Laser desorption/ionization mass spectrometry of lipids using etched silver substrates.

PubMed

Schnapp, Andreas; Niehoff, Ann-Christin; Koch, Annika; Dreisewerd, Klaus

2016-07-15

Silver-assisted laser desorption/ionization mass spectrometry can be used for the analysis of small molecules. For example, adduct formation with silver cations enables the molecular analysis of long-chain hydrocarbons, which are difficult to ionize via conventional matrix-assisted laser desorption ionization (MALDI). Here we used highly porous silver foils, produced by etching with nitric acid, as sample substrates for LDI mass spectrometry. As model system for the analysis of complex lipid mixtures, cuticular extracts of fruit flies (Drosophila melanogaster) and worker bees (Apis mellifera) were investigated. The mass spectra obtained by spotting extract onto the etched silver substrates demonstrate the sensitive detection of numerous lipid classes such as long-chain saturated and unsaturated hydrocarbons, fatty acyl alcohols, wax esters, and triacylglycerols. MS imaging of cuticular surfaces with a lateral resolution of a few tens of micrometers became possible after blotting, i.e., after transferring lipids by physical contact with the substrate. The examples of pheromone-producing male hindwings of the squinting bush brown butterfly (Bicyclus anynana) and a fingermark are shown. Because the substrates are also easy to produce, they provide a viable alternative to colloidal silver nanoparticles and other so far described silver substrates. Copyright © 2016 Elsevier Inc. All rights reserved.

Determination of pollutant diffusion coefficients in naturally formed biofilms using a single tube extractive membrane bioreactor

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

Zhang, S.F.; Splendiani, A.; Freitas dos Santos, L.M.

A novel technique has been used to determine the effective diffusion coefficients for 1,1,2-trichloroethane (TCE), a nonreacting tracer, in biofilms growing on the external surface of a silicone rubber membrane tube during degradation of 1,2-dichloroethane (DCE) by Xanthobacter autotrophicus GJ10 and monochlorobenzene (MCB) by Pseudomonas JS150. Experiments were carried out in a single tube extractive membrane bioreactor (STEMB), whose configuration makes it possible to measure the transmembrane flux of substrates. A video imaging technique (VIT) was employed for in situ biofilm thickness measurement and recording. Diffusion coefficients of TCE in the biofilms and TCE mass transfer coefficients in the liquidmore » films adjacent to the biofilms were determined simultaneously using a resistances-in-series diffusion model. It was found that the flux and overall mass transfer coefficient of TCE decrease with increasing biofilm thickness, showing the importance of biofilm diffusion on the mass transfer process. Similar fluxes were observed for the nonreacting tracer (TCE) and the reactive substrates (MCB or DCE), suggesting that membrane-attached biofilm systems can be rate controlled primarily by substrate diffusion. The TCE diffusion coefficient in the JS150 biofilm appeared to be dependent on biofilm thickness, decreasing markedly for biofilm thicknesses of >1 mm. The values of the TCE diffusion coefficients in the JS150 biofilms <1-mm thick are approximately twice those in water and fall to around 30% of the water value for biofilms >1-mm thick.« less

Mass-transfer limitations for immobilized enzyme-catalyzed kinetic resolution of racemate in a fixed-bed reactor.

PubMed

Xiu, G H; Jiang, L; Li, P

2001-07-05

A mathematical model has been developed for immobilized enzyme-catalyzed kinetic resolution of racemate in a fixed-bed reactor in which the enzyme-catalyzed reaction (the irreversible uni-uni competitive Michaelis-Menten kinetics is chosen as an example) was coupled with intraparticle diffusion, external mass transfer, and axial dispersion. The effects of mass-transfer limitations, competitive inhibition of substrates, deactivation on the enzyme effective enantioselectivity, and the optical purity and yield of the desired product are examined quantitatively over a wide range of parameters using the orthogonal collocation method. For a first-order reaction, an analytical solution is derived from the mathematical model for slab-, cylindrical-, and spherical-enzyme supports. Based on the analytical solution for the steady-state resolution process, a new concise formulation is presented to predict quantitatively the mass-transfer limitations on enzyme effective enantioselectivity and optical purity and yield of the desired product for a continuous steady-state kinetic resolution process in a fixed-bed reactor. Copyright 2001 John Wiley & Sons, Inc.

Controls and variability of solute and sedimentary fluxes in Arctic and sub-Arctic Environments

NASA Astrophysics Data System (ADS)

Dixon, John

2015-04-01

Six major factors consistently emerge as controls on the spatial and temporal variability in sediment and solute fluxes in cold climates. They are climatic, geologic, physiographic or relief, biologic, hydrologic, and regolith factors. The impact of these factors on sediment and solute mass transfer in Arctic and sub-Arctic environments is examined. Comparison of non-glacierized Arctic vs. subarctic drainage basins reveals the effects of these controls. All drainage basins exhibit considerable variability in rates of sediment and solute fluxes. For the non-glacierized drainage basins there is a consistent increase in sediment mass transfer by slope processes and fluvial processes as relief increases. Similarly, a consistent increase in sediment mass transfer by slope and fluvial processes is observed as total precipitation increases. Similar patterns are also observed with respect to solute transport and relief and precipitation. Lithologic factors are most strongly observed in the contrast between volcanic vs. plutonic igneous bedrock substrates. Basins underlain by volcanic rocks display greater mass transfers than those underlain by plutonic rocks. Biologic influences are most strongly expressed by variations in extent of vegetation cover and the degree of human interference, with human impacted basins generating greater fluxes. For glacierized basins the fundamental difference to non-glacierized basins is an overall increase in mean annual mass transfers of sediment and a generally smaller magnitude solute transfer. The principal role of geology is observed with respect to lithology. Catchments underlain by limestone demonstrate substantially greater solute mass transfers than sediment transfer. The influence of relief is seen in the contrast in mass transfers between upland and lowland drainage basins with upland basins generating greater sediment and solute transfers than lowland basins. For glacierized basins the effects of biology and regolith appear to be largely overridden by the hydrologic impacts of glacierization.

Catalyst characterization in the presence of solvent: development of liquid phase structure–activity relationships

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

Gould, Nicholas S.; Xu, Bingjun

Due to the low volatility and highly oxygenated nature of biomass derived feedstocks, biomass upgrade reactions are frequently conducted in the presence of solvent to improve substrate mass transfer to the catalyst surface.

Catalyst characterization in the presence of solvent: development of liquid phase structure–activity relationships

DOE PAGES

Gould, Nicholas S.; Xu, Bingjun

2018-01-01

Due to the low volatility and highly oxygenated nature of biomass derived feedstocks, biomass upgrade reactions are frequently conducted in the presence of solvent to improve substrate mass transfer to the catalyst surface.

Hydride Transfer in DHFR by Transition Path Sampling, Kinetic Isotope Effects, and Heavy Enzyme Studies

PubMed Central

Wang, Zhen; Antoniou, Dimitri; Schwartz, Steven D.; Schramm, Vern L.

2016-01-01

Escherichia coli dihydrofolate reductase (ecDHFR) is used to study fundamental principles of enzyme catalysis. It remains controversial whether fast protein motions are coupled to the hydride transfer catalyzed by ecDHFR. Previous studies with heavy ecDHFR proteins labeled with 13C, 15N, and nonexchangeable 2H reported enzyme mass-dependent hydride transfer kinetics for ecDHFR. Here, we report refined experimental and computational studies to establish that hydride transfer is independent of protein mass. Instead, we found the rate constant for substrate dissociation to be faster for heavy DHFR. Previously reported kinetic differences between light and heavy DHFRs likely arise from kinetic steps other than the chemical step. This study confirms that fast (femtosecond to picosecond) protein motions in ecDHFR are not coupled to hydride transfer and provides an integrative computational and experimental approach to resolve fast dynamics coupled to chemical steps in enzyme catalysis. PMID:26652185

Gas hold-up and oxygen mass transfer in three pneumatic bioreactors operating with sugarcane bagasse suspensions.

PubMed

Esperança, M N; Cunha, F M; Cerri, M O; Zangirolami, T C; Farinas, C S; Badino, A C

2014-05-01

Sugarcane bagasse is a low-cost and abundant by-product generated by the bioethanol industry, and is a potential substrate for cellulolytic enzyme production. The aim of this work was to evaluate the effects of air flow rate (QAIR), solids loading (%S), sugarcane bagasse type, and particle size on the gas hold-up (εG) and volumetric oxygen transfer coefficient (kLa) in three different pneumatic bioreactors, using response surface methodology. Concentric tube airlift (CTA), split-cylinder airlift (SCA), and bubble column (BC) bioreactor types were tested. QAIR and %S affected oxygen mass transfer positively and negatively, respectively, while sugarcane bagasse type and particle size (within the range studied) did not influence kLa. Using large particles of untreated sugarcane bagasse, the loop-type bioreactors (CTA and SCA) exhibited higher mass transfer, compared to the BC reactor. At higher %S, SCA presented a higher kLa value (0.0448 s−1) than CTA, and the best operational conditions in terms of oxygen mass transfer were achieved for %S < 10.0 g L−1 and QAIR > 27.0 L min−1. These results demonstrated that pneumatic bioreactors can provide elevated oxygen transfer in the presence of vegetal biomass, making them an excellent option for use in three-phase systems for cellulolytic enzyme production by filamentous fungi.

The use of nanomaterials for mass spectrometry can be uplifting for analyte detection

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

Li, J.; Lipson, R. H.

2014-03-31

Surface-Assisted Laser Desorption Ionization (SALDI) involves desorbing and ionizing analyte molecules from a nanoporous substrate by laser irradiation for detection in a mass spectrometer. In this work experiments were designed to better understand the mechanisms governing desorption and ionization for Desorption Ionization On Silicon (DIOS), a variant of SALDI which uses porous silicon (pSi) as a substrate. Experiments are also reported for other nanoporous semiconducting materials (WO{sub 3}, TiO{sub 2}) which exhibit very similar behaviors; specifically, that both protonated analyte ions and analyte radical cations can be generated with relative intensities that depend on the position of the incident lasermore » focus relative to substrate surface. While thermal desorption appears to be important, preliminary evidence suggests that the ionization mechanism leading to protonated analytes involves in part electrons and holes formed when photoexciting the substrate above its electronic band gap, and the presence of defect states within the band gap. Radical cation formation appears to be driven in part by electron transfer due to the large electron affinity of each substrate used in this work.« less

Numerical simulations of epitaxial growth process in MOVPE reactor as a tool for design of modern semiconductors for high power electronics

NASA Astrophysics Data System (ADS)

Skibinski, Jakub; Caban, Piotr; Wejrzanowski, Tomasz; Kurzydlowski, Krzysztof J.

2014-10-01

In the present study numerical simulations of epitaxial growth of gallium nitride in Metal Organic Vapor Phase Epitaxy reactor AIX-200/4RF-S is addressed. Epitaxial growth means crystal growth that progresses while inheriting the laminar structure and the orientation of substrate crystals. One of the technological problems is to obtain homogeneous growth rate over the main deposit area. Since there are many agents influencing reaction on crystal area such as temperature, pressure, gas flow or reactor geometry, it is difficult to design optimal process. According to the fact that it's impossible to determine experimentally the exact distribution of heat and mass transfer inside the reactor during crystal growth, modeling is the only solution to understand the process precisely. Numerical simulations allow to understand the epitaxial process by calculation of heat and mass transfer distribution during growth of gallium nitride. Including chemical reactions in numerical model allows to calculate the growth rate of the substrate and estimate the optimal process conditions for obtaining the most homogeneous product.

Silicon Satellites: Picosats, Nanosats, and Microsats

NASA Technical Reports Server (NTRS)

Janson, Siegfried W.

1995-01-01

Silicon, the most abundant solid element in the Earth's lithosphere, is a useful material for spacecraft construction. Silicon is stronger than stainless steel, has a thermal conductivity about half that of aluminum, is transparent to much of the infrared radiation spectrum, and can form a stable oxide. These unique properties enable silicon to become most of the mass of a satellite, it can simultaneously function as structure, heat transfer system, radiation shield, optics, and semiconductor substrate. Semiconductor batch-fabrication techniques can produce low-power digital circuits, low-power analog circuits, silicon-based radio frequency circuits, and micro-electromechanical systems (MEMS) such as thrusters and acceleration sensors on silicon substrates. By exploiting these fabrication techniques, it is possible to produce highly-integrated satellites for a number of applications. This paper analyzes the limitations of silicon satellites due to size. Picosatellites (approximately 1 gram mass), nanosatellites (about 1 kg mass), and highly capable microsatellites (about 10 kg mass) can perform various missions with lifetimes of a few days to greater than a decade.

Large and pristine films of reduced graphene oxide

PubMed Central

Ahn, Sung Il; Kim, Kukjoo; Jung, Jura; Choi, Kyung Cheol

2015-01-01

A new self-assembly concept is introduced to form large and pristine films (15 cm in diameter) of reduced graphene oxide (RGO). The resulting film has different degrees of polarity on its two different sides due to the characteristic nature of the self-assembly process. The RGO film can be easily transferred from a glass substrate onto water and a polymer substrate after injection of water molecules between the RGO film and glass substrate using an electric steamer. The RGO film can also be easily patterned into various shapes with a resolution of around ±10 μm by a simple taping method, which is suitable for mass production of printed electronics at low cost. PMID:26689267

Ice-assisted transfer of carbon nanotube arrays.

PubMed

Wei, Haoming; Wei, Yang; Lin, Xiaoyang; Liu, Peng; Fan, Shoushan; Jiang, Kaili

2015-03-11

Decoupling the growth and the application of nanomaterials by transfer is an important issue in nanotechnology. Here, we developed an efficient transfer technique for carbon nanotube (CNT) arrays by using ice as a binder to temporarily bond the CNT array and the target substrate. Ice makes it an ultraclean transfer because the evaporation of ice ensures that no contaminants are introduced. The transferred superaligned carbon nanotube (SACNT) arrays not only keep their original appearance and initial alignment but also inherit their spinnability, which is the most desirable feature. The transfer-then-spin strategy can be employed to fabricate patterned CNT arrays, which can act as 3-dimensional electrodes in CNT thermoacoustic chips. Besides, the flip-chipped CNTs are promising field electron emitters. Furthermore, the ice-assisted transfer technique provides a cost-effective solution for mass production of SACNTs, giving CNT technologies a competitive edge, and this method may inspire new ways to transfer other nanomaterials.

Surface initiated atom transfer radical polymerization grafting of sodium styrene sulfonate from titanium and silicon substrates.

PubMed

Foster, Rami N; Keefe, Andrew J; Jiang, Shaoyi; Castner, David G

2013-11-01

This study investigates the grafting of poly-sodium styrene sulfonate (pNaSS) from trichlorosilane/10-undecen-1-yl 2-bromo-2-methylpropionate functionalized Si and Ti substrates by atom transfer radical polymerization (ATRP). The composition, molecular structure, thickness, and topography of the grafted pNaSS films were characterized with x-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), variable angle spectroscopic ellipsometry (VASE), and atomic force microscopy (AFM), respectively. XPS and ToF-SIMS results were consistent with the successful grafting of a thick and uniform pNaSS film on both substrates. VASE and AFM scratch tests showed the films were between 25 and 49 nm thick on Si, and between 13 and 35 nm thick on Ti. AFM determined root-mean-square roughness values were ∼2 nm on both Si and Ti substrates. Therefore, ATRP grafting is capable of producing relatively smooth, thick, and chemically homogeneous pNaSS films on Si and Ti substrates. These films will be used in subsequent studies to test the hypothesis that pNaSS-grafted Ti implants preferentially adsorb certain plasma proteins in an orientation and conformation that modulates the foreign body response and promotes formation of new bone.

Surface initiated atom transfer radical polymerization grafting of sodium styrene sulfonate from titanium and silicon substrates

PubMed Central

Foster, Rami N.; Keefe, Andrew J.; Jiang, Shaoyi; Castner, David G.

2013-01-01

This study investigates the grafting of poly-sodium styrene sulfonate (pNaSS) from trichlorosilane/10-undecen-1-yl 2-bromo-2-methylpropionate functionalized Si and Ti substrates by atom transfer radical polymerization (ATRP). The composition, molecular structure, thickness, and topography of the grafted pNaSS films were characterized with x-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), variable angle spectroscopic ellipsometry (VASE), and atomic force microscopy (AFM), respectively. XPS and ToF-SIMS results were consistent with the successful grafting of a thick and uniform pNaSS film on both substrates. VASE and AFM scratch tests showed the films were between 25 and 49 nm thick on Si, and between 13 and 35 nm thick on Ti. AFM determined root-mean-square roughness values were ∼2 nm on both Si and Ti substrates. Therefore, ATRP grafting is capable of producing relatively smooth, thick, and chemically homogeneous pNaSS films on Si and Ti substrates. These films will be used in subsequent studies to test the hypothesis that pNaSS-grafted Ti implants preferentially adsorb certain plasma proteins in an orientation and conformation that modulates the foreign body response and promotes formation of new bone. PMID:24482558

Cigarette Butt Decomposition and Associated Chemical Changes Assessed by 13C CPMAS NMR

PubMed Central

Bonanomi, Giuliano; Incerti, Guido; Cesarano, Gaspare; Gaglione, Salvatore A.; Lanzotti, Virginia

2015-01-01

Cigarette butts (CBs) are the most common type of litter on earth, with an estimated 4.5 trillion discarded annually. Apart from being unsightly, CBs pose a serious threat to living organisms and ecosystem health when discarded in the environment because they are toxic to microbes, insects, fish and mammals. In spite of the CB toxic hazard, no studies have addressed the effects of environmental conditions on CB decomposition rate. In this study we investigate the interactive effects of substrate fertility and N transfer dynamics on CB decomposition rate and carbon quality changes. We carried out an experiment using smoked CBs and wood sticks, used as a slow decomposing standard organic substrate, incubated in both laboratory and field conditions for two years. CB carbon quality changes during decomposition was assessed by 13C CPMAS NMR. Our experiment confirmed the low degradation rate of CBs which, on average, lost only 37.8% of their initial mass after two years of decomposition. Although a net N transfer occurred from soil to CBs, contrary to our hypothesis, mass loss in the medium-term (two years) was unaffected by N availability in the surrounding substrate. The opposite held for wood sticks, in agreement with the model that N-rich substrates promote the decomposition of other N-poor natural organic materials with a high C/N ratio. As regards CB chemical quality, after two years of decomposition 13C NMR spectroscopy highlighted very small changes in C quality that are likely to reflect a limited microbial attack. PMID:25625643

A continuous flow microfluidic calorimeter: 3-D numerical modeling with aqueous reactants.

PubMed

Sen, Mehmet A; Kowalski, Gregory J; Fiering, Jason; Larson, Dale

2015-03-10

A computational analysis of the reacting flow field, species diffusion and heat transfer processes with thermal boundary layer effects in a microchannel reactor with a coflow configuration was performed. Two parallel adjacent streams of aqueous reactants flow along a wide, shallow, enclosed channel in contact with a substrate, which is affixed to a temperature controlled plate. The Fluent computational fluid dynamics package solved the Navier-Stokes, mass transport and energy equations. The energy model, including the enthalpy of reaction as a nonuniform heat source, was validated by calculating the energy balance at several control volumes in the microchannel. Analysis reveals that the temperature is nearly uniform across the channel thickness, in the direction normal to the substrate surface; hence, measurements made by sensors at or near the surface are representative of the average temperature. Additionally, modeling the channel with a glass substrate and a silicone cover shows that heat transfer is predominantly due to the glass substrate. Finally, using the numerical results, we suggest that a microcalorimeter could be based on this configuration, and that temperature sensors such as optical nanohole array sensors could have sufficient spatial resolution to determine enthalpy of reaction.

A continuous flow microfluidic calorimeter: 3-D numerical modeling with aqueous reactants

PubMed Central

Sen, Mehmet A.; Kowalski, Gregory J.; Fiering, Jason; Larson, Dale

2015-01-01

A computational analysis of the reacting flow field, species diffusion and heat transfer processes with thermal boundary layer effects in a microchannel reactor with a coflow configuration was performed. Two parallel adjacent streams of aqueous reactants flow along a wide, shallow, enclosed channel in contact with a substrate, which is affixed to a temperature controlled plate. The Fluent computational fluid dynamics package solved the Navier–Stokes, mass transport and energy equations. The energy model, including the enthalpy of reaction as a nonuniform heat source, was validated by calculating the energy balance at several control volumes in the microchannel. Analysis reveals that the temperature is nearly uniform across the channel thickness, in the direction normal to the substrate surface; hence, measurements made by sensors at or near the surface are representative of the average temperature. Additionally, modeling the channel with a glass substrate and a silicone cover shows that heat transfer is predominantly due to the glass substrate. Finally, using the numerical results, we suggest that a microcalorimeter could be based on this configuration, and that temperature sensors such as optical nanohole array sensors could have sufficient spatial resolution to determine enthalpy of reaction. PMID:25937678

Numerical simulation of the alloying process during impulse induction heating of the metal substrate

NASA Astrophysics Data System (ADS)

Popov, V. N.

2017-10-01

2D numerical modeling of the processes during the alloying of the substrate surface metal layer is carried out. Heating, phase transition, heat and mass transfer in the molten metal, solidification of the melt are considered with the aid the proposed mathematical model. Under study is the applicability of the high-frequency electromagnetic field impulse for metal heating and melting. The distribution of the electromagnetic energy in the metal is described by empirical formulas. According to the results of numerical experiments, the flow structure in the melt and distribution of the alloying substances is evaluated.

Use of Glass Reinforced Concrete (GRC) as a substrate for photovoltaic modules

NASA Technical Reports Server (NTRS)

Eirls, J. L.

1980-01-01

A substrate for flat plate photovoltaic solar panel arrays using a glass fiber reinforced concrete (GRC) material was developed. The installed cost of this GRC panel is 30% less than the cost goal of the Near Term Low-Cost Flat Plate Photovoltaic Solar Array Program. The 4 ft by 8 ft panel is fabricated from readily available inexpensive materials, weighs a nominal 190 lbs., has exceptionally good strength and durability properties (rigid and resists weathering), is amenable to mass production and is easily installed on simple mountings. Solar cells are encapsulated in ethylene/vinyl acetate with Tedlar backing and Korad cover film. The laminates are attached to the GRC substrate with acrylic transfer tape and edge sealed with silicone RTV adhesive.

Mass spectrometric real-time monitoring of an enzymatic phosphorylation assay using internal standards and data-handling freeware.

PubMed

Krappmann, Michael; de Boer, Arjen R; Kool, Daniël R W; Irth, Hubertus; Letzel, Thomas

2016-04-30

Continuous-flow reaction detection systems (monitoring enzymatic reactions with mass spectrometry (MS)) lack quantitative values so far. Therefore, two independent internal standards (IS) are implemented in a way that the online system stability can be observed, quantitative conversion values for substrate and product can be obtained and they can be used as mass calibration standards for high MS accuracy. An application previously developed for the MS detection of peptide phosphorylation by cAMP-dependent protein kinase A (PKA) (De Boer et al., Anal. Bioanal. Chem. 2005, 381, 647-655) was transferred to a continuous-flow reaction detection system. This enzymatic reaction, involving enzyme activation as well as the transfer of a phosphate group from ATP to a peptide substrate, was used to prove the compatibility of a quantitative enzymatic assay in a continuous-flow real-time system (connected to MS). Moreover (using internal standards), the critical parameter reaction temperature (including solution density variations depending on temperature) was studied in the continuous-flow mixing system. Furthermore, two substrates (malantide and kemptide), two enzyme types (catalytic subunit of PKA and complete PKA) and one inhibitor were tested to determine system robustness and long-term availability. Even spraying solutions that contained significant amount of MS contaminants (e.g. the polluted catalytic subunit) resulted in quantifiable MS signal intensities. Subsequent recalculations using the internal standards led to results representing the power of this application. The presented methodology and the data evaluation with available Achroma freeware enable the direct coupling of biochemical assays with quantitative MS detection. Monitoring changes such as temperature, reaction time, inhibition, or compound concentrations can be observed quantitatively and thus enzymatic activity can be calculated. Copyright © 2016 John Wiley & Sons, Ltd.

Hydrodynamic fabrication of structurally gradient ZnO nanorods.

PubMed

Kim, Hyung Min; Youn, Jae Ryoun; Song, Young Seok

2016-02-26

We studied a new approach where structurally gradient nanostructures were fabricated by means of hydrodynamics. Zinc oxide (ZnO) nanorods were synthesized in a drag-driven rotational flow in a controlled manner. The structural characteristics of nanorods such as orientation and diameter were determined by momentum and mass transfer at the substrate surface. The nucleation of ZnO was induced by shear stress which plays a key role in determining the orientation of ZnO nanorods. The nucleation and growth of such nanostructures were modeled theoretically and analyzed numerically to understand the underlying physics of the fabrication of nanostructures controlled by hydrodynamics. The findings demonstrated that the precise control of momentum and mass transfer enabled the formation of ZnO nanorods with a structural gradient in diameter and orientation.

Transfer of monolayer TMD WS2 and Raman study of substrate effects

PubMed Central

Mlack, Jerome T.; Masih Das, Paul; Danda, Gopinath; Chou, Yung-Chien; Naylor, Carl H.; Lin, Zhong; López, Néstor Perea; Zhang, Tianyi; Terrones, Mauricio; Johnson, A. T. Charlie; Drndić, Marija

2017-01-01

A facile transfer process for transition metal dichalcogenide WS2 flakes is reported and the effect of the underlying substrate on the flake properties is investigated using Raman spectroscopy. The flakes are transferred from their growth substrate using polymethyl methacrylate (PMMA) and a wet etch to allow the user to transfer the flakes to a final substrate using a microscope and micromanipulator combined with semi-transparent Kapton tape. The substrates used range from insulators such as industry standard high-k dielectric HfO2 and “green polymer” parylene-C, to conducting chemical vapor deposition (CVD) grown graphene. Raman spectroscopy is used first to confirm the material quality of the transferred flakes to the substrates and subsequently to analyze and separate the effects arising from material transfer from those arising from interactions with the substrate. We observe changes in the Raman spectra associated with the interactions between the substrates in the flakes. These interactions affect both in-plane and out-of-plane modes in different ways depending on their sources, for example strain or surface charge. These changes vary with final substrate, with the strongest effects being observed for WS2 transferred onto graphene and HfO2, demonstrating the importance of understanding substrate interaction for fabrication of future devices. PMID:28220852

Film transfer enabled by nanosheet seed layers on arbitrary sacrificial substrates

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

Dral, A. P.; Nijland, M.; Koster, G.

An approach for film transfer is demonstrated that makes use of seed layers of nanosheets on arbitrary sacrificial substrates. Epitaxial SrTiO{sub 3}, SrRuO{sub 3}, and BiFeO{sub 3} films were grown on Ca{sub 2}Nb{sub 3}O{sub 10} nanosheet seed layers on phlogopite mica substrates. Cleavage of the mica substrates enabled film transfer to flexible polyethylene terephthalate substrates. Electron backscatter diffraction, X-ray diffraction, and atomic force microscopy confirmed that crystal orientation and film morphology remained intact during transfer. The generic nature of this approach is illustrated by growing films on zinc oxide substrates with a nanosheet seed layer. Film transfer to a flexiblemore » substrate was accomplished via acid etching.« less

Direct transfer of graphene onto flexible substrates.

PubMed

Martins, Luiz G P; Song, Yi; Zeng, Tingying; Dresselhaus, Mildred S; Kong, Jing; Araujo, Paulo T

2013-10-29

In this paper we explore the direct transfer via lamination of chemical vapor deposition graphene onto different flexible substrates. The transfer method investigated here is fast, simple, and does not require an intermediate transfer membrane, such as polymethylmethacrylate, which needs to be removed afterward. Various substrates of general interest in research and industry were studied in this work, including polytetrafluoroethylene filter membranes, PVC, cellulose nitrate/cellulose acetate filter membranes, polycarbonate, paraffin, polyethylene terephthalate, paper, and cloth. By comparing the properties of these substrates, two critical factors to ensure a successful transfer on bare substrates were identified: the substrate's hydrophobicity and good contact between the substrate and graphene. For substrates that do not satisfy those requirements, polymethylmethacrylate can be used as a surface modifier or glue to ensure successful transfer. Our results can be applied to facilitate current processes and open up directions for applications of chemical vapor deposition graphene on flexible substrates. A broad range of applications can be envisioned, including fabrication of graphene devices for opto/organic electronics, graphene membranes for gas/liquid separation, and ubiquitous electronics with graphene.

Fluid Mechanics and Heat Transfer of Liquid Precursor Droplets Injected into High-Temperature Plasmas

NASA Astrophysics Data System (ADS)

Basu, Saptarshi; Jordan, Eric H.; Cetegen, Baki M.

2008-03-01

Thermo-physical processes in liquid ceramic precursor droplets in plasma were modeled. Models include aerodynamic droplet break-up, droplet transport, as well as heat and mass transfer within individual droplets. Droplet size, solute concentration, and plasma temperature effects are studied. Results are discussed with the perspective of selecting processing conditions and injection parameters to obtain certain types of coating microstructures. Small droplets (<5 microns) are found to undergo volumetric precipitation and coating deposition with small unpyrolized material. Droplets can be made to undergo shear break-up by reducing surface tension and small droplets promote volumetric precipitation. Small particles reach substrate as molten splats resulting in denser coatings. Model predicts that larger droplets (>5 microns) tend to surface precipitate-forming shells with liquid core. They may be subjected to internal pressurization leading to shattering of shells and secondary atomization of liquid within. They arrive at the substrate as broken shells and unpyrolized material.

Operational parameters and their influence on particle-side mass transfer resistance in a packed bed bioreactor.

PubMed

Hussain, Amir; Kangwa, Martin; Yumnam, Nivedita; Fernandez-Lahore, Marcelo

2015-12-01

The influence of internal mass transfer on productivity as well as the performance of packed bed bioreactor was determined by varying a number of parameters; chitosan coating, flow rate, glucose concentration and particle size. Saccharomyces cerevisiae cells were immobilized in chitosan and non-chitosan coated alginate beads to demonstrate the effect on particle side mass transfer on substrate consumption time, lag phase and ethanol production. The results indicate that chitosan coating, beads size, glucose concentration and flow rate have a significant effect on lag phase duration. The duration of lag phase for different size of beads (0.8, 2 and 4 mm) decreases by increasing flow rate and by decreasing the size of beads. Moreover, longer lag phase were found at higher glucose medium concentration and also with chitosan coated beads. It was observed that by increasing flow rates; lag phase and glucose consumption time decreased. The reason is due to the reduction of external (fluid side) mass transfer as a result of increase in flow rate as glucose is easily transported to the surface of the beads. Varying the size of beads is an additional factor: as it reduces the internal (particle side) mass transfer by reducing the size of beads. The reason behind this is the distance for reactants to reach active site of catalyst (cells) and the thickness of fluid created layer around alginate beads is reduced. The optimum combination of parameters consisting of smaller beads size (0.8 mm), higher flow rate of 90 ml/min and glucose concentration of 10 g/l were found to be the maximum condition for ethanol production.

Enzymatic synthesis of farnesyl laurate in organic solvent: initial water activity, kinetics mechanism, optimization of continuous operation using packed bed reactor and mass transfer studies.

PubMed

Rahman, N K; Kamaruddin, A H; Uzir, M H

2011-08-01

The influence of water activity and water content was investigated with farnesyl laurate synthesis catalyzed by Lipozyme RM IM. Lipozyme RM IM activity depended strongly on initial water activity value. The best results were achieved for a reaction medium with an initial water activity of 0.11 since it gives the best conversion value of 96.80%. The rate constants obtained in the kinetics study using Ping-Pong-Bi-Bi and Ordered-Bi-Bi mechanisms with dead-end complex inhibition of lauric acid were compared. The corresponding parameters were found to obey the Ordered-Bi-Bi mechanism with dead-end complex inhibition of lauric acid. Kinetic parameters were calculated based on this model as follows: V (max) = 5.80 mmol l(-1) min(-1) g enzyme(-1), K (m,A) = 0.70 mmol l(-1) g enzyme(-1), K (m,B) = 115.48 mmol l(-1) g enzyme(-1), K (i) = 11.25 mmol l(-1) g enzyme(-1). The optimum conditions for the esterification of farnesol with lauric acid in a continuous packed bed reactor were found as the following: 18.18 cm packed bed height and 0.9 ml/min substrate flow rate. The optimum molar conversion of lauric acid to farnesyl laurate was 98.07 ± 0.82%. The effect of mass transfer in the packed bed reactor has also been studied using two models for cases of reaction limited and mass transfer limited. A very good agreement between the mass transfer limited model and the experimental data obtained indicating that the esterification in a packed bed reactor was mass transfer limited.

Method of transferring strained semiconductor structure

DOEpatents

Nastasi, Michael A [Santa Fe, NM; Shao, Lin [College Station, TX

2009-12-29

The transfer of strained semiconductor layers from one substrate to another substrate involves depositing a multilayer structure on a substrate having surface contaminants. An interface that includes the contaminants is formed in between the deposited layer and the substrate. Hydrogen atoms are introduced into the structure and allowed to diffuse to the interface. Afterward, the deposited multilayer structure is bonded to a second substrate and is separated away at the interface, which results in transferring a multilayer structure from one substrate to the other substrate. The multilayer structure includes at least one strained semiconductor layer and at least one strain-induced seed layer. The strain-induced seed layer can be optionally etched away after the layer transfer.

Direct transfer of graphene onto flexible substrates

PubMed Central

Martins, Luiz G. P.; Song, Yi; Zeng, Tingying; Dresselhaus, Mildred S.; Kong, Jing; Araujo, Paulo T.

2013-01-01

In this paper we explore the direct transfer via lamination of chemical vapor deposition graphene onto different flexible substrates. The transfer method investigated here is fast, simple, and does not require an intermediate transfer membrane, such as polymethylmethacrylate, which needs to be removed afterward. Various substrates of general interest in research and industry were studied in this work, including polytetrafluoroethylene filter membranes, PVC, cellulose nitrate/cellulose acetate filter membranes, polycarbonate, paraffin, polyethylene terephthalate, paper, and cloth. By comparing the properties of these substrates, two critical factors to ensure a successful transfer on bare substrates were identified: the substrate’s hydrophobicity and good contact between the substrate and graphene. For substrates that do not satisfy those requirements, polymethylmethacrylate can be used as a surface modifier or glue to ensure successful transfer. Our results can be applied to facilitate current processes and open up directions for applications of chemical vapor deposition graphene on flexible substrates. A broad range of applications can be envisioned, including fabrication of graphene devices for opto/organic electronics, graphene membranes for gas/liquid separation, and ubiquitous electronics with graphene. PMID:24127582

Carbon flux to growth or polyhydroxyalkanoate synthesis under microaerophilic conditions is affected by fatty acid chain-length in Pseudomonas putida LS46.

PubMed

Blunt, Warren; Dartiailh, Christopher; Sparling, Richard; Gapes, Daniel; Levin, David B; Cicek, Nazim

2018-05-24

Economical production of medium-chain length polyhydroxyalkanoates (mcl-PHA) is dependent on efficient cultivation processes. This work describes growth and mcl-PHA synthesis characteristics of Pseudomonas putida LS46 when grown on medium-chain length fatty acids (octanoic acid) and lower-cost long-chain fatty acids (LCFAs, derived from hydrolyzed canola oil) in microaerophilic environments. Growth on octanoic acid ceased when the oxygen uptake rate was limited by the oxygen transfer rate, and mcl-PHA accumulated to 61.9% of the cell dry mass. From LCFAs, production of non-PHA cell mass continued at a rate of 0.36 g L -1  h -1 under oxygen-limited conditions, while mcl-PHA accumulated simultaneously to 31% of the cell dry mass. The titer of non-PHA cell mass from LCFAs at 14 h post-inoculation was double that obtained from octanoic acid in bioreactors operated with identical feeding and aeration conditions. While the productivity for octanoic acid was higher by 14 h, prolonged cultivation on LCFAs achieved similar productivity but with twice the PHA titer. Simultaneous co-feeding of each substrate demonstrated the continued cell growth under microaerophilic conditions characteristic of LCFAs, and the resulting polymer was dominant in C8 monomers. Furthermore, co-feeding resulted in improved PHA titer and volumetric productivity compared to either substrate individually. These results suggest that LCFAs improve growth of P. putida in oxygen-limited environments and could reduce production costs since more non-PHA cell mass, the cellular factories required to produce mcl-PHA and the most oxygen-intensive cellular process, can be produced for a given oxygen transfer rate.

Synthesis of Graphene Based Membranes: Effect of Substrate Surface Properties on Monolayer Graphene Transfer.

PubMed

Kafiah, Feras; Khan, Zafarullah; Ibrahim, Ahmed; Atieh, Muataz; Laoui, Tahar

2017-01-21

In this work, we report the transfer of graphene onto eight commercial microfiltration substrates having different pore sizes and surface characteristics. Monolayer graphene grown on copper by the chemical vapor deposition (CVD) process was transferred by the pressing method over the target substrates, followed by wet etching of copper to obtain monolayer graphene/polymer membranes. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle (CA) measurements were carried out to explore the graphene layer transferability. Three factors, namely, the substrate roughness, its pore size, and its surface wetting (degree of hydrophobicity) are found to affect the conformality and coverage of the transferred graphene monolayer on the substrate surface. A good quality graphene transfer is achieved on the substrate with the following characteristics; being hydrophobic (CA > 90°), having small pore size, and low surface roughness, with a CA to RMS (root mean square) ratio higher than 2.7°/nm.

Methods of making membrane electrode assemblies

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

Kim, Yu Seung; Lee, Kwan -Soo; Rockward, Tommy Q. T.

Method of making a membrane electrode assembly comprising: providing a membrane comprising a perfluorinated sulfonic acid; providing a first transfer substrate; applying to a surface of the first transfer substrate a first ink, said first ink comprising an ionomer and a catalyst; applying to the first ink a suitable non-aqueous swelling agent; forming an assembly comprising: the membrane; and the first transfer substrate, wherein the surface of the first transfer substrate comprising the first ink and the non-aqueous swelling agent is disposed upon one surface of the membrane; and heating the assembly at a temperature of 150.degree. C. or lessmore » and at a pressure of from about 250 kPa to about 3000 kPa or less for a time suitable to allow substantially complete transfer of the first ink and the second ink to the membrane; and cooling the assembly to room temperature and removing the first transfer substrate and the second transfer substrate.« less

Method of transferring a thin crystalline semiconductor layer

DOEpatents

Nastasi, Michael A [Sante Fe, NM; Shao, Lin [Los Alamos, NM; Theodore, N David [Mesa, AZ

2006-12-26

A method for transferring a thin semiconductor layer from one substrate to another substrate involves depositing a thin epitaxial monocrystalline semiconductor layer on a substrate having surface contaminants. An interface that includes the contaminants is formed in between the deposited layer and the substrate. Hydrogen atoms are introduced into the structure and allowed to diffuse to the interface. Afterward, the thin semiconductor layer is bonded to a second substrate and the thin layer is separated away at the interface, which results in transferring the thin epitaxial semiconductor layer from one substrate to the other substrate.

Fabricating nanowire devices on diverse substrates by simple transfer-printing methods.

PubMed

Lee, Chi Hwan; Kim, Dong Rip; Zheng, Xiaolin

2010-06-01

The fabrication of nanowire (NW) devices on diverse substrates is necessary for applications such as flexible electronics, conformable sensors, and transparent solar cells. Although NWs have been fabricated on plastic and glass by lithographic methods, the choice of device substrates is severely limited by the lithographic process temperature and substrate properties. Here we report three new transfer-printing methods for fabricating NW devices on diverse substrates including polydimethylsiloxane, Petri dishes, Kapton tapes, thermal release tapes, and many types of adhesive tapes. These transfer-printing methods rely on the differences in adhesion to transfer NWs, metal films, and devices from weakly adhesive donor substrates to more strongly adhesive receiver substrates. Electrical characterization of fabricated NW devices shows that reliable ohmic contacts are formed between NWs and electrodes. Moreover, we demonstrated that Si NW devices fabricated by the transfer-printing methods are robust piezoresistive stress sensors and temperature sensors with reliable performance.

Three-dimensional three-phase model for simulation of hydrodynamics, oxygen mass transfer, carbon oxidation, nitrification and denitrification in an oxidation ditch.

PubMed

Lei, Li; Ni, Jinren

2014-04-15

A three-dimensional three-phase fluid model, supplemented by laboratory data, was developed to simulate the hydrodynamics, oxygen mass transfer, carbon oxidation, nitrification and denitrification processes in an oxidation ditch. The model provided detailed phase information on the liquid flow field, gas hold-up distribution and sludge sedimentation. The three-phase model described water-gas, water-sludge and gas-sludge interactions. Activated sludge was taken to be in a pseudo-solid phase, comprising an initially separated solid phase that was transported and later underwent biological reactions with the surrounding liquidmedia. Floc parameters were modified to improve the sludge viscosity, sludge density, oxygen mass transfer rate, and carbon substrate uptake due to adsorption onto the activated sludge. The validation test results were in very satisfactory agreement with laboratory data on the behavior of activated sludge in an oxidation ditch. By coupling species transport and biological process models, reasonable predictions are made of: (1) the biochemical kinetics of dissolved oxygen, chemical oxygen demand (COD) and nitrogen variation, and (2) the physical kinematics of sludge sedimentation. Copyright © 2014 Elsevier Ltd. All rights reserved.

A High-yield Two-step Transfer Printing Method for Large-scale Fabrication of Organic Single-crystal Devices on Arbitrary Substrates

PubMed Central

Deng, Wei; Zhang, Xiujuan; Pan, Huanhuan; Shang, Qixun; Wang, Jincheng; Zhang, Xiaohong; Zhang, Xiwei; Jie, Jiansheng

2014-01-01

Single-crystal organic nanostructures show promising applications in flexible and stretchable electronics, while their applications are impeded by the large incompatibility with the well-developed photolithography techniques. Here we report a novel two-step transfer printing (TTP) method for the construction of organic nanowires (NWs) based devices onto arbitrary substrates. Copper phthalocyanine (CuPc) NWs are first transfer-printed from the growth substrate to the desired receiver substrate by contact-printing (CP) method, and then electrode arrays are transfer-printed onto the resulting receiver substrate by etching-assisted transfer printing (ETP) method. By utilizing a thin copper (Cu) layer as sacrificial layer, microelectrodes fabricated on it via photolithography could be readily transferred to diverse conventional or non-conventional substrates that are not easily accessible before with a high transfer yield of near 100%. The ETP method also exhibits an extremely high flexibility; various electrodes such as Au, Ti, and Al etc. can be transferred, and almost all types of organic devices, such as resistors, Schottky diodes, and field-effect transistors (FETs), can be constructed on planar or complex curvilinear substrates. Significantly, these devices can function properly and exhibit closed or even superior performance than the device counterparts fabricated by conventional approach. PMID:24942458

Influence of soil-water ratio on the performance of slurry phase bioreactor treating herbicide contaminated soil.

PubMed

Venkata Mohan, S; Ramakrishna, M; Shailaja, S; Sarma, P N

2007-09-01

The influence of soil-water ratio was studied on the performance of the slurry phase bioreactor operated in sequencing batch mode (anoxic-aerobic-anoxic microenvironments) during the bioremediation of soil contaminated with pendimethalin. The performance of the reactors was evaluated at different soil-water ratios (1:5-1:25; at soil loading rate (60 kg of soil/cum-day to 12 kg of soil/cum-day)) keeping the loading rate of pendimethalin constant (133.2 g/kg of soil-day) in six reactors and variable (66.6 g/kg of soil-day to 166.6 g/kg of soil-day) in other four reactors. At 1:20 soil-water ratio, the slurry phase system showed enhanced degradation of substrate (629 microg pendimethalin/g soil). The removal efficiency of pendimethalin in the reactors was dependent on the mass-transfer rates of the substrate from the soil to the aqueous phase. Soil-water ratio and substrate loading rates showed significant influence on the substrate portioning, substrate degradation efficiency and substrate desorption rate.

The effect of gas double-dynamic on mass distribution in solid-state fermentation.

PubMed

Chen, Hong-Zhang; Zhao, Zhi-Min; Li, Hong-Qiang

2014-05-10

The mass distribution regularity in substrate of solid-state fermentation (SSF) has rarely been reported due to the heterogeneity of solid medium and the lack of suitable instrument and method, which limited the comprehensive analysis and enhancement of the SSF performance. In this work, the distributions of water, biomass, and fermentation product in different medium depths of SSF were determined using near-infrared spectroscopy (NIRS) and the developed models. Based on the mass distribution regularity, the effects of gas double-dynamic on heat transfer, microbial growth and metabolism, and product distribution gradient were systematically investigated. Results indicated that the maximum temperature of substrate and the maximum carbon dioxide evolution rate (CER) were 39.5°C and 2.48mg/(hg) under static aeration solid-state fermentation (SASSF) and 33.9°C and 5.38mg/(hg) under gas double-dynamic solid-state fermentation (GDSSF), respectively, with the environmental temperature for fermentation of 30±1°C. The fermentation production (cellulase activity) ratios of the upper, middle, and lower levels were 1:0.90:0.78 at seventh day under SASSF and 1:0.95:0.89 at fifth day under GDSSF. Therefore, combined with NIRS analysis, gas double-dynamic could effectively strengthen the solid-state fermentation performance due to the enhancement of heat transfer, the stimulation of microbial metabolism and the increase of the homogeneity of fermentation products. Copyright © 2014 Elsevier Inc. All rights reserved.

Conjugate heat transfer investigation on the cooling performance of air cooled turbine blade with thermal barrier coating

NASA Astrophysics Data System (ADS)

Ji, Yongbin; Ma, Chao; Ge, Bing; Zang, Shusheng

2016-08-01

A hot wind tunnel of annular cascade test rig is established for measuring temperature distribution on a real gas turbine blade surface with infrared camera. Besides, conjugate heat transfer numerical simulation is performed to obtain cooling efficiency distribution on both blade substrate surface and coating surface for comparison. The effect of thermal barrier coating on the overall cooling performance for blades is compared under varied mass flow rate of coolant, and spatial difference is also discussed. Results indicate that the cooling efficiency in the leading edge and trailing edge areas of the blade is the lowest. The cooling performance is not only influenced by the internal cooling structures layout inside the blade but also by the flow condition of the mainstream in the external cascade path. Thermal barrier effects of the coating vary at different regions of the blade surface, where higher internal cooling performance exists, more effective the thermal barrier will be, which means the thermal protection effect of coatings is remarkable in these regions. At the designed mass flow ratio condition, the cooling efficiency on the pressure side varies by 0.13 for the coating surface and substrate surface, while this value is 0.09 on the suction side.

Adhesion and transfer of PTFE to metals studied by auger emission spectroscopy

NASA Technical Reports Server (NTRS)

Pepper, S. V.; Buckley, D. H.

1972-01-01

The adhesion and transfer of polytetrafluoroethylene (PTFE) to metals in ultrahigh vacuum has been studied using Auger emission spectroscopy. The transfer was effected both by compressive static contact and by sliding contact. The transfer observed after static contact was independent of the chemical constitution of the substrate. Electron induced desorption of the fluorine in the transferred PTFE showed that the fluorine had no chemical interaction with the metal substrate. The coefficient of friction on metals was independent of the chemical constitution of the substrate. However, sliding PTFE on soft metals such as aluminum, generated wear fragments that lodged in the PTFE and machined the substrate.

Adhesion and transfer of polytetrafluorethylene to metals studied by Auger emission spectroscopy

NASA Technical Reports Server (NTRS)

Pepper, S. V.; Buckley, D. H.

1972-01-01

The adhesion and transfer of polytetrafluoroethylene (PTFE) to metals in ultrahigh vacuum were studied. The transfer was effected both by compressive static contact and by sliding contact. The transfer observed after static contact was independent of the chemical constitution of the substrate. Electron-induced desorption of the fluorine in the transferred PTFE showed that the fluorine had no chemical interaction with the metal substrate. The coefficient of friction on metals was independent of the chemical constitution of the substrate. However, sliding PTFE on soft metals, such as aluminum, generated wear fragments that lodged in the PTFE and machined the substrate.

A laser induced local transfer for patterning of RGB-OLED-displays

NASA Astrophysics Data System (ADS)

Kroeger, Michael; Hueske, Marc; Dobbertin, Thomas; Meyer, Jens; Krautwald, Henning; Riedl, Thomas; Johannes, Hans-Hermann; Kowalsky, Wolfgang

2005-07-01

RGB-OLED-displays can be realized by at least three different approaches: Color from white, color from blue or patterning of red, green and blue OLEDs, which is favorable for reasons of higher efficiency and lower costs. Common patterning techniques like photolithography cannot be applied due to the degradation of the OLEDs after the exposure to solvents. Shadow masking which is currently widely applied is not applicable for bigger substrate sizes of future mass production tools. Therefore a novel approach for patterning of organic semiconductors will be demonstrated. The laser induced local transfer (LILT) of organic small molecule materials allows for mass production of high resolution RGB-OLED-displays. An infrared absorbing target is coated with the desired emitting material, which is placed in a short distance in front of an OLED substrate. A scanner deflects and focuses an infrared laser beam onto the target. By adjusting scanning speed and laser power accurately the target locally heats up to a temperature where the organic material sublimes and will be deposited on the opposite OLED substrate. By repeating this for red, green and blue emitting materials a RGB-OLED-display can be realized. For process evaluation and development a LILT-module has been built, incorporating two custom vacuum chambers, several lift and transfer stages, a high-speed high-precision scanner and an infrared continuous-wave laser (cw). This module is designed to be part of a future inline deposition system for full-color OLED displays. In the first experiments it could be observed, that the pattern resolution is strongly dependent on the scanning speed, exhibiting minimum feature sizes of 40μm. It can be deducted that this is due to the laser's beam profile (TEM00), which allows for the smallest focus possible, but may not allow for rugged process conditions suitable for production. Rectangular steep-edged beam profiles may overcome this problem.

Transfer and alignment of random single-walled carbon nanotube films by contact printing.

PubMed

Liu, Huaping; Takagi, Daisuke; Chiashi, Shohei; Homma, Yoshikazu

2010-02-23

We present a simple method to transfer large-area random single-walled carbon nanotube (SWCNT) films grown on SiO(2) substrates onto another surface through a simple contact printing process. The transferred random SWCNT films can be assembled into highly ordered, dense regular arrays with high uniformity and reproducibility by sliding the growth substrate during the transfer process. The position of the transferred SWCNT film can be controlled by predefined patterns on the receiver substrates. The process is compatible with a variety of substrates, and even metal meshes for transmission electron microscopy (TEM) can be used as receiver substrates. Thus, suspended web-like SWCNT networks and aligned SWCNT arrays can be formed over the grids of TEM meshes, so that the structures of the transferred SWCNTs can be directly observed by TEM. This simple technique can be used to controllably transfer SWCNTs for property studies, for the fabrication of devices, or even as support films for TEM meshes.

Modeling and CFD simulation of nutrient distribution in picoliter bioreactors for bacterial growth studies on single-cell level.

PubMed

Westerwalbesloh, Christoph; Grünberger, Alexander; Stute, Birgit; Weber, Sophie; Wiechert, Wolfgang; Kohlheyer, Dietrich; von Lieres, Eric

2015-11-07

A microfluidic device for microbial single-cell cultivation of bacteria was modeled and simulated using COMSOL Multiphysics. The liquid velocity field and the mass transfer within the supply channels and cultivation chambers were calculated to gain insight in the distribution of supplied nutrients and metabolic products secreted by the cultivated bacteria. The goal was to identify potential substrate limitations or product accumulations within the cultivation device. The metabolic uptake and production rates, colony size, and growth medium composition were varied covering a wide range of operating conditions. Simulations with glucose as substrate did not show limitations within the typically used concentration range, but for alternative substrates limitations could not be ruled out. This lays the foundation for further studies and the optimization of existing picoliter bioreactor systems.

An investigation of the DC and RF performance of InP DHBTs transferred to RF CMOS wafer substrate

NASA Astrophysics Data System (ADS)

Ren, Kun; Zheng, Jiachen; Lu, Haiyan; Liu, Jun; Wu, Lishu; Zhou, Wenyong; Cheng, Wei

2018-05-01

This paper investigated the DC and RF performance of the InP double heterojunction bipolar transistors (DHBTs) transferred to RF CMOS wafer substrate. The measurement results show that the maximum values of the DC current gain of a substrate transferred device had one emitter finger, of 0.8 μm in width and 5 μm in length, are changed unobviously, while the cut-off frequency and the maximum oscillation frequency are decreased from 220 to 171 GHz and from 204 to 154 GHz, respectively. In order to have a detailed insight on the degradation of the RF performance, small-signal models for the InP DHBT before and after substrate transferred are presented and comparably extracted. The extracted results show that the degradation of the RF performance of the device transferred to RF CMOS wafer substrate are mainly caused by the additional introduced substrate parasitics and the increase of the capacitive parasitics induced by the substrate transfer process itself. Project supported by the National Natural Science Foundation of China (No. 61331006) and the Natural Science Foundation of Zhejiang Province (No. Y14F010017).

Ordered macroporous platinum electrode and enhanced mass transfer in fuel cells using inverse opal structure.

PubMed

Kim, Ok-Hee; Cho, Yong-Hun; Kang, Soon Hyung; Park, Hee-Young; Kim, Minhyoung; Lim, Ju Wan; Chung, Dong Young; Lee, Myeong Jae; Choe, Heeman; Sung, Yung-Eun

2013-01-01

Three-dimensional, ordered macroporous materials such as inverse opal structures are attractive materials for various applications in electrochemical devices because of the benefits derived from their periodic structures: relatively large surface areas, large voidage, low tortuosity and interconnected macropores. However, a direct application of an inverse opal structure in membrane electrode assemblies has been considered impractical because of the limitations in fabrication routes including an unsuitable substrate. Here we report the demonstration of a single cell that maintains an inverse opal structure entirely within a membrane electrode assembly. Compared with the conventional catalyst slurry, an ink-based assembly, this modified assembly has a robust and integrated configuration of catalyst layers; therefore, the loss of catalyst particles can be minimized. Furthermore, the inverse-opal-structure electrode maintains an effective porosity, an enhanced performance, as well as an improved mass transfer and more effective water management, owing to its morphological advantages.

Ceramic membrane microfilter as an immobilized enzyme reactor.

PubMed

Harrington, T J; Gainer, J L; Kirwan, D J

1992-10-01

This study investigated the use of a ceramic microfilter as an immobilized enzyme reactor. In this type of reactor, the substrate solution permeates the ceramic membrane and reacts with an enzyme that has been immobilized within its porous interior. The objective of this study was to examine the effect of permeation rate on the observed kinetic parameters for the immobilized enzyme in order to assess possible mass transfer influences or shear effects. Kinetic parameters were found to be independent of flow rate for immobilized penicillinase and lactate dehydrogenase. Therefore, neither mass transfer nor shear effects were observed for enzymes immobilized within the ceramic membrane. Both the residence time and the conversion in the microfilter reactor could be controlled simply by regulating the transmembrane pressure drop. This study suggests that a ceramic microfilter reactor can be a desirable alternative to a packed bed of porous particles, especially when an immobilized enzyme has high activity and a low Michaelis constant.

Formation of Au nano-patterns on various substrates using simplified nano-transfer printing method

NASA Astrophysics Data System (ADS)

Kim, Jong-Woo; Yang, Ki-Yeon; Hong, Sung-Hoon; Lee, Heon

2008-06-01

For future device applications, fabrication of the metal nano-patterns on various substrates, such as Si wafer, non-planar glass lens and flexible plastic films become important. Among various nano-patterning technologies, nano-transfer print method is one of the simplest techniques to fabricate metal nano-patterns. In nano-transfer printing process, thin Au layer is deposited on flexible PDMS mold, containing surface protrusion patterns, and the Au layer is transferred from PDMS mold to various substrates due to the difference of bonding strength of Au layer to PDMS mold and to the substrate. For effective transfer of Au layer, self-assembled monolayer, which has strong bonding to Au, is deposited on the substrate as a glue layer. In this study, complicated SAM layer coating process was replaced to simple UV/ozone treatment, which can activates the surface and form the -OH radicals. Using simple UV/ozone treatments on both Au and substrate, Au nano-pattern can be successfully transferred to as large as 6 in. diameter Si wafer, without SAM coating process. High fidelity transfer of Au nano-patterns to non-planar glass lens and flexible PET film was also demonstrated.

Dropwise Condensation on Soft Hydrophobic Coatings.

PubMed

Phadnis, Akshay; Rykaczewski, Konrad

2017-10-31

Promoting dropwise condensation (DWC) could improve the efficiency of many industrial systems. Consequently, a lot of effort has been dedicated to finding durable materials that could sustainably promote DWC as well as finding routes to enhance the heat transfer rate during this phase change process. Motivated by previous reports of substrate softening increasing droplet nucleation rate, here we investigated how mechanical properties of a substrate impact relevant droplet-surface interactions and DWC heat transfer rate. Specifically, we experimentally quantified the effect of hydrophobic elastomer's shear modulus on droplet nucleation density and shedding radius. To quantify the impact of substrate softening on heat transfer through individual droplets, we combined analytical solution of elastomer deformation induced by droplets with finite element modeling of the heat transfer process. By substituting these experimentally and theoretically derived values into DWC heat transfer model, we quantified the compounding effect of the substrate's mechanical properties on the overall heat transfer rate. Our results show that softening of the substrates below a shear modulus of 500 kPa results in a significant reduction in the condensation heat transfer rate. This trend is primarily driven by additional thermal resistance of the liquid posed by depression of the soft substrate.

Chitosan-microreactor: a versatile approach for heterogeneous organic synthesis in microfluidics.

PubMed

Basavaraju, K C; Sharma, Siddharth; Singh, Ajay K; Im, Do Jin; Kim, Dong-Pyo

2014-07-01

Microreactors have been proven to be efficient tools for a variety of homogeneous organic transformations due to their mixing efficiency, which results in very fast reactions, better heat and mass transfer, and simple scale-up. However, in heterogeneous catalytic reactions each catalyst needs an individual substrate as support. Herein, a versatile approach to immobilize metal catalysts on chitosan as a common substrate is presented. Chitosan, accommodating many metal catalysts, is grafted onto the microchannel surface as nanobrush. The versatility, catalytic efficiency, and stability/durability of the microreactor are demonstrated for a number of organic transformations involving various metal compounds as catalysts. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of Substrate and Process Parameters on the Gas-Substrate Convective Heat Transfer Coefficient During Cold Spraying

NASA Astrophysics Data System (ADS)

Mahdavi, Amirhossein; McDonald, André

2018-02-01

The final quality of cold-sprayed coatings can be significantly influenced by gas-substrate heat exchange, due to the dependence of the deposition efficiency of the particles on the substrate temperature distribution. In this study, the effect of the air temperature and pressure, as process parameters, and surface roughness and thickness, as substrate parameters, on the convective heat transfer coefficient of the impinging air jet was investigated. A low-pressure cold spraying unit was used to generate a compressed air jet that impinged on a flat substrate. A comprehensive mathematical model was developed and coupled with experimental data to estimate the heat transfer coefficient and the surface temperature of the substrate. The effect of the air total temperature and pressure on the heat transfer coefficient was studied. It was found that increasing the total pressure would increase the Nusselt number of the impinging air jet, while total temperature of the air jet had negligible effect on the Nusslet number. It was further found that increasing the roughness of the substrate enhanced the heat exchange between the impinging air jet and the substrate. As a result, higher surface temperatures on the rough substrate were measured. The study of the effect of the substrate thickness on the heat transfer coefficient showed that the Nusselt number that was predicted by the model was independent of the thickness of the substrate. The surface temperature profile, however, decreased in increasing radial distances from the stagnation point of the impinging jet as the thickness of the substrate increased. The results of the current study were aimed to inform on the influence and effect of substrate and process parameters on the gas-substrate heat exchange and the surface temperature of the substrate on the final quality of cold-sprayed coatings.

Ultraclean and Direct Transfer of a Wafer-Scale MoS2 Thin Film onto a Plastic Substrate.

PubMed

Phan, Hoang Danh; Kim, Youngchan; Lee, Jinhwan; Liu, Renlong; Choi, Yongsuk; Cho, Jeong Ho; Lee, Changgu

2017-02-01

An ultraclean method to directly transfer a large-area MoS 2 film from the original growth substrate to a flexible substrate by using epoxy glue is developed. The transferred film is observed to be free of wrinkles and cracks and to be as smooth as the film synthesized on the original substrate. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

From nano- to macro-engineering of oxide-encapsulated-nanoparticles for harsh reactions: one-step organization via cross-linking molecules.

PubMed

Zhang, Qiaofei; Zhao, Guofeng; Zhang, Zhiqiang; Han, Lupeng; Fan, Songyu; Chai, Ruijuan; Li, Yakun; Liu, Ye; Huang, Jun; Lu, Yong

2016-09-29

A strategy of "macro-micro-nano" organization is reported for embedding oxide-encapsulated-nanoparticles onto monolithic substrates in one-step with the aid of molecularly defined cross-linking agents. Such catalysts, with enhanced heat/mass transfer and high permeability, are qualified for several harsh reaction processes such as CH 4 /VOC abatement, gas-phase hydrogenation of dimethyl oxalate and oxidative dehydrogenation of ethane.

Heat and mass transfer models to understand the drying mechanisms of a porous substrate.

PubMed

Songok, Joel; Bousfield, Douglas W; Gane, Patrick A C; Toivakka, Martti

2016-02-01

While drying of paper and paper coatings is expensive, with significant energy requirements, the rate controlling mechanisms are not currently fully understood. Two two-dimensional models are used as a first approximation to predict the heat transfer during hot air drying and to evaluate the role of various parameters on the drying rates of porous coatings. The models help determine the structural limiting factors during the drying process, while applying for the first time the recently known values of coating thermal diffusivity. The results indicate that the thermal conductivity of the coating structure is not the controlling factor, but the drying rate is rather determined by the thermal transfer process at the structure surface. This underlines the need for ensuring an efficient thermal transfer from hot air to coating surface during drying, before considering further measures to increase the thermal conductivity of porous coatings.

A thermochemical-biochemical hybrid processing of lignocellulosic biomass for producing fuels and chemicals.

PubMed

Shen, Yanwen; Jarboe, Laura; Brown, Robert; Wen, Zhiyou

2015-12-01

Thermochemical-biological hybrid processing uses thermochemical decomposition of lignocellulosic biomass to produce a variety of intermediate compounds that can be converted into fuels and chemicals through microbial fermentation. It represents a unique opportunity for biomass conversion as it mitigates some of the deficiencies of conventional biochemical (pretreatment-hydrolysis-fermentation) and thermochemical (pyrolysis or gasification) processing. Thermochemical-biological hybrid processing includes two pathways: (i) pyrolysis/pyrolytic substrate fermentation, and (ii) gasification/syngas fermentation. This paper provides a comprehensive review of these two hybrid processing pathways, including the characteristics of fermentative substrates produced in the thermochemical stage and microbial utilization of these compounds in the fermentation stage. The current challenges of these two biomass conversion pathways include toxicity of the crude pyrolytic substrates, the inhibition of raw syngas contaminants, and the mass-transfer limitations in syngas fermentation. Possible approaches for mitigating substrate toxicities are discussed. The review also provides a summary of the current efforts to commercialize hybrid processing. Copyright © 2015 Elsevier Inc. All rights reserved.

Improve biogas production from low-organic-content sludge through high-solids anaerobic co-digestion with food waste.

PubMed

Liu, Chuanyang; Li, Huan; Zhang, Yuyao; Liu, Can

2016-11-01

Anaerobic co-digestion of sewage sludge and food waste was tested at two different total solid (TS) concentrations. In the low-solids group with TS 4.8%, the biogas production increased linearly as the ratio of food waste in substrate increased from 0 to 100%, but no synergetic effect was found between the two substrates. Moreover, the additive food waste resulted in the accumulation of volatile fatty acids and decelerated biogas production. Thus, the blend ratio of food waste should be lower than 50%. While in the high-solids group with TS 14%, the weak alkaline environment with pH 7.5-8.5 avoided excessive acidification but high concentration of free ammonia was a potential risk. However, good synergetic effect was found between the two substrates because the added food waste improved mass transfer in sludge cake. Thus, 50% was recommended as the optimum ratio of food waste in substrate because of the best synergetic effect. Copyright © 2016 Elsevier Ltd. All rights reserved.

Electrostatic transfer of epitaxial graphene to glass.

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

Ohta, Taisuke; Pan, Wei; Howell, Stephen Wayne

2010-12-01

We report on a scalable electrostatic process to transfer epitaxial graphene to arbitrary glass substrates, including Pyrex and Zerodur. This transfer process could enable wafer-level integration of graphene with structured and electronically-active substrates such as MEMS and CMOS. We will describe the electrostatic transfer method and will compare the properties of the transferred graphene with nominally-equivalent 'as-grown' epitaxial graphene on SiC. The electronic properties of the graphene will be measured using magnetoresistive, four-probe, and graphene field effect transistor geometries [1]. To begin, high-quality epitaxial graphene (mobility 14,000 cm2/Vs and domains >100 {micro}m2) is grown on SiC in an argon-mediated environmentmore » [2,3]. The electrostatic transfer then takes place through the application of a large electric field between the donor graphene sample (anode) and the heated acceptor glass substrate (cathode). Using this electrostatic technique, both patterned few-layer graphene from SiC(000-1) and chip-scale monolayer graphene from SiC(0001) are transferred to Pyrex and Zerodur substrates. Subsequent examination of the transferred graphene by Raman spectroscopy confirms that the graphene can be transferred without inducing defects. Furthermore, the strain inherent in epitaxial graphene on SiC(0001) is found to be partially relaxed after the transfer to the glass substrates.« less

The continuous assembly and transfer of nanoelements

NASA Astrophysics Data System (ADS)

Kumar, Arun

Patterned nanoelements on flexible polymeric substrates at micro/nano scale at high rate, low cost, and commercially viable route offer an opportunity for manufacturing devices with micro/nano scale features. These micro/nano scale now made with various nanoelement can enhance the device functionality in sensing and switching due to their improved conductivity and better mechanical properties. In this research the fundamental understanding of high rate assembly and transfer of nanoelements has been developed. To achieve this objective, three sub topics were made. In the first step, the use of electrophoresis for the controlled assembly of CNT's on interdigitated templates has been shown. The time scale of assembly reported is shorter than the previously reported assembly time (60 seconds). The mass deposited was also predicted using the Hamaker's law. It is also shown that pre-patterned CNT's could be transferred from the rigid templates onto flexible polymeric substrates using a thermoforming process. The time scale of transfer is less than one minute (50 seconds) and was found to be dependent on polymer chemistry. It was found that CNT's preferentially transfer from Au electrode to non-polar polymeric substrates (polyurethane and polyethylene terephalathate glycol) in the thermoforming process. In the second step, a novel process (Pulsed Electrophoresis) has been shown for the first time to assist the assembly of conducting polyaniline on gold nanowire interdigitated templates. This technique offers dynamic control over heat build-up, which has been a main drawback in the DC electrophoresis and AC dielectrophoresis as well as the main cause of nanowire template damage. The use of this technique allowed higher voltages to be applied, resulting in shorter assembly times (e.g., 17.4 seconds, assembly resolution of 100 nm). The pre-patterned templates with PANi deposition were subsequently used to transfer the nanoscale assembled PANi from the rigid templates to thermoplastic polyurethane using the thermoforming process. In the third step, a novel integration of high rate pulsed electrophoretic assembly with thermally assisted transfer in a roll-to-roll process has been shown. This technique allowed the whole assembly and transfer process to take place in only 30 seconds. Further, a processing window is developed to control the percent area coverage of PANi with the aid of the belt speed. Also shown is the effect of different types of polymer on the quality of transfer, and it concluded that the transfer is affected by the polymer chemistry.

Flow effects in a vertical CVD reactor

NASA Technical Reports Server (NTRS)

Young, G. W.; Hariharan, S. I.; Carnahan, R.

1992-01-01

A model is presented to simulate the non-Boussinesq flow in a vertical, two-dimensional, chemical vapor deposition reactor under atmospheric pressure. Temperature-dependent conductivity, mass diffusivity, viscosity models, and reactive species mass transfer to the substrate are incorporated. In the limits of small Mach number and small aspect ratio, asymptotic expressions for the flow, temperature, and species fields are developed. Soret diffusion effects are also investigated. Analytical solutions predict an inverse relationship between temperature field and concentration field due to Soret effects. This finding is consistent with numerical simulations, assisting in the understanding of the complex interactions amongst the flow, thermal, and species fields in a chemically reacting system.

Fabrication of complex nanoscale structures on various substrates

NASA Astrophysics Data System (ADS)

Han, Kang-Soo; Hong, Sung-Hoon; Lee, Heon

2007-09-01

Polymer based complex nanoscale structures were fabricated and transferred to various substrates using reverse nanoimprint lithography. To facilitate the fabrication and transference of the large area of the nanostructured layer to the substrates, a water-soluble polyvinyl alcohol mold was used. After generation and transference of the nanostructured layer, the polyvinyl alcohol mold was removed by dissolving in water. A residue-free, UV-curable, glue layer was formulated and used to bond the nanostructured layer onto the substrates. As a result, nanometer scale patterned polymer layers were bonded to various substrates and three-dimensional nanostructures were also fabricated by stacking of the layers.

Screening of HIV-1 Protease Using a Combination of an Ultra-High-Throughput Fluorescent-Based Assay and RapidFire Mass Spectrometry.

PubMed

Meng, Juncai; Lai, Ming-Tain; Munshi, Vandna; Grobler, Jay; McCauley, John; Zuck, Paul; Johnson, Eric N; Uebele, Victor N; Hermes, Jeffrey D; Adam, Gregory C

2015-06-01

HIV-1 protease (PR) represents one of the primary targets for developing antiviral agents for the treatment of HIV-infected patients. To identify novel PR inhibitors, a label-free, high-throughput mass spectrometry (HTMS) assay was developed using the RapidFire platform and applied as an orthogonal assay to confirm hits identified in a fluorescence resonance energy transfer (FRET)-based primary screen of > 1 million compounds. For substrate selection, a panel of peptide substrates derived from natural processing sites for PR was evaluated on the RapidFire platform. As a result, KVSLNFPIL, a new substrate measured to have a ~ 20- and 60-fold improvement in k cat/K m over the frequently used sequences SQNYPIVQ and SQNYPIV, respectively, was identified for the HTMS screen. About 17% of hits from the FRET-based primary screen were confirmed in the HTMS confirmatory assay including all 304 known PR inhibitors in the set, demonstrating that the HTMS assay is effective at triaging false-positives while capturing true hits. Hence, with a sampling rate of ~7 s per well, the RapidFire HTMS assay enables the high-throughput evaluation of peptide substrates and functions as an efficient tool for hits triage in the discovery of novel PR inhibitors. © 2015 Society for Laboratory Automation and Screening.

Properties of GaN grown on sapphire substrates

NASA Technical Reports Server (NTRS)

Crouch, R. K.; Debnam, W. J.; Fripp, A. L.

1978-01-01

Epitaxial growth of GaN on sapphire substrates using an open-tube growth furnace has been carried out to study the effects of substrate orientation and transfer gas upon the properties of the layers. It has been found that for the (0001) substrates, surface appearance was virtually independent of carrier gas and of doping levels. For the (1(-1)02) substrates surface faceting was greatly reduced when He was used as a transfer gas as opposed to H2. Faceting was also reduced when the GaN was doped with Zn, and the best surfaces for the (1(-1)02) substrates were obtained in a Zn-doped run using He as the transfer gas. The best sample in terms of electrical properties for the (1(-1)02) substrate had a mobility greater than 400 sq cm/V per sec and a carrier concentration of about 10 to the 17th per cu cm. This sample was undoped and used He as the transfer gas. The best (0001) sample was also grown undoped with He as the transfer gas and had a mobility of 300 sq cm/V per sec and a carrier concentration of 1 x 10 to the 18th per cu cm.

Determination of diffusion coefficients and diffusion characteristics for chlorferon and diethylthiophosphate in Ca-alginate gel beads.

PubMed

Ha, Jiyeon; Engler, Cady R; Lee, Seung Jae

2008-07-01

Diffusion characteristics of chlorferon and diethylthiophosphate (DETP) in Ca-alginate gel beads were studied to assist in designing and operating bioreactor systems. Diffusion coefficients for chlorferon and DETP in Ca-alginate gel beads determined at conditions suitable for biodegradation studies were 2.70 x 10(-11) m(2)/s and 4.28 x 10(-11) m(2)/s, respectively. Diffusivities of chlorferon and DETP were influenced by several factors, including viscosity of the bulk solution, agitation speed, and the concentrations of diffusing substrate and immobilized cells. Diffusion coefficients increased with increasing agitation speed, probably due to poor mixing at low speed and some attrition of beads at high speeds. Diffusion coefficients also increased with decreasing substrate concentration. Increased cell concentration in the gel beads caused lower diffusivity. Theoretical models to predict diffusivities as a function of cell weight fraction overestimated the effective diffusivities for both chlorferon and DETP, but linear relations between effective diffusivity and cell weight fraction were derived from experimental data. Calcium-alginate gel beads with radii of 1.65-1.70 mm used in this study were not subject to diffusional limitations: external mass transfer resistances were negligible based on Biot number calculations and effectiveness factors indicated that internal mass transfer resistance was negligible. Therefore, the degradation rates of chlorferon and DETP inside Ca-alginate gel beads were reaction-limited. (c) 2007 Wiley Periodicals, Inc.

Fabrication of nanowire electronics on nonconventional substrates by water-assisted transfer printing method

NASA Astrophysics Data System (ADS)

Lee, Chi Hwan; Kim, Dong Rip; Zheng, Xiaolin

2015-06-01

We report a simple, versatile, and wafer-scale water-assisted transfer printing method (WTP) that enables the transfer of nanowire devices onto diverse nonconventional substrates that were not easily accessible before, such as paper, plastics, tapes, glass, polydimethylsiloxane (PDMS), aluminum foil, and ultrathin polymer substrates. The WTP method relies on the phenomenon of water penetrating into the interface between Ni and SiO2. The transfer yield is nearly 100%, and the transferred devices, including NW resistors, diodes, and field effect transistors, maintain their original geometries and electronic properties with high fidelity.

Identification of Microalgae by Laser Desorption/Ionization Mass Spectrometry Coupled with Multiple Nanomatrices.

PubMed

Peng, Lung-Hsiang; Unnikrishnan, Binesh; Shih, Chi-Yu; Hsiung, Tung-Ming; Chang, Jeng; Hsu, Pang-Hung; Chiu, Tai-Chia; Huang, Chih-Ching

2016-04-01

In this study, we demonstrate a simple method to identify microalgae by surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) using three different substrates: HgSe, HgTe, and HgTeSe nanostructures. The fragmentation/ionization processes of complex molecules in algae varied according to the heat absorption and transfer efficiency of the nanostructured matrices (NMs). Therefore, the mass spectra obtained for microalgae showed different patterns of m/z values for different NMs. The spectra contained both significant and nonsignificant peaks. Constructing a Venn diagram with the significant peaks obtained for algae when using HgSe, HgTe, and HgTeSe NMs in m/z ratio range 100-1000, a unique relationship among the three sets of values was obtained. This unique relationship of sets is different for each species of microalgae. Therefore, by observing the particular relationship of sets, we successfully identified different algae such as Isochrysis galbana, Emiliania huxleyi, Thalassiosira weissflogii, Nannochloris sp., Skeletonema cf. costatum, and Tetraselmis chui. This simple and cost-effective SALDI-MS analysis method coupled with multi-nanomaterials as substrates may be extended to identify other microalgae and microorganisms in real samples. Graphical Abstract Identification of microalgae by surface-assisted laser desorption/ionization mass spectrometry coupled with three different mercury-based nanosubstrates.

Salt-assisted clean transfer of continuous monolayer MoS2 film for hydrogen evolution reaction

NASA Astrophysics Data System (ADS)

Cho, Heung-Yeol; Nguyen, Tri Khoa; Ullah, Farman; Yun, Jong-Won; Nguyen, Cao Khang; Kim, Yong Soo

2018-03-01

The transfer of two-dimensional (2D) materials from one substrate to another is challenging but of great importance for technological applications. Here, we propose a facile etching and residue-free method for transferring a large-area monolayer MoS2 film continuously grown on a SiO2/Si by chemical vapor deposition. Prior to synthesis, the substrate is dropped with water- soluble perylene-3, 4, 9, 10-tetracarboxylic acid tetrapotassium salt (PTAS). The as-grown MoS2 on the substrate is simply dipped in water to quickly dissolve PTAS to yield the MoS2 film floating on the water surface, which is subsequently transferred to the desired substrate. The morphological, optical and X-ray photoelectron spectroscopic results show that our method is useful for fast and clean transfer of the MoS2 film. Specially, we demonstrate that monolayer MoS2 film transferred onto a conducting substrate leads to excellent performance for hydrogen evolution reaction with low overpotential (0.29 V vs the reversible hydrogen electrode) and Tafel slope (85.5 mV/decade).

POLYELECTROLYTE MULTILAYER STAMPING IN AQUEOUS PHASE AND NON-CONTACT MODE

PubMed Central

Mehrotra, Sumit; Lee, Ilsoon; Liu, Chun; Chan, Christina

2011-01-01

Polyelectrolyte multilayer (PEM) transfer printing has been previously achieved by stamping under dry conditions. Here, we show for the first time, that PEM can be transferred from a stamp to the base substrate under aqueous conditions whereby the two surfaces are in a non-contact mode. Degradable multilayers of (PAA/PEG)10.5 followed by non-degradable multilayers of (PDAC/SPS)80.5 were fabricated under acidic pH conditions on either PDMS or glass (stamp), and subsequently transferred over top of another multilayer prepared on a different substrate (base substrate), with a spacing of ~ 200 μm between the stamping surface and the base substrate. This multilayer transfer was performed under physiological pH conditions. This process is referred to herein as non-contact, aqueous-phase multilayer (NAM) transfer. NAM transfer can be useful for applications such as fabricating three-dimensional (3-D) cellular scaffolds. We attempted to create a 3-D cellular scaffold using NAM transfer, and characterized the scaffolds with conventional and fluorescence microscopy. PMID:21860540

Epitaxial growth of silicon for layer transfer

DOEpatents

Teplin, Charles; Branz, Howard M

2015-03-24

Methods of preparing a thin crystalline silicon film for transfer and devices utilizing a transferred crystalline silicon film are disclosed. The methods include preparing a silicon growth substrate which has an interface defining substance associated with an exterior surface. The methods further include depositing an epitaxial layer of silicon on the silicon growth substrate at the surface and separating the epitaxial layer from the substrate substantially along the plane or other surface defined by the interface defining substance. The epitaxial layer may be utilized as a thin film of crystalline silicon in any type of semiconductor device which requires a crystalline silicon layer. In use, the epitaxial transfer layer may be associated with a secondary substrate.

Digital Transfer Growth of Patterned 2D Metal Chalcogenides by Confined Nanoparticle Evaporation

DOE PAGES

Mahjouri-Samani, Masoud; Tian, Mengkun; Wang, Kai; ...

2014-10-19

Developing methods for the facile synthesis of two-dimensional (2D) metal chalcogenides and other layered materials is crucial for emerging applications in functional devices. Controlling the stoichiometry, number of the layers, crystallite size, growth location, and areal uniformity is challenging in conventional vapor phase synthesis. Here, we demonstrate a new route to control these parameters in the growth of metal chalcogenide (GaSe) and dichalcogenide (MoSe 2) 2D crystals by precisely defining the mass and location of the source materials in a confined transfer growth system. A uniform and precise amount of stoichiometric nanoparticles are first synthesized and deposited onto a substratemore » by pulsed laser deposition (PLD) at room temperature. This source substrate is then covered with a receiver substrate to form a confined vapor transport growth (VTG) system. By simply heating the source substrate in an inert background gas, a natural temperature gradient is formed that evaporates the confined nanoparticles to grow large, crystalline 2D nanosheets on the cooler receiver substrate, the temperature of which is controlled by the background gas pressure. Large monolayer crystalline domains (~ 100 m lateral sizes) of GaSe and MoSe 2 are demonstrated, as well as continuous monolayer films through the deposition of additional precursor materials. This novel PLD-VTG synthesis and processing method offers a unique approach for the controlled growth of large-area, metal chalcogenides with a controlled number of layers in patterned growth locations for optoelectronics and energy related applications.« less

Biolithography: Slime mould patterning of polyaniline

NASA Astrophysics Data System (ADS)

Berzina, Tatiana; Dimonte, Alice; Adamatzky, Andrew; Erokhin, Victor; Iannotta, Salvatore

2018-03-01

Slime mould Physarum polycephalum develops intricate patterns of protoplasmic networks when foraging on a non-nutrient substrates. The networks are optimised for spanning larger spaces with minimum body mass and for quick transfer of nutrients and metabolites inside the slime mould's body. We hybridise the slime mould's networks with conductive polymer polyaniline and thus produce micro-patterns of conductive networks. This unconventional lithographic method opens new perspectives in development of living technology devices, biocompatible non-silicon hardware for applications in integrated circuits, bioelectronics, and biosensing.

Fabrication of porous matrix membrane (PMM) using metal-organic framework as green template for water treatment.

PubMed

Lee, Jian-Yuan; Tang, Chuyang Y; Huo, Fengwei

2014-01-17

Pressure-driven membranes with high porosity can potentially be fabricated by removing template, such as low water stability metal-organic frameworks (MOFs) or other nanoparticles, in polymeric matrix. We report on the use of benign MOFs as green template to enhance porosity and interconnectivity of the water treatment membranes. Significantly enhanced separation performance was observed which might be attributed to the mass transfer coefficient of the substrate layer increased in ultrafiltration (UF) application.

Integration of Indium Phosphide Based Devices with Flexible Substrates

NASA Astrophysics Data System (ADS)

Chen, Wayne Huai

2011-12-01

Flexible substrates have many advantages in applications where bendability, space, or weight play important roles or where rigid circuits are undesirable. However, conventional flexible thin film transistors are typically characterized as having low carrier mobility as compared to devices used in the electronics industry. This is in part due to the limited temperature tolerance of plastic flexible substrates, which commonly reduces the highest processing temperature to below 200°C. Common approaches of implementation include low temperature deposition of organic, amorphous, or polycrystalline semiconductors, all of which result in carrier mobility well below 100 cm2V -1s-1. High quality, single crystalline III-V semiconductors such as indium phosphide (InP), on the other hand, have carrier mobility well over 1000 cm 2V-1s-1 at room temperature, depending on carrier concentration. Recently, the ion-cut process has been used in conjunction with wafer bonding to integrate thin layers of III-V material onto silicon for optoelectronic applications. This approach has the advantage of high scalability, reusability of the initial III-V substrate, and the ability to tailor the location (depth) of the layer splitting. However, the transferred substrate usually suffers from hydrogen implantation damage. This dissertation demonstrates a new approach to enable integration of InP with various substrates, called the double-flip transfer process. The process combines ion-cutting with adhesive bonding. The problem of hydrogen implantation was overcome by patterned ion-cut transfer. In this type of transfer, areas of interest are shielded from implantation but still transferred by surrounding implanted regions. We found that patterned ion-cut transfer is strongly dependent upon crystal orientation and that using cleavage-plane oriented donors can be beneficial in transferring large areas of high quality semiconductor material. InP-based devices were fabricated to demonstrate the transfer process and test functionality following transfer. Passive devices (photodetectors) as well as active transistors were transferred and fabricated on various substrates. The transferred device layers were either implanted through with a blanket implant or protected with an ion-mask during implantation. Results demonstrate the viability of the double-flip ion-cut process in achieving very high electron mobility (˜2800 cm2V-1s-1) transistors on plastic flexible substrates.

The feasibility study of crude palm oil transesterification at 30 °C operation.

PubMed

Sim, Jia Huey; Kamaruddin, Azlina Harun; Bhatia, Subhash

2010-12-01

The objective of this research is to investigate the potential of transesterification of crude palm oil (CPO) to biodiesel at 30 degrees C. The mass transfer limitations problem crucial at 30 degrees C due to the viscosity of CPO has been addressed. The process parameters that are closely related to mass transfer effects like enzyme loading, agitation speed and reaction time were optimized. An optimum methanol to oil substrate molar ratio at 6.5:1 was observed and maintained throughout the experiments. The optimum operating condition for the transesterification process was found at 6.67 wt% of enzyme loading and at 150 rpm of agitation speed. The corresponding initial reaction and FAME yield obtained at 6 h were 89.29% FAME yield/hr and 85.01%, respectively. The 85% FAME yield obtained at 30 degrees C operation of CPO transesterification shows that the process is potentially feasible for the biodiesel synthesis. 2010 Elsevier Ltd. All rights reserved.

Transfer of micro and nano-photonic silicon nanomembrane waveguide devices on flexible substrates.

PubMed

Ghaffari, Afshin; Hosseini, Amir; Xu, Xiaochuan; Kwong, David; Subbaraman, Harish; Chen, Ray T

2010-09-13

This paper demonstrates transfer of optical devices without extra un-patterned silicon onto low-cost, flexible plastic substrates using single-crystal silicon nanomembranes. Employing this transfer technique, stacking two layers of silicon nanomembranes with photonic crystal waveguide in the first layer and multi mode interference couplers in the second layer is shown, respectively. This technique is promising to realize high density integration of multilayer hybrid structures on flexible substrates.

A One-Pot/Single-Analysis Approach to Substrate Scope Investigations Using Comprehensive Two-Dimensional Gas Chromatography (GC×GC).

PubMed

O'Neil, Gregory W; Nelson, Robert K; Wright, Alicia M; Reddy, Christopher M

2016-05-06

A representative substrate scope investigation for an enantioselective catalytic ketone-reduction has been performed as a single reaction on a mixture containing equimolar amounts of nine (9) prototypical compounds. The resulting analyte pool containing 18 potential products from nine different reactions could all be completely resolved in a single chromatographic injection using comprehensive two-dimensional gas chromatography (GC×GC) with time-of-flight mass spectrometry, allowing for simultaneous determination of percent conversion and enantiomeric excess for each substrate. The results obtained for an enantioselective iron-catalyzed asymmetric transfer hydrogenation using this one-pot/single-analysis approach were similar to those reported for the individualized reactions, demonstrating the utility of this strategy for streamlining substrate scope investigations. Moreover, for this particular catalyst, activity and selectivity were not greatly affected by the presence of other ketones or enantioenriched reduced products. This approach allows for faster and greener analyses that are central to new reaction development, as well as an opportunity to gain further insights into other established transformations.

Gas sensors boosted by two-dimensional h-BN enabled transfer on thin substrate foils: towards wearable and portable applications.

PubMed

Ayari, Taha; Bishop, Chris; Jordan, Matthew B; Sundaram, Suresh; Li, Xin; Alam, Saiful; ElGmili, Youssef; Patriarche, Gilles; Voss, Paul L; Salvestrini, Jean Paul; Ougazzaden, Abdallah

2017-11-09

The transfer of GaN based gas sensors to foreign substrates provides a pathway to enhance sensor performance, lower the cost and extend the applications to wearable, mobile or disposable systems. The main keys to unlocking this pathway is to grow and fabricate the sensors on large h-BN surface and to transfer them to the flexible substrate without any degradation of the performances. In this work, we develop a new generation of AlGaN/GaN gas sensors with boosted performances on a low cost flexible substrate. We fabricate 2-inch wafer scale AlGaN/GaN gas sensors on sacrificial two-dimensional (2D) nano-layered h-BN without any delamination or cracks and subsequently transfer sensors to an acrylic surface on metallic foil. This technique results in a modification of relevant device properties, leading to a doubling of the sensitivity to NO 2 gas and a response time that is more than 6 times faster than before transfer. This new approach for GaN-based sensor design opens new avenues for sensor improvement via transfer to more suitable substrates, and is promising for next-generation wearable and portable opto-electronic devices.

Laser-assisted simultaneous transfer and patterning of vertically aligned carbon nanotube arrays on polymer substrates for flexible devices.

PubMed

In, Jung Bin; Lee, Daeho; Fornasiero, Francesco; Noy, Aleksandr; Grigoropoulos, Costas P

2012-09-25

We demonstrate a laser-assisted dry transfer technique for assembling patterns of vertically aligned carbon nanotube arrays on a flexible polymeric substrate. A laser beam is applied to the interface of a nanotube array and a polycarbonate sheet in contact with one another. The absorbed laser heat promotes nanotube adhesion to the polymer in the irradiated regions and enables selective pattern transfer. A combination of the thermal transfer mechanism with rapid direct writing capability of focused laser beam irradiation allows us to achieve simultaneous material transfer and direct micropatterning in a single processing step. Furthermore, we demonstrate that malleability of the nanotube arrays transferred onto a flexible substrate enables post-transfer tailoring of electric conductance by collapsing the aligned nanotubes in different directions. This work suggests that the laser-assisted transfer technique provides an efficient route to using vertically aligned nanotubes as conductive elements in flexible device applications.

Portable ultrahigh-vacuum sample storage system for polarization-dependent total-reflection fluorescence x-ray absorption fine structure spectroscopy

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

Watanabe, Yoshihide, E-mail: e0827@mosk.tytlabs.co.jp; Nishimura, Yusaku F.; Suzuki, Ryo

A portable ultrahigh-vacuum sample storage system was designed and built to investigate the detailed geometric structures of mass-selected metal clusters on oxide substrates by polarization-dependent total-reflection fluorescence x-ray absorption fine structure spectroscopy (PTRF-XAFS). This ultrahigh-vacuum (UHV) sample storage system provides the handover of samples between two different sample manipulating systems. The sample storage system is adaptable for public transportation, facilitating experiments using air-sensitive samples in synchrotron radiation or other quantum beam facilities. The samples were transferred by the developed portable UHV transfer system via a public transportation at a distance over 400 km. The performance of the transfer system was demonstratedmore » by a successful PTRF-XAFS study of Pt{sub 4} clusters deposited on a TiO{sub 2}(110) surface.« less

Toward mass producible ordered bulk heterojunction organic photovoltaic devices.

PubMed

Kim, Taeyong; Yoon, Hyunsik; Song, Hyung-Jun; Haberkorn, Niko; Cho, Younghyun; Sung, Seung Hyun; Lee, Chang Hee; Char, Kookheon; Theato, Patrick

2012-12-13

A strategy to fabricate nanostructured poly(3-hexylthiophene) (P3HT) films for organic photovoltaic (OPV) cells by a direct transfer method from a reusable soft replica mold is presented. The flexible polyfluoropolyether (PFPE) replica mold allows low-pressure and low- temperature process condition for the successful transfer of nanostructured P3HT films onto PEDOT/PSS-coated ITO substrates. To reduce the fabrication cost of masters in large area, we employed well-ordered anodic aluminum oxide (AAO) as a template. Also, we provide a method to fabricate reversed nanostructures by exploiting the self-replication of replica molds. The concept of the transfer method in low temperature with a flexible and reusable replica mold obtained from an AAO template will be a firm foundation for a low-cost fabrication process of ordered OPVs. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Verification of radionuclide transfer factors to domestic-animal food products, using indigenous elements and with emphasis on iodine.

PubMed

Sheppard, S C; Long, J M; Sanipelli, B

2010-11-01

Recent reviews have established benchmark values for transfer factors that describe radionuclide transfer from plants to animal food product such as milk, eggs and meat. They also illustrate the paucity of data for some elements and some food products. The present study quantified transfer data using indigenous elements measured in dairy, poultry and other livestock farms in Canada. Up to 62 elements are reported, with particular emphasis on iodine (I) because of the need to accurately assess the behaviour of (129)I from disposal of nuclear fuel waste. There was remarkable agreement with the literature values, and for many elements the present study involved many more observations than were previously available. Perhaps the most important observation was that product/substrate concentration ratios (CR) were quite consistent across species, whereas the traditional fractional transfer factors (TF, units of d kg(-1) or d L(-1)) necessarily vary with body mass (feed intake). This suggests that for long-term assessments, it may be advisable to change the models to use CR rather than TF.

Decal transfer microfabrication

DOEpatents

Nuzzo, Ralph G.; Childs, William Robert

2004-10-19

A method of making a microstructure includes forming a pattern in a surface of a silicon-containing elastomer, oxidizing the pattern, contacting the pattern with a substrate; and bonding the oxidized pattern and the substrate such that the pattern and the substrate are irreversibly attached. The silicon-containing elastomer may be removably attached to a transfer pad.

A general strategy for hybrid thin film fabrication and transfer onto arbitrary substrates.

PubMed

Zhang, Yong; Magan, John J; Blau, Werner J

2014-04-28

The development of thin film-based structures/devices often requires thin films to be transferred onto arbitrary substrates/surfaces. Controllable and non-destructive transfer method, although highly desired, remains quite challenging. Here we report a general method for fabrication and transfer of hybrid (ultra)thin films. The proposed solution-based in-situ transfer method shows not only its robust ability for thin film transfer onto arbitrary substrates but also its highly controlled and non-destructive characteristic. With a hole structure as the support, fully-stretched free-standing thin film is prepared. The successful transfer to a curved surface demonstrates the possibility for production of thin film-coated complex optical components. Ultrathin (35 nm) hybrid film transferred onto PET (50 μm thick) shows high transparency (>90% in visible range), conductivity (1.54 × 10(4) S/m), and flexibility (radius of curvature down to mm scale). The reported transfer method would provide a powerful route towards complex thin film-based structures/devices.

A General Strategy for Hybrid Thin Film Fabrication and Transfer onto Arbitrary Substrates

PubMed Central

Zhang, Yong; Magan, John J.; Blau, Werner J.

2014-01-01

The development of thin film-based structures/devices often requires thin films to be transferred onto arbitrary substrates/surfaces. Controllable and non-destructive transfer method, although highly desired, remains quite challenging. Here we report a general method for fabrication and transfer of hybrid (ultra)thin films. The proposed solution-based in-situ transfer method shows not only its robust ability for thin film transfer onto arbitrary substrates but also its highly controlled and non-destructive characteristic. With a hole structure as the support, fully-stretched free-standing thin film is prepared. The successful transfer to a curved surface demonstrates the possibility for production of thin film-coated complex optical components. Ultrathin (35 nm) hybrid film transferred onto PET (50 μm thick) shows high transparency (>90% in visible range), conductivity (1.54 × 104 S/m), and flexibility (radius of curvature down to mm scale). The reported transfer method would provide a powerful route towards complex thin film-based structures/devices. PMID:24769689

Snapshots of C-S Cleavage in Egt2 Reveals Substrate Specificity and Reaction Mechanism.

PubMed

Irani, Seema; Naowarojna, Nathchar; Tang, Yang; Kathuria, Karan R; Wang, Shu; Dhembi, Anxhela; Lee, Norman; Yan, Wupeng; Lyu, Huijue; Costello, Catherine E; Liu, Pinghua; Zhang, Yan Jessie

2018-05-17

Sulfur incorporation in the biosynthesis of ergothioneine, a histidine thiol derivative, differs from other well-characterized transsulfurations. A combination of a mononuclear non-heme iron enzyme-catalyzed oxidative C-S bond formation and a subsequent pyridoxal 5'-phosphate (PLP)-mediated C-S lyase reaction leads to the net transfer of a sulfur atom from a cysteine to a histidine. In this study, we structurally and mechanistically characterized a PLP-dependent C-S lyase Egt2, which mediates the sulfoxide C-S bond cleavage in ergothioneine biosynthesis. A cation-π interaction between substrate and enzyme accounts for Egt2's preference of sulfoxide over thioether as a substrate. Using mutagenesis and structural biology, we captured three distinct states of the Egt2 C-S lyase reaction cycle, including a labile sulfenic intermediate captured in Egt2 crystals. Chemical trapping and high-resolution mass spectrometry were used to confirm the involvement of the sulfenic acid intermediate in Egt2 catalysis. Copyright © 2018 Elsevier Ltd. All rights reserved.

Diplogelasinospora grovesii IMI 171018 immobilized in polyurethane foam. An efficient biocatalyst for stereoselective reduction of ketones.

PubMed

Quezada, M A; Carballeira, J D; Sinisterra, J V

2012-05-01

Diplogelasinospora grovesii has been reported as a very active biocatalyst in the reduction of ketones. Along the text, the properties of this filamentous fungus as an immobilized catalyst are described. For this purpose, several immobilization supports as agar and polyurethane foam were tested. Experimental assays were also performed to test different co-substrates for the regeneration of the required enzyme cofactor. The fungus immobilized in polyurethane foam lead to the most stable and active catalyst. This derivative, using i-PrOH as co-substrate, could be reused at least 18 times without appreciable activity loss (>90% activity remains). Kinetic runs experiments shown that the reduction of cyclohexanone, selected as model substrate, followed a pseudo-first kinetic order and that the rate controlling step was the mass transfer through the cell wall. The deactivation kinetic constants were also determined. The reduction of different chiral ketones showed that the ketone reductase activity followed the Prelog's rule. Copyright © 2012 Elsevier Ltd. All rights reserved.

Male-Specific Transfer and Fine Scale Spatial Differences of Newly Identified Cuticular Hydrocarbons and Triacylglycerides in a Drosophila Species Pair

PubMed Central

Yew, Joanne Y.; Dreisewerd, Klaus; de Oliveira, Cássia Cardoso; Etges, William J.

2011-01-01

We analyzed epicuticular hydrocarbon variation in geographically isolated populations of D. mojavensis cultured on different rearing substrates and a sibling species, D. arizonae, with ultraviolet laser desorption/ionization mass spectrometry (UV-LDI MS). Different body parts, i.e. legs, proboscis, and abdomens, of both species showed qualitatively similar hydrocarbon profiles consisting mainly of long-chain monoenes, dienes, trienes, and tetraenes. However, D. arizonae had higher amounts of most hydrocarbons than D. mojavensis and females of both species exhibited greater hydrocarbon amounts than males. Hydrocarbon profiles of D. mojavensis populations were significantly influenced by sex and rearing substrates, and differed between body parts. Lab food–reared flies had lower amounts of most hydrocarbons than flies reared on fermenting cactus substrates. We discovered 48 male- and species-specific hydrocarbons ranging in size from C22 to C50 in the male anogenital region of both species, most not described before. These included several oxygen-containing hydrocarbons in addition to high intensity signals corresponding to putative triacylglycerides, amounts of which were influenced by larval rearing substrates. Some of these compounds were transferred to female cuticles in high amounts during copulation. This is the first study showing that triacylglycerides may be a separate class of courtship-related signaling molecules in drosophilids. This study also extends the kind and number of epicuticular hydrocarbons in these species and emphasizes the role of larval ecology in influencing amounts of these compounds, many of which mediate courtship success within and between species. PMID:21369358

Storage and growth of denitrifiers in aerobic granules: part I. model development.

PubMed

Ni, Bing-Jie; Yu, Han-Qing

2008-02-01

A mathematical model, based on the Activated Sludge Model No.3 (ASM3), is developed to describe the storage and growth activities of denitrifiers in aerobic granules under anoxic conditions. In this model, mass transfer, hydrolysis, simultaneous anoxic storage and growth, anoxic maintenance, and endogenous decay are all taken into account. The model established is implemented in the well-established AQUASIM simulation software. A combination of completely mixed reactor and biofilm reactor compartments provided by AQUASIM is used to simulate the mass transport and conversion processes occurring in both bulk liquid and granules. The modeling results explicitly show that the external substrate is immediately utilized for storage and growth at feast phase. More external substrates are diverted to storage process than the primary biomass production process. The model simulation indicates that the nitrate utilization rate (NUR) of granules-based denitrification process includes four linear phases of nitrate reduction. Furthermore, the methodology for determining the most important parameter in this model, that is, anoxic reduction factor, is established. (c) 2007 Wiley Periodicals, Inc.

Guided growth of horizontal GaN nanowires on quartz and their transfer to other substrates.

PubMed

Goren-Ruck, Lior; Tsivion, David; Schvartzman, Mark; Popovitz-Biro, Ronit; Joselevich, Ernesto

2014-03-25

The guided growth of horizontal nanowires has so far been demonstrated on a limited number of substrates. In most cases, the nanowires are covalently bonded to the substrate where they grow and cannot be transferred to other substrates. Here we demonstrate the guided growth of well-aligned horizontal GaN nanowires on quartz and their subsequent transfer to silicon wafers by selective etching of the quartz while maintaining their alignment. The guided growth was observed on different planes of quartz with varying degrees of alignment. We characterized the crystallographic orientations of the nanowires and proposed a new mechanism of "dynamic graphoepitaxy" for their guided growth on quartz. The transfer of the guided nanowires enabled the fabrication of back-gated field-effect transistors from aligned nanowire arrays on oxidized silicon wafers and the production of crossbar arrays. The guided growth of transferrable nanowires opens up the possibility of massively parallel integration of nanowires into functional systems on virtually any desired substrate.

Fabrication of non-hexagonal close packed colloidal array on a substrate by transfer

NASA Astrophysics Data System (ADS)

Banik, Meneka; Mukherjee, Rabibrata

Self-organized colloidal arrays find application in fabrication of solar cells with advanced light management strategies. We report a simple spincoating based approach for fabricating two dimensional colloidal crystals with hexagonal and non-hexagonal close packed assembly on flat and nanopatterned substrates. The non-HCP arrays were fabricated by spin coating the particles onto soft lithographically fabricated substrates. The substrate patterns impose directionality to the particles by confining them within the grooves. We have developed a technique by which the HCP and non-HCP arrays can be transferred to any surface. For this purpose the colloidal arrays were fabricated on a UV degradable PMMA layer, resulting in transfer of the particles on UV exposure. This allows the colloidal structures to be transported across substrates irrespective of their surface energy, wettability or morphology. Since the particles are transferred without exposing it to any kind of chemical or thermal environment, it can be utilized for placing particles on top of thin film solar cells for improving their absorption efficiency.

Direct metal transfer printing on flexible substrate for fabricating optics functional devices

NASA Astrophysics Data System (ADS)

Jiang, Yingjie; Zhou, Xiaohong; Zhang, Feng; Shi, Zhenwu; Chen, Linsen; Peng, Changsi

2015-11-01

New functional materials and devices based on metal patterns can be widely used in many new and expanding industries,such as flat panel displays, alternative energy,sensors and so on. In this paper, we introduce a new transfer printing method for fabricating metal optics functional devices. This method can directly transfer a metal pattern from a polyethylene terephthalate (PET)supported UV or polydimethylsiloxane (PDMS) pattern to another PET substrate. Purely taking advantage of the anaerobic UV curing adhesive (a-UV) on PET substrate, metal film can be easily peeled off from micro/nano-structured surface. As a result, metal film on the protrusion can be selectively transferred onto the target substrate, to make it the metal functional surface. But which on the bottom can not be transferred. This method provides low cost fabrication of metal thin film devices by avoiding high cost lithography process. Compared with conventional approach, this method can get more smooth rough edges and has wider tolerance range for the original master mold. Future developments and potential applications of this metal transfer method will be addressed.

Damage-free patterning of ferroelectric lead zirconate titanate thin films for microelectromechanical systems via contact printing

NASA Astrophysics Data System (ADS)

Welsh, Aaron

This thesis describes the utilization and optimization of the soft lithographic technique, microcontact printing, to additively pattern ferroelectric lead zirconate titanate (PZT) thin films for application in microelectromechanical systems (MEMS). For this purpose, the solution wetting, pattern transfer, printing dynamics, stamp/substrate configurations, and processing damages were optimized for incorporation of PZT thin films into a bio-mass sensor application. This patterning technique transfers liquid ceramic precursors onto a device stack in a desired configuration either through pattern definition in the stamp, substrate or both surfaces. It was determined that for ideal transfer of the pattern from the stamp to the substrate surface, wetting between the solution and the printing surface is paramount. To this end, polyurethane-based stamp surfaces were shown to be wet uniformly by polar solutions. Patterned stamp surfaces revealed that printing from raised features onto flat substrates could be accomplished with a minimum feature size of 5 mum. Films patterned by printing as a function of thickness (0.1 to 1 mum) showed analogous functional properties to continuous films that were not patterned. Specifically, 1 mum thick PZT printed features had a relative permittivity of 1050 +/- 10 and a loss tangent of 2.0 +/- 0.4 % at 10 kHz; remanent polarization was 30 +/- 0.4 muC/cm 2 and the coercive field was 45 +/- 1 kV/cm; and a piezoelectric coefficient e31,f of -7 +/- 0.4 C/m2. No pinching in the minor hysteresis loops or splitting of the first order reversal curve (FORC) distributions was observed. Non-uniform distribution of the solution over the printed area becomes more problematic as feature size is decreased. This resulted in solutions printed from 5 mum wide raised features exhibiting a parabolic shape with sidewall angles of ˜ 1 degree. As an alternative, printing solutions from recesses in the stamp surface resulted in more uniform solution thickness transfer across the entire feature widths, with increased sidewall angles of ˜ 35 degrees. This was at the cost of degrading line edge definition from ˜ 200 nm to ˜ 500 nm. The loss of line edge definition was mitigated through the combined use of printing from stamp recesses onto raised substrate features. This allowed for printing of PZT features down to 1 mum wide. Solutions could also be transferred onto both fixed and free standing cantilever structures patterned into a substrate surface. Optimization of the stamp removal from the substrate was crucial in increasing sidewall angles of printed PZT films. It was determined that solutions gel once deposited onto the stamp before printing. As a result, printed films could not redistribute easily after transfer had occurred. Through a combination of varying peeling directions and peeling rates, it was possible to deposit thin film PZT on a pre patterned feature ˜ 1 mum wide with sidewall angles > 80 degrees. These printing techniques were utilized in printing a 250 nm thick 30/70 PZT onto prepatterned cantilever structures for use in a bio-functionalized, mass sensing resonating structure in collaboration with a bio-nanoelectromechincal sensing research group from the University of Toulouse, France. The features ranged in lateral size from 30 down to 1 mum. The printed devices exhibited a relative permittivity of 500 +/- 10 and a loss tangent of 0.9 +/- 0.1 %. The hysteresis loops were well formed, without pinching of the loops, and exhibited remanent polarizations of 24 +/- 0.5 muC/cm2, and coercive fields of 110 +/- 1 kV/cm. Dry etched features of the same size and thickness displayed a relative permittivity of 445 +/- 8 and a loss tangent of 0.9 +/- 0.1 %. The hysteresis loops exhibited pinched loops with remanent polarizations of 24 +/- 0.7 muC/cm2, and coercive fields of 112 +/- 2 kV/cm. Upon cycling, the dry etched films developed a 20 kV/cm imprint with reduced remanent polarizations to 20.5 +/- 0.5 muC/cm2 .

Transfer of graphene onto Pt/Glass substrate for transparent and large area graphene film using low temperature water bath

NASA Astrophysics Data System (ADS)

Aziz, Tengku Norazman Tengku Abd; Rosli, Aimi Bazilah; Yusoff, Marmeezee Mohd; Herman, Sukreen Hana; Zulkifli, Zurita

2018-05-01

This paper demonstrates the transfer of graphene at low temperature using water bath. Graphene in water solution (highly opaque) was transferred onto Platinum/Glass (Pt/Glass) substrate and the technique involves no additional chemicals. We obtained high transparency and large area of graphene film that is free of contaminants. The transferred graphene is characterized using FESEM, Raman spectroscopy and I-V measurements. This transfer method enables us to transfer graphene onto ZnO thin film for memristive devices.

Modification of graphene by ion beam

NASA Astrophysics Data System (ADS)

Gawlik, G.; Ciepielewski, P.; Jagielski, J.; Baranowski, J.

2017-09-01

Ion induced defect generation in graphene was analyzed using Raman spectroscopy. A single layer graphene membrane produced by chemical vapor deposition (CVD) on copper foil and then transferred on glass substrate was subjected to helium, carbon, nitrogen, argon and krypton ions bombardment at energies from the range 25 keV to 100 keV. A density of ion induced defects and theirs mean size were estimated by using Raman measurements. Increasing number of defects generated by ion with increase of ion mass and decrease of ion energy was observed. Dependence of ion defect efficiency (defects/ion) on ion mass end energy was proportional to nuclear stopping power simulated by SRIM. No correlation between ion defect efficiency and electronic stopping power was observed.

A tunable sub-100 nm silicon nanopore array with an AAO membrane mask: reducing unwanted surface etching by introducing a PMMA interlayer

NASA Astrophysics Data System (ADS)

Lim, Namsoo; Pak, Yusin; Kim, Jin Tae; Hwang, Youngkyu; Lee, Ryeri; Kumaresan, Yogeenth; Myoung, Nosoung; Ko, Heung Cho; Jung, Gun Young

2015-08-01

Highly ordered silicon (Si) nanopores with a tunable sub-100 nm diameter were fabricated by a CF4 plasma etching process using an anodic aluminum oxide (AAO) membrane as an etching mask. To enhance the conformal contact of the AAO membrane mask to the underlying Si substrate, poly(methyl methacrylate) (PMMA) was spin-coated on top of the Si substrate prior to the transfer of the AAO membrane. The AAO membrane mask was fabricated by two-step anodization and subsequent removal of the aluminum support and the barrier layer, which was then transferred to the PMMA-coated Si substrate. Contact printing was performed on the sample with a pressure of 50 psi and a temperature of 120 °C to make a conformal contact of the AAO membrane mask to the Si substrate. The CF4 plasma etching was conducted to transfer nanopores onto the Si substrate through the PMMA interlayer. The introduced PMMA interlayer prevented unwanted surface etching of the Si substrate by eliminating the etching ions and radicals bouncing at the gap between the mask and the substrate, resulting in a smooth Si nanopore array.Highly ordered silicon (Si) nanopores with a tunable sub-100 nm diameter were fabricated by a CF4 plasma etching process using an anodic aluminum oxide (AAO) membrane as an etching mask. To enhance the conformal contact of the AAO membrane mask to the underlying Si substrate, poly(methyl methacrylate) (PMMA) was spin-coated on top of the Si substrate prior to the transfer of the AAO membrane. The AAO membrane mask was fabricated by two-step anodization and subsequent removal of the aluminum support and the barrier layer, which was then transferred to the PMMA-coated Si substrate. Contact printing was performed on the sample with a pressure of 50 psi and a temperature of 120 °C to make a conformal contact of the AAO membrane mask to the Si substrate. The CF4 plasma etching was conducted to transfer nanopores onto the Si substrate through the PMMA interlayer. The introduced PMMA interlayer prevented unwanted surface etching of the Si substrate by eliminating the etching ions and radicals bouncing at the gap between the mask and the substrate, resulting in a smooth Si nanopore array. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02786a

Knowledge-transfer learning for prediction of matrix metalloprotease substrate-cleavage sites.

PubMed

Wang, Yanan; Song, Jiangning; Marquez-Lago, Tatiana T; Leier, André; Li, Chen; Lithgow, Trevor; Webb, Geoffrey I; Shen, Hong-Bin

2017-07-18

Matrix Metalloproteases (MMPs) are an important family of proteases that play crucial roles in key cellular and disease processes. Therefore, MMPs constitute important targets for drug design, development and delivery. Advanced proteomic technologies have identified type-specific target substrates; however, the complete repertoire of MMP substrates remains uncharacterized. Indeed, computational prediction of substrate-cleavage sites associated with MMPs is a challenging problem. This holds especially true when considering MMPs with few experimentally verified cleavage sites, such as for MMP-2, -3, -7, and -8. To fill this gap, we propose a new knowledge-transfer computational framework which effectively utilizes the hidden shared knowledge from some MMP types to enhance predictions of other, distinct target substrate-cleavage sites. Our computational framework uses support vector machines combined with transfer machine learning and feature selection. To demonstrate the value of the model, we extracted a variety of substrate sequence-derived features and compared the performance of our method using both 5-fold cross-validation and independent tests. The results show that our transfer-learning-based method provides a robust performance, which is at least comparable to traditional feature-selection methods for prediction of MMP-2, -3, -7, -8, -9 and -12 substrate-cleavage sites on independent tests. The results also demonstrate that our proposed computational framework provides a useful alternative for the characterization of sequence-level determinants of MMP-substrate specificity.

Indium-bump-free antimonide superlattice membrane detectors on silicon substrates

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

Zamiri, M., E-mail: mzamiri@chtm.unm.edu, E-mail: skrishna@chtm.unm.edu; Klein, B.; Schuler-Sandy, T.

2016-02-29

We present an approach to realize antimonide superlattices on silicon substrates without using conventional Indium-bump hybridization. In this approach, PIN superlattices are grown on top of a 60 nm Al{sub 0.6}Ga{sub 0.4}Sb sacrificial layer on a GaSb host substrate. Following the growth, the individual pixels are transferred using our epitaxial-lift off technique, which consists of a wet-etch to undercut the pixels followed by a dry-stamp process to transfer the pixels to a silicon substrate prepared with a gold layer. Structural and optical characterization of the transferred pixels was done using an optical microscope, scanning electron microscopy, and photoluminescence. The interface betweenmore » the transferred pixels and the new substrate was abrupt, and no significant degradation in the optical quality was observed. An Indium-bump-free membrane detector was then fabricated using this approach. Spectral response measurements provided a 100% cut-off wavelength of 4.3 μm at 77 K. The performance of the membrane detector was compared to a control detector on the as-grown substrate. The membrane detector was limited by surface leakage current. The proposed approach could pave the way for wafer-level integration of photonic detectors on silicon substrates, which could dramatically reduce the cost of these detectors.« less

Scalable alignment and transfer of nanowires in a Spinning Langmuir Film.

PubMed

Zhu, Ren; Lai, Yicong; Nguyen, Vu; Yang, Rusen

2014-10-21

Many nanomaterial-based integrated nanosystems require the assembly of nanowires and nanotubes into ordered arrays. A generic alignment method should be simple and fast for the proof-of-concept study by a researcher, and low-cost and scalable for mass production in industries. Here we have developed a novel Spinning-Langmuir-Film technique to fulfill both requirements. We used surfactant-enhanced shear flow to align inorganic and organic nanowires, which could be easily transferred to other substrates and ready for device fabrication in less than 20 minutes. The aligned nanowire areal density can be controlled in a wide range from 16/mm(-2) to 258/mm(-2), through the compression of the film. The surface surfactant layer significantly influences the quality of alignment and has been investigated in detail.

Depolarization after resonance energy transfer (DARET): a sensitive fluorescence-based assay for botulinum neurotoxin protease activity.

PubMed

Gilmore, Marcella A; Williams, Dudley; Okawa, Yumiko; Holguin, Bret; James, Nicholas G; Ross, Justin A; Roger Aoki, K; Jameson, David M; Steward, Lance E

2011-06-01

The DARET (depolarization after resonance energy transfer) assay is a coupled Förster resonance energy transfer (FRET)-fluorescence polarization assay for botulinum neurotoxin type A or E (BoNT/A or BoNT/E) proteolytic activity that relies on a fully recombinant substrate. The substrate consists of blue fluorescent protein (BFP) and green fluorescent protein (GFP) flanking SNAP-25 (synaptosome-associated protein of 25 kDa) residues 134-206. In this assay, the substrate is excited with polarized light at 387 nm, which primarily excites the BFP, whereas emission from the GFP is monitored at 509 nm. Energy transfer from the BFP to the GFP in the intact substrate results in a substantial depolarization of the GFP emission. The energy transfer is eliminated when the fluorescent domains separate on cleavage by the endopeptidase, and emission from the directly excited GFP product fragment is then highly polarized, resulting in an overall increase in polarization. This increase in polarization can be monitored to assay the proteolytic activity of BoNT/A and BoNT/E in real time. It allows determination of the turnover rate of the substrate and the kinetic constants (V(max) and k(cat)) based on the concentration of cleaved substrate determined directly from the measurements using the additivity properties of polarization. The assay is amenable to high-throughput applications. Copyright © 2011 Elsevier Inc. All rights reserved.

Fabricating metal-oxide-semiconductor field-effect transistors on a polyethylene terephthalate substrate by applying low-temperature layer transfer of a single-crystalline silicon layer by meniscus force

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

Sakaike, Kohei; Akazawa, Muneki; Nakamura, Shogo

2013-12-02

A low-temperature local-layer technique for transferring a single-crystalline silicon (c-Si) film by using a meniscus force was proposed, and an n-channel metal-oxide-semiconductor field-effect transistor (MOSFET) was fabricated on polyethylene terephthalate (PET) substrate. It was demonstrated that it is possible to transfer and form c-Si films in the required shape at the required position on PET substrates at extremely low temperatures by utilizing a meniscus force. The proposed technique for layer transfer was applied for fabricating high-performance c-Si MOSFETs on a PET substrate. The fabricated MOSFET showed a high on/off ratio of more than 10{sup 8} and a high field-effect mobilitymore » of 609 cm{sup 2} V{sup −1} s{sup −1}.« less

A novel continuous two-phase partitioning bioreactor operated with polymeric tubing: Performance validation for enhanced biological removal of toxic substrates.

PubMed

Tomei, M Concetta; Mosca Angelucci, Domenica; Daugulis, Andrew J

2017-02-01

A continuous two-phase partitioning bioreactor (C-TPPB), operated with coiled tubing made of the DuPont polymer Hytrel 8206, was tested for the bioremediation of 4-chlorophenol, as a model toxic compound. The tubing was immersed in the aqueous phase, with the contaminated water flowing tube-side, and an adapted microbial culture suspended in the bioreactor itself, with the metabolic demand of the cells creating a concentration gradient to cause the substrate to diffuse into the bioreactor for biodegradation. The system was operated over a range of loadings (tubing influent concentration 750-1500 mg L -1 ), with near-complete substrate removal in all cases. Distribution of the contaminant at the end of the tests (96 h) highlighted biological removal in the range of 87-95%, while the amount retained in the polymer ranged from ∼1 to 8%. Mass transfer of the substrate across the tubing wall was not limiting, and the polymer demonstrated the capacity to buffer the substrate loadings and to adapt to microbial metabolism. The impact of C-TPPB operation on biomass activity was also investigated by a kinetic characterization of the microbial culture, which showed better resistance to substrate inhibition after C-TPPB operation, thereby confirming the beneficial effect of sub-inhibitory controlled conditions, characteristic of TPPB systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cultivation of E. coli in single- and ten-stage tower-loop reactors.

PubMed

Adler, I; Schügerl, K

1983-02-01

E. Coli was cultivated in batch and continuous operations in the presence of an antifoam agent in stirred-tank and in single- and ten-stage airlift tower reactors with an outer loop. The maximum specific growth rate, mu(m), the substrate yield coefficient, Y(x/s), the respiratory quotient, RQ, substrate conversion, U(s), the volumetric mass transfer coefficient, K(L)a, the specific interfacial area, a, and the specific power input, P/V(L), were measured and compared. If a medium is used with a concentration of complex substrates (extracts) 2.5 times higher than that of glucose, a spectrum of C sources is available and cell regulation influences reactor performance. Both mu(m) and Y(X/S), which were evaluated in batch reactors, cannot be used for continuous reactors or, when measured in stirred-tank reactors, cannot be employed for tower-loop reactors: mu(m) is higher in the stirred-tank batch than in the tower-loop batch reactor, mu(m) and Y(x/s) are higher in the continuous reactor than in the batch single-stage tower-loop reactor. The performance of the single-stage is better than that of the ten-stage reactor due to the inefficient trays employed. A reduction of the medium recirculation rate reduces OTR, U(s), Pr, and Y(X/S) and causes cell sedimentation and flocculation. The volumetric mass transfer coefficient is reduced with increasing cultivation time; the Sauter bubble diameter, d(s), remains constant and does not depend on operational conditions. An increase in the medium recirculation rate reduces k(L)a. The specific power input, P/V(L), for the single-stage tower loop is much lower with the same k(L)a value than for a stirred tank. The relationship k(L)a vs. P/V(L) evaluated for model media in stirred tanks, can also be used for cultivations in these reactors.

Modeling enzyme production with Aspergillus oryzae in pilot scale vessels with different agitation, aeration, and agitator types.

PubMed

Albaek, Mads O; Gernaey, Krist V; Hansen, Morten S; Stocks, Stuart M

2011-08-01

The purpose of this article is to demonstrate how a model can be constructed such that the progress of a submerged fed-batch fermentation of a filamentous fungus can be predicted with acceptable accuracy. The studied process was enzyme production with Aspergillus oryzae in 550 L pilot plant stirred tank reactors. Different conditions of agitation and aeration were employed as well as two different impeller geometries. The limiting factor for the productivity was oxygen supply to the fermentation broth, and the carbon substrate feed flow rate was controlled by the dissolved oxygen tension. In order to predict the available oxygen transfer in the system, the stoichiometry of the reaction equation including maintenance substrate consumption was first determined. Mainly based on the biomass concentration a viscosity prediction model was constructed, because rising viscosity of the fermentation broth due to hyphal growth of the fungus leads to significant lower mass transfer towards the end of the fermentation process. Each compartment of the model was shown to predict the experimental results well. The overall model can be used to predict key process parameters at varying fermentation conditions. Copyright © 2011 Wiley Periodicals, Inc.

Biodegradation of paint stripper solvents in a modified gas lift loop bioreactor.

PubMed

Vanderberg-Twary, L; Steenhoudt, K; Travis, B J; Hanners, J L; Foreman, T M; Brainard, J R

1997-07-05

Paint stripping wastes generated during the decontamination and decommissioning of former nuclear facilities contain paint stripping organics (dichloromethane, 2-propanol, and methanol) and bulk materials containing paint pigments. It is desirable to degrade the organic residues as part of an integrated chemical-biological treatment system. We have developed a modified gas lift loop bioreactor employing a defined consortium of Rhodococcus rhodochrous strain OFS and Hyphomicrobium sp. DM-2 that degrades paint stripper organics. Mass transfer coefficients and kinetic constants for biodegradation in the system were determined. It was found that transfer of organic substrates from surrogate waste into the air and further into the liquid medium in the bioreactor were rapid processes, occurring within minutes. Monod kinetics was employed to model the biodegradation of paint stripping organics. Analysis of the bioreactor process was accomplished with BIOLAB, a mathematical code that simulates coupled mass transfer and biodegradation processes. This code was used to fit experimental data to Monod kinetics and to determine kinetic parameters. The BIOLAB code was also employed to compare activities in the bioreactor of individual microbial cultures to the activities of combined cultures in the bioreactor. This code is of benefit for further optimization and scale-up of the bioreactor for treatment of paint stripping and other volatile organic wastes in bulk materials.

Sulfur K-edge X-ray absorption spectroscopy and density functional theory calculations on monooxo Mo(IV) and bisoxo Mo(VI) bis-dithiolenes: insights into the mechanism of oxo transfer in sulfite oxidase and its relation to the mechanism of DMSO reductase.

PubMed

Ha, Yang; Tenderholt, Adam L; Holm, Richard H; Hedman, Britt; Hodgson, Keith O; Solomon, Edward I

2014-06-25

Sulfur K-edge X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations have been used to determine the electronic structures of two complexes [Mo(IV)O(bdt)2](2-) and [Mo(VI)O2(bdt)2](2-) (bdt = benzene-1,2-dithiolate(2-)) that relate to the reduced and oxidized forms of sulfite oxidase (SO). These are compared with those of previously studied dimethyl sulfoxide reductase (DMSOr) models. DFT calculations supported by the data are extended to evaluate the reaction coordinate for oxo transfer to a phosphite ester substrate. Three possible transition states are found with the one at lowest energy, stabilized by a P-S interaction, in good agreement with experimental kinetics data. Comparison of both oxo transfer reactions shows that in DMSOr, where the oxo is transferred from the substrate to the metal ion, the oxo transfer induces electron transfer, while in SO, where the oxo transfer is from the metal site to the substrate, the electron transfer initiates oxo transfer. This difference in reactivity is related to the difference in frontier molecular orbitals (FMO) of the metal-oxo and substrate-oxo bonds. Finally, these experimentally related calculations are extended to oxo transfer by sulfite oxidase. The presence of only one dithiolene at the enzyme active site selectively activates the equatorial oxo for transfer, and allows facile structural reorganization during turnover.

Transferable ordered ni hollow sphere arrays induced by electrodeposition on colloidal monolayer.

PubMed

Duan, Guotao; Cai, Weiping; Li, Yue; Li, Zhigang; Cao, Bingqiang; Luo, Yuanyuan

2006-04-13

We report an electrochemical synthesis of two-dimensionally ordered porous Ni arrays based on polystyrene sphere (PS) colloidal monolayer. The morphology can be controlled from bowl-like to hollow sphere-like structure by changing deposition time under a constant current. Importantly, such ordered Ni arrays on a conducting substrate can be transferred integrally to any other desired substrates, especially onto an insulting substrate or curved surface. The magnetic measurements of the two-dimensional hollow sphere array show the coercivity values of 104 Oe for the applied field parallel to the film, and 87 Oe for the applied field perpendicular to the film, which is larger than those of bulk Ni and hollow Ni submicrometer-sized spheres. The formation of hollow sphere arrays is attributed to preferential nucleation on the interstitial sites between PS in the colloidal monolayer and substrate, and growth along PSs' surface. The transferability of the arrays originates from partial contact between the Ni hollow spheres and substrate. Such novel Ni ordered nanostructured arrays with transferability and high magnetic properties should be useful in applications such as data storage, catalysis, and magnetics.

Organic photochemical storage of solar energy. Progress report, February 1, 1979-January 31, 1980

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

Jones, G. II

1980-02-01

Study of valence isomerization of organic compounds has focused on two mechanisms of photosensitization involving either electron donor-acceptor interaction or energy transfer. The quenching of fluorescent sensitizers by isomerizable substrates results in the formation of excited complexes. These sensitizer-substrate pairs are highly polarized, leading to changes in bond order for the substrates. For several substrates such as quadricyclene, hexamethyldewarbenzene, and a nonbornadiene derivative, this perturbation results in efficient valence isomerization. Isomerization observed on irradiation of charge transfer complexes of isomerizable substrates is consistent with a similar exciplex - template mechanism. The energy transfer mechanism of photosensitization has been studied bymore » measuring the temperature dependence of quantum yield for isomerization of dimethyl norbornadiene-2,3-dicarboxylate sensitized by benzanthrone. From temperature and quencher concentration profiles quenching constants have been obtained which are consistent with an endoergic triplet energy transfer mechanism. The thermal upconversion of the low energy triplet of benzanthrone results in a threefold increase in isomerization quantum yield over a 90/sup 0/ temperature range.« less

Pulsed laser induced heat transfer from a phthalocyanine-based thin film to a Bi, Al-substituted DyIG substrate: photothermal demagnetization observed by magnetic circular dichroism and numerical analysis.

PubMed

Karasawa, Masanobu; Ishii, Kazuyuki

2018-05-03

We have investigated the demagnetization of a ferrimagnetic substrate, Bi, Al-substituted dysprosium iron garnet (Bi0.8Dy2.2Fe4.3Al0.7O12), based on selective pulsed laser irradiation of a molecular thin film consisting of μ-oxo-bis[hydroxyl{2,9(or 10),16(or 17),23(or 24)-tetra-tert-butylphthalocyanato}silicon] ((SiPc)2) and poly(vinylidene fluoride), and succeeded in reproducing photothermal energy transfer from a molecular thin film to an inorganic magnetic substrate in a submicrometer-order and a submicrosecond time scale using numerical analysis. After the instant temperature rise due to nanosecond pulsed laser irradiation of the (SiPc)2-based film, followed by heat transfer from the film to the neighboring magnetic substrate, demagnetization of the magnetic substrate was spectroscopically monitored by the decrease in its magnetic circular dichroism (MCD) intensity. The MCD intensity decreased with increasing pulsed laser energy, which reflects the fact that the submicrometer-order region of the substrate was demagnetized as a result of temperature rise reaching high Curie temperature. This heat transfer phenomenon resulting in the demagnetization of the magnetic substrate was numerically analyzed in a submicrometer-order and a submicrosecond time scale using the finite difference method: the demagnetized regions were calculated to be the same order of magnitude as those experimentally evaluated. These results would provide a more detailed understanding of photothermal energy transfer in organic-inorganic hybrid materials, which would be useful for developing photofunctional materials.

Transfer of Graphene Layers Grown on SiC Wafers to Other Substrates and Their Integration into Field Effect Transistors

NASA Astrophysics Data System (ADS)

Unarunotai, Sakulsuk; Murata, Yuya; Chialvo, Cesar; Kim, Hoon-Sik; MacLaren, Scott; Mason, Nadya; Petrov, Ivan; Rogers, John

2010-03-01

An approach to produce graphene films by epitaxial growth on silicon carbide substrate is promising, but its current implementation requires the use of SiC as the device substrate. We present a simple method for transferring epitaxial sheets of graphene on SiC to other substrates. The graphene was grown on the (0001) face of 6H-SiC by thermal annealing in a hydrogen atmosphere. Transfer was accomplished using a peeling process with a bilayer film of Gold/polyimide, to yield graphene with square millimeters of coverage on the target substrate. Back gated field-effect transistors fabricated on oxidized silicon substrates with Cr/Au as source-drain electrodes exhibited ambipolar characteristics with hole mobilities of ˜100 cm^2/V-s, and negligible influence of resistance at the contacts. This work was supported by the U.S. DOE, under Award No. DE-FG02-07ER46471, through the Frederick Seitz Materials Research Laboratory at the University of Illinois at Urbana-Champaign.

Automatic graphene transfer system for improved material quality and efficiency

PubMed Central

Boscá, Alberto; Pedrós, Jorge; Martínez, Javier; Palacios, Tomás; Calle, Fernando

2016-01-01

In most applications based on chemical vapor deposition (CVD) graphene, the transfer from the growth to the target substrate is a critical step for the final device performance. Manual procedures are time consuming and depend on handling skills, whereas existing automatic roll-to-roll methods work well for flexible substrates but tend to induce mechanical damage in rigid ones. A new system that automatically transfers CVD graphene to an arbitrary target substrate has been developed. The process is based on the all-fluidic manipulation of the graphene to avoid mechanical damage, strain and contamination, and on the combination of capillary action and electrostatic repulsion between the graphene and its container to ensure a centered sample on top of the target substrate. The improved carrier mobility and yield of the automatically transferred graphene, as compared to that manually transferred, is demonstrated by the optical and electrical characterization of field-effect transistors fabricated on both materials. In particular, 70% higher mobility values, with a 30% decrease in the unintentional doping and a 10% strain reduction are achieved. The system has been developed for lab-scale transfer and proved to be scalable for industrial applications. PMID:26860260

Gas diffusion electrodes improve hydrogen gas mass transfer for a hydrogen oxidizing bioanode

PubMed Central

Rodenas, Pau; Zhu, Fangqi; Sleutels, Tom; Saakes, Michel; Buisman, Cees

2017-01-01

Abstract Background Bioelectrochemical systems (BESs) are capable of recovery of metals at a cathode through oxidation of organic substrate at an anode. Recently, also hydrogen gas was used as an electron donor for recovery of copper in BESs. Oxidation of hydrogen gas produced a current density of 0.8 A m‐2 and combined with Cu2+ reduction at the cathode, produced 0.25 W m‐2. The main factor limiting current production was the mass transfer of hydrogen to the biofilm due to the low solubility of hydrogen in the anolyte. Here, the mass transfer of hydrogen gas to the bioanode was improved by use of a gas diffusion electrode (GDE). Results With the GDE, hydrogen was oxidized to produce a current density of 2.9 A m‐2 at an anode potential of –0.2 V. Addition of bicarbonate to the influent led to production of acetate, in addition to current. At a bicarbonate concentration of 50 mmol L‐1, current density increased to 10.7 A m‐2 at an anode potential of –0.2 V. This increase in current density could be due to oxidation of formed acetate in addition to oxidation of hydrogen, or enhanced growth of hydrogen oxidizing bacteria due to the availability of acetate as carbon source. The effect of mass transfer was further assessed through enhanced mixing and in combination with the addition of bicarbonate (50 mmol L‐1) current density increased further to 17.1 A m‐2. Conclusion Hydrogen gas may offer opportunities as electron donor for bioanodes, with acetate as potential intermediate, at locations where excess hydrogen and no organics are available. © 2017 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. PMID:29200586

Boron nitride nanotubes matrix for signal enhancement in infrared laser desorption postionization mass spectrometry.

PubMed

Lu, Qiao; Hu, Yongjun; Chen, Jiaxin; Li, Yujian; Song, Wentao; Jin, Shan; Liu, Fuyi; Sheng, Liusi

2018-09-01

The nanomaterials function as the substrate to trap analytes, absorb energy from the laser irradiation and transfer energy to the analytes to facilitate the laser desorption process. In this work, the signal intensity and reproducibility of analytes with nanomaterials as matrices were explored by laser desorption postionization mass spectrometry (LDPI-MS). Herein, the desorbed neutral species were further ionized by vacuum ultraviolet (VUV, 118 nm) and analyzed by mass spectrometer. Compared with other nanomaterial matrices such as graphene and carbon nanotubes (CNTs), boron nitride nanotubes (BNNTs) exhibited much higher desorption efficiency under infrared (IR) light and produced no background signal in the whole mass range by LDPI-MS. Additionally, this method was successfully and firstly exploited to in situ detection and imaging for drugs of low concentration in intact tissues, which proved the utility, facility and convenience of this method applied in drug discovery and biomedical research. Copyright © 2018 Elsevier B.V. All rights reserved.

Dioxygen in Polyoxometalate Mediated Reactions.

PubMed

Weinstock, Ira A; Schreiber, Roy E; Neumann, Ronny

2018-03-14

In this review article, we consider the use of molecular oxygen in reactions mediated by polyoxometalates. Polyoxometalates are anionic metal oxide clusters of a variety of structures that are soluble in liquid phases and therefore amenable to homogeneous catalytic transformations. Often, they are active for electron transfer oxidations of a myriad of substrates and upon reduction can be reoxidized by molecular oxygen. For example, the phosphovanadomolybdate, H 5 PV 2 Mo 10 O 40 , can oxidize Pd(0) thereby enabling aerobic reactions catalyzed by Pd and H 5 PV 2 Mo 10 O 40 . In a similar vein, polyoxometalates can stabilize metal nanoparticles, leading to additional transformations. Furthermore, electron transfer oxidation of other substrates such as halides and sulfur-containing compounds is possible. More uniquely, H 5 PV 2 Mo 10 O 40 and its analogues can mediate electron transfer-oxygen transfer reactions where oxygen atoms are transferred from the polyoxometalate to the substrate. This unique property has enabled correspondingly unique transformations involving carbon-carbon, carbon-hydrogen, and carbon-metal bond activation. The pathway for the reoxidation of vanadomolybdates with O 2 appears to be an inner-sphere reaction, but the oxidation of one-electron reduced polyoxotungstates has been shown through intensive research to be an outer-sphere reaction. Beyond electron transfer and electron transfer-oxygen transfer aerobic transformations, there a few examples of apparent dioxygenase activity where both oxygen atoms are donated to a substrate.

Wax transfer printing to enable robust barrier definition in devices based on non-standard porous materials

NASA Astrophysics Data System (ADS)

To, Anthony; Downs, Corey; Fu, Elain

2017-05-01

Wax printing has become a common method of fabricating channels in cellulose-based microfluidic devices. However, a limitation of wax printing is that it is restricted to relatively thin, smooth substrates that are compatible with processing by a commercial wax printer. In the current report, we describe a simple patterning method that extends the utility of wax printers for creating hydrophobic barriers on non-standard porous substrates via a process called wax transfer printing. We demonstrate the use of multiple wax transfer cycles to create well-defined, robust, and reproducible barriers in a thick cellulose substrate that is not compatible with feeding through a wax printer. We characterize the method for (i) wax spreading within the substrate as a function of heating time, (ii) the ability to create functional barriers in a substrate, and (iii) reproducibility in line width.

Sublimation-assisted graphene transfer technique based on small polyaromatic hydrocarbons

NASA Astrophysics Data System (ADS)

Chen, Mingguang; Stekovic, Dejan; Li, Wangxiang; Arkook, Bassim; Haddon, Robert C.; Bekyarova, Elena

2017-06-01

Advances in the chemical vapor deposition (CVD) growth of graphene have made this material a very attractive candidate for a number of applications including transparent conductors, electronics, optoeletronics, biomedical devices and energy storage. The CVD method requires transfer of graphene on a desired substrate and this is most commonly accomplished with polymers. The removal of polymer carriers is achieved with organic solvents or thermal treatment which makes this approach inappropriate for application to plastic thin films such as polyethylene terephthalate substrates. An ultraclean graphene transfer method under mild conditions is highly desired. In this article, we report a naphthalene-assisted graphene transfer technique which provides a reliable route to residue-free transfer of graphene to both hard and flexible substrates. The quality of the transferred graphene was characterized with atomic force microscopy, scanning electron microscopy, and Raman spectroscopy. Field effect transistors, based on the naphthalene-transfered graphene, were fabricated and characterized. This work has the potential to broaden the applications of CVD graphene in fields where ultraclean graphene and mild graphene transfer conditions are required.

Development of Fluorescent Substrates and Assays for the Key Autophagy-Related Cysteine Protease Enzyme, ATG4B

PubMed Central

Nguyen, Thanh G.; Honson, Nicolette S.; Arns, Steven; Davis, Tara L.; Dhe-Paganon, Sirano; Kovacic, Suzana; Kumar, Nag S.; Pfeifer, Tom A.

2014-01-01

Abstract The cysteine protease ATG4B plays a role in key steps of the autophagy process and is of interest as a potential therapeutic target. At an early step, ATG4B cleaves proLC3 isoforms to form LC3-I for subsequent lipidation to form LC3-II and autophagosome membrane insertion. ATG4B also cleaves phosphatidylethanolamine (PE) from LC3-II to regenerate LC3-I, enabling its recycling for further membrane biogenesis. Here, we report several novel assays for monitoring the enzymatic activity of ATG4B. An assay based on mass spectrometric analysis and quantification of cleavage of the substrate protein LC3-B was developed and, while useful for mechanistic studies, was not suitable for high throughput screening (HTS). A doubly fluorescent fluorescence resonance energy transfer (FRET) ligand YFP-LC3B-EmGFP (FRET-LC3) was constructed and shown to be an excellent substrate for ATG4B with rates of cleavage similar to that for LC3B itself. A HTS assay to identify candidate inhibitors of ATG4B utilizing FRET-LC3 as a substrate was developed and validated with a satisfactory Z′ factor and high signal-to-noise ratio suitable for screening small molecule libraries. Pilot screens of the 1,280-member library of pharmacologically active compounds (LOPAC™) and a 3,481-member library of known drugs (KD2) gave hit rates of 0.6% and 0.5% respectively, and subsequent titrations confirmed ATG4B inhibitory activity for three compounds, both in the FRET and mass spectrometry assays. The FRET- and mass spectrometry–based assays we have developed will allow for both HTS for inhibitors of ATG4B and mechanistic approaches to study inhibition of a major component of the autophagy pathway. PMID:24735444

Direct Substrate Identification with an Analog Sensitive (AS) Viral Cyclin-Dependent Kinase (v-Cdk).

PubMed

Umaña, Angie C; Iwahori, Satoko; Kalejta, Robert F

2018-01-19

Viral cyclin-dependent kinases (v-Cdks) functionally emulate their cellular Cdk counterparts. Such viral mimicry is an established phenomenon that we extend here through chemical genetics. Kinases contain gatekeeper residues that limit the size of molecules that can be accommodated within the enzyme active site. Mutating gatekeeper residues to smaller amino acids allows larger molecules access to the active site. Such mutants can utilize bio-orthoganol ATPs for phosphate transfer and are inhibited by compounds ineffective against the wild type protein, and thus are referred to as analog-sensitive (AS) kinases. We identified the gatekeeper residues of the v-Cdks encoded by Epstein-Barr virus (EBV) and human cytomegalovirus (HCMV) and mutated them to generate AS kinases. The AS-v-Cdks are functional and utilize different ATP derivatives with a specificity closely matching their cellular ortholog, AS-Cdk2. The AS derivative of the EBV v-Cdk was used to transfer a thiolated phosphate group to targeted proteins which were then purified through covalent capture and identified by mass spectrometry. Pathway analysis of these newly identified direct substrates of the EBV v-Cdk extends the potential influence of this kinase into all stages of gene expression (transcription, splicing, mRNA export, and translation). Our work demonstrates the biochemical similarity of the cellular and viral Cdks, as well as the utility of AS v-Cdks for substrate identification to increase our understanding of both viral infections and Cdk biology.

Enhanced production of poly(3-hydroxybutyrate) in a novel airlift reactor with in situ cell retention using Azohydromonas australica.

PubMed

Gahlawat, Geeta; Sengupta, Bedoshree; Srivastava, Ashok K

2012-09-01

Economic production of biodegradable plastics is a challenge particularly because of high substrate and energy cost inputs for its production. Research efforts are being directed towards innovations to minimize both of the above costs to economize polyhydroxybutyrate (PHB) production. A novel airlift reactor (ALR) with outer aeration and internal settling was utilized in this investigation. Although it featured no power consumption for agitation, it facilitated increased oxygen transfer rate and better cell retention than stirred tank reactor (STR), thereby resulting in enhanced PHB productivity. ALR with in situ cell retention demonstrated a significant improvement in biomass concentration and biopolymer accumulation. The total PHB production rate, specific biomass, and product yield in the ALR were observed to be 0.84 g/h, 0.43 g/g, and 0.32 g/g, respectively. The studies revealed that the volumetric oxygen mass transfer rate and mixing time for ALR were 0.016 s⁻¹ and 3.73 s, respectively, at 2.0 vvm as compared with corresponding values of 0.005 s⁻¹ and 4.95 s, respectively, in STR. This demonstrated that ALR has better oxygen mass transfer and mixing efficiency than STR. Hence, ALR with cell retention would serve as a better bioreactor design for economic biopolymer production than STR, particularly due to its lower cost of operation and simplicity along with its enhanced oxygen and heat transfer rates.

Container lid gasket protective strip for double door transfer system

DOEpatents

Allen, Jr., Burgess M

2013-02-19

An apparatus and a process for forming a protective barrier seal along a "ring of concern" of a transfer container used with double door systems is provided. A protective substrate is supplied between a "ring of concern" and a safety cover in which an adhesive layer of the substrate engages the "ring of concern". A compressive foam strip along an opposite side of the substrate engages a safety cover such that a compressive force is maintained between the "ring of concern" and the adhesive layer of the substrate.

PMMA-Etching-Free Transfer of Wafer-scale Chemical Vapor Deposition Two-dimensional Atomic Crystal by a Water Soluble Polyvinyl Alcohol Polymer Method

PubMed Central

Van Ngoc, Huynh; Qian, Yongteng; Han, Suk Kil; Kang, Dae Joon

2016-01-01

We have explored a facile technique to transfer large area 2-Dimensional (2D) materials grown by chemical vapor deposition method onto various substrates by adding a water-soluble Polyvinyl Alcohol (PVA) layer between the polymethyl-methacrylate (PMMA) and the 2D material film. This technique not only allows the effective transfer to an arbitrary target substrate with a high degree of freedom, but also avoids PMMA etching thereby maintaining the high quality of the transferred 2D materials with minimum contamination. We applied this method to transfer various 2D materials grown on different rigid substrates of general interest, such as graphene on copper foil, h-BN on platinum and MoS2 on SiO2/Si. This facile transfer technique has great potential for future research towards the application of 2D materials in high performance optical, mechanical and electronic devices. PMID:27616038

One-step synthesis of carbon nanosheets converted from a polycyclic compound and their direct use as transparent electrodes of ITO-free organic solar cells.

PubMed

Son, Su-Young; Noh, Yong-Jin; Bok, Changsuk; Lee, Sungho; Kim, Byoung Gak; Na, Seok-In; Joh, Han-Ik

2014-01-21

Through a catalyst- and transfer-free process, we fabricated indium tin oxide (ITO)-free organic solar cells (OSCs) using a carbon nanosheet (CNS) with properties similar to graphene. The morphological and electrical properties of the CNS derived from a polymer of intrinsic microporosity-1 (PIM-1), which is mainly composed of several aromatic hydrocarbons and cycloalkanes, can be easily controlled by adjusting the polymer concentration. The CNSs, which are prepared by simple spin-coating and heat-treatment on a quartz substrate, are directly used as the electrodes of ITO-free OSCs, showing a high efficiency of approximately 1.922% under 100 mW cm(-2) illumination and air mass 1.5 G conditions. This catalyst- and transfer-free approach is highly desirable for electrodes in organic electronics.

In-Plane Channel-Structured Catalyst Layer for Polymer Electrolyte Membrane Fuel Cells.

PubMed

Lee, Dong-Hyun; Jo, Wonhee; Yuk, Seongmin; Choi, Jaeho; Choi, Sungyu; Doo, Gisu; Lee, Dong Wook; Kim, Hee-Tak

2018-02-07

In this study, we present a novel catalyst layer (CL) with in-plane flow channels to enhance the mass transports in polymer electrolyte membrane fuel cells. The CL with in-plane channels on its surface is fabricated by coating a CL slurry onto a surface-treated substrate with the inverse line pattern and transferring the dried CL from the substrate to a membrane. The membrane electrode assembly with the in-plane channel-patterned CL has superior power performances in high current densities compared with an unpatterned, flat CL, demonstrating a significant enhancement of the mass-transport property by the in-plane channels carved in the CL. The performance gain is more pronounced when the channel direction is perpendicular to the flow field direction, indicating that the in-plane channels increase the utilization of the CL under the rib area. An oxygen-transport resistance analysis shows that both molecular and Knudsen diffusion can be facilitated with the introduction of the in-plane channels. The direct CL patterning technique provides a platform for the fabrication of advanced CL structures with a high structural fidelity and design flexibility and a rational guideline for designing high-performance CLs.

Novel Acoustic Loading of a Mass Spectrometer: Toward Next-Generation High-Throughput MS Screening.

PubMed

Sinclair, Ian; Stearns, Rick; Pringle, Steven; Wingfield, Jonathan; Datwani, Sammy; Hall, Eric; Ghislain, Luke; Majlof, Lars; Bachman, Martin

2016-02-01

High-throughput, direct measurement of substrate-to-product conversion by label-free detection, without the need for engineered substrates or secondary assays, could be considered the "holy grail" of drug discovery screening. Mass spectrometry (MS) has the potential to be part of this ultimate screening solution, but is constrained by the limitations of existing MS sample introduction modes that cannot meet the throughput requirements of high-throughput screening (HTS). Here we report data from a prototype system (Echo-MS) that uses acoustic droplet ejection (ADE) to transfer femtoliter-scale droplets in a rapid, precise, and accurate fashion directly into the MS. The acoustic source can load samples into the MS from a microtiter plate at a rate of up to three samples per second. The resulting MS signal displays a very sharp attack profile and ions are detected within 50 ms of activation of the acoustic transducer. Additionally, we show that the system is capable of generating multiply charged ion species from simple peptides and large proteins. The combination of high speed and low sample volume has significant potential within not only drug discovery, but also other areas of the industry. © 2015 Society for Laboratory Automation and Screening.

The graphene phonon dispersion with C12 and C13 isotopes

NASA Astrophysics Data System (ADS)

Whiteway, Eric; Bernard, Simon; Yu, Victor; Austing, D. Guy; Hilke, Michael

2013-12-01

Using very uniform large scale chemical vapor deposition grown graphene transferred onto silicon, we were able to identify 15 distinct Raman lines associated with graphene monolayers. This was possible thanks to a combination of different carbon isotopes and different Raman laser energies and extensive averaging without increasing the laser power. This allowed us to obtain a detailed experimental phonon dispersion relation for many points in the Brillouin zone. We further identified a D+D' peak corresponding to a double phonon process involving both an inter- and intra-valley phonon. In order to both eliminate substrate effects and to probe large areas, we undertook to study Raman scattering for large scale chemical vapor deposition (CVD) grown graphene using two different isotopes (C12 and C13) so that we can effectively exclude and subtract the substrate contributions, since a heavier mass downshifts only the vibrational properties, while keeping all other properties the same.

Unprecedented covalently attached ATRP initiator onto OH-functionalized mica surfaces.

PubMed

Lego, Béatrice; Skene, W G; Giasson, Suzanne

2008-01-15

Mica substrates were activated by a plasma method leading to OH-functionalized surfaces to which an atom transfer radical polymerization (ATRP) radical initiator was covalently bound using standard siloxane protocols. The unprecedented covalently immobilized initiator underwent radical polymerization with tert-butyl acrylate, yielding for the first time end-grafted polymer brushes that are covalently linked to mica. The initiator grafting on the mica substrate was confirmed by time-of-flight secondary ion mass spectrometry (TOF-SIMS), while the change in the water contact angle of the OH-activated mica surface was used to follow the change in surface coverage of the initiator on the surface. The polymer brush and initiator film thicknesses relative to the virgin mica were confirmed by atomic force microscopy (AFM). This was done by comparing the atomic step-height difference between a protected area of freshly cleaved mica and a zone exposed to plasma activation, initiator immobilization, and then ATRP.

A novel type of thermostable alpha-D-glucosidase from Thermoanaerobacter thermohydrosulfuricus exhibiting maltodextrinohydrolase activity.

PubMed Central

Wimmer, B; Lottspeich, F; Ritter, J; Bronnenmeier, K

1997-01-01

An alpha-glucosidase with the ability to attack polymeric substrates was purified to homogeneity from culture supernatants of Thermoanaerobacter thermohydrosulfuricus DSM 567. The enzyme is apparently a glycoprotein with a molecular mass of 160 kDa. Maximal activity is observed between pH5 and 7 at 75 degrees C. The alpha-glucosidase is active towards p-nitrophenyl-alpha-D-glucoside, maltose, malto-oligosaccharides, starch and pullulan. Highest activity is displayed towards the disaccharide maltose. In addition to glucose, maltohexaose and maltoheptaose can be detected as the initial products of starch hydrolysis. After short incubations of pullulan, glucose is found as the only product. At high substrate concentrations, maltose and malto-oligosaccharide, but not glucose, are used as acceptors for glucosyl-transfer. These findings indicate that the T. thermohydrosulfuricus enzyme represents a novel type of alpha-glucosidase exhibiting maltase, glucohydrolase and 'maltodextrinohydrolase' activity. PMID:9371718

Optical determination of charge transfer times from indoline dyes to ZnO in solid state dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Meyenburg, I.; Hofeditz, N.; Ruess, R.; Rudolph, M.; Schlettwein, D.; Heimbrodt, W.

2018-05-01

We studied the electron transfer at the interface of organic-inorganic hybrids consisting of indoline derivatives (D149 and D131) on ZnO substrates using a new optical method. We revealed the electron transfer times from the excited dye, e.g. the excitons formed in the dye aggregates to the ZnO substrate by analyzing the photoluminescence transients of the excitons after femtosecond excitation and applying kinetic model calculations. We reveal the changes of the electron transfer times by applying electrical bias. Pushing the Fermi energy of the ZnO substrate towards the excited dye level the transfer time gets longer and eventually the electron transfer is suppressed. The level alignment between the excited dye state and the ZnO Fermi-level is estimated. The excited state of D131 is about 100 meV higher than the respective state of D149 compared to the ZnO conduction band. This leads to shorter electron transfer times and eventually to higher quantum efficiencies of the solar cells.

Simulation Approach for Microscale Noncontinuum Gas-Phase Heat Transfer

NASA Astrophysics Data System (ADS)

Torczynski, J. R.; Gallis, M. A.

2008-11-01

In microscale thermal actuators, gas-phase heat transfer from the heated beams to the adjacent unheated substrate is often the main energy-loss mechanism. Since the beam-substrate gap is comparable to the molecular mean free path, noncontinuum gas effects are important. A simulation approach is presented in which gas-phase heat transfer is described by Fourier's law in the bulk gas and by a wall boundary condition that equates the normal heat flux to the product of the gas-solid temperature difference and a heat transfer coefficient. The dimensionless parameters in this heat transfer coefficient are determined by comparison to Direct Simulation Monte Carlo (DSMC) results for heat transfer from beams of rectangular cross section to the substrate at free-molecular to near-continuum gas pressures. This simulation approach produces reasonably accurate gas-phase heat-transfer results for wide ranges of beam geometries and gas pressures. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Fabrication and improved photoelectrochemical properties of a transferred GaN-based thin film with InGaN/GaN layers.

PubMed

Cao, Dezhong; Xiao, Hongdi; Gao, Qingxue; Yang, Xiaokun; Luan, Caina; Mao, Hongzhi; Liu, Jianqiang; Liu, Xiangdong

2017-08-17

Herein, a lift-off mesoporous GaN-based thin film, which consisted of a strong phase-separated InGaN/GaN layer and an n-GaN layer, was fabricated via an electrochemical etching method in a hydrofluoric acid (HF) solution for the first time and then transferred onto quartz or n-Si substrates, acting as photoanodes during photoelectrochemical (PEC) water splitting in a 1 M NaCl aqueous solution. Compared to the as-grown GaN-based film, the transferred GaN-based thin films possess higher and blue-shifted light emission, presumably resulting from an increase in the surface area and stress relaxation in the InGaN/GaN layer embedded on the mesoporous n-GaN. The properties such as (i) high photoconversion efficiency, (ii) low turn-on voltage (-0.79 V versus Ag/AgCl), and (iii) outstanding stability enable the transferred films to have excellent PEC water splitting ability. Furthermore, as compared to the film transferred onto the quartz substrate, the film transferred onto the n-Si substrate exhibits higher photoconversion efficiency (2.99% at -0.10 V) due to holes (h + ) in the mesoporous n-GaN layer that originate from the n-Si substrate.

Stretchable hydrogen sensors employing palladium nanosheets transferred onto an elastomeric substrate

NASA Astrophysics Data System (ADS)

Namgung, Gitae; Ta, Qui Thanh Hoai; Noh, Jin-Seo

2018-07-01

Stretchable hydrogen sensors were fabricated from Pd nanosheets that were transferred onto a PDMS substrate. To prepare the Pd nanosheets, a Pd thin film on PDMS was first biaxially stretched and then PDMS substrate was etched off. The size of Pd nanosheets decreased as the applied strain increased and the film thickness decreased. A transfer technique was utilized to implement the stretchable hydrogen sensors. The stretchable sensors exhibited negative response behaviors upon the exposure to hydrogen gas. Interestingly, the sensors worked even under large strains up to 30%, demonstrating a potential as a high-strain-tolerable hydrogen sensor for the first time.

Electronic structures of 1-ML C84/Ag(111): Energy level alignment and work function variation

NASA Astrophysics Data System (ADS)

Wang, Peng; Zhao, Li-Li; Zhang, Jin-Juan; Li, Wen-Jie; Liu, Wei-Hui; Chen, Da; Sheng, Chun-Qi; Wang, Jia-Ou; Qian, Hai-Jie; Ibrahim, Kurash; Li, Hong-Nian

2017-12-01

The electronic structures of fullerene/metal interface are critical to the performance of devices based on fullerene in molecular electronics and organic electronics. Herein, we investigate the electronic structures at the interface between C84 and Ag(111) by photoelectron spectroscopy and soft X-ray absorption spectroscopy techniques. It is observed that C84 monolayer on Ag(111) surface (1-ML C84/Ag(111)) has metallic nature. A charge transfer from substrate to the unoccupied states of C84 is determined to be 1.3 electrons per molecule. However, the work function of 1-ML C84 (4.72 eV) is observed slightly larger than that of the clean Ag(111) substrate (4.50 eV). A bidirectional charge transfer model is introduced to understand the work function variation of the fullerene/metal system. In addition to the charge transfer from substrate to the adsorbate's unoccupied states, there exists non-negligible back charge transfer from fullerene occupied molecular orbital to the metal substrate through interfacial hybridization. The Fermi level will be pinned at ∼4.72 eV for C84 monolayer on coinage metal substrate.

A tunable sub-100 nm silicon nanopore array with an AAO membrane mask: reducing unwanted surface etching by introducing a PMMA interlayer.

PubMed

Lim, Namsoo; Pak, Yusin; Kim, Jin Tae; Hwang, Youngkyu; Lee, Ryeri; Kumaresan, Yogeenth; Myoung, NoSoung; Ko, Heung Cho; Jung, Gun Young

2015-08-28

Highly ordered silicon (Si) nanopores with a tunable sub-100 nm diameter were fabricated by a CF4 plasma etching process using an anodic aluminum oxide (AAO) membrane as an etching mask. To enhance the conformal contact of the AAO membrane mask to the underlying Si substrate, poly(methyl methacrylate) (PMMA) was spin-coated on top of the Si substrate prior to the transfer of the AAO membrane. The AAO membrane mask was fabricated by two-step anodization and subsequent removal of the aluminum support and the barrier layer, which was then transferred to the PMMA-coated Si substrate. Contact printing was performed on the sample with a pressure of 50 psi and a temperature of 120 °C to make a conformal contact of the AAO membrane mask to the Si substrate. The CF4 plasma etching was conducted to transfer nanopores onto the Si substrate through the PMMA interlayer. The introduced PMMA interlayer prevented unwanted surface etching of the Si substrate by eliminating the etching ions and radicals bouncing at the gap between the mask and the substrate, resulting in a smooth Si nanopore array.

Pattern transfer printing by kinetic control of adhesion to an elastomeric stamp

DOEpatents

Nuzzo, Ralph G [Champaign, IL; Rogers, John A [Champaign, IL; Menard, Etienne [Urbana, IL; Lee, Keon Jae [Tokyo, JP; Khang, Dahl-Young [Urbana, IL; Sun, Yugang [Champaign, IL; Meitl, Matthew [Champaign, IL; Zhu, Zhengtao [Urbana, IL

2011-05-17

The present invention provides methods, systems and system components for transferring, assembling and integrating features and arrays of features having selected nanosized and/or microsized physical dimensions, shapes and spatial orientations. Methods of the present invention utilize principles of `soft adhesion` to guide the transfer, assembly and/or integration of features, such as printable semiconductor elements or other components of electronic devices. Methods of the present invention are useful for transferring features from a donor substrate to the transfer surface of an elastomeric transfer device and, optionally, from the transfer surface of an elastomeric transfer device to the receiving surface of a receiving substrate. The present methods and systems provide highly efficient, registered transfer of features and arrays of features, such as printable semiconductor element, in a concerted manner that maintains the relative spatial orientations of transferred features.

Single-Enzyme Nanoparticles Armored by a Nanometer-Scale Organic/Inorganic Network

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

Kim, Jungbae; Grate, Jay W.

2003-09-01

We have developed armored single-enzyme nanoparticles (SENs), which dramatically stabilize a protease (a-chymotrypsin, CT) by surrounding each enzyme molecule with a porous composite organic/inorganic shell of less than a few nanometers thick. The armored enzymes show no decrease in CT activity at 30C for four days while free CT activity is rapidly reduced by orders of magnitude. The armored shell around CT is sufficiently thin and porous that it does not place any serious mass-transfer limitation on substrates. This unique approach will have a great impact in using enzymes in various fields.

Transferable and flexible thin film devices for engineering applications

NASA Astrophysics Data System (ADS)

Mutyala, Madhu Santosh K.; Zhou, Jingzhou; Li, Xiaochun

2014-05-01

Thin film devices can be of significance for manufacturing, energy conversion systems, solid state electronics, wireless applications, etc. However, these thin film sensors/devices are normally fabricated on rigid silicon substrates, thus neither flexible nor transferrable for engineering applications. This paper reports an innovative approach to transfer polyimide (PI) embedded thin film devices, which were fabricated on glass, to thin metal foils. Thin film thermocouples (TFTCs) were fabricated on a thin PI film, which was spin coated and cured on a glass substrate. Another layer of PI film was then spin coated again on TFTC/PI and cured to obtain the embedded TFTCs. Assisted by oxygen plasma surface coarsening of the PI film on the glass substrate, the PI embedded TFTC was successfully transferred from the glass substrate to a flexible copper foil. To demonstrate the functionality of the flexible embedded thin film sensors, they were transferred to the sonotrode tip of an ultrasonic metal welding machine for in situ process monitoring. The dynamic temperatures near the sonotrode tip were effectively measured under various ultrasonic vibration amplitudes. This technique of transferring polymer embedded electronic devices onto metal foils yield great potentials for numerous engineering applications.

Active pixel sensor with intra-pixel charge transfer

NASA Technical Reports Server (NTRS)

Fossum, Eric R. (Inventor); Mendis, Sunetra (Inventor); Kemeny, Sabrina E. (Inventor)

1995-01-01

An imaging device formed as a monolithic complementary metal oxide semiconductor integrated circuit in an industry standard complementary metal oxide semiconductor process, the integrated circuit including a focal plane array of pixel cells, each one of the cells including a photogate overlying the substrate for accumulating photo-generated charge in an underlying portion of the substrate, a readout circuit including at least an output field effect transistor formed in the substrate, and a charge coupled device section formed on the substrate adjacent the photogate having a sensing node connected to the output transistor and at least one charge coupled device stage for transferring charge from the underlying portion of the substrate to the sensing node.

Active pixel sensor with intra-pixel charge transfer

NASA Technical Reports Server (NTRS)

Fossum, Eric R. (Inventor); Mendis, Sunetra (Inventor); Kemeny, Sabrina E. (Inventor)

2003-01-01

An imaging device formed as a monolithic complementary metal oxide semiconductor integrated circuit in an industry standard complementary metal oxide semiconductor process, the integrated circuit including a focal plane array of pixel cells, each one of the cells including a photogate overlying the substrate for accumulating photo-generated charge in an underlying portion of the substrate, a readout circuit including at least an output field effect transistor formed in the substrate, and a charge coupled device section formed on the substrate adjacent the photogate having a sensing node connected to the output transistor and at least one charge coupled device stage for transferring charge from the underlying portion of the substrate to the sensing node.

Active pixel sensor with intra-pixel charge transfer

NASA Technical Reports Server (NTRS)

Fossum, Eric R. (Inventor); Mendis, Sunetra (Inventor); Kemeny, Sabrina E. (Inventor)

2004-01-01

An imaging device formed as a monolithic complementary metal oxide semiconductor integrated circuit in an industry standard complementary metal oxide semiconductor process, the integrated circuit including a focal plane array of pixel cells, each one of the cells including a photogate overlying the substrate for accumulating photo-generated charge in an underlying portion of the substrate, a readout circuit including at least an output field effect transistor formed in the substrate, and a charge coupled device section formed on the substrate adjacent the photogate having a sensing node connected to the output transistor and at least one charge coupled device stage for transferring charge from the underlying portion of the substrate to the sensing node.

Protein dynamics promote hydride tunnelling in substrate oxidation by aryl-alcohol oxidase.

PubMed

Carro, Juan; Martínez-Júlvez, Marta; Medina, Milagros; Martínez, Angel T; Ferreira, Patricia

2017-11-01

The temperature dependence of hydride transfer from the substrate to the N5 of the FAD cofactor during the reductive half-reaction of Pleurotus eryngii aryl-alcohol oxidase (AAO) is assessed here. Kinetic isotope effects on both the pre-steady state reduction of the enzyme and its steady-state kinetics, with differently deuterated substrates, suggest an environmentally-coupled quantum-mechanical tunnelling process. Moreover, those kinetic data, along with the crystallographic structure of the enzyme in complex with a substrate analogue, indicate that AAO shows a pre-organized active site that would only require the approaching of the hydride donor and acceptor for the tunnelled transfer to take place. Modification of the enzyme's active-site architecture by replacement of Tyr92, a residue establishing hydrophobic interactions with the substrate analogue in the crystal structure, in the Y92F, Y92L and Y92W variants resulted in different temperature dependence patterns that indicated a role of this residue in modulating the transfer reaction.

A multiphase mixture model for substrate concentration distribution characteristics and photo-hydrogen production performance of the entrapped-cell photobioreactor.

PubMed

Guo, Cheng-Long; Cao, Hong-Xia; Pei, Hong-Shan; Guo, Fei-Qiang; Liu, Da-Meng

2015-04-01

A multiphase mixture model was developed for revealing the interaction mechanism between biochemical reactions and transfer processes in the entrapped-cell photobioreactor packed with gel granules containing Rhodopseudomonas palustris CQK 01. The effects of difference operation parameters, including operation temperature, influent medium pH value and porosity of packed bed, on substrate concentration distribution characteristics and photo-hydrogen production performance were investigated. The results showed that the model predictions were in good agreement with the experimental data reported. Moreover, the operation temperature of 30 °C and the influent medium pH value of 7 were the most suitable conditions for photo-hydrogen production by biodegrading substrate. In addition, the lower porosity of packed bed was beneficial to enhance photo-hydrogen production performance owing to the improvement on the amount of substrate transferred into gel granules caused by the increased specific area for substrate transfer in the elemental volume. Copyright © 2015 Elsevier Ltd. All rights reserved.

Refining the reaction mechanism of O2 towards its co-substrate in cofactor-free dioxygenases

PubMed Central

2016-01-01

Cofactor-less oxygenases perform challenging catalytic reactions between singlet co-substrates and triplet oxygen, in spite of apparently violating the spin-conservation rule. In 1-H-3-hydroxy-4-oxoquinaldine-2,4-dioxygenase, the active site has been suggested by quantum chemical computations to fine tune triplet oxygen reactivity, allowing it to interact rapidly with its singlet substrate without the need for spin inversion, and in urate oxidase the reaction is thought to proceed through electron transfer from the deprotonated substrate to an aminoacid sidechain, which then feeds the electron to the oxygen molecule. In this work, we perform additional quantum chemical computations on these two systems to elucidate several intriguing features unaddressed by previous workers. These computations establish that in both enzymes the reaction proceeds through direct electron transfer from co-substrate to O2 followed by radical recombination, instead of minimum-energy crossing points between singlet and triplet potential energy surfaces without formal electron transfer. The active site does not affect the reactivity of oxygen directly but is crucial for the generation of the deprotonated form of the co-substrates, which have redox potentials far below those of their protonated forms and therefore may transfer electrons to oxygen without sizeable thermodynamic barriers. This mechanism seems to be shared by most cofactor-less oxidases studied so far. PMID:28028471

Refining the reaction mechanism of O2 towards its co-substrate in cofactor-free dioxygenases.

PubMed

Silva, Pedro J

2016-01-01

Cofactor-less oxygenases perform challenging catalytic reactions between singlet co-substrates and triplet oxygen, in spite of apparently violating the spin-conservation rule. In 1- H -3-hydroxy-4-oxoquinaldine-2,4-dioxygenase, the active site has been suggested by quantum chemical computations to fine tune triplet oxygen reactivity, allowing it to interact rapidly with its singlet substrate without the need for spin inversion, and in urate oxidase the reaction is thought to proceed through electron transfer from the deprotonated substrate to an aminoacid sidechain, which then feeds the electron to the oxygen molecule. In this work, we perform additional quantum chemical computations on these two systems to elucidate several intriguing features unaddressed by previous workers. These computations establish that in both enzymes the reaction proceeds through direct electron transfer from co-substrate to O 2 followed by radical recombination, instead of minimum-energy crossing points between singlet and triplet potential energy surfaces without formal electron transfer. The active site does not affect the reactivity of oxygen directly but is crucial for the generation of the deprotonated form of the co-substrates, which have redox potentials far below those of their protonated forms and therefore may transfer electrons to oxygen without sizeable thermodynamic barriers. This mechanism seems to be shared by most cofactor-less oxidases studied so far.

Pattern transfer with stabilized nanoparticle etch masks

NASA Astrophysics Data System (ADS)

Hogg, Charles R.; Picard, Yoosuf N.; Narasimhan, Amrit; Bain, James A.; Majetich, Sara A.

2013-03-01

Self-assembled nanoparticle monolayer arrays are used as an etch mask for pattern transfer into Si and SiOx substrates. Crack formation within the array is prevented by electron beam curing to fix the nanoparticles to the substrate, followed by a brief oxygen plasma to remove excess carbon. This leaves a dot array of nanoparticle cores with a minimum gap of 2 nm. Deposition and liftoff can transform the dot array mask into an antidot mask, where the gap is determined by the nanoparticle core diameter. Reactive ion etching is used to transfer the dot and antidot patterns into the substrate. The effect of the gap size on the etching rate is modeled and compared with the experimental results.

Realizing controllable graphene nucleation by regulating the competition of hydrogen and oxygen during chemical vapor deposition heating.

PubMed

Zhang, Haoran; Zhang, Yaqian; Zhang, Yanhui; Chen, Zhiying; Sui, Yanping; Ge, Xiaoming; Deng, Rongxuan; Yu, Guanghui; Jin, Zhi; Liu, Xinyu

2016-08-24

Oxygen can passivate Cu surface active sites when graphene nucleates. Thus, the nucleation density is decreased. The CuO/Cu substrate was chosen for graphene domain synthesis in our study. The results indicate that the CuO/Cu substrate is beneficial for large-scale, single-crystal graphene domain synthesis. Graphene grown on the CuO/Cu substrate exhibits fewer nucleation sites than on Cu foils, suggesting that graphene follows an oxygen-dominating growth. Hydrogen treatment via a heating process could weaken the surface oxygen's role in limiting graphene nucleation under the competition of hydrogen and oxygen and could transfer the synthesis of graphene into a hydrogen-dominating growth. However, the competition only exists during the chemical vapor deposition heating process. For non-hydrogen heated samples, oxygen-dominating growth is experienced even though the samples are annealed in hydrogen for a long time after the heating process. With the temperature increases, the role of hydrogen gradually decreases. The balance of hydrogen and oxygen is adjusted by introducing hydrogen gas at a different heating temperatures. The oxygen concentration on the substrate surface is believed to determine the reactions mechanisms based on the secondary ion mass spectrometry test results. This study provides a new method for the controllable synthesis of graphene nucleation during a heating process.

Numerical and Experimental Approaches Toward Understanding Lava Flow Heat Transfer

NASA Astrophysics Data System (ADS)

Rumpf, M.; Fagents, S. A.; Hamilton, C.; Crawford, I. A.

2013-12-01

We have performed numerical modeling and experimental studies to quantify the heat transfer from a lava flow into an underlying particulate substrate. This project was initially motivated by a desire to understand the transfer of heat from a lava flow into the lunar regolith. Ancient regolith deposits that have been protected by a lava flow may contain ancient solar wind, solar flare, and galactic cosmic ray products that can give insight into the history of our solar system, provided the records were not heated and destroyed by the overlying lava flow. In addition, lava-substrate interaction is an important aspect of lava fluid dynamics that requires consideration in lava emplacement models Our numerical model determines the depth to which the heat pulse will penetrate beneath a lava flow into the underlying substrate. Rigorous treatment of the temperature dependence of lava and substrate thermal conductivity and specific heat capacity, density, and latent heat release are imperative to an accurate model. Experiments were conducted to verify the numerical model. Experimental containers with interior dimensions of 20 x 20 x 25 cm were constructed from 1 inch thick calcium silicate sheeting. For initial experiments, boxes were packed with lunar regolith simulant (GSC-1) to a depth of 15 cm with thermocouples embedded at regular intervals. Basalt collected at Kilauea Volcano, HI, was melted in a gas forge and poured directly onto the simulant. Initial lava temperatures ranged from ~1200 to 1300 °C. The system was allowed to cool while internal temperatures were monitored by a thermocouple array and external temperatures were monitored by a Forward Looking Infrared (FLIR) video camera. Numerical simulations of the experiments elucidate the details of lava latent heat release and constrain the temperature-dependence of the thermal conductivity of the particulate substrate. The temperature-dependence of thermal conductivity of particulate material is not well known, especially at high temperatures. It is important to have this property well constrained as substrate thermal conductivity is the greatest influence on the rate of lava-substrate heat transfer. At Kilauea and Mauna Loa Volcanoes, Hawaii, and other volcanoes that threaten communities, lava may erupt over a variety of substrate materials including cool lava flows, volcanic tephra, soils, sand, and concrete. The composition, moisture, organic content, porosity, and grain size of the substrate dictate the thermophysical properties, thus affecting the transfer of heat from the lava flow into the substrate and flow mobility. Particulate substrate materials act as insulators, subduing the rate of heat transfer from the flow core. Therefore, lava that flows over a particulate substrate will maintain higher core temperatures over a longer period, enhancing flow mobility and increasing the duration and aerial coverage of the resulting flow. Lava flow prediction models should include substrate specification with temperature dependent material property definitions for an accurate understanding of flow hazards.

Flexible crossbar-structured resistive memory arrays on plastic substrates via inorganic-based laser lift-off.

PubMed

Kim, Seungjun; Son, Jung Hwan; Lee, Seung Hyun; You, Byoung Kuk; Park, Kwi-Il; Lee, Hwan Keon; Byun, Myunghwan; Lee, Keon Jae

2014-11-26

Crossbar-structured memory comprising 32 × 32 arrays with one selector-one resistor (1S-1R) components are initially fabricated on a rigid substrate. They are transferred without mechanical damage via an inorganic-based laser lift-off (ILLO) process as a result of laser-material interaction. Addressing tests of the transferred memory arrays are successfully performed to verify mitigation of cross-talk on a plastic substrate. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabrication of all-carbon nanotube electronic devices on flexible substrates through CVD and transfer methods.

PubMed

Zou, Yuan; Li, Qunqing; Liu, Junku; Jin, Yuanhao; Qian, Qingkai; Jiang, Kaili; Fan, Shoushan

2013-11-13

SWNT thin films with different nanotube densities are fabricated by CVD while controlling the concentration of catalyst and growth time. Three layers of SWNT films are transferred to flexible substrates serving as electrodes and channel materials, respectively. All-carbon nanotube TFTs with an on/off ratio as high as 10(5) are obtained. Inverters are fabricated on top of the flexible substrates with symmetric input/output behavior. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Flexible Nonstick Replica Mold for Transfer Printing of Ag Ink.

PubMed

Lee, Bong Kuk; Yu, Han Young; Kim, Yarkyeon; Yoon, Yong Sun; Jang, Won Ik; Do, Lee-Mi; Park, Ji-Ho; Park, Jaehoon

2016-03-01

We report the fabrication of flexible replica molds for transfer printing of Ag ink on a rigid glass substrate. As mold precursors, acrylic mixtures were prepared from silsesquioxane-based materials, silicone acrylate, poly(propylene glycol) diacrylate, 3,3,4,4,5,5,6,6,7,7,8,8, 9,9,10,10,10-heptadecafluorodecyl methacrylate, and photoinitiator. By using these materials, the replica molds were fabricated from a silicon master onto a flexible substrate by means of UV-assisted molding process at room temperature. The wettability of Ag ink decreased with increase in the water contact angle of replica molds. On the other hand, the transfer rate of Ag ink onto adhesive-modified substrates increased with increase in the water contact angle of replica molds. Transferred patterns were found to be thermally stable on the photocurable adhesive layer, whereas Ag-ink patterns transferred on non-photocurable adhesives were distorted by thermal treatment. We believe that these characteristics of replica molds and adhesives offer a new strategy for the development of the transfer printing of solution-based ink materials.

Delaminated Transfer of CVD Graphene

NASA Astrophysics Data System (ADS)

Clavijo, Alexis; Mao, Jinhai; Tilak, Nikhil; Altvater, Michael; Andrei, Eva

Single layer graphene is commonly synthesized by dissociation of a carbonaceous gas at high temperatures in the presence of a metallic catalyst in a process known as Chemical Vapor Deposition or CVD. Although it is possible to achieve high quality graphene by CVD, the standard transfer technique of etching away the metallic catalyst is wasteful and jeopardizes the quality of the graphene film by contamination from etchants. Thus, development of a clean transfer technique and preservation of the parent substrate remain prominent hurdles to overcome. In this study, we employ a copper pretreatment technique and optimized parameters for growth of high quality single layer graphene at atmospheric pressure. We address the transfer challenge by utilizing the adhesive properties between a polymer film and graphene to achieve etchant-free transfer of graphene films from a copper substrate. Based on this concept we developed a technique for dry delamination and transferring of graphene to hexagonal boron nitride substrates, which produced high quality graphene films while at the same time preserving the integrity of the copper catalyst for reuse. DOE-FG02-99ER45742, Ronald E. McNair Postbaccalaureate Achievement Program.

IHF-independent assembly of the Tn10 strand transfer transpososome: implications for inhibition of disintegration.

PubMed

Stewart, Barry J; Wardle, Simon J; Haniford, David B

2002-08-15

The frequency of DNA transposition in transposition systems that employ a strand transfer step may be significantly affected by the occurrence of a disintegration reaction, a reaction that reverses the strand transfer event. We have asked whether disintegration occurs in the Tn10 transposition system. We show that disintegration substrates (substrates constituting one half of the strand transfer product) are assembled into a transpososome that mimics the strand transfer intermediate. This strand transfer transpososome (STT) does appear to support an intermolecular disintegration reaction, but only at a very low level. Strikingly, assembly of the STT is not dependent on IHF, a host protein that is required for de novo assembly of all previously characterized Tn10 transpososomes. We suggest that disintegration substrates are able to form both transposon end and target type contacts with transposase because of their enhanced conformational flexibility. This probably allows the conformation of DNA within the complex that prevents the destructive disintegration reaction, and is responsible for relaxing the DNA sequence requirements for STT formation relative to other Tn10 transpososomes.

IHF-independent assembly of the Tn10 strand transfer transpososome: implications for inhibition of disintegration

PubMed Central

Stewart, Barry J.; Wardle, Simon J.; Haniford, David B.

2002-01-01

The frequency of DNA transposition in transposition systems that employ a strand transfer step may be significantly affected by the occurrence of a disintegration reaction, a reaction that reverses the strand transfer event. We have asked whether disintegration occurs in the Tn10 transposition system. We show that disintegration substrates (substrates constituting one half of the strand transfer product) are assembled into a transpososome that mimics the strand transfer intermediate. This strand transfer transpososome (STT) does appear to support an intermolecular disintegration reaction, but only at a very low level. Strikingly, assembly of the STT is not dependent on IHF, a host protein that is required for de novo assembly of all previously characterized Tn10 transpososomes. We suggest that disintegration substrates are able to form both transposon end and target type contacts with transposase because of their enhanced conformational flexibility. This probably allows the conformation of DNA within the complex that prevents the destructive disintegration reaction, and is responsible for relaxing the DNA sequence requirements for STT formation relative to other Tn10 transpososomes. PMID:12169640

Conversion of H2 and CO2 to CH4 and acetate in fed-batch biogas reactors by mixed biogas community: a novel route for the power-to-gas concept.

PubMed

Szuhaj, Márk; Ács, Norbert; Tengölics, Roland; Bodor, Attila; Rákhely, Gábor; Kovács, Kornél L; Bagi, Zoltán

2016-01-01

Applications of the power-to-gas principle for the handling of surplus renewable electricity have been proposed. The feasibility of using hydrogenotrophic methanogens as CH4 generating catalysts has been demonstrated. Laboratory and scale-up experiments have corroborated the benefits of the CO2 mitigation via biotechnological conversion of H2 and CO2 to CH4. A major bottleneck in the process is the gas-liquid mass transfer of H2. Fed-batch reactor configuration was tested at mesophilic temperature in laboratory experiments in order to improve the contact time and H2 mass transfer between the gas and liquid phases. Effluent from an industrial biogas facility served as biocatalyst. The bicarbonate content of the effluent was depleted after some time, but the addition of stoichiometric CO2 sustained H2 conversion for an extended period of time and prevented a pH shift. The microbial community generated biogas from the added α-cellulose substrate with concomitant H2 conversion, but the organic substrate did not facilitate H2 consumption. Fed-batch operational mode allowed a fourfold increase in volumetric H2 load and a 6.5-fold augmentation of the CH4 formation rate relative to the CSTR reactor configuration. Acetate was the major by-product of the reaction. Fed-batch reactors significantly improve the efficiency of the biological power-to-gas process. Besides their storage function, biogas fermentation effluent reservoirs can serve as large-scale bio CH4 reactors. On the basis of this recognition, a novel concept is proposed, which merges biogas technology with other means of renewable electricity production for improved efficiency and sustainability.

Meniscus-force-mediated layer transfer technique using single-crystalline silicon films with midair cavity: Application to fabrication of CMOS transistors on plastic substrates

NASA Astrophysics Data System (ADS)

Sakaike, Kohei; Akazawa, Muneki; Nakagawa, Akitoshi; Higashi, Seiichiro

2015-04-01

A novel low-temperature technique for transferring a silicon-on-insulator (SOI) layer with a midair cavity (supported by narrow SiO2 columns) by meniscus force has been proposed, and a single-crystalline Si (c-Si) film with a midair cavity formed in dog-bone shape was successfully transferred to a poly(ethylene terephthalate) (PET) substrate at its heatproof temperature or lower. By applying this proposed transfer technique, high-performance c-Si-based complementary metal-oxide-semiconductor (CMOS) transistors were successfully fabricated on the PET substrate. The key processes are the thermal oxidation and subsequent hydrogen annealing of the SOI layer on the midair cavity. These processes ensure a good MOS interface, and the SiO2 layer works as a “blocking” layer that blocks contamination from PET. The fabricated n- and p-channel c-Si thin-film transistors (TFTs) on the PET substrate showed field-effect mobilities of 568 and 103 cm2 V-1 s-1, respectively.

Micro-masonry for 3D additive micromanufacturing.

PubMed

Keum, Hohyun; Kim, Seok

2014-08-01

Transfer printing is a method to transfer solid micro/nanoscale materials (herein called 'inks') from a substrate where they are generated to a different substrate by utilizing elastomeric stamps. Transfer printing enables the integration of heterogeneous materials to fabricate unexampled structures or functional systems that are found in recent advanced devices such as flexible and stretchable solar cells and LED arrays. While transfer printing exhibits unique features in material assembly capability, the use of adhesive layers or the surface modification such as deposition of self-assembled monolayer (SAM) on substrates for enhancing printing processes hinders its wide adaptation in microassembly of microelectromechanical system (MEMS) structures and devices. To overcome this shortcoming, we developed an advanced mode of transfer printing which deterministically assembles individual microscale objects solely through controlling surface contact area without any surface alteration. The absence of an adhesive layer or other modification and the subsequent material bonding processes ensure not only mechanical bonding, but also thermal and electrical connection between assembled materials, which further opens various applications in adaptation in building unusual MEMS devices.

Identifying the substrate proteins of U-box E3s E4B and CHIP by orthogonal ubiquitin transfer.

PubMed

Bhuripanyo, Karan; Wang, Yiyang; Liu, Xianpeng; Zhou, Li; Liu, Ruochuan; Duong, Duc; Zhao, Bo; Bi, Yingtao; Zhou, Han; Chen, Geng; Seyfried, Nicholas T; Chazin, Walter J; Kiyokawa, Hiroaki; Yin, Jun

2018-01-01

E3 ubiquitin (UB) ligases E4B and carboxyl terminus of Hsc70-interacting protein (CHIP) use a common U-box motif to transfer UB from E1 and E2 enzymes to their substrate proteins and regulate diverse cellular processes. To profile their ubiquitination targets in the cell, we used phage display to engineer E2-E4B and E2-CHIP pairs that were free of cross-reactivity with the native UB transfer cascades. We then used the engineered E2-E3 pairs to construct "orthogonal UB transfer (OUT)" cascades so that a mutant UB (xUB) could be exclusively used by the engineered E4B or CHIP to label their substrate proteins. Purification of xUB-conjugated proteins followed by proteomics analysis enabled the identification of hundreds of potential substrates of E4B and CHIP in human embryonic kidney 293 cells. Kinase MAPK3 (mitogen-activated protein kinase 3), methyltransferase PRMT1 (protein arginine N -methyltransferase 1), and phosphatase PPP3CA (protein phosphatase 3 catalytic subunit alpha) were identified as the shared substrates of the two E3s. Phosphatase PGAM5 (phosphoglycerate mutase 5) and deubiquitinase OTUB1 (ovarian tumor domain containing ubiquitin aldehyde binding protein 1) were confirmed as E4B substrates, and β-catenin and CDK4 (cyclin-dependent kinase 4) were confirmed as CHIP substrates. On the basis of the CHIP-CDK4 circuit identified by OUT, we revealed that CHIP signals CDK4 degradation in response to endoplasmic reticulum stress.

Identifying the substrate proteins of U-box E3s E4B and CHIP by orthogonal ubiquitin transfer

PubMed Central

Bhuripanyo, Karan; Wang, Yiyang; Liu, Xianpeng; Zhou, Li; Liu, Ruochuan; Duong, Duc; Zhao, Bo; Bi, Yingtao; Zhou, Han; Chen, Geng; Seyfried, Nicholas T.; Chazin, Walter J.; Kiyokawa, Hiroaki; Yin, Jun

2018-01-01

E3 ubiquitin (UB) ligases E4B and carboxyl terminus of Hsc70-interacting protein (CHIP) use a common U-box motif to transfer UB from E1 and E2 enzymes to their substrate proteins and regulate diverse cellular processes. To profile their ubiquitination targets in the cell, we used phage display to engineer E2-E4B and E2-CHIP pairs that were free of cross-reactivity with the native UB transfer cascades. We then used the engineered E2-E3 pairs to construct “orthogonal UB transfer (OUT)” cascades so that a mutant UB (xUB) could be exclusively used by the engineered E4B or CHIP to label their substrate proteins. Purification of xUB-conjugated proteins followed by proteomics analysis enabled the identification of hundreds of potential substrates of E4B and CHIP in human embryonic kidney 293 cells. Kinase MAPK3 (mitogen-activated protein kinase 3), methyltransferase PRMT1 (protein arginine N-methyltransferase 1), and phosphatase PPP3CA (protein phosphatase 3 catalytic subunit alpha) were identified as the shared substrates of the two E3s. Phosphatase PGAM5 (phosphoglycerate mutase 5) and deubiquitinase OTUB1 (ovarian tumor domain containing ubiquitin aldehyde binding protein 1) were confirmed as E4B substrates, and β-catenin and CDK4 (cyclin-dependent kinase 4) were confirmed as CHIP substrates. On the basis of the CHIP-CDK4 circuit identified by OUT, we revealed that CHIP signals CDK4 degradation in response to endoplasmic reticulum stress. PMID:29326975

Light-Emitting GaAs Nanowires on a Flexible Substrate.

PubMed

Valente, João; Godde, Tillmann; Zhang, Yunyan; Mowbray, David J; Liu, Huiyun

2018-06-18

Semiconductor nanowire-based devices are among the most promising structures used to meet the current challenges of electronics, optics and photonics. Due to their high surface-to-volume ratio and excellent optical and electrical properties, devices with low power, high efficiency and high density can be created. This is of major importance for environmental issues and economic impact. Semiconductor nanowires have been used to fabricate high performance devices, including detectors, solar cells and transistors. Here, we demonstrate a technique for transferring large-area nanowire arrays to flexible substrates while retaining their excellent quantum efficiency in emission. Starting with a defect-free self-catalyzed molecular beam epitaxy (MBE) sample grown on a Si substrate, GaAs core-shell nanowires are embedded in a dielectric, removed by reactive ion etching and transferred to a plastic substrate. The original structural and optical properties, including the vertical orientation, of the nanowires are retained in the final plastic substrate structure. Nanowire emission is observed for all stages of the fabrication process, with a higher emission intensity observed for the final transferred structure, consistent with a reduction in nonradiative recombination via the modification of surface states. This transfer process could form the first critical step in the development of flexible nanowire-based light-emitting devices.

Combining light-harvesting with detachability in high-efficiency thin-film silicon solar cells.

PubMed

Ram, Sanjay K; Desta, Derese; Rizzoli, Rita; Bellettato, Michele; Lyckegaard, Folmer; Jensen, Pia B; Jeppesen, Bjarke R; Chevallier, Jacques; Summonte, Caterina; Larsen, Arne Nylandsted; Balling, Peter

2017-06-01

Efforts to realize thin-film solar cells on unconventional substrates face several obstacles in achieving good energy-conversion efficiency and integrating light-management into the solar cell design. In this report a technique to circumvent these obstacles is presented: transferability and an efficient light-harvesting scheme are combined for thin-film silicon solar cells by the incorporation of a NaCl layer. Amorphous silicon solar cells in p-i-n configuration are fabricated on reusable glass substrates coated with an interlayer of NaCl. Subsequently, the solar cells are detached from the substrate by dissolution of the sacrificial NaCl layer in water and then transferred onto a plastic sheet, with a resultant post-transfer efficiency of 9%. The light-trapping effect of the surface nanotextures originating from the NaCl layer on the overlying solar cell is studied theoretically and experimentally. The enhanced light absorption in the solar cells on NaCl-coated substrates leads to significant improvement in the photocurrent and energy-conversion efficiency in solar cells with both 350 and 100 nm thick absorber layers, compared to flat-substrate solar cells. Efficient transferable thin-film solar cells hold a vast potential for widespread deployment of off-grid photovoltaics and cost reduction.

Microfabrication of plastic-PDMS microfluidic devices using polyimide release layer and selective adhesive bonding

DOE PAGES

Wang, Shuyu; Yu, Shifeng; Lu, Ming; ...

2017-03-15

In this study, we present an improved method to bond poly(dimethylsiloxane) (PDMS) with polyimide (PI) to develop flexible substrate microfluidic devices. The PI film was separately fabricated on a silicon wafer by spin coating followed by thermal treatment to avoid surface unevenness of the flexible substrate. In this way, we could also integrate flexible substrate into standard micro-electromechanical systems (MEMS) fabrication. Meanwhile, the adhesive epoxy was selectively transferred to the PDMS microfluidic device by a stamp-and-stick method to avoid epoxy clogging the microfluidic channels. To spread out the epoxy evenly on the transferring substrate, we used superhydrophilic vanadium oxide filmmore » coated glass as the transferring substrate. After the bonding process, the flexible substrate could easily be peeled off from the rigid substrate. Contact angle measurement was used to characterize the hydrophicity of the vanadium oxide film. X-ray photoelectron spectroscopy analysis was conducted to study the surface of the epoxy. We further evaluated the bonding quality by peeling tests, which showed a maximum bonding strength of 100 kPa. By injecting with black ink, the plastic microfluidic device was confirmed to be well bonded with no leakage for a day under 1 atm. Finally, this proposed versatile method could bond the microfluidic device and plastic substrate together and be applied in the fabrication of some biosensors and lab-on-a-chip systems.« less

3.4-Inch Quarter High Definition Flexible Active Matrix Organic Light Emitting Display with Oxide Thin Film Transistor

NASA Astrophysics Data System (ADS)

Hatano, Kaoru; Chida, Akihiro; Okano, Tatsuya; Sugisawa, Nozomu; Inoue, Tatsunori; Seo, Satoshi; Suzuki, Kunihiko; Oikawa, Yoshiaki; Miyake, Hiroyuki; Koyama, Jun; Yamazaki, Shunpei; Eguchi, Shingo; Katayama, Masahiro; Sakakura, Masayuki

2011-03-01

In this paper, we report a 3.4-in. flexible active matrix organic light emitting display (AMOLED) display with remarkably high definition (quarter high definition: QHD) in which oxide thin film transistors (TFTs) are used. We have developed a transfer technology in which a TFT array formed on a glass substrate is separated from the substrate by physical force and then attached to a flexible plastic substrate. Unlike a normal process in which a TFT array is directly fabricated on a thin plastic substrate, our transfer technology permits a high integration of high performance TFTs, such as low-temperature polycrystalline silicon TFTs (LTPS TFTs) and oxide TFTs, on a plastic substrate, because a flat, rigid, and thermally-stable glass substrate can be used in the TFT fabrication process in our transfer technology. As a result, this technology realized an oxide TFT array for an AMOLED on a plastic substrate. Furthermore, in order to achieve a high-definition AMOLED, color filters were incorporated in the TFT array and a white organic light-emitting diode (OLED) was combined. One of the features of this device is that the whole body of the device can be bent freely because a source driver and a gate driver can be integrated on the substrate due to the high mobility of an oxide TFT. This feature means “true” flexibility.

Microfabrication of plastic-PDMS microfluidic devices using polyimide release layer and selective adhesive bonding

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

Wang, Shuyu; Yu, Shifeng; Lu, Ming

In this study, we present an improved method to bond poly(dimethylsiloxane) (PDMS) with polyimide (PI) to develop flexible substrate microfluidic devices. The PI film was separately fabricated on a silicon wafer by spin coating followed by thermal treatment to avoid surface unevenness of the flexible substrate. In this way, we could also integrate flexible substrate into standard micro-electromechanical systems (MEMS) fabrication. Meanwhile, the adhesive epoxy was selectively transferred to the PDMS microfluidic device by a stamp-and-stick method to avoid epoxy clogging the microfluidic channels. To spread out the epoxy evenly on the transferring substrate, we used superhydrophilic vanadium oxide filmmore » coated glass as the transferring substrate. After the bonding process, the flexible substrate could easily be peeled off from the rigid substrate. Contact angle measurement was used to characterize the hydrophicity of the vanadium oxide film. X-ray photoelectron spectroscopy analysis was conducted to study the surface of the epoxy. We further evaluated the bonding quality by peeling tests, which showed a maximum bonding strength of 100 kPa. By injecting with black ink, the plastic microfluidic device was confirmed to be well bonded with no leakage for a day under 1 atm. Finally, this proposed versatile method could bond the microfluidic device and plastic substrate together and be applied in the fabrication of some biosensors and lab-on-a-chip systems.« less

Engineered Structured Sorbents for the Adsorption of Carbon Dioxide and Water Vapor from Manned Spacecraft Atmospheres: Applications and Modeling 2007/2008

NASA Technical Reports Server (NTRS)

Knox, James C.; Howard, David F.; Perry, Jay L.

2007-01-01

In NASA s Vision for Space Exploration, humans will once again travel beyond the confines of earth s gravity, this time to remain there for extended periods. These forays will place unprecedented demands on launch systems. They must not only blast out of earth s gravity well as during the Apollo moon missions, but also launch the supplies needed to sustain a larger crew over much longer periods. Thus all spacecraft systems, including those for the separation of metabolic carbon dioxide and water from a crewed vehicle, must be minimized with respect to mass, power, and volume. Emphasis is also placed on system robustness both to minimize replacement parts and ensure crew safety when a quick return to earth is not possible. This paper describes efforts to improve on typical packed beds of sorbent pellets by making use of structured sorbents and alternate bed configurations to improve system efficiency and reliability. The development efforts described offer a complimentary approach combining testing of subscale systems and multiphysics computer simulations to characterize the regenerative heating substrates and evaluation of engineered structured sorbent geometries. Mass transfer, heat transfer, and fluid dynamics are included in the transient simulations.

Apparatus and method of direct water cooling several parallel circuit cards each containing several chip packages

DOEpatents

Cipolla, Thomas M [Katonah, NY; Colgan, Evan George [Chestnut Ridge, NY; Coteus, Paul W [Yorktown Heights, NY; Hall, Shawn Anthony [Pleasantville, NY; Tian, Shurong [Mount Kisco, NY

2011-12-20

A cooling apparatus, system and like method for an electronic device includes a plurality of heat producing electronic devices affixed to a wiring substrate. A plurality of heat transfer assemblies each include heat spreaders and thermally communicate with the heat producing electronic devices for transferring heat from the heat producing electronic devices to the heat transfer assemblies. The plurality of heat producing electronic devices and respective heat transfer assemblies are positioned on the wiring substrate having the regions overlapping. A heat conduit thermally communicates with the heat transfer assemblies. The heat conduit circulates thermally conductive fluid therethrough in a closed loop for transferring heat to the fluid from the heat transfer assemblies via the heat spreader. A thermally conductive support structure supports the heat conduit and thermally communicates with the heat transfer assemblies via the heat spreader transferring heat to the fluid of the heat conduit from the support structure.

Active pixel sensor having intra-pixel charge transfer with analog-to-digital converter

NASA Technical Reports Server (NTRS)

Fossum, Eric R. (Inventor); Mendis, Sunetra K. (Inventor); Pain, Bedabrata (Inventor); Nixon, Robert H. (Inventor); Zhou, Zhimin (Inventor)

2003-01-01

An imaging device formed as a monolithic complementary metal oxide semiconductor integrated circuit in an industry standard complementary metal oxide semiconductor process, the integrated circuit including a focal plane array of pixel cells, each one of the cells including a photogate overlying the substrate for accumulating photo-generated charge in an underlying portion of the substrate, a readout circuit including at least an output field effect transistor formed in the substrate, and a charge coupled device section formed on the substrate adjacent the photogate having a sensing node connected to the output transistor and at least one charge coupled device stage for transferring charge from the underlying portion of the substrate to the sensing node and an analog-to-digital converter formed in the substrate connected to the output of the readout circuit.

Active pixel sensor having intra-pixel charge transfer with analog-to-digital converter

NASA Technical Reports Server (NTRS)

Fossum, Eric R. (Inventor); Mendis, Sunetra K. (Inventor); Pain, Bedabrata (Inventor); Nixon, Robert H. (Inventor); Zhou, Zhimin (Inventor)

2000-01-01

An imaging device formed as a monolithic complementary metal oxide semiconductor Integrated circuit in an industry standard complementary metal oxide semiconductor process, the integrated circuit including a focal plane array of pixel cells, each one of the cells including a photogate overlying the substrate for accumulating photo-generated charge in an underlying portion of the substrate, a readout circuit including at least an output field effect transistor formed in the substrate, and a charge coupled device section formed on the substrate adjacent the photogate having a sensing node connected to the output transistor and at least one charge coupled device stage for transferring charge from the underlying portion of the substrate to the sensing node and an analog-to-digital converter formed in the substrate connected to the output of the readout circuit.

Re-polarization of nuclear spins using selective SABRE-INEPT.

PubMed

Knecht, Stephan; Kiryutin, Alexey S; Yurkovskaya, Alexandra V; Ivanov, Konstantin L

2018-02-01

A method is proposed for significant improvement of NMR pulse sequences used in high-field SABRE (Signal Amplification By Reversible Exchange) experiments. SABRE makes use of spin order transfer from parahydrogen (pH 2 , the H 2 molecule in its singlet spin state) to a substrate in a transient organometallic Ir-based complex. The technique proposed here utilizes "re-polarization", i.e., multiple application of an NMR pulse sequence used for spin order transfer. During re-polarization only the form of the substrate, which is bound to the complex, is excited by selective NMR pulses and the resulting polarization is transferred to the free substrate via chemical exchange. Owing to the fact that (i) only a small fraction of the substrate molecules is in the bound form and (ii) spin relaxation of the free substrate is slow, the re-polarization scheme provides greatly improved NMR signal enhancement, ε. For instance, when pyridine is used as a substrate, single use of the SABRE-INEPT sequence provides ε≈260 for 15 N nuclei, whereas SABRE-INEPT with re-polarization yields ε>2000. We anticipate that the proposed method is useful for achieving maximal NMR enhancement with spin hyperpolarization techniques. Copyright © 2017 Elsevier Inc. All rights reserved.

Re-polarization of nuclear spins using selective SABRE-INEPT

NASA Astrophysics Data System (ADS)

Knecht, Stephan; Kiryutin, Alexey S.; Yurkovskaya, Alexandra V.; Ivanov, Konstantin L.

2018-02-01

A method is proposed for significant improvement of NMR pulse sequences used in high-field SABRE (Signal Amplification By Reversible Exchange) experiments. SABRE makes use of spin order transfer from parahydrogen (pH2, the H2 molecule in its singlet spin state) to a substrate in a transient organometallic Ir-based complex. The technique proposed here utilizes "re-polarization", i.e., multiple application of an NMR pulse sequence used for spin order transfer. During re-polarization only the form of the substrate, which is bound to the complex, is excited by selective NMR pulses and the resulting polarization is transferred to the free substrate via chemical exchange. Owing to the fact that (i) only a small fraction of the substrate molecules is in the bound form and (ii) spin relaxation of the free substrate is slow, the re-polarization scheme provides greatly improved NMR signal enhancement, ε . For instance, when pyridine is used as a substrate, single use of the SABRE-INEPT sequence provides ε ≈ 260 for 15N nuclei, whereas SABRE-INEPT with re-polarization yields ε > 2000 . We anticipate that the proposed method is useful for achieving maximal NMR enhancement with spin hyperpolarization techniques.

Modeling of enhanced catalysis in multienzyme nanostructures: effect of molecular scaffolds, spatial organization, and concentration.

PubMed

Roberts, Christopher C; Chang, Chia-en A

2015-01-13

Colocalized multistep enzymatic reaction pathways within biological catabolic and metabolic processes occur with high yield and specificity. Spatial organization on membranes or surfaces may be associated with increased efficiency of intermediate substrate transfer. Using a new Brownian dynamics package, GeomBD, we explored the geometric features of a surface-anchored enzyme system by parallel coarse-grained Brownian dynamics simulations of substrate diffusion over microsecond (μs) to millisecond (ms) time scales. We focused on a recently developed glucose oxidase (GOx), horseradish peroxidase (HRP), and DNA origami-scaffold enzyme system, where the H2O2 substrate of HRP is produced by GOx. The results revealed and explained a significant advantage in catalytic enhancement by optimizing interenzyme distance and orientation in the presence of the scaffold model. The planar scaffold colocalized the enzymes and provided a diffusive barrier that enhanced substrate transfer probability, becoming more relevant with increasing interenzyme distance. The results highlight the importance of protein geometry in the proper assessment of distance and orientation dependence on the probability of substrate transfer. They shed light on strategies for engineering multienzyme complexes and further investigation of enhanced catalytic efficiency for substrate diffusion between membrane-anchoring proteins.

Full-wafer fabrication by nanostencil lithography of micro/nanomechanical mass sensors monolithically integrated with CMOS.

PubMed

Arcamone, J; van den Boogaart, M A F; Serra-Graells, F; Fraxedas, J; Brugger, J; Pérez-Murano, F

2008-07-30

Wafer-scale nanostencil lithography (nSL) is used to define several types of silicon mechanical resonators, whose dimensions range from 20 µm down to 200 nm, monolithically integrated with CMOS circuits. We demonstrate the simultaneous patterning by nSL of ∼2000 nanodevices per wafer by post-processing standard CMOS substrates using one single metal evaporation, pattern transfer to silicon and subsequent etch of the sacrificial layer. Resonance frequencies in the MHz range were measured in air and vacuum. As proof-of-concept towards an application as high performance sensors, CMOS integrated nano/micromechanical resonators are successfully implemented as ultra-sensitive areal mass sensors. These devices demonstrate the ability to monitor the deposition of gold layers whose average thickness is smaller than a monolayer. Their areal mass sensitivity is in the range of 10(-11) g cm(-2) Hz(-1), and their thickness resolution corresponds to approximately a thousandth of a monolayer.

Release strategies for making transferable semiconductor structures, devices and device components

DOEpatents

Rogers, John A; Nuzzo, Ralph G; Meitl, Matthew; Ko, Heung Cho; Yoon, Jongseung; Menard, Etienne; Baca, Alfred J

2014-11-25

Provided are methods for making a device or device component by providing a multilayer structure having a plurality of functional layers and a plurality of release layers and releasing the functional layers from the multilayer structure by separating one or more of the release layers to generate a plurality of transferable structures. The transferable structures are printed onto a device substrate or device component supported by a device substrate. The methods and systems provide means for making high-quality and low-cost photovoltaic devices, transferable semiconductor structures, (opto-)electronic devices and device components.

Release strategies for making transferable semiconductor structures, devices and device components

DOEpatents

Rogers, John A [Champaign, IL; Nuzzo, Ralph G [Champaign, IL; Meitl, Matthew [Raleigh, NC; Ko, Heung Cho [Urbana, IL; Yoon, Jongseung [Urbana, IL; Menard, Etienne [Durham, NC; Baca, Alfred J [Urbana, IL

2011-04-26

Provided are methods for making a device or device component by providing a multilayer structure having a plurality of functional layers and a plurality of release layers and releasing the functional layers from the multilayer structure by separating one or more of the release layers to generate a plurality of transferable structures. The transferable structures are printed onto a device substrate or device component supported by a device substrate. The methods and systems provide means for making high-quality and low-cost photovoltaic devices, transferable semiconductor structures, (opto-)electronic devices and device components.

Release strategies for making transferable semiconductor structures, devices and device components

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

Rogers, John A.; Nuzzo, Ralph G.; Meitl, Matthew

2016-05-24

Provided are methods for making a device or device component by providing a multi layer structure having a plurality of functional layers and a plurality of release layers and releasing the functional layers from the multilayer structure by separating one or more of the release layers to generate a plurality of transferable structures. The transferable structures are printed onto a device substrate or device component supported by a device substrate. The methods and systems provide means for making high-quality and low-cost photovoltaic devices, transferable semiconductor structures, (opto-)electronic devices and device components.

Carbon nanotube substrates and catalyzed hot stamp for polishing and patterning the substrates

DOEpatents

Wang, Yuhuang [Evanston, IL; Hauge, Robert H [Houston, TX; Schmidt, Howard K [Houston, TX; Kim, Myung Jong [Houston, TX; Kittrell, W Carter [Houston, TX

2009-09-08

The present invention is generally directed to catalyzed hot stamp methods for polishing and/or patterning carbon nanotube-containing substrates. In some embodiments, the substrate, as a carbon nanotube fiber end, is brought into contact with a hot stamp (typically at 200-800.degree. C.), and is kept in contact with the hot stamp until the morphology/patterns on the hot stamp have been transferred to the substrate. In some embodiments, the hot stamp is made of material comprising one or more transition metals (Fe, Ni, Co, Pt, Ag, Au, etc.), which can catalyze the etching reaction of carbon with H.sub.2, CO.sub.2, H.sub.2O, and/or O.sub.2. Such methods can (1) polish the carbon nanotube-containing substrate with a microscopically smooth finish, and/or (2) transfer pre-defined patterns from the hot stamp to the substrate. Such polished or patterned carbon nanotube substrates can find application as carbon nanotube electrodes, field emitters, and field emitter arrays for displays and electron sources.

Mechanism of the 2,3-diphosphoglycerate-dependent phosphoglycerate mutase from rabbit muscle.

PubMed

Britton, H G; Clarke, J B

1972-11-01

1. The properties and kinetics of the 2,3-diphosphoglycerate-dependent phosphoglycerate mutases are discussed. There are at least three possible mechanisms for the reaction: (i) a phosphoenzyme (Ping Pong) mechanism; (ii) an intermolecular transfer of phosphate from 2,3-diphosphoglycerate to the substrates (sequential mechanism); (iii) an intramolecular transfer of phosphate. It is concluded that these mechanisms cannot be distinguished by conventional kinetic measurements. 2. The fluxes for the different mechanisms are calculated and it is shown that it should be possible to distinguish between the mechanisms by appropriate induced-transport tests and by comparing the fluxes of (32)P- and (14)C-labelled substrates at chemical equilibrium. 3. With (14)C-labelled substrates no induced transport was found over a wide concentration range, and with (32)P-labelled substrates co-transport occurred that was independent of concentration over a twofold range. (14)C-labelled substrates exchange at twice the rate of (32)P-labelled substrates at chemical equilibrium. The results were completely in accord with a phosphoenzyme mechanism and indicated a rate constant for the isomerization of the phosphoenzyme of not less than 4x10(6)s(-1). The intramolecular transfer of phosphate (and intermolecular transfer between two or more molecules of substrate) were completely excluded. The intermolecular transfer of phosphate from 2,3-diphosphoglycerate would have been compatible with the results only if the K(m) for 2-phosphoglycerate had been over 7.5-fold smaller than the observed value and if an isomerization of the enzyme-2,3-diphosphoglycerate complex had been the major rate-limiting step in the reaction. 4. The very rapid isomerization of the phosphoenzyme that the experiments demonstrate suggests a mechanism that does not involve a formal isomerization. According to this new scheme the enzyme is closely related mechanistically and perhaps evolutionarily to a 2,3-diphosphoglycerate diphosphatase.

Mechanism of the 2,3-diphosphoglycerate-dependent phosphoglycerate mutase from rabbit muscle

PubMed Central

Britton, H. G.; Clarke, J. B.

1972-01-01

1. The properties and kinetics of the 2,3-diphosphoglycerate-dependent phosphoglycerate mutases are discussed. There are at least three possible mechanisms for the reaction: (i) a phosphoenzyme (Ping Pong) mechanism; (ii) an intermolecular transfer of phosphate from 2,3-diphosphoglycerate to the substrates (sequential mechanism); (iii) an intramolecular transfer of phosphate. It is concluded that these mechanisms cannot be distinguished by conventional kinetic measurements. 2. The fluxes for the different mechanisms are calculated and it is shown that it should be possible to distinguish between the mechanisms by appropriate induced-transport tests and by comparing the fluxes of 32P- and 14C-labelled substrates at chemical equilibrium. 3. With 14C-labelled substrates no induced transport was found over a wide concentration range, and with 32P-labelled substrates co-transport occurred that was independent of concentration over a twofold range. 14C-labelled substrates exchange at twice the rate of 32P-labelled substrates at chemical equilibrium. The results were completely in accord with a phosphoenzyme mechanism and indicated a rate constant for the isomerization of the phosphoenzyme of not less than 4×106s−1. The intramolecular transfer of phosphate (and intermolecular transfer between two or more molecules of substrate) were completely excluded. The intermolecular transfer of phosphate from 2,3-diphosphoglycerate would have been compatible with the results only if the Km for 2-phosphoglycerate had been over 7.5-fold smaller than the observed value and if an isomerization of the enzyme-2,3-diphosphoglycerate complex had been the major rate-limiting step in the reaction. 4. The very rapid isomerization of the phosphoenzyme that the experiments demonstrate suggests a mechanism that does not involve a formal isomerization. According to this new scheme the enzyme is closely related mechanistically and perhaps evolutionarily to a 2,3-diphosphoglycerate diphosphatase. PMID:4677138

Synthesis and Transfer of Large-Area Monolayer WS2 Crystals: Moving Toward the Recyclable Use of Sapphire Substrates.

PubMed

Xu, Zai-Quan; Zhang, Yupeng; Lin, Shenghuang; Zheng, Changxi; Zhong, Yu Lin; Xia, Xue; Li, Zhipeng; Sophia, Ponraj Joice; Fuhrer, Michael S; Cheng, Yi-Bing; Bao, Qiaoliang

2015-06-23

Two-dimensional layered transition metal dichalcogenides (TMDs) show intriguing potential for optoelectronic devices due to their exotic electronic and optical properties. Only a few efforts have been dedicated to large-area growth of TMDs. Practical applications will require improving the efficiency and reducing the cost of production, through (1) new growth methods to produce large size TMD monolayer with less-stringent conditions, and (2) nondestructive transfer techniques that enable multiple reuse of growth substrate. In this work, we report to employ atmospheric pressure chemical vapor deposition (APCVD) for the synthesis of large size (>100 μm) single crystals of atomically thin tungsten disulfide (WS2), a member of TMD family, on sapphire substrate. More importantly, we demonstrate a polystyrene (PS) mediated delamination process via capillary force in water which reduces the etching time in base solution and imposes only minor damage to the sapphire substrate. The transferred WS2 flakes are of excellent continuity and exhibit comparable electron mobility after several growth cycles on the reused sapphire substrate. Interestingly, the photoluminescence emission from WS2 grown on the recycled sapphire is much higher than that on fresh sapphire, possibly due to p-type doping of monolayer WS2 flakes by a thin layer of water intercalated at the atomic steps of the recycled sapphire substrate. The growth and transfer techniques described here are expected to be applicable to other atomically thin TMD materials.

Palladium pincer complex catalyzed stannyl and silyl transfer to propargylic substrates: synthetic scope and mechanism.

PubMed

Kjellgren, Johan; Sundén, Henrik; Szabó, Kálmán J

2005-02-16

Pincer complex catalyzed substitution of various propargylic substrates could be achieved using tin- and silicon-based dimetallic reagents to obtain propargyl- and allenylstannanes and silanes. These reactions involving chloride, mesylate, and epoxide substrates could be carried out under mild conditions, and therefore many functionalities (such as COOEt, OR, OH, NR, and NAc) are tolerated. It was shown that pincer catalysts with electron-supplying ligands, such as NCN, SCS, and SeCSe complexes, display the highest catalytic activity. The catalytic substitution of secondary propargyl chlorides and primary propargyl chlorides with electron-withdrawing substituents proceeds with high regioselectivity providing the allenyl product. Opening of the propargyl epoxides takes place with an excellent stereo- and regioselectivity to give stereodefined allenylstannanes. Silylstannanes as dimetallic reagents undergo an exclusive silyl transfer to the propargylic substrate affording allenylsilanes with high regioselectivity. According to our mechanistic studies, the key intermediate of the reaction is an organostannane (or silane)-coordinated pincer complex, which is formed from the dimetallic reagent and the corresponding pincer complex catalyst. DFT modeling studies have shown that the trimethylstannyl functionality is transferred to the propargylic substrate in a single reaction step with high allenyl selectivity. Inspection of the TS structures reveals that the trimethylstannyl group transfer is initiated by the attack of the palladium-tin sigma-bond electrons on the propargylic substrate. This is a novel mechanism in palladium chemistry, which is based on the unique topology of the pincer complex catalysts.

Natural printed silk substrate circuit fabricated via surface modification using one step thermal transfer and reduction graphene oxide

NASA Astrophysics Data System (ADS)

Cao, Jiliang; Huang, Zhan; Wang, Chaoxia

2018-05-01

Graphene conductive silk substrate is a preferred material because of its biocompatibility, flexibility and comfort. A flexible natural printed silk substrate circuit was fabricated by one step transfer of graphene oxide (GO) paste from transfer paper to the surface of silk fabric and reduction of the GO to reduced graphene oxide (RGO) using a simple hot press treatment. The GO paste was obtained through ultrasonic stirring exfoliation under low temperature, and presented excellent printing rheological properties at high concentration. The silk fabric was obtained a surface electric resistance as low as 12.15 KΩ cm-1, in the concentration of GO 50 g L-1 and hot press at 220 °C for 120 s. Though the whiteness and strength decreased with the increasing of hot press temperature and time slowly, the electric conductivity of RGO surface modification silk substrate improved obviously. The surface electric resistance of RGO/silk fabrics increased from 12.15 KΩ cm-1 to 18.05 KΩ cm-1, 28.54 KΩ cm-1 and 32.53 KΩ cm-1 after 10, 20 and 30 washing cycles, respectively. The results showed that the printed silk substrate circuit has excellent washability. This process requires no chemical reductant, and the reduction efficiency and reduction degree of GO is high. This time-effective and environmentally-friendly one step thermal transfer and reduction graphene oxide onto natural silk substrate method can be easily used to production of reduced graphene oxide (RGO) based flexible printed circuit.

Spatially Mapping Energy Transfer from Single Plasmonic Particles to Semiconductor Substrates via STEM/EELS.

PubMed

Li, Guoliang; Cherqui, Charles; Bigelow, Nicholas W; Duscher, Gerd; Straney, Patrick J; Millstone, Jill E; Masiello, David J; Camden, Jon P

2015-05-13

Energy transfer from plasmonic nanoparticles to semiconductors can expand the available spectrum of solar energy-harvesting devices. Here, we spatially and spectrally resolve the interaction between single Ag nanocubes with insulating and semiconducting substrates using electron energy-loss spectroscopy, electrodynamics simulations, and extended plasmon hybridization theory. Our results illustrate a new way to characterize plasmon-semiconductor energy transfer at the nanoscale and bear impact upon the design of next-generation solar energy-harvesting devices.

Azimuthally and radially excited charge transfer plasmon and Fano lineshapes in conductive sublayer-mediated nanoassemblies.

PubMed

Ahmadivand, Arash; Gerislioglu, Burak; Pala, Nezih

2017-11-01

Here, the plasmon responses of both symmetric and antisymmetric oligomers on a conductive substrate under linear, azimuthal, and radial polarization excitations are analyzed numerically. By observing charge transfer plasmons under cylindrical vector beam (CVB) illumination for what we believe is the first time, we show that our studies open new horizons to induce significant charge transfer plasmons and antisymmetric Fano resonance lineshapes in metallic substrate-mediated plasmonic nanoclusters under both azimuthal and radial excitation as CVBs.

Wettability Investigations and Wet Transfer Enhancement of Large-Area CVD-Graphene on Aluminum Nitride

PubMed Central

Knapp, Marius; Hoffmann, René; Cimalla, Volker; Ambacher, Oliver

2017-01-01

The two-dimensional and virtually massless character of graphene attracts great interest for radio frequency devices, such as surface and bulk acoustic wave resonators. Due to its good electric conductivity, graphene might be an alternative as a virtually massless electrode by improving resonator performance regarding mass-loading effects. We report on an optimization of the commonly used wet transfer technique for large-area graphene, grown via chemical vapor deposition, onto aluminum nitride (AlN), which is mainly used as an active, piezoelectric material for acoustic devices. Today, graphene wet transfer is well-engineered for silicon dioxide (SiO2). Investigations on AlN substrates reveal highly different surface properties compared to SiO2 regarding wettability, which strongly influences the quality of transferred graphene monolayers. Both physical and chemical effects of a plasma treatment of AlN surfaces change wettability and avoid large-scale cracks in the transferred graphene sheet during desiccation. Spatially-resolved Raman spectroscopy reveals a strong strain and doping dependence on AlN plasma pretreatments correlating with the electrical conductivity of graphene. In our work, we achieved transferred crack-free large-area (40 × 40 mm2) graphene monolayers with sheet resistances down to 350 Ω/sq. These achievements make graphene more powerful as an eco-friendly and cheaper replacement for conventional electrode materials used in radio frequency resonator devices. PMID:28820462

Using White Dwarf Companions of Blue Stragglers to Constrain Mass Transfer Physics

NASA Astrophysics Data System (ADS)

Gosnell, Natalie M.; Leiner, Emily; Geller, Aaron M.; Knigge, Christian; Mathieu, Robert D.; Sills, Alison; Leigh, Nathan

2018-06-01

Complete membership studies of old open clusters reveal that 25% of the evolved stars follow pathways in stellar evolution that are impacted by binary evolution. Recent studies show that the majority of blue straggler stars, traditionally defined to be stars brighter and bluer than the corresponding main sequence turnoff, are formed through mass transfer from a giant star onto a main sequence companion, resulting in a white dwarf in a binary system with a blue straggler. We will present constraints on the histories and mass transfer efficiencies for two blue straggler-white dwarf binaries in open cluster NGC 188. The constraints are a result of measuring white dwarf cooling temperatures and surface gravities with HST COS far-ultraviolet spectroscopy. This information sets both the timeline for mass transfer and the stellar masses in the pre-mass transfer binary, allowing us to constrain aspects of the mass transfer physics. One system is formed through Case C mass transfer, leaving a CO-core white dwarf, and provides an interesting test case for mass transfer from an asymptotic giant branch star in an eccentric system. The other system formed through Case B mass transfer, leaving a He-core white dwarf, and challenges our current understanding of the expected regimes for stable mass transfer from red giant branch stars.

Experimental characterization and modeling for the growth rate of oxide coatings from liquid solutions of metalorganic precursors by ultrasonic pulsed injection in a cold-wall low-pressure reactor

NASA Astrophysics Data System (ADS)

Krumdieck, Susan Pran

Several years ago, a method for depositing ceramic coatings called the Pulsed-MOCVD system was developed by the Raj group at Cornell University in association with Dr. Harvey Berger and Sono-Tek Corporation. The process was used to produce epitaxial thin films of TiO2 on sapphire substrates under conditions of low pressure, relatively high temperature, and very low growth rate. The system came to CU-Boulder when Professor Raj moved here in 1997. It is quite a simple technique and has several advantages over typical CVD systems. The purpose of this dissertation is two-fold; (1) understand the chemical processes, thermodynamics, and kinetics of the Pulsed-MOCVD technique, and (2) determine the possible applications by studying the film structure and morphology over the entire range of deposition conditions. Polycrystalline coatings of ceramic materials were deposited on nickel in the low-pressure, cold-wall reactor from metalorganic precursors, titanium isopropoxide, and a mixture of zirconium isopropoxide and yttria isopropoxide. The process utilized pulsed liquid injection of a dilute precursor solution with atomization by ultrasonic nozzle. Thin films (less than 1mum) with fine-grained microstructure and thick coatings (up to 1mum) with columnar-microstructure were deposited on heated metal substrates by thermal decomposition of a single liquid precursor. The influence of each of the primary deposition parameters, substrate temperature, total flow rate, and precursor concentration on growth rate, conversion efficiency and morphology were investigated. The operating conditions were determined for kinetic, mass transfer, and evaporation process control regimes. Kinetic controlled deposition was found to produce equiaxed morphology while mass transfer controlled deposition produced columnar morphology. A kinetic model of the deposition process was developed and compared to data for deposition of TiO2 from Ti(OC3H7) 4 precursor. The results demonstrate that growth rate and morphology over the range of process operating conditions would make the Pulsed-MOCVD system suitable for application of thermal barrier coatings, electrical insulating layers, corrosion protection coatings, and the electrolyte layers in solid oxide fuel cells.

The Influence of Oscillatory Fractions on Mass Transfer of Non-Newtonian Fluid in Wavy-Walled Tubes for Pulsatile Flow

NASA Astrophysics Data System (ADS)

Zhu, Donghui; Bian, Yongning

2018-03-01

The shape of pipeline structure, fluid medium and flow state have important influence on the heat transfer and mass effect of fluid. In this paper, we investigated the mass transfer behavior of Non-Newtonian fluid CMC solution with 700ppm concentration in five different-sized axisymmetric wave-walled tubes for pulsatile flow. It is revealed that the effect of mass transfer is enhanced with the increase of oscillatory fractions P based on the PIV measurements. Besides, mass transfer rate was measured by the electrochemical method in the larger oscillatory points rate range. It is observed that mass transfer rate increases with the increase in P and reached the maximum mass transfer rate at the most optimal oscillatory fractions P opt. After reaching the optimal oscillatory fractions P opt, the mass transfer rate decreases with increasing P.

Nano-Biotechnology in Using Enzymes for Environmental Remediation: Single-Enzyme Nanoparticles

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

Kim, Jungbae; Grate, Jay W.

2005-01-01

We have developed armored single-enzyme nanoparticles (SENs), which dramatically stabilize a protease (a-chymotrypsin, CT) by surrounding each enzyme molecule with a porous composite organic/inorganic shell of less than a few nanometers thick. The armored enzymes show no decrease in CT activity at 30°C for a day while free CT activity is rapidly reduced by orders of magnitude. The armored shell around CT is sufficiently thin and porous that it does not place any serious mass-transfer limitation of substrate. This unique approach will have a great impact in using enzymes in various fields, including environmental remediation.

Analysis of Ligand-Receptor Association and Intermediate Transfer Rates in Multienzyme Nanostructures with All-Atom Brownian Dynamics Simulations.

PubMed

Roberts, Christopher C; Chang, Chia-En A

2016-08-25

We present the second-generation GeomBD Brownian dynamics software for determining interenzyme intermediate transfer rates and substrate association rates in biomolecular complexes. Substrate and intermediate association rates for a series of enzymes or biomolecules can be compared between the freely diffusing disorganized configuration and various colocalized or complexed arrangements for kinetic investigation of enhanced intermediate transfer. In addition, enzyme engineering techniques, such as synthetic protein conjugation, can be computationally modeled and analyzed to better understand changes in substrate association relative to native enzymes. Tools are provided to determine nonspecific ligand-receptor association residence times, and to visualize common sites of nonspecific association of substrates on receptor surfaces. To demonstrate features of the software, interenzyme intermediate substrate transfer rate constants are calculated and compared for all-atom models of DNA origami scaffold-bound bienzyme systems of glucose oxidase and horseradish peroxidase. Also, a DNA conjugated horseradish peroxidase enzyme was analyzed for its propensity to increase substrate association rates and substrate local residence times relative to the unmodified enzyme. We also demonstrate the rapid determination and visualization of common sites of nonspecific ligand-receptor association by using HIV-1 protease and an inhibitor, XK263. GeomBD2 accelerates simulations by precomputing van der Waals potential energy grids and electrostatic potential grid maps, and has a flexible and extensible support for all-atom and coarse-grained force fields. Simulation software is written in C++ and utilizes modern parallelization techniques for potential grid preparation and Brownian dynamics simulation processes. Analysis scripts, written in the Python scripting language, are provided for quantitative simulation analysis. GeomBD2 is applicable to the fields of biophysics, bioengineering, and enzymology in both predictive and explanatory roles.

Assessment of water droplet evaporation mechanisms on hydrophobic and superhydrophobic substrates.

PubMed

Pan, Zhenhai; Dash, Susmita; Weibel, Justin A; Garimella, Suresh V

2013-12-23

Evaporation rates are predicted and important transport mechanisms identified for evaporation of water droplets on hydrophobic (contact angle ~110°) and superhydrophobic (contact angle ~160°) substrates. Analytical models for droplet evaporation in the literature are usually simplified to include only vapor diffusion in the gas domain, and the system is assumed to be isothermal. In the comprehensive model developed in this study, evaporative cooling of the interface is accounted for, and vapor concentration is coupled to local temperature at the interface. Conjugate heat and mass transfer are solved in the solid substrate, liquid droplet, and surrounding gas. Buoyancy-driven convective flows in the droplet and vapor domains are also simulated. The influences of evaporative cooling and convection on the evaporation characteristics are determined quantitatively. The liquid-vapor interface temperature drop induced by evaporative cooling suppresses evaporation, while gas-phase natural convection acts to enhance evaporation. While the effects of these competing transport mechanisms are observed to counterbalance for evaporation on a hydrophobic surface, the stronger influence of evaporative cooling on a superhydrophobic surface accounts for an overprediction of experimental evaporation rates by ~20% with vapor diffusion-based models. The local evaporation fluxes along the liquid-vapor interface for both hydrophobic and superhydrophobic substrates are investigated. The highest local evaporation flux occurs at the three-phase contact line region due to proximity to the higher temperature substrate, rather than at the relatively colder droplet top; vapor diffusion-based models predict the opposite. The numerically calculated evaporation rates agree with experimental results to within 2% for superhydrophobic substrates and 3% for hydrophobic substrates. The large deviations between past analytical models and the experimental data are therefore reconciled with the comprehensive model developed here.

Screening of thermophilic anaerobic bacteria for solid substrate cultivation on lignocellulosic substrates.

PubMed

Chinn, Mari S; Nokes, Sue E; Strobel, Herbert J

2006-01-01

Interest in solid substrate cultivation (SSC) techniques is gaining for biochemical production from renewable resources; however, heat and mass transfer problems may limit application of this technique. The use of anaerobic thermophiles in SSC offers a unique solution to overcoming these challenges. The production potential of nine thermophilic anaerobic bacteria was examined on corn stover, sugar cane bagasse, paper pulp sludge, and wheat bran in submerged liquid cultivation (SmC) and SSC. Production of acetate, ethanol, and lactate was measured over a 10 day period, and total product concentrations were used to compare the performance of different organism-substrate combinations using the two cultivation methods. Overall microbial activity in SmC and SSC was dependent on the organism and growth substrate. Clostridium thermocellum strains JW20, LQRI, and 27405 performed significantly better in SSC when grown on sugar cane bagasse and paper pulp sludge, producing at least 70 and 170 mM of total products, respectively. Growth of C. thermocellum strains in SSC on paper pulp sludge proved to be most favorable, generating at least twice the concentration of total products produced in SmC (p-value < 0.05). Clostridium thermolacticum TC21 demonstrated growth on all substrates producing 30-80 and 60-116 mM of total product in SmC and SSC, respectively. Bacterial species with optimal growth temperatures of 70 degrees C grew best on wheat bran in SmC, producing total product concentrations of 45-75 mM. For some of the organism-substrate combinations total end product concentrations in SSC exceeded those in SmC, indicating that SSC may be a promising alternative for microbial activity and value-added biochemical production.

Low-temperature graphene synthesis using microwave plasma CVD

NASA Astrophysics Data System (ADS)

Yamada, Takatoshi; Kim, Jaeho; Ishihara, Masatou; Hasegawa, Masataka

2013-02-01

The graphene chemical vapour deposition (CVD) technique at substrate temperatures around 300 °C by a microwave plasma sustained by surface waves (surface wave plasma chemical vapour deposition, SWP-CVD) is discussed. A low-temperature, large-area and high-deposition-rate CVD process for graphene films was developed. It was found from Raman spectra that the deposited films on copper (Cu) substrates consisted of high-quality graphene flakes. The fabricated graphene transparent conductive electrode showed uniform optical transmittance and sheet resistance, which suggests the possibility of graphene for practical electrical and optoelectronic applications. It is intriguing that graphene was successfully deposited on aluminium (Al) substrates, for which we did not expect the catalytic effect to decompose hydrocarbon and hydrogen molecules. We developed a roll-to-roll SWP-CVD system for continuous graphene film deposition towards industrial mass production. A pair of winder and unwinder systems of Cu film was installed in the plasma CVD apparatus. Uniform Raman spectra were confirmed over the whole width of 297 mm of Cu films. We successfully transferred the deposited graphene onto PET films, and confirmed a transmittance of about 95% and a sheet resistance of less than 7 × 105 Ω/sq.

3D Imaging of Water-Drop Condensation on Hydrophobic and Hydrophilic Lubricant-Impregnated Surfaces

NASA Astrophysics Data System (ADS)

Kajiya, Tadashi; Schellenberger, Frank; Papadopoulos, Periklis; Vollmer, Doris; Butt, Hans-Jürgen

2016-04-01

Condensation of water from the atmosphere on a solid surface is an ubiquitous phenomenon in nature and has diverse technological applications, e.g. in heat and mass transfer. We investigated the condensation kinetics of water drops on a lubricant-impregnated surface, i.e., a micropillar array impregnated with a non-volatile ionic liquid. Growing and coalescing drops were imaged in 3D using a laser scanning confocal microscope equipped with a temperature and humidity control. Different stages of condensation can be discriminated. On a lubricant-impregnated hydrophobic micropillar array these are: (1) Nucleation on the lubricant surface. (2) Regular alignment of water drops between micropillars and formation of a three-phase contact line on a bottom of the substrate. (3) Deformation and bridging by coalescence which eventually leads to a detachment of the drops from the bottom substrate. The drop-substrate contact does not result in breakdown of the slippery behaviour. Contrary, on a lubricant-impregnated hydrophilic micropillar array, the condensed water drops replace the lubricant. Consequently, the surface loses its slippery property. Our results demonstrate that a Wenzel-like to Cassie transition, required to maintain the facile removal of condensed water drops, can be induced by well-chosen surface hydrophobicity.

3D Imaging of Water-Drop Condensation on Hydrophobic and Hydrophilic Lubricant-Impregnated Surfaces.

PubMed

Kajiya, Tadashi; Schellenberger, Frank; Papadopoulos, Periklis; Vollmer, Doris; Butt, Hans-Jürgen

2016-04-04

Condensation of water from the atmosphere on a solid surface is an ubiquitous phenomenon in nature and has diverse technological applications, e.g. in heat and mass transfer. We investigated the condensation kinetics of water drops on a lubricant-impregnated surface, i.e., a micropillar array impregnated with a non-volatile ionic liquid. Growing and coalescing drops were imaged in 3D using a laser scanning confocal microscope equipped with a temperature and humidity control. Different stages of condensation can be discriminated. On a lubricant-impregnated hydrophobic micropillar array these are: (1) Nucleation on the lubricant surface. (2) Regular alignment of water drops between micropillars and formation of a three-phase contact line on a bottom of the substrate. (3) Deformation and bridging by coalescence which eventually leads to a detachment of the drops from the bottom substrate. The drop-substrate contact does not result in breakdown of the slippery behaviour. Contrary, on a lubricant-impregnated hydrophilic micropillar array, the condensed water drops replace the lubricant. Consequently, the surface loses its slippery property. Our results demonstrate that a Wenzel-like to Cassie transition, required to maintain the facile removal of condensed water drops, can be induced by well-chosen surface hydrophobicity.

Identification of a botulinum C3-like enzyme in bovine brain that catalyzes ADP-ribosylation of GTP-binding proteins.

PubMed

Maehama, T; Takahashi, K; Ohoka, Y; Ohtsuka, T; Ui, M; Katada, T

1991-06-05

A novel enzyme activity was found in bovine brain cytosol that transfers the ADP-ribosyl moiety of NAD to proteins with Mr values of 22,000 and 25,000. The substrates were the same GTP-binding proteins serving as the substrate of an ADP-ribosyltransferase C3 which was produced by a type C strain of Clostridium botulinum. The brain enzyme was partially purified from the cytosol and had a molecular mass of approximately 20,000 on a gel filtration column. The brain endogenous enzyme displayed unique properties similar to those observed with botulinum C3 enzyme. The enzyme activity was markedly stimulated by a protein factor that had been initially found in the cytosol as an activator for botulinum C3-catalyzed ADP-ribosylation (Ohtsuka, T., Nagata, K., Iiri, T., Nozawa, Y., Ueno, K., Ui, M., and Katada, T. (1989) J. Biol. Chem. 264, 15000-15005). The activity of the brain enzyme was also affected by certain types of detergents or phospholipids. The substrate of the brain enzyme was specific for GTP-binding proteins serving as the substrate of botulinum C3 enzyme; the alpha-subunits of trimeric GTP-binding proteins which served as the substrate of cholera or pertussis toxin were not ADP-ribosylated by the endogenous enzyme. Thus, this is the first report showing an endogenous enzyme in mammalian cells that catalyzes ADP-ribosylation of small molecular weight GTP-binding proteins.

Electrically pumped 1.3 microm room-temperature InAs/GaAs quantum dot lasers on Si substrates by metal-mediated wafer bonding and layer transfer.

PubMed

Tanabe, Katsuaki; Guimard, Denis; Bordel, Damien; Iwamoto, Satoshi; Arakawa, Yasuhiko

2010-05-10

An electrically pumped InAs/GaAs quantum dot laser on a Si substrate has been demonstrated. The double-hetero laser structure was grown on a GaAs substrate by metal-organic chemical vapor deposition and layer-transferred onto a Si substrate by GaAs/Si wafer bonding mediated by a 380-nm-thick Au-Ge-Ni alloy layer. This broad-area Fabry-Perot laser exhibits InAs quantum dot ground state lasing at 1.31 microm at room temperature with a threshold current density of 600 A/cm(2). (c) 2010 Optical Society of America.

The C-terminal cytidine deaminase domain of APOBEC3G itself undergoes intersegmental transfer for a target search, as revealed by real-time NMR monitoring.

PubMed

Kamba, Keisuke; Nagata, Takashi; Katahira, Masato

2018-01-31

APOBEC3G (A3G), an anti-human immunodeficiency virus 1 factor, deaminates cytidines. We examined deamination of two cytidines located separately on substrate ssDNA by the C-terminal domain (CTD) of A3G using real-time NMR monitoring. The deamination preference between the two cytidines was lost when either the substrate or non-substrate ssDNA concentration increased. When the non-substrate ssDNA concentration increased, the deamination activity first increased, but then decreased. This indicates that even a single domain, A3G-CTD, undergoes intersegmental transfer for a target search.

Inertial sensing microelectromechanical (MEM) safe-arm device

DOEpatents

Roesler, Alexander W [Tijeras, NM; Wooden, Susan M [Sandia Park, NM

2009-05-12

Microelectromechanical (MEM) safe-arm devices comprise a substrate upon which a sense mass, that can contain an energetic material, is constrained to move along a pathway defined by a track disposed on the surface of the substrate. The pathway has a first end comprising a "safe" position and a second end comprising an "armed" position, whereat the second end the sense mass can be aligned proximal to energetic materials comprising the explosive train, within an explosive component. The sense mass can be confined in the safe position by a first latch, operable to release the sense mass by an acceleration acting in a direction substantially normal to the surface of the substrate. A second acceleration, acting in a direction substantially parallel to the surface of the substrate, can cause the sense mass to traverse the pathway from the safe position to the armed position.

Hybrid Quantum/Classical Molecular Dynamics Simulations of the Proton Transfer Reactions Catalyzed by Ketosteroid Isomerase: Analysis of Hydrogen Bonding, Conformational Motions, and Electrostatics

PubMed Central

Chakravorty, Dhruva K.; Soudackov, Alexander V.; Hammes-Schiffer, Sharon

2009-01-01

Hybrid quantum/classical molecular dynamics simulations of the two proton transfer reactions catalyzed by ketosteroid isomerase are presented. The potential energy surfaces for the proton transfer reactions are described with the empirical valence bond method. Nuclear quantum effects of the transferring hydrogen increase the rates by a factor of ~8, and dynamical barrier recrossings decrease the rates by a factor of 3–4. For both proton transfer reactions, the donor-acceptor distance decreases substantially at the transition state. The carboxylate group of the Asp38 side chain, which serves as the proton acceptor and donor in the first and second steps, respectively, rotates significantly between the two proton transfer reactions. The hydrogen bonding interactions within the active site are consistent with the hydrogen bonding of both Asp99 and Tyr14 to the substrate. The simulations suggest that a hydrogen bond between Asp99 and the substrate is present from the beginning of the first proton transfer step, whereas the hydrogen bond between Tyr14 and the substrate is virtually absent in the first part of this step but forms nearly concurrently with the formation of the transition state. Both hydrogen bonds are present throughout the second proton transfer step until partial dissociation of the product. The hydrogen bond between Tyr14 and Tyr55 is present throughout both proton transfer steps. The active site residues are more mobile during the first step than during the second step. The van der Waals interaction energy between the substrate and the enzyme remains virtually constant along the reaction pathway, but the electrostatic interaction energy is significantly stronger for the dienolate intermediate than for the reactant and product. Mobile loop regions distal to the active site exhibit significant structural rearrangements and, in some cases, qualitative changes in the electrostatic potential during the catalytic reaction. These results suggest that relatively small conformational changes of the enzyme active site and substrate strengthen the hydrogen bonds that stabilize the intermediate, thereby facilitating the proton transfer reactions. Moreover, the conformational and electrostatic changes associated with these reactions are not limited to the active site but rather extend throughout the entire enzyme. PMID:19799395

Contribution of the C-Terminal Region of a Group II Chaperonin to its Interaction with Prefoldin and Substrate Transfer.

PubMed

Zako, Tamotsu; Sahlan, Muhamad; Fujii, Sayaka; Yamamoto, Yohei Y; Tai, Phan The; Sakai, Kotaro; Maeda, Mizuo; Yohda, Masafumi

2016-06-05

Prefoldin is a molecular chaperone that captures an unfolded protein substrate and transfers it to a group II chaperonin. Previous studies have shown that the interaction sites for prefoldin are located in the helical protrusions of group II chaperonins. However, it does not exclude the possibility of the existence of other interaction sites. In this study, we constructed C-terminal truncation mutants of a group II chaperonin and examined the effects of these mutations on the chaperone's function and interaction with prefoldin. Whereas the mutants with up to 6 aa truncation from the C-terminus retained more than 90% chaperone activities for protecting citrate synthase from thermal aggregation and refolding of green fluorescent protein and isopropylmalate dehydrogenase, the truncation mutants showed decreased affinities for prefoldin. Consequently, the truncation mutants showed reduced transfer efficiency of the denatured substrate protein from prefoldin and subsequent chaperonin-dependent refolding. The results clearly show that the C-terminal region of group II chaperonins contributes to their interactions with prefoldin, the transfer of the substrate protein from prefoldin and its refolding. Copyright © 2016 Elsevier Ltd. All rights reserved.

Charge transfer from an adsorbed ruthenium-based photosensitizer through an ultra-thin aluminium oxide layer and into a metallic substrate

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

Gibson, Andrew J.; Temperton, Robert H.; Handrup, Karsten

2014-06-21

The interaction of the dye molecule N3 (cis-bis(isothiocyanato)bis(2,2-bipyridyl-4,4′-dicarbo-xylato) -ruthenium(II)) with the ultra-thin oxide layer on a AlNi(110) substrate, has been studied using synchrotron radiation based photoelectron spectroscopy, resonant photoemission spectroscopy, and near edge X-ray absorption fine structure spectroscopy. Calibrated X-ray absorption and valence band spectra of the monolayer and multilayer coverages reveal that charge transfer is possible from the molecule to the AlNi(110) substrate via tunnelling through the ultra-thin oxide layer and into the conduction band edge of the substrate. This charge transfer mechanism is possible from the LUMO+2 and 3 in the excited state but not from the LUMO,more » therefore enabling core-hole clock analysis, which gives an upper limit of 6.0 ± 2.5 fs for the transfer time. This indicates that ultra-thin oxide layers are a viable material for use in dye-sensitized solar cells, which may lead to reduced recombination effects and improved efficiencies of future devices.« less

Mass Transfer with Chemical Reaction.

ERIC Educational Resources Information Center

DeCoursey, W. J.

1987-01-01

Describes the organization of a graduate course dealing with mass transfer, particularly as it relates to chemical reactions. Discusses the course outline, including mathematics models of mass transfer, enhancement of mass transfer rates by homogeneous chemical reaction, and gas-liquid systems with chemical reaction. (TW)

Micro-masonry for 3D Additive Micromanufacturing

PubMed Central

Keum, Hohyun; Kim, Seok

2014-01-01

Transfer printing is a method to transfer solid micro/nanoscale materials (herein called ‘inks’) from a substrate where they are generated to a different substrate by utilizing elastomeric stamps. Transfer printing enables the integration of heterogeneous materials to fabricate unexampled structures or functional systems that are found in recent advanced devices such as flexible and stretchable solar cells and LED arrays. While transfer printing exhibits unique features in material assembly capability, the use of adhesive layers or the surface modification such as deposition of self-assembled monolayer (SAM) on substrates for enhancing printing processes hinders its wide adaptation in microassembly of microelectromechanical system (MEMS) structures and devices. To overcome this shortcoming, we developed an advanced mode of transfer printing which deterministically assembles individual microscale objects solely through controlling surface contact area without any surface alteration. The absence of an adhesive layer or other modification and the subsequent material bonding processes ensure not only mechanical bonding, but also thermal and electrical connection between assembled materials, which further opens various applications in adaptation in building unusual MEMS devices. PMID:25146178

Image sensor with motion artifact supression and anti-blooming

NASA Technical Reports Server (NTRS)

Pain, Bedabrata (Inventor); Wrigley, Chris (Inventor); Yang, Guang (Inventor); Yadid-Pecht, Orly (Inventor)

2006-01-01

An image sensor includes pixels formed on a semiconductor substrate. Each pixel includes a photoactive region in the semiconductor substrate, a sense node, and a power supply node. A first electrode is disposed near a surface of the semiconductor substrate. A bias signal on the first electrode sets a potential in a region of the semiconductor substrate between the photoactive region and the sense node. A second electrode is disposed near the surface of the semiconductor substrate. A bias signal on the second electrode sets a potential in a region of the semiconductor substrate between the photoactive region and the power supply node. The image sensor includes a controller that causes bias signals to be provided to the electrodes so that photocharges generated in the photoactive region are accumulated in the photoactive region during a pixel integration period, the accumulated photocharges are transferred to the sense node during a charge transfer period, and photocharges generated in the photoactive region are transferred to the power supply node during a third period without passing through the sense node. The imager can operate at high shutter speeds with simultaneous integration of pixels in the array. High quality images can be produced free from motion artifacts. High quantum efficiency, good blooming control, low dark current, low noise and low image lag can be obtained.

High speed CMOS imager with motion artifact supression and anti-blooming

NASA Technical Reports Server (NTRS)

Pain, Bedabrata (Inventor); Wrigley, Chris (Inventor); Yang, Guang (Inventor); Yadid-Pecht, Orly (Inventor)

2001-01-01

An image sensor includes pixels formed on a semiconductor substrate. Each pixel includes a photoactive region in the semiconductor substrate, a sense node, and a power supply node. A first electrode is disposed near a surface of the semiconductor substrate. A bias signal on the first electrode sets a potential in a region of the semiconductor substrate between the photoactive region and the sense node. A second electrode is disposed near the surface of the semiconductor substrate. A bias signal on the second electrode sets a potential in a region of the semiconductor substrate between the photoactive region and the power supply node. The image sensor includes a controller that causes bias signals to be provided to the electrodes so that photocharges generated in the photoactive region are accumulated in the photoactive region during a pixel integration period, the accumulated photocharges are transferred to the sense node during a charge transfer period, and photocharges generated in the photoactive region are transferred to the power supply node during a third period without passing through the sense node. The imager can operate at high shutter speeds with simultaneous integration of pixels in the array. High quality images can be produced free from motion artifacts. High quantum efficiency, good blooming control, low dark current, low noise and low image lag can be obtained.

43 CFR 3106.4-3 - Mass transfers.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Mass transfers. 3106.4-3 Section 3106.4-3... or Otherwise § 3106.4-3 Mass transfers. (a) A mass transfer may be utilized in lieu of the provisions... large number of Federal leases to the same transferee. (b) Three originally executed copies of the mass...

Method of using a germanium layer transfer to Si for photovoltaic applications and heterostructure made thereby

DOEpatents

Atwater, Jr., Harry A.; Zahler, James M.

2006-11-28

Ge/Si and other nonsilicon film heterostructures are formed by hydrogen-induced exfoliation of the Ge film which is wafer bonded to a cheaper substrate, such as Si. A thin, single-crystal layer of Ge is transferred to Si substrate. The bond at the interface of the Ge/Si heterostructures is covalent to ensure good thermal contact, mechanical strength, and to enable the formation of an ohmic contact between the Si substrate and Ge layers. To accomplish this type of bond, hydrophobic wafer bonding is used, because as the invention demonstrates the hydrogen-surface-terminating species that facilitate van der Waals bonding evolves at temperatures above 600.degree. C. into covalent bonding in hydrophobically bound Ge/Si layer transferred systems.

X-ray Crystal Structures Elucidate the Nucleotidyl Transfer Reaction of Transcript Initiation Using Two Nucleotides

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

M Gleghorn; E Davydova; R Basu

2011-12-31

We have determined the X-ray crystal structures of the pre- and postcatalytic forms of the initiation complex of bacteriophage N4 RNA polymerase that provide the complete set of atomic images depicting the process of transcript initiation by a single-subunit RNA polymerase. As observed during T7 RNA polymerase transcript elongation, substrate loading for the initiation process also drives a conformational change of the O helix, but only the correct base pairing between the +2 substrate and DNA base is able to complete the O-helix conformational transition. Substrate binding also facilitates catalytic metal binding that leads to alignment of the reactive groupsmore » of substrates for the nucleotidyl transfer reaction. Although all nucleic acid polymerases use two divalent metals for catalysis, they differ in the requirements and the timing of binding of each metal. In the case of bacteriophage RNA polymerase, we propose that catalytic metal binding is the last step before the nucleotidyl transfer reaction.« less

Protein kinase A catalytic subunit primed for action: Time-lapse crystallography of Michaelis complex formation

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

Das, Amit; Gerlits, Oksana O.; Parks, Jerry M.

The catalytic subunit of the cyclic AMP-dependent protein kinase A (PKAc) catalyzes the transfer of the γ-phosphate of bound Mg 2ATP to a serine or threonine residue of a protein substrate. Here, time-lapse X-ray crystallography was used to capture a series of complexes of PKAc with an oligopeptide substrate and unreacted Mg 2ATP, including the Michaelis complex, that reveal important geometric rearrangements in and near the active site preceding the phosphoryl transfer reaction. Contrary to the prevailing view, Mg 2+ binds first to the M1 site as a complex with ATP and is followed by Mg 2+ binding to themore » M2 site. Furthermore, the target serine hydroxyl of the peptide substrate rotates away from the active site toward the bulk solvent, which breaks the hydrogen bond with D166. In conclusion, the serine hydroxyl of the substrate rotates back toward D166 to form the Michaelis complex with the active site primed for phosphoryl transfer.« less

Protein kinase A catalytic subunit primed for action: Time-lapse crystallography of Michaelis complex formation

DOE PAGES

Das, Amit; Gerlits, Oksana O.; Parks, Jerry M.; ...

2015-11-12

The catalytic subunit of the cyclic AMP-dependent protein kinase A (PKAc) catalyzes the transfer of the γ-phosphate of bound Mg 2ATP to a serine or threonine residue of a protein substrate. Here, time-lapse X-ray crystallography was used to capture a series of complexes of PKAc with an oligopeptide substrate and unreacted Mg 2ATP, including the Michaelis complex, that reveal important geometric rearrangements in and near the active site preceding the phosphoryl transfer reaction. Contrary to the prevailing view, Mg 2+ binds first to the M1 site as a complex with ATP and is followed by Mg 2+ binding to themore » M2 site. Furthermore, the target serine hydroxyl of the peptide substrate rotates away from the active site toward the bulk solvent, which breaks the hydrogen bond with D166. In conclusion, the serine hydroxyl of the substrate rotates back toward D166 to form the Michaelis complex with the active site primed for phosphoryl transfer.« less

Graphene-on-semiconductor substrates for analog electronics

DOEpatents

Lagally, Max G.; Cavallo, Francesca; Rojas-Delgado, Richard

2016-04-26

Electrically conductive material structures, analog electronic devices incorporating the structures and methods for making the structures are provided. The structures include a layer of graphene on a semiconductor substrate. The graphene layer and the substrate are separated by an interfacial region that promotes transfer of charge carriers from the surface of the substrate to the graphene.

Method for materials deposition by ablation transfer processing

DOEpatents

Weiner, Kurt H.

1996-01-01

A method in which a thin layer of semiconducting, insulating, or metallic material is transferred by ablation from a source substrate, coated uniformly with a thin layer of said material, to a target substrate, where said material is desired, with a pulsed, high intensity, patternable beam of energy. The use of a patternable beam allows area-selective ablation from the source substrate resulting in additive deposition of the material onto the target substrate which may require a very low percentage of the area to be covered. Since material is placed only where it is required, material waste can be minimized by reusing the source substrate for depositions on multiple target substrates. Due to the use of a pulsed, high intensity energy source the target substrate remains at low temperature during the process, and thus low-temperature, low cost transparent glass or plastic can be used as the target substrate. The method can be carried out atmospheric pressures and at room temperatures, thus eliminating vacuum systems normally required in materials deposition processes. This invention has particular application in the flat panel display industry, as well as minimizing materials waste and associated costs.

Intramolecular Hydrogen Transfer Reactions Catalyzed by Pentamethylcyclopentadienyl Rhodium and Cobalt Olefin Complexes: Mechanistic Studies.

PubMed

Bolig, Andrew D; Lyons, Thomas W; DiSalvo, Darren T; Brookhart, Maurice

2016-01-08

The mechanism of intramolecular transfer dehydrogenation catalyzed by [Cp * M(VTMS) 2 ] ( 1 , M=Rh, 2 , M=Co, Cp* = C 5 Me 5 , VTMS = vinyltrimethylsilane) complexes has been studied using vinyl silane protected alcohols as substrates. Deuterium-labeled substrates have been synthesized and the regioselectivity of H/D transfers investigated using 1 H and 2 H NMR spectroscopy. The labeling studies establish a regioselective pathway consisting of alkene directed α C-H activation, 2,1 alkene insertion, and finally β-hydride elimination to give silyl enol ether products.

Flow of a surfactant across a thin liquid film wetting a solid substrate

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

Peng, J.B.; He, S.X.; Dutta, P.

1989-12-15

Transfer of a monolayer (valinomycin) between two Langmuir troughs via an interconnecting glass bridge'' has been observed when there is a difference between the monolayer pressures in the two troughs. Assuming that the transfer occurs over the surface of the thin film of water that wets the bridge,'' the transfer rate can be used to estimate the thickness of the liquid film. The thickness thus determined may be used to determine the retarded van der Waals (Hamaker) constant associated with the interaction of the film with the underlying substrate.

Formation and investigation of ultrathin layers of Co2FeSi ferromagnetic alloy synthesized on silicon covered with a CaF2 barrier layer

NASA Astrophysics Data System (ADS)

Grebenyuk, G. S.; Gomoyunova, M. V.; Pronin, I. I.; Vyalikh, D. V.; Molodtsov, S. L.

2016-03-01

Ultrathin (∼2 nm) films of Co2FeSi ferromagnetic alloy were formed on silicon by solid-phase epitaxy and studied in situ. Experiments were carried out in an ultrahigh vacuum (UHV) using substrates of Si(1 1 1) single crystals covered with a 5 nm thick CaF2 barrier layer. The elemental and phase composition as well as the magnetic properties of the synthesized films were analyzed by photoelectron spectroscopy using synchrotron radiation and by magnetic linear dichroism in photoemission of Fe 3p and Co 3p electrons. The study shows that the synthesis of the Co2FeSi ferromagnetic alloy occurs in the temperature range of 200-400 °C. At higher temperatures, the films become island-like and lose their ferromagnetic properties, as the CaF2 barrier layer is unable to prevent a mass transfer between the film and the Si substrate, which violates the stoichiometry of the alloy.

Activity screening of carrier domains within nonribosomal peptide synthetases using complex substrate mixtures and large molecule mass spectrometry.

PubMed

Dorrestein, Pieter C; Blackhall, Jonathan; Straight, Paul D; Fischbach, Michael A; Garneau-Tsodikova, Sylvie; Edwards, Daniel J; McLaughlin, Shaun; Lin, Myat; Gerwick, William H; Kolter, Roberto; Walsh, Christopher T; Kelleher, Neil L

2006-02-14

For screening a pool of potential substrates that load carrier domains found in nonribosomal peptide synthetases, large molecule mass spectrometry is shown to be a new, unbiased assay. Combining the high resolving power of Fourier transform mass spectrometry with the ability of adenylation domains to select their own substrates, the mass change that takes place upon formation of a covalent intermediate thus identifies the substrate. This assay has an advantage over traditional radiochemical assays in that many substrates, the substrate pool, can be screened simultaneously. Using proteins on the nikkomycin, clorobiocin, coumermycin A1, yersiniabactin, pyochelin, and enterobactin biosynthetic pathways as proof of principle, preferred substrates are readily identified from substrate pools. Furthermore, this assay can be used to provide insight into the timing of tailoring events of biosynthetic pathways as demonstrated using the bromination reaction found on the jamaicamide biosynthetic pathway. Finally, this assay can provide insight into the role and function of orphan gene clusters for which the encoded natural product is unknown. This is demonstrated by identifying the substrates for two NRPS modules from the pksN and pksJ genes that are found on an orphan NRPS/PKS hybrid cluster from Bacillus subtilis. This new assay format is especially timely for activity screening in an era when new types of thiotemplate assembly lines that defy classification are being discovered at an accelerating rate.

Fuel Reforming Technologies (BRIEFING SLIDES)

DTIC Science & Technology

2009-09-01

Heat and Mass Transfer , Catalysis...Gallons Of Fuel/Day/1100men Deployment  To Reduce Noise/Thermal Signature And 4 Environmental Emissions Advanced Heat and Mass Transfer 5 Advanced... Heat and Mass & Transfer Technologies Objective Identify And Develop New Technologies To Enhance Heat And Mass Transfer In Deployed Energy

Wafer-Level Membrane-Transfer Process for Fabricating MEMS

NASA Technical Reports Server (NTRS)

Yang, Eui-Hyeok; Wiberg, Dean

2003-01-01

A process for transferring an entire wafer-level micromachined silicon structure for mating with and bonding to another such structure has been devised. This process is intended especially for use in wafer-level integration of microelectromechanical systems (MEMS) that have been fabricated on dissimilar substrates. Unlike in some older membrane-transfer processes, there is no use of wax or epoxy during transfer. In this process, the substrate of a wafer-level structure to be transferred serves as a carrier, and is etched away once the transfer has been completed. Another important feature of this process is that two electrodes constitutes an electrostatic actuator array. An SOI wafer and a silicon wafer (see Figure 1) are used as the carrier and electrode wafers, respectively. After oxidation, both wafers are patterned and etched to define a corrugation profile and electrode array, respectively. The polysilicon layer is deposited on the SOI wafer. The carrier wafer is bonded to the electrode wafer by using evaporated indium bumps. The piston pressure of 4 kPa is applied at 156 C in a vacuum chamber to provide hermetic sealing. The substrate of the SOI wafer is etched in a 25 weight percent TMAH bath at 80 C. The exposed buried oxide is then removed by using 49 percent HF droplets after an oxygen plasma ashing. The SOI top silicon layer is etched away by using an SF6 plasma to define the corrugation profile, followed by the HF droplet etching of the remaining oxide. The SF6 plasma with a shadow mask selectively etches the polysilicon membrane, if the transferred membrane structure needs to be patterned. Electrostatic actuators with various electrode gaps have been fabricated by this transfer technique. The gap between the transferred membrane and electrode substrate is very uniform ( 0.1 m across a wafer diameter of 100 mm, provided by optimizing the bonding control). Figure 2 depicts the finished product.

Conceptual models governing leaching behavior and their long-term predictive capability

USGS Publications Warehouse

Claassen, Hans C.

1981-01-01

Six models that may be used to describe the interaction of radioactive waste solids with aqueous solutions are as follows:Simple linear mass transfer;Simple parabolic mass transfer;Parabolic mass transfer with the formation of a diffusion-limiting surface layer at an arbitrary time;Initial parabolic mass transfer followed by linear mass transfer at an arbitrary time;Parabolic (or linear) mass transfer and concomitant surface sorption; andParabolic (or linear) mass transfer and concomitant chemical precipitation.Some of these models lead to either illogical or unrealistic predictions when published data are extrapolated to long times. These predictions result because most data result from short-term experimentation. Probably for longer times, processes will occur that have not been observed in the shorter experiments. This hypothesis has been verified by mass-transfer data from laboratory experiments using natural volcanic glass to predict the composition of groundwater. That such rate-limiting mechanisms do occur is reassuring, although now it is not possible to deduce a single mass-transfer limiting mechanism that could control the solution concentration of all components of all waste forms being investigated. Probably the most reasonable mechanisms are surface sorption and chemical precipitation of the species of interest. Another is limiting of mass transfer by chemical precipitation on the waste form surface of a substance not containing the species of interest, that is, presence of a diffusion-limiting layer. The presence of sorption and chemical precipitation as factors limiting mass transfer has been verified in natural groundwater systems, whereas the diffusion-limiting mechanism has not been verified yet.

Impact of kinetic mass transfer on free convection in a porous medium

NASA Astrophysics Data System (ADS)

Lu, Chunhui; Shi, Liangsheng; Chen, Yiming; Xie, Yueqing; Simmons, Craig T.

2016-05-01

We investigate kinetic mass transfer effects on unstable density-driven flow and transport processes by numerical simulations of a modified Elder problem. The first-order dual-domain mass transfer model coupled with a variable-density-flow model is employed to describe transport behavior in porous media. Results show that in comparison to the no-mass-transfer case, a higher degree of instability and more unstable system is developed in the mass transfer case due to the reduced effective porosity and correspondingly a larger Rayleigh number (assuming permeability is independent on the mobile porosity). Given a constant total porosity, the magnitude of capacity ratio (i.e., immobile porosity/mobile porosity) controls the macroscopic plume profile in the mobile domain, while the magnitude of mass transfer timescale (i.e., the reciprocal of the mass transfer rate coefficient) dominates its evolution rate. The magnitude of capacity ratio plays an important role on the mechanism driving the mass flux into the aquifer system. Specifically, for a small capacity ratio, solute loading is dominated by the density-driven transport, while with increasing capacity ratio local mass transfer dominated solute loading may occur at later times. At significantly large times, however, both mechanisms contribute comparably to solute loading. Sherwood Number could be a nonmonotonic function of mass transfer timescale due to complicated interactions of solute between source zone, mobile zone and immobile zone in the top boundary layer, resulting in accordingly a similar behavior of the total mass. The initial assessment provides important insights into unstable density-driven flow and transport in the presence of kinetic mass transfer.

Photoelectron spectroscopy study of the electronic structures at CoPc/Bi(111) interface

NASA Astrophysics Data System (ADS)

Sun, Haoliang; Liang, Zhaofeng; Shen, Kongchao; Hu, Jinbang; Ji, Gengwu; Li, Zheshen; Li, Haiyang; Zhu, Zhiyuan; Li, Jiong; Gao, Xingyu; Han, Huang; Jiang, Zheng; Song, Fei

2017-07-01

Self-assembly of functional molecules on solid substrate has been recognized as an appealing approach for the fabrication of diverse nanostructures for nanoelectronics. Herein, we investigate the growth of cobalt phthalocyanine (CoPc) on a Bi(111) surface with focus on the interface electronic structures utilizing photoelectron spectroscopy. While charge transfer from bismuth substrate to the molecule results in the emergence of an interface component in the Co 3p core level at lower binding energy, core-levels associated to the molecular ligand (C 1s and N 1s) are less influenced by the adsorption. In addition, density functional theory (DFT) calculations also support the empirical inference that the molecule-substrate interaction mainly involves the out-of-plane empty Co 3d orbital and bismuth states. Finally, valence band spectra demonstrate the molecule-substrate interaction is induced by interface charge transfer, agreeing well with core level measurements. Charge transfer is shown to be mainly from the underlying bismuth substrate to the empty states located at the central Co atom in the CoPc molecules. This report may provide a fundamental basis to the on-surface engineering of interfaces for molecular devices and spintronics.

Corynebacterium diphtheriae methionine sulfoxide reductase a exploits a unique mycothiol redox relay mechanism.

PubMed

Tossounian, Maria-Armineh; Pedre, Brandán; Wahni, Khadija; Erdogan, Huriye; Vertommen, Didier; Van Molle, Inge; Messens, Joris

2015-05-01

Methionine sulfoxide reductases are conserved enzymes that reduce oxidized methionines in proteins and play a pivotal role in cellular redox signaling. We have unraveled the redox relay mechanisms of methionine sulfoxide reductase A of the pathogen Corynebacterium diphtheriae (Cd-MsrA) and shown that this enzyme is coupled to two independent redox relay pathways. Steady-state kinetics combined with mass spectrometry of Cd-MsrA mutants give a view of the essential cysteine residues for catalysis. Cd-MsrA combines a nucleophilic cysteine sulfenylation reaction with an intramolecular disulfide bond cascade linked to the thioredoxin pathway. Within this cascade, the oxidative equivalents are transferred to the surface of the protein while releasing the reduced substrate. Alternatively, MsrA catalyzes methionine sulfoxide reduction linked to the mycothiol/mycoredoxin-1 pathway. After the nucleophilic cysteine sulfenylation reaction, MsrA forms a mixed disulfide with mycothiol, which is transferred via a thiol disulfide relay mechanism to a second cysteine for reduction by mycoredoxin-1. With x-ray crystallography, we visualize two essential intermediates of the thioredoxin relay mechanism and a cacodylate molecule mimicking the substrate interactions in the active site. The interplay of both redox pathways in redox signaling regulation forms the basis for further research into the oxidative stress response of this pathogen. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Prediction of mass transfer coefficient in rotating bed contactor (Higee) using artificial neural network

NASA Astrophysics Data System (ADS)

Saha, Dipendu

2009-02-01

The feasibility of drastically reducing the contactor size in mass transfer processes utilizing centrifugal field has generated a lot of interest in rotating packed bed (Higee). Various investigators have proposed correlations to predict mass transfer coefficients in Higee, but, none of the correlations was more than 20-30% accurate. In this work, artificial neural network (ANN) is employed for predicting mass transfer coefficient data. Results show that ANN provides better estimation of mass transfer coefficient with accuracy 5-15%.

Nanofabrication on unconventional substrates using transferred hard masks

DOE PAGES

Li, Luozhou; Bayn, Igal; Lu, Ming; ...

2015-01-15

Here, a major challenge in nanofabrication is to pattern unconventional substrates that cannot be processed for a variety of reasons, such as incompatibility with spin coating, electron beam lithography, optical lithography, or wet chemical steps. Here, we present a versatile nanofabrication method based on re-usable silicon membrane hard masks, patterned using standard lithography and mature silicon processing technology. These masks, transferred precisely onto targeted regions, can be in the millimetre scale. They allow for fabrication on a wide range of substrates, including rough, soft, and non-conductive materials, enabling feature linewidths down to 10 nm. Plasma etching, lift-off, and ion implantationmore » are realized without the need for scanning electron/ion beam processing, UV exposure, or wet etching on target substrates.« less

Devices with extended area structures for mass transfer processing of fluids

DOEpatents

TeGrotenhuis, Ward E.; Wegeng, Robert S.; Whyatt, Greg A.; King, David L.; Brooks, Kriston P.; Stenkamp, Victoria S.

2009-04-21

A microchannel device includes several mass transfer microchannels to receive a fluid media for processing at least one heat transfer microchannel in fluid communication with a heat transfer fluid defined by a thermally conductive wall, and at several thermally conductive fins each connected to the wall and extending therefrom to separate the mass transfer microchannels from one another. In one form, the device may optionally include another heat transfer microchannel and corresponding wall that is positioned opposite the first wall and has the fins and the mass transfer microchannels extending therebetween.

A molecular dynamics simulation study of amino acid selectivity of LeuRS editing domain from Thermus thermophilus.

PubMed

Rayevsky, Alexey; Sharifi, Mohsen; Tukalo, Michael

2018-06-18

The accuracy of protein synthesis is provided by the editing functions of aminoacyl-tRNA synthetases (aaRSs), a mechanism that eliminates misactivated amino acids or mischarged tRNAs. Despite research efforts, some molecular bases of these mechanisms are still unclear. The post-transfer editing pathway of leucyl-tRNA synthetase (LeuRS) carried out in a special insertion domain (the Connective Polypeptide 1 or CP1), as editing domain. Recently, it was shown by in vivo studies and was supported by mutagenesis, and the kinetics approaches that the CP1 domain of LeuRS has discriminatory power for different substrates. The goal of this work is to investigate the structural basis for amino acid recognition of LeuRS post-transfer editing processes with molecular dynamics (MD) simulation method. To pursue this aim, the molecular modeling studies on Thermus thermophiles LeuRS (LeuRSTT) with two post-transfer substrates (norvalyl-tRNA Leu and isoleucyl-tRNA Leu ) was performed. Our results revealed that post-transfer substrate norvalyl-tRNA Leu is more favorable. Moreover, the MD simulations show that branched side chain of Ile-A76 cannot allow water molecules to get close, which leads to a significant decrease in the rate of hydrolysis. Finally, the study showed that site mutation Asp347Ala has elucidated a number of fine structural differences in the binding mode of two post-transfer substrates to the active centre of LeuRS editing domain and two conserved threonines, namely Thr247 and Thr248, are responsible for the amino acid selection through the interaction with substrates. Copyright © 2018 Elsevier Inc. All rights reserved.

Multiple isotope effects with alternative dinucleotide substrates as a probe of the malic enzyme reaction

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

Weiss, P.M.; Urbauer, J.L.; Cleland, W.W.

1991-06-11

Deuterium isotope effects and {sup 13}C isotope effects with deuterium- and protium-labeled malate have been obtained for both NAD- and NADP-malic enzymes by using a variety of alternative dinucleotide substrates. With nicotinamide-containing dinucleotides as the oxidizing substrate, the {sup 13}C effect decreases when deuterated malate is the substrate compared to the value obtained with protium-labeled malate. These data are consistent with a stepwise chemical mechanism in which hydride transfer precedes decarboxylation of the oxalacetate intermediate as previously proposed. When dinucleotide substrates such as thio-NAD, 3-nicotinamide rings are used, the {sup 13}C effect increases when deuterated malate is the substrate comparedmore » to the value obtained with protium-labeled malate. These data, at face value, are consistent with a change in mechanism from stepwise to concerted for the oxidative decarboxylation portion of the mechanism. However, the increase in the deuterium isotope effect from 1.5 to 3 with a concomitant decrease in the {sup 13}C isotope effect from 1.034 to 1.003 as the dinucleotide substrate is changed suggests that the reaction may still be stepwise with the non-nicotinamide dinucleotides. A more likely explanation is that a {beta}-secondary {sup 13}C isotope effect accompanies hydride transfer as a result of hyperconjugation of the {beta}-carboxyl of malate as the transition state for the hydride transfer step is approached.« less

Effect of the submergence, the bed form geometry, and the speed of the surface water flow on the mitigation of pesticides in agricultural ditches

NASA Astrophysics Data System (ADS)

Boutron, Olivier; Margoum, Christelle; Chovelon, Jean-Marc; Guillemain, CéLine; Gouy, VéRonique

2011-08-01

Pesticides, which have been extensively used in agriculture, have become a major environmental issue, especially regarding surface and groundwater contamination. Of particular importance are vegetated farm drainage ditches, which can play an important role in the mitigation of pesticide contamination by adsorption onto ditch bed substrates. This role is, however, poorly understood, especially regarding the influence of hydrodynamic parameters, which make it difficult to promote best management practice of these systems. We have assessed the influence of three of these parameters (speed of the surface water flow, submergence, and geometrical characteristics of the bed forms) on the transfer and adsorption of selected pesticides (isoproturon, diuron, tebuconazole, and azoxystrobin) into the bed substrate by performing experiments with a tilted experimental flume, using hemp fibers as a standard of natural organic substrates that are found at the bottom of agricultural ditches. Results show the transfer of pesticides from surface water flow into bed substrate is favored, both regarding the amounts transferred into the bed substrate and the kinetics of the transfer, when the surface water speed and the submergence increase and when the bed forms are made of rectangular shapes. Extrapolation of flume data over a distance of several hundred meters suggests that an interesting possibility for improving the mitigation of pesticides in ditches would be to increase the submergence and to favor bed forms that tend to enhance perturbations and subsequent infiltration of the surface water flow.

Cell-printing and transfer technology applications for bone defects in mice.

PubMed

Tsugawa, Junichi; Komaki, Motohiro; Yoshida, Tomoko; Nakahama, Ken-ichi; Amagasa, Teruo; Morita, Ikuo

2011-10-01

Bone regeneration therapy based on the delivery of osteogenic factors and/or cells has received a lot of attention in recent years since the discovery of pluripotent stem cells. We reported previously that the implantation of capillary networks engineered ex vivo by the use of cell-printing technology could improve blood perfusion. Here, we developed a new substrate prepared by coating glass with polyethylene glycol (PEG) to create a non-adhesive surface and subsequent photo-lithography to finely tune the adhesive property for efficient cell transfer. We examined the cell-transfer efficiency onto amniotic membrane and bone regenerative efficiency in murine calvarial bone defect. Cell transfer of KUSA-A1 cells (murine osteoblasts) to amniotic membrane was performed for 1 h using the substrates. Cell transfer using the substrate facilitated cell engraftment onto the amniotic membrane compared to that by direct cell inoculation. KUSA-A1 cells transferred onto the amniotic membrane were applied to critical-sized calvarial bone defects in mice. Micro-computed tomography (micro-CT) analysis showed rapid and effective bone formation by the cell-equipped amniotic membrane. These results indicate that the cell-printing and transfer technology used to create the cell-equipped amniotic membrane was beneficial for the cell delivery system. Our findings support the development of a biologically stable and effective bone regeneration therapy. Copyright © 2011 John Wiley & Sons, Ltd.

Scalable transfer of vertical graphene nanosheets for flexible supercapacitor applications

NASA Astrophysics Data System (ADS)

Sahoo, Gopinath; Ghosh, Subrata; Polaki, S. R.; Mathews, Tom; Kamruddin, M.

2017-10-01

Vertical graphene nanosheets (VGN) are the material of choice for application in next-generation electronic devices. The growing demand for VGN-based flexible devices for the electronics industry brings in restriction on VGN growth temperature. The difficulty associated with the direct growth of VGN on flexible substrates can be overcome by adopting an effective strategy of transferring the well-grown VGN onto arbitrary flexible substrates through a soft chemistry route. In the present study, we report an inexpensive and scalable technique for the polymer-free transfer of VGN onto arbitrary substrates without disrupting its morphology, structure, and properties. After transfer, the morphology, chemical structure, and electrical properties are analyzed by scanning electron microscopy, Raman spectroscopy, x-ray photoelectron spectroscopy, and four-probe resistive methods, respectively. The wetting properties are studied from the water contact angle measurements. The observed results indicate the retention of morphology, surface chemistry, structure, and electronic properties. Furthermore, the storage capacity of the transferred VGN-based binder-free and current collector-free flexible symmetric supercapacitor device is studied. A very low sheet resistance of 670 Ω/□ and excellent supercapacitance of 158 μF cm-2 with 86% retention after 10 000 cycles show the prospect of the damage-free VGN transfer approach for the fabrication of flexible nanoelectronic devices.

Printing transferable components using microstructured elastomeric surfaces with pressure modulated reversible adhesion

DOEpatents

Menard, Etienne; Rogers, John A.; Kim, Seok; Carlson, Andrew

2016-08-09

In a method of printing a transferable component, a stamp including an elastomeric post having three-dimensional relief features protruding from a surface thereof is pressed against a component on a donor substrate with a first pressure that is sufficient to mechanically deform the relief features and a region of the post between the relief features to contact the component over a first contact area. The stamp is retracted from the donor substrate such that the component is adhered to the stamp. The stamp including the component adhered thereto is pressed against a receiving substrate with a second pressure that is less than the first pressure to contact the component over a second contact area that is smaller than the first contact area. The stamp is then retracted from the receiving substrate to delaminate the component from the stamp and print the component onto the receiving substrate. Related apparatus and stamps are also discussed.

Trace Impurity Analysis in Ta Films Using Glow Discharge Mass Spectrometry: Concentration Change of Impurities by Applying Negative Substrate Bias Voltage

NASA Astrophysics Data System (ADS)

Lim, Jae-Won; Mimura, Kouji; Isshiki, Minoru

2004-12-01

Glow discharge mass spectrometry (GDMS) was used to analyze a Ta target and Ta films for trace impurities. The Ta films were deposited on Si (100) substrate at substrate bias voltages of 0 V and -125 V using a non-mass separated ion beam deposition system. Although both Ta films were contaminated by impurities during the deposition, the Ta film deposited at a substrate bias voltage of -125 V showed lower impurity content than the Ta film deposited without the substrate bias voltage, which means that applying a negative bias voltage to the substrate decreased the total concentration of impurities. Furthermore, the concentration change of individual impurities in the Ta film is related to their ionization ratio in the argon discharge plasma. Considering the effect of the ionization potential of an individual impurity on the ionization ratio, purification by applying a negative bias voltage to the substrate results from Penning ionization and an ionization mechanism proposed in this study, as well as from the difference between the kinetic energies of Ta neutral atoms and Ta+ ions accelerated toward the substrate with/without a negative substrate bias voltage.

Revealing metabolic storage processes in electrode respiring bacteria by differential electrochemical mass spectrometry.

PubMed

Kubannek, F; Schröder, U; Krewer, U

2018-06-01

In this work we employ differential electrochemical mass spectrometry (DEMS) in combination with static and dynamic electrochemical techniques for the study of metabolic processes of electrochemically active bacteria. CO 2 production during acetate oxidation by electrode respiring bacteria was measured, in-vivo and online with a sensitivity of 6.5 ⋅ 10 -13 mol/s. The correlation of ion current and electrical current provides insight into the interaction of metabolic processes and extra-cellular electron transfer. In low-turnover CVs, two competing potential dependent electron transfer mechanisms were observed and formal potentials of two redox systems that are involved in complete oxidation of acetate to CO 2 were determined. By balancing charge and carbon flows during dynamic measurements, two significant storage mechanisms in electrochemically active bacteria were identified: 1) a charge storage mechanism that allows substrate oxidation to proceed at a constant rate despite of external current flowing in cathodic direction. 2) a carbon storage mechanism that allows the biofilm to take up acetate at an unchanged rate at very low potentials even though the oxidation to CO 2 stops. These storage capabilities allow a limited decoupling of electrical current and CO 2 production rate. Copyright © 2018 Elsevier B.V. All rights reserved.

Formation mechanism and mechanics of dip-pen nanolithography using molecular dynamics.

PubMed

Wu, Cheng-Da; Fang, Te-Hua; Lin, Jen-Fin

2010-03-02

Molecular dynamics simulations are used to investigate the mechanisms of molecular transference, pattern formation, and mechanical behavior in the dip-pen nanolithography (DPN) process. The effects of deposition temperature were studied using molecular trajectories, the meniscus characteristic, surface absorbed energy, and pattern formation analysis. At the first transferred stage (at the initial indentation depth), the conformation of SAM molecules lies almost on the substrate surface. The molecules start to stand on the substrate due to the pull and drag forces at the second transferred stage (after the tip is pulled up). According to the absorbed energy behavior, the second transferred stage has larger transferred amounts and the transfer rate is strongly related to temperature. When molecules were deposited at low temperature (e.g., room temperature), the pattern shape was more highly concentrated. The pattern shape at high temperatures expanded and the area increased because of good molecular diffusion.

HIV‑1 Integrase Strand Transfer Inhibitors with Reduced Susceptibility to Drug Resistant Mutant Integrases | Center for Cancer Research

Cancer.gov

On the cover: Mutant forms of HIV-1 IN reduce the therapeutic effectiveness of integrase strand transfer inhibitors (INSTIs). The cover figure shows the IN of prototype foamy virus complexed to a novel INSTI (gold) that retains potency against resistant mutants of HIV-1 IN. Overlain are the host and viral DNA substrates (blue and green, respectively), showing substrate mimicry

Aerobic microbial mineralization of dichloroethene as sole carbon substrate

USGS Publications Warehouse

Bradley, P.M.; Chapelle, F.H.

2000-01-01

Microorganisms indigenous to the bed sediments of a black- water stream utilized 1,2-dichloroethene (1,2-DCE) as a sole carbon substrate for aerobic metabolism. Although no evidence of growth was observed in the minimal salts culture media used in this study, efficient aerobic microbial mineralization of 1,2-DCE as sole carbon substrate was maintained through three sequential transfers (107 final dilution) of the original environmental innoculum. These results indicate that 1,2-DCE can be utilized as a primary substrate to support microbial metabolism under aerobic conditions.Microorganisms indigenous to the bed sediments of a black-water stream utilized 1,2-dichloroethene (1,2-DCE) as a sole carbon substrate for aerobic metabolism. Although no evidence of growth was observed in the minimal salts culture media used in this study, efficient aerobic microbial mineralization of 1,2-DCE as sole carbon substrate was maintained through three sequential transfers (107 final dilution) of the original environmental innoculum. These results indicate that 1,2-DCE can be utilized as a primary substrate to support microbial metabolism under aerobic conditions.

Hydride transfer made easy in the oxidation of alcohols catalyzed by choline oxidase

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

Gadda, G.; Orville, A.; Pennati, A.

2008-06-08

Choline oxidase (E.C. 1.1.3.17) catalyzes the two-step, four-electron oxidation of choline to glycine betaine with betaine aldehyde as enzyme-associated intermediate and molecular oxygen as final electron acceptor (Scheme 1). The gem-diol, hydrated species of the aldehyde intermediate of the reaction acts as substrate for aldehyde oxidation, suggesting that the enzyme may use similar strategies for the oxidation of the alcohol substrate and aldehyde intermediate. The determination of the chemical mechanism for alcohol oxidation has emerged from biochemical, mechanistic, mutagenetic, and structural studies. As illustrated in the mechanism of Scheme 2, the alcohol substrate is initially activated in the active sitemore » of the enzyme by removal of the hydroxyl proton. The resulting alkoxide intermediate is then stabilized in the enzyme-substrate complex via electrostatic interactions with active site amino acid residues. Alcohol oxidation then occurs quantum mechanically via the transfer of the hydride ion from the activated substrate to the N(5) flavin locus. An essential requisite for this mechanism of alcohol oxidation is the high degree of preorganization of the activated enzyme-substrate complex, which is achieved through an internal equilibrium of the Michaelis complex occurring prior to, and independently from, the subsequent hydride transfer reaction. The experimental evidence that support the mechanism for alcohol oxidation shown in Scheme 2 is briefly summarized in the Results and Discussion section.« less

Identification of peptidase substrates in human plasma by FTMS based differential mass spectrometry

NASA Astrophysics Data System (ADS)

Yates, Nathan A.; Deyanova, Ekaterina G.; Geissler, Wayne; Wiener, Matthew C.; Sachs, Jeffrey R.; Wong, Kenny K.; Thornberry, Nancy A.; Sinha Roy, Ranabir; Settlage, Robert E.; Hendrickson, Ronald C.

2007-01-01

Approximately 2% of the human genome encodes for proteases. Unfortunately, however, the biological roles of most of these enzymes remain poorly defined, since the physiological substrates are typically unknown and are difficult to identify using traditional methods. We have developed a proteomics experiment based on FTMS profiling and differential mass spectrometry (dMS) to identify candidate endogenous substrates of proteases using fractionated human plasma as the candidate substrate pool. Here we report proof-of-concept experiments for identifying in vitro substrates of aminopeptidase P2, (APP2) and dipeptidyl peptidase 4 (DPP-4), a peptidase of therapeutic interest for the treatment of type 2 diabetes. For both proteases, previously validated peptide substrates spiked into the human plasma pool were identified. Of note, the differential mass spectrometry experiments also identified novel substrates for each peptidase in the subfraction of human plasma. Targeted MS/MS analysis of these peptides in the complex human plasma pool and manual confirmation of the amino acid sequences led to the identification of these substrates. The novel DPP-4 substrate EPLGRQLTSGP was chemically synthesized and cleavage kinetics were determined in an in vitro DPP-4 enzyme assay. The apparent second order rate constant (kcat/KM) for DPP-4-mediated cleavage was determined to be 2.3 x 105 M-1 s-1 confirming that this peptide is efficiently processed by the peptidase in vitro. Collectively, these results demonstrate that differential mass spectrometry has the potential to identify candidate endogenous substrates of target proteases from a human plasma pool. Importantly, knowledge of the endogenous substrates can provide useful insight into the biology of these enzymes and provides useful biomarkers for monitoring their activity in vivo.

Photo-fermentative hydrogen production from crop residue: A mini review.

PubMed

Zhang, Quanguo; Wang, Yi; Zhang, Zhiping; Lee, Duu-Jong; Zhou, Xuehua; Jing, Yanyan; Ge, Xumeng; Jiang, Danping; Hu, Jianjun; He, Chao

2017-04-01

Photofermentative hydrogen production from crop residues, if feasible, can lead to complete conversion of organic substances to hydrogen (and carbon dioxide). This mini review lists the studies on photofermentative hydrogen production using crop residues as feedstock. Pretreatment methods, substrate structure, mechanism of photosynthetic bacteria growth and metabolism were discussed. Photofermentative hydrogen production from pure culture, consortia and mutants, and the geometry, light sources, mass transfer resistances and the operational strategies of the photo-bioreactor were herein reviewed. Future studies of regulation mechanism of photosynthetic bacteria, such as highly-efficient strain breeding and gene reconstruction, and development of new-generation photo-bioreactor were suggested. Copyright © 2017 Elsevier Ltd. All rights reserved.

Redox inactive metal ion triggered N-dealkylation by an iron catalyst with dioxygen activation: a lesson from lipoxygenases.

PubMed

Zhang, Jisheng; Wang, Yujuan; Luo, Nengchao; Chen, Zhuqi; Wu, Kangbing; Yin, Guochuan

2015-06-07

Utilization of dioxygen as the terminal oxidant at ambient temperature is always a challenge in redox chemistry, because it is hard to oxidize a stable redox metal ion like iron(III) to its high oxidation state to initialize the catalytic cycle. Inspired by the dioxygenation and co-oxidase activity of lipoxygenases, herein, we introduce an alternative protocol to activate the sluggish iron(III) species with non-redox metal ions, which can promote its oxidizing power to facilitate substrate oxidation with dioxygen, thus initializing the catalytic cycle. In oxidations of N,N-dimethylaniline and its analogues, adding Zn(OTf)2 to the [Fe(TPA)Cl2]Cl catalyst can trigger the amine oxidation with dioxygen, whereas [Fe(TPA)Cl2]Cl alone is very sluggish. In stoichiometric oxidations, it has also been confirmed that the presence of Zn(OTf)2 can apparently improve the electron transfer capability of the [Fe(TPA)Cl2]Cl complex. Experiments using different types of substrates as trapping reagents disclosed that the iron(IV) species does not occur in the catalytic cycle, suggesting that oxidation of amines is initialized by electron transfer rather than hydrogen abstraction. Combined experiments from UV-Vis, high resolution mass spectrometry, electrochemistry, EPR and oxidation kinetics support that the improved electron transfer ability of iron(III) species originates from its interaction with added Lewis acids like Zn(2+) through a plausible chloride or OTf(-) bridge, which has promoted the redox potential of iron(III) species. The amine oxidation mechanism was also discussed based on the available data, which resembles the co-oxidase activity of lipoxygenases in oxidative dealkylation of xenobiotic metabolisms where an external electron donor is not essential for dioxygen activation.

Atomic and electronic structure of trilayer graphene/SiC(0001): Evidence of Strong Dependence on Stacking Sequence and charge transfer.

PubMed

Pierucci, Debora; Brumme, Thomas; Girard, Jean-Christophe; Calandra, Matteo; Silly, Mathieu G; Sirotti, Fausto; Barbier, Antoine; Mauri, Francesco; Ouerghi, Abdelkarim

2016-09-15

The transport properties of few-layer graphene are the directly result of a peculiar band structure near the Dirac point. Here, for epitaxial graphene grown on SiC, we determine the effect of charge transfer from the SiC substrate on the local density of states (LDOS) of trilayer graphene using scaning tunneling microscopy/spectroscopy and angle resolved photoemission spectroscopy (ARPES). Different spectra are observed and are attributed to the existence of two stable polytypes of trilayer: Bernal (ABA) and rhomboedreal (ABC) staking. Their electronic properties strongly depend on the charge transfer from the substrate. We show that the LDOS of ABC stacking shows an additional peak located above the Dirac point in comparison with the LDOS of ABA stacking. The observed LDOS features, reflecting the underlying symmetry of the two polytypes, were reproduced by explicit calculations within density functional theory (DFT) including the charge transfer from the substrate. These findings demonstrate the pronounced effect of stacking order and charge transfer on the electronic structure of trilayer or few layer graphene. Our approach represents a significant step toward understand the electronic properties of graphene layer under electrical field.

A cluster of carboxylic groups in PsbO protein is involved in proton transfer from the water oxidizing complex of Photosystem II.

PubMed

Shutova, Tatiana; Klimov, Vyacheslav V; Andersson, Bertil; Samuelsson, Göran

2007-06-01

The hypothesis presented here for proton transfer away from the water oxidation complex of Photosystem II (PSII) is supported by biochemical experiments on the isolated PsbO protein in solution, theoretical analyses of better understood proton transfer systems like bacteriorhodopsin and cytochrome oxidase, and the recently published 3D structure of PS II (Pdb entry 1S5L). We propose that a cluster of conserved glutamic and aspartic acid residues in the PsbO protein acts as a buffering network providing efficient acceptors of protons derived from substrate water molecules. The charge delocalization of the cluster ensures readiness to promptly accept the protons liberated from substrate water. Therefore protons generated at the catalytic centre of PSII need not be released into the thylakoid lumen as generally thought. The cluster is the beginning of a localized, fast proton transfer conduit on the lumenal side of the thylakoid membrane. Proton-dependent conformational changes of PsbO may play a role in the regulation of both supply of substrate water to the water oxidizing complex and the resultant proton transfer.

Method for materials deposition by ablation transfer processing

DOEpatents

Weiner, K.H.

1996-04-16

A method in which a thin layer of semiconducting, insulating, or metallic material is transferred by ablation from a source substrate, coated uniformly with a thin layer of said material, to a target substrate, where said material is desired, with a pulsed, high intensity, patternable beam of energy. The use of a patternable beam allows area-selective ablation from the source substrate resulting in additive deposition of the material onto the target substrate which may require a very low percentage of the area to be covered. Since material is placed only where it is required, material waste can be minimized by reusing the source substrate for depositions on multiple target substrates. Due to the use of a pulsed, high intensity energy source the target substrate remains at low temperature during the process, and thus low-temperature, low cost transparent glass or plastic can be used as the target substrate. The method can be carried out atmospheric pressures and at room temperatures, thus eliminating vacuum systems normally required in materials deposition processes. This invention has particular application in the flat panel display industry, as well as minimizing materials waste and associated costs. 1 fig.

Mass transfer in white dwarf-neutron star binaries

NASA Astrophysics Data System (ADS)

Bobrick, Alexey; Davies, Melvyn B.; Church, Ross P.

2017-05-01

We perform hydrodynamic simulations of mass transfer in binaries that contain a white dwarf and a neutron star (WD-NS binaries), and measure the specific angular momentum of material lost from the binary in disc winds. By incorporating our results within a long-term evolution model, we measure the long-term stability of mass transfer in these binaries. We find that only binaries containing helium white dwarfs (WDs) with masses less than a critical mass of MWD, crit = 0.2 M⊙ undergo stable mass transfer and evolve into ultracompact X-ray binaries. Systems with higher mass WDs experience unstable mass transfer, which leads to tidal disruption of the WD. Our low critical mass compared to the standard jet-only model of mass-loss arises from the efficient removal of angular momentum in the mechanical disc winds, which develop at highly super-Eddington mass-transfer rates. We find that the eccentricities expected for WD-NS binaries when they come into contact do not affect the loss of angular momentum, and can only affect the long-term evolution if they change on shorter time-scales than the mass-transfer rate. Our results are broadly consistent with the observed numbers of both ultracompact X-ray binaries and radio pulsars with WD companions. The observed calcium-rich gap transients are consistent with the merger rate of unstable systems with higher mass WDs.

The effects of dual-domain mass transfer on the tritium-helium-3 dating method.

PubMed

Neumann, Rebecca B; Labolle, Eric M; Harvey, Charles F

2008-07-01

Diffusion of tritiated water (referred to as tritium) and helium-3 between mobile and immobile regions in aquifers (mass transfer) can affect tritium and helium-3 concentrations and hence tritium-helium-3 (3H/3He) ages that are used to estimate aquifer recharge and groundwater residence times. Tritium and helium-3 chromatographically separate during transport because their molecular diffusion coefficients differ. Simulations of tritium and helium-3 transport and diffusive mass transfer along stream tubes show that mass transfer can shift the 3H/3He age of the tritium and helium-3 concentration ([3H + 3He]) peak to dates much younger than the 1963 peak in atmospheric tritium. Furthermore, diffusive mass-transfer can cause the 3H/3He age to become younger downstream along a stream tube, even as the mean water-age must increase. Simulated patterns of [3H + 3He] versus 3H/3He age using a mass transfer model appear consistent with a variety of field data. These results suggest that diffusive mass transfer should be considered, especially when the [3H + 3He] peak is not well defined or appears younger than the atmospheric peak. 3H/3He data provide information about upstream mass-transfer processes that could be used to constrain mass-transfer models; however, uncritical acceptance of 3H/3He dates from aquifers with immobile regions could be misleading.

Residue-and-polymer-free graphene transfer: DNA-CTMA/graphene/GaN bio-hybrid photodiode for light-sensitive applications

NASA Astrophysics Data System (ADS)

Reddy, M. Siva Pratap; Park, Herie; Lee, Jung-Hee

2018-02-01

In this work, we present a residue-and-polymer-free graphene transfer method by using the adhesive force between graphene and a target substrate, the hydrophobic property of graphene, and the surface tension of the solutions. We used an n-type GaN substrate as the target substrate to make a photodiode (PD). Recently, the inclusion of biomolecules in photodetection technology has attracted considerable attention in the electronics and photonics research, particularly due to the rapid evolution of organic-inorganic bio-hybrid PDs (Bio-HPDs). This report presents a significant photoresponse of the bioinspired graphene-based PD fabricated with deoxyribonucleic acid-cetyltrimetylammonium chloride (DNA-CTMA) biomolecules on the n-type GaN substrate. Bio-HPDs respond to the infrared, visible, and ultraviolet wavelengths. Moreover, the Bio-HPDs show photosensitivities (Iphoto/Idark) of 21, 143, and 1194 for infrared, visible, and ultraviolet wavebands, respectively, which can be attributed to the integration of high-mobility graphene and photosensitive DNA-CTMA biomolecules. In addition, the corresponding charge transfer mechanisms in the PDs are explained by energy band diagrams.

Pressure activated interconnection of micro transfer printed components

NASA Astrophysics Data System (ADS)

Prevatte, Carl; Guven, Ibrahim; Ghosal, Kanchan; Gomez, David; Moore, Tanya; Bonafede, Salvatore; Raymond, Brook; Trindade, António Jose; Fecioru, Alin; Kneeburg, David; Meitl, Matthew A.; Bower, Christopher A.

2016-05-01

Micro transfer printing and other forms of micro assembly deterministically produce heterogeneously integrated systems of miniaturized components on non-native substrates. Most micro assembled systems include electrical interconnections to the miniaturized components, typically accomplished by metal wires formed on the non-native substrate after the assembly operation. An alternative scheme establishing interconnections during the assembly operation is a cost-effective manufacturing method for producing heterogeneous microsystems, and facilitates the repair of integrated microsystems, such as displays, by ex post facto addition of components to correct defects after system-level tests. This letter describes pressure-concentrating conductor structures formed on silicon (1 0 0) wafers to establish connections to preexisting conductive traces on glass and plastic substrates during micro transfer printing with an elastomer stamp. The pressure concentrators penetrate a polymer layer to form the connection, and reflow of the polymer layer bonds the components securely to the target substrate. The experimental yield of series-connected test systems with >1000 electrical connections demonstrates the suitability of the process for manufacturing, and robustness of the test systems against exposure to thermal shock, damp heat, and mechanical flexure shows reliability of the resulting bonds.

Room temperature rubbing for few-layer two-dimensional thin flakes directly on flexible polymer substrates

PubMed Central

Yu, Yan; Jiang, Shenglin; Zhou, Wenli; Miao, Xiangshui; Zeng, Yike; Zhang, Guangzu; Liu, Sisi

2013-01-01

The functional layers of few-layer two-dimensional (2-D) thin flakes on flexible polymers for stretchable applications have attracted much interest. However, most fabrication methods are “indirect” processes that require transfer steps. Moreover, previously reported “transfer-free” methods are only suitable for graphene and not for other few-layer 2-D thin flakes. Here, a friction based room temperature rubbing method is proposed for fabricating different types of few-layer 2-D thin flakes (graphene, hexagonal boron nitride (h-BN), molybdenum disulphide (MoS2), and tungsten disulphide (WS2)) on flexible polymer substrates. Commercial 2-D raw materials (graphite, h-BN, MoS2, and WS2) that contain thousands of atom layers were used. After several minutes, different types of few-layer 2-D thin flakes were fabricated directly on the flexible polymer substrates by rubbing procedures at room temperature and without any transfer step. These few-layer 2-D thin flakes strongly adhere to the flexible polymer substrates. This strong adhesion is beneficial for future applications. PMID:24045289

Quasi-steady-state voltammetry of rapid electron transfer reactions at the macroscopic substrate of the scanning electrochemical microscope.

PubMed

Nioradze, Nikoloz; Kim, Jiyeon; Amemiya, Shigeru

2011-02-01

We report on a novel theory and experiment for scanning electrochemical microscopy (SECM) to enable quasi-steady-state voltammetry of rapid electron transfer (ET) reactions at macroscopic substrates. With this powerful approach, the substrate potential is cycled widely across the formal potential of a redox couple while the reactant or product of a substrate reaction is amperometrically detected at the tip in the feedback or substrate generation/tip collection mode, respectively. The plot of tip current versus substrate potential features the retraceable sigmoidal shape of a quasi-steady-state voltammogram although a transient voltammogram is obtained at the macroscopic substrate. Finite element simulations reveal that a short tip-substrate distance and a reversible substrate reaction (except under the tip) are required for quasi-steady-state voltammetry. Advantageously, a pair of quasi-steady-state voltammograms is obtained by employing both operation modes to reliably determine all transport, thermodynamic, and kinetic parameters as confirmed experimentally for rapid ET reactions of ferrocenemethanol and 7,7,8,8-tetracyanoquinodimethane at a Pt substrate with ∼0.5 μm-radius Pt tips positioned at 90 nm-1 μm distances. Standard ET rate constants of ∼7 cm/s were obtained for the latter mediator as the largest determined for a substrate reaction by SECM. Various potential applications of quasi-steady-state voltammetry are also proposed.

A facile alternative technique for large-area graphene transfer via sacrificial polymer

DOE PAGES

Auchter, Eric; Marquez, Justin; Yarbro, Stephen L.; ...

2017-12-07

A novel method of transferring large-area graphene sheets onto a variety of substrates using Formvar (polyvinyl formal) is presented. Due to the ease at which formvar can be dissolved in chloroform this method allows for a consistent, a clean, and a more rapid transfer than other techniques including the PMMA assisted one. This novel transfer method is demonstrated by transferring large-area graphene onto a range of substrates including commercial TEM grids, silicon dioxide and glass. Raman spectroscopy was used to confirm the presence of graphene and characterize the morphological properties of the large-area sheets. SEM and AFM analyses demonstrated themore » effectiveness of our rapid transfer technique for clean crystalline large-area graphene sheets. The removal of the sacrificial polymer was found to be one to two orders of magnitude faster than PMMA methods. Ultimately this facile transfer technique offers new opportunities for a wide range of applications for large-area graphene through the utilization of a new sacrificial polymer.« less

A facile alternative technique for large-area graphene transfer via sacrificial polymer

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

Auchter, Eric; Marquez, Justin; Yarbro, Stephen L.

A novel method of transferring large-area graphene sheets onto a variety of substrates using Formvar (polyvinyl formal) is presented. Due to the ease at which formvar can be dissolved in chloroform this method allows for a consistent, a clean, and a more rapid transfer than other techniques including the PMMA assisted one. This novel transfer method is demonstrated by transferring large-area graphene onto a range of substrates including commercial TEM grids, silicon dioxide and glass. Raman spectroscopy was used to confirm the presence of graphene and characterize the morphological properties of the large-area sheets. SEM and AFM analyses demonstrated themore » effectiveness of our rapid transfer technique for clean crystalline large-area graphene sheets. The removal of the sacrificial polymer was found to be one to two orders of magnitude faster than PMMA methods. Ultimately this facile transfer technique offers new opportunities for a wide range of applications for large-area graphene through the utilization of a new sacrificial polymer.« less

Synthesis and characterization of TiO₂ and TiO₂/Ag for use in photodegradation of methylviologen, with kinetic study by laser flash photolysis.

PubMed

Ramos, Dayana Doffinger; Bezerra, Paula C S; Quina, Frank H; Dantas, Renato F; Casagrande, Gleison A; Oliveira, Silvio C; Oliveira, Márcio R S; Oliveira, Lincoln C S; Ferreira, Valdir S; Oliveira, Samuel L; Machulek, Amilcar

2015-01-01

This paper reports the synthesis, characterization, and application of TiO2 and TiO2/Ag nanoparticles for use in photocatalysis, employing the herbicide methylviologen (MV) as a substrate for photocatalytic activity testing. At suitable metal to oxide ratios, increases in silver surface coating on TiO2 enhanced the efficiency of heterogeneous photocatalysis by increasing the electron transfer constant. The sol-gel method was used for TiO2 synthesis. P25 TiO2 was the control material. Both oxides were subjected to the same silver incorporation process. The materials were characterized by conventional spectroscopy, SEM micrography, X-ray diffraction, calculation of surface area per mass of catalyst, and thermogravimetry. Also, electron transfers between TiO2 or TiO2/Ag and MV in the absence and presence of sodium formate were investigated using laser flash photolysis. Oxides synthesized with 2.0 % silver exhibited superior photocatalytic activity for MV degradation.

Radiative heat transfer in low-dimensional systems -- microscopic mode

NASA Astrophysics Data System (ADS)

Woods, Lilia; Phan, Anh; Drosdoff, David

2013-03-01

Radiative heat transfer between objects can increase dramatically at sub-wavelength scales. Exploring ways to modulate such transport between nano-systems is a key issue from fundamental and applied points of view. We advance the theoretical understanding of radiative heat transfer between nano-objects by introducing a microscopic model, which takes into account the individual atoms and their atomic polarizabilities. This approach is especially useful to investigate nano-objects with various geometries and give a detailed description of the heat transfer distribution. We employ this model to study the heat exchange in graphene nanoribbon/substrate systems. Our results for the distance separations, substrates, and presence of extended or localized defects enable making predictions for tailoring the radiative heat transfer at the nanoscale. Financial support from the Department of Energy under Contract No. DE-FG02-06ER46297 is acknowledged.

Vacancies in epitaxial graphene

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

Davydov, S. Yu., E-mail: Sergei-Davydov@mail.ru

The coherent-potential method is used to consider the problem of the influence of a finite concentration of randomly arranged vacancies on the density of states of epitaxial graphene. To describe the density of states of the substrate, simple models (the Anderson model, Haldane-Anderson model, and parabolic model) are used. The electronic spectrum of free single-sheet graphene is considered in the low-energy approximation. Charge transfer in the graphene-substrate system is discussed. It is shown that, in all cases, the density of states of epitaxial graphene decreases proportionally to the vacancy concentration. At the same time, the average charge transferred from graphenemore » to the substrate increases.« less

Scalable alignment of CdS nanowires based on efficient roll-on transfer technique.

PubMed

Yan, Shancheng; Shi, Yi; Xiao, Zhongdang; Wang, Junzhuan; Hu, Dong; Xul, Xin; Lu, Tao; Liu, Aili; Gao, Fan

2013-06-01

A roll-on transfer strategy is developed to enable large-scale and uniform assembly of CdS nanowires on various rigid and flexible substrate materials. In this method, the CdS nanowires were synthesized by the hydrothermal method. The dispersed CdS NWs could be firstly aligned and selectively deposited at the micro/nanochannels between aligned nanofibers on the surface of the donor roller as a result of evaporation-induced flow and capillary action, and then the directional and aligned transfer of the CdS NWs from the donor roller to a receiver substrate via roll-on transfer technique. Finally, a device structures consisting of the nanowire channel and two metal electrodes was fabricated. The electrical property of this device was observed.

Influence of the boundary conditions on heat and mass transfer in spacer-filled channels

NASA Astrophysics Data System (ADS)

Ciofalo, M.; La Cerva, M. F.; Di Liberto, M.; Tamburini, A.

2017-11-01

The purpose of this study is to discuss some problems which arise in heat or mass transfer in complex channels, with special reference to the spacer-filled channels adopted in membrane processes. Among the issues addressed are the consistent definition of local and mean heat or mass transfer coefficients; the influence of the wall boundary conditions; the influence of one-side versus two-side heat/mass transfer. Most of the results discussed were obtained by finite volume CFD simulations concerning heat transfer in Membrane Distillation or mass transfer in Electrodialysis and Reverse Electrodialysis, but many of the conclusions apply also to different processes involving geometrically complex channels

Method and apparatus for coating a patterned thin film on a substrate from a fluid source with continuous feed capability

DOEpatents

Burrows, Paul E [Kennewick, WA; Sapochak, Linda S [Kennewick, WA

2009-09-22

A method and apparatus for forming patterned coatings of thin film, non-polymerizable compounds on a substrate. A mixture of the non-polymerizable compound and a liquid carrier is pumped into the interior of a heated evaporation box having an internal temperature sufficient to convert substantially all of the non-polymerizable compound and liquid carrier to a gaseous form. The non-polymerizable compound and liquid carrier are then removed from the evaporation box via exit slit in the evaporation box. Adjacent to the exit slit, and maintained in a vacuum, is a first substrate upon which the non-polymerizable compound condenses. The first substrate is in motion, for example on a web roller, thereby allowing a continuous coating of the non-polymerizable compound to be applied to the first substrate. Once the non-polymerizable compound is applied to one side of the first substrate, an energy source is then directed toward the opposite side of the first substrate. In this manner, a portion of the non-polymerizable compound is removed from the first substrate. A second substrate is then provided adjacent to the first substrate, and the non-polymerizable compound is thereby transferred from the first substrate onto the second substrate. By repeatedly transferring portions of the non-polymerizable material from the first substrate to the second substrate in this manner, the thin film, non-polymerizable materials can be formed onto the second substrate in a predetermined pattern, and in a continuous and highly efficient process.

Within-Site Variation in Feather Stable Hydrogen Isotope (δ2Hf) Values of Boreal Songbirds: Implications for Assignment to Molt Origin.

PubMed

Nordell, Cameron J; Haché, Samuel; Bayne, Erin M; Sólymos, Péter; Foster, Kenneth R; Godwin, Christine M; Krikun, Richard; Pyle, Peter; Hobson, Keith A

2016-01-01

Understanding bird migration and dispersal is important to inform full life-cycle conservation planning. Stable hydrogen isotope ratios from feathers (δ2Hf) can be linked to amount-weighted long-term, growing season precipitation δ2H (δ2Hp) surfaces to create δ2Hf isoscapes for assignment to molt origin. However, transfer functions linking δ2Hp with δ2Hf are influenced by physiological and environmental processes. A better understanding of the causes and consequences of variation in δ2Hf values among individuals and species will improve the predictive ability of geographic assignment tests. We tested for effects of species, land cover, forage substrate, nest substrate, diet composition, body mass, sex, and phylogenetic relatedness on δ2Hf from individuals at least two years old of 21 songbird species captured during the same breeding season at a site in northeastern Alberta, Canada. For four species, we also tested for a year × species interaction effect on δ2Hf. A model including species as single predictor received the most support (AIC weight = 0.74) in explaining variation in δ2Hf. A species-specific variance parameter was part of all best-ranked models, suggesting variation in δ2Hf was not consistent among species. The second best-ranked model included a forage substrate × diet interaction term (AIC weight = 0.16). There was a significant year × species interaction effect on δ2Hf suggesting that interspecific differences in δ2Hf can differ among years. Our results suggest that within- and among-year interspecific variation in δ2Hf is the most important source of variance typically not being explicitly quantified in geographic assignment tests using non-specific transfer functions to convert δ2Hp into δ2Hf. However, this source of variation is consistent with the range of variation from the transfer functions most commonly being propagated in assignment tests of geographic origins for passerines breeding in North America.

Power generation using different cation, anion, and ultrafiltration membranes in microbial fuel cells.

PubMed

Kim, Jung Rae; Cheng, Shaoan; Oh, Sang-Eun; Logan, Bruce E

2007-02-01

Proton exchange membranes (PEMs) are often used in microbial fuel cells (MFCs) to separate the liquid in the anode and cathode chambers while allowing protons to pass between the chambers. However, negatively or positively charged species present at high concentrations in the medium can also be used to maintain charge balance during power generation. An anion exchange membrane (AEM) produced the largest power density (up to 610 mW/m2) and Coulombic efficiency (72%) in MFCs relative to values achieved with a commonly used PEM (Nafion), a cation exchange membrane (CEM), or three different ultrafiltration (UF) membranes with molecular weight cut offs of 0.5K, 1K, and 3K Daltons in different types of MFCs. The increased performance of the AEM was due to proton charge-transfer facilitated by phosphate anions and low internal resistance. The type of membrane affected maximum power densities in two-chamber, air-cathode cube MFCs (C-MFCs) with low internal resistance (84-91 omega for all membranes except UF-0.5K) but not in two-chamber aqueous-cathode bottle MFCs (B-MFCs) due to their higher internal resistances (1230-1272 omega except UF-0.5K). The UF-0.5K membrane produced very high internal resistances (6009 omega, B-MFC; 1814omega, C-MFC) and was the least permeable to both oxygen (mass transfer coefficient of k(O) = 0.19 x 10(-4) cm/s) and acetate (k(A) = 0.89 x 10(-8) cm/s). Nafion was the most permeable membrane to oxygen (k(O) = 1.3 x 10(-4) cm/s), and the UF-3K membrane was the most permeable to acetate (k(A) = 7.2 x 10(-8) cm/s). Only a small percent of substrate was unaccounted for based on measured Coulombic efficiencies and estimates of biomass production and substrate losses using Nafion, CEM, and AEM membranes (4-8%), while a substantial portion of substrate was lost to unidentified processes for the UF membranes (40-89%). These results show that many types of membranes can be used in two-chambered MFCs, even membranes that transfer negatively charged species.

Synthetic Graphene Grown by Chemical Vapor Deposition on Copper Foils

DTIC Science & Technology

2013-04-11

b) Transparent PMMA /graphene membrane floating on copper etchant. (c) Three layers of stacked CVD graphene on a cover glass made by consecutively...insulating substrate is a critical step for fabricating electronic devices. PMMA -assisted transfer techniques are commonly applied because of their...simplicity and repeatability.13 In a typical transfer, a graphene film on Cu substrate was first coated with PMMA (950PMMA-A4, MicroChem)b by spin

Value-added Synthesis of Graphene: Recycling Industrial Carbon Waste into Electrodes for High-Performance Electronic Devices

PubMed Central

Seo, Hong-Kyu; Kim, Tae-Sik; Park, Chibeom; Xu, Wentao; Baek, Kangkyun; Bae, Sang-Hoon; Ahn, Jong-Hyun; Kim, Kimoon; Choi, Hee Cheul; Lee, Tae-Woo

2015-01-01

We have developed a simple, scalable, transfer-free, ecologically sustainable, value-added method to convert inexpensive coal tar pitch to patterned graphene films directly on device substrates. The method, which does not require an additional transfer process, enables direct growth of graphene films on device substrates in large area. To demonstrate the practical applications of the graphene films, we used the patterned graphene grown on a dielectric substrate directly as electrodes of bottom-contact pentacene field-effect transistors (max. field effect mobility ~0.36 cm2·V−1·s−1), without using any physical transfer process. This use of a chemical waste product as a solid carbon source instead of commonly used explosive hydrocarbon gas sources for graphene synthesis has the dual benefits of converting the waste to a valuable product, and reducing pollution. PMID:26567845

Repeated growth and bubbling transfer of graphene with millimetre-size single-crystal grains using platinum.

PubMed

Gao, Libo; Ren, Wencai; Xu, Huilong; Jin, Li; Wang, Zhenxing; Ma, Teng; Ma, Lai-Peng; Zhang, Zhiyong; Fu, Qiang; Peng, Lian-Mao; Bao, Xinhe; Cheng, Hui-Ming

2012-02-28

Large single-crystal graphene is highly desired and important for the applications of graphene in electronics, as grain boundaries between graphene grains markedly degrade its quality and properties. Here we report the growth of millimetre-sized hexagonal single-crystal graphene and graphene films joined from such grains on Pt by ambient-pressure chemical vapour deposition. We report a bubbling method to transfer these single graphene grains and graphene films to arbitrary substrate, which is nondestructive not only to graphene, but also to the Pt substrates. The Pt substrates can be repeatedly used for graphene growth. The graphene shows high crystal quality with the reported lowest wrinkle height of 0.8 nm and a carrier mobility of greater than 7,100 cm(2) V(-1) s(-1) under ambient conditions. The repeatable growth of graphene with large single-crystal grains on Pt and its nondestructive transfer may enable various applications.

Repeated growth and bubbling transfer of graphene with millimetre-size single-crystal grains using platinum

PubMed Central

Gao, Libo; Ren, Wencai; Xu, Huilong; Jin, Li; Wang, Zhenxing; Ma, Teng; Ma, Lai-Peng; Zhang, Zhiyong; Fu, Qiang; Peng, Lian-Mao; Bao, Xinhe; Cheng, Hui-Ming

2012-01-01

Large single-crystal graphene is highly desired and important for the applications of graphene in electronics, as grain boundaries between graphene grains markedly degrade its quality and properties. Here we report the growth of millimetre-sized hexagonal single-crystal graphene and graphene films joined from such grains on Pt by ambient-pressure chemical vapour deposition. We report a bubbling method to transfer these single graphene grains and graphene films to arbitrary substrate, which is nondestructive not only to graphene, but also to the Pt substrates. The Pt substrates can be repeatedly used for graphene growth. The graphene shows high crystal quality with the reported lowest wrinkle height of 0.8 nm and a carrier mobility of greater than 7,100 cm2 V−1 s−1 under ambient conditions. The repeatable growth of graphene with large single-crystal grains on Pt and its nondestructive transfer may enable various applications. PMID:22426220

Value-added Synthesis of Graphene: Recycling Industrial Carbon Waste into Electrodes for High-Performance Electronic Devices

NASA Astrophysics Data System (ADS)

Seo, Hong-Kyu; Kim, Tae-Sik; Park, Chibeom; Xu, Wentao; Baek, Kangkyun; Bae, Sang-Hoon; Ahn, Jong-Hyun; Kim, Kimoon; Choi, Hee Cheul; Lee, Tae-Woo

2015-11-01

We have developed a simple, scalable, transfer-free, ecologically sustainable, value-added method to convert inexpensive coal tar pitch to patterned graphene films directly on device substrates. The method, which does not require an additional transfer process, enables direct growth of graphene films on device substrates in large area. To demonstrate the practical applications of the graphene films, we used the patterned graphene grown on a dielectric substrate directly as electrodes of bottom-contact pentacene field-effect transistors (max. field effect mobility ~0.36 cm2·V-1·s-1), without using any physical transfer process. This use of a chemical waste product as a solid carbon source instead of commonly used explosive hydrocarbon gas sources for graphene synthesis has the dual benefits of converting the waste to a valuable product, and reducing pollution.

Value-added Synthesis of Graphene: Recycling Industrial Carbon Waste into Electrodes for High-Performance Electronic Devices.

PubMed

Seo, Hong-Kyu; Kim, Tae-Sik; Park, Chibeom; Xu, Wentao; Baek, Kangkyun; Bae, Sang-Hoon; Ahn, Jong-Hyun; Kim, Kimoon; Choi, Hee Cheul; Lee, Tae-Woo

2015-11-16

We have developed a simple, scalable, transfer-free, ecologically sustainable, value-added method to convert inexpensive coal tar pitch to patterned graphene films directly on device substrates. The method, which does not require an additional transfer process, enables direct growth of graphene films on device substrates in large area. To demonstrate the practical applications of the graphene films, we used the patterned graphene grown on a dielectric substrate directly as electrodes of bottom-contact pentacene field-effect transistors (max. field effect mobility ~0.36 cm(2)·V(-1)·s(-1)), without using any physical transfer process. This use of a chemical waste product as a solid carbon source instead of commonly used explosive hydrocarbon gas sources for graphene synthesis has the dual benefits of converting the waste to a valuable product, and reducing pollution.

Fabrication and room temperature operation of semiconductor nano-ring lasers using a general applicable membrane transfer method

NASA Astrophysics Data System (ADS)

Fan, Fan; Yu, Yueyang; Amiri, Seyed Ebrahim Hashemi; Quandt, David; Bimberg, Dieter; Ning, C. Z.

2017-04-01

Semiconductor nanolasers are potentially important for many applications. Their design and fabrication are still in the early stage of research and face many challenges. In this paper, we demonstrate a generally applicable membrane transfer method to release and transfer a strain-balanced InGaAs quantum-well nanomembrane of 260 nm in thickness onto various substrates with a high yield. As an initial device demonstration, nano-ring lasers of 1.5 μm in outer diameter and 500 nm in radial thickness are fabricated on MgF2 substrates. Room temperature single mode operation is achieved under optical pumping with a cavity volume of only 0.43λ03 (λ0 in vacuum). Our nano-membrane based approach represents an advantageous alternative to other design and fabrication approaches and could lead to integration of nanolasers on silicon substrates or with metallic cavity.

Malic enzyme: Tritium isotope effects with alternative dinucleotide substrates and divalent metal ions

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

Karsten, W.E.; Harris, B.G.; Cook, P.F.

1992-01-01

The NAD-malic enzyme from Ascaris suum catalyzes the divalent metal ion dependent oxidative decarboxylation of L-malate to yield pyruvate, carbon dioxide and NADH. Multiple isotope effect studies suggest a stepwise chemical mechanism with hydride transfer from L-malate to NAD occurring first to form oxalacetate, followed by decarboxylation. Utilizing L-malate-2-T, tritium V/K isotope effects have been determined for the hydride transfer step using a variety of alternative dinucleotide substrates and divalent metal ions. Combination of these data with deuterium isotope effects data and previously determined [sup 13]C isotope effects has allowed the calculation of intrinsic isotope effects for the malic enzymemore » catalyzed reaction. The identity of both the dinucleotide substrate and divalent metal ion has an effect of the size of the intrinsic isotope effect for hydride transfer.« less

Experimentally biased model structure of the Hsc70/auxilin complex: Substrate transfer and interdomain structural change

PubMed Central

Gruschus, James M.; Greene, Lois E.; Eisenberg, Evan; Ferretti, James A.

2004-01-01

A model structure of the Hsc70/auxilin complex has been constructed to gain insight into interprotein substrate transfer and ATP hydrolysis induced conformational changes in the multidomain Hsc70 structure. The Hsc70/auxilin system, which is a member of the Hsp70/Hsp40 chaperone system family, uncoats clathrin-coated vesicles in an ATP hydrolysis-driven process. Incorporating previous results from NMR and mutant binding studies, the auxilin J-domain was docked into the Hsc70 ATPase domain lower cleft using rigid backbone/flexible side chain molecular dynamics, and the Hsc70 substrate binding domain was docked by a similar procedure. For comparison, J-domain and substrate binding domain docking sites were obtained by the rigid-body docking programs DOT and ZDOCK, filtered and ranked by the program ClusPro, and relaxed using the same rigid backbone/flexible side chain dynamics. The substrate binding domain sites were assessed in terms of conserved surface complementarity and feasibility in the context of substrate transfer, both for auxilin and another Hsp40 protein, Hsc20. This assessment favors placement of the substrate binding domain near D152 on the ATPase domain surface adjacent to the J-domain invariant HPD segment, with the Hsc70 interdomain linker in the lower cleft. Examining Hsc70 interdomain energetics, we propose that long-range electrostatic interactions, perhaps due to a difference in the pKa values of bound ATP and ADP, could play a major role in the structural change induced by ATP hydrolysis. Interdomain electrostatic interactions also appear to play a role in stimulation of ATPase activity due to J-domain binding and substrate binding by Hsc70. PMID:15273304

Structural pathway of regulated substrate transfer and threading through an Hsp100 disaggregase.

PubMed

Deville, Célia; Carroni, Marta; Franke, Kamila B; Topf, Maya; Bukau, Bernd; Mogk, Axel; Saibil, Helen R

2017-08-01

Refolding aggregated proteins is essential in combating cellular proteotoxic stress. Together with Hsp70, Hsp100 chaperones, including Escherichia coli ClpB, form a powerful disaggregation machine that threads aggregated polypeptides through the central pore of tandem adenosine triphosphatase (ATPase) rings. To visualize protein disaggregation, we determined cryo-electron microscopy structures of inactive and substrate-bound ClpB in the presence of adenosine 5'- O -(3-thiotriphosphate), revealing closed AAA+ rings with a pronounced seam. In the substrate-free state, a marked gradient of resolution, likely corresponding to mobility, spans across the AAA+ rings with a dynamic hotspot at the seam. On the seam side, the coiled-coil regulatory domains are locked in a horizontal, inactive orientation. On the opposite side, the regulatory domains are accessible for Hsp70 binding, substrate targeting, and activation. In the presence of the model substrate casein, the polypeptide threads through the entire pore channel and increased nucleotide occupancy correlates with higher ATPase activity. Substrate-induced domain displacements indicate a pathway of regulated substrate transfer from Hsp70 to the ClpB pore, inside which a spiral of loops contacts the substrate. The seam pore loops undergo marked displacements, along with ordering of the regulatory domains. These asymmetric movements suggest a mechanism for ATPase activation and substrate threading during disaggregation.

Mesoporous Silica Gel-Based Mixed Matrix Membranes for Improving Mass Transfer in Forward Osmosis: Effect of Pore Size of Filler.

PubMed

Lee, Jian-Yuan; Wang, Yining; Tang, Chuyang Y; Huo, Fengwei

2015-11-23

The efficiency of forward osmosis (FO) process is generally limited by the internal concentration polarization (ICP) of solutes inside its porous substrate. In this study, mesoporous silica gel (SG) with nominal pore size ranging from 4-30 nm was used as fillers to prepare SG-based mixed matrix substrates. The resulting mixed matrix membranes had significantly reduced structural parameter and enhanced membrane water permeability as a result of the improved surface porosity of the substrates. An optimal filler pore size of ~9 nm was observed. This is in direct contrast to the case of thin film nanocomposite membranes, where microporous nanoparticle fillers are loaded to the membrane rejection layer and are designed in such a way that these fillers are able to retain solutes while allowing water to permeate through them. In the current study, the mesoporous fillers are designed as channels to both water and solute molecules. FO performance was enhanced at increasing filler pore size up to 9 nm due to the lower hydraulic resistance of the fillers. Nevertheless, further increasing filler pore size to 30 nm was accompanied with reduced FO efficiency, which can be attributed to the intrusion of polymer dope into the filler pores.

3D Imaging of Water-Drop Condensation on Hydrophobic and Hydrophilic Lubricant-Impregnated Surfaces

PubMed Central

Kajiya, Tadashi; Schellenberger, Frank; Papadopoulos, Periklis; Vollmer, Doris; Butt, Hans-Jürgen

2016-01-01

Condensation of water from the atmosphere on a solid surface is an ubiquitous phenomenon in nature and has diverse technological applications, e.g. in heat and mass transfer. We investigated the condensation kinetics of water drops on a lubricant-impregnated surface, i.e., a micropillar array impregnated with a non-volatile ionic liquid. Growing and coalescing drops were imaged in 3D using a laser scanning confocal microscope equipped with a temperature and humidity control. Different stages of condensation can be discriminated. On a lubricant-impregnated hydrophobic micropillar array these are: (1) Nucleation on the lubricant surface. (2) Regular alignment of water drops between micropillars and formation of a three-phase contact line on a bottom of the substrate. (3) Deformation and bridging by coalescence which eventually leads to a detachment of the drops from the bottom substrate. The drop-substrate contact does not result in breakdown of the slippery behaviour. Contrary, on a lubricant-impregnated hydrophilic micropillar array, the condensed water drops replace the lubricant. Consequently, the surface loses its slippery property. Our results demonstrate that a Wenzel-like to Cassie transition, required to maintain the facile removal of condensed water drops, can be induced by well-chosen surface hydrophobicity. PMID:27040483

Radiation pressure of light pulses and conservation of linear momentum in dispersive media.

PubMed

Scalora, Michael; D'Aguanno, Giuseppe; Mattiucci, Nadia; Bloemer, Mark J; Centini, Marco; Sibilia, Concita; Haus, Joseph W

2006-05-01

We derive an expression for the Minkowski momentum under conditions of dispersive susceptibility and permeability, and compare it to the Abraham momentum in order to test the principle of conservation of linear momentum when matter is present. We investigate cases when an incident pulse interacts with a variety of structures, including thick substrates, resonant, free-standing, micron-sized multilayer stacks, and negative index materials. In general, we find that for media only a few wavelengths thick the Minkowski and Abraham momentum densities yield similar results. For more extended media, including substrates and Bragg mirrors embedded inside thick dielectric substrates, our calculations show dramatic differences between the Minkowski and Abraham momenta. Without exception, in all cases investigated the instantaneous Lorentz force exerted on the medium is consistent only with the rate of change of the Abraham momentum. As a practical example, we use our model to predict that electromagnetic momentum and energy buildup inside a multilayer stack can lead to widely tunable accelerations that may easily reach and exceed 10(10) m/s(2) for a mass of 10(-5) g. Our results suggest that the physics of the photonic band edge and other similar finite structures may be used as a testing ground for basic electromagnetic phenomena such as momentum transfer to macroscopic media.

Mesoporous Silica Gel–Based Mixed Matrix Membranes for Improving Mass Transfer in Forward Osmosis: Effect of Pore Size of Filler

PubMed Central

Lee, Jian-Yuan; Wang, Yining; Tang, Chuyang Y.; Huo, Fengwei

2015-01-01

The efficiency of forward osmosis (FO) process is generally limited by the internal concentration polarization (ICP) of solutes inside its porous substrate. In this study, mesoporous silica gel (SG) with nominal pore size ranging from 4–30 nm was used as fillers to prepare SG-based mixed matrix substrates. The resulting mixed matrix membranes had significantly reduced structural parameter and enhanced membrane water permeability as a result of the improved surface porosity of the substrates. An optimal filler pore size of ~9 nm was observed. This is in direct contrast to the case of thin film nanocomposite membranes, where microporous nanoparticle fillers are loaded to the membrane rejection layer and are designed in such a way that these fillers are able to retain solutes while allowing water to permeate through them. In the current study, the mesoporous fillers are designed as channels to both water and solute molecules. FO performance was enhanced at increasing filler pore size up to 9 nm due to the lower hydraulic resistance of the fillers. Nevertheless, further increasing filler pore size to 30 nm was accompanied with reduced FO efficiency, which can be attributed to the intrusion of polymer dope into the filler pores. PMID:26592565

Optimization of Enzyme-Substrate Pairing for Bioluminescence Imaging of Gene Transfer Using Renilla and Gaussia Luciferases

PubMed Central

Kimura, Takahiro; Hiraoka, Kei; Kasahara, Noriyuki; Logg, Christopher R.

2010-01-01

Background Bioluminescence imaging (BLI) permits the noninvasive quantitation and localization of transduction and expression by gene transfer vectors. The tendency of tissue to attenuate light in the optical region, however, limits the sensitivity of BLI. Improvements in light output from bioluminescent reporter systems would allow the detection of lower levels of expression, smaller numbers of cells and expression from deeper and more attenuating tissues within an animal. Methods With the goal of identifying substrates that allow improved sensitivity with Renilla luciferase (RLuc) and Gaussia luciferase (GLuc) reporter genes, we evaluated native coelenterazine and three of its most promising derivatives in BLI of cultured cells transduced with retroviral vectors encoding these reporters. Of the eight enzyme-substrate pairs tested, the two that performed best were further evaluated in mice to compare their effectiveness for imaging vector-modified cells in live animals. Results In cell culture, we observed striking differences in luminescence levels from the various enzyme-substrate combinations and found that the two luciferases exhibited markedly distinct abilities to generate light with the substrates. The most effective pairs were RLuc with the synthetic coelenterazine derivative ViviRen, and GLuc with native coelenterazine. In animals, these two pairs allowed similar detection sensitivities, which were 8–15 times higher than that of the prototypical RLuc-native coelenterazine combination. Conclusions Our results demonstrate that substrate selection can dramatically influence the detection sensitivity of RLuc and GLuc and that appropriate selection of substrate can greatly improve the performance of reporter genes encoding these enzymes for monitoring gene transfer by BLI. PMID:20527045

Optimization of enzyme-substrate pairing for bioluminescence imaging of gene transfer using Renilla and Gaussia luciferases.

PubMed

Kimura, Takahiro; Hiraoka, Kei; Kasahara, Noriyuki; Logg, Christopher R

2010-06-01

Bioluminescence imaging (BLI) permits the non-invasive quantification and localization of transduction and expression by gene transfer vectors. The tendency of tissue to attenuate light in the optical region, however, limits the sensitivity of BLI. Improvements in light output from bioluminescent reporter systems would allow the detection of lower levels of expression, smaller numbers of cells and expression from deeper and more attenuating tissues within an animal. With the goal of identifying substrates that allow improved sensitivity with Renilla luciferase (RLuc) and Gaussia luciferase (GLuc) reporter genes, we evaluated native coelenterazine and three of its most promising derivatives in BLI of cultured cells transduced with retroviral vectors encoding these reporters. Of the eight enzyme-substrate pairs tested, the two that performed best were further evaluated in mice to compare their effectiveness for imaging vector-modified cells in live animals. In cell culture, we observed striking differences in luminescence levels from the various enzyme-substrate combinations and found that the two luciferases exhibited markedly distinct abilities to generate light with the substrates. The most effective pairs were RLuc with the synthetic coelenterazine derivative ViviRen, and GLuc with native coelenterazine. In animals, these two pairs allowed similar detection sensitivities, which were eight- to 15-fold higher than that of the prototypical RLuc-native coelenterazine combination. Substrate selection can dramatically influence the detection sensitivity of RLuc and GLuc and appropriate choice of substrate can greatly improve the performance of reporter genes encoding these enzymes for monitoring gene transfer by BLI.

Parallel-plate submicron gap formed by micromachined low-density pillars for near-field radiative heat transfer

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

Ito, Kota, E-mail: kotaito@mosk.tytlabs.co.jp; Research Center for Advanced Science and Technology; Miura, Atsushi

Near-field radiative heat transfer has been a subject of great interest due to the applicability to thermal management and energy conversion. In this letter, a submicron gap between a pair of diced fused quartz substrates is formed by using micromachined low-density pillars to obtain both the parallelism and small parasitic heat conduction. The gap uniformity is validated by the optical interferometry at four corners of the substrates. The heat flux across the gap is measured in a steady-state and is no greater than twice of theoretically predicted radiative heat flux, which indicates that the parasitic heat conduction is suppressed tomore » the level of the radiative heat transfer or less. The heat conduction through the pillars is modeled, and it is found to be limited by the thermal contact resistance between the pillar top and the opposing substrate surface. The methodology to form and evaluate the gap promotes the near-field radiative heat transfer to various applications such as thermal rectification, thermal modulation, and thermophotovoltaics.« less

Direct dry transfer of CVD graphene to an optical substrate by in situ photo-polymerization

NASA Astrophysics Data System (ADS)

Kessler, Felipe; Muñoz, Pablo A. R.; Phelan, Ciaran; Romani, Eric C.; Larrudé, Dunieskys R. G.; Freire, Fernando L.; Thoroh de Souza, Eunézio A.; de Matos, Christiano J. S.; Fechine, Guilhermino J. M.

2018-05-01

Here, we report on a method that allows graphene produced by chemical vapor deposition (CVD) to be directly transferred to an optically transparent photo resin, by in situ photo-polymerization of the latter, with high efficiency and low contamination. Two photocurable resins, A and B, with different viscosities but essentially the same chemical structure, were used. Raman spectroscopy and surface energy results show that large continuous areas of graphene were transferred with minimal defects to the lower viscosity resin (B), due to the better contact between the resin and graphene. As a proof-of-principle optical experiment, graphene on the polymeric substrate was subjected to high-intensity femtosecond infrared pulses and third-harmonic generation was observed with no noticeable degradation of the sample. A sheet third-order susceptibility χ (3) = 0.71 ×10-28m3V-2 was obtained, matching that of graphene on a glass substrate. These results indicate the suitability of the proposed transfer method, and of the photo resin, for the production of nonlinear photonic components and devices.

Investigation of mass transfer intensification under power ultrasound irradiation using 3D computational simulation: A comparative analysis.

PubMed

Sajjadi, Baharak; Asgharzadehahmadi, Seyedali; Asaithambi, Perumal; Raman, Abdul Aziz Abdul; Parthasarathy, Rajarathinam

2017-01-01

This paper aims at investigating the influence of acoustic streaming induced by low-frequency (24kHz) ultrasound irradiation on mass transfer in a two-phase system. The main objective is to discuss the possible mass transfer improvements under ultrasound irradiation. Three analyses were conducted: i) experimental analysis of mass transfer under ultrasound irradiation; ii) comparative analysis between the results of the ultrasound assisted mass transfer with that obtained from mechanically stirring; and iii) computational analysis of the systems using 3D CFD simulation. In the experimental part, the interactive effects of liquid rheological properties, ultrasound power and superficial gas velocity on mass transfer were investigated in two different sonicators. The results were then compared with that of mechanical stirring. In the computational part, the results were illustrated as a function of acoustic streaming behaviour, fluid flow pattern, gas/liquid volume fraction and turbulence in the two-phase system and finally the mass transfer coefficient was specified. It was found that additional turbulence created by ultrasound played the most important role on intensifying the mass transfer phenomena compared to that in stirred vessel. Furthermore, long residence time which depends on geometrical parameters is another key for mass transfer. The results obtained in the present study would help researchers understand the role of ultrasound as an energy source and acoustic streaming as one of the most important of ultrasound waves on intensifying gas-liquid mass transfer in a two-phase system and can be a breakthrough in the design procedure as no similar studies were found in the existing literature. Copyright © 2016. Published by Elsevier B.V.

Suitability of the first-order mass transfer concept for describing cyclic diffusive mass transfer in stagnant zones

NASA Astrophysics Data System (ADS)

Griffioen, Jasper

1998-10-01

The concept of first-order mass transfer between mobile and immobile regions, which mathematically simplifies the concept of Fickian diffusion in stagnant areas, has often been used to describe physical nonequilibrium transport of solutes into natural porous media. This study compares the two concepts, using analytical expressions describing cyclic mass transfer into and out of stagnant layers. The results show that the first-order mass transfer concept cannot describe continuous diffusion into the immobile zone during period of net outward diffusion if the immobile zone has not filled completely during the period of net inward diffusion. This sets phenomenological limitations to the first-order mass transfer concept when short periods of relative time are involved; these limitations have to be compared with the practical limitations to the Fickian diffusion concept.

Spatially Controlled Noncovalent Functionalization of 2D Materials Based on Molecular Architecture.

PubMed

Bang, Jae Jin; Porter, Ashlin G; Davis, Tyson C; Hayes, Tyler R; Claridge, Shelley A

2018-05-15

Polymerizable amphiphiles can be assembled into lying-down phases on 2D materials such as graphite and graphene to create chemically orthogonal surface patterns at 5-10 nm scales, locally modulating functionality of the 2D basal plane. Functionalization can be carried out through Langmuir-Schaefer conversion, in which a subset of molecules is transferred out of a standing phase film on water onto the 2D substrate. Here, we leverage differences in molecular structure to spatially control transfer at both nanoscopic and microscopic scales. We compare transfer properties of five different single- and dual-chain amphiphiles, demonstrating that those with strong lateral interactions (e.g., hydrogen-bonding networks) exhibit the lowest transfer efficiencies. Since molecular structures also influence microscopic domain morphologies in Langmuir films, we show that it is possible to transfer such microscale patterns, taking advantage of variations in the local transfer rates based on the structural heterogeneity in Langmuir films. Nanoscale domain morphologies also vary in ways that are consistent with predicted relative transfer and diffusion rates. These results suggest strategies to tailor noncovalent functionalization of 2D substrates through controlled LS transfer.

Hydrophobic networked PbO2 electrode for electrochemical oxidation of paracetamol drug and degradation mechanism kinetics.

PubMed

He, Yapeng; Wang, Xue; Huang, Weimin; Chen, Rongling; Zhang, Wenli; Li, Hongdong; Lin, Haibo

2018-02-01

A hydrophobic networked PbO 2 electrode was deposited on mesh titanium substrate and utilized for the electrochemical elimination towards paracetamol drug. Three dimensional growth mechanism of PbO 2 layer provided more loading capacity of active materials and network structure greatly reduced the mass transfer for the electrochemical degradation. The active electrochemical surface area based on voltammetric charge quantity of networked PbO 2 electrode is about 2.1 times for traditional PbO 2 electrode while lower charge transfer resistance (6.78 Ω cm 2 ) could be achieved on networked PbO 2 electrode. The electrochemical incineration kinetics of paracetamol drug followed a pseudo first-order behavior and the corresponding rate constant were 0.354, 0.658 and 0.880 h -1 for traditional, networked PbO 2 and boron doped diamond electrode. Higher electrochemical elimination kinetics could be achieved on networked PbO 2 electrode and the performance can be equal to boron doped diamond electrode in result. Based on the quantification of reactive oxidants (hydroxyl radicals), the utilization rate of hydroxyl radicals could reach as high as 90% on networked PbO 2 electrode. The enhancement of excellent electrochemical oxidation capacity towards paracetamol drug was related to the properties of higher loading capacity, enhanced mass transfer and hydrophobic surface. The possible degradation mechanism and pathway of paracetamol on networked PbO 2 electrode were proposed in details accordingly based on the intermediate products. Copyright © 2017 Elsevier Ltd. All rights reserved.

A bipartite signal mediates the transfer of type IV secretion substrates of Bartonella henselae into human cells.

PubMed

Schulein, Ralf; Guye, Patrick; Rhomberg, Thomas A; Schmid, Michael C; Schröder, Gunnar; Vergunst, Annette C; Carena, Ilaria; Dehio, Christoph

2005-01-18

Bacterial type IV secretion (T4S) systems mediate the transfer of macromolecular substrates into various target cells, e.g., the conjugative transfer of DNA into bacteria or the transfer of virulence proteins into eukaryotic host cells. The T4S apparatus VirB of the vascular tumor-inducing pathogen Bartonella henselae causes subversion of human endothelial cell (HEC) function. Here we report the identification of multiple protein substrates of VirB, which, upon translocation into HEC, mediate all known VirB-dependent cellular changes. These Bartonella-translocated effector proteins (Beps) A-G are encoded together with the VirB system and the T4S coupling protein VirD4 on a Bartonella-specific pathogenicity island. The Beps display a modular architecture, suggesting an evolution by extensive domain duplication and reshuffling. The C terminus of each Bep harbors at least one copy of the Bep-intracellular delivery domain and a short positively charged tail sequence. This biparte C terminus constitutes a transfer signal that is sufficient to mediate VirB/VirD4-dependent intracellular delivery of reporter protein fusions. The Bep-intracellular delivery domain is also present in conjugative relaxases of bacterial conjugation systems. We exemplarily show that the C terminus of such a conjugative relaxase mediates protein transfer through the Bartonella henselae VirB/VirD4 system into HEC. Conjugative relaxases may thus represent the evolutionary origin of the here defined T4S signal for protein transfer into human cells.

Biodegradation of 2,4,6-trichlorophenol in a packed-bed biofilm reactor equipped with an internal net draft tube riser for aeration and liquid circulation.

PubMed

Jesús, A Gómez-De; Romano-Baez, F J; Leyva-Amezcua, L; Juárez-Ramírez, C; Ruiz-Ordaz, N; Galíndez-Mayer, J

2009-01-30

For the aerobic biodegradation of the fungicide and defoliant 2,4,6-trichlorophenol (2,4,6-TCP), a bench-scale packed-bed bioreactor equipped with a net draft tube riser for liquid circulation and oxygenation (PB-ALR) was constructed. To obtain a high packed-bed volume relative to the whole bioreactor volume, a high A(D)/A(R) ratio was used. Reactor's downcomer was packed with a porous support of volcanic stone fragments. PB-ALR hydrodynamics and oxygen mass transfer behavior was evaluated and compared to the observed behavior of the unpacked reactor operating as an internal airlift reactor (ALR). Overall gas holdup values epsilon(G), and zonal oxygen mass transfer coefficients determined at various airflow rates in the PB-ALR, were higher than those obtained with the ALR. When comparing mixing time values obtained in both cases, a slight increment in mixing time was observed when reactor was operated as a PB-ALR. By using a mixed microbial community, the biofilm reactor was used to evaluate the aerobic biodegradation of 2,4,6-TCP. Three bacterial strains identified as Burkholderia sp., Burkholderia kururiensis and Stenotrophomonas sp. constituted the microbial consortium able to cometabolically degrade the 2,4,6-TCP, using phenol as primary substrate. This consortium removed 100% of phenol and near 99% of 2,4,6-TCP. Mineralization and dehalogenation of 2,4,6-TCP was evidenced by high COD removal efficiencies ( approximately 95%), and by the stoichiometric release of chloride ions from the halogenated compound ( approximately 80%). Finally, it was observed that the microbial consortium was also capable to metabolize 2,4,6-TCP without phenol as primary substrate, with high removal efficiencies (near 100% for 2,4,6-TCP, 92% for COD and 88% for chloride ions).

Support effects on adsorption and catalytic activation of O2 in single atom iron catalysts with graphene-based substrates.

PubMed

Gao, Zheng-Yang; Yang, Wei-Jie; Ding, Xun-Lei; Lv, Gang; Yan, Wei-Ping

2018-03-07

The adsorption and catalytic activation of O 2 on single atom iron catalysts with graphene-based substrates were investigated systematically by density functional theory calculation. It is found that the support effects of graphene-based substrates have a significant influence on the stability of the single atom catalysts, the adsorption configuration, the electron transfer mechanism, the adsorption energy and the energy barrier. The differences in the stable adsorption configuration of O 2 on single atom iron catalysts with different graphene-based substrates can be well understood by the symmetrical matching principle based on frontier molecular orbital analysis. There are two different mechanisms of electron transfer, in which the Fe atom acts as the electron donor in single vacancy graphene-based substrates while the Fe atom mainly acts as the bridge for electron transfer in double vacancy graphene-based substrates. The Fermi softness and work function are good descriptors of the adsorption energy and they can well reveal the relationship between electronic structure and adsorption energy. This single atom iron catalyst with single vacancy graphene modified by three nitrogen atoms is a promising non-noble metal single atom catalyst in the adsorption and catalytic oxidation of O 2 . Furthermore, the findings can lay the foundation for the further study of graphene-based support effects and provide a guideline for the development and design of new non-noble-metal single atom catalysts.

Redox-coupled proton transfer mechanism in nitrite reductase revealed by femtosecond crystallography.

PubMed

Fukuda, Yohta; Tse, Ka Man; Nakane, Takanori; Nakatsu, Toru; Suzuki, Mamoru; Sugahara, Michihiro; Inoue, Shigeyuki; Masuda, Tetsuya; Yumoto, Fumiaki; Matsugaki, Naohiro; Nango, Eriko; Tono, Kensuke; Joti, Yasumasa; Kameshima, Takashi; Song, Changyong; Hatsui, Takaki; Yabashi, Makina; Nureki, Osamu; Murphy, Michael E P; Inoue, Tsuyoshi; Iwata, So; Mizohata, Eiichi

2016-03-15

Proton-coupled electron transfer (PCET), a ubiquitous phenomenon in biological systems, plays an essential role in copper nitrite reductase (CuNiR), the key metalloenzyme in microbial denitrification of the global nitrogen cycle. Analyses of the nitrite reduction mechanism in CuNiR with conventional synchrotron radiation crystallography (SRX) have been faced with difficulties, because X-ray photoreduction changes the native structures of metal centers and the enzyme-substrate complex. Using serial femtosecond crystallography (SFX), we determined the intact structures of CuNiR in the resting state and the nitrite complex (NC) state at 2.03- and 1.60-Å resolution, respectively. Furthermore, the SRX NC structure representing a transient state in the catalytic cycle was determined at 1.30-Å resolution. Comparison between SRX and SFX structures revealed that photoreduction changes the coordination manner of the substrate and that catalytically important His255 can switch hydrogen bond partners between the backbone carbonyl oxygen of nearby Glu279 and the side-chain hydroxyl group of Thr280. These findings, which SRX has failed to uncover, propose a redox-coupled proton switch for PCET. This concept can explain how proton transfer to the substrate is involved in intramolecular electron transfer and why substrate binding accelerates PCET. Our study demonstrates the potential of SFX as a powerful tool to study redox processes in metalloenzymes.

Hot Films on Ceramic Substrates for Measuring Skin Friction

NASA Technical Reports Server (NTRS)

Noffz, Greg; Leiser, Daniel; Bartlett, Jim; Lavine, Adrienne

2003-01-01

Hot-film sensors, consisting of a metallic film on an electrically nonconductive substrate, have been used to measure skin friction as far back as 1931. A hot film is maintained at an elevated temperature relative to the local flow by passing an electrical current through it. The power required to maintain the specified temperature depends on the rate at which heat is transferred to the flow. The heat transfer rate correlates to the velocity gradient at the surface, and hence, with skin friction. The hot-film skin friction measurement method is most thoroughly developed for steady-state conditions, but additional issues arise under transient conditions. Fabricating hot-film substrates using low-thermal-conductivity ceramics can offer advantages over traditional quartz or polyester-film substrates. First, a low conductivity substrate increases the fraction of heat convected away by the fluid, thus increasing sensitivity to changes in flow conditions. Furthermore, the two-part, composite nature of the substrate allows the installation of thermocouple junctions just below the hot film, which can provide an estimate of the conduction heat loss.

Probing the effect of charge transfer enhancement in off resonance mode SERS via conjugation of the probe dye between silver nanoparticles and metal substrates.

PubMed

Selvakannan, Pr; Ramanathan, Rajesh; Plowman, Blake J; Sabri, Ylias M; Daima, Hemant K; O'Mullane, Anthony P; Bansal, Vipul; Bhargava, Suresh K

2013-08-21

The charge transfer-mediated surface enhanced Raman scattering (SERS) of crystal violet (CV) molecules that were chemically conjugated between partially polarized silver nanoparticles and optically smooth gold and silver substrates has been studied under off-resonant conditions. Tyrosine molecules were used as a reducing agent to convert silver ions into silver nanoparticles where oxidised tyrosine caps the silver nanoparticle surface with its semiquinone group. This binding through the quinone group facilitates charge transfer and results in partially oxidised silver. This establishes a chemical link between the silver nanoparticles and the CV molecules, where the positively charged central carbon of CV molecules can bind to the terminal carboxylate anion of the oxidised tyrosine molecules. After drop casting Ag nanoparticles bound with CV molecules it was found that the free terminal amine groups tend to bind with the underlying substrates. Significantly, only those CV molecules that were chemically conjugated between the partially polarised silver nanoparticles and the underlying gold or silver substrates were found to show SERS under off-resonant conditions. The importance of partial charge transfer at the nanoparticle/capping agent interface and the resultant conjugation of CV molecules to off resonant SERS effects was confirmed by using gold nanoparticles prepared in a similar manner. In this case the capping agent binds to the nanoparticle through the amine group which does not facilitate charge transfer from the gold nanoparticle and under these conditions SERS enhancement in the sandwich configuration was not observed.

High Fidelity Tape Transfer Printing Based On Chemically Induced Adhesive Strength Modulation

NASA Astrophysics Data System (ADS)

Sim, Kyoseung; Chen, Song; Li, Yuhang; Kammoun, Mejdi; Peng, Yun; Xu, Minwei; Gao, Yang; Song, Jizhou; Zhang, Yingchun; Ardebili, Haleh; Yu, Cunjiang

2015-11-01

Transfer printing, a two-step process (i.e. picking up and printing) for heterogeneous integration, has been widely exploited for the fabrication of functional electronics system. To ensure a reliable process, strong adhesion for picking up and weak or no adhesion for printing are required. However, it is challenging to meet the requirements of switchable stamp adhesion. Here we introduce a simple, high fidelity process, namely tape transfer printing(TTP), enabled by chemically induced dramatic modulation in tape adhesive strength. We describe the working mechanism of the adhesion modulation that governs this process and demonstrate the method by high fidelity tape transfer printing several types of materials and devices, including Si pellets arrays, photodetector arrays, and electromyography (EMG) sensors, from their preparation substrates to various alien substrates. High fidelity tape transfer printing of components onto curvilinear surfaces is also illustrated.

Sulfate-reducing bacteria: Microbiology and physiology

NASA Technical Reports Server (NTRS)

Peck, H. D.

1985-01-01

The sulfate reducing bacteria, the first nonphotosynthetic anaerobic bacteria demonstrated to contain c type cytochromes, perform electron transfer coupled to phosphorylation. A new bioenergetic scheme for the formation of a proton gradient for growth of Desulfovibrio on organic substrates and sulfate involving vectors electron transfer and consistent with the cellular localization of enzymes and electron transfer components was proposed. Hydrogen is produced in the cytoplasm from organic substrates and, as a permease molecule diffuses rapidly across the cytoplasmic membrane, it is oxidized to protons and electrons by the periplasmic hydrogenase. The electrons only are transferred across the cytoplasmic membrane to the cytoplasm where they are used to reduce sulfate to sulfide. The protons are used for transport or to drive a reversible ATPOSE. The net effect is the transfer of protons across the cytoplasmic membrane with the intervention of a proton pump. This type of H2 cycling is relevant to the bioenergetics of other types of anaerobic microorganisms.

Ultra thin metallic coatings to control near field radiative heat transfer

NASA Astrophysics Data System (ADS)

Esquivel-Sirvent, R.

2016-09-01

We present a theoretical calculation of the changes in the near field radiative heat transfer between two surfaces due to the presence of ultra thin metallic coatings on semiconductors. Depending on the substrates, the radiative heat transfer is modulated by the thickness of the ultra thin film. In particular we consider gold thin films with thicknesses varying from 4 to 20 nm. The ultra-thin film has an insulator-conductor transition close to a critical thickness of dc = 6.4 nm and there is an increase in the near field spectral heat transfer just before the percolation transition. Depending on the substrates (Si or SiC) and the thickness of the metallic coatings we show how the near field heat transfer can be increased or decreased as a function of the metallic coating thickness. The calculations are based on available experimental data for the optical properties of ultrathin coatings.

Mass and heat transfer in crushed oil shale

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

Carley, J.F.; Straub, J.S.; Ott, L.L.

1984-04-01

Heat and mass transfer between gases and oil-shale particles are both important for all proposed retorting processes. Past studies of transfer in packed beds, which have disagreed substantially in their results, have nearly all been done with beds of regular particles of uniform size, whereas oil-shale retorting involves particles of diverse shapes and widely ranging sizes. To resolve these questions, we have made 349 runs in which we measured mass-transfer rates from naphthalene particles of diverse shapes buried in packed beds through which air was passed at room temperature. This technique permits calculation of the mass-transfer coefficient for each activemore » particle in the bed rather than, as in most past studies, for the bed as a whole. The data were analyzed in two ways: (1) by the traditional correlation of Colburn j/sub D/ vs Reynolds number and (2) by multiple regression of the mass-transfer coefficient on air rate, traditional correlation of Colburn j/sub D/ vs Reynolds number and (3) by multiple regression of the mass-transfer coefficient on air rate, sizes of active and inert particles, void fraction, and temperature. Principal findings are: (1) local Reynolds number should be based on active particle size rather than average size for the bed; (2) no appreciable differences were seen between shallow beds and deep ones; (3) mass transfer was 26% faster for spheres and lozenges buried in shale than for all-sphere beds; (4) orientation of lozenges in shale beds has little effect on mass-transfer rate; (5) a useful summarizing equation for either mass or heat transfer in shale beds is log j.epsilon = -.0747 - .6344 log Re + .0592 log/sup 2/Re where j = either j/sub D/ or j/sub H/, the Chilton-Colburn j-factors for mass and heat transfer, Re = the Reynolds number defined for packed beds, and epsilon = the void fraction in the bed. 12 references, 15 figures.« less

SOI MESFETs on high-resistivity, trap-rich substrates

NASA Astrophysics Data System (ADS)

Mehr, Payam; Zhang, Xiong; Lepkowski, William; Li, Chaojiang; Thornton, Trevor J.

2018-04-01

The DC and RF characteristics of metal-semiconductor field-effect-transistors (MESFETs) on conventional CMOS silicon-on-insulator (SOI) substrates are compared to nominally identical devices on high-resistivity, trap-rich SOI substrates. While the DC transfer characteristics are statistically identical on either substrate, the maximum available gain at GHz frequencies is enhanced by ∼2 dB when using the trap-rich substrates, with maximum operating frequencies, fmax, that are approximately 5-10% higher. The increased fmax is explained by the reduced substrate conduction at GHz frequencies using a lumped-element, small-signal model.

Electric propulsion for geostationary orbit insertion

NASA Technical Reports Server (NTRS)

Oleson, Steven R.; Curran, Francis M.; Myers, Roger M.

1995-01-01

Solar electric propulsion (SEP) technology is already being used for geostationary satellite stationkeeping to increase payload mass. By using this same technology to perform part of the orbit transfer additional increases in payload mass can be achieved. Advanced chemical and N2H4 arcjet systems are used to increase the payload mass by performing stationkeeping and part of the orbit transfer. Four mission options are analyzed which show the impact of either sharing the orbit transfer between chemical and SEP systems or having either complete the transfer alone. Results show that for an Atlas 2AS payload increases in net mass (geostationary satellite mass less wet propulsion system mass) of up to 100 kg can be achieved using advanced chemical for the transfer and advanced N2H4 arcjets for stationkeeping. An additional 100 kg can be added using advanced N2H4 arcjets for part of a 40 day orbit transfer.

Determination of long-range scalar (1)H-(1)H coupling constants responsible for polarization transfer in SABRE.

PubMed

Eshuis, Nan; Aspers, Ruud L E G; van Weerdenburg, Bram J A; Feiters, Martin C; Rutjes, Floris P J T; Wijmenga, Sybren S; Tessari, Marco

2016-04-01

SABRE (Signal Amplification By Reversible Exchange) nuclear spin hyperpolarization method can provide strongly enhanced NMR signals as a result of the reversible association of small molecules with para-hydrogen (p-H2) at an iridium metal complex. The conversion of p-H2 singlet order to enhanced substrate proton magnetization within such complex is driven by the scalar coupling interactions between the p-H2 derived hydrides and substrate nuclear spins. In the present study these long-range homonuclear couplings are experimentally determined for several SABRE substrates using an NMR pulse sequence for coherent hyperpolarization transfer at high magnetic field. Pyridine and pyrazine derivatives appear to have a similar ∼1.2 Hz (4)J coupling to p-H2 derived hydrides for their ortho protons, and a much lower (5)J coupling for their meta protons. Interestingly, the (4)J hydride-substrate coupling for five-membered N-heterocyclic substrates is well below 1 Hz. Copyright © 2016 Elsevier Inc. All rights reserved.

Determination of long-range scalar 1H-1H coupling constants responsible for polarization transfer in SABRE

NASA Astrophysics Data System (ADS)

Eshuis, Nan; Aspers, Ruud L. E. G.; van Weerdenburg, Bram J. A.; Feiters, Martin C.; Rutjes, Floris P. J. T.; Wijmenga, Sybren S.; Tessari, Marco

2016-04-01

SABRE (Signal Amplification By Reversible Exchange) nuclear spin hyperpolarization method can provide strongly enhanced NMR signals as a result of the reversible association of small molecules with para-hydrogen (p-H2) at an iridium metal complex. The conversion of p-H2 singlet order to enhanced substrate proton magnetization within such complex is driven by the scalar coupling interactions between the p-H2 derived hydrides and substrate nuclear spins. In the present study these long-range homonuclear couplings are experimentally determined for several SABRE substrates using an NMR pulse sequence for coherent hyperpolarization transfer at high magnetic field. Pyridine and pyrazine derivatives appear to have a similar ∼1.2 Hz 4J coupling to p-H2 derived hydrides for their ortho protons, and a much lower 5J coupling for their meta protons. Interestingly, the 4J hydride-substrate coupling for five-membered N-heterocyclic substrates is well below 1 Hz.

Understanding and controlling the substrate effect on graphene electron-transfer chemistry via reactivity imprint lithography

NASA Astrophysics Data System (ADS)

Wang, Qing Hua; Jin, Zhong; Kim, Ki Kang; Hilmer, Andrew J.; Paulus, Geraldine L. C.; Shih, Chih-Jen; Ham, Moon-Ho; Sanchez-Yamagishi, Javier D.; Watanabe, Kenji; Taniguchi, Takashi; Kong, Jing; Jarillo-Herrero, Pablo; Strano, Michael S.

2012-09-01

Graphene has exceptional electronic, optical, mechanical and thermal properties, which provide it with great potential for use in electronic, optoelectronic and sensing applications. The chemical functionalization of graphene has been investigated with a view to controlling its electronic properties and interactions with other materials. Covalent modification of graphene by organic diazonium salts has been used to achieve these goals, but because graphene comprises only a single atomic layer, it is strongly influenced by the underlying substrate. Here, we show a stark difference in the rate of electron-transfer reactions with organic diazonium salts for monolayer graphene supported on a variety of substrates. Reactions proceed rapidly for graphene supported on SiO2 and Al2O3 (sapphire), but negligibly on alkyl-terminated and hexagonal boron nitride (hBN) surfaces, as shown by Raman spectroscopy. We also develop a model of reactivity based on substrate-induced electron-hole puddles in graphene, and achieve spatial patterning of chemical reactions in graphene by patterning the substrate.

Direct transfer of metallic photonic structures onto end facets of optical fibers

NASA Astrophysics Data System (ADS)

Zhang, Xinping; Liu, Feifei; Lin, Yuanhai

2016-07-01

We present a flexible approach to transfer metallic photonic crystals (MPCs) onto end facets of optical fibers. The MPCs were initially fabricated on a glass substrate with a spacer layer of indium tin oxide (ITO), which was used as a buffer layer in the transferring process. The fiber ends were firstly welded on the top surface of the MPCs by a drop of polymer solution after the solvent evaporated. The ITO layer was then etched by hydrochloric acid (HCl), so that the MPCs got off the substrate and were transferred to the fiber ends. Alternatively, the MPCs may be also etched off the substrate first by immersing the sample in HCl. The ultra-thin MPC sheet consisting of gold nanolines interlaced with photoresist gratings was then transferred to cap the fiber ends. In the later approach, we can choose which side of the MPCs to be used as the contact with the fiber facet. Such methods enabled convenient nanostructuring on optical fiber tips and achieving miniaturized MPC devices with compact integration, extending significantly applications of MPCs. In particular, the fabrications presented in this manuscript enrich the lab-on-fiber engineering techniques and the resultant devices have potential applications in remote sensing and detection systems.

Broadly tunable terahertz difference-frequency generation in quantum cascade lasers on silicon

NASA Astrophysics Data System (ADS)

Jung, Seungyong; Kim, Jae Hyun; Jiang, Yifan; Vijayraghavan, Karun; Belkin, Mikhail A.

2018-01-01

We report broadly tunable terahertz (THz) sources based on intracavity Cherenkov difference-frequency generation in quantum cascade lasers transfer-printed on high-resistivity silicon substrates. Spectral tuning from 1.3 to 4.3 THz was obtained from a 2-mm long laser chip using a modified Littrow external cavity setup. The THz power output and the midinfrared-to-THz conversion efficiency of the devices transferred on silicon are dramatically enhanced, compared with the devices on a native semi-insulating InP substrate. Enhancement is particularly significant at higher THz frequencies, where the tail of the Reststrahlen band results in a strong absorption of THz light in the InP substrate.

Printable semiconductor structures and related methods of making and assembling

DOEpatents

Nuzzo, Ralph G.; Rogers, John A.; Menard, Etienne; Lee, Keon Jae; Khang; , Dahl-Young; Sun, Yugang; Meitl, Matthew; Zhu, Zhengtao; Ko, Heung Cho; Mack, Shawn

2013-03-12

The present invention provides a high yield pathway for the fabrication, transfer and assembly of high quality printable semiconductor elements having selected physical dimensions, shapes, compositions and spatial orientations. The compositions and methods of the present invention provide high precision registered transfer and integration of arrays of microsized and/or nanosized semiconductor structures onto substrates, including large area substrates and/or flexible substrates. In addition, the present invention provides methods of making printable semiconductor elements from low cost bulk materials, such as bulk silicon wafers, and smart-materials processing strategies that enable a versatile and commercially attractive printing-based fabrication platform for making a broad range of functional semiconductor devices.

Printable semiconductor structures and related methods of making and assembling

DOEpatents

Nuzzo, Ralph G [Champaign, IL; Rogers, John A [Champaign, IL; Menard, Etienne [Durham, NC; Lee, Keon Jae [Tokyo, JP; Khang, Dahl-Young [Urbana, IL; Sun, Yugang [Westmont, IL; Meitl, Matthew [Raleigh, NC; Zhu, Zhengtao [Rapid City, SD; Ko, Heung Cho [Urbana, IL; Mack, Shawn [Goleta, CA

2011-10-18

The present invention provides a high yield pathway for the fabrication, transfer and assembly of high quality printable semiconductor elements having selected physical dimensions, shapes, compositions and spatial orientations. The compositions and methods of the present invention provide high precision registered transfer and integration of arrays of microsized and/or nanosized semiconductor structures onto substrates, including large area substrates and/or flexible substrates. In addition, the present invention provides methods of making printable semiconductor elements from low cost bulk materials, such as bulk silicon wafers, and smart-materials processing strategies that enable a versatile and commercially attractive printing-based fabrication platform for making a broad range of functional semiconductor devices.

Printable semiconductor structures and related methods of making and assembling

DOEpatents

Nuzzo, Ralph G.; Rogers, John A.; Menard, Etienne; Lee, Keon Jae; Khang, Dahl-Young; Sun, Yugang; Meitl, Matthew; Zhu, Zhengtao; Ko, Heung Cho; Mack, Shawn

2010-09-21

The present invention provides a high yield pathway for the fabrication, transfer and assembly of high quality printable semiconductor elements having selected physical dimensions, shapes, compositions and spatial orientations. The compositions and methods of the present invention provide high precision registered transfer and integration of arrays of microsized and/or nanosized semiconductor structures onto substrates, including large area substrates and/or flexible substrates. In addition, the present invention provides methods of making printable semiconductor elements from low cost bulk materials, such as bulk silicon wafers, and smart-materials processing strategies that enable a versatile and commercially attractive printing-based fabrication platform for making a broad range of functional semiconductor devices.

Nano transfer and nanoreplication using deterministically grown sacrificial nanotemplates

DOEpatents

Melechko, Anatoli V [Oak Ridge, TN; McKnight, Timothy E [Greenback, TN; Guillorn, Michael A [Ithaca, NY; Ilic, Bojan [Ithaca, NY; Merkulov, Vladimir I [Knoxville, TX; Doktycz, Mitchel J [Knoxville, TN; Lowndes, Douglas H [Knoxville, TN; Simpson, Michael L [Knoxville, TN

2012-03-27

Methods, manufactures, machines and compositions are described for nanotransfer and nanoreplication using deterministically grown sacrificial nanotemplates. An apparatus, includes a substrate and a nanoconduit material coupled to a surface of the substrate. The substrate defines an aperture and the nanoconduit material defines a nanoconduit that is i) contiguous with the aperture and ii) aligned substantially non-parallel to a plane defined by the surface of the substrate.

Condensation heat transfer and pressure drop of R-410A in a 7.0 mm O.D. microfin tube at low mass fluxes

NASA Astrophysics Data System (ADS)

Kim, Nae-Hyun

2016-12-01

R-410A condensation heat transfer and pressure drop data are provided for a 7.0 mm O.D. microfin tube at low mass fluxes (50-250 kg/m2 s). The heat transfer coefficient of the microfin tube shows a minimum behavior with the mass flux. At a low mass flux, where flow pattern is stratified, condensation induced by surface tension by microfins overwhelms condensation induced by shear, and the heat transfer coefficient decreases as mass flux increases. At a high mass flux, where flow pattern is annular, condensation induced by shear governs the heat transfer, and the heat transfer coefficient increases as mass flux increases. The pressure drop of the microfin tube is larger than that of the smooth tube at the annular flow regime. On the contrary, the pressure drop of the smooth tube is larger than that of the microfin tube at the stratified flow regime.

Secondary ion mass spectrometry study of ex situ annealing of epitaxial GaAs grown on Si substrates

NASA Technical Reports Server (NTRS)

Radhakrishnan, G.; Mccullough, O.; Cser, J.; Katz, J.

1988-01-01

Samples of epitaxial GaAs grown on (100) Si substrates using molecular beam epitaxy were annealed at four different temperatures, from 800 to 950 C. Following annealing, the samples were analyzed using secondary ion mass spectrometry. Depth profiles of Ga, As, and Si reveal optimum conditions for annealing, and place a lower limit on a damage threshold for GaAs/Si substrates.

Computational Investigation of the Interplay of Substrate Positioning and Reactivity in Catechol O-Methyltransferase

PubMed Central

Patra, Niladri; Ioannidis, Efthymios I.

2016-01-01

Catechol O-methyltransferase (COMT) is a SAM- and Mg2+-dependent methyltransferase that regulates neurotransmitters through methylation. Simulations and experiments have identified divergent catecholamine substrate orientations in the COMT active site: molecular dynamics simulations have favored a monodentate coordination of catecholate substrates to the active site Mg2+, and crystal structures instead preserve bidentate coordination along with short (2.65 Å) methyl donor-acceptor distances. We carry out longer dynamics (up to 350 ns) to quantify interconversion between bidentate and monodentate binding poses. We provide a systematic determination of the relative free energy of the monodentate and bidentate structures in order to identify whether structural differences alter the nature of the methyl transfer mechanism and source of enzymatic rate enhancement. We demonstrate that the bidentate and monodentate binding modes are close in energy but separated by a 7 kcal/mol free energy barrier. Analysis of interactions in the two binding modes reveals that the driving force for monodentate catecholate orientations in classical molecular dynamics simulations is derived from stronger electrostatic stabilization afforded by alternate Mg2+ coordination with strongly charged active site carboxylates. Mixed semi-empirical-classical (SQM/MM) substrate C-O distances (2.7 Å) for the bidentate case are in excellent agreement with COMT X-ray crystal structures, as long as charge transfer between the substrates, Mg2+, and surrounding ligands is permitted. SQM/MM free energy barriers for methyl transfer from bidentate and monodentate catecholate configurations are comparable at around 21–22 kcal/mol, in good agreement with experiment (18–19 kcal/mol). Overall, the work suggests that both binding poses are viable for methyl transfer, and accurate descriptions of charge transfer and electrostatics are needed to provide balanced relative barriers when multiple binding poses are accessible, for example in other transferases. PMID:27564542

The influence of agitation on oil substrate dispersion and oxygen transfer in Pseudomonas aeruginosa USM-AR2 fermentation producing rhamnolipid in a stirred tank bioreactor.

PubMed

Nur Asshifa, M N; Zambry, Nor Syafirah; Salwa, M S; Yahya, Ahmad R M

2017-07-01

Water-immiscible substrate, diesel, was supplied as the main substrate in the fermentation of Pseudomonas aeruginosa USM-AR2 producing rhamnolipid biosurfactant, in a stirred tank bioreactor. In addition to the typical gas-aqueous system, this system includes gas-hydrocarbon-aqueous phases and the presence of surfactant (rhamnolipid) in the fermentation broth. The effect of diesel dispersion on volumetric oxygen transfer coefficient, k L a, and thus oxygen transfer, was evaluated at different agitations of 400, 500 and 600 rpm. The oxygen transfer in this oil-water-surfactant system was shown to be affected by different oil dispersion at those agitation rates. The highest diesel dispersion was obtained at 500 rpm or impeller tip speed of 1.31 m/s, compared to 400 and 600 rpm, which led to the highest k L a, growth and rhamnolipid production by P. aeruginosa USM-AR2. This showed the highest substrate mixing and homogenization at this agitation speed that led to the efficient substrate utilization by the cells. The oxygen uptake rate of P. aeruginosa USM-AR2 was 5.55 mmol/L/h, which showed that even the lowest k L a (48.21 h -1 ) and hence OTR (57.71 mmol/L/h) obtained at 400 rpm was sufficient to fulfill the oxygen demand of the cells. The effect of rhamnolipid concentration on k L a showed that k L a increased as rhamnolipid concentration increased to 0.6 g/L before reaching a plateau. This trend was similar for all agitation rates of 400, 500 and 600 rpm, which might be due to the increase in the resistance to oxygen transfer (k L decrease) and the increase in the specific interfacial area (a).

Influence of indoor environmental factors on mass transfer parameters and concentrations of semi-volatile organic compounds.

PubMed

Wei, Wenjuan; Mandin, Corinne; Ramalho, Olivier

2018-03-01

Semi-volatile organic compounds (SVOCs) in indoor environments can partition among the gas phase, airborne particles, settled dust, and available surfaces. The mass transfer parameters of SVOCs, such as the mass transfer coefficient and the partition coefficient, are influenced by indoor environmental factors. Subsequently, indoor SVOC concentrations and thus occupant exposure can vary depending on environmental factors. In this review, the influence of six environmental factors, i.e., indoor temperature, humidity, ventilation, airborne particle concentration, source loading factor, and reactive chemistry, on the mass transfer parameters and indoor concentrations of SVOCs was analyzed and tentatively quantified. The results show that all mass transfer parameters vary depending on environmental factors. These variations are mostly characterized by empirical equations, particularly for humidity. Theoretical calculations of these parameters based on mass transfer mechanisms are available only for the emission of SVOCs from source surfaces when airborne particles are not present. All mass transfer parameters depend on the temperature. Humidity influences the partition of SVOCs among different phases and is associated with phthalate hydrolysis. Ventilation has a combined effect with the airborne particle concentration on SVOC emission and their mass transfer among different phases. Indoor chemical reactions can produce or eliminate SVOCs slowly. To better model the dynamic SVOC concentration indoors, the present review suggests studying the combined effect of environmental factors in real indoor environments. Moreover, interactions between indoor environmental factors and human activities and their influence on SVOC mass transfer processes should be considered. Copyright © 2017 Elsevier Ltd. All rights reserved.

Precise impurity analysis of Cu films by GDMS: relation between negative substrate bias voltage and impurity ionization potentials

NASA Astrophysics Data System (ADS)

Lim, J. W.; Mimura, K.; Isshiki, M.

2005-02-01

Cu films were deposited on Si(100) substrates by applying a negative substrate bias voltage using the non-mass-separated ion beam deposition method. Glow-discharge mass spectrometry was used to determine the impurity concentrations of the deposited Cu films and the 6N Cu target. It was found that the Cu film deposited at the substrate bias voltage of -50 V showed lower impurity contents than the Cu film deposited without the substrate bias voltage, although both the Cu films were contaminated during the deposition. The purification effect might result from the following reasons: (i) the Penning ionization and an ionization mechanism proposed in the present study, (ii) a difference in the kinetic energy of accelerated Cu+ ions toward the substrate with/without the negative substrate bias voltage.

Fundamental mass transfer modeling of emission of volatile organic compounds from building materials

NASA Astrophysics Data System (ADS)

Bodalal, Awad Saad

In this study, a mass transfer theory based model is presented for characterizing the VOC emissions from building materials. A 3-D diffusion model is developed to describe the emissions of volatile organic compounds (VOCs) from individual sources. Then the formulation is extended to include the emissions from composite sources (system comprising an assemblage of individual sources). The key parameters for the model (The diffusion coefficient of the VOC in the source material D, and the equilibrium partition coefficient k e) were determined independently (model parameters are determined without the use of chamber emission data). This procedure eliminated to a large extent the need for emission testing using environmental chambers, which is costly, time consuming, and may be subject to confounding sink effects. An experimental method is developed and implemented to measure directly the internal diffusion (D) and partition coefficients ( ke). The use of the method is illustrated for three types of VOC's: (i) Aliphatic Hydrocarbons, (ii) Aromatic Hydrocarbons and ( iii) Aldehydes, through typical dry building materials (carpet, plywood, particleboard, vinyl floor tile, gypsum board, sub-floor tile and OSB). Then correlations for predicting D and ke based solely on commonly available properties such as molecular weight and vapour pressure were proposed for each product and type of VOC. These correlations can be used to estimate the D and ke when direct measurement data are not available, and thus facilitate the prediction of VOC emissions from the building materials using mass transfer theory. The VOC emissions from a sub-floor material (made of the recycled automobile tires), and a particleboard are measured and predicted. Finally, a mathematical model to predict the diffusion coefficient through complex sources (floor adhesive) as a function of time was developed. Then this model (for diffusion coefficient in complex sources) was used to predict the emission rate from material system (namely, substrate//glue//vinyl tile).

Protein Design for Pathway Engineering

PubMed Central

Eriksen, Dawn T.; Lian, Jiazhang; Zhao, Huimin

2013-01-01

Design and construction of biochemical pathways has increased the complexity of biosynthetically-produced compounds when compared to single enzyme biocatalysis. However, the coordination of multiple enzymes can introduce a complicated set of obstacles to overcome in order to achieve a high titer and yield of the desired compound. Metabolic engineering has made great strides in developing tools to optimize the flux through a target pathway, but the inherent characteristics of a particular enzyme within the pathway can still limit the productivity. Thus, judicious protein design is critical for metabolic and pathway engineering. This review will describe various strategies and examples of applying protein design to pathway engineering to optimize the flux through the pathway. The proteins can be engineered for altered substrate specificity/selectivity, increased catalytic activity, reduced mass transfer limitations through specific protein localization, and reduced substrate/product inhibition. Protein engineering can also be expanded to design biosensors to enable high through-put screening and to customize cell signaling networks. These strategies have successfully engineered pathways for significantly increased productivity of the desired product or in the production of novel compounds. PMID:23558037

Mixing effects on the kinetics and the dynamics of two-phase enzymatic hydrolysis of hemicellulose for biofuel production.

PubMed

Dutta, Sajal Kanti; Chakraborty, Saikat

2018-07-01

This work uses a coupled experimental and modeling approach to explore the effects of macro- and micro-mixing on the kinetics and the dynamics of two-phase enzymatic hydrolysis of hemicellulose. Reactor mixing does not alter the non-competitive nature of product inhibition in hemicellulose hydrolysis by endoxylanase, but produces stronger inhibition that reduces the soluble sugar yield by 8-14.5%, as the mixing speed increases from 0 to 200 rpm. The kinetic constants (K m , V max , K x ) assume mass-transfer disguised values at 0-200 rpm. An optimal mixing strategy, comprising of 55-70 min of initial rapid convective macromixing followed by diffusive micromixing (without any macromixing) for the rest of the hydrolysis, increases xylose and reducing sugar yields by 6.3-8% and 13-20%, respectively, over continuous mixing at 200 rpm, for 1-5 mg/ml substrate loading at an optimum enzyme to substrate ratio of 1:20, with an energy saving of 94-96% over 24 h. Copyright © 2018 Elsevier Ltd. All rights reserved.

Protein design for pathway engineering.

PubMed

Eriksen, Dawn T; Lian, Jiazhang; Zhao, Huimin

2014-02-01

Design and construction of biochemical pathways has increased the complexity of biosynthetically-produced compounds when compared to single enzyme biocatalysis. However, the coordination of multiple enzymes can introduce a complicated set of obstacles to overcome in order to achieve a high titer and yield of the desired compound. Metabolic engineering has made great strides in developing tools to optimize the flux through a target pathway, but the inherent characteristics of a particular enzyme within the pathway can still limit the productivity. Thus, judicious protein design is critical for metabolic and pathway engineering. This review will describe various strategies and examples of applying protein design to pathway engineering to optimize the flux through the pathway. The proteins can be engineered for altered substrate specificity/selectivity, increased catalytic activity, reduced mass transfer limitations through specific protein localization, and reduced substrate/product inhibition. Protein engineering can also be expanded to design biosensors to enable high through-put screening and to customize cell signaling networks. These strategies have successfully engineered pathways for significantly increased productivity of the desired product or in the production of novel compounds. Copyright © 2013 Elsevier Inc. All rights reserved.

Characterization of high explosive particles using cluster secondary ion mass spectrometry.

PubMed

Gillen, Greg; Mahoney, Christine; Wight, Scott; Lareau, Richard

2006-01-01

The use of secondary ion mass spectrometry (SIMS) for the detection and spatially resolved analysis of individual high explosive particles is described. A C(8) (-) carbon cluster primary ion beam was used in a commercial SIMS instrument to analyze samples of high explosives dispersed as particles on silicon substrates. In comparison with monatomic primary ion bombardment, the carbon cluster primary ion beam was found to greatly enhance characteristic secondary ion signals from the explosive compounds while causing minimal beam-induced degradation. The resistance of these compounds to degradation under ion bombardment allows explosive particles to be analyzed under high primary ion dose bombardment (dynamic SIMS) conditions, facilitating the rapid acquisition of spatially resolved molecular information. The use of cluster SIMS combined with computer control of the sample stage position allows for the automated identification and counting of explosive particle distributions on silicon surfaces. This will be useful for characterizing the efficiency of transfer of particulates in trace explosive detection portal collectors and/or swipes utilized for ion mobility spectrometry applications.

Synthesis, Spray Deposition, and Hot-Press Transfer of Copper Nanowires for Flexible Transparent Electrodes.

PubMed

Deshmukh, Rupali; Calvo, Micha; Schreck, Murielle; Tervoort, Elena; Sologubenko, Alla S; Niederberger, Markus

2018-06-20

We report a solution-phase approach to the synthesis of crystalline copper nanowires (Cu NWs) with an aspect ratio >1000 via a new catalytic mechanism comprising copper ions. The synthesis involves the reaction between copper(II) chloride and copper(II) acetylacetonate in a mixture of oleylamine and octadecene. Reaction parameters such as the molar ratio of precursors as well as the volume ratio of solvents offer the possibility to tune the morphology of the final product. A simple low-cost spray deposition method was used to fabricate Cu NW films on a glass substrate. Post-treatment under reducing gas (5% H 2 + 95% N 2 ) atmosphere resulted in Cu NW films with a low sheet resistance of 24.5 Ω/sq, a transmittance of T = 71% at 550 nm (including the glass substrate), and a high oxidation resistance. Moreover, the conducting Cu NW networks on a glass substrate can easily be transferred onto a polycarbonate substrate using a simple hot-press transfer method without compromising on the electrical performance. The resulting flexible transparent electrodes show excellent flexibility ( R/ R o < 1.28) upon bending to curvatures of 1 mm radius.

Determination of the mass transfer limiting step of dye adsorption onto commercial adsorbent by using mathematical models.

PubMed

Marin, Pricila; Borba, Carlos Eduardo; Módenes, Aparecido Nivaldo; Espinoza-Quiñones, Fernando R; de Oliveira, Silvia Priscila Dias; Kroumov, Alexander Dimitrov

2014-01-01

Reactive blue 5G dye removal in a fixed-bed column packed with Dowex Optipore SD-2 adsorbent was modelled. Three mathematical models were tested in order to determine the limiting step of the mass transfer of the dye adsorption process onto the adsorbent. The mass transfer resistance was considered to be a criterion for the determination of the difference between models. The models contained information about the external, internal, or surface adsorption limiting step. In the model development procedure, two hypotheses were applied to describe the internal mass transfer resistance. First, the mass transfer coefficient constant was considered. Second, the mass transfer coefficient was considered as a function of the dye concentration in the adsorbent. The experimental breakthrough curves were obtained for different particle diameters of the adsorbent, flow rates, and feed dye concentrations in order to evaluate the predictive power of the models. The values of the mass transfer parameters of the mathematical models were estimated by using the downhill simplex optimization method. The results showed that the model that considered internal resistance with a variable mass transfer coefficient was more flexible than the other ones and this model described the dynamics of the adsorption process of the dye in the fixed-bed column better. Hence, this model can be used for optimization and column design purposes for the investigated systems and similar ones.

Carbon monoxide mass transfer for syngas fermentation in a stirred tank reactor with dual impeller configurations.

PubMed

Ungerman, Andrew J; Heindel, Theodore J

2007-01-01

This study compares the power demand and gas-liquid volumetric mass transfer coefficient, kLa, in a stirred tank reactor (STR) (T = 0.211 m) using different impeller designs and schemes in a carbon monoxide-water system, which is applicable to synthesis gas (syngas) fermentation. Eleven different impeller schemes were tested over a range of operating conditions typically associated with the "after large cavity" region (ALC) of a Rushton-type turbine (D/T = 0.35). It is found that the dual Rushton-type impeller scheme exhibits the highest volumetric mass transfer rates for all operating conditions; however, it also displays the lowest mass transfer performance (defined as the volumetric mass transfer coefficient per unit power input) for all conditions due to its high power consumption. Dual impeller schemes with an axial flow impeller as the top impeller show improved mass transfer rates without dramatic increases in power draw. At high gas flow rates, dual impeller schemes with a lower concave impeller have kLa values similar to those of the Rushton-type dual impeller schemes but show improved mass transfer performance. It is believed that the mass transfer performance can be further enhanced for the bottom concave impeller schemes by operating at conditions beyond the ALC region defined for Rushton-type impellers because the concave impeller can handle higher gas flow rates prior to flooding.

Graphene fixed-end beam arrays based on mechanical exfoliation

NASA Astrophysics Data System (ADS)

Li, Peng; You, Zheng; Haugstad, Greg; Cui, Tianhong

2011-06-01

A low-cost mechanical exfoliation method is presented to transfer graphite to graphene for free-standing beam arrays. Nickel film or photoresist is used to peel off and transfer patterned single-layer or multilayer graphene onto substrates with macroscopic continuity. Free-standing graphene beam arrays are fabricated on both silicon and polymer substrates. Their mechanical properties are studied by atomic force microscopy. Finally, a graphene based radio frequency switch is demonstrated, with its pull-in voltage and graphene-silicon junction investigated.

Transferable and flexible label-like macromolecular memory on arbitrary substrates with high performance and a facile methodology.

PubMed

Lai, Ying-Chih; Hsu, Fang-Chi; Chen, Jian-Yu; He, Jr-Hau; Chang, Ting-Chang; Hsieh, Ya-Ping; Lin, Tai-Yuan; Yang, Ying-Jay; Chen, Yang-Fang

2013-05-21

A newly designed transferable and flexible label-like organic memory based on a graphene electrode behaves like a sticker, and can be readily placed on desired substrates or devices for diversified purposes. The memory label reveals excellent performance despite its physical presentation. This may greatly extend the memory applications in various advanced electronics and provide a simple scheme to integrate with other electronics. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sub-second carbon-nanotube-mediated microwave sintering for high-conductivity silver patterns on plastic substrates

NASA Astrophysics Data System (ADS)

Jung, Sunshin; Chun, Su Jin; Han, Joong Tark; Woo, Jong Seok; Shon, Cha-Hwa; Lee, Geon-Woong

2016-02-01

A method of microwave sintering that is mediated by carbon nanotubes (CNTs) has been developed to obtain high-conductivity Ag patterns on the top of heat-sensitive plastic substrates within a short time. The Ag patterns are printed on CNTs formed on plastic substrates and rapidly heated to a great extent by the heat transferred from the microwave-heated CNTs. The conductivity of the microwave-sintered Ag patterns reaches ~39% that of bulk Ag within 1 s without substrate deformation. Furthermore, microwave sintering enhances the adhesion of Ag patterns to the thermoplastic substrates because the sintering causes interfacial fusion between the Ag patterns and the substrates, and CNTs physically connect the patterns with the substrates.A method of microwave sintering that is mediated by carbon nanotubes (CNTs) has been developed to obtain high-conductivity Ag patterns on the top of heat-sensitive plastic substrates within a short time. The Ag patterns are printed on CNTs formed on plastic substrates and rapidly heated to a great extent by the heat transferred from the microwave-heated CNTs. The conductivity of the microwave-sintered Ag patterns reaches ~39% that of bulk Ag within 1 s without substrate deformation. Furthermore, microwave sintering enhances the adhesion of Ag patterns to the thermoplastic substrates because the sintering causes interfacial fusion between the Ag patterns and the substrates, and CNTs physically connect the patterns with the substrates. Electronic supplementary information (ESI) available: Temperature difference in Ag/CNT/PC samples; the carbon content and electrical performance after microwave sintering; microwave sintering of Ag/CNT patterns; physical connection between the substrate and sintered Ag lines; touch-piano (figure and movie). See DOI: 10.1039/c5nr08082g

Assembly of metallic nanoparticle arrays on glass via nanoimprinting and thin-film dewetting

PubMed Central

Lee, Sun-Kyu; Hwang, Sori; Kim, Yoon-Kee

2017-01-01

We propose a nanofabrication process to generate large-area arrays of noble metal nanoparticles on glass substrates via nanoimprinting and dewetting of metallic thin films. Glass templates were made via pattern transfer from a topographic Si mold to an inorganically cross-linked sol–gel (IGSG) resist on glass using a two-layer polydimethylsiloxane (PDMS) stamp followed by annealing, which turned the imprinted resist into pure silica. The transparent, topographic glass successfully templated the assembly of Au and Ag nanoparticle arrays via thin-film deposition and dewetting at elevated temperatures. The microstructural and mechanical characteristics that developed during the processes were discussed. The results are promising for low-cost mass fabrication of devices for several photonic applications. PMID:28546899

Assembly of metallic nanoparticle arrays on glass via nanoimprinting and thin-film dewetting.

PubMed

Lee, Sun-Kyu; Hwang, Sori; Kim, Yoon-Kee; Oh, Yong-Jun

2017-01-01

We propose a nanofabrication process to generate large-area arrays of noble metal nanoparticles on glass substrates via nanoimprinting and dewetting of metallic thin films. Glass templates were made via pattern transfer from a topographic Si mold to an inorganically cross-linked sol-gel (IGSG) resist on glass using a two-layer polydimethylsiloxane (PDMS) stamp followed by annealing, which turned the imprinted resist into pure silica. The transparent, topographic glass successfully templated the assembly of Au and Ag nanoparticle arrays via thin-film deposition and dewetting at elevated temperatures. The microstructural and mechanical characteristics that developed during the processes were discussed. The results are promising for low-cost mass fabrication of devices for several photonic applications.

Evidence for proton tunneling and a transient covalent flavin-substrate adduct in choline oxidase S101A.

PubMed

Uluisik, Rizvan; Romero, Elvira; Gadda, Giovanni

2017-11-01

The effect of temperature on the reaction of alcohol oxidation catalyzed by choline oxidase was investigated with the S101A variant of choline oxidase. Anaerobic enzyme reduction in a stopped-flow spectrophotometer was biphasic using either choline or 1,2-[ 2 H 4 ]-choline as a substrate. The limiting rate constants k lim1 and k lim2 at saturating substrate were well separated (k lim1 /k lim2 >9), and were >15-fold slower than for wild-type choline oxidase. Solvent deuterium kinetic isotope effects (KIEs) ~4 established that k lim1 probes the proton transfer from the substrate hydroxyl to a catalytic base. Primary substrate deuterium KIEs ≥7 demonstrated that k lim2 reports on hydride transfer from the choline alkoxide to the flavin. Between 15°C and 39°C the k lim1 and k lim2 values increased with increasing temperature, allowing for the analyses of H + and H - transfers using Eyring and Arrhenius formalisms. Temperature-independent KIE on the k lim1 value ( H2O k lim1 / D2O k lim1 ) suggests that proton transfer occurs within a highly reorganized tunneling-ready-state with a narrow distribution of donor-acceptor distances. Eyring analysis of the k lim2 value gave lines with the slope (choline) >slope (D-choline) , suggesting kinetic complexity. Spectral evidence for the transient occurrence of a covalent flavin-substrate adduct during the first phase of the anaerobic reaction of S101A CHO with choline is presented, supporting the notion that an important role of amino acid residues in the active site of flavin-dependent enzymes is to eliminate alternative reactions of the versatile enzyme-bound flavin for the reaction that needs to be catalyzed. Copyright © 2017 Elsevier B.V. All rights reserved.

Mass and heat transfer in crushed oil shale

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

Carley, J.F.; Ott, L.L.; Swecker, J.L.

1995-03-01

Studies of heat and mass transfer in packed beds, which disagree substantially in their findings, have nearly all been done with beds of regular particles of uniform size, whereas oil-shale retorting involves particles of diverse irregular shapes and sizes. The authors, in 349 runs, measured mass-transfer rates front naphthalene particles buried in packed beds by passing through air at room temperature. An exact catalog between convection of heat and mass makes it possible to infer heat-transfer coefficients from measured mass-transfer coefficients and fluid properties. Some beds consisted of spheres, naphthalene and inert, of the same, contrasting or distributed sizes. Inmore » some runs, naphthalene spheres were buried in beds of crushed shale, some in narrow screen ranges and others with a wide size range. In others, naphthalene lozenges of different shapes were buried in beds of crushed shale in various bed axis orientations. This technique permits calculation of the mass-transfer coefficient for each active particle in the bed rather than, as in most past studies, for the bed as a whole. The data are analyzed by the traditional correlation of Colburn j{sub D} vs. Reynolds number and by multiple regression of the mass-transfer coefficient on air rate, sizes of active and inert particles, void fraction, and temperature. Principal findings are: local Reynolds number should be based on the active-particle size, not the average for the whole bed; differences between shallow and deep beds are not appreciable; mass transfer is 26% faster for spheres and lozenges buried in shale than in all-sphere beds; orientation of lozenges in shale beds has little or no effect on mass-transfer rate; and for mass or heat transfer in shale beds, log(j{center_dot}{epsilon}) = {minus}0.0747 - 0.6344 log N{sub Re} + 0. 0592 log {sup 2} N{sub Re}.« less

Effect of operating temperature on styrene mass transfer characteristics in a biotrickling filter.

PubMed

Parnian, Parham; Zamir, Seyed Morteza; Shojaosadati, Seyed Abbas

2017-05-01

To study the effect of operating temperature on styrene mass transfer from gas to liquid phase in biotrickling filters (BTFs), overall mass transfer coefficient (K L a) was calculated through fitting test data to a general mass balance model under abiotic conditions. Styrene was used as the volatile organic compound and the BTF was packed with a mixture of pall rings and pumice. Operating temperature was set at 30°C and 50°C for mesophilic and thermophilic conditions, respectively. K L a values increased from 54 to 70 h -1 at 30°C and from 60 to 90 h -1 at 50°C, respectively, depending on the countercurrent gas to liquid flow ratio that varied in the range of 7.5-32. Evaluation of styrene mass transfer capacity (MTC) showed that liquid-phase mass transfer resistance decreased as the flow ratio increased at constant temperature. MTC also decreased with an increase in operating temperature. Both gas-liquid partition coefficient and K L a increased with increasing temperature; however the effect on gas-liquid partition coefficient was more significant and served to increase mass transfer limitations. Thermophilic biofiltration on the one hand increases mass transfer limitations, but on the other hand may enhance the biodegradation rate in favor of enhancing BTFs' performance.

Comparison of different substrates for laser-induced electron transfer desorption/ionization of metal complexes

NASA Astrophysics Data System (ADS)

Grechnikov, A. A.; Georgieva, V. B.; Donkov, N.; Borodkov, A. S.; Pento, A. V.; Raicheva, Z. G.; Yordanov, Tc A.

2016-03-01

Four different substrates, namely, graphite, tungsten, amorphous silicon (α-Si) and titanium dioxide (TiO2) films, were compared in view of the laser-induced electron transfer desorption/ionization (LETDI) of metal coordination complexes. A rhenium complex with 8-mercaptoquinoline, a copper complex with diphenylthiocarbazone and chlorophyll A were studied as the test analytes. The dependencies of the ion yield and the surface temperature on the incident radiation fluence were investigated experimentally and theoretically. The temperature was estimated using the numerical solution of a one-dimensional heat conduction problem with a heat source distributed in time and space. It was found that at the same temperature, the ion yield from the different substrates varies in the range of three orders of magnitude. The direct comparison of all studied substrates revealed that LETDI from the TiO2 and α-Si films offer a better choice for producing molecular ions of metal coordination complexes.

Ozone mass transfer behaviors on physical and chemical absorption for hollow fiber membrane contactors.

PubMed

Zhang, Yong; Li, Kuiling; Wang, Jun; Hou, Deyin; Liu, Huijuan

2017-09-01

To understand the mass transfer behaviors in hollow fiber membrane contactors, ozone fluxes affected by various conditions and membranes were investigated. For physical absorption, mass transfer rate increased with liquid velocity and the ozone concentration in the gas. Gas flow rate was little affected when the velocity was larger than the critical value, which was 6.1 × 10 -3 m/s in this study. For chemical absorption, the flux was determined by the reaction rate between ozone and the absorbent. Therefore, concentration, species, and pH affected the mass transfer process markedly. For different absorbents, the order of mass transfer rate was the same as the reaction rate constant, which was phenol, sodium nitrite, hydrogen peroxide, and oxalate. Five hydrophobic membranes with various properties were employed and the mass transfer behavior can be described by the Graetz-Lévèque equation for the physical absorption process. The results showed the process was controlled by liquid film and the gas phase conditions, and membrane properties did not affect the ozone flux. For the chemical absorption, gas film, membrane and liquid film affected the mass transfer together, and none of them were negligible.

Local Mass and Heat Transfer on a Turbine Blade Tip

DOE PAGES

Jin, P.; Goldstein, R. J.

2003-01-01

Locmore » al mass and heat transfer measurements on a simulated high-pressure turbine blade-tip surface are conducted in a linear cascade with a nonmoving tip endwall, using a naphthalene sublimation technique. The effects of tip clearance (0.86–6.90% of chord) are investigated at various exit Reynolds numbers (4–7 × 10 5 ) and turbulence intensities (0.2 and 12.0%). The mass transfer on the tip surface is significant along its pressure edge at the smallest tip clearance. At the two largest tip clearances, the separation bubble on the tip surface can cover the whole width of the tip on the second half of the tip surface. The average mass-transfer rate is highest at a tip clearance of 1.72% of chord. The average mass-transfer rate on the tip surface is four and six times as high as on the suction and the pressure surface, respectively. A high mainstream turbulence level of 12.0% reduces average mass-transfer rates on the tip surface, while the higher mainstream Reynolds number generates higher local and average mass-transfer rates on the tip surface.« less

Environmentally-assisted technique for transferring devices onto non-conventional substrates

DOEpatents

Lee, Chi-Hwan; Kim, Dong Rip; Zheng, Xiaolin

2016-05-10

A device fabrication method includes: (1) providing a growth substrate including an oxide layer; (2) forming a metal layer over the oxide layer; (3) forming a stack of device layers over the metal layer; (4) performing fluid-assisted interfacial debonding of the metal layer to separate the stack of device layers and the metal layer from the growth substrate; and (5) affixing the stack of device layers to a target substrate.

Enhancing NMR of insensitive nuclei by transfer of SABRE spin hyperpolarization

NASA Astrophysics Data System (ADS)

Pravdivtsev, Andrey N.; Yurkovskaya, Alexandra V.; Zimmermann, Herbert; Vieth, Hans-Martin; Ivanov, Konstantin L.

2016-09-01

We describe the performance of methods for enhancing NMR (Nuclear Magnetic Resonance) signals of "insensitive", but important NMR nuclei, which are based on the SABRE (Signal Amplification By Reversible Exchange) technique, i.e., on spin order transfer from parahydrogen (H2 molecule in its nuclear singlet spin state) to a substrate in a transient organometallic complex. Here such transfer is performed at high magnetic fields by INEPT-type NMR pulse sequences, modified for SABRE. Signal enhancements up to three orders of magnitude are obtained for 15N nuclei; the possibility of sensitive detection of 2D-NMR 1H-15N spectra of SABRE complexes and substrates is demonstrated.

Mechanical properties of water-assembled graphene oxide Langmuir monolayers: Guiding controlled transfer

DOE PAGES

Harrison, Katharine L.; Biedermann, Laura B.; Zavadil, Kevin R.

2015-08-24

Liquid-phase transfer of graphene oxide (GO) and reduced graphene oxide (RGO) monolayers is investigated from the perspective of the mechanical properties of these films. Monolayers are assembled in a Langmuir–Blodgett trough, and oscillatory barrier measurements are used to characterize the resulting compressive and shear moduli as a function of surface pressure. GO monolayers are shown to develop a significant shear modulus (10–25 mN/m) at relevant surface pressures while RGO monolayers do not. The existence of a shear modulus indicates that GO is acting as a two-dimensional solid driven by strong interaction between the individual GO sheets. The absence of suchmore » behavior in RGO is attributed to the decrease in oxygen moieties on the sheet basal plane, permitting RGO sheets to slide across one another with minimum energy dissipation. Knowledge of this two-dimensional solid behavior is exploited to successfully transfer large-area, continuous GO films to hydrophobic Au substrates. The key to successful transfer is the use of shallow-angle dipping designed to minimize tensile stress present during the insertion or extraction of the substrate. A shallow dip angle on hydrophobic Au does not impart a beneficial effect for RGO monolayers, as these monolayers do not behave as two-dimensional solids and do not remain coherent during the transfer process. As a result, we hypothesize that this observed correlation between monolayer mechanical properties and continuous film transfer success is more universally applicable across substrate hydrophobicities and could be exploited to control the transfer of films composed of two-dimensional materials.« less

A bipartite signal mediates the transfer of type IV secretion substrates of Bartonella henselae into human cells

PubMed Central

Schulein, Ralf; Guye, Patrick; Rhomberg, Thomas A.; Schmid, Michael C.; Schröder, Gunnar; Vergunst, Annette C.; Carena, Ilaria; Dehio, Christoph

2005-01-01

Bacterial type IV secretion (T4S) systems mediate the transfer of macromolecular substrates into various target cells, e.g., the conjugative transfer of DNA into bacteria or the transfer of virulence proteins into eukaryotic host cells. The T4S apparatus VirB of the vascular tumor-inducing pathogen Bartonella henselae causes subversion of human endothelial cell (HEC) function. Here we report the identification of multiple protein substrates of VirB, which, upon translocation into HEC, mediate all known VirB-dependent cellular changes. These Bartonella-translocated effector proteins (Beps) A-G are encoded together with the VirB system and the T4S coupling protein VirD4 on a Bartonella-specific pathogenicity island. The Beps display a modular architecture, suggesting an evolution by extensive domain duplication and reshuffling. The C terminus of each Bep harbors at least one copy of the Bep-intracellular delivery domain and a short positively charged tail sequence. This biparte C terminus constitutes a transfer signal that is sufficient to mediate VirB/VirD4-dependent intracellular delivery of reporter protein fusions. The Bep-intracellular delivery domain is also present in conjugative relaxases of bacterial conjugation systems. We exemplarily show that the C terminus of such a conjugative relaxase mediates protein transfer through the Bartonella henselae VirB/VirD4 system into HEC. Conjugative relaxases may thus represent the evolutionary origin of the here defined T4S signal for protein transfer into human cells. PMID:15642951

Importance of a serine proximal to the C(4a) and N(5) flavin atoms for hydride transfer in choline oxidase.

PubMed

Yuan, Hongling; Gadda, Giovanni

2011-02-08

Choline oxidase catalyzes the flavin-dependent, two-step oxidation of choline to glycine betaine with the formation of an aldehyde intermediate. In the first oxidation reaction, the alcohol substrate is initially activated to its alkoxide via proton abstraction. The substrate is oxidized via transfer of a hydride from the alkoxide α-carbon to the N(5) atom of the enzyme-bound flavin. In the wild-type enzyme, proton and hydride transfers are mechanistically and kinetically uncoupled. In this study, we have mutagenized an active site serine proximal to the C(4a) and N(5) atoms of the flavin and investigated the reactions of proton and hydride transfers by using substrate and solvent kinetic isotope effects. Replacement of Ser101 with threonine, alanine, cysteine, or valine resulted in biphasic traces in anaerobic reductions of the flavin with choline investigated in a stopped-flow spectrophotometer. Kinetic isotope effects established that the kinetic phases correspond to the proton and hydride transfer reactions catalyzed by the enzyme. Upon removal of Ser101, there is an at least 15-fold decrease in the rate constants for proton abstraction, irrespective of whether threonine, alanine, valine, or cysteine is present in the mutant enzyme. A logarithmic decrease spanning 4 orders of magnitude is seen in the rate constants for hydride transfer with increasing hydrophobicity of the side chain at position 101. This study shows that the hydrophilic character of a serine residue proximal to the C(4a) and N(5) flavin atoms is important for efficient hydride transfer.

Organic electronics with polymer dielectrics on plastic substrates fabricated via transfer printing

NASA Astrophysics Data System (ADS)

Hines, Daniel R.

Printing methods are fast becoming important processing techniques for the fabrication of flexible electronics. Some goals for flexible electronics are to produce cheap, lightweight, disposable radio frequency identification (RFID) tags, very large flexible displays that can be produced in a roll-to-roll process and wearable electronics for both the clothing and medical industries. Such applications will require fabrication processes for the assembly of dissimilar materials onto a common substrate in ways that are compatible with organic and polymeric materials as well as traditional solid-state electronic materials. A transfer printing method has been developed with these goals and application in mind. This printing method relies primarily on differential adhesion where no chemical processing is performed on the device substrate. It is compatible with a wide variety of materials with each component printed in exactly the same way, thus avoiding any mixed processing steps on the device substrate. The adhesion requirements of one material printed onto a second are studied by measuring the surface energy of both materials and by surface treatments such as plasma exposure or the application of self-assembled monolayers (SAM). Transfer printing has been developed within the context of fabricating organic electronics onto plastic substrates because these materials introduce unique opportunities associated with processing conditions not typically required for traditional semiconducting materials. Compared to silicon, organic semiconductors are soft materials that require low temperature processing and are extremely sensitive to chemical processing and environmental contamination. The transfer printing process has been developed for the important and commonly used organic semiconducting materials, pentacene (Pn) and poly(3-hexylthiophene) (P3HT). A three-step printing process has been developed by which these materials are printed onto an electrode subassembly consisting of previously printed electrodes separated by a polymer dielectric layer all on a plastic substrate. These bottom contact, flexible organic thin-film transistors (OTFT) have been compared to unprinted (reference) devices consisting of top contact electrodes and a silicon dioxide dielectric layer on a silicon substrate. Printed Pn and P3HT TFTs have been shown to out-perform the reference devices. This enhancement has been attributed to an annealing under pressure of the organic semiconducting material.

Ferrocene pixels by laser-induced forward transfer: towards flexible microelectrode printing

NASA Astrophysics Data System (ADS)

Mitu, B.; Matei, A.; Filipescu, M.; Palla Papavlu, A.; Bercea, A.; Lippert, T.; Dinescu, M.

2017-03-01

The aim of this work is to demonstrate the potential of laser-induced forward transfer (LIFT) as a printing technology, alternative to standard microfabrication techniques, in the area of flexible micro-electrode fabrication. First, ferrocene thin films are deposited onto fused silica and fused silica substrates previously coated with a photodegradable polymer film (triazene polymer) by matrix assisted pulsed laser evaporation (MAPLE). The morphology and chemical structure of the ferrocene thin films deposited by MAPLE has been investigated by atomic force microscopy and Fourier transformed infrared spectroscopy, and no structural damage occurs as a result of the laser deposition. Second, LIFT is applied to print for the first time ferrocene pixels and lines onto flexible polydimethylsiloxane (PDMS) substrates. The ferrocene pixels and lines are flawlessly transferred onto the PDMS substrates in air at room temperature, without the need of additional conventional photolithography processes. We believe that these results are very promising for a variety of applications ranging from flexible electronics to lab-on-a-chip devices, MEMS, and medical implants.

Transfer printing of thermoreversible ion gels for flexible electronics.

PubMed

Lee, Keun Hyung; Zhang, Sipei; Gu, Yuanyan; Lodge, Timothy P; Frisbie, C Daniel

2013-10-09

Thermally assisted transfer printing was employed to pattern thin films of high capacitance ion gels on polyimide, poly(ethylene terephthalate), and SiO2 substrates. The ion gels consisted of 20 wt % block copolymer poly(styrene-b-ethylene oxide-b-styrene and 80 wt % ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethyl sulfonyl)amide. Patterning resolution was on the order of 10 μm. Importantly, ion gels containing the block polymer with short PS end blocks (3.4 kg/mol) could be transfer-printed because of thermoreversible gelation that enabled intimate gel-substrate contact at 100 °C, while gels with long PS blocks (11 kg/mol) were not printable at the same temperature due to poor wetting contact between the gel and substrates. By using printed ion gels as high-capacitance gate insulators, electrolyte-gated thin-film transistors were fabricated that operated at low voltages (<1 V) with high on/off current ratios (∼10(5)). Statistical analysis of carrier mobility, turn-on voltage, and on/off ratio for an array of printed transistors demonstrated the excellent reproducibility of the printing technique. The results show that transfer printing is an attractive route to pattern high-capacitance ion gels for flexible thin-film devices.

Strain transfer through film-substrate interface and surface curvature evolution during a tensile test

NASA Astrophysics Data System (ADS)

He, Wei; Han, Meidong; Goudeau, Philippe; Bourhis, Eric Le; Renault, Pierre-Olivier; Wang, Shibin; Li, Lin-an

2018-03-01

Uniaxial tensile tests on polyimide-supported thin metal films are performed to respectively study the macroscopic strain transfer through an interface and the surface curvature evolution. With a dual digital image correlation (DIC) system, the strains of the film and the substrate can be simultaneously measured in situ during the tensile test. For the true strains below 2% (far beyond the films' elastic limit), a complete longitudinal strain transfer is present irrespective of the film thickness, residual stresses and microstructure. By means of an optical surface profiler, the three-dimensional (3D) topography of film surface can be obtained during straining. As expected, the profile of the specimen center remains almost flat in the tensile direction. Nevertheless, a relatively significant curvature evolution (of the same order with the initial curvature induced by residual stresses) is observed along the transverse direction as a result of a Poisson's ratio mismatch between the film and the substrate. Furthermore, finite element method (FEM) has been performed to simulate the curvature evolution considering the geometric nonlinearity and the perfect strain transfer at the interface, which agrees well with the experimental results.

VizieR Online Data Catalog: Adiabatic mass loss in binary stars. II. (Ge+, 2015)

NASA Astrophysics Data System (ADS)

Ge, H.; Webbink, R. F.; Chen, X.; Han, Z.

2016-02-01

In the limit of extremely rapid mass transfer, the response of a donor star in an interacting binary becomes asymptotically one of adiabatic expansion. We survey here adiabatic mass loss from Population I stars (Z=0.02) of mass 0.10M⊙-100M⊙ from the zero-age main sequence to the base of the giant branch, or to central hydrogen exhaustion for lower main sequence stars. The logarithmic derivatives of radius with respect to mass along adiabatic mass-loss sequences translate into critical mass ratios for runaway (dynamical timescale) mass transfer, evaluated here under the assumption of conservative mass transfer. For intermediate- and high-mass stars, dynamical mass transfer is preceded by an extended phase of thermal timescale mass transfer as the star is stripped of most of its envelope mass. The critical mass ratio qad (throughout this paper, we follow the convention of defining the binary mass ratio as q{equiv}Mdonor/Maccretor) above which this delayed dynamical instability occurs increases with advancing evolutionary age of the donor star, by ever-increasing factors for more massive donors. Most intermediate- or high-mass binaries with nondegenerate accretors probably evolve into contact before manifesting this instability. As they approach the base of the giant branch, however, and begin developing a convective envelope, qad plummets dramatically among intermediate-mass stars, to values of order unity, and a prompt dynamical instability occurs. Among low-mass stars, the prompt instability prevails throughout main sequence evolution, with qad declining with decreasing mass, and asymptotically approaching qad=2/3, appropriate to a classical isentropic n=3/2 polytrope. Our calculated qad values agree well with the behavior of time-dependent models by Chen & Han (2003MNRAS.341..662C) of intermediate-mass stars initiating mass transfer in the Hertzsprung gap. Application of our results to cataclysmic variables, as systems that must be stable against rapid mass transfer, nicely circumscribes the range in qad as a function of the orbital period in which they are found. These results are intended to advance the verisimilitude of population synthesis models of close binary evolution. (3 data files).

Prediction and rational correlation of thermophoretically reduced particle mass transfer to hot surfaces across laminar or turbulent forced-convection gas boundary layers

NASA Technical Reports Server (NTRS)

Gokoglu, Suleyman A.; Rosner, Daniel E.

1986-01-01

A formulation previously developed to predict and correlate the thermophoretically-augmented submicron particle mass transfer rate to cold surfaces is found to account for the thermophoretically reduced particle mass transfer rate to overheated surfaces such that thermophoresis brings about a 10-decade reduction below the convective mass transfer rate expected by pure Brownian diffusion and convection alone. Thermophoretic blowing is shown to produce effects on particle concentration boundary-layer (BL) structure and wall mass transfer rates similar to those produced by real blowing through a porous wall. The applicability of the correlations to developing BL-situations is demonstrated by a numerical example relevant to wet-steam technology.

Radiative Transfer in Seagrass Canopies

DTIC Science & Technology

1999-09-30

Radiative Transfer in Seagrass Canopies Richard C. Zimmerman Moss Landing Marine Laboratories P. O. Box 450 Moss Landing, CA 95039 phone (831) 655...models of radiative transfer for optically shallow waters with benthic substrates colonized by submerged plant canopies ( seagrasses and seaweeds). Such...coastal resources. SCIENTIFIC OBJECTIVES The objectives of this study are to • Develop radiative transfer models of seagrass and seaweed canopies in

Versatile transfer of aligned carbon nanotubes with polydimethylsiloxane as the intermediate

NASA Astrophysics Data System (ADS)

Zhu, Yanwu; Lim, Xiaodai; Chea Sim, Mong; Teck Lim, Chwee; Haur Sow, Chorng

2008-08-01

A simple technique to transfer aligned multi-walled carbon nanotubes (MWCNTs) is demonstrated in this work. With polydimethylsiloxane (PDMS) as the transfer medium, as-grown or patterned MWCNT arrays are directly transferred onto a wide variety of Pt-coated substrates such as glossy paper, cloth, polymers, glass slides, and metal foils at low temperatures. The surface of the transferred CNTs is cleaner with better alignment, compared with the as-grown one. Furthermore, the transferred CNTs show strong adhesion and good electric contact with the target substrates. A maximal current density of ~104 A cm-2 has been achieved from the CNT interconnects prepared with this technique. Because of the lower density and open-ended structures, improved field emission performance has been obtained from CNTs transferred on polymers, based on which flexible emitter devices can be fabricated. In addition, the surface of transferred CNTs becomes more hydrophilic, with an averaged contact angle of 93.4 ± 5.8°, in contrast to the super-hydrophobic as-grown CNT surface (contact angle 151.6 ± 5.5°). With versatile properties and flexible applications, the technique provides a simple and cost-effective way towards future nanodevices based on CNTs.

Irradiation-driven Mass Transfer Cycles in Compact Binaries

NASA Astrophysics Data System (ADS)

Büning, A.; Ritter, H.

2005-08-01

We elaborate on the analytical model of Ritter, Zhang, & Kolb (2000) which describes the basic physics of irradiation-driven mass transfer cycles in semi-detached compact binary systems. In particular, we take into account a contribution to the thermal relaxation of the donor star which is unrelated to irradiation and which was neglected in previous studies. We present results of simulations of the evolution of compact binaries undergoing mass transfer cycles, in particular also of systems with a nuclear evolved donor star. These computations have been carried out with a stellar evolution code which computes mass transfer implicitly and models irradiation of the donor star in a point source approximation, thereby allowing for much more realistic simulations than were hitherto possible. We find that low-mass X-ray binaries (LMXBs) and cataclysmic variables (CVs) with orbital periods ⪉ 6hr can undergo mass transfer cycles only for low angular momentum loss rates. CVs containing a giant donor or one near the terminal age main sequence are more stable than previously thought, but can possibly also undergo mass transfer cycles.

Direct measurement of adhesion energy of monolayer graphene as-grown on copper and its application to renewable transfer process.

PubMed

Yoon, Taeshik; Shin, Woo Cheol; Kim, Taek Yong; Mun, Jeong Hun; Kim, Taek-Soo; Cho, Byung Jin

2012-03-14

Direct measurement of the adhesion energy of monolayer graphene as-grown on metal substrates is important to better understand its bonding mechanism and control the mechanical release of the graphene from the substrates, but it has not been reported yet. We report the adhesion energy of large-area monolayer graphene synthesized on copper measured by double cantilever beam fracture mechanics testing. The adhesion energy of 0.72 ± 0.07 J m(-2) was found. Knowing the directly measured value, we further demonstrate the etching-free renewable transfer process of monolayer graphene that utilizes the repetition of the mechanical delamination followed by the regrowth of monolayer graphene on a copper substrate. © 2012 American Chemical Society

Low-energy mass-selected ion beam production of fragments produced from hexamethyldisilane for SiC film formation

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

Yoshimura, Satoru, E-mail: yosimura@ppl.eng.osaka-u.ac.jp; Sugimoto, Satoshi; Kiuchi, Masato

2016-03-14

We have proposed an experimental methodology which makes it possible to deposit silicon carbide (SiC) films on Si substrates with a low-energy mass-selected ion beam system using hexamethyldisilane (HMD) as a gas source. In this study, one of the fragment ions produced from HMD, SiCH{sub 4}{sup +}, was mass-selected. The ion energy was approximately 100 eV. Then, the SiCH{sub 4}{sup +} ions were irradiated to a Si(100) substrate. When the temperature of the Si substrate was set at 800 °C during the ion irradiation, the X-ray diffraction and Raman spectroscopy of the substrate following the completion of ion irradiation experiment demonstrated themore » occurrence of 3C-SiC deposition.« less

Simultaneous Heat and Mass Transfer Model for Convective Drying of Building Material

NASA Astrophysics Data System (ADS)

Upadhyay, Ashwani; Chandramohan, V. P.

2018-04-01

A mathematical model of simultaneous heat and moisture transfer is developed for convective drying of building material. A rectangular brick is considered for sample object. Finite-difference method with semi-implicit scheme is used for solving the transient governing heat and mass transfer equation. Convective boundary condition is used, as the product is exposed in hot air. The heat and mass transfer equations are coupled through diffusion coefficient which is assumed as the function of temperature of the product. Set of algebraic equations are generated through space and time discretization. The discretized algebraic equations are solved by Gauss-Siedel method via iteration. Grid and time independent studies are performed for finding the optimum number of nodal points and time steps respectively. A MATLAB computer code is developed to solve the heat and mass transfer equations simultaneously. Transient heat and mass transfer simulations are performed to find the temperature and moisture distribution inside the brick.

Jason Woods | NREL

Science.gov Websites

doctoral student since 2007. Jason's area of expertise is heat and mass transfer, including the design , analysis, and testing of heat and mass transfer devices and processes. Research Interests Membrane Thermal energy storage Heat and mass transfer enhancements Combined cooling, heat, and power (CCHP

Environmentally-assisted technique for transferring devices onto non-conventional substrates

DOEpatents

Lee, Chi-Hwan; Kim, Dong Rip; Zheng, Xiaolin

2014-08-26

A device fabrication method includes: (1) providing a growth substrate including a base and an oxide layer disposed over the base; (2) forming a metal layer over the oxide layer; (3) forming a stack of device layers over the metal layer; (4) performing interfacial debonding of the metal layer to separate the stack of device layers and the metal layer from the growth substrate; and (5) affixing the stack of device layers to a target substrate.

The role of intra-NAPL diffusion on mass transfer from MGP residuals

NASA Astrophysics Data System (ADS)

Shafieiyoun, Saeid; Thomson, Neil R.

2018-06-01

An experimental and computational study was performed to investigate the role of multi-component intra-NAPL diffusion on NAPL-water mass transfer. Molecular weight and the NAPL component concentrations were determined to be the most important parameters affecting intra-NAPL diffusion coefficients. Four NAPLs with different viscosities but the same quantified mass were simulated. For a spherical NAPL body, a combination of NAPL properties and interphase mass transfer rate can result in internal diffusion limitations. When the main intra-NAPL diffusion coefficients are in the range of self-diffusion coefficients (10-5 to 10-6 cm2/s), dissolution is not limited by internal diffusion except for high mass transfer rate coefficients (>180 cm/day). For a complex and relatively high viscous NAPL (>50 g/(cm s)), smaller intra-NAPL diffusion coefficients (<10-8) are expected and even low mass transfer rate coefficients ( 6 cm/day) can result in diffusion-limited dissolution.

International Space Station (ISS) Water Transfer Hardware Logistics

NASA Technical Reports Server (NTRS)

Shkedi, Brienne D.

2006-01-01

Water transferred from the Space Shuttle to the International Space Station (ISS) is generated as a by-product from the Shuttle fuel cells, and is generally preferred over the Progress which has to launch water from the ground. However, launch mass and volume are still required for the transfer and storage hardware. Some of these up-mass requirements have been reduced since ISS assembly began due to changes in the storage hardware (CWC). This paper analyzes the launch mass and volume required to transfer water from the Shuttle and analyzes the up-mass savings due to modifications in the CWC. Suggestions for improving the launch mass and volume are also provided.

Heat and Mass Transfer in an L Shaped Porous Medium

NASA Astrophysics Data System (ADS)

Salman Ahmed, N. J.; Azeem; Yunus Khan, T. M.

2017-08-01

This article is an extension to the heat transfer in L-shaped porous medium by including the mass diffusion. The heat and mass transfer in the porous domain is represented by three coupled partial differential equations representing the fluid movement, energy transport and mass transport. The equations are converted into algebraic form of equations by the application of finite element method that can be conveniently solved by matrix method. An iterative approach is adopted to solve the coupled equations by setting suitable convergence criterion. The results are discussed in terms of heat transfer characteristics influenced by physical parameters such as buoyancy ratio, Lewis number, Rayleigh number etc. It is found that these physical parameters have significant effect on heat and mass transfer behavior of L-shaped porous medium.

Electrical characterization of non‐Fickian transport in groundwater and hyporheic systems

USGS Publications Warehouse

Singha, Kamini; Pidlisecky, Adam; Day-Lewis, Frederick D.; Gooseff, Michael N.

2008-01-01

Recent work indicates that processes controlling solute mass transfer between mobile and less mobile domains in porous media may be quantified by combining electrical geophysical methods and electrically conductive tracers. Whereas direct geochemical measurements of solute preferentially sample the mobile domain, electrical geophysical methods are sensitive to changes in bulk electrical conductivity (bulk EC) and therefore sample EC in both the mobile and immobile domains. Consequently, the conductivity difference between direct geochemical samples and remotely sensed electrical geophysical measurements may provide an indication of mass transfer rates and mobile and immobile porosities in situ. Here we present (1) an overview of a theoretical framework for determining parameters controlling mass transfer with electrical resistivity in situ; (2) a review of a case study estimating mass transfer processes in a pilot‐scale aquifer storage recovery test; and (3) an example application of this method for estimating mass transfer in watershed settings between streams and the hyporheic corridor. We demonstrate that numerical simulations of electrical resistivity studies of the stream/hyporheic boundary can help constrain volumes and rates of mobile‐immobile mass transfer. We conclude with directions for future research applying electrical geophysics to understand field‐scale transport in aquifer and fluvial systems subject to rate‐limited mass transfer.

Air sparging: Air-water mass transfer coefficients

NASA Astrophysics Data System (ADS)

Braida, Washington J.; Ong, Say Kee

1998-12-01

Experiments investigating the mass transfer of several dissolved volatile organic compounds (VOCs) across the air-water interface were conducted using a single-air- channel air-sparging system. Three different porous media were used in the study. Air velocities ranged from 0.2 cm s-1 to 2.5 cm s-1. The tortuosity factor for each porous medium and the air-water mass transfer coefficients were estimated by fitting experimental data to a one-dimensional diffusion model. The estimated mass transfer coefficients KG ranged from 1.79 × 10-3 cm min-1 to 3.85 × 10-2 cm min-1. The estimated lumped gas phase mass transfer coefficients KGa were found to be directly related to the air diffusivity of the VOC, air velocity, and particle size, and inversely related to the Henry's law constant of the VOCs. Of the four parameters investigated, the parameter that controlled or had a dominant effect on the lumped gas phase mass transfer coefficient was the air diffusivity of the VOC. Two empirical models were developed by correlating the Damkohler and the modified air phase Sherwood numbers with the air phase Peclet number, Henry's law constant, and the reduced mean particle size of porous media. The correlation developed in this study may be used to obtain better predictions of mass transfer fluxes for field conditions.

Investigations of effect of phase change mass transfer rate on cavitation process with homogeneous relaxation model

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

He, Zhixia; Zhang, Liang; Saha, Kaushik

The super high fuel injection pressure and micro size of nozzle orifice has been an important development trend for the fuel injection system. Accordingly, cavitation transient process, fuel compressibility, amount of noncondensable gas in the fuel and cavitation erosion have attracted more attention. Based on the fact of cavitation in itself is a kind of thermodynamic phase change process, this paper takes the perspective of the cavitation phase change mass transfer process to analyze above mentioned phenomenon. The two-phase cavitating turbulent flow simulations with VOF approach coupled with HRM cavitation model and U-RANS of standard k-ε turbulence model were performedmore » for investigations of cavitation phase change mass transfer process. It is concluded the mass transfer time scale coefficient in the Homogenous Relaxation Model (HRM) representing mass transfer rate should tend to be as small as possible in a condition that ensured the solver stable. At very fast mass transfer rate, the phase change occurs at very thin interface between liquid and vapor phase and condensation occurs more focused and then will contribute predictably to a more serious cavitation erosion. Both the initial non-condensable gas in fuel and the fuel compressibility can accelerate the cavitation mass transfer process.« less

Influence of Pupation Substrate on Mass Production and Fitness of Adult Anastrepha obliqua Macquart (Diptera: Tephritidae) for Sterile Insect Technique Application.

PubMed

Aceituno-Medina, Marysol; Rivera-Ciprian, José Pedro; Hernández, Emilio

2017-12-05

Tephritid mass-rearing systems require an artificial substrate for pupation. Pupation substrate characteristics influence the quality of insects produced. Coconut fiber, as an alternative to the conventional pupation substrate vermiculite, was evaluated for Anastrepha obliqua Macquart (Diptera: Tephritidae) pupation behavior (pupation patterns, distribution, respiration rate, and pupal weight) and adult fitness (adult eclosion time, flight ability, and male mating competitiveness). Pupation percentage at 24 h, pupal weight, and flight ability were not significantly affected by substrate type. Adult eclosion levels of 50% were reached at 29.7 and 41.6 h for coconut fiber and vermiculite, respectively. Pupae distribution patterns differed between substrates because the larval aggregation level was reduced during the pupation process in coconut fiber. The pupae aggregation was three times greater in vermiculite than in coconut fiber. A higher respiratory rate in the last days of pupation and adult eclosion were recorded in the insects maintained in coconut fiber. Coconut fiber suitability as a pupation substrate for quality mass production of pupae and its implications for sterile insect technique are discussed. © The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Purification and Characterization of Pyranose Oxidase from the White Rot Fungus Trametes multicolor

PubMed Central

Leitner, Christian; Volc, Jindrich; Haltrich, Dietmar

2001-01-01

We purified an intracellular pyranose oxidase from mycelial extracts of the white rot fungus Trametes multicolor by using ammonium sulfate fractionation, hydrophobic interaction, ion-exchange chromatography, and gel filtration. The native enzyme has a molecular mass of 270 kDa as determined by equilibrium ultracentrifugation and is composed of four identical 68-kDa subunits as determined by matrix-assisted laser desorption ionization mass spectrometry. Each subunit contains one covalently bound flavin adenine dinucleotide as its prosthetic group. The enzyme oxidizes several aldopyranoses specifically at position C-2, and its preferred electron donor substrates are d-glucose, d-xylose, and l-sorbose. During this oxidation reaction electrons are transferred to oxygen, yielding hydrogen peroxide. In addition, the enzyme catalyzes the two-electron reduction of 1,4-benzoquinone, several substituted benzoquinones, and 2,6-dichloroindophenol, as well as the one-electron reduction of the ABTS [2,2′-azinobis(3-ethylbenzthiazolinesulfonic acid)] cation radical. As judged by the catalytic efficiencies (kcat/Km), some of these quinone electron acceptors are much better substrates for pyranose oxidase than oxygen. The optimum pH of the pyranose oxidase-catalyzed reaction depends strongly on the electron acceptor employed and varies from 4 to 8. It has been proposed that the main metabolic function of pyranose oxidase is as a constituent of the ligninolytic system of white rot fungi that provides peroxidases with H2O2. An additional function could be reduction of quinones, key intermediates that are formed during mineralization of lignin. PMID:11472941

Fabrication of functional fibronectin patterns by nanosecond excimer laser direct write for tissue engineering applications.

PubMed

Grigorescu, S; Hindié, M; Axente, E; Carreiras, F; Anselme, K; Werckmann, J; Mihailescu, I N; Gallet, O

2013-07-01

Laser direct write techniques represent a prospective alternative for engineering a new generation of hybrid biomaterials via the creation of patterns consisting of biological proteins onto practically any type of substrate. In this paper we report on the characterization of fibronectin features obtained onto titanium substrates by UV nanosecond laser transfer. Fourier-transform infrared spectroscopy measurements evidenced no modification in the secondary structure of the post-transferred protein. The molecular weight of the transferred protein was identical to the initial fibronectin, no fragment bands being found in the transferred protein's Western blot migration profile. The presence of the cell-binding domain sequence and the mannose groups within the transferred molecules was revealed by anti-fibronectin monoclonal antibody immunolabelling and FITC-Concanavalin-A staining, respectively. The in vitro tests performed with MC3T3-E1 osteoblast-like cells and Swiss-3T3 fibroblasts showed that the cells' morphology and spreading were strongly influenced by the presence of the fibronectin spots.

Sub-10 nm Silicon Nanopillar Fabrication Using Fast and Brushless Thermal Assembly of PS-b-PDMS Diblock Copolymer.

PubMed

Garnier, Jérôme; Arias-Zapata, Javier; Marconot, Olivier; Arnaud, Sandrine; Böhme, Sophie; Girardot, Cécile; Buttard, Denis; Zelsmann, Marc

2016-04-20

A new approach to obtaining spherical nanodomains using polystyrene-block-polydimethylsiloxane (PS-b-PDMS) is proposed. To reduce drastically the process time, we blended a copolymer with cylindrical morphology with a PS homopolymer. Adding PS homopolymer into a low-molar-mass cylindrical morphology PS-b-PDMS system drives it toward a spherical morphology. Besides, by controlling the as-spun state, spherical PDMS nanodomains could be kept and thermally arranged. This PS-homopolymer addition allows not only an efficient, purely thermal arrangement process of spheres but also the ability to work directly on nontreated silicon substrates. Indeed, as shown by STEM measurements, no PS brush surface treatment was necessary in our study to avoid a PDMS wetting layer at the interface with the Si substrate. Our approach was compared to a sphere-forming diblock copolymer, which needs a longer thermal annealing. Furthermore, GISAXS measurements provided complete information on PDMS sphere features. Excellent long-range order spherical microdomains were therefore produced on flat surfaces and inside graphoepitaxy trenches with a period of 21 nm, as were in-plane spheres with a diameter of 8 nm with a 15 min thermal annealing. Finally, direct plasma-etching transfer into the silicon substrate was demonstrated, and 20 nm high silicon nanopillars were obtained, which are very promising results for various nanopatterning applications.

Modeling diffusion control on organic matter decomposition in unsaturated soil pore space

NASA Astrophysics Data System (ADS)

Vogel, Laure; Pot, Valérie; Garnier, Patricia; Vieublé-Gonod, Laure; Nunan, Naoise; Raynaud, Xavier; Chenu, Claire

2014-05-01

Soil Organic Matter decomposition is affected by soil structure and water content, but field and laboratory studies about this issue conclude to highly variable outcomes. Variability could be explained by the discrepancy between the scale at which key processes occur and the measurements scale. We think that physical and biological interactions driving carbon transformation dynamics can be best understood at the pore scale. Because of the spatial disconnection between carbon sources and decomposers, the latter rely on nutrient transport unless they can actively move. In hydrostatic case, diffusion in soil pore space is thus thought to regulate biological activity. In unsaturated conditions, the heterogeneous distribution of water modifies diffusion pathways and rates, thus affects diffusion control on decomposition. Innovative imaging and modeling tools offer new means to address these effects. We have developed a new model based on the association between a 3D Lattice-Boltzmann Model and an adimensional decomposition module. We designed scenarios to study the impact of physical (geometry, saturation, decomposers position) and biological properties on decomposition. The model was applied on porous media with various morphologies. We selected three cubic images of 100 voxels side from µCT-scanned images of an undisturbed soil sample at 68µm resolution. We used LBM to perform phase separation and obtained water phase distributions at equilibrium for different saturation indices. We then simulated the diffusion of a simple soluble substrate (glucose) and its consumption by bacteria. The same mass of glucose was added as a pulse at the beginning of all simulations. Bacteria were placed in few voxels either regularly spaced or concentrated close to or far from the glucose source. We modulated physiological features of decomposers in order to weight them against abiotic conditions. We could evidence several effects creating unequal substrate access conditions for decomposers, hence inducing contrasted decomposition kinetics: position of bacteria relative to the substrate diffusion pathways, diffusion rate and hydraulic connectivity between bacteria and substrate source, local substrate enrichment due to restricted mass transfer. Physiological characteristics had a strong impact on decomposition only when glucose diffused easily but not when diffusion limitation prevailed. This suggests that carbon dynamics should not be considered to derive from decomposers' physiology alone but rather from the interactions of biological and physical processes at the microscale.

Mass Transfer Limited Enhanced Bioremediation at Dnapl Source Zones: a Numerical Study

NASA Astrophysics Data System (ADS)

Kokkinaki, A.; Sleep, B. E.

2011-12-01

The success of enhanced bioremediation of dense non-aqueous phase liquids (DNAPLs) relies on accelerating contaminant mass transfer from the organic to the aqueous phase, thus enhancing the depletion of DNAPL source zones compared to natural dissolution. This is achieved by promoting biological activity that reduces the contaminant's aqueous phase concentration. Although laboratory studies have demonstrated that high reaction rates are attainable by specialized microbial cultures in DNAPL source zones, field applications of the technology report lower reaction rates and prolonged remediation times. One possible explanation for this phenomenon is that the reaction rates are limited by the rate at which the contaminant partitions from the DNAPL to the aqueous phase. In such cases, slow mass transfer to the aqueous phase reduces the bioavailability of the contaminant and consequently decreases the potential source zone depletion enhancement. In this work, the effect of rate limited mass transfer on bio-enhanced dissolution of DNAPL chlorinated ethenes is investigated through a numerical study. A multi-phase, multi-component groundwater transport model is employed to simulate DNAPL mass depletion for a range of source zone scenarios. Rate limited mass transfer is modeled by a linear driving force model, employing a thermodynamic approach for the calculation of the DNAPL - water interfacial area. Metabolic reductive dechlorination is modeled by Monod kinetics, considering microbial growth and self-inhibition. The model was utilized to identify conditions in which mass transfer, rather than reaction, is the limiting process, as indicated by the bioavailability number. In such cases, reaction is slower than expected, and further increase in the reaction rate does not enhance mass depletion. Mass transfer rate limitations were shown to affect both dechlorination and microbial growth kinetics. The complex dynamics between mass transfer, DNAPL transport and distribution, and dechlorination kinetics were reflected in a transient, spatially heterogeneous bioavailability number and dissolution enhancement. In agreement with the literature, source zone architecture largely determined the impact of mass transfer on potential dissolution enhancement, with bioavailability decreasing the most at high ganglia to pool ratios. The results of this study suggest that if mass transfer rate limitations are not considered in designing bioremediation applications at DNAPL source zones, the enhancement of DNAPL depletion and the overall effectiveness of enhanced bioremediation may be significantly overestimated.

Capillary electrophoresis electrospray ionization mass spectrometry interface

DOEpatents

Smith, Richard D.; Severs, Joanne C.

1999-01-01

The present invention is an interface between a capillary electrophoresis separation capillary end and an electrospray ionization mass spectrometry emitter capillary end, for transporting an anolyte sample from a capillary electrophoresis separation capillary to a electrospray ionization mass spectrometry emitter capillary. The interface of the present invention has: (a) a charge transfer fitting enclosing both of the capillary electrophoresis capillary end and the electrospray ionization mass spectrometry emitter capillary end; (b) a reservoir containing an electrolyte surrounding the charge transfer fitting; and (c) an electrode immersed into the electrolyte, the electrode closing a capillary electrophoresis circuit and providing charge transfer across the charge transfer fitting while avoiding substantial bulk fluid transfer across the charge transfer fitting. Advantages of the present invention have been demonstrated as effective in providing high sensitivity and efficient analyses.

Murt user`s guide: A hybrid Lagrangian-Eulerian finite element model of multiple-pore-region solute transport through subsurface media

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

Gwo, J.P.; Jardine, P.M.; Yeh, G.T.

Matrix diffusion, a diffusive mass transfer process,in the structured soils and geologic units at ORNL, is believe to be an important subsurface mass transfer mechanism; it may affect off-site movement of radioactive wastes and remediation of waste disposal sites by locally exchanging wastes between soil/rock matrix and macropores/fractures. Advective mass transfer also contributes to waste movement but is largely neglected by researchers. This report presents the first documented 2-D multiregion solute transport code (MURT) that incorporates not only diffusive but also advective mass transfer and can be applied to heterogeneous porous media under transient flow conditions. In this report, theoreticalmore » background is reviewed and the derivation of multiregion solute transport equations is presented. Similar to MURF (Gwo et al. 1994), a multiregion subsurface flow code, multiplepore domains as suggested by previous investigators (eg, Wilson and Luxmoore 1988) can be implemented in MURT. Transient or steady-state flow fields of the pore domains can be either calculated by MURF or by modelers. The mass transfer process is briefly discussed through a three-pore-region multiregion solute transport mechanism. Mass transfer equations that describe mass flux across pore region interfaces are also presented and parameters needed to calculate mass transfer coefficients detailed. Three applications of MURT (tracer injection problem, sensitivity analysis of advective and diffusive mass transfer, hillslope ponding infiltration and secondary source problem) were simulated and results discussed. Program structure of MURT and functions of MURT subroutiness are discussed so that users can adapt the code; guides for input data preparation are provided in appendices.« less

Enantioselective photochemistry via Lewis acid catalyzed triplet energy transfer

PubMed Central

Blum, Travis R.; Miller, Zachary D.; Bates, Desiree M.; Guzei, Ilia A.; Yoon, Tehshik P.

2017-01-01

Relatively few catalytic systems are able to control the stereochemistry of electronically excited organic intermediates. Here we report the discovery that a chiral Lewis acid complex can catalyze triplet energy transfer from an electronically excited photosensitizer. This strategy is applied to asymmetric [2+2] photocycloadditions of 2′-hydroxychalcones using tris(bipyridyl) ruthenium(II) as a sensitizer. A variety of electrochemical, computational, and spectroscopic data rule out substrate activation via photoinduced electron transfer and instead support a mechanism in which Lewis acid coordination dramatically lowers the triplet energy of the chalcone substrate. We expect that this approach will enable chemists to more broadly apply their detailed understanding of chiral Lewis acid catalysis to stereocontrol in reactions of electronically excited states. PMID:27980203

Quantification of the Mass Transfer at Fluid Interfaces in Microfluidic Channels

NASA Astrophysics Data System (ADS)

Wismeth, Carina; Manhart, Michael; Niessner, Reinhard; Baumann, Thomas

2017-04-01

Mass transfer rates at interfaces in a complex porous media are relevant in many environmental applications and control the functions of natural filter systems in subsurface environments. The mass transfer at fluid interfaces is associated with interface convection caused by local inhomogeneities in interface tension and hydrodynamic instabilities at the interface. If there is a surface tension gradient along the surface a shear stress jump is generated that results in fluid motion along the surface that is called Marangoni effect. These spontaneous convection currents can lead to an increased mass transfer of the transition component at the phase boundary and to an increased mixing of the phases. Therefore compensatory currents at the interface can have a significant influence on the subsurface transport of contaminants in the groundwater area, especially in the vadose zone. Using microfluidic channels and advanced experimental techniques it is possible to measure the fluid flow and mass transfer rates directly and to quantify the effect of the Marangoni convection on the mass transfer at interfaces between a non-aqueous liquid and water with high temporal and spatial resolution. The use of fluorescent particles as well as the recording and analysis of their trajectories is intended to visualize interfacial processes and to quantify the mass transfer at fluid phase boundaries. Concentration gradients at the interface are analysed by spectroscopic methods and allow an assessment of the enrichment and depletion at the phase boundaries. Extensive test series provide the experimental basis for quantifying and analysing the impact of the Marangoni effect on the mass transfer rates at interfaces in porous media in subsurface aquatic environments. Within this research project we concentrate on the effect of Marangoni convection on the mass transfer near an 1-octanol-water interface, which serves as a well defined proxy for non-aqueous phase liquids in porous media. Experiments and a numerical simulation are closely coupled to provide a generic data set with high reproducibility and used to obtain highly resolved three-dimensional data of mass transfer in two- and three-phase systems to foster the understanding of subsurface transport, especially in the vadose zone.

Charge transfer photodissociation of phenol on Ag(111)

NASA Astrophysics Data System (ADS)

Lee, Junseok; Ryu, Sunmin; Ku, Jong Seok; Kim, Seong Keun

2001-12-01

The photochemistry of phenol on Ag(111) has been investigated by post-irradiation temperature programmed desorption (TPD). Ultraviolet (UV) irradiation at 355 and 266 nm was found to affect only the chemisorption layer in direct contact with the metal surface, while leaving the multilayer virtually intact. The main photoinduced reaction was found to be photodissociation of the O-H bond of phenol. Two new peaks were observed at the mass of phenol in the post-irradiation TPD spectrum at 335 K and 455 K. These peaks were assigned to the recombinative desorption of phenoxy with the hydrogen from O-H bond photodissociation and from thermal C-H bond fission, respectively. The photodissociation cross section was measured at different wavelengths and coverages. A charge transfer type photodissociation mechanism was proposed, where hot electrons generated in the substrate by UV photons attach to the affinity level of the adsorbed phenol. The transition to the transient anionic potential then leads to facile dissociation of O-H bond. The affinity level of phenol has been estimated to lie at 3.2-3.5 eV above the Fermi level for the 1 ML case.

Near-field radiative heat transfer in scanning thermal microscopy computed with the boundary element method

NASA Astrophysics Data System (ADS)

Nguyen, K. L.; Merchiers, O.; Chapuis, P.-O.

2017-11-01

We compute the near-field radiative heat transfer between a hot AFM tip and a cold substrate. This contribution to the tip-sample heat transfer in Scanning Thermal Microscopy is often overlooked, despite its leading role when the tip is out of contact. For dielectrics, we provide power levels exchanged as a function of the tip-sample distance in vacuum and spatial maps of the heat flux deposited into the sample which indicate the near-contact spatial resolution. The results are compared to analytical expressions of the Proximity Flux Approximation. The numerical results are obtained by means of the Boundary Element Method (BEM) implemented in the SCUFF-EM software, and require first a thorough convergence analysis of the progressive implementation of this method to the thermal emission by a sphere, the radiative transfer between two spheres, and the radiative exchange between a sphere and a finite substrate.

Charge transfer at organic-inorganic interfaces—Indoline layers on semiconductor substrates

NASA Astrophysics Data System (ADS)

Meyenburg, I.; Falgenhauer, J.; Rosemann, N. W.; Chatterjee, S.; Schlettwein, D.; Heimbrodt, W.

2016-12-01

We studied the electron transfer from excitons in adsorbed indoline dye layers across the organic-inorganic interface. The hybrids consist of indoline derivatives on the one hand and different inorganic substrates (TiO2, ZnO, SiO2(0001), fused silica) on the other. We reveal the electron transfer times from excitons in dye layers to the organic-inorganic interface by analyzing the photoluminescence transients of the dye layers after femtosecond excitation and applying kinetic model calculations. A correlation between the transfer times and four parameters have been found: (i) the number of anchoring groups, (ii) the distance between the dye and the organic-inorganic interface, which was varied by the alkyl-chain lengths between the carboxylate anchoring group and the dye, (iii) the thickness of the adsorbed dye layer, and (iv) the level alignment between the excited dye ( π* -level) and the conduction band minimum of the inorganic semiconductor.

High-frequency self-aligned graphene transistors with transferred gate stacks.

PubMed

Cheng, Rui; Bai, Jingwei; Liao, Lei; Zhou, Hailong; Chen, Yu; Liu, Lixin; Lin, Yung-Chen; Jiang, Shan; Huang, Yu; Duan, Xiangfeng

2012-07-17

Graphene has attracted enormous attention for radio-frequency transistor applications because of its exceptional high carrier mobility, high carrier saturation velocity, and large critical current density. Herein we report a new approach for the scalable fabrication of high-performance graphene transistors with transferred gate stacks. Specifically, arrays of gate stacks are first patterned on a sacrificial substrate, and then transferred onto arbitrary substrates with graphene on top. A self-aligned process, enabled by the unique structure of the transferred gate stacks, is then used to position precisely the source and drain electrodes with minimized access resistance or parasitic capacitance. This process has therefore enabled scalable fabrication of self-aligned graphene transistors with unprecedented performance including a record-high cutoff frequency up to 427 GHz. Our study defines a unique pathway to large-scale fabrication of high-performance graphene transistors, and holds significant potential for future application of graphene-based devices in ultra-high-frequency circuits.

Dye-sensitized solar cells using laser processing techniques

NASA Astrophysics Data System (ADS)

Kim, Heungsoo; Pique, Alberto; Kushto, Gary P.; Auyeung, Raymond C. Y.; Lee, S. H.; Arnold, Craig B.; Kafafi, Zakia H.

2004-07-01

Laser processing techniques, such as laser direct-write (LDW) and laser sintering, have been used to deposit mesoporous nanocrystalline TiO2 (nc-TiO2) films for use in dye-sensitized solar cells. LDW enables the fabrication of conformal structures containing metals, ceramics, polymers and composites on rigid and flexible substrates without the use of masks or additional patterning techniques. The transferred material maintains a porous, high surface area structure that is ideally suited for dye-sensitized solar cells. In this experiment, a pulsed UV laser (355nm) is used to forward transfer a paste of commercial TiO2 nanopowder (P25) onto transparent conducting electrodes on flexible polyethyleneterephthalate (PET) and rigid glass substrates. For the cells based on flexible PET substrates, the transferred TiO2 layers were sintered using an in-situ laser to improve electron paths without damaging PET substrates. In this paper, we demonstrate the use of laser processing techniques to produce nc-TiO2 films (~10 μm thickness) on glass for use in dye-sensitized solar cells (Voc = 690 mV, Jsc = 8.7 mA/cm2, ff = 0.67, η = 4.0 % at 100 mW/cm2). This work was supported by the Office of Naval Research.

Atmospheric pressure plasma jet for biomedical applications characterised by passive thermal probe

NASA Astrophysics Data System (ADS)

Mance, Diana; Wiese, Ruben; Kewitz, Thorben; Kersten, Holger

2018-05-01

Atmospheric pressure plasma jets (APPJs) are a promising tool in medicine with extensive possibilities of utilization. For a safe and therapeutically effective application of APPJs, it is necessary to know in detail the physical processes in plasma as well as possible hazards. In this paper, we focus on plasma thermal energy transferred to the substrate, i.e. to a passive thermal probe acting as substrate dummy. Specifically, we examined the dependence of transferred energy on the distance from the plasma source outlet, on the gas flow rate, and on the length of the visible plasma plume. The plasma plume is the plasma carried by the gas flow from the outlet of the source into the ambient air. The results show the distance between the plasma-generating device and the substrate to be the most important determinant of the transferred thermal energy, among the three examined variables. Most importantly for the end-user, the results also show this relation to be non-linear. To describe this relation, we chose a model based on a Boltzmann type of sigmoid function. Based on the results of our modelling and visual inspection of the plasma, we provide sort of a user guide for the adjustment of a suitable energy flux on the (bio) substrate.

Phthalates and alternative plasticizers and potential for contact exposure from children's backpacks and toys.

PubMed

Xie, Mingjie; Wu, Yaoxing; Little, John C; Marr, Linsey C

2016-01-01

This work focuses on the mass content of plasticizers in children's backpacks and toys, and their mass transfer from product surfaces to cotton wipes. The mass content of plasticizers in six backpacks and seven toys was measured by extracting them in tetrahydrofuran. Bis(2-ethylhexyl) terephthalate (DEHT) was the most common plasticizer, dominating the composition of plasticizers in four backpacks (average mass content in product polyvinyl chloride, 5.38 ± 1.98%-25.5 ± 3.54%) and six plastic toys (8.17 ± 1.85%-21.2 ± 1.11%). The surface of each product was wiped with three dry and three wet (by isopropanol) cotton wipes, so as to evaluate the mass transfer of plasticizers to clothing and human skin, respectively. DEHT was the most common plasticizer detected on wipe samples. There were strong correlations (backpacks r=0.90; plastic toys r=0.96) between average mass transfer of DEHT to wet wipes and its average mass content in the product. The mass transfers of the five dominant plasticizers in one backpack to both dry and wet wipes were also correlated (both r=1.00) with their mass contents. These results suggest that the mass transfer of plasticizers from products to clothing or human skin is strongly associated with their mass content.

Micro environmental sensing device

DOEpatents

Polosky, Marc A.; Lukens, Laurance L.

2006-05-02

A microelectromechanical (MEM) acceleration switch is disclosed which includes a proof mass flexibly connected to a substrate, with the proof mass being moveable in a direction substantially perpendicular to the substrate in response to a sensed acceleration. An electrode on the proof mass contacts one or more electrodes located below the proof mass to provide a switch closure in response to the sensed acceleration. Electrical latching of the switch in the closed position is possible with an optional latching electrode. The MEM acceleration switch, which has applications for use as an environmental sensing device, can be fabricated using micromachining.

Mass transfer effects in a gasification riser

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

Breault, Ronald W.; Li, Tingwen; Nicoletti, Phillip

2013-07-01

In the development of multiphase reacting computational fluid dynamics (CFD) codes, a number of simplifications were incorporated into the codes and models. One of these simplifications was the use of a simplistic mass transfer correlation for the faster reactions and omission of mass transfer effects completely on the moderate speed and slow speed reactions such as those in a fluidized bed gasifier. Another problem that has propagated is that the mass transfer correlation used in the codes is not universal and is being used far from its developed bubbling fluidized bed regime when applied to circulating fluidized bed (CFB) risermore » reactors. These problems are true for the major CFD codes. To alleviate this problem, a mechanistic based mass transfer coefficient algorithm has been developed based upon an earlier work by Breault et al. This fundamental approach uses the local hydrodynamics to predict a local, time varying mass transfer coefficient. The predicted mass transfer coefficients and the corresponding Sherwood numbers agree well with literature data and are typically about an order of magnitude lower than the correlation noted above. The incorporation of the new mass transfer model gives the expected behavior for all the gasification reactions evaluated in the paper. At the expected and typical design values for the solid flow rate in a CFB riser gasifier an ANOVA analysis has shown the predictions from the new code to be significantly different from the original code predictions. The new algorithm should be used such that the conversions are not over predicted. Additionally, its behaviors with changes in solid flow rate are consistent with the changes in the hydrodynamics.« less

Beyond the standard two-film theory: Computational fluid dynamics simulations for carbon dioxide capture in a wetted wall column

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

Wang, Chao; Xu, Zhijie; Lai, Canhai

The standard two-film theory (STFT) is a diffusion-based mechanism that can be used to describe gas mass transfer across liquid film. Fundamental assumptions of the STFT impose serious limitations on its ability to predict mass transfer coefficients. To better understand gas absorption across liquid film in practical situations, a multiphase computational fluid dynamics (CFD) model fully equipped with mass transport and chemistry capabilities has been developed for solvent-based carbon dioxide (CO 2) capture to predict the CO 2 mass transfer coefficient in a wetted wall column. The hydrodynamics is modeled using a volume of fluid method, and the diffusive andmore » reactive mass transfer between the two phases is modeled by adopting a one-fluid formulation. We demonstrate that the proposed CFD model can naturally account for the influence of many important factors on the overall mass transfer that cannot be quantitatively explained by the STFT, such as the local variation in fluid velocities and properties, flow instabilities, and complex geometries. The CFD model also can predict the local mass transfer coefficient variation along the column height, which the STFT typically does not consider.« less

Beyond the standard two-film theory: Computational fluid dynamics simulations for carbon dioxide capture in a wetted wall column

DOE PAGES

Wang, Chao; Xu, Zhijie; Lai, Canhai; ...

2018-03-27

The standard two-film theory (STFT) is a diffusion-based mechanism that can be used to describe gas mass transfer across liquid film. Fundamental assumptions of the STFT impose serious limitations on its ability to predict mass transfer coefficients. To better understand gas absorption across liquid film in practical situations, a multiphase computational fluid dynamics (CFD) model fully equipped with mass transport and chemistry capabilities has been developed for solvent-based carbon dioxide (CO 2) capture to predict the CO 2 mass transfer coefficient in a wetted wall column. The hydrodynamics is modeled using a volume of fluid method, and the diffusive andmore » reactive mass transfer between the two phases is modeled by adopting a one-fluid formulation. We demonstrate that the proposed CFD model can naturally account for the influence of many important factors on the overall mass transfer that cannot be quantitatively explained by the STFT, such as the local variation in fluid velocities and properties, flow instabilities, and complex geometries. The CFD model also can predict the local mass transfer coefficient variation along the column height, which the STFT typically does not consider.« less

ADIABATIC MASS LOSS IN BINARY STARS. II. FROM ZERO-AGE MAIN SEQUENCE TO THE BASE OF THE GIANT BRANCH

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

Ge, Hongwei; Chen, Xuefei; Han, Zhanwen

2015-10-10

In the limit of extremely rapid mass transfer, the response of a donor star in an interacting binary becomes asymptotically one of adiabatic expansion. We survey here adiabatic mass loss from Population I stars (Z = 0.02) of mass 0.10 M{sub ⊙}–100 M{sub ⊙} from the zero-age main sequence to the base of the giant branch, or to central hydrogen exhaustion for lower main sequence stars. The logarithmic derivatives of radius with respect to mass along adiabatic mass-loss sequences translate into critical mass ratios for runaway (dynamical timescale) mass transfer, evaluated here under the assumption of conservative mass transfer. Formore » intermediate- and high-mass stars, dynamical mass transfer is preceded by an extended phase of thermal timescale mass transfer as the star is stripped of most of its envelope mass. The critical mass ratio q{sub ad} (throughout this paper, we follow the convention of defining the binary mass ratio as q ≡ M{sub donor}/M{sub accretor}) above which this delayed dynamical instability occurs increases with advancing evolutionary age of the donor star, by ever-increasing factors for more massive donors. Most intermediate- or high-mass binaries with nondegenerate accretors probably evolve into contact before manifesting this instability. As they approach the base of the giant branch, however, and begin developing a convective envelope, q{sub ad} plummets dramatically among intermediate-mass stars, to values of order unity, and a prompt dynamical instability occurs. Among low-mass stars, the prompt instability prevails throughout main sequence evolution, with q{sub ad} declining with decreasing mass, and asymptotically approaching q{sub ad} = 2/3, appropriate to a classical isentropic n = 3/2 polytrope. Our calculated q{sub ad} values agree well with the behavior of time-dependent models by Chen and Han of intermediate-mass stars initiating mass transfer in the Hertzsprung gap. Application of our results to cataclysmic variables, as systems that must be stable against rapid mass transfer, nicely circumscribes the range in q{sub ad} as a function of the orbital period in which they are found. These results are intended to advance the verisimilitude of population synthesis models of close binary evolution.« less

Membrane-Mediated Extraction and Biodegradation of Volatile Organic Compounds From Air

DTIC Science & Technology

2005-01-01

side boundary-layer mass transfer resistance is a significant fraction of the total mass transfer resistance ( Raghunath , 1992). In some cases where...Sci. 59: 53–72. Raghunath , B., and S.–T. Hwang (1992). “Effect of boundary layer mass transfer resistance in the pervaporation of dilute organics

A comparison of mass transfer coefficients between trickle-bed, hollow fiber membrane and stirred tank reactors.

PubMed

Orgill, James J; Atiyeh, Hasan K; Devarapalli, Mamatha; Phillips, John R; Lewis, Randy S; Huhnke, Raymond L

2013-04-01

Trickle-bed reactor (TBR), hollow fiber membrane reactor (HFR) and stirred tank reactor (STR) can be used in fermentation of sparingly soluble gasses such as CO and H2 to produce biofuels and bio-based chemicals. Gas fermenting reactors must provide high mass transfer capabilities that match the kinetic requirements of the microorganisms used. The present study compared the volumetric mass transfer coefficient (K(tot)A/V(L)) of three reactor types; the TBR with 3 mm and 6 mm beads, five different modules of HFRs, and the STR. The analysis was performed using O2 as the gaseous mass transfer agent. The non-porous polydimethylsiloxane (PDMS) HFR provided the highest K(tot)A/V(L) (1062 h(-1)), followed by the TBR with 6mm beads (421 h(-1)), and then the STR (114 h(-1)). The mass transfer characteristics in each reactor were affected by agitation speed, and gas and liquid flow rates. Furthermore, issues regarding the comparison of mass transfer coefficients are discussed. Copyright © 2013 Elsevier Ltd. All rights reserved.

Determination of the profile of DO and its mass transferring coefficient in a biofilm reactor packed with semi-suspended bio-carriers.

PubMed

Tang, Bing; Song, Haoliang; Bin, Liying; Huang, Shaosong; Zhang, Wenxiang; Fu, Fenglian; Zhao, Yiliang; Chen, Qianyu

2017-10-01

The work aims at illustrating the profile of DO and its mass transferring process in a biofilm reactor packed with a novel semi-suspended bio-carrier, and further revealing the main factors that influence the mass transferring coefficient of DO within the biofilm. Results showed that the biofilm was very easy to attach and grow on the semi-suspended bio-carrier, which obviously changed the DO profile inside and outside the biofilm. The semi-suspended bio-carrier caused three different mass transfer zones occurring in the bioreactor, including the zones of bulk solution, boundary layer and biofilm, in which, the boundary layer zone had an obvious higher mass transfer resistance. Increasing the aeration rate might improve the hydrodynamic conditions in the bioreactor and accelerate the mass transfer of DO, but it also detached the biofilm from the surface of bio-carrier, which reduced the consumption of DO, and accordingly, decreased the DO gradient in the bioreactor. Copyright © 2017 Elsevier Ltd. All rights reserved.

[Correlation of molecular weight and nanofiltration mass transfer coefficient of phenolic acid composition from Salvia miltiorrhiza].

PubMed

Li, Cun-Yu; Wu, Xin; Gu, Jia-Mei; Li, Hong-Yang; Peng, Guo-Ping

2018-04-01

Based on the molecular sieving and solution-diffusion effect in nanofiltration separation, the correlation between initial concentration and mass transfer coefficient of three typical phenolic acids from Salvia miltiorrhiza was fitted to analyze the relationship among mass transfer coefficient, molecular weight and concentration. The experiment showed a linear relationship between operation pressure and membrane flux. Meanwhile, the membrane flux was gradually decayed with the increase of solute concentration. On the basis of the molecular sieving and solution-diffusion effect, the mass transfer coefficient and initial concentration of three phenolic acids showed a power function relationship, and the regression coefficients were all greater than 0.9. The mass transfer coefficient and molecular weight of three phenolic acids were negatively correlated with each other, and the order from high to low is protocatechualdehyde >rosmarinic acid> salvianolic acid B. The separation mechanism of nanofiltration for phenolic acids was further clarified through the analysis of the correlation of molecular weight and nanofiltration mass transfer coefficient. The findings provide references for nanofiltration separation, especially for traditional Chinese medicine with phenolic acids. Copyright© by the Chinese Pharmaceutical Association.

Mass transfer in a 1370 C (2500 F) lithium thermal convection loop

NASA Technical Reports Server (NTRS)

Scheuermann, C. M.

1974-01-01

Experimental results from a test to evaluate interstitial element mass transfer effects on T-111, ASTAR 811C, and ASTAR 1211C after 5000 hours in flowing lithium at 1370 C (2500 F) are presented. No gross corrosion effects were observed. However, hafnium and nitrogen transfer to cooler regions within the loop were noted. Oxygen was in general removed from test specimens, but there was no evidence to indicate that it was a major factor in the mass transfer process. Carbon and hydrogen transfer were not detected.

Transferring-free and large-area graphitic carbon film growth by using molecular beam epitaxy at low growth temperature

NASA Astrophysics Data System (ADS)

Lin, Meng-Yu; Wang, Cheng-Hung; Pao, Chun-Wei; Lin, Shih-Yen

2015-09-01

Graphitic carbon films prepared by using molecular beam epitaxy (MBE) on metal templates with different thicknesses deposited on SiO2/Si substrates are investigated in this paper. With thick Cu templates, only graphitic carbon flakes are obtained near the Cu grain boundaries at low growth temperatures on metal/SiO2 interfaces. By replacing the Cu templates with thin Ni templates, complete graphitic carbon films with superior crystalline quality is obtained at 600 °C on SiO2/Si substrates after removing the Ni templates. The enhanced attachment of the graphitic carbon film to the SiO2/Si substrates with reduced Ni thickness makes the approach a promising approach for transferring-free graphene preparation at low temperature by using MBE.

The Transfer of a Holographic Structure from Dihromated Gelatin Layers on a Polymethylmethacrylate Substrate

NASA Astrophysics Data System (ADS)

Ganzherli, N. M.; Gulyaev, S. N.; Maurer, I. A.; Khazvalieva, D. R.

2018-03-01

The possibility of the transfer of a holographic structure that was originally registered on layers of dichromated gelatin (DCG) onto a substrate material of polymethylmethacrylate (PMMA) has been shown. The use of a selective destructive effect of short-wave UV radiation with a wavelength that is less than 270 nm is the basis of the mechanism of formation of secondary relief-phase holographic structure on the surface of PMMA. The optimization of processing modes and selection of developing compositions which are based on isopropanol and methylisobutylketone (MIBK) have been carried out, which made it possible to create reliefphase holographic gratings with high diffraction efficiency (DE) of about 25% and the maximum depth of the surface relief of the order of 1 μm on the substrates of PMMA.

Insights into the glycyl radical enzyme active site of benzylsuccinate synthase: a computational study.

PubMed

Bharadwaj, Vivek S; Dean, Anthony M; Maupin, C Mark

2013-08-21

The fumarate addition reaction, catalyzed by the enzyme benzylsuccinate synthase (BSS), is considered to be one of the most intriguing and energetically challenging reactions in biology. BSS belongs to the glycyl radical enzyme family and catalyzes the fumarate addition reaction, which enables microorganisms to utilize hydrocarbons as an energy source under anaerobic conditions. Unfortunately, the extreme sensitivity of the glycyl radical to oxygen has hampered the structural and kinetic characterization of BSS, thereby limiting our knowledge on this enzyme. To enhance our molecular-level understanding of BSS, a computational approach involving homology modeling, docking studies, and molecular dynamics (MD) simulations has been used to deduce the structure of BSS's catalytic subunit (BSSα) and illuminate the molecular basis for the fumarate addition reaction. We have identified two conserved and distinct binding pockets at the BSSα active site: a hydrophobic pocket for toluene binding and a polar pocket for fumaric acid binding. Subsequent dynamical and energetic evaluations have identified Glu509, Ser827, Leu390, and Phe384 as active site residues critical for substrate binding. The orientation of substrates at the active site observed in MD simulations is consistent with experimental observations of the syn addition of toluene to fumaric acid. It is also found that substrate binding tightens the active site and restricts the conformational flexibility of the thiyl radical, leading to hydrogen transfer distances conducive to the proposed reaction mechanism. The stability of substrates at the active site and the occurrence of feasible radical transfer distances between the thiyl radical, substrates, and the active site glycine indicate a substrate-assisted radical transfer pathway governing fumarate addition.

DNA and Protein Requirements for Substrate Conformational Changes Necessary for Human Flap Endonuclease-1-catalyzed Reaction*

PubMed Central

Algasaier, Sana I.; Exell, Jack C.; Bennet, Ian A.; Thompson, Mark J.; Gotham, Victoria J. B.; Shaw, Steven J.; Craggs, Timothy D.; Finger, L. David; Grasby, Jane A.

2016-01-01

Human flap endonuclease-1 (hFEN1) catalyzes the essential removal of single-stranded flaps arising at DNA junctions during replication and repair processes. hFEN1 biological function must be precisely controlled, and consequently, the protein relies on a combination of protein and substrate conformational changes as a prerequisite for reaction. These include substrate bending at the duplex-duplex junction and transfer of unpaired reacting duplex end into the active site. When present, 5′-flaps are thought to thread under the helical cap, limiting reaction to flaps with free 5′-termini in vivo. Here we monitored DNA bending by FRET and DNA unpairing using 2-aminopurine exciton pair CD to determine the DNA and protein requirements for these substrate conformational changes. Binding of DNA to hFEN1 in a bent conformation occurred independently of 5′-flap accommodation and did not require active site metal ions or the presence of conserved active site residues. More stringent requirements exist for transfer of the substrate to the active site. Placement of the scissile phosphate diester in the active site required the presence of divalent metal ions, a free 5′-flap (if present), a Watson-Crick base pair at the terminus of the reacting duplex, and the intact secondary structure of the enzyme helical cap. Optimal positioning of the scissile phosphate additionally required active site conserved residues Tyr40, Asp181, and Arg100 and a reacting duplex 5′-phosphate. These studies suggest a FEN1 reaction mechanism where junctions are bound and 5′-flaps are threaded (when present), and finally the substrate is transferred onto active site metals initiating cleavage. PMID:26884332

Highly Enhanced Electromechanical Stability of Large-Area Graphene with Increased Interfacial Adhesion Energy by Electrothermal-Direct Transfer for Transparent Electrodes.

PubMed

Kim, Jangheon; Kim, Gi Gyu; Kim, Soohyun; Jung, Wonsuk

2016-09-07

Graphene, a two-dimensional sheet of carbon atoms in a hexagonal lattice structure, has been extensively investigated for research and industrial applications as a promising material with outstanding electrical, mechanical, and chemical properties. To fabricate graphene-based devices, graphene transfer to the target substrate with a clean and minimally defective surface is the first step. However, graphene transfer technologies require improvement in terms of uniform transfer with a clean, nonfolded and nontorn area, amount of defects, and electromechanical reliability of the transferred graphene. More specifically, uniform transfer of a large area is a key challenge when graphene is repetitively transferred onto pretransferred layers because the adhesion energy between graphene layers is too low to ensure uniform transfer, although uniform multilayers of graphene have exhibited enhanced electrical and optical properties. In this work, we developed a newly suggested electrothermal-direct (ETD) transfer method for large-area high quality monolayer graphene with less defects and an absence of folding or tearing of the area at the surface. This method delivers uniform multilayer transfer of graphene by repetitive monolayer transfer steps based on high adhesion energy between graphene layers and the target substrate. To investigate the highly enhanced electromechanical stability, we conducted mechanical elastic bending experiments and reliability tests in a highly humid environment. This ETD-transferred graphene is expected to replace commercial transparent electrodes with ETD graphene-based transparent electrodes and devices such as a touch panels with outstanding electromechanical stability.

Plasma phospholipid transfer protein activity is inversely associated with betaine in diabetic and non-diabetic subjects.

PubMed

Dullaart, R P F; Garcia, Erwin; Jeyarajah, Elias; Gruppen, Eke G; Connelly, Margery A

2016-08-31

The choline metabolite, betaine, plays a role in lipid metabolism, and may predict the development of cardiovascular disease and type 2 diabetes mellitus (T2DM). Phospholipid transfer protein (PLTP) and lecithin:cholesterol acyltransferase (LCAT) require phosphatidylcholine as substrate, raising the possibility that there is an intricate relationship of these protein factors with choline metabolism. Here we determined the relationships of PLTP and LCAT activity with betaine in subjects with and without T2DM. Plasma betaine (nuclear magnetic resonance spectroscopy), PLTP activity (liposome-vesicle HDL system), LCAT activity (exogenous substrate assay) and (apo)lipoproteins were measured in 65 type 2 diabetic (T2DM) and in 55 non-diabetic subjects. PLTP and LCAT activity were elevated in T2DM (p < 0.05), whereas the difference in betaine was not significant. In age-, sex- and diabetes status-controlled correlation analysis, betaine was inversely correlated with triglycerides and positively with HDL cholesterol (p < 0.05 to 0.01). PLTP and LCAT activity were positively correlated with triglycerides and inversely with HDL cholesterol (p < 0.05 to 0.001). PLTP (r = -0.245, p = 0.006) and LCAT activity (r = -0.195, p = 0.035) were correlated inversely with betaine. The inverse association of PLTP activity with betaine remained significant after additional adjustment for body mass index and lipoprotein variables (β = -0.179, p = 0.034), whereas its association with LCAT activity lost significance (β = -0.056, p = 0.44). Betaine may influence lipoprotein metabolism via an effect on PLTP activity.

Functional properties and structural requirements of the plasmid pMV158-encoded MobM relaxase domain.

PubMed

Fernández-López, Cris; Pluta, Radoslaw; Pérez-Luque, Rosa; Rodríguez-González, Lorena; Espinosa, Manuel; Coll, Miquel; Lorenzo-Díaz, Fabián; Boer, D Roeland

2013-07-01

A crucial element in the horizontal transfer of mobilizable and conjugative plasmids is the relaxase, a single-stranded endonuclease that nicks the origin of transfer (oriT) of the plasmid DNA. The relaxase of the pMV158 mobilizable plasmid is MobM (494 residues). In solution, MobM forms a dimer through its C-terminal domain, which is proposed to anchor the protein to the cell membrane and to participate in type 4 secretion system (T4SS) protein-protein interactions. In order to gain a deeper insight into the structural MobM requirements for efficient DNA catalysis, we studied two endonuclease domain variants that include the first 199 or 243 amino acid residues (MobMN199 and MobMN243, respectively). Our results confirmed that the two proteins behaved as monomers in solution. Interestingly, MobMN243 relaxed supercoiled DNA and cleaved single-stranded oligonucleotides harboring oriTpMV158, whereas MobMN199 was active only on supercoiled DNA. Protein stability studies using gel electrophoresis and mass spectrometry showed increased susceptibility to degradation at the domain boundary between the N- and C-terminal domains, suggesting that the domains change their relative orientation upon DNA binding. Overall, these results demonstrate that MobMN243 is capable of nicking the DNA substrate independently of its topology and that the amino acids 200 to 243 modulate substrate specificity but not the nicking activity per se. These findings suggest that these amino acids are involved in positioning the DNA for the nuclease reaction rather than in the nicking mechanism itself.

Wettability of Molten Aluminum-Silicon Alloys on Graphite and Surface Tension of Those Alloys at 1273 K (1000 °C)

NASA Astrophysics Data System (ADS)

Mao, Weiji; Noji, Takayasu; Teshima, Kenichiro; Shinozaki, Nobuya

2016-06-01

The wettability of molten aluminum-silicon alloys with silicon contents of 0, 6, 10, and 20 mass pct on graphite substrates by changing the placing sequence of aluminum and silicon and the surface tension of those alloys were investigated at 1273 K (1000 °C) using the sessile drop method under vacuum. The results showed that the wetting was not affected by changing the placing sequence of the Al-Si alloys on the graphite substrates. The wettability was not improved significantly upon increasing the Si content from 0 to 10 mass pct, whereas a notable decrease of 22 deg in the contact angle was observed when increasing the Si content from 10 to 20 mass pct. This was attributed to the transformation of the interfacial reaction product from Al4C3 into SiC, provided the addition of Si to Al was sufficient. It was verified that the liquid Al can wet the SiC substrate very well in nature, which might explain why the occurrence of SiC would improve the wettability of the Al-20 mass pct Si alloy on the graphite substrate. The results also showed that the surface tension values of the molten Al-Si alloys decreased monotonously with an increase in Si content, being 875, 801, 770, and 744 mN/m for molten Al, Al-6 mass pct Si, Al-10 mass pct Si, and Al-20 mass pct Si alloys, respectively.

Toward a universal mass-momentum transfer relationship for predicting nutrient uptake and metabolite exchange in benthic reef communities

NASA Astrophysics Data System (ADS)

Falter, James L.; Lowe, Ryan J.; Zhang, Zhenlin

2016-09-01

Here we synthesize data from previous field and laboratory studies describing how rates of nutrient uptake and metabolite exchange (mass transfer) are related to form drag and bottom stresses (momentum transfer). Reanalysis of this data shows that rates of mass transfer are highly correlated (r2 ≥ 0.9) with the root of the bottom stress (τbot0.4) under both waves and currents and only slightly higher under waves (~10%). The amount of mass transfer that can occur per unit bottom stress (or form drag) is influenced by morphological features ranging anywhere from millimeters to meters in scale; however, surface-scale roughness (millimeters) appears to have little effect on actual nutrient uptake by living reef communities. Although field measurements of nutrient uptake by natural reef communities agree reasonably well with predictions based on existing mass-momentum transfer relationships, more work is needed to better constrain these relationships for more rugose and morphologically complex communities.

Influence of drying air parameters on mass transfer characteristics of apple slices

NASA Astrophysics Data System (ADS)

Beigi, Mohsen

2016-10-01

To efficiently design both new drying process and equipment and/or to improve the existing systems, accurate values of mass transfer characteristics are necessary. The present study aimed to investigate the influence of drying air parameters (i.e. temperature, velocity and relative humidity) on effective diffusivity and convective mass transfer coefficient of apple slices. The Dincer and Dost model was used to determine the mass transfer characteristics. The obtained Biot number indicated that the moisture transfer in the apple slices was controlled by both internal and external resistance. The effective diffusivity and mass transfer coefficient values obtained to be in the ranges of 7.13 × 10-11-7.66 × 10-10 and 1.46 × 10-7-3.39 × 10-7 m s-1, respectively and the both of them increased with increasing drying air temperature and velocity, and decreasing relative humidity. The validation of the model showed that the model predicted the experimental drying curves of the samples with a good accuracy.

Ultrasound in Enzyme Activation and Inactivation

NASA Astrophysics Data System (ADS)

Mawson, Raymond; Gamage, Mala; Terefe, Netsanet Shiferaw; Knoerzer, Kai

As discussed in previous chapters, most effects due to ultrasound arise from cavitation events, in particular, collapsing cavitation bubbles. These collapsing bubbles generate very high localized temperatures and pressure shockwaves along with micro-streaming that is associated with high shear forces. These effects can be used to accelerate the transport of substrates and reaction products to and from enzymes, and to enhance mass transfer in enzyme reactor systems, and thus improve efficiency. However, the high velocity streaming, together with the formation of hydroxy radicals and heat generation during collapsing of bubbles, may also potentially affect the biocatalyst stability, and this can be a limiting factor in combined ultrasound/enzymatic applications. Typically, enzymes can be readily denatured by slight changes in environmental conditions, including temperature, pressure, shear stress, pH and ionic strength.

A class of exact solutions for biomacromolecule diffusion-reaction in live cells.

PubMed

Sadegh Zadeh, Kouroush; Montas, Hubert J

2010-06-07

A class of novel explicit analytic solutions for a system of n+1 coupled partial differential equations governing biomolecular mass transfer and reaction in living organisms are proposed, evaluated, and analyzed. The solution process uses Laplace and Hankel transforms and results in a recursive convolution of an exponentially scaled Gaussian with modified Bessel functions. The solution is developed for wide range of biomolecular binding kinetics from pure diffusion to multiple binding reactions. The proposed approach provides solutions for both Dirac and Gaussian laser beam (or fluorescence-labeled biomacromolecule) profiles during the course of a Fluorescence Recovery After Photobleaching (FRAP) experiment. We demonstrate that previous models are simplified forms of our theory for special cases. Model analysis indicates that at the early stages of the transport process, biomolecular dynamics is governed by pure diffusion. At large times, the dominant mass transfer process is effective diffusion. Analysis of the sensitivity equations, derived analytically and verified by finite difference differentiation, indicates that experimental biologists should use full space-time profile (instead of the averaged time series) obtained at the early stages of the fluorescence microscopy experiments to extract meaningful physiological information from the protocol. Such a small time frame requires improved bioinstrumentation relative to that in use today. Our mathematical analysis highlights several limitations of the FRAP protocol and provides strategies to improve it. The proposed model can be used to study biomolecular dynamics in molecular biology, targeted drug delivery in normal and cancerous tissues, motor-driven axonal transport in normal and abnormal nervous systems, kinetics of diffusion-controlled reactions between enzyme and substrate, and to validate numerical simulators of biological mass transport processes in vivo. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Facilitated release of substrate protein from prefoldin by chaperonin.

PubMed

Zako, Tamotsu; Iizuka, Ryo; Okochi, Mina; Nomura, Tomoko; Ueno, Taro; Tadakuma, Hisashi; Yohda, Masafumi; Funatsu, Takashi

2005-07-04

Prefoldin is a chaperone that captures a protein-folding intermediate and transfers it to the group II chaperonin for correct folding. However, kinetics of interactions between prefoldin and substrate proteins have not been investigated. In this study, dissociation constants and dissociation rate constants of unfolded proteins with prefoldin were firstly measured using fluorescence microscopy. Our results suggest that binding and release of prefoldin from hyperthermophilic archaea with substrate proteins were in a dynamic equilibrium. Interestingly, the release of substrate proteins from prefoldin was facilitated when chaperonin was present, supporting a handoff mechanism of substrate proteins from prefoldin to the chaperonin.

Device for thermal transfer and power generation

DOEpatents

Weaver, Stanton Earl [Northville, NY; Arik, Mehmet [Niskayuna, NY

2011-04-19

A system is provided. The system includes a device that includes top and bottom thermally conductive substrates positioned opposite to one another, wherein a top surface of the bottom thermally conductive substrate is substantially atomically flat and a thermal blocking layer disposed between the top and bottom thermally conductive substrates. The device also includes top and bottom electrodes separated from one another between the top and bottom thermally conductive substrates to define a tunneling path, wherein the top electrode is disposed on the thermal blocking layer and the bottom electrode is disposed on the bottom thermally conductive substrate.

Transfer-free, lithography-free and fast growth of patterned CVD graphene directly on insulators by using sacrificial metal catalyst.

PubMed

Dong, Yibo; Xie, Yiyang; Xu, Chen; Fu, Yafei; Fan, Xing; Li, Xuejian; Wang, Le; Xiong, Fangzhu; Guo, Weiling; Pan, Guanzhong; Wang, Qiuhua; Qian, Fengsong; Sun, Jie

2018-06-14

Chemical vapor deposited graphene suffers from two problems: transfer from metal catalysts to insulators, and photoresist induced degradation during patterning. Both result in macroscopic and microscopic damages such as holes, tears, doping, and contamination, translated into property and yield dropping. We attempt to solve the problems simultaneously. A nickel thin film is evaporated on SiO 2 as a sacrificial catalyst, on which surface graphene is grown. A polymer (PMMA) support is spin-coated on the graphene. During the Ni wet etching process, the etchant can permeate the polymer, making the etching efficient. The PMMA/graphene layer is fixed on the substrate by controlling the surface morphology of Ni film during the graphene growth. After etching, the graphene naturally adheres to the insulating substrate. By using this method, transfer-free, lithography-free and fast growth of graphene realized. The whole experiment has good repeatability and controllability. Compared with graphene transfer between substrates, here, no mechanical manipulation is required, leading to minimal damage. Due to the presence of Ni, the graphene quality is intrinsically better than catalyst-free growth. The Ni thickness and growth temperature are controlled to limit the number of layers of graphene. The technology can be extended to grow other two-dimensional materials with other catalysts.

Near-perfect broadband absorption from hyperbolic metamaterial nanoparticles

NASA Astrophysics Data System (ADS)

Riley, Conor T.; Smalley, Joseph S. T.; Brodie, Jeffrey R. J.; Fainman, Yeshaiahu; Sirbuly, Donald J.; Liu, Zhaowei

2017-02-01

Broadband absorbers are essential components of many light detection, energy harvesting, and camouflage schemes. Current designs are either bulky or use planar films that cause problems in cracking and delamination during flexing or heating. In addition, transferring planar materials to flexible, thin, or low-cost substrates poses a significant challenge. On the other hand, particle-based materials are highly flexible and can be transferred and assembled onto a more desirable substrate but have not shown high performance as an absorber in a standalone system. Here, we introduce a class of particle absorbers called transferable hyperbolic metamaterial particles (THMMP) that display selective, omnidirectional, tunable, broadband absorption when closely packed. This is demonstrated with vertically aligned hyperbolic nanotube (HNT) arrays composed of alternating layers of aluminum-doped zinc oxide and zinc oxide. The broadband absorption measures >87% from 1,200 nm to over 2,200 nm with a maximum absorption of 98.1% at 1,550 nm and remains large for high angles. Furthermore, we show the advantages of particle-based absorbers by transferring the HNTs to a polymer substrate that shows excellent mechanical flexibility and visible transparency while maintaining near-perfect absorption in the telecommunications region. In addition, other material systems and geometries are proposed for a wider range of applications.

"Self-Peel-Off" Transfer Produces Ultrathin Polyvinylidene-Fluoride-Based Flexible Nanodevices.

PubMed

Tai, Yanlong; Lubineau, Gilles

2017-04-01

Here, a new strategy, self-peel-off transfer, for the preparation of ultrathin flexible nanodevices made from polyvinylidene-fluoride (PVDF) is reported. In this process, a functional pattern of nanoparticles is transferred via peeling from a temporary substrate to the final PVDF film. This peeling process takes advantage of the differences in the work of adhesion between the various layers (the PVDF layer, the nanoparticle-pattern layer and the substrate layer) and of the high stresses generated by the differential thermal expansion of the layers. The work of adhesion is mainly guided by the basic physical/chemical properties of these layers and is highly sensitive to variations in temperature and moisture in the environment. The peeling technique is tested on a variety of PVDF-based functional films using gold/palladium nanoparticles, carbon nanotubes, graphene oxide, and lithium iron phosphate. Several PVDF-based flexible nanodevices are prepared, including a single-sided wireless flexible humidity sensor in which PVDF is used as the substrate and a double-sided flexible capacitor in which PVDF is used as the ferroelectric layer and the carrier layer. Results show that the nanodevices perform with high repeatability and stability. Self-peel-off transfer is a viable preparation strategy for the design and fabrication of flexible, ultrathin, and light-weight nanodevices.

Maskless deposition technique for the physical vapor deposition of thin film and multilayer coatings with subnanometer precision and accuracy

DOEpatents

Vernon, Stephen P.; Ceglio, Natale M.

2000-01-01

The invention is a method for the production of axially symmetric, graded and ungraded thickness thin film and multilayer coatings that avoids the use of apertures or masks to tailor the deposition profile. A motional averaging scheme permits the deposition of uniform thickness coatings independent of the substrate radius. Coating uniformity results from an exact cancellation of substrate radius dependent terms, which occurs when the substrate moves at constant velocity. If the substrate is allowed to accelerate over the source, arbitrary coating profiles can be generated through appropriate selection and control of the substrate center of mass equation of motion. The radial symmetry of the coating profile is an artifact produced by orbiting the substrate about its center of mass; other distributions are obtained by selecting another rotation axis. Consequently there is a direct mapping between the coating thickness and substrate equation of motion which can be used to tailor the coating profile without the use of masks and apertures.

Determination of hydride transfer stereospecificity of NADH-dependent alcohol-aldehyde/ketone oxidoreductase from Sulfolobus solfataricus.

PubMed

Trincone, A; Lama, L; Rella, R; D'Auria, S; Raia, C A; Nicolaus, B

1990-10-18

This paper describes the determination of stereospecificity of hydride transfer reaction of an alcohol dehydrogenase isolated from the archaebacterium Sulfolobus solfataricus. The 1H-NMR and EI-MS data indicate that the enzyme transfers the pro-R hydrogen from coenzyme to substrate and is therefore an A-specific dehydrogenase.

Non-viral gene delivery regulated by stiffness of cell adhesion substrates.

PubMed

Kong, Hyun Joon; Liu, Jodi; Riddle, Kathryn; Matsumoto, Takuya; Leach, Kent; Mooney, David J

2005-06-01

Non-viral gene vectors are commonly used for gene therapy owing to safety concerns with viral vectors. However, non-viral vectors are plagued by low levels of gene transfection and cellular expression. Current efforts to improve the efficiency of non-viral gene delivery are focused on manipulations of the delivery vector, whereas the influence of the cellular environment in DNA uptake is often ignored. The mechanical properties (for example, rigidity) of the substrate to which a cell adheres have been found to mediate many aspects of cell function including proliferation, migration and differentiation, and this suggests that the mechanics of the adhesion substrate may regulate a cell's ability to uptake exogeneous signalling molecules. In this report, we present a critical role for the rigidity of the cell adhesion substrate on the level of gene transfer and expression. The mechanism relates to material control over cell proliferation, and was investigated using a fluorescent resonance energy transfer (FRET) technique. This study provides a new material-based control point for non-viral gene therapy.

Template-Stripped Tunable Plasmonic Devices on Stretchable and Rollable Substrates

PubMed Central

2015-01-01

We use template stripping to integrate metallic nanostructures onto flexible, stretchable, and rollable substrates. Using this approach, high-quality patterned metals that are replicated from reusable silicon templates can be directly transferred to polydimethylsiloxane (PDMS) substrates. First we produce stretchable gold nanohole arrays and show that their optical transmission spectra can be modulated by mechanical stretching. Next we fabricate stretchable arrays of gold pyramids and demonstrate a modulation of the wavelength of light resonantly scattered from the tip of the pyramid by stretching the underlying PDMS film. The use of a flexible transfer layer also enables template stripping using a cylindrical roller as a substrate. As an example, we demonstrate roller template stripping of metallic nanoholes, nanodisks, wires, and pyramids onto the cylindrical surface of a glass rod lens. These nonplanar metallic structures produced via template stripping with flexible and stretchable films can facilitate many applications in sensing, display, plasmonics, metasurfaces, and roll-to-roll fabrication. PMID:26402066

Spin mixing at level anti-crossings in the rotating frame makes high-field SABRE feasible.

PubMed

Pravdivtsev, Andrey N; Yurkovskaya, Alexandra V; Vieth, Hans-Martin; Ivanov, Konstantin L

2014-12-07

A new technique is proposed to carry out Signal Amplification By Reversible Exchange (SABRE) experiments at high magnetic fields. SABRE is a method, which utilizes spin order transfer from para-hydrogen to the spins of a substrate in transient complexes using suitable catalysts. Such a transfer of spin order is efficient at low magnetic fields, notably, in the Level Anti-Crossing (LAC) regions. Here it is demonstrated that LAC conditions can also be fulfilled at high fields in the rotating reference frame under the action of an RF-field. Spin mixing at LACs allows one to polarize substrates at high fields as well; the achievable NMR enhancements are around 360 for the ortho-protons of partially deuterated pyridine used as a substrate and around 700 for H2 and substrate in the active complex with the catalyst. High-field SABRE effects have also been found for several other molecules containing a nitrogen atom in the aromatic ring.

Modification of (137)Cs transfer to rape (Brassica napus L.) phytomass under the influence of soil microorganisms.

PubMed

Pareniuk, O; Shavanova, K; Laceby, J P; Illienko, V; Tytova, L; Levchuk, S; Gudkov, I; Nanba, K

2015-11-01

After nuclear accidents, such as those experienced in Chernobyl and Fukushima, microorganisms may help purify contaminated soils by changing the mobility of radionuclides and their availability for plants by altering the physical and chemical properties of the substrate. Here, using model experiments with quartz sand as a substrate we investigate the influence of microorganisms on (137)Cs transfer from substrate to plants. The highest transition of (137)Cs from substrate to plants (50% increase compared to the control) was observed after Brassica napus L. seeds were inoculated by Azotobacter chroococcum. The best results for reducing the accumulation of (137)Cs radionuclides (30% less) were noted after the inoculation by Burkholderia sp.. Furthermore, Bacillus megaterium demonstrated an increased ability to accumulate (137)Cs. This research improves our prediction of the behavior of radionuclides in soil and may contribute towards new, microbiological countermeasures for soil remediation following nuclear accidents. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of tip-substrate gap, deposition temperature, holding time, and pull-off velocity on dip-pen lithography investigated using molecular dynamics simulation

NASA Astrophysics Data System (ADS)

Wu, Cheng-Da; Fang, Te-Hua; Lin, Jen-Fin

2012-05-01

The process parameters in the dip-pen nanolithography process, including tip-substrate gap, deposition temperature, holding time, and pull-off velocity are evaluated in terms of the mechanism of molecular transference, alkanethiol meniscus characteristic, surface adsorbed energy, and pattern formation using molecular dynamics simulations. The simulation results clearly show that the optimum deposition occurs at a smaller tip-substrate gap, a slower pull-off velocity, a higher temperature, and a longer holding time. The pattern area increases with decreasing tip-substrate gap and increasing deposition temperature and holding time. With an increase in deposition temperature, the molecular transfer ability significantly increases. Pattern height is a function of meniscus length. When the pull-off velocity is decreased, the pattern height increases. The height of the neck in meniscus decreases and the neck width increases with holding time. Meniscus size increases with increasing deposition temperature and holding time.

Ice Generation and the Heat and Mass Transfer Phenomena of Introducing Water to a Cold Bath of Brine.

PubMed

Yun, Xiao; Quarini, Giuseppe L

2017-03-13

We demonstrate a method for the study of the heat and mass transfer and of the freezing phenomena in a subcooled brine environment. Our experiment showed that, under the proper conditions, ice can be produced when water is introduced to a bath of cold brine. To make ice form, in addition to having the brine and water mix, the rate of heat transfer must bypass that of mass transfer. When water is introduced in the form of tiny droplets to the brine surface, the mode of heat and mass transfer is by diffusion. The buoyancy stops water from mixing with the brine underneath, but as the ice grows thicker, it slows down the rate of heat transfer, making ice more difficult to grow as a result. When water is introduced inside the brine in the form of a flow, a number of factors are found to influence how much ice can form. Brine temperature and concentration, which are the driving forces of heat and mass transfer, respectively, can affect the water-to-ice conversion ratio; lower bath temperatures and brine concentrations encourage more ice to form. The flow rheology, which can directly affect both the heat and mass transfer coefficients, is also a key factor. In addition, the flow rheology changes the area of contact of the flow with the bulk fluid.

Discrete multi-physics simulations of diffusive and convective mass transfer in boundary layers containing motile cilia in lungs.

PubMed

Ariane, Mostapha; Kassinos, Stavros; Velaga, Sitaram; Alexiadis, Alessio

2018-04-01

In this paper, the mass transfer coefficient (permeability) of boundary layers containing motile cilia is investigated by means of discrete multi-physics. The idea is to understand the main mechanisms of mass transport occurring in a ciliated-layer; one specific application being inhaled drugs in the respiratory epithelium. The effect of drug diffusivity, cilia beat frequency and cilia flexibility is studied. Our results show the existence of three mass transfer regimes. A low frequency regime, which we called shielding regime, where the presence of the cilia hinders mass transport; an intermediate frequency regime, which we have called diffusive regime, where diffusion is the controlling mechanism; and a high frequency regime, which we have called convective regime, where the degree of bending of the cilia seems to be the most important factor controlling mass transfer in the ciliated-layer. Since the flexibility of the cilia and the frequency of the beat changes with age and health conditions, the knowledge of these three regimes allows prediction of how mass transfer varies with these factors. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effect of soil type and exposure duration on mortality and transfer of chlorantraniliprole and fipronil on Formosan subterranean termites (Isoptera: Rhinotermitidae).

PubMed

Gautam, Bal K; Henderson, Gregg

2011-12-01

The uptake and potential transfer of chlorantraniliprole and fipronil by the Formosan subterranean termite, Coptotermes formosanus Shiraki, was investigated in the laboratory by using donor-recipient model bioassays. Two different types of substrates, sandy loam soil (18.6% organic matter) and sand (0.19% organic matter), were used to evaluate how these treated substrates impact the direct mortality and transfer efficiency of the two nonrepellent termiticides tested at different concentrations. Chlorantraniliprole exhibited a more delayed mortality on termites than fipronil in sand. In soil, chlorantraniliprole did not cause higher mortality to either donor or recipient termite at any of the tested concentrations during a 21-d test period when compared with controls. Compared with the controls, a greater number of donors died in the soil treated with fipronil at 14 h postinteraction, and higher death of recipients occurred at 21 d but only in the 60-ppm concentration tested. Our data showed that chlorantraniliprole performed best in substrate with low organic matter against

User's manual for the one-dimensional hypersonic experimental aero-thermodynamic (1DHEAT) data reduction code

NASA Technical Reports Server (NTRS)

Hollis, Brian R.

1995-01-01

A FORTRAN computer code for the reduction and analysis of experimental heat transfer data has been developed. This code can be utilized to determine heat transfer rates from surface temperature measurements made using either thin-film resistance gages or coaxial surface thermocouples. Both an analytical and a numerical finite-volume heat transfer model are implemented in this code. The analytical solution is based on a one-dimensional, semi-infinite wall thickness model with the approximation of constant substrate thermal properties, which is empirically corrected for the effects of variable thermal properties. The finite-volume solution is based on a one-dimensional, implicit discretization. The finite-volume model directly incorporates the effects of variable substrate thermal properties and does not require the semi-finite wall thickness approximation used in the analytical model. This model also includes the option of a multiple-layer substrate. Fast, accurate results can be obtained using either method. This code has been used to reduce several sets of aerodynamic heating data, of which samples are included in this report.

Shift in Mass Transfer of Wastewater Contaminants from Microplastics in the Presence of Dissolved Substances.

PubMed

Seidensticker, Sven; Zarfl, Christiane; Cirpka, Olaf A; Fellenberg, Greta; Grathwohl, Peter

2017-11-07

In aqueous environments, hydrophobic organic contaminants are often associated with particles. Besides natural particles, microplastics have raised public concern. The release of pollutants from such particles depends on mass transfer, either in an aqueous boundary layer or by intraparticle diffusion. Which of these mechanisms controls the mass-transfer kinetics depends on partition coefficients, particle size, boundary conditions, and time. We have developed a semianalytical model accounting for both processes and performed batch experiments on the desorption kinetics of typical wastewater pollutants (phenanthrene, tonalide, and benzophenone) at different dissolved-organic-matter concentrations, which change the overall partitioning between microplastics and water. Initially, mass transfer is externally dominated, while finally, intraparticle diffusion controls release kinetics. Under boundary conditions typical for batch experiments (finite bath), desorption accelerates with increasing partition coefficients for intraparticle diffusion, while it becomes independent of partition coefficients if film diffusion prevails. On the contrary, under field conditions (infinite bath), the pollutant release controlled by intraparticle diffusion is not affected by partitioning of the compound while external mass transfer slows down with increasing sorption. Our results clearly demonstrate that sorption/desorption time scales observed in batch experiments may not be transferred to field conditions without an appropriate model accounting for both the mass-transfer mechanisms and the specific boundary conditions at hand.

On the importance of the heat and mass transfer resistances in internally-cooled liquid desiccant dehumidifiers and regenerators

DOE PAGES

Woods, Jason; Kozubal, Eric

2018-02-06

Liquid desiccant heat and mass exchangers are a promising technology for efficient humidity control in buildings. Many researchers have investigated these exchangers, often using numerical models to predict their performance. However, there is a lack of information in the literature on the magnitude of the heat and mass transfer resistances, both for the dehumidifier (which absorbs moisture from the air) and the regenerator (which heats the liquid desiccant to re-concentrate it). This article focuses on internally-cooled, 3-fluid exchangers in a parallel plate geometry. Water heats or cools a desiccant across a plate, and the desiccant absorbs or releases water intomore » an airstream through a membrane. A sensitivity analysis was used to estimate the importance of each of the heat and mass transfer resistances (air, membrane, desiccant, plate, water), and how it changes with different design geometries. The results show that, for most designs, the latent and sensible heat transfer of the dehumidifier is dominated by the air mass transfer resistance and air heat transfer resistance, respectively. The air mass transfer resistance is also important for the regenerator, but much less so; the change in the desiccant equilibrium humidity ratio due to a change in either temperature or desiccant mass fraction is much higher at the regenerator's higher temperatures. This increases the importance of (1) getting heat from the water to the desiccant/membrane interface, and (2) diffusing salt ions quickly away from the desiccant/membrane interface. The membrane heat transfer and water heat transfer resistances were found to be the least important. These results can help inform decisions about what simplifying assumptions to make in numerical models, and can also help in designing these exchangers by understanding which resistances are most important.« less

On the importance of the heat and mass transfer resistances in internally-cooled liquid desiccant dehumidifiers and regenerators

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

Woods, Jason; Kozubal, Eric

Liquid desiccant heat and mass exchangers are a promising technology for efficient humidity control in buildings. Many researchers have investigated these exchangers, often using numerical models to predict their performance. However, there is a lack of information in the literature on the magnitude of the heat and mass transfer resistances, both for the dehumidifier (which absorbs moisture from the air) and the regenerator (which heats the liquid desiccant to re-concentrate it). This article focuses on internally-cooled, 3-fluid exchangers in a parallel plate geometry. Water heats or cools a desiccant across a plate, and the desiccant absorbs or releases water intomore » an airstream through a membrane. A sensitivity analysis was used to estimate the importance of each of the heat and mass transfer resistances (air, membrane, desiccant, plate, water), and how it changes with different design geometries. The results show that, for most designs, the latent and sensible heat transfer of the dehumidifier is dominated by the air mass transfer resistance and air heat transfer resistance, respectively. The air mass transfer resistance is also important for the regenerator, but much less so; the change in the desiccant equilibrium humidity ratio due to a change in either temperature or desiccant mass fraction is much higher at the regenerator's higher temperatures. This increases the importance of (1) getting heat from the water to the desiccant/membrane interface, and (2) diffusing salt ions quickly away from the desiccant/membrane interface. The membrane heat transfer and water heat transfer resistances were found to be the least important. These results can help inform decisions about what simplifying assumptions to make in numerical models, and can also help in designing these exchangers by understanding which resistances are most important.« less

Effects of heat and mass transfer on unsteady boundary layer flow of a chemical reacting Casson fluid

NASA Astrophysics Data System (ADS)

Khan, Kashif Ali; Butt, Asma Rashid; Raza, Nauman

2018-03-01

In this study, an endeavor is to observe the unsteady two-dimensional boundary layer flow with heat and mass transfer behavior of Casson fluid past a stretching sheet in presence of wall mass transfer by ignoring the effects of viscous dissipation. Chemical reaction of linear order is also invoked here. Similarity transformation have been applied to reduce the governing equations of momentum, energy and mass into non-linear ordinary differential equations; then Homotopy analysis method (HAM) is applied to solve these equations. Numerical work is done carefully with a well-known software MATHEMATICA for the examination of non-dimensional velocity, temperature, and concentration profiles, and then results are presented graphically. The skin friction (viscous drag), local Nusselt number (rate of heat transfer) and Sherwood number (rate of mass transfer) are discussed and presented in tabular form for several factors which are monitoring the flow model.

Improving mass transfer to soften tissues by pulsed electric fields: fundamentals and applications.

PubMed

Puértolas, E; Luengo, E; Álvarez, I; Raso, J

2012-01-01

The mass transfer phenomenon occurs in many operations of the food industry with the purpose of obtaining a given substance of interest, removing water from foods, or introducing a given substance into the food matrix. Pretreatments that modify the permeability of the cell membranes, such as grinding, heating, or enzymatic treatment, enhance the mass transfer. However, these techniques may require a significant amount of energy and can cause losses of valuable food compounds. Pulsed electric field (PEF) technology is a nonthermal processing method that causes permeabilization of cell membranes using low energy requirements and minimizing quality deterioration of the food compounds. Many practical applications of PEF for enhancing mass transfer in the food industry have been investigated. The purpose of this chapter is to give an overview of the state of the art of application of PEF for improving mass transfer in the food industry.

Secondary ion emission from arachidic acid LB-layers under Ar +, Xe +, Ga + and SF 5+ primary ion bombardment

NASA Astrophysics Data System (ADS)

Stapel, D.; Brox, O.; Benninghoven, A.

1999-02-01

The influence of primary ion energy, mass and composition on sputtering and secondary ion emission of arachidic acid Langmuir-Blodgett mono- and multilayers, deposited on gold substrates, has been investigated. Ga +, Ar +, 129Xe+ and SF 5+ in the energy range 5-25 keV were used as primary ions. Yields Y, damage cross-sections σ, and ion formation efficiencies E have been determined for selected secondary ions, characterizing the molecular overlayer, the overlayer substrate interface and the substrate. We found a strong influence of layer thickness and of primary ion energy, mass and composition on Y, σ and E. Information depth increases with increasing ion energy and decreasing mass of primary ions, being higher for SF 5+ than for Xe +. Y, σ and E increase with increasing primary ion mass. They are considerably higher for a molecular (SF 5+) than for atomic ions of comparable mass ( 129Xe+). The experimental results supply information on the extension of impact cascades, generated in different substrate materials by different primary ion species and different energies. They demonstrate that in analytical SIMS application information depths can be minimized and yields and ion formation efficiencies can be maximized by the use of molecular primary ions.

Enhancing SERS by Means of Supramolecular Charge Transfer

NASA Technical Reports Server (NTRS)

Wong, Eric; Flood, Amar; Morales, Alfredo

2009-01-01

In a proposed method of sensing small quantities of molecules of interest, surface enhanced Raman scattering (SERS) spectroscopy would be further enhanced by means of intermolecular or supramolecular charge transfer. There is a very large potential market for sensors based on this method for rapid detection of chemical and biological hazards. In SERS, the Raman signals (vibrational spectra) of target molecules become enhanced by factors of the order of 108 when those molecules are in the vicinities of nanostructured substrate surfaces that have been engineered to have plasmon resonances that enhance local electric fields. SERS, as reported in several prior NASA Tech Briefs articles and elsewhere, has remained a research tool and has not yet been developed into a practical technique for sensing of target molecules: this is because the short range (5 to 20 nm) of the field enhancement necessitates engineering of receptor molecules to attract target molecules to the nanostructured substrate surfaces and to enable reliable identification of the target molecules in the presence of interferants. Intermolecular charge-transfer complexes have been used in fluorescence-, photoluminescence-, and electrochemistry-based techniques for sensing target molecules, but, until now, have not been considered for use in SERS-based sensing. The basic idea of the proposed method is to engineer receptor molecules that would be attached to nanostructured SERS substrates and that would interact with the target molecules to form receptor-target supramolecular charge-transfer complexes wherein the charge transfer could be photoexcited.

Dual-mass vibratory rate gyroscope with suppressed translational acceleration response and quadrature-error correction capability

NASA Technical Reports Server (NTRS)

Clark, William A. (Inventor); Juneau, Thor N. (Inventor); Lemkin, Mark A. (Inventor); Roessig, Allen W. (Inventor)

2001-01-01

A microfabricated vibratory rate gyroscope to measure rotation includes two proof-masses mounted in a suspension system anchored to a substrate. The suspension has two principal modes of compliance, one of which is driven into oscillation. The driven oscillation combined with rotation of the substrate about an axis perpendicular to the substrate results in Coriolis acceleration along the other mode of compliance, the sense-mode. The sense-mode is designed to respond to Coriolis accelerationwhile suppressing the response to translational acceleration. This is accomplished using one or more rigid levers connecting the two proof-masses. The lever allows the proof-masses to move in opposite directions in response to Coriolis acceleration. The invention includes a means for canceling errors, termed quadrature error, due to imperfections in implementation of the sensor. Quadrature-error cancellation utilizes electrostatic forces to cancel out undesired sense-axis motion in phase with drive-mode position.

Water Activated Graphene Oxide Transfer Using Wax Printed Membranes for Fast Patterning of a Touch Sensitive Device.

PubMed

Baptista-Pires, Luis; Mayorga-Martínez, Carmen C; Medina-Sánchez, Mariana; Montón, Helena; Merkoçi, Arben

2016-01-26

We demonstrate a graphene oxide printing technology using wax printed membranes for the fast patterning and water activation transfer using pressure based mechanisms. The wax printed membranes have 50 μm resolution, longtime stability and infinite shaping capability. The use of these membranes complemented with the vacuum filtration of graphene oxide provides the control over the thickness. Our demonstration provides a solvent free methodology for printing graphene oxide devices in all shapes and all substrates using the roll-to-roll automatized mechanism present in the wax printing machine. Graphene oxide was transferred over a wide variety of substrates as textile or PET in between others. Finally, we developed a touch switch sensing device integrated in a LED electronic circuit.

Substrate-bound Crystal Structures Reveal Features Unique to Mycobacterium tuberculosis N-Acetyl-glucosamine 1-Phosphate Uridyltransferase and a Catalytic Mechanism for Acetyl Transfer

PubMed Central

Jagtap, Pravin Kumar Ankush; Soni, Vijay; Vithani, Neha; Jhingan, Gagan Deep; Bais, Vaibhav Singh; Nandicoori, Vinay Kumar; Prakash, Balaji

2012-01-01

N-Acetyl-glucosamine-1-phosphate uridyltransferase (GlmU), a bifunctional enzyme involved in bacterial cell wall synthesis is exclusive to prokaryotes. GlmU, now recognized as a promising target to develop new antibacterial drugs, catalyzes two key reactions: acetyl transfer and uridyl transfer at two independent domains. Hitherto, we identified GlmU from Mycobacterium tuberculosis (GlmUMtb) to be unique in possessing a 30-residue extension at the C terminus. Here, we present the crystal structures of GlmUMtb in complex with substrates/products bound at the acetyltransferase active site. Analysis of these and mutational data, allow us to infer a catalytic mechanism operative in GlmUMtb. In this SN2 reaction, His-374 and Asn-397 act as catalytic residues by enhancing the nucleophilicity of the attacking amino group of glucosamine 1-phosphate. Ser-416 and Trp-460 provide important interactions for substrate binding. A short helix at the C-terminal extension uniquely found in mycobacterial GlmU provides the highly conserved Trp-460 for substrate binding. Importantly, the structures reveal an uncommon mode of acetyl-CoA binding in GlmUMtb; we term this the U conformation, which is distinct from the L conformation seen in the available non-mycobacterial GlmU structures. Residues, likely determining U/L conformation, were identified, and their importance was evaluated. In addition, we identified that the primary site for PknB-mediated phosphorylation is Thr-418, near the acetyltransferase active site. Down-regulation of acetyltransferase activity upon Thr-418 phosphorylation is rationalized by the structures presented here. Overall, this work provides an insight into substrate recognition, catalytic mechanism for acetyl transfer, and features unique to GlmUMtb, which may be exploited for the development of inhibitors specific to GlmU. PMID:22969087

Interfacial and thermal energy driven growth and evolution of Langmuir-Schaefer monolayers of Au-nanoparticles.

PubMed

Mukhopadhyay, Mala; Hazra, S

2018-01-03

Structures of Langmuir-Schaefer (LS) monolayers of thiol-coated Au-nanoparticles (DT-AuNPs) deposited on H-terminated and OTS self-assembled Si substrates (of different hydrophobic strength and stability) and their evolution with time under ambient conditions, which plays an important role for their practical use as 2D-nanostructures over large areas, were investigated using the X-ray reflectivity technique. The strong effect of substrate surface energy (γ) on the initial structures and the competitive role of room temperature thermal energy (kT) and the change in interfacial energy (Δγ) at ambient conditions on the evolution and final structures of the DT-AuNP LS monolayers are evident. The strong-hydrophobic OTS-Si substrate, during transfer, seems to induce strong attraction towards hydrophobic DT-AuNPs on hydrophilic (repulsive) water to form vertically compact partially covered (with voids) monolayer structures (of perfect monolayer thickness) at low pressure and nearly covered buckled monolayer structures (of enhanced monolayer thickness) at high pressure. After transfer, the small kT-energy (in absence of repulsive water) probably fluctuates the DT-AuNPs to form vertically expanded monolayer structures, through systematic exponential growth with time. The effect is prominent for the film deposited at low pressure, where the initial film-coverage and film-thickness are low. On the other hand, the weak-hydrophobic H-Si substrate, during transfer, appears to induce optimum attraction towards DT-AuNPs to better mimic the Langmuir monolayer structures on it. After transfer, the change in the substrate surface nature, from weak-hydrophobic to weak-hydrophilic with time (i.e. Δγ-energy, apart from the kT-energy), enhances the size of the voids and weakens the monolayer/bilayer structure to form a similar expanded monolayer structure, the thickness of which is probably optimized by the available thermal energy.

Beyond the standard two-film theory: Computational fluid dynamics simulations for carbon dioxide capture in a wetted wall column

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

Wang, Chao; Xu, Zhijie; Lai, Canhai

The standard two-film theory (STFT) is a diffusion-based mechanism that can be used to describe gas mass transfer across liquid film. Fundamental assumptions of the STFT impose serious limitations on its ability to predict mass transfer coefficients. To better understand gas absorption across liquid film in practical situations, a multiphase computational fluid dynamics (CFD) model fully equipped with mass transport and chemistry capabilities has been developed for solvent-based carbon dioxide (CO2) capture to predict the CO2 mass transfer coefficient in a wetted wall column. The hydrodynamics is modeled using a volume of fluid method, and the diffusive and reactive massmore » transfer between the two phases is modeled by adopting a one-fluid formulation. We demonstrate that the proposed CFD model can naturally account for the influence of many important factors on the overall mass transfer that cannot be quantitatively explained by the STFT, such as the local variation in fluid velocities and properties, flow instabilities, and complex geometries. The CFD model also can predict the local mass transfer coefficient variation along the column height, which the STFT typically does not consider.« less

Effect of Schmidt number on mass transfer across a sheared gas-liquid interface in a wind-driven turbulence.

PubMed

Takagaki, Naohisa; Kurose, Ryoichi; Kimura, Atsushi; Komori, Satoru

2016-11-14

The mass transfer across a sheared gas-liquid interface strongly depends on the Schmidt number. Here we investigate the relationship between mass transfer coefficient on the liquid side, k L , and Schmidt number, Sc, in the wide range of 0.7 ≤ Sc ≤ 1000. We apply a three-dimensional semi direct numerical simulation (SEMI-DNS), in which the mass transfer is solved based on an approximated deconvolution model (ADM) scheme, to wind-driven turbulence with mass transfer across a sheared wind-driven wavy gas-liquid interface. In order to capture the deforming gas-liquid interface, an arbitrary Lagrangian-Eulerian (ALE) method is employed. Our results show that similar to the case for flat gas-liquid interfaces, k L for the wind-driven wavy gas-liquid interface is generally proportional to Sc -0.5 , and can be roughly estimated by the surface divergence model. This trend is endorsed by the fact that the mass transfer across the gas-liquid interface is controlled mainly by streamwise vortices on the liquid side even for the wind-driven turbulence under the conditions of low wind velocities without wave breaking.

Effect of Schmidt number on mass transfer across a sheared gas-liquid interface in a wind-driven turbulence

PubMed Central

Takagaki, Naohisa; Kurose, Ryoichi; Kimura, Atsushi; Komori, Satoru

2016-01-01

The mass transfer across a sheared gas-liquid interface strongly depends on the Schmidt number. Here we investigate the relationship between mass transfer coefficient on the liquid side, kL, and Schmidt number, Sc, in the wide range of 0.7 ≤ Sc ≤ 1000. We apply a three-dimensional semi direct numerical simulation (SEMI-DNS), in which the mass transfer is solved based on an approximated deconvolution model (ADM) scheme, to wind-driven turbulence with mass transfer across a sheared wind-driven wavy gas-liquid interface. In order to capture the deforming gas-liquid interface, an arbitrary Lagrangian-Eulerian (ALE) method is employed. Our results show that similar to the case for flat gas-liquid interfaces, kL for the wind-driven wavy gas-liquid interface is generally proportional to Sc−0.5, and can be roughly estimated by the surface divergence model. This trend is endorsed by the fact that the mass transfer across the gas-liquid interface is controlled mainly by streamwise vortices on the liquid side even for the wind-driven turbulence under the conditions of low wind velocities without wave breaking. PMID:27841325

Mass transfer study on the electrochemical removal of copper ions from synthetic effluents using reticulated vitreous carbon.

PubMed

Britto-Costa, Pedro H; Ruotolo, Luís Augusto M

2013-01-01

Porous electrodes have been successfully used for metal electrodeposition from diluted aqueous solution due to their high porosity and specific surface area, which lead to high mass transfer rates. This work studies the mass transfer of copper electrodeposition on reticulated vitreous carbon in a flow reactor without membrane. The flow configuration, otherwise the filter-press electrochemical reactors, was designed in order to minimize the pressure drop. The mass transfer coefficient was determined by voltammetric and galvanostatic electrodeposition. In the voltammetric experiments a Luggin capillary was used to measure the current-potential curves and to determine the limiting current (and, consequently, the mass transfer coefficient). In the galvanostatic experiments the concentration-time curves were obtained and considering a limiting current kinetics model, the mass transfer coefficient (k(m)) was determined for different flow velocities. The results showed that both methods give similar values of k(m), thus the voltammetric method can be recommended because it is faster and simpler. Finally, the reactor performance was compared with others from literature, and it was observed that the proposed reactor design has high Sherwood numbers similar to other reactor configurations using membranes and reticulated vitreous carbon electrodes.

Convection Heat and Mass Transfer in a Power Law Fluid with Non Constant Relaxation Time Past a Vertical Porous Plate in the Presence of Thermo and Thermal Diffusion

NASA Astrophysics Data System (ADS)

Olajuwon, B. I.; Oyelakin, I. S.

2012-12-01

The paper investigates convection heat and mass transfer in power law fluid flow with non relaxation time past a vertical porous plate in presence of a chemical reaction, heat generation, thermo diffu- sion and thermal diffusion. The non - linear partial differential equations governing the flow are transformed into ordinary differential equations using the usual similarity method. The resulting similarity equations are solved numerically using Runge-Kutta shooting method. The results are presented as velocity, temperature and concentration profiles for pseudo plastic fluids and for different values of parameters governing the prob- lem. The skin friction, heat transfer and mass transfer rates are presented numerically in tabular form. The results show that these parameters have significant effects on the flow, heat transfer and mass transfer.

Method of forming crystalline silicon devices on glass

DOEpatents

McCarthy, Anthony M.

1995-01-01

A method for fabricating single-crystal silicon microelectronic components on a silicon substrate and transferring same to a glass substrate. This is achieved by utilizing conventional silicon processing techniques for fabricating components of electronic circuits and devices on bulk silicon, wherein a bulk silicon surface is prepared with epitaxial layers prior to the conventional processing. The silicon substrate is bonded to a glass substrate and the bulk silicon is removed leaving the components intact on the glass substrate surface. Subsequent standard processing completes the device and circuit manufacturing. This invention is useful in applications requiring a transparent or insulating substrate, particularly for display manufacturing. Other applications include sensors, actuators, optoelectronics, radiation hard electronics, and high temperature electronics.

Boiling Heat Transfer Mechanisms in Earth and Low Gravity: Boundary Condition and Heater Aspect Ratio Effects

NASA Technical Reports Server (NTRS)

Kim, Jungho

2004-01-01

Boiling is a complex phenomenon where hydrodynamics, heat transfer, mass transfer, and interfacial phenomena are tightly interwoven. An understanding of boiling and critical heat flux in microgravity environments is of importance to space based hardware and processes such as heat exchange, cryogenic fuel storage and transportation, electronic cooling, and material processing due to the large amounts of heat that can be removed with relatively little increase in temperature. Although research in this area has been performed in the past four decades, the mechanisms by which heat is removed from surfaces in microgravity are still unclear. Recently, time and space resolved heat transfer data were obtained in both earth and low gravity environments using an array of microheaters varying in size between 100 microns to 700 microns. These heaters were operated in both constant temperature as well as constant heat flux mode. Heat transfer under nucleating bubbles in earth gravity were directly measured using a microheater array with 100 m resolution operated in constant temperature mode with low and high subcooled bulk liquid along with images from below and from the side. The individual bubble departure diameter and energy transfer were larger with low subcooling but the departure frequency increased at high subcooling, resulting in higher overall heat transfer. The bubble growth for both subcoolings was primarily due to energy transfer from the superheated liquid layer relatively little was due to wall heat transfer during the bubble growth process. Oscillating bubbles and sliding bubbles were also observed in highly subcooled boiling. Transient conduction and/or microconvection was the dominant heat transfer mechanism in the above cases. A transient conduction model was developed and compared with the experimental data with good agreement. Data was also obtained with the heater array operated in a constant heat flux mode and measuring the temperature distribution across the array during boiling. The instantaneous heat transfer into the substrate was numerically determined and subtracted from the supplied heat to obtain the wall to liquid heat flux.

Lipases Immobilization for Effective Synthesis of Biodiesel Starting from Coffee Waste Oils

PubMed Central

Ferrario, Valerio; Veny, Harumi; De Angelis, Elisabetta; Navarini, Luciano; Ebert, Cynthia; Gardossi, Lucia

2013-01-01

Immobilized lipases were applied to the enzymatic conversion of oils from spent coffee ground into biodiesel. Two lipases were selected for the study because of their conformational behavior analysed by Molecular Dynamics (MD) simulations taking into account that immobilization conditions affect conformational behavior of the lipases and ultimately, their efficiency upon immobilization. The enzymatic synthesis of biodiesel was initially carried out on a model substrate (triolein) in order to select the most promising immobilized biocatalysts. The results indicate that oils can be converted quantitatively within hours. The role of the nature of the immobilization support emerged as a key factor affecting reaction rate, most probably because of partition and mass transfer barriers occurring with hydrophilic solid supports. Finally, oil from spent coffee ground was transformed into biodiesel with yields ranging from 55% to 72%. The synthesis is of particular interest in the perspective of developing sustainable processes for the production of bio-fuels from food wastes and renewable materials. The enzymatic synthesis of biodiesel is carried out under mild conditions, with stoichiometric amounts of substrates (oil and methanol) and the removal of free fatty acids is not required. PMID:24970178

Lipases immobilization for effective synthesis of biodiesel starting from coffee waste oils.

PubMed

Ferrario, Valerio; Veny, Harumi; De Angelis, Elisabetta; Navarini, Luciano; Ebert, Cynthia; Gardossi, Lucia

2013-08-13

Immobilized lipases were applied to the enzymatic conversion of oils from spent coffee ground into biodiesel. Two lipases were selected for the study because of their conformational behavior analysed by Molecular Dynamics (MD) simulations taking into account that immobilization conditions affect conformational behavior of the lipases and ultimately, their efficiency upon immobilization. The enzymatic synthesis of biodiesel was initially carried out on a model substrate (triolein) in order to select the most promising immobilized biocatalysts. The results indicate that oils can be converted quantitatively within hours. The role of the nature of the immobilization support emerged as a key factor affecting reaction rate, most probably because of partition and mass transfer barriers occurring with hydrophilic solid supports. Finally, oil from spent coffee ground was transformed into biodiesel with yields ranging from 55% to 72%. The synthesis is of particular interest in the perspective of developing sustainable processes for the production of bio-fuels from food wastes and renewable materials. The enzymatic synthesis of biodiesel is carried out under mild conditions, with stoichiometric amounts of substrates (oil and methanol) and the removal of free fatty acids is not required.

Desiccation of a pool of blood: from fluid mechanics to forensic investigations

NASA Astrophysics Data System (ADS)

Nicloux, Celine; Brutin, David

2012-11-01

The evaporation of biological fluids (with droplet configuration) has been studied since a few years due to several applications in medical fields such as medical tests, drug screening, biostabilization... The evaporation of a drop of whole blood leads to the formation of final typical pattern of cracks. Flow motion, adhesion, gelation and fracturation all occur during the evaporation of this complex matter. During the drying, a sol-gel transition develops. The evaporation of a pool of blood is studied in order to link the pattern formation and the evaporation dynamics. We intend to transfer the knowledge acquired for drops on pool to improve the forensic investigations. In this study, we focus on both pool of blood and pure water to determine the transition region from drop to pool and then to characterize the evaporation rate in the pool configuration. The spreading of blood which can be seen as a complex fluid is strongly influenced the substrate nature. The initial contact angle of blood on different substrate nature will influence the maximum thickness of the layer and then will influence the evaporation mass flux. The authors gratefully acknowledge the help and the fruitful discussions raised with A. Boccoz.

Biofiltration of gasoline and ethanol-amended gasoline vapors.

PubMed

Soares, Marlene; Woiciechowski, Adenise L; Kozliak, Evguenii I; Paca, Jan; Soccol, Carlos R

2012-01-01

Assuming the projected increase in use of ethanol as a biofuel, the current study was conducted to compare the biofiltration efficiencies for plain and 25% ethanol-containing gasoline. Two biofilters were operated in a downflow mode for 7 months, one of them being compost-based whereas the other using a synthetic packing material, granulated tire rubber, inoculated with gasoline-degrading microorganisms. Inlet concentrations measured as total hydrocarbon (TH) ranged from 1.9 to 5.8 g m(-3) at a constant empty bed retention time of 6.84 min. Contrary to the expectations based on microbiological considerations, ethanol-amended gasoline was more readily biodegraded than plain hydrocarbons, with the respective steady state elimination capacities of 26-43 and 14-18 gTH m(-3) h(-1) for the compost biofilter. The efficiency of both biofilters significantly declined upon the application of higher loads of plain gasoline, yet immediately recovering when switched back to ethanol-blended gasoline. The unexpected effect of ethanol in promoting gasoline biodegradation was explained by increasing hydrocarbon partitioning into the aqueous phase, with mass transfer being rate limiting for the bulk of components. The tire rubber biofilter, after a long acclimation, surpassed the compost biofilter in performance, presumably due to the 'buffering' effect of this packing material increasing the accessibility of gasoline hydrocarbons to the biofilm. With improved substrate mass transfer, biodegradable hydrocarbons were removed in the tire rubber biofilter's first reactor stage, with most of the remaining poorly degradable smaller-size hydrocarbons being degraded in the second stage.

Metal-Organic Framework Modified Glass Substrate for Analysis of Highly Volatile Chemical Warfare Agents by Paper Spray Mass Spectrometry.

PubMed

Dhummakupt, Elizabeth S; Carmany, Daniel O; Mach, Phillip M; Tovar, Trenton M; Ploskonka, Ann M; Demond, Paul S; DeCoste, Jared B; Glaros, Trevor

2018-03-07

Paper spray mass spectrometry has been shown to successfully analyze chemical warfare agent (CWA) simulants. However, due to the volatility differences between the simulants and real G-series (i.e., sarin, soman) CWAs, analysis from an untreated paper substrate proved difficult. To extend the analytical lifetime of these G-agents, metal-organic frameworks (MOFs) were successfully integrated onto the paper spray substrates to increase adsorption and desorption. In this study, several MOFs and nanoparticles were tested to extend the analytical lifetimes of sarin, soman, and cyclosarin on paper spray substrates. It was found that the addition of either UiO-66 or HKUST-1 to the paper substrate increased the analytical lifetime of the G-agents from less than 5 min detectability to at least 50 min.

Tuning ultrafast electron injection dynamics at organic-graphene/metal interfaces.

PubMed

Ravikumar, Abhilash; Kladnik, Gregor; Müller, Moritz; Cossaro, Albano; Bavdek, Gregor; Patera, Laerte L; Sánchez-Portal, Daniel; Venkataraman, Latha; Morgante, Alberto; Brivio, Gian Paolo; Cvetko, Dean; Fratesi, Guido

2018-05-03

We compare the ultrafast charge transfer dynamics of molecules on epitaxial graphene and bilayer graphene grown on Ni(111) interfaces through first principles calculations and X-ray resonant photoemission spectroscopy. We use 4,4'-bipyridine as a prototypical molecule for these explorations as the energy level alignment of core-excited molecular orbitals allows ultrafast injection of electrons from a substrate to a molecule on a femtosecond timescale. We show that the ultrafast injection of electrons from the substrate to the molecule is ∼4 times slower on weakly coupled bilayer graphene than on epitaxial graphene. Through our experiments and calculations, we can attribute this to a difference in the density of states close to the Fermi level between graphene and bilayer graphene. We therefore show how graphene coupling with the substrate influences charge transfer dynamics between organic molecules and graphene interfaces.

Incomplete mass transfer processes in 28Si +93Nb reaction

NASA Astrophysics Data System (ADS)

Tripathi, R.; Sodaye, S.; Ramachandran, K.; Sharma, S. K.; Pujari, P. K.

Cross sections of reaction products were measured in 28Si +93Nb reaction using recoil catcher technique involving by off-line gamma-ray spectrometry at beam energies of 105 and 155MeV. At Elab = 155MeV, the contribution from different incomplete mass transfer processes is investigated. Results of the present studies show the contribution from deep inelastic collision (DIC), massive transfer or incomplete fusion (ICF) and quasi-elastic transfer (QET). The contribution from massive transfer reactions was confirmed from the fractional yield of the reaction products in the forward catcher foil. The present results are different from those from the reactions with comparatively higher entrance channel mass asymmetry with lighter projectiles, for which dominant transfer processes are ICF and QET which involve mass transfer predominantly from projectile to target. The N/Z values of the products close to the target mass were observed to be in a wide range, starting from N/Z of the target (93Nb) and extending slightly below the N/Z of the composite system, consistent with the contribution from DIC and QET reactions. At Elab = 105MeV, a small contribution from QET was observed in addition to complete fusion.

Transfer in SLA and Creoles: The Implications of Causative Serial Verbs in the Interlanguage of Vietnamese ESL Learners

ERIC Educational Resources Information Center

Helms-Park, Rena

2003-01-01

This paper presents a study that attributes verb serialization in the interlanguage of Vietnamese-speaking ESL learners to language transfer and, furthermore, puts forward the view that such transfer bears a resemblance to substrate influence in creoles with serial verb constructions (SVCs). In a task that elicited English causatives through…

Suppression of copper thin film loss during graphene synthesis.

PubMed

Lee, Alvin L; Tao, Li; Akinwande, Deji

2015-01-28

Thin metal films can be used to catalyze the growth of nanomaterials in place of the bulk metal, while greatly reducing the amount of material used. A big drawback of copper thin films (0.5-1.5 μm thick) is that, under high temperature/vacuum synthesis, the mass loss of films severely reduces the process time due to discontinuities in the metal film, thereby limiting the time scale for controlling metal grain and film growth. In this work, we have developed a facile method, namely "covered growth" to extend the time copper thin films can be exposed to high temperature/vacuum environment for graphene synthesis. The key to preventing severe mass loss of copper film during the high temperature chemical vapor deposition (CVD) process is to have a cover piece on top of the growth substrate. This new "covered growth" method enables the high-temperature annealing of the copper film upward of 4 h with minimal mass loss, while increasing copper film grain and graphene domain size. Graphene was then successfully grown on the capped copper film with subsequent transfer for device fabrication. Device characterization indicated equivalent physical, chemical, and electrical properties to conventional CVD graphene. Our "covered growth" provides a convenient and effective solution to the mass loss issue of thin films that serve as catalysts for a variety of 2D material syntheses.

Proposed method for evaluating the effects of PCBs in sediment on egg mass viability and reproductive success in frogs

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

Schmidt, C.S.; Henning, M.H.; Ebert, E.S.

1995-12-31

A proposed study design for evaluating the effect of PCBs in the sediments of a large New England river on reproductive success in frogs is described. Depending on field conditions and species abundance, the study will use either bullfrogs, Rana catesbiana; spring peepers, Hyla pickeringii; or green frogs, Rana claymitans as the study model. A selected number of gravid females will be collected from both the target area and a reference area matched with respect to a number of key variables including, but not limited to, stream flow, temperature, pH, substrate type, depth, surrounding land use, and organic carbon contentmore » of sediments. The gravid frogs will be transferred to a laboratory, where the egg masses will be stripped following induced ovulation, and then fertilized using semen from males collected in the field. Egg masses will be maintained under static renewal conditions for a period up to and including 7 days post hatch, during which mortality and gross morphological appearance will be evaluated. In the event that statistically significant differences in these endpoints are noted, a dose response model will be developed to relate observed effects to previously determined PCB concentrations in egg masses and maternal tissues. The results of this study will be of significant utility in evaluating reproductive toxicity of PCBs in ecological risk assessment.« less

Heat and Mass Transfer Processes in Scrubber of Flue Gas Heat Recovery Device

NASA Astrophysics Data System (ADS)

Veidenbergs, Ivars; Blumberga, Dagnija; Vigants, Edgars; Kozuhars, Grigorijs

2010-01-01

The paper deals with the heat and mass transfer process research in a flue gas heat recovery device, where complicated cooling, evaporation and condensation processes are taking place simultaneously. The analogy between heat and mass transfer is used during the process of analysis. In order to prepare a detailed process analysis based on heat and mass process descriptive equations, as well as the correlation for wet gas parameter calculation, software in the Microsoft Office Excel environment is being developed.

Delayed Triplet-State Formation through Hybrid Charge Transfer Exciton at Copper Phthalocyanine/GaAs Heterojunction.

PubMed

Lim, Heeseon; Kwon, Hyuksang; Kim, Sang Kyu; Kim, Jeong Won

2017-10-05

Light absorption in organic molecules on an inorganic substrate and subsequent electron transfer to the substrate create so-called hybrid charge transfer exciton (HCTE). The relaxation process of the HCTE states largely determines charge separation efficiency or optoelectronic device performance. Here, the study on energy and time-dispersive behavior of photoelectrons at the hybrid interface of copper phthalocyanine (CuPc)/p-GaAs(001) upon light excitation of GaAs reveals a clear pathway for HCTE relaxation and delayed triplet-state formation. According to the ground-state energy level alignment at the interface, CuPc/p-GaAs(001) shows initially fast hole injection from GaAs to CuPc. Thus, the electrons in GaAs and holes in CuPc form an unusual HCTE state manifold. Subsequent electron transfer from GaAs to CuPc generates the formation of the triplet state in CuPc with a few picoseconds delay. Such two-step charge transfer causes delayed triplet-state formation without singlet excitation and subsequent intersystem crossing within the CuPc molecules.

Using Carbon Nanotubes for Nanometer-Scale Energy Transfer Microscopy

NASA Astrophysics Data System (ADS)

Johnston, Jessica; Shafran, Eyal; Mangum, Ben; Mu, Chun; Gerton, Jordan

2009-10-01

We investigate optical energy transfer between fluorophores and carbon nanotubes (CNTs). CNTs are grown on Si-oxide wafers by chemical vapor deposition (CVD), lifted off substrates by atomic force microscope (AFM) tips via Van der Waals forces, then shortened by electrical pulses. The tip-attached CNTs are scanned over fluorescent CdSe-ZnS quantum dots (QDs) with sub-nm precision while recording the fluorescence rate. A novel photon counting technique enables us to produce 3D maps of the QD-CNT coupling, revealing nanoscale lateral and vertical features. All CNTs tested (>50) strongly quenched the QD fluorescence, apparently independent of chirality. In some data, a delay in the recovery of QD fluorescence following CNT-QD contact was observed, suggesting possible charge transfer in this system. In the future, we will perform time-resolved studies to quantify the rate of energy and charge transfer processes and study the possible differences in fluorescence quenching and nanotube-QD energy transfer when comparing single-walled (SW) versus multi-walled (MW) CNTs, attempting to grow substrates consisting primarily of SW or MWCNTs and characterizing the structure of tip-attached CNTs using optical spectroscopy.

Chemical and charge transfer studies on interfaces of a conjugated polymer and ITO

NASA Astrophysics Data System (ADS)

David, Tanya M. S.; Arasho, Wondwosson; Smith, O'Neil; Hong, Kunlun; Bonner, Carl; Sun, Sam-Shajing

2017-08-01

Conjugated oligomers and polymers are very attractive for potential future plastic electronic and opto-electronic device applications such as plastic photo detectors and solar cells, thermoelectric devices, field effect transistors, and light emitting diodes. Understanding and optimizing charge transport between an active polymer layer and conductive substrate is critical to the optimization of polymer based electronic and opto-electronic devices. This study focused on the design, synthesis, self-assembly, and electron transfers and transports of a phosphonic acid end-functionalized polyphenylenevinylene (PPV) that was covalently attached and self-assembled onto an Indium Tin Oxide (ITO) substrate. This study demonstrated how atomic force microscopy (AFM) can be an effective characterization technique in conjunction with conventional electron transfer methods, including cyclic voltammetry (CV), towards determining electron transfer rates in polymer and polymer/conductor interface systems. This study found that the electron transfer rates of covalently attached and self-assembled films were much faster than the spin coated films. The knowledge from this study can be very useful for designing potential polymer based electronic and opto-electronic thin film devices.

Polymer-coated compliant receivers for intact laser-induced forward transfer of thin films: experimental results and modelling

NASA Astrophysics Data System (ADS)

Feinaeugle, Matthias; Horak, Peter; Sones, Collin L.; Lippert, Thomas; Eason, Rob W.

2014-09-01

In this study, we investigate both experimentally and numerically laser-induced forward transfer (LIFT) of thin films to determine the role of a thin polymer layer coating the receiver with the aim of modifying the rate of deceleration and reduction of material stress preventing intact material transfer. A numerical model of the impact phase during LIFT shows that such a layer reduces the modelled stress. The evolution of stress within the transferred deposit and the substrate as a function of the thickness of the polymer layer, the transfer velocity and the elastic properties of the polymer are evaluated. The functionality of the polymer layer is verified experimentally by LIFT printing intact 1- m-thick bismuth telluride films and polymeric light-emitting diode pads onto a layer of 12-m-thick polydimethylsiloxane and 50-nm-thick poly(3,4-ethylenedioxythiophene) blended with poly(styrenesulfonate) (PEDOT:PSS), respectively. Furthermore, it is demonstrated experimentally that the introduction of such a compliant layer improves adhesion between the deposit and its substrate.

Selective Nanoscale Mass Transport across Atomically Thin Single Crystalline Graphene Membranes.

PubMed

Kidambi, Piran R; Boutilier, Michael S H; Wang, Luda; Jang, Doojoon; Kim, Jeehwan; Karnik, Rohit

2017-05-01

Atomically thin single crystals, without grain boundaries and associated defect clusters, represent ideal systems to study and understand intrinsic defects in materials, but probing them collectively over large area remains nontrivial. In this study, the authors probe nanoscale mass transport across large-area (≈0.2 cm 2 ) single-crystalline graphene membranes. A novel, polymer-free picture frame assisted technique, coupled with a stress-inducing nickel layer is used to transfer single crystalline graphene grown on silicon carbide substrates to flexible polycarbonate track etched supports with well-defined cylindrical ≈200 nm pores. Diffusion-driven flow shows selective transport of ≈0.66 nm hydrated K + and Cl - ions over ≈1 nm sized small molecules, indicating the presence of selective sub-nanometer to nanometer sized defects. This work presents a framework to test the barrier properties and intrinsic quality of atomically thin materials at the sub-nanometer to nanometer scale over technologically relevant large areas, and suggests the potential use of intrinsic defects in atomically thin materials for molecular separations or desalting. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Modelling for reactor-style aerobic composting based on coupling theory of mass-heat-momentum transport and Contois equation.

PubMed

He, Xueqin; Han, Lujia; Ge, Jinyi; Huang, Guangqun

2018-04-01

This study establishes an optimal mathematical modelling to rationally describe the dynamic changes and spatial distribution of temperature and oxygen concentration in the aerobic composting process using coupling mass-heat-momentum transfer based on the microbial mechanism. Two different conditional composting experiments, namely continuous aeration and intermittent aeration, were performed to verify the proposed model. The results show that the model accurately predicted the dynamic changes in temperature (case I: R 2  = 0.93, RMSE = 1.95 K; case II: R 2  = 0.86, RMSE = 4.69 K) and oxygen concentration (case I: R 2  = 0.90, RMSE = 1.26%; case II: R 2  = 0.75, RMSE = 2.93%) in the central point of compost substrates. It also systematically simulated fluctuations in oxygen concentration caused by boundary conditions and the spatial distribution of the actual temperature and oxygen concentration. The proposed model exhibits good applicability in simulating the actual working conditions of aerobic composting process. Copyright © 2018 Elsevier Ltd. All rights reserved.

Correlation of chemical evaporation rate with vapor pressure.

PubMed

Mackay, Donald; van Wesenbeeck, Ian

2014-09-02

A new one-parameter correlation is developed for the evaporation rate (ER) of chemicals as a function of molar mass (M) and vapor pressure (P) that is simpler than existing correlations. It applies only to liquid surfaces that are unaffected by the underlying solid substrate as occurs in the standard ASTM evaporation rate test and to quiescent liquid pools. The relationship has a sounder theoretical basis than previous correlations because ER is correctly correlated with PM rather than P alone. The inclusion of M increases the slope of previous log ER versus log P regressions to a value close to 1.0 and yields a simpler one-parameter correlation, namely, ER (μg m(-1) h(-1)) = 1464P (Pa) × M (g mol(-1)). Applications are discussed for the screening level assessment and ranking of chemicals for evaporation rate, such as pesticides, fumigants, and hydrocarbon carrier fluids used in pesticide formulations, liquid consumer products used indoors, and accidental spills of liquids. The mechanistic significance of the single parameter as a mass-transfer coefficient or velocity is discussed.

Detection of transient radical cations in electron transfer-initiated Diels-Alder reactions by electrospray ionization mass spectrometry.

PubMed

Fürmeier, Sven; Metzger, Jürgen O

2004-11-10

The coupling of a simple microreactor to an atmospheric pressure ion source, such as electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI), allows the investigation of reactions in solution by mass spectrometry. The tris(p-bromophenyl)aminium hexachloroantimonate (1(*)(+)SbCl(6)(-))-initiated reactions of phenylvinylsulfide (2) and cyclopentadiene (3) and of trans-anethole (5) and isoprene (6) and the dimerization of 1,3-cyclohexadiene (8) to give the respective Diels-Alder products were studied. These preparatively interesting reactions proceed as radical cation chain reactions via the transient radical cations of the respective dienophiles and of the respective Diels-Alder addition products. These radical cations could be detected directly and characterized unambiguously in the reacting solution by ESI-MS-MS. The identity was confirmed by comparison with MS-MS spectra of the authentic radical cations obtained by APCI-MS and by CID experiments of the corresponding molecular ions generated by EI-MS. In addition, substrates and products could be monitored easily in the reacting solution by APCI-MS.

The Roles of Biofilm Conductivity and Donor Substrate Kinetics in a Mixed-Culture Biofilm Anod

EPA Science Inventory

We experimentally assessed kinetics and thermodynamics of electron transfer (ET) from the donor substrate (acetate) to the anode for a mixed-culture biofilm anode. We interpreted the results with a modified biofilm-conduction model consisting of three ET steps: (1) intracellular...

Silver doped catalysts for treatment of exhaust

DOEpatents

Park, Paul Worn; Hester, Virgil Raymond; Ragle, Christie Susan; Boyer, Carrie L.

2009-06-02

A method of making an exhaust treatment element includes washcoating a substrate with a slurry that includes a catalyst support material. At least some of the catalyst support material from the slurry may be transferred to the substrate, and silver metal (Ag) is dispersed within the catalyst support material.

Atomistic determinants of co-enzyme Q reduction at the Qi-site of the cytochrome bc1 complex

NASA Astrophysics Data System (ADS)

Postila, Pekka A.; Kaszuba, Karol; Kuleta, Patryk; Vattulainen, Ilpo; Sarewicz, Marcin; Osyczka, Artur; Róg, Tomasz

2016-09-01

The cytochrome (cyt) bc1 complex is an integral component of the respiratory electron transfer chain sustaining the energy needs of organisms ranging from humans to bacteria. Due to its ubiquitous role in the energy metabolism, both the oxidation and reduction of the enzyme’s substrate co-enzyme Q has been studied vigorously. Here, this vast amount of data is reassessed after probing the substrate reduction steps at the Qi-site of the cyt bc1 complex of Rhodobacter capsulatus using atomistic molecular dynamics simulations. The simulations suggest that the Lys251 side chain could rotate into the Qi-site to facilitate binding of half-protonated semiquinone - a reaction intermediate that is potentially formed during substrate reduction. At this bent pose, the Lys251 forms a salt bridge with the Asp252, thus making direct proton transfer possible. In the neutral state, the lysine side chain stays close to the conserved binding location of cardiolipin (CL). This back-and-forth motion between the CL and Asp252 indicates that Lys251 functions as a proton shuttle controlled by pH-dependent negative feedback. The CL/K/D switching, which represents a refinement to the previously described CL/K pathway, fine-tunes the proton transfer process. Lastly, the simulation data was used to formulate a mechanism for reducing the substrate at the Qi-site.

Förster-Induced Energy Transfer in Functionalized Graphene

PubMed Central

2014-01-01

Carbon nanostructures are ideal substrates for functionalization with molecules since they consist of a single atomic layer giving rise to an extraordinary sensitivity to changes in their surrounding. The functionalization opens a new research field of hybrid nanostructures with tailored properties. Here, we present a microscopic view on the substrate–molecule interaction in the exemplary hybrid material consisting of graphene functionalized with perylene molecules. First experiments on similar systems have been recently realized illustrating an extremely efficient transfer of excitation energy from adsorbed molecules to the carbon substrate, a process with a large application potential for high-efficiency photovoltaic devices and biomedical imaging and sensing. So far, there has been no microscopically founded explanation for the observed energy transfer. Based on first-principle calculations, we have explicitly investigated the different transfer mechanisms revealing the crucial importance of Förster coupling. Due to the efficient Coulomb interaction in graphene, we obtain strong Förster rates in the range of 1/fs. We investigate its dependence on the substrate–molecule distance R and describe the impact of the momentum transfer q for an efficient energy transfer. Furthermore, we find that the Dexter transfer mechanism is negligibly small due to the vanishing overlap between the involved strongly localized orbital functions. The gained insights are applicable to a variety of carbon-based hybrid nanostructures. PMID:24808936

Mass transfer resistance in ASFF reactors for waste water treatment.

PubMed

Ettouney, H M; Al-Haddad, A A; Abu-Irhayem, T M

1996-01-01

Analysis of mass transfer resistances was performed for an aerated submerged fixed-film reactor (ASFF) for the treatment of waste water containing a mixture of sucrose and ammonia. Both external and internal mass transfer resistances were considered in the analysis, and characterized as a function of feed flow-rate and concentration. Results show that, over a certain operating regime, external mass transfer resistance in the system was greater for sucrose removal than ammonia. This is because the reaction rates for carbon removal were much larger than those of nitrogen. As a result, existence of any form of mass transfer resistance caused by inadequate mixing or diffusion limitations, strongly affects the overall removal rates of carbon more than nitrogen. Effects of the internal måss transfer resistance were virtually non-existent for ammonia removal. This behaviour was found over two orders of magnitude range for the effective diffusivity for ammonia, and one order of magnitude for the film specific surface area. However, over the same parameters' range, it is found that sucrose removal was strongly affected upon lowering its effective diffusivity and increasing the film specific surface area.

Model non-equilibrium molecular dynamics simulations of heat transfer from a hot gold surface to an alkylthiolate self-assembled monolayer.

PubMed

Zhang, Yue; Barnes, George L; Yan, Tianying; Hase, William L

2010-05-07

Model non-equilibrium molecular dynamics (MD) simulations are presented of heat transfer from a hot Au {111} substrate to an alkylthiolate self-assembled monolayer (H-SAM) to assist in obtaining an atomic-level understanding of experiments by Wang et al. (Z. Wang, J. A. Carter, A. Lagutchev, Y. K. Koh, N.-H. Seong, D. G. Cahill, and D. D. Dlott, Science, 2007, 317, 787). Different models are considered to determine how they affect the heat transfer dynamics. They include temperature equilibrated (TE) and temperature gradient (TG) thermostat models for the Au(s) surface, and soft and stiff S/Au(s) models for bonding of the S-atoms to the Au(s) surface. A detailed analysis of the non-equilibrium heat transfer at the heterogeneous interface is presented. There is a short time temperature gradient within the top layers of the Au(s) surface. The S-atoms heat rapidly, much faster than do the C-atoms in the alkylthiolate chains. A high thermal conductivity in the H-SAM, perpendicular to the interface, results in nearly identical temperatures for the CH(2) and CH(3) groups versus time. Thermal-induced disorder is analyzed for the Au(s) substrate, the S/Au(s) interface and the H-SAM. Before heat transfer occurs from the hot Au(s) substrate to the H-SAM, there is disorder at the S/Au(s) interface and within the alkylthiolate chains arising from heat-induced disorder near the surface of hot Au(s). The short-time rapid heating of the S-atoms enhances this disorder. The increasing disorder of H-SAM chains with time results from both disorder at the Au/S interface and heat transfer to the H-SAM chains.

Fabrication of patterned surface by soft lithographic technique for confinement of lipid bilayer

NASA Astrophysics Data System (ADS)

Moulick, Ranjita Ghosh; Mayer, Dirk

2018-04-01

In this paper we demonstrated that a 3D pattern can be well transferred from a silicon Master to a gold substrate using µcontact printing. In this process 1-Octadecanthiol served as an ink and printing followed by etching generated the desired pattern on the gold substrate. The prepatterned substrate was also used for lipid vesicle fusion and revealed that lipid molecules selectively bind to the gold layer.

Protein-based stable isotope probing.

PubMed

Jehmlich, Nico; Schmidt, Frank; Taubert, Martin; Seifert, Jana; Bastida, Felipe; von Bergen, Martin; Richnow, Hans-Hermann; Vogt, Carsten

2010-12-01

We describe a stable isotope probing (SIP) technique that was developed to link microbe-specific metabolic function to phylogenetic information. Carbon ((13)C)- or nitrogen ((15)N)-labeled substrates (typically with >98% heavy label) were used in cultivation experiments and the heavy isotope incorporation into proteins (protein-SIP) on growth was determined. The amount of incorporation provides a measure for assimilation of a substrate, and the sequence information from peptide analysis obtained by mass spectrometry delivers phylogenetic information about the microorganisms responsible for the metabolism of the particular substrate. In this article, we provide guidelines for incubating microbial cultures with labeled substrates and a protocol for protein-SIP. The protocol guides readers through the proteomics pipeline, including protein extraction, gel-free and gel-based protein separation, the subsequent mass spectrometric analysis of peptides and the calculation of the incorporation of stable isotopes into peptides. Extraction of proteins and the mass fingerprint measurements of unlabeled and labeled fractions can be performed in 2-3 d.

Formation of black hole x-ray binaries in globular clusters

NASA Astrophysics Data System (ADS)

Kremer, Kyle; Chatterjee, Sourav; Rodriguez, Carl; Rasio, Frederic

2018-01-01

We explore the formation of mass-transferring binary systems containing black holes within globular clusters. We show that it is possible to form mass-transferring binaries with main sequence, giant, and white dwarf companions with a variety of orbital parameters in globular clusters spanning a large range in present-day properties. We show that the presence of mass-transferring black hole systems has little correlation with the total number of black holes within the cluster at any time. In addition to mass-transferring binaries retained within their host clusters at late times, we also examine the black hole and neutron star binaries that are ejected from their host clusters. These ejected systems may contribute to the low-mass x-ray binary population in the galactic field.

Modelling mass transfer during venting/soil vapour extraction: Non-aqueous phase liquid/gas mass transfer coefficient estimation

NASA Astrophysics Data System (ADS)

Esrael, D.; Kacem, M.; Benadda, B.

2017-07-01

We investigate how the simulation of the venting/soil vapour extraction (SVE) process is affected by the mass transfer coefficient, using a model comprising five partial differential equations describing gas flow and mass conservation of phases and including an expression accounting for soil saturation conditions. In doing so, we test five previously reported quations for estimating the non-aqueous phase liquid (NAPL)/gas initial mass transfer coefficient and evaluate an expression that uses a reference NAPL saturation. Four venting/SVE experiments utilizing a sand column are performed with dry and non-saturated sand at low and high flow rates, and the obtained experimental results are subsequently simulated, revealing that hydrodynamic dispersion cannot be neglected in the estimation of the mass transfer coefficient, particularly in the case of low velocities. Among the tested models, only the analytical solution of a convection-dispersion equation and the equation proposed herein are suitable for correctly modelling the experimental results, with the developed model representing the best choice for correctly simulating the experimental results and the tailing part of the extracted gas concentration curve.

Disentangling oil weathering using GC x GC. 2. Mass transfer calculations.

PubMed

Arey, J Samuel; Nelson, Robert K; Plata, Desiree L; Reddy, Christopher M

2007-08-15

Hydrocarbon mass transfers to the atmosphere and water column drive the early weathering of oil spills and also control the chemical exposures of many coastal wildlife species. However, in the field, mass transfer rates of individual hydrocarbons to air and water are often uncertain. In the Part 1 companion to this paper, we used comprehensive two-dimensional gas chromatography (GC x GC) to identify distinct signatures of evaporation and dissolution encoded in the compositional evolution of weathered oils. In Part 2, we further investigate patterns of mass removal in GC x GC chromatograms using a mass transfer model. The model was tailored to conditions at a contaminated beach on Buzzards Bay, MA, after the 2003 Bouchard 120 oil spill. The model was applied to all resolved hydrocarbon compounds in the C11-C24 boiling range, based on their GC x GC-estimated vapor pressures and aqueous solubilities. With no fitted parameters, the model successfully predicted GC x GC chromatogram patterns of mass removal associated with evaporation, water-washing, and diffusion-limited transport. This enabled a critical field evaluation of the mass transfer model and also allowed mass apportionment estimates of hundreds of individual hydrocarbon compounds to air and water. Ultimately, this method should improve assessments of wildlife exposures to oil spill hydrocarbons.

Three-dimensional simulations of turbulent convective mixing in ONe and CO classical nova explosions

DOE PAGES

Casanova, Jordi; José, Jordi; García-Berro, Enrique; ...

2016-10-25

Classical novae are thermonuclear explosions that take place in the envelopes of accreting white dwarfs in binary systems. The material piles up under degenerate conditions, driving a thermonuclear runaway. The energy released by the suite of nuclear processes operating at the envelope heats the material up to peak temperatures of ~(1-4) × 10 8 K. During these events, about 10 -3-10 -7 M ⊙, enriched in CNO and, sometimes, other intermediate-mass elements (e.g., Ne, Na, Mg, Al) are ejected into the interstellar medium. To account for the gross observational properties of classical novae (in particular, the high concentrations of metalsmore » spectroscopically inferred in the ejecta), models require mixing between the (solar-like) material transferred from the secondary and the outermost layers (CO- or ONe-rich) of the underlying white dwarf. Recent multidimensional simulations have demonstrated that Kelvin-Helmholtz instabilities can naturally produce self-enrichment of the accreted envelope with material from the underlying white dwarf at levels that agree with observations. However, the feasibility of this mechanism has been explored in the framework of CO white dwarfs, while mixing with different substrates still needs to be properly addressed. We performed three-dimensional simulations of mixing at the core-envelope interface during nova outbursts with the multidimensional code FLASH, for two types of substrates: CO- and ONe-rich. We also show that the presence of an ONe-rich substrate, as in “neon novae”, yields higher metallicity enhancements in the ejecta than CO-rich substrates (i.e., non-neon novae). Finally, a number of requirements and constraints for such 3D simulations (e.g., minimum resolution, size of the computational domain) are also outlined.« less

Controllable Growth of Large-Size Crystalline MoS2 and Resist-Free Transfer Assisted with a Cu Thin Film.

PubMed

Lin, Ziyuan; Zhao, Yuda; Zhou, Changjian; Zhong, Ren; Wang, Xinsheng; Tsang, Yuen Hong; Chai, Yang

2015-12-21

Two-dimensional MoS2 is a promising material for future nanoelectronics and optoelectronics. It has remained a great challenge to grow large-size crystalline and high surface coverage monolayer MoS2. In this work, we investigate the controllable growth of monolayer MoS2 evolving from triangular flakes to continuous thin films by optimizing the concentration of gaseous MoS2, which has been shown a both thermodynamic and kinetic growth factor. A single-crystal monolayer MoS2 larger than 300 μm was successfully grown by suppressing the nuclei density and supplying sufficient source. Furthermore, we present a facile process of transferring the centimeter scale MoS2 assisted with a copper thin film. Our results show the absence of observable residues or wrinkles after we transfer MoS2 from the growth substrates onto flat substrates using this technique, which can be further extended to transfer other two-dimensional layered materials.

Controllable Growth of Large-Size Crystalline MoS2 and Resist-Free Transfer Assisted with a Cu Thin Film

NASA Astrophysics Data System (ADS)

Lin, Ziyuan; Zhao, Yuda; Zhou, Changjian; Zhong, Ren; Wang, Xinsheng; Tsang, Yuen Hong; Chai, Yang

2015-12-01

Two-dimensional MoS2 is a promising material for future nanoelectronics and optoelectronics. It has remained a great challenge to grow large-size crystalline and high surface coverage monolayer MoS2. In this work, we investigate the controllable growth of monolayer MoS2 evolving from triangular flakes to continuous thin films by optimizing the concentration of gaseous MoS2, which has been shown a both thermodynamic and kinetic growth factor. A single-crystal monolayer MoS2 larger than 300 μm was successfully grown by suppressing the nuclei density and supplying sufficient source. Furthermore, we present a facile process of transferring the centimeter scale MoS2 assisted with a copper thin film. Our results show the absence of observable residues or wrinkles after we transfer MoS2 from the growth substrates onto flat substrates using this technique, which can be further extended to transfer other two-dimensional layered materials.

Heat-transfer dynamics during cryogen spray cooling of substrate at different initial temperatures.

PubMed

Jia, Wangcun; Aguilar, Guillermo; Wang, Guo-Xiang; Nelson, J Stuart

2004-12-07

Cryogen spray cooling (CSC) is used to minimize the risk of epidermal damage during laser dermatologic therapy. However, the dominant mechanisms of heat transfer during the transient cooling process are incompletely understood. The objective of this study is to elucidate the physics of CSC by measuring the effect of initial substrate temperature (T0) on cooling dynamics. Cryogen was delivered by a straight-tube nozzle onto a skin phantom. A fast-response thermocouple was used to record the phantom temperature changes before, during and after the cryogen spray. Surface heat fluxes (q") and heat-transfer coefficients (h) were computed using an inverse heat conduction algorithm. The maximum surface heat flux (q"max) was observed to increase with T0. The surface temperature corresponding to q"max also increased with T0 but the latter has no significant effect on h. It is concluded that heat transfer between the cryogen spray and skin phantom remains in the nucleate boiling region even if T0 is 80 degrees C.

High-frequency self-aligned graphene transistors with transferred gate stacks

PubMed Central

Cheng, Rui; Bai, Jingwei; Liao, Lei; Zhou, Hailong; Chen, Yu; Liu, Lixin; Lin, Yung-Chen; Jiang, Shan; Huang, Yu; Duan, Xiangfeng

2012-01-01

Graphene has attracted enormous attention for radio-frequency transistor applications because of its exceptional high carrier mobility, high carrier saturation velocity, and large critical current density. Herein we report a new approach for the scalable fabrication of high-performance graphene transistors with transferred gate stacks. Specifically, arrays of gate stacks are first patterned on a sacrificial substrate, and then transferred onto arbitrary substrates with graphene on top. A self-aligned process, enabled by the unique structure of the transferred gate stacks, is then used to position precisely the source and drain electrodes with minimized access resistance or parasitic capacitance. This process has therefore enabled scalable fabrication of self-aligned graphene transistors with unprecedented performance including a record-high cutoff frequency up to 427 GHz. Our study defines a unique pathway to large-scale fabrication of high-performance graphene transistors, and holds significant potential for future application of graphene-based devices in ultra–high-frequency circuits. PMID:22753503

Low-temperature fabrication of dye-sensitized solar cells by transfer of composite porous layers

NASA Astrophysics Data System (ADS)

Dürr, Michael; Schmid, Andreas; Obermaier, Markus; Rosselli, Silvia; Yasuda, Akio; Nelles, Gabriele

2005-08-01

Dye-sensitized solar cells have established themselves as a potential low-cost alternative to conventional solar cells owing to their remarkably high power-conversion efficiency combined with `low-tech' fabrication processes. As a further advantage, the active layers consisting of nanoporous TiO2 are only some tens of micrometres thick and are therefore in principle suited for flexible applications. However, typical flexible plastic substrates cannot withstand the process temperatures of up to 500 ∘C commonly used for sintering the TiO2 nanoparticles together. Even though some promising routes for low-temperature sintering have been proposed, those layers cannot compete as regards electrical properties with layers obtained with the standard high-temperature process. Here we show that by a lift-off technique, presintered porous layers can be transferred to an arbitrary second substrate, and the original electrical properties of the transferred porous layers are maintained. The transfer process is greatly assisted by the application of composite layers comprising nanoparticles and nanorods.

Time-dependent areal mass density for disc-shaped substrates in a corona-activated flow stream at atmospheric pressure for argon/acetylene admixture

NASA Astrophysics Data System (ADS)

Xie, Shuzheng; Islam, Rokibul; Hussein, Bashir; Englund, Karl; Pedrow, Patrick

2015-09-01

In this research we use a 40-needle array energized with 60 Hz AC voltage in the range 5 to 15 kV RMS. Plasma processing takes place downstream from a grounded planar screen (the opposing electrode). The needle-to-screen gap is in the range 4 to 10 cm and its E-field generates weakly ionized plasma via streamers and back corona. Deposited material is plasma-polymerized acetylene. Substrates are potassium bromide, mica, wood, paper, and gold-covered solids. Substrate chemical species influence the efficiency with which the disc amasses plasma-polymerized material, at least until the substrate is fully covered with film. Early plasma-polymerization is accompanied by nucleation-site-dominated nodules but longer term deposition results in a film that fully covers the substrate. We will report on time-dependent areal mass density associated with run times in the range 5-60 minutes. Film thickness will be measured using instruments that include visible light microscopy, TEM, and SEM. Others in our research group are studying areal mass density for early times (1-5 minutes) when nodule growth (at nucleation sites) dominates the deposition process.

Thermal Enhancement of Silicon Carbide (SiC) Power Electronics and Laser Bars: Statistical Design Optimization of a Liquid-Cooled Power Electronic Heat Sink

DTIC Science & Technology

2015-08-01

Forced Convective Heat Transfer Across a Pin Fin Micro Heat Sink”, International Journal of Heat and Mass Transfer 48 (2005) 3615-3627. 3. Cao...from Pin Fins Situated in an Oncoming Longitudinal Flow Which Turns to Crossflow”, International Journal of Heat and Mass Transfer, Vol. 25 No. 5...Flow Forced Convection”, International Journal of Heat and Mass Transfer, Vol. 39, No. 2, pp. 311-317, 1996. 11. Khan, W., Culham, J., and Yovanovich

Smooth information flow in temperature climate network reflects mass transport

NASA Astrophysics Data System (ADS)

Hlinka, Jaroslav; Jajcay, Nikola; Hartman, David; Paluš, Milan

2017-03-01

A directed climate network is constructed by Granger causality analysis of air temperature time series from a regular grid covering the whole Earth. Using winner-takes-all network thresholding approach, a structure of a smooth information flow is revealed, hidden to previous studies. The relevance of this observation is confirmed by comparison with the air mass transfer defined by the wind field. Their close relation illustrates that although the information transferred due to the causal influence is not a physical quantity, the information transfer is tied to the transfer of mass and energy.

An Assessment of the General Applicability of the Relationship Between Nucleation of CO Bubbles and Mass Transfer of Phosphorus in Liquid Iron Alloys

NASA Astrophysics Data System (ADS)

Gu, Kezhuan; Dogan, Neslihan; Coley, Kenneth S.

2018-06-01

The current paper seeks to demonstrate the general applicability of the authors' recently developed treatment of surface renewal during decarburization of Fe-C-S alloys and its effect on the mass transport of phosphorus in the metal phase. The proposed model employs a quantitative model of CO bubble nucleation in the metal to predict the rate of surface renewal, which can then in turn be used to predict the mass-transfer coefficient for phosphorus. A model of mixed transport control in the slag and metal phases was employed to investigate the dephosphorization kinetics between a liquid iron alloy and oxidizing slag. Based on previous studies of the mass-transfer coefficient of FeO in the slag, it was possible to separate the mass transfer coefficient of phosphorus in metal phase, km , from the overall mass-transfer coefficient k_{{o}} . Using this approach, km was investigated under a wide range of conditions and shown to be represented reasonably by the mechanism proposed. The mass-transfer model was tested against results from the literature over a wide range of conditions. The analysis showed that the FeO content in the slag, silicon in the metal and the experimental temperature have strong impact on, km , almost entirely because of their effect on decarburization behavior.

An Assessment of the General Applicability of the Relationship Between Nucleation of CO Bubbles and Mass Transfer of Phosphorus in Liquid Iron Alloys

NASA Astrophysics Data System (ADS)

Gu, Kezhuan; Dogan, Neslihan; Coley, Kenneth S.

2018-02-01

The current paper seeks to demonstrate the general applicability of the authors' recently developed treatment of surface renewal during decarburization of Fe-C-S alloys and its effect on the mass transport of phosphorus in the metal phase. The proposed model employs a quantitative model of CO bubble nucleation in the metal to predict the rate of surface renewal, which can then in turn be used to predict the mass-transfer coefficient for phosphorus. A model of mixed transport control in the slag and metal phases was employed to investigate the dephosphorization kinetics between a liquid iron alloy and oxidizing slag. Based on previous studies of the mass-transfer coefficient of FeO in the slag, it was possible to separate the mass transfer coefficient of phosphorus in metal phase, km , from the overall mass-transfer coefficient k_{{o}} . Using this approach, km was investigated under a wide range of conditions and shown to be represented reasonably by the mechanism proposed. The mass-transfer model was tested against results from the literature over a wide range of conditions. The analysis showed that the FeO content in the slag, silicon in the metal and the experimental temperature have strong impact on, km , almost entirely because of their effect on decarburization behavior.

Method for preparing ultraflat, atomically perfect areas on large regions of a crystal surface by heteroepitaxy deposition

DOEpatents

El Gabaly, Farid; Schmid, Andreas K.

2013-03-19

A novel method of forming large atomically flat areas is described in which a crystalline substrate having a stepped surface is exposed to a vapor of another material to deposit a material onto the substrate, which material under appropriate conditions self arranges to form 3D islands across the substrate surface. These islands are atomically flat at their top surface, and conform to the stepped surface of the substrate below at the island-substrate interface. Thereafter, the deposited materials are etched away, in the etch process the atomically flat surface areas of the islands transferred to the underlying substrate. Thereafter the substrate may be cleaned and annealed to remove any remaining unwanted contaminants, and eliminate any residual defects that may have remained in the substrate surface as a result of pre-existing imperfections of the substrate.

Performance of an ultrafiltration membrane bioreactor (UF-MBR) as a processing strategy for the synthesis of galacto-oligosaccharides at high substrate concentrations.

PubMed

Córdova, Andrés; Astudillo, Carolina; Vera, Carlos; Guerrero, Cecilia; Illanes, Andrés

2016-04-10

The performance of an ultrafiltration membrane bioreactor for galacto-oligosaccharides (GOS) synthesis using high lactose concentrations (470 g/L) and β-galactosidase from Aspergillus oryzae was assessed. Tested processing variables were: transmembrane-pressure (PT), crossflow-velocity (CFV) and temperature. Results showed that processing variables had significant effect on the yield, the enzyme productivity and the flux but did not on GOS concentration and reaction conversion obtained. As expected, the use of high turbulences improved mass transfer and reduced the membrane fouling, but the use of very high crossflow-velocities caused operational instability due to vortex formation and lactose precipitation. The use of a desirability function allowed determining optimal conditions which were: PT (4.38 bar), CFV (7.35 m/s) and temperature (53.1 °C), optimizing simultaneously flux and specific enzyme productivity Under these optimal processing conditions, shear-stress and temperature did not affect the enzyme but long-term operation was limited by flux decay. In comparison to a conventional batch system, at 12.5h of processing time, the continuous GOS synthesis in the UF-MBR increased significantly the amount of processed substrate and a 2.44-fold increase in the amount of GOS produced per unit mass of catalyst was obtained with respect to a conventional batch system. Furthermore, these results can be improved by far by tuning the membranearea/reactionvolume ratio, showing that the use of an UF-MBR is an attractive alternative for the GOS synthesis at very high lactose concentrations. Copyright © 2016 Elsevier B.V. All rights reserved.

Sulfanegen sodium treatment in a rabbit model of sub-lethal cyanide toxicity

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

Brenner, Matthew, E-mail: mbrenner@uci.ed; Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of California, Irvine, CA 92868; Kim, Jae G.

2010-11-01

The aim of this study is to investigate the ability of intramuscular and intravenous sulfanegen sodium treatment to reverse cyanide effects in a rabbit model as a potential treatment for mass casualty resulting from cyanide exposure. Cyanide poisoning is a serious chemical threat from accidental or intentional exposures. Current cyanide exposure treatments, including direct binding agents, methemoglobin donors, and sulfur donors, have several limitations. Non-rhodanese mediated sulfur transferase pathways, including 3-mercaptopyruvate sulfurtransferase (3-MPST) catalyze the transfer of sulfur from 3-MP to cyanide, forming pyruvate and less toxic thiocyanate. We developed a water-soluble 3-MP prodrug, 3-mercaptopyruvatedithiane (sulfanegen sodium), with the potentialmore » to provide a continuous supply of substrate for CN detoxification. In addition to developing a mass casualty cyanide reversal agent, methods are needed to rapidly and reliably diagnose and monitor cyanide poisoning and reversal. We use non-invasive technology, diffuse optical spectroscopy (DOS) and continuous wave near infrared spectroscopy (CWNIRS) to monitor physiologic changes associated with cyanide exposure and reversal. A total of 35 animals were studied. Sulfanegen sodium was shown to reverse the effects of cyanide exposure on oxyhemoglobin and deoxyhemoglobin rapidly, significantly faster than control animals when administered by intravenous or intramuscular routes. RBC cyanide levels also returned to normal faster following both intramuscular and intravenous sulfanegen sodium treatment than controls. These studies demonstrate the clinical potential for the novel approach of supplying substrate for non-rhodanese mediated sulfur transferase pathways for cyanide detoxification. DOS and CWNIRS demonstrated their usefulness in optimizing the dose of sulfanegen sodium treatment.« less

CFD Application to Flow-Accelerated Corrosion in Feeder Bends

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

Pietralik, John M.; Smith, Bruce A.W.

2006-07-01

Feeder piping in CANDU{sup R} plants experiences a thinning degradation mechanism called Flow-Accelerated Corrosion (FAC). The piping is made of carbon steel and has high water flow speeds. Although the water chemistry is highly alkaline with room-temperature pH in a range of 10.0-10.5, the piping has FAC rates exceeding 0.1 mm/year in some locations, e.g., in bends. One of the most important parameters affecting the FAC rate is the mass transfer coefficient for convective mass transport of ferrous ions. The ions are created at the pipe wall as a result of corrosion, diffuse through the oxide layer, and are transportedmore » from the oxide-layer/water interface to the bulk water by mass transport. Consequently, the local flow characteristics contribute to the highly turbulent convective mass transfer. Plant data and laboratory experiments indicate that the mass transfer step dominates FAC under feeder conditions. In this study, the flow and mass transfer in a feeder bend under operating conditions were simulated using the Fluent{sup TM} computer code. Because the flow speed is very high, with the Reynolds numbers in a range of several millions, and because the geometry is complex, experiments in a 1:1 scale were conducted with the main objective to validate flow simulations. The experiments measured pressure at several key locations and visualized the flow. The flow and mass transfer models were validated using available friction-factor and mass transfer correlations and literature experiments on mass transfer in a bend. The validation showed that the turbulence model that best predicts the experiments is the realizable k-{epsilon} model. Other two-equation turbulence models, as well as one-equation models and Reynolds stress models were tried. The near-wall treatment used the non-equilibrium wall functions. The wall functions were modified for surface roughness when necessary. A comparison of the local mass transfer coefficient with measured FAC rate in plant specimens shows very good agreement. Visualization experiments indicate secondary flows in the bends. No boundary layer separation was observed in experiments or in simulations. (authors)« less

Revealing the Crystalline Integrity of Wafer-Scale Graphene on SiO2/Si: An Azimuthal RHEED Approach.

PubMed

Lu, Zonghuan; Sun, Xin; Xiang, Yu; Washington, Morris A; Wang, Gwo-Ching; Lu, Toh-Ming

2017-07-12

The symmetry of graphene is usually determined by a low-energy electron diffraction (LEED) method when the graphene is on the conductive substrates, but LEED cannot handle graphene transferred to SiO 2 /Si substrates due to the charging effect. While transmission electron microscopy can generate electron diffraction on post-transferred graphene, this method is too localized. Herein, we employed an azimuthal reflection high-energy electron diffraction (RHEED) method to construct the reciprocal space mapping and determine the symmetry of wafer-size graphene both pre- and post-transfer. In this work, single-crystalline Cu(111) films were prepared on sapphire(0001) and spinel(111) substrates with sputtering. Then the graphene was epitaxially grown on single-crystalline Cu(111) films with a low pressure chemical vapor deposition. The reciprocal space mapping using azimuthal RHEED confirmed that the graphene grown on Cu(111) films was single-crystalline, no matter the form of the monolayer or multilayer structure. While the Cu(111) film grown on sapphire(0001) may occasionally consist of 60° in-plane rotational twinning, the reciprocal space mapping revealed that the in-plane orientation of graphene grown atop was not affected. The proposed method for checking the crystalline integrity of the post-transferred graphene sheets is an important step in the realization of the graphene as a platform to fabricate electronic and optoelectronic devices.

Hydrodynamic and thermal modeling of two-dimensional microdroplet arrays for digitized heat transfer

NASA Astrophysics Data System (ADS)

Baird, Eric S.

This document describes hydrodynamic and thermal modeling of two-dimensional microdroplet arrays for use in digitized heat transfer (DHT), a novel active thermal management technique for high power density electronics and integrated microsystems. In DHT, thermal energy is transported by a discrete array of electrostatically activated microdroplets of liquid metals, alloys or aqueous solutions with the potential of supporting significantly higher heat transfer rates than classical air-cooled heat sinks. Actuation methods for dispensing and transporting individual fluid slugs with a high degree of precision and programmability are described, with simple approximate formulae for net forces for steady state and transient velocities in terms of known parameters. A modified cavity flow solver is developed to provide details on the internal flow properties of a translating microdroplet and used to detail the effects of droplet curvature, internal mixing, Peclet number and other parameters on the heat transfer capabilities of a discretized liquid flow. The concept of Nusselt number is generalized to an individual fluid slug and shown to oscillate with a period equal to the droplet's mixing rate. In whole, DHT is demonstrated to be a viable new alternative for achieving the most important objectives of electronic cooling (i.e., minimization of the maximum substrate temperature, reduction of the substrate temperature gradient and removal of substrate hot spots) and a sound fundamental description of the method's electro-, hydro- and thermodynamics is provided.

The 300 Area Integrated Field Research Challenge Quality Assurance Project Plan

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

Fix, N. J.

Pacific Northwest National Laboratory and a group of expert collaborators are using the U.S. Department of Energy Hanford Site 300 Area uranium plume within the footprint of the 300-FF-5 groundwater operable unit as a site for an Integrated Field-Scale Subsurface Research Challenge (IFRC). The IFRC is entitled Multi-Scale Mass Transfer Processes Controlling Natural Attenuation and Engineered Remediation: An IFRC Focused on the Hanford Site 300 Area Uranium Plume Project. The theme is investigation of multi-scale mass transfer processes. A series of forefront science questions on mass transfer are posed for research that relate to the effect of spatial heterogeneities; themore » importance of scale; coupled interactions between biogeochemical, hydrologic, and mass transfer processes; and measurements/approaches needed to characterize and model a mass transfer-dominated system. This Quality Assurance Project Plan provides the quality assurance requirements and processes that will be followed by the 300 Area IFRC Project. This plan is designed to be used exclusively by project staff.« less

Accreting Black Hole Binaries in Globular Clusters

NASA Astrophysics Data System (ADS)

Kremer, Kyle; Chatterjee, Sourav; Rodriguez, Carl L.; Rasio, Frederic A.

2018-01-01

We explore the formation of mass-transferring binary systems containing black holes (BHs) within globular clusters (GC). We show that it is possible to form mass-transferring BH binaries with main sequence, giant, and white dwarf companions with a variety of orbital parameters in GCs spanning a large range in present-day properties. All mass-transferring BH binaries found in our models at late times are dynamically created. The BHs in these systems experienced a median of ∼30 dynamical encounters within the cluster before and after acquiring the donor. Furthermore, we show that the presence of mass-transferring BH systems has little correlation with the total number of BHs within the cluster at any time. This is because the net rate of formation of BH–non-BH binaries in a cluster is largely independent of the total number of retained BHs. Our results suggest that the detection of a mass-transferring BH binary in a GC does not necessarily indicate that the host cluster contains a large BH population.

Influence of Wind Pressure on the Carbonation of Concrete

PubMed Central

Zou, Dujian; Liu, Tiejun; Du, Chengcheng; Teng, Jun

2015-01-01

Carbonation is one of the major deteriorations that accelerate steel corrosion in reinforced concrete structures. Many mathematical/numerical models of the carbonation process, primarily diffusion-reaction models, have been established to predict the carbonation depth. However, the mass transfer of carbon dioxide in porous concrete includes molecular diffusion and convection mass transfer. In particular, the convection mass transfer induced by pressure difference is called penetration mass transfer. This paper presents the influence of penetration mass transfer on the carbonation. A penetration-reaction carbonation model was constructed and validated by accelerated test results under high pressure. Then the characteristics of wind pressure on the carbonation were investigated through finite element analysis considering steady and fluctuating wind flows. The results indicate that the wind pressure on the surface of concrete buildings results in deeper carbonation depth than that just considering the diffusion of carbon dioxide. In addition, the influence of wind pressure on carbonation tends to increase significantly with carbonation depth. PMID:28793462

Saponification reaction system: a detailed mass transfer coefficient determination.

PubMed

Pečar, Darja; Goršek, Andreja

2015-01-01

The saponification of an aromatic ester with an aqueous sodium hydroxide was studied within a heterogeneous reaction medium in order to determine the overall kinetics of the selected system. The extended thermo-kinetic model was developed compared to the previously used simple one. The reaction rate within a heterogeneous liquid-liquid system incorporates a chemical kinetics term as well as mass transfer between both phases. Chemical rate constant was obtained from experiments within a homogeneous medium, whilst the mass-transfer coefficient was determined separately. The measured thermal profiles were then the bases for determining the overall reaction-rate. This study presents the development of an extended kinetic model for considering mass transfer regarding the saponification of ethyl benzoate with sodium hydroxide within a heterogeneous reaction medium. The time-dependences are presented for the mass transfer coefficient and the interfacial areas at different heterogeneous stages and temperatures. The results indicated an important role of reliable kinetic model, as significant difference in k(L)a product was obtained with extended and simple approach.

Direct Numerical Simulation of Fluid Flow and Mass Transfer in Particle Clusters

PubMed Central

2018-01-01

In this paper, an efficient ghost-cell based immersed boundary method is applied to perform direct numerical simulation (DNS) of mass transfer problems in particle clusters. To be specific, a nine-sphere cuboid cluster and a random-generated spherical cluster consisting of 100 spheres are studied. In both cases, the cluster is composed of active catalysts and inert particles, and the mutual influence of particles on their mass transfer performance is studied. To simulate active catalysts the Dirichlet boundary condition is imposed at the external surface of spheres, while the zero-flux Neumann boundary condition is applied for inert particles. Through our studies, clustering is found to have negative influence on the mass transfer performance, which can be then improved by dilution with inert particles and higher Reynolds numbers. The distribution of active/inert particles may lead to large variations of the cluster mass transfer performance, and individual particle deep inside the cluster may possess a high Sherwood number. PMID:29657359

Influence of Wind Pressure on the Carbonation of Concrete.

PubMed

Zou, Dujian; Liu, Tiejun; Du, Chengcheng; Teng, Jun

2015-07-24

Carbonation is one of the major deteriorations that accelerate steel corrosion in reinforced concrete structures. Many mathematical/numerical models of the carbonation process, primarily diffusion-reaction models, have been established to predict the carbonation depth. However, the mass transfer of carbon dioxide in porous concrete includes molecular diffusion and convection mass transfer. In particular, the convection mass transfer induced by pressure difference is called penetration mass transfer. This paper presents the influence of penetration mass transfer on the carbonation. A penetration-reaction carbonation model was constructed and validated by accelerated test results under high pressure. Then the characteristics of wind pressure on the carbonation were investigated through finite element analysis considering steady and fluctuating wind flows. The results indicate that the wind pressure on the surface of concrete buildings results in deeper carbonation depth than that just considering the diffusion of carbon dioxide. In addition, the influence of wind pressure on carbonation tends to increase significantly with carbonation depth.

Gradient doping - a case study with Ti-Fe2O3 towards an improved photoelectrochemical response.

PubMed

Srivastav, Anupam; Verma, Anuradha; Banerjee, Anamika; Khan, Saif A; Gupta, Mukul; Satsangi, Vibha Rani; Shrivastav, Rohit; Dass, Sahab

2016-12-07

The present study investigates the effect of gradient doping on modifying the photoelectrochemical response of Ti-doped Fe 2 O 3 photoanodes for their use in sunlight based water splitting for hydrogen evolution. The deposition of a thin film over the ITO (tin doped indium oxide) substrate was carried out using a spray pyrolysis method. The concentration of dopant was varied from 0.5-8.0 at% and two sets of samples were also prepared with low to high (0.5-8%) and high to low (8-0.5%) dopant concentrations in the direction towards the substrate. The prepared thin films were characterized using X-ray Diffractometry (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX) Spectroscopy, Secondary Ion Mass Spectroscopy (SIMS), X-ray Photoelectron Spectroscopy (XPS) and UV-visible Spectroscopy. The photoelectrochemical studies revealed that the deposition of dopant layers with a low to high concentration towards the substrate exhibited a highly improved photoresponse (200 times) in comparison to the pristine sample and a two fold enhancement in comparison to 2% Ti-doped Fe 2 O 3 . The improvement in the photoresponse has been attributed to the values of a high flat band potential, low resistance, high open circuit voltage, carrier separation efficiency, applied bias photon-to-current conversion efficiency (ABPE), and incident photon-to-current conversion efficiency (IPCE). A reduced charge transfer resistance has been demonstrated with Nyquist plots.

Low platinum loading for high temperature proton exchange membrane fuel cell developed by ultrasonic spray coating technique

NASA Astrophysics Data System (ADS)

Su, Huaneng; Jao, Ting-Chu; Barron, Olivia; Pollet, Bruno G.; Pasupathi, Sivakumar

2014-12-01

This paper reports use of an ultrasonic-spray for producing low Pt loadings membrane electrode assemblies (MEAs) with the catalyst coated substrate (CCS) fabrication technique. The main MEA sub-components (catalyst, membrane and gas diffusion layer (GDL)) are supplied from commercial manufacturers. In this study, high temperature (HT) MEAs with phosphoric acid (PA)-doped poly(2,5-benzimidazole) (AB-PBI) membrane are fabricated and tested under 160 °C, hydrogen and air feed 100 and 250 cc min-1 and ambient pressure conditions. Four different Pt loadings (from 0.138 to 1.208 mg cm-2) are investigated in this study. The experiment data are determined by in-situ electrochemical methods such as polarization curve, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The high Pt loading MEA exhibits higher performance at high voltage operating conditions but lower performances at peak power due to the poor mass transfer. The Pt loading 0.350 mg cm-2 GDE performs the peak power density and peak cathode mass power to 0.339 W cm-2 and 0.967 W mgPt-1, respectively. This work presents impressive cathode mass power and high fuel cell performance for high temperature proton exchange membrane fuel cells (HT-PEMFCs) with low Pt loadings.

Experimental Investigations of the Internal Energy of Molecules Evaporated via Laser-induced Acoustic Desorption into a Fourier-transform Ion Cyclotron Resonance Mass Spectrometer (LIAD/FT-ICR)

PubMed Central

Shea, Ryan C.; Petzold, Christopher J.; Liu, Ji-ang; Kenttämaa, Hilkka I.

2008-01-01

The internal energy of neutral gas-phase organic and biomolecules, evaporated by means of laser-induced acoustic desorption (LIAD) into a Fourier-transform ion cyclotron resonance mass spectrometer (FT-ICR), was investigated through several experimental approaches. The desorbed molecules were demonstrated not to undergo degradation during the desorption process by collecting LIAD-evaporated molecules and subjecting them to analysis by electrospray ionization/quadrupole ion trap mass spectrometry. Previously established gas-phase basicity (GB) values were remeasured for LIAD-evaporated organic molecules and biomolecules with the use of the bracketing method. No endothermic reactions were observed. The remeasured basicity values are in close agreement with the values reported in the literature. The amount of internal energy deposited during LIAD is concluded to be less than a few kcal/mol. Chemical ionization with a series of proton transfer reagents was employed to obtain a breakdown curve for a protonated dipeptide, val-pro, evaporated by LIAD. Comparison of this breakdown curve with a previously published analogous curve obtained by using substrate-assisted laser desorption (SALD) to evaporate the peptide suggests that the molecules evaporated via LIAD have less internal energy than those evaporated via SALD. PMID:17263513

Nanorods on surface of GaN-based thin-film LEDs deposited by post-annealing after photo-assisted chemical etching

NASA Astrophysics Data System (ADS)

Chen, Lung-Chien; Lin, Wun-Wei; Liu, Te-Yu

2017-01-01

This study investigates the optoelectronic characteristics of gallium nitride (GaN)-based thin-film light-emitting diodes (TF-LEDs) that are formed by a two-step transfer process that involves wet etching and post-annealing. In the two-step transfer process, GaN LEDs were stripped from sapphire substrates by the laser lift-off (LLO) method using a KrF laser and then transferred onto ceramic substrates. Ga-K nanorods were formed on the surface of the GaN-based TF-LEDs following photo-assisted chemical etching and photo-enhanced post-annealing at 100 °C for 1 min. As a result, the light output power of GaN-based TF-LEDs with wet etching and post-annealing was over 72% more than that of LEDs that did not undergo these treatments.

Multi-Scale Mass Transfer Processes Controlling Natural Attenuation and Engineered Remediation: An IFRC Focused on Hanford’s 300 Area Uranium Plume

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

Zachara, John M.; Bjornstad, Bruce N.; Christensen, John N.

2010-02-01

The Integrated Field-Scale Subsurface Research Challenge (IFRC) at the Hanford Site 300 Area uranium (U) plume addresses multi-scale mass transfer processes in a complex hydrogeologic setting where groundwater and riverwater interact. A series of forefront science questions on mass transfer are posed for research which relate to the effect of spatial heterogeneities; the importance of scale; coupled interactions between biogeochemical, hydrologic, and mass transfer processes; and measurements and approaches needed to characterize and model a mass-transfer dominated system. The project was initiated in February 2007, with CY 2007 and CY 2008 progress summarized in preceding reports. The site has 35more » instrumented wells, and an extensive monitoring system. It includes a deep borehole for microbiologic and biogeochemical research that sampled the entire thickness of the unconfined 300 A aquifer. Significant, impactful progress has been made in CY 2009 with completion of extensive laboratory measurements on field sediments, field hydrologic and geophysical characterization, four field experiments, and modeling. The laboratory characterization results are being subjected to geostatistical analyses to develop spatial heterogeneity models of U concentration and chemical, physical, and hydrologic properties needed for reactive transport modeling. The field experiments focused on: (1) physical characterization of the groundwater flow field during a period of stable hydrologic conditions in early spring, (2) comprehensive groundwater monitoring during spring to characterize the release of U(VI) from the lower vadose zone to the aquifer during water table rise and fall, (3) dynamic geophysical monitoring of salt-plume migration during summer, and (4) a U reactive tracer experiment (desorption) during the fall. Geophysical characterization of the well field was completed using the down-well Electrical Resistance Tomography (ERT) array, with results subjected to robust, geostatistically constrained inversion analyses. These measurements along with hydrologic characterization have yielded 3D distributions of hydraulic properties that have been incorporated into an updated and increasingly robust hydrologic model. Based on significant findings from the microbiologic characterization of deep borehole sediments in CY 2008, down-hole biogeochemistry studies were initiated where colonization substrates and spatially discrete water and gas samplers were deployed to select wells. The increasingly comprehensive field experimental results, along with the field and laboratory characterization, are leading to a new conceptual model of U(VI) flow and transport in the IFRC footprint and the 300 Area in general, and insights on the microbiological community and associated biogeochemical processes. A significant issue related to vertical flow in the IFRC wells was identified and evaluated during the spring and fall field experimental campaigns. Both upward and downward flows were observed in response to dynamic Columbia River stage. The vertical flows are caused by the interaction of pressure gradients with our heterogeneous hydraulic conductivity field. These impacts are being evaluated with additional modeling and field activities to facilitate interpretation and mitigation. The project moves into CY 2010 with ambitious plans for a drilling additional wells for the IFRC well field, additional experiments, and modeling. This research is part of the ERSP Hanford IFRC at Pacific Northwest National Laboratory.« less