Assisted phytoremediation of Cd-contaminated soil using poplar rooted cuttings

NASA Astrophysics Data System (ADS)

Alizadeh, S.; Zahedi-Amiri, G.; Savaghebi-Firoozabadi, G.; Etemad, V.; Shirvany, A.; Shirmardi, M.

2012-07-01

To investigate the effect of amended substrates on cadmium uptake by one-year old poplar rooted cuttings a pot culture was carried out. Pots were filled with three substrates. Four treatments of Cd supply including were organized. The results showed that higher biomass productions in substrates A and B compare to substrate C, led to an increase total Cd uptake two times more than that in substrate C, at 150 mg kg-1 concentration. Meanwhile maximum total uptake occurred in substrate B at 100 mg kg-1 concentration. Using synthetic chelators such as ethylenediaminetetraacetic acid in order to achieve high removal rate led to increased environmental impacts while they are not expected when such environmental friendly approaches are applied.

Impact of the silicon substrate resistivity and growth condition on the deep levels in Ni-Au/AlN/Si MIS Capacitors

NASA Astrophysics Data System (ADS)

Wang, Chong; Simoen, Eddy; Zhao, Ming; Li, Wei

2017-10-01

Deep levels formed under different growth conditions of a 200 nm AlN buffer layer on B-doped Czochralski Si(111) substrates with different resistivity were investigated by deep-level transient spectroscopy (DLTS) on metal-insulator-semiconductor capacitors. Growth-temperature-dependent Al diffusion in the Si substrate was derived from the free carrier density obtained by capacitance-voltage measurement on samples grown on p- substrates. The DLTS spectra revealed a high concentration of point and extended defects in the p- and p+ silicon substrates, respectively. This indicated a difference in the electrically active defects in the silicon substrate close to the AlN/Si interface, depending on the B doping concentration.

A facile and cost-effective TEM grid approach to design gold nano-structured substrates for high throughput plasmonic sensitive detection of biomolecules.

PubMed

Jia, Kun; Bijeon, Jean Louis; Adam, Pierre Michel; Ionescu, Rodica Elena

2013-02-21

A commercial TEM grid was used as a mask for the creation of extremely well-organized gold micro-/nano-structures on a glass substrate via a high temperature annealing process at 500 °C. The structured substrate was (bio)functionalized and used for the high throughput LSPR immunosensing of different concentrations of a model protein named bovine serum albumin.

Investigations of different doping concentration of phosphorus and boron into silicon substrate on the variable temperature Raman characteristics

NASA Astrophysics Data System (ADS)

Li, Xiaoli; Ding, Kai; Liu, Jian; Gao, Junxuan; Zhang, Weifeng

2018-01-01

Different doped silicon substrates have different device applications and have been used to fabricate solar panels and large scale integrated circuits. The thermal transport in silicon substrates are dominated by lattice vibrations, doping type, and doping concentration. In this paper, a variable-temperature Raman spectroscopic system is applied to record the frequency and linewidth changes of the silicon peak at 520 cm-1 in five chips of silicon substrate with different doping concentration of phosphorus and boron at the 83K to 1473K temperature range. The doping has better heat sensitive to temperature on the frequency shift over the low temperature range from 83K to 300K but on FWHM in high temperature range from 300K to 1473K. The results will be helpful for fundamental study and practical applications of silicon substrates.

Toward nanomolar detection by NMR through SABRE hyperpolarization.

PubMed

Eshuis, Nan; Hermkens, Niels; van Weerdenburg, Bram J A; Feiters, Martin C; Rutjes, Floris P J T; Wijmenga, Sybren S; Tessari, Marco

2014-02-19

SABRE is a nuclear spin hyperpolarization technique based on the reversible association of a substrate molecule and para-hydrogen (p-H2) to a metal complex. During the lifetime of such a complex, generally fractions of a second, the spin order of p-H2 is transferred to the nuclear spins of the substrate molecule via a transient scalar coupling network, resulting in strongly enhanced NMR signals. This technique is generally applied at relatively high concentrations (mM), in large excess of substrate with respect to metal complex. Dilution of substrate ligands below stoichiometry results in progressive decrease of signal enhancement, which precludes the direct application of SABRE to the NMR analysis of low concentration (μM) solutions. Here, we show that the efficiency of SABRE at low substrate concentrations can be restored by addition of a suitable coordinating ligand to the solution. The proposed method allowed NMR detection below 1 μM in a single scan.

Defect studies of thin ZnO films prepared by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Vlček, M.; Čížek, J.; Procházka, I.; Novotný, M.; Bulíř, J.; Lančok, J.; Anwand, W.; Brauer, G.; Mosnier, J.-P.

2014-04-01

Thin ZnO films were grown by pulsed laser deposition on four different substrates: sapphire (0 0 0 1), MgO (1 0 0), fused silica and nanocrystalline synthetic diamond. Defect studies by slow positron implantation spectroscopy (SPIS) revealed significantly higher concentration of defects in the studied films when compared to a bulk ZnO single crystal. The concentration of defects in the films deposited on single crystal sapphire and MgO substrates is higher than in the films deposited on amorphous fused silica substrate and nanocrystalline synthetic diamond. Furthermore, the effect of deposition temperature on film quality was investigated in ZnO films deposited on synthetic diamond substrates. Defect studies performed by SPIS revealed that the concentration of defects firstly decreases with increasing deposition temperature, but at too high deposition temperatures it increases again. The lowest concentration of defects was found in the film deposited at 450° C.

Electrical properties of n-type GaSb substrates and p-type GaSb buffer layers for InAs/InGaSb superlattice infrared detectors

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

Mitchel, W. C., E-mail: William.Mitchel.1@us.af.mil; Haugan, H. J.; Mou, Shin

2015-09-15

Lightly doped n-type GaSb substrates with p-type GaSb buffer layers are the preferred templates for growth of InAs/InGaSb superlattices used in infrared detector applications because of relatively high infrared transmission and a close lattice match to the superlattices. We report here temperature dependent resistivity and Hall effect measurements of bare substrates and substrate-p-type buffer layer structures grown by molecular beam epitaxy. Multicarrier analysis of the resistivity and Hall coefficient data demonstrate that high temperature transport in the substrates is due to conduction in both the high mobility zone center Γ band and the low mobility off-center L band. High overallmore » mobility values indicate the absence of close compensation and that improved infrared and transport properties were achieved by a reduction in intrinsic acceptor concentration. Standard transport measurements of the undoped buffer layers show p-type conduction up to 300 K indicating electrical isolation of the buffer layer from the lightly n-type GaSb substrate. However, the highest temperature data indicate the early stages of the expected p to n type conversion which leads to apparent anomalously high carrier concentrations and lower than expected mobilities. Data at 77 K indicate very high quality buffer layers.« less

Alcohol-to-acid ratio and substrate concentration affect product structure in chain elongation reactions initiated by unacclimatized inoculum.

PubMed

Liu, Yuhao; Lü, Fan; Shao, Liming; He, Pinjing

2016-10-01

The objective of the study was to investigate whether the ratio of ethanol to acetate affects yield and product structure in chain elongation initiated by unacclimatized mixed cultures. The effect of varying the substrate concentration, while maintaining the same ratio of alcohol to acid, was also investigated. With a high substrate concentration, an alcohol to acid ratio >2:1 provided sufficient electron donor capacity for the chain elongation reaction. With an ethanol to acetate ratio of 3:1 (300mM total carbon), the highest n-caproate concentration (3033±98mg/L) was achieved during the stable phase of the reaction. A lower substrate concentration (150mM total carbon) gave a lower yield of products and led to reduced carbon transformation efficiency compared with other reaction conditions. The use of unacclimatized inoculum in chain elongation can produce significant amounts of odd-carbon-number carboxylates as a result of protein hydrolysis. Copyright © 2016 Elsevier Ltd. All rights reserved.

D-malate production by permeabilized Pseudomonas pseudoalcaligenes; optimization of conversion and biocatalyst productivity.

PubMed

Michielsen, M J; Frielink, C; Wijffels, R H; Tramper, J; Beeftink, H H

2000-04-14

For the development of a continuous process for the production of solid D-malate from a Ca-maleate suspension by permeabilized Pseudomonas pseudoalcaligenes, it is important to understand the effect of appropriate process parameters on the stability and activity of the biocatalyst. Previously, we quantified the effect of product (D-malate2 -) concentration on both the first-order biocatalyst inactivation rate and on the biocatalytic conversion rate. The effects of the remaining process parameters (ionic strength, and substrate and Ca2 + concentration) on biocatalyst activity are reported here. At (common) ionic strengths below 2 M, biocatalyst activity was unaffected. At high substrate concentrations, inhibition occurred. Ca2+ concentration did not affect biocatalyst activity. The kinetic parameters (both for conversion and inactivation) were determined as a function of temperature by fitting the complete kinetic model, featuring substrate inhibition, competitive product inhibition and first-order irreversible biocatalyst inactivation, at different temperatures simultaneously through three extended data sets of substrate concentration versus time. Temperature affected both the conversion and inactivation parameters. The final model was used to calculate the substrate and biocatalyst costs per mmol of product in a continuous system with biocatalyst replenishment and biocatalyst recycling. Despite the effect of temperature on each kinetic parameter separately, the overall effect of temperature on the costs was found to be negligible (between 293 and 308 K). Within pertinent ranges, the sum of the substrate and biocatalyst costs per mmol of product was calculated to decrease with the influent substrate concentration and the residence time. The sum of the costs showed a minimum as a function of the influent biocatalyst concentration.

Lactate Dehydrogenase Catalysis: Roles of Keto, Hydrated, and Enol Pyruvate

ERIC Educational Resources Information Center

Meany, J. E.

2007-01-01

Many carbonyl substrates of oxidoreductase enzymes undergo hydration and enolization so that these substrate systems are partitioned between keto, hydrated (gem-diol), and enol forms in aqueous solution. Some oxidoreductase enzymes are subject to inhibition by high concentrations of substrate. For such enzymes, two questions arise pertaining to…

Performance-Enhancing Methods for Au Film over Nanosphere Surface-Enhanced Raman Scattering Substrate and Melamine Detection Application

PubMed Central

Wang, Jun Feng; Wu, Xue Zhong; Xiao, Rui; Dong, Pei Tao; Wang, Chao Guang

2014-01-01

A new high-performance surface-enhanced Raman scattering (SERS) substrate with extremely high SERS activity was produced. This SERS substrate combines the advantages of Au film over nanosphere (AuFON) substrate and Ag nanoparticles (AgNPs). A three order enhancement of SERS was observed when Rhodamine 6G (R6G) was used as a probe molecule to compare the SERS effects of the new substrate and commonly used AuFON substrate. These new SERS substrates can detect R6G down to 1 nM. The new substrate was also utilized to detect melamine, and the limit of detection (LOD) is 1 ppb. A linear relationship was also observed between the SERS intensity at Raman peak 682 cm−1 and the logarithm of melamine concentrations ranging from 10 ppm to 1 ppb. This ultrasensitive SERS substrate is a promising tool for detecting trace chemical molecules because of its simple and effective fabrication procedure, high sensitivity and high reproducibility of the SERS effect. PMID:24886913

Performance-enhancing methods for Au film over nanosphere surface-enhanced Raman scattering substrate and melamine detection application.

PubMed

Wang, Jun Feng; Wu, Xue Zhong; Xiao, Rui; Dong, Pei Tao; Wang, Chao Guang

2014-01-01

A new high-performance surface-enhanced Raman scattering (SERS) substrate with extremely high SERS activity was produced. This SERS substrate combines the advantages of Au film over nanosphere (AuFON) substrate and Ag nanoparticles (AgNPs). A three order enhancement of SERS was observed when Rhodamine 6G (R6G) was used as a probe molecule to compare the SERS effects of the new substrate and commonly used AuFON substrate. These new SERS substrates can detect R6G down to 1 nM. The new substrate was also utilized to detect melamine, and the limit of detection (LOD) is 1 ppb. A linear relationship was also observed between the SERS intensity at Raman peak 682 cm(-1) and the logarithm of melamine concentrations ranging from 10 ppm to 1 ppb. This ultrasensitive SERS substrate is a promising tool for detecting trace chemical molecules because of its simple and effective fabrication procedure, high sensitivity and high reproducibility of the SERS effect.

Impact of temperature and substrate concentration on degradation rates of acetate, propionate and hydrogen and their links to microbial community structure.

PubMed

Zhao, Jing; Westerholm, Maria; Qiao, Wei; Yin, Dongmin; Bi, Shaojie; Jiang, Mengmeng; Dong, Renjie

2018-05-01

The present study investigates the conversion of acetate, propionate and hydrogen consumption linked to the microbial community structure and related to temperature and substrate concentration. Biogas reactors were continuously fed with coffee powder (20 g-COD/L) or acetate (20, 40, and 60 g-COD/L) and operated for 193 days at 37 °C or 55 °C conditions. Starting HRT was 23 days which was then reduced to 7 days. The kinetics of acetate and propionate degradation and hydrogen consumption rates were measured in batch assays. At HRT 7 days, the degradation rate of propionate was higher in thermophilic batches, while acetate degradation rate was higher at mesophilic conditions. The gaseous hydrogen consumption in acetate reactors increased proportionally with temperature and substrate concentration, while the dissolved hydrogen was not affected. The relative high abundance of hydrogentrophic methanogens indicated that the methanogenesis was directed towards the syntrophic acetate oxidation pathway at high acetate concentration and high temperature. Copyright © 2018 Elsevier Ltd. All rights reserved.

Continuous process for singlet oxygenation of hydrophobic substrates in microemulsion using a pervaporation membrane.

PubMed

Caron, Laurent; Nardello, Véronique; Mugge, José; Hoving, Erik; Alsters, Paul L; Aubry, Jean-Marie

2005-02-15

Chemically generated singlet oxygen (1O2, 1Deltag) is able to oxidize a great deal of hydrophobic substrates from molybdate-catalyzed hydrogen peroxide decomposition, provided a suitable reaction medium such as a microemulsion system is used. However, high substrate concentrations or poorly reactive organics require large amounts of H2O2 that generate high amounts of water and thus destabilize the system. We report results obtained on combining dark singlet oxygenation of hydrophobic substrates in microemulsions with a pervaporation membrane process. To avoid composition alterations after addition of H2O2 during the peroxidation, the reaction mixture circulates through a ceramic membrane module that enables a partial and selective dewatering of the microemulsion. Optimization phase diagrams of sodium molybdate/water/alcohol/anionic surfactant/organic solvent have been elaborated to maximize the catalyst concentration and therefore the reaction rate. The membrane selectivity towards the mixture constituents has been investigated showing that a high retention is observed for the catalyst, for organic solvents and hydrophobic substrates, but not for n-propanol (cosurfactant) and water. The efficiency of such a process is illustrated with the peroxidation of a poorly reactive substrate, viz., beta-pinene.

Iron [Fe(0)]-rich substrate based on iron-carbon micro-electrolysis for phosphorus adsorption in aqueous solutions.

PubMed

Deng, Shihai; Li, Desheng; Yang, Xue; Xing, Wei; Li, Jinlong; Zhang, Qi

2017-02-01

The phosphorus (P) adsorption properties of an iron [Fe(0)]-rich substrate (IRS) composed of iron scraps and activated carbon were investigated based on iron-carbon micro-electrolysis (IC-ME) and compared to the substrates commonly used in constructed wetlands (CWs) to provide an initial characterization of the [Fe(0)]-rich substrate. The results showed that P was precipitated by Fe(III) dissolved from the galvanic cell reactions in the IRS and the reaction was suppressed by the pH and stopped when the pH exceeded 8.90 ± 0.09. The adsorption capacity of the IRS decreased by only 4.6% in the second round of adsorption due to Fe(0) consumption in the first round. Substrates with high Ca- and Mg-oxide contents and high Fe- and Al-oxide contents had higher P adsorption capacities at high and low pH values, respectively. Substrates containing high Fe and Al concentrations and low Ca concentrations were more resistant to decreases in the P adsorption capacity resulting from organic matter (OM) accumulation. The IRS with an iron scrap to activated carbon volume ratio of 3:2 resulted in the highest P adsorption capacity (9.34 ± 0.14 g P kg -1 ), with minimal pH change and strong adaptability to OM accumulation. The Fe(0)-rich substrate has the considerable potential for being used as a CW substrate. Copyright © 2016 Elsevier Ltd. All rights reserved.

Systems analysis of effector caspase activation and its control by X-linked inhibitor of apoptosis protein

PubMed Central

Rehm, Markus; Huber, Heinrich J; Dussmann, Heiko; Prehn, Jochen H M

2006-01-01

Activation of effector caspases is a final step during apoptosis. Single-cell imaging studies have demonstrated that this process may occur as a rapid, all-or-none response, triggering a complete substrate cleavage within 15 min. Based on biochemical data from HeLa cells, we have developed a computational model of apoptosome-dependent caspase activation that was sufficient to remodel the rapid kinetics of effector caspase activation observed in vivo. Sensitivity analyses predicted a critical role for caspase-3-dependent feedback signalling and the X-linked-inhibitor-of-apoptosis-protein (XIAP), but a less prominent role for the XIAP antagonist Smac. Single-cell experiments employing a caspase fluorescence resonance energy transfer substrate verified these model predictions qualitatively and quantitatively. XIAP was predicted to control this all-or-none response, with concentrations as high as 0.15 μM enabling, but concentrations >0.30 μM significantly blocking substrate cleavage. Overexpression of XIAP within these threshold concentrations produced cells showing slow effector caspase activation and submaximal substrate cleavage. Our study supports the hypothesis that high levels of XIAP control caspase activation and substrate cleavage, and may promote apoptosis resistance and sublethal caspase activation in vivo. PMID:16932741

Bioethanol production: an integrated process of low substrate loading hydrolysis-high sugars liquid fermentation and solid state fermentation of enzymatic hydrolysis residue.

PubMed

Chu, Qiulu; Li, Xin; Ma, Bin; Xu, Yong; Ouyang, Jia; Zhu, Junjun; Yu, Shiyuan; Yong, Qiang

2012-11-01

An integrated process of enzymatic hydrolysis and fermentation was investigated for high ethanol production. The combination of enzymatic hydrolysis at low substrate loading, liquid fermentation of high sugars concentration and solid state fermentation of enzymatic hydrolysis residue was beneficial for conversion of steam explosion pretreated corn stover to ethanol. The results suggested that low substrate loading hydrolysis caused a high enzymatic hydrolysis yield; the liquid fermentation of about 200g/L glucose by Saccharomyces cerevisiae provided a high ethanol concentration which could significantly decrease cost of the subsequent ethanol distillation. A solid state fermentation of enzymatic hydrolysis residue was combined, which was available to enhance ethanol production and cellulose-to-ethanol conversion. The results of solid state fermentation demonstrated that the solid state fermentation process accompanied by simultaneous saccharification and fermentation. Copyright © 2012 Elsevier Ltd. All rights reserved.

Vacuum-deposited polymer/silver reflector material

NASA Astrophysics Data System (ADS)

Affinito, John D.; Martin, Peter M.; Gross, Mark E.; Bennett, Wendy D.

1994-09-01

Weatherable, low cost, front surface, solar reflectors on flexible substrates would be highly desirable for lamination to solar concentrator panels. The method to be described in this paper may permit such reflector material to be fabricated for less the 50$CNT per square foot. Vacuum deposited Polymer/Silver/Polymer reflectors and Fabry-Perot interference filters were fabricated in a vacuum web coating operation on polyester substrates. Reflectivities were measured in the wavelength range from .4 micrometers to .8 micrometers . It is hoped that a low cost substrate can be used with the substrate laminated to the concentrator and the weatherable acrylic polymer coating facing the sun. This technique should be capable of deposition line speeds approaching 1500 linear feet/minute2. Central to this technique is a new vacuum deposition process for the high rate deposition of polymer films. This polymer process involves the flash evaporation of an acrylic monomer onto a moving substrate. The monomer is subsequently cured by an electron beam or ultraviolet light. This high speed polymer film deposition process has been named the PML process- for Polymer Multi- Layer.

Kinetics of Substrate Biodegradation under the Cumulative Effects of Bioavailability and Self-Inhibition.

PubMed

Gharasoo, Mehdi; Centler, Florian; Van Cappellen, Philippe; Wick, Lukas Y; Thullner, Martin

2015-05-05

Microbial degradation is an important process in many environments controlling for instance the cycling of nutrients or the biodegradation of contaminants. At high substrate concentrations toxic effects may inhibit the degradation process. Bioavailability limitations of a degradable substrate can therefore either improve the overall dynamics of degradation by softening the contaminant toxicity effects to microorganisms, or slow down the biodegradation by reducing the microbial access to the substrate. Many studies on biodegradation kinetics of a self-inhibitive substrate have mainly focused on physiological responses of the bacteria to substrate concentration levels without considering the substrate bioavailability limitations rising from different geophysical and geochemical dynamics at pore-scale. In this regard, the role of bioavailability effects on the kinetics of self-inhibiting substrates is poorly understood. In this study, we theoretically analyze this role and assess the interactions between self-inhibition and mass transfer-limitations using analytical/numerical solutions, and show the findings practical relevance for a simple model scenario. Although individually self-inhibition and mass-transfer limitations negatively impact biodegradation, their combined effect may enhance biodegradation rates above a concentration threshold. To our knowledge, this is the first theoretical study describing the cumulative effects of the two mechanisms together.

H.sub.2O doped WO.sub.3, ultra-fast, high-sensitivity hydrogen sensors

DOEpatents

Liu, Ping [Denver, CO; Tracy, C Edwin [Golden, CO; Pitts, J Roland [Lakewood, CO; Lee, Se-Hee [Lakewood, CO

2011-03-22

An ultra-fast response, high sensitivity structure for optical detection of low concentrations of hydrogen gas, comprising: a substrate; a water-doped WO.sub.3 layer coated on the substrate; and a palladium layer coated on the water-doped WO.sub.3 layer.

In vitro fermentation of total mixed diets differing in concentrate proportion: relative effects of inocula and substrates.

PubMed

Serment, Amélie; Giger-Reverdin, Sylvie; Schmidely, Philippe; Dhumez, Ophélie; Broudiscou, Laurent P; Sauvant, Daniel

2016-01-15

In vitro techniques are used to predict ruminant feedstuff values or characterise rumen fermentation. As the results are influenced by several factors, such as the relative effects of inocula and substrates, this study aimed to examine in vitro incubation of two total mixed rations (substrates) differing in their proportion of concentrate [low (L): 350 g kg(-1) vs. high (H): 700 g kg(-1)] incubated in inocula provided by goats fed either a L or a H diet. Gas production and composition in carbon dioxide (CO2), methane (CH4 ) and hydrogen (H2), volatile fatty acids (VFAs), soluble carbohydrates (SCs) and ammonia (NH3) concentrations, and pH of the fermentation fluid were measured. In comparison with the L inoculum and L substrate, the H ones produced more CO2 and CH4 gas, which led to higher SCs and VFA concentrations, and lower acetate-to-propionate ratio and NH3 concentration, with a predominant effect of the inoculum. The effects of the inocula and of the substrates were additive using donor animals adapted to the diets. © 2015 Society of Chemical Industry.

High ethanol producing derivatives of Thermoanaerobacter ethanolicus

DOEpatents

Ljungdahl, L.G.; Carriera, L.H.

1983-05-24

Derivatives of the newly discovered microorganism Thermoanaerobacter ethanolicus which under anaerobic and thermophilic conditions continuously ferment substrates such as starch, cellobiose, glucose, xylose and other sugars to produce recoverable amounts of ethanol solving the problem of fermentations yielding low concentrations of ethanol using the parent strain of the microorganism Thermoanaerobacter ethanolicus are disclosed. These new derivatives are ethanol tolerant up to 10% (v/v) ethanol during fermentation. The process includes the use of an aqueous fermentation medium, containing the substrate at a substrate concentration greater than 1% (w/v).

High ethanol producing derivatives of Thermoanaerobacter ethanolicus

DOEpatents

Ljungdahl, Lars G.; Carriera, Laura H.

1983-01-01

Derivatives of the newly discovered microorganism Thermoanaerobacter ethanolicus which under anaerobic and thermophilic conditions continuously ferment substrates such as starch, cellobiose, glucose, xylose and other sugars to produce recoverable amounts of ethanol solving the problem of fermentations yielding low concentrations of ethanol using the parent strain of the microorganism Thermoanaerobacter ethanolicus are disclosed. These new derivatives are ethanol tolerant up to 10% (v/v) ethanol during fermentation. The process includes the use of an aqueous fermentation medium, containing the substrate at a substrate concentration greater than 1% (w/v).

Fish protein substrates can substitute effectively for poultry by-product meal when incorporated in high-quality senior dog diets.

PubMed

Zinn, K E; Hernot, D C; Fastinger, N D; Karr-Lilienthal, L K; Bechtel, P J; Swanson, K S; Fahey, G C

2009-08-01

An experiment was conducted to analytically define several novel fish substrates and determine the effects of feeding diets containing these substrates on total tract nutrient digestibilities and on immune status of senior dogs. The control diet contained poultry by-product meal while test diets contained 20% milt meal (MM), pink salmon hydrolysate (PSH) and white fish meal (WFM) added at the expense of poultry by-product meal. Concentrations of lymphocytes positive for CD3, CD4, CD8 and CD21 cell-surface markers and immunoglobulin concentrations were measured. Gene expression of cytokines tumour necrosis factor (TNF)-, interleukin (IL)-6, interferon (IFN)-, IL-10 and transforming growth factor (TGF)-β was determined by quantitative real-time polymerase chain reaction. Major compositional differences were noted among fish substrates but apparent nutrient digestibility coefficients and immune indices were not affected by treatment. Fish protein substrates were found to be effective substitutes for poultry by-product meal, providing diets of high nutritive value for senior dogs.

Ultra-high sensitive substrates for surface enhanced Raman scattering, made of 3 nm gold nanoparticles embedded on SiO2 nanospheres

NASA Astrophysics Data System (ADS)

Phatangare, A. B.; Dhole, S. D.; Dahiwale, S. S.; Bhoraskar, V. N.

2018-05-01

The surface properties of substrates made of 3 nm gold nanoparticles embedded on SiO2 nanospheres enabled fingerprint detection of thiabendazole (TBZ), crystal violet (CV) and 4-Aminothiophenol (4-ATP) at an ultralow concentration of ∼10-18 M by surface enhanced Raman spectroscopy (SERS). Gold nanoparticles of an average size of ∼3 nm were synthesized and simultaneously embedded on SiO2 nanospheres by the electron irradiation method. The substrates made from the 3 nm gold nanoparticles embedded on SiO2 nanospheres were successfully used for recording fingerprint SERS spectra of TBZ, CV and 4-ATP over a wide range of concentrations from 10-6 M to 10-18 M using 785 nm laser. The unique features of these substrates are roughness near the surface due to the inherent structural defects of 3 nm gold nanoparticles, nanogaps of ≤ 1 nm between the embedded nanoparticles and their high number. These produced an abundance of nanocavities which act as active centers of hot-spots and provided a high electric field at the reporter molecules and thus an enhancement factor required to record the SERS spectra at ultra low concentration of 10-18 M. The SERS spectra recorded by the substrates of 4 nm and 6 nm gold nanoparticles are discussed.

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.

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

PubMed

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

2018-02-12

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

Zeta potential of microfluidic substrates: 1. Theory, experimental techniques, and effects on separations.

PubMed

Kirby, Brian J; Hasselbrink, Ernest F

2004-01-01

This paper summarizes theory, experimental techniques, and the reported data pertaining to the zeta potential of silica and silicon with attention to use as microfluidic substrate materials, particularly for microchip chemical separations. Dependence on cation concentration, buffer and cation type, pH, cation valency, and temperature are discussed. The Debye-Hückel limit, which is often correctly treated as a good approximation for describing the ion concentration in the double layer, can lead to serious errors if it is extended to predict the dependence of zeta potential on the counterion concentration. For indifferent univalent electrolytes (e.g., sodium and potassium), two simple scalings for the dependence of zeta potential on counterion concentration can be derived in high- and low-zeta limits of the nonlinear Poisson-Boltzman equation solution in the double layer. It is shown that for most situations relevant to microchip separations, the high-zeta limit is most applicable, leading to the conclusion that the zeta potential on silica substrates is approximately proportional to the logarithm of the molar counterion concentration. The zeta vs. pH dependence measurements from several experiments are compared by normalizing the zeta based on concentration.

Resonance shifting: A simple, all-optical method for circumventing the reabsorption problem in luminescent concentrators

NASA Astrophysics Data System (ADS)

Giebink, Noel; Wiederrecht, Gary; Wasielewski, Michael

2011-03-01

Luminescent concentrators (LSCs) were developed over three decades ago as a simple route to obtain high concentration ratio for photovoltaic cells without tracking the sun. In principle, high concentration ratios 100 are possible for commonly used chromophores. In practice, however, there is typically an overlap between the chromophore absorption and emission spectra that, although small, ultimately leads to unacceptable reabsorption losses, limiting the concentration ratio to ~ 10 and hence the utility of LSCs to date. We introduce a simple, all-optical means of avoiding reabsorption loss by ``resonance shifting'' from a bilayer cavity that consists of an absorber/emitter waveguide lying upon a low refractive index layer supported by a transparent substrate. Emission is evanescently coupled into the substrate at sharply defined angles and hence, by varying the cavity thickness over the device area, the original absorption resonance can be avoided at each bounce, allowing for extremely low propagation loss to the substrate edges and hence an increase in the optical concentration ratio. We validate this concept for absorber/emitter layers composed of both a typical luminescent polymer and inorganic semiconductor nanocrystals, demonstrating near-lossless propagation in each case.

Paper-basd surface enhanced Raman spectroscopy of pnenobarbital sodium for point-of-care therapeutic drug monitoring

NASA Astrophysics Data System (ADS)

Yokoyama, Moe; Yamada, Kenji; Nishimura, Takahiro; Kido, Michiko; Jeong, Hieyong; Ohno, Yuko

2015-03-01

Therapeutic drug monitoring (TDM) contributes to safe and effective pharmacotherapy in clinical fields. A simple, rapid, low-cost, and minimally-invasive drug measurement method attracts much interest for point-of-care TDM. Tear fluids can be collected minimally-invasively compared to blood sampling and there is a correlation between a drug concentration in tears and that in bloods. Surface enhanced Raman spectroscopy (SERS) with paper-based substrate is useful for point-of-care TDM owing to inexpensiveness and high-sensitivity. Paper is also a safe tear collection tool. Then we are studying on a paper-based SERS of tear specimen for point-of-care TDM. In this paper, to improve sensitivity in measuring drug concentration in tear fluids, we fabricated a SERS substrate by coating gold nano-rods on a paper substrate and evaluated whether the fabricated substrate can enhance Raman scattering. Sodium phenobarbital (PB), an anti-convulsant agent, was used as a target. In experiment, the fabricated substrate indicated the lower detection limit of PB in a solution than a plain paper substrate. This result showed the potential of the paper based SERS substrate to measure drug concentration in tears simply and inexpensively.

COSIM: A Finite-Difference Computer Model to Predict Ternary Concentration Profiles Associated With Oxidation and Interdiffusion of Overlay-Coated Substrates

NASA Technical Reports Server (NTRS)

Nesbitt, James A.

2001-01-01

A finite-difference computer program (COSIM) has been written which models the one-dimensional, diffusional transport associated with high-temperature oxidation and interdiffusion of overlay-coated substrates. The program predicts concentration profiles for up to three elements in the coating and substrate after various oxidation exposures. Surface recession due to solute loss is also predicted. Ternary cross terms and concentration-dependent diffusion coefficients are taken into account. The program also incorporates a previously-developed oxide growth and spalling model to simulate either isothermal or cyclic oxidation exposures. In addition to predicting concentration profiles after various oxidation exposures, the program can also be used to predict coating life based on a concentration dependent failure criterion (e.g., surface solute content drops to 2%). The computer code is written in FORTRAN and employs numerous subroutines to make the program flexible and easily modifiable to other coating oxidation problems.

Kinetic modeling of lactic acid production from batch submerged fermentation of cheese whey

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

Tango, M.S.A.; Ghaly, A.E.

1999-12-01

A kinetic model for the production of lactic acid through batch submerged fermentation of cheese whey using Lactobacillus helveticus was developed. The model accounts for the effect of substrate limitation, substrate inhibition, lactic acid inhibition, maintenance energy and cell death on the cell growth, substrate utilization, and lactic acid production during the fermentation process. The model was evaluated using experimental data from Tango and Ghaly (1999). The predicted results obtained from the model compared well with experimental (R{sup 2} = 0.92--0.98). The model was also used to investigate the effect of the initial substrate concentration on the lag period, fermentationmore » time, specific growth rate, and cell productivity during batch fermentation. The maximum specific growth rate ({micro}{sub m}), the saturation constant (K{sub S}), the substrate inhibition constant (K{sub IS}), and the lactic acid inhibition constant (K{sub IP}) were found to be 0.25h{sup {minus}1}, 0.9 g/L, 250.0 g/L, and 60.0 g/L, respectively. High initial lactose concentration in cheese whey reduced both the specific growth rate and substrate utilization rate due to the substrate inhibition phenomenon. The maximum lactic acid production occurred at about 100 g/L initial lactose concentration after 40 h of fermentation. The maximum lactic acid concentration above which Lactobacillus helveticus did not grow was found to be 80.0 g/L.« less

Adaptation of the xylose fermenting yeast Saccharomyces cerevisiae F12 for improving ethanol production in different fed-batch SSF processes.

PubMed

Tomás-Pejó, E; Ballesteros, M; Oliva, J M; Olsson, L

2010-11-01

An efficient fermenting microorganism for bioethanol production from lignocellulose is highly tolerant to the inhibitors released during pretreatment and is able to ferment efficiently both glucose and xylose. In this study, directed evolution was employed to improve the xylose fermenting Saccharomyces cerevisiae F12 strain for bioethanol production at high substrate loading. Adapted and parental strains were compared with respect to xylose consumption and ethanol production. Adaptation led to an evolved strain more tolerant to the toxic compounds present in the medium. When using concentrated prehydrolysate from steam-pretreated wheat straw with high inhibitor concentration, an improvement of 65 and 20% in xylose consumption and final ethanol concentration, respectively, were achieved using the adapted strain. To address the need of high substrate loadings, fed-batch SSF experiments were performed and an ethanol concentration as high as 27.4 g/l (61% of the theoretical) was obtained with 11.25% (w/w) of water insoluble solids (WIS).

Single-molecule imaging at high fluorophore concentrations by local activation of dye

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

Geertsema, Hylkje J.; Mangel, Walter F.; Schulte, Aartje C.

Single-molecule fluorescence microscopy is a powerful approach to observe biomolecular interactions with high spatial and temporal resolution. Detecting fluorescent signals from individual, labeled proteins above high levels of background fluorescence remains challenging, however. For this reason, the concentrations of labeled proteins in in vitro assays are often kept low compared to their in vivo concentrations. Here, we present a new fluorescence imaging technique by which single fluorescent molecules can be observed in real time at high, physiologically relevant concentrations. The technique requires a protein and its macromolecular substrate to be labeled each with a different fluorophore. Then, making use ofmore » short-distance energy-transfer mechanisms, the fluorescence from only those proteins bound to their substrate are selectively activated. This approach is demonstrated by labeling a DNA substrate with an intercalating stain, exciting the stain, and using energy transfer from the stain to activate the fluorescence of only those labeled DNA-binding proteins bound to the DNA. Such an experimental design allowed us to observe the sequence-independent interaction of Cy5-labeled interferon-inducible protein 16 (IFI16) with DNA and the sliding via one-dimensional diffusion of Cy5-labeled adenovirus protease (pVIc-AVP) on DNA in the presence of a background of hundreds of nM Cy5 fluorophore.« less

Single-molecule imaging at high fluorophore concentrations by local activation of dye

DOE PAGES

Geertsema, Hylkje J.; Mangel, Walter F.; Schulte, Aartje C.; ...

2015-02-17

Single-molecule fluorescence microscopy is a powerful approach to observe biomolecular interactions with high spatial and temporal resolution. Detecting fluorescent signals from individual, labeled proteins above high levels of background fluorescence remains challenging, however. For this reason, the concentrations of labeled proteins in in vitro assays are often kept low compared to their in vivo concentrations. Here, we present a new fluorescence imaging technique by which single fluorescent molecules can be observed in real time at high, physiologically relevant concentrations. The technique requires a protein and its macromolecular substrate to be labeled each with a different fluorophore. Then, making use ofmore » short-distance energy-transfer mechanisms, the fluorescence from only those proteins bound to their substrate are selectively activated. This approach is demonstrated by labeling a DNA substrate with an intercalating stain, exciting the stain, and using energy transfer from the stain to activate the fluorescence of only those labeled DNA-binding proteins bound to the DNA. Such an experimental design allowed us to observe the sequence-independent interaction of Cy5-labeled interferon-inducible protein 16 (IFI16) with DNA and the sliding via one-dimensional diffusion of Cy5-labeled adenovirus protease (pVIc-AVP) on DNA in the presence of a background of hundreds of nM Cy5 fluorophore.« less

Effects on transport of rapidly penetrating, competing substrates: activation and inhibition of the choline carrier in erythrocytes by imidazole.

PubMed

Devés, R; Krupka, R M

1987-01-01

The properties of the choline transport system are fundamentally altered in saline solution containing 5 mM imidazole buffer instead of 5 mM phosphate: (i) The system no longer exhibits accelerated exchange. (ii) Choline in the external compartment fails to increase the rate of inactivation of the carrier by N-ethylmaleimide. (iii) Depending on the relative concentrations of choline and imidazole, transport may be activated or inhibited. The maximum rates are increased more than fivefold by imidazole, but at moderate substrate concentrations activation is observed with low concentrations of imidazole and inhibition with high concentrations. (iv) The imidazole effect is asymmetric, there being a greater tendency to activate exit than entry. All this behavior is predicted by the carrier model if imidazole is a substrate of the choline carrier having a high maximum transport rate but a relatively low affinity, and if imidazole rapidly enters the cell by simple diffusion, so that it can add to carrier sites on both sides of the membrane. Addition at the cis side inhibits, and at the trans side activates. According to the carrier model, asymmetry is a necessary consequence of the potassium ion gradient in red cells, potassium ion being another substrate of the choline system.

Temporal Microbial Community Dynamics in Microbial Electrolysis Cells – Influence of Acetate and Propionate Concentration

PubMed Central

Hari, Ananda Rao; Venkidusamy, Krishnaveni; Katuri, Krishna P.; Bagchi, Samik; Saikaly, Pascal E.

2017-01-01

Microbial electrolysis cells (MECs) are widely considered as a next generation wastewater treatment system. However, fundamental insight on the temporal dynamics of microbial communities associated with MEC performance under different organic types with varied loading concentrations is still unknown, nevertheless this knowledge is essential for optimizing this technology for real-scale applications. Here, the temporal dynamics of anodic microbial communities associated with MEC performance was examined at low (0.5 g COD/L) and high (4 g COD/L) concentrations of acetate or propionate, which are important intermediates of fermentation of municipal wastewaters and sludge. The results showed that acetate-fed reactors exhibited higher performance in terms of maximum current density (I: 4.25 ± 0.23 A/m2), coulombic efficiency (CE: 95 ± 8%), and substrate degradation rate (98.8 ± 1.2%) than propionate-fed reactors (I: 2.7 ± 0.28 A/m2; CE: 68 ± 9.5%; substrate degradation rate: 84 ± 13%) irrespective of the concentrations tested. Despite of the repeated sampling of the anodic biofilm over time, the high-concentration reactors demonstrated lower and stable performance in terms of current density (I: 1.1 ± 0.14 to 4.2 ± 0.21 A/m2), coulombic efficiency (CE: 44 ± 4.1 to 103 ± 7.2%) and substrate degradation rate (64.9 ± 6.3 to 99.7 ± 0.5%), while the low-concentration reactors produced higher and dynamic performance (I: 1.1 ± 0.12 to 4.6 ± 0.1 A/m2; CE: 52 ± 2.5 to 105 ± 2.7%; substrate degradation rate: 87.2 ± 0.2 to 99.9 ± 0.06%) with the different substrates tested. Correlating reactor’s performance with temporal dynamics of microbial communities showed that relatively similar anodic microbial community composition but with varying relative abundances was observed in all the reactors despite differences in the substrate and concentrations tested. Particularly, Geobacter was the predominant bacteria on the anode biofilm of all MECs over time suggesting its possible role in maintaining functional stability of MECs fed with low and high concentrations of acetate and propionate. Taken together, these results provide new insights on the microbial community dynamics and its correlation to performance in MECs fed with different concentrations of acetate and propionate, which are important volatile fatty acids in wastewater. PMID:28775719

Improving surface-enhanced Raman scattering effect using gold-coated hierarchical polystyrene bead substrates modified with postgrowth microwave treatment.

PubMed

Yuen, Clement; Zheng, Wei; Huang, Zhiwei

2008-01-01

We report a novel postgrowth microwave heating implementation by selectively modifying hierarchical polystyrene (PS) bead substrates coated with gold (Au) films to effectively improve the surface-enhanced Raman scattering (SERS) effect on the analytes. The SERS signal of probe molecule rhodamine 6G (Rh 6G) on the microwave-treated Au-PS substrates can be improved by 10-fold, while the detection limit of Rh 6G in concentration can be enhanced by two orders of magnitude compared to the as-growth substrates. The high-quality SERS spectrum of saliva can also be acquired using the modified substrates, demonstrating the potential for the realization of the high-performance SERS substrates for biomedical applications.

Technology development of fabrication techniques for advanced solar dynamic concentrators

NASA Technical Reports Server (NTRS)

Richter, Scott W.

1991-01-01

The objective of the advanced concentrator program is to develop the technology that will lead to lightweight, highly reflective, accurate, scaleable, and long lived space solar dynamic concentrators. The advanced concentrator program encompasses new and innovative concepts, fabrication techniques, materials selection, and simulated space environmental testing. Fabrication techniques include methods of fabricating the substrates and coating substrate surfaces to produce high quality optical surfaces, acceptable for further coating with vapor deposited optical films. The selected materials to obtain a high quality optical surface include microsheet glass and Eccocoat EP-3 epoxy, with DC-93-500 selected as a candidate silicone adhesive and levelizing layer. The following procedures are defined: cutting, cleaning, forming, and bonding microsheet glass. Procedures are also defined for surface cleaning, and EP-3 epoxy application. The results and analyses from atomic oxygen and thermal cycling tests are used to determine the effects of orbital conditions in a space environment.

High current densities enable exoelectrogens to outcompete aerobic heterotrophs for substrate.

PubMed

Ren, Lijiao; Zhang, Xiaoyuan; He, Weihua; Logan, Bruce E

2014-11-01

In mixed-culture microbial fuel cells (MFCs), exoelectrogens and other microorganisms compete for substrate. It has previously been assumed that substrate losses to other terminal electron acceptors over a fed-batch cycle, such as dissolved oxygen, are constant. However, a constant rate of substrate loss would only explain small increases in coulombic efficiencies (CEs, the fraction of substrate recovered as electrical current) with shorter cycle times, but not the large increases in CE that are usually observed with higher current densities and reduced cycle times. To better understand changes in CEs, COD concentrations were measured over time in fed-batch, single-chamber, air-cathode MFCs at different current densities (external resistances). COD degradation rates were all found to be first-order with respect to COD concentration, even under open circuit conditions with no current generation (first-order rate constant of 0.14 ± 0.01 h(-1) ). The rate of COD removal increased when there was current generation, with the highest rate constant (0.33 ± 0.02 h(-1) ) obtained at the lowest external resistance (100 Ω). Therefore, as the substrate concentration was reduced more quickly due to current generation, the rate of loss of substrate to non-exoelectrogens decreased due to this first-order substrate-concentration dependence. As a result, coulombic efficiencies rapidly increased due to decreased, and not constant, removal rates of substrate by non-exoelectrogens. These results show that higher current densities (lower resistances) redirect a greater percentage of substrate into current generation, enabling large increase in CEs with increased current densities. Biotechnol. Bioeng. 2014;111: 2163-2169. © 2014 Wiley Periodicals, Inc. © 2014 Wiley Periodicals, Inc.

Process for producing nickel electrode having lightweight substrate

NASA Technical Reports Server (NTRS)

Lim, Hong S. (Inventor)

1996-01-01

A nickel electrode having a lightweight porous nickel substrate is subjected to a formation cycle involving heavy overcharging and under-discharging in a KOH electrolyte having a concentration of 26% to 31%, resulting in electrodes displaying high active material utilization.

Process for the fermentative production of acetone, butanol and ethanol

DOEpatents

Glassner, David A.; Jain, Mahendra K.; Datta, Rathin

1991-01-01

A process including multistage continuous fermentation followed by batch fermentation with carefully chosen temperatures for each fermentation step, combined with an asporogenic strain of C. acetobutylicum and a high carbohydrate substrate concentration yields extraordinarily high butanol and total solvents concentrations.

Aryl acylamidase activity of human serum albumin with o-nitrotrifluoroacetanilide as the substrate.

PubMed

Masson, Patrick; Froment, Marie-Thérèse; Darvesh, Sultan; Schopfer, Lawrence M; Lockridge, Oksana

2007-08-01

Albumin is generally regarded as an inert protein with no enzyme activity. However, albumin has esterase activity as well as aryl acylamidase activity. A new acetanilide substrate, o-nitrotrifluoroacetanilide (o-NTFNAC), which is more reactive than the classical o-nitroacetanilide, made it possible to determine the catalytic parameters for hydrolysis by fatty-acid free human serum albumin. Owing to the low enzymatic activity of albumin, kinetic studies were performed at high albumin concentration (0.075 mM). The albumin behavior with this substrate was Michaelis-Menten like. Kinetic analysis was performed according to the formalism used for catalysis at high enzyme concentration. This approach provided values for the turnover and dissociation constant of the albumin-substrate complex: k(cat) = 0.13 +/- 0.02 min(-1) and Ks = 0.67 +/- 0.04 mM. MALDI-TOF experiments showed that unlike the ester substrate p-nitrophenyl acetate, o-NTFNAC does not form a stable adduct (acetylated enzyme). Kinetic analysis and MALDI-TOF experiments demonstrated that hydrolysis of o-NTFNAC by albumin is fully rate-limited by the acylation step (k(cat) = k2). Though the aryl acylamidase activity of albumin is low (k(cat)/Ks = 195 M(-1)min(-1)), because of its high concentration in human plasma (0.6-1 mM), albumin may participate in hydrolysis of aryl acylamides through second-order kinetics. This suggests that albumin may have a role in the metabolism of endogenous and exogenous aromatic amides, including drugs and xenobiotics.

Subcellular localization of rat CYP2E1 impacts metabolic efficiency toward common substrates.

PubMed

Hartman, Jessica H; Martin, H Cass; Caro, Andres A; Pearce, Amy R; Miller, Grover P

2015-12-02

Cytochrome P450 2E1 (CYP2E1) detoxifies or bioactivates many low molecular-weight compounds. Most knowledge about CYP2E1 activity relies on studies of the enzyme localized to endoplasmic reticulum (erCYP2E1); however, CYP2E1 undergoes transport to mitochondria (mtCYP2E1) and becomes metabolically active. We report the first comparison of in vitro steady-state kinetic profiles for erCYP2E1 and mtCYP2E1 oxidation of probe substrate 4-nitrophenol and pollutants styrene and aniline using subcellular fractions from rat liver. For all substrates, metabolic efficiency changed with substrate concentration for erCYP2E1 reflected in non-hyperbolic kinetic profiles but not for mtCYP2E1. Hyperbolic kinetic profiles for the mitochondrial enzyme were consistent with Michaelis-Menten mechanism in which metabolic efficiency was constant. By contrast, erCYP2E1 metabolism of 4-nitrophenol led to a loss of enzyme efficiency at high substrate concentrations when substrate inhibited the reaction. Similarly, aniline metabolism by erCYP2E1 demonstrated negative cooperativity as metabolic efficiency decreased with increasing substrate concentration. The opposite was observed for erCYP2E1 oxidation of styrene; the sigmoidal kinetic profile indicated increased efficiency at higher substrate concentrations. These mechanisms and CYP2E1 levels in mitochondria and endoplasmic reticulum were used to estimate the impact of CYP2E1 subcellular localization on metabolic flux of pollutants. Those models showed that erCYP2E1 mainly carries out aniline metabolism at all aniline concentrations. Conversely, mtCYP2E1 dominates styrene oxidation at low styrene concentrations and erCYP2E1 at higher concentrations. Taken together, subcellular localization of CYP2E1 results in distinctly different enzyme activities that could impact overall metabolic clearance and/or activation of substrates and thus impact the interpretation and prediction of toxicological outcomes. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Ethanol production from a biomass mixture of furfural residues with green liquor-peroxide saccarified cassava liquid.

PubMed

Ji, Li; Zheng, Tianran; Zhao, Pengxiang; Zhang, Weiming; Jiang, Jianxin

2016-06-01

As the most abundant renewable resources, lignocellulosic materials are ideal candidates as alternative feedstock for bioethanol production. Cassava residues (CR) are byproducts of the cassava starch industry which can be mixed with lignocellulosic materials for ethanol production. The presence of lignin in lignocellulosic substrates can inhibit saccharification by reducing the cellulase activity. Simultaneous saccharification and fermentation (SSF) of furfural residues (FR) pretreated with green liquor and hydrogen peroxide (GL-H2O2) with CR saccharification liquid was investigated. The final ethanol concentration, yield, initial rate, number of live yeast cells, and the dead yeast ratio were compared to evaluate the effectiveness of combining delignificated lignocellulosic substrates and starchy substrates for ethanol production. Our results indicate that 42.0 % of FR lignin removal was achieved on FR using of 0.06 g H2O2/g-substrate and 9 mL GL/g-substrate at 80 °C. The highest overall ethanol yield was 93.6 % of the theoretical. When the ratio of 0.06 g/g-H2O2-GL-pretreated FR to CR was 5:1, the ethanol concentration was the same with that ratio of untreated FR to CR of 1:1. Using 0.06 g/g-H2O2-GL-pretreated FR with CR at a ratio of 2:1 resulted in 51.9 g/L ethanol concentration. Moreover, FR pretreated with GL-H2O2 decreased the concentration of byproducts in SSF compared with that obtained in the previous study. The lignin in FR would inhibit enzyme activity and GL-H2O2 is an advantageous pretreatment method to treat FR and high intensity of FR pretreatment increased the final ethanol concentration. The efficiency of ethanol fermentation of was improved when delignification increased. GL-H2O2 is an advantageous pretreatment method to treat FR. As the pretreatment dosage of GL-H2O2 on FR increased, the proportion of lignocellulosic substrates was enhanced in the SSF of the substrate mixture of CR and FR as compared with untreated FR. Moreover, the final ethanol concentration was increased with a high ethanol yield and lower byproduct concentrations.

The influence of gravity on the distribution of the deposit formed onto a substrate by sessile, hanging, and sandwiched hanging drop evaporation.

PubMed

Sandu, Ion; Fleaca, Claudiu Teodor

2011-06-15

The focus of the present article is the study of the influence of gravity on the particle deposition profiles on a solid substrate during the evaporation of sessile, hanging and sandwiched hanging drops of colloidal particle suspensions. For concentrations of nanoparticles in the colloidal solutions in the range 0.0001-1 wt.%, highly diluted suspensions will preferentially form rings while concentrated suspensions will preferentially form spots in both sessile and hanging drop evaporation. For intermediary concentrations, the particle deposition profiles will depend on the nanoparticle aggregation dynamics in the suspension during the evaporation process, gravity and on the detailed evaporation geometry. The evaporation of a drop of toluene/carbon nanoparticle suspension hanging from a pendant water drop will leave on the substrate a circular spot with no visible external ring. By contrast, a clear external ring is formed on the substrate by the sessile evaporation of a similar drop of suspension sandwiched between a water drop and the substrate. From the application viewpoint, these processes can be used to create preferential electrical conductive carbon networks and contacts for arrays of self-assembled nanostructures fabricated on solid substrates as well as on flexible polymeric substrates. Copyright © 2011 Elsevier Inc. All rights reserved.

Extremely high intracellular concentration of glucose-6-phosphate and NAD(H) in Deinococcus radiodurans.

PubMed

Yamashiro, Takumi; Murata, Kousaku; Kawai, Shigeyuki

2017-03-01

Deinococcus radiodurans is highly resistant to ionizing radiation and UV radiation, and oxidative stress caused by such radiations. NADP(H) seems to be important for this resistance (Slade and Radman, Microbiol Mol Biol Rev 75:133-191; Slade, Radman, Microbiol Mol Biol Rev 75:133-191, 2011), but the mechanism underlying the generation of NADP(H) or NAD(H) in D. radiodurans has not fully been addressed. Intracellular concentrations of NAD + , NADH, NADP + , and NADPH in D. radiodurans are also not determined yet. We found that cell extracts of D. radiodurans catalyzed reduction of NAD(P) + in vitro, indicating that D. radiodurans cells contain both enzymes and a high concentration of substrates for this activity. The enzyme and the substrate were attributed to glucose-6-phosphate dehydrogenase and glucose-6-phosphate of which intracellular concentration was extremely high. Unexpectedly, the intracellular concentration of NAD(H) was also much greater than that of NADP(H), suggesting some significant roles of NADH. These unusual features of this bacterium would shed light on a new aspect of physiology of this bacterium.

Highly sensitive surface enhanced Raman scattering substrates based on Ag decorated Si nanocone arrays and their application in trace dimethyl phthalate detection

NASA Astrophysics Data System (ADS)

Zuo, Zewen; Zhu, Kai; Ning, Lixin; Cui, Guanglei; Qu, Jun; Cheng, Ying; Wang, Junzhuan; Shi, Yi; Xu, Dongsheng; Xin, Yu

2015-01-01

Wafer-scale three-dimensional (3D) surface enhancement Raman scattering (SERS) substrates were prepared using the plasma etching and ion sputtering methods that are completely compatible with well-established silicon device technologies. The substrates are highly sensitive with excellent uniformity and reproducibility, exhibiting an enhancement factor up to 1012 with a very low relative standard deviation (RSD) around 5%. These are attributed mainly to the uniform-distributed, multiple-type high-density hot spots originating from the structural characteristics of Ag nanoparticles (NPs) decorated Si nanocone (NC) arrays. We demonstrate that the trace dimethyl phthalate (DMP) at a concentration of 10-7 M can be well detected using this SERS substrate, showing that the AgNPs-decorated SiNC arrays can serve as efficient SERS substrates for phthalate acid esters (PAEs) detection with high sensitivity.

Conversion of woody biomass into fermentable sugars by cellulase from Agaricus arvensis.

PubMed

Jeya, Marimuthu; Nguyen, Ngoc-Phuong-Thao; Moon, Hee-Jung; Kim, Sang-Hwan; Lee, Jung-Kul

2010-11-01

Agaricus arvensis, a newly isolated basidiomycetous fungus, was found to secrete efficient cellulases. The strain produced the highest endoglucanase (EG), cellobiohydrolase (CBH) and beta-glucosidase (BGL) activities of 0.3, 3.2 and 8U/mg-protein, respectively, with rice straw as the carbon source. Saccharification of the woody biomass with A. arvensis cellulase as the enzyme source released a high level of fermentable sugars. Enzymatic hydrolysis of the poplar biomass was optimized using the response surface methodology in order to study the influence of the variables (pH, temperature, cellulases concentration and substrate concentration). The enzyme and substrate concentrations were identified as the limiting factors for the saccharification of poplar wood biomass. A total reducing sugar level of 29g/L (293mg/g-substrate) was obtained at an enzyme concentration of 65FPU/g-substrate after optimization of the hydrolysis parameters. The model validation showed a good agreement between the experimental results and the predicted responses. A. arvensis could be a good candidate for the production of reducing sugars from a cellulosic biomass.

Au coated PS nanopillars as a highly ordered and reproducible SERS substrate

NASA Astrophysics Data System (ADS)

Kim, Yong-Tae; Schilling, Joerg; Schweizer, Stefan L.; Sauer, Guido; Wehrspohn, Ralf B.

2017-07-01

Noble metal nanostructures with nanometer gap size provide strong surface-enhanced Raman scattering (SERS) which can be used to detect trace amounts of chemical and biological molecules. Although several approaches were reported to obtain active SERS substrates, it still remains a challenge to fabricate SERS substrates with high sensitivity and reproducibility using low-cost techniques. In this article, we report on the fabrication of Au sputtered PS nanopillars based on a template synthetic method as highly ordered and reproducible SERS substrates. The SERS substrates are fabricated by anodic aluminum oxide (AAO) template-assisted infiltration of polystyrene (PS) resulting in hemispherical structures, and a following Au sputtering process. The optimum gap size between adjacent PS nanopillars and thickness of the Au layers for high SERS sensitivity are investigated. Using the Au sputtered PS nanopillars as an active SERS substrate, the Raman signal of 4-methylbenzenethiol (4-MBT) with a concentration down to 10-9 M is identified with good signal reproducibility, showing great potential as promising tool for SERS-based detection.

Study on the Enhanced Operation of Self-Ventilation-Based Coupling System for Domestic Wastewater Treatment

NASA Astrophysics Data System (ADS)

Kong, Lingwei; Wang, Lu; Zhang, Yi; Mei, Rongwu; Zhang, Yu

2018-06-01

In this study, a new coupling system of biological filter bed and subsurface-flow constructed wetland based on the self-ventilation network was proposed, and the comparative pollutant removal efficiency at low and high influent concentration of the pilot coupling system with different substrates configurations were investigated. The study found that: The comparison system (b) had better removal rates than that of the original system (a), and the removal rate when treating low influent concentration was 74.10%, 94.14%, 73.57% and 69.53%, while in high influent concentration case was 81.30%, 90.28%, 88.57% and 75.36% for CODCr , NH4+ -N, TN and TP, respectively. The removal of the above main water indexes of the comparison system (b) promoted by 11.00%, 11.55%, 2.69% and 8.09% respectively in low influent concentration case and 4.20%, 9.20%, 7.66% and 13.61% respectively in high influent concentration case when comparing to the original system (a), which showed that the optimized configuration of various kinds of substrates was significant and was more beneficial to the degradation and removal of pollutants. The adsorption and interception function of substrates in the constructed wetland was the main way of phosphorus removal. The function of self-ventilation ensured the amount of DO in the coupling system, making the phosphorus removal was less affected comparing to structure of traditional wetland.

Effect of lactose concentration on batch production of ethanol from cheese whey using Candida pseudotropicalis

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

Ghaly, A.E.; El-Taweel, A.A.

1995-07-01

The effect of lactose concentration on growth of Candida pseudotropicalis and ethanol production from cheese whey under batch conditions was investigated. Four initial lactose concentrations ranging from 50 to 200 g/L (5 to 20% wt/vol) were used. High concentration of lactose had an inhibitory effect on the specific growth rate, lactose utilization rate, and ethanol production rate. The maximum cell concentration was influenced by the initial substrate concentration as well as ethanol concentration. Inhibition of ethanol production was more pronounced at higher initial lactose concentrations. The maximum ethanol yield (96.6% of the theoretical yield) was achieved with the 100 g/Lmore » initial substrate concentration. The results indicated that pH control during alcohol fermentation of cheese whey is not necessary. 41 refs., 12 figs., 1 tab.« less

Sensing of p53 and EGFR Biomarkers Using High Efficiency SERS Substrates

PubMed Central

Owens, Peter; Phillipson, Nigel; Perumal, Jayakumar; O’Connor, Gerard M.; Olivo, Malini

2015-01-01

In this paper we describe a method for the determination of protein concentration using Surface Enhanced Raman Resonance Scattering (SERRS) immunoassays. We use two different Raman active linkers, 4-aminothiophenol and 6-mercaptopurine, to bind to a high sensitivity SERS substrate and investigate the influence of varying concentrations of p53 and EGFR on the Raman spectra. Perturbations in the spectra are due to the influence of protein–antibody binding on Raman linker molecules and are attributed to small changes in localised mechanical stress, which are enhanced by SERRS. These influences are greatest for peaks due to the C-S functional group and the Full Width Half Maximum (FWHM) was found to be inversely proportional to protein concentration. PMID:26516922

Synthesis and characterization of InN nanocrystals on glass substrate by plasma assisted reactive evaporation

NASA Astrophysics Data System (ADS)

Ganesh, V.; Alizadeh, M.; Shuhaimi, A.; Sundaram, S.; Hakim, K. M.; Goh, B. T.; Rahman, S. A.

2017-07-01

InN nanocrystals were grown on glass substrate by plasma assisted reactive evaporation technique and the quality was compared with InN on Si (111) substrate. Single phase InN was confirmed by X-ray diffraction and micro Raman analysis on both the substrates. Agglomerated and Hexagonal faceting nanocrystals observed by field emission scanning electron microscopy. Energy dispersive X-ray analysis shows InN nanocrystals are nearly stochiometric. Photoluminescence reveals a broad emission near bandedge at 2 .04 eV and defect band at 1.07 eV. The Hall measurement on both the substrates reveals high electron carrier concentration. These encouraging results obtained suggested that high quality single crystalline InN can be obtained on glass substrate further optimizing the growth parameters. This novel growth of InN nanocrystals on glass substrate is an important step towards the development of monolithic, high efficiency low-cost InGaN-based renewable energy sources.

High Temperature Solar Reflector, Its Preparation and Use

NASA Technical Reports Server (NTRS)

Jaworske, Donald A. (Inventor)

1999-01-01

A coating-substrate combination having high specular reflectivity at high temperatures reaching 8000 C in a vacuum is described. The substrate comprises pure nickel metal or a nickel-containing metal alloy such as stainless steel having a highly polished reflective surface. The coating is a layer of silver deposited on the substrate to a thickness of 300 A to 3000 A. A 300 A to 5000 A protective coating of silica, alumina or magnesium fluoride is used to cover the silver and to protect it from oxidation. The combination is useful as a parabolic shaped secondary concentrator for collecting solar radiation for generating power or thermal energy for satellite uses. The reflective layer and protective coating preferably are applied to the reflective surface of the substrate by electron beam evaporation or by ion sputtering.

COSIM: A Finite-Difference Computer Model to Predict Ternary Concentration Profiles Associated with Oxidation and Interdiffusion of Overlay-Coated Substrates

NASA Technical Reports Server (NTRS)

Nesbitt, James A.

2000-01-01

A finite-difference computer program (COSIM) has been written which models the one-dimensional, diffusional transport associated with high-temperature oxidation and interdiffusion of overlay-coated substrates. The program predicts concentration profiles for up to three elements in the coating and substrate after various oxidation exposures. Surface recession due to solute loss is also predicted. Ternary cross terms and concentration-dependent diffusion coefficients are taken into account. The program also incorporates a previously-developed oxide growth and spalling model to simulate either isothermal or cyclic oxidation exposures. In addition to predicting concentration profiles after various oxidation exposures, the program can also be used to predict coating fife based on a concentration dependent failure criterion (e.g., surface solute content drops to two percent). The computer code, written in an extension of FORTRAN 77, employs numerous subroutines to make the program flexible and easily modifiable to other coating oxidation problems.

Effects of continuous triiodothyronine infusion on the tricarboxylic acid cycle in the normal immature swine heart under extracorporeal membrane oxygenation in vivo

PubMed Central

Kajimoto, Masaki; O'Kelly Priddy, Colleen M.; Ledee, Dolena R.; Xu, Chun; Isern, Nancy; Olson, Aaron K.

2014-01-01

Extracorporeal membrane oxygenation (ECMO) is frequently used in infants with postoperative cardiopulmonary failure. ECMO also suppresses circulating triiodothyronine (T3) levels and modifies myocardial metabolism. We assessed the hypothesis that T3 supplementation reverses ECMO-induced metabolic abnormalities in the immature heart. Twenty-two male Yorkshire pigs (age: 25–38 days) with ECMO received [2-13C]lactate, [2,4,6,8-13C4]octanoate (medium-chain fatty acid), and [U-13C]long-chain fatty acids as metabolic tracers either systemically (totally physiological intracoronary concentration) or directly into the coronary artery (high substrate concentration) for the last 60 min of each protocol. NMR analysis of left ventricular tissue determined the fractional contribution of these substrates to the tricarboxylic acid cycle. Fifty percent of the pigs in each group received intravenous T3 supplement (bolus at 0.6 μg/kg and then continuous infusion at 0.2 μg·kg−1·h−1) during ECMO. Under both substrate loading conditions, T3 significantly increased the fractional contribution of lactate with a marginal increase in the fractional contribution of octanoate. Both T3 and high substrate provision increased the myocardial energy status, as indexed by phosphocreatine concentration/ATP concentration. In conclusion, T3 supplementation promoted lactate metabolism to the tricarboxylic acid cycle during ECMO, suggesting that T3 releases the inhibition of pyruvate dehydrogenase. Manipulation of substrate utilization by T3 may be used therapeutically during ECMO to improve the resting energy state and facilitate weaning. PMID:24531815

Effects of continuous triiodothyronine infusion on the tricarboxylic acid cycle in the normal immature swine heart under extracorporeal membrane oxygenation in vivo.

PubMed

Kajimoto, Masaki; Priddy, Colleen M O'Kelly; Ledee, Dolena R; Xu, Chun; Isern, Nancy; Olson, Aaron K; Portman, Michael A

2014-04-15

Extracorporeal membrane oxygenation (ECMO) is frequently used in infants with postoperative cardiopulmonary failure. ECMO also suppresses circulating triiodothyronine (T3) levels and modifies myocardial metabolism. We assessed the hypothesis that T3 supplementation reverses ECMO-induced metabolic abnormalities in the immature heart. Twenty-two male Yorkshire pigs (age: 25-38 days) with ECMO received [2-(13)C]lactate, [2,4,6,8-(13)C4]octanoate (medium-chain fatty acid), and [U-(13)C]long-chain fatty acids as metabolic tracers either systemically (totally physiological intracoronary concentration) or directly into the coronary artery (high substrate concentration) for the last 60 min of each protocol. NMR analysis of left ventricular tissue determined the fractional contribution of these substrates to the tricarboxylic acid cycle. Fifty percent of the pigs in each group received intravenous T3 supplement (bolus at 0.6 μg/kg and then continuous infusion at 0.2 μg·kg(-1)·h(-1)) during ECMO. Under both substrate loading conditions, T3 significantly increased the fractional contribution of lactate with a marginal increase in the fractional contribution of octanoate. Both T3 and high substrate provision increased the myocardial energy status, as indexed by phosphocreatine concentration/ATP concentration. In conclusion, T3 supplementation promoted lactate metabolism to the tricarboxylic acid cycle during ECMO, suggesting that T3 releases the inhibition of pyruvate dehydrogenase. Manipulation of substrate utilization by T3 may be used therapeutically during ECMO to improve the resting energy state and facilitate weaning.

Characterization of the respiration-induced yeast mitochondrial permeability transition pore.

PubMed

Bradshaw, Patrick C; Pfeiffer, Douglas R

2013-12-01

When isolated mitochondria from the yeast Saccharomyces cerevisiae oxidize respiratory substrates in the absence of phosphate and ADP, the yeast mitochondrial unselective channel, also called the yeast permeability transition pore (yPTP), opens in the inner membrane, dissipating the electrochemical gradient. ATP also induces yPTP opening. yPTP opening allows mannitol transport into isolated mitochondria of laboratory yeast strains, but mannitol is not readily permeable through the yPTP in an industrial yeast strain, Yeast Foam. The presence of oligomycin, an inhibitor of ATP synthase, allowed for respiration-induced mannitol permeability in mitochondria from this strain. Potassium (K+) had varied effects on the respiration-induced yPTP, depending on the concentration of the respiratory substrate added. At low respiratory substrate concentrations K+ inhibited respiration-induced yPTP opening, while at high substrate concentrations this effect diminished. However, at the high respiratory substrate concentrations, the presence of K+ partially prevented phosphate inhibition of yPTP opening. Phosphate was found to inhibit respiration-induced yPTP opening by binding a site on the matrix space side of the inner membrane in addition to its known inhibitory effect of donating protons to the matrix space to prevent the pH change necessary for yPTP opening. The respiration-induced yPTP was also inhibited by NAD, Mg2+, NH4 + or the oxyanion vanadate polymerized to decavanadate. The results demonstrate similar effectors of the respiration-induced yPTP as those previously described for the ATP-induced yPTP and reconcile previous strain-dependent differences in yPTP solute selectivity. Copyright © 2013 John Wiley & Sons, Ltd.

Adaptation to metals in widespread and endemic plants.

PubMed Central

Shaw, A J

1994-01-01

Bryophytes, including the mosses, liverworts, and hornworts, occur in a variety of habitats with high concentrations of metals and have other characteristics that are advantageous for studies of metal tolerance. Mosses may evolve genetically specialized, metal-tolerant races less frequently than flowering plants. Some species of mosses appear to have inherently high levels of metal tolerance even in individuals that have not been subjected to natural selection in contaminated environments. Scopelophila cataractae, one of the so-called copper mosses, not only tolerates extremely high concentrations of metals in its substrates, but requires these substrates for optimum growth. This species should be included in mechanistic studies of tolerance at the cellular and molecular levels. PMID:7713025

Synthesis and evaluation of fluorogenic triglycerides as lipase assay substrates.

PubMed

Andersen, Rokhsana J; Brask, Jesper

2016-06-01

Three racemic fluorogenic triglycerides are synthesized and evaluated as lipase assay substrates. The presented synthesis route goes through a key triglyceride intermediate which can be chemoselectively functionalized with a wide range of different probes. Hence the substrate can be tailor-made for a specific assay, or focus can be on low cost in larger scale for applications in high-throughput screening (HTS) assays. In the specific examples, TG-ED, TG-FD and TG-F2 are assembled with the Edans-Dabcyl or the fluorescein-Dabcyl FRET pair, or relying on fluorescein self-quenching, respectively. Proof-of-concept assays allowed determination of 1st order kinetic parameters (kcat/KM) of 460s(-1)M(-1), 59s(-1)M(-1) and 346s(-1)M(-1), respectively, for the three substrates. Commercially available EnzChek lipase substrate provided 204s(-1)M(-1). Substrate concentration was identified as a critical parameter, with measured reaction rates decreasing at higher concentrations when intermolecular quenching becomes significant. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Quantitative measurement of protein digestion in simulated gastric fluid.

PubMed

Herman, Rod A; Korjagin, Valerie A; Schafer, Barry W

2005-04-01

The digestibility of novel proteins in simulated gastric fluid is considered to be an indicator of reduced risk of allergenic potential in food, and estimates of digestibility for transgenic proteins expressed in crops are required for making a human-health risk assessment by regulatory authorities. The estimation of first-order rate constants for digestion under conditions of low substrate concentration was explored for two protein substrates (azocoll and DQ-ovalbumin). Data conformed to first-order kinetics, and half-lives were relatively insensitive to significant variations in both substrate and pepsin concentration when high purity pepsin preparations were used. Estimation of digestion efficiency using densitometric measurements of relative protein concentration based on SDS-PAGE corroborated digestion estimates based on measurements of dye or fluorescence release from the labeled substrates. The suitability of first-order rate constants for estimating the efficiency of the pepsin digestion of novel proteins is discussed. Results further support a kinetic approach as appropriate for comparing the digestibility of proteins in simulated gastric fluid.

Concentration-Dependent Patterns of Leucine Incorporation by Coastal Picoplankton

PubMed Central

Alonso, Cecilia; Pernthaler, Jakob

2006-01-01

Coastal pelagic environments are believed to feature concentration gradients of dissolved organic carbon at a microscale, and they are characterized by pronounced seasonal differences in substrate availability for the heterotrophic picoplankton. Microbial taxa that coexist in such habitats might thus differ in their ability to incorporate substrates at various concentrations. We investigated the incorporation patterns of leucine in four microbial lineages from the coastal North Sea at concentrations between 0.1 and 100 nM before and during a spring phytoplankton bloom. Community bulk incorporation rates and the fraction of leucine-incorporating cells in the different populations were analyzed. Significantly fewer bacterial cells incorporated the amino acid before (13 to 35%) than during (23 to 47%) the bloom at all but the highest concentration. The incorporation rate per active cell in the prebloom situation was constant above 0.1 nM added leucine, whereas it increased steeply with substrate concentration during the bloom. At both time points, a high proportion of members of the Roseobacter clade incorporated leucine at all concentrations (55 to 80% and 86 to 94%, respectively). In contrast, the fractions of leucine-incorporating cells increased substantially with substrate availability in bacteria from the SAR86 clade (8 to 31%) and from DE cluster 2 of the Flavobacteria-Sphingobacteria (14 to 33%). The incorporation patterns of marine Euryarchaeota were between these extremes (30 to 56% and 48 to 70%, respectively). Our results suggest that the contribution of microbial taxa to the turnover of particular substrates may be concentration dependent. This may help us to understand the specific niches of coexisting populations that appear to compete for the same resources. PMID:16517664

Interactions of chlorphenesin and divalent metal ions with phosphodiesterase.

PubMed

Edelson, J; McMullen, J P

1976-09-01

Chlorphenesin inhibition of the hydrolysis of cyclic AMP by guinea-pig lung phosphodiesterase was reversed by the addition of exogenous magnesium ions. Chlorphenesin and theophylline inhibition of this enzyme was shown to be noncompetitive when the substrate concentration was low. Kinetic studies of the inhibition of beef heart phosphodiesterase by chlorphenesin and theophylline indicated that the substrate concentration was a factor in determining whether inhibition was competitive or noncompetitive. Calcium, cobalt and copper ions were inhibitory to guinea-pig lung phosphodiesterase. The inhibition due to chlorphenesin was partially reversed by low (40 mM or less) concentrations of barium ions; high concentrations of barium ions, or manganese ions, were inhibitory. The concentration of the divalent cation did not affect the type of inhibition that was observed.

High quality nitrogen-doped zinc oxide thin films grown on ITO by sol-gel method

NASA Astrophysics Data System (ADS)

Pathak, Trilok Kumar; Kumar, Vinod; Purohit, L. P.

2015-11-01

Highly transparent N-doped ZnO thin films were deposited on ITO coated corning glass substrate by sol-gel method. Ammonium nitrate was used as a dopant source of N with varying the doping concentration 0, 0.5, 1.0, 2.0 and 3.0 at%. The DSC analysis of prepared NZO sols is observed a phase transition at 150 °C. X-ray diffraction pattern showed the preferred (002) peak of ZnO, which was deteriorated with increased N concentrations. The transmittance of NZO thin films was observed to be ~88%. The bandgap of NZO thin films increased from 3.28 to 3.70 eV with increased N concentration from 0 to 3 at%. The maximum carrier concentration 8.36×1017 cm-3 and minimum resistivity 1.64 Ω cm was observed for 3 at% N doped ZnO thin films deposited on glass substrate. These highly transparent ZnO thin films can be used as a window layer in solar cells and optoelectronic devices.

Pretreatment process for forming a smooth surface diamond film on a carbon-coated substrate

DOEpatents

Feng, Zhu; Brewer, Marilee; Brown, Ian; Komvopoulos, Kyriakos

1994-01-01

A process is disclosed for the pretreatment of a carbon-coated substrate to provide a uniform high density of nucleation sites thereon for the subsequent deposition of a continuous diamond film without the application of a bias voltage to the substrate. The process comprises exposing the carbon-coated substrate, in a microwave plasma enhanced chemical vapor deposition system, to a mixture of hydrogen-methane gases, having a methane gas concentration of at least about 4% (as measured by partial pressure), while maintaining the substrate at a pressure of about 10 to about 30 Torr during the pretreatment.

Ultrasonic degradation of acetaminophen in water: effect of sonochemical parameters and water matrix.

PubMed

Villaroel, Erica; Silva-Agredo, Javier; Petrier, Christian; Taborda, Gonzalo; Torres-Palma, Ricardo A

2014-09-01

This paper deals about the sonochemical water treatment of acetaminophen (ACP, N-acetyl-p-aminophenol or paracetamol), one of the most popular pharmaceutical compounds found in natural and drinking waters. Effect of ultrasonic power (20-60 W), initial ACP concentration (33-1323 μmol L(-1)) and pH (3-12) were evaluated. High ultrasonic powers and, low and natural acidic pH values favored the efficiency of the treatment. Effect of initial substrate concentration showed that the Langmuir-type kinetic model fit well the ACP sonochemical degradation. The influence of organic compounds in the water matrix, at concentrations 10-fold higher than ACP, was also evaluated. The results indicated that only organic compounds having a higher value of the Henry's law constant than the substrate decrease the efficiency of the treatment. On the other hand, ACP degradation in mineral natural water showed to be strongly dependent of the initial substrate concentration. A positive matrix effect was observed at low ACP concentrations (1.65 μmol L(-1)), which was attributed to the presence of bicarbonate ion in solution. However, at relative high ACP concentrations a detrimental effect of matrix components was noticed. Finally, the results indicated that ultrasonic action is able to transform ACP in aliphatic organic compounds that could be subsequently eliminated in a biological system. Copyright © 2014 Elsevier B.V. All rights reserved.

Aromatic aldehydes at the active site of aldehyde oxidoreductase from Desulfovibrio gigas: reactivity and molecular details of the enzyme-substrate and enzyme-product interaction.

PubMed

Correia, Hugo D; Marangon, Jacopo; Brondino, Carlos D; Moura, Jose J G; Romão, Maria J; González, Pablo J; Santos-Silva, Teresa

2015-03-01

Desulfovibrio gigas aldehyde oxidoreductase (DgAOR) is a mononuclear molybdenum-containing enzyme from the xanthine oxidase (XO) family, a group of enzymes capable of catalyzing the oxidative hydroxylation of aldehydes and heterocyclic compounds. The kinetic studies reported in this work showed that DgAOR catalyzes the oxidative hydroxylation of aromatic aldehydes, but not heterocyclic compounds. NMR spectroscopy studies using (13)C-labeled benzaldehyde confirmed that DgAOR catalyzes the conversion of aldehydes to the respective carboxylic acids. Steady-state kinetics in solution showed that high concentrations of the aromatic aldehydes produce substrate inhibition and in the case of 3-phenyl propionaldehyde a suicide substrate behavior. Hydroxyl-substituted aromatic aldehydes present none of these behaviors but the kinetic parameters are largely affected by the position of the OH group. High-resolution crystallographic structures obtained from single crystals of active-DgAOR soaked with benzaldehyde showed that the side chains of Phe425 and Tyr535 are important for the stabilization of the substrate in the active site. On the other hand, the X-ray data of DgAOR soaked with trans-cinnamaldehyde showed a cinnamic acid molecule in the substrate channel. The X-ray data of DgAOR soaked with 3-phenyl propionaldehyde showed clearly how high substrate concentrations inactivate the enzyme by binding covalently at the surface of the enzyme and blocking the substrate channel. The different reactivity of DgAOR versus aldehyde oxidase and XO towards aromatic aldehydes and N-heterocyclic compounds is explained on the basis of the present kinetic and structural data.

Revisiting nitrification in the Eastern Tropical South Pacific: A focus on controls

NASA Astrophysics Data System (ADS)

Peng, Xuefeng; Fuchsman, Clara A.; Jayakumar, Amal; Warner, Mark J.; Devol, Allan H.; Ward, Bess B.

2016-03-01

Nitrification, the oxidation of ammonium (NH4+) to nitrite (NO2-) and to nitrate (NO3-), is a component of the nitrogen (N) cycle internal to the fixed N pool. In oxygen minimum zones (OMZs), which are hotspots for oceanic fixed N loss, nitrification plays a key role because it directly supplies substrates for denitrification and anaerobic ammonia oxidation (anammox), and may compete for substrates with these same processes. However, the control of oxygen and substrate concentrations on nitrification are not well understood. We performed onboard incubations with 15N-labeled substrates to measure rates of NH4+ and NO2- oxidation in the eastern tropical South Pacific (ETSP). The spatial and depth distributions of NH4+ and NO2- oxidation rates were primarily controlled by NH4+ and NO2- availability, oxygen concentration, and light. In the euphotic zone, nitrification was partially photoinhibited. In the anoxic layer, NH4+ oxidation was negligible or below detection, but high rates of NO2- oxidation were observed. NH4+ oxidation displayed extremely high affinity for both NH4+ and oxygen. The positive linear correlations between NH4+ oxidation rates and in situ NH4+ concentrations and ammonia monooxygenase subunit A (amoA) gene abundances in the upper oxycline indicate that the natural assemblage of ammonia oxidizers responds to in situNH4+ concentrations or supply by adjusting their population size, which determines the NH4+ oxidation potential. The depth distribution of archaeal and bacterial amoA gene abundances and N2O concentration, along with independently reported simultaneous direct N2O production rate measurements, suggests that AOA were predominantly responsible for NH4+ oxidation, which was a major source of N2O production at oxygen concentrations > 5 µM.

A Model of Extracellular Enzymes in Free-Living Microbes: Which Strategy Pays Off?

PubMed Central

Thygesen, Uffe H.; Riemann, Lasse; Stedmon, Colin A.

2015-01-01

An initial modeling approach was applied to analyze how a single, nonmotile, free-living, heterotrophic bacterial cell may optimize the deployment of its extracellular enzymes. Free-living cells live in a dilute and complex substrate field, and to gain enough substrate, their extracellular enzymes must be utilized efficiently. The model revealed that surface-attached and free enzymes generate unique enzyme and substrate fields, and each deployment strategy has distinctive advantages. For a solitary cell, surface-attached enzymes are suggested to be the most cost-efficient strategy. This strategy entails potential substrates being reduced to very low concentrations. Free enzymes, on the other hand, generate a radically different substrate field, which suggests significant benefits for the strategy if free cells engage in social foraging or experience high substrate concentrations. Swimming has a slight positive effect for the attached-enzyme strategy, while the effect is negative for the free-enzyme strategy. The results of this study suggest that specific dissolved organic compounds in the ocean likely persist below a threshold concentration impervious to biological utilization. This could help explain the persistence and apparent refractory state of oceanic dissolved organic matter (DOM). Microbial extracellular enzyme strategies, therefore, have important implications for larger-scale processes, such as shaping the role of DOM in ocean carbon sequestration. PMID:26253668

Porous Silicon Covered with Silver Nanoparticles as Surface-Enhanced Raman Scattering (SERS) Substrate for Ultra-Low Concentration Detection.

PubMed

Kosović, Marin; Balarin, Maja; Ivanda, Mile; Đerek, Vedran; Marciuš, Marijan; Ristić, Mira; Gamulin, Ozren

2015-12-01

Microporous and macro-mesoporous silicon templates for surface-enhanced Raman scattering (SERS) substrates were produced by anodization of low doped p-type silicon wafers. By immersion plating in AgNO3, the templates were covered with silver metallic film consisting of different silver nanostructures. Scanning electron microscopy (SEM) micrographs of these SERS substrates showed diverse morphology with significant difference in an average size and size distribution of silver nanoparticles. Ultraviolet-visible-near-infrared (UV-Vis-NIR) reflection spectroscopy showed plasmonic absorption at 398 and 469 nm, which is in accordance with the SEM findings. The activity of the SERS substrates was tested using rhodamine 6G (R6G) dye molecules and 514.5 nm laser excitation. Contrary to the microporous silicon template, the SERS substrate prepared from macro-mesoporous silicon template showed significantly broader size distribution of irregular silver nanoparticles as well as localized surface plasmon resonance closer to excitation laser wavelength. Such silver morphology has high SERS sensitivity that enables ultralow concentration detection of R6G dye molecules up to 10(-15) M. To our knowledge, this is the lowest concentration detected of R6G dye molecules on porous silicon-based SERS substrates, which might even indicate possible single molecule detection.

MnO2-Based Electrochemical Supercapacitors on Flexible Carbon Substrates

NASA Astrophysics Data System (ADS)

Tadjer, Marko J.; Mastro, Michael A.; Rojo, José M.; Mojena, Alberto Boscá; Calle, Fernando; Kub, Francis J.; Eddy, Charles R.

2014-04-01

Manganese dioxide films were grown on large area flexible carbon aerogel substrates. Characterization by x-ray diffraction confirmed α-MnO2 growth. Three types of films were compared as a function of hexamethylenetetramine (HMTA) concentration during growth. The highest concentration of HM TA produced MnO2 flower-like films, as observed by scanning electron microscopy, whose thickness and surface coverage lead to both a higher specific capacitance and higher series resistance. Specific capacitance was measured to be 64 F/g using a galvanostatic setup, compared to the 47 F/g-specific capacitance of the carbon aerogel substrate. Such supercapacitor devices can be fabricated on large area sheets of carbon aerogel to achieve high total capacitance.

Kinetics of Alcohol Dehydrogenase-Catalyzed Oxidation of Ethanol Followed by Visible Spectroscopy

ERIC Educational Resources Information Center

Bendinskas, Kestutis; DiJiacomo, Christopher; Krill, Allison; Vitz, Ed

2005-01-01

The effect of substrate concentration on the rate of enzymatic reaction was investigated and typical Michaelis-Mentin kinetics was observed during the first week. The first order reaction at relatively low concentrations of ethanol and the pseudo zero-order reaction at high concentrations of ethanol were emphasized.

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

Moto, Kenta; Sadoh, Taizoh; Miyao, Masanobu, E-mail: miyao@ed.kyushu-u.ac.jp

Crystalline GeSn-on-insulator structures with high Sn concentration (>8%), which exceeds thermal equilibrium solid-solubility (∼2%) of Sn in Ge, are essential to achieve high-speed thin film transistors and high-efficiency optical devices. We investigate non-thermal equilibrium growth of Ge{sub 1−x}Sn{sub x} (0 ≤ x ≤ 0.2) on quartz substrates by using pulsed laser annealing (PLA). The window of laser fluence enabling complete crystallization without film ablation is drastically expanded (∼5 times) by Sn doping above 5% into Ge. Substitutional Sn concentration in grown layers is found to be increased with decreasing irradiation pulse number. This phenomenon can be explained on the basis of significant thermal non-equilibriummore » growth achieved by higher cooling rate after PLA with a lower pulse number. As a result, GeSn crystals with substitutional Sn concentration of ∼12% are realized at pulse irradiation of single shot for the samples with the initial Sn concentration of 15%. Raman spectroscopy and electron microscopy measurements reveal the high quality of the grown layer. This technique will be useful to fabricate high-speed thin film transistors and high-efficiency optical devices on insulating substrates.« less

Succinic acid production from duckweed (Landoltia punctata) hydrolysate by batch fermentation of Actinobacillus succinogenes GXAS137.

PubMed

Shen, Naikun; Wang, Qingyan; Zhu, Jing; Qin, Yan; Liao, Siming; Li, Yi; Zhu, Qixia; Jin, Yanling; Du, Liqin; Huang, Ribo

2016-07-01

Duckweed is potentially an ideal succinic acid (SA) feedstock due to its high proportion of starch and low lignin content. Pretreatment methods, substrate content and nitrogen source were investigated to enhance the bioconversion of duckweed to SA and to reduce the costs of production. Results showed that acid hydrolysis was an effective pretreatment method because of its high SA yield. The optimum substrate concentration was 140g/L. The optimum substrate concentration was 140g/L. Corn steep liquor powder could be considered a feasible and inexpensive alternative to yeast extract as a nitrogen source. Approximately 57.85g/L of SA was produced when batch fermentation was conducted in a 1.3L stirred bioreactor. Therefore, inexpensive duckweed can be a promising feedstock for the economical and efficient production of SA through fermentation by Actinobacillus succinogenes GXAS137. Copyright © 2016. Published by Elsevier Ltd.

Liquid-Phase Epitaxial Growth of ZnS, ZnSe and Their Mixed Compounds Using Te as Solvent

NASA Astrophysics Data System (ADS)

Nakamura, Hiroshi; Aoki, Masaharu

1981-01-01

Epitaxial layers of ZnS, ZnSe and their mixed compounds were grown on ZnS substrates by the liquid-phase epitaxial growth (LPE) method using Te as the solvent. The open-tube slide-boat technique was used, and a suitable starting temperature for growth was found to be 850°C for ZnS and 700-800°C for ZnSe. The ZnS epitaxial layers grown on {111}A and {111}B oriented ZnS substrates were thin (˜1 μm) and smooth, had low, uniform Te concentrations (˜0.1 at.%) and were highly luminescent. The ZnSe epitaxial layers were relatively thick (10-30 μm) and had fairly high Te concentrations (a few at.%). Various mixed compound ZnS1-xSex were also grown on ZnS substrates.

Optimization of High-Throughput Sequencing Kinetics for determining enzymatic rate constants of thousands of RNA substrates

PubMed Central

Niland, Courtney N.; Jankowsky, Eckhard; Harris, Michael E.

2016-01-01

Quantification of the specificity of RNA binding proteins and RNA processing enzymes is essential to understanding their fundamental roles in biological processes. High Throughput Sequencing Kinetics (HTS-Kin) uses high throughput sequencing and internal competition kinetics to simultaneously monitor the processing rate constants of thousands of substrates by RNA processing enzymes. This technique has provided unprecedented insight into the substrate specificity of the tRNA processing endonuclease ribonuclease P. Here, we investigate the accuracy and robustness of measurements associated with each step of the HTS-Kin procedure. We examine the effect of substrate concentration on the observed rate constant, determine the optimal kinetic parameters, and provide guidelines for reducing error in amplification of the substrate population. Importantly, we find that high-throughput sequencing, and experimental reproducibility contribute their own sources of error, and these are the main sources of imprecision in the quantified results when otherwise optimized guidelines are followed. PMID:27296633

Porous glass makes effective substrate for ozone-sensing reagent

NASA Technical Reports Server (NTRS)

1965-01-01

Porous-glass substrate is used for absorption of a dye used in measuring the concentration of atmospheric ozone at high altitudes. This measurement is based on the chemiluminescence produced in the reaction between ozone and the dye, rhodamine B. The porous glass provides a large interstitial surface area which promotes this reaction.

Influence of GaAs substrate properties on the congruent evaporation temperature

NASA Astrophysics Data System (ADS)

Spirina, A. A.; Nastovjak, A. G.; Shwartz, N. L.

2018-03-01

High-temperature annealing of GaAs(111)A and GaAs(111)B substrates under Langmuir evaporation conditions was studied using Monte Carlo simulation. The maximal value of the congruent evaporation temperature was estimated. The congruent evaporation temperature was demonstrated to be dependent on the surface orientation and concentration of surface defects.

Synthesis of a Fucosylated Trisaccharide Via Transglycosylation by α-L-Fucosidase from Thermotoga maritima.

PubMed

Guzmán-Rodríguez, Francisco; Alatorre-Santamaría, Sergio; Gómez-Ruiz, Lorena; Rodríguez-Serrano, Gabriela; García-Garibay, Mariano; Cruz-Guerrero, Alma

2018-05-02

Fucosylated oligosaccharides, such as 2'-fucosyllactose in human milk, have important biological functions such as prebiotics and preventing infection. In this work, the effect of an acceptor substrate (lactose) and the donor substrate 4-nitrophenyl-α-L-fucopyranoside (pNP-Fuc) on the synthesis of a fucosylated trisaccharide was studied in a transglycosylation reaction using α-L-fucosidase from Thermotoga maritima. Conducting a matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), it was demonstrated that synthesized oligosaccharide corresponded to a fucosylated trisaccharide, and high-performance liquid chromatography (HPLC) of the hydrolyzed compound confirmed it was fucosyllactose. As the concentration of the acceptor substrate increased, the concentration and synthesis rate of the fucosylated trisaccharide also increased, and the highest concentration obtained was 0.883 mM (25.2% yield) when using the higher initial lactose concentration (584 mM). Furthermore, the lower donor/acceptor ratio had the highest synthesis, so at the molar ratio of 0.001, a concentration of 0.286 mM was obtained (32.5% yield).

Biohydrogen Production from Pineapple Waste: Effect of Substrate Concentration and Acid Pretreatment

NASA Astrophysics Data System (ADS)

Cahyari, K.; Putri, A. M.; Oktaviani, E. D.; Hidayat, M. A.; Norajsha, J. D.

2018-05-01

Biohydrogen is the ultimate choice of energy carrier in future due to its superior qualities such as fewer greenhouse gases emission, high energy density (142 kJ/gram), and high energy conversion using a fuel cell. Production of biohydrogen from organic waste e.g. pineapple waste offers a simultaneous solution for renewable energy production and waste management. It is estimated that pineapple cultivation in Indonesia generated more than 1 million ton/year comprising of rotten pineapple fruit, leaves, and stems. Majority of this waste is dumped into landfill area without any treatments which lead to many environmental problems. This research was meant to investigate the utilization of pineapple waste i.e. peel and the core of pineapple fruit and leaves to produce biohydrogen through mesophilic dark fermentation (30°C, 1 atm, pH 5.0). Effect of dilute acid treatment and substrate concentration was particularly investigated in these experiments. Peel and core of pineapple waste were subjected to fermentation at 3 various substrate concentration i.e. 8.8, 17.6 and 26.4-gram VS/liter. Meanwhile, pineapple leaves were pretreated using dilute acid (H2SO4) at 0.2, 0.3 and 0.4 N and followed by dark fermentation. Results show that the highest yield of biohydrogen was obtained at a substrate concentration of 26.4-gram VS/liter both for peel and core of the waste. Pretreatment using dilute acid (H2SO4) 0.3 N might improve fermentation process with a higher yield at 0.8 ml/gram VS. Hydrogen percentage in biogas produced during fermentation process was in the range between 5 – 32% of volume ratio. In summary, it is possible to utilize pineapple waste for production of biohydrogen at an optimum substrate concentration of 26.4-gram VS/liter and acid pretreatment (H2SO4) of 0.3 N.

Pretreatment process for forming a smooth surface diamond film on a carbon-coated substrate

DOEpatents

Feng, Z.; Brewer, M.; Brown, I.; Komvopoulos, K.

1994-05-03

A process is disclosed for the pretreatment of a carbon-coated substrate to provide a uniform high density of nucleation sites thereon for the subsequent deposition of a continuous diamond film without the application of a bias voltage to the substrate. The process comprises exposing the carbon-coated substrate, in a microwave plasma enhanced chemical vapor deposition system, to a mixture of hydrogen-methane gases, having a methane gas concentration of at least about 4% (as measured by partial pressure), while maintaining the substrate at a pressure of about 10 to about 30 Torr during the pretreatment. 6 figures.

Ag/SiO2 surface-enhanced Raman scattering substrate for plasticizer detection

NASA Astrophysics Data System (ADS)

Wu, Ming-Chung; Lin, Ming-Pin; Lin, Ting-Han; Su, Wei-Fang

2018-04-01

In this study, we demonstrated a simple method of fabricating a high-performance surface-enhanced Raman scattering (SERS) substrate. Monodispersive SiO2 colloidal spheres were self-assembled on a silicon wafer, and then a silver layer was coated on it to obtain a Ag/SiO2 SERS substrate. The Ag/SiO2 SERS substrates were used to detect three kinds of plasticizer with different concentrations, namely, including bis(2-ethylhexyl)phthalate (DEHP), benzyl butyl phthalate (BBP), and dibutyl phthalate (DBP). The enhancement of Raman scattering intensity caused by surface plasmon resonance can be observed using the Ag/SiO2 SERS substrates. The Ag/SiO2 SERS substrate with a 150-nm-thick silver layer can detect plasticizers, and it satisfies the detection limit of plasticizers at 100 ppm. The developed highly sensitive Ag/SiO2 SERS substrates show a potential for the design and fabrication of functional sensors to identify the harmful plasticizers that plastic products release in daily life.

Deposition of an Ultraflat Graphene Oxide Nanosheet on Atomically Flat Substrates

NASA Astrophysics Data System (ADS)

Khan, M. Z. H.; Shahed, S. M. F.; Yuta, N.; Komeda, T.

2017-07-01

In this study, graphene oxide (GO) sheets produced in the form of stable aqueous dispersions were deposited on Au (111), freshly cleaved mica, and highly oriented pyrolytic graphite (HOPG) substrates. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to study the presence and distinct contact of GO sheets on the substrates. It was revealed from the topography images that high-quality ultraflat GO monolayer sheets formed on the substrates without distinct cracking/wrinkling or folding. GO sheets with apparent height variation observed by microscopy also indicate ultraflat deposition with clear underlying steps. It was observed that ultrasonication and centrifuge steps prior to deposition were very effective for getting oxidation debris (OD)-free ultraflat single monolayer GO nanosheets onto substrates and that the process depends on the concentration of supplied GO solutions.

Direct Observation of Asphaltene Nanoparticles on Model Mineral Substrates.

PubMed

Raj, Gijo; Lesimple, Alain; Whelan, Jamie; Naumov, Panče

2017-06-27

The propensity for adherence to solid surfaces of asphaltenes, a complex solubility class of heteropolycyclic aromatic compounds from the heavy fraction of crude oil, has long been the root cause of scale deposition and remains an intractable problem in the petroleum industry. Although the adhesion is essential to understanding the process of asphaltene deposition, the relationship between the conformation of asphaltene molecules on mineral substrates and its impact on adhesion and mechanical properties of the deposits is not completely understood. To rationalize the primary processes in the process of organic scale deposition, here we use atomic force microscopy (AFM) to visualize the morphology of petroleum asphaltenes deposited on model mineral substrates. High imaging contrast was achieved by the differential adhesion of the tip between asphaltenes and the mineral substrate. While asphaltenes form smooth continuous films on all substrates at higher concentrations, they deposit as individual nanoparticles at lower concentrations. The size, shape, and spatial distribution of the nanoaggregates are strongly affected by the nature of the substrate; while uniformly distributed spherical particles are formed on highly polar and hydrophilic substrates (mica), irregular islands and thicker patches are observed with substrates of lower polarity (silica and calcite). Asphaltene nanoparticles flatten when adsorbed on highly oriented pyrolytic graphite due to π-π interactions with the polycyclic core. Force-distance profiles provide direct evidence of the conformational changes of asphaltene molecules on hydrophilic/hydrophobic substrates that result in dramatic changes in adhesion and mechanical properties of asphaltene deposits. Such an understanding of the nature of adhesion and mechanical properties tuned by surface properties, on the level of asphaltene nanoaggregates, would contribute to the design of efficient asphaltene inhibitors for preventing asphaltene fouling on targeted surfaces. Unlike flat surfaces, the AFM phase contrast images of defected calcite surfaces show that asphaltenes form continuous deposits to fill the recesses, and this process could trigger the onset for asphaltene deposition.

Effect of Trisodium Citrate Concentration on the Structural and Photodiode Performance of CdO Thin Films

NASA Astrophysics Data System (ADS)

Ravikumar, M.; Valanarasu, S.; Chandramohan, R.; Jacob, S. Santhosh Kumar; Kathalingam, A.

2015-08-01

CdO thin films were deposited on glass and silicon substrates by simple perfume atomizer at 350°C using cadmium acetate and trisodium citrate (TSC). The effect of the TSC concentration on the structural, morphological, optical, and photoconductive properties of the prepared CdO thin films was investigated. X-Ray diffraction (XRD) studies of the deposited films revealed improvement in crystalline nature with increase of TSC concentration. Films prepared without TSC showed porous nature, not fully covering the substrate, whereas films prepared using TSC exhibited full coverage of the substrate with uniform particles. Optical transmittance study of the films showed high transmittance (50% to 60%), and the absorption edge was found to shift towards the red region depending on the TSC concentration. The films exhibited a direct band-to-band transition with bandgap varying between 2.31 eV and 2.12 eV. Photoconductivity studies of the n-CdO/ p-Si structure for various TSC concentrations were also carried out. I- V characteristics of this n-CdO/ p-Si structure revealed the formation of rectifying junctions, and its photoconductivity was found to increase with the TSC concentration.

Anaerobic digestion of slaughterhouse waste: main process limitations and microbial community interactions.

PubMed

Palatsi, J; Viñas, M; Guivernau, M; Fernandez, B; Flotats, X

2011-02-01

Fresh pig/cattle slaughterhouse waste mixtures, with different lipid-protein ratios, were characterized and their anaerobic biodegradability assessed in batch tests. The resultant methane potentials were high (270-300 L(CH4) kg(-1)(COD)) making them interesting substrates for the anaerobic digestion process. However, when increasing substrate concentrations in consecutive batch tests, up to 15 g(COD) kg(-1), a clear inhibitory process was monitored. Despite the reported severe inhibition, related to lipid content, the system was able to recover activity and successfully degrade the substrate. Furthermore, 16SrRNA gene-based DGGE results showed an enrichment of specialized microbial populations, such as β-oxidizing/proteolitic bacteria (Syntrophomonas sp., Coprothermobacter sp. and Anaerobaculum sp.), and syntrophic methanogens (Methanosarcina sp.). Consequently, the lipid concentration of substrate and the structure of the microbial community are the main limiting factors for a successful anaerobic treatment of fresh slaughterhouse waste. Copyright © 2010 Elsevier Ltd. All rights reserved.

Portulaca grandiflora as green roof vegetation: Plant growth and phytoremediation experiments.

PubMed

Vijayaraghavan, K; Arockiaraj, Jesu; Kamala-Kannan, Seralathan

2017-06-03

Finding appropriate rooftop vegetation may improve the quality of runoff from green roofs. Portulaca grandiflora was examined as possible vegetation for green roofs. Green roof substrate was found to have low bulk density (360.7 kg/m 3 ) and high water-holding capacity (49.4%), air-filled porosity (21.1%), and hydraulic conductivity (5270 mm/hour). The optimal substrate also supported the growth of P. grandiflora with biomass multiplication of 450.3% and relative growth rate of 0.038. Phytoextraction potential of P. grandiflora was evaluated using metal-spiked green roof substrate as a function of time and spiked substrate metal concentration. It was identified that P. grandiflora accumulated all metals (Al, Cd, Cr, Cu, Fe, Ni, Pb, and Zn) from metal-spiked green roof substrate. At the end of 40 days, P. grandiflora accumulated 811 ± 26.7, 87.2 ± 3.59, 416 ± 15.8, 459 ± 15.6, 746 ± 20.9, 357 ± 18.5, 565 ± 6.8, and 596 ± 24.4 mg/kg of Al, Cd, Cr, Cu, Fe, Ni, Pb and Zn, respectively. Results also indicated that spiked substrate metal concentration strongly influenced metal accumulation property of P. grandiflora with metal uptake increased and accumulation factor decreased with increase in substrate metal concentration. P. grandiflora also showed potential to translocate all the examined metals with translocation factor greater than 1 for Al, Cu, Fe, and Zn, indicating hyperaccumulation property.

Diverse 2D structures obtained by adsorption of charged ABA triblock copolymer on different surfaces

NASA Astrophysics Data System (ADS)

Kontturi, Katri S.; Vesterinen, Arja-Helena; Seppälä, Jukka; Laine, Janne

2012-11-01

In the larger context of 2D polymeric structures, the morphologies obtained by adsorption and subsequent drying of charged, ABA type amphiphilic triblock copolymer of poly[2-(dimethylamino)ethyl metacrylate] (PDMAEMA) and poly(propylene oxide) (PPO) were investigated with atomic force microscopy and X-ray photoelectron spectroscopy as well as in situ adsorption analysis with quartz crystal microbalance with dissipation monitoring. Hydrophilic silica and hydrophobic polystyrene (PS) were used as substrates for adsorption. The structures emerging from the self-assembly of adsorbing polymer were profoundly influenced by composition of the aqueous solution and the choice of substrate. When adsorbed from dilute polymer solution where the concentration is so low that the polymer does not yet show surface-active behavior, the triblock copolymer unimers associated on hydrophilic silica surface forming large, irregular clustered aggregates, with sizes increasing with electrolyte concentration of the solution. On a hydrophobic PS substrate, on the other hand, unimers spread much more evenly, forming clear surface patterns. The roughness of these patterned structures was tuned with the electrolyte concentration of the solution. Adsorption from a more concentrated polymer solution, where the surface-activity of the polymer is perceptible, resulted in the formation of a smooth film with complete coverage over the hydrophilic silica substrate when the electrolyte concentration was high. On PS, on the other hand, nucleation of evenly scattered globular, disk-like micelles was induced. Besides the dry film morphology, the even distribution of the irreversibly adsorbed polymer over the PS surface was likely to serve as an optimal platform for the build-up of reversible hydrophobically bound multilayers at high electrolyte concentration. The multilayer formation was reversible because a decrease in the electrolyte concentration of the solution re-introduces strong electrostatic repulsion between the multilayered polymer coils which results in breakdown of the layer.

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.

Study on the aerobic biodegradability and degradation kinetics of 3-NP; 2,4-DNP and 2,6-DNP.

PubMed

She, Zonglian; Xie, Tian; Zhu, Yingjie; Li, Leilei; Tang, Gaifeng; Huang, Jian

2012-11-30

Four biodegradability tests (BOD(5)/COD ratio, production of carbon dioxide, relative oxygen uptake rate and relative enzymatic activity) were used to determine the aerobic biodegradability of 3-nitrophenol (3-NP), 2,4-dinitrophenol (2,4-DNP) and 2,6-dinitrophenol (2,6-DNP). Furthermore, biodegradation kinetics of the compounds was investigated in sequencing batch reactors both in the presence of glucose (co-substrate) and with nitrophenol as the sole carbon source. Among the three tested compounds, 3-NP showed the best biodegradability while 2,6-DNP was the most difficult to be biodegraded. The Haldane equation was applied to the kinetic test data of the nitrophenols. The kinetic constants are as follows: the maximum specific degradation rate (K(max)), the saturation constants (K(S)) and the inhibition constants (K(I)) were in the range of 0.005-2.98 mg(mgSS d)(-1), 1.5-51.9 mg L(-1) and 1.8-95.8 mg L(-1), respectively. The presence of glucose enhanced the degradation of the nitrophenols at low glucose concentrations. The degradation of 3-NP was found to be accelerated with the increasing of glucose concentrations from 0 to 660 mg L(-1). At high (1320-2000 mg L(-1)) glucose concentrations, the degradation rate of 3-NP was reduced and the K(max) of 3-NP was even lower than the value obtained in the absence of glucose, suggesting that high concentrations of co-substrate could inhibit 3-NP biodegradation. At 2,4-DNP concentration of 30 mg L(-1), the K(max) of 2,4-DNP with glucose as co-substrate was about 30 times the value with 2,4-DNP as sole substrate. 2,6-DNP preformed high toxicity in the case of sole carbon source degradation and the kinetic data was hardly obtained. Copyright © 2012 Elsevier B.V. All rights reserved.

A model of extracellular enzymes in free-living microbes: which strategy pays off?

PubMed

Traving, Sachia J; Thygesen, Uffe H; Riemann, Lasse; Stedmon, Colin A

2015-11-01

An initial modeling approach was applied to analyze how a single, nonmotile, free-living, heterotrophic bacterial cell may optimize the deployment of its extracellular enzymes. Free-living cells live in a dilute and complex substrate field, and to gain enough substrate, their extracellular enzymes must be utilized efficiently. The model revealed that surface-attached and free enzymes generate unique enzyme and substrate fields, and each deployment strategy has distinctive advantages. For a solitary cell, surface-attached enzymes are suggested to be the most cost-efficient strategy. This strategy entails potential substrates being reduced to very low concentrations. Free enzymes, on the other hand, generate a radically different substrate field, which suggests significant benefits for the strategy if free cells engage in social foraging or experience high substrate concentrations. Swimming has a slight positive effect for the attached-enzyme strategy, while the effect is negative for the free-enzyme strategy. The results of this study suggest that specific dissolved organic compounds in the ocean likely persist below a threshold concentration impervious to biological utilization. This could help explain the persistence and apparent refractory state of oceanic dissolved organic matter (DOM). Microbial extracellular enzyme strategies, therefore, have important implications for larger-scale processes, such as shaping the role of DOM in ocean carbon sequestration. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Fabrication of novel compound SERS substrates composed of silver nanoparticles and porous gold nanoclusters: A study on enrichment detection of urea

NASA Astrophysics Data System (ADS)

Li, Yali; Li, Qianwen; Sun, Chengbin; Jin, Sila; Park, Yeonju; Zhou, Tieli; Wang, Xu; Zhao, Bing; Ruan, Weidong; Jung, Young Mee

2018-01-01

A new type of surface-enhanced Raman scattering (SERS) substrate was fabricated through the layer-by-layer self-assembly of silver nanoparticles (AgNPs, av. 45 nm in diameter) and porous gold nanoclusters/nanoparticles (AuNPs, av. 143 nm in diameter). The development of the porosity of the AuNPs was investigated, and successful SERS applications of the porous AuNPs were also examined. As compared with AgNP films, the enhancement factor of Ag-Au compound substrates is increased 6 times at the concentration of 10-6 M. This additional enhancement contributes to the trace-amount-detection of target molecules enormously. The contribution is generated through the increase of the usable surface area arising from the nanoscale pores distributed three-dimensionally in the porous AuNPs, which enrich the adsorption sites and hot spots for the adsorption of probe molecules, making the developed nanofilms highly sensitive SERS substrates. The substrates were used for the detection of a physiological metabolite of urea molecules. The results reached to a very low concentration of 1 mM and exhibited good quantitative character over the physiological concentration range (1 ∼ 20 mM) under mimicking biophysical conditions. These results show that the prepared substrate has great potential in the ultrasensitive SERS-based detection and in SERS-based biosensors.

Effect of surface chemical composition on the surface potential and iso-electric point of silicon substrates modified with self-assembled monolayers.

PubMed

Kuo, Che-Hung; Chang, Hsun-Yun; Liu, Chi-Ping; Lee, Szu-Hsian; You, Yun-Wen; Shyue, Jing-Jong

2011-03-07

Self-assembled monolayer (SAM)-modified nano-materials are a new technology to deliver drug molecules. While the majority of these depend on covalently immobilizing molecules on the surface, it is proposed that electrostatic interactions may be used to deliver drugs. By tuning the surface potential of solid substrates with SAMs, drug molecules could be either absorbed on or desorbed from substrates through the difference in electrostatic interactions around the selected iso-electric point (IEP). In this work, the surface of silicon substrates was tailored with various ratios of 3-aminopropyltrimethoxysilane (APTMS) and 3-mercaptopropyltrimethoxysilane (MPTMS), which form amine- and thiol-bearing SAMs, respectively. The ratio of the functional groups on the silicon surface was quantified by X-ray photoelectron spectrometry (XPS); in general, the deposition kinetics of APTMS were found to be faster than those of MPTMS. Furthermore, for solutions with high MPTMS concentrations, the relative deposition rate of APTMS increased dramatically due to the acid-base reaction in the solution and subsequent electrostatic interactions between the molecules and the substrate. The zeta potential in aqueous electrolytes was determined with an electro-kinetic analyzer. By depositing SAMs of binary functional groups in varied ratios, the surface potential and IEP of silicon substrates could be fine-tuned. For <50% amine concentration in SAMs, the IEP changed linearly with the chemical composition from <2 to 7.18. For higher amine concentrations, the IEP slowly increased with concentration to 7.94 because the formation of hydrogen-bonding suppressed the subsequent protonation of amines.

Lost Mold Rapid Infiltration Forming of Mesoscale Ceramics: Part 1, Fabrication

PubMed Central

Antolino, Nicholas E.; Hayes, Gregory; Kirkpatrick, Rebecca; Muhlstein, Christopher L.; Frecker, Mary I.; Mockensturm, Eric M.; Adair, James H.

2009-01-01

Free-standing mesoscale (340 μm × 30 μm × 20 μm) bend bars with an aspect ratio over 15:1 and an edge resolution as fine as a single grain diameter (∼400 nm) have been fabricated in large numbers on refractory ceramic substrates by combining a novel powder processing approach with photoresist molds and an innovative lost-mold thermal process. The colloid and interfacial chemistry of the nanoscale zirconia particulates has been modeled and used to prepare highly concentrated suspensions. Engineering solutions to challenges in mold fabrication and casting have yielded free-standing, crack-free parts. Molds are fabricated using high-aspect-ratio photoresist on ceramic substrates. Green parts are formed using a rapid infiltration method that exploits the shear thinning behavior of the highly concentrated ceramic suspension in combination with gelcasting. The mold is thermally decomposed and the parts are sintered in place on the ceramic substrate. Chemically aided attrition milling disperses and concentrates the as-received 3Y-TZP powder to produce a dense, fine-grained sintered microstructure. Initial three-point bend strength data are comparable to that of conventional zirconia; however, geometric irregularities (e.g., trapezoidal cross sections) are present in this first generation and are discussed with respect to the distribution of bend strength. PMID:19809595

Cobalt- and platinum-rich ferromanganese crusts and associated substrate rocks from the Marshall Islands

USGS Publications Warehouse

Hein, J.R.; Schwab, W.C.; Davis, A.

1988-01-01

Ferromanganese crusts cover most hard substrates on seafloor edifices in the central Pacific basin. Crust samples and their associated substrates from seven volcanic edifices of Cretaceous age along the Ratak chain of the Marshall Islands are discussed. The two most abundant substrate lithologies recovered were limestone, dominantly fore-reef slope deposits, and volcanic breccia composed primarily of differentiated alkalic basalt and hawaiite clasts in a phosphatized carbonate matrix. The degree of mass wasting on the slopes of these seamounts is inversely correlated with the thickness of crusts. Crusts are generally thin on limestone substrate. Away from areas of active mass-wasting processes, and large atolls, crusts may be as thick as 10 cm maximum. The dominant crystalline phase in the Marshall Islands crusts is ??-MnO2 (vernadite). High concentrations of cobalt, platinum and rhodium strongly suggest that the Marshall Islands crusts are a viable source for these important metals. Many metals and the rare earth elements vary significantly on a fine scale through most crusts, thus reflecting the abundances of different host mineral phases in the crusts and changes in seawater composition with time. High concentrations of cobalt, nickel, titanium, zinc, lead, cerium and platinum result from a combination of their substitution in the iron and manganese phases and their oxidation potential. ?? 1988.

Alternating gradient photodetector

NASA Technical Reports Server (NTRS)

Overhauser, Albert W. (Inventor); Maserjian, Joseph (Inventor)

1989-01-01

A far infrared (FIR) range responsive photodetector is disclosed. There is a substrate of degenerate germanium. A plurality of alternating impurity-band and high resistivity layers of germanium are disposed on the substrate. The impurity-band layers have a doping concentration therein sufficiently high to include donor bands which can release electrons upon impingement by FIR photons of energy hv greater than an energy gap epsilon. The high resistivity layers have a doping concentration therein sufficiently low as to not include conducting donor bands and are depleted of electrons. Metal contacts are provided for applying an electrical field across the substrate and the plurality of layers. In the preferred embodiment as shown, the substrate is degenerate n-type (N++) germanium; the impurity-band layers are n+ layers of germanium doped to approximately the low 10(exp 16)/cu cm range; and, the high resistivity layers are n-layers of germanium doped to a maximum of approximately 10(exp)/cu cm. Additionally, the impurity-band layers have a thickness less than a conduction-electron diffusion length in germanium and likely to be in the range of 0.1 to 1.0 micron, the plurality of impurity-bands is of a number such that the flux of FIR photons passing therethrough will be substantially totally absorbed therein, the thickness of the high resistivity layers is such compared to the voltage applied that the voltage drop in each the high resistivity layers controls the occurence of impact ionization in the impurity-band layers to a desired level.

Chemistry of Sulfur-Contaminated Soil Substrate from a Former Frasch Extraction Method Sulfur Mine Leachate with Various Forms of Litter in a Controlled Experiment.

PubMed

Likus-Cieślik, Justyna; Pietrzykowski, Marcin; Chodak, Marcin

2018-01-01

The impact of tree litter on soil chemistry leachate and sulfurous substrates of mine soils from former Jeziórko sulfur mine was investigated. Composites were used: soil substrate (less contaminated at mean 5090 mg kg -1  S or high contaminated at 42,500 mg kg -1  S) + birch or pine litter and control substrate (no litter). The composites were rinsed with distilled water over 12 weeks. In the obtained leachate, pH, EC, dissolved organic carbon, N, Ca, Mg, Al, and S were determined. Physicochemical parameters of the substrates and their basal respiration rate were determined. Rinsing and litter application lowered sulfur concentration in high contamination substrates. Pine litter application decreased EC and increased pH of the low-contaminated substrate. The substrate pH remained at low phytotoxic level (i.e., below 3.0), resulting in the low biological activity of the composites. Birch litter application increased leaching of N and Mg, indicating the possibility of an intensification of soil-forming processes in contaminated sites.

Growth of high-quality AlN epitaxial film by optimizing the Si substrate surface

NASA Astrophysics Data System (ADS)

Huang, Liegen; Li, Yuan; Wang, Wenliang; Li, Xiaochan; zheng, Yulin; Wang, Haiyan; Zhang, Zichen; Li, Guoqiang

2018-03-01

High-quality AlN epitaxial films have been grown on Si substrates by optimizing the hydrofluoric acid (HF) solution for cleaning of Si substrates. Effect of the Si substrate surface on the surface morphology and structural property of AlN epitaxial films is investigated in detail. It is revealed that as the concentration of HF solution increases from 0 to 2.0%, the surface morphology and the crystalline quality are initially improved and then get worse, and show an optimized value at 1.5%. The as-grown ∼200 nm-thick AlN epitaxial films on Si substrates grown with HF solution of 1.5% reveal the root-mean-square (RMS) surface roughness of 0.49 nm and the full-width at half-maximum for AlN(0002) X-ray rocking curve of 0.35°, indicating the smooth surface morphology and the high crystalline quality. The corresponding mechanism is proposed to interpret the effect of Si substrate surface on surface morphology and structural property of AlN epitaxial films, and provides an effective approach for the perspective fabrication of AlN-based devices.

SiN sub x passivation of silicon surfaces

NASA Technical Reports Server (NTRS)

Olsen, L. C.

1986-01-01

The objectives were to perform surface characterization of high efficiency n+/p and p+/n silicon cells, to relate surface density to substrate dopant concentration, and to identify dominant current loss mechanisms in high efficiency cells. The approach was to measure density of states on homogeneously doped substrates with high frequency C-V and Al/SiN sub x/Si structures; to investigate density of states and photoresponse of high efficiency N+/P and P+/N cells; and to conduct I-V-T studies to identify current loss nechanisms in high efficiency cells. Results are given in tables and graphs.

Cystathionine β-Synthase Inhibition Is a Potential Therapeutic Approach to Treatment of Ischemic Injury

PubMed Central

Chan, Su Jing; Chai, Chou; Lim, Tze Wei; Yamamoto, Mie; Lo, Eng H; Lai, Mitchell Kim Peng

2015-01-01

Hydrogen sulfide (H2S) has been reported to exacerbate stroke outcome in experimental models. Cystathionine β-synthase (CBS) has been implicated as the predominant H2S-producing enzyme in central nervous system. When SH-SY5Y cells were transfected to overexpress CBS, these cells were able to synthesize H2S when exposed to high levels of enzyme substrates but not substrate concentrations that may reflect normal physiological conditions. At the same time, these cells demonstrated exacerbated cell death when subjected to oxygen and glucose deprivation (OGD) together with high substrate concentrations, indicating that H2S production has a detrimental effect on cell survival. This effect could be abolished by CBS inhibition. The same effect was observed with primary astrocytes exposed to OGD and high substrates or sodium hydrosulfide. In addition, CBS was upregulated and activated by truncation in primary astrocytes subjected to OGD. When rats were subjected to permanent middle cerebral artery occlusion, CBS activation was also observed. These results imply that in acute ischemic conditions, CBS is upregulated and activated by truncation causing an increased production of H2S, which exacerbate the ischemic injuries. Therefore, CBS inhibition may be a viable approach to stroke treatment. PMID:25873304

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.

Applications of Quantum Cascade Laser Scanners for Remote Detection of Chemical and Biological Threats and Weapons of Mass Destruction

DTIC Science & Technology

2014-07-09

Rivera. Highly Sensitive Filter Paper Substrate for SERS Trace Explosives Detection , International Journal of Spectroscopy, (09 2012): 0. doi: 10.1155...Highly Sensitive Filter Paper Substrate for SERS Field Detection of Trace Threat Chemicals”, PITTCON-2013: Forensic Analysis in the Lab and Crime Scene...the surface. In addition, built-in algorithms were used for nearly real-time sample detection . Trace and bulk concentrations of the other substances

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

NASA Astrophysics Data System (ADS)

Peng, Cheng-Jien

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

Influence of Substrate Temperature on Structural, Electrical and Optical Properties of Ito Thin Films Prepared by RF Magnetron Sputtering

NASA Astrophysics Data System (ADS)

He, Bo; Zhao, Lei; Xu, Jing; Xing, Huaizhong; Xue, Shaolin; Jiang, Meng

2013-10-01

In this paper, we investigated indium-tin-oxide (ITO) thin films on glass substrates deposited by RF magnetron sputtering using ceramic target to find the optimal condition for fabricating optoelectronic devices. The structural, electrical and optical properties of the ITO films prepared at various substrate temperatures were investigated. The results indicate the grain size increases with substrate temperature increases. As the substrate temperature grew up, the resistivity of ITO films greatly decreased. The ITO film possesses high quality in terms of electrode functions, when substrate temperature is 480°C. The resistivity is as low as 9.42 × 10-5 Ω•cm, while the carrier concentration and mobility are as high as 3.461 × 1021 atom/cm3 and 19.1 cm2/Vṡs, respectively. The average transmittance of the film is about 95% in the visible region. The novel ITO/np-Silicon frame, which prepared by RF magnetron sputtering at 480°C substrate temperature, can be used not only for low-cost solar cell, but also for high quantum efficiency of UV and visible lights enhanced photodetector for various applications.

Investigation of AlGaN/GaN high electron mobility transistor structures on 200-mm silicon (111) substrates employing different buffer layer configurations.

PubMed

Lee, H-P; Perozek, J; Rosario, L D; Bayram, C

2016-11-21

AlGaN/GaN high electron mobility transistor (HEMT) structures are grown on 200-mm diameter Si(111) substrates by using three different buffer layer configurations: (a) Thick-GaN/3 × {Al x Ga 1-x N}/AlN, (b) Thin-GaN/3 × {Al x Ga 1-x N}/AlN, and (c) Thin-GaN/AlN, so as to have crack-free and low-bow (<50 μm) wafer. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, high resolution-cross section transmission electron microscopy, optical microscopy, atomic-force microscopy, cathodoluminescence, Raman spectroscopy, X-ray diffraction (ω/2θ scan and symmetric/asymmetric ω scan (rocking curve scan), reciprocal space mapping) and Hall effect measurements are employed to study the structural, optical, and electrical properties of these AlGaN/GaN HEMT structures. The effects of buffer layer stacks (i.e. thickness and content) on defectivity, stress, and two-dimensional electron gas (2DEG) mobility and 2DEG concentration are reported. It is shown that 2DEG characteristics are heavily affected by the employed buffer layers between AlGaN/GaN HEMT structures and Si(111) substrates. Particularly, we report that in-plane stress in the GaN layer affects the 2DEG mobility and 2DEG carrier concentration significantly. Buffer layer engineering is shown to be essential for achieving high 2DEG mobility (>1800 cm 2 /V∙s) and 2DEG carrier concentration (>1.0 × 10 13  cm -2 ) on Si(111) substrates.

Investigation of AlGaN/GaN high electron mobility transistor structures on 200-mm silicon (111) substrates employing different buffer layer configurations

PubMed Central

Lee, H.-P.; Perozek, J.; Rosario, L. D.; Bayram, C.

2016-01-01

AlGaN/GaN high electron mobility transistor (HEMT) structures are grown on 200-mm diameter Si(111) substrates by using three different buffer layer configurations: (a) Thick-GaN/3 × {AlxGa1−xN}/AlN, (b) Thin-GaN/3 × {AlxGa1−xN}/AlN, and (c) Thin-GaN/AlN, so as to have crack-free and low-bow (<50 μm) wafer. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, high resolution-cross section transmission electron microscopy, optical microscopy, atomic-force microscopy, cathodoluminescence, Raman spectroscopy, X-ray diffraction (ω/2θ scan and symmetric/asymmetric ω scan (rocking curve scan), reciprocal space mapping) and Hall effect measurements are employed to study the structural, optical, and electrical properties of these AlGaN/GaN HEMT structures. The effects of buffer layer stacks (i.e. thickness and content) on defectivity, stress, and two-dimensional electron gas (2DEG) mobility and 2DEG concentration are reported. It is shown that 2DEG characteristics are heavily affected by the employed buffer layers between AlGaN/GaN HEMT structures and Si(111) substrates. Particularly, we report that in-plane stress in the GaN layer affects the 2DEG mobility and 2DEG carrier concentration significantly. Buffer layer engineering is shown to be essential for achieving high 2DEG mobility (>1800 cm2/V∙s) and 2DEG carrier concentration (>1.0 × 1013 cm−2) on Si(111) substrates. PMID:27869222

First-principles study of hydrogen adsorption in metal-doped COF-10

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

Wu Miaomiao; Sun Qiang; Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284

2010-10-21

Covalent organic frameworks (COFs), due to their low-density, high-porosity, and high-stability, have promising applications in gas storage. In this study we have explored the potential of COFs doped with Li and Ca metal atoms for storing hydrogen under ambient thermodynamic conditions. Using density functional theory we have performed detailed calculations of the sites Li and Ca atoms occupy in COF-10 and their interaction with hydrogen molecules. The binding energy of Li atom on COF-10 substrate is found to be about 1.0 eV and each Li atom can adsorb up to three H{sub 2} molecules. However, at high concentration, Li atomsmore » cluster and, consequently, their hydrogen storage capacity is reduced due to steric hindrance between H{sub 2} molecules. On the other hand, due to charge transfer from Li to the substrate, O sites provide additional enhancement for hydrogen adsorption. With increasing concentration of doped metal atoms, the COF-10 substrate provides an additional platform for storing hydrogen. Similar conclusions are reached for Ca doped COF-10.« less

Fabrication of a superhydrophobic and high-glossy copper coating on aluminum substrates

NASA Astrophysics Data System (ADS)

Yang, Hao; He, Yuantao; Wu, Zhongqiang; Miao, Jing; Yang, Fang; Lu, Zhong

2018-03-01

Superhydrophobic metal coatings have been extensively studied in recent years because of their significant potential applications. Unfortunately, most of them lost the original metallic luster due to the micro/nano binary structures. In this paper, a facile method was developed to prepare a superhydrophobic and high-glossy copper coating on aluminum substrates. The bionic lotus leaf surfaces were constructed by electroless plating method and further modified with octadecanethiol. The wettability and gloss could be tuned by the concentration of the precursor. With the increase of CuSO4 concentration, the surface roughness of the coating raised, thus resulting in increase of contact angle and decrease of glossiness. When the CuSO4 concentration was 30 mmol/L, the coating exhibited a sub-micro/nano binary structure, in which 20-30 nm protuberances were grown on 300-500 nm mastoids. Such special morphology endowed the coating with superhydrophobic and high-glossy properties, and the coating also showed ultra-low water adhesion and stable dynamic water repellence.

Studies on choline permeation through the plasma membrane and its incorporation into phosphatidyl choline of Ehrlich-Lettré-ascites tumor cells in vitro.

PubMed

Haeffner, E W

1975-02-03

The initial rate of incorporation of 14C or 3H-labeled choline into Ehrlich-Lettre ascites cells of the glycogen-free strain seven days after inoculation was investigated in vitro. 1. At choline concentrations in the medium between 6 to 30 muM and 100 to 500 muM the choline uptake by the cells followed Michaelis-Menton Kinetics with V values between 31 to 100 and 59 to 500 pmol per minute at a given cell density, and average Q10-values of 2.1 at the high and of 2.4 at the low choline molarity. The K-m-values increased from 27 muM to 58.8 muM at low and from 0.11 mM to 0.22 mM at high choline concentrations over a temperature range between 15 degrees C and 37 degrees C. Arrhenius plot of the V values gave two lines, one with a transition temperature at 25 degrees C at low and one straight line at high choline concentrations, from which the energy of activation for choline uptake was determined to be 16 kcal/mol. 2. It is assumed that two systems exist for the choline uptake by the ascites cells. One, operative at low substrate concentrations, which is saturable and probably is to be classified as a carrier-mediated facilitated diffusion process, can be strongly inhibited by deoxyglucose or 2,4-dinitrophenol and also by substrate analogues such as chlorocholine or benzoylcholine. Ouabain affects this system to a lesser extent. The other system functioning at high choline concentrations may be a simple diffusion process, which is little inhibited by substrate analogues, ouabain and deoxyglucose; however, it is also inhibited by 2,4-dinitrophenol and p-chloromercuribenzoate. 3. Choline incorporation into the acid-insoluble material (lecithin) gave linear Michaelis-Menton kinetics at the low and the high substrate concentration respectively. K-m-values decreased with an increase in temperature at low and increased with rising temperature at high substrate concentrations thus reflecting a close relationship between choline uptake and its metabolism. Labeling of lecithin choline in the various subcellular fractions under the conditions of the functioning of a carrier-mediated process was in the order: mitochondria (50%) greater than plasma membranes (25%) greater nuclei (14%) greater than microsomes (9%) greater than supernatant (1.5%). 4. Treatment of the cells with p-chloromercuribenzoate or heat shock at 50 degrees C markedly reduced the cholinee uptake and concomitantly its conversion into lecithin. Kinetic analysis revealed that the inhibitory effect of p-chloromercuribenzoate was competitive and that of the heat shock non-competitive in nature. Further the choline uptake by the cells was found to be the rate-limiting step, since the rate of choline phosphorylation was determined by the extracellular choline concentration. Pulse chase experiments showed a rapid turnover of the choline moiety with a concomitant increase in activity of the lecithin fraction and little change within the choline phosphate pool.

Anaerobic monodigestion of poultry manure: determination of operational parameters for CSTR.

PubMed

Chamy, R; León, C; Vivanco, E; Poirrier, P; Ramos, C

2012-01-01

In this work the anaerobic monodigestion for the treatment of turkey manure was evaluated, without its codigestion with another substrate. The effect of the organic loading rate (OLR) and the substrate concentration (high total solids (TS) concentration) or product concentration (high volatile fatty acids (VFA) and/or ammonia (NH(3)-N) concentrations) was studied. The results show that for a continuous stirred tank reactor (CSTR) operation, a maximum of 40 g/L of TS and 4.0 g/L of ammonium (NH(4)(+)) was required. In addition, the maximum organic loading rate (OLR) will not exceed 1.5 kg VS/m(3)d. Higher TS and NH(4)(+) concentrations and OLR lead to a reduction on the methane productivity and volatile solids (VS) removal. During the CSTR operation, a high alkalinity concentration (above 10 g/L CaCO(3)) was found; this situation allowed maintaining a constant and appropriate pH (close to 7.8), despite the VFA accumulation. In this sense, the alkalinity ratio (α) is a more appropriate control and monitoring parameter of the reactor operation compared to pH. Additionally, with this parameter a VS removal of 80% with a methane productivity of 0.50 m(3)(CH4)/m(3)(R)d is achieved.

Growth of monolayer MoS2 films in a quasi-closed crucible encapsulated substrates by chemical vapor deposition

NASA Astrophysics Data System (ADS)

Yang, Yong; Pu, Hongbin; Lin, Tao; Li, Lianbi; Zhang, Shan; Sun, Gaopeng

2017-07-01

Monolayer molybdenum disulfide (m-MoS2) has attracted significant interest due to its unique electronic and optical properties. Herein, we report the successful fabrication of high quality and continuous m-MoS2 films in a quasi-closed crucible encapsulated substrates via a three-zone chemical vapor deposition (CVD) system. Quasi-closed crucible lowers the concentration of precursors around substrates and makes the sulfurization rate gentle, which is beneficial for invariable m-MoS2 growth. Characterization results indicate that as-grown m-MoS2 films are of high crystallinity and high quality comparable to the exfoliated MoS2. This approach is also adapted to the growth of other transition metal dichalcogenides.

Massive spalling of intermetallic compounds in solder-substrate reactions due to limited supply of the active element

NASA Astrophysics Data System (ADS)

Yang, S. C.; Ho, C. E.; Chang, C. W.; Kao, C. R.

2007-04-01

Massive spalling of intermetallic compounds has been reported in the literature for several solder/substrate systems, including SnAgCu soldered on Ni substrate, SnZn on Cu, high-Pb PbSn on Cu, and high-Pb PbSn on Ni. In this work, a unified thermodynamic argument is proposed to explain this rather unusual phenomenon. According to this argument, two necessary conditions must be met. The number one condition is that at least one of the reactive constituents of the solder must be present in a limited amount, and the second condition is that the soldering reaction has to be very sensitive to its concentration. With the growth of intermetallic, more and more atoms of this constituent are extracted out of the solder and incorporated into the intermetallic. As the concentration of this constituent decreases, the original intermetallic at the interface becomes a nonequilibrium phase, and the spalling of the original intermetallic occurs.

Massive spalling of intermetallic compounds in solder-substrate reactions due to limited supply of the active element

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

Yang, S. C.; Ho, C. E.; Chang, C. W.

2007-04-15

Massive spalling of intermetallic compounds has been reported in the literature for several solder/substrate systems, including SnAgCu soldered on Ni substrate, SnZn on Cu, high-Pb PbSn on Cu, and high-Pb PbSn on Ni. In this work, a unified thermodynamic argument is proposed to explain this rather unusual phenomenon. According to this argument, two necessary conditions must be met. The number one condition is that at least one of the reactive constituents of the solder must be present in a limited amount, and the second condition is that the soldering reaction has to be very sensitive to its concentration. With themore » growth of intermetallic, more and more atoms of this constituent are extracted out of the solder and incorporated into the intermetallic. As the concentration of this constituent decreases, the original intermetallic at the interface becomes a nonequilibrium phase, and the spalling of the original intermetallic occurs.« less

High Mobility SiGe/Si Transistor Structures on Sapphire Substrates Using Ion Implantation

NASA Technical Reports Server (NTRS)

Alterovitz, S. A.; Mueller, C. H.; Croke, E. T.

2003-01-01

High mobility n-type SiGe/Si transistor structures have been fabricated on sapphire substrates by ion implanting phosphorus ions into strained 100 Angstrom thick silicon channels for the first time. The strained Si channels were sandwiched between Si(sub 0.7)Ge(sub 0.3) layers, which, in turn, were deposited on Si(sub 0.7)Ge(sub 0.3) virtual substrates and graded SiGe buffer layers. After the molecular beam epitaxy (MBE) film growth process was completed, ion thick silicon channels implantation and post-annealing were used to introduce donors. The phosphorous ions were preferentially located in the Si channel at a peak concentration of approximately 1x10(exp 18)/cu cm. Room temperature electron mobilities exceeding 750 sq cm/V-sec at carrier densities of 1x10(exp 12)/sq cm were measured. Electron concentration appears to be the key factor that determines mobility, with the highest mobility observed for electron densities in the 1 - 2x10(exp 12)/sq cm range.

CO.sub.2 removal sorbent composition with high chemical stability during multiple cycles

DOEpatents

Siriwardane, Ranjani V.; Rosencwaig, Shira

2015-09-22

Disclosed herein is a clay-alkali-amine CO.sub.2 sorbent composition prepared by integrating a clay substrate, basic alkali salt, and amine liquid. The basic alkali salt is present relative to the clay substrate in a weight ratio of from about 1 part to about 50 parts per 100 parts of the clay substrate. The amine liquid is present relative to a clay-alkali combination in a weight ratio of from about 1 part to about 10 parts per 10 parts of the clay-alkali combination. The clay-alkali-amine C02 sorbent is particularly advantageous for low temperature CO.sub.2 removal cycles in a gas stream having a C02 concentration less than around 2000 ppm and an oxygen concentration around 21%, such as air.

Highly conductive homoepitaxial Si-doped Ga2O3 films on (010) β-Ga2O3 by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Leedy, Kevin D.; Chabak, Kelson D.; Vasilyev, Vladimir; Look, David C.; Boeckl, John J.; Brown, Jeff L.; Tetlak, Stephen E.; Green, Andrew J.; Moser, Neil A.; Crespo, Antonio; Thomson, Darren B.; Fitch, Robert C.; McCandless, Jonathan P.; Jessen, Gregg H.

2017-07-01

Si-doped Ga2O3 thin films were fabricated by pulsed laser deposition on semi-insulating (010) β-Ga2O3 and (0001) Al2O3 substrates. Films deposited on β-Ga2O3 showed single crystal, homoepitaxial growth as determined by high resolution transmission electron microscopy and x-ray diffraction. Corresponding films deposited on Al2O3 were mostly single phase, polycrystalline β-Ga2O3 with a preferred (20 1 ¯ ) orientation. An average conductivity of 732 S cm-1 with a mobility of 26.5 cm2 V-1 s-1 and a carrier concentration of 1.74 × 1020 cm-3 was achieved for films deposited at 550 °C on β-Ga2O3 substrates as determined by Hall-Effect measurements. Two orders of magnitude improvement in conductivity were measured using native substrates versus Al2O3. A high activation efficiency was obtained in the as-deposited condition. The high carrier concentration Ga2O3 thin films achieved by pulsed laser deposition enable application as a low resistance ohmic contact layer in β-Ga2O3 devices.

Strontium-90 concentration factors of lake plankton, macrophytes, and substrates.

PubMed

Kalnina, Z; Polikarpov, G

1969-06-27

The ratio of concentration of strontium-90 in living and inert lake components to that in lake water (concentration factors) was determined for plankton, macrophytes, and substrates in eutrophic, mesotropric-eutrophic, and dystrophic Latgalian lakes. Concentration factors of strontium-90 in aquatic organisms and substrates are higher in a dystrophic lake than in the other types.

Uptake of uranium by aquatic plants growing in fresh water ecosystem around uranium mill tailings pond at Jaduguda, India.

PubMed

Jha, V N; Tripathi, R M; Sethy, N K; Sahoo, S K

2016-01-01

Concentration of uranium was determined in aquatic plants and substrate (sediment or water) of fresh water ecosystem on and around uranium mill tailings pond at Jaduguda, India. Aquatic plant/substrate concentration ratios (CRs) of uranium were estimated for different sites on and around the uranium mill tailings disposal area. These sites include upstream and downstream side of surface water sources carrying the treated tailings effluent, a small pond inside tailings disposal area and residual water of this area. Three types of plant groups were investigated namely algae (filamentous and non-filamentous), other free floating & water submerged and sediment rooted plants. Wide variability in concentration ratio was observed for different groups of plants studied. The filamentous algae uranium concentration was significantly correlated with that of water (r=0.86, p<0.003). For sediment rooted plants significant correlation was found between uranium concentration in plant and the substrate (r=0.88, p<0.001). Both for other free floating species and sediment rooted plants, uranium concentration was significantly correlated with Mn, Fe, and Ni concentration of plants (p<0.01). Filamentous algae, Jussiaea and Pistia owing to their high bioproductivity, biomass, uranium accumulation and concentration ratio can be useful for prospecting phytoremediation of stream carrying treated or untreated uranium mill tailings effluent. Copyright © 2015 Elsevier B.V. All rights reserved.

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.

Ion Diffusion-Directed Assembly Approach to Ultrafast Coating of Graphene Oxide Thick Multilayers.

PubMed

Zhao, Xiaoli; Gao, Weiwei; Yao, Weiquan; Jiang, Yanqiu; Xu, Zhen; Gao, Chao

2017-10-24

The layer-by-layer (LbL) assembly approach has been widely used to fabricate multilayer coatings on substrates with multiple cycles, whereas it is hard to access thick films efficiently. Here, we developed an ion diffusion-directed assembly (IDDA) strategy to rapidly make multilayer thick coatings in one step on arbitrary substrates. To achieve multifunctional coatings, graphene oxide (GO) and metallic ions were selected as the typical building blocks and diffusion director in IDDA, respectively. With diffusion of metallic ions from substrate to negatively charged GO dispersion spontaneously (i.e., from high-concentration region to low-concentration region), GO was assembled onto the substrate sheet-by-sheet via sol-gel transformation. Because metallic ions with size of subnanometers can diffuse directionally and freely in the aqueous dispersion, GO was coated on the substrate efficiently, giving rise to films with desired thickness up to 10 μm per cycle. The IDDA approach shows three main merits: (1) high efficiency with a μm-scale coating rate; (2) controllability over thickness and evenness; and (3) generality for substrates of plastics, metals and ceramics with any shapes and morphologies. With these merits, IDDA strategy was utilized in the efficient fabrication of functional graphene coatings that exhibit outstanding performance as supercapacitors, electromagnetic interference shielding textiles, and anticorrosion coatings. This IDDA approach can be extended to other building blocks including polymers and colloidal nanoparticles, promising for the scalable production and application of multifunctional coatings.

Effect of a blend of essential oil compounds on the colonization of starch-rich substrates by bacteria in the rumen.

PubMed

Duval, S M; McEwan, N R; Graham, R C; Wallace, R J; Newbold, C J

2007-12-01

To investigate the mode of action of a blend of essential oil compounds on the colonization of starch-rich substrates by rumen bacteria. Starch-rich substrates were incubated, in nylon bags, in the rumen of sheep organized in a 4 x 4 latin square design and receiving a 60:40 silage : concentrate diet. The concentrate was either high or low in crude protein, and the diet was supplemented or not with a commercial blend of essential oil compounds (110 mg per day). The total genomic DNA was extracted from the residues in the bags. The total eubacterial DNA was quantified by real-time PCR and the proportion of Ruminobacter amylophilus, Streptococcus bovis and Prevotella bryantii was determined. Neither the supplementation with essential oil compounds nor the amount of crude protein affected the colonization of the substrates by the bacteria quantified. However, colonization was significantly affected by the substrate colonized. The effect of essential oils on the colonization of starch-rich substrates is not mediated through the selective inhibition of R. amylophilus. This study enhances our understanding of the colonization of starch-rich substrates, as well as of the mode of action of the essential oils as rumen manipulating agents.

Preparation of sorbent pellets with high integrity for sorption of CO.sub.2 from gas streams

DOEpatents

Siriwardane, Ranjani V.

2016-05-10

Method for the production of a CO.sub.2 sorbent prepared by integrating a clay substrate, basic alkali salt, amine liquid, hydraulic binder, and a liquid binder. The basic alkali salt is present relative to the clay substrate in a weight ratio of from about 1 part to about 50 parts per 100 parts of the clay substrate. The amine liquid is present relative to a clay-alkali combination in a weight ratio of from about 1 part to about 10 parts per 10 parts of the clay-alkali combination. The clay substrate and basic alkali salt may be combined in a solid-solid heterogeneous mixture and followed by introduction of the amine liquid. Alternatively, an alkaline solution may be blended with the amine solution prior to contacting the clay substrate. The clay-alkali-amine CO.sub.2 sorbent is particularly advantageous for low temperature CO.sub.2 removal cycles in a gas stream having a CO.sub.2 concentration less than around 2000 ppm and an oxygen concentration around 21%, such as air.

Advanced concentrator panels

NASA Technical Reports Server (NTRS)

Bell, D. M.; Bedard, R. J., Jr.

1981-01-01

The prototype fabrication of a lightweight, high-quality cellular glass substrate reflective panel for use in an advanced point-focusing solar concentrator was completed. The reflective panel is a gore shaped segment of an 11-m paraboloidal dish. The overall concentrator design and the design of the reflective panels are described. prototype-specific panel design modifications are discussed and the fabrication approach and procedure outlined.

Drug transport by reconstituted P-glycoprotein in proteoliposomes. Effect of substrates and modulators, and dependence on bilayer phase state.

PubMed

Lu, P; Liu, R; Sharom, F J

2001-03-01

The P-glycoprotein multidrug transporter (Pgp) is an active efflux pump for chemotherapeutic drugs, natural products and hydrophobic peptides. Pgp is envisaged as a 'hydrophobic vacuum cleaner', and drugs are believed to gain access to the substrate binding sites from within the membrane, rather than from the aqueous phase. The intimate association of both Pgp and its substrates with the membrane suggests that its function may be regulated by the biophysical properties of the lipid bilayer. Using the high affinity fluorescent substrate tetramethylrosamine (TMR), we have monitored, in real time, transport in proteoliposomes containing reconstituted Pgp. The TMR concentration gradient generated by Pgp was collapsed by the addition of either the ATPase inhibitor, vanadate, or Pgp modulators. TMR transport by Pgp obeyed Michaelis--Menten kinetics with respect to both of its substrates. The Km for ATP was 0.48 mM, close to the K(m) for ATP hydrolysis, and the K(m) for TMR was 0.3 microM. TMR transport was inhibited in a concentration-dependent fashion by verapamil and cyclosporin A, and activated (probably by a positive allosteric effect) by the transport substrate colchicine. TMR transport by Pgp reconstituted into proteoliposomes composed of two synthetic phosphatidylcholines showed a highly unusual biphasic temperature dependence. The rate of TMR transport was relatively high in the rigid gel phase, reached a maximum at the melting temperature of the bilayer, and then decreased in the fluid liquid crystalline phase. This pattern of temperature dependence suggests that the rate of drug transport by Pgp may be dominated by partitioning of drug into the bilayer.

The impact of furfural concentrations and substrate-to-biomass ratios on biological hydrogen production from synthetic lignocellulosic hydrolysate using mesophilic anaerobic digester sludge.

PubMed

Akobi, Chinaza; Hafez, Hisham; Nakhla, George

2016-12-01

This study evaluated the impact of furfural (a furan derivative) on hydrogen production rates and yields at initial substrate-to-microorganism ratios (S°/X°) of 4, 2, 1, and 0.5gCOD/gVSS and furfural concentrations of 4, 2, 1, and 0.5g/L. Fermentation studies were carried out in batches using synthetic lignocellulosic hydrolysate as substrate and mesophilic anaerobic digester sludge as seed. Contrary to other literature studies where furfural was inhibitory, this study showed that furfural concentrations of up to 1g/L enhanced hydrogen production with yields as high as 19% from the control (batch without furfural). Plots of hydrogen yields against gfurfural/gsugars and hydrogen yields versus gfurfural/gbiomass showed negative linear correlation indicating that these parameters influence biohydrogen production. Regression analysis indicated that gfurfural/gsugars initial exerted a greater effect on the degree of inhibition of hydrogen production than gfurfural/gVSS final . Copyright © 2016 Elsevier Ltd. All rights reserved.

Lightweight solar concentrator structures, phase 2

NASA Technical Reports Server (NTRS)

Williams, Brian E.; Kaplan, Richard B.

1993-01-01

This report summarizes the results of the program conducted by Ultramet under SBIR Phase 2 Contract NAS3-25418. The objective of this program was to develop lightweight materials and processes for advanced high accuracy Space Solar Concentrators using rigidized foam for the substrate structure with an integral optical surface.

A novel bifunctional Ni-doped TiO2 inverse opal with enhanced SERS performance and excellent photocatalytic activity

NASA Astrophysics Data System (ADS)

Li, Xuehong; Wu, Yun; Shen, Yuhua; Sun, Yan; Yang, Ying; Xie, Anjian

2018-01-01

Three-dimensional inverse opal photonic microarray (IOPM) structure exhibits good qualities in structural regularity and interconnectivity, such as high specific surface area, large pore volume, uniform pore size, and ordered periodic construction. Here, a novel nickel-doped titanium dioxide IOPM (Ni-TiO2 IOPM) was fabricated for the first time as a bifunctional material for the applications of surface-enhanced Raman scattering (SERS) substrate and photocatalyst. The Ni doping could change the defect concentration of the substrate to enhance the SERS effect, and could increase the light absorption of the substrate in visible region. The synergistic effect of Ni doping and the periodically ordered porous structure enhanced both SERS sensitivity and photocatalytic activity. As a SERS substrate, the Ni-TiO2 IOPM exhibited highly sensitive detection capability for 4-mercaptobenzoic acid (4-MBA) at a concentration as low as 1 × 10-11 M. Under simulated sunlight, about 95% of the methylene blue (MB) was degraded within 90 min when Ni-TiO2 IOPM was used as the photocatalytst. The Ni-TiO2 IOPM prepared in this work may be a promising bifunctional SERS substrate candidate for organic sewage detection and environment protection. In addition, the fabrication strategy can be extended to synthesize other nanomaterials with orderly and porous structure.

Production of a Pseudomonas lipase in n-alkane substrate and its isolation using an improved ammonium sulfate precipitation technique.

PubMed

Kanwar, Lambit; Gogoi, Binod Kumar; Goswami, Pranab

2002-09-01

Among the various lipidic and non-lipidic substances, normal alkanes within the chain lengths of C-12 to C-20 served as the best carbon substrates for the production of extracellular lipase by Pseudomonas species G6. Maximum lipase production of 25 U/ml of the culture broth was obtained by using n-hexadecane as the sole carbon substrate. The optimum pH of 8 and temperature of 34 + 1 degrees C were demonstrated for the production of lipase in n-hexadecane substrate. The optimum concentration of iron, which played a critical role on the lipase production, was found to be 0.25 mg/l. Lipase production could be enhanced to nearly 2.4-fold by using tributyrin at a concentration of 0.05% (v/v) in the culture medium. High recovery of the lipase protein (83%) from the culture broth was achieved by treating the culture supernatant with Silicone 21 Defoamer followed by ammonium sulfate (60% saturation) fractionation.

Potential use of the facultative halophyte Chenopodium quinoa Willd. as substrate for biogas production cultivated with different concentrations of sodium chloride under hydroponic conditions.

PubMed

Turcios, Ariel E; Weichgrebe, Dirk; Papenbrock, Jutta

2016-03-01

This project analyses the biogas potential of the halophyte Chenopodium quinoa Willd. In a first approach C. quinoa was grown with different concentrations of NaCl (0, 10 and 20 ppt NaCl) and the crop residues were used as substrate for biogas production. In a second approach, C. quinoa was grown with 0, 10, 20 and 30 ppt NaCl under hydroponic conditions and the fresh biomass was used as substrate. The more NaCl is in the culture medium, the higher the sodium, potassium, crude ash and hemicellulose content in the plant tissue whereas the calcium, sulfur, nitrogen and carbon content in the biomass decrease. According to this study, it is possible to produce high yields of methane using biomass of C. quinoa. The highest specific methane yields were obtained using the substrate from the plants cultivated at 10 and 20 ppt NaCl in both experiments. Copyright © 2015 Elsevier Ltd. All rights reserved.

Multiple binding modes of substrate to the catalytic RNA subunit of RNase P from Escherichia coli.

PubMed Central

Pomeranz Krummel, D A; Altman, S

1999-01-01

M1 RNA that contained 4'-thiouridine was photochemically cross-linked to different substrates and to a product of the reaction it governs. The locations of the cross-links in these photochemically induced complexes were identified. The cross-links indicated that different substrates share some contacts but have distinct binding modes to M1 RNA. The binding of some substrates also results in a substrate-dependent conformational change in the enzymatic RNA, as evidenced by the appearance of an M1 RNA intramolecular cross-link. The identification of the cross-links between M1 RNA and product indicate that they are shared with only one of the three cross-linked E-S complexes that were identified, an indication of noncompetitive inhibition by the product. We also examined whether the cross-linked complexes between M1 RNA and substrate(s) or product are altered in the presence of the enzyme's protein cofactor (C5 protein) and in the presence of different concentrations of divalent metal ions. C5 protein enhanced the yield of certain M1 RNA-substrate cross-linked complexes for both wild-type M1 RNA and a deletion mutant of M1 RNA (delta[273-281]), but not for the M1 RNA-product complex. High concentrations of Mg2+ increased the yield of all M1 RNA-substrate complexes but not the M1 RNA-product complex. PMID:10445877

Tribology of bio-inspired nanowrinkled films on ultrasoft substrates.

PubMed

Lackner, Juergen M; Waldhauser, Wolfgang; Major, Lukasz; Teichert, Christian; Hartmann, Paul

2013-01-01

Biomimetic design of new materials uses nature as antetype, learning from billions of years of evolution. This work emphasizes the mechanical and tribological properties of skin, combining both hardness and wear resistance of its surface (the stratum corneum) with high elasticity of the bulk (epidermis, dermis, hypodermis). The key for combination of such opposite properties is wrinkling, being consequence of intrinsic stresses in the bulk (soft tissue): Tribological contact to counterparts below the stress threshold for tissue trauma occurs on the thick hard stratum corneum layer pads, while tensile loads smooth out wrinkles in between these pads. Similar mechanism offers high tribological resistance to hard films on soft, flexible polymers, which is shown for diamond-like carbon (DLC) and titanium nitride thin films on ultrasoft polyurethane and harder polycarbonate substrates. The choice of these two compared substrate materials will show that ultra-soft substrate materials are decisive for the distinct tribological material. Hierarchical wrinkled structures of films on these substrates are due to high intrinsic compressive stress, which evolves during high energetic film growth. Incremental relaxation of these stresses occurs by compound deformation of film and elastic substrate surface, appearing in hierarchical nano-wrinkles. Nano-wrinkled topographies enable high elastic deformability of thin hard films, while overstressing results in zigzag film fracture along larger hierarchical wrinkle structures. Tribologically, these fracture mechanisms are highly important for ploughing and sliding of sharp and flat counterparts on hard-coated ultra-soft substrates like polyurethane. Concentration of polyurethane deformation under the applied normal loads occurs below these zigzag cracks. Unloading closes these cracks again. Even cyclic testing do not lead to film delamination and retain low friction behavior, if the adhesion to the substrate is high and the initial friction coefficient of the film against the sliding counterpart low, e.g. found for DLC.

Tribology of bio-inspired nanowrinkled films on ultrasoft substrates

PubMed Central

Lackner, Juergen M.; Waldhauser, Wolfgang; Major, Lukasz; Teichert, Christian; Hartmann, Paul

2013-01-01

Biomimetic design of new materials uses nature as antetype, learning from billions of years of evolution. This work emphasizes the mechanical and tribological properties of skin, combining both hardness and wear resistance of its surface (the stratum corneum) with high elasticity of the bulk (epidermis, dermis, hypodermis). The key for combination of such opposite properties is wrinkling, being consequence of intrinsic stresses in the bulk (soft tissue): Tribological contact to counterparts below the stress threshold for tissue trauma occurs on the thick hard stratum corneum layer pads, while tensile loads smooth out wrinkles in between these pads. Similar mechanism offers high tribological resistance to hard films on soft, flexible polymers, which is shown for diamond-like carbon (DLC) and titanium nitride thin films on ultrasoft polyurethane and harder polycarbonate substrates. The choice of these two compared substrate materials will show that ultra-soft substrate materials are decisive for the distinct tribological material. Hierarchical wrinkled structures of films on these substrates are due to high intrinsic compressive stress, which evolves during high energetic film growth. Incremental relaxation of these stresses occurs by compound deformation of film and elastic substrate surface, appearing in hierarchical nano-wrinkles. Nano-wrinkled topographies enable high elastic deformability of thin hard films, while overstressing results in zigzag film fracture along larger hierarchical wrinkle structures. Tribologically, these fracture mechanisms are highly important for ploughing and sliding of sharp and flat counterparts on hard-coated ultra-soft substrates like polyurethane. Concentration of polyurethane deformation under the applied normal loads occurs below these zigzag cracks. Unloading closes these cracks again. Even cyclic testing do not lead to film delamination and retain low friction behavior, if the adhesion to the substrate is high and the initial friction coefficient of the film against the sliding counterpart low, e.g. found for DLC. PMID:24688710

Development of a high-throughput liquid state assay for lipase activity using natural substrates and rhodamine B.

PubMed

Zottig, Ximena; Meddeb-Mouelhi, Fatma; Beauregard, Marc

2016-03-01

A fluorescence-based assay for the determination of lipase activity using rhodamine B as an indicator, and natural substrates such as olive oil, is described. It is based on the use of a rhodamine B-natural substrate emulsion in liquid state, which is advantageous over agar plate assays. This high-throughput method is simple and rapid and can be automated, making it suitable for screening and metagenomics application. Reaction conditions such as pH and temperature can be varied and controlled. Using triolein or olive oil as a natural substrate allows monitoring of lipase activity in reaction conditions that are closer to those used in industrial settings. The described method is sensitive over a wide range of product concentrations and offers good reproducibility. Copyright © 2015 Elsevier Inc. All rights reserved.

Mechanisms of Enhanced Catalysis in Enzyme-DNA Nanostructures Revealed through Molecular Simulations and Experimental Analysis.

PubMed

Gao, Yingning; Roberts, Christopher C; Toop, Aaron; Chang, Chia-En A; Wheeldon, Ian

2016-08-03

Understanding and controlling the molecular interactions between enzyme substrates and DNA nanostructures has important implications in the advancement of enzyme-DNA technologies as solutions in biocatalysis. Such hybrid nanostructures can be used to create enzyme systems with enhanced catalysis by controlling the local chemical and physical environments and the spatial organization of enzymes. Here we have used molecular simulations with corresponding experiments to describe a mechanism of enhanced catalysis due to locally increased substrate concentrations. With a series of DNA nanostructures conjugated to horseradish peroxidase, we show that binding interactions between substrates and the DNA structures can increase local substrate concentrations. Increased local substrate concentrations in HRP(DNA) nanostructures resulted in 2.9- and 2.4-fold decreases in the apparent Michaelis constants of tetramethylbenzidine and 4-aminophenol, substrates of HRP with tunable binding interactions to DNA nanostructures with dissociation constants in the micromolar range. Molecular simulations and kinetic analysis also revealed that increased local substrate concentrations enhanced the rates of substrate association. Identification of the mechanism of increased local concentration of substrates in close proximity to enzymes and their active sites adds to our understanding of nanostructured biocatalysis from which we can develop guidelines for enhancing catalysis in rationally designed systems. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Role of multiple substrates (spent mushroom compost, ochre, steel slag, and limestone) in passive remediation of metal-containing acid mine drainage.

PubMed

Molahid, Verma Loretta M; Mohd Kusin, Faradiella; Madzin, Zafira

2018-01-12

The potential of selected materials in treating metal-rich acid mine drainage (AMD) has been investigated in a series of batch experiment. The efficiencies of both single and mixed substrates under two conditions i.e. low- and high-concentration solutions containing heavy metals were evaluated. Synthetic metal-containing AMD was used in the experiments treated using spent mushroom compost (SMC), ochre, steel slag (SS), and limestone. Different ratios of treatment materials were incorporated in the substrate mix and were tested in an anoxic condition. In the batch test, physicochemical parameters (pH, redox potential, total dissolved solids, conductivity, and Ca concentration) and heavy metals (Fe, Mn, Pb, Zn, and Al) were analysed. The mixed substrates have shown satisfactory performance in increasing pH with increasing Ca concentration and removing metals. It has been found that SS and ochre played an important role in the treatment of AMD. The results showed that the mixed substrates SM1 (i.e. 10% SMC mixed with 20% ochre, 30% steel slag, and 40% limestone) and SM2 (i.e. 20% SMC mixed with 30% ochre, 40% steel slag, and 10% limestone) were effective in increasing the pH from as low as 3.5-8.09, and removing heavy metals with more than 90% removal efficiencies.

Effect of the dilution rate on microbial competition: r-strategist can win over k-strategist at low substrate concentration.

PubMed

Winkler, Mari-K H; Boets, Pieter; Hahne, Birk; Goethals, Peter; Volcke, Eveline I P

2017-01-01

The conditions present in both in vitro and in vivo ecosystems determine the microbial population harbouring it. One commonly accepted theory is that a species with a high substrate affinity and low growth rate (k-strategist) will win the competition against a second species with a lower substrate affinity and higher growth rate (r-strategist) if both species are subjected to low substrate concentrations. In this study two nitrite oxidizing bacteria (NOB), Nitrospira defluvii (k-strategist) and Nitrobacter vulgaris (r-strategist), were cultivated in a continuous reactor systems. The minimal hydraulic retention time (HRT) required for maintaining the slower growing Nitrospira was first determined. A reactor containing Nitrobacter was set to the same HRT and Nitrospira was injected to evaluate the effect of the dilution rate on the competition between both species. By following the microbial population dynamics with qPCR analysis, it was shown that not only the substrate affinity drives the competition between k- and r-strategists but also the dilution rate. Experimental data and numerical simulations both revealed that the washout of Nitrobacter was significantly delayed at dilution rates close to the μmax of Nitrospira. The competition could be even reverted towards Nitrobacter (r-strategist) despite of low nitrite concentrations and dilution rates lower than the μmax of Nitrospira.

Impact of structure and morphology of nanostructured ceria coating on AISI 304 oxidation kinetics

NASA Astrophysics Data System (ADS)

Aadhavan, R.; Suresh Babu, K.

2017-07-01

Nanostructured ceria-based coatings are shown to be protective against high-temperature oxidation of AISI 304 due to the dynamics of oxidation state and associated defects. However, the processing parameters of deposition have a strong influence in determining the structural and morphological aspects of ceria. The present work focuses on the effect of variation in substrate temperature (50-300 °C) and deposition rate (0.1-50 Å/s) of ceria in electron beam physical vapour evaporation method and correlates the changes in structure and morphology to high-temperature oxidation protection. Unlike deposition rate, substrate temperature exhibited a profound influence on crystallite size (7-18 nm) and oxygen vacancy concentration. Upon isothermal oxidation at 1243 K for 24 h, bare AISI 304 exhibited a linear mass gain with a rate constant of 3.0 ± 0.03 × 10-3 kg2 m-4 s-1 while ceria coating lowered the kinetics by 3-4 orders. Though the thickness of the coating was kept constant at 2 μm, higher deposition rate offered one order lower protection due to the porous nature of the coating. Variation in the substrate temperature modulated the porosity as well as oxygen vacancy concentration and displayed the best protection for coatings deposited at moderate substrate temperature. The present work demonstrates the significance of selecting appropriate processing parameters to obtain the required morphology for efficient high-temperature oxidation protection.

Influence of drainage and nutrient-solution nitrogen and potassium concentrations on the agronomic behavior of bell-pepper plants cultivated in a substrate.

PubMed

Wamser, Anderson Fernando; Cecilio Filho, Arthur Bernardes; Nowaki, Rodrigo Hiyoshi Dalmazzo; Mendoza-Cortez, Juan Waldir; Urrestarazu, Miguel

2017-01-01

The interactive effects of N (6, 9, 12 and 15 mmol L-1) and K (3, 5, 7, and 9 mmol L-1) concentrations in nutrient solutions were evaluated on bell pepper grown in a coconut-coir substrate and fertilized without drainage. An additional treatment with drainage was evaluated using N and K concentrations of 12 and 7 mmol L-1, respectively. The hybrid Eppo cultivar of yellow bell pepper was cultivated for 252 days beginning 9 November 2012. Electrical conductivity (EC), the N and K concentrations in the substrate solution, marketable fruit yield, total dry weight and macronutrient concentrations in shoots were periodically evaluated. Fruit production was lower in the system without drainage, regardless of the N and K concentrations, compared to the recommended 10-20% drainage of the volume of nutrient solution applied. Higher K concentrations in the nutrient solution did not affect plant production in the system without drainage for the substrate with an initial K concentration of 331.3 mg L-1. Fruit yield was higher without drainage at a nutrient-solution N concentration of 10.7 mmol L-1. The upper EC limit of the substrate solution in the system without drainage was exceeded 181 days after planting. Either lower nutrient concentrations in the nutrient solution or a drainage system could thus control the EC in the substrate solution.

Polyhydroxyalkanoate production as a side stream process on a municipal waste water treatment plant.

PubMed

Pittmann, T; Steinmetz, H

2014-09-01

This work describes the production of polyhydroxyalkanoates (PHAs) as a side stream process on a municipal waste water treatment plant (WWTP) at different operation conditions. Therefore various tests were conducted regarding a high PHA production and stable PHA composition. Influence of substrate concentration, temperature, pH and cycle time of an installed feast/famine-regime were investigated. The results demonstrated a strong influence of the operating conditions on the PHA production. Lower substrate concentration, 20°C, neutral pH-value and a 24h cycle time are preferable for high PHA production up to 28.4% of cell dry weight (CDW). PHA composition was influenced by cycle time only and a stable PHA composition was reached. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effect of pH and nitrite concentration on nitrite oxidation rate.

PubMed

Jiménez, E; Giménez, J B; Ruano, M V; Ferrer, J; Serralta, J

2011-10-01

The effect of pH and nitrite concentration on the activity of the nitrite oxidizing bacteria (NOB) in an activated sludge reactor has been determined by means of laboratory batch experiments based on respirometric techniques. The bacterial activity was measured at different pH and at different total nitrite concentrations (TNO₂). The experimental results showed that the nitrite oxidation rate (NOR) depends on the TNO₂ concentration independently of the free nitrous acid (FNA) concentration, so FNA cannot be considered as the real substrate for NOB. NOB were strongly affected by low pH values (no activity was detected at pH 6.5) but no inhibition was observed at high pH values (activity was nearly the same for the pH range 7.5-9.95). A kinetic expression for nitrite oxidation process including switch functions to model the effect of TNO₂ concentration and pH inhibition is proposed. Substrate half saturation constant and pH inhibition constants have been obtained. Copyright © 2011 Elsevier Ltd. All rights reserved.

Periodic silver nanocluster arrays over large-area silica nanosphere template as highly sensitive SERS substrate

NASA Astrophysics Data System (ADS)

Hou, Xu; Wang, Qi; Mao, Guoming; Liu, Hao; Yu, Rongdi; Ren, Xiaomin

2018-04-01

Periodic Ag nanocluster arrays for surface enhanced Raman spectroscopy (SERS) were fabricated through magnetron sputtering Ag over a large-area monolayer template which is based on silica (SiO2) nanospheres. High-density nanogaps between the adjacent Ag nanoclusters acted as "hot-spots", making a dominant contribution to the high-performance SERS detection. Moreover, the nanospheres and Ag nanoclusters effectively increased the surface roughness and also enlarged the surface area of as-obtained SERS substrate, which resulted in a further enhancement in Raman signals. As-prepared SERS substrates showed very high sensitivity with the enhancement factor (EF) value of 4.1 × 1012 for Rhodamine 6G (R6G), allowing the corresponding detection limit as low as 10-16 M. Additionally, SERS signal of melamine was still strong even though its concentration was lowered to 10-7 M. Our results show that preparing highly sensitive SERS substrate with periodic Ag nanoclusters over SiO2 nanosphere template is a convenient and promising pathway for chemical and biologic sensing.

Transparent anodic TiO2 nanotube arrays on plastic substrates for disposable biosensors and flexible electronics.

PubMed

Farsinezhad, Samira; Mohammadpour, Arash; Dalrymple, Ashley N; Geisinger, Jared; Kar, Piyush; Brett, Michael J; Shankar, Karthik

2013-04-01

Exploitation of anodically formed self-organized TiO2 nanotube arrays in mass-manufactured, disposable biosensors, rollable electrochromic displays and flexible large-area solar cells would greatly benefit from integration with transparent and flexible polymeric substrates. Such integration requires the vacuum deposition of a thin film of titanium on the desired substrate, which is then anodized in suitable media to generate TiO2 nanotube arrays. However the challenges associated with control of Ti film morphology, nanotube array synthesis conditions, and film adhesion and transparency, have necessitated the use of substrate heating during deposition to temperatures of at least 300 degrees C and as high as 500 degrees C to generate highly ordered open-pore nanotube arrays, thus preventing the use of polymeric substrates. We report on a film growth technique that exploits atomic peening to achieve high quality transparent TiO2 nanotube arrays with lengths up to 5.1 microm at room temperature on polyimide substrates without the need for substrate heating or substrate biasing or a Kauffman ion source. The superior optical quality and uniformity of the nanotube arrays was evidenced by the high specular reflectivity and the smooth pattern of periodic interferometric fringes in the transmission spectra of the nanotube arrays, from which the wavelength-dependent effective refractive index was extracted for the air-TiO2 composite medium. A fluorescent immunoassay biosensor constructed using 5.1 microm-long transparent titania nanotube arrays (TTNAs) grown on Kapton substrates detected human cardiac troponin I at a concentration of 0.1 microg ml(-1).

Enhanced bioethanol production by fed-batch simultaneous saccharification and co-fermentation at high solid loading of Fenton reaction and sodium hydroxide sequentially pretreated sugarcane bagasse.

PubMed

Zhang, Teng; Zhu, Ming-Jun

2017-04-01

A study on the fed-batch simultaneous saccharification and co-fermentation (SSCF) of Fenton reaction combined with NaOH pretreated sugarcane bagasse (SCB) at a high solid loading of 10-30% (w/v) was investigated. Enzyme feeding mode, substrate feeding mode and combination of both were compared with the batch mode under respective solid loadings. Ethanol concentrations of above 80g/L were obtained in batch and enzyme feeding modes at a solid loading of 30% (w/v). Enzyme feeding mode was found to increase ethanol productivity and reduce enzyme loading to a value of 1.23g/L/h and 9FPU/g substrate, respectively. The present study provides an economically feasible process for high concentration bioethanol production. Copyright © 2017 Elsevier Ltd. All rights reserved.

Indole-3-acetic acid biosynthetic pathway and aromatic amino acid aminotransferase activities in Pantoea dispersa strain GPK.

PubMed

Kulkarni, G B; Nayak, A S; Sajjan, S S; Oblesha, A; Karegoudar, T B

2013-05-01

This investigation deals with the production of IAA by a bacterial isolate Pantoea dispersa strain GPK (PDG) identified by 16S rRNA gene sequence analysis. HPLC and Mass spectral analysis of metabolites from bacterial spent medium revealed that, IAA production by PDG is Trp-dependent and follows indole-3-pyruvic acid (IPyA) pathway. Substrate specificity study of aromatic amino acid aminotransferase (AAT) showed high activities, only when tryptophan (Trp) and α-ketoglutarate (α-kg) were used as substrates. AAT is highly specific for Trp and α-kg as amino group donor and acceptor, respectively. The effect of exogenous IAA on bacterial growth was established. Low concentration of exogenous IAA induced the growth, whereas high concentration decreased the growth of bacterium. PDG treatment significantly increased the root length, shoot length and dry mass of the chickpea and pigeon pea plants. © 2013 The Society for Applied Microbiology.

Continuous ethanol production from cheese whey fermentation by Candida pseudotropicalis

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

Ghaly, A.E.; El-Taweel, A.A.

1997-12-01

Three pilot-scale continuous mix reactors of 5-L volume each were used to study the effects of retention time (18--42 hours) and initial substrate concentration (50--150 g/L) on the cell yield, lactose consumption, and maximum ethanol concentration during continuous fermentation of cheese whey using the yeast Candida pseudotropicalis. A microaeration rate of 480 mL/min and a nutrient supplement (yeast extract) concentration of 0.1% vol/vol were used. The results indicated that the dissolved oxygen concentration, temperature, cell concentration, lactose utilization rate, and ethanol concentration were affected by hydraulic retention time and initial substrate concentration. The highest cell concentration of 5.46 g/L andmore » the highest ethanol concentration of 57.96 g/L (with a maximum ethanol yield of 99.6% from the theoretical yield) were achieved at the 42-hour hydraulic retention time and the 150 g/L initial substrate concentration, whereas the highest cell yield was observed at the 50 g/L initial substrate concentration and the 36-hour hydraulic retention time. Lactose utilizations of 98, 91, and 83% were obtained with 50, 100, and 150 g/L initial substrate concentrations at the 42-hour hydraulic retention time. A pH control system was found unnecessary.« less

Aerobic digestion of starch wastewater in a fluidized bed bioreactor with low density biomass support.

PubMed

Rajasimman, M; Karthikeyan, C

2007-05-08

A solid-liquid-gas, multiphase, fluidized bed bioreactor with low density particles was used in this study to treat the high organic content starch industry wastewater. The characteristics of starch wastewater were studied. It shows high organic content and acidic nature. The performance of a three phase fluidized bed bioreactor with low density biomass support was studied under various average initial substrate concentrations, by varying COD values (2250, 4475, 6730 and 8910 mg/L) and for various hydraulic retention times (8, 16, 24, 32 and 40 h) based on COD removal efficiency. The optimum bed height for the maximum COD reduction was found to be 80 cm. Experiments were carried out in the bioreactor at an optimized bed height, after the formation of biofilm on the surface of low-density particles (density=870 kg/m(3)). Mixed culture obtained from the sludge, taken from starch industry effluent treatment plant, was used as the source for microorganisms. From the results it was observed that increase in initial substrate concentration leads to decrease in COD reduction and COD reduction increases with increase in hydraulic retention time. The optimum COD removal of 93.8% occurs at an initial substrate concentration of 2250 mg/L and for the hydraulic retention time of 24h.

Chelatable trace zinc causes low, irreproducible KDAC8 activity.

PubMed

Toro, Tasha B; Edenfield, Samantha A; Hylton, Brandon J; Watt, Terry J

2018-01-01

Acetylation is an important regulatory mechanism in cells, and emphasis is being placed on identifying substrates and small molecule modulators of this post-translational modification. However, the reported in vitro activity of the lysine deacetylase KDAC8 is inconsistent across experimental setups, even with the same substrate, complicating progress in the field. We detected trace levels of zinc, a known inhibitor of KDAC8 when present in excess, even in high-quality buffer reagents, at concentrations that are sufficient to significantly inhibit the enzyme under common reaction conditions. We hypothesized that trace zinc in solution could account for the observed variability in KDAC8 activity. We demonstrate that addition of chelators, including BSA, EDTA, and citrate, and/or the use of a phosphate-based buffer instead of the more common tris-based buffer, eliminates the inhibition from low levels of zinc as well as the dependence of specific activity on enzyme concentration. This results in high KDAC8 activity that is consistent across buffer systems, even using low concentrations of enzyme. We report conditions that are suitable for several assays to increase both enzyme activity and reproducibility. Our results have significant implications for approaches used to identify substrates and small molecule modulators of KDAC8 and interpretation of existing data. Copyright © 2017 Elsevier Inc. All rights reserved.

Success of chemolithoautotrophic SUP05 and Sulfurimonas GD17 cells in pelagic Baltic Sea redox zones is facilitated by their lifestyles as K- and r-strategists.

PubMed

Rogge, Andreas; Vogts, Angela; Voss, Maren; Jürgens, Klaus; Jost, Günter; Labrenz, Matthias

2017-06-01

Chemolithoautotrophic sulfur-oxidizing and denitrifying Gamma- (particularly the SUP05 cluster) and Epsilonproteobacteria (predominantly Sulfurimonas subgroup GD17) are assumed to compete for substrates (electron donors and acceptors) in marine pelagic redox gradients. To elucidate their ecological niche separation we performed 34 S 0 , 15 NO3- and H 13 CO3- stable-isotope incubations with water samples from Baltic Sea suboxic, chemocline and sulfidic zones followed by combined phylogenetic staining and high-resolution secondary ion mass spectrometry of single cells. SUP05 cells were small-sized (0.06-0.09 µm 3 ) and most abundant in low-sulfidic to suboxic zones, whereas Sulfurimonas GD17 cells were significantly larger (0.26-0.61 µm 3 ) and most abundant at the chemocline and below. Together, SUP05 and GD17 cells accumulated up to 48% of the labelled substrates but calculation of cell volume-specific rates revealed that GD17 cells incorporated labelled substrates significantly faster throughout the redox zone, thereby potentially outcompeting SUP05 especially at high substrate concentrations. Thus, in synopsis with earlier described features of SUP05/GD17 we conclude that their spatially overlapping association in stratified sulfidic zones is facilitated by their different lifestyles: whereas SUP05 cells are streamlined, non-motile K-strategists adapted to low substrate concentrations, GD17 cells are motile r-strategists well adapted to fluctuating substrate and redox conditions. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

Fabrication of novel plasmonics-active substrates

NASA Astrophysics Data System (ADS)

Dhawan, Anuj; Gerhold, Michael; Du, Yan; Misra, Veena; Vo-Dinh, Tuan

2009-02-01

This paper describes methodologies for fabricating of highly efficient plasmonics-active SERS substrates - having metallic nanowire structures with pointed geometries and sub-5 nm gap between the metallic nanowires enabling concentration of high EM fields in these regions - on a wafer-scale by a reproducible process that is compatible with large-scale development of these substrates. Excitation of surface plasmons in these nanowire structures leads to substantial enhancement in the Raman scattering signal obtained from molecules lying in the vicinity of the nanostructure surface. The methodologies employed included metallic coating of silicon nanowires fabricated by employing deep UV lithography as well as controlled growth of silicon germanium on silicon nanostructures to form diamond-shaped nanowire structures followed by metallic coating. These SERS substrates were employed for detecting chemical and biological molecules of interest. In order to characterize the SERS substrates developed in this work, we obtained SERS signals from molecules such as p-mercaptobenzoic acid (pMBA) and cresyl fast violet (CFV) attached to or adsorbed on the metal-coated SERS substrates. It was observed that both gold-coated triangular shaped nanowire substrates as well as gold-coated diamond shaped nanowire substrates provided very high SERS signals for the nanowires having sub-15 nm gaps and that the SERS signal depends on the closest spacing between the metal-coated silicon and silicon germanium nanowires. SERS substrates developed by the different processes were also employed for detection of biological molecules such as DPA (Dipicolinic Acid), an excellent marker for spores of bacteria such as Anthrax.

Techno-economic analysis of three different substrate removal and reuse strategies for III-V solar cells: Techno-economic analysis for III-V solar cells

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

Ward, J. Scott; Remo, Timothy; Horowitz, Kelsey

The high cost of wafers suitable for epitaxial deposition of III-V solar cells has been a primary barrier to widespread use of these cells in low-concentration and one-sun terrestrial solar applications. A possible solution is to reuse the substrate many times, thus spreading its cost across many cells. We performed a bottom-up techno-economic analysis of three different strategies for substrate reuse in high-volume manufacturing: epitaxial lift-off, spalling, and the use of a porous germanium release layer. The analysis shows that the potential cost reduction resulting from substrate reuse is limited in all three strategies--not by the number of reuse cyclesmore » achievable, but by the costs that are incurred in each cycle to prepare the substrate for another epitaxial deposition. The dominant substrate-preparation cost component is different for each of the three strategies, and the cost-ranking of these strategies is subject to change if future developments substantially reduce the cost of epitaxial deposition.« less

Self-assembled nanospheres with multiple endohedral binding sites pre-organize catalysts and substrates for highly efficient reactions

NASA Astrophysics Data System (ADS)

Wang, Qi-Qiang; Gonell, Sergio; Leenders, Stefan H. A. M.; Dürr, Maximilian; Ivanović-Burmazović, Ivana; Reek, Joost N. H.

2016-03-01

Tuning reagent and catalyst concentrations is crucial in the development of efficient catalytic transformations. In enzyme-catalysed reactions the substrate is bound—often by multiple non-covalent interactions—in a well-defined pocket close to the active site of the enzyme; this pre-organization facilitates highly efficient transformations. Here we report an artificial system that co-encapsulates multiple catalysts and substrates within the confined space defined by an M12L24 nanosphere that contains 24 endohedral guanidinium-binding sites. Cooperative binding means that sulfonate guests are bound much more strongly than carboxylates. This difference has been used to fix gold-based catalysts firmly, with the remaining binding sites left to pre-organize substrates. This strategy was applied to a Au(I)-catalysed cyclization of acetylenic acid to enol lactone in which the pre-organization resulted in much higher reaction rates. We also found that the encapsulated sulfonate-containing Au(I) catalysts did not convert neutral (acid) substrates, and so could have potential in the development of substrate-selective catalysis and base-triggered on/off switching of catalysis.

Swelling and Contraction of Corn Mitochondria 1

PubMed Central

Stoner, C. D.; Hanson, J. B.

1966-01-01

A survey has been made of the properties of corn mitochondria in swelling and contraction. The mitochondria swell spontaneously in KCl but not in sucrose. Aged mitochondria will swell rapidly in sucrose if treated with citrate or EDTA. Swelling does not impair oxidative phosphorylation if bovine serum albumin is present. Contraction can be maintained or initiated with ATP + Mg or an oxidizable substrate, contraction being more rapid with the substrate. Magnesium is not required for substrate powered contraction. Contraction powered by ATP is accompanied by the release of phosphate. Oligomycin inhibits both ATP-powered contraction and the release of phosphate. However, it does not affect substrate-powered contraction. Substrate powered contraction is inhibited by electron-transport inhibitors. The uncoupler, carbonyl cyanide m-chlorophenyl hydrazone, accelerates swelling and inhibits both ATP-and substrate-powered contraction. However, the concentrations required are well in excess of those required to produce uncoupling and to accelerate adenosine triphosphatase; the concentrations required inhibit respiration in a phosphorylating medium. Phosphate is a very effective inhibitor of succinate-powered contraction. Neither oligomycin nor Mg affects the phosphate inhibition. Phosphate is less inhibitory with the ATP-powered contraction. The results are discussed in terms of a hypothesis that contraction is associated with a nonphosphorylated high energy intermediate of oxidative phosphorylation. Images PMID:16656248

Substrate inhibition kinetics of phenol biodegradation

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

Goudar, C.T.; Ganji, S.H.; Pujar, B.G.

Phenol biodegradation was studied in batch experiments using an acclimated inoculum and initial phenol concentrations ranging from 0.1 to 1.3 g/L. Phenol depletion an associated microbial growth were monitored over time to provide information that was used to estimate the kinetics of phenol biodegradation. Phenol inhibited biodegradation at high concentrations, and a generalized substrate inhibition model based on statistical thermodynamics was used to describe the dynamics of microbial growth in phenol. For experimental data obtained in this study, the generalized substrate inhibition model reduced to a form that is analogous to the Andrews equation, and the biokinetic parameters {micro}{sub max},more » maximum specific growth; K{sub s}, saturation constant; and K{sub i}, inhibition constant were estimated as 0.251 h{sup {minus}1}, 0.011 g/L, and 0.348 g/L, respectively, using a nonlinear least squares technique. Given the wide variability in substrate inhibition models used to describe phenol biodegradation, an attempt was made to justify selection of particular model based on theoretical considerations. Phenol biodegradation data from nine previously published studies were used in the generalized substrate inhibition model to determine the appropriate form of the substrate inhibition model. In all nine cases, the generalized substrate inhibition model reduced to a form analogous to the Andrews equation suggesting the suitability of the Andrews equation to describe phenol biodegradation data.« less

Process Optimization on Micro-Aeration Supply for High Production Yield of 2,3-Butanediol from Maltodextrin by Metabolically-Engineered Klebsiella oxytoca

PubMed Central

Jantama, Sirima Suvarnakuta; Kanchanatawee, Sunthorn

2016-01-01

An optimization process with a cheap and abundant substrate is considered one of the factors affecting the price of the production of economical 2,3-Butanediol (2,3-BD). A combination of the conventional method and response surface methodology (RSM) was applied in this study. The optimized levels of pH, aeration rate, agitation speed, and substrate concentration (maltodextrin) were investigated to determine the cost-effectiveness of fermentative 2,3-BD production by metabolically-engineered Klebsiella oxytoca KMS005. Results revealed that pH, aeration rate, agitation speed, and maltodextrin concentration at levels of 6.0, 0.8 vvm, 400 rpm, and 150 g/L respectively were the optimal conditions. RSM also indicated that the agitation speed was the most influential parameter when either agitation and aeration interaction or agitation and substrate concentration interaction played important roles for 2,3-BD production by the strain from maltodextrin. Under interim fed-batch fermentation, 2,3-BD concentration, yield, and productivity were obtained at 88.1±0.2 g/L, 0.412±0.001 g/g, and 1.13±0.01 g/L/h respectively within 78 h. PMID:27603922

Buffer Layer Doping Concentration Measurement Using VT-VSUB Characteristics of GaN HEMT with p-GaN Substrate Layer

NASA Astrophysics Data System (ADS)

Hu, Cheng-Yu; Nakatani, Katsutoshi; Kawai, Hiroji; Ao, Jin-Ping; Ohno, Yasuo

To improve the high voltage performance of AlGaN/GaN heterojunction field effect transistors (HFETs), we have fabricated AlGaN/GaN HFETs with p-GaN epi-layer on sapphire substrate with an ohmic contact to the p-GaN (p-sub HFET). Substrate bias dependent threshold voltage variation (VT-VSUB) was used to directly determine the doping concentration profile in the buffer layer. This VT-VSUB method was developed from Si MOSFET. For HFETs, the insulator is formed by epitaxially grown and heterogeneous semiconductor layer while for Si MOSFETs the insulator is amorphous SiO2. Except that HFETs have higher channel mobility due to the epitaxial insulator/semiconductor interface, HFETs and Si MOSFETs are basically the same in the respect of device physics. Based on these considerations, the feasibility of this VT-VSUB method for AlGaN/GaN HFETs was discussed. In the end, the buffer layer doping concentration was measured to be 2 × 1017cm-3, p-type, which is well consistent with the Mg concentration obtained from secondary ion mass spectroscopy (SIMS) measurement.

Highly selective anti-Prelog synthesis of optically active aryl alcohols by recombinant Escherichia coli expressing stereospecific alcohol dehydrogenase.

PubMed

Li, Ming; Nie, Yao; Mu, Xiao Qing; Zhang, Rongzhen; Xu, Yan

2016-07-03

Biocatalytic asymmetric synthesis has been widely used for preparation of optically active chiral alcohols as the important intermediates and precursors of active pharmaceutical ingredients. However, the available whole-cell system involving anti-Prelog specific alcohol dehydrogenase is yet limited. A recombinant Escherichia coli system expressing anti-Prelog stereospecific alcohol dehydrogenase from Candida parapsilosis was established as a whole-cell system for catalyzing asymmetric reduction of aryl ketones to anti-Prelog configured alcohols. Using 2-hydroxyacetophenone as the substrate, reaction factors including pH, cell status, and substrate concentration had obvious impacts on the outcome of whole-cell biocatalysis, and xylose was found to be an available auxiliary substrate for intracellular cofactor regeneration, by which (S)-1-phenyl-1,2-ethanediol was achieved with an optical purity of 97%e.e. and yield of 89% under the substrate concentration of 5 g/L. Additionally, the feasibility of the recombinant cells toward different aryl ketones was investigated, and most of the corresponding chiral alcohol products were obtained with an optical purity over 95%e.e. Therefore, the whole-cell system involving recombinant stereospecific alcohol dehydrogenase was constructed as an efficient biocatalyst for highly enantioselective anti-Prelog synthesis of optically active aryl alcohols and would be promising in the pharmaceutical industry.

High-Sensitivity Surface-Enhanced Raman Scattering (SERS) Substrate Based on a Gold Colloid Solution with a pH Change for Detection of Trace-Level Polycyclic Aromatic Hydrocarbons in Aqueous Solution.

PubMed

Shi, Xiaofeng; Liu, Shu; Han, Xiaohong; Ma, Jun; Jiang, Yongchao; Yu, Guifeng

2015-05-01

In this study, a gold colloid solution whose parameters were optimized, and without any surfactants, was developed as a surface-enhanced Raman scattering (SERS) substrate for the detection of trace-level polycyclic aromatic hydrocarbons (PAHs). A gold colloid solution with 57 nm gold particles and pH 13 was prepared to be the SERS substrate. It had impressive enhancement that was two orders of magnitude higher than that of a gold colloid solution with 57 nm gold particles and without pH change (pH 6). Even with a compact field-based Raman spectrometer, naphthalene, phenanthrene, anthracene, fluoranthene, and pyrene were detected, with limits of detection at 6.8 nM, 3.4 nM, 1.8 nM, 0.68 nM (680 pM), and 0.44 nM (440 pM), respectively. The significant enhancement was ascribed to an electromagnetic mechanism and a charge-transfer mechanism. Quantitative analyses for these five PAHs in water were also performed. The SERS intensities of PAHs were found to have good linear dependence relations with the concentrations in low concentration. This high-sensitivity, easily prepared substrate offers a promising technology for the quantitative detection of trace-level PAHs.

The Inhibitory Effect of Non-Substrate and Substrate DNA on the Ligation and Self-Adenylylation Reactions Catalyzed by T4 DNA Ligase

PubMed Central

Bauer, Robert J.; Evans, Thomas C.; Lohman, Gregory J. S.

2016-01-01

DNA ligases are essential both to in vivo replication, repair and recombination processes, and in vitro molecular biology protocols. Prior characterization of DNA ligases through gel shift assays has shown the presence of a nick site to be essential for tight binding between the enzyme and its dsDNA substrate, with no interaction evident on dsDNA lacking a nick. In the current study, we observed a significant substrate inhibition effect, as well as the inhibition of both the self-adenylylation and nick-sealing steps of T4 DNA ligase by non-nicked, non-substrate dsDNA. Inhibition by non-substrate DNA was dependent only on the total DNA concentration rather than the structure; with 1 μg/mL of 40-mers, 75-mers, or circular plasmid DNA all inhibiting ligation equally. A >15-fold reduction in T4 DNA ligase self-adenylylation rate when in the presence of high non-nicked dsDNA concentrations was observed. Finally, EMSAs were utilized to demonstrate that non-substrate dsDNA can compete with nicked dsDNA substrates for enzyme binding. Based upon these data, we hypothesize the inhibition of T4 DNA ligase by non-nicked dsDNA is direct evidence for a two-step nick-binding mechanism, with an initial, nick-independent, transient dsDNA-binding event preceding a transition to a stable binding complex in the presence of a nick site. PMID:26954034

The Inhibitory Effect of Non-Substrate and Substrate DNA on the Ligation and Self-Adenylylation Reactions Catalyzed by T4 DNA Ligase.

PubMed

Bauer, Robert J; Evans, Thomas C; Lohman, Gregory J S

2016-01-01

DNA ligases are essential both to in vivo replication, repair and recombination processes, and in vitro molecular biology protocols. Prior characterization of DNA ligases through gel shift assays has shown the presence of a nick site to be essential for tight binding between the enzyme and its dsDNA substrate, with no interaction evident on dsDNA lacking a nick. In the current study, we observed a significant substrate inhibition effect, as well as the inhibition of both the self-adenylylation and nick-sealing steps of T4 DNA ligase by non-nicked, non-substrate dsDNA. Inhibition by non-substrate DNA was dependent only on the total DNA concentration rather than the structure; with 1 μg/mL of 40-mers, 75-mers, or circular plasmid DNA all inhibiting ligation equally. A >15-fold reduction in T4 DNA ligase self-adenylylation rate when in the presence of high non-nicked dsDNA concentrations was observed. Finally, EMSAs were utilized to demonstrate that non-substrate dsDNA can compete with nicked dsDNA substrates for enzyme binding. Based upon these data, we hypothesize the inhibition of T4 DNA ligase by non-nicked dsDNA is direct evidence for a two-step nick-binding mechanism, with an initial, nick-independent, transient dsDNA-binding event preceding a transition to a stable binding complex in the presence of a nick site.

Nutrient leaching from extensive green roofs with different substrate compositions: a laboratory study.

PubMed

Zhang, Wei; Zhong, Xing; Che, Wu

2018-02-01

To investigate nutrient leaching from extensive green roofs, green roof platforms were established to investigate the effluent quantity and quality during artificial rainfall. When the influent volume reached three times the empty bed volume, for which the cumulative rainfall was around 300 mm, the effluent TP and COD concentrations of green roof platforms filled with peat soil did not tend to stabilize. For a long-term operation, the substrate depths had little significant influence on TN, TP and COD concentrations of the green roof effluents. A normalized cumulative emission process method was proposed to discuss the difference in various pollutant leaching processes. Obvious differences in the leaching process of different contaminants for green roof platforms filled with various substrates were observed. For the green roof filled with modified substrates, the nitrogen and phosphorus pollutant leaching rates were relatively high in the initial stage of green roof operation and the phosphorus leaching rate was higher than that of nitrogen. The green roof is a sink for TN, but not for TP and COD in this study. The outcomes are critical for the selection of green roof substrates and also contribute to green roof maintenance.

Method of preparation of a CO.sub.2 removal sorbent with high chemical stability during multiple cycles

DOEpatents

Siriwardane, Ranjani V.; Rosencwaig, Shira

2015-07-14

Method for the production of a clay-alkali-amine CO.sub.2 sorbent prepared by integrating a clay substrate, basic alkali salt, and amine liquid. The basic alkali salt is present relative to the clay substrate in a weight ratio of from about 1 part to about 50 parts per 100 parts of the clay substrate. The amine liquid is present relative to a clay-alkali combination in a weight ratio of from about 1 part to about 10 parts per 10 parts of the clay-alkali combination. The clay substrate and basic alkali salt may be combined in a solid-solid heterogeneous mixture and followed by introduction of the amine liquid. Alternatively, an alkaline solution may be blended with the amine solution prior to contacting the clay substrate. The clay-alkali-amine CO.sub.2 sorbent is particularly advantageous for low temperature CO.sub.2 removal cycles in a gas stream having a CO.sub.2 concentration less than around 2000 ppm and an oxygen concentration around 21%, such as air. Results are presented illustrating the performance of the clay-alkali-amine CO.sub.2 sorbent compared to a clay-amine sorbent lacking the alkali inclusion.

Influence of drainage and nutrient-solution nitrogen and potassium concentrations on the agronomic behavior of bell-pepper plants cultivated in a substrate

PubMed Central

2017-01-01

The interactive effects of N (6, 9, 12 and 15 mmol L-1) and K (3, 5, 7, and 9 mmol L-1) concentrations in nutrient solutions were evaluated on bell pepper grown in a coconut-coir substrate and fertilized without drainage. An additional treatment with drainage was evaluated using N and K concentrations of 12 and 7 mmol L-1, respectively. The hybrid Eppo cultivar of yellow bell pepper was cultivated for 252 days beginning 9 November 2012. Electrical conductivity (EC), the N and K concentrations in the substrate solution, marketable fruit yield, total dry weight and macronutrient concentrations in shoots were periodically evaluated. Fruit production was lower in the system without drainage, regardless of the N and K concentrations, compared to the recommended 10–20% drainage of the volume of nutrient solution applied. Higher K concentrations in the nutrient solution did not affect plant production in the system without drainage for the substrate with an initial K concentration of 331.3 mg L-1. Fruit yield was higher without drainage at a nutrient-solution N concentration of 10.7 mmol L-1. The upper EC limit of the substrate solution in the system without drainage was exceeded 181 days after planting. Either lower nutrient concentrations in the nutrient solution or a drainage system could thus control the EC in the substrate solution. PMID:28678884

Effect of film thickness on localized surface plasmon enhanced chemical sensor

NASA Astrophysics Data System (ADS)

Kassu, Aschalew; Farley, Carlton; Sharma, Anup; Kim, Wonkyu; Guo, Junpeng

2014-05-01

A highly-sensitive, reliable, simple and inexpensive chemical detection and identification platform is demonstrated. The sensing technique is based on localized surface plasmon enhanced Raman scattering measurements from gold-coated highly-ordered symmetric nanoporous ceramic membranes fabricated from anodic aluminum oxide. To investigate the effects of the thickness of the sputter-coated gold films on the sensitivity of sensor, and optimize the performance of the substrates, the geometry of the nanopores and the film thicknesses are varied in the range of 30 nm to 120 nm. To characterize the sensing technique and the detection limits, surface enhanced Raman scatterings of low concentrations of a standard chemical adsorbed on the gold coated substrates are collected and analyzed. The morphology of the proposed substrates is characterized by atomic force microscopy and the optical properties including transmittance, reflectance and absorbance of each substrate are also investigated.

Fabrication of chitosan-silver nanoparticle hybrid 3D porous structure as a SERS substrate for biomedical applications

NASA Astrophysics Data System (ADS)

Jung, Gyeong-Bok; Kim, Ji-Hye; Burm, Jin Sik; Park, Hun-Kuk

2013-05-01

We propose a simple, low-cost, large-area, and functional surface enhanced Raman scattering (SERS) substrate for biomedical applications. The SERS substrate with chitosan-silver nanoparticles (chitosan-Ag NPs) hybrid 3D porous structure was fabricated simply by a one-step method. The chitosan was used as a template for the Ag NPs deposition. SERS enhancement by the chitosan-Ag NPs substrate was experimentally verified using rhodamine B as an analyte. Thiolated single stranded DNA was also measured for atopic dermatitis genetic markers (chemokines CCL17) at a low concentration of 5 pM. We successfully designed a novel SERS substrate with silver nanoparticle hybridized 3D porous chitosan that has the potential to become a highly sensitive and selective tool for biomedical applications.

Electron concentration in highly resistive GaN substrates co-doped with Si, C, and Fe

NASA Astrophysics Data System (ADS)

Tokuda, Hirokuni; Suzuki, Kosuke; Asubar, Joel T.; Kuzuhara, Masaaki

2018-07-01

Electron concentration in highly resistive GaN substrates with intentional iron (Fe) dopants as well as unintentionally incorporated silicon (Si) and carbon (C) dopants has been investigated. Si, C, and Fe atomic concentrations were 2 × 1017, 1 × 1016, and 1 × 1019 cm‑3, respectively as measured by secondary ion mass spectroscopy (SIMS). Temperature dependence of current–voltage (I–V) characteristics revealed that the resistivity (ρ) was 3.8 × 109 Ω cm at 300 K and monotonously decreased to 3.1 × 104 Ω cm at 570 K, giving an activation energy of 0.63 eV. Electron concentration (n) was modeled using analytical equation assuming three impurity levels of Si donor, C and Fe acceptors. The n of 5.0 × 107 and 3.1 × 1012 cm‑3 at 300 and 570 K, respectively, with an effective activation energy of 0.60 eV, were derived based on the model. These calculated electron concentration values are in good agreement with the experimental results. In addition, quantitatively analyzed results revealed that around 2 orders of magnitude reduction of n is expected by increasing doping concentration of Fe from 1.0 × 1018 to 1.0 × 1020 cm‑3.

Effects of pH and Oxygen on Photosynthetic Reactions of Intact Chloroplasts 1

PubMed Central

Heber, Ulrich; Andrews, T. John; Boardman, N. Keith

1976-01-01

Oxygen inhibition of photosynthesis was studied with intact spinach (Spinacia oleracea L.) chloroplasts which exhibited very high rates of photosynthetic CO2 reduction and were insensitive to additions of photosynthetic intermediates when CO2 was available at saturating concentrations. Photosynthetic rates were measured polarographically as O2 evolution, and the extent of the reduction of substrate was estimated from the amount of O2 evolved. With CO2 as substrate, inhibition of photosynthesis by O2 was dependent on pH. At pH values above 8, rates of O2 evolution were strongly inhibited by O2 and only a fraction of the added bicarbonate was reduced before O2 evolution ceased. The extent of O2 evolution declined with increasing O2 concentration and decreasing initial bicarbonate concentration. At pH 7.2, the initial photosynthetic rate was inhibited about 30% at high O2 levels, but the extent of O2 evolution was unaffected and most of the added bicarbonate was reduced. Photosynthetic O2 evolution with 3-phosphoglycerate as substrate was similarly dependent on pH and O2 concentration. In contrast, there was little effect of O2 and pH on oxaloacetate-dependent oxygen evolution. Acid-base shift experiments with osmotically shocked chloroplasts showed that ATP formation was not affected by O2. The results are discussed in terms of a balance between photosynthetic O2 evolution and O2 consumption by the ribulose diphosphate oxygenase reaction. PMID:16659466

Growth graphene on silver-copper nanoparticles by chemical vapor deposition for high-performance surface-enhanced Raman scattering

NASA Astrophysics Data System (ADS)

Zhang, Xiumei; Xu, Shicai; Jiang, Shouzhen; Wang, Jihua; Wei, Jie; Xu, Shida; Gao, Shoubao; Liu, Hanping; Qiu, Hengwei; Li, Zhen; Liu, Huilan; Li, Zhenhua; Li, Hongsheng

2015-10-01

We present a graphene/silver-copper nanoparticle hybrid system (G/SCNPs) to be used as a high-performance surface-enhanced Raman scattering (SERS) substrate. The silver-copper nanoparticles wrapped by a monolayer graphene layer are directly synthesized on SiO2/Si substrate by chemical vapor deposition in a mixture of methane and hydrogen. The G/SCNPs shows excellent SERS enhancement activity and high reproducibility. The minimum detected concentration of R6G is as low as 10-10 M and the calibration curve shows a good linear response from 10-6 to 10-10 M. The date fluctuations from 20 positions of one SERS substrate are less than 8% and from 20 different substrates are less than 10%. The high reproducibility of the enhanced Raman signals could be due to the presence of an ultrathin graphene layer and uniform morphology of silver-copper nanoparticles. The use of G/SCNPs for detection of nucleosides extracted from human urine demonstrates great potential for the practical applications on a variety of detection in medicine and biotechnology field.

Detection of Prohibited Fish Drugs Using Silver Nanowires as Substrate for Surface-Enhanced Raman Scattering

PubMed Central

Song, Jia; Huang, Yiqun; Fan, Yuxia; Zhao, Zhihui; Yu, Wansong; Rasco, Barbara A.; Lai, Keqiang

2016-01-01

Surface-enhanced Raman scattering or surface-enhanced Raman spectroscopy (SERS) is a promising detection technology, and has captured increasing attention. Silver nanowires were synthesized using a rapid polyol method and optimized through adjustment of the molar ratio of poly(vinyl pyrrolidone) and silver nitrate in a glycerol system. Ultraviolet-visible spectrometry, X-ray diffraction, and transmission electron microscopy were used to characterize the silver nanowires. The optimal silver nanowires were used as a SERS substrate to detect prohibited fish drugs, including malachite green, crystal violet, furazolidone, and chloramphenicol. The SERS spectra of crystal violet could be clearly identified at concentrations as low as 0.01 ng/mL. The minimum detectable concentration for malachite green was 0.05 ng/mL, and for both furazolidone and chloramphenicol were 0.1 μg/mL. The results showed that the as-prepared Ag nanowires SERS substrate exhibits high sensitivity and activity. PMID:28335303

Effects of Continuous Triiodothyronine Infusion on Citric Acid Cycle in the Normal Immature Swine Heart under Extracorporeal Membrane Oxygenation in vivo

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

Kajimoto, Masaki; O'Kelly-Priddy, Colleen M.; Ledee, Dolena R.

Extracorporeal membrane oxygenation (ECMO) is frequently used in infants with postoperative cardiopulmonary failure. ECMO also suppresses circulating triiodothyronine (T 3) levels and modifies myocardial metabolism. We assessed the hypothesis that T 3 supplementation reverses ECMO induced metabolic abnormalities in the immature heart. Twenty-two male Yorkshire pigs (age 25-38 days) with ECMO were received [2- 13C]lactate, [2,4,6,8- 13C]octanoate (medium chain fatty acid) and [U- 13C]long-chain fatty acids as metabolic tracers either systemically (totally physiological intracoronary concentration) or directly into the coronary artery (high substrate concentration) for the last 60 minutes of each protocol. Nuclear magnetic resonance (NMR) analysis of left ventricularmore » tissue determined the fractional contribution (Fc) of these substrates to the citric acid cycle (CAC). Fifty percent of the pigs in each group received intravenous T 3 supplement (bolus at 0.6 μg/kg and then continuous infusion at 0.2 μg/kg/hour) during ECMO. Under both substrate loading conditions T 3 significantly increased lactate-Fc with a marginal increase in octanoate-Fc. Both T 3 and high substrate provision increased myocardial energy status indexed by [Phosphocreatine]/[ATP]. In conclusion, T 3 supplementation promoted lactate metabolism to the CAC during ECMO suggesting that T 3 releases inhibition of pyruvate dehydrogenase. Manipulation of substrate utilization by T 3 may be used therapeutically during ECMO to improve resting energy state and facilitate weaning.« less

Structural, Electrical and Optical Properties of Sputtered-Grown InN Films on ZnO Buffered Silicon, Bulk GaN, Quartz and Sapphire Substrates

NASA Astrophysics Data System (ADS)

Bashir, Umar; Hassan, Zainuriah; Ahmed, Naser M.; Afzal, Naveed

2018-05-01

Indium nitride (InN) films were grown on Si (111), bulk GaN, quartz and sapphire substrates by radio frequency magnetron sputtering. Prior to the film deposition, a zinc oxide (ZnO) buffer layer was deposited on all the substrates. The x-ray diffraction patterns of InN films on ZnO-buffered substrates indicated c-plane-oriented films whereas the Raman spectroscopy results indicated A1 (LO) and E2 (high) modes of InN on all the substrates. The crystalline quality of InN was found to be better on sapphire and quartz than on the other substrates. The surface roughness of InN was studied using an atomic force microscope. The results indicated higher surface roughness of the film on sapphire as compared to the others; however, roughness of the film was lower than 8 nm on all the substrates. The electrical properties indicated higher electron mobility of InN (20.20 cm2/Vs) on bulk GaN than on the other substrates. The optical band gap of InN film was more than 2 eV in all the cases and was attributed to high carrier concentration in the film.

Microstructural study of Mg-doped p-type GaN: Correlation between high-resolution electron microscopy and Raman spectroscopy

NASA Astrophysics Data System (ADS)

Tsen, S.-C. Y.; Smith, David J.; Tsen, K. T.; Kim, W.; Morkoç, H.

1997-12-01

A series of Mg-doped GaN films (˜1-1.3 μm) grown by reactive molecular beam epitaxy at substrate temperatures of 750 and 800 °C has been studied by high-resolution electron microscopy (HREM) and Raman spectroscopy. Stacking defects parallel to the substrate surface were observed in samples grown on sapphire substrates at 750 °C with AlN buffer layers (60-70 nm) at low Mg concentration. A transition region with mixed zinc-blende cubic (c) and wurtzite hexagonal (h) phases having the relative orientations of (111)c//(00.1)h and (11¯0)c//(10.0)h was observed for increased Mg concentration. The top surfaces of highly doped samples were rough and assumed a completely zinc-blende phase with some inclined stacking faults. Samples grown with a Mg cell temperature of 350 °C and high doping levels were highly disordered with many small crystals having inclined stacking faults, microtwins, and defective wurtzite and zinc-blende phases. Correlation between HREM and Raman scattering results points towards the presence of compressive lattice distortion along the growth direction which might be attributable to structural defects. The films grown at 800 °C had better quality with less observable defects and less yellow luminescence than samples grown at 750 °C.

Effect of the substrate on the insulator-metal transition of vanadium dioxide films

NASA Astrophysics Data System (ADS)

Kovács, György J.; Bürger, Danilo; Skorupa, Ilona; Reuther, Helfried; Heller, René; Schmidt, Heidemarie

2011-03-01

Single-phase vanadium dioxide films grown on (0001) sapphire and (001) silicon substrates show a very different insulator-metal electronic transition. A detailed description of the growth mechanisms and the substrate-film interaction is given, and the characteristics of the electronic transition are described by the morphology and grain boundary structure. (Tri-)epitaxy-stabilized columnar growth of VO2 takes place on the sapphire substrate, whereas on silicon the expected Zone II growth is identified. We have found that in the case of the Si substrate the reasons for the broader hysteresis and the lower switching amplitude are the formation of an amorphous insulating VOx (x > 2.6) phase coexisting with VO2 and the high vanadium vacancy concentration of the VO2. These phenomena are the result of the excess oxygen during the growth and the interaction between the silicon substrate and the growing film.

Spectroscopy on the wing: naturally inspired SERS substrates for biochemical analysis.

PubMed

Garrett, Natalie L; Vukusic, Peter; Ogrin, Feodor; Sirotkin, Evgeny; Winlove, C Peter; Moger, Julian

2009-03-01

We show that naturally occurring chitinous nanostructures found on the wings of the Graphium butterfly can be used as substrates for surface-enhanced Raman scattering when coated with a thin film of gold or silver. The substrates were found to exhibit excellent biocompatibility and sensitivity, making them ideal for protein assaying. An assay using avidin/biotin binding showed that the substrates could be used to quantify protein binding directly from changes in the surface-enhanced Raman scattering (SERS) spectra and were sensitive over a concentration range comparable with a typical enzyme-linked immunosorbent assays (ELISA) assay. A biomimetic version of the wing nanostructures produced using a highly reproducible, large-scale fabrication process, yielded comparable enhancement factors and biocompatibility. The excellent biocompatibility of the wings and biomimetic substrates is unparalleled by other lithographically produced substrates, and this could pave the way for widespread application of ultrasensitive SERS-based bioassays.

Electrical properties and surface morphology of electron beam evaporated p-type silicon thin films on polyethylene terephthalate for solar cells applications

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

Ang, P. C.; Ibrahim, K.; Pakhuruddin, M. Z.

2015-04-24

One way to realize low-cost thin film silicon (Si) solar cells fabrication is by depositing the films with high-deposition rate and manufacturing-compatible electron beam (e-beam) evaporation onto inexpensive foreign substrates such as glass or plastic. Most of the ongoing research is reported on e-beam evaporation of Si films on glass substrates to make polycrystalline solar cells but works combining both e-beam evaporation and plastic substrates are still scarce in the literature. This paper studies electrical properties and surface morphology of 1 µm electron beam evaporated Al-doped p-type silicon thin films on textured polyethylene terephthalate (PET) substrate for application as anmore » absorber layer in solar cells. In this work, Si thin films with different doping concentrations (including an undoped reference) are prepared by e-beam evaporation. Energy dispersion X-ray (EDX) showed that the Si films are uniformly doped by Al dopant atoms. With increased Al/Si ratio, doping concentration increased while both resistivity and carrier mobility of the films showed opposite relationships. Root mean square (RMS) surface roughness increased. Overall, the Al-doped Si film with Al/Si ratio of 2% (doping concentration = 1.57×10{sup 16} atoms/cm{sup 3}) has been found to provide the optimum properties of a p-type absorber layer for fabrication of thin film Si solar cells on PET substrate.« less

Microbial respiration and kinetics of extracellular enzymes activities through rhizosphere and detritusphere at agricultural site

NASA Astrophysics Data System (ADS)

Löppmann, Sebastian; Blagodatskaya, Evgenia; Kuzyakov, Yakov

2014-05-01

Rhizosphere and detritusphere are soil microsites with very high resource availability for microorganisms affecting their biomass, composition and functions. In the rhizosphere low molecular compounds occur with root exudates and low available polymeric compounds, as belowground plant senescence. In detritusphere the substrate for decomposition is mainly a polymeric material of low availability. We hypothesized that microorganisms adapted to contrasting quality and availability of substrates in the rhizosphere and detritusphere are strongly different in affinity of hydrolytic enzymes responsible for decomposition of organic compounds. According to common ecological principles easily available substrates are quickly consumed by microorganisms with enzymes of low substrate affinity (i.e. r-strategists). The slow-growing K-strategists with enzymes of high substrate affinity are better adapted for growth on substrates of low availability. Estimation of affinity of enzyme systems to the substrate is based on Michaelis-Menten kinetics, reflecting the dependency of decomposition rates on substrate amount. As enzymes-mediated reactions are substrate-dependent, we further hypothesized that the largest differences in hydrolytic activity between the rhizosphere and detritusphere occur at substrate saturation and that these differences are smoothed with increasing limitation of substrate. Affected by substrate limitation, microbial species follow a certain adaptation strategy. To achieve different depth gradients of substrate availability 12 plots on an agricultural field were established in the north-west of Göttingen, Germany: 1) 4 plots planted with maize, reflecting lower substrate availability with depth; 2) 4 unplanted plots with maize litter input (0.8 kg m-2 dry maize residues), corresponding to detritusphere; 3) 4 bare fallow plots as control. Maize litter was grubbed homogenously into the soil at the first 5 cm to ensure comparable conditions for the herbivore and detritivore communities in the soil. The kinetics (Km and Vmax) of four extracellular hydrolytic enzymes responsible for C- and phosphorous-cycle (β-glucosidase, β-xylosidase, β-cellobiohydrolase and acid phosphatase), microbial biomass, basal respiration (BR) and substrate-induced respiration (SIR) were measured in rhizosphere, detritusphere and control from 0 - 10 and 10 - 20 cm. The metabolic quotient (qCO2) was calculated as specific indicator for efficiency of microbial substrate utilization. We observed clear differences in enzymes activities at low and high concentrations of substrate. At substrate saturation enzyme activity rates of were significantly higher in rooted plots compared to litter amended plots, whereas at lower concentration no treatment effect could be found. The BR, SIR and qCO2 values were significantly higher at 0 - 10 cm of the planted treatment compared to litter and control plots, revealing a significantly higher respiration at lower efficiency of microbial substrate utilization in the rhizosphere. The Michaelis-Menten constant (Km) decreased with depth, especially for β-glucosidase, acid phosphatase and β-xylosidase, indicating higher substrate affinity of microorganisms in deeper soil and therefore different enzyme systems functioning. The substrate affinity factor (Vmax/Km) increased 2-fold with depth for various enzymes, reflecting a switch of predominantly occurring microbial strategies. Vmax/Km ratio indicated relative domination of zymogenous microbial communities (r-strategists) in 0 - 10 cm depth as compared with 10 - 20 cm depth where the K-strategists dominated.

Contrasting ability to take up leucine and thymidine among freshwater bacterial groups: implications for bacterial production measurements

PubMed Central

Pérez, María Teresa; Hörtnagl, Paul; Sommaruga, Ruben

2010-01-01

We examined the ability of different freshwater bacterial groups to take up leucine and thymidine in two lakes. Utilization of both substrates by freshwater bacteria was examined at the community level by looking at bulk incorporation rates and at the single-cell level by combining fluorescent in situ hybridization and signal amplification by catalysed reporter deposition with microautoradiography. Our results showed that leucine was taken up by 70–80% of Bacteria-positive cells, whereas only 15–43% of Bacteria-positive cells were able to take up thymidine. When a saturating substrate concentration in combination with a short incubation was used, 80–90% of Betaproteobacteria and 67–79% of Actinobacteria were positive for leucine uptake, whereas thymidine was taken up by < 10% of Betaproteobacteria and by < 1% of the R-BT subgroup that dominated this bacterial group. Bacterial abundance was a good predictor of the relative contribution of bacterial groups to leucine uptake, whereas when thymidine was used Actinobacteria represented the large majority (> 80%) of the cells taking up this substrate. Increasing the substrate concentration to 100 nM did not affect the percentage of R-BT cells taking up leucine (> 90% even at low concentrations), but moderately increased the fraction of thymidine-positive R-BT cells to a maximum of 35% of the hybridized cells. Our results show that even at very high concentrations, thymidine is not taken up by all, otherwise active, bacterial cells. PMID:19725866

Serine Protease Zymography: Low-Cost, Rapid, and Highly Sensitive RAMA Casein Zymography.

PubMed

Yasumitsu, Hidetaro

2017-01-01

To detect serine protease activity by zymography, casein and CBB stain have been used as a substrate and a detection procedure, respectively. Casein zymography has been using substrate concentration at 1 mg/mL and employing conventional CBB stain. Although ordinary casein zymography provides reproducible results, it has several disadvantages including time-consuming and relative low sensitivity. Improved casein zymography, RAMA casein zymography, is rapid and highly sensitive. RAMA casein zymography completes the detection process within 1 h after incubation and increases the sensitivity at least by tenfold. In addition to serine protease, the method also detects metalloprotease 7 (MMP7, Matrilysin) with high sensitivity.

Increased oceanic microplastic debris enhances oviposition in an endemic pelagic insect

PubMed Central

Goldstein, Miriam C.; Rosenberg, Marci; Cheng, Lanna

2012-01-01

Plastic pollution in the form of small particles (diameter less than 5 mm)—termed ‘microplastic’—has been observed in many parts of the world ocean. They are known to interact with biota on the individual level, e.g. through ingestion, but their population-level impacts are largely unknown. One potential mechanism for microplastic-induced alteration of pelagic ecosystems is through the introduction of hard-substrate habitat to ecosystems where it is naturally rare. Here, we show that microplastic concentrations in the North Pacific Subtropical Gyre (NPSG) have increased by two orders of magnitude in the past four decades, and that this increase has released the pelagic insect Halobates sericeus from substrate limitation for oviposition. High concentrations of microplastic in the NPSG resulted in a positive correlation between H. sericeus and microplastic, and an overall increase in H. sericeus egg densities. Predation on H. sericeus eggs and recent hatchlings may facilitate the transfer of energy between pelagic- and substrate-associated assemblages. The dynamics of hard-substrate-associated organisms may be important to understanding the ecological impacts of oceanic microplastic pollution. PMID:22573831

Increased oceanic microplastic debris enhances oviposition in an endemic pelagic insect.

PubMed

Goldstein, Miriam C; Rosenberg, Marci; Cheng, Lanna

2012-10-23

Plastic pollution in the form of small particles (diameter less than 5 mm)--termed 'microplastic'--has been observed in many parts of the world ocean. They are known to interact with biota on the individual level, e.g. through ingestion, but their population-level impacts are largely unknown. One potential mechanism for microplastic-induced alteration of pelagic ecosystems is through the introduction of hard-substrate habitat to ecosystems where it is naturally rare. Here, we show that microplastic concentrations in the North Pacific Subtropical Gyre (NPSG) have increased by two orders of magnitude in the past four decades, and that this increase has released the pelagic insect Halobates sericeus from substrate limitation for oviposition. High concentrations of microplastic in the NPSG resulted in a positive correlation between H. sericeus and microplastic, and an overall increase in H. sericeus egg densities. Predation on H. sericeus eggs and recent hatchlings may facilitate the transfer of energy between pelagic- and substrate-associated assemblages. The dynamics of hard-substrate-associated organisms may be important to understanding the ecological impacts of oceanic microplastic pollution.

Silicanizing Process On Mild Steel Substrate by Using Tronoh Silica Sand: Microstructure, composition and coating growth

NASA Astrophysics Data System (ADS)

Y, Yusnenti F. M.; M, Othman; Mustapha, Mazli; I, MohdYusri

2016-02-01

A new Silicanizing process on formation of coating on mild steel using Tronoh Silica Sand (TSS) is presented. The process was performed in the temperature range 1000- 1100°C and with varying deposition time of 1-4 hours. Influence of the layer and the substrate constituents on the coating compatibility of the whole silicanized layer is described in detail. Morphology and structure of the silicanized layer were investigated by XRF, XRD and SEM. It is observed that diffusion coatings containing high concentrations of silica which profile distribution of SiO2 in the silicanized layer was encountered and the depth from the surface to the substrate was taken as the layer thickness. The results also depicted that a longer deposition time have tendency to produce a looser and larger grain a hence rougher layer. The silicanized layer composed of FeSi and Fe2SiO4 phases with preferred orientation within the experimental range. It is also found that longer deposition time and higher temperature resulted in an increase in SiO2 concentration on the substrate (mild steel).

Overlay coating degradation by simultaneous oxidation and coating/substrate interdiffusion. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Nesbitt, J. A.

1983-01-01

Degradation of NiCrAlZr overlay coatings on various NiCrAl substrates was examined after cyclic oxidation. Concentration/distance profiles were measured in the coating and substrate after various oxidation exposures at 1150 C. For each stubstrate, the Al content in the coating decreased rapidly. The concentration/distance profiles, and particularly that for Al, reflected the oxide spalling resistance of each coated substrate. A numerical model was developed to simulate diffusion associated with overlay-coating degradation by oxidation and coating/substrate interdiffusion. Input to the numerical model consisted of the Cr and Al content of the coating and substrate, ternary diffusivities, and various oxide spalling parameters. The model predicts the Cr and Al concentrations in the coating and substrate after any number of oxidation/thermal cycles. The numerical model also predicts coating failure based on the ability of the coating to supply sufficient Al to the oxide scale. The validity of the model was confirmed by comparison of the predicted and measured concentration/distance profiles. The model was subsequently used to identify the most critical system parameters affecting coating life.

Rare earth elements concentration in mushroom cultivation substrates affects the production process and fruit-bodies content of Pleurotus ostreatus and Cyclocybe cylindracea.

PubMed

Koutrotsios, Georgios; Danezis, Georgios P; Georgiou, Constantinos A; Zervakis, Georgios I

2018-04-20

Concentrations of 16 rare earth elements (REEs) and two actinides were determined for the first time both in cultivated mushrooms and in their production substrates by inductively coupled plasma mass spectroscopy. Moreover, the effect of REEs on cultivation parameters and composition of the final product was assessed, together with their potential use for authentication purposes. The concentrations of REEs varied greatly among seven cultivation substrates and correlated with measurements in Cyclocybe cylindracea mushrooms; no such correlation was established in Pleurotus ostreatus. Reduction of hemicellulose, cellulose, and lignin in substrates during P. ostreatus cultivation was positively correlated with REE concentrations, which also affected the production performance depending on the species examined. In all cases, a negative correlation was established between bioconcentration factors (BCF) in mushrooms and REE content in substrates, while the effect of substrate composition on BCF values varied according to the element studied. The estimated daily intake values of REEs through mushroom consumption was at much lower levels than those reported as potentially harmful for human health. The content of REEs in cultivation substrates and in mushrooms revealed that the bioaccumulation of elements differed in each fungus. The nature/origin of substrates seemed to affect the concentration of REEs in mushrooms to a considerable extent. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

Tripartite ATP-independent Periplasmic (TRAP) Transporters Use an Arginine-mediated Selectivity Filter for High Affinity Substrate Binding*

PubMed Central

Fischer, Marcus; Hopkins, Adam P.; Severi, Emmanuele; Hawkhead, Judith; Bawdon, Daniel; Watts, Andrew G.; Hubbard, Roderick E.; Thomas, Gavin H.

2015-01-01

Tripartite ATP-independent periplasmic (TRAP) transporters are secondary transporters that have evolved an obligate dependence on a substrate-binding protein (SBP) to confer unidirectional transport. Different members of the DctP family of TRAP SBPs have binding sites that recognize a diverse range of organic acid ligands but appear to only share a common electrostatic interaction between a conserved arginine and a carboxylate group in the ligand. We investigated the significance of this interaction using the sialic acid-specific SBP, SiaP, from the Haemophilus influenzae virulence-related SiaPQM TRAP transporter. Using in vitro, in vivo, and structural methods applied to SiaP, we demonstrate that the coordination of the acidic ligand moiety of sialic acid by the conserved arginine (Arg-147) is essential for the function of the transporter as a high affinity scavenging system. However, at high substrate concentrations, the transporter can function in the absence of Arg-147 suggesting that this bi-molecular interaction is not involved in further stages of the transport cycle. As well as being required for high affinity binding, we also demonstrate that the Arg-147 is a strong selectivity filter for carboxylate-containing substrates in TRAP transporters by engineering the SBP to recognize a non-carboxylate-containing substrate, sialylamide, through water-mediated interactions. Together, these data provide biochemical and structural support that TRAP transporters function predominantly as high affinity transporters for carboxylate-containing substrates. PMID:26342690

A highly sensitive biological detection substrate based on TiO2 nanowires supporting gold nanoparticles

NASA Astrophysics Data System (ADS)

Zeng, Yuan; Tan, Hai-jun; Cheng, Xiu-Lan; Chen, Rui; Wang, Ying

2011-12-01

Surface enhanced Raman scattering (SERS) has attracted widespread concern in the field of bioassay because it can enhance normally weak Raman signal by several orders of magnitude and facilitate the highly sensitive detection of molecules. Conventional SERS substrates are prepared by placing metal nanoparticles on a planar surface. Here we show a unique SERS substrate stacked by disordered TiO2 nanowires (TiO2-NWs) supportig gold nanocrystals. The structure can be easily fabricated by chemical synthesis at low cost. The COMSOL model simulation shows the designed SERS substrate is capable of output high Local Field Enhancement (LFE) in the Near Infrared region (NIR) that is the optimal wavelength in bio-detection because of both the unique coupling enhancement effect amony nearby Au nanocrystals on TiO2-NWs and the Suface Plasmon Resonance (SPR) effect of TiO2 -NWs. The as-prepared transparent and freestanding SERS substrate is capable of detecting extremely low concentration R6G molecular, showing much higher Raman signal because of the extremely large surface area and the uniqueTiO2-NWs self-assemblied by Au nanocrystals. These results provide a new approach to ultrasensitive bioassay device.

Photonic metasurface made of array of lens-like SiGe Mie resonators formed on (100) Si substrate via dewetting

NASA Astrophysics Data System (ADS)

Poborchii, Vladimir; Shklyaev, Alexander; Bolotov, Leonid; Uchida, Noriyuki; Tada, Tetsuya; Utegulov, Zhandos N.

2017-12-01

Metasurfaces consisting of arrays of high-index Mie resonators concentrating/redirecting light are important for integrated optics, photodetectors, and solar cells. Herein, we report the optical properties of low-Ge-content SiGe lens-like Mie resonator island arrays fabricated via dewetting during Ge deposition on a Si(100) surface at approximately 900 °C. We observe enhancement of the Si interaction with light owing to the efficient island-induced light concentration in the submicron-depth Si layer, which is mediated by both near-field Mie resonance leaking into the substrate and far-field light focusing. Such metasurfaces can improve the Si photodetector and solar-cell performance.

Method of making reflecting film reflector

DOEpatents

Cottingham, James G.

1980-01-01

A reflector of the reflecting film type is disclosed and which may be used in a heliostatic system for concentrating solar energy and comprising a reflecting film bonded to an appropriate rigid substrate in such a way that specularity of a very high order is achieved. A method of bonding the reflecting film to the substrate is also disclosed and comprises the steps of initially adhering the film to a smooth, clean flat rigid surface with a non-bonding liquid between the rigid surface and film, and then bonding the substrate and film. The non-bonding liquid has a molecular adhesion greater than any stresses due to handling or curing of the bonding agent which is applied between the film and the opposing surface of the rigid substrate.

An Additional Method for Analyzing the Reversible Inhibition of an 
Enzyme Using Acid Phosphatase as a Model.

PubMed

Baumhardt, Jordan M; Dorsey, Benjamin M; McLauchlan, Craig C; Jones, Marjorie A

2015-08-01

Using wheat germ acid phosphatase and sodium orthovanadate as a competitive inhibitor, a novel method for analyzing reversible inhibition was carried out. Our alternative approach involves plotting the initial velocity at which product is formed as a function of the ratio of substrate concentration to inhibitor concentration at a constant enzyme concentration and constant assay conditions. The concept of initial concentrations driving equilibrium leads to the chosen axes. Three apparent constants can be derived from this plot: K max , K min , and K inflect . K max and K min represent the substrate to inhibitor concentration ratio for complete inhibition and minimal inhibition, respectively. K inflect represents the substrate to inhibitor concentration ratio at which the enzyme-substrate complex is equal to the inhibitory complex. These constants can be interpolated from the graph or calculated using the first and second derivative of the plot. We conclude that a steeper slope and a shift of the line to the right (increased x-axis values) would indicate a better inhibitor. Since initial velocity is not a linear function of the substrate/inhibitor ratio, this means that inhibition changes more quickly with the change in the [S]/ [I] ratio. When preincubating the enzyme with substrate before the addition of inhibitor, preincubating the enzyme with inhibitor before the addition of substrate or with concurrent addition of both substrate and inhibitor, modest changes in the slopes and y-intercepts were obtained. This plot appears useful for known competitive and non-competitive inhibitors and may have general applicability.

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

Sabah, Fayroz A., E-mail: fayroz-arif@yahoo.com; Department of Electrical Engineering, College of Engineering, Al-Mustansiriya University, Baghdad; Ahmed, Naser M., E-mail: naser@usm.my

The copper sulphide (CuS) thin films were grown with good adhesion by spray pyrolysis deposition (SPD) on Ti, ITO and glass substrates at 200 °C. The distance between nozzle and substrate is 30 cm. The composition was prepared by mixing copper chloride CuCl{sub 2}.2H{sub 2}O as a source of Cu{sup 2+} and sodium thiosulfate Na{sub 2}S{sub 2}O{sub 3}.5H{sub 2}O as a source of and S{sup 2−}. Two concentrations (0.2 and 0.4 M) were used for each CuCl{sub 2} and Na{sub 2}S{sub 2}O{sub 3} to be prepared and then sprayed (20 ml). The process was started by spraying the solution formore » 3 seconds and after 10 seconds the cycle was repeated until the solution was sprayed completely on the hot substrates. The structural characteristics were studied using X-ray diffraction; they showed covellite CuS hexagonal crystal structure for 0.2 M concentration, and covellite CuS hexagonal crystal structure with two small peaks of chalcocite Cu{sub 2}S hexagonal crystal structure for 0.4 M concentration. Also the surface and electrical characteristics were investigated using Field Emission Scanning Electron Microscopy (FESEM) and current source device, respectively. The surface study for the CuS thin films showed nanorods to be established for 0.2 M concentration and mix of nanorods and nanoplates for 0.4 M concentration. The electrical study showed ohmic behavior and low resistivity for these films. Hall Effect was measured for these thin films, it showed that all samples of CuS are p- type thin films and ensured that the resistivity for thin films of 0.2 M concentration was lower than that of 0.4 M concentration; and for the two concentrations CuS thin film deposited on ITO had the lowest resistivity. This leads to the result that the conductivity was high for CuS thin film deposited on ITO substrate, and the conductivity of the three thin films of 0.2 M concentration was higher than that of 0.4 M concentration.« less

Biobased methacrylic acid via selective catalytic decarboxylation of itaconic acid

USDA-ARS?s Scientific Manuscript database

We report a bio-based route to methacrylic acid via selective decarboxylation of itaconic acid utilizing catalytic ruthenium carbonyl propionate in an aqueous solvent system. High selectivity (>90%) was achieved at low catalyst loading (0.1 mol %) with high substrate concentration (5.5 M) at low tem...

High performance ZnO:Al films deposited on PET substrates using facing target sputtering

NASA Astrophysics Data System (ADS)

Guo, Tingting; Dong, Guobo; Gao, Fangyuan; Xiao, Yu; Chen, Qiang; Diao, Xungang

2013-10-01

ZnO:Al (ZAO) thin films have been deposited on flexible PET substrates using a plasma damage-free facing target sputtering system at room temperature. The structure, surface morphology, electrical and optical properties were investigated as a function of working power. All the samples have a highly preferred orientation of the c-axis perpendicular to the PET substrate and have a high quality surface. With increased working power, the carrier concentration changes slightly, the mobility increases at the beginning and decreases after it reaches a maximum value, in line with electrical conductivity. The figure of merit has been significantly improved with increasing of the working power. Under the optimized condition, the lowest resistivity of 1.3 × 10-3 Ω cm with a sheet resistance of 29 Ω/□ and the relative visible transmittance above 93% in the visible region were obtained.

Temperature and substrate chemistry as major drivers of interregional variability of leaf microbial decomposition and cellulolytic activity in headwater streams.

PubMed

Fenoy, Encarnación; Casas, J Jesús; Díaz-López, Manuel; Rubio, Juan; Guil-Guerrero, J Luís; Moyano-López, Francisco J

2016-11-01

Abiotic factors, substrate chemistry and decomposers community composition are primary drivers of leaf litter decomposition. In soil, much of the variation in litter decomposition is explained by climate and substrate chemistry, but with a significant contribution of the specialisation of decomposer communities to degrade specific substrates (home-field advantage, HFA). In streams, however, HFA effects on litter decomposition have not been explicitly tested. We evaluated responses of microbial decomposition and β-glucosidase activity to abiotic factors, substrate and decomposer assemblages, using a reciprocal litter transplant experiment: 'ecosystem type' (mountain vs lowland streams) × 'litter chemistry' (alder vs reed). Temperature, pH and ionic concentration were higher in lowland streams. Decomposition for both species was faster in lowland streams. Decomposition of reed was more accelerated in lowland compared with mountain streams than that of alder, suggesting higher temperature sensitivity of decomposition in reed. Q10 (5°C-15°C) values of β-glucosidase activity were over 2. The alkaline pH and high ionic concentration of lowland streams depleted enzyme activity. We found similar relationships of decomposition or enzyme activity with abiotic factors for both species, suggesting limited support to the HFA hypothesis. Overall, our results suggest a prime role of temperature interacting with substrate chemistry on litter decomposition. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Lactulose production by a thermostable glycoside hydrolase from the hyperthermophilic archaeon Caldivirga maquilingensis IC-167.

PubMed

Letsididi, Rebaone; Hassanin, Hinawi Am; Koko, Marwa Yf; Zhang, Tao; Jiang, Bo; Mu, Wanmeng

2018-02-01

Lactulose has various uses in the food and pharmaceutical fields. Thermostable enzymes have many advantages for industrial exploitation, including high substrate solubilities as well as reduced risk of process contamination. Enzymatic synthesis of lactulose employing a transgalactosylation reaction by a recombinant thermostable glycoside hydrolase (GH1) from the hyperthermophilic archaeon Caldivirga maquilingensis IC-167 was investigated. The optimal pH for lactulose production was found to be 4.5, while the optimal temperature was 85 °C, before it dropped moderately to 83% at 90 °C. However, the relative activity for lactulose synthesis dropped sharply to 35% at 95 °C. At optimal reaction conditions of 70% (w/w) initial sugar substrates with molar ratio of lactose to fructose of 1:4, 15 U mL -1 enzyme concentration and 85 °C, the time course reaction produced a maximum lactulose concentration of 108 g L -1 at 4 h, corresponding to a lactulose yield of 14% and 27 g L -1  h -1 productivity with 84% lactose conversion. The transgalactosylation reaction for lactulose synthesis was greatly influenced by the ratio of galactose donor to acceptor. This novel GH1 may be useful for process applications owing to its high activity in very concentrated substrate reaction media and promising thermostability. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Catalytic efficiency is a better predictor of arsenic toxicity to soil alkaline phosphatase.

PubMed

Wang, Ziquan; Tian, Haixia; Lu, Guannan; Zhao, Yiming; Yang, Rui; Megharaj, Mallavarapu; He, Wenxiang

2018-02-01

Arsenic (As) is an inhibitor of phosphatase, however, in the complex soil system, the substrate concentration effect and the mechanism of As inhibition of soil alkaline phosphatase (ALP) and its kinetics has not been adequately studied. In this work, we investigated soil ALP activity in response to As pollution at different substrate concentrations in various types of soils and explored the inhibition mechanism using the enzyme kinetics. The results showed that As inhibition of soil ALP activity was substrate concentration-dependent. Increasing substrate concentration decreased inhibition rate, suggesting reduced toxicity. This dependency was due to the competitive inhibition mechanism of As to soil ALP. The kinetic parameters, maximum reaction velocity (V max ) and Michaelis constant (K m ) in unpolluted soils were 0.012-0.267mMh -1 and 1.34-3.79mM respectively. The competitive inhibition constant (K ic ) was 0.17-0.70mM, which was lower than K m , suggesting higher enzyme affinity for As than for substrate. The ecological doses, ED 10 and ED 50 (concentration of As that results in 10% and 50% inhibition on enzyme parameter) for inhibition of catalytic efficiency (V max /K m ) were lower than those for inhibition of enzyme activity at different substrate concentrations. This suggests that the integrated kinetic parameter, catalytic efficiency is substrate concentration independent and more sensitive to As than ALP activity. Thus, catalytic efficiency was proposed as a more reliable indicator than ALP activity for risk assessment of As pollution. Copyright © 2017 Elsevier Inc. All rights reserved.

Multiple evidence for methylotrophic methanogenesis as the dominant methanogenic pathway in hypersaline sediments from the Orca Basin, Gulf of Mexico

NASA Astrophysics Data System (ADS)

Zhuang, Guang-Chao; Elling, Felix J.; Nigro, Lisa M.; Samarkin, Vladimir; Joye, Samantha B.; Teske, Andreas; Hinrichs, Kai-Uwe

2016-08-01

Among the most extreme habitats on Earth, dark, deep, anoxic brines host unique microbial ecosystems that remain largely unexplored. As the terminal step of anaerobic degradation of organic matter, methanogenesis is a potentially significant but poorly constrained process in deep-sea hypersaline environments. We combined biogeochemical and phylogenetic analyses with incubation experiments to unravel the origin of methane in the hypersaline sediments of Orca Basin in the northern Gulf of Mexico. Substantial concentrations of methane, up to 3.4 mM, coexisted with high concentrations of sulfate from 16 to 43 mM in two sediment cores retrieved from the northern and southern parts of Orca Basin. The strong depletion of 13C in methane (-77‰ to -89‰) points towards a biological source. While low concentrations of competitive substrates limited the significance of hydrogenotrophic and acetoclastic methanogenesis, the presence of non-competitive methylated substrates (methanol, trimethylamine, dimethyl sulfide, dimethylsulfoniopropionate) supported the potential for methane generation through methylotrophic methanogenesis. Thermodynamic calculations demonstrated that hydrogenotrophic and acetoclastic methanogenesis were unlikely to occur under in situ conditions, while methylotrophic methanogenesis from a variety of substrates was highly favorable. Likewise, carbon isotope relationships between methylated substrates and methane suggested methylotrophic methanogenesis was the major source of methane. Stable and radio-isotope tracer experiments with 13C-labeled bicarbonate, acetate and methanol and 14C-labeled methylamine indicated that methylotrophic methanogenesis was the predominant methanogenic pathway. Based on 16S rRNA gene sequences, halophilic methylotrophic methanogens related to the genus Methanohalophilus dominated the benthic archaeal community in the northern basin and also occurred in the southern basin. High abundances of methanogen lipid biomarkers such as intact polar and polyunsaturated hydroxyarchaeols were detected in sediments from the northern basin, with lower abundances in the southern basin. Strong 13C-depletion of saturated and monounsaturated hydroxyarchaeol were consistent with methylotrophic methanogenesis as the major methanogenic pathway. Collectively, the availability of methylated substrates, thermodynamic calculations, experimentally determined methanogenic activity as well as lipid and gene biomarkers support the hypothesis that methylotrophic methanogenesis is the predominant pathway of methane formation in the presence of sulfate in Orca Basin sediments.

Leachate Concentrations of Ammonium, Nitrate, and Phosphorus as Affected by Nutrient Release from Four Different Types of Controlled-Release Fertilizers and Crop Development of Containerized Waxleaf Privet.

USDA-ARS?s Scientific Manuscript database

Concentrations of ammonium, nitrate, and phosphorus in irrigation leachate were measured weekly over a 47-week period from a high-fertility, neutral-pH substrate into which four types of 12-month controlled-release fertilizers (Osmocote, Nutricote, Polyon, or Multicote) were incorporated. Containers...

Graphene oxide-Ag nanoparticles-pyramidal silicon hybrid system for homogeneous, long-term stable and sensitive SERS activity

NASA Astrophysics Data System (ADS)

Guo, Jia; Xu, Shicai; Liu, Xiaoyun; Li, Zhe; Hu, Litao; Li, Zhen; Chen, Peixi; Ma, Yong; Jiang, Shouzhen; Ning, Tingyin

2017-02-01

In our work, few layers graphene oxide (GO) were directly synthesized on Ag nanoparticles (AgNPs) by spin-coating method to fabricate a GO-AgNPs hybrid structure on a pyramidal silicon (PSi) substrate for surface-enhanced Raman scattering (SERS). The GO-AgNPs-PSi substrate showed excellent Raman enhancement effect, the minimum detected concentration for Rhodamine 6G (R6G) can reach 10-12 M, which is one order of magnitude lower than the AgNPs-PSi substrate and two order of magnitude lower than the GO-AgNPs-flat-Si substrate. The linear fit calibration curve with error bars is presented and the value of R2 of 612 and 773 cm-1 can reach 0.986 and 0.980, respectively. The excellent linear response between the Raman intensity and R6G concentrations prove that the prepared GO-AgNPs-PSi substrates can serve as good SERS substrate for molecule detection. The maximum deviations of SERS intensities from 20 positions of the GO-AgNPs-PSi substrate are less than 8%, revealing the high homogeneity of the SERS substrate. The excellent homogeneity of the enhanced Raman signals can be attributed to well-separated pyramid arrays of PSi, the uniform morphology of AgNPs and multi-functions of GO layer. Besides, the uniform GO film can effectively protect AgNPs from oxidation and endow the hybrid system a good stability and long lifetime. This GO-AgNPs-PSi substrate may provide a new way toward practical applications for the ultrasensitive and label-free SERS detection in areas of medicine, food safety and biotechnology.

A Four-Hour Yeast Bioassay for the Direct Measure of Estrogenic Activity in Wastewater without Sample Extraction, Concentration, or Sterilization

PubMed Central

Balsiger, Heather A.; de la Torre, Roberto; Lee, Wen-Yee; Cox, Marc B.

2010-01-01

The assay described here represents an improved yeast bioassay that provides a rapid yet sensitive screening method for EDCs with very little hands-on time and without the need for sample preparation. Traditional receptor-mediated reporter assays in yeast were performed twelve to twenty four hours after ligand addition, used colorimetric substrates, and, in many cases, required high, non-physiological concentrations of ligand. With the advent of new chemiluminescent substrates a ligand-induced signal can be detected within thirty minutes using high picomolar to low nanomolar concentrations of estrogen. As a result of the sensitivity (EC50 for estradiol is ~ 0.7 nM) and the very short assay time (2-4 hours) environmental water samples can typically be assayed directly without sterilization, extraction, and concentration. Thus, these assays represent rapid and sensitive approaches for determining the presence of contaminants in environmental samples. As proof of principle, we directly assayed wastewater influent and effluent taken from a wastewater treatment plant in the El Paso, TX area for the presence of estrogenic activity. The data obtained in the four-hour yeast bioassay directly correlated with GC-mass spectrometry analysis of these same water samples. PMID:20074779

Effect of citric acid on metals mobility in pruning wastes and biosolids compost and metals uptake in Atriplex halimus and Rosmarinus officinalis.

PubMed

Tapia, Y; Eymar, E; Gárate, A; Masaguer, A

2013-05-01

To assess metal mobility in pruning waste and biosolids compost (pH 6.9 and total concentration of metals in milligram per kilogram of Cd 1.9, Cu 132, Fe 8,513, Mn 192, Pb 81, and Zn 313), shrubs species Atriplex halimus and Rosmarinus officinalis were transplanted in this substrate and irrigated with citric acid (4 g L(-1), pH 2.9) and nutrient solution daily for 60 days. Citric acid significantly increased the concentrations of soluble Mn and Fe in the nutrient substrate solution measured by suction probes, while other metals did not vary in concentration (Cu and Zn) or were not observed at detectable levels (Cd and Pb). In plants, citric acid significantly increased the concentrations of Cu (2.7 ± 0.1-3.3 ± 0.1 mg kg(-1)), Fe (49.2 ± 5.2-76.8 ± 6.8 mg kg(-1)), and Mn (7.2 ± 1.1-11.4 ± 0.7 mg kg(-1)) in leaves of R. officinalis, whereas the concentration of only Mn (25.4 ± 0.3-42.2 ± 2.9 mg kg(-1)) was increased in A. halimus. Increasing Fe and Mn solubility by citric acid addition indicates the possibility of using it to improve plant nutrition. The mobility of metals in this substrate was influenced for the concentration of the metal, the degree of humification of organic matter and its high Fe content.

Magneto-optic evaluation of antiferromagnetic α-Fe2O3 nanoparticles coated on a quartz substrate

NASA Astrophysics Data System (ADS)

Balasubramanian, Srinath; Panmand, Rajendra; Kumar, Ganapathy; Mahajan, Satish M.; Kale, Bharat B.

2016-03-01

This paper presents a prima facie study of the magneto-optic response of antiferromagnetic α-Fe2O3 nanoparticles coated on a quartz substrate investigated by MOKE. The concentrations of the iron oxide nanoparticles in the films were varied from 8.6% to 21.5% and showed a linear increase in film thicknesses. As the concentration of the iron oxide nanoparticles were increased, the samples changed from a net-like morphology to a crystalline morphology. Magnetization reversals in the lower concentration samples were asymmetric with the reversals for the ascending and descending branch of the hysteresis loop occurring on the same side. The asymmetry in the magnetization reversal was attributed to the angle between the antiferromagnetic easy axis and the external magnetic field. With increase in concentration, an improvement in the magneto-optic response was observed with the magnetization reversal occurring via coherent rotation for both ascending and descending branches of the hysteresis loop. The changes in the magneto-optic behavior for the samples with higher concentrations is attributed to the strong exchange interactions and changes in the shape of the nanoparticles. Sensitivity studies performed on the samples showed an increased magneto-optic sensitivity to changes in magnetic field for samples of higher concentration. The high sensitivity of these samples could be exploited in magneto-optic sensors. Nanoparticles on a quartz substrate could find applications in bio-medicine due to their bio-compatibility.

Functional expression and characterization of the Trypanosoma brucei procyclic glucose transporter, THT2.

PubMed

Barrett, M P; Tetaud, E; Seyfang, A; Bringaud, F; Baltz, T

1995-12-15

The gene encoding THT2, one of two hexose-transporter isoforms present in Trypanosoma brucei, has been expressed in both Xenopus laevis oocytes and a stably transfected line of Chinese hamster ovary (CHO) cells. The heterologously expressed gene encodes a protein with pharmacological and kinetic parameters similar to those of the hexose transporter measured in procyclic-culture-form trypanosomes. The substrate recognition of the THT2 transporter differed from that of the THT1 isoform, which is expressed only in bloodstream forms, in that: (i) it has a relatively high affinity for substrate with a Km of 59 microM for 2-deoxy-D-glucose (2-DOG) and a similar high affinity for D-glucose (compared with Km of 0.5 mM for 2-DOG in bloodstream forms); (ii) the affinity for 6-deoxy-D-glucose (6-DOG) is two orders of magnitude lower than that for D-glucose, whereas the bloodstream-form transporter recognizes D-glucose and its 6-DOG analogue with similar affinity; (iii) the bloodstream-form transporter, but not THT2, recognizes 3-fluoro-3-deoxy-D-glucose. D-Fructose-transport capacity and insensitivity to D-galactose was also found in THT2-expressing CHO cells and procyclic trypanosomes. We conclude from these cumulative results that the THT2 gene encodes the transporter responsible for hexose transport in procyclic trypanosomes. The transport of 2-DOG in procyclic organisms was inhibited by both the protonophore, carbonyl cyanide 4-trifluoromethoxy phenylhydrazone (FCCP), and KCN, suggesting a requirement for a protonmotive force. However, sensitivity to these reagents depended on the external substrate concentration, with uptake being unaffected at substrate concentrations higher than 2 mM. THT2 expressed in CHO cells behaved as a facilitated transporter, and was unaffected by FCCP or KCN over the whole substrate concentration range tested.

Kinetic study of alkaline protease 894 for the hydrolysis of the pearl oyster Pinctada martensii

NASA Astrophysics Data System (ADS)

Chen, Xin; Chen, Hua; Cai, Bingna; Liu, Qingqin; Sun, Huili

2013-05-01

A new enzyme (alkaline protease 894) obtained from the marine extremophile Flavobacterium yellowsea (YS-80-122) has exhibited strong substrate-binding and catalytic activity, even at low temperature, but the characteristics of the hydrolysis with this enzyme are still unclear. The pearl oyster Pinctada martensii was used in this study as the raw material to illustrate the kinetic properties of protease 894. After investigating the intrinsic relationship between the degree of hydrolysis and several factors, including initial reaction pH, temperature, substrate concentration, enzyme concentration, and hydrolysis time, the kinetics model was established. This study showed that the optimal conditions for the enzymatic hydrolysis were an initial reaction pH of 5.0, temperature of 30°C, substrate concentration of 10% (w/v), enzyme concentration of 2 500 U/g, and hydrolysis time of 160 min. The kinetic characteristics of the protease for the hydrolysis of P. martensii were obtained. The inactivation constant was found to be 15.16/min, and the average relative error between the derived kinetics model and the actual measurement was only 3.04%, which indicated a high degree of fitness. Therefore, this study provides a basis for the investigation of the concrete kinetic characteristics of the new protease, which has potential applications in the food industry.

Comparative research on phosphorus removal by pilot-scale vertical flow constructed wetlands using steel slag and modified steel slag as substrates.

PubMed

Yun, Yupan; Zhou, Xiaoqin; Li, Zifu; Uddin, Sayed Mohammad Nazim; Bai, Xiaofeng

2015-01-01

This research mainly focused on the phosphorus removal performance of pilot-scale vertical flow constructed wetlands with steel slag (SS) and modified steel slag (MSS). First, bench-scale experiments were conducted to evaluate the phosphorus adsorption capacity. Results showed that the Langmuir model could better describe the adsorption characteristics of the two materials; the maximum adsorption of MSS reached 12.7 mg/g, increasing by 34% compared to SS (9.5 mg/g). Moreover, pilot-scale constructed wetlands with SS and MSS were set up outdoors. Then, the influence of hydraulic retention time (HRT) and phosphorus concentration in phosphorus removal for two wetlands were investigated. Results revealed that better performance of the two systems could be achieved with an HRT of 2 d and phosphorus concentration in the range of 3-4.5 mg/L; the system with MSS had a better removal efficiency than the one with SS in the same control operation. Finally, the study implied that MSS could be used as a promising substrate for wetlands to treat wastewater with a high phosphorus concentration. However, considering energy consumption, SS could be regarded as a better alternative for substrate when treating sewage with a low phosphorus concentration.

Direct Deposition of Metal (DDM) as a Repair Process for Metallic Military Parts

DTIC Science & Technology

2013-01-20

metal powder has properties metallurgically compatible with the substrate material. As the laser beam advances along a predefined tool path in a layer...Methodology Background During the DDM process, the energy of a high power industrial laser beam and a concentric stream of metallic alloy powder ...compatible with the substrate material. As the laser beam advances along a predefined tool path in a layer by layer fashion, metal powder is deposited

Cytochrome P450 3A4 in vivo ketoconazole competitive inhibition: determination of Ki and dangers associated with high clearance drugs in general.

PubMed

Boxenbaum, H

1999-01-01

Assuming complete hepatic substrate metabolism and system linearity, quantitative effects of in vivo competitive inhibition are investigated. Following oral administration of a substrate in the presence of a competitive inhibitor, determination of the inhibition constant (Ki) is possible when plasma concentration-time profiles of both substrate and inhibitor are available. When triazolam is the P450 3A4 substrate and ketoconazole the competitive inhibitor, Ki approximately 1.2 microg/mL in humans. The effects of competitive inhibition can be divided into two components: first-pass hepatic metabolism and systemic metabolism. For drugs with high hepatic extraction ratios, the impact of competitive inhibition on hepatic first-pass metabolism can be particularly dramatic. For example, human terfenadine hepatic extraction goes from 95% in the absence of a competitive inhibitor to 35% in the presence of one (ketoconazole, 200 mg po Q 12 h dosed to steady-state). First-pass extraction therefore goes from 5% in the absence of the inhibitor to 65% in its presence. The combined effect on first-pass and systemic metabolism produces an approximate 37 fold increase in terfenadine area under the plasma concentration-time curve. Assuming intact drug is active and/or toxic, development of metabolized drugs with extensive first-pass metabolism should be avoided if possible, since inhibition of metabolism may lead to profound increases in exposure.

Silicon insulator-based dielectrophoresis devices for minimized heating effects.

PubMed

Zellner, Phillip; Agah, Masoud

2012-08-01

Concentration of biological specimens that are extremely dilute in a solution is of paramount importance for their detection. Microfluidic chips based on insulator-based DEP (iDEP) have been used to selectively concentrate bacteria and viruses. iDEP biochips are currently fabricated with glass or polymer substrates to allow for high electric fields within the channels. Joule heating is a well-known problem in these substrates and can lead to decreased throughput and even device failure. In this work, we present, for the first time, highly efficient trapping and separation of particles in DC iDEP devices that are fabricated on silicon using a single-etch-step three-dimensional microfabrication process with greatly improved heat dissipation properties. Fabrication in silicon allows for greater heat dissipation for identical geometries and operating conditions. The 3D fabrication allows for higher performance at lower applied potentials. Thermal measurements were performed on both the presented silicon chips and previously published PDMS devices comprised of microposts. Trapping and separation of 1 and 2 μm polystyrene particles was demonstrated. These results demonstrate the feasibility of high-performance silicon iDEP devices for the next generation of sorting and concentration microsystems. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Co-digestion of manure and industrial waste--The effects of trace element addition.

PubMed

Nordell, Erik; Nilsson, Britt; Nilsson Påledal, Sören; Karisalmi, Kaisa; Moestedt, Jan

2016-01-01

Manure is one of the most common substrates for biogas production. Manure from dairy- and swine animals are often considered to stabilize the biogas process by contributing nutrients and trace elements needed for the biogas process. In this study two lab-scale reactors were used to evaluate the effects of trace element addition during co-digestion of manure from swine- and dairy animals with industrial waste. The substrate used contained high background concentrations of both cobalt and nickel, which are considered to be the most important trace elements. In the reactor receiving additional trace elements, the volatile fatty acids (VFA) concentration was 89% lower than in the control reactor. The lower VFA concentration contributed to a more digested digestate, and thus lower methane emissions in the subsequent storage. Also, the biogas production rate increased with 24% and the biogas production yield with 10%, both as a result of the additional trace elements at high organic loading rates. All in all, even though 50% of the feedstock consisted of manure, trace element addition resulted in multiple positive effects and a more reliable process with stable and high yield. Copyright © 2015 Elsevier Ltd. All rights reserved.

Advanced laser diagnostics for diamond deposition research

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

Kruger, C.H.; Owano, T.G.; Wahl, E.H.

Chemical Vapor Deposition (CVD) using thermal plasmas is attractive for diamond synthesis applications due to the inherently high reactant densities and throughput, but the associated high gas-phase collision rates in the boundary layer above the substrate produce steep thermal and species gradients which can drive the complex plasma chemistry away from optimal conditions. To understand and control these environments, accurate measurements of temperature and species concentrations within the reacting boundary layer are needed. This is challenging in atmospheric pressure reactors due to the highly luminous environment, steep thermal and species gradients, and small spatial scales. The applicability of degenerate four-wavemore » mixing (DFWM) as a spectroscopic probe of atmospheric pressure reacting plasmas has been investigated. This powerful, nonlinear technique has been applied to the measurement of temperature and radical species concentrations in the boundary layer of a diamond growth substrate immersed in a flowing atmospheric pressure plasma. In-situ measurements of CH and C{sub 2} radicals have been performed to determine spatially resolved profiles of vibrational temperature, rotational temperature, and species concentration. Results of these measurements are compared with the predictions of a detailed numerical simulation.« less

Photoluminescence of Er-doped silicon-rich oxide thin films with high Al concentrations

NASA Astrophysics Data System (ADS)

Rozo, Carlos; Fonseca, Luis F.; Jaque, Daniel; García Solé, José

Er-doped silicon-rich oxide (SRO) thin films co-doped with Al in high concentrations were prepared by sputtering. Some films were deposited using a substrate heater (150 °C

Kinetics of N-Utilization By Natural Phytoplankton Assemblages During Upwelling Events At The NW Iberian Shelf

NASA Astrophysics Data System (ADS)

Brion, N.; Elskens, M.; Dehairs, F.; Baeyens, W.

2003-04-01

The concentration-dependent uptakes of nitrate, ammonium and the effect of ammo-nium on the f-ratio were surveyed in surface waters of the NW Iberian shelf during June 1997, July 1998 and September 1999. Because relationships between rates and substrate concentrations were quite variable, ranging from linear to convex shaped curves, they were fitted to rational functions. Stepwize regression analysis yielded subsequent model equations with reasonable statistical properties which allowed describing all but all a few cases. Differentiating these equations with respect to the concentration gave the slope of the tangent to the curve, i.e., the variation in rate expected for a given perturbation of the ambient substrate concentration. The initial slope value was then used as an index to gauge the "affinity" of the plankton community for the nitrogen substrate utilization. In June 1997, the situation at the Iberian shelf showed no upwelling except near Cape Finistère. Overall, the phytoplankton community displayed a high "affinity" for both nitrate and ammonium and low f-ratio values, which is indicative of a re-generated production regime. High ammonium regeneration rates supported furthermore these observations. It was also demonstrated that the new production rates is only marginally sensitive to changes of the ambient nitrate and/or ammonium concentrations. This indicates that the production regime is rather stable throughout. Only at Cape Finistère, nitrate concentrations were high reflecting the onset of an upwelling event. In this zone, the phytoplankton community, taking advantage of its high affinity for nitrate enhanced both total N-uptake rate and f-ratio. In July 1998, the situation evolved towards an extension to the south of the upwelling event starting at Cape Finistère. In this southern zone of the upwelling the phytoplankton community displayed generally a lower affinity for nitrate (but not for ammonium) than in 1997. In spite of this lower affinity, nitrate uptake rate was dominant resulting in f-ratio values greater than 0.5, a characteristic of a new production regime. The new production rate is only marginally sensitive to increases of the ambient nitrate, but is drastically inhibited by small increases of the ambient ammonium. The situation of September 1999 was very close to that observed in July 1998, with higher nitrate concentrations in the coastal northern part of the sampling area dominated by upwelling.

Optical characterization of nanoporous AAO sensor substrate

NASA Astrophysics Data System (ADS)

Kassu, Aschalew; Farley, Carlton W.; Sharma, Anup

2014-05-01

Nanoporous anodic aluminum oxide (AAO) has been investigated as an ideal and cost-effective chemical and biosensing platform. In this paper, we report the optical properties of periodic 100 micron thick nanoporous anodic alumina membranes with uniform and high density cylindrical pores penetrating the entire thickness of the substrate, ranging in size from 18 nm to 150 nm in diameter and pore periods from 44 nm to 243 nm. The surface geometry of the top and bottom surface of each membrane is studied using atomic force microscopy. The optical properties including transmittance, reflectance, and absorbance spectra on both sides of each substrate are studied and found to be symmetrical. It is observed that, as the pore size increases, the peak resonance intensity in transmittance decreases and in absorbance increases. The effects of the pore sizes on the optical properties of the bare nanoporous membranes and the benefit of using arrays of nanohole arrays with varying hole size and periodicity as a chemical sensing platform is also discussed. To characterize the optical sensing technique, transmittance and reflectance measurements of various concentrations of a standard chemical adsorbed on the bare nanoporous substrates are investigated. The preliminary results presented here show variation in transmittance and reflectance spectra with the concentration of the chemical used or the amount of the material adsorbed on the surface of the substrate.

BaSi2 formation mechanism in thermally evaporated films and its application to reducing oxygen impurity concentration

NASA Astrophysics Data System (ADS)

Hara, Kosuke O.; Yamamoto, Chiaya; Yamanaka, Junji; Arimoto, Keisuke; Nakagawa, Kiyokazu; Usami, Noritaka

2018-04-01

Thermal evaporation is a simple and rapid method to fabricate semiconducting BaSi2 films. In this study, to elucidate the BaSi2 formation mechanism, the microstructure of a BaSi2 epitaxial film fabricated by thermal evaporation has been investigated by transmission electron microscopy. The BaSi2 film is found to consist of three layers with different microstructural characteristics, which is well explained by assuming two stages of film deposition. In the first stage, BaSi2 forms through the diffusion of Ba atoms from the deposited Ba-rich film to the Si substrate while in the second stage, the mutual diffusion of Ba and Si atoms in the film leads to BaSi2 formation. On the basis of the BaSi2 formation mechanism, two issues are addressed. One is the as-yet unclarified reason for epitaxial growth. It is found important to quickly form BaSi2 in the first stage for the epitaxial growth of upper layers. The other issue is the high oxygen concentration in BaSi2 films around the BaSi2-Si interface. Two routes of oxygen incorporation, i.e., oxidation of the Si substrate surface and initially deposited Ba-rich layer by the residual gas, are identified. On the basis of this knowledge, oxygen concentration is decreased by reducing the holding time of the substrate at high temperatures and by premelting of the source. In addition, X-ray diffraction results show that the decrease in oxygen concentration can lead to an increased proportion of a-axis-oriented grains.

Heterobimetallic catalysis in asymmetric 1,4-addition of O-alkylhydroxylamine to enones.

PubMed

Yamagiwa, Noriyuki; Matsunaga, Shigeki; Shibasaki, Masakatsu

2003-12-31

A heterobimetallic YLi3tris(binaphthoxide) catalyst (YLB) promoted a 1,4-addition of O-methylhydroxylamine in high enantiomeric excess (up to 97% ee). Catalyst loading was reduced to as little as 0.5 mol %, still affording the 1,4-adduct in 96% yield and 96% ee. A high concentration of substrates and the scalability of the present system is also practically useful. The results suggested that the heterobimetallic catalysis was not deactivated even in the presence of excess amine under highly concentrated conditions. A Y and Li bimetallic cooperative function was essential for a high catalyst turnover number.

Effects of substrate heating and vacuum annealing on optical and electrical properties of alumina-doped ZnO films deposited by DC magnetron sputtering

NASA Astrophysics Data System (ADS)

Tang, Chien-Jen; Wang, Chun-Yuan; Jaing, Cheng-Chung

2011-10-01

Alumina-doped zinc oxide (AZO) films have wide range of applications in optical and optoelectronic devices. AZO films have advantage in high transparency, high stability to hydrogen plasma and low cost to alternative ITO film. AZO film was prepared by direct-current (DC) magnetron sputtering from ceramic ZnO:Al2O3 target. The AZO films were compared in two different conditions. The first is substrate heating process, in which AZO film was deposited by different substrate temperature, room temperature, 150 °C and 250 °C. The second is vacuum annealing process, in which AZO film with deposited at room temperature have been annealed at 250 °C and 450 °C in vacuum. The optical properties, electrical properties, grain size and surface structure properties of the films were studied by UV-VIS-NIR spectrophotometer, Hall effect measurement equipment, x-ray diffraction, and scanning electron microscopy. The resistivity, carrier mobility, carrier concentration, and grain size of AZO films were 1.92×10-3 Ω-cm, 6.38 cm2/Vs, 5.08×1020 #/cm3, and 31.48 nm respectively, in vacuum annealing of 450 °C. The resistivity, carrier mobility, carrier concentration, and grain size of AZO films were 8.72×10-4 Ω-cm, 6.32 cm2/Vs, 1.13×1021 #/cm3, and 31.56 nm, respectively, when substrate temperature was at 250 °C. Substrate heating process is better than vacuum annealed process for AZO film deposited by DC Magnetron Sputtering.

Cadmium (II) removal mechanisms in microbial electrolysis cells.

PubMed

Colantonio, Natalie; Kim, Younggy

2016-07-05

Cadmium is a toxic heavy metal, causing serious environmental and human health problems. Conventional methods for removing cadmium from wastewater are expensive and inefficient for low concentrations. Microbial electrolysis cells (MECs) can simultaneously treat wastewater, produce hydrogen gas, and remove heavy metals with low energy requirements. Lab-scale MECs were operated to remove cadmium under various electric conditions: applied voltages of 0.4, 0.6, 0.8, and 1.0 V; and a fixed cathode potential of -1.0 V vs. Ag/AgCl. Regardless of the electric condition, rapid removal of cadmium was demonstrated (50-67% in 24 h); however, cadmium concentration in solution increased after the electric current dropped with depleted organic substrate under applied voltage conditions. For the fixed cathode potential, the electric current was maintained even after substrate depletion and thus cadmium concentration did not increase. These results can be explained by three different removal mechanisms: cathodic reduction; Cd(OH)2 precipitation; and CdCO3 precipitation. When the current decreased with depleted substrates, local pH at the cathode was no longer high due to slowed hydrogen evolution reaction (2H(+)+2e(-)→H2); thus, the precipitated Cd(OH)2 and CdCO3 started dissolving. To prevent their dissolution, sufficient organic substrates should be provided when MECs are used for cadmium removal. Copyright © 2016 Elsevier B.V. All rights reserved.

Similarities and differences in the biochemical and enzymological properties of the four isomaltases from Saccharomyces cerevisiae

PubMed Central

Deng, Xu; Petitjean, Marjorie; Teste, Marie-Ange; Kooli, Wafa; Tranier, Samuel; François, Jean Marie; Parrou, Jean-Luc

2014-01-01

The yeast Saccharomyces cerevisiae IMA multigene family encodes four isomaltases sharing high sequence identity from 65% to 99%. Here, we explore their functional diversity, with exhaustive in-vitro characterization of their enzymological and biochemical properties. The four isoenzymes exhibited a preference for the α-(1,6) disaccharides isomaltose and palatinose, with Michaëlis–Menten kinetics and inhibition at high substrates concentration. They were also able to hydrolyze trisaccharides bearing an α-(1,6) linkage, but also α-(1,2), α-(1,3) and α-(1,5) disaccharides including sucrose, highlighting their substrate ambiguity. While Ima1p and Ima2p presented almost identical characteristics, our results nevertheless showed many singularities within this protein family. In particular, Ima3p presented lower activities and thermostability than Ima2p despite only three different amino acids between the sequences of these two isoforms. The Ima3p_R279Q variant recovered activity levels of Ima2p, while the Leu-to-Pro substitution at position 240 significantly increased the stability of Ima3p and supported the role of prolines in thermostability. The most distant protein, Ima5p, presented the lowest optimal temperature and was also extremely sensitive to temperature. Isomaltose hydrolysis by Ima5p challenged previous conclusions about the requirement of specific amino acids for determining the specificity for α-(1,6) substrates. We finally found a mixed inhibition by maltose for Ima5p while, contrary to a previous work, Ima1p inhibition by maltose was competitive at very low isomaltose concentrations and uncompetitive as the substrate concentration increased. Altogether, this work illustrates that a gene family encoding proteins with strong sequence similarities can lead to enzyme with notable differences in biochemical and enzymological properties. PMID:24649402

Similarities and differences in the biochemical and enzymological properties of the four isomaltases from Saccharomyces cerevisiae.

PubMed

Deng, Xu; Petitjean, Marjorie; Teste, Marie-Ange; Kooli, Wafa; Tranier, Samuel; François, Jean Marie; Parrou, Jean-Luc

2014-01-01

The yeast Saccharomyces cerevisiae IMA multigene family encodes four isomaltases sharing high sequence identity from 65% to 99%. Here, we explore their functional diversity, with exhaustive in-vitro characterization of their enzymological and biochemical properties. The four isoenzymes exhibited a preference for the α-(1,6) disaccharides isomaltose and palatinose, with Michaëlis-Menten kinetics and inhibition at high substrates concentration. They were also able to hydrolyze trisaccharides bearing an α-(1,6) linkage, but also α-(1,2), α-(1,3) and α-(1,5) disaccharides including sucrose, highlighting their substrate ambiguity. While Ima1p and Ima2p presented almost identical characteristics, our results nevertheless showed many singularities within this protein family. In particular, Ima3p presented lower activities and thermostability than Ima2p despite only three different amino acids between the sequences of these two isoforms. The Ima3p_R279Q variant recovered activity levels of Ima2p, while the Leu-to-Pro substitution at position 240 significantly increased the stability of Ima3p and supported the role of prolines in thermostability. The most distant protein, Ima5p, presented the lowest optimal temperature and was also extremely sensitive to temperature. Isomaltose hydrolysis by Ima5p challenged previous conclusions about the requirement of specific amino acids for determining the specificity for α-(1,6) substrates. We finally found a mixed inhibition by maltose for Ima5p while, contrary to a previous work, Ima1p inhibition by maltose was competitive at very low isomaltose concentrations and uncompetitive as the substrate concentration increased. Altogether, this work illustrates that a gene family encoding proteins with strong sequence similarities can lead to enzyme with notable differences in biochemical and enzymological properties.

The Catalytic Function of Enzymes.

ERIC Educational Resources Information Center

Splittgerber, Allan G.

1985-01-01

Discusses: structure of the enzyme molecule; active site; reaction mechanism; transition state; factors affecting enzyme reaction rates, concentration of enzyme; concentration of substrate; product concentration; temperature effects and pH effects; factors causing a lowering of activation energy; proximity and orientation effects; substrate strain…

Design and development of green roof substrate to improve runoff water quality: plant growth experiments and adsorption.

PubMed

Vijayaraghavan, K; Raja, Franklin D

2014-10-15

Many studies worldwide have investigated the potential benefits achievable by transforming brown roofs of buildings to green roofs. However, little literature examined the runoff quality/sorption ability of green roofs. As the green roof substrate is the main component to alter the quality of runoff, this investigation raises the possibility of using a mixture of low-cost inorganic materials to develop a green roof substrate. The tested materials include exfoliated vermiculite, expanded perlite, crushed brick and sand along with organic component (coco-peat). Detailed physical and chemical analyses revealed that each of these materials possesses different characteristics and hence a mix of these materials was desirable to develop an optimal green roof substrate. Using factorial design, 18 different substrate mixes were prepared and detailed examination indicated that mix-12 exhibited desirable characteristics of green roof substrate with low bulk density (431 kg/m(3)), high water holding capacity (39.4%), air filled porosity (19.5%), and hydraulic conductivity (4570 mm/h). The substrate mix also provided maximum support to Portulaca grandiflora (380% total biomass increment) over one month of growth. To explore the leaching characteristics and sorption capacity of developed green roof substrate, a down-flow packed column arrangement was employed. High conductivity and total dissolved solids along with light metal ions (Na, K, Ca and Mg) were observed in the leachates during initial stages of column operation; however the concentration of ions ceased during the final stages of operation (600 min). Experiments with metal-spiked deionized water revealed that green roof substrate possess high sorption capacity towards various heavy metal ions (Al, Fe, Cr, Cu, Ni, Pb, Zn and Cd). Thus the developed growth substrate possesses desirable characteristics for green roofs along with high sorption capacity. Copyright © 2014 Elsevier Ltd. All rights reserved.

Influence of ionic strength and surfactant concentration on electrostatic surfacial assembly of cetyltrimethylammonium bromide-capped gold nanorods on fully immersed glass.

PubMed

Ferhan, Abdul Rahim; Guo, Longhua; Kim, Dong-Hwan

2010-07-20

The effect of ionic strength as well as surfactant concentration on the surface assembly of cetyltrimethylammonium bromide (CTAB)-capped gold nanorods (GNRs) has been studied. Glass substrates were modified to yield a net negative charge through electrostatic coating of polystyrenesulfonate (PSS) over a self-assembled monolayer (SAM) of positively charged aminopropyltriethoxysilane (APTS). The substrates were then fully immersed in GNR solutions at different CTAB concentrations and ionic strengths. Under slightly excess CTAB concentrations, it was observed that the density of GNRs immobilized on a substrate was predictably tunable through the adjustment of NaCl concentration over a wide range. Motivated by the experimental observation, we hypothesize that electrostatic shielding of charges around the GNRs affects the density of GNR immobilization. This model ultimately explains that at moderate to high CTAB concentrations a second electrostatic shielding effect contributed by excess CTAB molecules occurs, resulting in a parabolic trend of nanorod surface density when ionic strength is continually increased. In contrast, at a low CTAB concentration, the effect of ionic strength becomes much less significant due to insufficient CTAB molecules to provide for the second electrostatic shielding effect. The tunability of electrostatic-based surface assembly of GNRs enables the attainment of a dense surface assembly of nanorods without significant removal of CTAB or any other substituted stabilizing agent, both of which could compromise the stability and morphology of GNRs in solution. An additional study performed to investigate the robustness of such electrostatic-based surface assembly also proved its reliability to be used as biosensing platforms.

Potential role for human P-glycoprotein in the transport of lacosamide.

PubMed

Zhang, Chunbo; Chanteux, Hugues; Zuo, Zhong; Kwan, Patrick; Baum, Larry

2013-07-01

Antiepileptic drugs (AEDs) do not effectively treat 30-40% of patients with epilepsy. Export of AEDs by P-glycoprotein (Pgp, ABCB1, or MDR1), which is overexpressed in the blood-brain barrier in drug-resistant patients, may be a mechanism for resistance to AEDs. For most recently approved AEDs, whether they are transported by Pgp is unknown. We investigated whether a new AED, lacosamide (LCM), is a substrate of human Pgp. LLC-PK1 and MDCKII cells transfected with the human MDR1 gene were used to determine the substrate status of LCM in concentration equilibrium transport assays (CETAs). An equal concentration of drug was initially loaded in both the apical and basal chambers, and the concentration in both chambers was measured up to 4 h. The experiments were repeated in the presence of the Pgp inhibitors verapamil and tariquidar. Caco-2 assays were used to determine the intrinsic permeability and efflux ratio of LCM as well as its potential to inhibit digoxin, a Pgp substrate. Lacosamide was transported by MDR1-transfected cells from basolateral to apical sides. The efflux of LCM could be completely blocked by verapamil or tariquidar. In Caco-2 assays, LCM showed high permeability without a significant efflux ratio; it did not inhibit digoxin, a Pgp substrate. Although LCM is a substrate of Pgp in CETA, Caco-2 data demonstrated that passive diffusion should play a major role in the overall disposition of LCM. The critical role of Pgp should be addressed in vivo. Wiley Periodicals, Inc. © 2013 International League Against Epilepsy.

Biogeochemical response of organic-rich freshwater marshes in the Louisiana delta plain to chronic river water influx

USGS Publications Warehouse

Swarzenski, C.M.; Doyle, T.W.; Fry, B.; Hargis, T.G.

2008-01-01

To help evaluate effects of Mississippi River inputs to sustainability of coastal Louisiana ecosystems, we compared porewater and substrate quality of organic-rich Panicum hemitomon freshwater marshes inundated by river water annually for more than 30 years (Penchant basin, PB) or not during the same time (Barataria basin, BB). In the marshes receiving river water the soil environment was more reduced, the organic substrate was more decomposed and accumulated more sulfur. The porewater dissolved ammonium and orthophosphate concentrations were an order of magnitude higher and sulfide and alkalinity concentrations were more than twice as high in PB compared with BB marshes. The pH was higher and dissolved iron concentrations were more than an order of magnitude lower in PB marshes than in BB marshes. The influx of nutrient-rich river water did not enhance end-of-year above-ground standing biomass or vertical accretion rates of the shallow substrate. The differences in porewater chemistry and substrate quality are reasonably linked to the long-term influx of river water through biogeochemical processes and transformations involving alkalinity, nitrate and sulfate. The key factor is the continual replenishment of alkalinity, nitrate and sulfate via overland flow during high river stage each year for several weeks to more than 6 months. This leads to a reducing soil environment, pooling of the phytotoxin sulfide and inorganic nutrients in porewater, and internally generated alkalinity. Organic matter decomposition is enhanced under these conditions and root mats degraded. The more decomposed root mat makes these marshes more susceptible to erosion during infrequent high-energy events (for example hurricanes) and regular low-energy events, such as tides and the passage of weather fronts. Our findings were unexpected and, if generally applicable, suggest that river diversions may not be the beneficial mitigating agent of wetland restoration and conservation that they are anticipated to be. ?? 2008 Springer Science+Business Media B.V.

UO(2) 2+ speciation determines uranium toxicity and bioaccumulation in an environmental Pseudomonas sp. isolate.

PubMed

Vanengelen, Michael R; Field, Erin K; Gerlach, Robin; Lee, Brady D; Apel, William A; Peyton, Brent M

2010-04-01

In the present study, experiments were performed to investigate how representative cellulosic breakdown products, when serving as growth substrates under aerobic conditions, affect hexavalent uranyl cation (UO(2) (2+)) toxicity and bioaccumulation within a Pseudomonas sp. isolate (designated isolate A). Isolate A taken from the Cold Test Pit South (CTPS) region of the Idaho National Laboratory (INL), Idaho Falls, ID, USA. The INL houses low-level uranium-contaminated cellulosic material and understanding how this material, and specifically its breakdown products, affect U-bacterial interactions is important for understanding UO(2) (2+) fate and mobility. Toxicity was modeled using a generalized Monod expression. Butyrate, dextrose, ethanol, and lactate served as growth substrates. The potential contribution of bicarbonate species present in high concentrations was also investigated and compared with toxicity and bioaccumulation patterns seen in low-bicarbonate conditions. Isolate A was significantly more sensitive to UO(2) (2+) and accumulated significantly more UO(2) (2+) in low-bicarbonate concentrations. In addition, UO(2) (2+) growth inhibition and bioaccumulation varied depending on the growth substrate. In the presence of high bicarbonate concentrations, sensitivity to UO(2) (2+) inhibition was greatly mitigated, and did not vary between the four substrates tested. The extent of UO(2) (2+) accumulation was also diminished. The observed patterns were related to UO(2) (2+) aqueous complexation, as predicted by MINTEQ (ver. 2.52) (Easton, PA, USA). In the low- bicarbonate medium, the presence of positively charged and unstable UO(2) (2+)-hydroxide complexes explained both the greater sensitivity of isolate A to UO(2) (2+), and the ability of isolate A to accumulate significant amounts of UO(2) (2+). The exclusive presence of negatively charged and stable UO(2) (2+)-carbonate complexes in the high bi-carbonate medium explained the diminished sensitivity of isolate A to UO(2) (2+) toxicity, and limited ability of isolate A to accumulate UO(2) (2+). (c) 2010 SETAC.

Analysis of synthetic diamond single crystals by X-ray topography and double-crystal diffractometry

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

Prokhorov, I. A., E-mail: igor.prokhorov@mail.ru; Ralchenko, V. G.; Bolshakov, A. P.

2013-12-15

Structural features of diamond single crystals synthesized under high pressure and homoepitaxial films grown by chemical vapor deposition (CVD) have been analyzed by double-crystal X-ray diffractometry and topography. The conditions of a diffraction analysis of diamond crystals using Ge monochromators have been optimized. The main structural defects (dislocations, stacking faults, growth striations, second-phase inclusions, etc.) formed during crystal growth have been revealed. The nitrogen concentration in high-pressure/high-temperature (HPHT) diamond substrates is estimated based on X-ray diffraction data. The formation of dislocation bundles at the film-substrate interface in the epitaxial structures has been revealed by plane-wave topography; these dislocations are likelymore » due to the relaxation of elastic macroscopic stresses caused by the lattice mismatch between the substrate and film. The critical thicknesses of plastic relaxation onset in CVD diamond films are calculated. The experimental techniques for studying the real diamond structure in optimizing crystal-growth technology are proven to be highly efficient.« less

Complex-formation between reduced xanthine oxidase and purine substrates demonstrated by electron paramagnetic resonance

PubMed Central

Pick, Frances M.; Bray, R. C.

1969-01-01

The origin of the Rapid molybdenum electron-paramagnetic-resonance signals, which are obtained on reducing xanthine oxidase with purine or with xanthine, and whose parameters were measured by Bray & Vänngård (1969), was studied. It is concluded that these signals represent complexes of reduced enzyme with substrate molecules. Xanthine forms one complex at high concentrations and a different one at low concentrations. Purine forms a complex indistinguishable from the low-concentration xanthine complex. There are indications that some other substrates also form complexes, but uric acid, a reaction product, does not appear to do so. The possible significance of the complexes in the catalytic cycle of the enzyme is discussed and it is suggested that they represent substrate molecules bound at the reduced active site, waiting their turn to react there, when the enzyme has been reoxidized. Support for this role for the complexes was deduced from experiments in which frozen samples of enzyme–xanthine mixtures, prepared by the rapid-freezing method, were warmed until the signals began to change. Under these conditions an increase in amplitude of the Very Rapid signal took place. Data bearing on the origin of the Slow molybdenum signal are also discussed. This signal disappears only slowly in the presence of oxygen, and its appearance rate is unaffected by change in the concentration of dithionite. It is concluded that, like other signals from the enzyme, it is due to Mov but that a slow change of ligand takes place before it is seen. The Slow species, like the Rapid, seems capable of forming complexes with purines. PMID:4310056

The Effect of Sedimentation Conditions of Frozen Deposits at the Kolyma Lowland on the Distribution of Methane and Microorganisms Activity

NASA Astrophysics Data System (ADS)

Oshurkova, V.; Kholodov, A. L.; Spektor, V.; Sherbakova, V.; Rivkina, E.

2014-12-01

Biogeochemical and microbiological investigations of methane distribution and origin in Northeastern Arctic permafrost sediments indicated that microbial methane production was observed in situ in thawed and permanently frozen deposits (Rivkina et al., 2007). To check the hypothesis about the correlation between permafrost ground type and quantity of methane, produced by microorganisms, the samples from deposits of thermokarst depression (alas), Yedoma and fluvial deposits of Kolyma floodplain for gas measurements and microbiological study were collected and the experiment with anaerobic incubation was conducted. Gas analysis indicated that alas and floodplain samples were characterized by high methane concentrations whereas Yedoma samples had only traces of methane. Two media with different substrates were prepared anaerobically for incubation. First medium contained sucrose as a substrate for hydrolytic microflora and the second one contained acetate as a substrate for methanogens. Two samples from alas, one sample from Yedoma and one from floodplain were placed in anaerobic bottles and media under gas mixture (N2, CO2 and H2) were added. The bottles were incubated for 2 weeks at room temperature. The results of the experiment showed that there was the increase of methane concentrations in the bottles with Yedoma and Floodplain samples to 52-60 and 67-90 %, respectively, from initial concentrations in contrast with Alas sample inoculated bottles. At the same time the concentration of methane in control bottles, which did not include substrates, increased to 15-19%. Current research is a part of NSF funded project "The Polaris".

High-performance SERS substrate based on hybrid structure of graphene oxide/AgNPs/Cu film@pyramid Si

NASA Astrophysics Data System (ADS)

Li, Zhe; Xu, Shi Cai; Zhang, Chao; Liu, Xiao Yun; Gao, Sai Sai; Hu, Li Tao; Guo, Jia; Ma, Yong; Jiang, Shou Zhen; Si, Hai Peng

2016-12-01

We present a novel surface-enhanced Raman scattering (SERS) substrate based on graphene oxide/silver nanoparticles/copper film covered silicon pyramid arrays (GO/AgNPs/PCu@Si) by a low-cost and simple method. The GO/AgNPs/PCu@Si substrate presents high sensitivity, good homogeneity and well stability with R6G molecules as a probe. The detected concentration of Rhodamine 6 G (R6G) is as low as 10-15 M. These sensitive SERS behaviors are also confirmed in theory via a commercial COMSOL software, the electric field enhancement is not only formed between the AgNPs, but also formed between the AgNPs and Cu film. And the GO/AgNPs/PCu@Si substrates also present good property on practical application for the detection of methylene blue (MB) and crystal violet (CV). This work may offer a novel and practical method to facilitate the SERS applications in areas of medicine, food safety and biotechnology.

High-performance SERS substrate based on hybrid structure of graphene oxide/AgNPs/Cu film@pyramid Si.

PubMed

Li, Zhe; Xu, Shi Cai; Zhang, Chao; Liu, Xiao Yun; Gao, Sai Sai; Hu, Li Tao; Guo, Jia; Ma, Yong; Jiang, Shou Zhen; Si, Hai Peng

2016-12-07

We present a novel surface-enhanced Raman scattering (SERS) substrate based on graphene oxide/silver nanoparticles/copper film covered silicon pyramid arrays (GO/AgNPs/PCu@Si) by a low-cost and simple method. The GO/AgNPs/PCu@Si substrate presents high sensitivity, good homogeneity and well stability with R6G molecules as a probe. The detected concentration of Rhodamine 6 G (R6G) is as low as 10 -15 M. These sensitive SERS behaviors are also confirmed in theory via a commercial COMSOL software, the electric field enhancement is not only formed between the AgNPs, but also formed between the AgNPs and Cu film. And the GO/AgNPs/PCu@Si substrates also present good property on practical application for the detection of methylene blue (MB) and crystal violet (CV). This work may offer a novel and practical method to facilitate the SERS applications in areas of medicine, food safety and biotechnology.

High-performance SERS substrate based on hybrid structure of graphene oxide/AgNPs/Cu film@pyramid Si

PubMed Central

Li, Zhe; Xu, Shi Cai; Zhang, Chao; Liu, Xiao Yun; Gao, Sai Sai; Hu, Li Tao; Guo, Jia; Ma, Yong; Jiang, Shou Zhen; Si, Hai Peng

2016-01-01

We present a novel surface-enhanced Raman scattering (SERS) substrate based on graphene oxide/silver nanoparticles/copper film covered silicon pyramid arrays (GO/AgNPs/PCu@Si) by a low-cost and simple method. The GO/AgNPs/PCu@Si substrate presents high sensitivity, good homogeneity and well stability with R6G molecules as a probe. The detected concentration of Rhodamine 6 G (R6G) is as low as 10−15 M. These sensitive SERS behaviors are also confirmed in theory via a commercial COMSOL software, the electric field enhancement is not only formed between the AgNPs, but also formed between the AgNPs and Cu film. And the GO/AgNPs/PCu@Si substrates also present good property on practical application for the detection of methylene blue (MB) and crystal violet (CV). This work may offer a novel and practical method to facilitate the SERS applications in areas of medicine, food safety and biotechnology. PMID:27924863

A miniaturized assay for measuring small molecule phosphorylation in the presence of complex matrices.

PubMed

Spry, Christina; Saliba, Kevin J; Strauss, Erick

2014-04-15

We describe here a simple, miniaturized radiation-based phosphorylation assay that can be used to monitor phosphorylation of a diverse range of small molecule substrates in the presence of purified and crude enzyme preparations. Ba(OH)2 and ZnSO4 are used to terminate phosphoryl transfer and to precipitate selectively the phosphorylated reaction product in a single step; non-phosphorylated substrate is removed by filtration prior to quantification. The key advantages over alternative radiation-based assays are that: (i) high-energy/short-lived radioactive emitters are not required; (ii) high-quality data can be obtained without the need for high radioactivity concentrations; and (iii) the assay is compatible with high-throughput applications. Copyright © 2013 Elsevier Inc. All rights reserved.

Low-Cost, Disposable, Flexible and Highly Reproducible Screen Printed SERS Substrates for the Detection of Various Chemicals

PubMed Central

Wu, Wei; Liu, Li; Dai, Zhigao; Liu, Juhua; Yang, Shuanglei; Zhou, Li; Xiao, Xiangheng; Jiang, Changzhong; Roy, Vellaisamy A.L.

2015-01-01

Ideal SERS substrates for sensing applications should exhibit strong signal enhancement, generate a reproducible and uniform response, and should be able to fabricate in large-scale and low-cost. Herein, we demonstrate low-cost, highly sensitive, disposable and reproducible SERS substrates by means of screen printing Ag nanoparticles (NPs) on a plastic PET (Polyethylene terephthalate) substrates. While there are many complex methods for the fabrication of SERS substrates, screen printing is suitable for large-area fabrication and overcomes the uneven radial distribution. Using as-printed Ag substrates as the SERS platform, detection of various commonly known chemicals have been done. The SERS detection limit of Rhodamine 6G (R6G) is higher than the concentration of 1 × 10−10 M. The relative standard deviation (RSD) value for 784 points on the detection of R6G and Malachite green (MG) is less than 20% revealing a homogeneous SERS distribution and high reproducibility. Moreover, melamine (MA) is detected in fresh liquid-milk without additional pretreatment, which may accelerate the application of rapid on-line detection of MA in liquid milk. Our screen printing method highlights the use of large-scale printing strategies for the fabrication of well-defined functional nanostructures with applications well beyond the field of SERS sensing. PMID:25974125

Optical connections on flexible substrates

NASA Astrophysics Data System (ADS)

Bosman, Erwin; Geerinck, Peter; Christiaens, Wim; Van Steenberge, Geert; Vanfleteren, Jan; Van Daele, Peter

2006-04-01

Optical interconnections integrated on a flexible substrate combine the advantages of optical data transmissions (high bandwidth, no electromagnetic disturbance and low power consumption) and those of flexible substrates (compact, ease of assembly...). Especially the flexible character of the substrates can significantly lower the assembly cost and leads to more compact modules. Especially in automotive-, avionic-, biomedical and sensing applications there is a great potential for these flexible optical interconnections because of the increasing data-rates, increasing use of optical sensors and requirement for smaller size and weight. The research concentrates on the integration of commercially available polymer optical layers (Truemode Backplane TM Polymer, Ormocer®) on a flexible Polyimide film, the fabrication of waveguides and out-of plane deflecting 45° mirrors, the characterization of the optical losses due to the bending of the substrate, and the fabrication of a proof-of-principal demonstrator. The resulting optical structures should be compatible with the standard fabrication of flexible printed circuit boards.

Identification of dominant scattering mechanism in epitaxial graphene on SiC

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

Lin, Jingjing; Guo, Liwei, E-mail: lwguo@iphy.ac.cn, E-mail: chenx29@aphy.iphy.ac.cn; Jia, Yuping

2014-05-05

A scheme of identification of scattering mechanisms in epitaxial graphene (EG) on SiC substrate is developed and applied to three EG samples grown on SiC (0001), (112{sup ¯}0), and (101{sup ¯}0) substrates. Hall measurements combined with defect detection technique enable us to evaluate the individual contributions to the carrier scatterings by defects and by substrates. It is found that the dominant scatterings can be due to either substrate or defects, dependent on the substrate orientations. The EG on SiC (112{sup ¯}0) exhibits a better control over the two major scattering mechanisms and achieves the highest mobility even with a highmore » carrier concentration, promising for high performance graphene-based electronic devices. The method developed here will shed light on major aspects in governing carrier transport in EG to harness it effectively.« less

Surface-enhanced Raman spectroscopy with Au-nanoparticle substrate fabricated by using femtosecond pulse

NASA Astrophysics Data System (ADS)

Zhang, Wending; Li, Cheng; Gao, Kun; Lu, Fanfan; Liu, Min; Li, Xin; Zhang, Lu; Mao, Dong; Gao, Feng; Huang, Ligang; Mei, Ting; Zhao, Jianlin

2018-05-01

Au-nanoparticle (Au-NP) substrates for surface-enhanced Raman spectroscopy (SERS) were fabricated by grid-like scanning a Au-film using a femtosecond pulse. The Au-NPs were directly deposited on the Au-film surface due to the scanning process. The experimentally obtained Au-NPs presented local surface plasmon resonance effect in the visible spectral range, as verified by finite difference time domain simulations and measured reflection spectrum. The SERS experiment using the Au-NP substrates exhibited high activity and excellent substrate reproducibility and stability, and a clearly present Raman spectra of target analytes, e.g. Rhodamine-6G, Rhodamine-B and Malachite green, with concentrations down to 10‑9 M. This work presents an effective approach to producing Au-NP SERS substrates with advantages in activity, reproducibility and stability, which could be used in a wide variety of practical applications for trace amount detection.

The Influence of Pre-Heated Treatment to Improve Adhesion Bond Coating Strength of Fly Ash Based Geopolymer Ceramic

NASA Astrophysics Data System (ADS)

Jamaludin, L.; Abdullah, M. M. A. B.; Hussin, K.; Kadir, A. Abdul

2018-06-01

The study focus on effect of pre-heated ceramic surface on the adhesion bond strength between geopolymer coating coating and ceramic substrates. Ceramic substrates was pre-heated at different temperature (400 °C, 600 °C, 800 °C and 1000 °C). Fly ash geopolymer coating material potential used to protect surface used in exposure conditions after sintering at high temperature. Fly ash and alkali activator (Al2O3/Na2SiO3) were mixed with 2.0 solids-to-liquid ratios to prepare geopolymer coating material at constant NaOH concentration of 12M. Adhesion test was conducted to determine the adhesion bond between ceramic substrates and fly ash coating material. The results showed the pre-heated ceramic substrates effect the adhesion bond of coating compared with untreated substrates with increasing of strength up to 20 % for temperature 600 °C.

Surface-enhanced Raman spectroscopy with Au-nanoparticle substrate fabricated by using femtosecond pulse.

PubMed

Zhang, Wending; Li, Cheng; Gao, Kun; Lu, Fanfan; Liu, Min; Li, Xin; Zhang, Lu; Mao, Dong; Gao, Feng; Huang, Ligang; Mei, Ting; Zhao, Jianlin

2018-05-18

Au-nanoparticle (Au-NP) substrates for surface-enhanced Raman spectroscopy (SERS) were fabricated by grid-like scanning a Au-film using a femtosecond pulse. The Au-NPs were directly deposited on the Au-film surface due to the scanning process. The experimentally obtained Au-NPs presented local surface plasmon resonance effect in the visible spectral range, as verified by finite difference time domain simulations and measured reflection spectrum. The SERS experiment using the Au-NP substrates exhibited high activity and excellent substrate reproducibility and stability, and a clearly present Raman spectra of target analytes, e.g. Rhodamine-6G, Rhodamine-B and Malachite green, with concentrations down to 10 -9 M. This work presents an effective approach to producing Au-NP SERS substrates with advantages in activity, reproducibility and stability, which could be used in a wide variety of practical applications for trace amount detection.

HOG MAP kinase regulation of alternariol biosynthesis in Alternaria alternata is important for substrate colonization.

PubMed

Graf, Eva; Schmidt-Heydt, Markus; Geisen, Rolf

2012-07-16

Strains of the genus Alternaria are ubiquitously present and frequently found on fruits, vegetables and cereals. One of the most commonly found species from this genus is A. alternata which is able to produce the mycotoxin alternariol among others. To date only limited knowledge is available about the regulation of the biosynthesis of alternariol, especially under conditions relevant to food. Tomatoes are a typical substrate of A. alternata and have a high water activity. On the other hand cereals with moderate water activity are also frequently colonized by A. alternata. In the current analysis it was demonstrated that even minor changes in the osmotic status of the substrate affect the alternariol biosynthesis of strains from vegetables resulting in nearly complete inhibition. High osmolarity in the environment is usually transmitted to the transcriptional level of downstream regulated genes by the HOG signal cascade (high osmolarity glycerol cascade) which is a MAP kinase transduction pathway. The phosphorylation status of the A. alternata HOG (AaHOG) was determined. Various concentrations of NaCl induce the phosphorylation of AaHOG in a concentration, time and strain dependent manner. A strain with a genetically inactivated aahog gene was no longer able to produce alternariol indicating that the activity of the aahog gene is required for alternariol biosynthesis. Further experiments revealed that the biosynthesis of alternariol is important for the fungus to colonize tomato tissue. The tight water activity dependent regulation of alternariol biosynthesis ensures alternariol biosynthesis at conditions which indicate an optimal colonization substrate for the fungus. Copyright © 2012 Elsevier B.V. All rights reserved.

Towards field detection of polycyclic aromatic hydrocarbons (PAHs) in environment water using a self-assembled SERS sensor

NASA Astrophysics Data System (ADS)

Yan, Xia; Shi, Xiaofeng; Yang, Jie; Zhang, Xu; Jia, Wenjie; Ma, Jun

2017-10-01

A self-assembled surface enhanced Raman scattering (SERS) sensor is reported in this paper. To achieve high sensitivity, a high sensitive SERS substrate and a high efficient self-constructed light path were made. The SERS substrate was composed by gold nanoparticles (AuNPs, pH=13), glycidyl methacrylate-ethylene dimethacrylate (GMA-EDMA) porous material and syringe filter. The substrate had a good repeatability, and the relative standard deviation (RSD) of the same substrate was less than 5%. The efficiency of the self-constructed light path is about two times better than RPB Y type reflection fiber when the energy density was roughly equal on samples. The size of the SERS sensor is 350×300×180 mm and the weight is 15 kg. Its miniaturization and portable can comply with the requirements of field detection. Besides, it has good sensitivity, stability and selectivity. For lab experiments, strong enhancements of Raman scattering from organic pollutant polycyclic aromatic hydrocarbons (PAHs) molecules were exhibited. The dependences of SERS intensities on concentrations of PAHs were investigated, and the results indicated that they revealed a satisfactory linear relationship in low concentrations. The limits of detection (LODs) of PAHs phenanthrene and fluorene are 8.3×10-10 mol/L and 7.1×10-10 mol/L respectively [signal to noise ratio (S/N) =3]. Based on this SERS sensor, signals of benzo (a) pyrene and pyrene were found in environmental water and the sensor would be an ideal candidate for field detection of PAHs.

The rate of the AMP/adenosine substrate cycle in concanavalin-A-stimulated rat lymphocytes.

PubMed Central

Szondy, Z; Newsholme, E A

1989-01-01

The effect of adenosine on the metabolism of prelabelled adenine nucleotides was investigated in concanavalin-A-stimulated rat lymphocytes. Adenosine in the presence of the adenosine deaminase inhibitor, deoxycoformycin, caused a 2-fold increase in the ATP concentration. This effect was, in part, countereacted by an increased rate of adenine nucleotide catabolism, which could be explained by a stimulation of AMP deaminase (EC 3.5.4.6). At the same time a continuous rate of labelled adenosine production was found, which was not affected by the increased ATP concentration and which could only be detected by the trapping effect of a high concentration of added unlabelled adenosine. It is concluded that the rate of the substrate cycle between AMP and adenosine is low (1.9 +/- 0.2 nmol/h per 10(7) cells) in comparison to the rate of AMP deamination. PMID:2552990

Thermal bubble inkjet printing of water-based graphene oxide and graphene inks on heated substrate

NASA Astrophysics Data System (ADS)

Huang, Simin; Shen, Ruoxi; Qian, Bo; Li, Lingying; Wang, Wenhao; Lin, Guanghui; Zhang, Xiaofei; Li, Peng; Xie, Yonglin

2018-04-01

Stable-jetting water-based graphene oxide (GO) and graphene (GR) inks without any surfactant or stabilizer are prepared from an unstable-jetting water-based starting solvent, with many thermal bubble inkjet satellite drops, by simply increasing the material concentration. The concentration-dependent thermal bubble inkjet droplet generation process is studied in detail. To overcome the low concentration properties of water-based thermal bubble inkjet inks, the substrate temperature is tuned below 60 °C to achieve high-quality print lines. Due to the difference in hydrophilicity and hydrophobicity of the 2D materials, the printed GO lines show a different forming mechanism from that of the GR lines. The printed GO lines are reduced by thermal annealing and by ascorbic acid, respectively. The reduced GO lines exhibit electrical conductivity of the same order of magnitude as that of the GR lines.

Effect of Gynosaponin on Rumen In vitro Methanogenesis under Different Forage-Concentrate Ratios

PubMed Central

Manatbay, Bakhetgul; Cheng, Yanfen; Mao, Shengyong; Zhu, Weiyun

2014-01-01

The study aimed to investigate the effects of gynosaponin on in vitro methanogenesis under different forage-concentrate ratios (F:C ratios). Experiment was conducted with two kinds of F:C ratios (F:C = 7:3 and F:C = 3:7) and gynosaponin addition (0 mg and 16 mg) in a 2×2 double factorial design. In the presence of gynosaponin, methane production and acetate concentration were significantly decreased, whereas concentration of propionate tended to be increased resulting in a significant reduction (p<0.05) of acetate:propionate ratio (A:P ratio), in high-forage substrate. Gynosaponin treatment increased (p<0.05) the butyrate concentration in both F:C ratios. Denaturing gradient gel electrophoresis (DGGE) analysis showed there was no apparent shift in the composition of total bacteria, protozoa and methanogens after treated by gynosaponin under both F:C ratios. The real-time polymerase chain reaction (PCR) analysis indicated that variable F:C ratios significantly affected the abundances of Fibrobacter succinogenes, Rumninococcus flavefaciens, total fungi and counts of protozoa (p<0.05), but did not affect the mcrA gene copies of methanogens and abundance of total bacteria. Counts of protozoa and abundance of F.succinogenes were decreased significantly (p<0.05), whereas mcrA gene copies of methanogens were decreased slightly (p<0.10) in high-forage substrate after treated by gynosaponin. However, gynosaponin treatment under high-concentrate level did not affect the methanogenesis, fermentation characteristics and tested microbes. Accordingly, overall results suggested that gynosaponin supplementation reduced the in vitro methanogenesis and improved rumen fermentation under high-forage condition by changing the abundances of related rumen microbes. PMID:25083102

Highly reflective polymeric substrates functionalized utilizing atomic layer deposition

NASA Astrophysics Data System (ADS)

Zuzuarregui, Ana; Coto, Borja; Rodríguez, Jorge; Gregorczyk, Keith E.; Ruiz de Gopegui, Unai; Barriga, Javier; Knez, Mato

2015-08-01

Reflective surfaces are one of the key elements of solar plants to concentrate energy in the receivers of solar thermal electricity plants. Polymeric substrates are being considered as an alternative to the widely used glass mirrors due to their intrinsic and processing advantages, but optimizing both the reflectance and the physical stability of polymeric mirrors still poses technological difficulties. In this work, polymeric surfaces have been functionalized with ceramic thin-films by atomic layer deposition. The characterization and optimization of the parameters involved in the process resulted in surfaces with a reflection index of 97%, turning polymers into a real alternative to glass substrates. The solution we present here can be easily applied in further technological areas where seemingly incompatible combinations of polymeric substrates and ceramic coatings occur.

Short communication: cheminformatics analysis to identify predictors of antiviral drug penetration into the female genital tract.

PubMed

Thompson, Corbin G; Sedykh, Alexander; Nicol, Melanie R; Muratov, Eugene; Fourches, Denis; Tropsha, Alexander; Kashuba, Angela D M

2014-11-01

The exposure of oral antiretroviral (ARV) drugs in the female genital tract (FGT) is variable and almost unpredictable. Identifying an efficient method to find compounds with high tissue penetration would streamline the development of regimens for both HIV preexposure prophylaxis and viral reservoir targeting. Here we describe the cheminformatics investigation of diverse drugs with known FGT penetration using cluster analysis and quantitative structure-activity relationships (QSAR) modeling. A literature search over the 1950-2012 period identified 58 compounds (including 21 ARVs and representing 13 drug classes) associated with their actual concentration data for cervical or vaginal tissue, or cervicovaginal fluid. Cluster analysis revealed significant trends in the penetrative ability for certain chemotypes. QSAR models to predict genital tract concentrations normalized to blood plasma concentrations were developed with two machine learning techniques utilizing drugs' molecular descriptors and pharmacokinetic parameters as inputs. The QSAR model with the highest predictive accuracy had R(2)test=0.47. High volume of distribution, high MRP1 substrate probability, and low MRP4 substrate probability were associated with FGT concentrations ≥1.5-fold plasma concentrations. However, due to the limited FGT data available, prediction performances of all models were low. Despite this limitation, we were able to support our findings by correctly predicting the penetration class of rilpivirine and dolutegravir. With more data to enrich the models, we believe these methods could potentially enhance the current approach of clinical testing.

The crystallogenesis of a human estradiol dehydrogenase-substrate complex

NASA Astrophysics Data System (ADS)

Zhu, Dao-Wei; Azzi, Arezki; Rehse, Peter; Lin, Sheng-Xiang

1996-10-01

Human 17β-hydroxysteroid dehydrogenase type 1 is an important steroidogenic enzyme catalyzing the synthesis of the most active estrogen: estradiol. The enzyme is formed by two identical subunits (34.5 kDa). In this paper, we report the preparation of a stoichiometric 17β-HSD1-estradiol complex sample at a much higher concentration than the solubility of the free substrate, using a gradual concentration of the enzyme-substrate mixture starting at low concentration. The complex is successfully crystallized by vapor diffusion at pH 7.5 with polyethyleneglycol 4000 as the precipitating agent. The space group is C2 with a = 123.56 Å, b = 45.21 Å, c = 61.30 Å and β = 99.06°. There is one monomer in the asymmetric unit and two molecules of the enzyme in a unit cell. A diffraction data set to 2.5 Å has been collected to 86% completeness on native crystals. The high quality of the electronic density map of estradiol supports the full occupancy of the binding site, thus confirming the efficiency of the complex preparation. This method will also be useful in crystallizing other steroid-dehydrogenase complexes.

Indirect Competitive Enzyme-Linked Immunosorbent Assay (ELISA).

PubMed

Kohl, Thomas O; Ascoli, Carl A

2017-07-05

The indirect competitive ELISA (indirect cELISA) pits plate-immobilized antigen against antigens in solution for binding to antigen-specific antibody. The antigens in solution are in the test sample and are first incubated with antigen-specific antibody. These antibody-antigen complexes are then added to microtiter plates whose wells have been coated with purified antigen. The wells are washed to remove unbound antigen-antibody complexes and free antigen. A reporter-labeled secondary antibody is then added followed by the addition of substrate. Substrate hydrolysis yields a signal that is inversely proportional to antigen concentration within the sample. This is because when antigen concentration is high in the test sample, most of the antibody is bound before adding the solution to the plate. Most of the antibody remains in solution (as complexes) and is thus washed away before the addition of the reporter-labeled secondary antibody and substrate. Thus, the higher the antigen concentration in the test sample, the weaker the resultant signal in the detection step. The indirect cELISA is often used for competitive detection and quantification of antibodies against viral diseases in biological samples. © 2017 Cold Spring Harbor Laboratory Press.

Solution of non-steady-state substrate concentration in the action of biosensor response at mixed enzyme kinetics

NASA Astrophysics Data System (ADS)

Senthamarai, R.; Jana Ranjani, R.

2018-04-01

In this paper, a mathematical model of an amperometric biosensor at mixed enzyme kinetics and diffusion limitation in the case of substrate inhibition has been developed. The model is based on time dependent reaction diffusion equation containing a non -linear term related to non -Michaelis - Menten kinetics of the enzymatic reaction. Solution for the concentration of the substrate has been derived for all values of parameters using the homotopy perturbation method. All the approximate analytic expressions of substrate concentration are compared with simulation results using Scilab/Matlab program. Finally, we have given a satisfactory agreement between them.

Process for growing epitaxial gallium nitride and composite wafers

DOEpatents

Weber, Eicke R.; Subramanya, Sudhir G.; Kim, Yihwan; Kruger, Joachim

2003-05-13

A novel growth procedure to grow epitaxial Group III metal nitride thin films on lattice-mismatched substrates is proposed. Demonstrated are the quality improvement of epitaxial GaN layers using a pure metallic Ga buffer layer on c-plane sapphire substrate. X-ray rocking curve results indicate that the layers had excellent structural properties. The electron Hall mobility increases to an outstandingly high value of .mu.>400 cm.sup.2 /Vs for an electron background concentration of 4.times.10.sup.17 cm.sup.-3.

Metal Nanoparticles/Porous Silicon Microcavity Enhanced Surface Plasmon Resonance Fluorescence for the Detection of DNA.

PubMed

Wang, Jiajia; Jia, Zhenhong

2018-02-23

A porous silicon microcavity (PSiMC) with resonant peak wavelength of 635 nm was fabricated by electrochemical etching. Metal nanoparticles (NPs)/PSiMC enhanced fluorescence substrates were prepared by the electrostatic adherence of Au NPs that were distributed in PSiMC. The Au NPs/PSiMC device was used to characterize the target DNA immobilization and hybridization with its complementary DNA sequences marked with Rhodamine red (RRA). Fluorescence enhancement was observed on the Au NPs/PSiMC device substrate; and the minimum detection concentration of DNA ran up to 10 pM. The surface plasmon resonance (SPR) of the MC substrate; which is so well-positioned to improve fluorescence enhancement rather the fluorescence enhancement of the high reflection band of the Bragg reflector; would welcome such a highly sensitive in biosensor.

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.

Permeability and Microstructure of Suspension Plasma-Sprayed YSZ Electrolytes for SOFCs on Various Substrates

NASA Astrophysics Data System (ADS)

Marr, Michael; Kesler, Olivera

2012-12-01

Yttria-stabilized zirconia electrolyte coatings for solid oxide fuel cells were deposited by suspension plasma spraying using a range of spray conditions and a variety of substrates, including finely structured porous stainless steel disks and cathode layers on stainless steel supports. Electrolyte permeability values and trends were found to be highly dependent on which substrate was used. The most gas-tight electrolyte coatings were those deposited directly on the porous metal disks. With this substrate, permeability was reduced by increasing the torch power and reducing the stand-off distance to produce dense coating microstructures. On the substrates with cathodes, electrolyte permeability was reduced by increasing the stand-off distance, which reduced the formation of segmentation cracks and regions of aligned and concentrated porosity. The formation mechanisms of the various permeability-related coating features are discussed and strategies for reducing permeability are presented. The dependences of electrolyte deposition efficiency and surface roughness on process conditions and substrate properties are also presented.

Role of Annular Lipids in the Functional Properties of Leucine Transporter LeuT Proteomicelles.

PubMed

LeVine, Michael V; Khelashvili, George; Shi, Lei; Quick, Matthias; Javitch, Jonathan A; Weinstein, Harel

2016-02-16

Recent work has shown that the choice of the type and concentration of detergent used for the solubilization of membrane proteins can strongly influence the results of functional experiments. In particular, the amino acid transporter LeuT can bind two substrate molecules in low concentrations of n-dodecyl β-d-maltopyranoside (DDM), whereas high concentrations reduce the molar binding stoichiometry to 1:1. Subsequent molecular dynamics (MD) simulations of LeuT in DDM proteomicelles revealed that DDM can penetrate to the extracellular vestibule and make stable contacts in the functionally important secondary substrate binding site (S2), suggesting a potential competitive mechanism for the reduction in binding stoichiometry. Because annular lipids can be retained during solubilization, we performed MD simulations of LeuT proteomicelles at various stages of the solubilization process. We find that at low DDM concentrations, lipids are retained around the protein and penetration of detergent into the S2 site does not occur, whereas at high concentrations, lipids are displaced and the probability of DDM binding in the S2 site is increased. This behavior is dependent on the type of detergent, however, as we find in the simulations that the detergent lauryl maltose-neopentyl glycol, which is approximately twice the size of DDM and structurally more closely resembles lipids, does not penetrate the protein even at very high concentrations. We present functional studies that confirm the computational findings, emphasizing the need for careful consideration of experimental conditions, and for cautious interpretation of data in gathering mechanistic information about membrane proteins.

Role of Annular Lipids in the Functional Properties of Leucine Transporter LeuT Proteomicelles

PubMed Central

2016-01-01

Recent work has shown that the choice of the type and concentration of detergent used for the solubilization of membrane proteins can strongly influence the results of functional experiments. In particular, the amino acid transporter LeuT can bind two substrate molecules in low concentrations of n-dodecyl β-d-maltopyranoside (DDM), whereas high concentrations reduce the molar binding stoichiometry to 1:1. Subsequent molecular dynamics (MD) simulations of LeuT in DDM proteomicelles revealed that DDM can penetrate to the extracellular vestibule and make stable contacts in the functionally important secondary substrate binding site (S2), suggesting a potential competitive mechanism for the reduction in binding stoichiometry. Because annular lipids can be retained during solubilization, we performed MD simulations of LeuT proteomicelles at various stages of the solubilization process. We find that at low DDM concentrations, lipids are retained around the protein and penetration of detergent into the S2 site does not occur, whereas at high concentrations, lipids are displaced and the probability of DDM binding in the S2 site is increased. This behavior is dependent on the type of detergent, however, as we find in the simulations that the detergent lauryl maltose-neopentyl glycol, which is approximately twice the size of DDM and structurally more closely resembles lipids, does not penetrate the protein even at very high concentrations. We present functional studies that confirm the computational findings, emphasizing the need for careful consideration of experimental conditions, and for cautious interpretation of data in gathering mechanistic information about membrane proteins. PMID:26811944

Photoinduced Bioorthogonal 1,3-Dipolar Poly-cycloaddition Promoted by Oxyanionic Substrates for Spatiotemporal Operation of Molecular Glues.

PubMed

Hatano, Junichi; Okuro, Kou; Aida, Takuzo

2016-01-04

PGlue(PZ), a pyrazoline (PZ)-based fluorescent adhesive which can be generated spatiotemporally in living systems, was developed. Since PGlue(PZ) carries many guanidinium ion (Gu(+)) pendants, it strongly adheres to various oxyanionic substrates through a multivalent salt-bridge interaction. PGlue(PZ) is given by bioorthogonal photopolymerization of a Gu(+)-appended monomer (Glue(TZ)), bearing tetrazole (TZ) and olefinic termini. Upon exposure to UV light, Glue(TZ) transforms into a nitrileimine (NI) intermediate (Glue(NI)), which is eligible for 1,3-dipolar polycycloaddition. However, Glue(NI) in aqueous media can concomitantly be deactivated into Glue(WA) by the addition of water, and the polymerization hardly occurs unless Glue(NI) is concentrated. We found that, even under high dilution, Glue(NI) is concentrated on oxyanionic substrates to a sufficient level for the polymerization, so that their surfaces can be point-specifically functionalized with PGlue(PZ) by the use of a focused beam of UV light. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kinetic study of sunflower phospholipase Dα: interactions with micellar substrate, detergents and metals.

PubMed

Abdelkafi, Slim; Abousalham, Abdelkarim

2011-07-01

Phospholipase Dα (PLDα) purified from six-day post-germinated sunflower seeds was inactive in vitro on bilamellar substrates. It was fully active on mixed micelles made with phospholipids and a mixture of Triton-X100 and SDS at equal concentrations. It had an absolute need for divalent ions and calcium ions at millimolar concentration were the most efficient. Calcium had two effects. Firstly, using the fluorescent probe 2-p-toluidinylnaphtalene-6-sulfonate, we showed that the enzyme was able to bind calcium with a dissociation constant of 40-50 mM. This high value is probably due to the modification of the C2 domain which lacks some coordination residues allowing the binding of the metal. Secondly, using turbidity measurements, we showed that the metal ions interact with the SDS contained in the mixed micelles thus leading to an aggregated form of the substrate which is more easily hydrolyzed by PLDα. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Effect of plasma nitriding on the structural stability and hydrogen absorption capability of Pd-coated Nb during thermal treatment

NASA Astrophysics Data System (ADS)

Ohtsu, Naofumi; Kozuka, Taro; Shibata, Yuga; Yamane, Misao

2017-11-01

Plasma nitriding was explored for improving the thermal stability of a composite hydrogen permeable membrane comprising a Pd coating on Nb substrate. A NbN intermediate layer was formed on the Nb substrate, and the progress of interdiffusion and deterioration of hydrogen absorption behavior after a thermal treatment at 573 and 773 K, respectively, were investigated. The intermediate layer significantly suppressed the interdiffusion between the coating and the substrate. Furthermore, an increase in the NbN concentration of the intermediate layer enhanced the suppression efficiency. However, the hydrogen permeability of the intermediate layer was significantly low, and hence, an increase in NbN concentration further decreased the hydrogen permeability. We concluded that the nitride layer with a high NbN content was unsuitable as an intermediate layer owing to its low hydrogen permeability, while the partial nitride layer with a low NbN content was inefficient in suppressing the interdiffusion.

Single-shot characterization of enzymatic reaction constants Km and kcat by an acoustic-driven, bubble-based fast micromixer.

PubMed

Xie, Yuliang; Ahmed, Daniel; Lapsley, Michael Ian; Lin, Sz-Chin Steven; Nawaz, Ahmad Ahsan; Wang, Lin; Huang, Tony Jun

2012-09-04

In this work we present an acoustofluidic approach for rapid, single-shot characterization of enzymatic reaction constants K(m) and k(cat). The acoustofluidic design involves a bubble anchored in a horseshoe structure which can be stimulated by a piezoelectric transducer to generate vortices in the fluid. The enzyme and substrate can thus be mixed rapidly, within 100 ms, by the vortices to yield the product. Enzymatic reaction constants K(m) and k(cat) can then be obtained from the reaction rate curves for different concentrations of substrate while holding the enzyme concentration constant. We studied the enzymatic reaction for β-galactosidase and its substrate (resorufin-β-D-galactopyranoside) and found K(m) and k(cat) to be 333 ± 130 μM and 64 ± 8 s(-1), respectively, which are in agreement with published data. Our approach is valuable for studying the kinetics of high-speed enzymatic reactions and other chemical reactions.

[Limiting factors of waste land revegetation in indigenous zinc smelting areas of western Guizhou].

PubMed

Lin, Wen-Jie; Xiao, Tang-Fu; Ao, Zi-Qiang; Xing, Jun; Ma, Huan-Cheng; Hu, Ting-Xing

2007-03-01

With indigenous zinc smelting waste residue, contaminated soil and background soil as test substrates, a pot experiment was conducted to study the growth characteristics of Lolium perenne and Trifolium pretense on these substrates. The results showed that the major limiting factors of waste land revegetation in indigenous zinc smelting areas of western Guizhou were the salt-alkali stress and the lower contents of organic matter, total N, available N and total K. The heavy metals in waste residue had a high concentration, but their available forms only occupied a small proportion, with low toxicity to plant but having potential harmful risk. Contaminated soil had lower concentrations of heavy metals than waste residue, but its contained heavy metals were more in available form. The constraints of revegetation on contaminated soil were the toxicity of heavy metals and the low contents of available P and K. Mixing contaminated soil with zinc smelting waste residue could be one of the effective approaches for the substrate amendment in indigenous zinc smelting areas.

Effect of Trichoderma on horticultural seedlings' growth promotion depending on inoculum and substrate type.

PubMed

Marín-Guirao, J I; Rodríguez-Romera, P; Lupión-Rodríguez, B; Camacho-Ferre, F; Tello-Marquina, J C

2016-10-01

The biostimulant effect of Trichoderma spp. on horticultural crops are highly variable. Thus, practical use of Trichoderma sp. requires feasible formulated products and suitable substrates. This study evaluates the survival and the growth-promotion effect of a Trichoderma saturnisporum rice formulation compared with a nonformulated conidia suspension (seven treatments in total), on tomato, pepper and cucumber seedlings grown in two substrates: (i) rich in organic matter (OM) and (ii) mineral substrate without OM. The results showed beneficial effects on seedling growth in the OM-rich substrate when T. saturnisporum rice formulation (mainly at maximum concentration) was applied, but the effects were opposite when the mineral substrate without OM was used. The effects were closely linked to the level of inoculum in the substrate, which was greater upon application of the formulated inoculum as opposed to the nonformulated one. The use of rice to prepare the inoculum of T. saturnisporum seems to be promising for seedling growth in the nursery when it is applied in a substrate that is rich in organic matter, but it must be considered that under certain conditions of food shortage, Trichoderma sp. could show pathogenicity to seedlings. This study provides evidence of the complexity inherent in the use of micro-organisms in agriculture, while also confirming that the activity of the biofertilizers based on Trichoderma depends on the type of inoculum and its concentration, as well as the properties of the medium in which the fungi develop. Further studies assessing the effectiveness or possible pathogenicity of Trichoderma in different soils under greenhouse conditions must be addressed. © 2016 The Society for Applied Microbiology.

Inoculation of sphagnum-based soil substrate with entomopathogenic fungus Isaria fumosorosea (Hypocreales: Cordycipitaceae)

NASA Astrophysics Data System (ADS)

Zemek, Rostislav; Konopická, Jana; Bohatá, Andrea

2018-04-01

Convenient ecological alternative to broad-spectrum chemical pesticides is the utilization of natural enemies, like predators, parasitoids and microorganisms. A substantial number of microbial biopesticides based on entomopathogenic fungi have been developed worldwide since 1960s. Beauveria bassiana (Balsamo-Crivelli) Vuillemin, Metarhizium anisopliae (Metchnikoff) Sorokin, Isaria fumosorosea (Wize), and B. brongniartii (Saccardo) Petch are the most common species used in commercially produced mycopesticides. Besides direct biological pest control, these fungi could be also used in preventive application programs, particularly in ornamental or nursery plants to provide better control against pests. The aim of the present study was to investigate potential of pre-colonization of sphagnum-based soil substrate with I. fumosorosea strain CCM 8367 which was found earlier to be highly virulent against several pest species. We developed simple laboratory apparatus for application of fungal spore suspension into the substrate. Suspension was prepared from blastospores obtained by submerged cultivation on potato dextrose broth (PDB) medium using an orbital shaker. Inoculated substrate was placed into plastic bags and stored at constant temperature for six months. Every month, samples were analyzed for concentration of colony forming units (CFU) by elution and selective medium technique. The results showed that at 20°C the fungus successfully colonized the soil substrate and persisted there although the mean concentration slightly decreased from 5.89×104 to 2.76×104 CFU per milliliter of substrate during the experiment. Temperature 30°C had negative effect on survival of the fungus and is not recommended for long-term storage of pre-inoculated substrate. We can conclude that I. fumosorosea-colonized substrate can be convenient for preventive and permanent protection of various plants against soil-dwelling pests.

Effect of Boron Doping on High-Resolution X-Ray Diffraction Metrology

NASA Astrophysics Data System (ADS)

Faheem, M.; Zhang, Y.; Dai, X.

2018-03-01

The effect of boron (B) doping on high-resolution X-ray diffraction (HXRD) metrology has been investigated. Twelve samples of Si1-xGex films were epitaxially grown on Si (100) substrates with different thicknesses, germanium (Ge) concentrations and with/without B dopants. Secondary ion mass spectroscopy (SIMS) and HXRD were employed for measurements of B doping, Ge concentration, strain, and thickness of the layers. The SIMS results show the absence of B in two samples while the rest of the samples have B doping in the range of 8.40 × 1018-8.7 × 1020 atoms/cm3 with Ge concentration of 13.3-55.2 at.%. The HXRD measurements indicate the layers thickness of 7.07-108.13 nm along with Ge concentration of 12.82-49.09 at.%. The difference in the Ge concentration measured by SIMS and HXRD was found to deend on B doping. For the undoped samples, the difference is 0.5 at.% and increases with B doping but with no linear proportionality. The difference in the Ge concentration was 7.11 at.% for the highly B-doped (8.7 × 1020 atoms/cm3) sample. The B doping influences the Si1-xGex structure, causing a change in the lattice parameter and producing tensile strains shifting Si1-xGex peaks towards Si (100) substrate peaks in the HXRD diffraction patterns. As a result, Vegard's law is no longer effective and makes a high impact on the HXRD measurement. The comparison between symmetric (004) and asymmetric (+113, +224) reciprocal space mappings (RSM) showed a slight difference in Ge concentration between the undoped and lower B-doped samples. However, there is a change of 0.21 at.% observed for the highly doped Si1-xGex samples. RSM's (+113) demonstrate the small SiGe peak broadening as B doping increases, which indicates a minor crystal distortion.

Electrogenic Binding of Intracellular Cations Defines a Kinetic Decision Point in the Transport Cycle of the Human Serotonin Transporter.

PubMed

Hasenhuetl, Peter S; Freissmuth, Michael; Sandtner, Walter

2016-12-09

The plasmalemmal monoamine transporters clear the extracellular space from their cognate substrates and sustain cellular monoamine stores even during neuronal activity. In some instances, however, the transporters enter a substrate-exchange mode, which results in release of intracellular substrate. Understanding what determines the switch between these two transport modes demands time-resolved measurements of intracellular (co-)substrate binding and release. Here, we report an electrophysiological investigation of intracellular solute-binding to the human serotonin transporter (SERT) expressed in HEK-293 cells. We measured currents induced by rapid application of serotonin employing varying intracellular (co-)substrate concentrations and interpreted the data using kinetic modeling. Our measurements revealed that the induction of the substrate-exchange mode depends on both voltage and intracellular Na + concentrations because intracellular Na + release occurs before serotonin release and is highly electrogenic. This voltage dependence was blunted by electrogenic binding of intracellular K + and, notably, also H + In addition, our data suggest that Cl - is bound to SERT during the entire catalytic cycle. Our experiments, therefore, document an essential role of electrogenic binding of K + or of H + to the inward-facing conformation of SERT in (i) cancelling out the electrogenic nature of intracellular Na + release and (ii) in selecting the forward-transport over the substrate-exchange mode. Finally, the kinetics of intracellular Na + release and K + (or H + ) binding result in a voltage-independent rate-limiting step where SERT may return to the outward-facing state in a KCl- or HCl-bound form. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Alkylamine capped metal nanoparticle "inks" for printable SERS substrates, electronics and broadband photodetectors.

PubMed

Polavarapu, Lakshminarayana; Manga, Kiran Kumar; Yu, Kuai; Ang, Priscilla Kailian; Cao, Hanh Duyen; Balapanuru, Janardhan; Loh, Kian Ping; Xu, Qing-Hua

2011-05-01

We report a facile and general method for the preparation of alkylamine capped metal (Au and Ag) nanoparticle "ink" with high solubility. Using these metal nanoparticle "inks", we have demonstrated their applications for large scale fabrication of highly efficient surface enhanced Raman scattering (SERS) substrates by a facile solution processing method. These SERS substrates can detect analytes down to a few nM. The flexible plastic SERS substrates have also been demonstrated. The annealing temperature dependent conductivity of the nanoparticle films indicated a transition temperature above which high conductivity was achieved. The transition temperature could be tailored to the plastic compatible temperatures by using proper alkylamine as the capping agent. The ultrafast electron relaxation studies of the nanoparticle films demonstrated that faster electron relaxation was observed at higher annealing temperatures due to stronger electronic coupling between the nanoparticles. The applications of these highly concentrated alkylamine capped metal nanoparticle inks for the printable electronics were demonstrated by printing the oleylamine capped gold nanoparticles ink as source and drain for the graphene field effect transistor. Furthermore, the broadband photoresponse properties of the Au and Ag nanoparticle films have been demonstrated by using visible and near-infrared lasers. These investigations demonstrate that these nanoparticle "inks" are promising for applications in printable SERS substrates, electronics, and broadband photoresponse devices. © The Royal Society of Chemistry 2011

Nitrate removal from high strength nitrate-bearing wastes in granular sludge sequencing batch reactors.

PubMed

Krishna Mohan, Tulasi Venkata; Renu, Kadali; Nancharaiah, Yarlagadda Venkata; Satya Sai, Pedapati Murali; Venugopalan, Vayalam Purath

2016-02-01

A 6-L sequencing batch reactor (SBR) was operated for development of granular sludge capable of denitrification of high strength nitrates. Complete and stable denitrification of up to 5420 mg L(-1) nitrate-N (2710 mg L(-1) nitrate-N in reactor) was achieved by feeding simulated nitrate waste at a C/N ratio of 3. Compact and dense denitrifying granular sludge with relatively stable microbial community was developed during reactor operation. Accumulation of large amounts of nitrite due to incomplete denitrification occurred when the SBR was fed with 5420 mg L(-1) NO3-N at a C/N ratio of 2. Complete denitrification could not be achieved at this C/N ratio, even after one week of reactor operation as the nitrite levels continued to accumulate. In order to improve denitrification performance, the reactor was fed with nitrate concentrations of 1354 mg L(-1), while keeping C/N ratio at 2. Subsequently, nitrate concentration in the feed was increased in a step-wise manner to establish complete denitrification of 5420 mg L(-1) NO3-N at a C/N ratio of 2. The results show that substrate concentration plays an important role in denitrification of high strength nitrate by influencing nitrite accumulation. Complete denitrification of high strength nitrates can be achieved at lower substrate concentrations, by an appropriate acclimatization strategy. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Resonance-shifting luminescent solar concentrators

DOEpatents

Giebink, Noel Christopher; Wiederrecht, Gary P; Wasielewski, Michael R

2014-09-23

An optical system and method to overcome luminescent solar concentrator inefficiencies by resonance-shifting, in which sharply directed emission from a bi-layer cavity into a glass substrate returns to interact with the cavity off-resonance at each subsequent reflection, significantly reducing reabsorption loss en route to the edges. In one embodiment, the system comprises a luminescent solar concentrator comprising a transparent substrate, a luminescent film having a variable thickness; and a low refractive index layer disposed between the transparent substrate and the luminescent film.

Resonance-shifting luminescent solar concentrators

DOEpatents

Giebink, Noel Christopher; Wiederrecht, Gary P.; Wasielewski, Michael R.

2018-01-23

An optical system and method to overcome luminescent solar concentrator inefficiencies by resonance-shifting, in which sharply directed emission from a bi-layer cavity into a glass substrate returns to interact with the cavity off-resonance at each subsequent reflection, significantly reducing reabsorption loss en route to the edges. In one embodiment, the system comprises a luminescent solar concentrator comprising a transparent substrate, a luminescent film having a variable thickness; and a low refractive index layer disposed between the transparent substrate and the luminescent film.

Hydrothermal synthesis of highly crystalline ZnO nanorod arrays: Dependence of morphology and alignment on growth conditions

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

Azzez, Shrook A., E-mail: shurouq44@yahoo.com; Hassan, Z.; Alimanesh, M.

Highly oriented zinc oxide nanorod were successfully grown on seeded p-type silicon substrate by hydrothermal methode. The morphology and the crystallinty of ZnO c-axis (002) arrays were systematically studied using field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) methods. The effect of seed layer pre-annealing on nanorods properties was explained according to the nucleation site of ZnO nanoparticles on silicon substrate. In addition, the variation of the equal molarity of zinc nitrate hexahydrate and hexamine concentrations in the reaction vessel play a crucial role related to the ZnO nanorods.

High-fluence ion implantation in silicon carbide for fabrication of a compliant substrate

NASA Astrophysics Data System (ADS)

Lioubtchenko, Mikhail

GaN and related nitrides are promising materials for applications as UV/blue light emitters and in high-power, high-temperature electonic devices. Unfortunately, the vast potential of these materials cannot be realized effectively due to a large density of threading dislocations, arising from large lattice mismatch between GaN and utilized substrates. Therefore, a new approach to the heteroepitaxial growth is desirable, and a compliant substrate might help to remedy the situation. A modified model for the compliant substrate consisting of the compliant membrane glued to a thick handling substrate by a soft layer was proposed. We have chosen 6H-SiC as a starting substrate and ion implantation as a means of creating a buried layer. High fluence ion implantation of different species in 6H-SiC was performed at elevated temperatures and damage removal/accumulation was studied. It was found that temperatures around 1600°C are necessary to successfully recrystallize the radiation damage for Ti, Ga, Si and C implantations, but no damage removal was monitored for In implantation. In order to minimize the damage produced during ion implantation, it was decided to employ a multistep process in which each implantation step was followed by annealing. This approach was realized for 125 keV Ti++ and 300 keV Ga+ implantations up to a total dose of 1.8 x 1017 cm--2. Ti-implanted substrates were shown to retain good quality in the top layer, whereas Ga implantation preserves the quality of the near-surface region only at lower doses. The implanted species concentration was monitored after each step using Rutherford Backscattering (RBS). GaN films were grown on the prepared substrates and a control SiC sample by MOCVD. TEM and photoluminescence measurements have demonstrated that the quality of GaN films improves upon growth on compliant substrates.

Human plasma metabolic profiles of benzydamine, a flavin-containing monooxygenase probe substrate, simulated with pharmacokinetic data from control and humanized-liver mice.

PubMed

Yamazaki-Nishioka, Miho; Shimizu, Makiko; Suemizu, Hiroshi; Nishiwaki, Megumi; Mitsui, Marina; Yamazaki, Hiroshi

2018-02-01

1. Benzydamine is used clinically as a nonsteroidal anti-inflammatory drug in oral rinses and is employed in preclinical research as a flavin-containing monooxygenase (FMO) probe substrate. In this study, plasma concentrations of benzydamine and its primary N-oxide and N-demethylated metabolites were investigated in control TK-NOG mice, in humanized-liver mice, and in mice whose liver cells had been ablated with ganciclovir. 2. Following oral administration of benzydamine (10 mg/kg) in humanized-liver TK-NOG mice, plasma concentrations of benzydamine N-oxide were slightly higher than those of demethyl benzydamine. In contrast, in control and ganciclovir-treated TK-NOG mice, concentrations of demethyl benzydamine were slightly higher than those of benzydamine N-oxide. 3. Simulations of human plasma concentrations of benzydamine and its N-oxide were achieved using simplified physiologically based pharmacokinetic models based on data from control TK-NOG mice and from reported benzydamine concentrations after low-dose administration in humans. Estimated clearance rates based on data from humanized-liver and ganciclovir-treated TK-NOG mice were two orders magnitude high. 4. The pharmacokinetic profiles of benzydamine were different for control and humanized-liver TK-NOG mice. Humanized-liver mice are generally accepted human models; however, drug oxidation in mouse kidney might need to be considered when probe substrates undergo FMO-dependent drug oxidation in mouse liver and kidney.

Growth and elemental content of two tree species growing on abandoned coal fly ash basins. [Liquidambar styraciflua L. ; Platanus occidentalis

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

Carlson, C.L.; Adriano, D.C.

Differences in aboveground tissue concentrations of trace elements were assessed for sweetgum (Liquidambar styraciflua L.) and sycamore (Plantanus occidentalis L.) growing on two abandoned coal fly ash basins and a control soil. The wet basin (pH = 5.58) had originally received precipitator ash in an ash-water slurry, while the dry basin (pH = 8.26) had received both precipitator and bottom ash in dry form. In general, trees from the wet basin exhibited elevated trace element concentrations in comparison to the controls, while the dry basin trees exhibited reduced concentrations. On eof the most striking differenced in elemental concentrations among themore » ash basin and control trees was observed for Mn, with the control trees exhibiting concentrations orders of magnitude greater than the ash basin trees. Differences in foliar trace element concentrations among the sites can generally be explained by differences in substrate trace element concentrations and/or substrate pH. While trees from the wet ash basin generally had the highest trace element concentrations, these trees also attained the greatest height and diameter growth, suggesting that the elevated trace element concentrations in the wet basin substrate are not limiting the establishment of these two species. The greater height and diameter growth of the wet basin trees is presumably a result of the greater water-holding capacity of the substrate on this site. Differences in growth and tissue concentrations between sweetgum and sycamore highlight the importance of using more than one species when assessing metal toxicity or deficiency on a given substrate.« less

Effect of crude glycerol-derived inhibitors on ethanol production by Enterobacter aerogenes.

PubMed

Lee, Sang Jun; Kim, Sung Bong; Kang, Seong Woo; Han, Sung Ok; Park, Chulhwan; Kim, Seung Wook

2012-01-01

In this study, ethanol production from pure and crude glycerol using Enterobacter aerogenes ATCC 29007 was evaluated under anaerobic culture conditions. Inhibitory effects of substrate concentrations, pH, and salt concentrations were investigated based on crude glycerol components. Ethanol production was performed with pure glycerol concentrations ranging from 5 to 30 g/L to evaluate the effects of substrate concentration and osmotic pressure. The consumed glycerol was 5-14.33 g/L, and the yield of ethanol was higher than 0.75 mol ethanol/mol glycerol after 24 h of cultivation. To evaluate the inhibitory effects of salts (NaCl and KCl), experiments were performed with 0-20 g/L of each salt. Inhibitory effects of salts were strongest at high salt concentrations. The inhibitory effect of pH was performed in the pH range 4-10, and cell growth and ethanol production were highest at pH 5-6. Also, ethanol production was slightly inhibited at low concentration of crude glycerol comparison with pure glycerol. However, significant inhibitory effects were not observed at 1.5 and 2% crude glycerol which showed higher ethanol production compared to pure glycerol.

Development of MoSi2 coating with Al doping by using high energy milling method

NASA Astrophysics Data System (ADS)

Simanjuntak, C. M. S.; Hastuty, S.; Izzuddin, H.; Sundawa, R.; Sudiro, T.; Sukarto, A.; Thosin, K. A. Z.

2018-03-01

MoSi2 is well known as a material for high temperature application because it has high oxidation and corrosion resistance. The aim of this research is to develop MoSi2 coating with Al doping on Stainless Steel 316 (SS316) substrate using High-Energy Milling method. Aluminium is added to the coating as a dopant to increase formation of MoSi2 coating layer on the substrate. The variations used here based on the concentrations of doping Al (at.%) and duration of milling. Results show that the MoSi2 coatings with variations of 30 and 50 at.% of Al doping and 3 and 6 hours of milling times were successfully coated on the surface of SS 316 using the high-energy milling method. The most optimum coating result after oxidation test at 1100 °C for 100 hours is shown by MoSi2-30%Al with 3 hours of milling times. From the oxidation results, the Al doping into MoSi2 coating was able to increase the oxidation resistance of the SS 316 substrate.

One-step process of hydrothermal and alkaline treatment of wheat straw for improving the enzymatic saccharification.

PubMed

Sun, Shaolong; Zhang, Lidan; Liu, Fang; Fan, Xiaolin; Sun, Run-Cang

2018-01-01

To increase the production of bioethanol, a two-step process based on hydrothermal and dilute alkaline treatment was applied to reduce the natural resistance of biomass. However, the process required a large amount of water and a long operation time due to the solid/liquid separation before the alkaline treatment, which led to decrease the pure economic profit for production of bioethanol. Therefore, four one-step processes based on order of hydrothermal and alkaline treatment have been developed to enhance concentration of glucose of wheat straw by enzymatic saccharification. The aim of the present study was to systematically evaluated effect for different one-step processes by analyzing the physicochemical properties (composition, structural change, crystallinity, surface morphology, and BET surface area) and enzymatic saccharification of the treated substrates. In this study, hemicelluloses and lignins were removed from wheat straw and the morphologic structures were destroyed to various extents during the four one-step processes, which were favorable for cellulase absorption on cellulose. A positive correlation was also observed between the crystallinity and enzymatic saccharification rate of the substrate under the conditions given. The surface area of the substrate was positively related to the concentration of glucose in this study. As compared to the control (3.0 g/L) and treated substrates (11.2-14.6 g/L) obtained by the other three one-step processes, the substrate treated by one-step process based on successively hydrothermal and alkaline treatment had a maximum glucose concentration of 18.6 g/L, which was due to the high cellulose concentration and surface area for the substrate, accompanying with removal of large amounts of lignins and hemicelluloses. The present study demonstrated that the order of hydrothermal and alkaline treatment had significant effects on the physicochemical properties and enzymatic saccharification of wheat straw. The one-step process based on successively hydrothermal and alkaline treatment is a simple operating and economical feasible method for the production of glucose, which will be further converted into bioethanol.

Microbial community changes as a possible factor controlling carbon sequestration in subsoil

NASA Astrophysics Data System (ADS)

Strücker, Juliane; Jörgensen, Rainer Georg

2015-04-01

In order to gain more knowledge regarding the microbial community and their influence on carbon sequestration in subsoil two depth profiles with different soil organic carbon (SOC) concentrations were sampled. The SOC concentrations developed naturally due to deposition and erosion. This experiment offers the opportunity to investigate to which extend natural SOC availability or other subsoil specific conditions influence the composition and the functional diversity of the microbial community and in return if there is any evidence how the microbial community composition affects carbon sequestration under these conditions. Soil samples were taken at four different depths on two neighbouring arable sites; one Kolluvisol with high SOC concentrations (8-12 g/kg) throughout the profile and one Luvisol with low SOC concentrations (3-4 g/kg) below 30 cm depth. The multi substrate induced respiration (MSIR) method was used to identify shifts in the functional diversity of the microbial community along the depth profiles. Amino sugars Muramic Acid and Glucosamine were measured as indicators for bacterial and fungal residues and ergosterol was determined as marker for saprotrophic fungi. The results of the discriminant analysis of the respiration values obtained from the 17 substrates used in the MSIR show that the substrate use in subsoil is different from the substrate use in topsoil. The amino sugar analysis and the ratio of ergosterol to microbial biomass C indicate that the fungal dominance of the microbial community decreases with depth. The results from this study support previous findings, which also observed decreasing fungal dominance with depth. Furthermore the MSIR approach shows clearly that not only the composition of the microbial community but also their substrate use changes with depth. Thus, a different microbial community with altered substrate requirements could be an important reason for enhanced carbon sequestration in subsoil. The fact that the MSIR was also able to differentiate between the two sites proves the assumption that resources are an important factor controlling the functional diversity of the microbial community, as abiotic factors are very similar for the two profiles, but the sites show a different depth gradient for SOC.

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.

Selected classes of minimised hammerhead ribozyme have very high cleavage rates at low Mg2+ concentration.

PubMed Central

Conaty, J; Hendry, P; Lockett, T

1999-01-01

In vitro selection was used to enrich for highly efficient RNA phosphodiesterases within a size-constrained (18 nt) ribonucleotide domain. The starting population (g0) was directed in trans against an RNA oligonucleotide substrate immobilised to an avidin-magnetic phase. Four rounds of selection were conducted using 20 mM Mg2+to fractionate the population on the basis of divalent metal ion-dependent phosphodiesterase activity. The resulting generation 4 (g4) RNA was then directed through a further two rounds of selection using low concentrations of Mg2+. Generation 6 (g6) was composed of sets of active, trans cleaving minimised ribozymes, containing recognised hammerhead motifs in the conserved nucleotides, but with highly variable linker domains (loop II-L.1-L.4). Cleavage rate constants in the g6 population ranged from 0.004 to 1.3 min-1at 1 mM Mg2+(pH 8.0, 37 degrees C). Selection was further used to define conserved positions between G(10.1) and C(11.1) required for high cleavage activity at low Mg2+concentration. At 10 mM MgCl2the kinetic phenotype of these molecules was comparable to a hammerhead ribozyme with 4 bp in helix II. At low Mg2+concentration, the disparity in cleavage rate constants increases in favour of the minimised ribozymes. Favourable kinetic traits appeared to be a general property for specific selected linker sequences, as the high rates of catalysis were transferable to a different substrate system. PMID:10325431

Substrate Cooperativity in Marine Luciferases

PubMed Central

Tzertzinis, George; Schildkraut, Ezra; Schildkraut, Ira

2012-01-01

Marine luciferases are increasingly used as reporters to study gene regulation. These luciferases have utility in bioluminescent assay development, although little has been reported on their catalytic properties in response to substrate concentration. Here, we report that the two marine luciferases from the copepods, Gaussia princeps (GLuc) and Metridia longa (MLuc) were found, surprisingly, to produce light in a cooperative manner with respect to their luciferin substrate concentration; as the substrate concentration was decreased 10 fold the rate of light production decreased 1000 fold. This positive cooperative effect is likely a result of allostery between the two proposed catalytic domains found in Gaussia and Metridia. In contrast, the marine luciferases from Renilla reniformis (RLuc) and Cypridina noctiluca (CLuc) demonstrate a linear relationship between the concentration of their respective luciferin and the rate of light produced. The consequences of these enzyme responses are discussed. PMID:22768230

Influence of Y doping concentration on the properties of nanostructured MxZn1-xO (M=Y) thin film deposited by nebulizer spray pyrolysis technique

NASA Astrophysics Data System (ADS)

Mariappan, R.; Ponnuswamy, V.; Chandra Bose, A.; Suresh, R.; Ragavendar, M.

2014-09-01

Yttrium doped Zinc Oxide (YxZn1-xO) thin films deposited at a substrate temperature 400 °C. The effect of substrate temperature on the structural, surface morphology, compositional, optical and electrical properties of YxZn1-xO thin films was studied. X-ray diffraction studies show that all films are polycrystalline in nature with hexagonal crystal structure having highly textured (002) plane parallel to the surface of the substrate. The structural parameters, such as lattice constants (a and c), crystallite size (D), dislocation density (δ), microstrain (σ) and texture coefficient were calculated for different yttrium doping concentrations (x). High resolution scanning electron microscopy measurements reveal that the surface morphology of the films change from platelet like grains to hexagonal structure with grain size increase due to the yttrium doping. Energy dispersive spectroscopy confirms the presence of Y, Zn and O elements in the films prepared. Optical studies showed that all samples have a strong optical transmittance higher than 70% in the visible range. A slight shift of the absorption edge towards the large wavelengths was observed as the Y doping concentration increased. This result shows that the band gap is slightly decreased from 3.10 to 2.05 eV with increase of the yttrium doping concentrations (up to 7.5%) and then slightly increased. Room temperature PL measurements were done and the band-to-band emission energies of films were determined and reported. The complex impedance of the 10%Y doped ZnO film shows two distinguished semicircles and the diameter of the arcs got decreased in diameter as the temperature increases from 70 to 175 °C.

Nernst-ping-pong model for evaluating the effects of the substrate concentration and anode potential on the kinetic characteristics of bioanode.

PubMed

Peng, Sikan; Liang, Da-Wei; Diao, Peng; Liu, Yanyan; Lan, Fei; Yang, Yuhan; Lu, Shanfu; Xiang, Yan

2013-05-01

Understanding the electron-transfer mechanism and kinetic characteristics of bioanodes is greatly significant to enhance the electron-generating efficiencies in bioelectrochemical systems (BESs). A Nernst-ping-pong model is proposed here to investigate the kinetics and biochemical processes of bioanodes in a microbial electrolysis cell. This model can accurately describe the effects of the substrate (including substrate inhibition) and the anode potential on the current of bioanodes. Results show that the half-wave potential positively shifts as the substrate concentration increases, indicating that the rate-determining steps of anodic processes change from substrate oxidation to intracellular electron transport reaction. The anode potential has negligible effects on the enzymatic catalysis of anodic microbes in the range of -0.25 V to +0.1 V vs. a saturated calomel electrode. It turns out that to reduce the anodic energy loss caused by overpotential, higher substrate concentrations are preferred, if the substrate do not significantly and adversely affect the output current. Copyright © 2013 Elsevier Ltd. All rights reserved.

Material growth and characterization for solid state devices

NASA Technical Reports Server (NTRS)

Stefanakos, E. K.; Collis, W. J.; Abul-Fadl, A.; Iyer, S.

1984-01-01

During the reporting period, InGaAs was grown on Fe-doped (semi-insulating) (100) InP substrates by current controlled liquid phase epitaxy (CCLPE) at 640 C and current densities of 2.5A sq/cm to 5 A/sq cm for periods from 5 to 30 minutes. Special efforts were made to reduce the background carrier concentration in the grown layers as much as possible. The best layers exhibited carrier concentrations in the mid-10 to the 15th power/cu cm range and up to 10,900 sq cm/V-sec room temperature mobility. InGaAsP quaternary layers of energy gap corresponding to wavelengths of approximately 1.5 microns and 1.3 microns were grown on (100) InP substrates by CCLPE. In the device fabrication area, work was directed toward processing MISFET's using InGaAs. SiO2, Si3N4 and Al2O3 were deposited by ion beam sputtering, electron beam evaporation and chemical vapor reaction on Si, GaAs, and InGaAs substrates. SiO2 and Si3N4 sputtered layers were found to possess a high density of pinhole defects that precluded capacitance-voltage analysis. Chemical vapor deposited Al2O3 layers on Si, GaAs and InGaAs substrates also exhibited a large number of pinhole defects. This prevented achieving good MIS devices over most of the substrate surface area.

Concentration dependence of biotransformation in fish liver S9: Optimizing substrate concentrations to estimate hepatic clearance for bioaccumulation assessment.

PubMed

Lo, Justin C; Allard, Gayatri N; Otton, S Victoria; Campbell, David A; Gobas, Frank A P C

2015-12-01

In vitro bioassays to estimate biotransformation rate constants of contaminants in fish are currently being investigated to improve bioaccumulation assessments of hydrophobic contaminants. The present study investigates the relationship between chemical substrate concentration and in vitro biotransformation rate of 4 environmental contaminants (9-methylanthracene, pyrene, chrysene, and benzo[a]pyrene) in rainbow trout (Oncorhynchus mykiss) liver S9 fractions and methods to determine maximum first-order biotransformation rate constants. Substrate depletion experiments using a series of initial substrate concentrations showed that in vitro biotransformation rates exhibit strong concentration dependence, consistent with a Michaelis-Menten kinetic model. The results indicate that depletion rate constants measured at initial substrate concentrations of 1 μM (a current convention) could underestimate the in vitro biotransformation potential and may cause bioconcentration factors to be overestimated if in vitro biotransformation rates are used to assess bioconcentration factors in fish. Depletion rate constants measured using thin-film sorbent dosing experiments were not statistically different from the maximum depletion rate constants derived using a series of solvent delivery-based depletion experiments for 3 of the 4 test chemicals. Multiple solvent delivery-based depletion experiments at a range of initial concentrations are recommended for determining the concentration dependence of in vitro biotransformation rates in fish liver fractions, whereas a single sorbent phase dosing experiment may be able to provide reasonable approximations of maximum depletion rates of very hydrophobic substances. © 2015 SETAC.

Supplementation of banana flower powder pellet and plant oil sources on in vitro ruminal fermentation, digestibility, and methane production.

PubMed

Kang, Sungchhang; Wanapat, Metha; Viennasay, Bounnaxay

2016-12-01

The objective of this study was to evaluate the effects of banana flower power pellet (BAFLOP-pellet) and plant oil source on in vitro gas production, fermentation efficiency, and methane (CH 4 ) production. Rumen fluid was collected from two rumen-fistulated dairy steers fed on rice straw-based diet with concentrate supplement to maintain normal rumen ecology. All supplemented feed were added to respective treatments in the 30:70 roughage to concentrate-based substrate. The treatments were arranged according to a 3 × 3 factorial arrangement in a completely randomized design. First factor was different levels of BAFLOP-pellet supplementation (0, 30, and 60 g/kg of dietary substrate) and second factor was plant oil source supplementation [non-supplemented, 20 g/kg krabok seed oil (KSO), and 20 g/kg coconut oil (CO) of dietary substrate, respectively]. Under this investigation, BAFLOP-pellet supplementation increased gas production kinetics and in vitro digestibility (P < 0.05). Ruminal pH was dropped post incubation time in the non-supplemented group but was enhanced in BAFLOP-pellet-supplemented treatments. On the other hand, supplementation of KSO and CO depressed gas production and digestibility, but did not influence ruminal pH. In addition, protozoal population and CH 4 production were decreased by BAFLOP-pellet and plant oil addition (P < 0.05). Based on this study, it could be concluded that supplementation of BAFLOP-pellet and plant oil source could enhance the in vitro fermentation efficiency while reduced protozoal population and CH 4 production. It is suggested that BAFLOP-pellet (60 g/kg of dietary substrate) and KSO/CO (20 g/kg of dietary substrate) could be used to manipulate rumen fermentation characteristics fed on high-concentrate diet.

Potential of Cultivated Ganoderma lucidum Mushrooms for the Production of Supplements Enriched with Essential Elements.

PubMed

Rzymski, Piotr; Mleczek, Mirosław; Niedzielski, Przemysław; Siwulski, Marek; Gąsecka, Monika

2016-03-01

Ganoderma lucidum is an important medicinal mushroom species and there is continuous interest in its bioactive properties. This study evaluated whether it may additionally serve as a nutritional supplement for the trace elements: selenium (Se), copper (Cu), and zinc (Zn). Mushrooms were cultivated on substrates enriched with 0.1 to 0.8 mM of inorganic Se alone or in combination with Zn and/or Cu. Supplementation increased accumulation of the elements in fruiting bodies regardless of the applied cultivation model. G. lucidum demonstrated the ability to accumulate significant amounts of organic Se, maximally amounting to (i) over 44 mg/kg when the substrate was supplemented only with Se, (ii) over 20 mg/kg in the Se+Cu model, (iii) over 25 mg/kg in the Se+Zn model, and (iv) 15 mg/kg in the Se+Cu+Zn model. The accumulation of Cu and Zn steadily increased with their initial substrate concentrations. Maximum concentrations found after supplementation with 0.8 mM amounted to over 55 mg/kg (Se+Zn) and 52 mg/kg (Se+Cu+Zn) of Zn, and 29 mg/kg (Se+Cu) and over 31 mg/kg (Se+Cu+Zn) of Cu. The greater the supplemented concentration and number of supplemented elements, the lower the biomass of G. lucidum fruiting bodies. Nevertheless, it still remained high when the substrate was supplemented up to 0.4 mM with each element. These results highlight that G. lucidum can easily incorporate elements from the substrate and that, when biofortified, its dried fruiting bodies may serve as a nutritional source of these essential elements. © 2016 Institute of Food Technologists®

Transparent and conductive indium doped cadmium oxide thin films prepared by pulsed filtered cathodic arc deposition

DOE PAGES

Zhu, Yuankun; Mendelsberg, Rueben J.; Zhu, Jiaqi; ...

2012-11-26

Indium doped cadmium oxide (CdO:In) films with different In concentrations were prepared on low-cost glass substrates by pulsed filtered cathodic arc deposition (PFCAD). In this study, it is shown that polycrystalline CdO:In films with smooth surface and dense structure are obtained. In-doping introduces extra electrons leading to remarkable improvements of electron mobility and conductivity, as well as improvement in the optical transmittance due to the Burstein Moss effect. CdO:In films on glass substrates with thickness near 230 nm show low resistivity of 7.23 x 10 -5 Ωcm, high electron mobility of 142 cm 2/Vs, and mean transmittance over 80% frommore » 500-1250 nm (including the glass substrate). These high quality pulsed arc-grown CdO:In films are potentially suitable for high efficiency multi-junction solar cells that harvest a broad range of the solar spectrum.« less

Preparation and evaluation of nanocellulose-gold nanoparticle nanocomposites for SERS applications.

PubMed

Wei, Haoran; Rodriguez, Katia; Renneckar, Scott; Leng, Weinan; Vikesland, Peter J

2015-08-21

Nanocellulose is of research interest due to its extraordinary optical, thermal, and mechanical properties. The incorporation of guest nanoparticles into nanocellulose substrates enables production of novel nanocomposites with a broad range of applications. In this study, gold nanoparticle/bacterial cellulose (AuNP/BC) nanocomposites were prepared and evaluated for their applicability as surface-enhanced Raman scattering (SERS) substrates. The nanocomposites were prepared by citrate mediated in situ reduction of Au(3+) in the presence of a BC hydrogel at 303 K. Both the size and morphology of the AuNPs were functions of the HAuCl4 and citrate concentrations. At high HAuCl4 concentrations, Au nanoplates form within the nanocomposites and are responsible for high SERS enhancements. At lower HAuCl4 concentrations, uniform nanospheres form and the SERS enhancement is dependent on the nanosphere size. The time-resolved increase in the SERS signal was probed as a function of drying time with SERS 'hot-spots' primarily forming in the final minutes of nanocomposite drying. The application of the AuNP/BC nanocomposites for detection of the SERS active dyes MGITC and R6G as well as the environmental contaminant atrazine is illustrated as is its use under low and high pH conditions. The results indicate the broad applicability of this nanocomposite for analyte detection.

Differences in the response of soil dehydrogenase activity to Cd contamination are determined by the different substrates used for its determination.

PubMed

Tan, Xiangping; Liu, Yanju; Yan, Kaihong; Wang, Ziquan; Lu, Guannan; He, Yike; He, Wenxiang

2017-02-01

Dehydrogenase activity (DHA) is an important indicator of heavy metal toxicity in contaminated soils. Different instances of DHA were determined using various substrates and which could affect the description of heavy metal toxicity. Currently, too few investigations have been done on selecting appropriate substrates. This study employed indoor simulation to determine soil DHA and its response to external cadmium (Cd) using two substrates (TTC and INT). Hormesis for DHA obtained using the TTC method (DHA-TTC) in low Cd concentration was observed which was quickly inhibited in high Cd concentration. While DHA obtained using the INT method (DHA-INT) decreased slowly when Cd concentration increased. The DHA-TTC and DHA-INT in soils at Cd concentration of 500 mg kg -1 decreased 86% and 53%, respectively, compared to the control. The dose-response relationship of Cd to DHA can be well simulated using the logistic model (p < 0.01), which indicated DHA could be used to indicate soil Cd toxicity. Multiple stepwise regression analysis revealed that total organic matter (TOC) is the major factor influencing the toxicity of Cd to DHA-TTC, while TOC, pH and cation exchange capacity (CEC) are major factors influencing the toxicity of Cd to DHA-INT. The different responses of soil DHA-TTC and DHA-INT to Cd are due to the differences in electron transport chain characteristics between TTC and INT, as well as the influence of soil properties. Although both DHA-TTC and DHA-INT can monitor soil Cd contamination, DHA-INT is recommended as a superior bio-indicator to indicate and assess contamination of Cd in soil. Copyright © 2016 Elsevier Ltd. All rights reserved.

Kinetics of thermophilic anaerobes in fixed-bed reactors.

PubMed

Perez, M; Romero, L I; Sales, D

2001-08-01

The main objective of this study is to estimate growth kinetic constants and the concentration of "active" attached biomass in two anaerobic thermophilic reactors which contain different initial sizes of immobilized anaerobic mixed cultures and decompose distillery wastewater. This paper studies the substrate decomposition in two lab-scale fixed-bed reactors operating at batch conditions with corrugated tubes as support media. It can be demonstrated that high micro-organisms-substrate ratios favor the degradation activity of the different anaerobic cultures, allowing the stable operation without lag-phases and giving better quality in effluent. The kinetic parameters obtained--maximum specific growth rates (mu(max)), non-biodegradable substrate (S(NB)) and "active or viable biomass" concentrations (X(V0))--were obtained by applying the Romero kinetic model [L.I. Romero, 1991. Desarrollo de un modelo matemático general para los procesos fermentativos, Cinética de la degradación anaerobia, Ph.D. Thesis, University of Cádiz (Spain), Serv. Pub. Univ. Cádiz], with COD as substrate and methane (CH4) as the main product of the anaerobic process. This method is suitable to calculate and to differentiate the main kinetic parameters of both the total anaerobic mixed culture and the methanogenic population. Comparison of experimental measured concentration of volatile attached solids (VS(att)) in both reactors with the estimated "active" biomass concentrations obtained by applying Romero kinetic model [L.I. Romero, 1991. Desarrollo de un modelo matemático general para los procesos fermentativos, Cinética de la degradación anaerobia, Ph.D. Thesis, University of Cádiz (Spain), Serv. Pub. Univ. Cádiz] shows that a large amount of inert matter is present in the fixed-bed reactor.

Molecular beam epitaxial growth of high-quality InSb on InP and GaAs substrates

NASA Technical Reports Server (NTRS)

Oh, J. E.; Bhattacharya, P. K.; Chen, Y. C.; Tsukamoto, S.

1989-01-01

Epitaxial layers of InSb were grown on InP and GaAs substrates by molecular beam epitaxy. The dependence of the epilayer quality on flux ratio, J sub Sb4/J sub In, was studied. Deviation from an optimum value of J sub Sb4/J sub In (approx. 2) during growth led to deterioration in the surface morphology and the electrical and crystalline qualities of the films. Room temperature electron mobilities as high as 70,000 and 53,000 sq cm /V-s were measured in InSb layers grown on InP and GaAs substrates, respectively. Unlike the previous results, the conductivity in these films is n-type even at T = 13 K, and no degradation of the electron mobility due to the high density of dislocations was observed. The measured electron mobilities (and carrier concentrations) at 77 K in InSb layers grown on InP and GaAs substrates are 110,000 sq cm/V-s (3 x 10(15) cm(-3)) and 55,000 sq cm/V-s (4.95 x 10(15) cm(-3)), respectively, suggesting their application to electronic devices at cryogenic temperatures.

Uniform modeling of bacterial colony patterns with varying nutrient and substrate

NASA Astrophysics Data System (ADS)

Schwarcz, Deborah; Levine, Herbert; Ben-Jacob, Eshel; Ariel, Gil

2016-04-01

Bacteria develop complex patterns depending on growth condition. For example, Bacillus subtilis exhibit five different patterns depending on substrate hardness and nutrient concentration. We present a unified integro-differential model that reproduces the entire experimentally observed morphology diagram at varying nutrient concentrations and substrate hardness. The model allows a comprehensive and quantitative comparison between experimental and numerical variables and parameters, such as colony growth rate, nutrient concentration and diffusion constants. As a result, the role of the different physical mechanisms underlying and regulating the growth of the colony can be evaluated.

Method for sustaining microorganism culture in syngas fermentation process in decreased concentration or absence of various substrates

DOEpatents

Adams, Stephen S.; Scott, Syrona; Ko, Ching-Whan

2015-05-19

The present invention relates to methods for sustaining microorganism culture in a syngas fermentation reactor in decreased concentration or absence of various substrates comprising: adding carbon dioxide and optionally alcohol; maintaining free acetic acid concentrations; and performing the above mentioned steps within specified time.

Production of high molecular weight poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymer by Cupriavidus malaysiensis USMAA1020 utilising substrate with longer carbon chain.

PubMed

Huong, Kai-Hee; Elina, K A R; Amirul, A A

2018-05-01

Long carbon chain alkanediols are used in the production of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)], however these substrates possess high toxicity towards bacterial cells. This study demonstrated the effective utilisation of a long carbon chain alkanediol, namely 1,8-octanediol, to enhance the yield and production of a copolymer with a high molecular weight of over 1000 kDa, which is desirable for novel applications in medical and biopharmaceuticals. The increased PHA content (47-61 wt%) and concentration (1.7-4.5 g/L) was achieved by additional feeding of a combination of C4 substrates at C/N 10, with 1,8-octanediol + γ-butyrolactone producing P(3HB-co-22 mol% 4HB) with a high molecular weight (1060 kDa) and elongation at break of 970%. The DO-stat feeding strategy of C/N 10 has shown an increment of PHA concentration for both carbon combination, 0.45-4.27 g/L and 0.32-3.36 g/L for 1,8-octanediol + sodium 4-hydroxybutyrate (4HB-Na) and 1,8-octanediol + γ-butyrolactone, but with a slight reduction on molecular weight and mechanical strength. Nonetheless, further study revealed that a nitrogen-absence feeding strategy could retain the high molecular weight and elongation at break of the copolymer, and simultaneously improving the overall P(3HB-co-4HB) production. Copyright © 2018 Elsevier B.V. All rights reserved.

Fluorescence polarization immunoassays for monitoring nucleoside triphosphate diphosphohydrolase (NTPDase) activity.

PubMed

Fiene, Amelie; Baqi, Younis; Lecka, Joanna; Sévigny, Jean; Müller, Christa E

2015-01-07

The following members of the ecto-nucleoside triphosphate diphosphohydrolase family, NTPDase1 (CD39), NTPDase-2, -3, and -8, play an important role in purinergic signal transduction by regulating extracellular nucleotide levels. Potent and selective NTPDase inhibitors are required as pharmacological tools and have potential as novel drugs, e.g. for anti-cancer and anti-bacterial therapy. We have developed fast and sensitive NTPDase fluorescence polarization (FP) immunoassays using the natural substrates (ATP or ADP). During the NTPDase1-catalyzed reaction, the substrate is dephosphorylated to ADP which is further dephosphorylated yielding AMP as the final product (by NTPDase1). NTPDase3 and -8 yield AMP and ADP, while NTPDase2 results mainly in the formation of ADP. Direct quantification of the respective product, AMP or ADP, is achieved by displacement of an appropriate fluorescent tracer nucleotide from a specific antibody leading to a change in fluorescence polarization. The assays are highly sensitive and can be performed with low substrate concentrations (20 μM ATP or 10 μM ADP) below the KM values of NTPDases, which simplifies the identification of novel competitive inhibitors. Optimized antibody and enzyme concentrations allow the reproducible detection of 2 μM ADP and 1 μM AMP (at 10% substrate conversion). Validation of the assays yielded excellent Z'-factors greater than 0.70 for all investigated NTPDase subtypes indicating high robustness of the analytical method. Furthermore, we tested a standard inhibitor and performed a first exemplary screening campaign with a library consisting of >400 compounds (Z'-factor: 0.87, hit rate 0.5%). Thereby we demonstrated the suitability of the FP assay for IC50 value determination and high-throughput screening in a 384-well format. The new FP assays were shown to be superior to current standard assays.

Adaptation of continuous biogas reactors operating under wet fermentation conditions to dry conditions with corn stover as substrate.

PubMed

Kakuk, Balázs; Kovács, Kornél L; Szuhaj, Márk; Rákhely, Gábor; Bagi, Zoltán

2017-08-01

Corn stover (CS) is the agricultural by-product of maize cultivation. Due to its high abundance and high energy content it is a promising substrate for the bioenergy sector. However, it is currently neglected in industrial scale biogas plants, because of its slow decomposition and hydrophobic character. To assess the maximum biomethane potential of CS, long-term batch fermentations were carried out with various substrate concentrations and particle sizes for 72 days. In separate experiments we adapted the biogas producing microbial community in wet fermentation arrangement first to the lignocellulosic substrate, in Continuous Stirred Tank Reactor (CSTR), then subsequently, by continuously elevating the feed-in concentration, to dry conditions in solid state fermenters (SS-AD). In the batch tests, the <10 mm fraction of the grinded and sieved CS was amenable for biogasification, but it required 10% more time to produce 90% of the total biomethane yield than the <2 mm sized fraction, although in the total yields there was no significant difference between the two size ranges. We also observed that increasing amount of substrate added to the fermentation lowered the specific methane yield. In the CSTR experiment, the daily substrate loading was gradually increased from 1 to 2 g vs /L/day until the system produced signs of overloading. Then the biomass was transferred to SS-AD reactors and the adaptation process was studied. Although the specific methane yields were lower in the SS-AD arrangement (177 mL CH 4 /g vs in CSTR vs. 105 mL in SS-AD), the benefits of process operational parameters, i.e. lower energy consumption, smaller reactor volume, digestate amount generated and simpler configuration, may compensate the somewhat lower yield. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

The link of feast-phase dissolved oxygen (DO) with substrate competition and microbial selection in PHA production.

PubMed

Wang, Xiaofei; Oehmen, Adrian; Freitas, Elisabete B; Carvalho, Gilda; Reis, Maria A M

2017-04-01

Polyhydroxyalkanoates (PHAs) are biobased and biodegradable polyesters with the potential to replace conventional plastics. Aeration requires large amounts of energy in PHA production by mixed microbial cultures (MMCs), particularly during the feast phase due to substrate uptake. The objective of this study was to investigate the impact of DO concentrations on microbial selection, substrate competition and PHA production performance by MMCs. This represents the first study investigating DO impact on PHA production while feeding the multiple volatile fatty acids (VFAs) typically encountered in real fermented feedstocks, as well as the substrate preferences at different DO levels. Efficient microbial cultures were enriched under both high (3.47 ± 1.12 mg/L) and low (0.86 ± 0.50 mg/L) DO conditions in the feast phase containing mostly the same populations but with different relative abundance. The most abundant microorganisms in the two MMCs were Plasticicumulans, Zoogloea, Paracoccus, and Flavobacterium. Butyrate and valerate were found to be the preferred substrates as compared to acetate and propionate regardless of DO concentrations. In the accumulation step, the PHA storage capacity and yield were less affected by the change of DO levels when applying the culture selected under low DO in the feast phase (PHA storage capacity >60% and yield > 0.9 Cmol PHA/Cmol VFA). A high DO level is required for maximal PHA accumulation rates with the four VFAs (acetate, propionate, butyrate and valerate) present, due to the lower specific uptake rates of acetate and propionate under low DO conditions. However, butyrate and valerate specific uptake rates were less impacted by DO levels and hence low DO for PHA accumulation may be effective when feed is composed of these substrates only. Copyright © 2017 Elsevier Ltd. All rights reserved.

Water on graphene: review of recent progress

NASA Astrophysics Data System (ADS)

Melios, C.; Giusca, C. E.; Panchal, V.; Kazakova, O.

2018-04-01

The sensitivity of graphene to the surrounding environment is given by its π electrons, which are directly exposed to molecules in the ambient air. The high sensitivity of graphene to the local environment has shown to be both advantageous and problematic for graphene-based devices, such as transistors and sensors, where the graphene carrier concentration and mobility changes due to ambient humidity variations. In this review, recent progress is presented in understanding the effects of water on different types of graphene: epitaxially grown and quasi-free standing on SiC(0 0 0 1), grown by chemical vapour deposition and transfered on SiO2, and exfoliated flakes. It is demonstrated that water withdraws electrons from graphene, but the graphene-water interaction highly depends on the thickness, layer stacking, underlying substrate and substrate-induced doping. Moreover, we highlight the importance of clear and unambiguous description of the environmental conditions (i.e. relative humidity) whenever a routine characterisation for carrier concentration and mobility is reported (often presented as a simple figure-of-merit), as these electrical characteristics are highly dependent on the adsorbed molecules and the surrounding environment.

Efficient production of butyric acid from Jerusalem artichoke by immobilized Clostridium tyrobutyricum in a fibrous-bed bioreactor.

PubMed

Huang, Jin; Cai, Jin; Wang, Jin; Zhu, Xiangcheng; Huang, Lei; Yang, Shang-Tian; Xu, Zhinan

2011-02-01

Butyric acid is an important specialty chemical with wide industrial applications. The feasible large-scale fermentation for the economical production of butyric acid requires low-cost substrate and efficient process. In the present study, butyric acid production by immobilized Clostridium tyrobutyricum was successfully performed in a fibrous-bed bioreactor using Jerusalem artichoke as the substrate. Repeated-batch fermentation was carried out to produce butyric acid with a high butyrate yield (0.44 g/g), high productivity (2.75 g/L/h) and a butyrate concentration of 27.5 g/L. Furthermore, fed-batch fermentation using sulfuric acid pretreated Jerusalem artichoke hydrolysate resulted in a high butyric acid concentration of 60.4 g/L, with the yield of 0.38 g/g and the selectivity of ∼ 85.1 (85.1g butyric acid/g acetic acid). Thus, the production of butyric acid from Jerusalem artichoke on a commercial scale could be achieved based on the system developed in this work. Copyright © 2010. Published by Elsevier Ltd.

Water and glucose gradients in the substrate measured with NMR imaging during solid-state fermentation with Aspergillus oryzae.

PubMed

Nagel, Frank-Jan; Van As, Henk; Tramper, Johannes; Rinzema, Arjen

2002-09-20

Gradients inside substrate particles cannot be prevented in solid-state fermentation. These gradients can have a strong effect on the physiology of the microorganisms but have hitherto received little attention in experimental studies. We report gradients in moisture and glucose content during cultivation of Aspergillus oryzae on membrane-covered wheat-dough slices that were calculated from (1)H-NMR images. We found that moisture gradients in the solid substrate remain small when evaporation is minimized. This is corroborated by predictions of a diffusion model. In contrast, strong glucose gradients developed. Glucose concentrations just below the fungal mat remained low due to high glucose uptake rates, but deeper in the matrix glucose accumulated to very high levels. Integration of the glucose profile gave an average concentration close to the measured average content. On the basis of published data, we expect that the glucose levels in the matrix cause a strong decrease in water activity. The results demonstrate that NMR can play an important role in quantitative analysis of water and glucose gradients at the particle level during solid-state fermentation, which is needed to improve our understanding of the response of fungi to this nonconventional fermentation environment. Copyright 2002 Wiley Periodicals, Inc.

Use of fruit residues for pectinase production by Aspergillus flavipes FP-500 and Aspergillus terreus FP-370.

PubMed

Martínez-Trujillo, A; Arreguín-Rangel, L; García-Rivero, M; Aguilar-Osorio, G

2011-08-01

Utilization of fruit residues for pectinase production by two Aspergillus strains for recognizing the effects of some factors during fermentation and describing enzyme production kinetics. Pectinase production on several fruit residues was compared. The effects of three factors on the production of several pectinases were evaluated by a full factorial 2(k) experimental design. Higher activities were obtained on lemon peel. In both strains, acidic pH values and high carbon source concentration favoured exopectinase and endopectinase production, while higher pH values and low carbon source concentration promoted pectin lyase and rhamnogalacturonase production. Unstructured mathematical modelling provided a good description of pectinase production in a submerged batch culture. Fruit residues were very good substrates for pectinase production, and Aspergillus strains used showed a promising performance in submerged fermentation. Mathematical modelling was useful to describe growth and pectinase production. Lemon peel can be used as a substrate to obtain high pectinase titres by Aspergillus flavipes FP-500 and Aspergillus terreus FP-370. The factors that contributed to improve the yield were identified, which supports the possibility of using this substrate in the industrial production of these enzymes. © 2011 The Authors. Letters in Applied Microbiology © 2011 The Society for Applied Microbiology.

Kinetic study on anaerobic oxidation of methane coupled to denitrification.

PubMed

Yu, Hou; Kashima, Hiroyuki; Regan, John M; Hussain, Abid; Elbeshbishy, Elsayed; Lee, Hyung-Sool

2017-09-01

Monod kinetic parameters provide information required for kinetic analysis of anaerobic oxidation of methane coupled to denitrification (AOM-D). This information is critical for engineering AOM-D processes in wastewater treatment facilities. We first experimentally determined Monod kinetic parameters for an AOM-D enriched culture and obtained the following values: maximum specific growth rate (μ max ) 0.121/d, maximum substrate-utilization rate (q max ) 28.8mmol CH 4 /g cells-d, half maximum-rate substrate concentration (K s ) 83μΜ CH 4 , growth yield (Y) 4.76gcells/mol CH 4 , decay coefficient (b) 0.031/d, and threshold substrate concentration (S min ) 28.8μM CH 4 . Clone library analysis of 16S rRNA and mcrA gene fragments suggested that AOM-D reactions might have occurred via the syntrophic interaction between denitrifying bacteria (e.g., Ignavibacterium, Acidovorax, and Pseudomonas spp.) and hydrogenotrophic methanogens (Methanobacterium spp.), supporting reverse methanogenesis-dependent AOM-D in our culture. High μ max and q max , and low K s for the AOM-D enrichment imply that AOM-D could play a significant role in mitigating atmospheric methane efflux. In addition, these high kinetic features suggest that engineered AOM-D systems may provide a sustainable alternative to nitrogen removal in wastewater treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

Using T-RFLP data on denitrifier community composition to inform understanding of denitrification in stream sediments (Invited)

NASA Astrophysics Data System (ADS)

Wang, S.; Somers, K.; Sudduth, E.; Hassett, B.; Bernhardt, E. S.; Urban, D. L.

2010-12-01

We used terminal restriction fragment length polymorphism (T-RFLP), a molecular fingerprinting method, to characterize denitrifier communities in sediments taken from 48 study streams in North Carolina, USA. In addition to characterizing denitrifier communities, we also used denitrification enzyme activity (DEA) assays to measure potential denitrification rates. Due to differences in watershed land-use, study streams covered a gradient of nitrogen and carbon concentrations, as well as a gradient of contaminant loading from stormwater and sanitary sewers. Nitrogen and carbon (i.e., substrate) concentrations are commonly used to make predictions about denitrification rates in streams. Such models do not take into account denitrifier community composition, which may be an important, independent control of denitrification rates, particularly under stressful conditions (e.g., high contaminant loading) that prevent communities from capitalizing on high substrate availability. Our results indicate that substrate availability by itself was a weak predictor of denitrification rates; the same was also true for denitrifier community composition. However, when both factors were incorporated in a multiple regression model, the percent variation explained increased substantially. These findings suggest that T-RFLP, a relatively cost-effective method, can be used to improve our understanding of controls on denitrification rates in streams with varying watershed land-uses.

A simple fabrication of plasmonic surface-enhanced Raman scattering (SERS) substrate for pesticide analysis via the immobilization of gold nanoparticles on UF membrane

NASA Astrophysics Data System (ADS)

Hong, Jangho; Kawashima, Ayato; Hamada, Noriaki

2017-06-01

In this study, we developed a facile fabrication method to access a highly reproducible plasmonic surface enhanced Raman scattering substrate via the immobilization of gold nanoparticles on an Ultrafiltration (UF) membrane using a suction technique. This was combined with a simple and rapid analyte concentration and detection method utilizing portable Raman spectroscopy. The minimum detectable concentrations for aqueous thiabendazole standard solution and thiabendazole in orange extract are 0.01 μg/mL and 0.125 μg/g, respectively. The partial least squares (PLS) regression plot shows a good linear relationship between 0.001 and 100 μg/mL of analyte, with a root mean square error of prediction (RMSEP) of 0.294 and a correlation coefficient (R2) of 0.976 for the thiabendazole standard solution. Meanwhile, the PLS plot also shows a good linear relationship between 0.0 and 2.5 μg/g of analyte, with an RMSEP value of 0.298 and an R2 value of 0.993 for the orange peel extract. In addition to the detection of other types of pesticides in agricultural products, this highly uniform plasmonic substrate has great potential for application in various environmentally-related areas.

Bio-inspired in situ growth of monolayer silver nanoparticles on graphene oxide paper as multifunctional substrate

NASA Astrophysics Data System (ADS)

Li, Shi-Kuo; Yan, You-Xian; Wang, Jin-Long; Yu, Shu-Hong

2013-11-01

In this study, we report a facile bio-inspired method for large-scale preparation of highly dispersed Ag nanoparticles (NPs) on the surface of flexible reduced graphene oxide (rGO) paper with using dopamine (DA) both as a reductant and a surface modifier. Through the self-polymerization of dopamine, free-standing GO paper can be simultaneously reduced and modified with following in situ growth of monolayer Ag NPs on such a substrate. The spherical Ag NPs with an average diameter of 80 nm have a narrow size distribution and tunable cover density. Such a flexible rGO/Ag hybrid paper presents enhanced antibacterial activity against E. coli and a high active and sensitive SERS response toward Rhodamine 6G (R6G) molecules. The detection signals can be obtained while the R6G concentration is as low as to 10-8 M. This work provides a simple strategy for large-scale fabrication of monolayer Ag NPs on flexible rGO paper as a portable antibacterial substrate and a potential SERS substrate for molecular detection applications.In this study, we report a facile bio-inspired method for large-scale preparation of highly dispersed Ag nanoparticles (NPs) on the surface of flexible reduced graphene oxide (rGO) paper with using dopamine (DA) both as a reductant and a surface modifier. Through the self-polymerization of dopamine, free-standing GO paper can be simultaneously reduced and modified with following in situ growth of monolayer Ag NPs on such a substrate. The spherical Ag NPs with an average diameter of 80 nm have a narrow size distribution and tunable cover density. Such a flexible rGO/Ag hybrid paper presents enhanced antibacterial activity against E. coli and a high active and sensitive SERS response toward Rhodamine 6G (R6G) molecules. The detection signals can be obtained while the R6G concentration is as low as to 10-8 M. This work provides a simple strategy for large-scale fabrication of monolayer Ag NPs on flexible rGO paper as a portable antibacterial substrate and a potential SERS substrate for molecular detection applications. Electronic supplementary information (ESI) available: Preparation of GO aqueous colloid solution; XPS spectra of GO paper and PDA modified rGO paper; SEM images of rGO/Ag hybrid paper after immersed in mercaptoethanol solution or in high alkaline solution; photograph and SEM image of pure rGO paper after reaction with AgNO3 solution. SEM image and TEM graph of the pre-synthesized Ag NPs and their SEM images incubated with PDA modified rGO paper; SERS spectra of R6G (1.0 × 10-4 M) molecules before and after cleaning with concentrated hydrochloric acid liquid taken on rGO/Ag hybrid paper obtained by a reaction with 1.0 M AgNO3 solution; SERS spectra of R6G (1.0 × 10-4 M) molecules with different reusable cycles taken on rGO/Ag hybrid paper obtained by a reaction with 1.0 M AgNO3 solution; comparison between different kinds of substrates with the detection limit toward R6G. See DOI: 10.1039/c3nr03857b

A field study to evaluate the impact of different factors on the nutrient pollutant concentrations in green roof runoff.

PubMed

Wang, Xiaochen; Zhao, Xinhua; Peng, Chenrui; Zhang, Xinbo; Wang, Jianghai

2013-01-01

The objectives of this study are to investigate the impact of different factors on the nutrient pollutant concentrations in green roof runoff and to provide reference data for the engineering design of dual substrate layer green roofs. The data were collected from eight different trays under three kinds of artificial rains. The results showed that except for total phosphorus, dual substrate layer green roofs behaved as a sink for most of the nutrient pollutants (significant at p < 0.05), and the first-flush effect did not occur during the 27 simulated rain events. The results also revealed that the concentration of these nutrient pollutants in the runoff strongly depended on the features of the nutrient substrates used in the green roof and the depth of the adsorption substrates. Compared with the influence of the substrates, the influence of the plant density and drainage systems was small.

Method of accurate thickness measurement of boron carbide coating on copper foil

DOEpatents

Lacy, Jeffrey L.; Regmi, Murari

2017-11-07

A method is disclosed of measuring the thickness of a thin coating on a substrate comprising dissolving the coating and substrate in a reagent and using the post-dissolution concentration of the coating in the reagent to calculate an effective thickness of the coating. The preferred method includes measuring non-conducting films on flexible and rough substrates, but other kinds of thin films can be measure by matching a reliable film-substrate dissolution technique. One preferred method includes determining the thickness of Boron Carbide films deposited on copper foil. The preferred method uses a standard technique known as inductively coupled plasma optical emission spectroscopy (ICPOES) to measure boron concentration in a liquid sample prepared by dissolving boron carbide films and the Copper substrates, preferably using a chemical etch known as ceric ammonium nitrate (CAN). Measured boron concentration values can then be calculated.

Adsorption of goethite onto quartz and kaolinite

USGS Publications Warehouse

Goldberg, M.C.; Weiner, Eugene R.; Boymel, P.M.

1984-01-01

The adsorption of colloidal goethite onto quartz and kaolinite substrates has been studied as a function of pH and NaCl concentration. Goethite adsorption was measured quantitatively by Fourier-transform infrared spectroscopy. The results indicate that adsorption onto both substrates is due primarily to coulombic forces; however, the pH dependence of adsorption is very different for the two substrates. This is explained by the fact that the surface charge on quartz is entirely pH-dependent, while kaolinite has surface faces which carry a permanent negative charge. Adsorption of goethite on to kaolinite increases markedly with increasing NaCl concentration, while adsorption onto quartz is relatively independent of NaCl concentration. This can be explained by the influence of NaCl concentration upon the development of surface charge on the substrates. A method is described for separating surface-bound goethite from free goethite.

Regulation of fruit ascorbic acid concentrations during ripening in high and low vitamin C tomato cultivars

PubMed Central

2012-01-01

Background To gain insight into the regulation of fruit ascorbic acid (AsA) pool in tomatoes, a combination of metabolite analyses, non-labelled and radiolabelled substrate feeding experiments, enzyme activity measurements and gene expression studies were carried out in fruits of the ‘low-’ and ‘high-AsA’ tomato cultivars ‘Ailsa Craig’ and ‘Santorini’ respectively. Results The two cultivars exhibited different profiles of total AsA (totAsA, AsA + dehydroascorbate) and AsA accumulation during ripening, but both displayed a characteristic peak in concentrations at the breaker stage. Substrate feeding experiments demonstrated that the L-galactose pathway is the main AsA biosynthetic route in tomato fruits, but that substrates from alternative pathways can increase the AsA pool at specific developmental stages. In addition, we show that young fruits display a higher AsA biosynthetic capacity than mature ones, but this does not lead to higher AsA concentrations due to either enhanced rates of AsA breakdown (‘Ailsa Craig’) or decreased rates of AsA recycling (‘Santorini’), depending on the cultivar. In the later stages of ripening, differences in fruit totAsA-AsA concentrations of the two cultivars can be explained by differences in the rate of AsA recycling activities. Analysis of the expression of AsA metabolic genes showed that only the expression of one orthologue of GDP-L-galactose phosphorylase (SlGGP1), and of two monodehydroascorbate reductases (SlMDHAR1 and SlMDHAR3) correlated with the changes in fruit totAsA-AsA concentrations during fruit ripening in ‘Ailsa Craig’, and that only the expression of SlGGP1 was linked to the high AsA concentrations found in red ripe ‘Santorini’ fruits. Conclusions Results indicate that ‘Ailsa Craig’ and ‘Santorini’ use complementary mechanisms to maintain the fruit AsA pool. In the low-AsA cultivar (‘Ailsa Craig’), alternative routes of AsA biosynthesis may supplement biosynthesis via L-galactose, while in the high-AsA cultivar (‘Santorini’), enhanced AsA recycling activities appear to be responsible for AsA accumulation in the later stages of ripening. Gene expression studies indicate that expression of SlGGP1 and two orthologues of SlMDHAR are closely correlated with totAsA-AsA concentrations during ripening and are potentially good candidates for marker development for breeding and selection. PMID:23245200

Mechanism of papain-catalyzed synthesis of oligo-tyrosine peptides.

PubMed

Mitsuhashi, Jun; Nakayama, Tsutomu; Narai-Kanayama, Asako

2015-01-01

Di-, tri-, and tetra-tyrosine peptides with angiotensin I-converting enzyme inhibitory activity were synthesized by papain-catalyzed polymerization of L-tyrosine ethyl ester in aqueous media at 30 °C. Varying the reaction pH from 6.0 to 7.5 and the initial concentration of the ester substrate from 25 to 100 mM, the highest yield of oligo-tyrosine peptides (79% on a substrate basis) was produced at pH 6.5 and 75 mM, respectively. In the reaction initiated with 100 mM of the substrate, approx. 50% yield of insoluble, highly polymerized peptides accumulated. At less than 15 mM, the reaction proceeded poorly; however, from 30 mM to 120 mM a dose-dependent increase in the consumption rate of the substrate was observed with a sigmoidal curve. Meanwhile, each of the tri- and tetra-tyrosine peptides, even at approx. 5mM, was consumed effectively by papain but was not elongated to insoluble polymers. For deacylation of the acyl-papain intermediate through which a new peptide bond is made, L-tyrosine ethyl ester, even at 5mM, showed higher nucleophilic activity than di- and tri-tyrosine. These results indicate that the mechanism through which papain polymerizes L-tyrosine ethyl ester is as follows: the first interaction between papain and the ester substrate is a rate-limiting step; oligo-tyrosine peptides produced early in the reaction period are preferentially used as acyl donors, while the initial ester substrate strongly contributes as a nucleophile to the elongation of the peptide product; and the balance between hydrolytic fragmentation and further elongation of oligo-tyrosine peptides is dependent on the surrounding concentration of the ester substrate. Copyright © 2015 Elsevier Inc. All rights reserved.

Impact of substrate contamination with mycotoxins, heavy metals and pesticides on the growth performance and composition of black soldier fly larvae (Hermetia illucens) for use in the feed and food value chain.

PubMed

Purschke, Benedict; Scheibelberger, Rafaela; Axmann, Sonja; Adler, Andreas; Jäger, Henry

2017-08-01

Edible insects have emerged as an alternative and sustainable source of high-quality, animal-derived protein and fat for livestock production or direct human nutrition. During the production of insects, substrate quality is a key parameter to assure optimal insect biomass gain as well as the safety of feed and food derived from commercially reared insects. Therefore, the influence of a realistic substrate contamination scenario on growth performance and accumulation behaviour of black soldier fly larvae (BSFL; Hermetia illucens L.) was investigated. Newly hatched larvae were fed on a corn-based substrate spiked with heavy metals (As, Cd, Cr, Hg, Ni, Pb), mycotoxins (aflatoxins B1/B2/G2, deoxynivalenol, ochratoxin A, zearalenone) and pesticides (chlorpyrifos, chlorpyrifos-methyl, pirimiphos-methyl) under defined breeding conditions (10 days, 28°C, 67% relative humidity). The extent of contaminants' bioaccumulation in the larval tissue as well as the effect on growing determinants were examined. The applied heavy metal substrate contamination was shown to impair larval growing indicated by significantly lower post-trial larval mass and feed conversion ratio (FCR). Cd and Pb accumulation factors of 9 and 2, respectively, were determined, while the concentrations of other heavy metals in the larvae remained below the initial substrate concentration. In contrast, mycotoxins and pesticides have neither been accumulated in the larval tissue nor significantly affected the growing determinants in comparison with the control. The use of BSFL as livestock feed requires contaminant monitoring - especially for Cd and Pb - in the substrates as well as in feedstuff containing BSFL to ensure feed and food safety along the value chain.

Carbon Conversion Efficiency and Limits of Productive Bacterial Degradation of Methyl tert-Butyl Ether and Related Compounds▿

PubMed Central

Müller, Roland H.; Rohwerder, Thore; Harms, Hauke

2007-01-01

The utilization of the fuel oxygenate methyl tert-butyl ether (MTBE) and related compounds by microorganisms was investigated in a mainly theoretical study based on the YATP concept. Experiments were conducted to derive realistic maintenance coefficients and Ks values needed to calculate substrate fluxes available for biomass production. Aerobic substrate conversion and biomass synthesis were calculated for different putative pathways. The results suggest that MTBE is an effective heterotrophic substrate that can sustain growth yields of up to 0.87 g g−1, which contradicts previous calculation results (N. Fortin et al., Environ. Microbiol. 3:407-416, 2001). Sufficient energy equivalents were generated in several of the potential assimilatory routes to incorporate carbon into biomass without the necessity to dissimilate additional substrate, efficient energy transduction provided. However, when a growth-related kinetic model was included, the limits of productive degradation became obvious. Depending on the maintenance coefficient ms and its associated biomass decay term b, growth-associated carbon conversion became strongly dependent on substrate fluxes. Due to slow degradation kinetics, the calculations predicted relatively high threshold concentrations, Smin, below which growth would not further be supported. Smin strongly depended on the maximum growth rate μmax, and b and was directly correlated with the half maximum rate-associated substrate concentration Ks, meaning that any effect impacting this parameter would also change Smin. The primary metabolic step, catalyzing the cleavage of the ether bond in MTBE, is likely to control the substrate flux in various strains. In addition, deficits in oxygen as an external factor and in reduction equivalents as a cellular variable in this reaction should further increase Ks and Smin for MTBE. PMID:17220260

Enhancement options for the utilisation of nitrogen rich animal by-products in anaerobic digestion.

PubMed

Resch, Christoph; Wörl, Alexander; Waltenberger, Reinhold; Braun, Rudolf; Kirchmayr, Roland

2011-02-01

This study focuses on the enhancement of an Austrian anaerobic digestion plant at a slaughterhouse site which exclusively uses animal by-products as substrate. High ammonia concentrations from protein degradation cause severe inhibitions of anaerobic microorganisms. For improving the current situation the COD:TKN ratio is widened by (a) ammonia stripping directly out of the process and (b) addition of a C source to the substrate. Different OLR and HRT were tested in continuous experiments to simulate new operating conditions. The results show that the addition of carbon cannot improve fermentation capacity. The reduction of ammonia boosts the degradation: After reduction of TKN from 7.5 to 4.0 g kg(-1) the initially high VFA concentration decreased and the COD degradation was improved by 55.5%. Hence, the implementation of the new N reduction process facilitates either the increase of the OLR by 61% or the reduction of the HRT by 25%. Copyright © 2010 Elsevier Ltd. All rights reserved.

Enhanced biosynthesis of chiral phenyllactic acid from L-phenylalanine through a new whole-cell biocatalyst.

PubMed

Zheng, Zhaojuan; Xia, Meijuan; Fang, Xuchao; Jiang, Ting; Ouyang, Jia

2018-06-22

Phenyllactic acid (PLA) is a high-value compound, which was usually produced by lactic acid bacteria (LAB) as biocatalysts and glucose or phenylpyruvic acid (PPA) as starting materials for PLA synthesis in previous studies. However, the PLA produced using LAB is a racemic mixture. Besides, both glucose and PPA were unsatisfactory substrates, as the former could not produce high concentrations of PLA while the latter is not a renewable and green substrate. To overcome these drawbacks, in this study, a new biotransformation process was developed for chiral PLA production from L-phenylalanine via the intermediate PPA using recombinant Escherichia coli co-expressing L-amino acid deaminase, NAD-dependent L-lactate dehydrogenase or NAD-dependent D-lactate dehydrogenase, and formate dehydrogenase. After optimization, the recombinant E. coli produced L- and D-PLA at concentrations of 59.9 and 60.3 mM in 6 h, respectively. Hence, this process provides an effective and promising alternative method for chiral PLA production.

Screening optimal substrates from Erhai lakeside for Ottelia acuminata (Gagnep.) Dandy, an endangered submerged macrophyte in China.

PubMed

Chen, Shuqin; Chu, Zhaosheng; Zhou, Yunqiao; Li, Qifeng; Wang, Tieyu

2018-05-08

Because of the unstable hydrodynamic conditions in the wild, the endangered aquatic plant should be cultivated first in constructed wetlands for the protection and expansion of germplasm resources. Ottelia acuminata (Gagnep.) Dandy has become extinct in Erhai Lake, Yunnan province, China. In order to optimize substrates for this species to artificial cultivation, the native substrate (sandy soils) and the other three representative ones (red paddy soils, alluvial paddy soils, and purple paddy soils) collected from Erhai lakeside were applied to cultivate O. acuminata for 50 days. Multi indicators, such as antioxidant enzymes activity, malondialdehyde and chlorophyll-α concentration, and relative growth rate of O. acuminata, were discussed and statistically analyzed to classify the substrates. The results suggested that even disregarding the physiology significance of these indicators, hierarchical clustering analysis had high efficiency on optimizing substrates. Although various single indexes suggested different optimal substrates for macrophyte growth, red paddy soil was never excluded out the optimal substrate classes. Further study is needed to assess the substrates optimization functionalities of these indicators. This study offers amounts of physiology data and an effective method to optimize substrates of O. acuminata. It is helpful for environmental scientists and ecological engineers to conduct the similar study on endangered species.

Deep Sequencing of Random Mutant Libraries Reveals the Active Site of the Narrow Specificity CphA Metallo-β-Lactamase is Fragile to Mutations.

PubMed

Sun, Zhizeng; Mehta, Shrenik C; Adamski, Carolyn J; Gibbs, Richard A; Palzkill, Timothy

2016-09-12

CphA is a Zn(2+)-dependent metallo-β-lactamase that efficiently hydrolyzes only carbapenem antibiotics. To understand the sequence requirements for CphA function, single codon random mutant libraries were constructed for residues in and near the active site and mutants were selected for E. coli growth on increasing concentrations of imipenem, a carbapenem antibiotic. At high concentrations of imipenem that select for phenotypically wild-type mutants, the active-site residues exhibit stringent sequence requirements in that nearly all residues in positions that contact zinc, the substrate, or the catalytic water do not tolerate amino acid substitutions. In addition, at high imipenem concentrations a number of residues that do not directly contact zinc or substrate are also essential and do not tolerate substitutions. Biochemical analysis confirmed that amino acid substitutions at essential positions decreased the stability or catalytic activity of the CphA enzyme. Therefore, the CphA active - site is fragile to substitutions, suggesting active-site residues are optimized for imipenem hydrolysis. These results also suggest that resistance to inhibitors targeted to the CphA active site would be slow to develop because of the strong sequence constraints on function.

Foliar manganese accumulation by Maytenus founieri (Celastraceae) in its native New Caledonian habitats: populational variation and localization by X-ray microanalysis.

PubMed

Fernando, D R; Woodrow, I E; Jaffré, T; Dumontet, V; Marshall, A T; Baker, A J M

2008-01-01

Hyperaccumulation by plants is a rare phenomenon that has potential practical benefits. The majority of manganese (Mn) hyperaccumulators discovered to date occur in New Caledonia, and little is known about their ecophysiology. This study reports on natural populations of one such species, the endemic shrub Maytenus founieri. Mean foliar Mn concentrations of two populations growing on ultramafic substrates with varying soil pHs were obtained. Leaf anatomies were examined by light microscopy, while the spatial distributions of foliar Mn in both populations were examined by qualitative scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS). Plants growing on two different substrates were found to have very different mean dry weight (DW) foliar Mn concentrations. Light microscopy showed that the leaves had very distinct thick dermal structures, consisting of multiple layers of large cells in the hypodermis. In vivo X-ray microprobe analyses revealed that, in both populations, Mn sequestration occurred primarily in these dermal tissues. The finding here that foliar Mn is most highly localized in the nonphotosynthetic tissues of M. founieri contrasts with results from similar studies on other woody species that accumulate high Mn concentrations in their shoots.

Stamping SERS for creatinine sensing

NASA Astrophysics Data System (ADS)

Li, Ming; Du, Yong; Zhao, Fusheng; Zeng, Jianbo; Santos, Greggy M.; Mohan, Chandra; Shih, Wei-Chuan

2015-03-01

Urine can be obtained easily, readily and non-invasively. The analysis of urine can provide metabolic information of the body and the condition of renal function. Creatinine is one of the major components of human urine associated with muscle metabolism. Since the content of creatinine excreted into urine is relatively constant, it is used as an internal standard to normalize water variations. Moreover, the detection of creatinine concentration in urine is important for the renal clearance test, which can monitor the filtration function of kidney and health status. In more details, kidney failure can be imminent when the creatinine concentration in urine is high. A simple device and protocol for creatinine sensing in urine samples can be valuable for point-of-care applications. We reported quantitative analysis of creatinine in urine samples by using stamping surface enhanced Raman scattering (S-SERS) technique with nanoporous gold disk (NPGD) based SERS substrate. S-SERS technique enables label-free and multiplexed molecular sensing under dry condition, while NPGD provides a robust, controllable, and high-sensitivity SERS substrate. The performance of S-SERS with NGPDs is evaluated by the detection and quantification of pure creatinine and creatinine in artificial urine within physiologically relevant concentration ranges.

Evaluating the influence of process parameters on soluble microbial products formation using response surface methodology coupled with grey relational analysis.

PubMed

Xu, Juan; Sheng, Guo-Ping; Luo, Hong-Wei; Fang, Fang; Li, Wen-Wei; Zeng, Raymond J; Tong, Zhong-Hua; Yu, Han-Qing

2011-01-01

Soluble microbial products (SMPs) present a major part of residual chemical oxygen demand (COD) in the effluents from biological wastewater treatment systems, and the SMP formation is greatly influenced by a variety of process parameters. In this study, response surface methodology (RSM) coupled with grey relational analysis (GRA) method was used to evaluate the effects of substrate concentration, temperature, NH(4)(+)-N concentration and aeration rate on the SMP production in batch activated sludge reactors. Carbohydrates were found to be the major component of SMP, and the influential priorities of these factors were: temperature>substrate concentration > aeration rate > NH(4)(+)-N concentration. On the basis of the RSM results, the interactive effects of these factors on the SMP formation were evaluated, and the optimal operating conditions for a minimum SMP production in such a batch activated sludge system also were identified. These results provide useful information about how to control the SMP formation of activated sludge and ensure the bioreactor high-quality effluent. Copyright © 2010 Elsevier Ltd. All rights reserved.

Screening of novel bacteria for the 2,3-butanediol production.

PubMed

Kallbach, Malee; Horn, Sonja; Kuenz, Anja; Prüße, Ulf

2017-02-01

Biotechnologically produced 2,3-butanediol (2,3-BDO) is a potential starting material for industrial bulk chemicals such as butadiene or methyl ethyl ketone which are currently produced from fossil feedstocks. So far, the highest 2,3-BDO concentrations have been obtained with risk group 2 microorganisms. In this study, three risk group 1 microorganisms are presented that are so far unknown for an efficient production of 2,3-BDO. The strains Bacillus atrophaeus NRS-213, Bacillus mojavensis B-14698, and Bacillus vallismortis B-14891 were evaluated regarding their ability to produce high 2,3-BDO concentrations with a broad range of different carbon sources. A maximum 2,3-BDO concentration of 60.4 g/L was reached with the strain B. vallismortis B-14891 with an initial glucose concentration of 200 g/L within 55 h in a batch cultivation. Besides glucose, B. vallismortis B-14891 converts 14 different substrates that can be obtained from residual biomass sources to 2,3-BDO. Therefore B. vallismortis B-14891 is a promising candidate for the large-scale production of 2,3-BDO with low-cost substrates.

Atmospheric mercury emissions from mine wastes and surrounding geologically enriched terrains

USGS Publications Warehouse

Gustin, M.S.; Coolbaugh, M.F.; Engle, M.A.; Fitzgerald, B.C.; Keislar, R.E.; Lindberg, S.E.; Nacht, D.M.; Quashnick, J.; Rytuba, J.J.; Sladek, C.; Zhang, H.; Zehner, R.E.

2003-01-01

Waste rock and ore associated with Hg, precious and base metal mining, and their surrounding host rocks are typically enriched in mercury relative to natural background concentrations (<0.1 ??g Hg g-1). Mercury fluxes to the atmosphere from mineralized areas can range from background rates (0-15 ng m-2 h-1) to tens of thousands of ng m-2 h-1. Mercury enriched substrate constitutes a long-term source of mercury to the global atmospheric mercury pool. Mercury emissions from substrate are influenced by light, temperature, precipitation, and substrate mercury concentration, and occur during the day and night. Light-enhanced emissions are driven by two processes: desorption of elemental mercury accumulated at the soil:air interface, and photo reduction of mercury containing phases. To determine the need for and effectiveness of regulatory controls on short-lived anthropogenic point sources the contribution of mercury from geologic non-point sources to the atmospheric mercury pool needs to be quantified. The atmospheric mercury contribution from small areas of mining disturbance with relatively high mercury concentrations are, in general, less than that from surrounding large areas of low levels of mercury enrichment. In the arid to semi-arid west-ern United States volatilization is the primary means by which mercury is released from enriched sites.

Arsenic, Lead, and Cadmium in U.S. Mushrooms and Substrate in Relation to Dietary Exposure.

PubMed

Seyfferth, Angelia L; McClatchy, Colleen; Paukett, Michelle

2016-09-06

Wild mushrooms can absorb high quantities of metal(loid)s, yet the concentration, speciation, and localization of As, Pb, and Cd in cultivated mushrooms, particularly in the United States, are unresolved. We collected 40 samples of 12 types of raw mushrooms from 2 geographic locations that produce the majority of marketable U.S. mushrooms and analyzed the total As, Pb, and Cd content, the speciation and localization of As in select samples, and assessed the metal sources and substrate-to-fruit transfer at one representative farm. Cremini mushrooms contained significantly higher total As concentrations than Shiitake and localized the As differently; while As in Cremini was distributed throughout the fruiting body, it was localized to the hymenophore region in Shiitake. Cd was significantly higher in Royal Trumpet than in White Button, Cremini, and Portobello, while no difference was observed in Pb levels among the mushrooms. Concentrations of As, Pb, and Cd were less than 1 μg g(-1) d.w. in all mushroom samples, and the overall risk of As, Cd, and Pb intake from mushroom consumption is low in the U.S. However, higher percentages of tolerable intake levels are observed when calculating risk based on single serving-sizes or when substrate contains elevated levels of metal(loid)s.

Methylation of 6-mercaptopurine and 6-thioguanine by thiopurine S-methyltransferase. A comparison of activity in red blood cell samples of 199 blood donors.

PubMed

Kröplin, T; Iven, H

2000-07-01

To compare 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG) as substrates for the methylation reaction catalysed by the enzyme thiopurine S-methyltransferase (TPMT). TPMT activity in haemolysed red blood cells of healthy blood donors was determined twice, using the same experimental setting and equal molar concentrations of 6-TG and 6-MP as substrates. After extraction, the reaction products 6-methyl-TG and 6-methyl-MP were quantified using specific high-performance liquid chromatography procedures. The medians of the TPMT activities from 199 blood donors were 54.4 nmol 6-MTG g(-1)Hb h(-1) when measured with 6-TG as the substrate and 35.8 nmol 6-MMP g(-1) Hb h(-1) when measured with 6-MP. The correlation coefficient for the 199 pairs of values was 0.8695. On average, TPMT activity was 34% lower with 6-MP as substrate than with 6-TG as substrate.

Determination of the cellulase activity distribution in Clostridium thermocellum and Caldicellulosiruptor obsidiansis cultures using a fluorescent substrate

DOE PAGES

Morrell-Falvey, Jennifer L.; Elkins, James G.; Wang, Zhi-Wu

2015-05-30

This study took advantage of resorufin cellobioside as a fluorescent substrate to determine the distribution of cellulase activity in cellulosic biomass fermentation systems. Cellulolytic biofilms were found to express nearly four orders greater cellulase activity compared to planktonic cultures of Clostridium thermocellum and Caldicellulosiruptor obsidiansis, which can be primarily attributed to the high cell concentration and surface attachment. The formation of biofilms results in cellulases being secreted close to their substrates, which appears to be an energetically favorable stategy for insoluble substrate utilization. For the same reason, cellulases should be closely associated with the surfaces of suspended cell in solublemore » substrate-fed culture, which has been verified with cellobiose-fed cultures of C. thermocellum and C. obsidiansis. This study addressed the importance of cellulase activity distribution in cellulosic biomass fermentation, and provided theoretical foundation for the leading role of biofilm in cellulose degradation. System optimization and reactor designs that promote biofilmformation in cellulosic biomass hydrolysismay promise an improved cellulosic biofuel process.« less

Glucose Oxidase-Mediated Polymerization as a Platform for Dual-Mode Signal Amplification and Biodetection

PubMed Central

Berron, Brad J; Johnson, Leah M; Ba, Xiao; McCall, Joshua D; Alvey, Nicholas J; Anseth, Kristi S; Bowman, Christopher N

2011-01-01

We report the first use of a polymerization-based ELISA substrate solution employing enzymatically mediated radical polymerization as a dual-mode amplification strategy. Enzymes are selectively coupled to surfaces to generate radicals that subsequently lead to polymerization-based amplification (PBA) and biodetection. Sensitivity and amplification of the polymerization-based detection system were optimized in a microwell strip format using a biotinylated microwell surface with a glucose oxidase (GOx)–avidin conjugate. The immobilized GOx is used to initiate polymerization, enabling the detection of the biorecognition event visually or through the use of a plate reader. Assay response is compared to that of an enzymatic substrate utilizing nitroblue tetrazolium in a simplified assay using biotinylated wells. The polymerization substrate exhibits equivalent sensitivity (2 µg/mL of GOx-avidin) and over three times greater signal amplification than this traditional enzymatic substrate since each radical that is enzymatically generated leads to a large number of polymerization events. Enzyme-mediated polymerization proceeds in an ambient atmosphere without the need for external energy sources, which is an improvement upon previous PBA platforms. Substrate formulations are highly sensitive to both glucose and iron concentrations at the lowest enzyme concentrations. Increases in amplification time correspond to higher assay sensitivities with no increase in non-specific signal. Finally, the polymerization substrate generated a signal to noise ratio of 14 at the detection limit (156 ng/mL) in an assay of transforming growth factor-beta. Biotechnol. Bioeng. 2011; 108:1521–1528. © 2011 Wiley Periodicals, Inc. PMID:21337335

Kinetics and regulation of the myofibrillar adenosine triphosphatase.

PubMed Central

Goodno, C C; Wall, C M; Perry, S V

1978-01-01

1. The steady-state kinetic behaviour of the ATPase (adenosine triphosphatase) of intact myofibrils was studied in the presence of both high and low concentrations of Ca2+ (0.25 mM and less than 10 nM respectively). 2. Kinetic data were collected over the initial linear phase of the assay, which lasts for 20--60s. To obtain consistent data we found it necessary to use either fresh myofibril preparations or preparations that had been stored in the presence of thiol compounds. 3. When assayed in the presence of 0.25 mM-Ca2+, the myofibrillar ATPase obeyed Michaelis-Menten kinetics over the range 0.03--5.0 mM-MgATP (Km 16 +/- 6 micrometer, V 0.4 +/- 0.1 mumol/min per mg). 4. At low Ca2+ concentrations (less than 10 nM) the myofibrillar ATPase displayed pronounced substrate inhibition, which was not observed at high Ca2+ concentrations. Thus increasing the MgATP concentration had the net effect of decreasing the ATPase activity at low Ca2+ relative to that at high Ca2+. This preferential effect of MgATP on the low-Ca2+ ATPase may be important in Ca2+ control. 5. The substrate inhibition that was observed at low Ca2+ was lost on storage or thiol modification of the myofibrils. 6. Under physiological conditions (2 mM-MgATP, I 0.15, pH 7.0), the ATPase of fresh and thiol-protected myofibrils displayed approx. 100-fold activation by Ca2+. PMID:154323

Bioprocess design guided by in situ substrate supply and product removal: process intensification for synthesis of (S)-1-(2-chlorophenyl)ethanol.

PubMed

Schmölzer, Katharina; Mädje, Katharina; Nidetzky, Bernd; Kratzer, Regina

2012-03-01

We report herein on bioprocess development guided by the hydrophobicities of substrate and product. Bioreductions of o-chloroacetophenone are severely limited by instability of the catalyst in the presence of aromatic substrate and (S)-1-(2-chlorophenyl)ethanol. In situ substrate supply and product removal was used to protect the utilized Escherichia coli whole cell catalyst based on Candida tenuis xylose reductase during the reaction. Further engineering at the levels of the catalyst and the reaction media was matched to low substrate concentrations in the aqueous phase. Productivities obtained in aqueous batch reductions were 21-fold improved by addition of 20% (v/v) hexane, NAD(+), expression engineering, cell permeabilization and pH optimization. Reduction of 300 mM substrate was accomplished in 97% yield and use of the co-solvent hexane in subsequent extraction steps led to 88% recovery. Product loss due to high catalyst loading was minimized by using the same extractant in bioreduction and product isolation. Copyright © 2012 Elsevier Ltd. All rights reserved.

Kinetic analysis of dihydroxyacetone production from crude glycerol by immobilized cells of Gluconobacter oxydans MTCC 904.

PubMed

Dikshit, Pritam Kumar; Moholkar, Vijayanand S

2016-09-01

The present study has investigated kinetic features of bioconversion of biodiesel-derived crude glycerol to dihydroxyacetone with immobilized Gluconobacter oxydans cells using modified Haldane substrate-inhibition model. The results have been compared against free cells and pure glycerol. Relative variations in the kinetic parameters KS, KI, Vmax, n and X reveal that immobilized G. oxydans cells (on PU foam substrate) with crude glycerol as substrate give higher order of inhibition (n) and lower maximum reaction velocities (Vmax). These results are essentially implications of substrate transport restrictions across immobilization matrix, which causes retention of substrate in the matrix and reduction in fractional available substrate (X) for the cells. This causes reduction in both KS (substrate concentration at Vmax/2) and KI (inhibition constant) as compared to free cells. For immobilized cells, substrate concentration (Smax) corresponding to Vmax is practically same for both pure and crude glycerol as substrate. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Effect of carbon substrate concentration on N2, N2O, NO, CO2, and CH4 emissions from a paddy soil in anaerobic condition].

PubMed

Chen, Nuo; Liao, Ting-ting; Wang, Rui; Zheng, Xun-hua; Hu, Rong-gui; Butterbach-Bahl, Klaus

2014-09-01

Understanding the effects of carbon and nitrogen substrates concentrations on the emissions of denitrification gases including nitrogen (N2) , nitrous oxide (N2O) and nitric oxide (NO), carbon dioxide (CO2) and methane (CH4) from anaerobic paddy soils is believed to be helpful for development of greenhouse gas mitigation strategies. Moreover, understanding the quantitative dependence of denitrification products compositions on carbon substrate concentration could provide some key parameters or parameterization scheme for developing process-oriented model(s) of nitrogen transformation. Using a silt loam soil collected from a paddy field, we investigated the influence of carbon substrate concentration on the emissions of the denitrification gases, CO2 and CH4 from anaerobically incubated soils by setting two treatments: control (CK) with initial soil nitrate and dissolved organic carbon (DOC) concentrations of ~ 50 mg.kg-1 and -28 mg kg-1 , respectively; and DOC added (C + ) with initial soil nitrate and DOC concentrations of ~50 mg.kg-1 and ~300 mg.kg-1 , respectively. The emissions of denitrification gases, CO2 and CH4, as well as concentrations of carbon and nitrogen substrates for each treatment were dynamically measured, using the gas-flow-soil-core technique and a paralleling substrate monitoring system. The results showed that CH4 emission was not observed in CK treatment while observed in C treatment. Aggregate emission of greenhouse gases for C + treatment was significantly higher comparing with the CK treatment (P <0. 01). The mass fractions of NO, N20 and N2 emissions in total nitrogen gases emissions were approximately 9% , 35% and 56% for CK treatment, respectively; and approximately 31% , 50% and 19% for C+ treatment, respectively, with significant differences between these two treatments (P < 0.01). The results indicated that carbon substrate concentrations can significantly change the composition of nitrogen gas emissions. The results also implicated that organic fertilizer should not be applied to nitrate-rich paddy soils prior to or during flooding so as to mitigate greenhouse gases emissions.

A simple way to synthesize large-scale Cu2O/Ag nanoflowers for ultrasensitive surface-enhanced Raman scattering detection

NASA Astrophysics Data System (ADS)

Zou, Junyan; Song, Weijia; Xie, Weiguang; Huang, Bo; Yang, Huidong; Luo, Zhi

2018-03-01

Here, we report a simple strategy to prepare highly sensitive surface-enhanced Raman spectroscopy (SERS) substrates based on Ag decorated Cu2O nanoparticles by combining two common techniques, viz, thermal oxidation growth of Cu2O nanoparticles and magnetron sputtering fabrication of a Ag nanoparticle film. Methylene blue is used as the Raman analyte for the SERS study, and the substrates fabricated under optimized conditions have very good sensitivity (analytical enhancement factor ˜108), stability, and reproducibility. A linear dependence of the SERS intensities with the concentration was obtained with an R 2 value >0.9. These excellent properties indicate that the substrate has great potential in the detection of biological and chemical substances.

Ag-NP@Ge-nanotaper/Si-micropillar ordered arrays as ultrasensitive and uniform surface enhanced Raman scattering substrates

NASA Astrophysics Data System (ADS)

Liu, Jing; Meng, Guowen; Li, Zhongbo; Huang, Zhulin; Li, Xiangdong

2015-10-01

Surface-enhanced Raman scattering (SERS) is considered to be an excellent candidate for analytical detection schemes, because of its molecular specificity, rapid response and high sensitivity. Here, SERS-substrates of Ag-nanoparticle (Ag-NP) decorated Ge-nanotapers grafted on hexagonally ordered Si-micropillar (denoted as Ag-NP@Ge-nanotaper/Si-micropillar) arrays are fabricated via a combinatorial process of two-step etching to achieve hexagonal Si-micropillar arrays, chemical vapor deposition of flocky Ge-nanotapers on each Si-micropillar and decoration of Ag-NPs onto the Ge-nanotapers through galvanic displacement. With high density three-dimensional (3D) ``hot spots'' created from the large quantities of the neighboring Ag-NPs and large-scale uniform morphology, the hierarchical Ag-NP@Ge-nanotaper/Si-micropillar arrays exhibit strong and reproducible SERS activity. Using our hierarchical 3D SERS-substrates, both methyl parathion (a commonly used pesticide) and PCB-2 (one congener of highly toxic polychlorinated biphenyls) with concentrations down to 10-7 M and 10-5 M have been detected respectively, showing great potential in SERS-based rapid trace-level detection of toxic organic pollutants in the environment.Surface-enhanced Raman scattering (SERS) is considered to be an excellent candidate for analytical detection schemes, because of its molecular specificity, rapid response and high sensitivity. Here, SERS-substrates of Ag-nanoparticle (Ag-NP) decorated Ge-nanotapers grafted on hexagonally ordered Si-micropillar (denoted as Ag-NP@Ge-nanotaper/Si-micropillar) arrays are fabricated via a combinatorial process of two-step etching to achieve hexagonal Si-micropillar arrays, chemical vapor deposition of flocky Ge-nanotapers on each Si-micropillar and decoration of Ag-NPs onto the Ge-nanotapers through galvanic displacement. With high density three-dimensional (3D) ``hot spots'' created from the large quantities of the neighboring Ag-NPs and large-scale uniform morphology, the hierarchical Ag-NP@Ge-nanotaper/Si-micropillar arrays exhibit strong and reproducible SERS activity. Using our hierarchical 3D SERS-substrates, both methyl parathion (a commonly used pesticide) and PCB-2 (one congener of highly toxic polychlorinated biphenyls) with concentrations down to 10-7 M and 10-5 M have been detected respectively, showing great potential in SERS-based rapid trace-level detection of toxic organic pollutants in the environment. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06001j

Plant/soil concentration ratios of SSWRa for contrasting sites around an active U mine-mill

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

Ibrahim, S.A.; Whicker, F.W.

Concentrations of 226Ra were determined in native vegetation and underlying substrate (soil and tailings) at various sites around a conventional open-pit, acid leach U production operation in Wyoming. Plant/soil concentration ratios (CRs) for 226Ra were estimated for various sites, including weathered tailings; a tailings impoundment shoreline; downwind from exposed tailings; a mine overburden reclamation area; and several background locations. Radium-226 concentrations for vegetation and substrate and CR values from the perturbed sites were elevated above background. The highest vegetation concentration (1.3 Bq g-1) was found in a grass which had invaded exposed, weathered tailings. Levels of 226Ra in soil andmore » vegetation and CR values decreased with distance from the tailings impoundment edge. CR values varied significantly among sites, but few differences were found between plant species groups. The observed CR values ranged from 0.07 at the background and reclamation areas to 0.4 downwind from the tailings area. Average CR values for plants growing on exposed tailings and within one meter from the impoundment edge were 0.15 and 0.3, respectively. CR values of 226Ra for plants on tailings substrates were comparatively low in contrast to other radionuclides in the U chain. We speculate that in the case of sulfuric acid leached tailings-derived material, 226Ra is sequestered as sulfate, which is highly insoluble relative to the sulfates of the other elements (e.g., U and Th) resulting in reduced availability for plant uptake.« less

Generic Schemes for Single-Molecule Kinetics. 2: Information Content of the Poisson Indicator.

PubMed

Avila, Thomas R; Piephoff, D Evan; Cao, Jianshu

2017-08-24

Recently, we described a pathway analysis technique (paper 1) for analyzing generic schemes for single-molecule kinetics based upon the first-passage time distribution. Here, we employ this method to derive expressions for the Poisson indicator, a normalized measure of stochastic variation (essentially equivalent to the Fano factor and Mandel's Q parameter), for various renewal (i.e., memoryless) enzymatic reactions. We examine its dependence on substrate concentration, without assuming all steps follow Poissonian kinetics. Based upon fitting to the functional forms of the first two waiting time moments, we show that, to second order, the non-Poissonian kinetics are generally underdetermined but can be specified in certain scenarios. For an enzymatic reaction with an arbitrary intermediate topology, we identify a generic minimum of the Poisson indicator as a function of substrate concentration, which can be used to tune substrate concentration to the stochastic fluctuations and to estimate the largest number of underlying consecutive links in a turnover cycle. We identify a local maximum of the Poisson indicator (with respect to substrate concentration) for a renewal process as a signature of competitive binding, either between a substrate and an inhibitor or between multiple substrates. Our analysis explores the rich connections between Poisson indicator measurements and microscopic kinetic mechanisms.

Quantitative determination of microbial activity and community nutritional status in estuarine sediments: evidence for a disturbance artifact

NASA Technical Reports Server (NTRS)

Findlay, R. H.; Pollard, P. C.; Moriarty, D. J.; White, D. C.

1985-01-01

In estuarine sediments with a high degree of vertical heterogeneity in reduced substrate and terminal electron acceptor concentrations, the method of exposure of the microbiota to labeled substrates can introduce a "disturbance artifact" into measures of metabolic activity. The detection of this artifact is based on quantitative measurement of the relative rates of incorporation of [14C]acetate into phospholipid fatty acids (PLFA) and endogenous storage lipid, poly-beta-hydroxyalkanoate (PHA). Previous studies have shown that PLFA synthesis measures cellular growth and that PHA synthesis measures carbon accumulation (unbalanced growth). The "disturbance artifact" of exposure to [14C]acetate was demonstrated by comparing injection of a core with the usual or pore-water replacement or slurry techniques. Only injection of labeled substrate allowed detection of preassay disturbance of the sediment with a garden rake. The raking increased PLFA synthesis with little effect to differences in concentration or distribution of [14C]acetate in the 10-min incubation. Bioturbation induced by sand dollar feeding in estuarine sediment could be detected in an increased PLFA/PHA ratio which was due to decreased PHA synthesis if the addition of labeled substrate was by the injection technique. Addition of labeled precursors to sediment by slurry or pore-water replacement induces greater disturbance artifacts than injection techniques.

Bioremediation of PAHs contaminated river sediment by an integrated approach with sequential injection of co-substrate and electron acceptor: Lab-scale study.

PubMed

Liu, Tongzhou; Zhang, Zhen; Dong, Wenyi; Wu, Xiaojing; Wang, Hongjie

2017-11-01

In this study, the feasibility of employing an integrated bioremediation approach in contaminated river sediment was evaluated. Sequential addition of co-substrate (acetate) and electron acceptor (NO 3 - ) in a two-phase treatment was capable of effectively removing polycyclic aromatic hydrocarbons (PAHs) in river sediment. The residual concentration of total PAHs decreased to far below effect range low (ERL) value within 91 days of incubation, at which concentration it could rarely pose biological impairment. The biodegradation of high molecular weight PAHs were found to be mainly occurred in the sediment treated with co-substrates (i.e. acetate or methanol), in which acetate was found to be more suitable for PAHs degradation. The role of co-substrates in influencing PAHs biodegradation was tentatively discussed herein. Additionally, the sediment odorous problem and blackish appearance were intensively addressed by NO 3 - injection. The results of this study demonstrated that integrating two or more approaches/processes would be a helpful option in sediment remediation. It can lead to a more effective remediation performance, handle multiple contamination issues, as well as mitigate environmental risks caused by one of the single methods. Copyright © 2017 Elsevier Ltd. All rights reserved.

Identifying and overcoming the effect of mass transfer limitation on decreased yield in enzymatic hydrolysis of lignocellulose at high solid concentrations.

PubMed

Du, Jian; Cao, Yuan; Liu, Guodong; Zhao, Jian; Li, Xuezhi; Qu, Yinbo

2017-04-01

Cellulose conversion decreases significantly with increasing solid concentrations during enzymatic hydrolysis of insoluble lignocellulosic materials. Here, mass transfer limitation was identified as a significant determining factor of this decrease by studying the hydrolysis of delignified corncob residue in shake flask, the most used reaction vessel in bench scale. Two mass transfer efficiency-related factors, mixing speed and flask filling, were shown to correlate closely with cellulose conversion at solid loadings higher than 15% DM. The role of substrate characteristics in mass transfer performance was also significant, which was revealed by the saccharification of two corn stover substrates with different pretreatment methods at the same solid loading. Several approaches including premix, fed-batch operation, and particularly the use of horizontal rotating reactor were shown to be valid in facilitating cellulose conversion via improving mass transfer efficiency at solid concentrations higher than 15% DM. Copyright © 2017 Elsevier Ltd. All rights reserved.

Impact of an acid fungal protease in high gravity fermentation for ethanol production using Indian sorghum as a feedstock.

PubMed

Gohel, V; Duan, G; Maisuria, V B

2013-01-01

This study evaluated the conventional jet cooking liquefaction process followed by simultaneous saccharification and fermentation (SSF) at 30% and 35% dry solids (DS) concentration of Indian sorghum feedstock for ethanol production, with addition of acid fungal protease or urea. To evaluate the efficacy of thermostable α-amylase in liquefaction at 30% and 35% DS concentration of Indian sorghum, liquefact solubility, higher dextrins, and fermentable sugars were analyzed at the end of the process. The liquefact was further subjected to SSF using yeast. In comparison with urea, addition of an acid fungal protease during SSF process was observed to accelerate yeast growth (μ), substrate consumption (Q(s)), ultimately ethanol yield based on substrate (Y(p/s)) and ethanol productivity based on fermentation time (Q(p)). The fermentation efficiency and ethanol recovery were determined for both concentrations of Indian sorghum and found to be increased with use of acid fungal protease in SSF process. Copyright © 2013 American Institute of Chemical Engineers.

On the electrostatic and steric similarity of lactam compounds and the natural substrate for bacterial cell-wall biosynthesis

NASA Astrophysics Data System (ADS)

Frau, J.; Price, S. L.

1996-04-01

Electrostatic and structural properties of a set of β-lactam, γ-lactam and nonlactam compounds have been analyzed and compared with those of a model of the natural substrate d-alanyl- d-alanine for the carboxy- and transpeptidase enzymes. This first comparison of the electrostatic properties has been based on a distributed multipole analysis of high-quality ab initio wave functions of the substrate and potential antibiotics. The electrostatic similarity of the substrate and active compounds is apparent, and contrasts with the electrostatic properties of the noninhibitors. This has been quantified to give a reasonable correlation with the MIC (Minimum Concentration for Inhibition) and with kinetic data (k2/K) in accordance with the model for interaction of the lactam compounds with dd-peptidase. These correlations provide a better prediction of antibacterial activity than purely structural criteria.

Light Trapping with Silicon Light Funnel Arrays

PubMed Central

Nissan, Yuval; Gabay, Tamir; Shalev, Gil

2018-01-01

Silicon light funnels are three-dimensional subwavelength structures in the shape of inverted cones with respect to the incoming illumination. Light funnel (LF) arrays can serve as efficient absorbing layers on account of their light trapping capabilities, which are associated with the presence of high-density complex Mie modes. Specifically, light funnel arrays exhibit broadband absorption enhancement of the solar spectrum. In the current study, we numerically explore the optical coupling between surface light funnel arrays and the underlying substrates. We show that the absorption in the LF array-substrate complex is higher than the absorption in LF arrays of the same height (~10% increase). This, we suggest, implies that a LF array serves as an efficient surface element that imparts additional momentum components to the impinging illumination, and hence optically excites the substrate by near-field light concentration, excitation of traveling guided modes in the substrate, and mode hybridization. PMID:29562685

Wettability of MnxSiyOz by Liquid Zn-Al Alloys

NASA Astrophysics Data System (ADS)

Kim, Yunkyum; Shin, Minsoo; Tang, Chengying; Lee, Joonho

2010-08-01

The wettability of MnxSiyOz by liquid Zn-Al alloys was investigated to obtain basic information on the coating properties of high-strength steels with surface oxides in the hot-dip galvanizing process. In this study, the contact angles of liquid Zn-Al alloys (Al concentrations were 0.12 and 0.23 wt pct) on four different MnxSiyOz oxides, namely MnO, MnSiO3, Mn2SiO4, and SiO2, were measured with the dispensed drop method. The contact angle did not change across time. With an increasing Al concentration, the contact angle was slightly decreased for MnO and Mn2SiO4, but there was no change for MnSiO3 and SiO2. With an increasing SiO2 content, the contact angle gradually increased by 54 wt pct to form MnSiO3, and for pure SiO2 substrate, the contact angle decreased again. Consequently, the MnSiO3 substrate showed the worst wettability among the four tested oxide substrates.

Growth of the extremophilic Deinococcus geothermalis DSM 11302 using co-substrate fed-batch culture.

PubMed

Bornot, Julie; Molina-Jouve, Carole; Uribelarrea, Jean-Louis; Gorret, Nathalie

2014-02-01

Deinococcus geothermalis metabolism has been scarcely studied to date, although new developments on its utilization for bioremediation have been carried out. So, large-scale production of this strain and a better understanding of its physiology are required. A fed-batch experiment was conducted to achieve a high cell density non-limiting culture of D. geothermalis DSM 11302. A co-substrate nutritional strategy using glucose and yeast extract was carried out in a 20-L bioreactor in order to maintain a non-limited growth at a maximal growth rate of 1 h(-1) at 45 °C. Substrate supplies were adjusted by monitoring online culture parameters and physiological data (dissolved oxygen, gas analyses, respiratory quotient, biomass concentration). The results showed that yeast extract could serve as both carbon and nitrogen sources, although glucose and ammonia were consumed too. Yeast extract carbon-specific uptake rate reached a value 4.5 times higher than glucose carbon-specific uptake rate. Cell concentration of 9.6 g L(-1) dry cell weight corresponding to 99 g of biomass was obtained using glucose and yeast extract as carbon and nitrogen sources.

Nanoscale Electrostructural Characterization of Compositionally Graded Al(x)Ga(1-x)N Heterostructures on GaN/Sapphire (0001) Substrate.

PubMed

Kuchuk, Andrian V; Lytvyn, Petro M; Li, Chen; Stanchu, Hryhorii V; Mazur, Yuriy I; Ware, Morgan E; Benamara, Mourad; Ratajczak, Renata; Dorogan, Vitaliy; Kladko, Vasyl P; Belyaev, Alexander E; Salamo, Gregory G

2015-10-21

We report on AlxGa1-xN heterostructures resulting from the coherent growth of a positive then a negative gradient of the Al concentration on a [0001]-oriented GaN substrate. These polarization-doped p-n junction structures were characterized at the nanoscale by a combination of averaging as well as depth-resolved experimental techniques including: cross-sectional transmission electron microscopy, high-resolution X-ray diffraction, Rutherford backscattering spectrometry, and scanning probe microscopy. We observed that a small miscut in the substrate orientation along with the accumulated strain during growth led to a change in the mosaic structure of the AlxGa1-xN film, resulting in the formation of macrosteps on the surface. Moreover, we found a lateral modulation of charge carriers on the surface which were directly correlated with these steps. Finally, using nanoscale probes of the charge density in cross sections of the samples, we have directly measured, semiquantitatively, both n- and p-type polarization doping resulting from the gradient concentration of the AlxGa1-xN layers.

Gold nanochestnut arrays as ultra-sensitive SERS substrate for detecting trace pesticide residue.

PubMed

Geng, Fei; Zhao, Huaping; Fu, Qun; Mi, Yan; Miao, Likun; Li, Wei; Dong, Yulian; Wu, Minghong; Lei, Yong

2018-07-20

In comparison to conventional spectroscopic techniques based on chromatography, surface-enhanced Raman spectroscopy (SERS) enables the rapid identification and detection of trace pesticide residues present in trace amounts in the environment and foods. Herein, a facile approach to fabricate unique gold nanochestnuts (GNCs) as an ultra-sensitive SERS substrate for detecting trace pesticide residues has been developed based on anodic aluminum oxide (AAO) templates. The GNCs are synthesized through the galvanic replacement of Ag on the top of Ni nanorod arrays. The as-prepared GNCs have well-controlled structural parameters, and importantly have unique anisotropic morphologies that benefit the enhancement in SERS performance. As a result, rhodamine 6 G (R6G) can be efficiently detected with GNCs as the SERS substrate even with a concentration of only 10 -12 M, and the Raman enhancement factor reaches up to 5.4 × 10 9 at this concentration. Further SERS measurement of thiram indicates a remarkable SERS-active sensitivity of the as-prepared GNCs with a detection limit of thiram up to 10 -14 M. The GNCs also exhibit a high signal-to-noise ratio.

Effect of low-oxygen-concentration layer on iron gettering capability of carbon-cluster ion-implanted Si wafer for CMOS image sensors

NASA Astrophysics Data System (ADS)

Onaka-Masada, Ayumi; Nakai, Toshiro; Okuyama, Ryosuke; Okuda, Hidehiko; Kadono, Takeshi; Hirose, Ryo; Koga, Yoshihiro; Kurita, Kazunari; Sueoka, Koji

2018-02-01

The effect of oxygen (O) concentration on the Fe gettering capability in a carbon-cluster (C3H5) ion-implanted region was investigated by comparing a Czochralski (CZ)-grown silicon substrate and an epitaxial growth layer. A high Fe gettering efficiency in a carbon-cluster ion-implanted epitaxial growth layer, which has a low oxygen region, was observed by deep-level transient spectroscopy (DLTS) and secondary ion mass spectroscopy (SIMS). It was demonstrated that the amount of gettered Fe in the epitaxial growth layer is approximately two times higher than that in the CZ-grown silicon substrate. Furthermore, by measuring the cathodeluminescence, the number of intrinsic point defects induced by carbon-cluster ion implantation was found to differ between the CZ-grown silicon substrate and the epitaxial growth layer. It is suggested that Fe gettering by carbon-cluster ion implantation comes through point defect clusters, and that O in the carbon-cluster ion-implanted region affects the formation of gettering sinks for Fe.

Effect of cost-effective substrates on growth cycle and yield of lingzhi or reishi medicinal mushroom, Ganoderma lucidum (higher Basidiomycetes) from Northwestern Himalaya (India).

PubMed

Mehta, Sheetal; Jandaik, Savita; Gupta, Dharmesh

2014-01-01

To find a cost-effective alternative substrate, the medicinal mushroom Ganoderma lucidum was grown on sawdusts of sheesham, mango, and poplar. Optimum spawn level was determined by spawning in substrates at various levels (1, 2, 3, and 4%). To determine the effect of supplementation, substrates were supplemented with wheat bran, rice bran and corn flour at different concentrations (10, 20, and 30%). Duration of growth cycle, mushroom yield, and biological efficiency data were recorded. Among substrates, mango sawdust was superior, with 1.5-fold higher yields than poplar sawdust, which was the least suitable. However with respect to fructification, mango sawdust produced the first primordia earlier (21±1 days) compared with the other investigated substrates. 3% spawn level was found to be optimal irrespective of the substrate. Yield and biological efficiency (BE) were maximally enhanced by supplementation with wheat bran, whereas rice bran was the least suitable supplement among those tested. Growth cycle shortened and mushroom yield increased to a maximum at the 20% level of supplements. Mango sawdust in combination with 20% wheat bran, if spawned at the 3% level, resulted in a high yield (BE = 58.57%).

Biomimetic nanocoatings with exceptional mechanical, barrier, and flame-retardant properties from large-scale one-step coassembly

PubMed Central

Ding, Fuchuan; Liu, Jingjing; Zeng, Songshan; Xia, Yan; Wells, Kacie M.; Nieh, Mu-Ping; Sun, Luyi

2017-01-01

Large-scale biomimetic organic/inorganic hybrid nanocoatings with a nacre-like microstructure were prepared via a facile coassembly process. Different from conventional polymer nanocomposites, these nanocoatings contain a high concentration of nanosheets, which can be well aligned along the substrate surface. Moreover, the nanosheets and polymer matrix can be chemically co–cross-linked. As a result, the nanocoatings exhibit exceptional mechanical properties (high stiffness and strength), barrier properties (to both oxygen and water vapor), and flame retardancy, but they are also highly transparent (maintaining more than 85% of their original transmittance to visible light). The nanocoatings can be applied to various substrates and regular or irregular surfaces (for example, films and foams). Because of their excellent performance and high versatility, these nanocoatings are expected to find widespread application. PMID:28776038

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.

Substrate nitridation induced modulations in transport properties of wurtzite GaN/p-Si (100) heterojunctions grown by molecular beam epitaxy

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

Bhat, Thirumaleshwara N.; Rajpalke, Mohana K.; Krupanidhi, S. B.

Phase pure wurtzite GaN films were grown on Si (100) substrates by introducing a silicon nitride layer followed by low temperature GaN growth as buffer layers. GaN films grown directly on Si (100) were found to be phase mixtured, containing both cubic ({beta}) and hexagonal ({alpha}) modifications. The x-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) spectroscopy studies reveal that the significant enhancement in the structural as well as in the optical properties of GaN films grown with silicon nitride buffer layer grown at 800 deg. C when compared to the samples grown in the absence of silicon nitridemore » buffer layer and with silicon nitride buffer layer grown at 600 deg. C. Core-level photoelectron spectroscopy of Si{sub x}N{sub y} layers reveals the sources for superior qualities of GaN epilayers grown with the high temperature substrate nitridation process. The discussion has been carried out on the typical inverted rectification behavior exhibited by n-GaN/p-Si heterojunctions. Considerable modulation in the transport mechanism was observed with the nitridation conditions. The heterojunction fabricated with the sample of substrate nitridation at high temperature exhibited superior rectifying nature with reduced trap concentrations. Lowest ideality factors ({approx}1.5) were observed in the heterojunctions grown with high temperature substrate nitridation which is attributed to the recombination tunneling at the space charge region transport mechanism at lower voltages and at higher voltages space charge limited current conduction is the dominating transport mechanism. Whereas, thermally generated carrier tunneling and recombination tunneling are the dominating transport mechanisms in the heterojunctions grown without substrate nitridation and low temperature substrate nitridation, respectively.« less

Enzymatic hydrolysis of lignocellulosic biomass by Kitasatospora sp. to produce xylo-oligosaccharides (XOS)

NASA Astrophysics Data System (ADS)

Rahmani, Nanik; Jannah, Alifah Mafatikhul; Lisdiyanti, Puspita; Prasetya, Bambang; Yopi

2017-11-01

The optimizations of enzymatic hydrolysis to produce of xylo-oligosaccharides (XOs) from three different lignocellulosic biomasses were investigated. Sugarcane bagasse, oil palm empty fruit bunch, and rice straw contain rich hemicelluloses especially hetero-xylan which can be hydrolyzes by endo-xylanase enzyme. Enzymatic hydrolysis of sugarcane bagasse by endo-xylanase from Kitasatospora sp. was optimum at temperature hydrolysis 30 °C using 16 U of enzyme concentrations and 4 % substrate concentrations, while oil palm empty fruit bunchwas optimum at temperature hydrolysis 30 °C using 16 U of enzyme concentrations and 5 % substrate concentrations, and rice straw was optimum at 40 °C temperature hydrolysis using 16 U of enzyme concentrations and 4 % substrate concentrations. The hydrolysis products were analyzed by TLC and HPLC. The main product hydrolysis for sugarcane bagasse, oil palm empty fruit bunch and rice straw are xylobiose.

Effects of wheat dried distillers' grains with solubles and cinnamaldehyde on in vitro fermentation and protein degradation using the Rusitec technique.

PubMed

Lia, Yangling; He, Maolong; Li, Chun; Forster, Robert; Beauchemin, Karen Anne; Yang, Wenzhu

2012-04-01

This study was conducted to evaluate the effect of wheat dried distillers' grains with solubles (DDGS) and cinnamaldehyde (CIN) on in vitro fermentation and microbial profiles using the rumen simulation technique. The control substrate (10% barley silage, 85% barley grain and 5% supplement, on dry matter basis) and the wheat DDGS substrate (30% wheat DDGS replaced an equal portion of barley grain) were combined with 0 and 300 mg CIN/l of culture fluid. The inclusion of DDGS increased (p < 0.05) the concentration of volatile fatty acids (VFA) and the molar proportion of acetate and propionate. Dry matter disappearance (p = 0.03) and production of bacterial protein (p < 0.01) were greater, whereas the disappearances of crude protein (CP) and neutral detergent fibre were less (p < 0.01) for the DDGS than for the control substrate. With addition of CIN, concentration of total VFA decreased and fermentation pattern changed to greater acetate and less propionate proportions (p < 0.01). The CIN reduced (p < 0.01) methane production and CP degradability. The copy numbers of Fibrobacter, Prevotella and Archaea were not affected by DDGS but were reduced (p < 0.05) by CIN. The results indicate that replacing barley grain by DDGS increased nutrient fermentability and potentially increase protein flows to the intestine. Supplementation of high-grain substrates with CIN reduced methane production and potentially increased the true protein reaching the small intestine; however, overall reduction of feed fermentation may lower the feeding value of a high-grain diet.

Boron accumulation and toxicity in hybrid poplar (Populus nigra × euramericana).

PubMed

Rees, Rainer; Robinson, Brett H; Menon, Manoj; Lehmann, Eberhard; Günthardt-Goerg, Madeleine S; Schulin, Rainer

2011-12-15

Poplars accumulate high B concentrations and are thus used for the phytomanagement of B contaminated soils. Here, we performed pot experiments in which Populus nigra × euramericana were grown on a substrate with B concentrations ranging from 13 to 280 mg kg(-1) as H(3)BO(3). Salix viminalis, Brassica juncea, and Lupinus albus were grown under some growing conditions for comparison. Poplar growth was unaffected at soil B treatment levels up to 93 mg kg(-1). Growth was progressively reduced at levels of 168 and 280 mg kg(-1). None of the other species survived at these substrate B levels. At leaf B concentrations <900 mg kg(-1) only <10% of the poplar leaf area showed signs of toxicity. Neutron radiography revealed that chlorotic leaf tissues had B concentrations of 1000-2000 mg kg(-1), while necrotic tissues had >2000 mg kg(-1). Average B concentrations of up to 3500 mg kg(-1) were found in leaves, while spots within leaves had concentrations >7000 mg kg(-1), showing that B accumulation in leaf tissue continued even after the onset of necrosis. The B accumulation ability of P. nigra × euramericana is associated with B hypertolerance in the living tissue and storage of B in dead leaf tissue.

Evaluation of cotton stalk hydrolysate for xylitol production.

PubMed

Sapcı, Burcu; Akpinar, Ozlem; Bolukbasi, Ufuk; Yilmaz, Levent

2016-07-03

Cotton stalk is a widely distributed and abundant lignocellulosic waste found in Turkey. Because of its rich xylose content, it can be a promising source for the production of xylitol. Xylitol can be produced by chemical or biotechnological methods. Because the biotechnological method is a simple process with great substrate specificity and low energy requirements, it is more of an economic alternative for the xylitol production. This study aimed to use cotton stalk for the production of xylitol with Candida tropicalis Kuen 1022. For this purpose, the combined effects of different oxygen concentration, inoculum level and substrate concentration were investigated to obtain high xylitol yield and volumetric xylitol production rate. Candida tropicalis Kuen 1022 afforded different concentrations of xylitol depending on xylose concentration, inoculum level, and oxygen concentration. The optimum xylose, yeast concentration, and airflow rate for cotton stalk hydrolysate were found as 10.41 g L(-1), 0.99 g L(-1), and 1.02 vvm, respectively, and under these conditions, xylitol yield and volumetric xylitol production rate were obtained as 36% and 0.06 g L(-1) hr(-1), respectively. The results of this study show that cotton stalk can serve as a potential renewable source for the production of xylitol.

Role of sucrose phosphate synthase in sucrose biosynthesis in ripening bananas and its relationship to the respiratory climacteric.

PubMed

Hubbard, N L; Pharr, D M; Huber, S C

1990-09-01

During ripening of bananas (Musa spp. [AAA group, Cavendish subgroup]), there is a massive conversion of starch to sucrose. Also during ripening there is a rise in respiration known as the respiratory climacteric. In this study changes in carbohydrate content, activities of starch and sucrose metabolizing enzymes, and respiration were measured to assess their potential interrelationships. Sucrose phosphate synthase activity increased dramatically during the first 4 days after initiation of ripening by ethylene treatment. Starch concentration decreased and sucrose concentration increased during this time period. Developmental changes in sucrose phosphate synthase activity were measured with limiting substrate (plus Pi) and saturating substrate concentrations. Activities were not parallel under the two assay conditions, providing tentative evidence that kinetically different forms of the enzyme may exist at different stages of ripening. Sucrose accumulation rate was most highly correlated with sucrose phosphate synthase activity assayed with limiting substrate concentrations (plus Pi). The cumulative amount of CO(2) respired during ripening was positively correlated with sugar accumulation (R(2) = 0.97). From this linear regression it was calculated that a constant 0.605 millimoles of CO(2) was evolved per mole of sucrose formed throughout ripening. Using this quantity, the percentage of the total respiratory ATP produced which was required for the conversion of starch to sucrose was calculated assuming different models for carbon export from the amyloplast. The results suggest that sucrose biosynthesis during ripening constitutes a significant sink for respiratory ATP.

Role of Sucrose Phosphate Synthase in Sucrose Biosynthesis in Ripening Bananas and Its Relationship to the Respiratory Climacteric 1

PubMed Central

Hubbard, Natalie L.; Pharr, D. Mason; Huber, Steven C.

1990-01-01

During ripening of bananas (Musa spp. [AAA group, Cavendish subgroup]), there is a massive conversion of starch to sucrose. Also during ripening there is a rise in respiration known as the respiratory climacteric. In this study changes in carbohydrate content, activities of starch and sucrose metabolizing enzymes, and respiration were measured to assess their potential interrelationships. Sucrose phosphate synthase activity increased dramatically during the first 4 days after initiation of ripening by ethylene treatment. Starch concentration decreased and sucrose concentration increased during this time period. Developmental changes in sucrose phosphate synthase activity were measured with limiting substrate (plus Pi) and saturating substrate concentrations. Activities were not parallel under the two assay conditions, providing tentative evidence that kinetically different forms of the enzyme may exist at different stages of ripening. Sucrose accumulation rate was most highly correlated with sucrose phosphate synthase activity assayed with limiting substrate concentrations (plus Pi). The cumulative amount of CO2 respired during ripening was positively correlated with sugar accumulation (R2 = 0.97). From this linear regression it was calculated that a constant 0.605 millimoles of CO2 was evolved per mole of sucrose formed throughout ripening. Using this quantity, the percentage of the total respiratory ATP produced which was required for the conversion of starch to sucrose was calculated assuming different models for carbon export from the amyloplast. The results suggest that sucrose biosynthesis during ripening constitutes a significant sink for respiratory ATP. PMID:16667688

Trans-membrane transport of n-octadecane by Pseudomonas sp. DG17.

PubMed

Hua, Fei; Wang, Hong Qi; Li, Yi; Zhao, Yi Cun

2013-12-01

The trans-membrane transport of hydrocarbons is an important and complex aspect of the process of biodegradation of hydrocarbons by microorganisms. The mechanism of transport of (14)C n-octadecane by Pseudomonas sp. DG17, an alkane-degrading bacterium, was studied by the addition of ATP inhibitors and different substrate concentrations. When the concentration of n-octadecane was higher than 4.54 μmol/L, the transport of (14)C n-octadecane was driven by a facilitated passive mechanism following the intra/extra substrate concentration gradient. However, when the cells were grown with a low concentration of the substrate, the cellular accumulation of n-octadecane, an energy-dependent process, was dramatically decreased by the presence of ATP inhibitors, and n-octadecane accumulation continually increased against its concentration gradient. Furthermore, the presence of non-labeled alkanes blocked (14)C n-octadecane transport only in the induced cells, and the trans-membrane transport of n-octadecane was specific with an apparent dissociation constant K t of 11.27 μmol/L and V max of 0.96 μmol/min/mg protein. The results indicated that the trans-membrane transport of n-octadecane by Pseudomonas sp. DG17 was related to the substrate concentration and ATP.

Hybrid Integration of III-V Solar Microcells for High Efficiency Concentrated Photovoltaic Modules

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

Tauke-Pedretti, Anna; Cederberg, Jeffery; Cruz-Campa, Jose Luis

The design, fabrication and performance of InGaAs and InGaP/GaAs microcells are presented. These cells are integrated with a Si wafer providing a path for insertion in hybrid concentrated photovoltaic modules. Comparisons are made between bonded cells and cells fabricated on their native wafer. The bonded cells showed no evidence of degradation in spite of the integration process which involved significant processing including the removal of the III-V substrate. Results from a number of hybrid cell configurations were reported. These cells employed integration techniques including wafer level bonding of processed cells and solder bonding of the cells. Lastly, the cells themselvesmore » showed evidence of degradation in spite of the integration process, which involved significant processing including the removal of the III-V substrate.« less

Hybrid Integration of III-V Solar Microcells for High Efficiency Concentrated Photovoltaic Modules

DOE PAGES

Tauke-Pedretti, Anna; Cederberg, Jeffery; Cruz-Campa, Jose Luis; ...

2018-03-09

The design, fabrication and performance of InGaAs and InGaP/GaAs microcells are presented. These cells are integrated with a Si wafer providing a path for insertion in hybrid concentrated photovoltaic modules. Comparisons are made between bonded cells and cells fabricated on their native wafer. The bonded cells showed no evidence of degradation in spite of the integration process which involved significant processing including the removal of the III-V substrate. Results from a number of hybrid cell configurations were reported. These cells employed integration techniques including wafer level bonding of processed cells and solder bonding of the cells. Lastly, the cells themselvesmore » showed evidence of degradation in spite of the integration process, which involved significant processing including the removal of the III-V substrate.« less

Development of High-Performance eSWIR HgCdTe-Based Focal-Plane Arrays on Silicon Substrates

NASA Astrophysics Data System (ADS)

Park, J. H.; Pepping, J.; Mukhortova, A.; Ketharanathan, S.; Kodama, R.; Zhao, J.; Hansel, D.; Velicu, S.; Aqariden, F.

2016-09-01

We report the development of high-performance and low-cost extended short-wavelength infrared (eSWIR) focal-plane arrays (FPAs) fabricated from molecular beam epitaxial (MBE)-grown HgCdTe on Si-based substrates. High-quality n-type eSWIR HgCdTe (cutoff wavelength ˜2.68 μm at 77 K, electron carrier concentration 5.82 × 1015 cm-3) layers were grown on CdTe/Si substrates by MBE. High degrees of uniformity in composition and thickness were demonstrated over three-inch areas, and low surface defect densities (voids 9.56 × 101 cm-2, micro-defects 1.67 × 103 cm-2) were measured. This material was used to fabricate 320 × 256 format, 30 μm pitch FPAs with a planar device architecture using arsenic implantation to achieve p-type doping. The dark current density of test devices showed good uniformity between 190 K and room temperature, and high-quality eSWIR imaging from hybridized FPAs was obtained with a median dark current density of 2.63 × 10-7 A/cm2 at 193 K with a standard deviation of 1.67 × 10-7 A/cm2.

Substrate mass transfer: analytical approach for immobilized enzyme reactions

NASA Astrophysics Data System (ADS)

Senthamarai, R.; Saibavani, T. N.

2018-04-01

In this paper, the boundary value problem in immobilized enzyme reactions is formulated and approximate expression for substrate concentration without external mass transfer resistance is presented. He’s variational iteration method is used to give approximate and analytical solutions of non-linear differential equation containing a non linear term related to enzymatic reaction. The relevant analytical solution for the dimensionless substrate concentration profile is discussed in terms of dimensionless reaction parameters α and β.

Hsp70 displaces small heat shock proteins from aggregates to initiate protein refolding.

PubMed

Żwirowski, Szymon; Kłosowska, Agnieszka; Obuchowski, Igor; Nillegoda, Nadinath B; Piróg, Artur; Ziętkiewicz, Szymon; Bukau, Bernd; Mogk, Axel; Liberek, Krzysztof

2017-03-15

Small heat shock proteins (sHsps) are an evolutionary conserved class of ATP-independent chaperones that protect cells against proteotoxic stress. sHsps form assemblies with aggregation-prone misfolded proteins, which facilitates subsequent substrate solubilization and refolding by ATP-dependent Hsp70 and Hsp100 chaperones. Substrate solubilization requires disruption of sHsp association with trapped misfolded proteins. Here, we unravel a specific interplay between Hsp70 and sHsps at the initial step of the solubilization process. We show that Hsp70 displaces surface-bound sHsps from sHsp-substrate assemblies. This Hsp70 activity is unique among chaperones and highly sensitive to alterations in Hsp70 concentrations. The Hsp70 activity is reflected in the organization of sHsp-substrate assemblies, including an outer dynamic sHsp shell that is removed by Hsp70 and a stable core comprised mainly of aggregated substrates. Binding of Hsp70 to the sHsp/substrate core protects the core from aggregation and directs sequestered substrates towards refolding pathway. The sHsp/Hsp70 interplay has major impact on protein homeostasis as it sensitizes substrate release towards cellular Hsp70 availability ensuring efficient refolding of damaged proteins under favourable folding conditions. © 2017 The Authors.

Functional test of a Radon sensor based on a high-resistivity-silicon BJT detector

NASA Astrophysics Data System (ADS)

Dalla Betta, G. F.; Tyzhnevyi, V.; Bosi, A.; Bonaiuti, M.; Angelini, C.; Batignani, G.; Bettarini, S.; Bosi, F.; Forti, F.; Giorgi, M. A.; Morsani, F.; Paoloni, E.; Rizzo, G.; Walsh, J.; Lusiani, A.; Ciolini, R.; Curzio, G.; D'Errico, F.; Del Gratta, A.; Bidinelli, L.; Rovati, L.; Saguatti, D.; Verzellesi, G.; Bosisio, L.; Rachevskaia, I.; Boscardin, M.; Giacomini, G.; Picciotto, A.; Piemonte, C.; Zorzi, N.; Calamosca, M.; Penzo, S.; Cardellini, F.

2013-08-01

A battery-powered, wireless Radon sensor has been designed and realized using a BJT, fabricated on a high-resistivity-silicon substrate, as a radiation detector. Radon daughters are electrostatically collected on the detector surface. Thanks to the BJT internal amplification, real-time α particle detection is possible using simple readout electronics, which records the particle arrival time and charge. Functional tests at known Radon concentrations, demonstrated a sensitivity up to 4.9 cph/(100 Bq/m3) and a count rate of 0.05 cph at nominally-zero Radon concentration.

Conceptual techniques for reducing parasitic current gain of lateral pnp transistors

NASA Technical Reports Server (NTRS)

Gallagher, R. C.; Scott, J. M.

1969-01-01

Two techniques have been conceptually proposed as possible means of reducing parasitic beta in lateral p-n-p transistors. One method uses a degenerate substrate and high concentration P /plus/ guard-ring diffusion, another places the base contact at the center of an annular ring structure.

A cellular glass substrate solar concentrator

NASA Technical Reports Server (NTRS)

Bedard, R.; Bell, D.

1980-01-01

The design of a second generation point focusing solar concentration is discussed. The design is based on reflective gores fabricated of thin glass mirror bonded continuously to a contoured substrate of cellular glass. The concentrator aperture and structural stiffness was optimized for minimum concentrator cost given the performance requirement of delivering 56 kWth to a 22 cm diameter receiver aperture with a direct normal insolation of 845 watts sq m and an operating wind of 50 kmph. The reflective panel, support structure, drives, foundation and instrumentation and control subsystem designs, optimized for minimum cost, are summarized. The use of cellular glass as a reflective panel substrate material is shown to offer significant weight and cost advantages compared to existing technology materials.

Partitioning of heavy metals in sub-surface flow treatment wetlands receiving high-strength wastewater.

PubMed

Wojciechowska, Ewa; Gajewska, Magdalena

2013-01-01

The retention of heavy metals at two pilot-scale treatment wetlands (TWs), consisting of two vertical flow beds (VSSF) followed by a horizontal flow bed (HSSF) was studied. The TWs received high-strength wastewater: reject waters from sewage sludge centrifugation (RW) and landfill leachate (LL). The concentrations of the metals Fe, Mn, Zn, Al, Pb, Cu, Cd, Co, and Ni were measured in treated wastewater, substrate of the beds and in plant material harvested from the beds (separately in above ground (ABG) parts and below ground (BG) parts). The TWs differed in metals retention. In the RW treating TW the metal removal efficiencies varied from 27% for Pb to over 97% for Fe and Al. In the LL treating system the concentrations of most metals decreased after VSSF-1 and VSSF-2 beds; however, in the outflow from the last (HSSF) bed, the concentrations of metals (apart from Al) increased again, probably due to the anaerobic conditions at the bed. A major removal pathway was sedimentation and adsorption onto soil substrate as well as precipitation and co-precipitation. In the LL treating facility the plants contained substantially higher metal concentrations in BG parts, while the upward movement of metals was restricted. In the RW treating facility the BG/ABG ratios were lower, indicating that metals were transported to shoots.

Kinetic studies of Chromobacterium viscosum lipase in AOT water in oil microemulsions and gelatin microemulsion-based organogels.

PubMed

Jenta, T R; Batts, G; Rees, G D; Robinson, B H

1997-06-05

Kinetic studies have shown that octyl decanoate synthesis by Chromobacterium viscosum (CV) lipase in sodium bis-2-(ethylhexyl) sulfosuccinate (AOT) water in oil (w/o) microemulsions occurs via the nonsequential (ping-pong) bi bi mechanism. There was evidence of single substrate inhibition by decanoic acid at high concentrations. Initial rate data yielded estimates for acid and alcohol Michaelis constants of ca. 10(-1) mol dm(-3) and a maximum rate under saturation conditions of ca. 10(-3) mol dm(-3) s(-1) for a lipase concentration of 0.36 mg cm(-3). CV lipase immobilized in AOT microemulsion-based organogels (MBGs) was also found to catalyze the synthesis of octyl decanoate according to the ping-pong bi bi mechanism. Reaction rates were similar in the free and immobilized systems under comparable conditions. Initial rates at saturating (but noninhibiting) substrate concentrations were first order with respect to CV lipase concentration in both w/o microemulsions and the MBG/oil systems. Gradients yielded an apparent k(cat) = 4.4 x 10(-4) mol g(-1) s(-1) in the case of w/o microemulsions, and 6.1 x 10(-4) mol g(-1) s(-1) for CV lipase immobilized in the MBGs. A third system comprising w/o microemulsions containing substrates and gelatin at concentrations comparable to those employed in the MBG formulations, provided a useful link between the conventional liquid microemulsion medium and the solid organogels. The nongelation of these intermediate systems stems from the early inclusion of substrate during a modified preparative protocol. The presence of substrate appears to prevent the development of a percolated microstructure that is thought to be a prerequisite for MBG formation. FT-NMR was employed as a semicontinuous in situ assay procedure. The apparent activity expressed by CV lipase in compositionally equivalent liquid and solid phase gelatin-containing systems was similar. An apparent activation energy of 24 +/- 2 kJ mol(-1) was determined by (1)H-NMR for esterification in gelatin-containing w/o microemulsions. This value agrees with previous determinations for CV lipase-catalyzed synthesis of octyl decanoate in "conventional" w/o microemulsions and MBG/oil systems. The similarities in lipase behavior are consistent with the claim, based largely on structural measurements, that the physico-chemical properties of the lipase-containing w/o microemulsion are to a large extent preserved on transformation to the daughter organogel. The close agreement of apparrent activation energies suggests that substrate mass transfer is not rate determining in the three studied systems.

Controlled Spalling in (100)-Oriented Germanium by Electroplating

NASA Astrophysics Data System (ADS)

Crouse, Dustin Ray

This work investigates controlled spalling as a method to exfoliate thin films of various thickness from rigid, crystalline germanium (Ge) substrates and to enable substrate reuse for III-V single junction photovoltaic devices. Technological limitations impeding wide-spread adoption of flexible electronics and high-material-cost photovoltaic devices have motivated significant interest in a method to remove devices from their substrates. DC magnetron sputtering has been previously utilized to remove semiconductor devices of various thicknesses from Ge substrates, but this method is expensive and time-consuming. Controlled spalling via high-speed electrodeposition is a fast, inexpensive exfoliation method that utilizes a tensile-stressed metal layer deposited on a (100)-oriented Ge substrate and an external force to mechanically propagate a crack parallel to the surface at a desired depth in the substrate material. Suo and Hutchinson's quantitative models describe critical combinations of film thickness and strain mismatch between a film and substrate at which a stressed bilayer system spontaneously spalls; however, fine control over a wide steady-state spall depth range has been limited by the ability to experimentally tailor strain mismatch caused by residual stress within deposited stressor layers. This work investigates the effect of tuning electroplating current density and electrolyte chemistry on the residual stress in a nickel stressor film and their impact on the achievable spall depth range. Steady-state spall depth is found to increase with increasing stressor layer thickness and decrease with increasing residual stress. By tailoring residual stress through adjusting plating conditions and the electrolyte's phosphorous concentration, wide control over spall depth within Ge substrates from sub-micron to 76microm-thicknesses were achieved. To assess the viability of utilizing controlled spalling for substrate reuse, this dissertation demonstrates the first III-V solar cells (GaInAsP, Eg 1.7 eV) grown directly on a spalled-Ge substrate without any additional surface preparation. Widespread adoption of high-efficiency III-V solar cells has been limited by expensive deposition processes and high material cost of substrates. Substrate reuse offers a promising route towards enabling III-V devices to become cost-competitive for one-sun terrestrial applications. In this study, the quality of spalled Ge surfaces is characterized to assess lattice matching capability between the device layer materials and the substrate. GaAs films grown on spalled Ge substrates by hydride vapor phase epitaxy were single-crystal in nature. III-V solar cells grown on spalled and pristine Ge substrates show nearly equivalent efficiency of 8%, despite the roughness of the spalled-Ge substrate. Principles of fractography were used to deduce that surface roughness originated from non-uniform crack propagation and mixed-mode loading during the spalling process.

High flux filtration medium based on nanofibrous substrate with hydrophilic nanocomposite coating.

PubMed

Wang, Xuefen; Chen, Xuming; Yoon, Kyunghwan; Fang, Dufei; Hsiao, Benjamin S; Chu, Benjamin

2005-10-01

A novel high flux filtration medium, consisting of a three-tier composite structure, i.e., a nonporous hydrophilic nanocomposite coating top layer, an electrospun nanofibrous substrate midlayer, and a conventional nonwoven microfibrous support, was demonstrated for oil/water emulsion separations for the first time. The nanofibrous substrate was prepared by electrospinning of poly(vinyl alcohol) (PVA) followed by chemical cross-linking with glutaraldehyde (GA) in acetone. The resulting cross-linked PVA substrates showed excellent water resistance and good mechanical properties. The top coating was based on a nanocomposite layer containing hydrophilic polyether-b-polyamide copolymer or a cross-linked PVA hydrogel incorporated with surface-oxidized multiwalled carbon nanotubes (MWNTs). Scanning electron microscopy (SEM) examinations indicated that the nanocomposite layer was nonporous within the instrumental resolution and MWNTs were well dispersed in the polymer matrix. Oil/ water emulsion tests showed that this unique type of filtration media exhibited a high flux rate (up to 330 L/m2-h at the feed pressure of 100 psi) and an excellent total organic solute rejection rate (99.8%) without appreciable fouling. The increase in the concentration of surface-oxidized MWNT in the coating layer generally improves the flux rate, which can be attributed to the generation of more effective hydrophilic nanochannels for water passage in the composite membranes.

A study of monoamine oxidase activity in fetal membranes.

PubMed

Sekizawa, A; Ishikawa, H; Morimoto, T; Hirose, K; Suzuki, A; Saito, H; Yanaihara, T; Arai, Y; Oguchi, K

1996-05-01

To study the role of decidual monoamine oxidase (MAO)-A and -B activities before delivery, the relationship between MAO activity in fetal membranes and catecholamine (CA) concentration in amniotic fluid (AF) was determined. Fetal membranes and AF were obtained at the time of elective Cesarean section (CS group, n = 11) and Cesarean section due to fetal distress without labor pains (FD group, n = 5). MAO-A and -B activities were radiometrically measured using 14C-5-hydroxytriptamine for MAO-A substrate and 14C-benzylamine for MAO-B substrate. CA concentrations in AF were measured by high performance liquid chromatograph with an electro-chemical detector. Both MAO-A and -B activities in decidua obtained from CS were significantly lower than those obtained from FD. Both norepinephrine (NE) and epinephrine (EP) concentrations were significantly lower in the CS group than the FD group. A significant positive correlation between decidual MAO-A activity and NE concentration in AF was observed. No significant correlation was observed between MAO-B activity and the concentration of NE in AF. There was no correlation between EP concentrations and MAO activities. These results suggest that CA concentration in AF may be related to the activity of MAO in fetal membranes, determined by certain physiological processes during pregnancy. It has been suggested that metabolism of monoamines in fetal membranes also plays an important role in reducing monoamine influx into maternal myometrium from the AF.

AGEs Induce Apoptosis in Rat Osteoblast Cells by Activating the Caspase-3 Signaling Pathway Under a High-Glucose Environment In Vitro.

PubMed

Liu, Jiaqiang; Mao, Jing; Jiang, Yi; Xia, Lunguo; Mao, Lixia; Wu, Yong; Ma, Pan; Fang, Bing

2016-03-01

Advanced glycation end products (AGEs) accumulate under high-glucose conditions and affect the healing of bone damage through various pathways; however, the detail mechanisms underlying these changes are unknown. In this study, we investigated the effects of AGEs on the apoptosis of in vitro-cultured rat osteoblasts under high-glucose conditions and explored the underlying mechanisms of these effects. First, we cultured rat osteoblasts and determined the accumulation of AGEs in the culture medium under high-glucose conditions. Then, we cultured rat osteoblasts under a high glucose concentration (35 mM), a normal glucose concentration (5.5 mM), and a normal glucose concentration (5.5 mM) in the presence of AGEs. We examined the effects of high glucose and AGEs on the apoptosis of rat osteoblasts at different time points and further analyzed the activity and changes in the levels of procaspase-3, caspase-3, and the caspase-3 substrate poly ADP-ribose polymerase (PARP). Finally, we added sRAGE (soluble RAGE) (an AGE inhibitor) or DEVD (a caspase-3 inhibitor) to each culture group and examined apoptosis under each culture condition and the changes in the levels of procaspase-3, caspase-3, and its substrate PARP. The results showed that the high-glucose condition and the addition of AGEs increased the apoptosis of rat osteoblast cells and simultaneously increased the activity and quantity of caspase-3. These increases could be inhibited by the AGE inhibitor sRAGE or the caspase-3 inhibitor DEVD. The above results demonstrate that high-glucose conditions lead to the accumulation of AGEs and activation of the caspase-3 signaling pathway, resulting in the increased apoptosis of cultured rat osteoblast cells.

Growth of mixed cultures on mixtures of substitutable substrates: the operating diagram for a structured model.

PubMed

Reeves, Gregory T; Narang, Atul; Pilyugin, Sergei S

2004-01-21

The growth of mixed microbial cultures on mixtures of substrates is a problem of fundamental biological interest. In the last two decades, several unstructured models of mixed-substrate growth have been studied. It is well known, however, that the growth patterns in mixed-substrate environments are dictated by the enzymes that catalyse the transport of substrates into the cell. We have shown previously that a model taking due account of transport enzymes captures and explains all the observed patterns of growth of a single species on two substitutable substrates (J. Theor. Biol. 190 (1998) 241). Here, we extend the model to study the steady states of growth of two species on two substitutable substrates. The model is analysed to determine the conditions for existence and stability of the various steady states. Simulations are performed to determine the flow rates and feed concentrations at which both species coexist. We show that if the interaction between the two species is purely competitive, then at any given flow rate, coexistence is possible only if the ratio of the two feed concentrations lies within a certain interval; excessive supply of either one of the two substrates leads to annihilation of one of the species. This result simplifies the construction of the operating diagram for purely competing species. This is because the two-dimensional surface that bounds the flow rates and feed concentrations at which both species coexist has a particularly simple geometry: It is completely determined by only two coordinates, the flow rate and the ratio of the two feed concentrations. We also study commensalistic interactions between the two species by assuming that one of the species excretes a product that can support the growth of the other species. We show that such interactions enhance the coexistence region.

Size effect model on kinetics of interfacial reaction between Sn-xAg-yCu solders and Cu substrate

PubMed Central

Huang, M. L.; Yang, F.

2014-01-01

The downsizing of solder balls results in larger interfacial intermetallic compound (IMC) grains and less Cu substrate consumption in lead-free soldering on Cu substrates. This size effect on the interfacial reaction is experimentally demonstrated and theoretically analyzed using Sn-3.0Ag-0.5Cu and Sn-3.5Ag solder balls. The interfacial reaction between the Sn-xAg-yCu solders and Cu substrates is a dynamic response to a combination of effects of interfacial IMC growth, Cu substrate consumption and composition variation in the interface zone. A concentration gradient controlled (CGC) kinetics model is proposed to explain the combined effects. The concentration gradient of Cu at the interface, which is a function of solder volume, initial Cu concentration and reaction time, is the root cause of the size effect. We found that a larger Cu concentration gradient results in smaller Cu6Sn5 grains and more consumption of Cu substrate. According to our model, the growth kinetics of interfacial Cu6Sn5 obeys a t1/3 law when the molten solder has approached the solution saturation, and will be slower otherwise due to the interfering dissolution mechanism. The size effect introduced in this model is supported by a good agreement between theoretical and experimental results. Finally, the scope of application of this model is discussed. PMID:25408359

LPCVD homoepitaxy of Si doped β-Ga2O3 thin films on (010) and (001) substrates

NASA Astrophysics Data System (ADS)

Rafique, Subrina; Karim, Md Rezaul; Johnson, Jared M.; Hwang, Jinwoo; Zhao, Hongping

2018-01-01

This paper presents the homoepitaxy of Si-doped β-Ga2O3 thin films on semi-insulating (010) and (001) Ga2O3 substrates via low pressure chemical vapor deposition with a growth rate of ≥1 μm/h. Both high resolution scanning transmission electron microscopy and X-ray diffraction measurements demonstrated high crystalline quality homoepitaxial growth of these thin films. Atomic resolution STEM images of the as-grown β-Ga2O3 thin films on (010) and (001) substrates show high quality material without extended defects or dislocations. The charge carrier transport properties of the as-grown Si-doped β-Ga2O3 thin films were characterized by the temperature dependent Hall measurement using van der Pauw patterns. The room temperature carrier concentrations achieved for the (010) and (001) homoepitaxial thin films were ˜1.2 × 1018 cm-3 and ˜9.5 × 1017 cm-3 with mobilities of ˜72 cm2/V s and ˜42 cm2/V s, respectively.

AlGaAs/InGaAs/AlGaAs double pulse doped pseudomorphic high electron mobility transistor structures on InGaAs substrates

NASA Astrophysics Data System (ADS)

Hoke, W. E.; Lyman, P. S.; Mosca, J. J.; McTaggart, R. A.; Lemonias, P. J.; Beaudoin, R. M.; Torabi, A.; Bonner, W. A.; Lent, B.; Chou, L.-J.; Hsieh, K. C.

1997-10-01

Double pulse doped AlGaAs/InGaAs/AlGaAs pseudomorphic high electron mobility transistor (PHEMT) structures have been grown on InxGa1-xAs (x=0.025-0.07) substrates using molecular beam epitaxy. A strain compensated, AlGaInAs/GaAs superlattice was used for improved resistivity and breakdown. Excellent electrical and optical properties were obtained for 110-Å-thick InGaAs channel layers with indium concentrations up to 31%. A room temperature mobility of 6860 cm2/V s with 77 K sheet density of 4.0×1012cm-2 was achieved. The InGaAs channel photoluminescence intensity was equivalent to an analogous structure on a GaAs substrate. To reduce strain PHEMT structures with a composite InGaP/AlGaAs Schottky layer were also grown. The structures also exhibited excellent electrical and optical properties. Transmission electron micrographs showed planar channel interfaces for highly strained In0.30Ga0.70As channel layers.

Utilization of biodiesel by-product as substrate for high-production of β-farnesene via relatively balanced mevalonate pathway in Escherichia coli.

PubMed

You, Shengping; Yin, Qingdian; Zhang, Jianye; Zhang, Chengyu; Qi, Wei; Gao, Lan; Tao, Zhiping; Su, Rongxin; He, Zhimin

2017-11-01

Farnesene has been identified as suitable jet fuel substitutes and metabolic engineering for microbial production of farnesene is an alternative and attractive route. In this study, due to accumulation of toxic intermediate isopentenyl pyrophosphate (IPP), an engineered Escherichia coli strain harboring heterologous mevalonate pathway produced only 4.11mg/L β-farnesene. Through higher-level expression of isopentenyl diphosphate isomerase and farnesyl diphosphate synthase to minimize the accumulated IPP, another engineered strain with relatively balanced mevalonate pathway was constructed and had the highest production of β-farnesene to date (8.74g/L) by Escherichia coli in a lab bioreactor. Furthermore, this is the first report on utilization of biodiesel by-product (simple purification) as substrate for high-production of β-farnesene by the engineered strain optimized and β-farnesene concentration reached 2.83g/L in a lab bioreactor. Therefore, the engineered strain optimized could be used as a platform host for high-production of other terpenoids using biodiesel by-product as substrate. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cell foundry with high product specificity and catalytic activity for 21-deoxycortisol biotransformation.

PubMed

Xiong, Shuting; Wang, Ying; Yao, Mingdong; Liu, Hong; Zhou, Xiao; Xiao, Wenhai; Yuan, Yingjin

2017-06-13

21-deoxycortisol (21-DF) is the key intermediate to manufacture pharmaceutical glucocorticoids. Recently, a Japan patent has realized 21-DF production via biotransformation of 17-hydroxyprogesterone (17-OHP) by purified steroid 11β-hydroxylase CYP11B1. Due to the less costs on enzyme isolation, purification and stabilization as well as cofactors supply, whole-cell should be preferentially employed as the biocatalyst over purified enzymes. No reports as so far have demonstrated a whole-cell system to produce 21-DF. Therefore, this study aimed to establish a whole-cell biocatalyst to achieve 21-DF transformation with high catalytic activity and product specificity. In this study, Escherichia coli MG1655(DE3), which exhibited the highest substrate transportation rate among other tested chassises, was employed as the host cell to construct our biocatalyst by co-expressing heterologous CYP11B1 together with bovine adrenodoxin and adrenodoxin reductase. Through screening CYP11B1s (with mutagenesis at N-terminus) from nine sources, Homo sapiens CYP11B1 mutant (G25R/G46R/L52 M) achieved the highest 21-DF transformation rate at 10.6 mg/L/h. Furthermore, an optimal substrate concentration of 2.4 g/L and a corresponding transformation rate of 16.2 mg/L/h were obtained by screening substrate concentrations. To be noted, based on structural analysis of the enzyme-substrate complex, two types of site-directed mutations were designed to adjust the relative position between the catalytic active site heme and the substrate. Accordingly, 1.96-fold enhancement on 21-DF transformation rate (to 47.9 mg/L/h) and 2.78-fold improvement on product/by-product ratio (from 0.36 to 1.36) were achieved by the combined mutagenesis of F381A/L382S/I488L. Eventually, after 38-h biotransformation in shake-flask, the production of 21-DF reached to 1.42 g/L with a yield of 52.7%, which is the highest 21-DF production as known. Heterologous CYP11B1 was manipulated to construct E. coli biocatalyst converting 17-OHP to 21-DF. Through the strategies in terms of (1) screening enzymes (with N-terminal mutagenesis) sources, (2) optimizing substrate concentration, and most importantly (3) rational design novel mutants aided by structural analysis, the 21-DF transformation rate was stepwise improved by 19.5-fold along with 4.67-fold increase on the product/byproduct ratio. Eventually, the highest 21-DF reported production was achieved in shake-flask after 38-h biotransformation. This study highlighted above described methods to obtain a high efficient and specific biocatalyst for the desired biotransformation.

Thallium Bromide Deposited Using Spray Coating

NASA Astrophysics Data System (ADS)

Ferreira, E. S.; Mulato, M.

2012-08-01

Spray coating was used to produce thallium bromide samples on glass substrates. The influence of several fabrication parameters on the final structural properties of the samples was investigated. Substrate position, substrate temperature, solution concentration, carrying gas, and solution flow were varied systematically, the physical deposition mechanism involved in each case being discussed. Total deposition time of about 3.5 h can lead to 62-μm-thick films, comprising completely packed micrometer-sized crystalline grains. X-ray diffraction and scanning electron microscopy were used to characterize the samples. On the basis of the experimental data, the optimum fabrication conditions were identified. The technique offers an alternative method for fast, cheap fabrication of large-area devices for the detection of high-energy radiation, i.e., X-rays and γ-rays, in medical imaging.

Carbon Source Preference in Chemosynthetic Hot Spring Communities

PubMed Central

Urschel, Matthew R.; Kubo, Michael D.; Hoehler, Tori M.; Peters, John W.

2015-01-01

Rates of dissolved inorganic carbon (DIC), formate, and acetate mineralization and/or assimilation were determined in 13 high-temperature (>73°C) hot springs in Yellowstone National Park (YNP), Wyoming, in order to evaluate the relative importance of these substrates in supporting microbial metabolism. While 9 of the hot spring communities exhibited rates of DIC assimilation that were greater than those of formate and acetate assimilation, 2 exhibited rates of formate and/or acetate assimilation that exceeded those of DIC assimilation. Overall rates of DIC, formate, and acetate mineralization and assimilation were positively correlated with spring pH but showed little correlation with temperature. Communities sampled from hot springs with similar geochemistries generally exhibited similar rates of substrate transformation, as well as similar community compositions, as revealed by 16S rRNA gene-tagged sequencing. Amendment of microcosms with small (micromolar) amounts of formate suppressed DIC assimilation in short-term (<45-min) incubations, despite the presence of native DIC concentrations that exceeded those of added formate by 2 to 3 orders of magnitude. The concentration of added formate required to suppress DIC assimilation was similar to the affinity constant (Km) for formate transformation, as determined by community kinetic assays. These results suggest that dominant chemoautotrophs in high-temperature communities are facultatively autotrophic or mixotrophic, are adapted to fluctuating nutrient availabilities, and are capable of taking advantage of energy-rich organic substrates when they become available. PMID:25819970

Effect of Alignment on Transport Properties of Carbon Nanotube/Metallic Junctions

NASA Technical Reports Server (NTRS)

Wincheski, Buzz; Namkung, Min; Smits, Jan; Williams, Phillip; Harvey, Robert

2003-01-01

Ballistic and spin coherent transport in single walled carbon nanotubes (SWCNT) are predicted to enable high sensitivity single-nanotube devices for strain and magnetic field sensing. Based upon these phenomena, electron beam lithography procedures have been developed to study the transport properties of purified HiPCO single walled carbon nanotubes for development into sensory materials for nondestructive evaluation. Purified nanotubes are dispersed in solvent suspension and then deposited on the device substrate before metallic contacts are defined and deposited through electron beam lithography. This procedure produces randomly dispersed ropes, typically 2 - 20 nm in diameter, of single walled carbon nanotubes. Transport and scanning probe microscopy studies have shown a good correlation between the junction resistance and tube density, alignment, and contact quality. In order to improve transport properties of the junctions a technique has been developed to align and concentrate nanotubes at specific locations on the substrate surface. Lithographic techniques are used to define local areas where high frequency electric fields are to be concentrated. Application of the fields while the substrate is exposed to nanotube-containing solution results in nanotube arrays aligned with the electric field lines. A second electron beam lithography layer is then used to deposit metallic contacts across the aligned tubes. Experimental measurements are presented showing the increased tube alignment and improvement in the transport properties of the junctions.

Paper-based chemiresistor for detection of ultralow concentrations of protein.

PubMed

Pozuelo, Marta; Blondeau, Pascal; Novell, Marta; Andrade, Francisco J; Xavier Rius, F; Riu, Jordi

2013-11-15

A new paper-based chemiresistor composed of a network of single-wall carbon nanotubes (SWCNTs) and anti-human immunoglobulin G (anti-HIgG) is reported herein. SWCNTs act as outstanding transducers because they provide high sensitivity in terms of resistance changes due to immunoreaction. As a result, the resistance-based biosensor reaches concentration detection as low as picomolar. The resulting paper-based biosensor is sensitive, selective and employs low-cost substrate and simple manufacturing stages. Since chemiresistors require low-power equipment and are able to detect low concentrations with inexpensive materials, the present approach may pave the way for the development of resistive biosensors at very low-cost with high performances. Copyright © 2013 Elsevier B.V. All rights reserved.

Gas flow rate dependence of the discharge characteristics of a helium atmospheric pressure plasma jet interacting with a substrate

NASA Astrophysics Data System (ADS)

Yan, Wen; Economou, Demetre J.

2017-10-01

A 2D (axisymmetric) computational study of the discharge characteristics of an atmospheric pressure plasma jet as a function of gas flow rate was performed. The helium jet emerged from a dielectric tube, with an average gas flow velocity in the range 2.5-20 m s-1 (1 atm, 300 K) in a nitrogen ambient, and impinged on a substrate a short distance dowstream. The effect of the substrate conductivity (conductror versus insulator) was also studied. Whenever possible, simulation predictions were compared with published experimental observations. Discharge ignition and propagation in the dielectric tube were hardly affected by the He gas flow velocity. Most properties of the plasma jet, however, depended sensitively on the He gas flow velocity, which determined the concentration distributions of helium and nitrogen in the mixing layer forming in the gap between the tube exit and the substrate. At low gas flow velocity, the plasma jet evolved from a hollow (donut-shaped) feature to one where the maximum of electron density was on axis. When the gas flow velocity was high, the plasma jet maintained its hollow structure until it struck the substrate. For a conductive substrate, the radial ion fluxes to the surface were relatively uniform over a radius of ~0.4-0.8 mm, and the dominant ion flux was that of He+. For a dielectric substrate, the radial ion fluxes to the surface peaked on the symmetry axis at low He gas flow velocity, but a hollow ion flux distribution was observed at high gas flow velocity. At the same time, the main ion flux switched from N2+ to He2+ as the He gas flow velocity increased from a low to a high value. The diameter of the plasma ‘footprint’ on the substrate first increased with increasing He gas flow velocity, and eventually saturated with further increases in velocity.

Biodegradation of high molecular weight lignin under sulfate reducing conditions: lignin degradability and degradation by-products.

PubMed

Ko, Jae-Jung; Shimizu, Yoshihisa; Ikeda, Kazuhiro; Kim, Seog-Ku; Park, Chul-Hwi; Matsui, Saburo

2009-02-01

This study is designed to investigate the biodegradation of high molecular weight (HMW) lignin under sulfate reducing conditions. With a continuously mesophilic operated reactor in the presence of co-substrates of cellulose, the changes in HMW lignin concentration and chemical structure were analyzed. The acid precipitable polymeric lignin (APPL) and lignin monomers, which are known as degradation by-products, were isolated and detected. The results showed that HMW lignin decreased and showed a maximum degradation capacity of 3.49 mg/l/day. APPL was confirmed as a polymeric degradation by-product and was accumulated in accordance with HMW lignin reduction. We also observed non-linear accumulation of aromatic lignin monomers such as hydrocinnamic acid. Through our experimental results, it was determined that HMW lignin, when provided with a co-substrate of cellulose, is biodegraded through production of APPL and aromatic monomers under anaerobic sulfate reducing conditions with a co-substrate of cellulose.

Surface-assisted laser desorption/ionization time-of-flight mass spectrometry of small drug molecules and high molecular weight synthetic/biological polymers using electrospun composite nanofibers.

PubMed

Bian, Juan; Olesik, Susan V

2017-03-27

Polyacrylonitrile/Nafion®/carbon nanotube (PAN/Nafion®/CNT) composite nanofibers were prepared using electrospinning. These electrospun nanofibers were studied as possible substrates for surface-assisted laser desorption/ionization (SALDI) and matrix-enhanced surface-assisted laser desorption/ionization time-of-flight mass spectrometry (ME-SALDI/TOF-MS) for the first time in this paper. Electrospinning provides this novel substrate with a uniform morphology and a narrow size distribution, where CNTs were evenly and firmly immobilized on polymeric nanofibers. The results show that PAN/Nafion®/CNT nanofibrous mats are good substrates for the analysis of both small drug molecules and high molecular weight polymers with high sensitivity. Markedly improved reproducibility was observed relative to MALDI. Due to the composite formation between the polymers and the CNTs, no contamination of the carbon nanotubes to the mass spectrometer was observed. Furthermore, electrospun nanofibers used as SALDI substrates greatly extended the duration of ion signals of target analytes compared to the MALDI matrix. The proposed SALDI approach was successfully used to quantify small drug molecules with no interference in the low mass range. The results show that verapamil could be detected with a surface concentration of 220 femtomoles, indicating the high detection sensitivity of this method. Analysis of peptides and proteins with the electrospun composite substrate using matrix assisted-SALDI was improved and a low limit of detection of approximately 6 femtomoles was obtained for IgG. Both SALDI and ME-SALDI analyses displayed high reproducibility with %RSD ≤ 9% for small drug molecules and %RSD ≤ 14% for synthetic polymers and proteins.

Enzymatic synthesis of 3-O-α-maltosyl-l-ascorbate using an engineered cyclodextrin glucanotransferase.

PubMed

Ahn, Hee-Jeong; Li, Chao; Cho, Hye-Bin; Park, Sunghoon; Chang, Pahn-Shick; Kim, Young-Wan

2015-02-15

A mutant derived from a cyclodextrin glucantransferase with an alanine residue as its acid/base catalyst residue (CGT-E284A) catalyzed regioselective glycosylation at 3-OH of l-ascorbic acid using α-maltosyl fluoride (αG2F) and l-ascorbic acid as the donor and acceptor, respectively, yielding 3-O-α-maltosyl-l-ascorbate (AA3αG2). The optimum conditions were determined by high-performance liquid chromatography analysis with 20mM αG2F and 40mM l-ascorbic acid as the substrates at pH 7.5 and 25°C with 1mg/ml of the enzyme for 24h. Calcium ions bound in CGT-E284A played an important role in the transglycosylation. CGT-E284A exhibited typical saturation kinetic behaviour for αG2F at a fixed acceptor concentration (40mM), and substrate inhibition by l-ascorbic acid was observed at high l-ascorbic acid concentrations (>60mM). AA3αG2 was isolated from a preparative scale reaction with a yield of 29%, and it showed extremely high stability under oxidative conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Structure dependent resistivity and dielectric characteristics of tantalum oxynitride thin films produced by magnetron sputtering

NASA Astrophysics Data System (ADS)

Cristea, D.; Crisan, A.; Cretu, N.; Borges, J.; Lopes, C.; Cunha, L.; Ion, V.; Dinescu, M.; Barradas, N. P.; Alves, E.; Apreutesei, M.; Munteanu, D.

2015-11-01

The main purpose of this work is to present and to interpret the change of electrical properties of TaxNyOz thin films, produced by DC reactive magnetron sputtering. Some parameters were varied during deposition: the flow of the reactive gases mixture (N2 and O2, with a constant concentration ratio of 17:3); the substrate voltage bias (grounded, -50 V or -100 V) and the substrate (glass, (1 0 0) Si or high speed steel). The obtained films exhibit significant differences. The variation of the deposition parameters induces variations of the composition, microstructure and morphology. These differences cause variation of the electrical resistivity essentially correlated with the composition and structural changes. The gradual decrease of the Ta concentration in the films induces amorphization and causes a raise of the resistivity. The dielectric characteristics of some of the high resistance TaxNyOz films were obtained in the samples with a capacitor-like design (deposited onto high speed steel, with gold pads deposited on the dielectric TaxNyOz films). Some of these films exhibited dielectric constant values higher than those reported for other tantalum based dielectric films.

Growth of GaN single crystals by a Ca- and Ba-added Na flux method

NASA Astrophysics Data System (ADS)

Ukegawa, H.; Konishi, Y.; Fujimori, T.; Miyoshi, N.; Imade, M.; Yoshimura, M.; Kitaoka, Y.; Sasaki, T.; Mori, Y.

2011-02-01

GaN substrates are desirable for fabricating ultra-violet LEDs and LDs, and high-power and high-frequency transistors. High-quality GaN single crystals can be obtained by using Na flux method, but the growth habit of bulk crystals must be controlled. In this study, we investigated the effects of additives (Ca, Ba) on the growth habit and impurity concentration in the crystals. The aspect ratio (c/a) of the crystals was increased by increasing the amount of additives, showing that the growth habit could be changed from the pyramidal shape to the prism shape. Ba concentration was below the detection limit (1x1015 atoms/cm3).

Using Plant Source as a Buffering Agent to Manipulating Rumen Fermentation in an In vitro Gas Production System.

PubMed

Kang, S; Wanapat, M

2013-10-01

The objective of this study was to investigate the effect of banana flower powder (BAFLOP) supplementation on gas production kinetics and rumen fermentation efficiency in in vitro incubation with different ratios of roughage to concentrate in swamp buffalo and cattle rumen fluid. Two male, rumen fistulated dairy steers and swamp buffaloes were used as rumen fluid donors. The treatments were arranged according to a 2×2×3 factorial arrangement in a Completely randomized design by using two ratios of roughage to concentrate (R:C; 75:25 and 25:75) and 3 levels of BAFLOP supplementation (0, 2 and 4% of dietary substrate) into two different kinds of rumen fluid (beef cattle and swamp buffalo). Under this investigation, the results revealed that the rumen ecology was affected by R:C ratio. The pH declined as a result of using high concentrate ratio; however, supplementation of BAFLOP could buffer the pH which led to an improvement of ruminal efficiency. BAFLOP supplementation affected acetic acid (C2) when the proportion of concentrate was increased. However, there were no effect on total volatile fatty acid (TVFA) and butyric acid (C4) by BAFLOP supplementation. The microbial community was affected by BAFLOP supplementation, especially the bacterial population. As revealed by real-time PCR, the populations of F. succinogenes and R. albus were reduced by the high concentrate treatments while that of R. flavafaciens were increased. The populations of three dominant cellulolytic bacteria were enhanced by BAFLOP supplementation, especially on high concentrate diet. BAFLOP supplementation did not influence the ammonia nitrogen (NH3-N) concentration, while R:C did. In addition, the in vitro digestibility was improved by either R:C or BAFLOP supplementation. The BAFLOP supplementation showed an effect on gas production kinetics, except for the gas production rate constant for the insoluble fraction (c), while treatments with high concentrate ratio resulted in the highest values. In addition, BAFLOP tended to increase gas production. Based on this study, it could be concluded that R:C had an effect on rumen ecology both in buffalo and cattle rumen fluid and hence, BAFLOP could be used as a rumen buffering agent for enhancing rumen ecology fed on high concentrate diet. It is recommended that level of BAFLOP supplementation should be at 2 to 4% of total dry matter of substrate. However, in vivo trials should be subsequently conducted to investigate the effect of BAFLOP in high concentrate diets on rumen ecology as well as ruminant production.

Acetate accumulation enhances mixed culture fermentation of biomass to lactic acid.

PubMed

Khor, Way Cern; Roume, Hugo; Coma, Marta; Vervaeren, Han; Rabaey, Korneel

2016-10-01

Lactic acid is a high-in-demand chemical, which can be produced through fermentation of lignocellulosic feedstock. However, fermentation of complex substrate produces a mixture of products at efficiencies too low to justify a production process. We hypothesized that the background acetic acid concentration plays a critical role in lactic acid yield; therefore, its retention via selective extraction of lactic acid or its addition would improve overall lactic acid production and eliminate net production of acetic acid. To test this hypothesis, we added 10 g/L of acetate to fermentation broth to investigate its effect on products composition and concentration and bacterial community evolution using several substrate-inoculum combinations. With rumen fluid inoculum, lactate concentrations increased by 80 ± 12 % (cornstarch, p < 0.05) and 16.7 ± 0.4 % (extruded grass, p < 0.05) while with pure culture inoculum (Lactobacillus delbrueckii and genetically modified (GM) Escherichia coli), a 4 to 23 % increase was observed. Using rumen fluid inoculum, the bacterial community was enriched within 8 days to >69 % lactic acid bacteria (LAB), predominantly Lactobacillaceae. Higher acetate concentration promoted a more diverse LAB population, especially on non-inoculated bottles. In subsequent tests, acetate was added in a semi-continuous percolation system with grass as substrate. These tests confirmed our findings producing lactate at concentrations 26 ± 5 % (p < 0.05) higher than the control reactor over 20 days operation. Overall, our work shows that recirculating acetate has the potential to boost lactic acid production from waste biomass to levels more attractive for application.

Kinetics of enzymatic high-solid hydrolysis of lignocellulosic biomass studied by calorimetry.

PubMed

Olsen, Søren N; Lumby, Erik; McFarland, Kc; Borch, Kim; Westh, Peter

2011-03-01

Enzymatic hydrolysis of high-solid biomass (>10% w/w dry mass) has become increasingly important as a key step in the production of second-generation bioethanol. To this end, development of quantitative real-time assays is desirable both for empirical optimization and for detailed kinetic analysis. In the current work, we have investigated the application of isothermal calorimetry to study the kinetics of enzymatic hydrolysis of two substrates (pretreated corn stover and Avicel) at high-solid contents (up to 29% w/w). It was found that the calorimetric heat flow provided a true measure of the hydrolysis rate with a detection limit of about 500 pmol glucose s(-1). Hence, calorimetry is shown to be a highly sensitive real-time method, applicable for high solids, and independent on the complexity of the substrate. Dose-response experiments with a typical cellulase cocktail enabled a multidimensional analysis of the interrelationships of enzyme load and the rate, time, and extent of the reaction. The results suggest that the hydrolysis rate of pretreated corn stover is limited initially by available attack points on the substrate surface (<10% conversion) but becomes proportional to enzyme dosage (excess of attack points) at later stages (>10% conversion). This kinetic profile is interpreted as an increase in polymer end concentration (substrate for CBH) as the hydrolysis progresses, probably due to EG activity in the enzyme cocktail. Finally, irreversible enzyme inactivation did not appear to be the source of reduced hydrolysis rate over time.

Modeling degradation and failure of Ni-Cr-Al overlay coatings

NASA Technical Reports Server (NTRS)

Nesbitt, J. A.; Heckel, R. W.

1984-01-01

Degradation of a Ni-16Cr-25Al-0.06Zr overlay coating on a Ni-22Cr substrate was examined after oxidation accompanied by thermal cycling. Concentration/distance profiles were measured in the coating and substrate after various one-hour cycles at 1150 C. A numerical model was developed to simulate coating degradation by simultaneous oxidation and coating/substrate interdiffusion. The validity of the model was confirmed by comparison of predicted and measured concentration/distance profiles. The ability of the model to identify critical system parameters was demonstrated for the case of the initial Al and Cr content of the coating and substrate.

Evaluation of hardboard manufacturing process wastewater as a feedstream for ethanol production.

PubMed

Groves, Stephanie; Liu, Jifei; Shonnard, David; Bagley, Susan

2013-07-01

Waste streams from the wood processing industry can serve as feedstream for ethanol production from biomass residues. Hardboard manufacturing process wastewater (HPW) was evaluated on the basis of monomeric sugar recovery and fermentability as a novel feedstream for ethanol production. Dilute acid hydrolysis, coupled with concentration of the wastewater resulted in a hydrolysate with 66 g/l total fermentable sugars. As xylose accounted for 53 % of the total sugars, native xylose-fermenting yeasts were evaluated for their ability to produce ethanol from the hydrolysate. The strains selected were, in decreasing order by ethanol yields from xylose (Y p/s, based on consumed sugars), Scheffersomyces stipitis ATCC 58785 (CBS 6054), Pachysolen tannophilus ATCC 60393, and Kluyveromyces marxianus ATCC 46537. The yeasts were compared on the basis of substrate utilization and ethanol yield during fermentations of the hydrolysate, measured using an HPLC. S. stipitis, P. tannophilus, and K. marxianus produced 0.34, 0.31, and 0.36 g/g, respectively. The yeasts were able to utilize between 58 and 75 % of the available substrate. S. stipitis outperformed the other yeast during the fermentation of the hydrolysate; consuming the highest concentration of available substrate and producing the highest ethanol concentration in 72 h. Due to its high sugar content and low inhibitor levels after hydrolysis, it was concluded that HPW is a suitable feedstream for ethanol production by S. stipitis.

High solids co-digestion of food and landscape waste and the potential for ammonia toxicity.

PubMed

Drennan, Margaret F; DiStefano, Thomas D

2014-07-01

A pilot-scale study was completed to determine the feasibility of high-solids anaerobic digestion (HSAD) of a mixture of food and landscape wastes at a university in central Pennsylvania (USA). HSAD was stable at low loadings (2g COD/L-day), but developed inhibitory ammonia concentrations at high loadings (15 g COD/L-day). At low loadings, methane yields were 232 L CH4/kg COD fed and 229 L CH4/kg VS fed, and at high loadings yields were 211 L CH4/kg COD fed and 272 L CH4/kg VS fed. Based on characterization and biodegradability studies, food waste appears to be a good candidate for HSAD at low organic loading rates; however, the development of ammonia inhibition at high loading rates suggests that the C:N ratio is too low for use as a single substrate. The relatively low biodegradability of landscape waste as reported herein made it an unsuitable substrate to increase the C:N ratio. Codigestion of food waste with a substrate high in bioavailable carbon is recommended to increase the C:N ratio sufficiently to allow HSAD at loading rates of 15 g COD/L-day. Copyright © 2014 Elsevier Ltd. All rights reserved.

Trace metal bioavailability: Modeling chemical and biological interactions of sediment-bound zinc

USGS Publications Warehouse

Luoma, S. N.; Bryan, G.W.; Jenne, Everett A.

1979-01-01

Extractable concentrations of sediment-bound Zn, as modified by the physicochemical form of the metal in the sediments, controlled Zn concentrations in the deposit-feeding bivalvesScrobicularia plana (collected from 40 stations in 17 estuaries in southwest England) andMacoma balthica (from 28 stations in San Francisco Bay). Over a wide range of concentrations, a significant correlation was found between ammonium acetate-soluble concentrations of Zn in sediments and Zn concentrations in Scrobicularia. This correlation was insufficiently precise to be of predictive value for Scrobicularia, and did not hold for Macoma over the narrower range of Zn concentrations observed in San Francisco Bay. Strong correlation of Zn concentrations inScrobicularia and the bioavailability of sediment-bound Zn to Macoma with ratios of sorption substrate (oxides of iron and manganese, organic carbon, carbonates, humic materials) concentrations in sediments were found in both the English and San Francisco Bay study areas. These correlations were attributed to substrate competition for sorption of Zn within sediments, assuming: 1) competition for sorption of Zn was largely controlled by the relative concentrations of substrates present in the sediments and 2) the bioavailability of Zn to the deposit feeders was determined by the partitioning of Zn among the substrates. The correlations indicated that the availability of Zn to the bivalves increased when concentrations of either amorphous inorganic oxides or humic substances increased in sediments. Availability was reduced at increased concentrations of organic carbon and, in San Francisco Bay, ammonium acetate-soluble Mn. Concentrations of biologically available Zn in solution and low salinities may also have enhanced Zn uptake, although the roles of these variables were less obvious from the statistical analysis.

Structural and electrical properties of Ge-on-Si(0 0 1) layers with ultra heavy n-type doping grown by MBE

NASA Astrophysics Data System (ADS)

Yurasov, D. V.; Antonov, A. V.; Drozdov, M. N.; Yunin, P. A.; Andreev, B. A.; Bushuykin, P. A.; Baydakova, N. A.; Novikov, A. V.

2018-06-01

In this paper we report about the formation of ultra heavy doped n-Ge layers on Si(0 0 1) substrates by molecular beam epitaxy and their characterization by different independent techniques. Combined study of structural and electrical properties of fabricated layers using secondary ion mass spectroscopy, X-ray diffraction, Hall effect and reflection measurements was carried out and it has revealed the achievable charge carrier densities exceeding 1020 cm-3 without deterioration of crystalline quality of such doped layers. It was also shown that X-ray analysis can be used as a fast, reliable and non-destructive method for evaluation of the electrically active Sb concentration in heavy doped Ge layers. The appropriate set of doping density allowed to adjust the plasmonic resonance position in Ge:Sb layers in a rather wide range reaching the wavelength of 3.6 μm for the highest doping concentration. Room temperature photoluminescence confirmed the high crystalline quality of such doped layers. Our results indicated the attainability of high electron concentration in Ge:Sb layers grown on Si substrates without crystalline quality deterioration which may find potential applications in the fields of Si-based photonics and mid-IR plasmonics.

Heteroepitaxial Cu 2O thin film solar cell on metallic substrates

DOE PAGES

Wee, Sung Hun; Huang, Po-Shun; Lee, Jung-Kun; ...

2015-11-06

Heteroepitaxial, single-crystal-like Cu 2O films on inexpensive, flexible, metallic substrates can potentially be used as absorber layers for fabrication of low-cost, high-performance, non-toxic, earth-abundant solar cells. Here, we report epitaxial growth of Cu 2O films on low cost, flexible, textured metallic substrates. Cu 2O films were deposited on the metallic templates via pulsed laser deposition under various processing conditions to study the influence of processing parameters on the structural and electronic properties of the films. It is found that pure, epitaxial Cu 2O phase without any trace of CuO phase is only formed in a limited deposition window of P(Omore » 2) - temperature. The (00l) single-oriented, highly textured, Cu 2O films deposited under optimum P(O 2) - temperature conditions exhibit excellent electronic properties with carrier mobility in the range of 40-60 cm 2 V -1 s -1 and carrier concentration over 10 16 cm -3. The power conversion efficiency of 1.65% is demonstrated from a proof-of-concept Cu 2O solar cell based on epitaxial Cu 2O film prepared on the textured metal substrate.« less

Production of fructanase by a wild strain of Saccharomyces cerevisiae on tequila agave fructan.

PubMed

Corona-González, R I; Pelayo-Ortiz, C; Jacques, G; Guatemala, G; Arriola, E; Arias, J A; Toriz, G

2015-01-01

A new wild strain of Saccharomyces cerevisiae (CF3) isolated from tequila must was evaluated for production of fructanase on Agave tequilana Weber fructan (FT). Fructanase activity (F) was assessed by a 3(3) factorial design (substrate, temperature and pH). High enzymatic activity (31.1 U/ml) was found at 30 °C, pH 5, using FT (10 g/l) as substrate. The effect of initial substrate concentration on F (FT0, 5.7-66 g/l) was studied and it was found that F was highest (44.8 U/ml) at FT0 25 g/l. A 2(2) factorial experimental design with five central points was utilized to study the effect of stirring and aeration on fructanase activity; stirring exhibited a stronger effect on F. The ratio fructanase to invertase (F/S) was 0.57, which confirms that the enzymes are fructanase. Crude fructanase reached high substrate hydrolysis (48 wt%) in 10 h. It is shown that S. cerevisiae CF3 was able to produce large amounts of fructanase by growing it on fructan from A. tequilana.

Optical and structural properties in type-II InAlAs/AlGaAs quantum dots observed by photoluminescence, X-ray diffraction and transmission electron microscopy

NASA Astrophysics Data System (ADS)

Ben Daly, A.; Craciun, D.; Laura Ursu, E.; Lemaître, A.; Maaref, M. A.; Iacomi, F.; Vasile, B. S.; Craciun, V.

2017-10-01

We present the effects of AlGaAs alloy composition on InAlAs quantum dots (QDs) optical and structural properties. Photoluminescence (PL) analysis of samples having a variety of aluminium composition values covering type-II transitions clearly in QDs showed the presence of two transitions X-Sh and X-Ph. High-resolution X-ray diffraction (HRXRD) investigations showed that the layers grew epitaxially on the GaAs substrate, with no relaxation regardless the Al content of AlGaAs layer. From the reciprocal space map (RSM) investigation around (004) and (115) diffraction peaks, it was shown that the InAlAs layer is fully strained, the in-plane lattice parameters (a and b, a = b) being identical to those of GaAs substrate, while the c lattice parameter was dependent on the In and Al concentrations, being larger than that of the substrate. High-resolution transmission electronic microscopy (HRTEM) investigations confirmed that films grew epitaxially on the GaAs substrate with no visible dislocations or other major defects within the InAlAs/GaAlAs QDs structure.

Heteroepitaxial Cu2O thin film solar cell on metallic substrates

PubMed Central

Wee, Sung Hun; Huang, Po-Shun; Lee, Jung-Kun; Goyal, Amit

2015-01-01

Heteroepitaxial, single-crystal-like Cu2O films on inexpensive, flexible, metallic substrates can potentially be used as absorber layers for fabrication of low-cost, high-performance, non-toxic, earth-abundant solar cells. Here, we report epitaxial growth of Cu2O films on low cost, flexible, textured metallic substrates. Cu2O films were deposited on the metallic templates via pulsed laser deposition under various processing conditions to study the influence of processing parameters on the structural and electronic properties of the films. It is found that pure, epitaxial Cu2O phase without any trace of CuO phase is only formed in a limited deposition window of P(O2) - temperature. The (00l) single-oriented, highly textured, Cu2O films deposited under optimum P(O2) - temperature conditions exhibit excellent electronic properties with carrier mobility in the range of 40–60 cm2 V−1 s−1 and carrier concentration over 1016 cm−3. The power conversion efficiency of 1.65% is demonstrated from a proof-of-concept Cu2O solar cell based on epitaxial Cu2O film prepared on the textured metal substrate. PMID:26541499

Alternative soilless media for growing Petunia x hybrida and Impatiens wallerana: physical behavior, effect of fertilization and nitrate losses.

PubMed

Chavez, Walter; Di Benedetto, Adalberto; Civeira, Gabriela; Lavado, Raúl

2008-11-01

The use of alternative soilless media for the production of potted plants requires knowledge of their physical and chemical characteristics to result in the best conditions for plant growth. We investigated the use of alternative soilless media based on river waste and Sphagnun sp. and Carex sp. from Argentinean peatlands on Petuniaxhybrida and Impatiens wallerana production at two fertilization levels (200 and 400mgl(-1)N). River waste or 'temperate peat' is the name given to a material, resulting from the accumulation of aquatic plant residues under an anaerobic subtropical environment, which is dredged from river banks. Our results showed that alternative substrates based on river waste can be used to grow high quality plants. This result was not fully explained on the basis of established methods to evaluate substrate quality. Highly concentrated fertigation solution decreased the substrate quality parameters and plant growth. Nitrate leaching from the alternative substrates containing river waste was lower than the standard peat-based materials, which makes river waste desirable from a sustainable pot production system perspective. River waste and Carex peat are suitable alternatives to Sphagnum peat from the Northern Hemisphere.

The influence of ozone on atmospheric emissions of gaseous elemental mercury and reactive gaseous mercury from substrates

USGS Publications Warehouse

Engle, M.A.; Sexauer, Gustin M.; Lindberg, S.E.; Gertler, A.W.; Ariya, P.A.

2005-01-01

Experiments were performed to investigate the effect of ozone (O 3) on mercury (Hg) emission from a variety of Hg-bearing substrates. Substrates with Hg(II) as the dominant Hg phase exhibited a 1.7 to 51-fold increase in elemental Hg (Hgo) flux and a 1.3 to 8.6-fold increase in reactive gaseous mercury (RGM) flux in the presence of O3-enriched clean (50 ppb O3; 8 substrates) and ambient air (up to ???70 ppb O3; 6 substrates), relative to clean air (oxidant and Hg free air). In contrast, Hgo fluxes from two artificially Hgo-amended substrates decreased by more than 75% during exposure to O3-enriched clean air relative to clean air. Reactive gaseous mercury emissions from Hg o-amended substrates increased immediately after exposure to O 3 but then decreased rapidly. These experimental results demonstrate that O3 is very important in controlling Hg emissions from substrates. The chemical mechanisms that produced these trends are not known but potentially involve heterogenous reactions between O3, the substrate, and Hg. Our experiments suggest they are not homogenous gas-phase reactions. Comparison of the influence of O3 versus light on increasing Hgo emissions from dry Hg(II)-bearing substrates demonstrated that they have a similar amount of influence although O3 appeared to be slightly more dominant. Experiments using water-saturated substrates showed that the presence of high-substrate moisture content minimizes reactions between atmospheric O3 and substrate-bound Hg. Using conservative calculations developed in this paper, we conclude that because O3 concentrations have roughly doubled in the last 100 years, this could have increased Hgo emissions from terrestrial substrates by 65-72%. ?? 2005 Elsevier Ltd. All rights reserved.

Threonine deaminase from extremely halophilic bacteria - Cooperative substrate kinetics and salt dependence.

NASA Technical Reports Server (NTRS)

Lieberman, M. M.; Lanyi, J. K.

1972-01-01

The effect of salt on the activity, stability, and allosteric properties of catabolic threonine deaminase from Halobacterium cutirubrum was studied. The enzyme exhibits sigmoidal kinetics with the substrate, threonine. The Hill slope is 1.55 at pH 10. The enzyme is activated by ADP at low substrate concentrations. In the presence of this effector, sigmoidal kinetics are no longer observed. At pH 10, in the absence of ADP, enzyme activity increases with increasing NaCl concentration from 0 to 4 M.

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.

Efficient surface enhanced Raman scattering on confeito-like gold nanoparticle-adsorbed self-assembled monolayers.

PubMed

Chang, Chia-Chi; Imae, Toyoko; Chen, Liang-Yih; Ujihara, Masaki

2015-12-28

Confeito-like gold nanoparticles (AuNPs; average diameter = 80 nm) exhibiting a plasmon absorption band at 590 nm were adsorbed through immersion-adsorption on two self-assembled monolayers (SAMs) of 3-aminopropyltriethoxysilane (APTES-SAM) and polystyrene spheres coated with amine-terminated poly(amido amine) dendrimers (DEN/PS-SAM). The surface enhanced Raman scattering (SERS) effect on the SAM substrates was examined using the molecules of a probe dye, rhodamine 6G (R6G). The Raman scattering was strongly intensified on both substrates, but the enhancement factor (>10,000) of the AuNP/DEN/PS-SAM hierarchy substrate was 5-10 times higher than that of the AuNP/APTES-SAM substrate. This strong enhancement is attributed to the large surface area of the substrate and the presence of hot spots. Furthermore, analyzing the R6G concentration dependence of SERS suggested that the enhancement mechanism effectively excited the R6G molecules in the first layer on the hot spots and invoked the strong SERS effect. These results indicate that the SERS activity of confeito-like AuNPs on SAM substrates has high potential in molecular electronic devices and ultrasensitive analyses.

Kinetics of suicide substrates. Practical procedures for determining parameters.

PubMed Central

Waley, S G

1985-01-01

Many clinically important or mechanistically interesting inhibitors react with enzymes by a branched pathway in which inactivation of the enzyme and formation of product are competing reactions. The steady-state kinetics for this pathway [Waley (1980) Biochem. J. 185, 771-773] gave equations for progress curves that were cumbersome. A convenient linear plot is now described. The time (t1/2) for 50% inactivation of the enzyme (this is also the time for 50% formation of product), or for 50% loss of substrate, is measured in a series of experiments in which the concentration of inhibitor, [I]0, is varied; in these experiments the ratio of the concentration of enzyme to the concentration of inhibitor is kept fixed. Then a plot of [I]0 X t1/2 against [I]0 is linear, and the kinetic parameters can be found from the slope and intercept. Furthermore, simplifications of the equations for progress curves are described that are valid when the concentration of inhibitors is high, or is low, or when the extent of reaction is low. The use of simulated data has shown that the recommended methods are not unduly sensitive to experimental error. PMID:4004802

Free energy analysis of cell spreading.

PubMed

McEvoy, Eóin; Deshpande, Vikram S; McGarry, Patrick

2017-10-01

In this study we present a steady-state adaptation of the thermodynamically motivated stress fiber (SF) model of Vigliotti et al. (2015). We implement this steady-state formulation in a non-local finite element setting where we also consider global conservation of the total number of cytoskeletal proteins within the cell, global conservation of the number of binding integrins on the cell membrane, and adhesion limiting ligand density on the substrate surface. We present a number of simulations of cell spreading in which we consider a limited subset of the possible deformed spread-states assumed by the cell in order to examine the hypothesis that free energy minimization drives the process of cell spreading. Simulations suggest that cell spreading can be viewed as a competition between (i) decreasing cytoskeletal free energy due to strain induced assembly of cytoskeletal proteins into contractile SFs, and (ii) increasing elastic free energy due to stretching of the mechanically passive components of the cell. The computed minimum free energy spread area is shown to be lower for a cell on a compliant substrate than on a rigid substrate. Furthermore, a low substrate ligand density is found to limit cell spreading. The predicted dependence of cell spread area on substrate stiffness and ligand density is in agreement with the experiments of Engler et al. (2003). We also simulate the experiments of Théry et al. (2006), whereby initially circular cells deform and adhere to "V-shaped" and "Y-shaped" ligand patches. Analysis of a number of different spread states reveals that deformed configurations with the lowest free energy exhibit a SF distribution that corresponds to experimental observations, i.e. a high concentration of highly aligned SFs occurs along free edges, with lower SF concentrations in the interior of the cell. In summary, the results of this study suggest that cell spreading is driven by free energy minimization based on a competition between decreasing cytoskeletal free energy and increasing passive elastic free energy. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effect of respiration buffer composition on mitochondrial metabolism and function.

PubMed

Wollenman, Lucas C; Vander Ploeg, Matthew R; Miller, Mackinzie L; Zhang, Yizhu; Bazil, Jason N

2017-01-01

Functional studies on isolated mitochondria critically rely on the right choice of respiration buffer. Differences in buffer composition can lead to dramatically different respiration rates leading to difficulties in comparing prior studies. The ideal buffer facilities high ADP-stimulated respiratory rates and minimizes substrate transport effects so that the ability to distinguish between various treatments and conditions is maximal. In this study, we analyzed a variety of respiration buffers and substrate combinations to determine the optimal conditions to support mitochondrial function through ADP-stimulated respiration and uncoupled respiration using FCCP. The buffers consisted of a standard KCl based buffer (B1) and three modified buffers with chloride replaced by the K-lactobionate, sucrose, and the antioxidant taurine (B2) or K-gluconate (B3). The fourth buffer (B4) was identical to B2 except that K-lactobionate was replaced with K-gluconate. The substrate combinations consisted of metabolites that utilize different pathways of mitochondrial metabolism. To test mitochondrial function, we used isolated cardiac guinea pig mitochondria and measured oxygen consumption for three respiratory states using an Oroboros Oxygraph-2k. These states were the leak state (energized mitochondria in the absence of adenylates), ADP-stimulated state (energized mitochondria in the presence of saturating ADP concentrations), and uncoupled state (energized mitochondria in the presence of FCCP). On average across all substrate combinations, buffers B2, B3, and B4 had an increase of 16%, 26%, and 35% for the leak state, ADP-simulated state, and uncoupled state, respectively, relative to rates using B1. The common feature distinguishing these buffers from B1 is the notable lack of high chloride concentrations. Based on the respiratory rate metrics obtained with the substrate combinations, we conclude that the adenine nucleotide translocase, the dicarboxylate carrier, and the alpha-ketoglutarate exchanger are partially inhibited by chloride. Therefore, when the goal is to maximize ADP-stimulated respiration, buffers containing K-lactobionate or K-gluconate are superior choices compared to the standard KCl-based buffers.

The effect of respiration buffer composition on mitochondrial metabolism and function

PubMed Central

Wollenman, Lucas C.; Vander Ploeg, Matthew R.; Miller, Mackinzie L.; Zhang, Yizhu

2017-01-01

Functional studies on isolated mitochondria critically rely on the right choice of respiration buffer. Differences in buffer composition can lead to dramatically different respiration rates leading to difficulties in comparing prior studies. The ideal buffer facilities high ADP-stimulated respiratory rates and minimizes substrate transport effects so that the ability to distinguish between various treatments and conditions is maximal. In this study, we analyzed a variety of respiration buffers and substrate combinations to determine the optimal conditions to support mitochondrial function through ADP-stimulated respiration and uncoupled respiration using FCCP. The buffers consisted of a standard KCl based buffer (B1) and three modified buffers with chloride replaced by the K-lactobionate, sucrose, and the antioxidant taurine (B2) or K-gluconate (B3). The fourth buffer (B4) was identical to B2 except that K-lactobionate was replaced with K-gluconate. The substrate combinations consisted of metabolites that utilize different pathways of mitochondrial metabolism. To test mitochondrial function, we used isolated cardiac guinea pig mitochondria and measured oxygen consumption for three respiratory states using an Oroboros Oxygraph-2k. These states were the leak state (energized mitochondria in the absence of adenylates), ADP-stimulated state (energized mitochondria in the presence of saturating ADP concentrations), and uncoupled state (energized mitochondria in the presence of FCCP). On average across all substrate combinations, buffers B2, B3, and B4 had an increase of 16%, 26%, and 35% for the leak state, ADP-simulated state, and uncoupled state, respectively, relative to rates using B1. The common feature distinguishing these buffers from B1 is the notable lack of high chloride concentrations. Based on the respiratory rate metrics obtained with the substrate combinations, we conclude that the adenine nucleotide translocase, the dicarboxylate carrier, and the alpha-ketoglutarate exchanger are partially inhibited by chloride. Therefore, when the goal is to maximize ADP-stimulated respiration, buffers containing K-lactobionate or K-gluconate are superior choices compared to the standard KCl-based buffers. PMID:29091971

Composition variations in pulsed-laser-deposited Y-Ba-Cu-O thin films as a function of deposition parameters

NASA Technical Reports Server (NTRS)

Foote, M. C.; Jones, B. B.; Hunt, B. D.; Barner, J. B.; Vasquez, R. P.; Bajuk, L. J.

1992-01-01

The composition of pulsed-ultraviolet-laser-deposited Y-Ba-Cu-O films was examined as a function of position across the substrate, laser fluence, laser spot size, substrate temperature, target conditioning, oxygen pressure and target-substrate distance. Laser fluence, laser spot size, and substrate temperature were found to have little effect on composition within the range investigated. Ablation from a fresh target surface results in films enriched in copper and barium, both of which decrease in concentration until a steady state condition is achieved. Oxygen pressure and target-substrate distance have a significant effect on film composition. In vacuum, copper and barium are slightly concentrated at the center of deposition. With the introduction of an oxygen background pressure, scattering results in copper and barium depletion in the deposition center, an effect which increases with increasing target-substrate distance. A balancing of these two effects results in stoichiometric deposition.

Study of Enzymatic Hydrolysis of Fructans from Agave salmiana Characterization and Kinetic Assessment

PubMed Central

Michel-Cuello, Christian; Ortiz-Cerda, Imelda; Moreno-Vilet, Lorena; Grajales-Lagunes, Alicia; Moscosa-Santillán, Mario; Bonnin, Johanne; González-Chávez, Marco Martín; Ruiz-Cabrera, Miguel

2012-01-01

Fructans were extracted from Agave salmiana juice, characterized and subjected to hydrolysis process using a commercial inulinase preparation acting freely. To compare the performance of the enzymatic preparation, a batch of experiments were also conducted with chicory inulin (reference). Hydrolysis was performed for 6 h at two temperatures (50, 60°C) and two substrate concentrations (40, 60 mg/ml). Hydrolysis process was monitored by measuring the sugars released and residual substrate by HPLC. A mathematical model which describes the kinetics of substrate degradation as well as fructose production was proposed to analyze the hydrolysis assessment. It was found that kinetics were significantly influenced by temperature, substrate concentration, and type of substrate (P < 0.01). The extent of substrate hydrolysis varied from 82 to 99%. Hydrolysis product was mainly constituted of fructose, obtaining from 77 to 96.4% of total reducing sugars. PMID:22629216

Comparative Emissions of Random Orbital Sanding between Conventional and Self-Generated Vacuum Systems

PubMed Central

Liverseed, David R.

2013-01-01

Conventional abrasive sanding generates high concentrations of particles. Depending on the substrate being abraded and exposure duration, overexposure to the particles can cause negative health effects ranging from respiratory irritation to cancer. The goal of this study was to understand the differences in particle emissions between a conventional random orbital sanding system and a self-generated vacuum random orbital sanding system with attached particle filtration bag. Particle concentrations were sampled for each system in a controlled test chamber for oak wood, chromate painted (hexavalent chromium) steel panels, and gel-coated (titanium dioxide) fiberglass panels using a Gesamtstaub-Probenahmesystem (GSP) sampler at three different locations adjacent to the sanding. Elevated concentrations were reported for all particles in the samples collected during conventional sanding. The geometric mean concentration ratios for the three substrates ranged from 320 to 4640 times greater for the conventional sanding system than the self-generated vacuum sanding system. The differences in the particle concentration generated by the two sanding systems were statistically significant with the two sample t-test (P < 0.0001) for all three substances. The data suggest that workers using conventional sanding systems could utilize the self-generated vacuum sanding system technology to potentially reduce exposure to particles and mitigate negative health effects. PMID:23065674

Comparative emissions of random orbital sanding between conventional and self-generated vacuum systems.

PubMed

Liverseed, David R; Logan, Perry W; Johnson, Carl E; Morey, Sandy Z; Raynor, Peter C

2013-03-01

Conventional abrasive sanding generates high concentrations of particles. Depending on the substrate being abraded and exposure duration, overexposure to the particles can cause negative health effects ranging from respiratory irritation to cancer. The goal of this study was to understand the differences in particle emissions between a conventional random orbital sanding system and a self-generated vacuum random orbital sanding system with attached particle filtration bag. Particle concentrations were sampled for each system in a controlled test chamber for oak wood, chromate painted (hexavalent chromium) steel panels, and gel-coated (titanium dioxide) fiberglass panels using a Gesamtstaub-Probenahmesystem (GSP) sampler at three different locations adjacent to the sanding. Elevated concentrations were reported for all particles in the samples collected during conventional sanding. The geometric mean concentration ratios for the three substrates ranged from 320 to 4640 times greater for the conventional sanding system than the self-generated vacuum sanding system. The differences in the particle concentration generated by the two sanding systems were statistically significant with the two sample t-test (P < 0.0001) for all three substances. The data suggest that workers using conventional sanding systems could utilize the self-generated vacuum sanding system technology to potentially reduce exposure to particles and mitigate negative health effects.

Novel Substrates as Sources of Ancient DNA: Prospects and Hurdles

PubMed Central

Green, Eleanor Joan

2017-01-01

Following the discovery in the late 1980s that hard tissues such as bones and teeth preserve genetic information, the field of ancient DNA analysis has typically concentrated upon these substrates. The onset of high-throughput sequencing, combined with optimized DNA recovery methods, has enabled the analysis of a myriad of ancient species and specimens worldwide, dating back to the Middle Pleistocene. Despite the growing sophistication of analytical techniques, the genetic analysis of substrates other than bone and dentine remain comparatively “novel”. Here, we review analyses of other biological substrates which offer great potential for elucidating phylogenetic relationships, paleoenvironments, and microbial ecosystems including (1) archaeological artifacts and ecofacts; (2) calcified and/or mineralized biological deposits; and (3) biological and cultural archives. We conclude that there is a pressing need for more refined models of DNA preservation and bespoke tools for DNA extraction and analysis to authenticate and maximize the utility of the data obtained. With such tools in place the potential for neglected or underexploited substrates to provide a unique insight into phylogenetics, microbial evolution and evolutionary processes will be realized. PMID:28703741

Roughness of Ti Substrates for Control of the Preferred Orientation of TiO 2 Nanotube Arrays as a New Orientation Factor

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

Seong, Won Mo; Kim, Dong Hoe; Park, Ik Jae

2015-06-11

We report the surface roughness of a Ti substrate as a critical factor for controlling the degree of the preferred orientation of anatase TiO2 nanotube arrays (NTAs) which are synthesized by anodization and a subsequent annealing process. The degree of the preferred orientation to the (004) plane of the anatase crystal structure has a strong dependency on the root-mean-square roughness (Sq) of the initial Ti substrate when the roughness-controlled substrates are anodized in an ethylene glycol-based electrolyte containing ~2 wt % of water. Highly preferred oriented NTAs were obtained from low-Sq (<10 nm) substrates, which were accompanied by uniform poremore » distribution and low concentration of hydroxyl ions in as-anodized amorphous NTAs. The mechanism of the preferred oriented crystallization of nanometer-scaled tube walls is explained considering the microscopic geometrical uniformity of the oxide barrier and nanopores at the early stage of anodization, which affected the local electric field and thus the insertion of the hydroxyl group into the amorphous TiO2 tube walls.« less

Electrochemical Fabrication of Nanostructures on Porous Silicon for Biochemical Sensing Platforms.

PubMed

Ko, Euna; Hwang, Joonki; Kim, Ji Hye; Lee, Joo Heon; Lee, Sung Hwan; Tran, Van-Khue; Chung, Woo Sung; Park, Chan Ho; Choo, Jaebum; Seong, Gi Hun

2016-01-01

We present a method for the electrochemical patterning of gold nanoparticles (AuNPs) or silver nanoparticles (AgNPs) on porous silicon, and explore their applications in: (1) the quantitative analysis of hydroxylamine as a chemical sensing electrode and (2) as a highly sensitive surface-enhanced Raman spectroscopy (SERS) substrate for Rhodamine 6G. For hydroxylamine detection, AuNPs-porous silicon can enhance the electrochemical oxidation of hydroxylamine. The current changed linearly for concentrations ranging from 100 μM to 1.32 mM (R(2) = 0.995), and the detection limit was determined to be as low as 55 μM. When used as SERS substrates, these materials also showed that nanoparticles decorated on porous silicon substrates have more SERS hot spots than those decorated on crystalline silicon substrates, resulting in a larger SERS signal. Moreover, AgNPs-porous silicon provided five-times higher signal compared to AuNPs-porous silicon. From these results, we expect that nanoparticles decorated on porous silicon substrates can be used in various types of biochemical sensing platforms.

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

Inhibition of Glucuronokinase by Substrate Analogs 1

PubMed Central

Gillard, Douglas F.; Dickinson, David B.

1978-01-01

Glucuronokinase from Lilium longiflorum pollen was purified 30- to 40- fold on a blue dextran-Sepharose column. Substrate analogs were tested for inhibitory effects, and nucleotide substrate specificity of the enzyme was determined. Nine nucleotides were tested, and all were inhibitory when the substrate was ATP. ADP was competitive with ATP and had a Ki value of 0.23 mm. None of the other nucleotide triphosphates could effectively substitute for ATP as a nucleotide substrate. Ten mm dATP and ITP reacted only 3% as rapidly as 10 mm ATP, while the rates for 10 mm GTP, CTP, UTP, and TTP were less than 1%. The glucuronic acid analogs, methyl α-glucuronoside, methyl β-glucuronoside, β-glucuronic acid-1-phosphate, and 4-O-methylglucuronic acid were tested as possible enzyme inhibitors. The three methyl derivatives showed little or no inhibition. The β-glucuronic acid-1-phosphate was inhibitory, with 50% inhibition obtained at 1 to 3 mm depending on the concentration of the glucuronic acid. It is concluded that the glucuronic acid-binding site on the enzyme is highly selective. PMID:16660589

Coarse grained modeling of directed assembly to form functional nanoporous films

NASA Astrophysics Data System (ADS)

Al Khatib, Amir

A coarse-grained (CG) simulation of polyethylene glycol (PEG) and Polymethylsilsesquixane nanoparticle (PMSSQ) referred to as (NP) at different sizes and concentrations were done using the Martini coarse-grained (CG) force field. The interactions between CG PEG and CG NP were parameterized from the chemical compound of each molecule and based on Martini force field. NP particles migrates to the surface of the substrate in an agreement with the experimental output at high temperature of 800K. This demonstration of nanoparticles-polymer film to direct it to self-assemble a systematically spatial pattern using the substrate surface energy as the key gating parameter. Validation of the model comparing molecular dynamics simulations with experimental data collected from previous study. NP interaction with the substrate at low interactions energy using Lennard-Johns potential were able to direct the NP to self-assemble in a hexagonal shape up to 4 layers above the substrate. This thesis established that substrate surface energy is a key gating parameter to direct the collective behavior of functional nanoparticles to form thin nanoporous films with spatially predetermined optical/dielectric constants.

Elastic Moduli of Nanoparticle-Polymer Composite Thin Films via Buckling on Elastomeric Substrates

NASA Astrophysics Data System (ADS)

Yuan, Hongyi; Karim, Alamgir; University of Akron Team

2011-03-01

Polymeric thin films find applications in diverse areas such as coatings, barriers and packaging. The dispersion of nanoparticles into the films was proven to be an effective method to generate tunable properties, particularly mechanical strength. However, there are very few methods for mechanical characterization of the composite thin films with high accuracy. In this study, nanometric polystyrene and polyvinyl alcohol films with uniformly dispersed cobalt and Cloisite nanoparticles at varying concentrations were synthesized via flow-coating and then transferred to crosslinked polydimethylsiloxane (PDMS) flexible substrates. The technique of Strain-Induced Elastic Buckling Instability for Mechanical Measurements (SIEBIMM) was employed to determine the elastic moduli of the films, which were calculated from the buckling patterns generated by applying compressive stresses. Results on moduli of films as a function of the concentrations of nanoparticles and the thicknesses of the composite films will be presented. *Corresponding author: alamgir@uakron.edu

Chlorine incorporation in silicon films deposited by low-pressure rf discharges in gas mixtures of SICL/sub 4/ + H/sup 2/ + AR

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

Manory, R; Auni, R; Grill, A

1984-12-01

Silicon films were deposited from tetrachlorosilane by its dissociation in argon and hydrogen rf plasma at a pressure of 2 Torr. The concentration of chlorine incorporated in the films was found to be dependent on the macrovariables of the plasma such as power input and substrate position in the plasma reactor. Mass spectrometric measurements of the plasma showed that the concentration of HCI in the plasma was strongly dependent on the power input and on position in the plasma along the gas stream. At high input powers the HCI formed in the plasma dissociates to free radicals, contributing to amore » recombination process in the gas phase and codeposition with silicon on the substrate. The correlation between the HCI reactions in the plasma and the incorporation of CL in the deposit is shown.« less

Rapid transporter regulation prevents substrate flow traffic jams in boron transport

PubMed Central

Sotta, Naoyuki; Duncan, Susan; Tanaka, Mayuki; Sato, Takafumi

2017-01-01

Nutrient uptake by roots often involves substrate-dependent regulated nutrient transporters. For robust uptake, the system requires a regulatory circuit within cells and a collective, coordinated behaviour across the tissue. A paradigm for such systems is boron uptake, known for its directional transport and homeostasis, as boron is essential for plant growth but toxic at high concentrations. In Arabidopsis thaliana, boron uptake occurs via diffusion facilitators (NIPs) and exporters (BORs), each presenting distinct polarity. Intriguingly, although boron soil concentrations are homogenous and stable, both transporters manifest strikingly swift boron-dependent regulation. Through mathematical modelling, we demonstrate that slower regulation of these transporters leads to physiologically detrimental oscillatory behaviour. Cells become periodically exposed to potentially cytotoxic boron levels, and nutrient throughput to the xylem becomes hampered. We conclude that, while maintaining homeostasis, swift transporter regulation within a polarised tissue context is critical to prevent intrinsic traffic-jam like behaviour of nutrient flow. PMID:28870285

Rapid transporter regulation prevents substrate flow traffic jams in boron transport.

PubMed

Sotta, Naoyuki; Duncan, Susan; Tanaka, Mayuki; Sato, Takafumi; Marée, Athanasius Fm; Fujiwara, Toru; Grieneisen, Verônica A

2017-09-05

Nutrient uptake by roots often involves substrate-dependent regulated nutrient transporters. For robust uptake, the system requires a regulatory circuit within cells and a collective, coordinated behaviour across the tissue. A paradigm for such systems is boron uptake, known for its directional transport and homeostasis, as boron is essential for plant growth but toxic at high concentrations. In Arabidopsis thaliana , boron uptake occurs via diffusion facilitators (NIPs) and exporters (BORs), each presenting distinct polarity. Intriguingly, although boron soil concentrations are homogenous and stable, both transporters manifest strikingly swift boron-dependent regulation. Through mathematical modelling, we demonstrate that slower regulation of these transporters leads to physiologically detrimental oscillatory behaviour. Cells become periodically exposed to potentially cytotoxic boron levels, and nutrient throughput to the xylem becomes hampered. We conclude that, while maintaining homeostasis, swift transporter regulation within a polarised tissue context is critical to prevent intrinsic traffic-jam like behaviour of nutrient flow.

78 FR 59555 - Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for the Fluted...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-26

... physical and chemical water quality parameters (such as temperature, dissolved oxygen, pH, and conductivity... unknown. High temperatures can reduce dissolved oxygen concentrations in the water, which slows growth... encystment, increase oxygen consumption, reduce the speed in which they orient themselves in the substrate...

Utilization of solid catfish manure waste as carbon and nutrient source for lactic acid production.

PubMed

Shi, Suan; Li, Jing; Blersch, David M

2018-06-01

The aim of this work was to study the solid waste (manure) produced by catfish as a potential feedstock for the production of lactic acid (LA) via fermentation. The solid waste contains high levels of both carbohydrates and nutrients that are sufficient for LA bacteria. Simultaneous saccharification and co-fermentation (SSCF) was applied using enzyme and Lactobacillus pentosus, and different loadings of enzyme and solid waste were tested. Results showed LA concentrations of 35.7 g/L were obtained at 15% solids content of catfish waste. Because of the high nutrient content in the fish waste, it could also be used as supplementary substrate for nitrogen and carbon sources with other lignocellulosic materials. A combined feedstock of catfish waste and paper mill sludge was tested, increasing the final LA concentration to 43.1 g/L at 12% solids loading. The catfish waste was shown to be a potential feedstock to provide both carbon and nutrients for LA production, suggesting its use as a sole substrate or in combination with other lignocellulosic materials.

Products derived from olive leaves and fruits can alter in vitro ruminal fermentation and methane production.

PubMed

Shakeri, Pirouz; Durmic, Zoey; Vadhanabhuti, Joy; Vercoe, Philip E

2017-03-01

The industrial processing of olive generates a high quantity of by-products. The objective of this study was to examine the effects of products derived from olive trees, i.e. leaves, fruits or kernels as a sole substrate (part A), and crude extract from leaves combined with a substrate (part B) on rumen microbial fermentation in an in vitro batch fermentation system. In this study, total gas production, methane production, and concentrations of volatile fatty acids (VFA) and ammonia in ruminal fluid were measured. In part A, in vitro fermentation of leaves or fruits yielded a gas and total VFA production that were comparable with control substrate, while most of them produced significantly less methane (up to 55.6%) when compared to control substrate. In part B, amongst leaf extracts, only addition of chloroform extract reduced methane production, which was also associated with a decrease (P < 0.01) in gas production. This effect was associated with a significant reduction (P < 0.01) in acetate to propionate ratio and ammonia production, but not in reduction in VFA concentrations. Olive leaf and olive leaf chloroform extract reduced ammonia production and increased the molar proportion of propionate in the rumen and can assist in developing novel feed additives for methane mitigation from the rumen. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Exo-pectinase production by Bacillus pumilus using different agricultural wastes and optimizing of medium components using response surface methodology.

PubMed

Tepe, Ozlem; Dursun, Arzu Y

2014-01-01

In this research, the production of exo-pectinase by Bacillus pumilus using different agricultural wastes was studied. Agricultural wastes containing pectin such as wheat bran, sugar beet pulp, sunflower plate, orange peel, banana peel, apple pomace and grape pomace were tested as substrates, and activity of exo-pectinase was determined only in the mediums containing sugar beet pulp and wheat bran. Then, effects of parameters such as concentrations of solid substrate (wheat bran and sugar beet pulp) (A), ammonium sulphate (B) and yeast extract (C) on the production of exo-pectinase were investigated by response surface methodology. First, wheat bran was used as solid substrate, and it was determined that exo-pectinase activity increased when relatively low concentrations of ammonium sulphate (0.12-0.21% w/v) and yeast extract (0.12-0.3% w/v) and relatively high wheat bran (~5-6% w/v) were used. Then, exo-pectinase production was optimized by response surface methodology using sugar beet pulp as a solid substrate. In comparison to P values of the coefficients, values of not greater than 0.05 of A and B (2) showed that the effect of these process variables in exo-pectinase production was important and that changes done in these variables will alter the enzyme activity.

Electrical characterisation of deep level defects in Be-doped AlGaAs grown on (100) and (311)A GaAs substrates by MBE

PubMed Central

2011-01-01

The growth of high mobility two-dimensional hole gases (2DHGs) using GaAs-GaAlAs heterostructures has been the subject of many investigations. However, despite many efforts hole mobilities in Be-doped structures grown on (100) GaAs substrate remained considerably lower than those obtained by growing on (311)A oriented surface using silicon as p-type dopant. In this study we will report on the properties of hole traps in a set of p-type Be-doped Al0.29Ga0.71As samples grown by molecular beam epitaxy on (100) and (311)A GaAs substrates using deep level transient spectroscopy (DLTS) technique. In addition, the effect of the level of Be-doping concentration on the hole deep traps is investigated. It was observed that with increasing the Be-doping concentration from 1 × 1016 to 1 × 1017 cm-3 the number of detected electrically active defects decreases for samples grown on (311)A substrate, whereas, it increases for (100) orientated samples. The DLTS measurements also reveal that the activation energies of traps detected in (311)A are lower than those in (100). From these findings it is expected that mobilities of 2DHGs in Be-doped GaAs-GaAlAs devices grown on (311)A should be higher than those on (100). PMID:21711687

Landscape-level variation in forest structure and biogeochemistry across a substrate age gradient in Hawaii.

PubMed

Vitousek, Peter; Asner, Gregory P; Chadwick, Oliver A; Hotchkiss, Sara

2009-11-01

We compared forest canopy heights and nitrogen concentrations in long-term research sites and in 2 x 2 km landscapes surrounding these sites along a substrate age gradient in the Hawaiian Islands. Both remote airborne and ground-based measurements were used to characterize processes that control landscape-level variation in canopy properties. We integrated a waveform light detection and ranging (LiDAR) system, a high-resolution imaging spectrometer, and a global positioning system/inertial measurement unit to provide highly resolved images of ground topography, canopy heights, and canopy nitrogen concentrations (1) within a circle 50 m in radius focused on a long-term study site in the center of each landscape; (2) for the entire 2 x 2 km landscape regardless of land cover; and (3) after stratification, for our target cover class, native-dominated vegetation on constructional geomorphic surfaces throughout each landscape. Remote measurements at all scales yielded the same overall patterns as did ground-based measurements in the long-term sites. The two younger landscapes supported taller trees than did older landscapes, while the two intermediate-aged landscapes had higher canopy nitrogen (N) concentrations than did either young or old landscapes. However, aircraft-based analyses detected substantial variability in canopy characteristics on the landscape level, even within the target cover class. Canopy heights were more heterogeneous on the older landscapes, with coefficients of variation increasing from 23-41% to 69-78% with increasing substrate age. This increasing heterogeneity was associated with a larger patch size of canopy turnover and with dominance of most secondary successional stands by the mat-forming fern Dicranopteris linearis in the older landscapes.

Substrate-Independent Robust and Heparin-Mimetic Hydrogel Thin Film Coating via Combined LbL Self-Assembly and Mussel-Inspired Post-Cross-linking.

PubMed

Ma, Lang; Cheng, Chong; He, Chao; Nie, Chuanxiong; Deng, Jie; Sun, Shudong; Zhao, Changsheng

2015-12-02

In this work, we designed a robust and heparin-mimetic hydrogel thin film coating via combined layer-by-layer (LbL) self-assembly and mussel-inspired post-cross-linking. Dopamine-grafted heparin-like/-mimetic polymers (DA-g-HepLP) with abundant carboxylic and sulfonic groups were synthesized by the conjugation of adhesive molecule, DA, which exhibited substrate-independent adhesive affinity to various solid surfaces because of the formation of irreversible covalent bonds. The hydrogel thin film coated substrates were prepared by a three-step reaction: First, the substrates were coated with DA-g-HepLP to generate negatively charged surfaces. Then, multilayers were obtained via LbL coating of chitosan and the DA-g-HepLP. Finally, the noncovalent multilayers were oxidatively cross-linked by NaIO4. Surface ATR-FTIR and XPS spectra confirmed the successful fabrication of the hydrogel thin film coatings onto membrane substrates; SEM images revealed that the substrate-independent coatings owned 3D porous morphology. The soaking tests in highly alkaline, acid, and concentrated salt solutions indicated that the cross-linked hydrogel thin film coatings owned high chemical resistance. In comparison, the soaking tests in physiological solution indicated that the cross-linked hydrogel coatings owned excellent long-term stability. The live/dead cell staining and morphology observations of the adhered cells revealed that the heparin-mimetic hydrogel thin film coated substrates had low cell toxicity and high promotion ability for cell proliferation. Furthermore, systematic in vitro investigations of protein adsorption, platelet adhesion, blood clotting, and blood-related complement activation confirmed that the hydrogel film coated substrates showed excellent hemocompatibility. Both the results of inhibition zone and bactericidal activity indicated that the gentamycin sulfate loaded hydrogel thin films had significant inhibition capability toward both Escherichia coli and Staphylococcus aureus bacteria. Combined the above advantages, it is believed that the designed heparin-mimetic hydrogel thin films may show high potential for applications in various biological and clinical fields, such as long-term hemocompatible and drug-loading materials for implants.

Metal-Semiconductor Nanocomposites for High Efficiency Thermoelectric Power Generation

DTIC Science & Technology

2013-12-07

standard III–V compound semiconductor processing techniques with terbium- doped InGaAs of high terbium concentration, Journal of Vacuum Science...even lower the required temperature for strong covalent bonding. We performed the oxide bonding for this substrate transfer task (see Figure 16 for...appropriate controls for assessing ErSb:InGaSb and other nanocomposites of p-type III-V compound semiconductors and their alloys. UCSC group calculated

[Enzymatic conversion of tetradecanol in heterogenous phase by yeast-alcohol dehydrogenase].

PubMed

Rothe, U; Schöpp, W; Aurich, H

1976-01-01

Alcohol dehydrogenase from yeast converts long-chain primary alcohols not only in the dissolved state, but also at the surface of undissolved particles. Tetradecanol beads with a defined surface can be produced and employed as model substrate. The reaction rate was determined by the proton release accomplished in the reaction. The initial reaction rate depends on the enzyme concentration. The relation is nonlinear (vi = k-[e]0,4); the numerical value of the exponent (n = 0.4) argues in favour of a reaction occurring at the interface. The Lineweaver-Burk plots become linear if the substrate concentrations are based on the molar surface concentrations of the particles. The pH optimum for the reaction at the surface is displaced by 0.25 pH units towards the alkaline region (compared with ethanol as substrate). The activation energy of the reaction with tetradecanol beads as substrate is 30% lower than that for the ethanol oxydation.

Dependence of Morphology of SiOx Nanowires on the Supersaturation of Au-Si Alloy Liquid Droplets Formed on the Au-Coated Si Substrate

NASA Astrophysics Data System (ADS)

Zhang, Han; Li, Ji-Xue; Jin, Ai-Zi; Zhang, Ze

2001-11-01

A thermodynamic theory about the dependence of morphology of SiOx nanowires on the super-saturation of alloy liquid droplets has been proposed on the basis of the vapour-liquid-solid growth mechanism and has been supported experimentally. By changing the Si concentration in the Au-Si liquid droplets formed on the Au-coated Si substrate, firework-, tulip- and bud-shaped SiOx nanowires were synthesized by a thermal evaporation method and distributed concentrically around some void defects in the Si substrate. Voids were formed underneath the surface of the Si substrate during the thermal evaporation at 850°C and resulted in the Si-concentration deficient thus different saturation of Au-Si droplets. Electron microscopy analysis showed that the nanowires had an amorphous structure and were terminated by Au-Si particles.

Sea-urchin-like Fe3O4@C@Ag particles: an efficient SERS substrate for detection of organic pollutants

NASA Astrophysics Data System (ADS)

Ye, Yingjie; Chen, Jin; Ding, Qianqian; Lin, Dongyue; Dong, Ronglu; Yang, Liangbao; Liu, Jinhuai

2013-06-01

Ag-coated sea-urchin-like Fe3O4@C core-shell particles can be synthesized by a facile one-step solvothermal method, followed by deposition of high-density Ag nanoparticles onto the carbon surface through an in situ growth process, respectively. The as-synthesized Ag-coated Fe3O4@C particles can be used as a surface-enhanced Raman scattering (SERS) substrate holding reproducible properties under an external magnetic force. The magnetic function of the particles allows concentrating the composite particles into small spatial regions, which can be exploited to decrease the amount of material per analysis while improving its SERS detection limit. In contrast to the traditional SERS substrates, the present Fe3O4@C@Ag particles hold the advantages of enrichment of organic pollutants for improving SERS detection limit and recycled utilization.Ag-coated sea-urchin-like Fe3O4@C core-shell particles can be synthesized by a facile one-step solvothermal method, followed by deposition of high-density Ag nanoparticles onto the carbon surface through an in situ growth process, respectively. The as-synthesized Ag-coated Fe3O4@C particles can be used as a surface-enhanced Raman scattering (SERS) substrate holding reproducible properties under an external magnetic force. The magnetic function of the particles allows concentrating the composite particles into small spatial regions, which can be exploited to decrease the amount of material per analysis while improving its SERS detection limit. In contrast to the traditional SERS substrates, the present Fe3O4@C@Ag particles hold the advantages of enrichment of organic pollutants for improving SERS detection limit and recycled utilization. Electronic supplementary information (ESI) available: Additional XRD patterns and SEM images of Fe3O4@C particles, SERS spectra of 4-ATP and 4-MPY using Fe3O4@C@Ag particles as the active substrates, magnetic behaviour of Fe3O4@C and Fe3O4@C@Ag particles. See DOI: 10.1039/c3nr01273e

Lactate and Pyruvate Are Major Sources of Energy for Stallion Sperm with Dose Effects on Mitochondrial Function, Motility, and ROS Production.

PubMed

Darr, Christa R; Varner, Dickson D; Teague, Sheila; Cortopassi, Gino A; Datta, Sandipan; Meyers, Stuart A

2016-08-01

Stallion sperm rely primarily on oxidative phosphorylation for production of ATP used in sperm motility and metabolism. The objective of the study was to identify which substrates included in Biggers, Whitten, and Whittingham (BWW) media are key to optimal mitochondrial function through measurements of sperm motility parameters, mitochondrial oxygen consumption, and cellular reactive oxygen species (ROS) production. It was expected that mitochondrial substrates, pyruvate and lactate, would support sperm motility and mitochondrial function better than the glycolytic substrate, glucose, due to direct utilization within the mitochondria. Measurements were performed after incubation in modified BWW media with varying concentrations of lactate, pyruvate, and glucose. The effects of media and duration of incubation on sperm motility, ROS production, and oxygen consumption were determined using a linear mixed-effects model. Duplicate ejaculates from four stallions were used in three separate experiments to determine the effects of substrate availability and concentration on sperm motility and mitochondrial function and the relationship of oxygen consumption with cellular ROS production. The present results indicate that lactate and pyruvate are the most important sources of energy for stallion sperm motility and velocity, and elicit a dose-dependent response. Additionally, lactate and pyruvate are ideal for maximal mitochondrial function, as sperm in these media operate at a very high level of their bioenergetic capability due to the high rate of energy metabolism. Moreover, we found that addition of glucose to the media is not necessary for short-term storage of equine sperm, and may even result in reduction of mitochondrial function. Finally, we have confirmed that ROS production can be the result of mitochondrial dysfunction as well as intense mitochondrial activity. © 2016 by the Society for the Study of Reproduction, Inc.

Combined substrate, enzyme and yeast feed in simultaneous saccharification and fermentation allow bioethanol production from pretreated spruce biomass at high solids loadings

PubMed Central

2014-01-01

Background Economically feasible cellulosic ethanol production requires that the process can be operated at high solid loadings, which currently imparts technical challenges including inefficient mixing leading to heat and mass transfer limitations and high concentrations of inhibitory compounds hindering microbial activity during simultaneous saccharification and fermentation (SSF) process. Consequently, there is a need to develop cost effective processes overcoming the challenges when working at high solid loadings. Results In this study we have modified the yeast cultivation procedure and designed a SSF process to address some of the challenges at high water insoluble solids (WIS) content. The slurry of non-detoxified pretreated spruce when used in a batch SSF at 19% (w/w) WIS was found to be inhibitory to Saccharomyces cerevisiae Thermosacc that produced 2 g l-1 of ethanol. In order to reduce the inhibitory effect, the non-washed solid fraction containing reduced amount of inhibitors compared to the slurry was used in the SSF. Further, the cells were cultivated in the liquid fraction of pretreated spruce in a continuous culture wherein the outflow of cell suspension was used as cell feed to the SSF reactor in order to maintain the metabolic state of the cell. Enhanced cell viability was observed with cell, enzyme and substrate feed in a SSF producing 40 g l-1 ethanol after 96 h corresponding to 53% of theoretical yield based on available hexose sugars compared to 28 g l-1 ethanol in SSF with enzyme and substrate feed but no cell feed resulting in 37% of theoretical yield at a high solids loading of 20% (w/w) WIS content. The fed-batch SSF also significantly eased the mixing, which is usually challenging in batch SSF at high solids loading. Conclusions A simple modification of the cell cultivation procedure together with a combination of yeast, enzyme and substrate feed in a fed-batch SSF process, made it possible to operate at high solids loadings in a conventional bioreactor. The proposed process strategy significantly increased the yeast cell viability and overall ethanol yield. It was also possible to obtain 4% (w/v) ethanol concentration, which is a minimum requirement for an economical distillation process. PMID:24713027

Combined substrate, enzyme and yeast feed in simultaneous saccharification and fermentation allow bioethanol production from pretreated spruce biomass at high solids loadings.

PubMed

Koppram, Rakesh; Olsson, Lisbeth

2014-04-08

Economically feasible cellulosic ethanol production requires that the process can be operated at high solid loadings, which currently imparts technical challenges including inefficient mixing leading to heat and mass transfer limitations and high concentrations of inhibitory compounds hindering microbial activity during simultaneous saccharification and fermentation (SSF) process. Consequently, there is a need to develop cost effective processes overcoming the challenges when working at high solid loadings. In this study we have modified the yeast cultivation procedure and designed a SSF process to address some of the challenges at high water insoluble solids (WIS) content. The slurry of non-detoxified pretreated spruce when used in a batch SSF at 19% (w/w) WIS was found to be inhibitory to Saccharomyces cerevisiae Thermosacc that produced 2 g l-1 of ethanol. In order to reduce the inhibitory effect, the non-washed solid fraction containing reduced amount of inhibitors compared to the slurry was used in the SSF. Further, the cells were cultivated in the liquid fraction of pretreated spruce in a continuous culture wherein the outflow of cell suspension was used as cell feed to the SSF reactor in order to maintain the metabolic state of the cell. Enhanced cell viability was observed with cell, enzyme and substrate feed in a SSF producing 40 g l-1 ethanol after 96 h corresponding to 53% of theoretical yield based on available hexose sugars compared to 28 g l-1 ethanol in SSF with enzyme and substrate feed but no cell feed resulting in 37% of theoretical yield at a high solids loading of 20% (w/w) WIS content. The fed-batch SSF also significantly eased the mixing, which is usually challenging in batch SSF at high solids loading. A simple modification of the cell cultivation procedure together with a combination of yeast, enzyme and substrate feed in a fed-batch SSF process, made it possible to operate at high solids loadings in a conventional bioreactor. The proposed process strategy significantly increased the yeast cell viability and overall ethanol yield. It was also possible to obtain 4% (w/v) ethanol concentration, which is a minimum requirement for an economical distillation process.

Common Ion Effects In Zeoponic Substrates: Dissolution And Cation Exchange Variations Due to Additions of Calcite, Dolomite and Wollastonite

NASA Technical Reports Server (NTRS)

Beiersdorfer, R. E.; Ming, D. W.; Galindo, C., Jr.

2003-01-01

c1inoptilolite-rich tuff-hydroxyapatite mixture (zeoponic substrate) has the potential to serve as a synthetic soil-additive for plant growth. Essential plant macro-nutrients such as calcium, phosphorous, magnesium, ammonium and potassium are released into solution via dissolution of the hydroxyapatite and cation exchange on zeolite charged sites. Plant growth experiments resulting in low yield for wheat have been attributed to a Ca deficiency caused by a high degree of cation exchange by the zeolite. Batch-equilibration experiments were performed in order to determine if the Ca deficiency can be remedied by the addition of a second Ca-bearing, soluble, mineral such as calcite, dolomite or wollastonite. Variations in the amount of calcite, dolomite or wollastonite resulted in systematic changes in the concentrations of Ca and P. The addition of calcite, dolomite or wollastonite to the zeoponic substrate resulted in an exponential decrease in the phosphorous concentration in solution. The exponential rate of decay was greatest for calcite (5.60 wt. % -I), intermediate for wollastonite (2.85 wt.% -I) and least for dolomite (1.58 wt.% -I). Additions of the three minerals resulted in linear increases in the calcium concentration in solution. The rate of increase was greatest for calcite (3.64), intermediate for wollastonite (2.41) and least for dolomite (0.61). The observed changes in P and Ca concentration are consistent with the solubilities of calcite, dolomite and wollastonite and with changes expected from a common ion effect with Ca. Keywords: zeolite, zeoponics, common-ion effect, clinoptilolite, hydroxyapatite

Polyhydroxyalkanoate Production on Waste Water Treatment Plants: Process Scheme, Operating Conditions and Potential Analysis for German and European Municipal Waste Water Treatment Plants

PubMed Central

Pittmann, Timo; Steinmetz, Heidrun

2017-01-01

This work describes the production of polyhydroxyalkanoates (PHA) as a side stream process on a municipal waste water treatment plant (WWTP) and a subsequent analysis of the production potential in Germany and the European Union (EU). Therefore, tests with different types of sludge from a WWTP were investigated regarding their volatile fatty acids (VFA) production-potential. Afterwards, primary sludge was used as substrate to test a series of operating conditions (temperature, pH, retention time (RT) and withdrawal (WD)) in order to find suitable settings for a high and stable VFA production. In a second step, various tests regarding a high PHA production and stable PHA composition to determine the influence of substrate concentration, temperature, pH and cycle time of an installed feast/famine-regime were conducted. Experiments with a semi-continuous reactor operation showed that a short RT of 4 days and a small WD of 25% at pH = 6 and around 30 °C is preferable for a high VFA production rate (PR) of 1913 mgVFA/(L×d) and a stable VFA composition. A high PHA production up to 28.4% of cell dry weight (CDW) was reached at lower substrate concentration, 20 °C, neutral pH-value and a 24 h cycle time. A final step a potential analysis, based on the results and detailed data from German waste water treatment plants, showed that the theoretically possible production of biopolymers in Germany amounts to more than 19% of the 2016 worldwide biopolymer production. In addition, a profound estimation regarding the EU showed that in theory about 120% of the worldwide biopolymer production (in 2016) could be produced on European waste water treatment plants. PMID:28952533

In vitro characterization of the inhibitory effects of ketoconazole on metabolic activities of cytochrome P-450 in canine hepatic microsomes.

PubMed

Kuroha, Masanori; Kuze, Yoji; Shimoda, Minoru; Kokue, Eiichi

2002-06-01

To evaluate the inhibitory potency of ketoconazole (KTZ) on the metabolic activities of isozymes of cytochrome P-450 (CYP) in dogs. 4 healthy 1-year-old male Beagles. Hepatic microsomes were harvested from 4 dogs after euthanasia. To investigate the effects of KTZ on CYP metabolic activities, 7-ethoxyresorufin, tolbutamide, bufuralol, and midazolam hydrochloride were used as specific substrates for CYP1A1/2, CYP2C21, CYP2D15, and CYP3A12, respectively. The concentrations of metabolites formed by CYP were measured by high-performance liquid chromatography, except for the resorufin concentrations that were measured by a fluorometric method. The reaction velocity-substrate concentration data were analyzed to obtain kinetic variables, including maximum reaction velocity, Michaelis-Menten constant, and inhibitory constant (Ki). KTZ competitively inhibited 7-ethoxyresorufin O-deethylation and midazolam 4-hydroxylation; it noncompetitively inhibited tolbutamide methylhydroxylation. Bufuralol 1'-hydroxylation was inhibited slightly by KTZ. The mean Ki values of KTZ were 10.6+/-6.0, 170+/-2.5, and 0.180+/-0.131 microM for 7-ethoxyresorufin O-deethylation, tolbutamide methylhydroxylation, and midazolam 4-hydroxylation, respectively. In dogs, KTZ at a therapeutic dose may change the pharmacokinetics of CYP3A12 substrates as a result of inhibition of their biotransformation. Furthermore, no influence of KTZ on the pharmacokinetics of CYP1A1/2, CYP2C21, and CYP2D15 substrates are likely. In clinical practice, adverse drug effects may develop when KTZ is administered concomitantly with a drug that is primarily metabolized by CYP3A12.

Mechanism of product inhibition for cellobiohydrolase Cel7A during hydrolysis of insoluble cellulose.

PubMed

Olsen, Johan P; Alasepp, Kadri; Kari, Jeppe; Cruys-Bagger, Nicolaj; Borch, Kim; Westh, Peter

2016-06-01

The cellobiohydrolase cellulase Cel7A is extensively utilized in industrial treatment of lignocellulosic biomass under conditions of high product concentrations, and better understanding of inhibition mechanisms appears central in attempts to improve the efficiency of this process. We have implemented an electrochemical biosensor assay for product inhibition studies of cellulases acting on their natural substrate, cellulose. Using this method we measured the hydrolytic rate of Cel7A as a function of both product (inhibitor) concentration and substrate load. This data enabled analyses along the lines of conventional enzyme kinetic theory. We found that the product cellobiose lowered the maximal rate without affecting the Michaelis constant, and this kinetic pattern could be rationalized by two fundamentally distinct molecular mechanisms. One was simple reversibility, that is, an increasing rate of the reverse reaction, lowering the net hydrolytic velocity as product concentrations increase. Strictly this is not a case of inhibition, as no catalytically inactive is formed. The other mechanism that matched the kinetic data was noncompetitive inhibition with an inhibition constant of 490 ± 40 μM. Noncompetitive inhibition implies that the inhibitor binds with comparable strength to either free enzyme or an enzymesubstrate complex, that is, that association between enzyme and substrate has no effect on the binding of the inhibitor. This mechanism is rarely observed, but we argue, that the special architecture of Cel7A with numerous subsites for binding of both substrate and product could give rise to a true noncompetitive inhibition mechanism. Biotechnol. Bioeng. 2016;113: 1178-1186. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

An in vitro evaluation of guanfacine as a substrate for P-glycoprotein

PubMed Central

Gillis, Nancy K; Zhu, Hao-Jie; Markowitz, John S

2011-01-01

Background With a US Food and Drug Administration-labeled indication to treat attention-deficit/hyperactivity disorder (ADHD), the nonstimulant guanfacine has become the preferred α2-agonist for ADHD treatment. However, significant interindividual variability has been observed in response to guanfacine. Consequently, hypotheses of a contributing interaction with the ubiquitously expressed drug transporter, P-glycoprotein (P-gp), have arisen. We performed an in vitro study to determine if guanfacine is indeed a substrate of P-gp. Methods Intracellular accumulation of guanfacine was compared between P-gp expressing LLC-PK1/MDR1 cells and P-gp-negative LLC-PK1 cells to evaluate the potential interaction between P-gp and guanfacine. Cellular retention of guanfacine was analyzed using a high-performance liquid chromatographic-ultraviolet method. Rhodamine6G, a known P-gp substrate, was included in the study as a positive control. Results At guanfacine concentrations of 50 μM and 5 μM, intracellular accumulation of guanfacine in LLC-PK1/MDR1 cells was, 35.9% ± 4.8% and 49.0% ± 28.3% respectively, of that in LLC-PK1 cells. In comparison, the concentration of rhodamine6G, the positive P-gp substrate, in LLC-PK1/MDR1 cells was only 5% of that in LLC-PK1 cells. Conclusion The results of the intracellular accumulation study suggest that guanfacine is, at best, a weak P-gp substrate. Therefore, it is unlikely that P-gp, or any genetic variants thereof, are a determining factor in the interindividual variability of response observed with guanfacine therapy. PMID:21931492

Surface modification of GC and HOPG with diazonium, amine, azide, and olefin derivatives.

PubMed

Tanaka, Mutsuo; Sawaguchi, Takahiro; Sato, Yukari; Yoshioka, Kyoko; Niwa, Osamu

2011-01-04

Surface modification of glassy carbon (GC) and highly oriented pyrolytic graphite (HOPG) was carried out with diazonium, amine, azide, and olefin derivatives bearing ferrocene as an electroactive moiety. Features of the modified surfaces were evaluated by surface concentrations of immobilized molecule, blocking effect of the modified surface against redox reaction, and surface observation using cyclic voltammetry and electrochemical scanning tunneling microscope (EC-STM). The measurement of surface concentrations of immobilized molecule revealed the following three aspects: (i) Diazonium and olefin derivatives could modify substrates with the dense-monolayer concentration. (ii) The surface concentration of immobilized amine derivative did not reach to the dense-monolayer concentration reflecting their low reactivity. (iii) The surface modification with the dense-monolayer concentration was also possible with azide derivative, but the modified surface contained some oligomers produced by the photoreaction of azides. Besides, the blocking effect against redox reaction was observed for GC modified with diazonium derivative and for HOPG modified with diazonium and azide derivatives, suggesting fabrication of a densely modified surface. Finally, the surface observation for HOPG modified with diazonium derivative by EC-STM showed a typical monolayer structure, in which the ferrocene moieties were packed densely at random. On the basis of those results, it was demonstrated that surface modification of carbon substrates with diazonium could afford a dense monolayer similar to the self-assembled monolayer (SAM) formation.

Aspergillus fumigatus SidA is a highly specific ornithine hydroxylase with bound flavin cofactor.

PubMed

Chocklett, Samuel W; Sobrado, Pablo

2010-08-10

Ferrichrome is a hydroxamate-containing siderophore produced by the pathogenic fungus Aspergillus fumigatus under iron-limiting conditions. This siderophore contains N(5)-hydroxylated l-ornithines essential for iron binding. A. fumigatus siderophore A (Af SidA) catalyzes the flavin- and NADPH-dependent hydroxylation of l-ornithine in ferrichrome biosynthesis. Af SidA was recombinantly expressed and purified as a soluble tetramer and is the first member of this class of flavin monooxygenases to be isolated with a bound flavin cofactor. The enzyme showed typical saturation kinetics with respect to l-ornithine while substrate inhibition was observed at high concentrations of NADPH and NADH. Increasing amounts of hydrogen peroxide were measured as a function of reduced nicotinamide coenzyme concentration, indicating that inhibition was caused by increased uncoupling. Af SidA is highly specific for its amino acid substrate, only hydroxylating l-ornithine. An 8-fold preference in the catalytic efficiency was determined for NADPH compared to NADH. In the absence of substrate, Af SidA can be reduced by NADPH, and a C4a-(hydro)peroxyflavin intermediate is observed. The decay of this intermediate is accelerated by l-ornithine binding. This intermediate was only stabilized by NADPH and not by NADH, suggesting a role for NADP(+) in the stabilization of intermediates in the reaction of Af SidA. NADP(+) is a competitive inhibitor with respect to NADPH, demonstrating that Af SidA forms a ternary complex with NADP(+) and l-ornithine during catalysis. The data suggest that Af SidA likely proceeds by a sequential kinetic mechanism.

Interactions of Penicillium griseofulvum with inorganic and organic substrates: vanadium, lead and hexachlorocyclohexane

NASA Astrophysics Data System (ADS)

Ceci, Andrea; Pierro, Lucia; Riccardi, Carmela; Maggi, Oriana; Pinzari, Flavia; Gadd, Geoffrey Michael; Petrangeli Papini, Marco; Persiani, Anna Maria

2015-04-01

Soil is an essential and non-renewable resource for human beings and ecosystems. In recent years, anthropogenic activities mainly related to hydrocarbon fuel combustion, mining and industrial activities have increased the levels of vanadium in the environment, raising concern over its spread. Vanadium may be essential for some bacteria and fungi, but can have toxic effects at high concentrations. The pesticide lindane or γ-hexachlorocyclohexane (γ-HCH) and another two isomers of hexachlorocyclohexane (HCH), α-HCH, and β-HCH, were included as persistent organic pollutants in the Stockholm Convention in 2008, and their worldwide spread and toxic effects on organisms are severe environmental problems. Fungi play important roles in soil and can survive in high concentrations of toxic elements and pesticides by possessing mechanisms for the degradation, utilization and transformation of organic and inorganic substrates. The transformation of potentially toxic elements (PTEs), and degradation of chlorinated pesticides and other persistent organic pollutants may provide environmentally-friendly and economical approaches for environmental management and restoration. In this work, we have investigated the tolerance of a soil fungal species, Penicillum griseofulvum, to different hexachlorocyclohexane (HCH) isomers, α-HCH, β-HCH, δ-HCH and γ-HCH or lindane, and two PTEs, vanadium and lead in relation to growth responses and biotransformation. P. griseofulvum was isolated from soils with high levels of PTEs (including vanadium and lead), and HCH residues. P. griseofulvum was able to tolerate vanadium concentrations up to 5 mM, combinations of 2.5 mM vanadium and lead compounds, and was able to grow in the presence of a 4 mg L-1 mixture of α-HCH, β-HCH, δ-HCH and γ-HCH, and degrade these substrates. Tolerance mechanisms may explain the occurrence of fungi in polluted habitats: their roles in the biotransformation of metals and persistent organic pollutants may provide opportunities for bioremediation. (287 words)

Oil palm frond juice as future fermentation substrate: a feasibility study.

PubMed

Maail, Che Mohd Hakiman Che; Ariffin, Hidayah; Hassan, Mohd Ali; Shah, Umi Kalsom Md; Shirai, Yoshihito

2014-01-01

Oil palm frond (OPF) juice is a potential industrial fermentation substrate as it has high sugars content and the OPF are readily available daily. However, maximum sugars yield and storage stability of the OPF juice are yet to be determined. This study was conducted to determine the effect of physical pretreatment and storage duration of OPF petiole on sugars yield. Storage stability of OPF juice at different storing conditions was also investigated. It was found that OPF petiole squeezed by hydraulic pressing machine gave the highest sugars recovery at almost 40 g/kg, accounting for a recovery yield of 88%. Storage of OPF petiole up to 72 hrs prior to squeezing reduced the free sugars by 11 g/kg. Concentrated OPF juice with 95% water removal had the best storage stability at both 4 and 30°C, when it was stored for 10 days. Moreover, concentrated OPF syrup prepared by thermal processing did not give any Maillard effect on microbial growth. Based on our results, OPF juice meets all the criteria as a good fermentation substrate as it is renewable, consistently available, and easy to be obtained, it does not inhibit microbial growth and product formation, and it contains no impurities.

An unattended device for high-voltage sampling and passive measurement of thoron decay products.

PubMed

Gierl, Stefanie; Meisenberg, Oliver; Haninger, Thomas; Wielunski, Marek; Tschiersch, Jochen

2014-02-01

An integrating measurement device for the concentration of airborne thoron decay products was designed and calibrated. It is suitable for unattended use over up to several months also in inhabited dwellings. The device consists of a hemispheric capacitor with a wire mesh as the outer electrode on ground potential and the sampling substrates as the inner electrode on +7.0 kV. Negatively charged and neutral thoron decay products are accelerated to and deposited on the sampling substrates. As sampling substrates, CR39 solid-state nuclear track detectors are used in order to record the alpha decay of the sampled decay products. Nuclide discrimination is achieved by covering the detectors with aluminum foil of different thickness, which are penetrated only by alpha particles with sufficient energy. Devices of this type were calibrated against working level monitors in a thoron experimental house. The sensitivity was measured as 9.2 tracks per Bq/m(3) × d of thoron decay products. The devices were used over 8 weeks in several houses built of earthen material in southern Germany, where equilibrium equivalent concentrations of 1.4-9.9 Bq/m(3) of thoron decay products were measured.

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

Korol, A.A.; Korol, Y.A.; Kasich-Pilipenko, I.Y.

Melted slip coatings were obtained and the structural changes in the coatings and their substrates upon simultaneous heating by concentrated solar radiant energy fluxes were studied. Well known wear and corrosion resistant TiC-Ni-B and WC-Ni-B coatings 50 to 300 microns thick applied by the slip method to flat or cylindrical stainless steel and titanium specimens were examined. The specimens were heated in an SGU-5 solar heating installation with a 2 m diameter parabolic mirror concentrator in a process chamber with a quartz window under a vacuum. Metallographic analysis revealed a finely dispersed heterogeneous structure with no visible porosity, good bondingmore » of coating to substrate, and uniform distribution of carbide phase in the metal matrix of the TiC-Ni-B coatings on titanium. Results were similar for the other coatings, indicating that concentrated solar energy can produce coatings with satisfactory surface quality, good density, and a framework structure. The coating interacted with the substrate by diffusion. Most of the volume of the substrate underwent no significant changes, indicating good bond strength between coatings and substrate.« less

Simultaneous saccharification and fermentation of steam exploded duckweed: Improvement of the ethanol yield by increasing yeast titre

PubMed Central

Zhao, X.; Moates, G.K.; Elliston, A.; Wilson, D.R.; Coleman, M.J.; Waldron, K.W.

2015-01-01

This study investigated the conversion of Lemna minor biomass to bioethanol. The biomass was pre-treated by steam explosion (SE, 210 °C, 10 min) and then subjected to simultaneous saccharification and fermentation (SSF) using Cellic® CTec 2 (20 U or 0.87 FPU g−1 substrate) cellulase plus β-glucosidase (2 U g−1 substrate) and a yeast inoculum of 10% (v/v or 8.0 × 107 cells mL−1). At a substrate concentration of 1% (w/v) an ethanol yield of 80% (w/w, theoretical) was achieved. However at a substrate concentration of 20% (w/v), the ethanol yield was lowered to 18.8% (w/w, theoretical). Yields were considerably improved by increasing the yeast titre in the inoculum or preconditioning the yeast on steam exploded liquor. These approaches enhanced the ethanol yield up to 70% (w/w, theoretical) at a substrate concentration of 20% (w/v) by metabolising fermentation inhibitors. PMID:26210138

Simultaneous saccharification and fermentation of steam exploded duckweed: Improvement of the ethanol yield by increasing yeast titre.

PubMed

Zhao, X; Moates, G K; Elliston, A; Wilson, D R; Coleman, M J; Waldron, K W

2015-10-01

This study investigated the conversion of Lemna minor biomass to bioethanol. The biomass was pre-treated by steam explosion (SE, 210°C, 10 min) and then subjected to simultaneous saccharification and fermentation (SSF) using Cellic® CTec 2 (20 U or 0.87 FPU g(-1) substrate) cellulase plus β-glucosidase (2 U g(-1) substrate) and a yeast inoculum of 10% (v/v or 8.0×10(7) cells mL(-1)). At a substrate concentration of 1% (w/v) an ethanol yield of 80% (w/w, theoretical) was achieved. However at a substrate concentration of 20% (w/v), the ethanol yield was lowered to 18.8% (w/w, theoretical). Yields were considerably improved by increasing the yeast titre in the inoculum or preconditioning the yeast on steam exploded liquor. These approaches enhanced the ethanol yield up to 70% (w/w, theoretical) at a substrate concentration of 20% (w/v) by metabolising fermentation inhibitors. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Introducing Michaelis-Menten Kinetics through Simulation

ERIC Educational Resources Information Center

Halkides, Christopher J.; Herman, Russell

2007-01-01

We describe a computer tutorial that introduces the concept of the steady state in enzyme kinetics. The tutorial allows students to produce graphs of the concentrations of free enzyme, enzyme-substrate complex, and product versus time in order to learn about the approach to steady state. By using a range of substrate concentrations and rate…

Effects of substrate type on plant growth and nitrogen and nitrate concentration in spinach

USDA-ARS?s Scientific Manuscript database

The effects of three commercial substrates (a mixture of forest residues, composted grape husks, and white peat; black peat; and coir) on plant growth and nitrogen (N) and nitrate (NO3) concentration and content were evaluated in spinach (Spinacia oleracea L. cv. Tapir). Spinach seedlings were trans...

Constructed wetland using corncob charcoal substrate: pollutants removal and intensification.

PubMed

Liu, Mao; Li, Boyuan; Xue, Yingwen; Wang, Hongyu; Yang, Kai

2017-09-01

To investigate the feasibility of using corncob charcoal substrate in constructed wetlands, four laboratory-scale vertical flow constructed wetlands (VFCWs) were built. Effluent pollutant (chemical oxygen demand (COD), NH 4 + -N, total phosphorus (TP)) concentrations during the experiment were determined to reveal pollutant removal mechanisms and efficiencies at different stages. In the stable stage, a VFCW using clay ceramisite substrate under aeration attained higher COD (95.1%), and NH 4 + -N (95.1%) removal efficiencies than a VFCW using corncob charcoal substrate (91.5% COD, 91.3% NH 4 + -N) under aeration, but lower TP removal efficiency (clay ceramisite 32.0% and corncob charcoal 40.0%). The VFCW with raw corncob substrate showed stronger COD emissions (maximum concentration 3,108 mg/L) than the corncob charcoal substrate (COD was lower than influent). The VFCW using corncob charcoal substrate performed much better than the VFCW using clay ceramisite substrate under aeration when the C/N ratio was low (C/N = 1.5, TN removal efficiency 36.89%, 4.1% respectively). These results suggest that corncob charcoal is a potential substrate in VFCWs under aeration with a unique self -supplying carbon source property in the denitrification process.

Concentration of (+/-)-propranolol in isolated, perfused lungs of rat.

PubMed Central

Dollery, C T; Junod, A F

1976-01-01

1 The metabolism and the accumulation of (+/-)-propranolol have been studied in isolated lungs of the rat, perfused with an artificial medium. 2 Little or no metabolism took place during the perfusion periods (up to 10 minutes). 3 Accumulation was observed with high tissue/medium ratios for substrate concentrations of 0.2 muM to 1 mM; there was evidence for saturability, but no real plateau could be seen. The presence of two binding sites with different affinities was established. 4 Cold greatly inhibited the accumulation process at low substrate concentrations, but had no effect at 1 mM propranolol. 5 Inhibition of accumulation was measured in the presence of imipramine, desmethylimipramine, nortryptiline, chlorpromazine and of Na+-free medium. Cocaine, 5-hydroxytryptamine and noradrenaline had no effect. Lidocaine enhanced the accumulation process. Release of previously bound propranolol was accelerated in the presence of propranolol and imipramine, unaffected by a Na+-free medium and decreased by cold and by lidocaine. 6 Experiments on lung tissue slices yielded qualitatively similar results to those obtained with perfused lungs. Ouabain and KCN had no or little effect on propranolol accumulation. PMID:1276542

Catalytic properties of thermophilic lactate dehydrogenase and halophilic malate dehydrogenase at high temperature and low water activity.

PubMed

Hecht, K; Wrba, A; Jaenicke, R

1989-07-15

Thermophilic lactate dehydrogenases from Thermotoga maritima and Bacillus stearothermophilus are stable up to temperature limits close to the optimum growth temperature of their parent organisms. Their catalytic properties are anomalous in that Km shows a drastic increase with increasing temperature. At low temperatures, the effect levels off. Extreme halophilic malate dehydrogenase from Halobacterium marismortui exhibits a similar anomaly. Increasing salt concentration (NaCl) leads to an optimum curve for Km, oxaloacctate while Km, NADH remains constant. Previous claims that the activity of halophilic malate dehydrogenase shows a maximum at 1.25 M NaCl are caused by limiting substrate concentration; at substrate saturation, specific activity of halophilic malate dehydrogenase reaches a constant value at ionic strengths I greater than or equal to 1 M. Non-halophilic (mitochondrial) malate dehydrogenase shows Km characteristics similar to those observed for the halophilic enzyme. The drastic decrease in specific activity of the mitochondrial enzyme at elevated salt concentrations is caused by the salt-induced increase in rigidity of the enzyme, rather than gross structural changes.

Sweet sorghum bagasse and corn stover serving as substrates for producing sophorolipids

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

Samad, Abdul; Zhang, Ji; Chen, Da

To make the process of producing sophorolipids by Candida bombicola truly sustainable, we investigated production of these biosurfactants on biomass hydrolysates. This study revealed: (1) yield of sophorolipds on bagasse hydrolysate decreased from 0.56 to 0.54 and to 0.37 g/g carbon source when yellow grease was dosed at 10, 40 and 60 g/L, respectively. In the same order, concentration of sophorolipids was 35.9, 41.9, and 39.3 g/L; (2) under similar conditions, sophorolipid yield was 0.12, 0.05 and 0.04 g/g carbon source when corn stover hydrolysate was mixed with soybean oil at 10, 20 and 40 g/L. Sophorolipid concentration was 11.6,more » 4.9, and 3.9 g/L for the three oil doses from low to high; and (3) when corn stover hydrolysate and yellow grease served as the substrates for cultivating the yeast in a fermentor, sophorolipid concentration reached 52.1 g/L. Upon further optimization, sophorolipids production from ligocellulose will be indeed sustainable.« less

Sweet sorghum bagasse and corn stover serving as substrates for producing sophorolipids.

PubMed

Samad, Abdul; Zhang, Ji; Chen, Da; Chen, Xiaowen; Tucker, Melvin; Liang, Yanna

2017-03-01

To make the process of producing sophorolipids by Candida bombicola truly sustainable, we investigated production of these biosurfactants on biomass hydrolysates. This study revealed: (1) yield of sophorolipds on bagasse hydrolysate decreased from 0.56 to 0.54 and to 0.37 g/g carbon source when yellow grease was dosed at 10, 40 and 60 g/L, respectively. In the same order, concentration of sophorolipids was 35.9, 41.9, and 39.3 g/L; (2) under similar conditions, sophorolipid yield was 0.12, 0.05 and 0.04 g/g carbon source when corn stover hydrolysate was mixed with soybean oil at 10, 20 and 40 g/L. Sophorolipid concentration was 11.6, 4.9, and 3.9 g/L for the three oil doses from low to high; and (3) when corn stover hydrolysate and yellow grease served as the substrates for cultivating the yeast in a fermentor, sophorolipid concentration reached 52.1 g/L. Upon further optimization, sophorolipids production from ligocellulose will be indeed sustainable.

The ZnO-FET Biosensor for Cardiac Troponin I

NASA Astrophysics Data System (ADS)

Fathil, M. F. M.; Arshad, M. K. Md; Nuzaihan, M. N. M.; Gopinath, Subash C. B.; Ruslinda, A. R.; Hashim, U.

2018-03-01

This paper investigates the influence of substrate-gate coupling on the ZnO-FET biosensor’s sensitivity for detection of cardiac troponin I (cTnI), a ‘gold standard’ biomarker for acute myocardial infarction (AMI). The FET-based device with introduction of substrate-gate coupling on p-type silicon-on-insulator (SOI) substrate is fabricated using conventional lithography processes. An n-type zinc oxide (ZnO) thin film deposited via electron-beam evaporator is used as transducer for bridging the source and drain regions. Surface modifications via functionalization with 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde (GA) as chemical linkers, followed by immobilization of cTnI monoclonal antibody (MAb-cTnI) as bio-receptor on the ZnO thin film allow different concentration of cTnI detection with high selectivity. The device’s sensitivity increases up to 9 %·(g/ml)-1 with the increase of the substrate-gate voltage (VSG) up to -10 V at very low limit of detection (LOD) down to 1.6 fg/ml.

Batch kinetics of Pseudomonas sp. growth on benzene. Modeling of product and substrate inhibitions.

PubMed

Monero, Alessandra; Lanza, Luca; Zilli, Mario; Sene, Luciane; Converti, Attilio

2003-01-01

Batch tests of benzene degradation were performed in liquid phase at 30 degrees C, pH 6.8 +/- 0.2, and 200 rpm in two 3-L stirred tank bioreactors, using the benzene-degrading bacterium Pseudomonas sp. NCIMB 9688. A relatively high starting biomass level (220-270 mg(X)/L) and starting benzene concentration ranging from 20 to 200 mg(S)/L were selected as conditions to investigate possible inhibition phenomena. Volumetric as well as specific rates of biomass formation and substrate consumption were calculated from experimental data of both growth and benzene degradation and used to propose and check a new overall kinetic model for cell growth simultaneously accounting for both product and substrate inhibitions. The results of the present study evidenced the occurrence of a competitive-type product inhibition due to 2-hydroxymuconic semialdehyde (K(iP)' = 0.902 mg(S)/L), which was stronger than the uncompetitive-type inhibition exerted by substrate (K(iS) = 7.69 mg(S)/L).

Hydroxylation of 1,8-cineole by Mucor ramannianus and Aspergillus niger.

PubMed

Ramos, Aline de Souza; Ribeiro, Joyce Benzaquem; Teixeira, Bruna Gomes; Ferreira, José Luiz Pinto; Silva, Jefferson Rocha de A; Ferreira, Alexandre do Amaral; de Souza, Rodrigo Octavio Mendonça Alves; Amaral, Ana Claudia F

2015-03-01

The monoterpenoid 1,8-cineole is obtained from the leaves of Eucalyptus globulus and it has important biological activities. It is a cheap natural substrate because it is a by-product of the Eucalyptus cultivation for wood and pulp production. In this study, it was evaluated the potential of three filamentous fungi in the biotransformation of 1,8-cineole. The study was divided in two steps: first, reactions were carried out with 1,8-cineole at 1 g/L for 24 h; afterwards, reactions were carried out with substrate at 5 g/L for 5 days. The substrate was hydroxylated into 2-exo-hydroxy-1,8-cineole and 3-exo-hydroxy-1,8-cineole by fungi Mucor ramannianus and Aspergillus niger with high stereoselectivity. Trichoderma harzianum was also tested but no transformation was detected. M. ramannianus led to higher than 99% of conversion within 24 h with a starting high substrate concentration (1 g/L). When substrate was added at 5 g/L, only M. ramannianus was able to catalyze the reaction, but the conversion level was 21.7% after 5 days. Both products have defined stereochemistry and could be used as chiral synthons. Furthermore, biological activity has been described for 3-exo-hydroxy-1,8-cineol. To the best of our knowledge, this is the first report on the use of M. ramannianus in this reaction.

Self-assembly of silver nanoparticles as high active surface-enhanced Raman scattering substrate for rapid and trace analysis of uranyl(VI) ions

NASA Astrophysics Data System (ADS)

Wang, Shaofei; Jiang, Jiaolai; Wu, Haoxi; Jia, Jianping; Shao, Lang; Tang, Hao; Ren, Yiming; Chu, Mingfu; Wang, Xiaolin

2017-06-01

A facile surface-enhanced Raman scattering (SERS) substrate based on the self-assembly of silver nanoparticles on the modified silicon wafer was obtained, and for the first time, an advanced SERS analysis method basing on this as-prepared substrate was established for high sensitive and rapid detection of uranyl ions. Due to the weakened bond strength of Odbnd Udbnd O resulting from two kinds of adsorption of uranyl species (;strong; and ;weak; adsorption) on the substrate, the ν1 symmetric stretch vibration frequency of Odbnd Udbnd O shifted from 871 cm- 1 (normal Raman) to 720 cm- 1 and 826 cm- 1 (SERS) along with significant Raman enhancement. Effects of the hydrolysis of uranyl ions on SERS were also investigated, and the SERS band at 826 cm- 1 was first used to approximately define the constitution of uranyl species at trace quantity level. Besides, the SERS intensity was proportional to the variable concentrations of uranyl nitrate ranging from 10- 7 to 10- 3 mol L- 1 with an excellent linear relation (R2 = 0.998), and the detection limit was 10- 7 mol L- 1. Furthermore, the related SERS approach involves low-cost substrate fabrication, rapid and trace analysis simultaneously, and shows great potential applications for the field assays of uranyl ions in the nuclear fuel cycle and environmental monitoring.

Effect of substrate on the atomic structure and physical properties of thermoelectric Ca3Co4O9 thin films

NASA Astrophysics Data System (ADS)

Qiao, Q.; Gulec, A.; Paulauskas, T.; Kolesnik, S.; Dabrowski, B.; Ozdemir, M.; Boyraz, C.; Mazumdar, D.; Gupta, A.; Klie, R. F.

2011-08-01

The incommensurately layered cobalt oxide Ca3Co4O9 exhibits an unusually high Seebeck coefficient as a polycrystalline bulk material, making it ideally suited for many high temperature thermoelectric applications. In this paper, we investigate properties of Ca3Co4O9 thin films grown on cubic perovskite SrTiO3, LaAlO3, and (La0.3Sr0.7)(Al0.65Ta0.35)O3 substrates and on hexagonal Al2O3 (sapphire) substrates using the pulsed laser deposition technique. X-ray diffraction and transmission electron microscopy analysis indicate strain-free growth of films, irrespective of the substrate. However, depending on the lattice and symmetry mismatch, defect-free growth of the hexagonal CoO2 layer is stabilized only after a critical thickness and, in general, we observe the formation of a stable Ca2CoO3 buffer layer near the substrate-film interface. Beyond this critical thickness, a large concentration of CoO2 stacking faults is observed, possibly due to weak interlayer interaction in this layered material. We propose that these stacking faults have a significant impact on the Seebeck coefficient and we report higher values in thinner Ca3Co4O9 films due to additional phonon scattering sites, necessary for improved thermoelectric properties.

Effect of substrate on the atomic structure and physical properties of thermoelectric Ca₃Co₄O₉ thin films.

PubMed

Qiao, Q; Gulec, A; Paulauskas, T; Kolesnik, S; Dabrowski, B; Ozdemir, M; Boyraz, C; Mazumdar, D; Gupta, A; Klie, R F

2011-08-03

The incommensurately layered cobalt oxide Ca(3)Co(4)O(9) exhibits an unusually high Seebeck coefficient as a polycrystalline bulk material, making it ideally suited for many high temperature thermoelectric applications. In this paper, we investigate properties of Ca(3)Co(4)O(9) thin films grown on cubic perovskite SrTiO(3), LaAlO(3), and (La(0.3)Sr(0.7))(Al(0.65)Ta(0.35))O(3) substrates and on hexagonal Al(2)O(3) (sapphire) substrates using the pulsed laser deposition technique. X-ray diffraction and transmission electron microscopy analysis indicate strain-free growth of films, irrespective of the substrate. However, depending on the lattice and symmetry mismatch, defect-free growth of the hexagonal CoO(2) layer is stabilized only after a critical thickness and, in general, we observe the formation of a stable Ca(2)CoO(3) buffer layer near the substrate-film interface. Beyond this critical thickness, a large concentration of CoO(2) stacking faults is observed, possibly due to weak interlayer interaction in this layered material. We propose that these stacking faults have a significant impact on the Seebeck coefficient and we report higher values in thinner Ca(3)Co(4)O(9) films due to additional phonon scattering sites, necessary for improved thermoelectric properties.

[Research on the preparative method of Arctigenin].

PubMed

Zhang, Li-Ying; Yang, Yi-Shun; Zhang, Tong; Ding, Yue; Cai, Zhen-Zhen; Tao, Jian-Sheng

2012-03-01

To research on the preparation of Arctigenin in vitro. Took enzyme concentration, time course and substrate concentration as investigation factors, used Box-Behnken design-response surface methodology to optimize the enzyme hydrolysis path of Arctigenin. The best operational path for Arctigenin was as follows: the temperature was 50 degrees C, pH was 4.8, enzyme concentration was 0.44 U/mL, time course was 46.81 min, substrate concentration was 0.29 mg/mL, the conversion rate was 90.94%. This research can be regarded as a referencein preparing Arctigenin in vitro.

Micromotors Powered by Enzyme Catalysis.

PubMed

Dey, Krishna K; Zhao, Xi; Tansi, Benjamin M; Méndez-Ortiz, Wilfredo J; Córdova-Figueroa, Ubaldo M; Golestanian, Ramin; Sen, Ayusman

2015-12-09

Active biocompatible systems are of great current interest for their possible applications in drug or antidote delivery at specific locations. Herein, we report the synthesis and study of self-propelled microparticles powered by enzymatic reactions and their directed movement in substrate concentration gradient. Polystyrene microparticles were functionalized with the enzymes urease and catalase using a biotin-streptavidin linkage procedure. The motion of the enzyme-coated particles was studied in the presence of the respective substrates, using optical microscopy and dynamic light scattering analysis. The diffusion of the particles was found to increase in a substrate concentration dependent manner. The directed chemotactic movement of these enzyme-powered motors up the substrate gradient was studied using three-inlet microfluidic channel architecture.

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.

Characteristics of Au Migration and Concentration Distributions in Au-Doped HgCdTe LPE Materials

NASA Astrophysics Data System (ADS)

Sun, Quanzhi; Yang, Jianrong; Wei, Yanfeng; Zhang, Juan; Sun, Ruiyun

2015-08-01

Annealing techniques and secondary ion mass spectrometry have been used to study the characteristics of Au migration and concentration distributions in HgCdTe materials grown by liquid phase epitaxy. Secondary ion mass spectrometry measurements showed that Au concentrations had obvious positive correlations with Hg-vacancy concentration and dislocation density of the materials. Au atoms migrate toward regions of high Hg-vacancy concentration or move away from these regions when the Hg-vacancy concentration decreases during annealing. The phenomenon can be explained by defect chemical equilibrium theory if Au atoms have a very large migration velocity compared with Hg vacancies. Au atoms will also migrate toward regions of high dislocation density, leading to a peak concentration in the inter-diffusion region of HgCdTe materials near the substrate. By use of an Hg and Te-rich annealing technique, different concentration distributions of both Au atoms and Hg vacancies in HgCdTe materials were obtained, indicating that Au-doped HgCdTe materials can be designed and prepared to satisfy the requirements of HgCdTe devices.

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.

Progress toward a 30 percent-efficient, monolithic, three-junction, two-terminal concentrator solar cell for space applications

NASA Technical Reports Server (NTRS)

Partain, L. D.; Chung, B.-C.; Virshup, G. F.; Schultz, J. C.; Macmillan, H. F.; Ristow, M. Ladle; Kuryla, M. S.; Bertness, K. A.

1991-01-01

Component efficiencies of 0.2/sq cm cells at approximately 100x AMO light concentration and 80 C temperatures are not at 15.3 percent for a 1.9 eV AlGaAs top cell, 9.9 percent for a 1.4 eV GaAs middle cell under a 1.9 eV AlGaAs filter, and 2.4 percent for a bottom 1.0 eV InGaAs cell under a GaAs substrate. The goal is to continue improvement in these performance levels and to sequentially grow these devices on a single substrate to give 30 percent efficient, monolithic, two-terminal, three-junction space concentrator cells. The broad objective is a 30 percent efficient monolithic two-terminal cell that can operate under 25 to 100x AMO light concentrations and at 75 to 100 C cell temperatures. Detailed modeling predicts that this requires three junctions. Two options are being pursued, and both use a 1.9 eV AlGaAs top junction and a 1.4 eV GaAs middle junction grown by a 1 atm OMVPE on a lattice matched substrate. Option 1 uses a low-doped GaAs substrate with a lattice mismatched 1.0 eV InGaAs cell formed on the back of the substrate. Option 2 uses a Ge substrate to which the AlGaAs and GaAs top junctions are lattice matched, with a bottom 0.7 eV Ge junction formed near the substrate interface with the GaAs growth. The projected efficiency contributions are near 16, 11, and 3 percent, respectively, from the top, middle, and bottom junctions.

The influence of boron doping level on quality and stability of diamond film on Ti substrate

NASA Astrophysics Data System (ADS)

Wei, J. J.; Li, Ch. M.; Gao, X. H.; Hei, L. F.; Lvun, F. X.

2012-07-01

In this study, we investigate the influence of boron doping level on film quality and stability of boron doped diamond (BDD) film deposited on titanium substrate (Ti/BDD) using microwave plasma chemical vapor deposition system. The results demonstrate that high boron concentration will improve the film conductivity, whereas the diamond film quality and adhesion are deteriorated obviously. The increase of total internal stress in the film and the variation of components within the interlayer will weaken the coating adhesion. According to the analysis of electrode inactivation mechanism, high boron doping level will be harmful to the electrode stability in the view of diamond quality and adhesion deterioration. In this study, 5000 ppm B/C ratio in the reaction gas is optimized for Ti/BDD electrode preparation.

Role of UDP-glucuronosyltransferase isoforms in 13-cis retinoic acid metabolism in humans.

PubMed

Rowbotham, Sophie E; Illingworth, Nicola A; Daly, Ann K; Veal, Gareth J; Boddy, Alan V

2010-07-01

13-cis Retinoic acid (13cisRA, isotretinoin) is an important drug in both dermatology, and the treatment of high-risk neuroblastoma. 13cisRA is known to undergo cytochrome P450-mediated oxidation, mainly by CYP2C8, but phase II metabolic pathways have not been characterized. In the present study, the glucuronidation activities of human liver (HLM) and intestinal microsomes (HIM), as well as a panel of human UDP-glucuronosyltransferases (UGTs) toward both 13cisRA and the 4-oxo metabolite, 4-oxo 13cisRA, were compared using high-performance liquid chromatography. Both HLM and, to a greater extent, HIM catalyzed the glucuronidation of 13cisRA and 4-oxo 13cisRA. Based on the structures of 13cisRA and 4-oxo 13cisRA, the glucuronides formed are conjugated at the terminal carboxylic acid. Further analysis revealed that UGT1A1, UGT1A3, UGT1A7, UGT1A8, and UGT1A9 were the major isoforms responsible for the glucuronidation of both substrates. For 13cisRA, a pronounced substrate inhibition was observed with individual UGTs and with HIM. UGT1A3 exhibited the highest rate of activity toward both substrates, and a high rate of activity toward 13cisRA glucuronidation was also observed with UGT1A7. However, for both substrates, K(m) values were above concentrations reported in clinical studies. Therefore, UGT1A9 is likely to be the most important enzyme in the glucuronidation of both substrates as this enzyme had the lowest K(m) and is expressed in both the intestine and at high levels in the liver.

Human Salivary Aldehyde Dehydrogenase: Purification, Kinetic Characterization and Effect of Ethanol, Hydrogen Peroxide and Sodium Dodecyl Sulfate on the Activity of the Enzyme.

PubMed

Alam, Md Fazle; Laskar, Amaj Ahmed; Choudhary, Hadi Hasan; Younus, Hina

2016-09-01

Human salivary aldehyde dehydrogenase (hsALDH) enzyme appears to be the first line of defense in the body against exogenous toxic aldehydes. However till date much work has not been done on this important member of the ALDH family. In this study, we have purified hsALDH to homogeneity by diethylaminoethyl-cellulose (DEAE-cellulose) ion-exchange chromatography in a single step. The molecular mass of the homodimeric enzyme was determined to be approximately 108 kDa. Four aromatic substrates; benzaldehyde, cinnamaldehyde, 2-naphthaldehyde and 6-methoxy-2-naphthaldehyde were used for determining the activity of pure hsALDH. K m values for these substrates were calculated to be 147.7, 5.31, 0.71 and 3.31 μM, respectively. The best substrates were found to be cinnamaldehyde and 2-naphthaldehyde since they exhibited high V max /K m values. 6-methoxy-2-naphthaldehyde substrate was used for further kinetic characterization of pure hsALDH. The pH and temperature optima of hsALDH were measured to be pH 8 and 45 °C, respectively. The pure enzyme is highly unstable at high temperatures. Ethanol, hydrogen peroxide and SDS activate hsALDH, therefore it is safe and beneficial to include them in mouthwashes and toothpastes in low concentrations.

Some characteristics of fructose 1,6-diphosphatase activity in rat liver

NASA Technical Reports Server (NTRS)

Ashman, P. U.; Lampkin, S. L.; Dillon, L.; Parks, R.

1974-01-01

A reliable assay for hepatic fructose 1,6-diphosphatase in the rat was developed. It was found that the greatest enzymic activity and highest protein levels were eluted from the colored portion of the homogenate. When the substrate concentration was 0.01M, the enzyme had optimal activity when incubated with 0.01M MgSO4 for 10 min. at 37 C in 0.05M Tris-HC1 buffer, pH 7.5. Specificity for the substrate, fructose 1,6-diphosphate, was obtained at substrate concentration of 0.01M.

Process for manufacture of inertial confinement fusion targets and resulting product

DOEpatents

Masnari, Nino A.; Rensel, Walter B.; Robinson, Merrill G.; Solomon, David E.; Wise, Kensall D.; Wuttke, Gilbert H.

1982-01-01

An ICF target comprising a spherical pellet of fusion fuel surrounded by a concentric shell; and a process for manufacturing the same which includes the steps of forming hemispheric shells of a silicon or other substrate material, adhering the shell segments to each other with a fuel pellet contained concentrically therein, then separating the individual targets from the parent substrate. Formation of hemispheric cavities by deposition or coating of a mold substrate is also described. Coatings or membranes may also be applied to the interior of the hemispheric segments prior to joining.

The Physical Electronics of Graphene on Germanium

NASA Astrophysics Data System (ADS)

Rojas Delgado, Richard

The properties of graphene make it an outstanding candidate for electronic-device applications, especially those that require no band gap but a high conductance. The conductance, involving both carrier mobility and carrier concentration, will depend critically on the substrate to which graphene is transferred. I demonstrate an exceptionally high conductance in graphene transferred to Ge(001) and provide an understanding of the mechanism. Essential in this understanding is an interfacial chemistry consisting of Ge oxide and suboxide layers that provide the necessary charges to dope the graphene sheet, and whose chemical behavior is such that one can obtain long-term stability in the conductance. In contrast, when high-quality graphene is grown directly on Ge (100), (111), or (110), the conductance is unexceptional, but oxidation of the surface is significantly delayed and slowed, relative to both clean Ge and Ge with graphene transferred to its surface. [2,3] I fabricate Hall bars in graphene transferred to Ge(001) and graphene grown on Ge(001) using atmospheric-pressure chemical vapor deposition (CVD) with methane precursors, and measure the sheet resistance and Hall effect from 300K to 10K. Values of mobility and carrier concentration are extracted. I obtain the highest combination of mobility and carrier concentration yet reported in graphene (suspended or supported) for temperatures from 10 to 300K. The implication is that the primary mechanisms for scattering charge in the graphene, roughness and a non-uniform electrostatic potential due to fixed charges, have limited effect when the substrate is oxidized Ge.

Structural characterization of ZnO thin films grown on various substrates by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Novotný, M.; Čížek, J.; Kužel, R.; Bulíř, J.; Lančok, J.; Connolly, J.; McCarthy, E.; Krishnamurthy, S.; Mosnier, J.-P.; Anwand, W.; Brauer, G.

2012-06-01

ZnO thin films were grown by pulsed laser deposition on three different substrates: sapphire (0 0 0 1), MgO (1 0 0) and fused silica (FS). The structure and morphology of the films were characterized by x-ray diffraction and scanning electron microscopy and defect studies were carried out using slow positron implantation spectroscopy (SPIS). Films deposited on all substrates studied in this work exhibit the wurtzite ZnO structure and are characterized by an average crystallite size of 20-100 nm. However, strong differences in the microstructure of films deposited on various substrates were found. The ZnO films deposited on MgO and sapphire single-crystalline substrates exhibit local epitaxy, i.e. a well-defined relation between film crystallites and the substrate. Domains with different orientation relationships with the substrate were found in both films. On the other hand, the film deposited on the FS substrate exhibits fibre texture with random lateral orientation of crystallites. Extremely high compressive in-plane stress of σ ˜ 14 GPa was determined in the film deposited on the MgO substrate, while the film deposited on sapphire is virtually stress-free, and the film deposited on the FS substrate exhibits a tensile in-plane stress of σ ˜ 0.9 GPa. SPIS investigations revealed that the concentration of open-volume defects in the ZnO films is substantially higher than that in a bulk ZnO single crystal. Moreover, the ZnO films deposited on MgO and sapphire single-crystalline substrates exhibit a significantly higher density of defects than the film deposited on the amorphous FS substrate.

High sensitivity fluorescent single particle and single molecule detection apparatus and method

DOEpatents

Mathies, Richard A.; Peck, Konan; Stryer, Lubert

1990-01-01

Apparatus is described for ultrasensitive detection of single fluorescent particles down to the single fluorescent molecule limit in a fluid or on a substrate comprising means for illuminating a predetermined volume of the fluid or area of the substrate whereby to emit light including background light from the fluid and burst of photons from particles residing in the area. The photon burst is detected in real time to generate output representative signal. The signal is received and the burst of energy from the fluorescent particles is distinguished from the background energy to provide an indication of the number, location or concentration of the particles or molecules.

A naturally occurring diatom frustule as a SERS substrate for the detection and quantification of chemicals

NASA Astrophysics Data System (ADS)

Chamuah, Nabadweep; Chetia, Lakhi; Zahan, Nashrat; Dutta, Sibasish; Ahmed, Gazi A.; Nath, Pabitra

2017-05-01

Naturally occurring photonic crystal structures play an important role in different fields of application. Herein, we exploit the periodic pore pattern of a diatom frustule and demonstrate surface-enhanced Raman scattering (SERS) using its structure as a template for the SERS substrate. Gold nanoparticles (AuNPs) were initially allowed to self-assemble on the surface and inside the pores of the diatoms. The enhancement in the localized surface plasmon resonance (LSPR) field magnitude for the assembled AuNPs on the diatom frustule were studied using simulation software. For the proposed SERS substrate, an average field enhancement of the order of 108 magnitude was observed. We demonstrate the operation of the designed substrate for the detection and quantification of Raman signals from two Raman active samples, namely malachite green (MG) and fluoride concentrations in drinking water. Using the proposed SERS substrate, an MG concentration as low as 1 nM with a relative standard deviation (RSD) of 7.57% and a fluoride concentration of 100 nM with an RSD of 17.26% could be measured with the Raman spectrometer. We envision that the proposed technique could emerge as an inexpensive alternative fabrication method of SERS substrates which can produce an enhanced LSPR field magnitude and scatter intense Raman signals from Raman active samples.

A detailed analysis of the energy levels configuration existing in the band gap of supersaturated silicon with titanium for photovoltaic applications

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

Pérez, E.; Dueñas, S.; Castán, H.

2015-12-28

The energy levels created in supersaturated n-type silicon substrates with titanium implantation in the attempt to create an intermediate band in their band-gap are studied in detail. Two titanium ion implantation doses (10{sup 13 }cm{sup -2} and 10{sup 14 }cm{sup -2}) are studied in this work by conductance transient technique and admittance spectroscopy. Conductance transients have been measured at temperatures of around 100 K. The particular shape of these transients is due to the formation of energy barriers in the conduction band, as a consequence of the band-gap narrowing induced by the high titanium concentration. Moreover, stationary admittance spectroscopy results suggest the existencemore » of different energy level configuration, depending on the local titanium concentration. A continuum energy level band is formed when titanium concentration is over the Mott limit. On the other hand, when titanium concentration is lower than the Mott limit, but much higher than the donor impurity density, a quasi-continuum energy level distribution appears. Finally, a single deep center appears for low titanium concentration. At the n-type substrate, the experimental results obtained by means of thermal admittance spectroscopy at high reverse bias reveal the presence of single levels located at around E{sub c}-425 and E{sub c}-275 meV for implantation doses of 10{sup 13 }cm{sup −2} and 10{sup 14 }cm{sup −2}, respectively. At low reverse bias voltage, quasi-continuously distributed energy levels between the minimum of the conduction bands, E{sub c} and E{sub c}-450 meV, are obtained for both doses. Conductance transients detected at low temperatures reveal that the high impurity concentration induces a band gap narrowing which leads to the formation of a barrier in the conduction band. Besides, the relationship between the activation energy and the capture cross section values of all the energy levels fits very well to the Meyer-Neldel rule. As it is known, the Meyer-Neldel rule typically appears in processes involving multiple excitations, like carrier capture and emission in deep levels, and it is generally observed in disordered systems. The obtained Meyer-Neldel energy value, 15.19 meV, is very close to the value obtained in multicrystalline silicon samples contaminated with iron (13.65 meV), meaning that this energy value could be associated to the phonons energy in this kind of substrates.« less

High-voltage lateral double-implanted MOSFETs implemented on high-purity semi-insulating 4H-SiC substrates with gate field plates

NASA Astrophysics Data System (ADS)

Seok, Ogyun; Kim, Hyoung Woo; Moon, Jeong Hyun; Lee, Hyun-Su; Bahng, Wook

2018-06-01

Lateral double-implanted MOSFETs (LDIMOSFETs) fabricated on on-axis high-purity semi-insulating (HPSI) 4H-SiC substrates with gate field plates have been demonstrated for the enhancement of reverse blocking capability. The effects of gate field plate on LDIMOSFET were analyzed by simulation and experimental methods. The electric field concentration at the gate edge was successfully suppressed by a gate field plate. A high breakdown voltage of 934 V and a figure of merit of 14.6 MW/cm2 were achieved at L FP of 2 µm and L drift of 15 µm, while those of the conventional device without a gate field plate were 744 V and 13.3 MW/cm2, respectively. Also, the fabricated device shows stable blocking characteristics at a high temperature of 250 °C. The drain leakage was increased by only 22% at 250 °C compared with that at room temperature.

MINERALIZATION OF MTBE WITH VARIOUS PRIMARY SUBSTRATES

EPA Science Inventory

Five specialized bioreactors have been operated for over a year to evaluate the biodegradability of the fuel oxygenate methyl-t-butyl -t-butyl ether (MTBE) under difference substrate/co-substrate conditions. One bioreactor has been fed MTBE at an influent concentration of 150 ...

Structural and physical properties of InAlAs quantum dots grown on GaAs

NASA Astrophysics Data System (ADS)

Vasile, B. S.; Daly, A. Ben; Craciun, D.; Alexandrou, I.; Lazar, S.; Lemaître, A.; Maaref, M. A.; Iacomi, F.; Craciun, V.

2018-04-01

Quantum dots (QDs), which have particular physical properties due to the three dimensions confinement effect, could be used in many advanced optoelectronic applications. We investigated the properties of InAlAs/AlGaAs QDs grown by molecular beam epitaxy on GaAs/Al0.5Ga0.5As layers. The optical properties of QDs were studied by low-temperature photoluminescence (PL). Two bandgap transitions corresponding to the X-Sh and X-Ph energy structure were observed. The QDs structure was investigated using high-resolution X-ray diffraction (HRXRD) and high-resolution transmission electron microscopy (HRTEM). HRXRD investigations showed that the layers grew epitaxially on the substrate, with no relaxation. HRTEM investigations confirmed the epitaxial nature of the grown structures. In addition, it was revealed that the In atoms aggregated in some prismatic regions, forming areas of high In concentration, that were still in perfect registry with the substrate.

Highly efficient aerobic oxidation of alcohols by using less-hindered nitroxyl-radical/copper catalysis: optimum catalyst combinations and their substrate scope.

PubMed

Sasano, Yusuke; Kogure, Naoki; Nishiyama, Tomohiro; Nagasawa, Shota; Iwabuchi, Yoshiharu

2015-04-01

The oxidation of alcohols into their corresponding carbonyl compounds is one of the most fundamental transformations in organic chemistry. In our recent report, 2-azaadamantane N-oxyl (AZADO)/copper catalysis promoted the highly chemoselective aerobic oxidation of unprotected amino alcohols into amino carbonyl compounds. Herein, we investigated the extension of the promising AZADO/copper-catalyzed aerobic oxidation of alcohols to other types of alcohol. During close optimization of the reaction conditions by using various alcohols, we found that the optimum combination of nitroxyl radical, copper salt, and solution concentration was dependent on the type of substrate. Various alcohols, including highly hindered and heteroatom-rich ones, were efficiently oxidized into their corresponding carbonyl compounds under mild conditions with lower amounts of the catalysts. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrohydrodynamic printing of silver nanowires for flexible and stretchable electronics.

PubMed

Cui, Zheng; Han, Yiwei; Huang, Qijin; Dong, Jingyan; Zhu, Yong

2018-04-19

A silver nanowire (AgNW) based conductor is a promising component for flexible and stretchable electronics. A wide range of flexible/stretchable devices using AgNW conductors has been demonstrated recently. High-resolution, high-throughput printing of AgNWs remains a critical challenge. Electrohydrodynamic (EHD) printing has been developed as a promising technique to print different materials on a variety of substrates with high resolution. Here, AgNW ink was developed for EHD printing. The printed features can be controlled by several parameters including AgNW concentration, ink viscosity, printing speed, stand-off distance, etc. With this method, AgNW patterns can be printed on a range of substrates, e.g. paper, polyethylene terephthalate (PET), glass, polydimethylsiloxane (PDMS), etc. First, AgNW samples on PDMS were characterized under bending and stretching. Then AgNW heaters and electrocardiogram (ECG) electrodes were fabricated to demonstrate the potential of this printing technique for AgNW-based flexible and stretchable devices.

Influence of yield on in vitro accumulation of aflatoxins in pecan (Carya illinoensis (Wang.) K. Koch) nutmeats.

PubMed

McMeans, J L

1983-02-01

Pecans were harvested from trees (Carya illinoensis (Wang.) K. Koch) in November of 1977 through 1979. Kernel meals from high-, medium-, and low-yielding trees were inoculated with a spore suspension of Aspergillus parasiticus and incubated for 7 days at 25 degrees C. Significant differences in aflatoxin accumulation were found among the three substrates, with a direct correlation between high aflatoxin concentration and tree yield.

Method of fabricating optical waveguides by ion implantation doping

DOEpatents

Appleton, B.R.; Ashley, P.R.; Buchal, C.J.

1987-03-24

A method for fabricating high-quality optical waveguides in optical quality oxide crystals by ion implantation doping and controlled epitaxial recrystallization is provided. Masked LiNbO/sub 3/ crystals are implanted with high concentrations of Ti dopant at ion energies of about 360 keV while maintaining the crystal near liquid nitrogen temperature. Ion implantation doping produces an amorphous, Ti-rich nonequilibrium phase in the implanted region. Subsequent thermal annealing in a water-saturated oxygen atmosphere at up to 1000/degree/C produces solid-phase epitaxial regrowth onto the crystalline substrate. A high-quality crystalline layer results which incorporates the Ti into the crystal structure at much higher concentrations than is possible by standard diffusion techniques, and this implanted region has excellent optical waveguiding properties.

Scalable Top-Down Approach Tailored by Interferometric Lithography to Achieve Large-Area Single-Mode GaN Nanowire Laser Arrays on Sapphire Substrate.

PubMed

Behzadirad, Mahmoud; Nami, Mohsen; Wostbrock, Neal; Zamani Kouhpanji, Mohammad Reza; Feezell, Daniel F; Brueck, Steven R J; Busani, Tito

2018-03-27

GaN nanowires are promising for optical and optoelectronic applications because of their waveguiding properties and large optical band gap. However, developing a precise, scalable, and cost-effective fabrication method with a high degree of controllability to obtain high-aspect-ratio nanowires with high optical properties and minimum crystal defects remains a challenge. Here, we present a scalable two-step top-down approach using interferometric lithography, for which parameters can be controlled precisely to achieve highly ordered arrays of nanowires with excellent quality and desired aspect ratios. The wet-etch mechanism is investigated, and the etch rates of m-planes {11̅00} (sidewalls) were measured to be 2.5 to 70 nm/h depending on the Si doping concentration. Using this method, uniform nanowire arrays were achieved over a large area (>10 5 μm 2 ) with an spect ratio as large as 50, a radius as small as 17 nm, and atomic-scale sidewall roughness (<1 nm). FDTD modeling demonstrated HE 11 is the dominant transverse mode in the nanowires with a radius of sub-100 nm, and single-mode lasing from vertical cavity nanowire arrays with different doping concentrations on a sapphire substrate was interestingly observed in photoluminescence measurements. High Q-factors of ∼1139-2443 were obtained in nanowire array lasers with a radius and length of 65 nm and 2 μm, respectively, corresponding to a line width of 0.32-0.15 nm (minimum threshold of 3.31 MW/cm 2 ). Our results show that fabrication of high-quality GaN nanowire arrays with adaptable aspect ratio and large-area uniformity is feasible through a top-down approach using interferometric lithography and is promising for fabrication of III-nitride-based nanophotonic devices (radial/axial) on the original substrate.