L(sm), stabilized by the surfactant at much higher perfume solution compositions. At higher surfactant concentrations, the tendency of LAS-6 to form more planar structures is evident. The more hydrophobic linalool promotes the formation of more planar structures. Combined with the greater tendency of LAS-6 to form planar structures, this results in the planar structures dominating the phase behavior for the LAS-6/linalool mixtures. For the LAS-6/linalool mixture, the self-assembly is in the form of micelles only at the lowest surfactant and perfume concentrations. Over most of the concentration-composition space explored, the structures are predominantly lamellar, L(α), or vesicle, L(v), or in the form of a lamellar/micellar coexistence. At low and intermediate amounts of LL, a significantly different structure is observed, and the aggregates are in the form of small, relatively monodisperse vesicles (i.e., nanovesicles), L(sv).

Effectiveness of three best management practices for highway-runoff quality along the Southeast Expressway, Boston, Massachusetts

USGS Publications Warehouse

Smith, Kirk P.

2002-01-01

Best management practices (BMPs) near highways are designed to reduce the amount of suspended sediment and associated constituents, including debris and litter, discharged from the roadway surface. The effectiveness of a deep-sumped hooded catch basin, three 2-chambered 1,500-gallon oil-grit separators, and mechanized street sweeping in reducing sediment and associated constituents was examined along the Southeast Expressway (Interstate Route 93) in Boston, Massachusetts. Repeated observations of the volume and distribution of bottom material in the oil-grit separators, including data on particle-size distributions, were compared to data from bottom material deposited during the initial 3 years of operation. The performance of catch-basin hoods and the oil-grit separators in reducing floating debris was assessed by examining the quantity of material retained by each structural BMP compared to the quantity of material retained by and discharged from the oil-grit separators, which received flow from the catch basins. The ability of each structural BMP to reduce suspended-sediment loads was assessed by examining (a) the difference in the concentrations of suspended sediment in samples collected simultaneously from the inlet and outlet of each BMP, and (b) the difference between inlet loads and outlet loads during a 14-month monitoring period for the catch basin and one separator, and a 10-month monitoring period for the second separator. The third separator was not monitored continuously; instead, samples were collected from it during three visits separated in time by several months. Suspended-sediment loads for the entire study area were estimated on the basis of the long-term average annual precipitation and the estimated inlet and outlet loads of two of the separators. The effects of mechanized street sweeping were assessed by evaluating the differences between suspended-sediment loads before and after street sweeping, relative to storm precipitation totals, and by comparing the particle-size distributions of sediment samples collected from the sweepers to bottom-material samples collected from the structural BMPs. A mass-balance calculation was used to quantify the accuracy of the estimated sediment-removal efficiency for each structural BMP. The ability of each structural BMP to reduce concentrations of inorganic and organic constituents was assessed by determining the differences in concentrations between the inlets and outlets of the BMPs for four storms. The inlet flows of the separators were sampled during five storms for analysis of fecal-indicator bacteria. The particle-size distribution of bottom material found in the first and second chambers of the separators was similar for all three separators. Consistent collection of floatable debris at the outlet of one separator during 12 storms suggests that floatable debris were not indefinitely retained.Concentrations of suspended sediment in discrete samples of runoff collected from the inlets of the two separators ranged from 8.5 to 7,110 mg/L. Concentrations of suspended sediment in discrete samples of runoff collected from the outlets of the separators ranged from 5 to 2,170 mg/L. The 14-month sediment-removal efficiency was 35 percent for one separator, and 28 percent for the second separator. In the combined-treatment system in this study, where catch basins provided primary suspended-sediment treatment, the separators reduced the mass of the suspended sediment from the pavement by about an additional 18 percent. The concentrations of suspended sediment in discrete samples of runoff collected from the inlet of the catch basin ranged from 32 to 13,600 mg/L. Concentrations of suspended sediment in discrete samples of runoff collected from the outlet of the catch basin ranged from 25.7 to 7,030 mg/L. The sediment-removal efficiency for individual storms during the 14-month monitoring period for the deep-sumped hooded catch basin was 39 percent.The concentrations of 29 in

Simultaneous influence of pectin and xyloglucan on structure and mechanical properties of bacterial cellulose composites.

PubMed

Szymańska-Chargot, Monika; Chylińska, Monika; Cybulska, Justyna; Kozioł, Arkadiusz; Pieczywek, Piotr M; Zdunek, Artur

2017-10-15

The impact of the matrix polysaccharides on the cellulose microfibrils structure as well as on the mechanical properties of cell walls still remains an open question. Therefore, the aim of investigations was to determine the simultaneous influence of (i) different concentrations of pectins with constant concentration of xyloglucan, and (ii) different concentrations of xyloglucan with constant concentration of pectins on cellulose structure. Composites of bacterial cellulose (BC) produced by Komagataeibacter xylinus are considered to mimic natural plant cell walls. This investigation showed that the lower the ratio of xyloglucan to pectin was, the higher Young's modulus of BC composite was and also obtained cellulose microfibrils were thinner. The increasing concentration of xyloglucan to pectin also caused the drop down in microfibrils crystallinity degree with predominant structure of cellulose I β . In that case, also the length of cellulose chains was growing and reaching the highest value among all BC composites. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of nitrogen-doping concentration on the electronic structure of CuAlO2 by first-principles studies

NASA Astrophysics Data System (ADS)

Liu, Wei-wei; Chen, Hong-xia; Liu, Cheng-lin; Wang, Rong

2017-02-01

Effect of N doping concentration on the electronic structure of N-doped CuAlO2 was investigated by density functional theory based on generalized-gradient approximation plus orbital potential. Lattice parameters a and c both increase with increasing N-doping concentration. Formation energies increase with increasing N doping concentration and all N-doped CuAlO2 were structurally stable. The calculated band gaps for N-doped CuAlO2 narrowed compared to pure CuAlO2, which was attributed to the stronger hybridization between Cu-3d and N-2p states and the downward shift of Cu-3p states in conduction bands. The higher the N-doping concentration is, the narrower the band gap. N-doped CuAlO2 shows a typical p-type semiconductor. The band structure changed from indirect to direct after N doping which will benefit the application of the CuAlO2 materials in optoelectronic and electronic devices.

Dish systems for CSP

DOE PAGES

Coventry, Joe; Andraka, Charles

2017-03-22

Parabolic dish technology, for concentrating solar power (CSP) applications, has been continuously modified and improved since the pioneering work in the 1970s. Best practice dishes now have features such as lightweight structure, balanced design, high-quality, low-cost mirror panels, and can be deployed rapidly with little in-field labour. This review focuses on the evolution of dish design, by examining features such as mode of tracking, structure and mirror design, for a wide selection of CSP dish examples. Finally, the review includes a brief summary of power generation options – both on-dish and central plant – as well as a discussion aboutmore » options for storage and hybridisation.« less

Structure of kaurane-type diterpenes from Parinari sprucei and their potential anticancer activity.

PubMed

Braca, Alessandra; Armenise, Annahil; Morelli, Ivano; Mendez, Jeannette; Mi, Qiuwen; Chai, Hee-Byung; Swanson, Steven M; Kinghorn, A Douglas; De Tommasi, Nunziatina

2004-06-01

Twenty-three kaurane-type diterpenes 1 - 23, including twenty new natural products 1 - 20, have been isolated from the leaves of Parinari sprucei and their structures elucidated by spectroscopic and chemical analysis. The isolated compounds were tested for their cytotoxic activity towards a panel of cancer cell lines. Compounds 9 and 10 showed activity against all cell lines with ED (50) values in the range of 10 - 20 microg/mL. The previously known 13-hydroxy-15-oxozoapatlin 21 was evaluated in an in vivo hollow fiber test, and found to be active with KB and LNCaP cells at the concentrations used.

Fabrication of Mediatorless/Membraneless Glucose/Oxygen Based Biofuel Cell using Biocatalysts Including Glucose Oxidase and Laccase Enzymes.

PubMed

Christwardana, Marcelinus; Kim, Ki Jae; Kwon, Yongchai

2016-07-18

Mediatorless and membraneless enzymatic biofuel cells (EBCs) employing new catalytic structure are fabricated. Regarding anodic catalyst, structure consisting of glucose oxidase (GOx), poly(ethylenimine) (PEI) and carbon nanotube (CNT) is considered, while three cathodic catalysts consist of glutaraldehyde (GA), laccase (Lac), PEI and CNT that are stacked together in different ways. Catalytic activities of the catalysts for glucose oxidation and oxygen reduction reactions (GOR and ORR) are evaluated. As a result, it is confirmed that the catalysts work well for promotion of GOR and ORR. In EBC tests, performances of EBCs including 150 μm-thick membrane are measured as references, while those of membraneless EBCs are measured depending on parameters like glucose flow rate, glucose concentration, distance between two electrodes and electrolyte pH. With the measurements, how the parameters affect EBC performance and their optimal conditions are determined. Based on that, best maximum power density (MPD) of membraneless EBC is 102 ± 5.1 μW · cm(-2) with values of 0.5 cc · min(-1) (glucose flow rate), 40 mM (glucose concentration), 1 mm (distance between electrodes) and pH 3. When membrane and membraneless EBCs are compared, MPD of the membraneless EBC that is run at the similar operating condition to EBC including membrane is speculated as about 134 μW · cm(-2).

Fabrication of Mediatorless/Membraneless Glucose/Oxygen Based Biofuel Cell using Biocatalysts Including Glucose Oxidase and Laccase Enzymes

NASA Astrophysics Data System (ADS)

Christwardana, Marcelinus; Kim, Ki Jae; Kwon, Yongchai

2016-07-01

Mediatorless and membraneless enzymatic biofuel cells (EBCs) employing new catalytic structure are fabricated. Regarding anodic catalyst, structure consisting of glucose oxidase (GOx), poly(ethylenimine) (PEI) and carbon nanotube (CNT) is considered, while three cathodic catalysts consist of glutaraldehyde (GA), laccase (Lac), PEI and CNT that are stacked together in different ways. Catalytic activities of the catalysts for glucose oxidation and oxygen reduction reactions (GOR and ORR) are evaluated. As a result, it is confirmed that the catalysts work well for promotion of GOR and ORR. In EBC tests, performances of EBCs including 150 μm-thick membrane are measured as references, while those of membraneless EBCs are measured depending on parameters like glucose flow rate, glucose concentration, distance between two electrodes and electrolyte pH. With the measurements, how the parameters affect EBC performance and their optimal conditions are determined. Based on that, best maximum power density (MPD) of membraneless EBC is 102 ± 5.1 μW · cm-2 with values of 0.5 cc · min-1 (glucose flow rate), 40 mM (glucose concentration), 1 mm (distance between electrodes) and pH 3. When membrane and membraneless EBCs are compared, MPD of the membraneless EBC that is run at the similar operating condition to EBC including membrane is speculated as about 134 μW · cm-2.

Membrane dish analysis: A summary of structural and optical analysis capabilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steele, C.R.; Balch, C.D.; Jorgensen, G.J.

Research at SERI within the Department of Energy's Solar Thermal Technology Program has focused on the development of membrane dish concentrators for space and terrestrial power applications. As potentially lightweight, inexpensive, high-performance structures, they are excellent candidates for space-deployable energy sources as well as cost-effective terrestrial energy concepts. A thorough engineering research treatment of these types of structures consists primarily of two parts: (1) structural mechanics of the membrane and ring support and (2) analysis and characterization of the concentrator optical performance. It is important to understand the effects of the membrane's structure and support system on the optical performancemore » of the concentrator. This requires an interface between appropriate structural and optical models. Until recently, such models and the required interface have not existed. This report documents research that has been conducted at SERI in this area. It is a compilation of several papers describing structural models of membrane dish structures and optical models used to predict dish concentrator optical and thermal performance. The structural models were developed under SERI subcontract by Dr. Steele and Dr. Balch of Stanford University. The optical model was developed in-house by SERI staff. In addition, the interface between the models is described. It allows easy and thorough characterization of membrane dish systems from the mechanics to the resulting optical performance. The models described herein have been and continue to be extremely useful to SERI, industry, and universities involved with the modeling and analysis of lightweight membrane concentrators for solar thermal applications.« less

Molecular dynamics simulations of structural transformation of perfluorooctane sulfonate (PFOS) at water/rutile interfaces.

PubMed

He, Guangzhi; Zhang, Meiyi; Zhou, Qin; Pan, Gang

2015-09-01

Concentration and salinity conditions are the dominant environmental factors affecting the behavior of perfluorinated compounds (PFCs) on the surfaces of a variety of solid matrices (suspended particles, sediments, and natural minerals). However, the mechanism has not yet been examined at molecular scales. Here, the structural transformation of perfluorooctane sulfonate (PFOS) at water/rutile interfaces induced by changes of the concentration level of PFOS and salt condition was investigated using molecular dynamics (MD) simulations. At low and intermediate concentrations all PFOS molecules directly interacted with the rutile (110) surface mainly by the sulfonate headgroups through electrostatic attraction, yielding a typical monolayer structure. As the concentration of PFOS increased, the molecules aggregated in a complex multi-layered structure, where an irregular assembling configuration was adsorbed on the monolayer structure by the van der Waals interactions between the perfluoroalkyl chains. When adding CaCl2 to the system, the multi-layered structure changed to a monolayer again, indicating that the addition of CaCl2 enhanced the critical concentration value to yield PFOS multilayer assemblies. The divalent Ca(2+) substituted for monovalent K(+) as the bridging counterion in PFOS adsorption. MD simulation may trigger wide applications in study of perfluorinated compounds (PFCs) from atomic/molecular scale. Copyright © 2015 Elsevier Ltd. All rights reserved.

Aggregation behavior and complex structure between triblock copolymer and anionic surfactants

NASA Astrophysics Data System (ADS)

Li, Yiming; Bao, Mutai; Wang, Zhining; Zhang, Haixia; Xu, Guiying

2011-01-01

The aggregation behavior and complex structure of ABA triblock copolymer EO 76PO 30EO 76 (F68) with sodium dodecyl sulfate (SDS) and sodium bis(2-ethylhexyl)sulfonate (AOT) in aqueous solution were investigated by surface tension, fluorescence techniques and dynamic light-scattering (DLS) measurements. It is revealed that in certain regions of binding, surfactant/F68 complexes are formed. Structural informations and size of complexes are evaluated. When F68 is present in its nonassociated state, F68/micellar SDS complexes are formed at SDS concentrations above its critical aggregation concentration (cac). The cac is well below the critical micellar concentration (cmc) of pure SDS, and a model suggesting how complexes are formed at the cac in the presence of F68 is described. Experimental results show that SDS interacts with F68 mainly through hydrophobic forces, polypropylene oxide (PPO) groups of F68 are solubilized into SDS micellar cores and poly(ethylene oxide) (PEO) groups interact with SDS micelles. This interaction mechanism results in a "pearl-necklace" complex structure. However, a different structure occurs for F68/AOT complex at lower F68 concentrations, as nonassociated F68 interacts with AOT mainly through ion-dipole interactions. Complexes with a "wrapping" structure at lower F68 concentrations are formed.

Structural and phase transition changes of sodium dodecyl sulfate micellar solution in alcohols probed by small-angle neutron scattering (SANS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Putra, Edy Giri Rachman; Patriati, Arum; Department of Chemistry, Faculty of Mathematics and Natural Sciences, University of Gadjah Mada, Bulaksumur, Yogyakarta 55281, Indonesia giri@batan.go.id

2015-04-16

Small-angle neutron scattering (SANS) measurements on 0.3M sodium dodecyl sulfate (SDS) micellar solutions have been performed in the presence of n-alcohols, from ethanol to decanol at different alcohol concentrations, 2–10 wt%. The ellipsoid micellar structure which occurred in the 0.3M SDS in aqueous solution with the size range of 30–50 Å has different behavior at various hydrocarbon chain length and concentration of alcohols. At low concentration and short chain-length of alcohols, such as ethanol, propanol, and butanol, the size of micelles reduced and had a spherical-like structure. The opposite effect occurred as medium to long chain alcohols, such as hexanol,more » octanol and decanol was added into the 0.3M SDS micellar solutions. The micelles structure changed to be more elongated in major axis and then crossed the critical phase transition from micellar solution into liquid crystal phase as lamellar structure emerged by further addition of alcohols. The inter-lamellar distances were also depending on the hydrocarbon chain length and concentration of alcohols. In the meantime, the persistent micellar structures occurred in addition of medium chain of n-alcohol, pentanol at all concentrations.« less

Microstructure and magnetic behavior studies of processing-controlled and composition-modified Fe-Ni and Mn-Al alloys

NASA Astrophysics Data System (ADS)

Geng, Yunlong

L10-type (Space group P4/mmm) magnetic compounds, including FeNi and MnAl, possess promising technical magnetic properties of both high magnetization and large magnetocrystalline anisotropy energy, and thus offer potential in replacing rare earth permanent magnets in some applications. In equiatomic Fe-Ni, the disorder-order transformation from fcc structure to the L10 structure is a diffusional transformation, but is inhibited by the low ordering temperature. The transformation could be enhanced through the creation of vacancies. Thus, mechanical alloying was employed to generate more open-volume defects. A decrease in grain size and concomitant increase in grain boundary area resulted from the mechanical alloying, while an initial increase in internal strain (manifested through an increase in dislocation density) was followed by a subsequent decrease with further alloying. However, a decrease in the net defect concentration was determined by Doppler broadening positron annihilation spectroscopy, as open volume defects utilized dislocations and grain boundaries as sinks. An alloy, Fe32Ni52Zr3B13, formed an amorphous structure after rapid solidification, with a higher defect concentration than crystalline materials. Mechanical milling was utilized in an attempt to generate even more defects. However, it was observed that Fe32Ni52Zr3B13 underwent crystallization during the milling process, which appears to be related to enhanced vacancy-type defect concentrations allowing growth of pre-existing Fe(Ni) nuclei. The milling and enhanced vacancy concentration also de-stabilizes the glass, leading to decreased crystallization temperatures, and ultimately leading to complete crystallization. In Mn-Al, the L10 structure forms from the parent hcp phase. However, this phase is slightly hyperstoichiometric relative to Mn, and the excess Mn occupies Al sites and couples antiparallel to the other Mn atoms. In this study, the Zr substituted preferentially for the Mn atoms in the Al layer, resulting in an increase in saturation magnetization, from 115 emu/g in the alloys without Zr to 128 emu/g in Mn53Al43C 3Zr1. To further improve the coercivity in Mn53Al 43C3Zr1, microstructure modification was achieved through the addition of excessive C and through surfactant-assisted mechanical milling. Enhancement in coercivity was accomplished through the microstructure modification, however, the loss of saturation magnetization was observed due to the formation of other equilibrium phases, including epsilon, beta-Mn and ZrO.

Developing visible and near-infrared reflectance spectroscopy to detect changes of the dermal collagen concentration

NASA Astrophysics Data System (ADS)

Wang, Chiao-Yi; Liao, Andy Ying Chi; Sung, Kung Bin

2018-02-01

Collagen provides skin structure integrity and its concentration is related to the severity of scars. The objective of this study is to develop a hand-held and relatively inexpensive system to detect changes of the dermal collagen concentration in vivo. Diffuse reflectance spectroscopy and two-layer diffusion model have often been used to quantify the collagen concentration and other optical properties of the skin. However, the influences of fat and muscle, which are just below the dermis, have not been thoroughly investigated. We applied Monte Carlo simulations to find source-detector separations most sensitive to changes in collagen absorption and identify four wavelengths between 650 nm and 1000 nm suitable for separating influences of other chromophores including melanin, oxyhemoglobin and deoxyhemoglobin. Our tissue model consisted of at least three layers including the epidermis, dermis and subcutaneous fat with an optional forth layer representing the muscle. Results showed that the reflectance of the three-layered tissue model differed significantly from that of the two-layered tissue model, and the additional muscle layer might also influence the reflectance depending on the thickness of the fat layer. In addition, whether scattering coefficients of the epidermis and dermis were the same significantly affected the reflectance. Differences in reflectance due to changes in the collagen concentration were distinct from those due to changes in scattering coefficients and other chromophores. Further in-vivo experiments are ongoing to to validate the proposed approach.

Low-cost modular array-field designs for flat-panel and concentrator photovoltaic systems

NASA Astrophysics Data System (ADS)

Post, H. N.; Carmichael, D. C.; Alexander, G.; Castle, J. A.

1982-09-01

Described are the design and development of low-cost, modular array fields for flat-panel and concentrator photovoltaic (PV) systems. The objective of the work was to reduce substantially the cost of the array-field Balance-of-System (BOS) subsystems and site-specific design costs as compared to previous PV installations. These subsystems include site preparation, foundations, support structures, electrical writing, grounding, lightning protection, electromagnetic interference considerations, and controls. To reduce these BOS and design costs, standardized modular (building-block) designs for flat-panel and concentrator array fields have been developed that are fully integrated and optimized for lowest life-cycle costs. Using drawings and specifications now available, these building-block designs can be used in multiples to install various size array fields. The developed designs are immediately applicable (1982) and reduce the array-field BOS costs to a fraction of previous costs.

Causal structure of oscillations in gene regulatory networks: Boolean analysis of ordinary differential equation attractors.

PubMed

Sun, Mengyang; Cheng, Xianrui; Socolar, Joshua E S

2013-06-01

A common approach to the modeling of gene regulatory networks is to represent activating or repressing interactions using ordinary differential equations for target gene concentrations that include Hill function dependences on regulator gene concentrations. An alternative formulation represents the same interactions using Boolean logic with time delays associated with each network link. We consider the attractors that emerge from the two types of models in the case of a simple but nontrivial network: a figure-8 network with one positive and one negative feedback loop. We show that the different modeling approaches give rise to the same qualitative set of attractors with the exception of a possible fixed point in the ordinary differential equation model in which concentrations sit at intermediate values. The properties of the attractors are most easily understood from the Boolean perspective, suggesting that time-delay Boolean modeling is a useful tool for understanding the logic of regulatory networks.

Bayesian spatio-temporal modeling of particulate matter concentrations in Peninsular Malaysia

NASA Astrophysics Data System (ADS)

Manga, Edna; Awang, Norhashidah

2016-06-01

This article presents an application of a Bayesian spatio-temporal Gaussian process (GP) model on particulate matter concentrations from Peninsular Malaysia. We analyze daily PM10 concentration levels from 35 monitoring sites in June and July 2011. The spatiotemporal model set in a Bayesian hierarchical framework allows for inclusion of informative covariates, meteorological variables and spatiotemporal interactions. Posterior density estimates of the model parameters are obtained by Markov chain Monte Carlo methods. Preliminary data analysis indicate information on PM10 levels at sites classified as industrial locations could explain part of the space time variations. We include the site-type indicator in our modeling efforts. Results of the parameter estimates for the fitted GP model show significant spatio-temporal structure and positive effect of the location-type explanatory variable. We also compute some validation criteria for the out of sample sites that show the adequacy of the model for predicting PM10 at unmonitored sites.

Inversion structure and winter ozone distribution in the Uintah Basin, Utah, U.S.A.

NASA Astrophysics Data System (ADS)

Lyman, Seth; Tran, Trang

2015-12-01

The Uintah Basin in Utah, U.S.A. experiences high concentrations of ozone during some winters due to strong, multi-day temperature inversions that facilitate the buildup of pollution from local sources, including the oil and gas industry. Together, elevation of monitoring sites and proximity to oil and gas wells explain as much as 90% of spatial variability in surface ozone concentrations during inversion episodes (i.e., R2 = 0.90). Inversion conditions start earlier and last longer at lower elevations, at least in part because lower elevations are more insulated from winds aloft that degrade inversion conditions and dilute produced ozone. Surface air transport under inversions is dominated by light, diurnal upslope-downslope flow that limits net transport distances. Thus, different areas of the Basin are relatively isolated from each other, allowing spatial factors like elevation and proximity to sources to strongly influence ozone concentrations at individual sites.

Changes in the structural composition and reactivity of Acer rubrum leaf litter tannins exposed to warming and altered precipitation: climatic stress-induced tannins are more reactive.

PubMed

Tharayil, Nishanth; Suseela, Vidya; Triebwasser, Daniella J; Preston, Caroline M; Gerard, Patrick D; Dukes, Jeffrey S

2011-07-01

• Climate change could increase the frequency with which plants experience abiotic stresses, leading to changes in their metabolic pathways. These stresses may induce the production of compounds that are structurally and biologically different from constitutive compounds. • We studied how warming and altered precipitation affected the composition, structure, and biological reactivity of leaf litter tannins in Acer rubrum at the Boston-Area Climate Experiment, in Massachusetts, USA. • Warmer and drier climatic conditions led to higher concentrations of protective compounds, including flavonoids and cutin. The abundance and structure of leaf tannins also responded consistently to climatic treatments. Drought and warming in combination doubled the concentration of total tannins, which reached 30% of leaf-litter DW. This treatment also produced condensed tannins with lower polymerization and a greater proportion of procyanidin units, which in turn reduced sequestration of tannins by litter fiber. Furthermore, because of the structural flexibility of these tannins, litter from this treatment exhibited five times more enzyme (β-glucosidase) complexation capacity on a per-weight basis. Warmer and wetter conditions decreased the amount of foliar condensed tannins. • Our finding that warming and drought result in the production of highly reactive tannins is novel, and highly relevant to climate change research as these tannins, by immobilizing microbial enzymes, could slow litter decomposition and thus carbon and nutrient cycling in a warmer, drier world. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

Structural diversity requires individual optimization of ethanol concentration in polysaccharide precipitation.

PubMed

Xu, Jun; Yue, Rui-Qi; Liu, Jing; Ho, Hing-Man; Yi, Tao; Chen, Hu-Biao; Han, Quan-Bin

2014-06-01

Ethanol precipitation is one of the most widely used methods for preparing natural polysaccharides, in which ethanol concentration significantly affects the precipitate yield, however, is usually set at 70-80%. Whether the standardization of ethanol concentration is appropriate has not been investigated. In the present study, the precipitation yields produced in varied ethanol concentrations (10-90%) were qualitatively and quantitatively evaluated by HPGPC (high-performance gel-permeation chromatography), using two series of standard glucans, namely dextrans and pullulans, as reference samples, and then eight natural samples. The results indicated that the response of a polysaccharide's chemical structure, with diversity in structural features and molecular sizes, to ethanol concentration is the decisive factor in precipitation of these glucans. Polysaccharides with different structural features, even though they have similar molecular weights, exhibit significantly different precipitation behaviors. For a specific glucan, the lower its molecular size, the higher the ethanol concentration needed for complete precipitation. The precipitate yield varied from 10% to 100% in 80% ethanol as the molecular size increased from 1kDa to 270kDa. This paper aims to draw scientists' attention to the fact that, in extracting natural polysaccharides by ethanol precipitation, the ethanol concentration must be individually optimized for each type of material. Copyright © 2014 Elsevier B.V. All rights reserved.

Spectroscopic investigation of the influence of calcium ion on the structures of casein micelles.

PubMed

Wang, Peng-Jie; Wu, Jian-Ping; Zhang, Hao; Guo, Hui-Yuan; Liu, Hong-Na; Ren, Fa-Zheng

2014-01-01

The effects of calcium ion on the structural properties of casein micelles in the course of heat treatment were synthetically examined by non-structure-invasive spectrometry. The hydrophobicity, reflected by extrinsic fluorescence (ANS fluorescence), was positively correlated with the concentration of the calcium ion, within the range of 0 to 12 mmol x L(-1). Meanwhile, the turbidity and stability of casein micelles also increased with the growth of calcium concentrations. However, opposite results were observed for hydrodynamic diameter and polydispersity index. Compared with the calcium ion, the calcium-chelator (citrate) has an opposite effect on the structural characteristics of casein micelles. Within the calcium concentrations range of 0 to 12 mmol x L(-1), the hydrophobicity, stability and turbidity were negatively correlated with the concentration of the calcium ion, nevertheless, opposite results were observed for hydrodynamic diameter and polydispersity index. All the results indicate that the calcium ion could be used to modify the structures of casein micelles during heat heatment.

Bismuth doping effect on crystal structure and photodegradation activity of Bi-TiO2 nanoparticles

NASA Astrophysics Data System (ADS)

Wu, Ming-Chung; Chang, Yin-Hsuan; Lin, Ting-Han

2017-04-01

The bismuth precursor is adopted as dopant to synthesize bismuth doped titanium dioxide nanoparticles (Bi-TiO2 NPs) with sol-gel method following by the thermal annealing treatment. We systematically developed a series of Bi-TiO2 NPs at several calcination temperatures and discovered the corresponding crystal structure by varying the bismuth doping concentration. At a certain 650 °C calcination temperature, the crystal structure of bismuth titanate (Bi2Ti2O7) is formed when the bismuth doping concentration is as high as 10.0 mol %. The photocatalytic activity of Bi-TiO2 NPs is increased by varying the doping concentration at the particular calcination temperature. By the definition X-ray diffraction (XRD) structural identification, a phase diagram of Bi-TiO2 NPs in doping concentration versus calcination temperature is provided. It can be useful for further study in the crystal structure engineering and the development of photocatalyst.

Processing/structure/property Relationships of Barium Strontium Titanate Thin Films for Dynamic Random Access Memory Application.

NASA Astrophysics Data System (ADS)

Peng, Cheng-Jien

The purpose of this study is to see the application feasibility of barium strontium titanate (BST) thin films on ultra large scale integration (ULSI) dynamic random access memory (DRAM) capacitors through the understanding of the relationships among processing, structure and electrical properties. Thin films of BST were deposited by multi-ion -beam reactive sputtering (MIBERS) technique and metallo -organic decomposition (MOD) method. The processing parameters such as Ba/Sr ratio, substrate temperature, annealing temperature and time, film thickness and doping concentration were correlated with the structure and electric properties of the films. Some effects of secondary low-energy oxygen ion bombardment were also examined. Microstructures of BST thin films could be classified into two types: (a) Type I structures, with multi-grains through the film thickness, for amorphous as-grown films after high temperature annealing, and (b) columnar structure (Type II) which remained even after high temperature annealing, for well-crystallized films deposited at high substrate temperatures. Type I films showed Curie-von Schweidler response, while Type II films showed Debted type behavior. Type I behavior may be attributed to the presence of a high density of disordered grain boundaries. Two types of current -voltage characteristics could be seen in non-bombarded films depending on the chemistry of the films (doped or undoped) and substrate temperature during deposition. Only the MIBERS films doped with high donor concentration and deposited at high substrate temperature showed space-charge -limited conduction (SCLC) with discrete shallow traps embedded in trap-distributed background at high electric field. All other non-bombarded films, including MOD films, showed trap-distributed SCLC behavior with a slope of {~}7.5-10 due to the presence of grain boundaries through film thickness or traps induced by unavoidable acceptor impurities in the films. Donor-doping could significantly improve the time -dependent dielectric breakdown (TDDB) behavior of BST thin films, mostly likely due to the lower oxygen vacancy concentration resulted from donor-doping.

Evaluation of an anal sac adenocarcinoma tumor in a Spitz dog.

PubMed

Javanbakht, Javad; Tavassoli, Abbas; Sabbagh, Atefeh; Hassan, Mehdy Aghamohammmad; Samakkhah, Shohreh Alian; Shafiee, Radmehr; Lakzian, Ali; Ghalee, Vahideh Rahmani; Gharebagh, Sonia Shoja

2013-01-01

A 9-year-old emasculated male Spitz with tenesmus and constipation had a subcutaneous mass at the left ventral aspect of the anus with history of polyuria and polydipsia. A complete blood cell count, serum biochemistry panel, and urinalysis (cystocentesis sample) were evaluated. Abnormalities in the serum biochemistry panel included a mildly elevated serum cholesterol concentration (7.28 mmol/L; reference interval, 2.70-5.94 mmol/L), increased serum alkaline phosphatase activity (184 U/L; reference interval, 9-90 U/L), alanine transaminase (122 U/L; reference interval, 5-60 U/L) activity and aspartate aminotransferase (80 U/L; reference interval, 5-55 U/L) activity, severe increased total calcium concentration (16.3 mg/dL; reference interval, 8.2-12.4 mg/dL or 9.3-11.4 mg/dL), and decreased total calcium concentration (3.4 mg/dL, reference interval, 2.5-5.6mg/dL). Furthermore, testing revealed an increased intact parathyroid hormone concentration (38.6 pmol/L; reference interval, 3-17 pmol/L). On cytologic and histopathologic examinations, various types of cells were observed. Most of the cells were oval to polygonal and had elliptical or elongate nuclei and a moderate amount of pale to basophilic cytoplasm. The remaining cells had round to oval nuclei and pale to basophilic cytoplasm. Cells of both types were loosely adhered to each other and were arranged in rosette-like structures. Both neoplastic cell types had fine homogenous chromatin and either a small indistinct nucleolus or no visible nucleolus. Mild anisokaryosis and anisocytosis were observed. Histologically, the mass consists of glandular structures formed by cuboidal cells admixed with bundles of spindle cells. Based on location and histologic features, the final diagnosis was adenocarcinoma of the apocrine gland of the anal sac, which should be included as a cytologic differential diagnosis when spindle cells and typical epithelial cells are observed in masses in the region of the anal sac of dogs.

Micromechanics of Sea Urchin Spines

PubMed Central

Tsafnat, Naomi; Fitz Gerald, John D.; Le, Hai N.; Stachurski, Zbigniew H.

2012-01-01

The endoskeletal structure of the Sea Urchin, Centrostephanus rodgersii, has numerous long spines whose known functions include locomotion, sensing, and protection against predators. These spines have a remarkable internal microstructure and are made of single-crystal calcite. A finite-element model of the spine’s unique porous structure, based on micro-computed tomography (microCT) and incorporating anisotropic material properties, was developed to study its response to mechanical loading. Simulations show that high stress concentrations occur at certain points in the spine’s architecture; brittle cracking would likely initiate in these regions. These analyses demonstrate that the organization of single-crystal calcite in the unique, intricate morphology of the sea urchin spine results in a strong, stiff and lightweight structure that enhances its strength despite the brittleness of its constituent material. PMID:22984468

Impact of monovalent cations on soil structure. Part I. Results of an Iranian soil

NASA Astrophysics Data System (ADS)

Farahani, Elham; Emami, Hojat; Keller, Thomas; Fotovat, Amir; Khorassani, Reza

2018-01-01

This study investigated the impact of monovalent cations on clay dispersion, aggregate stability, soil pore size distribution, and saturated hydraulic conductivity on agricultural soil in Iran. The soil was incubated with treatment solutions containing different concentrations (0-54.4 mmol l-1) of potassium and sodium cations. The treatment solutions included two levels of electrical conductivity (EC=3 or 6 dS m-1) and six K:Na ratios per electrical conductivity level. At both electrical conductivity levels, spontaneously dispersible clay increased with increasing K concentration, and with increasing K:Na ratio. A negative linear relationship between percentage of water-stable aggregates and spontaneously dispersible clay was observed. Clay dispersion generally reduced the mean pore size, presumably due to clogging of pores, resulting in increased water retention. At both electrical conductivity levels, hydraulic conductivity increased with increasing exchangeable potassium percentage at low exchangeable potassium percentage values, but decreased with further increases in exchangeable potassium percentage at higher exchangeable potassium percentage. This is in agreement with earlier studies, but seems in conflict with our data showing increasing spontaneously dispersible clay with increasing exchangeable potassium percentage. Our findings show that clay dispersion increased with increasing K concentration and increasing K:Na ratio, demonstrating that K can have negative impacts on soil structure.

Antimicrobial effect of the Lingzhi or Reishi medicinal mushroom, Ganoderma lucidum (higher Basidiomycetes) and its main compounds.

PubMed

Vazirian, Mahdi; Faramarzi, Mohammad Ali; Ebrahimi, Seyed Esmaeil Sadat; Esfahani, Hamid Reza Monsef; Samadi, Nasrin; Hosseini, Seyed Aboulfazl; Asghari, Ali; Manayi, Azadeh; Mousazadeh, Ali; Asef, Mohammad Reza; Habibi, Emran; Amanzadeh, Yaghoub

2014-01-01

Mushrooms are considered one of the richest sources of natural antibiotics, and various species of them inhibit the growth of a wide diversity of microorganisms. Ganoderma lucidum, a well-known medicinal mushroom. has many pharmacological and biological activities including an antimicrobial effect, although few studies have investigated the antibacterial and antifungal effects of its purified compounds. The chemical structure of the purified compounds from the hexane fraction was elucidated as ergosta-7,22-dien-3β-yl acetate, ergosta-5,7,22-trien-3β-yl acetate (isopyrocalciferol acetate), ergosta-7,22-dien-3-one, ergosta-7,22-dien-3β-ol, and ergosta-5,7,22-trien-3β-ol (ergostrol). In addition, the structure of ganodermadiol was demonstrated after purification from the chloroform fraction. The fractions inhibited Gram-positive bacteria and yeast, with minimum inhibitory concentration values of 6.25 mg/mL, but were ineffective against Gram-negative bacteria in the tested concentrations. The results were comparable for isolated compounds, whereas the mixture of ergosta-7,22-dien-3β-yl acetate and isopyrocalciferol acetate was weakly effective against Escherichia coli (minimum inhibitory concentration, 10 mg/mL). It could be assumed that the antimicrobial effect of crude fractions is the consequence of mixing triterpenoid and steroid compounds.

Mechanisms for Covalent Immobilization of Horseradish Peroxidase on Ion-Beam-Treated Polyethylene

PubMed Central

Kondyurin, Alexey V.; Naseri, Pourandokht; Tilley, Jennifer M. R.; Nosworthy, Neil J.; Bilek, Marcela M. M.; McKenzie, David R.

2012-01-01

The surface of polyethylene was modified by plasma immersion ion implantation. Structure changes including carbonization and oxidation were observed. High surface energy of the modified polyethylene was attributed to the presence of free radicals on the surface. The surface energy decay with storage time after treatment was explained by a decay of the free radical concentration while the concentration of oxygen-containing groups increased with storage time. Horseradish peroxidase was covalently attached onto the modified surface by the reaction with free radicals. Appropriate blocking agents can block this reaction. All aminoacid residues can take part in the covalent attachment process, providing a universal mechanism of attachment for all proteins. The native conformation of attached protein is retained due to hydrophilic interactions in the interface region. The enzymatic activity of covalently attached protein remained high. The long-term activity of the modified layer to attach protein is explained by stabilisation of unpaired electrons in sp2 carbon structures. A high concentration of free radicals can give multiple covalent bonds to the protein molecule and destroy the native conformation and with it the catalytic activity. The universal mechanism of protein attachment to free radicals could be extended to various methods of radiation damage of polymers. PMID:24278665

Study on rheological properties of CMC/Eu-Tb solutions with different concentrations

NASA Astrophysics Data System (ADS)

Fu, Z. C.; Ye, J.; Xiong, J.

2018-05-01

The rheological properties of polymer solution are sensitive to variations in the polymer structure. Carboxymethyl cellulose (CMC) aqueous solution has been used in many fields, such as food, medicine and paper industry. In this paper, the effects of different concentrations (2% - 6%) of CMC/Eu-Tb on their rheological properties were investigeted, including steady-state flow and viscoelastic response. The results show that, the viscosity of CMC/Eu-Tb is lower than that of CMC, at the same concentrations; the products solutions present a nearly Newtonian behavior at the low concentrations (2% - 3%); while at the higher concentrations (4% - 6%), the products solutions present a pseudoplastic behavior; shear-thinning behavior is due to the polymer chains unravel under the action of flow and the molecular chains are oriented in the flow direction. The results also show that the viscosity of the solutions decreases with increasing temperature. Dynamic rheological tests show that CMC/Eu-Tb has viscoelasticity in the concentrations of 2% - 6%. At lower concentrations, the elastic modulus G‧ is slightly higher than the viscous modulus G″, and as the concentrations increase, the elastic modulus G‧ is significantly higher than the viscous modulus G″. It means that at the lower solution concentrations, the solutions tend to be less elastic and easier to flow. Most of the energies are lost through the viscous flow. As the solution concentrations increase, the solutions tend to be more elastic, and the system tends to form a gel.

Landscape moderation of biodiversity patterns and processes - eight hypotheses.

PubMed

Tscharntke, Teja; Tylianakis, Jason M; Rand, Tatyana A; Didham, Raphael K; Fahrig, Lenore; Batáry, Péter; Bengtsson, Janne; Clough, Yann; Crist, Thomas O; Dormann, Carsten F; Ewers, Robert M; Fründ, Jochen; Holt, Robert D; Holzschuh, Andrea; Klein, Alexandra M; Kleijn, David; Kremen, Claire; Landis, Doug A; Laurance, William; Lindenmayer, David; Scherber, Christoph; Sodhi, Navjot; Steffan-Dewenter, Ingolf; Thies, Carsten; van der Putten, Wim H; Westphal, Catrin

2012-08-01

Understanding how landscape characteristics affect biodiversity patterns and ecological processes at local and landscape scales is critical for mitigating effects of global environmental change. In this review, we use knowledge gained from human-modified landscapes to suggest eight hypotheses, which we hope will encourage more systematic research on the role of landscape composition and configuration in determining the structure of ecological communities, ecosystem functioning and services. We organize the eight hypotheses under four overarching themes. Section A: 'landscape moderation of biodiversity patterns' includes (1) the landscape species pool hypothesis-the size of the landscape-wide species pool moderates local (alpha) biodiversity, and (2) the dominance of beta diversity hypothesis-landscape-moderated dissimilarity of local communities determines landscape-wide biodiversity and overrides negative local effects of habitat fragmentation on biodiversity. Section B: 'landscape moderation of population dynamics' includes (3) the cross-habitat spillover hypothesis-landscape-moderated spillover of energy, resources and organisms across habitats, including between managed and natural ecosystems, influences landscape-wide community structure and associated processes and (4) the landscape-moderated concentration and dilution hypothesis-spatial and temporal changes in landscape composition can cause transient concentration or dilution of populations with functional consequences. Section C: 'landscape moderation of functional trait selection' includes (5) the landscape-moderated functional trait selection hypothesis-landscape moderation of species trait selection shapes the functional role and trajectory of community assembly, and (6) the landscape-moderated insurance hypothesis-landscape complexity provides spatial and temporal insurance, i.e. high resilience and stability of ecological processes in changing environments. Section D: 'landscape constraints on conservation management' includes (7) the intermediate landscape-complexity hypothesis-landscape-moderated effectiveness of local conservation management is highest in structurally simple, rather than in cleared (i.e. extremely simplified) or in complex landscapes, and (8) the landscape-moderated biodiversity versus ecosystem service management hypothesis-landscape-moderated biodiversity conservation to optimize functional diversity and related ecosystem services will not protect endangered species. Shifting our research focus from local to landscape-moderated effects on biodiversity will be critical to developing solutions for future biodiversity and ecosystem service management. © 2012 The Authors. Biological Reviews © 2012 Cambridge Philosophical Society.

Asymmetric distribution of charged lipids between the leaflets of a vesicle bilayer induced by melittin and alamethicin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qian, Shuo; Heller, William T

2011-01-01

Cellular membranes are complex mixtures of lipids, proteins, and other small molecules that provide functional, dynamic barriers between the cell and its environment, as well as between environments within the cell. The lipid composition of the membrane is highly specific and controlled in terms of both content and lipid localization. The membrane structure results from the complex interplay between the wide varieties of molecules present. Here, small-angle neutron scattering and selective deuterium labeling were used to probe the impact of the membrane-active peptides melittin and alamethicin on the structure of lipid bilayers composed of a mixture of the lipids dimyristoylmore » phosphatidylglycerol (DMPG) and chain-perdeuterated dimyristoyl phosphatidylcholine (DMPC). We found that both peptides enriched the outer leaflet of the bilayer with the negatively charged DMPG, creating an asymmetric distribution of lipids. The level of enrichment is peptide concentration-dependent and is stronger for melittin than it is for alamethicin. The enrichment between the inner and outer bilayer leaflets occurs at very low peptide concentrations and increases with peptide concentration, including when the peptide adopts a membrane-spanning, pore-forming state. The results suggest that these membrane-active peptides may have a secondary stressful effect on target cells at low concentrations that results from a disruption of the lipid distribution between the inner and outer leaflets of the bilayer that is independent of the formation of transmembrane pores.« less

A Change in the Solar He II EUV Global Network Structure as an Indicator of the Geo-Effectiveness of Solar Minima

NASA Technical Reports Server (NTRS)

Didkovsky, L.; Gurman, J. B.

2013-01-01

Solar activity during 2007 - 2009 was very low, causing anomalously low thermospheric density. A comparison of solar extreme ultraviolet (EUV) irradiance in the He II spectral band (26 to 34 nm) from the Solar Extreme ultraviolet Monitor (SEM), one of instruments on the Charge Element and Isotope Analysis System (CELIAS) on board the Solar and Heliospheric Observatory (SOHO) for the two latest solar minima showed a decrease of the absolute irradiance of about 15 +/- 6 % during the solar minimum between Cycles 23 and 24 compared with the Cycle 22/23 minimum when a yearly running-mean filter was used. We found that some local, shorter-term minima including those with the same absolute EUV flux in the SEM spectral band show a higher concentration of spatial power in the global network structure from the 30.4 nm SOHO/Extreme ultraviolet Imaging Telescope (EIT) images for the local minimum of 1996 compared with the minima of 2008 - 2011.We interpret this higher concentration of spatial power in the transition region's global network structure as a larger number of larger-area features on the solar disk. These changes in the global network structure during solar minima may characterize, in part, the geo-effectiveness of the solar He II EUV irradiance in addition to the estimations based on its absolute levels.

Deciphering Cryptic Binding Sites on Proteins by Mixed-Solvent Molecular Dynamics.

PubMed

Kimura, S Roy; Hu, Hai Peng; Ruvinsky, Anatoly M; Sherman, Woody; Favia, Angelo D

2017-06-26

In recent years, molecular dynamics simulations of proteins in explicit mixed solvents have been applied to various problems in protein biophysics and drug discovery, including protein folding, protein surface characterization, fragment screening, allostery, and druggability assessment. In this study, we perform a systematic study on how mixtures of organic solvent probes in water can reveal cryptic ligand binding pockets that are not evident in crystal structures of apo proteins. We examine a diverse set of eight PDB proteins that show pocket opening induced by ligand binding and investigate whether solvent MD simulations on the apo structures can induce the binding site observed in the holo structures. The cosolvent simulations were found to induce conformational changes on the protein surface, which were characterized and compared with the holo structures. Analyses of the biological systems, choice of probes and concentrations, druggability of the resulting induced pockets, and application to drug discovery are discussed here.

Local Structure Determination of Carbon/Nickel Ferrite Composite Nanofibers Probed by X-ray Absorption Spectroscopy.

PubMed

Nilmoung, Sukunya; Kidkhunthod, Pinit; Maensiri, Santi

2015-11-01

Carbon/NiFe2O4 composite nanofibers have been successfully prepared by electrospinning method using a various concentration solution of Ni and Fe nitrates dispersed into polyacrylonitride (PAN) solution in N,N' dimethylformamide. The phase and mophology of PAN/NiFe2O4 composite samples were characterized and investigated by X-ray diffraction and scanning electron microscopy. The magnetic properties of the prepared samples were measured at ambient temperature by a vibrating sample magnetometer. It is found that all composite samples exhibit ferromagnetism. This could be local-structurally explained by the existed oxidation states of Ni2+ and Fe3+ in the samples. Moreover, local environments around Ni and Fe ions could be revealed by X-ray absorption spectroscopy (XAS) measurement including X-ray absorption near edge structure (XANES) and Extended X-ray absorption fine structure (EXAFS).

Recent developments in broadly applicable structure-biodegradability relationships.

PubMed

Jaworska, Joanna S; Boethling, Robert S; Howard, Philip H

2003-08-01

Biodegradation is one of the most important processes influencing concentration of a chemical substance after its release to the environment. It is the main process for removal of many chemicals from the environment and therefore is an important factor in risk assessments. This article reviews available methods and models for predicting biodegradability of organic chemicals from structure. The first section of the article briefly discusses current needs for biodegradability estimation methods related to new and existing chemicals and in the context of multimedia exposure models. Following sections include biodegradation test methods and endpoints used in modeling, with special attention given to the Japanese Ministry of International Trade and Industry test; a primer on modeling, describing the various approaches that have been used in the structure/biodegradability relationship work, and contrasting statistical and mechanistic approaches; and recent developments in structure/biodegradability relationships, divided into group contribution, chemometric, and artificial intelligence approaches.

New Polyphenols from a Deep Sea Spiromastix sp. Fungus, and Their Antibacterial Activities

PubMed Central

Niu, Siwen; Liu, Dong; Proksch, Peter; Shao, Zongze; Lin, Wenhan

2015-01-01

Eleven new polyphenols namely spiromastols A–K (1–11) were isolated from the fermentation broth of a deep sea-derived fungus Spiromastix sp. MCCC 3A00308. Their structures were determined by extensive NMR data and mass spectroscopic analysis in association with chemical conversion. The structures are classified as diphenyl ethers, diphenyl esters and isocoumarin derivatives, while the n-propyl group in the analogues is rarely found in natural products. Compounds 1–3 exhibited potent inhibitory effects against a panel of bacterial strains, including Xanthomanes vesicatoria, Pseudomonas lachrymans, Agrobacterium tumefaciens, Ralstonia solanacearum, Bacillus thuringensis, Staphylococcus aureus and Bacillus subtilis, with minimal inhibitory concentration (MIC) values ranging from 0.25 to 4 µg/mL. The structure-activity relationships are discussed, while the polychlorinated analogues 1–3 are assumed to be a promising structural model for further development as antibacterial agents. PMID:25913707

Dot-Projection Photogrammetry and Videogrammetry of Gossamer Space Structures

NASA Technical Reports Server (NTRS)

Pappa, Richard S.; Black, Jonathan T.; Blandino, Joseph R.; Jones, Thomas W.; Danehy, Paul M.; Dorrington, Adrian A.

2003-01-01

This paper documents the technique of using hundreds or thousands of projected dots of light as targets for photogrammetry and videogrammetry of gossamer space structures. Photogrammetry calculates the three-dimensional coordinates of each target on the structure, and videogrammetry tracks the coordinates versus time. Gossamer structures characteristically contain large areas of delicate, thin-film membranes. Examples include solar sails, large antennas, inflatable solar arrays, solar power concentrators and transmitters, sun shields, and planetary balloons and habitats. Using projected-dot targets avoids the unwanted mass, stiffness, and installation costs of traditional retroreflective adhesive targets. Four laboratory applications are covered that demonstrate the practical effectiveness of white-light dot projection for both static-shape and dynamic measurement of reflective and diffuse surfaces, respectively. Comparisons are made between dot-projection videogrammetry and traditional laser vibrometry for membrane vibration measurements. The paper closes by introducing a promising extension of existing techniques using a novel laser-induced fluorescence approach.

Variability in the gas phase composition of fluids discharged from Los Azufres geothermal field, Mexico

NASA Astrophysics Data System (ADS)

Santoyo, E.; Verma, S. P.; Nieva, D.; Portugal, E.

1991-07-01

Studies related to hydrological structure of the Los Azufres geothermal field and its effects on the exploitation of the field for generation of electrical energy have included a program of sampling and chemical analysis of fluids discharged by a number of deep wells in continuous production. Chemical analysis of the gaseous phase includes monitoring of CO 2, H 2S, NH 3, H 2, He, N 2, CH 4 and 222Rn. Five wells in Los Azufres field were periodically sampled during 1983-1988. The monitoring program has shown considerable variability in the gas concentrations of fluids. Before mid-1985, the 'base-line' concentrations of the gases showed standard deviations between 8 and 28%. During the later period, the average concentrations of different gases ranged from 37% to much higher values above the 'base-line'. The largest variations are observed in He, CO 2 and 222Rn. This variability is interpreted in terms of (1) addition of 'excess steam', (2) a possible relationship with earthquake events that occurred in México during September 19-21, 1985, and early May to early June of 1987 and, (3) more recent variations (after mid-1987), increased exploitation of the field.

Effects of haze pollution on microbial community changes and correlation with chemical components in atmospheric particulate matter.

PubMed

Sun, Yujiao; Xu, Shangwei; Zheng, Danyang; Li, Jie; Tian, Hezhong; Wang, Yong

2018-05-10

In this study, particulate matter (PM) with aerodynamic diameters of ≤2.5 and ≤10 μm (PM 2.5 and PM 10 , respectively), which was found at different concentrations in spring, was collected in Beijing. The chemical composition and bacterial community diversity of PM were determined, and the relationship between them was studied by 16S rRNA sequencing and mathematical statistics. Chemical composition analysis revealed greater relative percentages of total organic compounds (TOC) and secondary ions (NO 3 - , SO 4 2- , and NH 4 + ). The concentrations of Ca 2+ , Na + , Mg 2+ , K + and SO 4 2- increased in high-concentration PM, which was associated with the contribution of soil, dust and soot. Microbiological analysis revealed 1191 operational taxonomic units. Microbial community structure was stable at the phylum level. The most abundant phyla were Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes and Cyanobacteria. Community clustering analysis at the genus level showed that the difference in bacterial community structure between different PM concentrations (clean air vs. smog) was greater than that between different particle sizes. The dominant genera varied in different concentrations of PM. An unclassified genus of Cyanobacteria and Comamonadaceae were most abundant in low- and high-concentration PM, respectively. The microbial community structure was dynamic at the genus level due to different environmental factors. The dominant bacteria in high-concentration PM were widely distributed in soils, indicating that the soil contributed more to the increase in the PM. The individual microbes that were detected did not increase significantly as the PM concentration increased. The bacterial community structure was strongly correlated with K + , Ca 2+ , Na + , Mg 2+ , SO 4 2- and TOC in high-concentration PM and had a good correlation with NO 3 - , Cl - , NH 4 + and TIC in low-concentration PM. Soil and dust contributed to the increase in the concentration of the particles, and the relevant chemical components also produced differences in the bacterial community structure in different concentrations of PM. Copyright © 2018. Published by Elsevier B.V.

Effects of boron on structure and antioxidative activities of spleen in rats.

PubMed

Hu, Qianqian; Li, Shenghe; Qiao, Enmei; Tang, Zhongtao; Jin, Erhui; Jin, Guangming; Gu, Youfang

2014-04-01

In order to determine the relationship between boron and development of the spleen, especially in the promoting biological effects, we examined the effects of different levels of boron on weight, organ index, microstructure, and antioxidative activities of the spleen in rats. Sprague-Dawley (SD) rats were selected and treated with different concentrations of boron, and then, the organs were resected and weighed. One half of the tissue was fixed and embedded in paraffin to observe tissue structure changes. The other half of the tissue was homogenated for determining the antioxidant activities. The results showed that 40 mg/L of boron could increase weight, organ indexes, and antioxidant capacity of spleens and improve the spleen tissue structure, while the boron concentration above 80 mg/L could decrease weight, organ indexes, and antioxidant capacity of spleens and damage the spleen tissue structure. The higher the concentration, the more serious the damage was. Especially at the concentration of 640 mg/L, it could significantly inhibit the development of the spleen and even exhibit toxic effect. Hence, low boron concentration played a protective role in the development of the spleen, while high boron concentration could damage the organs and even produce toxic effect.

Effect of Trisodium Citrate Concentration on the Structural and Photodiode Performance of CdO Thin Films

NASA Astrophysics Data System (ADS)

Ravikumar, M.; Valanarasu, S.; Chandramohan, R.; Jacob, S. Santhosh Kumar; Kathalingam, A.

2015-08-01

CdO thin films were deposited on glass and silicon substrates by simple perfume atomizer at 350°C using cadmium acetate and trisodium citrate (TSC). The effect of the TSC concentration on the structural, morphological, optical, and photoconductive properties of the prepared CdO thin films was investigated. X-Ray diffraction (XRD) studies of the deposited films revealed improvement in crystalline nature with increase of TSC concentration. Films prepared without TSC showed porous nature, not fully covering the substrate, whereas films prepared using TSC exhibited full coverage of the substrate with uniform particles. Optical transmittance study of the films showed high transmittance (50% to 60%), and the absorption edge was found to shift towards the red region depending on the TSC concentration. The films exhibited a direct band-to-band transition with bandgap varying between 2.31 eV and 2.12 eV. Photoconductivity studies of the n-CdO/ p-Si structure for various TSC concentrations were also carried out. I- V characteristics of this n-CdO/ p-Si structure revealed the formation of rectifying junctions, and its photoconductivity was found to increase with the TSC concentration.

The two gap transitions in Ge1 -xSnx : Effect of non-substitutional complex defects

NASA Astrophysics Data System (ADS)

Querales-Flores, J. D.; Ventura, C. I.; Fuhr, J. D.; Barrio, R. A.

2016-09-01

The existence of non-substitutional β-Sn defects in Ge1 -xSnx alloys was confirmed by emission channeling experiments [Decoster et al., Phys. Rev. B 81, 155204 (2010)], which established that, although most Sn enters substitutionally (α-Sn) in the Ge lattice, a second significant fraction corresponds to the Sn-vacancy defect complex in the split-vacancy configuration (β-Sn), in agreement with our previous theoretical study [Ventura et al., Phys. Rev. B 79, 155202 (2009)]. Here, we present the electronic structure calculations for Ge1 -xSnx , including the substitutional α-Sn as well as the non-substitutional β-Sn defects. To include the presence of the non-substitutional complex defects in the electronic structure calculation for this multi-orbital alloy problem, we extended the approach for the purely substitutional alloy by Jenkins and Dow [Phys. Rev. B 36, 7994 (1987)]. We employed an effective substitutional two-site cluster equivalent to the real non-substitutional β-Sn defect, which was determined by a Green's functions calculation. We then calculated the electronic structure of the effective alloy purely in terms of substitutional defects, embedding the effective substitutional clusters in the lattice. Our results describe the two transitions of the fundamental gap of Ge1 -xSnx as a function of the total Sn-concentration: namely, from an indirect to a direct gap, first, and the metallization transition at a higher x. They also highlight the role of β-Sn in the reduction of the concentration range, which corresponds to the direct-gap phase of this alloy of interest for the optoelectronics applications.

Light Scattering Characterization of Elastin-Like Polypeptide Trimer Micelles

NASA Astrophysics Data System (ADS)

Tsuper, Ilona; Terrano, Daniel; Maraschky, Adam; Holland, Nolan; Streletzky, Kiril

The elastin-like polypeptides (ELP) nanoparticles are composed of three-armed star polypeptides connected by a negatively charged foldon. Each of the three arms extending from the foldon domain includes 20 repeats of the (GVGVP) amino acid sequence. The ELP polymer chains are soluble at room temperature and become insoluble at the transition temperature (close to 50 ° C), forming micelles. The size and shape of the micelle are dependent on the temperature and the pH of the solution, and on the concentration of the phosphate buffered saline (PBS). The depolarized dynamic light scattering (DDLS) was employed to study the structure and dynamics of micelles at 62 ° C. The solution was maintained at an approximate pH level of 7.3 - 7.5, while varying PBS concentration. At low salt concentrations (<15 mM), the micelle radius was about 10nm but not very reproducible on account of unstable pH levels arising from low buffer concentrations. At intermediate salt concentrations (15 - 60 mM), the system formed spherically-shaped micelles, exhibiting a steady growth in the hydrodynamic radius (Rh) from 10 to 21 nm, with increasing PBS concentration. Interestingly, higher salt concentrations (>60 mM) displayed an apparent elongation of the micelles evident by a significant VH signal, along with a surge in the apparent Rh. A model of micelle growth (and potential elongation) with increase in salt concentration is considered.

THz Properties of Adhesives

NASA Astrophysics Data System (ADS)

Stübling, E.; Gomell, L.; Sommer, S.; Winkel, A.; Kahlmeyer, M.; Böhm, S.; Koch, M.

2018-04-01

We determined the THz properties of 12 different adhesives which are mainly used for industrial purposes. The adhesives applied can be classified according to their chemical structure: epoxy resins, acrylic resins, and polyurethane based materials. This work represents a basis for future studies, which will concentrate on aging effects, including the absorption of water of adhesive joints. Thus, the dielectric properties of the unaged adhesives are investigated and the results of these measurements are described herein.

Sea shell solar collector

DOEpatents

Rabl, Ari

1976-01-01

A device is provided for the collection and concentration of solar radiant energy including a longitudinally extending structure having a wall for directing radiant energy. The wall is parabolic with its focus along a line parallel to an extreme ray of the sun at one solstice and with its axis along a line parallel to an extreme ray of the sun at the other solstice. An energy absorber is positioned to receive the solar energy thereby collected.

DARPA Helicopter Quieting Program W911NF0410424

DTIC Science & Technology

2009-05-01

Leishman , J. G. and Beddoes , T. S., “A Semi-Empirical Model for Dynamic Stall ,” Journal of the American Heli- copter Society, Vol. 34, No. 3, July 1989...of physical phenomena that include transonic and compressibility effects on the advancing blade, dynamic stall on the retreating blades and the...research approach is that even the most advanced models of a given discipline, e.g., comprehensive structural or flight dynamics codes , concentrate on a very

Accuracy improvement of interferometric Rayleigh scattering diagnostic

NASA Astrophysics Data System (ADS)

Yan, Bo; Chen, Li; Yin, Kewei; Chen, Shuang; Yang, Furong; Tu, Xiaobo

2017-10-01

Cavity structure is used to increase the Interferometric Rayleigh scattering signal intensity. By using ZEMAX method, we simulate a special cavity mode comprising two spherical reflectors with different size, including the focal length and the diameter. The simulations suggest that the parallel beam can reflect repeatedly in the resonant cavity and concentrate on the focus. Besides, the reflection times and the ray width can reach about 50 and 2.1 cm after some feasible solutions.

THz Properties of Adhesives

NASA Astrophysics Data System (ADS)

Stübling, E.; Gomell, L.; Sommer, S.; Winkel, A.; Kahlmeyer, M.; Böhm, S.; Koch, M.

2018-06-01

We determined the THz properties of 12 different adhesives which are mainly used for industrial purposes. The adhesives applied can be classified according to their chemical structure: epoxy resins, acrylic resins, and polyurethane based materials. This work represents a basis for future studies, which will concentrate on aging effects, including the absorption of water of adhesive joints. Thus, the dielectric properties of the unaged adhesives are investigated and the results of these measurements are described herein.

Analysis of Fluorinated Polyimides Flown on the Materials International Space Station Experiment

NASA Technical Reports Server (NTRS)

Finckenor, M. M.; Rodman, L.; Farmer, B.

2015-01-01

This Technical Memorandum documents the results from the Materials on International Space Station Experiment (MISSE) series involving fluorinated polyimide films analyzed at NASA Marshall Space Flight Center. These films may be used in thermal control, sunshield, solar sail, solar concentrator, and other lightweight polymer film applications. Results include postflight structural integrity, visual observations, determination of atomic oxygen erosion yield, and optical property changes as compared to preflight values.

Investigation of Molecular Structure and Thermal Properties of Thermo-Oxidative Aged SBS in Blends and Their Relations

PubMed Central

Xu, Xiong; Yu, Jianying; Xue, Lihui; Zhang, Canlin; Zha, Yagang; Gu, Yi

2017-01-01

Tri-block copolymer styrene–butadiene (SBS) is extensively applied in bituminous highway construction due to its high elasticity and excellent weather resistance. With the extension of time, tri-block structural SBS automatically degrades into bi-block structural SB- with some terminal oxygen-containing groups under the comprehensive effects of light, heat, oxygen, etc. In this paper, the effects of aging temperature, aging time and oxygen concentration on the molecular structure of thermo-oxidative aged SBS were mainly investigated using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), and the correlation between oxygen-containing groups and thermal properties (TG–DTG) was further discussed. The FTIR and XPS results show that rapid decomposition of SBS will occur with increments of aging temperature, aging time and oxygen concentration, and a large number of oxygen-containing groups such as –OH, C=O, –COOH, etc. will be formed during thermo-oxidative aging. In short-term aging, changes in aging temperature and oxygen concentration have a significant impact on the structural damage of SBS. However, in long-term aging, it has no further effect on the molecular structure of SBS or on increasing oxygen concentration. The TG and DTG results indicate that the concentration of substances with low molecular weight gradually increases with the improvement of the degree of aging of the SBS, while the initial decomposition rate increases at the beginning of thermal weightlessness and the decomposition rate slows down in comparison with neat SBS. From the relation between the XPS and TG results, it can be seen that the initial thermal stability of SBS rapidly reduces as the relative concentration of the oxygen-containing groups accumulates around 3%, while the maximum decomposition temperature slowly decreases when the relative concentration of the oxygen-containing groups is more than 3%, due to the difficult damage to strong bonds on the molecular structure of aged SBS. PMID:28773124

Investigation of Molecular Structure and Thermal Properties of Thermo-Oxidative Aged SBS in Blends and Their Relations.

PubMed

Xu, Xiong; Yu, Jianying; Xue, Lihui; Zhang, Canlin; Zha, Yagang; Gu, Yi

2017-07-07

Tri-block copolymer styrene-butadiene (SBS) is extensively applied in bituminous highway construction due to its high elasticity and excellent weather resistance. With the extension of time, tri-block structural SBS automatically degrades into bi-block structural SB- with some terminal oxygen-containing groups under the comprehensive effects of light, heat, oxygen, etc. In this paper, the effects of aging temperature, aging time and oxygen concentration on the molecular structure of thermo-oxidative aged SBS were mainly investigated using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), and the correlation between oxygen-containing groups and thermal properties (TG-DTG) was further discussed. The FTIR and XPS results show that rapid decomposition of SBS will occur with increments of aging temperature, aging time and oxygen concentration, and a large number of oxygen-containing groups such as -OH, C=O, -COOH, etc. will be formed during thermo-oxidative aging. In short-term aging, changes in aging temperature and oxygen concentration have a significant impact on the structural damage of SBS. However, in long-term aging, it has no further effect on the molecular structure of SBS or on increasing oxygen concentration. The TG and DTG results indicate that the concentration of substances with low molecular weight gradually increases with the improvement of the degree of aging of the SBS, while the initial decomposition rate increases at the beginning of thermal weightlessness and the decomposition rate slows down in comparison with neat SBS. From the relation between the XPS and TG results, it can be seen that the initial thermal stability of SBS rapidly reduces as the relative concentration of the oxygen-containing groups accumulates around 3%, while the maximum decomposition temperature slowly decreases when the relative concentration of the oxygen-containing groups is more than 3%, due to the difficult damage to strong bonds on the molecular structure of aged SBS.

Near-Field Receiving Water Monitoring of Trace Metals and a Benthic Community Near the Palo Alto Regional Water Quality Control Plant in South San Francisco Bay, California: 2008

USGS Publications Warehouse

Cain, Daniel J.; Thompson, Janet K.; Dyke, Jessica; Parcheso, Francis; Luoma, Samuel N.; Hornberger, Michelle I.

2009-01-01

Results reported herein include trace element concentrations in sediment and in the clam Macoma petalum (formerly reported as Macoma balthica (Cohen and Carlton, 1995)), clam reproductive activity, and benthic macroinvertebrate community structure for a mudflat one kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in South San Francisco Bay. This report includes data collected for the period January 2008 to December 2008 and extends a critical long-term biogeochemical record dating back to 1974. These data serve as the basis for the City of Palo Alto's Near-Field Receiving Water Monitoring Program, initiated in 1994. In 2008, metal concentrations in both sediments and clam tissue were among the lowest concentrations on record and consistent with results observed since 1991. Following significant reductions in the late 1980's, silver (Ag) and copper (Cu) concentrations appeared to have stabilized. Annual mean concentrations have fluctuated modestly (2-4 fold) in a nondirectional manner. Data for other metals, including chromium, mercury, nickel, selenium, vanadium, and zinc, have been collected since 1994. Over this period, concentrations of these elements, which more likely reflect regional inputs and systemwide processes, have remained relatively constant, aside from typical seasonal variation that is common to all elements. Within years, concentrations generally reach maximum in winter months (January-March) and decline to annual minima in spring through fall. Mercury (Hg) in sediments spiked to the highest observed level in January 2008. However, sedimentary concentrations for the rest of the year and concentrations of Hg in M. petalum for the entire year were consistent with data from previous years. Average selenium (Se) concentrations in sediment were the highest on record, but there is no evidence, yet, to suggest a temporal trend of increasing sedimentary Se. Selenium in M. petalum was not elevated relative to past years. Overall, Cu and Ag concentrations in sediments and soft tissues of the clam, M. petalum, remained representative of the concentrations observed since 1991 following significant reductions in the discharge of these elements from PARWQCP, suggesting that, similar to other elements of regulatory interest, regional scale factors now largely influence sedimentary and bioavailable concentrations of Cu and Ag. Analyses of the benthic-community structure of a mudflat in South San Francisco Bay over a 31-year period show that changes in the community have occurred concurrent with reduced concentrations of metals in the sediment and in the tissues of the biosentinel clam, M. petalum, from the same area. Analysis of the reproductive activity of M. petalum shows increases in reproductive activity concurrent with the decline in metal concentrations in the tissues of this organism. Reproductive activity is presently stable, with almost all animals initiating reproduction in the fall and spawning the following spring of most years. The community has shifted from being dominated by several opportunistic species to a community where the species are more similar in abundance, a pattern that suggests a more stable community that is subjected to less stress. In addition, two of the opportunistic species (Ampelisca abdita and Streblospio benedicti) that brood their young and live on the surface of the sediment in tubes, have shown a continual decline in dominance coincident with the decline in metals. Heteromastus filiformis, a subsurface polychaete worm that lives in the sediment, consumes sediment and organic particles residing in the sediment, and reproduces by laying their eggs on or in the sediment, has shown a concurrent increase in dominance and is now showing signs of population stability. An unidentified disturbance occurred on the mudflat in early 2008 that resulted in the loss of the benthic animals, except for those deep dwelling animals like Macoma petalum.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Pragati, E-mail: pkumar.phy@gmail.com; Department of Physics and Astrophysics, University of Delhi, Delhi, 110 007; Saxena, Nupur

This work shows the influence of Ag concentration on structural properties of pulsed laser deposited nanocrystalline CdS thin film. X-ray photoelectron spectroscopy (XPS) studies confirm the dopant concentration in CdS films and atomic concentration of elements. XPS studies show that the samples are slightly sulfur deficient. GAXRD scan reveals the structural phase transformation from cubic to hexagonal phase of CdS without appearance of any phase of CdO, Ag{sub 2}O or Ag{sub 2}S suggesting the substitutional doping of Ag ions. Photoluminescence studies illustrate that emission intensity increases with increase in dopant concentration upto 5% and then decreases for higher dopant concentration.

Integrated monitoring of wind plant systems

NASA Astrophysics Data System (ADS)

Whelan, Matthew J.; Janoyan, Kerop D.; Qiu, Tong

2008-03-01

Wind power is a renewable source of energy that is quickly gaining acceptance by many. Advanced sensor technologies have currently focused solely on improving wind turbine rotor aerodynamics and increasing of the efficiency of the blade design and concentration. Alternatively, potential improvements in wind plant efficiency may be realized through reduction of reactionary losses of kinetic energy to the structural and substructural systems supporting the turbine mechanics. Investigation of the complete dynamic structural response of the wind plant is proposed using a large-scale, high-rate wireless sensor network. The wireless network enables sensors to be placed across the sizable structure, including the rotating blades, without consideration of cabling issues and the economic burden associated with large spools of measurement cables. A large array of multi-axis accelerometers is utilized to evaluate the modal properties of the system as well as individual members and would enable long-term structural condition monitoring of the wind turbine as well. Additionally, environmental parameters, including wind speed, temperature, and humidity, are wirelessly collected for correlation. Such a wireless system could be integrated with electrical monitoring sensors and actuators and incorporated into a remote multi-turbine centralized plant monitoring and control system.

Self-assembly of knots and links

NASA Astrophysics Data System (ADS)

Orlandini, Enzo; Polles, Guido; Marenduzzo, Davide; Micheletti, Cristian

2017-03-01

Guiding the self-assembly of identical building blocks towards complex three-dimensional structures with a set of desired properties is a major goal in material science, chemistry and physics. A particularly challenging problem, especially explored in synthetic chemistry, is that of self-assembling closed structures with a target topology starting by simple geometrical templates. Here we overview and revisit recent advancements, based on stochastic simulations, where the geometry of rigid helical templates with functionalised sticky ends has been designed for self-assembling efficiently and reproducibly into a wide range of three-dimensional closed structures. Notably, these include non trivial topologies of links and knots, including the 819 knot that we had predicted to be highly encodable and that has only recently been obtained experimentally. By appropriately tuning the parameters that define the template shape, we show that, for fixed concentration of templates, the assembly process can be directed towards the formation of specific knotted and linked structures such as the trefoils, pentafoil knots, Hopf and Solomon links. More exotic and unexpected knots and links are also found. Our results should be relevant to the design of new protocols that can both increase and broaden the population of synthetise molecular knots and catenanes.

Near-atomic-resolution cryo-EM analysis of the Salmonella T3S injectisome basal body.

PubMed

Worrall, L J; Hong, C; Vuckovic, M; Deng, W; Bergeron, J R C; Majewski, D D; Huang, R K; Spreter, T; Finlay, B B; Yu, Z; Strynadka, N C J

2016-12-14

The type III secretion (T3S) injectisome is a specialized protein nanomachine that is critical for the pathogenicity of many Gram-negative bacteria, including purveyors of plague, typhoid fever, whooping cough, sexually transmitted infections and major nosocomial infections. This syringe-shaped 3.5-MDa macromolecular assembly spans both bacterial membranes and that of the infected host cell. The internal channel formed by the injectisome allows for the direct delivery of partially unfolded virulence effectors into the host cytoplasm. The structural foundation of the injectisome is the basal body, a molecular lock-nut structure composed predominantly of three proteins that form highly oligomerized concentric rings spanning the inner and outer membranes. Here we present the structure of the prototypical Salmonella enterica serovar Typhimurium pathogenicity island 1 basal body, determined using single-particle cryo-electron microscopy, with the inner-membrane-ring and outer-membrane-ring oligomers defined at 4.3 Å and 3.6 Å resolution, respectively. This work presents the first, to our knowledge, high-resolution structural characterization of the major components of the basal body in the assembled state, including that of the widespread class of outer-membrane portals known as secretins.

Experimental sulfate amendment alters peatland bacterial community structure.

PubMed

Strickman, R J S; Fulthorpe, R R; Coleman Wasik, J K; Engstrom, D R; Mitchell, C P J

2016-10-01

As part of a long-term, peatland-scale sulfate addition experiment, the impact of varying sulfate deposition on bacterial community responses was assessed using 16S tag encoded pyrosequencing. In three separate areas of the peatland, sulfate manipulations included an eight year quadrupling of atmospheric sulfate deposition (experimental), a 3-year recovery to background deposition following 5years of elevated deposition (recovery), and a control area. Peat concentrations of methylmercury (MeHg), a bioaccumulative neurotoxin, were measured, the production of which is attributable to a growing list of microorganisms, including many sulfate-reducing Deltaproteobacteria. The total bacterial and Deltaproteobacterial community structures in the experimental treatment differed significantly from those in the control and recovery treatments that were either indistinguishable or very similar to one another. Notably, the relatively rapid return (within three years) of bacterial community structure in the recovery treatment to a state similar to the control, demonstrates significant resilience of the peatland bacterial community to changes in atmospheric sulfate deposition. Changes in MeHg accumulation between sulfate treatments correlated with changes in the Deltaproteobacterial community, suggesting that sulfate may affect MeHg production through changes in the community structure of this group. Copyright © 2016 Elsevier B.V. All rights reserved.

The Effect of Electronic Structure on the Phases Present in High Entropy Alloys

PubMed Central

Leong, Zhaoyuan; Wróbel, Jan S.; Dudarev, Sergei L.; Goodall, Russell; Todd, Iain; Nguyen-Manh, Duc

2017-01-01

Multicomponent systems, termed High Entropy Alloys (HEAs), with predominantly single solid solution phases are a current area of focus in alloy development. Although different empirical rules have been introduced to understand phase formation and determine what the dominant phases may be in these systems, experimental investigation has revealed that in many cases their structure is not a single solid solution phase, and that the rules may not accurately distinguish the stability of the phase boundaries. Here, a combined modelling and experimental approach that looks into the electronic structure is proposed to improve accuracy of the predictions of the majority phase. To do this, the Rigid Band model is generalised for magnetic systems in prediction of the majority phase most likely to be found. Good agreement is found when the predictions are confronted with data from experiments, including a new magnetic HEA system (CoFeNiV). This also includes predicting the structural transition with varying levels of constituent elements, as a function of the valence electron concentration, n, obtained from the integrated spin-polarised density of states. This method is suitable as a new predictive technique to identify compositions for further screening, in particular for magnetic HEAs. PMID:28059106

The Effect of Electronic Structure on the Phases Present in High Entropy Alloys.

PubMed

Leong, Zhaoyuan; Wróbel, Jan S; Dudarev, Sergei L; Goodall, Russell; Todd, Iain; Nguyen-Manh, Duc

2017-01-06

Multicomponent systems, termed High Entropy Alloys (HEAs), with predominantly single solid solution phases are a current area of focus in alloy development. Although different empirical rules have been introduced to understand phase formation and determine what the dominant phases may be in these systems, experimental investigation has revealed that in many cases their structure is not a single solid solution phase, and that the rules may not accurately distinguish the stability of the phase boundaries. Here, a combined modelling and experimental approach that looks into the electronic structure is proposed to improve accuracy of the predictions of the majority phase. To do this, the Rigid Band model is generalised for magnetic systems in prediction of the majority phase most likely to be found. Good agreement is found when the predictions are confronted with data from experiments, including a new magnetic HEA system (CoFeNiV). This also includes predicting the structural transition with varying levels of constituent elements, as a function of the valence electron concentration, n, obtained from the integrated spin-polarised density of states. This method is suitable as a new predictive technique to identify compositions for further screening, in particular for magnetic HEAs.

Fresnel Concentrators for Space Solar Power and Solar Thermal Propulsion

NASA Technical Reports Server (NTRS)

Bradford, Rodney; Parks, Robert W.; Craig, Harry B. (Technical Monitor)

2001-01-01

Large deployable Fresnel concentrators are applicable to solar thermal propulsion and multiple space solar power generation concepts. These concentrators can be used with thermophotovoltaic, solar thermionic, and solar dynamic conversion systems. Thin polyimide Fresnel lenses and reflectors can provide tailored flux distribution and concentration ratios matched to receiver requirements. Thin, preformed polyimide film structure components assembled into support structures for Fresnel concentrators provide the capability to produce large inflation-deployed concentrator assemblies. The polyimide film is resistant to the space environment and allows large lightweight assemblies to be fabricated that can be compactly stowed for launch. This work addressed design and fabrication of lightweight polyimide film Fresnel concentrators, alternate materials evaluation, and data management functions for space solar power concepts, architectures, and supporting technology development.

Photothermal evaluation of the influence of nicotine, antitumor drugs, and radiation on cellular absorbing structures

NASA Astrophysics Data System (ADS)

Zharov, Vladimir P.; Galitovsky, Valentin; Chowdhury, Parimal; Chambers, Timothy

2004-07-01

This short review presents findings from a recent evaluation of the diagnostic capabilities of a new experimental design of the advanced photothermal (PT) imaging system; specifically, its performance in studying the impact of nicotine, a combination of antitumor drugs, and radiation on the absorbing structures of various cells. We used this imaging system to test our hypothesis that low doses of chemicals or drugs lead to changes in cell metabolism, that these changes are accompanied by the shrinking of cellular absorbing zones (e.g. organelles), and that these reactions cause increased local absorption. Conversely, high (toxic) doses may lead to swelling of organelles or release of chromophores into the intracellular space, causing decreased local absorption. In this study, we compared PT images and PT responses of the pancreatic exocrine tumor cell line AR42J resulting from exposure to various concentrations of nicotine versus those of control cells. We found that responses were almost proportional to the drug concentration in concentrations ranging from 1 nM-100 μM, reached saturation at a maximum of approximately 100 μM-1 mM, and then fell rapidly at concentrations ranging from 1-50 mM. We also examined the influence of antitumor drugs (vinblastine and paclitaxel) on KB3 carcinoma cells, with drug concentrations ranging from 10-10 nM to 10 nM. In this instance, exposure initially led to slight cell activation, which was then followed by decreased cellular PT response. Drug administration led to corresponding changes in the amplitude and spatial intracellular localization of PT responses, including bubble formation, as an indicator of local absorption level. Additionally, it was shown that, depending on cell type, x-ray radiation may produce effects similar to those resulting from exposure to drugs. Independent verification with a combined PT-fluorescence assay and conventional staining kits (trypan blue, Annexin V-propidium iodide [PI]) revealed that this new PT assay has the potential to detect different stages of environmental impact, including changes in cell metabolism and apoptotic- and toxic-related phenomena, at a concentration threshold sensitivity at least three orders of magnitude better than existing assays. This assay may also help optimize combined cancer therapies.

Circadian variation in serum cortisol during hydrocortisone replacement is not attributable to changes in cortisol-binding globulin concentrations.

PubMed

Chung, T T; Gunganah, K; Monson, J P; Drake, W M

2016-04-01

Patients taking hydrocortisone (HC) replacement for primary or secondary adrenal failure require individual adjustment of their dose. In addition to modifying the administered doses of HC for each patient, physicians are increasingly interested in variations in the bioavailability of glucocorticoid replacement. One potential determinant of the bioavailability of replaced HC is a variation in serum cortisol-binding globulin (CBG) concentration, which may, in turn, affect interpretation of cortisol profiles and individual dose selection for patients on hydrocortisone replacement therapy. To investigate the hypothesis that there is a circadian variation in CBG levels. A total of 34 male patients divided into 3 groups (10 patients with non-somatotroph structural pituitary disease on HC replacement, 11 patients with treated acromegaly on HC replacement and 13 patients with treated acromegaly not on HC replacement) and 10 healthy volunteers were included. Cortisol and CBG levels were measured at 6 time points (0800, 1100, 1300, 1500, 1700 and 1900). No significant circadian variation in CBG concentration was found in any of the 4 groups. Circadian variation in serum cortisol during hydrocortisone replacement is not attributable to changes in cortisol-binding globulin concentration. Changes in serum cortisol levels may thus be explained by other factors including 11 β-hydroxysteroid dehydrogenase type 1 activity or circadian changes in the binding properties of CBG. © 2015 John Wiley & Sons Ltd.

Microfiber Optical Sensors: A Review

PubMed Central

Lou, Jingyi; Wang, Yipei; Tong, Limin

2014-01-01

With diameter close to or below the wavelength of guided light and high index contrast between the fiber core and the surrounding, an optical microfiber shows a variety of interesting waveguiding properties, including widely tailorable optical confinement, evanescent fields and waveguide dispersion. Among various microfiber applications, optical sensing has been attracting increasing research interest due to its possibilities of realizing miniaturized fiber optic sensors with small footprint, high sensitivity, fast response, high flexibility and low optical power consumption. Here we review recent progress in microfiber optical sensors regarding their fabrication, waveguide properties and sensing applications. Typical microfiber-based sensing structures, including biconical tapers, optical gratings, circular cavities, Mach-Zehnder interferometers and functionally coated/doped microfibers, are summarized. Categorized by sensing structures, microfiber optical sensors for refractive index, concentration, temperature, humidity, strain and current measurement in gas or liquid environments are reviewed. Finally, we conclude with an outlook for challenges and opportunities of microfiber optical sensors. PMID:24670720

Comparison between cerebrospinal fluid and serum lactate concentrations in neurologic dogs with and without structural intracranial disease.

PubMed

Benedicenti, Leontine; Gianotti, Giacomo; Galban, Evelyn M

2018-04-01

The objectives of this study were to investigate the relationship between cerebrospinal fluid lactate and serum concentrations in dogs with clinical signs of central nervous system disease and to establish if cerebrospinal fluid lactate (CSF) concentrations are higher in dogs with structural intracranial disease (Group Pos-MRI) compared to dogs that have clinical signs of intracranial disease but no structural brain disease (Group Neg-MRI) based on magnetic resonance imaging (MRI) findings. Using a prospective study canine blood and cerebrospinal fluid were collected in 24 dogs with neurological signs after undergoing brain MRI. Dogs were divided in 2 groups. No significant difference between serum lactate (1.57 ± 0.9 mmol/L) and CSF lactate concentration (1.34 ± 0.3 mmol/L) was detected. There was a direct correlation between CSF and serum lactate concentration ( R = 0.731; P = 0.01). No significant difference was found in CSF lactate concentration between the 2 groups of dogs ( P = 0.13).

X-Ray Photoelectron Spectroscopy Study of the Heating Effects on Pd/6H-SiC Schottky Structure

NASA Technical Reports Server (NTRS)

Chen, Liang-Yu; Hunter, Gary W.; Neudeck, Philip G.; Knight, Dak

1998-01-01

X-ray photoelectron spectroscopy is used to study the effects of heat treatment on the Pd/6H-SiC Schottky diode structure. After heating the structure at 425 C for 140 h, a very thin surface layer of PdO mixed with SiO(x) formed on the palladium surface of the Schottky structure. Heat treatment promoted interfacial diffusion and reaction which significantly broadened the interfacial region. In the interfacial region, the palladium concentration decreases with depth, and the interfacial products are Pd(x)Si (x = 1,2,3,4). In the high Pd concentration regions, Pd4Si is the major silicide component while gr and Pd2Si are major components in the low Pd concentration region. At the center of the interface, where the total palladium concentration equals that of silicon, the concentrations of palladium associated with various palladium silicides (Pd(x)Si, x= 1,2,3,4) are approximately equal. The surface passivation layer composed of PdO and SiO, may significantly affect the electronic and catalytic properties of the surface of the Schottky diode which plays a major role in gas detection. The electronic properties of the Schottky structure may be dominated by a (Pd+Pd(x)Si)/SiC interface. In order to stabilize the properties of the Schottky structure the surface and interface diffusion and reactions must be controlled.

Influence of vibration on structure rheological properties of a highly concentrated suspension

NASA Astrophysics Data System (ADS)

Ouriev Uriev, Boris N.; Uriev, Naum B.

2005-08-01

The influence of mechanical vibration on the flow properties of a highly concentrated multiphase food system is explored in this work. An experimental set-up was designed and adapted to a conventional rotational rheometer with precise rheological characterization capability. A number of calibration tests were performed prior to fundamental experiments with a highly concentrated chocolate suspension. Also, the prediction of wall slippage in shear flow under vibration was evaluated. Analysis of the boundary conditions shows that no side effects such as wall slippage or the Taylor effect were present during the shear experiment under vibration. It was found that superposition of mechanical vibration and shear flow radically decreases the shear viscosity. Comparison between reference shear viscosities at specified shear rates and those measured under vibration shows considerable differences in flow properties. Conversion of the behaviour of the concentrated suspension from strongly shear-thinning to Newtonian flow is reported. Also, the appearance of vibration-induced dilatancy as a new phenomenon is described. It is suggested to relate such phenomena to the non-equilibrium between structure formation and disintegration under vibration and hydrodynamic forces of shear flow. The influence of vibration on structure formation can be well observed during measurement of the yield value of the chocolate suspension under vibration. Comparison with reference data shows how sensitive the structure of the concentrated suspension is to vibration in general. The effects and observations revealed provide a solid basis for further fundamental investigations of structure formation regularities in the flow of any highly concentrated system. The results also show the technological potential for non-conventional treatment of concentrated, multiphase systems.

Lower Flathead System Fisheries Study, South Bay of Flathead Lake, Volume III, 1983-1987 Final Report.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cross, David; Waite, Ian

1988-06-01

The Lower Flathead System Fisheries Study assessed the effects of Kerr Dam operation on the fisheries of the lower Flathead ecosystem. South Bay, the southern most lobe of Flathead Lake, is the most extensive area of shallow water, and therefore, most effected by changes in lake levels. This study began in January of 1984 and was completed in early 1987. Vegetative and structural cover are relatively limited in South Bay, a condition which could contribute to lower recruitment for some fish species. Our data show that the study area contained 0.04% structural and 5.4% vegetative cover in June at fullmore » pool. Both figures are less than 1.0% at minimum pool. Structural complexity mediates the ecological interactions between littoral zone fish and their prey, and can affect local productivity and growth in fish. Structural complexity may also be important to overwinter survival of young perch in Flathead Lake. Winter conditions, including ice cover and fall drawdown, seasonally eliminate the vegetative portion of most rooted macrophytes in South Bay. This results in substantial loss of what little structural cover exists, depriving the perch population of habitat which has been occupied all summer. The loss of cover from draw-down concentrates and probably exposes perch to greater predation, including cannibalism, than would occur if structural complexity were greater. 33 refs., 10 figs., 5 tabs.« less

Use of terbium as a probe of tRNA tertiary structure and folding.

PubMed Central

Hargittai, M R; Musier-Forsyth, K

2000-01-01

Lanthanide metals such as terbium have previously been shown to be useful for mapping metal-binding sites in RNA. Terbium binds to the same sites on RNA as magnesium, however, with a much higher affinity. Thus, low concentrations of terbium ions can easily displace magnesium and promote phosphodiester backbone scission. At higher concentrations, terbium cleaves RNA in a sequence-independent manner, with a preference for single-stranded, non-Watson-Crick base-paired regions. Here, we show that terbium is a sensitive probe of human tRNALys,3 tertiary structure and folding. When 1 microM tRNA is used, the optimal terbium ion concentration for detecting Mg2+-induced tertiary structural changes is 50-60 microM. Using these concentrations of RNA and terbium, a magnesium-dependent folding transition with a midpoint (KMg) of 2.6 mM is observed for unmodified human tRNALys,3. At lower Tb3+ concentrations, cleavage is restricted to nucleotides that constitute specific metal-binding pockets. This small chemical probe should also be useful for detecting protein induced structural changes in RNA. PMID:11105765

Effects of model structural uncertainty on carbon cycle projections: biological nitrogen fixation as a case study

NASA Astrophysics Data System (ADS)

Wieder, William R.; Cleveland, Cory C.; Lawrence, David M.; Bonan, Gordon B.

2015-04-01

Uncertainties in terrestrial carbon (C) cycle projections increase uncertainty of potential climate feedbacks. Efforts to improve model performance often include increased representation of biogeochemical processes, such as coupled carbon-nitrogen (N) cycles. In doing so, models are becoming more complex, generating structural uncertainties in model form that reflect incomplete knowledge of how to represent underlying processes. Here, we explore structural uncertainties associated with biological nitrogen fixation (BNF) and quantify their effects on C cycle projections. We find that alternative plausible structures to represent BNF result in nearly equivalent terrestrial C fluxes and pools through the twentieth century, but the strength of the terrestrial C sink varies by nearly a third (50 Pg C) by the end of the twenty-first century under a business-as-usual climate change scenario representative concentration pathway 8.5. These results indicate that actual uncertainty in future C cycle projections may be larger than previously estimated, and this uncertainty will limit C cycle projections until model structures can be evaluated and refined.

Impact load-induced micro-structural damage and micro-structure associated mechanical response of concrete made with different surface roughness and porosity aggregates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erdem, Savas, E-mail: evxse1@nottingham.ac.uk; Dawson, Andrew Robert; Thom, Nicholas Howard

2012-02-15

The relationship between the nature of micro damage under impact loading and changes in mechanical behavior associated with different microstructures is studied for concretes made with two different coarse aggregates having significant differences mainly in roughness and porosity - sintered fly ash and uncrushed gravel. A range of techniques including X-ray diffraction, digital image analysis, mercury porosimetry, X-ray computed tomography, laser surface profilometry and scanning electron microscopy were used to characterize the aggregates and micro-structures. The concrete prepared with lightweight aggregates was stronger in compression than the gravel aggregate concrete due to enhanced hydration as a result of internal curing.more » In the lightweight concrete, it was deduced that an inhomogeneous micro-structure led to strain incompatibilities and consequent localized stress concentrations in the mix, leading to accelerated failure. The pore structure, compressibility, and surface texture of the aggregates are of paramount importance for the micro-cracking growth.« less

Self-assembly of nanocomposite materials

DOEpatents

Brinker, C. Jeffrey; Sellinger, Alan; Lu, Yunfeng

2001-01-01

A method of making a nanocomposite self-assembly is provided where at least one hydrophilic compound, at least one hydrophobic compound, and at least one amphiphilic surfactant are mixed in an aqueous solvent with the solvent subsequently evaporated to form a self-assembled liquid crystalline mesophase material. Upon polymerization of the hydrophilic and hydrophobic compounds, a robust nanocomposite self-assembled material is formed. Importantly, in the reaction mixture, the amphiphilic surfactant has an initial concentration below the critical micelle concentration to allow formation of the liquid-phase micellar mesophase material. A variety of nanocomposite structures can be formed, depending upon the solvent evaporazation process, including layered mesophases, tubular mesophases, and a hierarchical composite coating composed of an isotropic worm-like micellar overlayer bonded to an oriented, nanolaminated underlayer.

Mathematical modeling of urea transport in the kidney.

PubMed

Layton, Anita T

2014-01-01

Mathematical modeling techniques have been useful in providing insights into biological systems, including the kidney. This article considers some of the mathematical models that concern urea transport in the kidney. Modeling simulations have been conducted to investigate, in the context of urea cycling and urine concentration, the effects of hypothetical active urea secretion into pars recta. Simulation results suggest that active urea secretion induces a "urea-selective" improvement in urine concentrating ability. Mathematical models have also been built to study the implications of the highly structured organization of tubules and vessels in the renal medulla on urea sequestration and cycling. The goal of this article is to show how physiological problems can be formulated and studied mathematically, and how such models may provide insights into renal functions.

The AAA protein spastin possesses two levels of basal ATPase activity.

PubMed

Fan, Xiangyu; Lin, Zhijie; Fan, Guanghui; Lu, Jing; Hou, Yongfei; Habai, Gulijiazi; Sun, Linyue; Yu, Pengpeng; Shen, Yuequan; Wen, Maorong; Wang, Chunguang

2018-05-01

The AAA ATPase spastin is a microtubule-severing enzyme that plays important roles in various cellular events including axon regeneration. Herein, we found that the basal ATPase activity of spastin is negatively regulated by spastin concentration. By determining a spastin crystal structure, we demonstrate the necessity of intersubunit interactions between spastin AAA domains. Neutralization of the positive charges in the microtubule-binding domain (MTBD) of spastin dramatically decreases the ATPase activity at low concentration, although the ATP-hydrolyzing potential is not affected. These results demonstrate that, in addition to the AAA domain, the MTBD region of spastin is also involved in regulating ATPase activity, making interactions between spastin protomers more complicated than expected. © 2018 Federation of European Biochemical Societies.

Novel CO 2 Foam Concepts and Injection Schemes for Improving CO 2 Sweep Efficiency in Sandstone and Carbonate Hydrocarbon Formations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Quoc; Hirasaki, George; Johnston, Keith

2015-02-05

We explored cationic, nonionic and zwitterionic surfactants to identify candidates that have the potential to satisfy all the key requirements for CO 2 foams in EOR. We have examined the formation, texture, rheology and stability of CO 2 foams as a function of the surfactant structure and formulation variables including temperature, pressure, water/CO 2 ratio, surfactant concentration, salinity and concentration of oil. Furthermore, the partitioning of surfactants between oil and water as well as CO 2 and water was examined in conjunction with adsorption measurements on limestone by the Hirasaki lab to develop strategies to optimize the transport of surfactantsmore » in reservoirs.« less

Mechanism of salt-induced activity enhancement of a marine-derived laccase, Lac15.

PubMed

Li, Jie; Xie, Yanan; Wang, Rui; Fang, Zemin; Fang, Wei; Zhang, Xuecheng; Xiao, Yazhong

2018-04-01

Laccase (benzenediol: oxygen oxidoreductases, EC1.10.3.2) is a multi-copper oxidase capable of oxidizing a variety of phenolic and other aromatic organic compounds. The catalytic power of laccase makes it an attractive candidate for potential applications in many areas of industry including biodegradation of organic pollutants and synthesis of novel drugs. Most laccases are vulnerable to high salt and have limited applications. However, some laccases are not only tolerant to but also activated by certain concentrations of salt and thus have great application potential. The mechanisms of salt-induced activity enhancement of laccases are unclear as yet. In this study, we used dynamic light scattering, size exclusion chromatography, analytical ultracentrifugation, intrinsic fluorescence emission, circular dichroism, ultraviolet-visible light absorption, and an enzymatic assay to investigate the potential correlation between the structure and activity of the marine-derived laccase, Lac15, whose activity is promoted by low concentrations of NaCl. The results showed that low concentrations of NaCl exert little influence on the protein structure, which was partially folded in the absence of the salt; moreover, the partially folded rather than the fully folded state seemed to be favorable for enzyme activity, and this partially folded state was distinctive from the so-called 'molten globule' occasionally observed in active enzymes. More data indicated that salt might promote laccase activity through mechanisms involving perturbation of specific local sites rather than a change in global structure. Potential binding sites for chloride ions and their roles in enzyme activity promotion are proposed.

Tannic Acid Inhibits Hepatitis C Virus Entry into Huh7.5 Cells

PubMed Central

Hagedorn, Curt H.

2015-01-01

Chronic infection with the hepatitis C virus (HCV) is a cause of cirrhosis and hepatocellular carcinoma worldwide. Although antiviral therapy has dramatically improved recently, a number of patients remain untreated and some do not clear infection with treatment. Viral entry is an essential step in initiating and maintaining chronic HCV infections. One dramatic example of this is the nearly 100% infection of newly transplanted livers in patients with chronic hepatitis C. HCV entry inhibitors could play a critical role in preventing HCV infection of newly transplanted livers. Tannic acid, a polymer of gallic acid and glucose molecules, is a plant-derived polyphenol that defends some plants from insects and microbial infections. It has been shown to have a variety of biological effects, including antiviral activity, and is used as a flavoring agent in foods and beverages. In this study, we demonstrate that tannic acid is a potent inhibitor of HCV entry into Huh7.5 cells at low concentrations (IC50 5.8 μM). It also blocks cell-to-cell spread in infectious HCV cell cultures, but does not inhibit HCV replication following infection. Moreover, experimental results indicate that tannic acid inhibits an early step of viral entry, such as the docking of HCV at the cell surface. Gallic acid, tannic acid’s structural component, did not show any anti-HCV activity including inhibition of HCV entry or replication at concentrations up to 25 μM. It is possible the tannin structure is related on the effect on HCV inhibition. Tannic acid, which is widely distributed in plants and foods, has HCV antiviral activity in cell culture at low micromolar concentrations, may provide a relative inexpensive adjuvant to direct-acting HCV antivirals and warrants future investigation. PMID:26186636

(A)biotic processes control soil carbon dynamics: quantitative assessment of model complexity, stability and response to perturbations for improving ESMs

NASA Astrophysics Data System (ADS)

Georgiou, K.; Abramoff, R. Z.; Harte, J.; Riley, W. J.; Torn, M. S.

2016-12-01

As global temperatures and atmospheric CO2 concentrations continue to increase, soil microbial activity and decomposition of soil organic matter (SOM) are expected to follow suit, potentially limiting soil carbon storage. Traditional global- and ecosystem-scale models simulate SOM decomposition using linear kinetics, which are inherently unable to reproduce carbon-concentration feedbacks, such as priming of native SOM at elevated CO2 concentrations. Recent studies using nonlinear microbial models of SOM decomposition seek to capture these interactions, and several groups are currently integrating these microbial models into Earth System Models (ESMs). However, despite their widespread ability to exhibit nonlinear responses, these models vary tremendously in complexity and, consequently, dynamics. In this study, we explore, both analytically and numerically, the emergent oscillatory behavior and insensitivity of SOM stocks to carbon inputs that have been deemed `unrealistic' in recent microbial models. We discuss the sources of instability in four models of varying complexity, by sequentially reducing complexity of a detailed model that includes microbial physiology, a mineral sorption isotherm, and enzyme dynamics. We also present an alternative representation of microbial turnover that limits population sizes and, thus, reduces oscillations. We compare these models to several long-term carbon input manipulations, including the Detritus Input and Removal Treatment (DIRT) experiments, to show that there are clear metrics that can be used to distinguish and validate the inherent dynamics of each model structure. We find that traditional linear and nonlinear models cannot readily capture the range of long-term responses observed across the DIRT experiments as a direct consequence of their model structures, and that modifying microbial turnover results in more realistic predictions. Finally, we discuss our findings in the context of improving microbial model behavior for inclusion in ESMs.

Biomass allocation and nutrients balance related to the concentration of Nitrogen and Phosphorus in Salvinia auriculata (Salviniaceae).

PubMed

Medeiros, J C C; Coelho, F F; Teixeira, E

2016-06-01

Aquatic plants can use differential allocation (trade-off) of carbon among their structures depending on the nutrition concentration. Given that N and P are limiting in the growth of plants, our questions were: Are the N and P concentrations in S. auriculata related to the biomass allocation to its structures? Is a differential allocation of N and P between floating and submerged leaves? We evaluated the relation between the nutrients and the biomass allocation, and the trade-off among the leaves using the Spearman correlation. Our results showed that N and P concentrations in S. auriculata are related to the biomass allocation to its structures, and that there is no trade-off of these nutrients between "shoot and root". Thus, we can see the importance of N and P concentration in the biomass of S. auriculata, and why this plant is capable to development in different environments as a weedy.

Concentration, physical state, and purity of bacterial endotoxin affect its detoxification by ionizing radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Csako, G.; Tsai, C.M.; Hochstein, H.D.

Increasing concentrations of a highly purified bacterial lipopolysaccharide preparation, the U.S. Reference Standard Endotoxin, were exposed to increasing doses of ionizing radiation from a 60Co source. At identical radiation doses both the structural change and Limulus amebocyte lysate (LAL) reactivity were progressively smaller with increasing concentrations of the lipopolysaccharide in an aqueous medium. Under the experimental conditions used, there was a linear relationship between the endotoxin concentration and radiation dose for the structural changes. In contrast to endotoxin in aqueous medium, endotoxin irradiated in its dry state showed no decrease in LAL reactivity and rabbit pyrogenicity. Endotoxin exposed to radiationmore » in water in the presence of albumin showed a much smaller decrease in LAL and pyrogenic activities than expected. The results show that the concentration, physical state, and purity of endotoxin influence its structural and functional alteration by ionizing radiation.« less

Role of nitrite in the photochemical formation of radicals in the snow.

PubMed

Jacobi, Hans-Werner; Kleffmann, Jörg; Villena, Guillermo; Wiesen, Peter; King, Martin; France, James; Anastasio, Cort; Staebler, Ralf

2014-01-01

Photochemical reactions in snow can have an important impact on the composition of the atmosphere over snow-covered areas as well as on the composition of the snow itself. One of the major photochemical processes is the photolysis of nitrate leading to the formation of volatile nitrogen compounds. We report nitrite concentrations determined together with nitrate and hydrogen peroxide in surface snow collected at the coastal site of Barrow, Alaska. The results demonstrate that nitrite likely plays a significant role as a precursor for reactive hydroxyl radicals as well as volatile nitrogen oxides in the snow. Pollution events leading to high concentrations of nitrous acid in the atmosphere contributed to an observed increase in nitrite in the surface snow layer during nighttime. Observed daytime nitrite concentrations are much higher than values predicted from steady-state concentrations based on photolysis of nitrate and nitrite indicating that we do not fully understand the production of nitrite and nitrous acid in snow. The discrepancy between observed and expected nitrite concentrations is probably due to a combination of factors, including an incomplete understanding of the reactive environment and chemical processes in snow, and a lack of consideration of the vertical structure of snow.

A Novel Approach To Improve the Efficiency of Block Freeze Concentration Using Ice Nucleation Proteins with Altered Ice Morphology.

PubMed

Jin, Jue; Yurkow, Edward J; Adler, Derek; Lee, Tung-Ching

2017-03-22

Freeze concentration is a separation process with high success in product quality. The remaining challenge is to achieve high efficiency with low cost. This study aims to evaluate the potential of using ice nucleation proteins (INPs) as an effective method to improve the efficiency of block freeze concentration while also exploring the related mechanism of ice morphology. Our results show that INPs are able to significantly improve the efficiency of block freeze concentration in a desalination model. Using this experimental system, we estimate that approximately 50% of the energy cost can be saved by the inclusion of INPs in desalination cycles while still meeting the EPA standard of drinking water (<500 ppm). Our investigative tools for ice morphology include optical microscopy and X-ray computed tomography imaging analysis. Their use indicates that INPs promote the development of a lamellar structured ice matrix with larger hydraulic diameters, which facilitates brine drainage and contains less brine entrapment as compared to control samples. These results suggest great potential for applying INPs to develop an energy-saving freeze concentration method via the alteration of ice morphology.

Pair mobility functions for rigid spheres in concentrated colloidal dispersions: Stresslet and straining motion couplings

NASA Astrophysics Data System (ADS)

Su, Yu; Swan, James W.; Zia, Roseanna N.

2017-03-01

Accurate modeling of particle interactions arising from hydrodynamic, entropic, and other microscopic forces is essential to understanding and predicting particle motion and suspension behavior in complex and biological fluids. The long-range nature of hydrodynamic interactions can be particularly challenging to capture. In dilute dispersions, pair-level interactions are sufficient and can be modeled in detail by analytical relations derived by Jeffrey and Onishi [J. Fluid Mech. 139, 261-290 (1984)] and Jeffrey [Phys. Fluids A 4, 16-29 (1992)]. In more concentrated dispersions, analytical modeling of many-body hydrodynamic interactions quickly becomes intractable, leading to the development of simplified models. These include mean-field approaches that smear out particle-scale structure and essentially assume that long-range hydrodynamic interactions are screened by crowding, as particle mobility decays at high concentrations. Toward the development of an accurate and simplified model for the hydrodynamic interactions in concentrated suspensions, we recently computed a set of effective pair of hydrodynamic functions coupling particle motion to a hydrodynamic force and torque at volume fractions up to 50% utilizing accelerated Stokesian dynamics and a fast stochastic sampling technique [Zia et al., J. Chem. Phys. 143, 224901 (2015)]. We showed that the hydrodynamic mobility in suspensions of colloidal spheres is not screened, and the power law decay of the hydrodynamic functions persists at all concentrations studied. In the present work, we extend these mobility functions to include the couplings of particle motion and straining flow to the hydrodynamic stresslet. The couplings computed in these two articles constitute a set of orthogonal coupling functions that can be utilized to compute equilibrium properties in suspensions at arbitrary concentration and are readily applied to solve many-body hydrodynamic interactions analytically.

Interactions between concentric form-from-structure and face perception revealed by visual masking but not adaptation

PubMed Central

Feczko, Eric; Shulman, Gordon L.; Petersen, Steven E.; Pruett, John R.

2014-01-01

Findings from diverse subfields of vision research suggest a potential link between high-level aspects of face perception and concentric form-from-structure perception. To explore this relationship, typical adults performed two adaptation experiments and two masking experiments to test whether concentric, but not nonconcentric, Glass patterns (a type of form-from-structure stimulus) utilize a processing mechanism shared by face perception. For the adaptation experiments, subjects were presented with an adaptor for 5 or 20 s, prior to discriminating a target. In the masking experiments, subjects saw a mask, then a target, and then a second mask. Measures of discriminability and bias were derived and repeated measures analysis of variance tested for pattern-specific masking and adaptation effects. Results from Experiment 1 show no Glass pattern-specific effect of adaptation to faces; results from Experiment 2 show concentric Glass pattern masking, but not adaptation, may impair upright/inverted face discrimination; results from Experiment 3 show concentric and radial Glass pattern masking impaired subsequent upright/inverted face discrimination more than translational Glass pattern masking; and results from Experiment 4 show concentric and radial Glass pattern masking impaired subsequent face gender discrimination more than translational Glass pattern masking. Taken together, these findings demonstrate interactions between concentric form-from-structure and face processing, suggesting a possible common processing pathway. PMID:24563526

Effects of sludge retention time, carbon and initial biomass concentrations on selection process: From activated sludge to polyhydroxyalkanoate accumulating cultures.

PubMed

Chen, Zhiqiang; Huang, Long; Wen, Qinxue; Zhang, Huichao; Guo, Zirui

2017-02-01

Four sequence batch reactors (SBRs) fed by fermented sugar cane wastewater were continuously operated under the aerobic dynamic feeding (ADF) mode with different configurations of sludge retention time (SRT), carbon and initial biomass concentrations to enrich polyhydroxyalkanoate (PHA) accumulating mixed microbial cultures (MMCs) from municipal activated sludge. The stability of SBRs was investigated besides the enrichment performance. The microbial community structures of the enriched MMCs were analyzed using terminal restriction fragment length polymorphism (T-RFLP). The optimum operating conditions for the enrichment process were: SRT of 5days, carbon concentration of 2.52g COD/L and initial biomass concentration of 3.65g/L. The best enrichment performance in terms of both operating stability and PHA storage ability of enriched cultures (with the maximum PHA content and PHA storage yield (Y PHA/S ) of 61.26% and 0.68mg COD/mg COD, respectively) was achieved under this condition. Effects of the SRT, carbon concentration and initial biomass concentration on the PHA accumulating MMCs selection process were discussed respectively. A new model including the segmentation of the enrichment process and the effects of SRT on each phase was proposed. Copyright © 2016. Published by Elsevier B.V.

Vibration isolation mounting system

NASA Technical Reports Server (NTRS)

Carter, Sam D. (Inventor); Bastin, Paul H. (Inventor)

1995-01-01

A system is disclosed for mounting a vibration producing device onto a spacecraft structure and also for isolating the vibration forces thereof from the structure. The system includes a mount on which the device is securely mounted and inner and outer rings. The rings and mount are concentrically positioned. The system includes a base (secured to the structure) and a set of links which are interconnected by a set of torsion bars which allow and resist relative rotational movement therebetween. The set of links are also rotatably connected to a set of brackets which are rigidly connected to the outer ring. Damped leaf springs interconnect the inner and outer rings and the mount allow relative translational movement therebetween in X and Y directions. The links, brackets and base are interconnected and configured so that they allow and resist translational movement of the device in the Z direction so that in combination with the springs they provide absorption of vibrational energy produced by the device in all three dimensions while providing rotational stiffness about all three axes to prevent undesired rotational motions.

Measuring the retina optical properties using a structured illumination imaging system

NASA Astrophysics Data System (ADS)

Basiri, A.; Nguyen, T. A.; Ibrahim, M.; Nguyen, Q. D.; Ramella-Roman, Jessica C.

2011-03-01

Patients with diabetic retinopathy (DR) may experience a reduction in retinal oxygen saturation (SO2). Close monitoring with a fundus ophthalmoscope can help in the prediction of the progression of disease. In this paper we present a noninvasive instrument based on structured illumination aimed at measuring the retina optical properties including oxygen saturation. The instrument uses two wavelngths one in the NIR and one visible, a fast acquisition camera, and a splitter system that allows for contemporaneous collection of images at two different wavelengths. This scheme greatly reduces eye movement artifacts. Structured illumination was achieved in two different ways, firstly several binary illumination masks fabricated using laser micro-machining were used, a near-sinusoidal projection pattern is ultimately achieved at the image plane by appropriate positioning of the binary masks. Secondarily a sinusoidal pattern printed on a thin plastic sheet was positioned at image plane of a fundus ophthalmoscope. The system was calibrated using optical phantoms of known optical properties as well as an eye phantom that included a 150μm capillary vessel containing different concentrations of oxygenated and deoxygenated hemoglobin.

Multidisciplinary study (CO2 flux, ERT, self-potential, permeability and structural surveys) in Fondi di Baia, Astroni and Agnano volcanoes: insights for the structural architecture of the Campi Flegrei caldera (southern Italy)

NASA Astrophysics Data System (ADS)

Isaia, Roberto; Carapezza, Maria Luisa; Conti, Eric; Giulia Di Giuseppe, Maria; Lucchetti, Carlo; Prinzi, Ernesto; Ranaldi, Massimo; Tarchini, Luca; Tramparulo, Francesco; Troiano, Antonio; Vitale, Stefano; Cascella, Enrico; Castello, Nicola; Cicatiello, Alessandro; Maiolino, Marco; Puzio, Domenico; Tazza, Lucia; Villani, Roberto

2017-04-01

Recent volcanism at Campi Flegrei caldera produced more than 70 eruptions in the last 15 ka formed different volcanic edifices. The vent distribution was related to the main volcano-tectonic structure active in the caldera along which also concentrated part of the present hydrothermal and fumarolic activity, such as in the Solfatara area. In order to define the role of major faults in the Campi Flegrei Caldera, we analyzed some volcanic craters (Fondi di Baia and Astroni) and the Agnano caldera, by means of different geochemical and geophysical technics including CO2 flux, electrical resistivity (ERT), self-potential and permeability surveys. We provided some ERT profiles and different maps of geochemical and geophysical features. Major fault planes were identified comparing ERT imaging with alignments of anomalies in maps. The results can improve the knowledge on the present state of these volcanoes actually not fully monitored though included in the area with high probability of future vent opening within the Campi Flegrei caldera.

Structure and Soot Properties of Nonbuoyant Ethylene/Air Laminar Jet Diffusion Flames. Appendix E; Repr. from AIAA Journal, v. 36 p 1346-1360

NASA Technical Reports Server (NTRS)

Urban, D. L.; Yuan, Z.-G.; Sunderland, P. B.; Linteris, G. T.; Voss, J. E.; Lin, K.-C.; Dai, Z.; Sun, K.; Faeth, G. M.; Ross, Howard D. (Technical Monitor)

2001-01-01

The structure and soot properties of round, soot-emitting, nonbuoyant, laminar jet diffusion flames are described, based on long-duration (175-230-s) experiments at microgravity carried out on orbit in the Space Shuttle Columbia. Experimental conditions included ethylene-fueled flames burning in still air at nominal pressures of 50 and 100 kPa and an ambient temperature of 300 K with luminous flame lengths of 49-64 mm Measurements included luminous flame shapes using color video imaging soot concentration (volume fraction) distributions using deconvoluted laser extinction imaging, soot temperature distributions using deconvoluted multiline emission imaging, gas temperature distributions at fuel-lean (plume) conditions using thermocouple probes, soot structure distributions using thermophoretic sampling and analysis by transmission electron microscopy, and flame radiation using a radiometer.The present flames were larger, and emitted soot more readily, than comparable flames observed during ground-based microgravity experiments due to closer approach to steady conditions resulting from the longer test times and the reduced gravitational disturbances of the space-based experiments.

Carrier doping into a superconducting BaPb0.7Bi0.3O3‑δ epitaxial film using an electric double-layer transistor structure

NASA Astrophysics Data System (ADS)

Komori, S.; Kakeya, I.

2018-06-01

Doping evolution of the unconventional superconducting properties in BaBiO3-based compounds has yet to be clarified in detail due to the significant change of the oxygen concentration accompanied by the chemical substitution. We suggest that the carrier concentration of an unconventional superconductor, BaPb0.7Bi0.3O3‑δ , is controllable without inducing chemical or structural changes using an electric double-layer transistor structure. The critical temperature is found to decrease systematically with increasing carrier concentration.

Nondeterministic self-assembly of two tile types on a lattice.

PubMed

Tesoro, S; Ahnert, S E

2016-04-01

Self-assembly is ubiquitous in nature, particularly in biology, where it underlies the formation of protein quaternary structure and protein aggregation. Quaternary structure assembles deterministically and performs a wide range of important functions in the cell, whereas protein aggregation is the hallmark of a number of diseases and represents a nondeterministic self-assembly process. Here we build on previous work on a lattice model of deterministic self-assembly to investigate nondeterministic self-assembly of single lattice tiles and mixtures of two tiles at varying relative concentrations. Despite limiting the simplicity of the model to two interface types, which results in 13 topologically distinct single tiles and 106 topologically distinct sets of two tiles, we observe a wide variety of concentration-dependent behaviors. Several two-tile sets display critical behaviors in the form of a sharp transition from bound to unbound structures as the relative concentration of one tile to another increases. Other sets exhibit gradual monotonic changes in structural density, or nonmonotonic changes, while again others show no concentration dependence at all. We catalog this extensive range of behaviors and present a model that provides a reasonably good estimate of the critical concentrations for a subset of the critical transitions. In addition, we show that the structures resulting from these tile sets are fractal, with one of two different fractal dimensions.

Structural and optical properties of nano-structured CdS thin films prepared by chemical bath deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bai, Rekha, E-mail: rekha.mittal07@gmail.com; Kumar, Dinesh; Chaudhary, Sujeet

2016-05-06

Cadmium sulfide (CdS) thin films have been deposited on conducting glass substrates by chemical bath deposition (CBD) technique. The effect of precursor concentration on the structural, morphological, compositional, and optical properties of the CdS films has been studied. Crystal structure of these CdS films is characterized by X-ray diffraction (XRD) and it reveals polycrystalline structure with mixture of cubic and wurtzite phases with grain size decreasing as precursor concentration is increased. Optical studies reveal that the CdS thin films have high transmittance in visible spectral region reaching 90% and the films possess direct optical band gap that decreases from 2.46more » to 2.39 eV with decreasing bath concentration. Our study suggests that growth is nucleation controlled.« less

Safety Assessment of Methyl Glucose Polyethers and Esters as Used in Cosmetics.

PubMed

Johnson, Wilbur; Heldreth, Bart; Bergfeld, Wilma F; Belsito, Donald V; Hill, Ronald A; Klaassen, Curtis D; Liebler, Daniel C; Marks, James G; Shank, Ronald C; Slaga, Thomas J; Snyder, Paul W; Andersen, F Alan

2016-11-01

The Cosmetic Ingredient Review Expert Panel (Panel) reviewed the safety of methyl glucose polyethers and esters which function in cosmetics as skin/hair-conditioning agents, surfactants, or viscosity increasing agents. The esters included in this assessment are mono-, di-, or tricarboxyester substituted methyl glucosides, and the polyethers are mixtures of various chain lengths. The Panel reviewed available animal and clinical data, including the molecular weights, log K ow s, and other properties in making its determination of safety on these ingredients. Where there were data gaps, similarities between molecular structures, physicochemical and biological characteristics, and functions and concentrations in cosmetics allowed for extrapolation of the available toxicological data to assess the safety of the entire group. The Panel concluded that there likely would be no significant systemic exposure from cosmetic use of these ingredients, and that these ingredients are safe in cosmetic formulations in the present practices of use and concentration. © The Author(s) 2016.

Distribution of phytobenthos in the Yakima River basin, Washington, in relation to geology, land use, and other environmental factors

USGS Publications Warehouse

Leland, Harry V.

1995-01-01

Benthic-algal distributions in the Yakima River, Washington, basin were, examined in relation to geology, land use, water chemistry, and stream habitat using indicator-species classification (TWINSPAN) and canonical correspondence analysis (CCA). Algal assemblages identified byTWINSPAN were each associated with a narrow range of water-quality conditions. In the Cascade geologic province, where timber harvest and grazing are the dominant land uses, differences in community structure (CCA site scores) and concentrations of major ions (Ca and Mg) and nutrients (solute P, SiO2 and inorganic N) varied with dominant rock type of the basin. In agricultural areas of the Columbia Plateau province, differences in phytobenthos structure were based primarily on the degree of enrichment of dissolved solids, inorganic N, and solute P from irrigation-return flows and subsurface drainage. Habitat characteristics strongly correlated with community structure included reach altitude, turbidity, substratum embeddedness (Columbia Plateau), large woody-debris density (Cascade Range), and composition and density of the riparian vegetation. Algal biomass (AFDM) correlated with composition and density of the riparian vegetation but not with measured chemical-constituent concentrations. Nitrogen limitation in streams of the Cascade Range favored nitrogen-fixing blue-green algae and diatoms with endosymbiotic blue-greens, whereas nitrogen heterotrophs were abundant in agricultural areas of the Columbia Plateau.

Distribution of phytobenthos in the Yakima River basin, Washington, in relation to geology, land use and other environmental factors

USGS Publications Warehouse

Leland, Harry V.

1995-01-01

Benthic-algal distributions in the Yakima River, Washington, basin were, examined in relation to geology, land use, water chemistry, and stream habitat using indicator-species classification (TWINSPAN) and canonical correspondence analysis (CCA). Algal assemblages identified byTWINSPAN were each associated with a narrow range of water-quality conditions. In the Cascade geologic province, where timber harvest and grazing are the dominant land uses, differences in community structure (CCA site scores) and concentrations of major ions (Ca and Mg) and nutrients (solute P, SiO2 and inorganic N) varied with dominant rock type of the basin. In agricultural areas of the Columbia Plateau province, differences in phytobenthos structure were based primarily on the degree of enrichment of dissolved solids, inorganic N, and solute P from irrigation-return flows and subsurface drainage. Habitat characteristics strongly correlated with community structure included reach altitude, turbidity, substratum embeddedness (Columbia Plateau), large woody-debris density (Cascade Range), and composition and density of the riparian vegetation. Algal biomass (AFDM) correlated with composition and density of the riparian vegetation but not with measured chemical-constituent concentrations. Nitrogen limitation in streams of the Cascade Range favored nitrogen-fixing blue-green algae and diatoms with endosymbiotic blue-greens, whereas nitrogen heterotrophs were abundant in agricultural areas of the Columbia Plateau.

Structural Modeling of a Five-Meter Thin Film Inflatable Antenna/Concentrator With Rigidized Support Struts

NASA Technical Reports Server (NTRS)

Smalley, Kurt B.; Tinker, Michael L.

2001-01-01

Dynamic characterization of a non-rigidized thin film inflatable antenna/solar concentrator structure with rigidized composite support struts is described in detail. A two-step finite element modeling approach in MSC/NASTRAN is utilized, consisting of: (1) a nonlinear static pressurization procedure used to obtain the updated stiffness matrix, and (2) a modal "restart" eigen solution that uses the modified stiffness matrix. Unique problems encountered in modeling of this large 5-m lightweight inflatable are identified, including considerable difficulty in obtaining convergence in the nonlinear pressurization solution. It was found that the extremely thin polyimide film material (.001 in or I mil) presents tremendous problems in obtaining a converged solution when internal pressure loading is applied. It was concluded that the ratios of film thickness to other geometric dimensions such as torus cross-sectional and ring diameter and lenticular diameter are the critical parameters for convergence of the pressurization procedure. Comparison of finite element predictions for frequency and mode shapes with experimental results indicated reasonable agreement considering the complexity of the structure, the film-to-air interaction, and the nonlinear material properties of the film. It was also concluded that analysis should be done using different finite element to codes to determine if a more robust and stable solution can be obtained.

Quantitative structure-cytotoxicity relationship of piperic acid amides.

PubMed

Shimada, Chiyako; Uesawa, Yoshihiro; Ishihara, Mariko; Kagaya, Hajime; Kanamoto, Taisei; Terakubo, Shigemi; Nakashima, Hideki; Takao, Koichi; Miyashiro, Takaki; Sugita, Yoshiaki; Sakagami, Hiroshi

2014-09-01

A total of 12 piperic acid amides, including piperine, were subjected to quantitative structure-activity relationship (QSAR) analysis, based on their cytotoxicity, tumor selectivity and anti-HIV activity, in order to find new biological activities. Cytotoxicity against four human oral squamous cell carcinoma (OSCC) cell lines and three human oral normal cells was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Tumor selectivity was evaluated by the ratio of the mean 50% cytotoxic concentration (CC50) against normal oral cells to that against OSCC cell lines. Anti-HIV activity was evaluated by the ratio of the CC50 to 50% HIV infection-cytoprotective concentration (EC50). Physicochemical, structural, and quantum-chemical parameters were calculated based on the conformations optimized by LowModeMD method followed by density functional theory method. All compounds showed low-to-moderate tumor selectivity, but no anti-HIV activity. N-Piperoyldopamine ( 8: ) which has a catechol moiety, showed the highest tumor selectivity, possibly due to its unique molecular shape and electrostatic interaction, especially its largest partial equalization of orbital electronegativities and vsurf descriptors. The present study suggests that molecular shape and ability for electrostatic interaction are useful parameters for estimating the tumor selectivity of piperic acid amides. Copyright© 2014 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Optoelectronic transport properties in amorphous/crystalline silicon solar cell heterojunctions measured by frequency-domain photocarrier radiometry: multi-parameter measurement reliability and precision studies.

PubMed

Zhang, Y; Melnikov, A; Mandelis, A; Halliop, B; Kherani, N P; Zhu, R

2015-03-01

A theoretical one-dimensional two-layer linear photocarrier radiometry (PCR) model including the presence of effective interface carrier traps was used to evaluate the transport parameters of p-type hydrogenated amorphous silicon (a-Si:H) and n-type crystalline silicon (c-Si) passivated by an intrinsic hydrogenated amorphous silicon (i-layer) nanolayer. Several crystalline Si heterojunction structures were examined to investigate the influence of the i-layer thickness and the doping concentration of the a-Si:H layer. The experimental data of a series of heterojunction structures with intrinsic thin layers were fitted to PCR theory to gain insight into the transport properties of these devices. The quantitative multi-parameter results were studied with regard to measurement reliability (uniqueness) and precision using two independent computational best-fit programs. The considerable influence on the transport properties of the entire structure of two key parameters that can limit the performance of amorphous thin film solar cells, namely, the doping concentration of the a-Si:H layer and the i-layer thickness was demonstrated. It was shown that PCR can be applied to the non-destructive characterization of a-Si:H/c-Si heterojunction solar cells yielding reliable measurements of the key parameters.

Optoelectronic transport properties in amorphous/crystalline silicon solar cell heterojunctions measured by frequency-domain photocarrier radiometry: Multi-parameter measurement reliability and precision studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Y.; Institute of Electronic Engineering and Optoelectronic Technology, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094; Melnikov, A.

2015-03-15

A theoretical one-dimensional two-layer linear photocarrier radiometry (PCR) model including the presence of effective interface carrier traps was used to evaluate the transport parameters of p-type hydrogenated amorphous silicon (a-Si:H) and n-type crystalline silicon (c-Si) passivated by an intrinsic hydrogenated amorphous silicon (i-layer) nanolayer. Several crystalline Si heterojunction structures were examined to investigate the influence of the i-layer thickness and the doping concentration of the a-Si:H layer. The experimental data of a series of heterojunction structures with intrinsic thin layers were fitted to PCR theory to gain insight into the transport properties of these devices. The quantitative multi-parameter results weremore » studied with regard to measurement reliability (uniqueness) and precision using two independent computational best-fit programs. The considerable influence on the transport properties of the entire structure of two key parameters that can limit the performance of amorphous thin film solar cells, namely, the doping concentration of the a-Si:H layer and the i-layer thickness was demonstrated. It was shown that PCR can be applied to the non-destructive characterization of a-Si:H/c-Si heterojunction solar cells yielding reliable measurements of the key parameters.« less

Photodegradation of fluorene in aqueous solution: Identification and biological activity testing of degradation products.

PubMed

Kinani, Said; Souissi, Yasmine; Kinani, Aziz; Vujović, Svetlana; Aït-Aïssa, Sélim; Bouchonnet, Stéphane

2016-04-15

Degradation of fluorene under UV-vis irradiation in water was investigated and structural elucidation of the main photoproducts was achieved using gas chromatography coupled with mass spectrometry. Twenty-six photoproducts were structurally identified, mainly on the basis of electron ionization mass spectra interpretation. The main generated transformation products are hydroxy derivatives. Some secondary photoproducts including fluorenone, hydroxy fluorenone, 2-biphenyl carboxylic acid, biphenylene, methanol fluorene congeners and hydroxy fluorene dimers were also observed. A photodegradation pathway was suggested on the basis of the chemical structures of photoproducts. Fluorene as well as its main photoproducts for which chemical standards were commercially available were tested for their ability to elicit cytotoxic, estrogenic and dioxin-like activity by using in vitro cell-based bioassays. None of the tested compounds was cytotoxic at concentrations up to 100 μM. However, 2-hydroxyfluorene and 3-hydroxyfluorene exerted significant estrogenic and dioxin-like activity on a concentration range of 3-30 μM, while fluorene and 9-hydroxyfluorene were weakly or not active, respectively, in our assays. This supports the view that photodegradation processes can generate by-products of higher toxicological concern than the parent compound and strengthens the need to further identify transformation products in the aquatic environment. Copyright © 2016 Elsevier B.V. All rights reserved.

Genome Structures and Transcriptomes Signify Niche Adaptation for the Multiple-Ion-Tolerant Extremophyte Schrenkiella parvula1[C][W][OPEN

PubMed Central

Oh, Dong-Ha; Hong, Hyewon; Lee, Sang Yeol; Yun, Dae-Jin; Bohnert, Hans J.; Dassanayake, Maheshi

2014-01-01

Schrenkiella parvula (formerly Thellungiella parvula), a close relative of Arabidopsis (Arabidopsis thaliana) and Brassica crop species, thrives on the shores of Lake Tuz, Turkey, where soils accumulate high concentrations of multiple-ion salts. Despite the stark differences in adaptations to extreme salt stresses, the genomes of S. parvula and Arabidopsis show extensive synteny. S. parvula completes its life cycle in the presence of Na+, K+, Mg2+, Li+, and borate at soil concentrations lethal to Arabidopsis. Genome structural variations, including tandem duplications and translocations of genes, interrupt the colinearity observed throughout the S. parvula and Arabidopsis genomes. Structural variations distinguish homologous gene pairs characterized by divergent promoter sequences and basal-level expression strengths. Comparative RNA sequencing reveals the enrichment of ion-transport functions among genes with higher expression in S. parvula, while pathogen defense-related genes show higher expression in Arabidopsis. Key stress-related ion transporter genes in S. parvula showed increased copy number, higher transcript dosage, and evidence for subfunctionalization. This extremophyte offers a framework to identify the requisite adjustments of genomic architecture and expression control for a set of genes found in most plants in a way to support distinct niche adaptation and lifestyles. PMID:24563282

Relationship between pulp structure breakdown and nutritional value of papaya (Carica papaya) and strawberry (Fragaria x ananassa) nectars using alternative thermal and non-thermal processing techniques.

PubMed

Swada, Jeffrey G; Keeley, Christopher J; Ghane, Mohammad A; Engeseth, Nicki J

2016-05-01

Papaya and strawberry contain a wide array of nutrients that contribute to human health; however, availability of these fruits is limited due to their short shelf lives and seasonal nature. In this study, the effect of alternative techniques including ultra high temperature (UHT, 20-135 °C, 1-3 s) and irradiation (0-10 kGy) on carotenoid concentration, antioxidant capacity and changes to pulp structure using transmission electron microscopy were determined for papaya and strawberry nectars. UHT had moderate effects on antioxidant capacity, but the greatest overall release of carotenoids from the pulp matrix (34.2%, 6.26%, 8.31%; β-cryptoxanthin, β-carotene, and lycopene, respectively). Irradiation resulted in the greatest increase in antioxidant capacity [19.22 to 24.32 µmol Trolox equivalents kg(-1) (papaya), 190.51 to 287.68 µmol Trolox equivalents kg(-1) (strawberry)], with moderate effects on carotenoid concentration. This research demonstrates that decreases in nutrient value and antioxidant capacity can result from processing, but that regeneration of these losses can be seen corresponding to the apparent breakdown of pulp structure. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

[Characteristics of particle size structure of plankton community in turbidity zone of near-shore waters, Liaoning Province of Northeast China].

PubMed

Song, Lun; Wang, Nian-bin; Song, Yong-Gang; Li, Nan

2013-04-01

Estuary and nearshore waters have complicated environment, where plankton community has a frequent feedback regulation and a very unstable particle size structure. In this paper, an investigation was made on the particle size structure of plankton in the turbidity zone of nearshore and port area waters in Liaoning Province of Northeast China. In the waters with high concentration inorganic nitrogen, phytoplankton biomass was mainly of small particle sizes, with the equivalent sphere diameter (ESD) being primarily 20-100 micro m, while in low nutrient waters, the phytoplankton biomass was mainly of larger size particles, with the ESD>100 micro m, indicating that the phytoplankton feedback regulation caused the phytoplankton community to be comprised of small sized organisms as part of the biological responses to high concentration suspended solids, which reduced the individual number of larger organisms such as Coscinodiscus. sp. and other species, and in turn, directly affected the fisheries resources, including a variety of fish and shrimp larvae fed on phytoplankton. A normalized biomass size spectrum with the characteristics of nearshore shallow aquatic oceanic ecosystems exhibiting eutrophication was constructed. The spectrum slope indicated that the plankton community biomass would gradually increase in size. The feasibility of using dinoflagellates and cladocerans as the bio-indicators for eutrophication was discussed.

Rhizospheric effects on the microbial community of e-waste-contaminated soils using phospholipid fatty acid and isoprenoid glycerol dialkyl glycerol tetraether analyses.

PubMed

Song, Mengke; Cheng, Zhineng; Luo, Chunling; Jiang, Longfei; Zhang, Dayi; Yin, Hua; Zhang, Gan

2018-04-01

We performed the study of rhizospheric effects on soil microbial community structure, including bacteria, fungi, actinomycete, and archaea, at an electronic waste (e-waste) recycling site by analyzing the phospholipid fatty acid (PLFA) and isoprenoid glycerol dialkyl glycerol tetraether (GDGT) contents. By comparing PLFA and isoprenoid GDGT profiles of rhizospheric and surrounding bulk soils of 11 crop species, we observed distinct microbial community structures. The total PLFA concentration was significantly higher in rhizospheric soils than in non-rhizospheric soils, whereas no obvious difference was found in the total isoprenoid GDGT concentrations. The microbial community structure was also different, with higher ratios of fungal-to-bacterial PLFAs (F/B) and lower relative abundance of Gram-positive bacteria in rhizospheric soils. The extent of rhizospheric effects varied among plant species, and Colocasia esculenta L. had the greatest positive effects on the total microbial biomass. Dissolved organic carbon and pH were the main environmental factors affecting the microbial community represented by PLFAs, while the archaeal community was influenced by copper and zinc in all soils. These results offer a comprehensive view of rhizospheric effects on microbes in heavy metal and persistent organic pollutant co-contaminated soil, and provide fundamental knowledge regarding microbial ecology in e-waste-contaminated soils.

Physical chemistry and evolution of salt tolerance in halobacteria

NASA Technical Reports Server (NTRS)

Lanyi, J. K.

1980-01-01

The cellular constituents of extremely halophilic bacteria not only tolerate high salt concentration, but in many cases require it for optical functioning. The characteristics affected by salt include enzyme activity, stability, allosteric regulation, conformation and subunit association. The salt effects are of two major kinds: electrostatic shielding of negative charges by cations at low salt concentration, and hydrophobic stabilization by salting-out type salts at high salt concentration. The composition of halobacterial proteins shows an excess of acidic amino acids and a deficiency of nonpolar amino acids, which accounts for these effects. Since the cohesive forces are weaker and the repulsing forces are stronger in these proteins, preventing aggregation in salt, these structures are no longer suited for functioning in the absence of high salt concentrations. Unlike these nonspecific effects, ribosomes in halobacteria show marked preference for potassium over sodium ions. To ensure the proper intracellular ionic composition, powerful ion transport systems have evolved in the halobacteria, resulting in the extrusion of sodium ions and their replacement by potassium. It is likely that such membrane transport system for ionic movements is a necessary requisite for salt tolerance.

Geographically Modified PageRank Algorithms: Identifying the Spatial Concentration of Human Movement in a Geospatial Network.

PubMed

Chin, Wei-Chien-Benny; Wen, Tzai-Hung

2015-01-01

A network approach, which simplifies geographic settings as a form of nodes and links, emphasizes the connectivity and relationships of spatial features. Topological networks of spatial features are used to explore geographical connectivity and structures. The PageRank algorithm, a network metric, is often used to help identify important locations where people or automobiles concentrate in the geographical literature. However, geographic considerations, including proximity and location attractiveness, are ignored in most network metrics. The objective of the present study is to propose two geographically modified PageRank algorithms-Distance-Decay PageRank (DDPR) and Geographical PageRank (GPR)-that incorporate geographic considerations into PageRank algorithms to identify the spatial concentration of human movement in a geospatial network. Our findings indicate that in both intercity and within-city settings the proposed algorithms more effectively capture the spatial locations where people reside than traditional commonly-used network metrics. In comparing location attractiveness and distance decay, we conclude that the concentration of human movement is largely determined by the distance decay. This implies that geographic proximity remains a key factor in human mobility.

A Novel Computational Method to Reduce Leaky Reaction in DNA Strand Displacement.

PubMed

Li, Xin; Wang, Xun; Song, Tao; Lu, Wei; Chen, Zhihua; Shi, Xiaolong

2015-01-01

DNA strand displacement technique is widely used in DNA programming, DNA biosensors, and gene analysis. In DNA strand displacement, leaky reactions can cause DNA signals decay and detecting DNA signals fails. The mostly used method to avoid leakage is cleaning up after upstream leaky reactions, and it remains a challenge to develop reliable DNA strand displacement technique with low leakage. In this work, we address the challenge by experimentally evaluating the basic factors, including reaction time, ratio of reactants, and ion concentration to the leakage in DNA strand displacement. Specifically, fluorescent probes and a hairpin structure reporting DNA strand are designed to detect the output of DNA strand displacement, and thus can evaluate the leakage of DNA strand displacement reactions with different reaction time, ratios of reactants, and ion concentrations. From the obtained data, mathematical models for evaluating leakage are achieved by curve derivation. As a result, it is obtained that long time incubation, high concentration of fuel strand, and inappropriate amount of ion concentration can weaken leaky reactions. This contributes to a method to set proper reaction conditions to reduce leakage in DNA strand displacement.

Design and research of focusable secondary microprism in concentrating photovoltaic module

NASA Astrophysics Data System (ADS)

Guo, Limin; Liu, Youqiang; Zhao, Guoming; Wang, Zhiyong

2017-09-01

Low tracking accuracy of tracker, wind induced vibration of structure and lens deformation by temperature lead to non-vertical incident irradiation to the Fresnel lens, which necessitates a secondary concentrator in actual engineering application of concentrating photovoltaic module. This paper adds a secondary focusable microprism between Fresnel lens and solar cells in order to improve optical efficiency. The 3D model of microprism is established by SOLIDWORDS and main parameters are optimized using ZEMAX. Results show that combination of Fresnel lens and focusable microprism achieves a higher energy when the secondary microprism upper spherical diameter is 18mm, the opposite side face included angle is 116°, and the side length of the bottom is 2.15mm. The highest energy of solar cell surface can reach 2.4998W, improving 33.2%, and the module height with the secondary microprism is 88mm, which reduces by 5.5mm without secondary microprism. Experimental results show that the optical efficiency of 400X concentrating module system is 88.67%, the acceptance angle is ±1.2°, the 400X module maximum output power is 144.7W.

Modeling Closed Equilibrium Systems of H2O-Dissolved CO2-Solid CaCO3.

PubMed

Tenno, Toomas; Uiga, Kalev; Mashirin, Alexsey; Zekker, Ivar; Rikmann, Ergo

2017-04-27

In many places in the world, including North Estonia, the bedrock is limestone, which consists mainly of CaCO 3 . Equilibrium processes in water involving dissolved CO 2 and solid CaCO 3 play a vital role in many biological and technological systems. The solubility of CaCO 3 in water is relatively low. Depending on the concentration of dissolved CO 2 , the solubility of CaCO 3 changes, which determines several important ground- and wastewater parameters, for example, Ca 2+ concentration and pH. The distribution of ions and molecules in the closed system solid H 2 O-dissolved CO 2 -solid CaCO 3 is described in terms of a structural scheme. Mathematical models were developed for the calculation of pH and concentrations of ions and molecules (Ca 2+ , CO 3 2- , HCO 3 - , H 2 CO 3 , CO 2 , H + , and OH - ) in the closed equilibrium system at different initial concentrations of CO 2 in the water phase using an iteration method. The developed models were then experimentally validated.

Models of GexSe1-x

NASA Astrophysics Data System (ADS)

Malouin, Marc-André.; Mousseau, Normand

2008-03-01

We present numerical models of chalcogenide glasses constructed using the effective two and three body interaction potential developed by Mauro and Varshneya [1] combined with the activation-relaxation technique (ART nouveau) [2]. Structures are prepared starting from a random distribution, avoiding biases and crystalline remnants. Structural properties are studied mainly via characteristic system measurements including partial and total radial distribution functions, bond angle distributions, mean coordinations and bonds population. Results are shown for GexSe1-x for various x concentrations and compared to both experimental measurements and ab initio simulation results. [1] J.C. Mauro and A.K. Varshneya, J. Am. Ceram. Soc., 89 [7] 2323-6 (2006). [2] R. Malek and N. Mousseau, Phys. Rev. E 62, 7723 (2000).

Theory of spiral structure.

NASA Technical Reports Server (NTRS)

Lin, C. C.

1971-01-01

The question whether the galactic spiral arms are material objects or wave patterns is discussed. A semiempirical approach is adopted in presenting the concept of density waves. The theory of density waves is considered, giving attention to a survey of theoretical developments by analytical methods, the implication of a spiral pattern of density waves, spirals with moderately small pitch angle, and the origin and permanence of galactic spirals. The theoretical aspects discussed are tested against more detailed observations in the Milky Way system. It is pointed out that the density wave concept introduced by Lindblad, including the material concentration of both gas and stars, is the essential basis for the spiral structure of disk-shaped galaxies.

Nano-cone resistive memory for ultralow power operation.

PubMed

Kim, Sungjun; Jung, Sunghun; Kim, Min-Hwi; Kim, Tae-Hyeon; Bang, Suhyun; Cho, Seongjae; Park, Byung-Gook

2017-03-24

SiN x -based nano-structure resistive memory is fabricated by fully silicon CMOS compatible process integration including particularly designed anisotropic etching for the construction of a nano-cone silicon bottom electrode (BE). Bipolar resistive switching characteristics have significantly reduced switching current and voltage and are demonstrated in a nano-cone BE structure, as compared with those in a flat BE one. We have verified by systematic device simulations that the main cause of reduction in the performance parameters is the high electric field being more effectively concentrated at the tip of the cone-shaped BE. The greatly improved nonlinearity of the nano-cone resistive memory cell will be beneficial in the ultra-high-density crossbar array.

Three-dimensional Distribution of Greenhouse Gas Concentrations over Megacities Observed by GOSAT

NASA Astrophysics Data System (ADS)

Kikuchi, N.; Kuze, A.; Kataoka, F.; Shiomi, K.; Hashimoto, M.; Suto, H.; Knuteson, R. O.; Iraci, L. T.; Yates, E. L.; Gore, W.; Tanaka, T.

2017-12-01

Since the launch in January 2009, TANSO-FTS onboard GOSAT continues to observe the global distribution of carbon dioxide (CO2) and methane (CH4) concentrations. The regular grid observation is the standard observation mode, because a reduction of the uncertainty in the surface fluxes of CO2 and CH4in a subcontinental scale is one of the prime objectives of GOSAT. To meet an increasing demand for monitoring the anthropogenic emission of the greenhouses gases from large cities, GOSAT has carried out extensive target mode observations over several megacities since 2016. Although the footprint of TANSO-FTS is relatively large, the flexible pointing mechanism enables us to cover a city and the surrounding area at the same time. Another advantage of GOSAT TANSO-FTS is that it measures both SWIR and TIR spectra at the same footprint. By adding TIR windows to the existing SWIR retrieval algorithm, we can get the degrees of freedom larger than 2 for CO2 concentrations. This means that we can retrieve not only the column averaged concentration of CO2 (XCO2), but also the two-layer structure of CO2 concentrations, independent of the a priori constraint. In this study, we present three-dimensional distributions of CO2 and CH4 retrieved from GOSAT observations over several megacities including New York City. Fig. 1 shows the seasonal variation of XCO2 over New York City in 2016 covered by 16 footprints of GOSAT observations. A three-dimensional representation of CO2 concentrations is shown in Fig. 2 observed on September 15, 2016. In this example, CO2 concentrations were lower in the lower atmosphere in most of GOSAT footprints, indicating that CO2 was depleted in the lower atmosphere as expected for the summer season. In the winter season, the CO2 concentrations were enhanced in the lower atmosphere as shown in Fig. 3. This example indicates that GOSAT can detect variations in both the column and the vertical structure of CO2 over megacities. Similar analyses are underway for other megacities and will be shown in the presentation.

Acquisition of High Field Nuclear Magnetic Resonance Spectrometers for Research in Molecular Structure, Function and Dynamics

DTIC Science & Technology

2010-09-01

starting materials at high concentration, such as plasmid DNA (3.6 µg/µL), pure lipofectamine, and pure cholesterol as received from the manufacturer, as...24), including analyzing the chemical composition of individual triglyceride -rich lipoproteins (25). A Raman spectrum appears when a small portion of...J. C., Keim, N. L., and Huser, T. (2005) Raman spectroscopic analysis of biochemical changes in individual triglyceride -rich lipoproteins in the pre

A simple 2D biofilm model yields a variety of morphological features.

PubMed

Hermanowicz, S W

2001-01-01

A two-dimensional biofilm model was developed based on the concept of cellular automata. Three simple, generic processes were included in the model: cell growth, internal and external mass transport and cell detachment (erosion). The model generated a diverse range of biofilm morphologies (from dense layers to open, mushroom-like forms) similar to those observed in real biofilm systems. Bulk nutrient concentration and external mass transfer resistance had a large influence on the biofilm structure.

Pyroelectric A1GaN/GaN HEMTs for ion-, gas- and Polar-Liquid Sensors

DTIC Science & Technology

2004-08-17

including the manipulation of pico- and nanofluid volumes on chemical or structural modified surfaces and defining suitable interfaces to the macroworld. A... nanofluidic dispensers based on piezo actuators, the micro periphery and the electronics for measuring biochemical assay systems (in vivo and in vitro...interface without the need of a modulation doped barrier. The carrier concentration and electron mobility within the 2DEG can be very high and build

Chemical study of the fungus Psilocybe merdaria.

PubMed

Yang, Ning-Ning; Ma, Qing-Yun; Huang, Sheng-Zhuo; Kong, Fan-Dong; Dai, Hao-Fu; Yu, Zhi-Fang; Zhao, You-Xing

2017-04-01

Chemical investigation on the cultures of the fungus Psilocybe merdaria resulted in the first isolation of 10 compounds including two new ones 11,14-dihydroxylneoechinulin E (1) and (S)-4-(4-methylpent-3-en-1-yl)-butyrolactone (2). Their structures were elucidated from the analysis of 1D and 2D NMR and MS data. Among them, compound 7 showed inhibitory activity against AChE with 20% percentage at a concentration of 50 μg/ml.

Methods for boron delivery to mammalian tissue

DOEpatents

Hawthorne, M. Frederick; Feaks, Debra A.; Shelly, Kenneth J.

2003-01-01

Boron neutron capture therapy can be used to destroy tumors. This treatment modality is enhanced by delivering compounds to the tumor site where the compounds have high concentrations of boron, the boron compounds being encapsulated in the bilayer of a liposome or in the bilayer as well as the internal space of the liposomes. Preferred compounds, include carborane units with multiple boron atoms within the carborane cage structure. Liposomes with increased tumor specificity may also be used.

Natural abundance 17O, 6Li NMR and molecular modeling studies of the solvation structures of lithium bis(fluorosulfonyl)imide/1,2-dimethoxyethane liquid electrolytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wan, Chuan; Hu, Mary Y.; Borodin, Oleg

2016-03-01

Natural abundance 17O and 6Li NMR experiments, quantum chemistry and molecular dynamics studies were employed to investigate the solvation structures of Li+ at various concentrations of LiFSI in DME electrolytes in an effort to solve this puzzle. It was found that the chemical shifts of both 17O and 6Li changed with the concentration of LiFSI, indicating the changes of solvation structures with concentration. For the quantum chemistry calculations, the coordinated cluster LiFSI(DME)2 forms at first, and its relative ratio increases with increasing LiFSI concentration to 1 M. Then the solvation structure LiFSI(DME) become the dominant component. As a result, themore » coordination of forming contact ion pairs between Li+ and FSI- ion increases, but the association between Li+ and DME molecule decreases. Furthermore, at LiFSI concentration of 4 M the solvation structures associated with Li+(FSI-)2(DME), Li+2(FSI-)(DME)4 and (LiFSI)2(DME)3 become the dominant components. For the molecular dynamics simulation, with increasing concentration, the association between DME and Li+ decreases, and the coordinated number of FSI- increases, which is in perfect accord with the DFT results. These results provide more insight on the fundamental mechanism on the very high CE of Li deposition in these electrolytes, especially at high current density conditions.« less

Modal Survey Test of the SOTV 2X3 Meter Off-Axis Inflatable Concentrator

NASA Technical Reports Server (NTRS)

Engberg, Robert C.; Lassiter, John O.; McGee, Jennie K.

2000-01-01

NASA's Marshall Space Flight Center has had several projects involving inflatable space structures. Projects in solar thermal propulsion have had the most involvement, primarily inflatable concentrators. A flight project called Shooting Star Experiment initiated the first detailed design, analysis and testing effort involving an inflatable concentrator that supported a Fresnel lens. The lens was to concentrate the sun's rays to provide an extremely large heat transfer for an experimental solar propulsion engine. Since the conclusion of this experiment, research and development activities for solar propulsion at Marshall Space Flight Center have continued both in the solar propulsion engine technology as well as inflatable space structures. Experience gained in conducting modal survey tests of inflatable structures for the Shooting Star Experiment has been used by dynamic test engineers at Marshall Space Flight Center to conduct a modal survey test on a Solar Orbital Transfer Vehicle (SOTV) off-axis inflatable concentrator. This paper describes how both previously learned test methods and new test methods that address the unique test requirements for inflatable structures were used. Effects of the inherent nonlinear response of the inflatable concentrator on test methods and test results are noted as well. Nine analytical mode shapes were successfully correlated to test mode shapes. The paper concludes with several "lessons learned" applicable to future dynamics testing and shows how Marshall Space Flight Center has utilized traditional and new methods for modal survey testing of inflatable space structures.

On correction of model of stabilization of distribution of concentration of radiation defects in a multilayer structure with account experiment data

NASA Astrophysics Data System (ADS)

Pankratov, E. L.

2018-05-01

We introduce a model of redistribution of point radiation defects, their interaction between themselves and redistribution of their simplest complexes (divacancies and diinterstitials) in a multilayer structure. The model gives a possibility to describe qualitatively nonmonotonicity of distributions of concentrations of radiation defects on interfaces between layers of the multilayer structure. The nonmonotonicity was recently found experimentally. To take into account the nonmonotonicity we modify recently used in literature model for analysis of distribution of concentration of radiation defects. To analyze the model we used an approach of solution of boundary problems, which could be used without crosslinking of solutions on interfaces between layers of the considered multilayer structures.

Lyotropic Phase Behavior of Polybutadiene-Poly(ethylene oxide) Diblock Copolymers in Ionic Liquids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simone, Peter M.; Lodge, Timothy P.

2008-08-26

The lyotropic phase behavior of three poly(1,2-butadiene-b-ethylene oxide) diblock copolymers (PB-PEO) with different monomer volume fractions has been studied in two different ionic liquids, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMI][TFSI]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMI][PF{sub 6}]), across the complete concentration range. The ordered microstructures present in the solutions were characterized via small-angle X-ray scattering (SAXS). The phase diagrams for the PB-PEO/ionic liquid solutions include regions corresponding to the classical copolymer microstructures: body-centered-cubic lattices of spheres, hexagonally ordered cylinders, and lamellae. Additionally, the phase diagrams also include wide regions of coexisting microstructures and regions apparently corresponding to a disordered network microstructure. The phase behavior ofmore » the PB-PEO copolymers in both ionic liquids was comparable to their previously reported aqueous solution behavior. The temperature dependence of the phase diagrams was very modest, indicative of a highly segregated system. The level of solvent selectivity was also investigated via cryogenic transmission electron microscopy (cryo-TEM) on dilute solutions. On the basis of the morphology of the dilute solution copolymer aggregate structures in the ionic liquid solvents, and on the structural length scales of the concentrated solutions, it was concluded that for PB-PEO [BMI][PF{sub 6}] behaves as a more selective solvent than [EMI][TFSI].« less

A Blood-Brain Barrier (BBB) Disrupter Is Also a Potent α-Synuclein (α-syn) Aggregation Inhibitor

PubMed Central

Shaltiel-Karyo, Ronit; Frenkel-Pinter, Moran; Rockenstein, Edward; Patrick, Christina; Levy-Sakin, Michal; Schiller, Abigail; Egoz-Matia, Nirit; Masliah, Eliezer; Segal, Daniel; Gazit, Ehud

2013-01-01

The development of disease-modifying therapy for Parkinson disease has been a main drug development challenge, including the need to deliver the therapeutic agents to the brain. Here, we examined the ability of mannitol to interfere with the aggregation process of α-synuclein in vitro and in vivo in addition to its blood-brain barrier-disrupting properties. Using in vitro studies, we demonstrated the effect of mannitol on α-synuclein aggregation. Although low concentration of mannitol inhibited the formation of fibrils, high concentration significantly decreased the formation of tetramers and high molecular weight oligomers and shifted the secondary structure of α-synuclein from α-helical to a different structure, suggesting alternative potential pathways for aggregation. When administered to a Parkinson Drosophila model, mannitol dramatically corrected its behavioral defects and reduced the amount of α-synuclein aggregates in the brains of treated flies. In the mThy1-human α-synuclein transgenic mouse model, a decrease in α-synuclein accumulation was detected in several brain regions following treatment, suggesting that mannitol promotes α-synuclein clearance in the cell bodies. It appears that mannitol has a general neuroprotective effect in the transgenic treated mice, which includes the dopaminergic system. We therefore suggest mannitol as a basis for a dual mechanism therapeutic agent for the treatment of Parkinson disease. PMID:23637226

A blood-brain barrier (BBB) disrupter is also a potent α-synuclein (α-syn) aggregation inhibitor: a novel dual mechanism of mannitol for the treatment of Parkinson disease (PD).

PubMed

Shaltiel-Karyo, Ronit; Frenkel-Pinter, Moran; Rockenstein, Edward; Patrick, Christina; Levy-Sakin, Michal; Schiller, Abigail; Egoz-Matia, Nirit; Masliah, Eliezer; Segal, Daniel; Gazit, Ehud

2013-06-14

The development of disease-modifying therapy for Parkinson disease has been a main drug development challenge, including the need to deliver the therapeutic agents to the brain. Here, we examined the ability of mannitol to interfere with the aggregation process of α-synuclein in vitro and in vivo in addition to its blood-brain barrier-disrupting properties. Using in vitro studies, we demonstrated the effect of mannitol on α-synuclein aggregation. Although low concentration of mannitol inhibited the formation of fibrils, high concentration significantly decreased the formation of tetramers and high molecular weight oligomers and shifted the secondary structure of α-synuclein from α-helical to a different structure, suggesting alternative potential pathways for aggregation. When administered to a Parkinson Drosophila model, mannitol dramatically corrected its behavioral defects and reduced the amount of α-synuclein aggregates in the brains of treated flies. In the mThy1-human α-synuclein transgenic mouse model, a decrease in α-synuclein accumulation was detected in several brain regions following treatment, suggesting that mannitol promotes α-synuclein clearance in the cell bodies. It appears that mannitol has a general neuroprotective effect in the transgenic treated mice, which includes the dopaminergic system. We therefore suggest mannitol as a basis for a dual mechanism therapeutic agent for the treatment of Parkinson disease.

Effect of Mo and Ti doping concentration on the structural and optical properties of ZnS nanoparticles

NASA Astrophysics Data System (ADS)

Naz, Hina; Ali, Rai Nauman; Zhu, Xingqun; Xiang, Bin

2018-06-01

In this paper, we report the effect of single phase Mo and Ti doping concentration on the structural and optical properties of the ZnS nanoparticles. The structural and optical properties of the as-synthesized samples have been examined by x-ray diffraction, transmission electron microscopy (TEM), UV-visible near infrared absorption spectroscopy and x-ray photoelectron spectroscopy. TEM characterizations reveal a variation in the doped ZnS nanoparticle size distribution by utilizing different dopants of Mo and Ti. In absorption spectra, a clear red shift of 14 nm is observed with increasing Mo concentration as compared to pure ZnS nanoparticles, while by increasing Ti doping concentration, blue shift of 14 nm is obtained. Moreover, it demonstrates that the value of energy band gap decreases from 4.03 eV to 3.89 eV in case of Mo doping. However, the value of energy band gap have shown a remarkable increase from 4.11 eV to 4.27 eV with increasing Ti doping concentration. Our results provide a new pathway to understand the effect of Mo and Ti doping concentrations on the structural and optical properties of ZnS nanoparticles as it could be the key to tune the properties for future optoelectronic devices.

The deep chlorophyll layer in Lake Ontario: Extent, mechanisms of formation, and abiotic predictors

USGS Publications Warehouse

Scofield, Anne E.; Watkins, James M.; Weidel, Brian C.; Luckey, Frederick J.; Rudstam, Lars G.

2017-01-01

Epilimnetic production has declined in Lake Ontario, but increased production in metalimnetic deep chlorophyll layers (DCLs) may compensate for these losses. We investigated the spatial and temporal extent of DCLs, the mechanisms driving DCL formation, and the use of physical variables for predicting the depth and concentration of the deep chlorophyll maximum (DCM) during April–September 2013. A DCL with DCM concentrations 2 to 3 times greater than those in the epilimnion was present when the euphotic depth extended below the epilimnion, which occurred primarily from late June through mid-August. In situ growth was important for DCL formation in June and July, but settling and photoadaptation likely also contributed to the later-season DCL. Supporting evidence includes: phytoplankton biovolume was 2.4 × greater in the DCL than in the epilimnion during July, the DCL phytoplankton community of July was different from that of May and the July epilimnion (p = 0.004), and there were concurrences of DCM with maxima in fine particle concentration and dissolved oxygen saturation. Higher nutrient levels in the metalimnion may also be a necessary condition for DCL formation because July metalimnetic concentrations were 1.5 × (nitrate) and 3.5 × (silica) greater than in the epilimnion. Thermal structure variables including epilimnion depth, thermocline depth, and thermocline steepness were useful for predicting DCM depth; the inclusion of euphotic depth only marginally improved these predictions. However, euphotic depth was critical for predicting DCM concentrations. The DCL is a productive and predictable feature of the Lake Ontario ecosystem during the stratified period.

The influence of spreading rate, basement composition, fluid chemistry and chimney morphology on the formation of gold-rich SMS deposits at slow and ultraslow mid-ocean ridges

NASA Astrophysics Data System (ADS)

Knight, Robert D.; Roberts, Stephen; Webber, Alexander P.

2018-01-01

Seafloor massive sulphide (SMS) deposits are variably enriched in precious metals including gold. However, the processes invoked to explain the formation of auriferous deposits do not typically apply to mid-ocean ridge settings. Here, we show a statistically significant, negative correlation between the average gold concentration of SMS deposits with spreading rate, at non-sedimented mid-ocean ridges. Deposits located at slow spreading ridges (20-40 mm/a) have average gold concentrations of between 850 and 1600 ppb; however, with increasing spreading rate (up to 140 mm/a), gold concentrations gradually decrease to between 50 and 150 ppb. This correlation of gold content with spreading rate may be controlled by the degree and duration of fluid-rock interaction, which is a function of the heat flux, crustal structure (faulting) and the permeability of the source rocks. Deposits at ultraslow ridges, including ultramafic-hosted deposits, are particularly enriched in gold. This is attributed to the higher permeability of the ultramafic source rocks achieved by serpentinisation and the inherent porosity of serpentine minerals, combined with relatively high gold concentrations in peridotite compared with mid-ocean ridge basalt. Variations in fluid chemistry, such as reducing conditions and the potential for increased sulphur availability at ultramafic-hosted sites, may also contribute to the high concentrations observed. Beehive chimneys, which offer more favourable conditions for gold precipitation, may be more prevalent at ultramafic-hosted sites due to diffuse low-velocity venting compared with more focussed venting at basalt-hosted sites.

Lorentz force in water: evidence that hydronium cyclotron resonance enhances polymorphism.

PubMed

D'Emilia, E; Giuliani, L; Lisi, A; Ledda, M; Grimaldi, S; Montagnier, L; Liboff, A R

2015-01-01

There is an ongoing question regarding the structure forming capabilities of water at ambient temperatures. To probe for different structures, we studied effects in pure water following magnetic field exposures corresponding to the ion cyclotron resonance of H3O(+). Included were measurements of conductivity and pH. We find that under ion cyclotron resonance (ICR) stimulation, water undergoes a transition to a form that is hydroxonium-like, with the subsequent emission of a transient 48.5 Hz magnetic signal, in the absence of any other measurable field. Our results indicate that hydronium resonance stimulation alters the structure of water, enhancing the concentration of EZ-water. These results are not only consistent with Del Giudice's model of electromagnetically coherent domains, but they can also be interpreted to show that these domains exist in quantized spin states.

Deciphering the kinetic structure of multi-ion plasma shocks

DOE PAGES

Keenan, Brett D.; Simakov, Andrei N.; Chacón, Luis; ...

2017-11-15

Here, strong collisional shocks in multi-ion plasmas are featured in many high-energy-density environments, including inertial confinement fusion implosions. However, their basic structure and its dependence on key parameters (e.g., the Mach number and the plasma ion composition) are poorly understood, and inconsistencies in that regard remain in the literature. In particular, the shock width's dependence on the Mach number has been hotly debated for decades. Using a high-fidelity Vlasov-Fokker-Planck code, iFP, and direct comparisons to multi-ion hydrodynamic simulations and semianalytic predictions, we resolve the structure of steady-state planar shocks in D- 3He plasmas. Additionally, we derive and confirm with kineticmore » simulations a quantitative description of the dependence of the shock width on the Mach number and initial ion concentration.« less

Deciphering the kinetic structure of multi-ion plasma shocks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keenan, Brett D.; Simakov, Andrei N.; Chacón, Luis

Here, strong collisional shocks in multi-ion plasmas are featured in many high-energy-density environments, including inertial confinement fusion implosions. However, their basic structure and its dependence on key parameters (e.g., the Mach number and the plasma ion composition) are poorly understood, and inconsistencies in that regard remain in the literature. In particular, the shock width's dependence on the Mach number has been hotly debated for decades. Using a high-fidelity Vlasov-Fokker-Planck code, iFP, and direct comparisons to multi-ion hydrodynamic simulations and semianalytic predictions, we resolve the structure of steady-state planar shocks in D- 3He plasmas. Additionally, we derive and confirm with kineticmore » simulations a quantitative description of the dependence of the shock width on the Mach number and initial ion concentration.« less

Dielectric barrier structure with hollow electrodes and its recoil effect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Shuang; Chen, Qunzhi; Liu, Jiahui

2015-06-15

A dielectric barrier structure with hollow electrodes (HEDBS), in which gas flow oriented parallel to the electric field, was proposed. Results showed that with this structure, air can be effectively ignited, forming atmospheric low temperature plasma, and the proposed HEDBS could achieve much higher electron density (5 × 10{sup 15}/cm{sup 3}). It was also found that the flow condition, including outlet diameter and flow rate, played a key role in the evolution of electron density. Optical emission spectroscopy diagnostic results showed that the concentration of reactive species had the same variation trend as the electron density. The simulated distribution of discharge gasmore » flow indicated that the HEDBS had a strong recoil effect on discharge gas, and could efficiently promote generating electron density as well as reactive species.« less

Local and average structure of Mn- and La-substituted BiFeO3

NASA Astrophysics Data System (ADS)

Jiang, Bo; Selbach, Sverre M.

2017-06-01

The local and average structure of solid solutions of the multiferroic perovskite BiFeO3 is investigated by synchrotron X-ray diffraction (XRD) and electron density functional theory (DFT) calculations. The average experimental structure is determined by Rietveld refinement and the local structure by total scattering data analyzed in real space with the pair distribution function (PDF) method. With equal concentrations of La on the Bi site or Mn on the Fe site, La causes larger structural distortions than Mn. Structural models based on DFT relaxed geometry give an improved fit to experimental PDFs compared to models constrained by the space group symmetry. Berry phase calculations predict a higher ferroelectric polarization than the experimental literature values, reflecting that structural disorder is not captured in either average structure space group models or DFT calculations with artificial long range order imposed by periodic boundary conditions. Only by including point defects in a supercell, here Bi vacancies, can DFT calculations reproduce the literature results on the structure and ferroelectric polarization of Mn-substituted BiFeO3. The combination of local and average structure sensitive experimental methods with DFT calculations is useful for illuminating the structure-property-composition relationships in complex functional oxides with local structural distortions.

Local and average structure of Mn- and La-substituted BiFeO 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Bo; Selbach, Sverre M.

2017-06-01

The local and average structure of solid solutions of the multiferroic perovskite BiFeO 3 is investigated by synchrotron X-ray diffraction (XRD) and electron density functional theory (DFT) calculations. The average experimental structure is determined by Rietveld refinement and the local structure by total scattering data analyzed in real space with the pair distribution function (PDF) method. With equal concentrations of La on the Bi site or Mn on the Fe site, La causes larger structural distortions than Mn. Structural models based on DFT relaxed geometry give an improved fit to experimental PDFs compared to models constrained by the space groupmore » symmetry. Berry phase calculations predict a higher ferroelectric polarization than the experimental literature values, reflecting that structural disorder is not captured in either average structure space group models or DFT calculations with artificial long range order imposed by periodic boundary conditions. Only by including point defects in a supercell, here Bi vacancies, can DFT calculations reproduce the literature results on the structure and ferroelectric polarization of Mn-substituted BiFeO 3. The combination of local and average structure sensitive experimental methods with DFT calculations is useful for illuminating the structure-property-composition relationships in complex functional oxides with local structural distortions.« less

Chapter A. Effects of urbanization on stream ecosystems in the South Platte River basin, Colorado and Wyoming

USGS Publications Warehouse

Sprague, Lori A.; Zuellig, Robert E.; Dupree, Jean A.

2006-01-01

This report describes the effects of urbanization on physical, chemical, and biological characteristics of stream ecosystems in 28 basins along an urban land-use gradient in the South Platte River Basin, Colorado and Wyoming, from 2002 through 2003. Study basins were chosen to minimize natural variability among basins due to factors such as geology, elevation, and climate and to maximize coverage of different stages of urban development among basins. Because land use or population density alone often are not a complete measure of urbanization, land use, land cover, infrastructure, and socioeconomic variables were integrated in a multimetric urban intensity index to represent the degree of urban development in each study basin. Physical characteristics studied included stream hydrology, stream temperature, and habitat; chemical characteristics studied included nutrients, pesticides, suspended sediment, sulfate, chloride, and fecal bacteria concentrations; and biological characteristics studied included algae, fish, and invertebrate communities. Semipermeable membrane devices (SPMDs), passive samplers that concentrate trace levels of hydrophobic organic contaminants like polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), also were used. The objectives of the study were to (1) examine physical, chemical, and biological responses along the gradient of urbanization; (2) determine the major physical, chemical, and landscape variables affecting the structure of aquatic communities; and (3) evaluate the relevance of the results to the management of water resources in the South Platte River Basin. Commonly observed effects of urbanization on instream physical, chemical, and biological characteristics, such as increased flashiness, higher magnitude and more frequent peak flows, increased concentrations of chemicals, and changes in aquatic community structure, generally were not observed in this study. None of the hydrologic, temperature, habitat, or chemical variables were correlated strongly (Spearman's rho greater than or equal to 0.7) with urban intensity, with the exception of some of the SPMD-based toxicity and chemical variables. SPMD-based measures of potential toxicity and PAH concentrations were positively correlated with urban intensity. The PAH concentrations also were positively correlated with measures of road density and negatively correlated with distance to the nearest road, indicating that automobile exhaust is a major source of these compounds in the study area. This source may be localized enough that the transport of PAHs would be minimally affected by water-management practices such as diversion or storage upstream. In contrast, the predominant sources of nutrients, bacteria, suspended sediment, sulfate, chloride, and pesticides may be more dispersed throughout the drainage area and, therefore, their transport to downstream sites may be subject to greater disruption by water regulation. Although no direct link was found between most water-chemistry characteristics and urbanization, invertebrate, algae, and fish-community characteristics were strongly associated with nutrients, pesticides, sulfate, chloride, and suspended sediment. None of the biological community variables were strongly correlated with the urban intensity index. Algal biomass predominantly was associated with total nitrogen concentrations, nitrite-plus-nitrate concentrations, and the duration of high flows. Fish communities predominantly were associated with housing age, the percentage of suspended sediment finer than 0.063 millimeters and chloride concentrations. Invertebrate communities predominantly were associated with the frequency of rising and falling flow events, the duration of high flows, total nitrogen concentrations, nitrite-plus-nitrate concentrations, and total herbicide concentrations. Historical records indicate that aquatic communities in the region may have been altered prior to any substantial urban development by early agricultural and water-management practices. Present-day aquatic communities are composed primarily of tolerant species even in areas of minimal urban development; when development does occur, the communities already may be resistant to disturbance. In addition to the effects of historical stressors on aquatic community structure, it is possible that current water-management practices in the study basins are having an effect. In the absence of natural, unaltered hydrologic conditions, more sensitive taxa may be unable to recolonize urban streams. The movement and storage of water also may lead to a disconnect between the land surface and streams, resulting in instream physical, chemical, and biological characteristics that, to some degree, are independent of land-cover characteristics.

Evaluation of Antioxidant Activity and Growth Control Properties of Nonoscale Structure Produced from Aloe vera var. littoralis Extract on Clinical Isolates of Salmonella

PubMed Central

Hosseiny, Hossein

2017-01-01

The aim of the study was to examine antibacterial properties of microemulsion structure produced from Aloe vera var. littoralis extract as a new tool of nanoscale drug-like materials. Aloe vera var. littoralis (A. littoralis) extract was prepared by distillation method. A nonocarrier structure in the microemulsion system was prepared from the extract. Serial concentrations were prepared from 8 mg/mL extract and the nonocarrier containing 0.1 mg/mL pure extract and were evaluated by a disk diffusion method for 35 Salmonella clinical isolates. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by microbroth dilution assay using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method by an enzyme-linked immunosorbent assay(ELISA) Microplate Reader apparatus. Antioxidant activity of the extract was determined by measuring the ferric reducing ability of plasma (FRAP) assay. From 35 clinical isolates of Salmonella, 17 isolates—including resistant isolates of S.E.1103 and S.E.49—had a zone of inhibition (ZI) of 7 to 32 mm in 0.007 mg/mL of the extract. S.E.76 isolate exposed to 30 µg/mL ceftazidime disk had a ZI of 12 mm but had 10 mm in 7µg/mL of A. littoralis extract. The inhibitory effect of a nanocarrier at a concentration of 25 µg/mL by 20 mm ZI was comparable by the ceftazidime (30 µg/mL) effect. MIC50 was 0.25 mg/mL and MBC50 was 0.5 mg/mL by MTT method for the extract. It was shown that A.littoralis extract had antioxidant activity of 31.67 µM/mg that could be increased based on concentration. It was concluded that the nanocarrier had a significant effect on the studied isolates in comparison with ordinary antibiotics and had potential for use as a natural antioxidant and antimicrobial material in complementary medicine. PMID:28758958

Structural and functional evidences for the interactions between nuclear hormone receptors and endocrine disruptors at low doses.

PubMed

Balaguer, Patrick; Delfosse, Vanessa; Grimaldi, Marina; Bourguet, William

Endocrine-disrupting chemicals (EDCs) represent a broad class of exogenous substances that cause adverse effects in the endocrine system mainly by interacting with nuclear hormone receptors (NRs). Humans are generally exposed to low doses of pollutants, and current researches aim at deciphering the mechanisms accounting for the health impact of EDCs at environmental concentrations. Our correlative analysis of structural, interaction and cell-based data has revealed a variety of, sometimes unexpected, binding modes, reflecting a wide range of EDC affinities and specificities. Here, we present a few representative examples to illustrate various means by which EDCs achieve high-affinity binding to NRs. These examples include the binding of the mycoestrogen α-zearalanol to estrogen receptors, the covalent interaction of organotins with the retinoid X- and peroxisome proliferator-activated receptors, and the cooperative binding of two chemicals to the pregnane X receptor. We also discuss some hypotheses that could further explain low-concentration effects of EDCs with weaker affinity towards NRs. Copyright © 2017. Published by Elsevier Masson SAS.

Speckle imaging of active galactic nuclei: NGC 1068 and NGC 4151

NASA Astrophysics Data System (ADS)

Ebstein, Steven Michael

High resolution images of NGC 1068 and NGC 4151 in the 5007 A line and the nearby continuum produced from data taken with the PAPA photon counting imaging detector using the technique of speckle imaging are presented. The images show an unresolved core of 5007 A emission in the middle of an extended emission region. The extended emission tends to lie alongside the subarcsecond radio structure. In NGC 4151, the extended emission comes from a nearly linear structure extending on both sides of the unresolved core. In NGC 1068, the extended emission is concentrated in lobes lying to the unresolved core but the emission is concentrated in lobes lying to either side of the major axis. The continuum of NGC 4151 is spatially unresolved. The continuum of NGC 1068 is extended approx. 1 in to the SW of the center of the 5007 A emission. Certain aspects of the PAPA detector are discussed, including the variable threshold discriminators that track the image intensifier pulse height and the camera artifacts. The data processing is described in detail.

Nanoscale Electrostructural Characterization of Compositionally Graded Al(x)Ga(1-x)N Heterostructures on GaN/Sapphire (0001) Substrate.

PubMed

Kuchuk, Andrian V; Lytvyn, Petro M; Li, Chen; Stanchu, Hryhorii V; Mazur, Yuriy I; Ware, Morgan E; Benamara, Mourad; Ratajczak, Renata; Dorogan, Vitaliy; Kladko, Vasyl P; Belyaev, Alexander E; Salamo, Gregory G

2015-10-21

We report on AlxGa1-xN heterostructures resulting from the coherent growth of a positive then a negative gradient of the Al concentration on a [0001]-oriented GaN substrate. These polarization-doped p-n junction structures were characterized at the nanoscale by a combination of averaging as well as depth-resolved experimental techniques including: cross-sectional transmission electron microscopy, high-resolution X-ray diffraction, Rutherford backscattering spectrometry, and scanning probe microscopy. We observed that a small miscut in the substrate orientation along with the accumulated strain during growth led to a change in the mosaic structure of the AlxGa1-xN film, resulting in the formation of macrosteps on the surface. Moreover, we found a lateral modulation of charge carriers on the surface which were directly correlated with these steps. Finally, using nanoscale probes of the charge density in cross sections of the samples, we have directly measured, semiquantitatively, both n- and p-type polarization doping resulting from the gradient concentration of the AlxGa1-xN layers.

Topotactic Metal-Insulator Transition in Epitaxial SrFeO x Thin Films

DOE PAGES

Khare, Amit; Shin, Dongwon; Yoo, Tae Sup; ...

2017-07-31

Multivalent transition metal oxides provide fascinating and rich physics related to oxygen stoichiometry. In particular, the adoptability of various valence states of transition metals enables perovskite oxides to display mixed (oxygen) ionic and electronic conduction and catalytic activity useful in many practical applications, including solid-oxide fuel cells (SOFCs), rechargeable batteries, gas sensors, and memristive devices. For proper realization of the ionic conduction and catalytic activity, it is essential to understand the reversible oxidation and reduction process, which is governed by oxygen storage/release steps in oxides. Topotactic phase transformation facilitates the redox process in perovskites with specific oxygen vacancy ordering bymore » largely varying the oxygen concentration of a material without losing the lattice framework. The concentration and diffusion of oxide ions (O 2–), the valence state of the transition metal cations, and the thermodynamic structural integrity together provide fundamental understanding and ways to explicitly control the redox reaction.[6] In addition, it offers an attractive route for tuning the emergent physical properties of transition metal oxides, via strong coupling between the crystal lattice and electronic structure.« less

Inhibition of Cancer-Associated Mutant Isocitrate Dehydrogenases by 2-thiohydantoin compounds

PubMed Central

Kogiso, Mari; Yao, Yuan; Zhou, Chao; Li, Xiao-Nan; Song, Yongcheng

2015-01-01

Somatic mutations of isocitrate dehydrogenase 1 (IDH1) at R132 are frequently found in certain cancers such as glioma. With losing the activity of wild-type IDH1, the R132H and R132C mutant proteins can reduce α-ketoglutaric acid (α-KG) to D-2-hydroxyglutaric acid (D2HG). The resulting high concentration of D2HG inhibits many α-KG-dependent dioxygenases, including histone demethylases, to cause broad histone hypermethylation. These aberrant epigenetic changes are responsible for initiation of these cancers. We report the synthesis, structure activity relationships, enzyme kinetics and binding thermodynamics of a novel series of 2-thiohydantoin and related compounds, among which several compounds are potent inhibitors of mutant IDH1 with Ki as low as 420 nM. X-ray crystal structures of IDH1(R132H) in complex with two inhibitors are reported, showing their inhibitor-protein interactions. These compounds can decrease the cellular concentration of D2HG, reduce the levels of histone methylation, and suppress proliferation of stem-like cancer cells in BT142 glioma with IDH1 R132H mutation. PMID:26280302

Crash energy management on the base of Movable cellular automata method

NASA Astrophysics Data System (ADS)

Psakhie, Serguei; Dmitriev, Andrei; Shilko, Evgueni; Tatarintsev, Evgueni; Korostelev, Serguei

2001-06-01

One of the main problems of materials science is increasing of structure's viability under dynamic loading. In general, a solution is the management of transformation of the energy of loading to the energy of destroying of the least important parts and details of the structure. It has to be noted that similar problem also exists in materials science, since a majority of modern materials are heterogeneous and have a complex internal structure. To optimize this structure for working under dynamic loading it is necessary to take into account the redistribution of elastic energy including phase transformation, generation and accumulation of micro-damages, etc. As far as real experiments on destroying the complex objects are sufficiently expensive and getting of detailed information is often associates with essential difficulties, the methods of computer modeling are used in solving the similar problems. As a rule, these are the methods of continuum mechanics. Although essential achievements have been obtained on the basis of these methods the continuum approach has several limitations, connected first of all with the possibility of description of generation of damages, formation and development of cracks and mass mixing effects. These problems may be solved on the basis of the Movable Cellular Automata (MCA) method, which has been successfully used for modeling fracture of the different material and structures In the paper behavior and peculiarities of failure of complex structures and materials under dynamic loading are studied on the basis of computer modeling. The results shown that sometimes even small changes of the internal structure leads to the significant increasing of the viability of the complex structures and materials. It is due to the elastic energy flux change over during the dynamical loading. This effect may be explained by the fact that elastic energy fluxes define the current stress concentration. Namely, because the area of inclusions are subjected by the largest displacement and due to less Young modulus of inclusions the loading pulses are transferred towards the other parts of the sample. This leads to "blurring" of the stress concentrators and conservation of wholeness of the structure. In its turn, this leads to essential raising up of threshold value of "injected" energy, i.e. the energy absorbed by the structure before loss of its carrying capacity. Practically, elastic energy "circulates" in the structure until a stress concentrator appears, which power will be sufficient for forming a macro-cracks. The results demonstrate a possibility of managing the fracture process under dynamic loading and raising viability of structures and heterogeneous materials by changing their internal structure, geometry, so by entering the specific inclusions.

Structure and free energy of cholesteric DNA droplets

NASA Astrophysics Data System (ADS)

Strey, Helmut; Hong, Helen; Easwar, Nalini

2000-03-01

Liquid crystals of DNA are the simplest model systems for DNA packing in cell nuclei or in phage heads. With increasing concentration DNA solutions exhibit the following phases: hexagonal, line hexatic, cholesteric, blue phases. We will present measurements of defect structure and pitch of cholesteric spherulites of short fragment DNA (146 base pairs). DNA concentration as well as salt concentrations are controlled by bathing the spherulites in poly (ethylene glycol) (MW 35,000u) solutions of known osmotic pressure. Combining polarizing microscopy and x-ray scattering with the osmotic stress method allows us to monitor the cholesteric structure and pitch as a function of interaxial distance between DNA molecules as well as salt concentration and type. In particular, we present data on how the DNA cholesteric pitch unwinds when the line hexatic phase is approached.

Revealing driving factors of China's PM2.5 pollution

NASA Astrophysics Data System (ADS)

Zheng, Y.; Zhao, H.; Zhang, Q.; Geng, G.; Tong, D.; Peng, L.; He, K.

2017-12-01

China's rapid economic development and intensive energy consumption are deteriorating the air quality significantly. Understanding the key driving factors behind China's growing emissions of air pollutants and the accompanying PM2.5 pollution is critical for the development of China's clean air policies and also provides insight into how other emerging economies may develop a clear sky future. Here we reveal the socioeconomic drivers of the variations of China's PM2.5 concentrations during 2002-2012 by using an interdisciplinary framework that integrates an emission inventory model, an index decomposition analysis model, and a regional air quality model. The decomposition results demostrate that the improvements in emission efficiency and energy efficiency failed to offset the increased emissions of both primary PM2.5 and gaseous PM2.5 precursors (including SO2 NOx, and volatile organic compounds) triggered by the surging economic growth during 2002-2012. During the same time, the effects of energy structure, production structure and population growth were relatively less significant to all pollutants, which indicates the potential of large emission abatements through energy structure and production structure adjustment. Sensitivity simulations by the air quality model based on the provincial decomposition results also show that the economic growth have outpaced efficiency improvements in the increments of PM2.5 concentrations during the study years. As China continues to develop rapidly, future policies should promote further improvements in efficiency and accelerate the adjustments toward clean energy and production structures, which are critical for reducing China's emissions and alleviating the severe PM2.5 pollution.

From atomic structure to excess entropy: a neutron diffraction and density functional theory study of CaO-Al2O3-SiO2 melts

NASA Astrophysics Data System (ADS)

Liu, Maoyuan; Jacob, Aurélie; Schmetterer, Clemens; Masset, Patrick J.; Hennet, Louis; Fischer, Henry E.; Kozaily, Jad; Jahn, Sandro; Gray-Weale, Angus

2016-04-01

Calcium aluminosilicate \\text{CaO}-\\text{A}{{\\text{l}}2}{{\\text{O}}3}-\\text{Si}{{\\text{O}}2} (CAS) melts with compositions {{≤ft(\\text{CaO}-\\text{Si}{{\\text{O}}2}\\right)}x}{{≤ft(\\text{A}{{\\text{l}}2}{{\\text{O}}3}\\right)}1-x} for x  <  0.5 and {{≤ft(\\text{A}{{\\text{l}}2}{{\\text{O}}3}\\right)}x}{{≤ft(\\text{Si}{{\\text{O}}2}\\right)}1-x} for x≥slant 0.5 are studied using neutron diffraction with aerodynamic levitation and density functional theory molecular dynamics modelling. Simulated structure factors are found to be in good agreement with experimental structure factors. Local atomic structures from simulations reveal the role of calcium cations as a network modifier, and aluminium cations as a non-tetrahedral network former. Distributions of tetrahedral order show that an increasing concentration of the network former Al increases entropy, while an increasing concentration of the network modifier Ca decreases entropy. This trend is opposite to the conventional understanding that increasing amounts of network former should increase order in the network liquid, and so decrease entropy. The two-body correlation entropy S 2 is found to not correlate with the excess entropy values obtained from thermochemical databases, while entropies including higher-order correlations such as tetrahedral order, O-M-O or M-O-M bond angles and Q N environments show a clear linear correlation between computed entropy and database excess entropy. The possible relationship between atomic structures and excess entropy is discussed.

Physico-chemical properties and cytotoxic effects of sugar-based surfactants: Impact of structural variations.

PubMed

Lu, Biao; Vayssade, Muriel; Miao, Yong; Chagnault, Vincent; Grand, Eric; Wadouachi, Anne; Postel, Denis; Drelich, Audrey; Egles, Christophe; Pezron, Isabelle

2016-09-01

Surfactants derived from the biorefinery process can present interesting surface-active properties, low cytotoxicity, high biocompatibility and biodegradability. They are therefore considered as potential sustainable substitutes to currently used petroleum-based surfactants. To better understand and anticipate their performances, structure-property relationships need to be carefully investigated. For this reason, we applied a multidisciplinary approach to systematically explore the effect of subtle structural variations on both physico-chemical properties and biological effects. Four sugar-based surfactants, each with an eight carbon alkyl chain bound to a glucose or maltose head group by an amide linkage, were synthesized and evaluated together along with two commercially available standard surfactants. Physico-chemical properties including solubility, Krafft point, surface-tension lowering and critical micellar concentration (CMC) in water and biological medium were explored. Cytotoxicity evaluation by measuring proliferation index and metabolic activity against dermal fibroblasts showed that all surfactants studied may induce cell death at low concentrations (below their CMC). Results revealed significant differences in both physico-chemical properties and cytotoxic effects depending on molecule structural features, such as the position of the linkage on the sugar head-group, or the orientation of the amide linkage. Furthermore, the cytotoxic response increased with the reduction of surfactant CMC. This study underscores the relevance of a methodical and multidisciplinary approach that enables the consideration of surfactant solution properties when applied to biological materials. Overall, our results will contribute to a better understanding of the concomitant impact of surfactant structure at physico-chemical and biological levels. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of Se concentration on photonic bandgap of 1-D As-S-Se/air multilayers

NASA Astrophysics Data System (ADS)

Singh, Rajpal; Suthar, B.; Bhargava, A.

2018-05-01

The photonic band structure of 1-D chalcogenide photonic crystal consisting of As-S-Se/air multilayered structure is studied. The photonic band structure is calculated using plane wave expansion method. The effect of Se constration on the photonic bandgap is studied. It is found that the photonic bandgap increases with Se-concentration and shows the red shift.

Effect of stress concentrations in composite structures

NASA Technical Reports Server (NTRS)

Babcock, G. D.; Knauss, W. G.

1984-01-01

The goal of achieving a better understanding of the failure of complex composite structure is sought. This type of structure requires a thorough understanding of the behavior under load both on a macro and micro scale if failure mechanisms are to be understood. The two problems being studied are the failure at a panel/stiffener interface and a generic problem of failure at a stress concentration.

Confirmation of a meteoritic component in impact-melt rocks of the Chesapeake Bay impact structure, Virginia, USA - Evidence from osmium isotopic and PGE systematics

USGS Publications Warehouse

Lee, S.R.; Horton, J. Wright; Walker, R.J.

2006-01-01

The osmium isotope ratios and platinum-group element (PGE) concentrations of impact-melt rocks in the Chesapeake Bay impact structure were determined. The impact-melt rocks come from the cored part of a lower-crater section of suevitic crystalline-clast breccia in an 823 m scientific test hole over the central uplift at Cape Charles, Virginia. The 187Os/188Os ratios of impact-melt rocks range from 0.151 to 0.518. The rhenium and platinum-group element (PGE) concentrations of these rocks are 30-270?? higher than concentrations in basement gneiss, and together with the osmium isotopes indicate a substantial meteoritic component in some impact-melt rocks. Because the PGE abundances in the impact-melt rocks are dominated by the target materials, interelemental ratios of the impact-melt rocks are highly variable and nonchondritic. The chemical nature of the projectile for the Chesapeake Bay impact structure cannot be constrained at this time. Model mixing calculations between chondritic and crustal components suggest that most impact-melt rocks include a bulk meteoritic component of 0.01-0.1% by mass. Several impact-melt rocks with lowest initial 187Os/188Os ratios and the highest osmium concentrations could have been produced by additions of 0.1%-0.2% of a meteoritic component. In these samples, as much as 70% of the total Os may be of meteoritic origin. At the calculated proportions of a meteoritic component (0.01-0.1% by mass), no mixtures of the investigated target rocks and sediments can reproduce the observed PGE abundances of the impact-melt rocks, suggesting that other PGE enrichment processes operated along with the meteoritic contamination. Possible explanations are 1) participation of unsampled target materials with high PGE abundances in the impact-melt rocks, and 2) variable fractionations of PGE during syn- to post-impact events. ?? The Meteoritical Society, 2006.

Process development and fabrication of space station type aluminum-clad graphite epoxy struts

NASA Technical Reports Server (NTRS)

Ring, L. R.

1990-01-01

The manufacture of aluminum-clad graphite epoxy struts, designed for application to the Space Station truss structure, is described. The strut requirements are identified, and the strut material selection rationale is discussed. The manufacturing procedure is described, and shop documents describing the details are included. Dry graphite fiber, Pitch-75, is pulled between two concentric aluminum tubes. Epoxy resin is then injected and cured. After reduction of the aluminum wall thickness by chemical milling the end fittings are bonded on the tubes. A discussion of the characteristics of the manufactured struts, i.e., geometry, weight, and any anomalies of the individual struts is included.

Concentration-Driven Assembly and Sol–Gel Transition of π-Conjugated Oligopeptides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Yuecheng; Li, Bo; Li, Songsong

Advances in supramolecular assembly have enabled the design and synthesis of functional materials with well-defined structures across multiple length scales. Biopolymer-synthetic hybrid materials can assemble into supramolecular structures with a broad range of structural and functional diversity through precisely controlled noncovalent interactions between subunits. Despite recent progress, there is a need to understand the mechanisms underlying the assembly of biohybrid/synthetic molecular building blocks, which ultimately control the emergent properties of hierarchical assemblies. Here in this work, we study the concentration-driven self-assembly and gelation of π-conjugated synthetic oligopeptides containing different π-conjugated cores (quaterthiophene and perylene diimide) using a combination of particlemore » tracking microrheology, confocal fluorescence microscopy, optical spectroscopy, and electron microscopy. Our results show that π-conjugated oligopeptides self-assemble into β-sheet-rich fiber-like structures at neutral pH, even in the absence of electrostatic screening of charged residues. A critical fiber formation concentration c fiber and a critical gel concentration c gel are determined for fiber-forming π-conjugated oligopeptides, and the linear viscoelastic moduli (storage modulus G' and loss modulus G") are determined across a wide range of peptide concentrations. These results suggest that the underlying chemical structure of the synthetic π-conjugated cores greatly influences the self-assembly process, such that oligopeptides appended to π-conjugated cores with greater torsional flexibility tend to form more robust fibers upon increasing peptide concentration compared to oligopeptides with sterically constrained cores. Overall, our work focuses on the molecular assembly of π-conjugated oligopeptides driven by concentration, which is controlled by a combination of enthalpic and entropic interactions between oligopeptide subunits.« less

Concentration-Driven Assembly and Sol–Gel Transition of π-Conjugated Oligopeptides

DOE PAGES

Zhou, Yuecheng; Li, Bo; Li, Songsong; ...

2017-08-17

Advances in supramolecular assembly have enabled the design and synthesis of functional materials with well-defined structures across multiple length scales. Biopolymer-synthetic hybrid materials can assemble into supramolecular structures with a broad range of structural and functional diversity through precisely controlled noncovalent interactions between subunits. Despite recent progress, there is a need to understand the mechanisms underlying the assembly of biohybrid/synthetic molecular building blocks, which ultimately control the emergent properties of hierarchical assemblies. Here in this work, we study the concentration-driven self-assembly and gelation of π-conjugated synthetic oligopeptides containing different π-conjugated cores (quaterthiophene and perylene diimide) using a combination of particlemore » tracking microrheology, confocal fluorescence microscopy, optical spectroscopy, and electron microscopy. Our results show that π-conjugated oligopeptides self-assemble into β-sheet-rich fiber-like structures at neutral pH, even in the absence of electrostatic screening of charged residues. A critical fiber formation concentration c fiber and a critical gel concentration c gel are determined for fiber-forming π-conjugated oligopeptides, and the linear viscoelastic moduli (storage modulus G' and loss modulus G") are determined across a wide range of peptide concentrations. These results suggest that the underlying chemical structure of the synthetic π-conjugated cores greatly influences the self-assembly process, such that oligopeptides appended to π-conjugated cores with greater torsional flexibility tend to form more robust fibers upon increasing peptide concentration compared to oligopeptides with sterically constrained cores. Overall, our work focuses on the molecular assembly of π-conjugated oligopeptides driven by concentration, which is controlled by a combination of enthalpic and entropic interactions between oligopeptide subunits.« less

Cardiac Biomarkers in Youth with Type 2 Diabetes Mellitus: Results from the TODAY Study.

PubMed

Gidding, Samuel S; Bacha, Fida; Bjornstad, Petter; Levitt Katz, Lorraine E; Levitsky, Lynne L; Lynch, Jane; Tryggestad, Jeanie B; Weinstock, Ruth S; El Ghormli, Laure; Lima, Joao A C

2018-01-01

To examine cardiac biomarkers over time in youth-onset type 2 diabetes, and relate serum concentrations to cardiovascular disease risk factors, and left ventricular structure and function. TODAY (Treatment Options for type 2 Diabetes in Adolescents and Youth) was a multicenter randomized trial of 3 treatments including 521 participants with type 2 diabetes, aged 10-17 years, and with 2-6 years of follow-up. Participants were 36% male, obese, and ethnically diverse. Annual serum concentrations of brain natriuretic peptide, troponin, tumor necrosis factor (TNF)-α, receptors 1 and 2 were related to blood pressure, body mass index, hemoglobin A1c, and left ventricular ejection fraction, diastolic function, relative wall thickness, and mass. Elevated concentrations of brain natriuretic peptide (≥100 pg/mL), TNF-α (≥5.6 pg/mL) and troponin (≥0.01 ng/mL), were present in 17.8%, 18.3%, and 34.2% of the cohort, respectively, at baseline, and in 15.4%, 17.1%, and 31.1% at the end of the study, with wide variability over time, without persistence in individuals or clear relationship to glycemia or cardiovascular structure/function. TNF receptors concentrations were increased at baseline and not significantly different from end-of-study concentrations. Adverse echocardiographic measures were more likely in the highest TNF receptor tertile (all P < .05): higher left ventricular mass (39.3 ± 9.0 g/m 2.7 ), left atrial internal dimension (3.7 ± 0.4 cm) and E/Em ratio, a measure of diastolic dysfunction (6.2 ± 1.9). After adjustment for body mass index, these relationships were no longer significant. Elevated serum concentrations of cardiac biomarkers were common in youth with type 2 diabetes, but their clinical significance is unclear and will require further long-term study. ClinicalTrials.govNCT00081328. Copyright © 2017 Elsevier Inc. All rights reserved.

Fabricating Composite-Material Structures Containing SMA Ribbons

NASA Technical Reports Server (NTRS)

Turner, Travis L.; Cano, Roberto J.; Lach, Cynthia L.

2003-01-01

An improved method of designing and fabricating laminated composite-material (matrix/fiber) structures containing embedded shape-memory-alloy (SMA) actuators has been devised. Structures made by this method have repeatable, predictable properties, and fabrication processes can readily be automated. Such structures, denoted as shape-memory-alloy hybrid composite (SMAHC) structures, have been investigated for their potential to satisfy requirements to control the shapes or thermoelastic responses of themselves or of other structures into which they might be incorporated, or to control noise and vibrations. Much of the prior work on SMAHC structures has involved the use SMA wires embedded within matrices or within sleeves through parent structures. The disadvantages of using SMA wires as the embedded actuators include (1) complexity of fabrication procedures because of the relatively large numbers of actuators usually needed; (2) sensitivity to actuator/ matrix interface flaws because voids can be of significant size, relative to wires; (3) relatively high rates of breakage of actuators during curing of matrix materials because of sensitivity to stress concentrations at mechanical restraints; and (4) difficulty of achieving desirable overall volume fractions of SMA wires when trying to optimize the integration of the wires by placing them in selected layers only.

Load concentration due to missing members in planar faces of a large space truss

NASA Technical Reports Server (NTRS)

Waltz, J. E.

1979-01-01

A large space structure with members missing was investigated using a finite element analysis. The particular structural configuration was the tetrahedral truss, with attention restricted to one of its planar faces. Initially the finite element model of a complete face was verified by comparing it with known results for some basic loadings. Then an analysis was made of the structure with members near the center removed. Some calculations were made on the influence of the mesh size of a structure containing a hexagonal hole, and an analysis was also made of a structure with a rigid hexagonal insert. In general, load concentration effects in these trusses were significantly lower than classical stress concentration effects in an infinitely wide isotropic plate with a circular rigid inclusion, although larger effects were obtained when a hole extended over several rings of elements.

Influence of the Ag concentration on the medium-range order in a CuZrAlAg bulk metallic glass

DOE PAGES

Gammer, C.; Escher, B.; Ebner, C.; ...

2017-03-21

Fluctuation electron microscopy of bulk metallic glasses of CuZrAl(Ag) demonstrates that medium-range order is sensitive to minor compositional changes. Furthermore, by analyzing nanodiffraction patterns medium-range order is detected with crystal-like motifs based on the B2 CuZr structure and its distorted structures resembling the martensitic ones. This result thus demonstrates some structural homology between the metallic glass and its high temperature crystalline phase. The amount of medium-range order seems slightly affected with increasing Ag concentration (0, 2, 5 at.%) but the structural motifs of the medium-range ordered clusters become more diverse at the highest Ag concentration. The decrease of dominant clustersmore » is consistent with the destabilization of the B2 structure measured by calorimetry and accounts for the increased glass-forming ability.« less

Influence of the Ag concentration on the medium-range order in a CuZrAlAg bulk metallic glass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gammer, C.; Escher, B.; Ebner, C.

Fluctuation electron microscopy of bulk metallic glasses of CuZrAl(Ag) demonstrates that medium-range order is sensitive to minor compositional changes. Furthermore, by analyzing nanodiffraction patterns medium-range order is detected with crystal-like motifs based on the B2 CuZr structure and its distorted structures resembling the martensitic ones. This result thus demonstrates some structural homology between the metallic glass and its high temperature crystalline phase. The amount of medium-range order seems slightly affected with increasing Ag concentration (0, 2, 5 at.%) but the structural motifs of the medium-range ordered clusters become more diverse at the highest Ag concentration. The decrease of dominant clustersmore » is consistent with the destabilization of the B2 structure measured by calorimetry and accounts for the increased glass-forming ability.« less

Ink composition for making a conductive silver structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walker, Steven B.; Lewis, Jennifer A.

An ink composition for making a conductive silver structure comprises a silver salt and a complex of (a) a complexing agent and a short chain carboxylic acid or (b) a complexing agent and a salt of a short chain carboxylic acid, according to one embodiment. A method for making a silver structure entails combining a silver salt and a complexing agent, and then adding a short chain carboxylic acid or a salt of the short chain carboxylic acid to the combined silver salt and a complexing agent to form an ink composition. A concentration of the complexing agent in themore » ink composition is reduced to form a concentrated formulation, and the silver salt is reduced to form a conductive silver structure, where the concentrated formulation and the conductive silver structure are formed at a temperature of about 120.degree. C. or less.« less

Simple electrolyte solutions: Comparison of DRISM and molecular dynamics results for alkali halide solutions

PubMed Central

Joung, In Suk; Luchko, Tyler; Case, David A.

2013-01-01

Using the dielectrically consistent reference interaction site model (DRISM) of molecular solvation, we have calculated structural and thermodynamic information of alkali-halide salts in aqueous solution, as a function of salt concentration. The impact of varying the closure relation used with DRISM is investigated using the partial series expansion of order-n (PSE-n) family of closures, which includes the commonly used hypernetted-chain equation (HNC) and Kovalenko-Hirata closures. Results are compared to explicit molecular dynamics (MD) simulations, using the same force fields, and to experiment. The mean activity coefficients of ions predicted by DRISM agree well with experimental values at concentrations below 0.5 m, especially when using the HNC closure. As individual ion activities (and the corresponding solvation free energies) are not known from experiment, only DRISM and MD results are directly compared and found to have reasonably good agreement. The activity of water directly estimated from DRISM is nearly consistent with values derived from the DRISM ion activities and the Gibbs-Duhem equation, but the changes in the computed pressure as a function of salt concentration dominate these comparisons. Good agreement with experiment is obtained if these pressure changes are ignored. Radial distribution functions of NaCl solution at three concentrations were compared between DRISM and MD simulations. DRISM shows comparable water distribution around the cation, but water structures around the anion deviate from the MD results; this may also be related to the high pressure of the system. Despite some problems, DRISM-PSE-n is an effective tool for investigating thermodynamic properties of simple electrolytes. PMID:23387564

Density functional theory and experimental study of the electronic structure and transport properties of La, V, Nb, and Ta doped SrTiO3

NASA Astrophysics Data System (ADS)

Baniecki, J. D.; Ishii, M.; Aso, H.; Kurihara, K.; Ricinschi, Dan

2013-01-01

The electronic structure and transport properties of donor doped SrTiO3 are studied using density functional theory with spin-orbit coupling and conductivity, Hall, and Seebeck effect measurements over a wide temperature range (100 K to 600 K). Split-off energies ΔSO are tunable through the dopant SO interaction strength and concentration varying from 28.1 meV for pure STO to 70.93 meV for SrTi0.5Nb0.5O3. At lower carrier concentrations and temperatures, SO coupling has a marked effect on both the filling dependence of the density-of-states mass as well as the temperature dependence of the Seebeck coefficient, with quantitative theoretical predictions based on DFT calculations that include the SO interaction in closer agreement to the experimental data. Moreover, the results suggest that the predictive power of the current theory is not unlimited, with less accuracy for the calculated S predicting the magnitude of the experimental S data at lower dopant concentrations than for degenerately doped systems. A concentration dependent mass enhancement of ˜2-5, relative to the density-of-states mass in the local density approximation, possibly due to the influence of electronic screening of the electron-phonon interaction, would bring the theoretical S in accord with the experimental S data. This additional carrier-dependent enhancement mechanism for S may give an additional degree of freedom in terms of designing new higher efficiency thermoelectric energy materials.

Models of globular proteins in aqueous solutions

NASA Astrophysics Data System (ADS)

Wentzel, Nathaniel James

Protein crystallization is a continuing area of research. Currently, there is no universal theory for the conditions required to crystallize proteins. A better understanding of protein crystallization will be helpful in determining protein structure and preventing and treating certain diseases. In this thesis, we will extend the understanding of globular proteins in aqueous solutions by analyzing various models for protein interactions. Experiments have shown that the liquid-liquid phase separation curves for lysozyme in solution with salt depend on salt type and salt concentration. We analyze a simple square well model for this system whose well depth depends on salt type and salt concentration, to determine the phase coexistence surfaces from experimental data. The surfaces, calculated from a single Monte Carlo simulation and a simple scaling argument, are shown as a function of temperature, salt concentration and protein concentration for two typical salts. Urate Oxidase from Asperigillus flavus is a protein used for studying the effects of polymers on the crystallization of large proteins. Experiments have determined some aspects of the phase diagram. We use Monte Carlo techniques and perturbation theory to predict the phase diagram for a model of urate oxidase in solution with PEG. The model used includes an electrostatic interaction, van der Waals attraction, and a polymerinduced depletion interaction. The results agree quantitatively with experiments. Anisotropy plays a role in globular protein interactions, including the formation of hemoglobin fibers in sickle cell disease. Also, the solvent conditions have been shown to play a strong role in the phase behavior of some aqueous protein solutions. Each has previously been treated separately in theoretical studies. Here we propose and analyze a simple, combined model that treats both anisotropy and solvent effects. We find that this model qualitatively explains some phase behavior, including the existence of a lower critical point under certain conditions.

[Characterization of structural change of ascorbate peroxidase from Chinese kale during denaturation by circular dichroism].

PubMed

Xi, Jia-Fu; Tang, Lei; Zhang, Jian-Hua; Zhang, Hong-Jian; Chen, Xu-Sheng; Mao, Zhong-Gui

2014-11-01

Circular dichroism (CD) is a special absorption spectrum. The secondary structure of protein such as α-helix, β-sheet and β-turn in the far ultraviolet region (190-250 nm) has a characteristic CD spectrum. In order to understand the activity and structural changes of ascorbate peroxidase from Chinese kale (BaAPX) during denaturation, specific activity and percentage of secondary structure of BaAPX under different time, temperature and concentration were analyzed by CD dynamically. In addition, the percentage of four secondary structures in BaAPX was calculated by CD analysis software Dichroweb. The results show that BaAPX is a full α-type enzyme whose specific activity is positively related to the percentage of α-helix. During denaturation of BaAPX, three kinds of structural changes were proposed: the one-step structural change from initial state (N state) to minimum state of α-helix (R state) under low concentration and low temperature; the one-step structural change from N state to equilibrium state (T state) under high concentration and low temperature; the two-step structural changes from N state through R state to final T state under heat treatment and low temperature renaturation.

The thermal stability of the nanograin structure in a weak solute segregation system.

PubMed

Tang, Fawei; Song, Xiaoyan; Wang, Haibin; Liu, Xuemei; Nie, Zuoren

2017-02-08

A hybrid model that combines first principles calculations and thermodynamic evaluation was developed to describe the thermal stability of a nanocrystalline solid solution with weak segregation. The dependence of the solute segregation behavior on the electronic structure, solute concentration, grain size and temperature was demonstrated, using the nanocrystalline Cu-Zn system as an example. The modeling results show that the segregation energy changes with the solute concentration in a form of nonmonotonic function. The change in the total Gibbs free energy indicates that at a constant solute concentration and a given temperature, a nanocrystalline structure can remain stable when the initial grain size is controlled in a critical range. In experiments, dense nanocrystalline Cu-Zn alloy bulk was prepared, and a series of annealing experiments were performed to examine the thermal stability of the nanograins. The experimental measurements confirmed the model predictions that with a certain solute concentration, a state of steady nanograin growth can be achieved at high temperatures when the initial grain size is controlled in a critical range. The present work proposes that in weak solute segregation systems, the nanograin structure can be kept thermally stable by adjusting the solute concentration and initial grain size.

Nitrogen Forms Influence Microcystin Concentration and Composition via Changes in Cyanobacterial Community Structure

PubMed Central

Monchamp, Marie-Eve; Pick, Frances R.; Beisner, Beatrix E.; Maranger, Roxane

2014-01-01

The eutrophication of freshwaters is a global health concern as lakes with excess nutrients are often subject to toxic cyanobacterial blooms. Although phosphorus is considered the main element regulating cyanobacterial biomass, nitrogen (N) concentration and more specifically the availability of different N forms may influence the overall toxicity of blooms. In this study of three eutrophic lakes prone to cyanobacterial blooms, we examined the effects of nitrogen species and concentrations and other environmental factors in influencing cyanobacterial community structure, microcystin (MC) concentrations and MC congener composition. The identification of specific MC congeners was of particular interest as they vary widely in toxicity. Different nitrogen forms appeared to influence cyanobacterial community structure leading to corresponding effects on MC concentrations and composition. Total MC concentrations across the lakes were largely explained by a combination of abiotic factors: dissolved organic nitrogen, water temperature and ammonium, but Microcystis spp. biomass was overall the best predictor of MC concentrations. Environmental factors did not appear to affect MC congener composition directly but there were significant associations between specific MC congeners and particular species. Based on redundancy analyses (RDA), the relative biomass of Microcystis aeruginosa was associated with MC-RR, M. wesenbergii with MC-LA and Aphanizomenon flos-aquae with MC-YR. The latter two species are not generally considered capable of MC production. Total nitrogen, water temperature, ammonium and dissolved organic nitrogen influenced the cyanobacterial community structure, which in turn resulted in differences in the dominant MC congener and the overall toxicity. PMID:24427318

Primary centers and secondary concentrations of tectonic activity through time in the western hemisphere of Mars

USGS Publications Warehouse

Anderson, R.C.; Dohm, J.M.; Golombek, M.P.; Haldemann, A.F.C.; Franklin, B.J.; Tanaka, K.L.; Lias, J.; Peer, B.

2001-01-01

Five main stages of radial and concentric structures formed around Tharsis from the Noachian through the Amazonian as determined by geologic mapping of 24,452 structures within the stratigraphic framework of Mars and by testing their radial and concentric orientations. Tectonic activity peaked in the Noachian (stage 1) around the largest center, Claritas, an elongate center extending more than 20?? in latitude and defined by about half of the total grabens which are concentrated in the Syria Planum, Thaumasia, and Tempe Terra regions. During the Late Noachian and Early Hesperian (stage 2), extensional structures formed along the length of present-day Valles Marineris and in Thaumasia (with a secondary concentration near Warrego Vallis) radial to a region just to the south of the central margin of Valles Marineris. Early Hesperian (stage 3) radial grabens in Pavonis, Syria, Ulysses, and Tempe Terra and somewhat concentric wrinkle ridges in Lunae and Solis Plana and in Thaumasia, Sirenum, Memnonia, and Amazonis are centered northwest of Syria with secondary centers at Thaumasia, Tempe Terra, Ulysses Fossae, and western Valles Marineris. Late Hesperian/Early Amazonian (stage 4) structures around Alba Patera, the northeast trending alignment of Tharsis Montes, and Olympus Mons appears centered on Alba Patera. Stage 5 structures (Middle-Late Amazonian) represent the last pulse of Tharsis-related activity and are found around the large shield volcanoes and are centered near Pavonis Mons. Tectonic activity around Tharsis began in the Noachian and generally decreased through geologic time to the Amazonian. Statistically significant radial distributions of structures formed during each stage, centered at different locations within the higher elevations of Tharsis. Secondary centers of radial structures during many of the stages appear related to previously identified local magmatic centers that formed at different times and locations throughout Tharsis. Copyright 2001 by the American Geophysical Union.

First spaceborne observation of the entire concentric airglow structure caused by tropospheric disturbance

NASA Astrophysics Data System (ADS)

Akiya, Y.; Saito, A.; Sakanoi, T.; Hozumi, Y.; Yamazaki, A.; Otsuka, Y.; Nishioka, M.; Tsugawa, T.

2014-10-01

Spaceborne imagers are able to observe the airglow structures with wide field of views regardless of the tropospheric condition that limits the observational time of the ground-based imagers. Concentric wave structures of the O2 airglow in 762 nm wavelength were observed over North America on 1 June 2013 from the International Space Station. This was the first observation in which the entire image of the structure was captured from space, and its spatial scale size was determined to be 1200 km radius without assumptions. The apparent horizontal wavelength was 80 km, and the amplitude in the intensity was approximately 20% of the background intensity. The propagation velocity of the structure was derived as 125 ± 62 m/s and atmospheric gravity waves were estimated to be generated for 3.5 ± 1.7 h. Concentric structures observed in this event were interpreted to be generated by super cells that caused a tornado in its early phase.

Environment-Dependent Distribution of the Sediment nifH-Harboring Microbiota in the Northern South China Sea

PubMed Central

Yang, Jinying; Li, Jing; Luan, Xiwu; Zhang, Yunbo; Gu, Guizhou; Xue, Rongrong; Zong, Mingyue; Klotz, Martin G.

2013-01-01

The South China Sea (SCS), the largest marginal sea in the Western Pacific Ocean, is a huge oligotrophic water body with very limited influx of nitrogenous nutrients. This suggests that sediment microbial N2 fixation plays an important role in the production of bioavailable nitrogen. To test the molecular underpinning of this hypothesis, the diversity, abundance, biogeographical distribution, and community structure of the sediment diazotrophic microbiota were investigated at 12 sampling sites, including estuarine, coastal, offshore, deep-sea, and methane hydrate reservoirs or their prospective areas by targeting nifH and some other functional biomarker genes. Diverse and novel nifH sequences were obtained, significantly extending the evolutionary complexity of extant nifH genes. Statistical analyses indicate that sediment in situ temperature is the most significant environmental factor influencing the abundance, community structure, and spatial distribution of the sediment nifH-harboring microbial assemblages in the northern SCS (nSCS). The significantly positive correlation of the sediment pore water NH4+ concentration with the nifH gene abundance suggests that the nSCS sediment nifH-harboring microbiota is active in N2 fixation and NH4+ production. Several other environmental factors, including sediment pore water PO43− concentration, sediment organic carbon, nitrogen and phosphorus levels, etc., are also important in influencing the community structure, spatial distribution, or abundance of the nifH-harboring microbial assemblages. We also confirmed that the nifH genes encoded by archaeal diazotrophs in the ANME-2c subgroup occur exclusively in the deep-sea methane seep areas, providing for the possibility to develop ANME-2c nifH genes as a diagnostic tool for deep-sea methane hydrate reservoir discovery. PMID:23064334

Water-soluble mercury ion sensing based on the thymine-Hg2+-thymine base pair using retroreflective Janus particle as an optical signaling probe.

PubMed

Chun, Hyeong Jin; Kim, Saemi; Han, Yong Duk; Kim, Dong Woo; Kim, Ka Ram; Kim, Hyo-Sop; Kim, Jae-Ho; Yoon, Hyun C

2018-05-01

Herein, we report an optical sensing platform for mercury ions (Hg 2+ ) in water based on the integration of Hg 2+ -mediated thymine-thymine (T-T) stabilization, a biotinylated stem-loop DNA probe, and a streptavidin-modified retroreflective Janus particle (SA-RJP). Two oligonucleotide probes, including a stem-loop DNA probe and an assistant DNA probe, were utilized. In the absence of Hg 2+ , the assistant DNA probe does not hybridize with the stem-loop probe due to their T-T mismatch, so the surface-immobilized stem-loop DNA probe remains a closed hairpin structure. In the presence of Hg 2+ , the DNA forms a double-stranded structure with the loop region via Hg 2+ -mediated T-T stabilization. This DNA hybridization induces stretching of the stem-loop DNA probe, exposing biotin. To translate these Hg 2+ -mediated structural changes in DNA probe into measurable signal, SA-RJP, an optical signaling label, is applied to recognize the exposed biotin. The number of biospecifically bound SA-RJPs is proportional to the concentration of Hg 2+ , so that the concentration of Hg 2+ can be quantitatively analyzed by counting the number of RJPs. Using the system, a highly selective and sensitive measurement of Hg 2+ was accomplished with a limit of detection of 0.027nM. Considering the simplified optical instrumentation required for retroreflection-based RJP counting, RJP-assisted Hg 2+ measurement can be accomplished in a much easier and inexpensive manner. Moreover, the detection of Hg 2+ in real drinking water samples including tap and commercial bottled water was successfully carried out. Copyright © 2018 Elsevier B.V. All rights reserved.

Assessment of biofilm changes and concentration-depth profiles during arsenopyrite oxidation by Acidithiobacillus thiooxidans.

PubMed

Ramírez-Aldaba, Hugo; Vazquez-Arenas, Jorge; Sosa-Rodríguez, Fabiola S; Valdez-Pérez, Donato; Ruiz-Baca, Estela; García-Meza, Jessica Viridiana; Trejo-Córdova, Gabriel; Lara, René H

2017-08-01

Biofilm formation and evolution are key factors to consider to better understand the kinetics of arsenopyrite biooxidation. Chemical and surface analyses were carried out using Raman spectroscopy, scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), glow discharge spectroscopy (GDS), and protein analysis (i.e., quantification) in order to evaluate the formation of intermediate secondary compounds and any significant changes arising in the biofilm structure of Acidithiobacillus thiooxidans during a 120-h period of biooxidation. Results show that the biofilm first evolves from a low cell density structure (1 to 12 h) into a formation of microcolonies (24 to 120 h) and then finally becomes enclosed by a secondary compound matrix that includes pyrite (FeS 2 )-like, S n 2- /S 0 , and As 2 S 3 compounds, as shown by Raman and SEM-EDS. GDS analyses (concentration-depth profiles, i.e., 12 h) indicate significant differences for depth speciation between abiotic control and biooxidized surfaces, thus providing a quantitative assessment of surface-bulk changes across samples (i.e. reactivity and /or structure-activity relationship). Respectively, quantitative protein analyses and CLSM analyses suggest variations in the type of extracellular protein expressed and changes in the biofilm structure from hydrophilic (i.e., exopolysaccharides) to hydrophobic (i.e., lipids) due to arsenopyrite and cell interactions during the 120-h period of biooxidation. We suggest feasible environmental and industrial implications for arsenopyrite biooxidation based on the findings of this study.

Enkephalins in the inferior mesenteric ganglion of the cat and in the area of the lower digestive tract innervated by this ganglion: quantification by radio-immunoassay and characterization by high pressure liquid chromatography.

PubMed

Cupo, A; Niel, J P; Miolan, J P; Jule, Y; Jarry, T

1988-01-01

Met-enkephalin, Leu-enkephalin and Met-enkephalin-Arg-Gly-Leu were quantified and characterized in the cat inferior mesenteric ganglion and in the area of the lower digestive tract innervated by this ganglion, including the proximal colon, distal colon and internal anal sphincter. In the structures studied, the concentrations of enkephalins expressed as femtomole/mg of wet tissue ranged from 66 to 160 with Met-enkephalin, from 15 to 45 with Leu-enkephalin and from 2 to 12 for Met-enkephalin-arg-gly-leu. In the lower digestive tract, the Met- and Leu-enkephalin content decreased from the proximal colon to the internal anal sphincter. The Met-enkephalin versus Leu-enkephalin ratio of the structures investigated were as follows: inferior mesenteric ganglion 3.2, proximal colon 4.4, distal colon 5, internal and sphincter 4.5. In individual samples of all the structures assayed the results of high pressure liquid chromatography (HPLC) analysis pointed to the presence of authentic Met- and Leu-enkephalin. HPLC analysis could not be carried out on Met-enkephalin-Arg-Gly-Leu due to the very low concentrations of this peptide in all the structures assayed. Our results, combined with those of previous immunohistochemical and physiological studies, support the idea that enkephalins are involved in the nervous control of the motility of the lower digestive tract.

The theoretical study of passive and active optical devices via planewave based transfer (scattering) matrix method and other approaches

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhuo, Ye

2011-01-01

In this thesis, we theoretically study the electromagnetic wave propagation in several passive and active optical components and devices including 2-D photonic crystals, straight and curved waveguides, organic light emitting diodes (OLEDs), and etc. Several optical designs are also presented like organic photovoltaic (OPV) cells and solar concentrators. The first part of the thesis focuses on theoretical investigation. First, the plane-wave-based transfer (scattering) matrix method (TMM) is briefly described with a short review of photonic crystals and other numerical methods to study them (Chapter 1 and 2). Next TMM, the numerical method itself is investigated in details and developed inmore » advance to deal with more complex optical systems. In chapter 3, TMM is extended in curvilinear coordinates to study curved nanoribbon waveguides. The problem of a curved structure is transformed into an equivalent one of a straight structure with spatially dependent tensors of dielectric constant and magnetic permeability. In chapter 4, a new set of localized basis orbitals are introduced to locally represent electromagnetic field in photonic crystals as alternative to planewave basis. The second part of the thesis focuses on the design of optical devices. First, two examples of TMM applications are given. The first example is the design of metal grating structures as replacements of ITO to enhance the optical absorption in OPV cells (chapter 6). The second one is the design of the same structure as above to enhance the light extraction of OLEDs (chapter 7). Next, two design examples by ray tracing method are given, including applying a microlens array to enhance the light extraction of OLEDs (chapter 5) and an all-angle wide-wavelength design of solar concentrator (chapter 8). In summary, this dissertation has extended TMM which makes it capable of treating complex optical systems. Several optical designs by TMM and ray tracing method are also given as a full complement of this work.« less

Virtual screening of a milk peptide database for the identification of food-derived antimicrobial peptides.

PubMed

Liu, Yufang; Eichler, Jutta; Pischetsrieder, Monika

2015-11-01

Milk provides a wide range of bioactive substances, such as antimicrobial peptides and proteins. Our study aimed to identify novel antimicrobial peptides naturally present in milk. The components of an endogenous bovine milk peptide database were virtually screened for charge, amphipathy, and predicted secondary structure. Thus, 23 of 248 screened peptides were identified as candidates for antimicrobial effects. After commercial synthesis, their antimicrobial activities were determined against Escherichia coli NEB5α, E. coli ATCC25922, and Bacillus subtilis ATCC6051. In the tested concentration range (<2 mM), bacteriostatic activity of 14 peptides was detected including nine peptides inhibiting both Gram-positive and Gram-negative bacteria. The most effective fragment was TKLTEEEKNRLNFLKKISQRYQKFΑLPQYLK corresponding to αS2 -casein151-181 , with minimum inhibitory concentration (MIC) of 4.0 μM against B. subtilis ATCC6051, and minimum inhibitory concentrations of 16.2 μM against both E. coli strains. Circular dichroism spectroscopy revealed conformational changes of most active peptides in a membrane-mimic environment, transitioning from an unordered to α-helical structure. Screening of food peptide databases by prediction tools is an efficient method to identify novel antimicrobial food-derived peptides. Milk-derived antimicrobial peptides may have potential use as functional food ingredients and help to understand the molecular mechanisms of anti-infective milk effects. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interaction of NaOH solutions with silica surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rimsza, Jessica M.; Jones, Reese E.; Criscenti, Louise J.

Sodium adsorption on silica surfaces depends on the solution counter-ion. Here, we use NaOH solutions to investigate basic environments. Sodium adsorption on hydroxylated silica surfaces from NaOH solutions were investigated through molecular dynamics with a dissociative force field, allowing for the development of secondary molecular species. Furthermore, across the NaOH concentrations (0.01 M – 1.0 M), ~50% of the Na + ions were concentrated in the surface region, developing silica surface charges between –0.01 C/m 2 (0.01 M NaOH) and –0.76 C/m 2 (1.0 M NaOH) due to surface site deprotonation. Five inner-sphere adsorption complexes were identified, including monodentate, bidentate,more » and tridentate configurations and two additional structures, with Na + ions coordinated by bridging oxygen and hydroxyl groups or water molecules. Coordination of Na + ions by bridging oxygen atoms indicates partial or complete incorporation of Na + ions into the silica surface. Residence time analysis identified that Na + ions coordinated by bridging oxygen atoms stayed adsorbed onto the surface four times longer than the mono/bi/tridentate species, indicating formation of relatively stable and persistent Na + ion adsorption structures. Such inner-sphere complexes form only at NaOH concentrations of > 0.5 M. Na + adsorption and lifetimes have implications for the stability of silica surfaces.« less

Interaction of NaOH solutions with silica surfaces

DOE PAGES

Rimsza, Jessica M.; Jones, Reese E.; Criscenti, Louise J.

2018-01-16

Sodium adsorption on silica surfaces depends on the solution counter-ion. Here, we use NaOH solutions to investigate basic environments. Sodium adsorption on hydroxylated silica surfaces from NaOH solutions were investigated through molecular dynamics with a dissociative force field, allowing for the development of secondary molecular species. Furthermore, across the NaOH concentrations (0.01 M – 1.0 M), ~50% of the Na + ions were concentrated in the surface region, developing silica surface charges between –0.01 C/m 2 (0.01 M NaOH) and –0.76 C/m 2 (1.0 M NaOH) due to surface site deprotonation. Five inner-sphere adsorption complexes were identified, including monodentate, bidentate,more » and tridentate configurations and two additional structures, with Na + ions coordinated by bridging oxygen and hydroxyl groups or water molecules. Coordination of Na + ions by bridging oxygen atoms indicates partial or complete incorporation of Na + ions into the silica surface. Residence time analysis identified that Na + ions coordinated by bridging oxygen atoms stayed adsorbed onto the surface four times longer than the mono/bi/tridentate species, indicating formation of relatively stable and persistent Na + ion adsorption structures. Such inner-sphere complexes form only at NaOH concentrations of > 0.5 M. Na + adsorption and lifetimes have implications for the stability of silica surfaces.« less

Fluorinated ionic liquids for protein drug delivery systems: Investigating their impact on the structure and function of lysozyme.

PubMed

Alves, Márcia; Vieira, Nicole S M; Rebelo, Luís Paulo N; Araújo, João M M; Pereiro, Ana B; Archer, Margarida

2017-06-30

Since the approval of recombinant human insulin by FDA in 1982, more than 200 proteins are currently available for pharmaceutical use to treat a wide range of diseases. However, innovation is still required to develop effective approaches for drug delivery. Our aim is to investigate the potential use of fluorinated ionic liquids (FILs) as drug delivery systems (DDS) for therapeutic proteins. Some initial parameters need to be assessed before further studies can proceed. This work evaluates the impact of FILs on the stability, function, structure and aggregation state of lysozyme. Different techniques were used for this purpose, which included differential scanning fluorimetry (DSF), spectrophotometric assays, circular dichroism (CD), dynamic light scattering (DLS), and scanning and transmission electron microscopy (SEM/TEM). Ionic liquids composed of cholinium-, imidazolium- or pyridinium- derivatives were combined with different anions and analysed at different concentrations in aqueous solutions (below and above the critical aggregation concentration, CAC). The results herein presented show that the addition of ionic liquids had no significant effect on the stability and hydrolytic activity of lysozyme. Moreover, a distinct behaviour was observed in DLS experiments for non-surfactant and surfactant ionic liquids, with the latter encapsulating the protein at concentrations above the CAC. These results encourage us to further study ionic liquids as promising tools for DDS of protein drugs. Copyright © 2017 Elsevier B.V. All rights reserved.

Sea Spray and Icing in the Emerging Open Water of the Arctic Ocean

DTIC Science & Technology

2015-06-12

concentrations of wind-generated sea spray and the resulting spray icing on offshore structures, such as wind turbines and exploration, drilling , and...We anticipate that structures placed in shallow water—wind turbines, drilling rigs, or man-made production islands, for instance—will, therefore...and the severity of sea spray icing on fixed offshore structures. We will use existing information on the relationship of the spray concentration

Ohmic contacts to p-GaN Using Au/Ni-Mg-O Metallization

NASA Astrophysics Data System (ADS)

Liday, Jozef; Vogrinčič, Peter; Hotový, Ivan; Bonanni, Alberta; Sitter, Helmut; Lalinský, Tibor; Vanko, Gabriel; Řeháček, Vlastimil; Breza, Juraj; Ecke, Gernot

2010-11-01

Electrical characteristics and elemental depth profiles of ohmic contacts to p-GaN using Au/Ni-Mg-Ox metallization have been investigated. The objective was to examine the possibilities of increasing the charge carrier concentration in the surface region of GaN by adding Mg, thus of a p-type dopant into the Au/NiOx metallization structure. For this purpose, a Ni-Mg-Ox layer with a low concentration of Mg was deposited on p-GaN by dc reactive magnetron sputtering. The top Au layer was deposited in a similar way. The fabricated contact structures were annealed in N2. When the Ni-Mg layer in the Au/Ni-Mg-Ox/p-GaN structure was deposited in an atmosphere with a low concentration of oxygen (0.2 at%), the structure exhibited a low resistance ohmic nature. The contact resistance was lower than in the case of a Au/Ni-Ox/p-GaN structure without the Mg dopant in the metallic layer. An increase in the concentration of oxygen in the working atmosphere resulted in higher values of the contact resistance of the Au/Ni-Mg-Ox/p-GaN structure. In our opinion the ohmic nature of the contact structure is related to the existence of a metal/p-NiO/p-GaN scheme. The measured values of the contact resistance in the Au/Ni-Mg-Ox/p-GaN structure in comparison with the Au/Ni-Ox/p-GaN structure are caused by an increased charge carrier concentration in the surface region of p-GaN, which is a consequence of Mg diffusion from the Ni-Mg-Ox layer.

Membrane re-modelling by BAR domain superfamily proteins via molecular and non-molecular factors.

PubMed

Nishimura, Tamako; Morone, Nobuhiro; Suetsugu, Shiro

2018-04-17

Lipid membranes are structural components of cell surfaces and intracellular organelles. Alterations in lipid membrane shape are accompanied by numerous cellular functions, including endocytosis, intracellular transport, and cell migration. Proteins containing Bin-Amphiphysin-Rvs (BAR) domains (BAR proteins) are unique, because their structures correspond to the membrane curvature, that is, the shape of the lipid membrane. BAR proteins present at high concentration determine the shape of the membrane, because BAR domain oligomers function as scaffolds that mould the membrane. BAR proteins co-operate with various molecular and non-molecular factors. The molecular factors include cytoskeletal proteins such as the regulators of actin filaments and the membrane scission protein dynamin. Lipid composition, including saturated or unsaturated fatty acid tails of phospholipids, also affects the ability of BAR proteins to mould the membrane. Non-molecular factors include the external physical forces applied to the membrane, such as tension and friction. In this mini-review, we will discuss how the BAR proteins orchestrate membrane dynamics together with various molecular and non-molecular factors. © 2018 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

Flow behaviour and structure of heterogeneous particles-water mixture in horizontal and inclined pipes

NASA Astrophysics Data System (ADS)

Vlasák, Pavel; Chára, Zdeněk; Konfršt, Jiří

2018-06-01

The effect of slurry velocity and mean concentration of heterogeneous particle-water mixture on flow behaviour and structure in the turbulent regime was studied in horizontal and inclined pipe sections of inner diameter D = 100 mm. The stratified flow pattern of heterogeneous particle-water mixture in the inclined pipe sections was revealed. The particles moved mostly near to the pipe invert. Concentration distribution in ascending and descending vertical pipe sections confirmed the effect of fall velocity on particle-carrier liquid slip velocity and increase of in situ concentration in the ascending pipe section. Slip velocity in two-phase flow, which is defined as the velocity difference between the solid and liquid phase, is one of mechanism of particle movement in two-phase flow. Due to the slip velocity, there is difference between transport and in situ concentrations, and the slip velocity can be determined from comparison of the in situ and transport concentration. For heterogeneous particle-water mixture flow the slip velocity depends on the flow structure.