Static electric field enhancement in nanoscale structures

Energy Technology Data Exchange (ETDEWEB)

Lepetit, Bruno, E-mail: bruno.lepetit@irsamc.ups-tlse.fr; Lemoine, Didier, E-mail: didier.lemoine@irsamc.ups-tlse.fr [Université de Toulouse, UPS, Laboratoire Collisions Agrégats Réactivité, IRSAMC, F-31062 Toulouse (France); CNRS, UMR 5589, F-31062 Toulouse (France); Márquez-Mijares, Maykel, E-mail: mmarquez@instec.cu [Université de Toulouse, UPS, Laboratoire Collisions Agrégats Réactivité, IRSAMC, F-31062 Toulouse (France); CNRS, UMR 5589, F-31062 Toulouse (France); Instituto Superior de Tecnologías y Ciencias Aplicadas, Avenida Salvador Allende 1110, Quinta de los Molinos, La Habana (Cuba)

2016-08-28

We study the effect of local atomic- and nano-scale protrusions on field emission and, in particular, on the local field enhancement which plays a key role as known from the Fowler-Nordheim model of electronic emission. We study atomic size defects which consist of right angle steps forming an infinite length staircase on a tungsten surface. This structure is embedded in a 1 GV/m ambient electrostatic field. We perform calculations based upon density functional theory in order to characterize the total and induced electronic densities as well as the local electrostatic fields taking into account the detailed atomic structure of the metal. We show how the results must be processed to become comparable with those of a simple homogeneous tungsten sheet electrostatic model. We also describe an innovative procedure to extrapolate our results to nanoscale defects of larger sizes, which relies on the microscopic findings to guide, tune, and improve the homogeneous metal model, thus gaining predictive power. Furthermore, we evidence analytical power laws for the field enhancement characterization. The main physics-wise outcome of this analysis is that limited field enhancement is to be expected from atomic- and nano-scale defects.

Protein separations using enhanced-fluidity liquid chromatography.

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Bennett, Raffeal; Olesik, Susan V

2017-11-10

Enhanced-fluidity liquid chromatography (EFLC) methods using methanol/H 2 O/CO 2 and hydrophilic interaction liquid chromatography (HILIC) were explored for the separation of proteins and peptides. EFLC is a separation mode that uses a mobile phase made of conventional solvents combined with liquid carbon dioxide (CO 2 ) in subcritical conditions. The addition of liquid CO 2 enhances diffusivity and decreases viscosity while maintaining mixture polarity, which typically results in reduced time of analysis. TFA additive and elevated temperature were leveraged as key factors in the separation of a 13-analyte intact protein mixture in under 5min. Under these conditions EFLC showed modest improvement in terms of peak asymmetry and analysis time over the competing ACN/H 2 O separation. Protein analytes detected by electrospray ionization - quadrupole time of flight, were shown to be unaffected by the addition of CO 2 in the mobile phase. Herein, the feasibility of separating hydrophilic proteins up to 80kDa (with transferrin) is demonstrated for CO 2 -containing mobile phases. Copyright © 2017 Elsevier B.V. All rights reserved.

Kirkwood-Buff Approach Rescues Overcollapse of a Disordered Protein in Canonical Protein Force Fields.

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Mercadante, Davide; Milles, Sigrid; Fuertes, Gustavo; Svergun, Dmitri I; Lemke, Edward A; Gräter, Frauke

2015-06-25

Understanding the function of intrinsically disordered proteins is intimately related to our capacity to correctly sample their conformational dynamics. So far, a gap between experimentally and computationally derived ensembles exists, as simulations show overcompacted conformers. Increasing evidence suggests that the solvent plays a crucial role in shaping the ensembles of intrinsically disordered proteins and has led to several attempts to modify water parameters and thereby favor protein-water over protein-protein interactions. This study tackles the problem from a different perspective, which is the use of the Kirkwood-Buff theory of solutions to reproduce the correct conformational ensemble of intrinsically disordered proteins (IDPs). A protein force field recently developed on such a basis was found to be highly effective in reproducing ensembles for a fragment from the FG-rich nucleoporin 153, with dimensions matching experimental values obtained from small-angle X-ray scattering and single molecule FRET experiments. Kirkwood-Buff theory presents a complementary and fundamentally different approach to the recently developed four-site TIP4P-D water model, both of which can rescue the overcollapse observed in IDPs with canonical protein force fields. As such, our study provides a new route for tackling the deficiencies of current protein force fields in describing protein solvation.

Nanoantennas for enhancing and confining the magnetic optical field

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Grosjean, Thierry; Mivelle, Mathieu; Baida, Fadi I.; Burr, Geoffrey W.; Fischer, Ulrich C.

2011-05-01

We propose different optical antenna structures for enhancing and confining the magnetic optical field. A common feature of these structures are concave corners in thin metal films as locations of the enhanced magnetic field. This proposal is inspired by Babinet's principle as the concave edges are the complementary structures to convex metal corners, which are known to be locations of a strongly enhanced electric field. Bowtie antennas and the bowtie apertures of appropriate size were shown to exhibit resonances in the infrared frequency range with an especially strong enhancement of the electrical field in the gap between 2 convex metal corners. We show by numerical calculations, that the complementary structures, the complementary bowtie aperture - the diabolo antenna - and the complementary bow tie antenna - two closely spaced triangular apertures in a metal film with a narrow gap between two opposing concave corners - exhibit resonances with a strongly enhanced magnetic field at the narrow metal constriction between the concave corners. We suggest sub-wavelength circuits of concave and convex corners as building blocks of planar metamaterials.

Enzyme Enhanced Protein Recovery from Green Biomass Pulp

DEFF Research Database (Denmark)

Dotsenko, Gleb; Lange, Lene

2017-01-01

of local protein resources based on upgrade from e.g. green plant biomass. In present work we consider different strategies for protein recovery from white clover and ryegrass screw press pulps, using aqueous extraction, as well as carbohydrases and proteases enhanced extraction. Protein recovery...... in these studies was determined as a yield of solubilized protein with regard to the total protein in a screw press pulp. Aqueous extraction at pH 8.0 resulted in approx. 40 % protein recovery, while proteases application (Savinase 16.0L, Novozymes) enabled twice higher protein yield. Application of plant cell...... pulp proteolyzates, generated by Savinase 16.0L protease....

Quantization of bovine serum albumin by fluorescence enhancement effects and corresponding binding of macrocyclic host-protein assembly.

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Bardhan, Munmun; Misra, Tapas; Ganguly, Tapan

2012-01-05

The present paper reports the investigations on the spectroscopic behavior of the binary complexes of the dye aurintricarboxylic acid (ATA) with protein bovine serum albumin (BSA) and 18-crown 6 (CW) (ATA·BSA, ATA·CW) and the ternary complex ATA·CW·BSA by using UV-vis steady state and time resolved fluorescence spectroscopy. The primary aim of the work is to determine the protein (BSA) quantization by fluorescence enhancement method and investigate the 'enhancer' activity of crown ether (CW) on it to increase the resolution. Steady state and time resolved fluorescence measurements demonstrated how fluorescence intensity of ATA could be used for the determination of the protein BSA in aqueous solution. The binding of dye (probe/fluorescent medicinal molecule) with protein and the denaturing effect in the polar environment of acetonitrile of the dye protein complex act as drug binding as well as drug release activity. Apart from its basic research point of view, the present study also possesses significant importance and applications in the field of medicinal chemistry. Copyright © 2011 Elsevier B.V. All rights reserved.

Protein solubility and folding enhancement by interaction with RNA.

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Seong Il Choi

Full Text Available While basic mechanisms of several major molecular chaperones are well understood, this machinery has been known to be involved in folding of only limited number of proteins inside the cells. Here, we report a chaperone type of protein folding facilitated by interaction with RNA. When an RNA-binding module is placed at the N-terminus of aggregation-prone target proteins, this module, upon binding with RNA, further promotes the solubility of passenger proteins, potentially leading to enhancement of proper protein folding. Studies on in vitro refolding in the presence of RNA, coexpression of RNA molecules in vivo and the mutants with impaired RNA binding ability suggests that RNA can exert chaperoning effect on their bound proteins. The results suggest that RNA binding could affect the overall kinetic network of protein folding pathway in favor of productive folding over off-pathway aggregation. In addition, the RNA binding-mediated solubility enhancement is extremely robust for increasing soluble yield of passenger proteins and could be usefully implemented for high-throughput protein expression for functional and structural genomic research initiatives. The RNA-mediated chaperone type presented here would give new insights into de novo folding in vivo.

Non-resonant terahertz field enhancement in periodically arranged nanoslits

DEFF Research Database (Denmark)

Novitsky, Andrey; Ivinskaya, Aliaksandra; Zalkovskij, Maksim

2012-01-01

We analyze ultra strong non-resonant field enhancement of THz field in periodic arrays of nanoslits cut in ultrathin metal films. The main feature of our approach is that the slit size and metal film thickness are several orders of magnitude smaller than the wavelength λ of the impinging radiatio...... by the microscopic Drude-Lorentz model taking into account retardation processes in the metal film and validated by the finite difference frequency domain method. We expect sensor and modulation applications of the predicted giant broadband field enhancement.......We analyze ultra strong non-resonant field enhancement of THz field in periodic arrays of nanoslits cut in ultrathin metal films. The main feature of our approach is that the slit size and metal film thickness are several orders of magnitude smaller than the wavelength λ of the impinging radiation...... approaches the THz wavelength but before entering the Raleigh-Wood anomaly, the field enhancement in nanoslit stays close to that in a single isolated slit, i.e., the well-known inversefrequency dependence. Both regimes are non-resonant and thus extremely broadband for P

Analytic Optimization of Near-Field Optical Chirality Enhancement

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2017-01-01

We present an analytic derivation for the enhancement of local optical chirality in the near field of plasmonic nanostructures by tuning the far-field polarization of external light. We illustrate the results by means of simulations with an achiral and a chiral nanostructure assembly and demonstrate that local optical chirality is significantly enhanced with respect to circular polarization in free space. The optimal external far-field polarizations are different from both circular and linear. Symmetry properties of the nanostructure can be exploited to determine whether the optimal far-field polarization is circular. Furthermore, the optimal far-field polarization depends on the frequency, which results in complex-shaped laser pulses for broadband optimization. PMID:28239617

Enhanced Bio-hydrogen Production from Protein Wastewater by Altering Protein Structure and Amino Acids Acidification Type

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Xiao, Naidong; Chen, Yinguang; Chen, Aihui; Feng, Leiyu

2014-01-01

Enhanced bio-hydrogen production from protein wastewater by altering protein structure and amino acids acidification type via pH control was investigated. The hydrogen production reached 205.2 mL/g-protein when protein wastewater was pretreated at pH 12 and then fermented at pH 10. The mechanism studies showed that pH 12 pretreatment significantly enhanced protein bio-hydrolysis during the subsequent fermentation stage as it caused the unfolding of protein, damaged the protein hydrogen bonding networks, and destroyed the disulfide bridges, which increased the susceptibility of protein to protease. Moreover, pH 10 fermentation produced more acetic but less propionic acid during the anaerobic fermentation of amino acids, which was consistent with the theory of fermentation type affecting hydrogen production. Further analyses of the critical enzymes, genes, and microorganisms indicated that the activity and abundance of hydrogen producing bacteria in the pH 10 fermentation reactor were greater than those in the control. PMID:24495932

Enhanced bio-hydrogen production from protein wastewater by altering protein structure and amino acids acidification type.

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Xiao, Naidong; Chen, Yinguang; Chen, Aihui; Feng, Leiyu

2014-02-05

Enhanced bio-hydrogen production from protein wastewater by altering protein structure and amino acids acidification type via pH control was investigated. The hydrogen production reached 205.2 mL/g-protein when protein wastewater was pretreated at pH 12 and then fermented at pH 10. The mechanism studies showed that pH 12 pretreatment significantly enhanced protein bio-hydrolysis during the subsequent fermentation stage as it caused the unfolding of protein, damaged the protein hydrogen bonding networks, and destroyed the disulfide bridges, which increased the susceptibility of protein to protease. Moreover, pH 10 fermentation produced more acetic but less propionic acid during the anaerobic fermentation of amino acids, which was consistent with the theory of fermentation type affecting hydrogen production. Further analyses of the critical enzymes, genes, and microorganisms indicated that the activity and abundance of hydrogen producing bacteria in the pH 10 fermentation reactor were greater than those in the control.

Complementary bowtie aperture for localizing and enhancing optical magnetic field

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Zhou, Nan; Kinzel, Edward C.; Xu, Xianfan

2011-08-01

Nanoscale bowtie antenna and bowtie aperture antenna have been shown to generate strongly enhanced and localized electric fields below the diffraction limit in the optical frequency range. According to Babinet's principle, their complements will be efficient for concentrating and enhancing magnetic fields. In this Letter, we discuss the enhancement of magnetic field intensity of nanoscale complementary bowtie aperture as well as complementary bowtie aperture antenna, or diabolo nanoantenna. We show that the complementary bowtie antenna resonates at a smaller wavelength and thus is more suitable for applications near visible wavelengths. The near-field magnetic intensity can be further enhanced by the addition of groove structures that scatter surface plasmon.

An Overview of Hardware for Protein Crystallization in a Magnetic Field

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Er-Kai Yan

2016-11-01

Full Text Available Protein crystallization under a magnetic field is an interesting research topic because a magnetic field may provide a special environment to acquire improved quality protein crystals. Because high-quality protein crystals are very useful in high-resolution structure determination using diffraction techniques (X-ray, neutron, and electron diffraction, research using magnetic fields in protein crystallization has attracted substantial interest; some studies have been performed in the past two decades. In this research field, the hardware is especially essential for successful studies because the environment is special and the design and utilization of the research apparatus in such an environment requires special considerations related to the magnetic field. This paper reviews the hardware for protein crystallization (including the magnet systems and the apparatus designed for use in a magnetic field and progress in this area. Future prospects in this field will also be discussed.

Energy landscape of all-atom protein-protein interactions revealed by multiscale enhanced sampling.

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Kei Moritsugu

2014-10-01

Full Text Available Protein-protein interactions are regulated by a subtle balance of complicated atomic interactions and solvation at the interface. To understand such an elusive phenomenon, it is necessary to thoroughly survey the large configurational space from the stable complex structure to the dissociated states using the all-atom model in explicit solvent and to delineate the energy landscape of protein-protein interactions. In this study, we carried out a multiscale enhanced sampling (MSES simulation of the formation of a barnase-barstar complex, which is a protein complex characterized by an extraordinary tight and fast binding, to determine the energy landscape of atomistic protein-protein interactions. The MSES adopts a multicopy and multiscale scheme to enable for the enhanced sampling of the all-atom model of large proteins including explicit solvent. During the 100-ns MSES simulation of the barnase-barstar system, we observed the association-dissociation processes of the atomistic protein complex in solution several times, which contained not only the native complex structure but also fully non-native configurations. The sampled distributions suggest that a large variety of non-native states went downhill to the stable complex structure, like a fast folding on a funnel-like potential. This funnel landscape is attributed to dominant configurations in the early stage of the association process characterized by near-native orientations, which will accelerate the native inter-molecular interactions. These configurations are guided mostly by the shape complementarity between barnase and barstar, and lead to the fast formation of the final complex structure along the downhill energy landscape.

Model calculation of the scanned field enhancement factor of CNTs

International Nuclear Information System (INIS)

Ahmad, Amir; Tripathi, V K

2006-01-01

The field enhancement factor of a carbon nanotube (CNT) placed in a cluster of CNTs is smaller than an isolated CNT because the electric field on one tube is screened by neighbouring tubes. This screening depends on the length of the CNTs and the spacing between them. We have derived an expression to compute the field enhancement factor of CNTs under any positional distribution of CNTs using a model of a floating sphere between parallel anode and cathode plates. Using this expression we can compute the field enhancement factor of a CNT in a cluster (non-uniformly distributed CNTs). This expression is used to compute the field enhancement factor of a CNT in an array (uniformly distributed CNTs). Comparison has been shown with experimental results and existing models

Near-field enhanced thermionic energy conversion for renewable energy recycling

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Ghashami, Mohammad; Cho, Sung Kwon; Park, Keunhan

2017-09-01

This article proposes a new energy harvesting concept that greatly enhances thermionic power generation with high efficiency by exploiting the near-field enhancement of thermal radiation. The proposed near-field enhanced thermionic energy conversion (NETEC) system is uniquely configured with a low-bandgap semiconductor cathode separated from a thermal emitter with a subwavelength gap distance, such that a significant amount of electrons can be photoexcited by near-field thermal radiation to contribute to the enhancement of thermionic current density. We theoretically demonstrate that the NETEC system can generate electric power at a significantly lower temperature than the standard thermionic generator, and the energy conversion efficiency can exceed 40%. The obtained results reveal that near-field photoexcitation can enhance the thermionic power output by more than 10 times, making this hybrid system attractive for renewable energy recycling.

Evidence that pulsed electric field treatment enhances the cell wall porosity of yeast cells.

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Ganeva, Valentina; Galutzov, Bojidar; Teissie, Justin

2014-02-01

The application of rectangular electric pulses, with 0.1-2 ms duration and field intensity of 2.5-4.5 kV/cm, to yeast suspension mediates liberation of cytoplasmic proteins without cell lysis. The aim of this study was to evaluate the effect of pulsed electric field with similar parameters on cell wall porosity of different yeast species. We found that electrically treated cells become more susceptible to lyticase digestion. In dependence on the strain and the electrical conditions, cell lysis was obtained at 2-8 times lower enzyme concentration in comparison with control untreated cells. The increase of the maximal lysis rate was between two and nine times. Furthermore, when applied at low concentration (1 U/ml), the lyticase enhanced the rate of protein liberation from electropermeabilized cells without provoking cell lysis. Significant differences in the cell surface of control and electrically treated cells were revealed by scanning electron microscopy. Data presented in this study allow us to conclude that electric field pulses provoke not only plasma membrane permeabilization, but also changes in the cell wall structure, leading to increased wall porosity.

Pulsed magnetic field: a contemporary approach offers to enhance plant growth and yield of soybean.

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Radhakrishnan, Ramalingam; Ranjitha Kumari, Bollipo Diana

2012-02-01

The possible involvement of pulsed magnetic field (PMF) pretreatment in development and yield of soybean was investigated. Seeds were subjected to 20 days with 1500 nT at 10.0 Hz of PMF for 5 h per day. PMF pretreatment increased the plant height, fresh and dry weight, and protein content with the changes of protein profile in 8 days old seedlings. In addition, activity of enzymes such as β-amylase, acid phosphatase, polyphenol oxidase and catalase was enhanced while α-amylase, alkaline phosphatase, protease and nitrate reductase activities declined due to PMF exposure. However, a considerable increment of Fe, Cu, Mn, Zn, Mg, K and Na contents with reduced level of Ca was found in PMF treated seedlings. The number of leaves, pods, seeds and length of pods, and weight of seeds were also remarkably higher in PMF treatment in contrast to controls. The results suggest that pretreatment of PMF plays important roles in improvement of crop productivity of soybean through the enhancement of protein, mineral accumulation and enzyme activities which leads to increase the growth and yield. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Protein Secondary Structure Prediction Using Deep Convolutional Neural Fields.

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Wang, Sheng; Peng, Jian; Ma, Jianzhu; Xu, Jinbo

2016-01-11

Protein secondary structure (SS) prediction is important for studying protein structure and function. When only the sequence (profile) information is used as input feature, currently the best predictors can obtain ~80% Q3 accuracy, which has not been improved in the past decade. Here we present DeepCNF (Deep Convolutional Neural Fields) for protein SS prediction. DeepCNF is a Deep Learning extension of Conditional Neural Fields (CNF), which is an integration of Conditional Random Fields (CRF) and shallow neural networks. DeepCNF can model not only complex sequence-structure relationship by a deep hierarchical architecture, but also interdependency between adjacent SS labels, so it is much more powerful than CNF. Experimental results show that DeepCNF can obtain ~84% Q3 accuracy, ~85% SOV score, and ~72% Q8 accuracy, respectively, on the CASP and CAMEO test proteins, greatly outperforming currently popular predictors. As a general framework, DeepCNF can be used to predict other protein structure properties such as contact number, disorder regions, and solvent accessibility.

How well do force fields capture the strength of salt bridges in proteins?

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Mustapha Carab Ahmed

2018-06-01

Full Text Available Salt bridges form between pairs of ionisable residues in close proximity and are important interactions in proteins. While salt bridges are known to be important both for protein stability, recognition and regulation, we still do not have fully accurate predictive models to assess the energetic contributions of salt bridges. Molecular dynamics simulation is one technique that may be used study the complex relationship between structure, solvation and energetics of salt bridges, but the accuracy of such simulations depends on the force field used. We have used NMR data on the B1 domain of protein G (GB1 to benchmark molecular dynamics simulations. Using enhanced sampling simulations, we calculated the free energy of forming a salt bridge for three possible lysine-carboxylate ionic interactions in GB1. The NMR experiments showed that these interactions are either not formed, or only very weakly formed, in solution. In contrast, we show that the stability of the salt bridges is overestimated, to different extents, in simulations of GB1 using seven out of eight commonly used combinations of fixed charge force fields and water models. We also find that the Amber ff15ipq force field gives rise to weaker salt bridges in good agreement with the NMR experiments. We conclude that many force fields appear to overstabilize these ionic interactions, and that further work may be needed to refine our ability to model quantitatively the stability of salt bridges through simulations. We also suggest that comparisons between NMR experiments and simulations will play a crucial role in furthering our understanding of this important interaction.

The competitor-introduced Ggamma recruitment system, a new approach for screening affinity-enhanced proteins.

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Fukuda, Nobuo; Ishii, Jun; Tanaka, Tsutomu; Kondo, Akihiko

2010-04-01

We have developed a new approach based on the Ggamma recruitment system to screen affinity-enhanced proteins by expressing a binding competitor. The previously established Ggamma recruitment system is a yeast two-hybrid (Y2H) system that utilizes G-protein signaling, and is based on the fact that membrane localization of the G-protein gamma subunit (Ggamma) is essential for signal transduction in yeast. In the original Y2H system, an engineered Ggamma that lacks membrane localization upon deletion of the lipid modification site (Ggamma(cyto)) is produced, and a candidate protein with an artificial lipidation site and its counterpart fused with Ggamma(cyto) are expressed. As protein-protein interactions bring Ggamma(cyto) towards the plasma membrane, G-protein signaling can be activated, and the interaction is detected by various cellular responses as the readout. In the current study, we expressed a third cytosolic protein that competes with the candidate protein to specifically isolate affinity-enhanced mutants from a mutation library of the candidate protein. Enhancing the affinity of the protein candidate guides the counterpart-Ggamma(cyto) fusion protein towards the plasma membrane and activates signaling. Using mutants of the Z domain derived from Staphylococcus aureus protein A as candidate proteins or competitors, and the Fc portion of human immunoglobulin G (IgG) as the counterpart, we demonstrate that affinity-enhanced proteins can be effectively screened from a library containing a 10 000-fold excess of non-enhanced proteins. This new approach, called the competitor-introduced Ggamma recruitment system, will be useful for efficient discovery of rare valuable candidates hidden among excess ordinary ones.

Protein sensing by nanofluidic crystal and its signal enhancement

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Sang, Jianming; Du, Hongtan; Wang, Wei; Chu, Ming; Wang, Yuedan; Li, Haichao; Alice Zhang, Haixia; Wu, Wengang; Li, Zhihong

2013-01-01

Nanofluidics has a unique property that ionic conductance across a nanometer-sized confined space is strongly affected by the space surface charge density, which can be utilized to construct electrical read-out biosensor. Based on this principle, this work demonstrated a novel protein sensor along with a sandwich signal enhancement approach. Nanoparticles with designed aptamer onside are assembled in a suspended micropore to form a 3-dimensional network of nanometer-sized interstices, named as nanofluidic crystal hereafter, as the basic sensing unit. Proteins captured by aptamers will change the surface charge density of nanoparticles and thereby can be detected by monitoring the ionic conductance across this nanofluidic crystal. Another aptamer can further enlarge the variations of the surface charge density by forming a sandwich structure (capturing aptamer/protein/signal enhancement aptamer) and the read-out conductance as well. The preliminary experimental results indicated that human α-thrombin was successfully detected by the corresponding aptamer modified nanofluidic crystal with the limit of detection of 5 nM (0.18 μg/ml) and the read-out signal was enhanced up to 3 folds by using another thrombin aptamer. Being easy to graft probe, facile and low-cost to prepare the nano-device, and having an electrical read-out, the present nanofluidic crystal scheme is a promising and universal strategy for protein sensing. PMID:24404017

Predicting protein complexes from weighted protein-protein interaction graphs with a novel unsupervised methodology: Evolutionary enhanced Markov clustering.

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Theofilatos, Konstantinos; Pavlopoulou, Niki; Papasavvas, Christoforos; Likothanassis, Spiros; Dimitrakopoulos, Christos; Georgopoulos, Efstratios; Moschopoulos, Charalampos; Mavroudi, Seferina

2015-03-01

Proteins are considered to be the most important individual components of biological systems and they combine to form physical protein complexes which are responsible for certain molecular functions. Despite the large availability of protein-protein interaction (PPI) information, not much information is available about protein complexes. Experimental methods are limited in terms of time, efficiency, cost and performance constraints. Existing computational methods have provided encouraging preliminary results, but they phase certain disadvantages as they require parameter tuning, some of them cannot handle weighted PPI data and others do not allow a protein to participate in more than one protein complex. In the present paper, we propose a new fully unsupervised methodology for predicting protein complexes from weighted PPI graphs. The proposed methodology is called evolutionary enhanced Markov clustering (EE-MC) and it is a hybrid combination of an adaptive evolutionary algorithm and a state-of-the-art clustering algorithm named enhanced Markov clustering. EE-MC was compared with state-of-the-art methodologies when applied to datasets from the human and the yeast Saccharomyces cerevisiae organisms. Using public available datasets, EE-MC outperformed existing methodologies (in some datasets the separation metric was increased by 10-20%). Moreover, when applied to new human datasets its performance was encouraging in the prediction of protein complexes which consist of proteins with high functional similarity. In specific, 5737 protein complexes were predicted and 72.58% of them are enriched for at least one gene ontology (GO) function term. EE-MC is by design able to overcome intrinsic limitations of existing methodologies such as their inability to handle weighted PPI networks, their constraint to assign every protein in exactly one cluster and the difficulties they face concerning the parameter tuning. This fact was experimentally validated and moreover, new

Optimization of translation profiles enhances protein expression and solubility.

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Anne-Katrin Hess

Full Text Available mRNA is translated with a non-uniform speed that actively coordinates co-translational folding of protein domains. Using structure-based homology we identified the structural domains in epoxide hydrolases (EHs and introduced slow-translating codons to delineate the translation of single domains. These changes in translation speed dramatically improved the solubility of two EHs of metagenomic origin in Escherichia coli. Conversely, the importance of transient attenuation for the folding, and consequently solubility, of EH was evidenced with a member of the EH family from Agrobacterium radiobacter, which partitions in the soluble fraction when expressed in E. coli. Synonymous substitutions of codons shaping the slow-transiting regions to fast-translating codons render this protein insoluble. Furthermore, we show that low protein yield can be enhanced by decreasing the free folding energy of the initial 5'-coding region, which can disrupt mRNA secondary structure and enhance ribosomal loading. This study provides direct experimental evidence that mRNA is not a mere messenger for translation of codons into amino acids but bears an additional layer of information for folding, solubility and expression level of the encoded protein. Furthermore, it provides a general frame on how to modulate and fine-tune gene expression of a target protein.

Geosynchronous magnetic field responses to fast solar wind dynamic pressure enhancements: MHD field model

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T. R. Sun

2012-08-01

Full Text Available We performed global MHD simulations of the geosynchronous magnetic field in response to fast solar wind dynamic pressure (Pd enhancements. Taking three Pd enhancement events in 2000 as examples, we found that the main features of the total field B and the dominant component Bz can be efficiently predicted by the MHD model. The predicted B and Bz varies with local time, with the highest level near noon and a slightly lower level around mid-night. However, it is more challenging to accurately predict the responses of the smaller component at the geosynchronous orbit (i.e., Bx and By. In contrast, the limitations of T01 model in predicting responses to fast Pd enhancements are presented.

Field-enhanced REB deposition and Bremsstrahlung production

International Nuclear Information System (INIS)

Halbleib, J.A. Sr.; Widner, M.M.

1977-07-01

Recently developed models are employed to describe the interaction of a high-current REB (relativistic electron beam) with planar gold foils in the presence of macroscopic electromagnetic fields. It is shown that, under certain conditions, azimuthal magnetic fields which either penetrate into the foil and/or exist on the transmission side of the foil can significantly enhance the specific power deposited in the foil over that which would be deposited for diode fields alone. Similar field effects suggest methods for improving the external conversion efficiencies, softening the spectra and focussing the source intensities of flash x-ray facilities. Finally, preliminary results are shown from a new trajectory-field model for self-consistent REB transport

Drosophila TDP-43 RNA-Binding Protein Facilitates Association of Sister Chromatid Cohesion Proteins with Genes, Enhancers and Polycomb Response Elements.

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Amanda Swain

2016-09-01

Full Text Available The cohesin protein complex mediates sister chromatid cohesion and participates in transcriptional control of genes that regulate growth and development. Substantial reduction of cohesin activity alters transcription of many genes without disrupting chromosome segregation. Drosophila Nipped-B protein loads cohesin onto chromosomes, and together Nipped-B and cohesin occupy essentially all active transcriptional enhancers and a large fraction of active genes. It is unknown why some active genes bind high levels of cohesin and some do not. Here we show that the TBPH and Lark RNA-binding proteins influence association of Nipped-B and cohesin with genes and gene regulatory sequences. In vitro, TBPH and Lark proteins specifically bind RNAs produced by genes occupied by Nipped-B and cohesin. By genomic chromatin immunoprecipitation these RNA-binding proteins also bind to chromosomes at cohesin-binding genes, enhancers, and Polycomb response elements (PREs. RNAi depletion reveals that TBPH facilitates association of Nipped-B and cohesin with genes and regulatory sequences. Lark reduces binding of Nipped-B and cohesin at many promoters and aids their association with several large enhancers. Conversely, Nipped-B facilitates TBPH and Lark association with genes and regulatory sequences, and interacts with TBPH and Lark in affinity chromatography and immunoprecipitation experiments. Blocking transcription does not ablate binding of Nipped-B and the RNA-binding proteins to chromosomes, indicating transcription is not required to maintain binding once established. These findings demonstrate that RNA-binding proteins help govern association of sister chromatid cohesion proteins with genes and enhancers.

Electric Field Stimulation Enhances Healing of Post-Traumatic Osteoarthritic Cartilage

Science.gov (United States)

2017-10-01

AWARD NUMBER: W81XWH-14-1-0591 TITLE: Electric Field Stimulation Enhances Healing of Post-Traumatic Osteoarthritic Cartilage PRINCIPAL...response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing...2016 – 29 Sep 2017 4. TITLE AND SUBTITLE Cartilage 5a. CONTRACT NUMBER Electric Field Stimulation Enhances Healing of Post-Traumatic Osteoarthritic

Cartilage oligomeric matrix protein enhances the vascularization of acellular nerves

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Wei-ling Cui

2016-01-01

Full Text Available Vascularization of acellular nerves has been shown to contribute to nerve bridging. In this study, we used a 10-mm sciatic nerve defect model in rats to determine whether cartilage oligomeric matrix protein enhances the vascularization of injured acellular nerves. The rat nerve defects were treated with acellular nerve grafting (control group alone or acellular nerve grafting combined with intraperitoneal injection of cartilage oligomeric matrix protein (experimental group. As shown through two-dimensional imaging, the vessels began to invade into the acellular nerve graft from both anastomotic ends at day 7 post-operation, and gradually covered the entire graft at day 21. The vascular density, vascular area, and the velocity of revascularization in the experimental group were all higher than those in the control group. These results indicate that cartilage oligomeric matrix protein enhances the vascularization of acellular nerves.

Protein-Ligand Informatics Force Field (PLIff): Toward a Fully Knowledge Driven "Force Field" for Biomolecular Interactions.

Science.gov (United States)

Verdonk, Marcel L; Ludlow, R Frederick; Giangreco, Ilenia; Rathi, Prakash Chandra

2016-07-28

The Protein Data Bank (PDB) contains a wealth of data on nonbonded biomolecular interactions. If this information could be distilled down to nonbonded interaction potentials, these would have some key advantages over standard force fields. However, there are some important outstanding issues to address in order to do this successfully. This paper introduces the protein-ligand informatics "force field", PLIff, which begins to address these key challenges ( https://bitbucket.org/AstexUK/pli ). As a result of their knowledge-based nature, the next-generation nonbonded potentials that make up PLIff automatically capture a wide range of interaction types, including special interactions that are often poorly described by standard force fields. We illustrate how PLIff may be used in structure-based design applications, including interaction fields, fragment mapping, and protein-ligand docking. PLIff performs at least as well as state-of-the art scoring functions in terms of pose predictions and ranking compounds in a virtual screening context.

Numerical Study of Electric Field Enhanced Combustion

KAUST Repository

Han, Jie

2016-01-01

Electric fields can be used to change and control flame properties, for example changing flame speed, enhancing flame stability, or reducing pollutant emission. The ions generated in flames are believed to play the primary role. Although experiments

Enhanced gauge symmetry and winding modes in double field theory

Energy Technology Data Exchange (ETDEWEB)

Aldazabal, G. [Centro Atómico Bariloche,8400 S.C. de Bariloche (Argentina); Instituto Balseiro (CNEA-UNC) and CONICET,8400 S.C. de Bariloche (Argentina); Graña, M. [Institut de Physique Théorique, CEA/ Saclay,91191 Gif-sur-Yvette Cedex (France); Iguri, S. [Instituto de Astronomía y Física del Espacio (CONICET-UBA), Universidad de Buenos Aires,1428 Buenos Aires (Argentina); Mayo, M. [Centro Atómico Bariloche,8400 S.C. de Bariloche (Argentina); Instituto Balseiro (CNEA-UNC) and CONICET,8400 S.C. de Bariloche (Argentina); Nuñez, C. [Instituto de Astronomía y Física del Espacio (CONICET-UBA), Universidad de Buenos Aires,1428 Buenos Aires (Argentina); Departamento de Física, FCEN, Universidad de Buenos Aires,C.C. 67 - Suc. 28, 1428 Buenos Aires (Argentina); Rosabal, J.A. [Departamento de Física, FCEN, Universidad de Buenos Aires,C.C. 67 - Suc. 28, 1428 Buenos Aires (Argentina)

2016-03-15

We provide an explicit example of how the string winding modes can be incorporated in double field theory. Our guiding case is the closed bosonic string compactified on a circle of radius close to the self-dual point, where some modes with non-zero winding or discrete momentum number become massless and enhance the U(1)×U(1) symmetry to SU(2)×SU(2). We compute three-point string scattering amplitudes of massless and slightly massive states, and extract the corresponding effective low energy gauge field theory. The enhanced gauge symmetry at the self-dual point and the Higgs-like mechanism arising when changing the compactification radius are examined in detail. The extra massless fields associated to the enhancement are incorporated into a generalized frame with ((O(d+3,d+3))/(O(d+3)×O(d+3))) structure, where d is the number of non-compact dimensions. We devise a consistent double field theory action that reproduces the low energy string effective action with enhanced gauge symmetry. The construction requires a truly non-geometric frame which explicitly depends on both the compact coordinate along the circle and its dual.

3D pressure field in lipid membranes and membrane-protein complexes

DEFF Research Database (Denmark)

Ollila, O H Samuli; Risselada, H Jelger; Louhivuori, Martti

2009-01-01

We calculate full 3D pressure fields for inhomogeneous nanoscale systems using molecular dynamics simulation data. The fields represent systems with increasing level of complexity, ranging from semivesicles and vesicles to membranes characterized by coexistence of two phases, including also...... a protein-membrane complex. We show that the 3D pressure field is distinctly different for curved and planar bilayers, the pressure field depends strongly on the phase of the membrane, and that an integral protein modulates the tension and elastic properties of the membrane....

Extractable proteins from field radiation vulcanized natural rubber latex

Energy Technology Data Exchange (ETDEWEB)

Parra, Duclerc F. [Chemical and Environmental Centre, Nuclear Energy Research Institute, Av. Lineu Prestes, 2242-CEP Sao Paulo (Brazil)]. E-mail: dfparra@ipen.br; Pinto Martins, Carlos Felipe [Chemical and Environmental Centre, Nuclear Energy Research Institute, Av. Lineu Prestes, 2242-CEP Sao Paulo (Brazil); Collantes, Hugo D.C. [Chemical and Environmental Centre, Nuclear Energy Research Institute, Av. Lineu Prestes, 2242-CEP Sao Paulo (Brazil); Lugao, Ademar B. [Chemical and Environmental Centre, Nuclear Energy Research Institute, Av. Lineu Prestes, 2242-CEP Sao Paulo (Brazil)

2005-07-01

The type I allergy associated with the use of natural rubber latex (NRL) products is caused by the NRL proteins leached by the sweat or other body fluids. Makuuchi's group proposed for the first time the proteins removal by the addition of water-soluble polymers (WSP) on radiation vulcanization of natural rubber latex (RVNRL) that is a promising process under development in many countries. In this study, Brazilian field natural rubber was irradiated with a {sup 60}Co gamma source to reduce the content of WSP in the final product. WSP was used as additive to improve the extraction of protein. After irradiation the RVNRL was centrifuged to extract the WSP and proteins. The analytical methodology for protein content was based on the modified Lowry method according to ASTM D5712. Protein determination was carried out in serum of latex and in the extracts of the gloves. The concentration of extractable water-soluble proteins in serum of irradiated field NRL (NRL1), not irradiated one (NRL2); of twice centrifuged sample with polymer additive NRL (NRL3) and of the glove manufactured (NRLG) are compared with commercial glove (CG). The irradiation process increases the extractable water-soluble proteins, EP, as reported in the literature. In this study the use of polymeric additive on the bi-centrifugation process to remove protein was successful and the EP of the glove obtained in NRL3 was at around 40% of the commercial glove.

Understanding and Manipulating Electrostatic Fields at the Protein-Protein Interface Using Vibrational Spectroscopy and Continuum Electrostatics Calculations.

Science.gov (United States)

Ritchie, Andrew W; Webb, Lauren J

2015-11-05

Biological function emerges in large part from the interactions of biomacromolecules in the complex and dynamic environment of the living cell. For this reason, macromolecular interactions in biological systems are now a major focus of interest throughout the biochemical and biophysical communities. The affinity and specificity of macromolecular interactions are the result of both structural and electrostatic factors. Significant advances have been made in characterizing structural features of stable protein-protein interfaces through the techniques of modern structural biology, but much less is understood about how electrostatic factors promote and stabilize specific functional macromolecular interactions over all possible choices presented to a given molecule in a crowded environment. In this Feature Article, we describe how vibrational Stark effect (VSE) spectroscopy is being applied to measure electrostatic fields at protein-protein interfaces, focusing on measurements of guanosine triphosphate (GTP)-binding proteins of the Ras superfamily binding with structurally related but functionally distinct downstream effector proteins. In VSE spectroscopy, spectral shifts of a probe oscillator's energy are related directly to that probe's local electrostatic environment. By performing this experiment repeatedly throughout a protein-protein interface, an experimental map of measured electrostatic fields generated at that interface is determined. These data can be used to rationalize selective binding of similarly structured proteins in both in vitro and in vivo environments. Furthermore, these data can be used to compare to computational predictions of electrostatic fields to explore the level of simulation detail that is necessary to accurately predict our experimental findings.

Water-processed carbon nanotube/graphene hybrids with enhanced field emission properties

International Nuclear Information System (INIS)

Song, Meng; Xu, Peng; Wang, Xu; Wu, Huizhen; Wang, Miao; Song, Yenan; Li, Zhenhua; Zhao, Pei; Shang, Xuefu

2015-01-01

Integrating carbon nanotubes (CNTs) and graphene into hybrid structures provides a novel approach to three dimensional (3D) materials with advantageous properties. Here we present a water-processing method to create integrated CNT/graphene hybrids and test their field emission properties. With an optimized mass ratio of CNTs to graphene, the hybrid shows a significantly enhanced field emission performance, such as turn-on electric field of 0.79 V/μm, threshold electric field of 1.05 V/μm, maximum current density of 0.1 mA/cm 2 , and field enhancement factor of ∼1.3 × 10 4 . The optimized mass ratio for field emission emphasizes the importance of both CNTs and graphene in the hybrid. We also hypothesize a possible mechanism for this enhanced field emission performance from the CNT/graphene hybrid. During the solution treatment, graphene oxide behaves as surfactant sheets for CNTs to form a well dispersed solution, which leads to a better organized 3D structure with more conducting channels for electron transport

Water-processed carbon nanotube/graphene hybrids with enhanced field emission properties

Energy Technology Data Exchange (ETDEWEB)

Song, Meng; Xu, Peng; Wang, Xu; Wu, Huizhen; Wang, Miao, E-mail: peizhao@zju.edu.cn, E-mail: miaowang@css.zju.edu.cn [Department of Physics, Zhejiang University, Hangzhou 310027 (China); Song, Yenan; Li, Zhenhua; Zhao, Pei, E-mail: peizhao@zju.edu.cn, E-mail: miaowang@css.zju.edu.cn [Institute of Applied Mechanics, Zhejiang University, Hangzhou 310027 (China); Shang, Xuefu [Department of Physics, Faculty of Science, Jiangsu University, Zhenjiang 212013 (China)

2015-09-15

Integrating carbon nanotubes (CNTs) and graphene into hybrid structures provides a novel approach to three dimensional (3D) materials with advantageous properties. Here we present a water-processing method to create integrated CNT/graphene hybrids and test their field emission properties. With an optimized mass ratio of CNTs to graphene, the hybrid shows a significantly enhanced field emission performance, such as turn-on electric field of 0.79 V/μm, threshold electric field of 1.05 V/μm, maximum current density of 0.1 mA/cm{sup 2}, and field enhancement factor of ∼1.3 × 10{sup 4}. The optimized mass ratio for field emission emphasizes the importance of both CNTs and graphene in the hybrid. We also hypothesize a possible mechanism for this enhanced field emission performance from the CNT/graphene hybrid. During the solution treatment, graphene oxide behaves as surfactant sheets for CNTs to form a well dispersed solution, which leads to a better organized 3D structure with more conducting channels for electron transport.

Sensitivity enhancement for membrane proteins reconstituted in parallel and perpendicular oriented bicelles obtained by using repetitive cross-polarization and membrane-incorporated free radicals

Energy Technology Data Exchange (ETDEWEB)

Koroloff, Sophie N. [North Carolina State University, Department of Chemistry (United States); Tesch, Deanna M. [Shaw University (United States); Awosanya, Emmanuel O.; Nevzorov, Alexander A., E-mail: alex-nevzorov@ncsu.edu [North Carolina State University, Department of Chemistry (United States)

2017-02-15

Multidimensional separated local-field and spin-exchange experiments employed by oriented-sample solid-state NMR are essential for structure determination and spectroscopic assignment of membrane proteins reconstituted in macroscopically aligned lipid bilayers. However, these experiments typically require a large number of scans in order to establish interspin correlations. Here we have shown that a combination of optimized repetitive cross polarization (REP-CP) and membrane-embedded free radicals allows one to enhance the signal-to-noise ratio by factors 2.4-3.0 in the case of Pf1 coat protein reconstituted in magnetically aligned bicelles with their normals being either parallel or perpendicular to the main magnetic field. Notably, spectral resolution is not affected at the 2:1 radical-to-protein ratio. Spectroscopic assignment of Pf1 coat protein in the parallel bicelles has been established as an illustration of the method. The proposed methodology will advance applications of oriented-sample NMR technique when applied to samples containing smaller quantities of proteins and three-dimensional experiments.

Graphene enhanced field emission from InP nanocrystals.

Science.gov (United States)

Iemmo, L; Di Bartolomeo, A; Giubileo, F; Luongo, G; Passacantando, M; Niu, G; Hatami, F; Skibitzki, O; Schroeder, T

2017-12-08

We report the observation of field emission (FE) from InP nanocrystals (NCs) epitaxially grown on an array of p-Si nanotips. We prove that FE can be enhanced by covering the InP NCs with graphene. The measurements are performed inside a scanning electron microscope chamber with a nano-controlled W-thread used as an anode. We analyze the FE by Fowler-Nordheim theory and find that the field enhancement factor increases monotonically with the spacing between the anode and the cathode. We also show that InP/p-Si junction has a rectifying behavior, while graphene on InP creates an ohmic contact. Understanding the fundamentals of such nanojunctions is key for applications in nanoelectronics.

Topology optimization of nanoparticles for localized electromagnetic field enhancement

DEFF Research Database (Denmark)

Christiansen, Rasmus Ellebæk; Vester-Petersen, Joakim; Madsen, Søren Peder

2017-01-01

We consider the design of individual and periodic arrangements of metal or semiconductor nanoparticles for localized electromagnetic field enhancement utilizing a topology optimization based numerical framework as the design tool. We aim at maximizing a function of the electromagnetic field...

Near-Field Enhanced Photochemistry of Single Molecules in a Scanning Tunneling Microscope Junction.

Science.gov (United States)

Böckmann, Hannes; Gawinkowski, Sylwester; Waluk, Jacek; Raschke, Markus B; Wolf, Martin; Kumagai, Takashi

2018-01-10

Optical near-field excitation of metallic nanostructures can be used to enhance photochemical reactions. The enhancement under visible light illumination is of particular interest because it can facilitate the use of sunlight to promote photocatalytic chemical and energy conversion. However, few studies have yet addressed optical near-field induced chemistry, in particular at the single-molecule level. In this Letter, we report the near-field enhanced tautomerization of porphycene on a Cu(111) surface in a scanning tunneling microscope (STM) junction. The light-induced tautomerization is mediated by photogenerated carriers in the Cu substrate. It is revealed that the reaction cross section is significantly enhanced in the presence of a Au tip compared to the far-field induced process. The strong enhancement occurs in the red and near-infrared spectral range for Au tips, whereas a W tip shows a much weaker enhancement, suggesting that excitation of the localized plasmon resonance contributes to the process. Additionally, using the precise tip-surface distance control of the STM, the near-field enhanced tautomerization is examined in and out of the tunneling regime. Our results suggest that the enhancement is attributed to the increased carrier generation rate via decay of the excited near-field in the STM junction. Additionally, optically excited tunneling electrons also contribute to the process in the tunneling regime.

Enhanced microactuation with magnetic field curing of ...

Indian Academy of Sciences (India)

ples have been enhanced by two times when compared with that of zero field cured samples. The effect of .... Gauge of wire ... electrolitic-300 mesh (84.67 µm) LR, Product No. ... be in the body centered cubic phase with a lattice parameter.

Whey Protein Supplementation Enhances Whole Body Protein Metabolism and Performance Recovery after Resistance Exercise: A Double-Blind Crossover Study

Directory of Open Access Journals (Sweden)

Daniel W. D. West

2017-07-01

Full Text Available No study has concurrently measured changes in free-living whole body protein metabolism and exercise performance during recovery from an acute bout of resistance exercise. We aimed to determine if whey protein ingestion enhances whole body net protein balance and recovery of exercise performance during overnight (10 h and 24 h recovery after whole body resistance exercise in trained men. In a double-blind crossover design, 12 trained men (76 ± 8 kg, 24 ± 4 years old, 14% ± 5% body fat; means ± standard deviation (SD performed resistance exercise in the evening prior to consuming either 25 g of whey protein (PRO; MuscleTech 100% Whey or an energy-matched placebo (CHO immediately post-exercise (0 h, and again the following morning (~10 h of recovery. A third randomized trial, completed by the same participants, involving no exercise and no supplement served as a rested control trial (Rest. Participants ingested [15N]glycine to determine whole body protein kinetics and net protein balance over 10 and 24 h of recovery. Performance was assessed pre-exercise and at 0, 10, and 24 h of recovery using a battery of tests. Net protein balance tended to improve in PRO (P = 0.064; effect size (ES = 0.61, PRO vs. CHO during overnight recovery. Over 24 h, net balance was enhanced in PRO (P = 0.036 but not in CHO (P = 0.84; ES = 0.69, PRO vs. CHO, which was mediated primarily by a reduction in protein breakdown (PRO < CHO; P < 0.01. Exercise decreased repetitions to failure (REP, maximal strength (MVC, peak and mean power, and countermovement jump performance (CMJ at 0 h (all P < 0.05 vs. Pre. At 10 h, there were small-to-moderate effects for enhanced recovery of the MVC (ES = 0.56, mean power (ES = 0.49, and CMJ variables (ES: 0.27–0.49 in PRO. At 24 h, protein supplementation improved MVC (ES = 0.76, REP (ES = 0.44, and peak power (ES = 0.55. In conclusion, whey protein supplementation enhances whole body anabolism, and may improve acute recovery of

Exchange Protein Activated by cAMP Enhances Long-Term Memory Formation Independent of Protein Kinase A

Science.gov (United States)

Ma, Nan; Abel, Ted; Hernandez, Pepe J.

2009-01-01

It is well established that cAMP signaling within neurons plays a major role in the formation of long-term memories--signaling thought to proceed through protein kinase A (PKA). However, here we show that exchange protein activated by cAMP (Epac) is able to enhance the formation of long-term memory in the hippocampus and appears to do so…

Whey Protein Supplementation Enhances Whole Body Protein Metabolism and Performance Recovery after Resistance Exercise: A Double-Blind Crossover Study.

Science.gov (United States)

West, Daniel W D; Abou Sawan, Sidney; Mazzulla, Michael; Williamson, Eric; Moore, Daniel R

2017-07-11

No study has concurrently measured changes in free-living whole body protein metabolism and exercise performance during recovery from an acute bout of resistance exercise. We aimed to determine if whey protein ingestion enhances whole body net protein balance and recovery of exercise performance during overnight (10 h) and 24 h recovery after whole body resistance exercise in trained men. In a double-blind crossover design, 12 trained men (76 ± 8 kg, 24 ± 4 years old, 14% ± 5% body fat; means ± standard deviation (SD)) performed resistance exercise in the evening prior to consuming either 25 g of whey protein (PRO; MuscleTech 100% Whey) or an energy-matched placebo (CHO) immediately post-exercise (0 h), and again the following morning (~10 h of recovery). A third randomized trial, completed by the same participants, involving no exercise and no supplement served as a rested control trial (Rest). Participants ingested [ 15 N]glycine to determine whole body protein kinetics and net protein balance over 10 and 24 h of recovery. Performance was assessed pre-exercise and at 0, 10, and 24 h of recovery using a battery of tests. Net protein balance tended to improve in PRO ( P = 0.064; effect size (ES) = 0.61, PRO vs. CHO) during overnight recovery. Over 24 h, net balance was enhanced in PRO ( P = 0.036) but not in CHO ( P = 0.84; ES = 0.69, PRO vs. CHO), which was mediated primarily by a reduction in protein breakdown (PRO protein supplementation improved MVC (ES = 0.76), REP (ES = 0.44), and peak power (ES = 0.55). In conclusion, whey protein supplementation enhances whole body anabolism, and may improve acute recovery of exercise performance after a strenuous bout of resistance exercise.

Enhancing protein to extremely high content in photosynthetic bacteria during biogas slurry treatment.

Science.gov (United States)

Yang, Anqi; Zhang, Guangming; Meng, Fan; Lu, Pei; Wang, Xintian; Peng, Meng

2017-12-01

This work proposed a novel approach to achieve an extremely high protein content in photosynthetic bacteria (PSB) using biogas slurry as a culturing medium. The results showed the protein content of PSB could be enhanced strongly to 90% in the biogas slurry, which was much higher than reported microbial protein contents. The slurry was partially purified at the same time. Dark-aerobic was more beneficial than light-anaerobic condition for protein accumulation. High salinity and high ammonia of the biogas slurry were the main causes for protein enhancement. In addition, the biogas slurry provided a good buffer system for PSB to grow. The biosynthesis mechanism of protein in PSB was explored according to theoretical analysis. During biogas slurry treatment, the activities of glutamate synthase and glutamine synthetase were increased by 26.55%, 46.95% respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of External Electric Field Stress on Gliadin Protein Conformation

OpenAIRE

Singh, Ashutosh; Munshi, Shirin; Raghavan, Vijaya

2013-01-01

A molecular dynamic (MD) modeling approach was applied to evaluate the effect of external electric field on gliadin protein structure and surface properties. Static electric field strengths of 0.001 V/nm and 0.002 V/nm induced conformational changes in the protein but had no significant effect on its surface properties. The study of hydrogen bond evolution during the course of simulation revealed that the root mean square deviation, radius of gyration and secondary structure formation, all de...

In vitro digestibility, protein composition and techno-functional properties of Saskatchewan grown yellow field peas (Pisum sativum L.) as affected by processing.

Science.gov (United States)

Ma, Zhen; Boye, Joyce I; Hu, Xinzhong

2017-02-01

Saskatchewan grown yellow field pea was subjected to different processing conditions including dehulling, micronization, roasting, conventional/microwave cooking, germination, and combined germination and conventional cooking/roasting. Their nutritional and antinutritional compositions, functional properties, microstructure, thermal properties, in vitro protein and starch digestibility, and protein composition were studied. Processed field peas including conventional cooked yellow peas (CCYP), microwave cooked yellow peas (MCYP), germinated-conventional cooked yellow peas (GCCYP), and germinated-roasted yellow peas (GRYP) exhibited the significantly higher in vitro protein digestibility (IVPD), which was in accordance with their significantly lower trypsin inhibitor activity and tannin content. The SDS-PAGE and size exclusion HPLC profiles of untreated pea proteins and their hydrolysates also confirmed the IVPD result that these four treatments facilitated the hydrolysis of pea proteins to a greater extent. The CCYP, MCYP, GCCYP, and GRYP also exhibited significantly higher starch digestibility which was supported by their lower onset (T o ), peak (T p ), and conclusion (T c ) temperatures obtained from DSC thermogram, their lower pasting properties and starch damage results, as well as their distinguished amorphous flakes' configuration observed on the scanning electron microscopic image. LC/ESI-MS/MS analysis following in-gel digests of SDS-PAGE separated proteins allowed detailed compositional characterization of pea proteins. The present study would provide fundamental information to help to better understand the functionality of field peas as ingredients, and particularly in regards to agri-food industry to improve the process efficiency of field peas with enhanced nutritional and techno-functional qualities. Copyright © 2016 Elsevier Ltd. All rights reserved.

Enhancement of sedimentation and coagulation with static magnetic field

Science.gov (United States)

Zieliński, Marcin; Dębowski, Marcin; Hajduk, Anna; Rusanowska, Paulina

2017-11-01

The static magnetic field can be an alternative method for wastewater treatment. It has been proved that this physical factor, accelerates the biochemical processes, catalyzes advanced oxidation, intensifies anaerobic and aerobic processes or reduces swelling of activated sludge. There are also reports proving the positive impact of the static magnetic field on the coagulation and sedimentation, as well as the conditioning and dewatering of sludge. In order to be applied in larger scale the published results should be verified and confirmed. In the studies, the enhancement of sedimentation by the static magnetic field was observed. The best sedimentation was noted in the experiment, where magnetizers were placed on activated sludge bioreactor and secondary settling tank. No effect of the static magnetic field on coagulation with the utilization of PIX 113 was observed. However, the static magnetic field enhanced coagulation with the utilization of PAX-XL9. The results suggest that increased sedimentation of colloids and activated sludge, can in practice mean a reduction in the size of the necessary equipment for sedimentation with an unchanged efficiency of the process.

Tunable paramagnetic relaxation enhancements by [Gd(DPA)3]3- for protein structure analysis

International Nuclear Information System (INIS)

Yagi, Hiromasa; Loscha, Karin V.; Su, Xun-Cheng; Stanton-Cook, Mitchell; Huber, Thomas; Otting, Gottfried

2010-01-01

Paramagnetic relaxation enhancements (PRE) present a powerful source of structural information in nuclear magnetic resonance (NMR) studies of proteins and protein-ligand complexes. In contrast to conventional PRE reagents that are covalently attached to the protein, the complex between gadolinium and three dipicolinic acid (DPA) molecules, [Gd(DPA) 3 ] 3- , can bind to proteins in a non-covalent yet site-specific manner. This offers straightforward access to PREs that can be scaled by using different ratios of [Gd(DPA) 3 ] 3- to protein, allowing quantitative distance measurements for nuclear spins within about 15 A of the Gd 3+ ion. Such data accurately define the metal position relative to the protein, greatly enhancing the interpretation of pseudocontact shifts induced by [Ln(DPA) 3 ] 3- complexes of paramagnetic lanthanide (Ln 3+ ) ions other than gadolinium. As an example we studied the quaternary structure of the homodimeric GCN4 leucine zipper.

Partial discharges and bulk dielectric field enhancement

DEFF Research Database (Denmark)

McAllister, Iain Wilson; Johansson, Torben

2000-01-01

A consequence of partial discharge activity within a gaseous void is the production of a field enhancement in the solid dielectric in the proximity of the void. This situation arises due to the charge created by the partial discharges accumulating at the void wall. The influence of the spatial...

Reply to comment on 'Model calculation of the scanned field enhancement factor of CNTs'

International Nuclear Information System (INIS)

Ahmad, Amir; Tripathi, V K

2010-01-01

In the paper (Ahmad and Tripathi 2006 Nanotechnology 17 3798), we derived an expression to compute the field enhancement factor of CNTs under any positional distribution of CNTs by using the model of a floating sphere between parallel anode and cathode plates. Using this expression we can compute the field enhancement factor of a CNT in a cluster (non-uniformly distributed CNTs). This expression was used to compute the field enhancement factor of a CNT in an array (uniformly distributed CNTs). We used an approximation to calculate the field enhancement factor. Hence, our expressions are correct in that assumption only. Zhbanov et al (2010 Nanotechnology 21 358001) suggest a correction that can calculate the field enhancement factor without using the approximation. Hence, this correction can improve the applicability of this model. (reply)

Magnetic Field Enhanced Superconductivity in Epitaxial Thin Film WTe2.

Science.gov (United States)

Asaba, Tomoya; Wang, Yongjie; Li, Gang; Xiang, Ziji; Tinsman, Colin; Chen, Lu; Zhou, Shangnan; Zhao, Songrui; Laleyan, David; Li, Yi; Mi, Zetian; Li, Lu

2018-04-25

In conventional superconductors an external magnetic field generally suppresses superconductivity. This results from a simple thermodynamic competition of the superconducting and magnetic free energies. In this study, we report the unconventional features in the superconducting epitaxial thin film tungsten telluride (WTe 2 ). Measuring the electrical transport properties of Molecular Beam Epitaxy (MBE) grown WTe 2 thin films with a high precision rotation stage, we map the upper critical field H c2 at different temperatures T. We observe the superconducting transition temperature T c is enhanced by in-plane magnetic fields. The upper critical field H c2 is observed to establish an unconventional non-monotonic dependence on temperature. We suggest that this unconventional feature is due to the lifting of inversion symmetry, which leads to the enhancement of H c2 in Ising superconductors.

Near-field enhanced electron acceleration from dielectric nanospheres in intense few-cycle laser fields

International Nuclear Information System (INIS)

Zherebtsov, S.; Znakovskaya, I.; Wirth, A.; Herrwerth, O.; Suessmann, F.; Ahmad, I.; Trushin, S.; Fennel, Th.; Plenge, J.; Antonsson, E.

2010-01-01

Complete text of publication follows. The interaction of nanostructured materials with few-cycle laser light has attracted significant attention lately. This interest is driven by both the quest for fundamental insight into the real-time dynamics of many-electron systems and a wide range of far-reaching applications, such as, e.g. ultrafast computation and information storage on the nanoscale and the generation of XUV frequency combs. We investigated the above-threshold electron emission from isolated SiO 2 nanoparticles in waveform controlled few-cycle laser fields at intensities close to the tunneling regime. The enhancement of the electron acceleration from the silica nanoparticles was explored as a function of the particle size (ranging from 50 to 147 nm) and the laser peak intensity (1 - 4x10 13 W/cm 2 ). Obtained cut-off values in the kinetic energy spectra are displayed in Fig. 1. The cut-off values show a linear dependence with intensity within the studied intensity range, with the average cut-off energy being 53 U P , indicated by the black line. Quasi-classical simulations of the emission process reveal that electron rescattering in the locally enhanced near-field of the particle is responsible for the large energy gain. The observed near-field enhancement offers promising new routes for pushing the limits of strong-field phenomena relying on electron rescattering, such as, high-harmonic generation and molecular imaging.

Perturbation of hydration layer in solvated proteins by external electric and electromagnetic fields: Insights from non-equilibrium molecular dynamics

Science.gov (United States)

Nandi, Prithwish K.; Futera, Zdenek; English, Niall J.

2016-11-01

Given the fundamental role of water in governing the biochemistry of enzymes, and in regulating their wider biological activity (e.g., by local water concentration surrounding biomolecules), the influence of extraneous electric and electromagnetic (e/m) fields thereon is of central relevance to biophysics and, more widely, biology. With the increase in levels of local and atmospheric microwave-frequency radiation present in modern life, as well as other electric-field exposure, the impact upon hydration-water layers surrounding proteins, and biomolecules generally, becomes a particularly pertinent issue. Here, we present a (non-equilibrium) molecular-dynamics-simulation study on a model protein (hen egg-white lysozyme) hydrated in water, in which we determine, inter alia, translational self-diffusivities for both hen egg-white lysozyme and its hydration layer together with relaxation dynamics of the hydrogen-bond network between the protein and its hydration-layer water molecules on a residue-per-residue basis. Crucially, we perform this analysis both above and below the dynamical-transition temperature (at ˜220 K), at 300 and 200 K, respectively, and we compare the effects of external static-electric and e/m fields with linear-response-régime (r.m.s.) intensities of 0.02 V/Å. It was found that the translational self-diffusivity of hen egg-white lysozyme and its hydration-water layer are increased substantially in static fields, primarily due to the induced electrophoretic motion, whilst the water-protein hydrogen-bond-network-rearrangement kinetics can also undergo rather striking accelerations, primarily due to the enhancement of a larger-amplitude local translational and rotational motion by charged and dipolar residues, which serves to promote hydrogen-bond breakage and re-formation kinetics. These external-field effects are particularly evident at 200 K, where they serve to induce the protein- and solvation-layer-response effects redolent of dynamical

Output Enhancement in the Transfer-Field Machine Using Rotor ...

African Journals Online (AJOL)

Output Enhancement in the Transfer-Field Machine Using Rotor Circuit Induced Currents. ... The output of a plain transfer-field machine would be much less than that of a conventional machine of comparable size and dimensions. The use of ... The same effects have their parallel for the asynchronous mode of operation.

Determination of Protein by Fluorescence Enhancement of Curcumin in Lanthanum-Curcumin-Sodium Dodecyl Benzene Sulfonate-Protein System

Energy Technology Data Exchange (ETDEWEB)

Wang, Feng [Zaozhuang University, People' s Republic of China; Huang, Wei [Zaozhuang University, People' s Republic of China; Zhang, Yunfeng [Zaozhuang University, People' s Republic of China; Wang, Mingyin [Zaozhuang University, People' s Republic of China; Sun, Lina [Zaozhuang University, People' s Republic of China; Tang, Bo [Shandong University, Jinan, China; Wang, Wei [ORNL

2011-01-01

We found that the fluorescence intensity of the lanthanum (La(3+))-curcumin (CU) complex can be highly enhanced by proteins in the presence of sodium dodecyl benzene sulphonate (SDBS). Based on this finding, a new fluorimetric method for the determination of protein was developed. Under optimized conditions, the enhanced intensities of fluorescence are quantitatively in proportion to the concentrations of proteins in the range 0.0080-20.0 g mL(-1) for bovine serum albumin (BSA) and 0.00080-20.0 g mL(-1) for human serum albumin (HSA) with excitation of 425 nm, and 0.00020-20.0 g mL(-1) for bovine serum albumin (BSA) and 0.00080-20.0 g mL(-1)for human serum albumin (HSA) with excitation of 280 nm, while corresponding qualitative detection limits (S/N 3) are as low as 5.368, 0.573, 0.049, 0.562 g mL(-1), respectively. Study on reaction mechanism reveals that proteins can bind with La(3+), CU and SDBS through self-assembling function with electrostatic attraction, hydrogen bonding, hydrophobic interaction and van der Waals forces, etc. The proteins form a supermolecular association with multilayer structure, in which La(3+)-CU is clamped between BSA and SDBS. The unique high fluorescence enhancement of CU is resulted through synergic effects of favorable hydrophobic microenvironment provided by BSA and SDBS, and efficient intermolecular energy transfer among BSA, SDBS and CU. In energy transfer process, La(3+) plays a crucial role because it not only shortens the distance between SDBS and CU, but also acts as a "bridge" for transferring the energy from BSA to CU.

Numerical Study of Electric Field Enhanced Combustion

KAUST Repository

Han, Jie

2016-12-26

Electric fields can be used to change and control flame properties, for example changing flame speed, enhancing flame stability, or reducing pollutant emission. The ions generated in flames are believed to play the primary role. Although experiments have been carried out to study electric field enhanced combustion, they are not sufficient to explain how the ions in a flame are affected by an electric field. It is therefore necessary to investigate the problem through numerical simulations. In the present work, the electric structure of stabilized CH4/air premixed flames at atmospheric pressure within a direct current field is studied using numerical simulations. This study consists of three parts. First, the transport equations are derived from the Boltzmann kinetic equation for each individual species. Second, a general method for computing the diffusivity and mobility of ions in a gas mixture is introduced. Third, the mechanisms for neutral and charged species are improved to give better predictions of the concentrations of charged species, based on experimental data. Following from this, comprehensive numerical results are presented, including the concentrations and fluxes of charged species, the distributions of the electric field and electric potential, and the electric current-voltage relation. Two new concepts introduced with the numerical results are the plasma sheath and dead zone in the premixed flame. A reactive plasma sheath and a Boltzmann relation sheath are discovered in the region near the electrodes. The plasma sheath penetrates into the flame gas when a voltage is applied, and penetrating further if the voltage is higher. The zone outside the region of sheath penetration is defined as the dead zone. With the two concepts, analytical solutions for the electric field, electric potential and current-voltage curve are derived. The solutions directly describe the electric structure of a premixed flame subject to a DC field. These analytical solutions

Response of eight tropical plants to enhanced ammonia deposition under field, conditions prevalent with SO{sub 2} and NH{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Rao, M.V.; Khijneri, S.; Dubey, P.S.; Kumawat, D.M. [Vikram University, Ujjain (India). School of Studies in Botany

1993-12-01

The impact of SO{sub 2} on the deposition of ammonia and the response of eight tropical tree species to excess deposition of ammonia was investigated. This was achieved by studying physiological aspects like total sugars, protein, nitrate reductace (NR) activity, organic/inorganic nitrogen ratio, specific leaf area and foliar injury in plants growing under field conditions prevalent with SO{sub 2} and NH{sub 3}. Analysis of water soluble substances present on foliar surfaces of the trees indicated enhanced NH{sub 4}{sup +} deposition and thereby result in enhanced foliar protein contents. Though the enhanced nitrogen was almost the same in different plants, the plants exhibited differential metabolic disturbances. Critical analysis of the reults indicated three distinct types of plant response. Plants like {ital Azadirachta indica}, {ital Acacia auriculiformis} and {ital Bambusa arundinaceae} maintained enhanced total sugars and NR activity and incorporated excess NH{sub 4}{sup +} into proteins, thus enabling the plant to compensate/alleviate SO{sub 2} induced injury. Ficus benghalensis and Ficus religiosa maintained unaltered total sugars and NR activity and could partly incorporate NH{sub 4}{sup +} into proteins, thus modifying rhe SO{sub 2} impact to some extent. {ital Dalbergia sissoo}, {ital Eucalyptus rostrat}a and {ital Mangifera indica} could not incorporate the excess NH{sub 4}{sup +}, mainly due to declined total sugars. The results indicate the ability of a plant to undergo species specific metabolic changes in order to cope with the excess nitrogen deposition, which may ultimately result in increasing or decreasing tolerance to SO{sub 2}. 23 refs., 3 figs., 9 tabs.

A universal formula for the field enhancement factor

Science.gov (United States)

Biswas, Debabrata

2018-04-01

The field enhancement factor (FEF) is an important quantity in field emission calculations since the tunneling electron current depends very sensitively on its magnitude. The exact dependence of FEF on the emitter height h, the radius of curvature at the apex Ra, as well as the shape of the emitter base are still largely unknown. In this work, a universal formula for the field enhancement factor is derived for a single emitter. It depends on the ratio h/Ra and has the form γ a = ( 2 h / R a ) / [ α 1 ln ( 4 h / R a ) - α 2 ] , where α1 and α2 depend on the charge distribution on the emitter. Numerical results show that a simpler form γ a = ( 2 h / R a ) / [ ln ( 4 h / R a ) - α ] is equally valid with α depending on the emitter-base. Thus, for the hyperboloid, conical, and ellipsoid emitters, the value of α is 0, 0.88, and 2, while for the cylindrical base, α ≃ 2.6.

Dissociation of activated protein C functions by elimination of protein S cofactor enhancement.

LENUS (Irish Health Repository)

Harmon, Shona

2008-11-07

Activated protein C (APC) plays a critical anticoagulant role in vivo by inactivating procoagulant factor Va and factor VIIIa and thus down-regulating thrombin generation. In addition, APC bound to the endothelial cell protein C receptor can initiate protease-activated receptor-1 (PAR-1)-mediated cytoprotective signaling. Protein S constitutes a critical cofactor for the anticoagulant function of APC but is not known to be involved in regulating APC-mediated protective PAR-1 signaling. In this study we utilized a site-directed mutagenesis strategy to characterize a putative protein S binding region within the APC Gla domain. Three single amino acid substitutions within the APC Gla domain (D35T, D36A, and A39V) were found to mildly impair protein S-dependent anticoagulant activity (<2-fold) but retained entirely normal cytoprotective activity. However, a single amino acid substitution (L38D) ablated the ability of protein S to function as a cofactor for this APC variant. Consequently, in assays of protein S-dependent factor Va proteolysis using purified proteins or in the plasma milieu, APC-L38D variant exhibited minimal residual anticoagulant activity compared with wild type APC. Despite the location of Leu-38 in the Gla domain, APC-L38D interacted normally with endothelial cell protein C receptor and retained its ability to trigger PAR-1 mediated cytoprotective signaling in a manner indistinguishable from that of wild type APC. Consequently, elimination of protein S cofactor enhancement of APC anticoagulant function represents a novel and effective strategy by which to separate the anticoagulant and cytoprotective functions of APC for potential therapeutic gain.

Space-charge-limited currents for cathodes with electric field enhanced geometry

Energy Technology Data Exchange (ETDEWEB)

Lai, Dingguo, E-mail: laidingguo@nint.ac.cn; Qiu, Mengtong; Xu, Qifu [State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Xi' an 701124 (China); Huang, Zhongliang [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

2016-08-15

This paper presents the approximate analytic solutions of current density for annulus and circle cathodes. The current densities of annulus and circle cathodes are derived approximately from first principles, which are in agreement with simulation results. The large scaling laws can predict current densities of high current vacuum diodes including annulus and circle cathodes in practical applications. In order to discuss the relationship between current density and electric field on cathode surface, the existing analytical solutions of currents for concentric cylinder and sphere diodes are fitted from existing solutions relating with electric field enhancement factors. It is found that the space-charge-limited current density for the cathode with electric-field enhanced geometry can be written in a general form of J = g(β{sub E}){sup 2}J{sub 0}, where J{sub 0} is the classical (1D) Child-Langmuir current density, β{sub E} is the electric field enhancement factor, and g is the geometrical correction factor depending on the cathode geometry.

Field enhanced luminescence of irradiated organics due to electron tunnelling

International Nuclear Information System (INIS)

Charlesby, A.

1981-01-01

Many organic materials, following exposure to high energy radiation at low temperatures, continue to emit light for long periods. One possible mechanism is that electrons trapped near their parent cations can tunnel back over long times depending on trap depth and distance. This luminescence can be greatly enhanced by the post-radiation application of an external electric field. Calculations on the kinetics of recombination by tunnelling for various trap depths and distances are extended to allow for the effect of an electrical field subsequently applied. The quantitative results lead to two methods of assessing trap depth, depending on immediate light enhancement and on its subsequent decay. The effect of field reversal is also explained. (author)

Field strength and dose dependence of contrast enhancement by gadolinium-based MR contrast agents

International Nuclear Information System (INIS)

Rinck, P.A.; Muller, R.N.

1999-01-01

The relaxivities r 1 and r 2 of magnetic resonance contrast agents and the T 1 relaxation time values of tissues are strongly field dependent. We present quantitative data and simulations of different gadolinium-based extracellular fluid contrast agents and the modulation of their contrast enhancement by the magnetic field to be able to answer the following questions: How are the dose and field dependences of their contrast enhancement? Is there an interrelationship between dose and field dependence? Should one increase or decrease doses at specific fields? Nuclear magnetic relaxation dispersion data were acquired for the following contrast agents: gadopentetate dimeglumine, gadoterate meglumine, gadodiamide injection, and gadoteridol injection, as well as for several normal and pathological human tissue samples. The magnetic field range stretched from 0.0002 to 4.7 T, including the entire clinical imaging range. The data acquired were then fitted with the appropriate theoretical models. The combination of the diamagnetic relaxation rates (R 1 = 1/T 1 and R 2 = 1/T 2 ) of tissues with the respective paramagnetic contributions of the contrast agents allowed the prediction of image contrast at any magnetic field. The results revealed a nearly identical field and dose-dependent increase of contrast enhancement induced by these contrast agents within a certain dose range. The target tissue concentration (TTC) was an important though nonlinear factor for enhancement. The currently recommended dose of 0.1 mmol/kg body weight seems to be a compromise close to the lower limits of diagnostically sufficient contrast enhancement for clinical imaging at all field strengths. At low field contrast enhancement might be insufficient. Adjustment of dose or concentration, or a new class of contrast agents with optimized relaxivity, would be a valuable contribution to a better diagnostic yield of contrast enhancement at all fields. (orig.)

Simvastatin enhances bone morphogenetic protein receptor type II expression

International Nuclear Information System (INIS)

Hu Hong; Sung, Arthur; Zhao, Guohua; Shi, Lingfang; Qiu Daoming; Nishimura, Toshihiko; Kao, Peter N.

2006-01-01

Statins confer therapeutic benefits in systemic and pulmonary vascular diseases. Bone morphogenetic protein (BMP) receptors serve essential signaling functions in cardiovascular development and skeletal morphogenesis. Mutations in BMP receptor type II (BMPR2) are associated with human familial and idiopathic pulmonary arterial hypertension, and pathologic neointimal proliferation of vascular endothelial and smooth muscle cells within small pulmonary arteries. In severe experimental pulmonary hypertension, simvastatin reversed disease and conferred a 100% survival advantage. Here, modulation of BMPR2 gene expression by simvastatin is characterized in human embryonic kidney (HEK) 293T, pulmonary artery smooth muscle, and lung microvascular endothelial cells (HLMVECs). A 1.4 kb BMPR2 promoter containing Egr-1 binding sites confers reporter gene activation in 293T cells which is partially inhibited by simvastatin. Simvastatin enhances steady-state BMPR2 mRNA and protein expression in HLMVEC, through posttranscriptional mRNA stabilization. Simvastatin induction of BMPR2 expression may improve BMP-BMPR2 signaling thereby enhancing endothelial differentiation and function

Endogenous fields enhanced stochastic resonance in a randomly coupled neuronal network

International Nuclear Information System (INIS)

Deng, Bin; Wang, Lin; Wang, Jiang; Wei, Xi-le; Yu, Hai-tao

2014-01-01

Highlights: • We study effects of endogenous fields on stochastic resonance in a neural network. • Stochastic resonance can be notably enhanced by endogenous field feedback. • Endogenous field feedback delay plays a vital role in stochastic resonance. • The parameters of low-passed filter play a subtle role in SR. - Abstract: Endogenous field, evoked by structured neuronal network activity in vivo, is correlated with many vital neuronal processes. In this paper, the effects of endogenous fields on stochastic resonance (SR) in a randomly connected neuronal network are investigated. The network consists of excitatory and inhibitory neurons and the axonal conduction delays between neurons are also considered. Numerical results elucidate that endogenous field feedback results in more rhythmic macroscope activation of the network for proper time delay and feedback coefficient. The response of the network to the weak periodic stimulation can be notably enhanced by endogenous field feedback. Moreover, the endogenous field feedback delay plays a vital role in SR. We reveal that appropriately tuned delays of the feedback can either induce the enhancement of SR, appearing at every integer multiple of the weak input signal’s oscillation period, or the depression of SR, appearing at every integer multiple of half the weak input signal’s oscillation period for the same feedback coefficient. Interestingly, the parameters of low-passed filter which is used in obtaining the endogenous field feedback signal play a subtle role in SR

Enhancement of grain size and crystallinity of thin layers of pentacene grown under magnetic field

Energy Technology Data Exchange (ETDEWEB)

Tabata, Kenichi [Division of Materials Science, Faculty of pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Yamamoto, Yohei, E-mail: yamamoto@ims.tsukuba.ac.jp [Division of Materials Science, Faculty of pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Tsukuba Research Center for Interdisciplinary Materials Science (TIMS), Faculty of pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Center for Integrated Research in Fundamental Science and Technology (CiRfSE), University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571 (Japan)

2016-03-31

Field-effect mobilities (μ) of pentacene films, prepared by a thermal deposition under a magnetic field (H-field), were largely enhanced, in comparison with that prepared without an H-field. Under a perpendicular H-field with respect to the substrate surface, the crystallinity of the edge-on pentacene orientation is enhanced, resulting in the 9-fold enhancement of μ. Furthermore, under parallel H-field with respect to the substrate surface, μ of the pentacene films were 23-fold greater than that prepared without the H-field. The surface morphology studies by atomic force microscopy of the ultra thin films of pentacene clarified that the grain size of the pentacene at the interface with the substrate is larger for films under parallel H-field than that prepared without an H-field. The simple and effective method for enhancing the semiconducting properties of the organic thin films gives high technological impact in its application to organic electronics. - Highlights: • Magnetic-field effect on the crystallinity of pentacene thin films • Magnetic-field effect on the morphology of pentacene thin films • Enhanced field-effect charge carrier mobility of pentacene thin films.

Enhancement of grain size and crystallinity of thin layers of pentacene grown under magnetic field

International Nuclear Information System (INIS)

Tabata, Kenichi; Yamamoto, Yohei

2016-01-01

Field-effect mobilities (μ) of pentacene films, prepared by a thermal deposition under a magnetic field (H-field), were largely enhanced, in comparison with that prepared without an H-field. Under a perpendicular H-field with respect to the substrate surface, the crystallinity of the edge-on pentacene orientation is enhanced, resulting in the 9-fold enhancement of μ. Furthermore, under parallel H-field with respect to the substrate surface, μ of the pentacene films were 23-fold greater than that prepared without the H-field. The surface morphology studies by atomic force microscopy of the ultra thin films of pentacene clarified that the grain size of the pentacene at the interface with the substrate is larger for films under parallel H-field than that prepared without an H-field. The simple and effective method for enhancing the semiconducting properties of the organic thin films gives high technological impact in its application to organic electronics. - Highlights: • Magnetic-field effect on the crystallinity of pentacene thin films • Magnetic-field effect on the morphology of pentacene thin films • Enhanced field-effect charge carrier mobility of pentacene thin films

Near field plasmonic gradient effects on high vacuum tip-enhanced Raman spectroscopy.

Science.gov (United States)

Fang, Yurui; Zhang, Zhenglong; Chen, Li; Sun, Mengtao

2015-01-14

Near field gradient effects in high vacuum tip-enhanced Raman spectroscopy (HV-TERS) are a recent developing ultra-sensitive optical and spectral analysis technology on the nanoscale, based on the plasmons and plasmonic gradient enhancement in the near field and under high vacuum. HV-TERS can not only be used to detect ultra-sensitive Raman spectra enhanced by surface plasmon, but also to detect clear molecular IR-active modes enhanced by strongly plasmonic gradient. Furthermore, the molecular overtone modes and combinational modes can also be experimentally measured, where the Fermi resonance and Darling-Dennison resonance were successfully observed in HV-TERS. Theoretical calculations using electromagnetic field theory firmly supported experimental observation. The intensity ratio of the plasmon gradient term over the linear plasmon term can reach values greater than 1. Theoretical calculations also revealed that with the increase in gap distance between tip and substrate, the decrease in the plasmon gradient was more significant than the decrease in plasmon intensity, which is the reason that the gradient Raman can be only observed in the near field. Recent experimental results of near field gradient effects on HV-TERS were summarized, following the section of the theoretical analysis.

Polyproline as a Minimal Antifreeze Protein Mimic That Enhances the Cryopreservation of Cell Monolayers.

Science.gov (United States)

Graham, Ben; Bailey, Trisha L; Healey, Joseph R J; Marcellini, Moreno; Deville, Sylvain; Gibson, Matthew I

2017-12-11

Tissue engineering, gene therapy, drug screening, and emerging regenerative medicine therapies are fundamentally reliant on high-quality adherent cell culture, but current methods to cryopreserve cells in this format can give low cell yields and require large volumes of solvent "antifreezes". Herein, we report polyproline as a minimum (bio)synthetic mimic of antifreeze proteins that is accessible by solution, solid-phase, and recombinant methods. We demonstrate that polyproline has ice recrystallisation inhibition activity linked to its amphipathic helix and that it enhances the DMSO cryopreservation of adherent cell lines. Polyproline may be a versatile additive in the emerging field of macromolecular cryoprotectants. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Protein supplementation may enhance the spontaneous recovery of neurological alterations in patients with ischaemic stroke.

Science.gov (United States)

Aquilani, Roberto; Scocchi, Marco; Iadarola, Paolo; Franciscone, Piero; Verri, Manuela; Boschi, Federica; Pasini, Evasio; Viglio, Simona

2008-12-01

To determine whether protein supplementation could enhance neurological recovery in subacute patients with ischaemic stroke. Alimentation-independent patients with ischaemic stroke were randomly allocated to either 21 days of protein supplementation (protein-supplemented group; n=20) or to a spontaneous diet only (control group; n=21) in order to investigate the recovery of neurological changes (measured using the National Institute of Health (NIH) Stroke Scale). Tertiary care rehabilitation in Italy. Forty-two patients (27 male and 15 female; 66.4 +/- 11 years) 16 +/-2 days after the acute event. Supplementation with a hyperproteic nutritional formula (10% protein). NIH Stroke Scale and protein intake. At admission to rehabilitation, both groups of patients were homogeneous for demographic, clinical and functional characteristics. After 21 days from the start of the protocol, the NIH Stroke Scale was found to be enhanced in the group with supplemental proteins (-4.4 +/- 1.5 score versus -3 +/- 1.4 of control group; P<0.01). When expressed as difference (triangle up) between baseline and 21 days, the NIH Stroke Scale correlated negatively with change in protein intake (g/day) (r=-0.50, P= 0.001) and positively with change in carbohydrate/protein ratio (r = +0.40, P=0.01) Protein supplementation may enhance neurological recovery in subacute patients with ischaemic stroke.

The ITO-capped WO3 nanowires biosensor based on field-effect transistor in label-free protein sensing

International Nuclear Information System (INIS)

Shariati, Mohsen

2017-01-01

The fabrication of ITO-capped WO 3 nanowires associated with their bio-sensing properties in field-effect transistor diagnostics basis as a biosensor has been reported. The bio-sensing property for manipulated nanowires elucidated that the grown nanostructures were very sensitive to protein. The ITO-capped WO 3 nanowires biosensor showed an intensive bio-sensing activity against reliable protein. Polylysine strongly charged bio-molecule was applied as model system to demonstrate the implementation of materialized biosensor. The employed sensing mechanism was 'label-free' and depended on bio-molecule's intrinsic charge. For nanowires synthesis, the vapor-liquid-solid mechanism was used. Nanowires were beyond a few hundred nanometers in lengths and around 15-20 nm in diameter, while the globe cap's size on the nanowires was around 15-25 nm. The indium tin oxide (ITO) played as catalyst in nanofabrication for WO 3 nanowires growth and had outstanding role in bio-sensing especially for bio-molecule adherence. In applied electric field presence, the fabricated device showed the great potential to enhance medical diagnostics. (orig.)

Giant Magnetic Field Enhancement in Hybridized MIM Structures

KAUST Repository

Alrasheed, Salma; Di Fabrizio, Enzo M.

2017-01-01

We propose numerically an approach to narrow the plasmon linewidth and enhance the magnetic near field intensity at a magnetic hot spot in a hybridized metal-insulatormetal (MIM) structure. First we insert in part of the dielectric layer of the MIM

Refractive index dependent local electric field enhancement in cylindrical gold nanohole

International Nuclear Information System (INIS)

Zhu Jian

2011-01-01

We report on the local electric field characters in a long cylindrical gold nanohole. Theoretical calculation results based on quasi-static model show that the local environmental dielectric constant dependent electric field intensity and field distribution in the gold nanohole show quite unique properties, different from those in the thin gold nanotube. Because of the thick gold wall, no plasmon hybridization exists. So there is only one resonance frequency taking place, and the intense local field has been focused into the gold nanohole. Our main finding is that, the local field in the nanohole is largely dependent on the inner hole refractive index and outer environmental refractive index. The competition between inner hole and outer polarization leads to a non-monotonic change of the local field intensity with increasing the dielectric constant of the nanohole. This refractive index controlled local field enhancement in cylindrical gold nanohole presents a potential for tunable surface-enhanced fluorescence and novel nano-optical biosensing applications.

Anti-oxidant, anti-inflammatory and immunomodulating properties of an enzymatic protein hydrolysate from yellow field pea seeds.

Science.gov (United States)

Ndiaye, Fatou; Vuong, Tri; Duarte, Jairo; Aluko, Rotimi E; Matar, Chantal

2012-02-01

Enzymatic protein hydrolysates of yellow pea seed have been shown to possess high anti-oxidant and anti-bacterial activities. The aim of this work was to confirm the anti-oxidant, anti-inflammatory and immunomodulating activities of an enzymatic protein hydrolysate of yellow field pea seeds. The anti-oxidant and anti-inflammatory properties of peptides from yellow field pea proteins (Pisum sativum L.) were investigated in LPS/IFN-γ-activated RAW 264.7 NO⁻ macrophages. The immunomodulating potential of pea protein hydrolysate (PPH) was then studied in a murine model. Pea protein hydrolysate, after a 12 h pre-treatment, showed significant inhibition of NO production by activated macrophages up to 20%. Moreover, PPH significantly inhibited their secretion of pro-inflammatory cytokines, TNF-α- and IL-6, up to 35 and 80%, respectively. Oral administration of PPH in mice enhanced the phagocytic activity of their peritoneal macrophages and stimulated the gut mucosa immune response. The number of IgA+ cells was elevated in the small intestine lamina propria, accompanied by an increase in the number of IL-4+, IL-10+ and IFN-γ+ cells. This was correlated to up-regulation of IL-6 secretion by small intestine epithelial cells (IEC), probably responsible for B-cell terminal differentiation to IgA-secreting cells. Moreover, PPH might have increased IL-6 production in IECs via the stimulation of toll-like receptors (TLRs) family, especially TLR2 and TLR4 since either anti-TLR2 or anti-TLR4 was able to completely abolish PPH-induced IL-6 secretion. Enzymatic protein degradation confers anti-oxidant, anti-inflammatory and immunomodulating potentials to pea proteins, and the resulted peptides could be used as an alternative therapy for the prevention of inflammatory-related diseases.

Gold nanoparticles enhance the X-ray-induced degradation of human centrin 2 protein

International Nuclear Information System (INIS)

Brun, Emilie; Duchambon, Patricia; Blouquit, Yves; Keller, Gerard; Sanche, Leon; Sicard-Roselli, Cecile

2009-01-01

In the war against cancer, radiotherapy is a prominent tool but counterbalanced by the fact that it also induces damages in healthy tissues. Nanotechnologies could open a new possibility to decrease these side effects. In particular, gold nanoparticles (GNPs) could be used as radio-sensitizers. As the role of proteins in the processes leading to cell death cannot be neglected, their radio-sensitization by GNPs is of great interest. This is particularly true in the case of the human centrin 2 protein, which has been proposed to be involved in DNA repair processes. To investigate this effect, we quantified for the first time the degradation of this protein in a gold colloidal solution when submitted to X-rays. We showed that the X-ray-induced degradation of the human centrin 2 protein is enhanced 1.5-fold in the presence of GNPs, even though no covalent bond exists between protein and GNPs. Among the conditions tested, the maximum enhancement was found with the higher GNP:protein ratio of 2x10 -4 and with the higher X-ray energy of 49 keV

Spatial and Angular Resolution Enhancement of Light Fields Using Convolutional Neural Networks

Science.gov (United States)

Gul, M. Shahzeb Khan; Gunturk, Bahadir K.

2018-05-01

Light field imaging extends the traditional photography by capturing both spatial and angular distribution of light, which enables new capabilities, including post-capture refocusing, post-capture aperture control, and depth estimation from a single shot. Micro-lens array (MLA) based light field cameras offer a cost-effective approach to capture light field. A major drawback of MLA based light field cameras is low spatial resolution, which is due to the fact that a single image sensor is shared to capture both spatial and angular information. In this paper, we present a learning based light field enhancement approach. Both spatial and angular resolution of captured light field is enhanced using convolutional neural networks. The proposed method is tested with real light field data captured with a Lytro light field camera, clearly demonstrating spatial and angular resolution improvement.

Communication: Multiple atomistic force fields in a single enhanced sampling simulation

Energy Technology Data Exchange (ETDEWEB)

Hoang Viet, Man [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202 (United States); Derreumaux, Philippe, E-mail: philippe.derreumaux@ibpc.fr [Laboratoire de Biochimie Théorique, UPR 9080, CNRS, Université Denis Diderot, Sorbonne Paris Cité IBPC, 13 rue Pierre et Marie Curie, 75005 Paris (France); Institut Universitaire de France, 103 Bvd Saint-Germain, 75005 Paris (France); Nguyen, Phuong H., E-mail: phuong.nguyen@ibpc.fr [Laboratoire de Biochimie Théorique, UPR 9080, CNRS, Université Denis Diderot, Sorbonne Paris Cité IBPC, 13 rue Pierre et Marie Curie, 75005 Paris (France)

2015-07-14

The main concerns of biomolecular dynamics simulations are the convergence of the conformational sampling and the dependence of the results on the force fields. While the first issue can be addressed by employing enhanced sampling techniques such as simulated tempering or replica exchange molecular dynamics, repeating these simulations with different force fields is very time consuming. Here, we propose an automatic method that includes different force fields into a single advanced sampling simulation. Conformational sampling using three all-atom force fields is enhanced by simulated tempering and by formulating the weight parameters of the simulated tempering method in terms of the energy fluctuations, the system is able to perform random walk in both temperature and force field spaces. The method is first demonstrated on a 1D system and then validated by the folding of the 10-residue chignolin peptide in explicit water.

Enhanced microcontact printing of proteins on nanoporous silica surface

Energy Technology Data Exchange (ETDEWEB)

Blinka, Ellen; Hu Ye; Gopal, Ashwini; Hoshino, Kazunori; Lin, Kevin; Zhang, John X J [Department of Biomedical Engineering, University of Texas at Austin, Austin, TX 78758 (United States); Loeffler, Kathryn; Liu Xuewu; Ferrari, Mauro, E-mail: John.Zhang@engr.utexas.edu [Department of Nanomedicine and Biomedical Engineering, University of Texas Health Science Service, Houston, TX 77031 (United States)

2010-10-15

We demonstrate porous silica surface modification, combined with microcontact printing, as an effective method for enhanced protein patterning and adsorption on arbitrary surfaces. Compared to conventional chemical treatments, this approach offers scalability and long-term device stability without requiring complex chemical activation. Two chemical surface treatments using functionalization with the commonly used 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde (GA) were compared with the nanoporous silica surface on the basis of protein adsorption. The deposited thickness and uniformity of porous silica films were evaluated for fluorescein isothiocyanate (FITC)-labeled rabbit immunoglobulin G (R-IgG) protein printed onto the substrates via patterned polydimethlysiloxane (PDMS) stamps. A more complete transfer of proteins was observed on porous silica substrates compared to chemically functionalized substrates. A comparison of different pore sizes (4-6 nm) and porous silica thicknesses (96-200 nm) indicates that porous silica with 4 nm diameter, 57% porosity and a thickness of 96 nm provided a suitable environment for complete transfer of R-IgG proteins. Both fluorescence microscopy and atomic force microscopy (AFM) were used for protein layer characterizations. A porous silica layer is biocompatible, providing a favorable transfer medium with minimal damage to the proteins. A patterned immunoassay microchip was developed to demonstrate the retained protein function after printing on nanoporous surfaces, which enables printable and robust immunoassay detection for point-of-care applications.

Enhancement of nucleation during hanging drop protein crystallization using HF treatment of cover glasses

Energy Technology Data Exchange (ETDEWEB)

Guo, Yun-Zhu; Yin, Da-Chuan; Lu, Qin-Qin; Wang, Xi-Kai; Liu, Jun [Key Laboratory for Space Bioscience and Biotechnology, Faculty of Life Sciences, Northwestern Polytechnical University, Xi' an 710072, Shaanxi (China)

2010-02-15

We examined a simple approach, i.e., etching cover glasses using hydrofluoric acid (HF), to determine whether cover glass treatment enhances nucleation in hanging drop protein crystallization. Hen egg white lysozyme and proteinase K were used as the model proteins. We found that the treatment increased the success rate of crystallization. The results indicated that the simple treatment, which is easy to adopt without changing much in the hanging drop method, can be utilized as an alternative method to enhance protein crystallization screens (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Protein-x of hepatitis B virus in interaction with CCAAT/enhancer-binding protein α (C/EBPα - an in silico analysis approach

Directory of Open Access Journals (Sweden)

Mohamadkhani Ashraf

2011-10-01

Full Text Available Abstract Background Even though many functions of protein-x from the Hepatitis B virus (HBV have been revealed, the nature of protein-x is yet unknown. This protein is well-known for its transactivation activity through interaction with several cellular transcription factors, it is also known as an oncogene. In this work, we have presented computational approaches to design a model to show the structure of protein-x and its respective binding sites associated with the CCAAT/enhancer-binding protein α (C/EBPα. C/EBPα belongs to the bZip family of transcription factors, which activates transcription of several genes through its binding sites in liver and fat cells. The C/EBPα has been shown to bind and modulate enhancer I and the enhancer II/core promoter of HBV. In this study using the bioinformatics tools we tried to present a reliable model for the protein-x interaction with C/EBPα. Results The amino acid sequence of protein-x was extracted from UniProt [UniProt:Q80IU5] and the x-ray crystal structure of the partial CCAAT-enhancer α [PDB:1NWQ] was retrieved from the Protein Data Bank (PDB. Similarity search for protein-x was carried out by psi-blast and bl2seq using NCBI [GenBank: BAC65106.1] and Local Meta-Threading-Server (LOMETS was used as a threading server for determining the maximum tertiary structure similarities. Advanced MODELLER was implemented to design a comparative model, however, due to the lack of a suitable template, Quark was used for ab initio tertiary structure prediction. The PDB-blast search indicated a maximum of 23% sequence identity and 33% similarity with crystal structure of the porcine reproductive and respiratory syndrome virus leader protease Nsp1α [PDB:3IFU]. This meant that protein-x does not have a suitable template to predict its tertiary structure using comparative modeling tools, therefore we used QUARK as an ab initio 3D prediction approach. Docking results from the ab initio tertiary structure of

High order harmonic generation in noble gases using plasmonic field enhancement

International Nuclear Information System (INIS)

Ciappina, Marcelo F.; Shaaran, Tahir; Lewenstein, Maciej

2013-01-01

Theoretical studies of high-order harmonic generation (HHG) in rare gases driven by plasmonic field enhancement are presented. This kind of fields appears when plasmonic nanostructures are illuminated by an intense few-cycle laser and have a particular spatial dependency, depending on the geometrical shape of the nanostructure. It is demonstrated that the strong nonhomogeneous character of the laser enhanced field plays an important role in the HHG process and significantly extends the harmonic cutoff. The models are based on numerical solution of the time dependent Schroedinger equation (TDSE) and supported by classical and semiclassical calculations. (copyright 2012 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Malting process optimization for protein digestibility enhancement in finger millet grain.

Science.gov (United States)

Hejazi, Sara Najdi; Orsat, Valérie

2016-04-01

Finger millet (Eleusine coracana) is a nutritious, gluten-free, and drought resistant cereal containing high amounts of protein, carbohydrate, and minerals. However, bio-availability of these nutrients is restricted due to the presence of an excessive level of anti-nutrient components, mainly phytic acid, tannin, and oxalate. It has been shown that a well-designed malting/germination process can significantly reduce these anti-nutrients and consequently enhance the nutrient availability. In the present study, the effects of two important germination factors, duration and temperature, on the enhancement of in-vitro protein digestibility of finger millet were thoroughly investigated and optimized. Based on a central composite design, the grains were germinated for 24, 36, and 48 h at 22, 26, and 30 °C. For all factor combinations, protein, peptide, phytic acid, tannin, and oxalate contents were evaluated and digestibility was assessed. It was shown that during the malting/germinating process, both temperature and duration factors significantly influenced the investigated quantities. Germination of finger millet for 48 h at 30 °C increased protein digestibility from 74 % (for native grain) up to 91 %. Besides, it notably decreased phytic acid, tannin, and oxalate contents by 45 %, 46 %, and 29 %, respectively. Linear correlations between protein digestibility and these anti-nutrients were observed.

Finite Element Method Simulations of the Near-Field Enhancement at the Vicinity of Fractal Rough Metallic Surfaces

International Nuclear Information System (INIS)

Micic, Miodrag; Klymyshyn, Nicholas A.; Lu, H Peter

2004-01-01

Near-field optical enhancement at metal surfaces and methods such as surface plasmon resonance (SPR), surface-enhanced Raman scattering (SERS), fluorescent quenching and enhancement, and various near-field scanning microscopies (NSOM) all depend on a metals surface properties, mainly on its morphology and SPR resonant frequency. We report on simulations of the influence of different surface morphologies on electromagnetic field enhancements at the rough surfaces of noble metals and also evaluate the optimal conditions for the generation of a surface-enhanced Raman signal of absorbed species on a metallic substrate. All simulations were performed with a classical electrodynamics approach using the full set of Maxwells equations, which were solved with the three-dimensional finite element method (FEM). Two different classes of surfaces where modeled using fractals, representing diffusion limited aggregation growth dendritic structures, such as one on the surface of electrodes, and second one representing the sponge-like structure used to model surfaces of particles with high porosity, such as metal coated catalyst supports. The simulations depict the high inhomogeneity of an enhanced electromagnetic field as both a field enhancement and field attenuation near the surface. While the diffusion limited aggregation dendritical fractals enhanced the near-field electromagnetic field, the sponge fractals significantly reduced the local electromagnetic field intensity. Moreover, the fractal orders of the fractal objects did not significantly alter the total enhancement, and the distribution of a near-field enhancement was essentially invariant to the changes in the angle of an incoming laser beam

Heat shock protein 90 (Hsp90) chaperone complex. A molecular target for enhancement of thermosensitivity and radiosensitivity

International Nuclear Information System (INIS)

Akimoto, Tetsuo; Nonaka, Tetsuo; Kitamoto, Yoshizumi; Sakurai, Hideyuki

2002-01-01

Heat shock protein 90 (Hsp90) is a highly conserved heat shock protein in animal and plants, and exists abundantly in the cytoplasm in unstressed condition, accounting for 1-2% in cytoplasmic proteins. Main difference of Hsp90 from other Hsps are its substrate that Hsp90 binds to. These substrates include various signal transduction proteins, kinase, steroid receptors and transcription factors, therefore, Hsp90 plays a key role in maintaining cellular signal transduction networks. Many chaperoned proteins (client proteins) of Hsp90 are associated with cellular proliferation or malignant transformation, thus Hsp90 chaperone complex has been focused as targets for cancer therapy. Among the client proteins, there are several molecules that have been defined as targets or factors for determination or enhancement of radiosensitivity or thermosensitivity. Thus, it is easily speculated that Hsp90 chaperone complex inhibitors that disrupt association of Hsp90 and client protein in combination with radiation or/and heat has potential effect on enhancement of radiosensitivity or thermosensitivity. In this paper, possible mechanisms in enhancing radiosensitivity or thermosensitivity according to the client proteins will be summarized. (author)

Enhanced SUMOylation of proteins containing a SUMO-interacting motif by SUMO-Ubc9 fusion

International Nuclear Information System (INIS)

Kim, Eui Tae; Kim, Kyeong Kyu; Matunis, Mike J.; Ahn, Jin-Hyun

2009-01-01

Identifying new targets for SUMO and understanding the function of protein SUMOylation are largely limited by low level of SUMOylation. It was found recently that Ubc9, the SUMO E2 conjugating enzyme, is covalently modified by SUMO at a lysine 14 in the N-terminal alpha helix, and that SUMO-modified Ubc9 has enhanced conjugation activity for certain target proteins containing a SUMO-interacting motif (SIM). Here, we show that, compared to intact Ubc9, the SUMO-Ubc9 fusion protein has higher conjugating activity for SIM-containing targets such as Sp100 and human cytomegalovirus IE2. Assays using an IE2 SIM mutant revealed the requirement of SIM for the enhanced IE2 SUMOylation by SUMO-Ubc9. In pull-down assays with cell extracts, the SUMO-Ubc9 fusion protein bound to more diverse cellular proteins and interacted with some SIM-containing proteins with higher affinities than Ubc9. Therefore, the devised SUMO-Ubc9 fusion will be useful for identifying SIM-containing SUMO targets and producing SUMO-modified proteins.

Protein profiles of field isolates ofBacillus anthracis from different endemic areas of Indonesia

Directory of Open Access Journals (Sweden)

M Bhakti Poerwadikarta

1998-03-01

Full Text Available Sonicated cell-free extract proteins of 14 field isolates ofBacillus anthracis from six different endemic areas of Indonesia were analyzed by the use of sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE methods . The protein profiles of each field isolate tested demonstrated slightly different at the protein bands with molecular weights of 18, 37, 52, 65 and 70 kDa, and varied between the field isolates and vaccine strains. The variation could provide clues to the source of anthrax transmission whether it was originated from similar strain or not.

The ITO-capped WO{sub 3} nanowires biosensor based on field-effect transistor in label-free protein sensing

Energy Technology Data Exchange (ETDEWEB)

Shariati, Mohsen [Sharif University of Technology, Institute for Nanoscience and Nanotechnology, Tehran (Iran, Islamic Republic of)

2017-05-15

The fabrication of ITO-capped WO{sub 3} nanowires associated with their bio-sensing properties in field-effect transistor diagnostics basis as a biosensor has been reported. The bio-sensing property for manipulated nanowires elucidated that the grown nanostructures were very sensitive to protein. The ITO-capped WO{sub 3} nanowires biosensor showed an intensive bio-sensing activity against reliable protein. Polylysine strongly charged bio-molecule was applied as model system to demonstrate the implementation of materialized biosensor. The employed sensing mechanism was 'label-free' and depended on bio-molecule's intrinsic charge. For nanowires synthesis, the vapor-liquid-solid mechanism was used. Nanowires were beyond a few hundred nanometers in lengths and around 15-20 nm in diameter, while the globe cap's size on the nanowires was around 15-25 nm. The indium tin oxide (ITO) played as catalyst in nanofabrication for WO{sub 3} nanowires growth and had outstanding role in bio-sensing especially for bio-molecule adherence. In applied electric field presence, the fabricated device showed the great potential to enhance medical diagnostics. (orig.)

Enhancing Field Research Methods with Mobile Survey Technology

Science.gov (United States)

Glass, Michael R.

2015-01-01

This paper assesses the experience of undergraduate students using mobile devices and a commercial application, iSurvey, to conduct a neighborhood survey. Mobile devices offer benefits for enhancing student learning and engagement. This field exercise created the opportunity for classroom discussions on the practicalities of urban research, the…

Enhanced vulnerability of human proteins towards disease-associated inactivation through divergent evolution.

Science.gov (United States)

Medina-Carmona, Encarnación; Fuchs, Julian E; Gavira, Jose A; Mesa-Torres, Noel; Neira, Jose L; Salido, Eduardo; Palomino-Morales, Rogelio; Burgos, Miguel; Timson, David J; Pey, Angel L

2017-09-15

Human proteins are vulnerable towards disease-associated single amino acid replacements affecting protein stability and function. Interestingly, a few studies have shown that consensus amino acids from mammals or vertebrates can enhance protein stability when incorporated into human proteins. Here, we investigate yet unexplored relationships between the high vulnerability of human proteins towards disease-associated inactivation and recent evolutionary site-specific divergence of stabilizing amino acids. Using phylogenetic, structural and experimental analyses, we show that divergence from the consensus amino acids at several sites during mammalian evolution has caused local protein destabilization in two human proteins linked to disease: cancer-associated NQO1 and alanine:glyoxylate aminotransferase, mutated in primary hyperoxaluria type I. We demonstrate that a single consensus mutation (H80R) acts as a disease suppressor on the most common cancer-associated polymorphism in NQO1 (P187S). The H80R mutation reactivates P187S by enhancing FAD binding affinity through local and dynamic stabilization of its binding site. Furthermore, we show how a second suppressor mutation (E247Q) cooperates with H80R in protecting the P187S polymorphism towards inactivation through long-range allosteric communication within the structural ensemble of the protein. Our results support that recent divergence of consensus amino acids may have occurred with neutral effects on many functional and regulatory traits of wild-type human proteins. However, divergence at certain sites may have increased the propensity of some human proteins towards inactivation due to disease-associated mutations and polymorphisms. Consensus mutations also emerge as a potential strategy to identify structural hot-spots in proteins as targets for pharmacological rescue in loss-of-function genetic diseases. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please

Electromagnetic field enhancement and spectrum shaping through plasmonically integrated optical vortices.

Science.gov (United States)

Ahn, Wonmi; Boriskina, Svetlana V; Hong, Yan; Reinhard, Björn M

2012-01-11

We introduce a new design approach for surface-enhanced Raman spectroscopy (SERS) substrates that is based on molding the optical powerflow through a sequence of coupled nanoscale optical vortices "pinned" to rationally designed plasmonic nanostructures, referred to as Vortex Nanogear Transmissions (VNTs). We fabricated VNTs composed of Au nanodiscs by electron beam lithography on quartz substrates and characterized their near- and far-field responses through combination of computational electromagnetism, and elastic and inelastic scattering spectroscopy. Pronounced dips in the far-field scattering spectra of VNTs provide experimental evidence for an efficient light trapping and circulation within the nanostructures. Furthermore, we demonstrate that VNT integration into periodic arrays of Au nanoparticles facilitates the generation of high E-field enhancements in the VNTs at multiple defined wavelengths. We show that spectrum shaping in nested VNT structures is achieved through an electromagnetic feed-mechanism driven by the coherent multiple scattering in the plasmonic arrays and that this process can be rationally controlled by tuning the array period. The ability to generate high E-field enhancements at predefined locations and frequencies makes nested VNTs interesting substrates for challenging SERS applications. © 2011 American Chemical Society

Gold nanoparticles enhance the X-ray-induced degradation of human centrin 2 protein

Energy Technology Data Exchange (ETDEWEB)

Brun, Emilie [Laboratoire de Chimie Physique, CNRS UMR 8000, Universite Paris-Sud 11, Bat. 350, 91405 Orsay Cedex (France); Duchambon, Patricia; Blouquit, Yves [INSERM U759, Imagerie Integrative, Campus Universitaire d' Orsay, Bat. 112, Institut Curie, Centre de Recherche, Laboratoire R. Latarjet, Campus Universitaire d' Orsay, 91405 Orsay Cedex (France); Keller, Gerard [UMR CNRS 8612, Physico-Chimie-Pharmacotechnie-Biopharmacie, Universite Paris 11, Faculte de Pharmacie, 5 rue Jean-Baptiste Clement, 92296 Chatenay-Malabry (France); Sanche, Leon [Groupe en Sciences des Radiations, Departement de Medecine Nucleaire et Radiobiologie, Faculte de Medecine, Universite de Sherbrooke, Sherbrooke, Quebec, Canada J1H 5N4 (Canada); Sicard-Roselli, Cecile [Laboratoire de Chimie Physique, CNRS UMR 8000, Universite Paris-Sud 11, Bat. 350, 91405 Orsay Cedex (France)], E-mail: cecile.sicard@u-psud.fr

2009-03-15

In the war against cancer, radiotherapy is a prominent tool but counterbalanced by the fact that it also induces damages in healthy tissues. Nanotechnologies could open a new possibility to decrease these side effects. In particular, gold nanoparticles (GNPs) could be used as radio-sensitizers. As the role of proteins in the processes leading to cell death cannot be neglected, their radio-sensitization by GNPs is of great interest. This is particularly true in the case of the human centrin 2 protein, which has been proposed to be involved in DNA repair processes. To investigate this effect, we quantified for the first time the degradation of this protein in a gold colloidal solution when submitted to X-rays. We showed that the X-ray-induced degradation of the human centrin 2 protein is enhanced 1.5-fold in the presence of GNPs, even though no covalent bond exists between protein and GNPs. Among the conditions tested, the maximum enhancement was found with the higher GNP:protein ratio of 2x10{sup -4} and with the higher X-ray energy of 49 keV.

Leucine pulses enhance skeletal muscle protein synthesis during continuous feeding in neonatal pigs

Science.gov (United States)

Infants unable to maintain oral feeding can be nourished by orogastric tube. We have shown that orogastric continuous feeding restricts muscle protein synthesis compared with intermittent bolus feeding in neonatal pigs. To determine whether leucine leu infusion can be used to enhance protein synthes...

Engineering signal peptides for enhanced protein secretion from Lactococcus lactis.

Science.gov (United States)

Ng, Daphne T W; Sarkar, Casim A

2013-01-01

Lactococcus lactis is an attractive vehicle for biotechnological production of proteins and clinical delivery of therapeutics. In many such applications using this host, it is desirable to maximize secretion of recombinant proteins into the extracellular space, which is typically achieved by using the native signal peptide from a major secreted lactococcal protein, Usp45. In order to further increase protein secretion from L. lactis, inherent limitations of the Usp45 signal peptide (Usp45sp) must be elucidated. Here, we performed extensive mutagenesis on Usp45sp to probe the effects of both the mRNA sequence (silent mutations) and the peptide sequence (amino acid substitutions) on secretion. We screened signal peptides based on their resulting secretion levels of Staphylococcus aureus nuclease and further evaluated them for secretion of Bacillus subtilis α-amylase. Silent mutations alone gave an increase of up to 16% in the secretion of α-amylase through a mechanism consistent with relaxed mRNA folding around the ribosome binding site and enhanced translation. Targeted amino acid mutagenesis in Usp45sp, combined with additional silent mutations from the best clone in the initial screen, yielded an increase of up to 51% in maximum secretion of α-amylase while maintaining secretion at lower induction levels. The best sequence from our screen preserves the tripartite structure of the native signal peptide but increases the positive charge of the n-region. Our study presents the first example of an engineered L. lactis signal peptide with a higher secretion yield than Usp45sp and, more generally, provides strategies for further enhancing protein secretion in bacterial hosts.

In situ detection of a heat-shock regulatory element binding protein using a soluble short synthetic enhancer sequence

Energy Technology Data Exchange (ETDEWEB)

Harel-Bellan, A; Brini, A T; Farrar, W L [National Cancer Institute, Frederick, MD (USA); Ferris, D K [Program Resources, Inc., Frederick, MD (USA); Robin, P [Institut Gustave Roussy, Villejuif (France)

1989-06-12

In various studies, enhancer binding proteins have been successfully absorbed out by competing sequences inserted into plasmids, resulting in the inhibition of the plasmid expression. Theoretically, such a result could be achieved using synthetic enhancer sequences not inserted into plasmids. In this study, a double stranded DNA sequence corresponding to the human heat shock regulatory element was chemically synthesized. By in vitro retardation assays, the synthetic sequence was shown to bind specifically a protein in extracts from the human T cell line Jurkat. When the synthetic enhancer was electroporated into Jurkat cells, not only the enhancer was shown to remain undegraded into the cells for up to 2 days, but also its was shown to bind intracellularly a protein. The binding was specific and was modulated upon heat shock. Furthermore, the binding protein was shown to be of the expected molecular weight by UV crosslinking. However, when the synthetic enhancer element was co-electroporated with an HSP 70-CAT reporter construct, the expression of the reporter plasmid was consistently enhanced in the presence of the exogenous synthetic enhancer.

Effect of canning on color, protein and phenolic profile of grains from kidney bean, field pea and chickpea.

Science.gov (United States)

Parmar, Naincy; Singh, Narpinder; Kaur, Amritpal; Virdi, Amardeep Singh; Thakur, Sheetal

2016-11-01

The aim of the present study was to evaluate the effect of canning on color, protein and phenolic profile of grains of kidney bean, field pea and chickpea varieties/accession. Color of grains of different pulses was enhanced after canning. Grains L* (lightness) decreased while a* (redness to yellowness) and b* (greenness to blueness) increased after canning in all the pulses. Protein profiling of grains of different pulses after canning revealed that kidney bean and chickpea, respectively, had the least and the most thermally susceptible polypeptides. Kidney bean and chickpea showed higher Percentage washed drained weight (PWDW) than field pea. Pulse with more grain hardness and PWDW showed higher degree of grain splitting during canning. Grain splitting was also higher in dark colored accessions/varieties as compared to the light colored. Ferulic acid was the most predominant compound present in raw grains of different pulses. Raw kidney bean grains showed higher accumulation of catechin, chlorogenic, protocatechuic acid, p-coumaric acid and ferulic acid than those of chickpea and field pea. Canning caused reduction in all the phenolic compounds except gallic acid and most prominent effect of canning on protocatechuic acid, chlorogenic and ferulic acid was observed. Copyright © 2016. Published by Elsevier Ltd.

Intracellular cholesterol-binding proteins enhance HDL-mediated cholesterol uptake in cultured primary mouse hepatocytes.

Science.gov (United States)

Storey, Stephen M; McIntosh, Avery L; Huang, Huan; Landrock, Kerstin K; Martin, Gregory G; Landrock, Danilo; Payne, H Ross; Atshaves, Barbara P; Kier, Ann B; Schroeder, Friedhelm

2012-04-15

A major gap in our knowledge of rapid hepatic HDL cholesterol clearance is the role of key intracellular factors that influence this process. Although the reverse cholesterol transport pathway targets HDL to the liver for net elimination of free cholesterol from the body, molecular details governing cholesterol uptake into hepatocytes are not completely understood. Therefore, the effects of sterol carrier protein (SCP)-2 and liver fatty acid-binding protein (L-FABP), high-affinity cholesterol-binding proteins present in hepatocyte cytosol, on HDL-mediated free cholesterol uptake were examined using gene-targeted mouse models, cultured primary hepatocytes, and 22-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-amino]-23,24-bisnor-5-cholen-3β-ol (NBD-cholesterol). While SCP-2 overexpression enhanced NBD-cholesterol uptake, counterintuitively, SCP-2/SCP-x gene ablation also 1) enhanced the rapid molecular phase of free sterol uptake detectable in rate and maximal uptake of HDL free cholesterol and 2) differentially enhanced free cholesterol uptake mediated by the HDL3, rather than the HDL2, subfraction. The increased HDL free cholesterol uptake was not due to increased expression or distribution of the HDL receptor [scavenger receptor B1 (SRB1)], proteins regulating SRB1 [postsynaptic density protein (PSD-95)/Drosophila disk large tumor suppressor (dlg)/tight junction protein (ZO1) and 17-kDa membrane-associated protein], or other intracellular cholesterol trafficking proteins (steroidogenic acute response protein D, Niemann Pick C, and oxysterol-binding protein-related proteins). However, expression of L-FABP, the single most prevalent hepatic cytosolic protein that binds cholesterol, was upregulated twofold in SCP-2/SCP-x null hepatocytes. Double-immunogold electron microscopy detected L-FABP sufficiently close to SRB1 for direct interaction, similar to SCP-2. These data suggest a role for L-FABP in HDL cholesterol uptake, a finding confirmed with SCP-2/SCP-x/L-FABP null

Labelling strategies for enhanced application of ICPMS in protein analysis

International Nuclear Information System (INIS)

Bettmer, J.; Kutscher, D.J.

2009-01-01

Full text: Quantitative protein analysis is one of today's challenges in analytical chemistry. Herein, mass spectrometric techniques play an important role with the use of both label-free and labelling approaches. In the field of ICPMS, the latter approach is attractive as it can provide highly sensitive detection of proteins after labelling with metal-containing compounds. Following a brief introduction to the different strategies described in the literature, this presentation will be focussed on protein labelling using a mercury compound (p-hydroxymercuribenzoic acid, pHMB). Besides fundamental studies on the derivatization process itself, a strategy will be presented in which absolute protein quantification can be achieved. Finally, the potential, but also limitations of the technique will be highlighted. (author)

Two-photon mapping of localized field enhancements in thin nanostrip antennas

DEFF Research Database (Denmark)

Beermann, I.; Novikov, S.M.; Søndergaard, Thomas

2008-01-01

scanning optical microscopy, in which two-photon-excited photoluminescence (TPL) excited with a strongly focused laser beam at the wavelength 745 nm is detected. We use TPL images to map the local field enhancements from individual nanostrips at a resolution of 0.35µm and compare results with theoretical......Resonant scattering and local field enhancements by 11-nm-thin gold nanostrip antennas due to constructive interference of counter propagating slow surface plasmon polaritons is investigated. We characterize nanostrips of widths between 50-530 nm using both reflection spectroscopy and nonlinear...

Enhancement of intermediate-field two-photon absorption by rationally shaped femtosecond pulses

International Nuclear Information System (INIS)

Chuntonov, Lev; Rybak, Leonid; Gandman, Andrey; Amitay, Zohar

2008-01-01

We extend the powerful frequency-domain analysis of femtosecond two-photon absorption to the intermediate-field regime of considerable absorption yields, where additionally to the weak-field nonresonant two-photon transitions also four-photon transitions play a role. Consequently, we rationally find that the absorption is enhanced over the transform-limited pulse by any shaped pulse having a spectral phase that is antisymmetric around one-half of the transition frequency and a spectrum that is asymmetric around it (red or blue detuned according to the system). The enhancement increases as the field strength increases. The theoretical results for Na are verified experimentally

Hydrophobicity-driven self-assembly of protein and silver nanoparticles for protein detection using surface-enhanced Raman scattering.

Science.gov (United States)

Kahraman, Mehmet; Balz, Ben N; Wachsmann-Hogiu, Sebastian

2013-05-21

Surface-enhanced Raman scattering (SERS) is a promising analytical technique for the detection and characterization of biological molecules and structures. The role of hydrophobic and hydrophilic surfaces in the self-assembly of protein-metallic nanoparticle structures for label-free protein detection is demonstrated. Aggregation is driven by both the hydrophobicity of the surface as well as the charge of the proteins. The best conditions for obtaining a reproducible SERS signal that allows for sensitive, label-free protein detection are provided by the use of hydrophobic surfaces and 16 × 10(11) NPs per mL. A detection limit of approximately 0.5 μg mL(-1) is achieved regardless of the proteins' charge properties and size. The developed method is simple and can be used for reproducible and sensitive detection and characterization of a wide variety of biological molecules and various structures with different sizes and charge status.

High-order-harmonic generation from H2+ molecular ions near plasmon-enhanced laser fields

Science.gov (United States)

Yavuz, I.; Tikman, Y.; Altun, Z.

2015-08-01

Simulations of plasmon-enhanced high-order-harmonic generation are performed for a H2+ molecular cation near the metallic nanostructures. We employ the numerical solution of the time-dependent Schrödinger equation in reduced coordinates. We assume that the main axis of H2+ is aligned perfectly with the polarization direction of the plasmon-enhanced field. We perform systematic calculations on plasmon-enhanced harmonic generation based on an infinite-mass approximation, i.e., pausing nuclear vibrations. Our simulations show that molecular high-order-harmonic generation from plasmon-enhanced laser fields is possible. We observe the dispersion of a plateau of harmonics when the laser field is plasmon enhanced. We find that the maximum kinetic energy of the returning electron follows 4 Up . We also find that when nuclear vibrations are enabled, the efficiency of the harmonics is greatly enhanced relative to that of static nuclei. However, the maximum kinetic energy 4 Up is largely maintained.

Enhancement of germination, growth, and photosynthesis in soybean by pre-treatment of seeds with magnetic field.

Science.gov (United States)

Shine, M B; Guruprasad, K N; Anand, Anjali

2011-09-01

Experiments were conducted to study the effect of static magnetic fields on the seeds of soybean (Glycine max (L.) Merr. var: JS-335) by exposing the seeds to different magnetic field strengths from 0 to 300 mT in steps of 50 mT for 30, 60, and 90 min. Treatment with magnetic fields improved germination-related parameters like water uptake, speed of germination, seedling length, fresh weight, dry weight and vigor indices of soybean seeds under laboratory conditions. Improvement over untreated control was 5-42% for speed of germination, 4-73% for seedling length, 9-53% for fresh weight, 5-16% for dry weight, and 3-88% and 4-27% for vigor indices I and II, respectively. Treatment of 200 mT (60 min) and 150 mT (60 min), which were more effective than others in increasing most of the seedling parameters, were further explored for their effect on plant growth, leaf photosynthetic efficiency, and leaf protein content under field conditions. Among different growth parameters, leaf area, and leaf fresh weight showed maximum enhancement (more than twofold) in 1-month-old plants. Polyphasic chlorophyll a fluorescence (OJIP) transients from magnetically treated plants gave a higher fluorescence yield at the J-I-P phase. The total soluble protein map (SDS-polyacrylamide gel) of leaves showed increased intensities of the bands corresponding to a larger subunit (53 KDa) and smaller subunit (14 KDa) of Rubisco in the treated plants. We report here the beneficial effect of pre-sowing magnetic treatment for improving germination parameters and biomass accumulation in soybean. Copyright © 2011 Wiley-Liss, Inc.

Enhanced protein retention on poly(caprolactone) via surface initiated polymerization of acrylamide

International Nuclear Information System (INIS)

Ma, Yuhao; Cai, Mengtan; He, Liu; Luo, Xianglin

2016-01-01

Graphical abstract: - Highlights: • Dense package of poly(acrylamide) on poly(caprolactone) surface was achieved by surface-initiated atom transfer radical polymerization. • Poly(acrylamide) grafted surface exhibited high protein retention ability. • Loaded protein was resistant to detachment and maintained its structure without denaturation. - Abstract: To enhance the biocompatibility or extend the biomedical application of poly(caprolactone) (PCL), protein retention on PCL surface is often required. In this study, poly(acrylamide) (PAAm) brushes were grown from PCL surface via surface-initiated atom transfer radical polymerization (SI-ATRP) and served as a protein-capturing platform. Grafted PAAm was densely packed on surface and exhibited superior protein retention ability. Captured protein was found to be resistant to washing under detergent environment. Furthermore, protein structure after being captured was investigated by circular dichroism (CD) spectroscopy, and the CD spectra verified that secondary structure of captured proteins was maintained, indicating no denaturation of protein happened for retention process.

HDR Pathological Image Enhancement Based on Improved Bias Field Correction and Guided Image Filter

Directory of Open Access Journals (Sweden)

Qingjiao Sun

2016-01-01

Full Text Available Pathological image enhancement is a significant topic in the field of pathological image processing. This paper proposes a high dynamic range (HDR pathological image enhancement method based on improved bias field correction and guided image filter (GIF. Firstly, a preprocessing including stain normalization and wavelet denoising is performed for Haematoxylin and Eosin (H and E stained pathological image. Then, an improved bias field correction model is developed to enhance the influence of light for high-frequency part in image and correct the intensity inhomogeneity and detail discontinuity of image. Next, HDR pathological image is generated based on least square method using low dynamic range (LDR image, H and E channel images. Finally, the fine enhanced image is acquired after the detail enhancement process. Experiments with 140 pathological images demonstrate the performance advantages of our proposed method as compared with related work.

Phonon-assisted field emission in silicon nanomembranes for time-of-flight mass spectrometry of proteins.

Science.gov (United States)

Park, Jonghoo; Aksamija, Zlatan; Shin, Hyun-Cheol; Kim, Hyunseok; Blick, Robert H

2013-06-12

Time-of-flight (TOF) mass spectrometry has been considered as the method of choice for mass analysis of large intact biomolecules, which are ionized in low charge states by matrix-assisted-laser-desorption/ionization (MALDI). However, it remains predominantly restricted to the mass analysis of biomolecules with a mass below about 50,000 Da. This limitation mainly stems from the fact that the sensitivity of the standard detectors decreases with increasing ion mass. We describe here a new principle for ion detection in TOF mass spectrometry, which is based upon suspended silicon nanomembranes. Impinging ion packets on one side of the suspended silicon nanomembrane generate nonequilibrium phonons, which propagate quasi-diffusively and deliver thermal energy to electrons within the silicon nanomembrane. This enhances electron emission from the nanomembrane surface with an electric field applied to it. The nonequilibrium phonon-assisted field emission in the suspended nanomembrane connected to an effective cooling of the nanomembrane via field emission allows mass analysis of megadalton ions with high mass resolution at room temperature. The high resolution of the detector will give better insight into high mass proteins and their functions.

Site-directed antibody immobilization using a protein A-gold binding domain fusion protein for enhanced SPR immunosensing.

Science.gov (United States)

de Juan-Franco, Elena; Caruz, Antonio; Pedrajas, J R; Lechuga, Laura M

2013-04-07

We have implemented a novel strategy for the oriented immobilization of antibodies onto a gold surface based on the use of a fusion protein, the protein A-gold binding domain (PAG). PAG consists of a gold binding peptide (GBP) coupled to the immunoglobulin-binding domains of staphylococcal protein A. This fusion protein provides an easy and fast oriented immobilization of antibodies preserving its native structure, while leaving the antigen binding sites (Fab) freely exposed. Using this immobilization strategy, we have demonstrated the performance of the immunosensing of the human Growth Hormone by SPR. A limit of detection of 90 ng mL(-1) was obtained with an inter-chip variability lower than 7%. The comparison of this method with other strategies for the direct immobilization of antibodies over gold surfaces has showed the enhanced sensitivity provided by the PAG approach.

Enhanced field emission properties of tilted graphene nanoribbons on aggregated TiO{sub 2} nanotube arrays

Energy Technology Data Exchange (ETDEWEB)

Hung, Shang-Chao, E-mail: schung99@gmail.com [Department of Information Technology & Communication, Shih Chien University Kaohsiung Campus, Neimen, Kaohsiung 845, Taiwan (China); Chen, Yu-Jyun [Graduate Institute of Electro-Optical Engineering & Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China)

2016-07-15

Highlights: • Graphene nanoribbons (GNBs) slanted on aggregate TiO{sub 2} nanotube (A-TNTs) as field-emitters. • Turn-on electric field and field enhancement factor β are dependent on the substrate morphology. • Various quantities of GNRs are deposited on top of A-TNTs (GNRs/A-TNTs) with different morphologies. • With an increase of GNBs compositions, the specimens' turn-on electric field is reduced to 2.8 V/μm. • The field enhancement factor increased rapidly to about 1964 with the addition of GNRs. - Abstract: Graphene nanoribbons (GNRs) slanted on aggregate TiO{sub 2} nanotube arrays (A-TNTs) with various compositions as field-emitters are reported. The morphology, crystalline structure, and composition of the as-obtained specimens were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and Raman spectrometry. The dependence of the turn-on electric field and the field enhancement factor β on substrate morphology was studied. An increase of GNRs reduces the specimens’ turn-on electric field to 2.8 V/μm and the field enhancement factor increased rapidly to about 1964 with the addition of GNRs. Results show a strong dependence of the field emission on GNR composition aligned with the gradient on the top of the A-TNT substrate. Enhanced FE properties of the modified TNTs can be mainly attributed to their improved electrical properties and rougher surface morphology.

Microscopic model of the THz field enhancement in a metal nanoslit

DEFF Research Database (Denmark)

Novitsky, Andrey; Zalkovskij, Maksim; Malureanu, Radu

2011-01-01

We discuss the strong THz-field enhancement effect in a metal slit of dozens of nanometers sizes reported recently. Proposed simple microscopic model considers electric charges induced at the edges of the slit by a polarized incident wave. These charges contribute then to the field in the slit...

Modeling of Local Magnetic Field Enhancements within Solar Flux Ropes

OpenAIRE

Romashets, E; Vandas, M; Poedts, Stefaan

2010-01-01

To model and study local magnetic-field enhancements in a solar flux rope we consider the magnetic field in its interior as a superposition of two linear (constant alpha) force-free magnetic-field distributions, viz. a global one, which is locally similar to a part of the cylinder, and a local torus-shaped magnetic distribution. The newly derived solution for a toroid with an aspect ratio close to unity is applied. The symmetry axis of the toroid and that of the cylinder may or may not coinci...

Cyclin B1 Destruction Box-Mediated Protein Instability: The Enhanced Sensitivity of Fluorescent-Protein-Based Reporter Gene System

Directory of Open Access Journals (Sweden)

Chao-Hsun Yang

2013-01-01

Full Text Available The periodic expression and destruction of several cyclins are the most important steps for the exact regulation of cell cycle. Cyclins are degraded by the ubiquitin-proteasome system during cell cycle. Besides, a short sequence near the N-terminal of cyclin B called the destruction box (D-box; CDB is also required. Fluorescent-protein-based reporter gene system is insensitive to analysis because of the overly stable fluorescent proteins. Therefore, in this study, we use human CDB fused with both enhanced green fluorescent protein (EGFP at C-terminus and red fluorescent protein (RFP, DsRed at N-terminus in the transfected human melanoma cells to examine the effects of CDB on different fluorescent proteins. Our results indicated that CDB-fused fluorescent protein can be used to examine the slight gene regulations in the reporter gene system and have the potential to be the system for screening of functional compounds in the future.

Global enhancement and structure formation of the magnetic field in spiral galaxies

Science.gov (United States)

Khoperskov, Sergey A.; Khrapov, Sergey S.

2018-01-01

In this paper we study numerically large-scale magnetic field evolution and its enhancement in gaseous disks of spiral galaxies. We consider a set of models with the various spiral pattern parameters and the initial magnetic field strength with taking into account gas self-gravity and cooling and heating processes. In agreement with previous studies we find out that galactic magnetic field is mostly aligned with gaseous structures, however small-scale gaseous structures (spurs and clumps) are more chaotic than the magnetic field structure. In spiral arms magnetic field often coexists with the gas distribution, in the inter-arm region we see filamentary magnetic field structure. These filaments connect several isolated gaseous clumps. Simulations reveal the presence of the small-scale irregularities of the magnetic field as well as the reversal of magnetic field at the outer edge of the large-scale spurs. We provide evidences that the magnetic field in the spiral arms has a stronger mean-field component, and there is a clear inverse correlation between gas density and plasma-beta parameter, compared to the rest of the disk with a more turbulent component of the field and an absence of correlation between gas density and plasma-beta. We show the mean field growth up to >3-10 μG in the cold gas during several rotation periods (>500-800 Myr), whereas ratio between azimuthal and radial field is equal to >4/1. We find an enhancement of random and ordered components of the magnetic field. Mean field strength increases by a factor of >1.5-2.5 for models with various spiral pattern parameters. Random magnetic field component can reach up to 25% from the total strength. By making an analysis of the time-dependent evolution of the radial Poynting flux, we point out that the magnetic field strength is enhanced more strongly at the galactic outskirts which is due to the radial transfer of magnetic energy by the spiral arms pushing the magnetic field outward. Our results also

Maltose-binding protein enhances secretion of recombinant human granzyme B accompanied by in vivo processing of a precursor MBP fusion protein.

Directory of Open Access Journals (Sweden)

Benjamin Dälken

Full Text Available BACKGROUND: The apoptosis-inducing serine protease granzyme B (GrB is an important factor contributing to lysis of target cells by cytotoxic lymphocytes. Expression of enzymatically active GrB in recombinant form is a prerequisite for functional analysis and application of GrB for therapeutic purposes. METHODS AND FINDINGS: We investigated the influence of bacterial maltose-binding protein (MBP fused to GrB via a synthetic furin recognition motif on the expression of the MBP fusion protein also containing an N-terminal α-factor signal peptide in the yeast Pichia pastoris. MBP markedly enhanced the amount of GrB secreted into culture supernatant, which was not the case when GrB was fused to GST. MBP-GrB fusion protein was cleaved during secretion by an endogenous furin-like proteolytic activity in vivo, liberating enzymatically active GrB without the need of subsequent in vitro processing. Similar results were obtained upon expression of a recombinant fragment of the ErbB2/HER2 receptor protein or GST as MBP fusions. CONCLUSIONS: Our results demonstrate that combination of MBP as a solubility enhancer with specific in vivo cleavage augments secretion of processed and functionally active proteins from yeast. This strategy may be generally applicable to improve folding and increase yields of recombinant proteins.

Maltose-Binding Protein Enhances Secretion of Recombinant Human Granzyme B Accompanied by In Vivo Processing of a Precursor MBP Fusion Protein

Science.gov (United States)

Dälken, Benjamin; Jabulowsky, Robert A.; Oberoi, Pranav; Benhar, Itai; Wels, Winfried S.

2010-01-01

Background The apoptosis-inducing serine protease granzyme B (GrB) is an important factor contributing to lysis of target cells by cytotoxic lymphocytes. Expression of enzymatically active GrB in recombinant form is a prerequisite for functional analysis and application of GrB for therapeutic purposes. Methods and Findings We investigated the influence of bacterial maltose-binding protein (MBP) fused to GrB via a synthetic furin recognition motif on the expression of the MBP fusion protein also containing an N-terminal α-factor signal peptide in the yeast Pichia pastoris. MBP markedly enhanced the amount of GrB secreted into culture supernatant, which was not the case when GrB was fused to GST. MBP-GrB fusion protein was cleaved during secretion by an endogenous furin-like proteolytic activity in vivo, liberating enzymatically active GrB without the need of subsequent in vitro processing. Similar results were obtained upon expression of a recombinant fragment of the ErbB2/HER2 receptor protein or GST as MBP fusions. Conclusions Our results demonstrate that combination of MBP as a solubility enhancer with specific in vivo cleavage augments secretion of processed and functionally active proteins from yeast. This strategy may be generally applicable to improve folding and increase yields of recombinant proteins. PMID:21203542

Improved means and methods for expressing recombinant proteins

NARCIS (Netherlands)

Poolman, Berend; Martinez Linares, Daniel; Gul, Nadia

2014-01-01

The invention relates to the field of genetic engineering and the production of recombinant proteins in microbial host cells. Provided is a method for enhanced expression of a recombinant protein of interest in a microbial host cell, comprising providing a microbial host cell wherein the function of

Field redevelopment optimization to unlock reserves and enhance production

Directory of Open Access Journals (Sweden)

AHMED AL-HASHAMI

2013-09-01

Full Text Available A cluster area "H" consists of 4 carbonate gas fields producing dry gas from N-A reservoir in the Northern area of Oman. These fields are producing with different maturity levels since 1968. An FDP (Field Development Plan study was done in 2006 which proposed drilling of 7 additional vertical wells beside the already existing 5 wells to develop the reserves and enhance gas production from the fields. The FDP well planning was based on a seismic amplitude "Qualitative Interpretation (QI" study that recommended drilling the areas with high amplitudes as an indication for gas presence, and it ignored the low amplitude areas even if it is structurally high. A follow up study was conducted in 2010 for "H" area fields using the same seismic data and the well data drilled post FDP. The new static and dynamic work revealed the wrong aspect of the 2006 QI study, and proved with evidence from well logs and production data that low seismic amplitudes in high structural areas have sweet spots of good reservoir quality rock. This has led to changing the old appraisal strategy and planning more wells in low amplitude areas with high structure and hence discovering new blocks that increased the reserves of the fields.Furthermore, water production in these fields started much earlier than FDP expectation. The subsurface team have integrated deeply with the operation team and started a project to find new solutions to handle the water production and enhance the gas rate. The subsurface team also started drilling horizontal wells in the fields to increase the UR, delay the water production and also reduce the wells total CAPEX by drilling less horizontal wells compared to many vertical as they have higher production and recovery. These subsurface and surface activities have successfully helped to stabilize and increase the production of "H" area cluster by developing more reserves and handling the water production.

Identification of milk proteins enhancing the antimicrobial activity of lactoferrin and lactoferricin.

Science.gov (United States)

Murata, M; Wakabayashi, H; Yamauchi, K; Abe, F

2013-08-01

Lactoferrin (LF) is known as an iron-binding antimicrobial protein present in exocrine secretions such as milk and releases the potent antimicrobial peptide lactoferricin (LFcin) by hydrolysis with pepsin. The antimicrobial activity of LF and LFcin has been studied well; however, their cooperative action with other milk proteins remains to be elucidated. In this study, we identified milk proteins enhancing the antimicrobial activity of bovine LF and LFcin against gram-negative bacteria, gram-positive bacteria, and fungi. As the target fraction, we isolated a minor milk protein fraction around 15 kDa, which was identified as bovine RNase 5 (angiogenin-1), RNase 4, and angiogenin-2 by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry. As these proteins are collectively known as the RNase A family, we referred to the target protein fraction as milk RNase of 15 kDa (MR15). The number of colony-forming units of Escherichia coli and other pathogenic microorganisms with the addition of MR15 to LF (MR15:LF ratio=16:1,000) was dramatically lowered than that with LF alone. On the other hand, MR15 itself did not show any reductions in the number of colony-forming units at the concentrations tested. Similarly, the antimicrobial activities of LFcin against various microorganisms were significantly enhanced by the addition of MR15. These results suggest that LF and MR15 may be concomitantly acting antimicrobial agents in milk. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Terahertz Near-Field Imaging Using Enhanced Transmission through a Single Subwavelength Aperture

Science.gov (United States)

Ishihara, Kunihiko; Ikari, Tomofumi; Minamide, Hiroaki; Shikata, Jun-ichi; Ohashi, Keishi; Yokoyama, Hiroyuki; Ito, Hiromasa

2005-07-01

We demonstrate terahertz (THz) near-field imaging using resonantly enhanced transmission of THz-wave radiation (λ˜ 200 μm) through a bull’s eye structure (a single subwavelength aperture surrounded by concentric periodic grooves in a metal plate). The bull’s eye structure shows extremely large enhanced transmission, which has the advantage for a single subwavelength aperture. The spatial resolution for the bull’s eye structure (with an aperture diameter d=100 μm) is evaluated in the near-field region, and a resolution of 50 μm (corresponding to λ/4) is achieved. We obtain the THz near-field images of the subwavelength metal pattern with a spatial resolution below the diffraction limit.

Gold nanoparticle assisted assembly of a heme protein for enhancement of long-range interfacial electron transfer

DEFF Research Database (Denmark)

Jensen, Palle Skovhus; Chi, Qijin; Grumsen, Flemming Bjerg

2007-01-01

and characterization of water-soluble gold nanoparticles (AuNPs) with core diameter 3-4 nm and their application for the enhancement of long-range interfacial ET of a heme protein. Gold nanoparticles were electrostatically conjugated with cyt c to form nanoparticle-protein hybrid ET systems with well...... and the protein molecule. When the nanoparticle-protein conjugates are assembled on Au(111) surfaces, long-range interfacial ET across a physical distance of over 50 A via the nanoparticle becomes feasible. Moreover, significant enhancement of the interfacial ET rate by more than an order of magnitude compared...... with that of cyt c in the absence of AuNPs is observed. AuNPs appear to serve as excellent ET relays, most likely by facilitating the electronic coupling between the protein redox center and the electrode surface....

Nitrile Probes of Electric Field Agree with Independently Measured Fields in Green Fluorescent Protein Even in the Presence of Hydrogen Bonding.

Science.gov (United States)

Slocum, Joshua D; Webb, Lauren J

2016-05-25

There is growing interest in using the nitrile vibrational oscillation as a site-specific probe of local environment to study dynamics, folding, and electrostatics in biological molecules such as proteins. Nitrile probes have been used extensively as reporters of electric field using vibrational Stark effect spectroscopy. However, the analysis of frequencies in terms of electric fields is potentially complicated by the large ground state dipole moment of the nitrile, which may irrevocably perturb the protein under investigation, and the ability of nitriles to accept hydrogen bonds, which causes frequency shifts that are not described by the Stark effect. The consequence of this is that vibrational spectroscopy of nitriles in biomolecules could be predominately sensitive to their local hydration status, not electrostatic environment, and have the potential to be particularly destabilizing to the protein. Here, we introduce green fluorescent protein (GFP) as a model system for addressing these concerns using biosynthetically incorporated p-cyanophenylalanine (pCNF) residues in the interior of GFP and measuring absorption energies of both the intrinsic GFP fluorophore and pCNF residues in response to a series of amino acid mutations. We show that observed changes in emission energy of GFP due to the mutations strongly correlate with changes in electric field experienced by both the nitrile probes and the intrinsic fluorophore. Additionally, we show that changes in electric field measured from the intrinsic fluorophore due to amino acid mutations are unperturbed by the addition of pCNF residues inserted nearby. Finally, we show that changes in electric field experienced by the vibrational probes trend monotonically with changes in field experienced by the native fluorophore even though the nitrile probe is engaged in moderate hydrogen bonding to nearby water molecules, indicated by the temperature dependence of the nitrile's absorption energy. Together these results

A chalcone isomerase-like protein enhances flavonoid production and flower pigmentation.

Science.gov (United States)

Morita, Yasumasa; Takagi, Kyoko; Fukuchi-Mizutani, Masako; Ishiguro, Kanako; Tanaka, Yoshikazu; Nitasaka, Eiji; Nakayama, Masayoshi; Saito, Norio; Kagami, Takashi; Hoshino, Atsushi; Iida, Shigeru

2014-04-01

Flavonoids are major pigments in plants, and their biosynthetic pathway is one of the best-studied metabolic pathways. Here we have identified three mutations within a gene that result in pale-colored flowers in the Japanese morning glory (Ipomoea nil). As the mutations lead to a reduction of the colorless flavonoid compound flavonol as well as of anthocyanins in the flower petal, the identified gene was designated enhancer of flavonoid production (EFP). EFP encodes a chalcone isomerase (CHI)-related protein classified as a type IV CHI protein. CHI is the second committed enzyme of the flavonoid biosynthetic pathway, but type IV CHI proteins are thought to lack CHI enzymatic activity, and their functions remain unknown. The spatio-temporal expression of EFP and structural genes encoding enzymes that produce flavonoids is very similar. Expression of both EFP and the structural genes is coordinately promoted by genes encoding R2R3-MYB and WD40 family proteins. The EFP gene is widely distributed in land plants, and RNAi knockdown mutants of the EFP homologs in petunia (Petunia hybrida) and torenia (Torenia hybrida) had pale-colored flowers and low amounts of anthocyanins. The flavonol and flavone contents in the knockdown petunia and torenia flowers, respectively, were also significantly decreased, suggesting that the EFP protein contributes in early step(s) of the flavonoid biosynthetic pathway to ensure production of flavonoid compounds. From these results, we conclude that EFP is an enhancer of flavonoid production and flower pigmentation, and its function is conserved among diverse land plant species. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.

Expression of endogenous proteins in maize hybrids in a multi-location field trial in India.

Science.gov (United States)

Gutha, Linga R; Purushottam, Divakar; Veeramachaneni, Aruna; Tigulla, Sarita; Kodappully, Vikas; Enjala, Chandana; Rajput, Hitendrasinh; Anderson, Jennifer; Hong, Bonnie; Schmidt, Jean; Bagga, Shveta

2018-05-17

Genetically modified (GM) crops undergo large scale multi-location field trials to characterize agronomics, composition, and the concentration of newly expressed protein(s) [herein referred to as transgenic protein(s)]. The concentration of transgenic proteins in different plant tissues and across the developmental stages of the plant is considered in the safety assessment of GM crops. Reference or housekeeping proteins are expected to maintain a relatively stable expression pattern in healthy plants given their role in cellular functions. Understanding the effects of genotype, growth stage and location on the concentration of endogenous housekeeping proteins may provide insight into the contribution these factors could have on transgenic protein concentrations in GM crops. The concentrations of three endogenous proteins (actin, elongation factor 1-alpha, and glyceraldehyde 3-phosphate dehydrogenase) were measured in several different maize hybrids grown across multiple field locations over 2 years. Leaf samples were collected from healthy plants at three developmental stages across the growing seasons, and protein concentrations were quantified by indirect enzyme-linked immunosorbent assay (ELISA) for each protein. In general, the concentrations of these three endogenous proteins were relatively consistent across hybrid backgrounds, when compared within one growth stage and location (2-26%CV), whereas the concentrations of proteins in the same hybrid and growth stage across different locations were more variable (12-64%CV). In general, the protein concentrations in 2013 and 2014 show similar trends in variability. Some degree of variability in protein concentrations should be expected for both transgenic and endogenous plant-expressed proteins. In the case of GM crops, the potential variation in protein concentrations due to location effects is captured in the current model of multi-location field testing.

Induction of heat shock-like proteins in Vigna sinensis seedlings growing under ultraviolet-B (280-320 nm) enhanced radiation

International Nuclear Information System (INIS)

Nedunchezhian, N.; Annamalainathan, K.; Kulandaivelu, G.

1992-01-01

The effect of ultraviolet-B (UV-B) enhanced fluorescent radiation on protein profile and protein synthesis has been investigated in Vigna sinensis L. cv. Walp seedlings growing at various temperatures. In seedlings growing at 30°C, UV-B radiation decreased the level of several proteins as seen in Coomassie brilliant blue stained gel. However, fluorography of the same gel indicates induction of three sets of proteins in the range of 70. 53 and 16 k Da. Such induction under UV-B enhanced radiation resembled that found after heat shock treatments. In seedlings at 10 and 20°C, induction of such proteins varied both qualitatively and quantitatively. At 40°C. UV-B enhanced radiation caused a cumulative effect with temperature. Strong induction of specific proteins by UV-B radiation in seedlings growing under normal temperature indicates a possible protective role

Electrohydrodynamic fibrillation governed enhanced thermal transport in dielectric colloids under a field stimulus.

Science.gov (United States)

Dhar, Purbarun; Maganti, Lakshmi Sirisha; Harikrishnan, A R

2018-05-30

Electrorheological (ER) fluids are known to exhibit enhanced viscous effects under an electric field stimulus. The present article reports the hitherto unreported phenomenon of greatly enhanced thermal conductivity in such electro-active colloidal dispersions in the presence of an externally applied electric field. Typical ER fluids are synthesized employing dielectric fluids and nanoparticles and experiments are performed employing an in-house designed setup. Greatly augmented thermal conductivity under a field's influence was observed. Enhanced thermal conduction along the fibril structures under the field effect is theorized as the crux of the mechanism. The formation of fibril structures has also been experimentally verified employing microscopy. Based on classical models for ER fluids, a mathematical formalism has been developed to predict the propensity of chain formation and statistically feasible chain dynamics at given Mason numbers. Further, a thermal resistance network model is employed to computationally predict the enhanced thermal conduction across the fibrillary colloid microstructure. Good agreement between the mathematical model and the experimental observations is achieved. The domineering role of thermal conductivity over relative permittivity has been shown by proposing a modified Hashin-Shtrikman (HS) formalism. The findings have implications towards better physical understanding and design of ER fluids from both 'smart' viscoelastic as well as thermally active materials points of view.

Differential tissue expression of enhanced green fluorescent protein in ‘Green mice’

OpenAIRE

Ma, De-Fu; Tezuka, Hideo; Kondo, Tetsuo; Sudo, Katsuko; Niu, Dong-Feng; Nakazawa, Tadao; Kawasaki, Tomonori; Yamane, Tetsu; Nakamura, Nobuki; Katoh, Ryohei

2010-01-01

In order to clarify tissue expression of enhanced green fluorescent protein (EGFP) in ‘green mice’ from a transgenic line having an EGFP cDNA under the control of a chicken beta-actin promoter and cytomegalovirus enhancer, we studied the expression of EGFP in various organs and tissues from these ‘green mice’ by immunohistochemistry with anti- EGFP antibody in conjunction with direct observation for EGFP fluorescence using confocal laser scanning microscopy. On i...

Are current atomistic force fields accurate enough to study proteins in crowded environments?

Directory of Open Access Journals (Sweden)

Drazen Petrov

2014-05-01

Full Text Available The high concentration of macromolecules in the crowded cellular interior influences different thermodynamic and kinetic properties of proteins, including their structural stabilities, intermolecular binding affinities and enzymatic rates. Moreover, various structural biology methods, such as NMR or different spectroscopies, typically involve samples with relatively high protein concentration. Due to large sampling requirements, however, the accuracy of classical molecular dynamics (MD simulations in capturing protein behavior at high concentration still remains largely untested. Here, we use explicit-solvent MD simulations and a total of 6.4 µs of simulated time to study wild-type (folded and oxidatively damaged (unfolded forms of villin headpiece at 6 mM and 9.2 mM protein concentration. We first perform an exhaustive set of simulations with multiple protein molecules in the simulation box using GROMOS 45a3 and 54a7 force fields together with different types of electrostatics treatment and solution ionic strengths. Surprisingly, the two villin headpiece variants exhibit similar aggregation behavior, despite the fact that their estimated aggregation propensities markedly differ. Importantly, regardless of the simulation protocol applied, wild-type villin headpiece consistently aggregates even under conditions at which it is experimentally known to be soluble. We demonstrate that aggregation is accompanied by a large decrease in the total potential energy, with not only hydrophobic, but also polar residues and backbone contributing substantially. The same effect is directly observed for two other major atomistic force fields (AMBER99SB-ILDN and CHARMM22-CMAP as well as indirectly shown for additional two (AMBER94, OPLS-AAL, and is possibly due to a general overestimation of the potential energy of protein-protein interactions at the expense of water-water and water-protein interactions. Overall, our results suggest that current MD force fields

Tip-enhanced near-field Raman spectroscopy with a scanning tunneling microscope and side-illumination optics.

Science.gov (United States)

Yi, K J; He, X N; Zhou, Y S; Xiong, W; Lu, Y F

2008-07-01

Conventional Raman spectroscopy (RS) suffers from low spatial resolution and low detection sensitivity due to the optical diffraction limit and small interaction cross sections. It has been reported that a highly localized and significantly enhanced electromagnetic field could be generated in the proximity of a metallic tip illuminated by a laser beam. In this study, a tip-enhanced RS system was developed to both improve the resolution and enhance the detection sensitivity using the tip-enhanced near-field effects. This instrument, by combining RS with a scanning tunneling microscope and side-illumination optics, demonstrated significant enhancement on both optical sensitivity and spatial resolution using either silver (Ag)-coated tungsten (W) tips or gold (Au) tips. The sensitivity improvement was verified by observing the enhancement effects on silicon (Si) substrates. Lateral resolution was verified to be below 100 nm by mapping Ag nanostructures. By deploying the depolarization technique, an apparent enhancement of 175% on Si substrates was achieved. Furthermore, the developed instrument features fast and reliable optical alignment, versatile sample adaptability, and effective suppression of far-field signals.

Surface-Enhanced Raman Scattering Nanoparticles as Optical Labels for Imaging Cell Surface Proteins

Science.gov (United States)

MacLaughlin, Christina M.

Assaying the expression of cell surface proteins has widespread application for characterizing cell type, developmental stage, and monitoring disease transformation. Immunophenotyping is conducted by treating cells with labelled targeting moieties that have high affinity for relevant surface protein(s). The sensitivity and specificity of immunophenotyping is defined by the choice of contrast agent and therefore, the number of resolvable signals that can be used to simultaneously label cells. Narrow band width surface-enhanced Raman scattering (SERS) nanoparticles are proposed as optical labels for multiplexed immunophenotying. Two types of surface coatings were investigated to passivate the gold nanoparticles, incorporate SERS functionality, and to facilitate attachment of targeting antibodies. Thiolated poly(ethylene glycol) forms dative bonds with the gold surface and is compatible with multiple physisorbed Raman-active reporter molecules. Ternary lipid bilayers are used to encapsulate the gold nanoparticles particles, and incorporate three different classes of Raman reporters. TEM, UV-Visible absorbance spectroscopy, DLS, and electrophoretic light scattering were used characterize the particle coating. Colourimetric protein assay, and secondary antibody labelling were used to quantify the antibody conjugation. Three different in vitromodels were used to investigate the binding efficacy and specificity of SERS labels for their biomarker targets. Primary human CLL cells, LY10 B lymphoma, and A549 adenocarcinoma lines were targeted. Dark field imaging was used to visualize the colocalization of SERS labels with cells, and evidence of receptor clustering was obtained based on colour shifts of the particles' Rayleigh scattering. Widefield, and spatially-resolved Raman spectra were used to detect labels singly, and in combination from labelled cells. Fluorescence flow cytometry was used to test the particles' binding specificity, and SERS from labelled cells was also

Comparison of membrane electroporation and protein denature in response to pulsed electric field with different durations.

Science.gov (United States)

Huang, Feiran; Fang, Zhihui; Mast, Jason; Chen, Wei

2013-05-01

In this paper, we compared the minimum potential differences in the electroporation of membrane lipid bilayers and the denaturation of membrane proteins in response to an intensive pulsed electric field with various pulse durations. Single skeletal muscle fibers were exposed to a pulsed external electric field. The field-induced changes in the membrane integrity (leakage current) and the Na channel currents were monitored to identify the minimum electric field needed to damage the membrane lipid bilayer and the membrane proteins, respectively. We found that in response to a relatively long pulsed electric shock (longer than the membrane intrinsic time constant), a lower membrane potential was needed to electroporate the cell membrane than for denaturing the membrane proteins, while for a short pulse a higher membrane potential was needed. In other words, phospholipid bilayers are more sensitive to the electric field than the membrane proteins for a long pulsed shock, while for a short pulse the proteins become more vulnerable. We can predict that for a short or ultrashort pulsed electric shock, the minimum membrane potential required to start to denature the protein functions in the cell plasma membrane is lower than that which starts to reduce the membrane integrity. Copyright © 2013 Wiley Periodicals, Inc.

Laser induced surface structuring of Cu for enhancement of field emission properties

Science.gov (United States)

Akram, Mahreen; Bashir, Shazia; Jalil, Sohail Abdul; Shahid Rafique, Muhammad; Hayat, Asma; Mahmood, Khaliq

2018-02-01

The effect of Nd:YAG (1064 nm, 10 ns, 10 Hz) laser induced surface structuring of copper (Cu) for enhancement of field emission (FE) properties has been investigated. X-ray diffraction analysis was employed to investigate the surface structural and compositional modifications. The surface structuring was explored by scanning electron microscope investigation. FE properties were studied under UHV conditions in a parallel plate configuration of planar un-irradiated Cu anode and laser irradiated Cu cathode. The Fowler-Nordheim plots were drawn to confirm the dominance of FE behavior of the measured I-V characteristics. The obtained values of turn-on field ‘E o’, field enhancement factor ‘β’ and maximum current density ‘J max’ come out to be to be in the range of 5.5-8.5 V μm-1, 1380-2730 and 147-375 μA cm-2 respectively for the Cu samples irradiated at laser irradiance ranging from 13 to 50 GW cm-2. The observed enhancement in the FE properties has been correlated with the growth of various surface structures such as ridged protrusions, cones and pores/tiny holes. The porous morphology is found to be responsible for a significant enhancement in the FE parameters.

Interleukin 17 enhances bone morphogenetic protein-2-induced ectopic bone formation

NARCIS (Netherlands)

Croes, M.; Kruyt, M. C.; Groen, W. M.; Van Dorenmalen, K. M.A.; Dhert, W. J.A.; Öner, F. C.; Alblas, J.

2018-01-01

Interleukin 17 (IL-17) stimulates the osteogenic differentiation of progenitor cells in vitro through a synergy with bone morphogenetic protein (BMP)-2. This study investigates whether the diverse responses mediated by IL-17 in vivo also lead to enhanced BMP-2-induced bone formation. Since IL-17 is

Trichinella spiralis infection enhances protein kinase C phosphorylation in guinea pig alveolar macrophages.

Science.gov (United States)

Dzik, J M; Zieliński, Z; Cieśla, J; Wałajtys-Rode, E

2010-03-01

To learn more about the signalling pathways involved in superoxide anion production in guinea pig alveolar macrophages, triggered by Trichinella spiralis infection, protein level and phosphorylation of mitogen activated protein (MAP) kinases and protein kinase C (PKC) were investigated. Infection with T. spiralis, the nematode having 'lung phase' during colonization of the host, enhances PKC phosphorylation in guinea pig alveolar macrophages. Isoenzymes beta and delta of PKC have been found significantly phosphorylated, although their location was not changed as a consequence of T. spiralis infection. Neither in macrophages from T. spiralis-infected guinea pig nor in platelet-activating factor (PAF)-stimulated macrophages from uninfected animals, participation of MAP kinases in respiratory burst activation was statistically significant. The parasite antigens seem to act through macrophage PAF receptors, transducing a signal for enhanced NADPH oxidase activity, as stimulating effect of newborn larvae homogenate on respiratory burst was abolished by specific PAF receptor antagonist CV 6209. A suppressive action of T. spiralis larvae on host alveolar macrophage innate immunological response was reflected by diminished protein level of ERK2 kinase and suppressed superoxide anion production, in spite of high level of PKC phosphorylation.

Bias-enhanced post-treatment process for enhancing the electron field emission properties of ultrananocrystalline diamond films

International Nuclear Information System (INIS)

Saravanan, A.; Huang, B. R.; Sankaran, K. J.; Tai, N. H.; Dong, C. L.; Lin, I. N.

2015-01-01

The electron field emission (EFE) properties of ultrananocrystalline diamond films were markedly improved via the bias-enhanced plasma post-treatment (bep) process. The bep-process induced the formation of hybrid-granular structure of the diamond (bep-HiD) films with abundant nano-graphitic phase along the grain boundaries that increased the conductivity of the films. Moreover, the utilization of Au-interlayer can effectively suppress the formation of resistive amorphous-carbon (a-C) layer, thereby enhancing the transport of electrons crossing the diamond-to-Si interface. Therefore, bep-HiD/Au/Si films exhibit superior EFE properties with low turn-on field of E 0  = 2.6 V/μm and large EFE current density of J e  = 3.2 mA/cm 2 (at 5.3 V/μm)

Self-Assembly of Protein Nanostructures to Enhance Biosensor Sensitivity

Science.gov (United States)

Olsen, Bradley; Dong, Xuehui; Obermeyer, Allie

The Langmuir adsorption isotherm predicts that the number of bound species on a surface at a given concentration will be directly proportional to the number of binding sites on the surface. Therefore, the number of binding events in a biosensor may be increased at a given analyte concentration if the surface density of binding domains is increased. Here, we demonstrate the formation of block copolymers where one block is a human IgG antibody or a nanobody and self-assemble these molecules into nanostructured films with a high density of binding sites. The type of nanostructure formed and the rate of transport through the protein-polymer layers are explored as a function of coil fraction of the protein-polymer conjugate block copolymers, showing optima for transport and assembly that depend upon the identity of the protein. For small enough analytes, binding to the antibodies and nanobodies is linear with film thickness, indicating that the entire film is accessible. Consistent with the enhanced number of binding sites and the prediction of the Langmuir isotherm, the films improve sensitivity by several orders of magnitude relative to chemisorbed protein layers used in current sensor designs. Current research is integrating this new material technology into prototype sensors. Work supported by the Air Force Office of Scientific Reesearch (AFOSR).

Using a silver-enhanced microarray sandwich structure to improve SERS sensitivity for protein detection.

Science.gov (United States)

Gu, Xuefang; Yan, Yuerong; Jiang, Guoqing; Adkins, Jason; Shi, Jian; Jiang, Guomin; Tian, Shu

2014-03-01

A simple and sensitive method, based on surface-enhanced Raman scattering (SERS), for immunoassay and label-free protein detection is reported. A series of bowl-shaped silver cavity arrays were fabricated by electrodeposition using a self-assembled polystyrene spheres template. The reflection spectra of these cavity arrays were recorded as a function of film thickness, and then correlated with SERS enhancement using sodium thiophenolate as the probe molecule. The results reveal that SERS enhancement can be maximized when the frequency of both the incident laser and the Raman scattering approach the frequency of the localized surface plasmon resonance. The optimized array was then used as the bottom layer of a silver nanoparticle-protein-bowl-shaped silver cavity array sandwich. The second layer of silver was introduced by the interactions between the proteins in the middle layer of the sandwich architecture and silver nanoparticles. Human IgG bound to the surface of this microcavity array can retain its recognition function. With the Raman reporter molecules labeled on the antibody, a detection limit down to 0.1 ng mL(-1) for human IgG is easily achieved. Furthermore, the SERS spectra of label-free proteins (catalase, cytochrome C, avidin and lysozyme) from the assembled sandwich have excellent reproducibility and high quality. The results reveal that the proposed approach has potential for use in qualitative and quantitative detection of biomolecules.

Thermal and Field Enhanced Photoemission Comparison of Theory to Experiment

CERN Document Server

Lynn-Jensen, Kevin

2004-01-01

Photocathodes are a critical component of high-gain FEL’s and the analysis of their emission is complex. Relating their performance under laboratory conditions to conditions of an rf photoinjector is difficult. Useful models must account for cathode surface conditions and material properties, as well as drive laser parameters. We have developed a time-dependent model accounting for the effects of laser heating and thermal propagation on photoemission. It accounts for surface conditions (coating, field enhancement, reflectivity), laser parameters (duration, intensity, wavelength), and material characteristics (reflectivity, laser penetration depth, scattering rates) to predict current distribution and quantum efficiency. The applicatIon will focus on photoemission from metals and, in particular, dispenser photocathodes: the later introduces complications such as coverage non-uniformity and field enhancement. The performance of experimentally characterized photocathodes will be extrapolated to 0.1 - 1 nC bunch...

Enhancement of the Performance of a Transfer Field Electric ...

African Journals Online (AJOL)

This paper reports the enhancement of the output power and power factor of a transfer field machine operating in the asynchronous mode by direct capacitance injection into the auxiliary winding of the machine, which is electrically isolated from the main winding but magnetically coupled to it. It is shown that by proper ...

Attention directed by expectations enhances receptive fields in cortical area MT.

Science.gov (United States)

Ghose, Geoffrey M; Bearl, David W

2010-02-22

Expectations, especially those formed on the basis of extensive training, can substantially enhance visual performance. However, it is not clear that the physiological mechanisms underlying this enhancement are identical to those examined by experiments in which attention is directed by explicit instructions rather than strong expectations. To study the changes in visual representations associated with strong expectations, we trained animals to detect a brief motion pulse that was embedded in noise. Because the nature of the pulse and the statistics of its appearance were well known to the animals, they formed strong expectations which determined their behavioral performance. We used white-noise methods to infer the receptive field structure of single neurons in area MT while they were performing this task. Incorporating non-linearities, we compared receptive fields during periods of time when the animals were expecting the motion pulse with periods of time when they were not. We found receptive field changes consistent with an increased reliability in signaling pulse occurrence. Moreover, these changes were not consistent with a simple gain modulation. The results suggest that strong expectations can create very specific changes in the visual representations at a cellular level to enhance performance. Copyright 2009 Elsevier Ltd. All rights reserved.

Laser ablation of polymer coatings allows for electromagnetic field enhancement mapping around nanostructures

DEFF Research Database (Denmark)

Fiutowski, Jacek; Maibohm, Christian; Kjelstrup-Hansen, Jakob

2011-01-01

Subdiffraction spatially resolved, quantitative mapping of strongly localized field intensity enhancement on gold nanostructures via laser ablation of polymer thin films is reported. Illumination using a femtosecond laser scanning microscope excites surface plasmons in the nanostructures....... The accompanying field enhancement substantially lowers the ablation threshold of the polymer film and thus creates local ablation spots and corresponding topographic modifications of the polymer film. Such modifications are quantified straightforwardly via scanning electron microscopy and atomic force microscopy...

Severe Weather Field Experience: An Undergraduate Field Course on Career Enhancement and Severe Convective Storms

Science.gov (United States)

Godfrey, Christopher M.; Barrett, Bradford S.; Godfrey, Elaine S.

2011-01-01

Undergraduate students acquire a deeper understanding of scientific principles through first-hand experience. To enhance the learning environment for atmospheric science majors, the University of North Carolina at Asheville has developed the severe weather field experience. Participants travel to Tornado Alley in the Great Plains to forecast and…

Enhanced transconductance in a double-gate graphene field-effect transistor

Science.gov (United States)

Hwang, Byeong-Woon; Yeom, Hye-In; Kim, Daewon; Kim, Choong-Ki; Lee, Dongil; Choi, Yang-Kyu

2018-03-01

Multi-gate transistors, such as double-gate, tri-gate and gate-all-around transistors are the most advanced Si transistor structure today. Here, a genuine double-gate transistor with a graphene channel is experimentally demonstrated. The top and bottom gates of the double-gate graphene field-effect transistor (DG GFET) are electrically connected so that the conductivity of the graphene channel can be modulated simultaneously by both the top and bottom gate. A single-gate graphene field-effect transistor (SG GFET) with only the top gate is also fabricated as a control device. For systematical analysis, the transfer characteristics of both GFETs were measured and compared. Whereas the maximum transconductance of the SG GFET was 17.1 μS/μm, that of the DG GFET was 25.7 μS/μm, which is approximately a 50% enhancement. The enhancement of the transconductance was reproduced and comprehensively explained by a physics-based compact model for GFETs. The investigation of the enhanced transfer characteristics of the DG GFET in this work shows the possibility of a multi-gate architecture for high-performance graphene transistor technology.

Hibiscus chlorotic ringspot virus coat protein upregulates sulfur metabolism genes for enhanced pathogen defense.

Science.gov (United States)

Gao, Ruimin; Ng, Florence Kai Lin; Liu, Peng; Wong, Sek-Man

2012-12-01

In both Hibiscus chlorotic ringspot virus (HCRSV)-infected and HCRSV coat protein (CP) agroinfiltrated plant leaves, we showed that sulfur metabolism pathway related genes-namely, sulfite oxidase (SO), sulfite reductase, and adenosine 5'-phosphosulfate kinase-were upregulated. It led us to examine a plausible relationship between sulfur-enhanced resistance (SED) and HCRSV infection. We broadened an established method to include different concentrations of sulfur (0S, 1S, 2S, and 3S) to correlate them to symptom development of HCRSV-infected plants. We treated plants with glutathione and its inhibitor to verify the SED effect. Disease resistance was induced through elevated glutathione contents during HCRSV infection. The upregulation of SO was related to suppression of symptom development induced by sulfur treatment. In this study, we established that HCRSV-CP interacts with SO which, in turn, triggers SED and leads to enhanced plant resistance. Thus, we have discovered a new function of SO in the SED pathway. This is the first report to demonstrate that the interaction of a viral protein and host protein trigger SED in plants. It will be interesting if such interaction applies generally to other host-pathogen interactions that will lead to enhanced pathogen defense.

Utilization of Field Enhancement in Plasmonic Waveguides for Subwavelength Light-Guiding, Polarization Handling, Heating, and Optical Sensing.

Science.gov (United States)

Dai, Daoxin; Wu, Hao; Zhang, Wei

2015-10-09

Plasmonic nanostructures have attracted intensive attention for many applications in recent years because of the field enhancement at the metal/dielectric interface. First, this strong field enhancement makes it possible to break the diffraction limit and enable subwavelength optical waveguiding, which is desired for nanophotonic integrated circuits with ultra-high integration density. Second, the field enhancement in plasmonic nanostructures occurs only for the polarization mode whose electric field is perpendicular to the metal/dielectric interface, and thus the strong birefringence is beneficial for realizing ultra-small polarization-sensitive/selective devices, including polarization beam splitters, and polarizers. Third, plasmonic nanostructures provide an excellent platform of merging electronics and photonics for some applications, e.g., thermal tuning, photo-thermal detection, etc. Finally, the field enhancement at the metal/dielectric interface helps a lot to realize optical sensors with high sensitivity when introducing plasmonic nanostrutures. In this paper, we give a review for recent progresses on the utilization of field enhancement in plasmonic nanostructures for these applications, e.g., waveguiding, polarization handling, heating, as well as optical sensing.

Utilization of Field Enhancement in Plasmonic Waveguides for Subwavelength Light-Guiding, Polarization Handling, Heating, and Optical Sensing

Directory of Open Access Journals (Sweden)

Daoxin Dai

2015-10-01

Full Text Available Plasmonic nanostructures have attracted intensive attention for many applications in recent years because of the field enhancement at the metal/dielectric interface. First, this strong field enhancement makes it possible to break the diffraction limit and enable subwavelength optical waveguiding, which is desired for nanophotonic integrated circuits with ultra-high integration density. Second, the field enhancement in plasmonic nanostructures occurs only for the polarization mode whose electric field is perpendicular to the metal/dielectric interface, and thus the strong birefringence is beneficial for realizing ultra-small polarization-sensitive/selective devices, including polarization beam splitters, and polarizers. Third, plasmonic nanostructures provide an excellent platform of merging electronics and photonics for some applications, e.g., thermal tuning, photo-thermal detection, etc. Finally, the field enhancement at the metal/dielectric interface helps a lot to realize optical sensors with high sensitivity when introducing plasmonic nanostrutures. In this paper, we give a review for recent progresses on the utilization of field enhancement in plasmonic nanostructures for these applications, e.g., waveguiding, polarization handling, heating, as well as optical sensing.

Binding proteins enhance specific uptake rate by increasing the substrate-transporter encounter rate.

Science.gov (United States)

Bosdriesz, Evert; Magnúsdóttir, Stefanía; Bruggeman, Frank J; Teusink, Bas; Molenaar, Douwe

2015-06-01

Microorganisms rely on binding-protein assisted, active transport systems to scavenge for scarce nutrients. Several advantages of using binding proteins in such uptake systems have been proposed. However, a systematic, rigorous and quantitative analysis of the function of binding proteins is lacking. By combining knowledge of selection pressure and physiochemical constraints, we derive kinetic, thermodynamic, and stoichiometric properties of binding-protein dependent transport systems that enable a maximal import activity per amount of transporter. Under the hypothesis that this maximal specific activity of the transport complex is the selection objective, binding protein concentrations should exceed the concentration of both the scarce nutrient and the transporter. This increases the encounter rate of transporter with loaded binding protein at low substrate concentrations, thereby enhancing the affinity and specific uptake rate. These predictions are experimentally testable, and a number of observations confirm them. © 2015 FEBS.

Tomato leaf curl Kerala virus (ToLCKeV AC3 protein forms a higher order oligomer and enhances ATPase activity of replication initiator protein (Rep/AC1

Directory of Open Access Journals (Sweden)

Mukherjee Sunil K

2010-06-01

Full Text Available Abstract Background Geminiviruses are emerging plant viruses that infect a wide variety of vegetable crops, ornamental plants and cereal crops. They undergo recombination during co-infections by different species of geminiviruses and give rise to more virulent species. Antiviral strategies targeting a broad range of viruses necessitate a detailed understanding of the basic biology of the viruses. ToLCKeV, a virus prevalent in the tomato crop of Kerala state of India and a member of genus Begomovirus has been used as a model system in this study. Results AC3 is a geminiviral protein conserved across all the begomoviral species and is postulated to enhance viral DNA replication. In this work we have successfully expressed and purified the AC3 fusion proteins from E. coli. We demonstrated the higher order oligomerization of AC3 using sucrose gradient ultra-centrifugation and gel-filtration experiments. In addition we also established that ToLCKeV AC3 protein interacted with cognate AC1 protein and enhanced the AC1-mediated ATPase activity in vitro. Conclusions Highly hydrophobic viral protein AC3 can be purified as a fusion protein with either MBP or GST. The purification method of AC3 protein improves scope for the biochemical characterization of the viral protein. The enhancement of AC1-mediated ATPase activity might lead to increased viral DNA replication.

Electric-field enhanced performance in catalysis and solid-state devices involving gases

Science.gov (United States)

Blackburn, Bryan M.; Wachsman, Eric D.; Van Assche, IV, Frederick Martin

2015-05-19

Electrode configurations for electric-field enhanced performance in catalysis and solid-state devices involving gases are provided. According to an embodiment, electric-field electrodes can be incorporated in devices such as gas sensors and fuel cells to shape an electric field provided with respect to sensing electrodes for the gas sensors and surfaces of the fuel cells. The shaped electric fields can alter surface dynamics, system thermodynamics, reaction kinetics, and adsorption/desorption processes. In one embodiment, ring-shaped electric-field electrodes can be provided around sensing electrodes of a planar gas sensor.

Expression and characterization of insulin growth factor-I-enhanced green fluorescent protein fused protein as a tracer for immunoassay

Energy Technology Data Exchange (ETDEWEB)

Shi Ruina [College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Huang Yong [College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Wang Dan [College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Zhao Meiping [College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Li Yuanzong [College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)]. E-mail: yzli@pku.edu.cn

2006-09-25

The insulin-like growth factor-I (IGF-I) is an important polypeptide hormone under investigation for body metabolism study and for doping detection. Here, we describe for the first time the expression of a recombinant fusion protein of IGF-I and the enhanced green fluorescent protein (EGFP). The genetic fusion approach enables preparation of conjugates with 1:1 stoichiometry and homogeneous structure. The fused protein (EGFP-IGF-I) was expressed as a soluble protein in cytoplasm of Escherichia coli and its fluorescence and immunoreaction properties were thoroughly characterized. Finally, we demonstrated the utility of the EGFP-IGF-I fusion protein for the fluorescence immunoassay of IGF-1. The linear range of the assay is 1.6 x 10{sup -8} to 2.0 x 10{sup -6} M with a detection limit of 1.6 x 10{sup -8} M. To our knowledge, this is the first time that EGFP has been used as a quantitative label in a fusion protein to develop a quantitative assay for IGF-I. Furthermore, the use of genetically engineered fusion proteins, which combine peptide hormones with fluorescent protein, can lead to a new labeling approach to a number of bioanalytical applications.

Expression and characterization of insulin growth factor-I-enhanced green fluorescent protein fused protein as a tracer for immunoassay

International Nuclear Information System (INIS)

Shi Ruina; Huang Yong; Wang Dan; Zhao Meiping; Li Yuanzong

2006-01-01

The insulin-like growth factor-I (IGF-I) is an important polypeptide hormone under investigation for body metabolism study and for doping detection. Here, we describe for the first time the expression of a recombinant fusion protein of IGF-I and the enhanced green fluorescent protein (EGFP). The genetic fusion approach enables preparation of conjugates with 1:1 stoichiometry and homogeneous structure. The fused protein (EGFP-IGF-I) was expressed as a soluble protein in cytoplasm of Escherichia coli and its fluorescence and immunoreaction properties were thoroughly characterized. Finally, we demonstrated the utility of the EGFP-IGF-I fusion protein for the fluorescence immunoassay of IGF-1. The linear range of the assay is 1.6 x 10 -8 to 2.0 x 10 -6 M with a detection limit of 1.6 x 10 -8 M. To our knowledge, this is the first time that EGFP has been used as a quantitative label in a fusion protein to develop a quantitative assay for IGF-I. Furthermore, the use of genetically engineered fusion proteins, which combine peptide hormones with fluorescent protein, can lead to a new labeling approach to a number of bioanalytical applications

Synergistic Enhancement of Enzyme Performance and Resilience via Orthogonal Peptide-Protein Chemistry Enabled Multilayer Construction.

Science.gov (United States)

Zhang, Xue-Jian; Wang, Xiao-Wei; Sun, Jiaxing; Su, Chao; Yang, Shuguang; Zhang, Wen-Bin

2018-05-16

Protein immobilization is critical to utilize their unique functions in diverse applications. Herein, we report that orthogonal peptide-protein chemistry enabled multilayer construction can facilitate the incorporation of various folded structural domains, including calmodulin in different states, affibody and dihydrofolate reductase (DHFR). An extended conformation is found to be the most advantageous for steady film growth. The resulting protein thin films exhibit sensitive and selective responsive behaviors to bio-signals (Ca2+, TFP, NADPH, etc.) and fully maintain the catalytic activity of DHFR. The approach is applicable to different substrates such as hydrophobic gold and hydrophilic silica microparticles. The DHFR enzyme can be immobilized onto silica microparticles with tunable amounts. The multi-layer set-up exhibits a synergistic enhancement of DHFR activity with increasing number of bilayers and also makes the embedded DHFR more resilient to lyophilization. Therefore, this is a convenient and versatile method for protein immobilization with potential benefits of synergistic enhancement in enzyme performance and resilience.

Identify High-Quality Protein Structural Models by Enhanced K-Means.

Science.gov (United States)

Wu, Hongjie; Li, Haiou; Jiang, Min; Chen, Cheng; Lv, Qiang; Wu, Chuang

2017-01-01

Background. One critical issue in protein three-dimensional structure prediction using either ab initio or comparative modeling involves identification of high-quality protein structural models from generated decoys. Currently, clustering algorithms are widely used to identify near-native models; however, their performance is dependent upon different conformational decoys, and, for some algorithms, the accuracy declines when the decoy population increases. Results. Here, we proposed two enhanced K -means clustering algorithms capable of robustly identifying high-quality protein structural models. The first one employs the clustering algorithm SPICKER to determine the initial centroids for basic K -means clustering ( SK -means), whereas the other employs squared distance to optimize the initial centroids ( K -means++). Our results showed that SK -means and K -means++ were more robust as compared with SPICKER alone, detecting 33 (59%) and 42 (75%) of 56 targets, respectively, with template modeling scores better than or equal to those of SPICKER. Conclusions. We observed that the classic K -means algorithm showed a similar performance to that of SPICKER, which is a widely used algorithm for protein-structure identification. Both SK -means and K -means++ demonstrated substantial improvements relative to results from SPICKER and classical K -means.

The inhibition of IGF-1 signaling promotes proteostasis by enhancing protein aggregation and deposition.

Science.gov (United States)

Moll, Lorna; Ben-Gedalya, Tziona; Reuveni, Hadas; Cohen, Ehud

2016-04-01

The discovery that the alteration of aging by reducing the activity of the insulin/IGF-1 signaling (IIS) cascade protects nematodes and mice from neurodegeneration-linked, toxic protein aggregation (proteotoxicity) raises the prospect that IIS inhibitors bear therapeutic potential to counter neurodegenerative diseases. Recently, we reported that NT219, a highly efficient IGF-1 signaling inhibitor, protects model worms from the aggregation of amyloid β peptide and polyglutamine peptides that are linked to the manifestation of Alzheimer's and Huntington's diseases, respectively. Here, we employed cultured cell systems to investigate whether NT219 promotes protein homeostasis (proteostasis) in mammalian cells and to explore its underlying mechanisms. We found that NT219 enhances the aggregation of misfolded prion protein and promotes its deposition in quality control compartments known as "aggresomes." NT219 also elevates the levels of certain molecular chaperones but, surprisingly, reduces proteasome activity and impairs autophagy. Our findings show that IGF-1 signaling inhibitors in general and NT219 in particular can promote proteostasis in mammalian cells by hyperaggregating hazardous proteins, thereby bearing the potential to postpone the onset and slow the progression of neurodegenerative illnesses in the elderly.-Moll, L., Ben-Gedalya, T., Reuveni, H., Cohen, E. The inhibition of IGF-1 signaling promotes proteostasis by enhancing protein aggregation and deposition. © FASEB.

Field experiment with liquid manure and enhanced biochar

Science.gov (United States)

Dunst, Gerald

2017-04-01

Field experiments with low amounts of various liquid manure enhanced biochars. In 2016 a new machine was developed to inject liquid biochar based fertilizer directly into the crop root zone. A large-scale field experiment with corn and oil seed pumpkin was set-up on 42 hectares on 15 different fields in the south East of Austria. Three treatments were compared: (1) surface spreading of liquid manure as control (common practice), (2) 20 cm deep root zone injection with same amount of liquid manure, and (3) 20 cm deep root zone injection with same amount of liquid manure mixed with 1 to 2 tons of various nutrient enhanced biochars. The biochar were quenched with the liquid phase from a separated digestate from a biogas plant (feedstock: cow manure). From May to October nitrate and ammonium content was analyzed monthly from 0-30cm and 30-60cm soil horizons. At the end of the growing season the yield was determined. The root zone injection of the liquid manure reduced the nitrate content during the first two months at 13-16% compared to the control. When the liquid manure was blended with biochar, Nitrate soil content was lowest (reduction 40-47%). On average the root zone injection of manure-biochar increased the yield by 7% compared to the surface applied control and 3% compared to the root zone injected manure without biochar. The results shows, that biochar is able to reduce the Nitrate load in soils and increase the yield of corn at the same time. The nutrient efficiency of organic liquid fertilizers can be increased.

A Comprehensive Model of Electric-Field-Enhanced Jumping-Droplet Condensation on Superhydrophobic Surfaces.

Science.gov (United States)

Birbarah, Patrick; Li, Zhaoer; Pauls, Alexander; Miljkovic, Nenad

2015-07-21

Superhydrophobic micro/nanostructured surfaces for dropwise condensation have recently received significant attention due to their potential to enhance heat transfer performance by shedding positively charged water droplets via coalescence-induced droplet jumping at length scales below the capillary length and allowing the use of external electric fields to enhance droplet removal and heat transfer, in what has been termed electric-field-enhanced (EFE) jumping-droplet condensation. However, achieving optimal EFE conditions for enhanced heat transfer requires capturing the details of transport processes that is currently lacking. While a comprehensive model has been developed for condensation on micro/nanostructured surfaces, it cannot be applied for EFE condensation due to the dynamic droplet-vapor-electric field interactions. In this work, we developed a comprehensive physical model for EFE condensation on superhydrophobic surfaces by incorporating individual droplet motion, electrode geometry, jumping frequency, field strength, and condensate vapor-flow dynamics. As a first step toward our model, we simulated jumping droplet motion with no external electric field and validated our theoretical droplet trajectories to experimentally obtained trajectories, showing excellent temporal and spatial agreement. We then incorporated the external electric field into our model and considered the effects of jumping droplet size, electrode size and geometry, condensation heat flux, and droplet jumping direction. Our model suggests that smaller jumping droplet sizes and condensation heat fluxes require less work input to be removed by the external fields. Furthermore, the results suggest that EFE electrodes can be optimized such that the work input is minimized depending on the condensation heat flux. To analyze overall efficiency, we defined an incremental coefficient of performance and showed that it is very high (∼10(6)) for EFE condensation. We finally proposed mechanisms

Ag-protein plasmonic architectures for surface plasmon-coupled emission enhancements and Fabry-Perot mode-coupled directional fluorescence emission

Science.gov (United States)

Badiya, Pradeep Kumar; Patnaik, Sai Gourang; Srinivasan, Venkatesh; Reddy, Narendra; Manohar, Chelli Sai; Vedarajan, Raman; Mastumi, Noriyoshi; Belliraj, Siva Kumar; Ramamurthy, Sai Sathish

2017-10-01

We report the use of silver decorated plant proteins as spacer material for augmented surface plasmon-coupled emission (120-fold enhancement) and plasmon-enhanced Raman scattering. We extracted several proteins from different plant sources [Triticum aestivum (TA), Aegle marmelos (AM), Ricinus communis (RC), Jatropha curcas (JC) and Simarouba glauca (SG)] followed by evaluation of their optical properties and simulations to rationalize observed surface plasmon resonance. Since the properties exhibited by protein thin films is currently gaining research interest, we have also carried out simulation studies with Ag-protein biocomposites as spacer materials in metal-dielectric-metal planar microcavity architecture for guided emission of Fabry-Perot mode-coupled fluorescence.

Quantum dynamical simulations of local field enhancement in metal nanoparticles.

Science.gov (United States)

Negre, Christian F A; Perassi, Eduardo M; Coronado, Eduardo A; Sánchez, Cristián G

2013-03-27

Field enhancements (Γ) around small Ag nanoparticles (NPs) are calculated using a quantum dynamical simulation formalism and the results are compared with electrodynamic simulations using the discrete dipole approximation (DDA) in order to address the important issue of the intrinsic atomistic structure of NPs. Quite remarkably, in both quantum and classical approaches the highest values of Γ are located in the same regions around single NPs. However, by introducing a complete atomistic description of the metallic NPs in optical simulations, a different pattern of the Γ distribution is obtained. Knowing the correct pattern of the Γ distribution around NPs is crucial for understanding the spectroscopic features of molecules inside hot spots. The enhancement produced by surface plasmon coupling is studied by using both approaches in NP dimers for different inter-particle distances. The results show that the trend of the variation of Γ versus inter-particle distance is different for classical and quantum simulations. This difference is explained in terms of a charge transfer mechanism that cannot be obtained with classical electrodynamics. Finally, time dependent distribution of the enhancement factor is simulated by introducing a time dependent field perturbation into the Hamiltonian, allowing an assessment of the localized surface plasmon resonance quantum dynamics.

Gene and protein expression following exposure to radiofrequency fields from mobile phones.

Science.gov (United States)

Vanderstraeten, Jacques; Verschaeve, Luc

2008-09-01

Since 1999, several articles have been published on genome-wide and/or proteome-wide response after exposure to radiofrequency (RF) fields whose signal and intensities were similar to or typical of those of currently used mobile telephones. These studies were performed using powerful high-throughput screening techniques (HTSTs) of transcriptomics and/or proteomics, which allow for the simultaneous screening of the expression of thousands of genes or proteins. We reviewed these HTST-based studies and compared the results with currently accepted concepts about the effects of RF fields on gene expression. In this article we also discuss these last in light of the recent concept of microwave-assisted chemistry. To date, the results of HTST-based studies of transcriptomics and/or proteomics after exposure to RF fields relevant to human exposure are still inconclusive, as most of the positive reports are flawed by methodologic imperfections or shortcomings. In addition, when positive findings were reported, no precise response pattern could be identified in a reproducible way. In particular, results from HTST studies tend to exclude the role of a cell stressor for exposure to RF fields at nonthermal intensities. However, on the basis of lessons from microwave-assisted chemistry, we can assume that RF fields might affect heat-sensitive gene or protein expression to an extent larger than would be predicted from temperature change only. But in all likelihood, this would concern intensities higher than those relevant to usual human exposure. The precise role of transcriptomics and proteomics in the screening of bioeffects from exposure to RF fields from mobile phones is still uncertain in view of the lack of positively identified phenotypic change and the lack of theoretical, as well as experimental, arguments for specific gene and/or protein response patterns after this kind of exposure.

Protein and metabolite composition of xylem sap from field-grown soybeans (Glycine max).

Science.gov (United States)

Krishnan, Hari B; Natarajan, Savithiry S; Bennett, John O; Sicher, Richard C

2011-05-01

The xylem, in addition to transporting water, nutrients and metabolites, is also involved in long-distance signaling in response to pathogens, symbionts and environmental stresses. Xylem sap has been shown to contain a number of proteins including metabolic enzymes, stress-related proteins, signal transduction proteins and putative transcription factors. Previous studies on xylem sap have mostly utilized plants grown in controlled environmental chambers. However, plants in the field are subjected to high light and to environmental stress that is not normally found in growth chambers. In this study, we have examined the protein and metabolite composition of xylem sap from field-grown cultivated soybean plants. One-dimensional gel electrophoresis of xylem sap from determinate, indeterminate, nodulating and non-nodulating soybean cultivars revealed similar protein profiles consisting of about 8-10 prominent polypeptides. Two-dimensional gel electrophoresis of soybean xylem sap resulted in the visualization of about 60 distinct protein spots. A total of 38 protein spots were identified using MALDI-TOF MS and LC-MS/MS. The most abundant proteins present in the xylem sap were identified as 31 and 28 kDa vegetative storage proteins. In addition, several proteins that are conserved among different plant species were also identified. Diurnal changes in the metabolite profile of xylem sap collected during a 24-h cycle revealed that asparagine and aspartate were the two predominant amino acids irrespective of the time collected. Pinitol (D-3-O-methyl-chiro-inositol) was the most abundant carbohydrate present. The possible roles of xylem sap proteins and metabolites as nutrient reserves for sink tissue and as an indicator of biotic stress are also discussed.

ON current enhancement of nanowire Schottky barrier tunnel field effect transistors

Science.gov (United States)

Takei, Kohei; Hashimoto, Shuichiro; Sun, Jing; Zhang, Xu; Asada, Shuhei; Xu, Taiyu; Matsukawa, Takashi; Masahara, Meishoku; Watanabe, Takanobu

2016-04-01

Silicon nanowire Schottky barrier tunnel field effect transistors (NW-SBTFETs) are promising structures for high performance devices. In this study, we fabricated NW-SBTFETs to investigate the effect of nanowire structure on the device characteristics. The NW-SBTFETs were operated with a backgate bias, and the experimental results demonstrate that the ON current density is enhanced by narrowing the width of the nanowire. We confirmed using the Fowler-Nordheim plot that the drain current in the ON state mainly comprises the quantum tunneling component through the Schottky barrier. Comparison with a technology computer aided design (TCAD) simulation revealed that the enhancement is attributed to the electric field concentration at the corners of cross-section of the NW. The study findings suggest an effective approach to securing the ON current by Schottky barrier width modulation.

Dietary protein and fat emulsions, processed by ultrasound and pulsed magnetic field

Directory of Open Access Journals (Sweden)

E. I. Verboloz

2017-01-01

Full Text Available For the baking of baked goods in order to save fats, different types of endorsement and protein-fatty emulsions which are used as ingredients in goods and for the protection of metal moulds from burning. Usually emulsion is prepared on bakery enterprises by National State Standard Р 51785–2001, involving mechanical beating up of ingredients. The authors suggested and studied the way of manufacturing of more stable food protein-fatty emulsions using ultrasonic transmitter with rigid neodymium magnets on its thickener. As ingredients, there were applied curd whey diluted with water, unpurified sunflower oil and sunflower phosphatides. Ratio of whey and water is 1:7. Physical effects of ultrasound and field of magnets in contact layer of liquid ingredients being dispersed have increased the viscosity and dispersion of protein-fatty emulsions. Hypothesis of increase of stability and sterility of protein-fatty emulsion by the selection of parameters of magnetic field and power of ultrasound transmitter is confirmed experimentally. Microscopic analysis shows high degree of homogeneity of emulsion under the time of processing 3-4 minutes and intensity of ultrasound 2 W/cm2, that is energetically profitable. There was revealed synergism of influence of physical effects of ultrasound and magnetic field on the durability and steadiness of emulsion to mechanical and temperature effect and also cidal effect, prolonging terms of product using. Manufacture of emulsions by the declared way using the ultrasound and magnetic field of constant neodymium magnets decreases number of injected elements-emulsifiers by 3-4 times or excludes their use at all. Existing piezoelectric ultrasound units as well as neodymium magnets have small sizes and low energy consumption, easily built into the line of continuous manufacture of emulsion for the bread production. Such emulsions are less demanding to the storage and transportation.

Enhanced energy transfer by near-field coupling of a nanostructured metamaterial with a graphene-covered plate

International Nuclear Information System (INIS)

Chang, Jui-Yung; Yang, Yue; Wang, Liping

2016-01-01

Coupled surface plasmon/phonon polaritons and hyperbolic modes are known to enhance radiative transfer across nanometer vacuum gaps but usually require identical materials. It becomes crucial to achieve strong near-field energy transfer between dissimilar materials for applications like near-field thermophotovoltaic and thermal rectification. In this work, we theoretically demonstrate enhanced near-field radiative transfer between a nanostructured metamaterial emitter and a graphene-covered planar receiver. Strong near-field coupling with two orders of magnitude enhancement in the spectral heat flux is achieved at the gap distance of 20 nm. By carefully selecting the graphene chemical potential and doping levels of silicon nanohole emitter and silicon plate receiver, the total near-field radiative heat flux can reach about 500 times higher than the far-field blackbody limit between 400 K and 300 K. The physical mechanism is elucidated by the near-field surface plasmon coupling with fluctuational electrodynamics and dispersion relations. The effects of graphene chemical potential, emitter and receiver doping levels, and vacuum gap distance on the near-field coupling and radiative energy transfer are analyzed in detail. - Highlights: • Near-field radiative transfer between a metamaterial and a graphene-covered plate is studied. • Effective medium theory with uniaxial optics is employed to model nanohole metamaterials. • Enhancement by 2 orders is found between dissimilar materials with graphene coating. • Extraordinary coupling of the nanostructured emitter with graphene is elucidated. • Effects of doping level of silicon and graphene chemical potential are investigated.

Translation system engineering in Escherichia coli enhances non-canonical amino acid incorporation into proteins.

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Gan, Rui; Perez, Jessica G; Carlson, Erik D; Ntai, Ioanna; Isaacs, Farren J; Kelleher, Neil L; Jewett, Michael C

2017-05-01

The ability to site-specifically incorporate non-canonical amino acids (ncAAs) into proteins has made possible the study of protein structure and function in fundamentally new ways, as well as the bio synthesis of unnatural polymers. However, the task of site-specifically incorporating multiple ncAAs into proteins with high purity and yield continues to present a challenge. At the heart of this challenge lies the lower efficiency of engineered orthogonal translation system components compared to their natural counterparts (e.g., translation elements that specifically use a ncAA and do not interact with the cell's natural translation apparatus). Here, we show that evolving and tuning expression levels of multiple components of an engineered translation system together as a whole enhances ncAA incorporation efficiency. Specifically, we increase protein yield when incorporating multiple p-azido-phenylalanine(pAzF) residues into proteins by (i) evolving the Methanocaldococcus jannaschii p-azido-phenylalanyl-tRNA synthetase anti-codon binding domain, (ii) evolving the elongation factor Tu amino acid-binding pocket, and (iii) tuning the expression of evolved translation machinery components in a single vector. Use of the evolved translation machinery in a genomically recoded organism lacking release factor one enabled enhanced multi-site ncAA incorporation into proteins. We anticipate that our approach to orthogonal translation system development will accelerate and expand our ability to site-specifically incorporate multiple ncAAs into proteins and biopolymers, advancing new horizons for synthetic and chemical biotechnology. Biotechnol. Bioeng. 2017;114: 1074-1086. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Theory and simulations of radiation friction induced enhancement of laser-driven longitudinal fields

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Gelfer, E. G.; Fedotov, A. M.; Weber, S.

2018-06-01

We consider the generation of a quasistatic longitudinal electric field by intense laser pulses propagating in a transparent plasma with radiation friction (RF) taken into account. For both circular and linear polarization of the driving pulse we develop a 1D analytical model of the process, which is valid in a wide range of laser and plasma parameters. We define the parameter region where RF results in an essential enhancement of the longitudinal field. The amplitude and the period of the generated longitudinal wave are estimated and optimized. Our theoretical predictions are confirmed by 1D and 2D PIC simulations. We also demonstrate numerically that RF should substantially enhance the longitudinal field generated in a plasma by a 10 PW laser such as ELI Beamlines.

Coulomb interactions between cytoplasmic electric fields and phosphorylated messenger proteins optimize information flow in cells.

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Robert A Gatenby

2010-08-01

Full Text Available Normal cell function requires timely and accurate transmission of information from receptors on the cell membrane (CM to the nucleus. Movement of messenger proteins in the cytoplasm is thought to be dependent on random walk. However, Brownian motion will disperse messenger proteins throughout the cytosol resulting in slow and highly variable transit times. We propose that a critical component of information transfer is an intracellular electric field generated by distribution of charge on the nuclear membrane (NM. While the latter has been demonstrated experimentally for decades, the role of the consequent electric field has been assumed to be minimal due to a Debye length of about 1 nanometer that results from screening by intracellular Cl- and K+. We propose inclusion of these inorganic ions in the Debye-Huckel equation is incorrect because nuclear pores allow transit through the membrane at a rate far faster than the time to thermodynamic equilibrium. In our model, only the charged, mobile messenger proteins contribute to the Debye length.Using this revised model and published data, we estimate the NM possesses a Debye-Huckel length of a few microns and find this is consistent with recent measurement using intracellular nano-voltmeters. We demonstrate the field will accelerate isolated messenger proteins toward the nucleus through Coulomb interactions with negative charges added by phosphorylation. We calculate transit times as short as 0.01 sec. When large numbers of phosphorylated messenger proteins are generated by increasing concentrations of extracellular ligands, we demonstrate they generate a self-screening environment that regionally attenuates the cytoplasmic field, slowing movement but permitting greater cross talk among pathways. Preliminary experimental results with phosphorylated RAF are consistent with model predictions.This work demonstrates that previously unrecognized Coulomb interactions between phosphorylated messenger

Extraordinary Magnetic Field Enhancement with Metallic Nanowire: Role of Surface Impedance in Babinet's Principle for Sub-Skin-Depth Regime

Science.gov (United States)

Koo, Sukmo; Kumar, M. Sathish; Shin, Jonghwa; Kim, Daisik; Park, Namkyoo

2009-12-01

We propose and analyze the “complementary” structure of a metallic nanogap, namely, the metallic nanowire for magnetic field enhancement. A huge enhancement of the field up to a factor of 300 was achieved. Introducing the surface impedance concept, we also develop and numerically confirm a new analytic theory which successfully predicts the field enhancement factors for metal nanostructures. Compared to the predictions of the classical Babinet principle applied to a nanogap, an order of magnitude difference in the field enhancement factor was observed for the sub-skin-depth regime nanowire.

Heat transfer enhancement in a convective field by applying ionic wind

International Nuclear Information System (INIS)

Tada, Y.; Takimoto, A.; Hayashi, Y.

1991-01-01

This paper reports that this study has been conducted to pursue the heat transfer enhancement in a convective field by applying electric field. Firstly, aimed at thinning boundary layer, swirl motions were caused by utilizing the ionic wind in a channel flow with parallel wire-electrode arrangement. Secondly, ionic wind was induced at right angle to the primary flow at regular intervals by using cross wire-electrode arrangement. Thirdly, to utilize the dynamical effect of adding particles under the Coulomb force, electric field was applied to gas-solid suspensions flow field. On the basis of these results, fundamental characteristics of the combined flow structure and the heat transfer in the EHD field were clarified, and the possibility of the practical application will be insighted

Field Enhancement in a Grounded Dielectric Slab by Using a Single Superstrate Layer

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Constantinos A. Valagiannopoulos

2012-01-01

Full Text Available The addition of a dielectric layer on a slab configuration is frequently utilized in various electromagnetic devices in order to give them certain desired operational characteristics. In this work, we consider a grounded dielectric film-slab, which is externally excited by a normally-incident Gaussian beam. On top of the film-slab, we use an additional suitably selected single isotropic superstrate layer in order to increase the field concentration inside the slab and hence achieve optimal power transfer from the external source to the internal region. We define a quantity of interest, called “enhancement factor,” expressing the increase of the field concentration in the film-slab when the superstrate is present compared to the case that it is absent. It is shown that large enhancement factor values may be achieved by choosing properly the permittivity, the permeability, and the thickness of the superstrate. In particular, it is demonstrated that the field in the film-slab is significantly enhanced when the slab is composed by an ϵ-near-zero (ENZ or low-index metamaterial.

Mapping the Protein Fold Universe Using the CamTube Force Field in Molecular Dynamics Simulations.

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Kukic, Predrag; Kannan, Arvind; Dijkstra, Maurits J J; Abeln, Sanne; Camilloni, Carlo; Vendruscolo, Michele

2015-10-01

It has been recently shown that the coarse-graining of the structures of polypeptide chains as self-avoiding tubes can provide an effective representation of the conformational space of proteins. In order to fully exploit the opportunities offered by such a 'tube model' approach, we present here a strategy to combine it with molecular dynamics simulations. This strategy is based on the incorporation of the 'CamTube' force field into the Gromacs molecular dynamics package. By considering the case of a 60-residue polyvaline chain, we show that CamTube molecular dynamics simulations can comprehensively explore the conformational space of proteins. We obtain this result by a 20 μs metadynamics simulation of the polyvaline chain that recapitulates the currently known protein fold universe. We further show that, if residue-specific interaction potentials are added to the CamTube force field, it is possible to fold a protein into a topology close to that of its native state. These results illustrate how the CamTube force field can be used to explore efficiently the universe of protein folds with good accuracy and very limited computational cost.

Vastly enhancing the chemical stability of phosphorene by employing an electric field.

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Gao, Junfeng; Zhang, Gang; Zhang, Yong-Wei

2017-03-23

Currently, a major hurdle preventing phosphorene from various electronic applications is its rapid oxidation under ambient conditions. Thus how to enhance its chemical stability by suppressing oxidation becomes an urgent task. Here, we reveal a highly effective procedure to suppress the oxidation of phosphorene by employing a suitable van der Waals (vdW) substrate and a vertical electric field. Our first-principles study shows that the phosphorene-MoSe 2 vdW heterostructure is able to reverse the stability of physisorption and chemisorption of molecular O 2 on phosphorene. With further application of a vertical electric field of -0.6 V Å -1 , the energy barrier for oxidation is able to further increase to 0.91 eV, leading to a 10 5 times enhancement in its lifetime compared with that without using the procedure at room temperature. Our work presents a viable strategy to vastly enhance the chemical stability of phosphorene in air.

Research field development ou iron-sulfur proteins by the Moessbauer spectroscopy and EPR

International Nuclear Information System (INIS)

Arsenio, T.P.; Taft, C.A.

1984-01-01

A research line on iron sulfides (chemical and structurally seemed with the iron-sulfur proteins), implanted and developed at CBPF-Brazil, using the same theoretical and experimental models used in the development of the research field on iron-sulfur proteins is reported. The techniques used are Moessbauer spectroscopy and EPR. (L.C.) [pt

Proton detection for signal enhancement in solid-state NMR experiments on mobile species in membrane proteins

Energy Technology Data Exchange (ETDEWEB)

Ward, Meaghan E.; Ritz, Emily [University of Guelph, Department of Physics (Canada); Ahmed, Mumdooh A. M. [Suez University, The Department of Physics, Faculty of Science (Egypt); Bamm, Vladimir V.; Harauz, George [University of Guelph, Biophysics Interdepartmental Group (Canada); Brown, Leonid S.; Ladizhansky, Vladimir, E-mail: vladizha@uoguelph.ca [University of Guelph, Department of Physics (Canada)

2015-12-15

Direct proton detection is becoming an increasingly popular method for enhancing sensitivity in solid-state nuclear magnetic resonance spectroscopy. Generally, these experiments require extensive deuteration of the protein, fast magic angle spinning (MAS), or a combination of both. Here, we implement direct proton detection to selectively observe the mobile entities in fully-protonated membrane proteins at moderate MAS frequencies. We demonstrate this method on two proteins that exhibit different motional regimes. Myelin basic protein is an intrinsically-disordered, peripherally membrane-associated protein that is highly flexible, whereas Anabaena sensory rhodopsin is composed of seven rigid transmembrane α-helices connected by mobile loop regions. In both cases, we observe narrow proton linewidths and, on average, a 10× increase in sensitivity in 2D insensitive nuclear enhancement of polarization transfer-based HSQC experiments when proton detection is compared to carbon detection. We further show that our proton-detected experiments can be easily extended to three dimensions and used to build complete amino acid systems, including sidechain protons, and obtain inter-residue correlations. Additionally, we detect signals which do not correspond to amino acids, but rather to lipids and/or carbohydrates which interact strongly with membrane proteins.

Analysis of near-field components of a plasmonic optical antenna and their contribution to quantum dot infrared photodetector enhancement.

Science.gov (United States)

Gu, Guiru; Vaillancourt, Jarrod; Lu, Xuejun

2014-10-20

In this paper, we analyze near-field vector components of a metallic circular disk array (MCDA) plasmonic optical antenna and their contribution to quantum dot infrared photodetector (QDIP) enhancement. The near-field vector components of the MCDA optical antenna and their distribution in the QD active region are simulated. The near-field overlap integral with the QD active region is calculated at different wavelengths and compared with the QDIP enhancement spectrum. The x-component (E(x)) of the near-field vector shows a larger intensity overlap integral and stronger correlation with the QDIP enhancement than E(z) and thus is determined to be the major near-field component to the QDIP enhancement.

Application of Ionizing Radiations to Produce New Polysaccharides and Proteins with Enhanced Functionality

International Nuclear Information System (INIS)

Al Assaf, S.

2006-01-01

Treatment of polysaccharides with ionizing radiation either in the solid state or in aqueous solution leads to degradation, whereas application of radiation to process synthetic polymers to introduce structural changes and special performance characteristics is now a thriving industry. Using a mediating gas associated during the radiation treatment prevents the degradation of natural polymers and enables the introduction of different molecular and functional characteristics, as previously achieved with synthetic polymers. For example, the molecular weight can be increased and standardised, protein distribution reorganised and modified to ensure better emulsification, viscosity and viscoelasticity enhanced, leading when required to hydrogel formation. More than one hydrocolloid can also be integrated into a single matrix using this process. Protein, within demineralised bone, too can be modified to give enhanced osteoinductive capacity. This experience has led to additional patented and proprietary processes, using standard food processing techniques, to promote changes in a wide range of hydrocolloids which emulates and extend those which occur naturally. The lecture will describe these structural changes and their functional role by reference to several hydrocolloids, including acacia gums, pectin, ispaghula and hyaluronan, bone morphogenic protein. Applications in food products, dietary fibre and medical products will be illustrated

Novel high power impulse magnetron sputtering enhanced by an auxiliary electrical field

Energy Technology Data Exchange (ETDEWEB)

Li, Chunwei, E-mail: lcwnefu@126.com, E-mail: xiubotian@163.com [College of Engineering and Technology, Northeast Forestry University, Harbin 150040 (China); State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Tian, Xiubo, E-mail: lcwnefu@126.com, E-mail: xiubotian@163.com [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China)

2016-08-15

The high power impulse magnetron sputtering (HIPIMS) technique is a novel highly ionized physical vapor deposition method with a high application potential. However, the electron utilization efficiency during sputtering is rather low and the metal particle ionization rate needs to be considerably improved to allow for a large-scale industrial application. Therefore, we enhanced the HIPIMS technique by simultaneously applying an electric field (EF-HIPIMS). The effect of the electric field on the discharge process was studied using a current sensor and an optical emission spectrometer. Furthermore, the spatial distribution of the electric potential and electric field during the EF-HIPIMS process was simulated using the ANSYS software. The results indicate that a higher electron utilization efficiency and a higher particle ionization rate could be achieved. The auxiliary anode obviously changed the distribution of the electric potential and the electric field in the discharge region, which increased the plasma density and enhanced the degree of ionization of the vanadium and argon gas. Vanadium films were deposited to further compare both techniques, and the morphology of the prepared films was investigated by scanning electron microscopy. The films showed a smaller crystal grain size and a denser growth structure when the electric field was applied during the discharge process.

L-Citrulline Supplementation Enhances Fetal Growth and Protein Synthesis in Rats with Intrauterine Growth Restriction.

Science.gov (United States)

Bourdon, Aurélie; Parnet, Patricia; Nowak, Christel; Tran, Nhat-Thang; Winer, Norbert; Darmaun, Dominique

2016-03-01

Intrauterine growth restriction (IUGR) results from either maternal undernutrition or impaired placental blood flow, exposing offspring to increased perinatal mortality and a higher risk of metabolic syndrome and cardiovascular disease during adulthood. l-Citrulline is a precursor of l-arginine and nitric oxide (NO), which regulates placental blood flow. Moreover, l-citrulline stimulates protein synthesis in other models of undernutrition. The aim of the study was to determine whether l-citrulline supplementation would enhance fetal growth in a model of IUGR induced by maternal dietary protein restriction. Pregnant rats were fed either a control (20% protein) or a low-protein (LP; 4% protein) diet. LP dams were randomly allocated to drink tap water either as such or supplemented with l-citrulline (2 g · kg(-1) · d(-1)), an isonitrogenous amount of l-arginine, or nonessential l-amino acids (NEAAs). On day 21 of gestation, dams received a 2-h infusion of l-[1-(13)C]-valine until fetuses were extracted by cesarean delivery. Isotope enrichments were measured in free amino acids and fetal muscle, liver, and placenta protein by GC-mass spectrometry. Fetal weight was ∼29% lower in the LP group (3.82 ± 0.06 g) than in the control group (5.41 ± 0.10 g) (P growth in a model of IUGR, and the effect may be mediated by enhanced fetal muscle protein synthesis and/or increased NO production. © 2016 American Society for Nutrition.

Enhancing Food Processing by Pulsed and High Voltage Electric Fields: Principles and Applications.

Science.gov (United States)

Wang, Qijun; Li, Yifei; Sun, Da-Wen; Zhu, Zhiwei

2018-02-02

Improvements in living standards result in a growing demand for food with high quality attributes including freshness, nutrition and safety. However, current industrial processing methods rely on traditional thermal and chemical methods, such as sterilization and solvent extraction, which could induce negative effects on food quality and safety. The electric fields (EFs) involving pulsed electric fields (PEFs) and high voltage electric fields (HVEFs) have been studied and developed for assisting and enhancing various food processes. In this review, the principles and applications of pulsed and high voltage electric fields are described in details for a range of food processes, including microbial inactivation, component extraction, and winemaking, thawing and drying, freezing and enzymatic inactivation. Moreover, the advantages and limitations of electric field related technologies are discussed to foresee future developments in the food industry. This review demonstrates that electric field technology has a great potential to enhance food processing by supplementing or replacing the conventional methods employed in different food manufacturing processes. Successful industrial applications of electric field treatments have been achieved in some areas such as microbial inactivation and extraction. However, investigations of HVEFs are still in an early stage and translating the technology into industrial applications need further research efforts.

Enhanced heterologous protein productivity by genome reduction in Lactococcus lactis NZ9000.

Science.gov (United States)

Zhu, Duolong; Fu, Yuxin; Liu, Fulu; Xu, Haijin; Saris, Per Erik Joakim; Qiao, Mingqiang

2017-01-03

The implementation of novel chassis organisms to be used as microbial cell factories in industrial applications is an intensive research field. Lactococcus lactis, which is one of the most extensively studied model organisms, exhibits superior ability to be used as engineered host for fermentation of desirable products. However, few studies have reported about genome reduction of L. lactis as a clean background for functional genomic studies and a model chassis for desirable product fermentation. Four large nonessential DNA regions accounting for 2.83% in L. lactis NZ9000 (L. lactis 9 k) genome (2,530,294 bp) were deleted using the Cre-loxP deletion system as the first steps toward a minimized genome in this study. The mutants were compared with the parental strain in several physiological traits and evaluated as microbial cell factories for heterologous protein production (intracellular and secretory expression) with the red fluorescent protein (RFP) and the bacteriocin leucocin C (LecC) as reporters. The four mutants grew faster, yielded enhanced biomass, achieved increased adenosine triphosphate content, and diminished maintenance demands compared with the wild strain in the two media tested. In particular, L. lactis 9 k-4 with the largest deletion was identified as the optimum candidate host for recombinant protein production. With nisin induction, not only the transcriptional efficiency but also the production levels of the expressed reporters were approximately three- to fourfold improved compared with the wild strain. The expression of lecC gene controlled with strong constitutive promoters P5 and P8 in L. lactis 9 k-4 was also improved significantly. The genome-streamlined L. lactis 9 k-4 outcompeted the parental strain in several physiological traits assessed. Moreover, L. lactis 9 k-4 exhibited good properties as platform organism for protein production. In future works, the genome of L. lactis will be maximally reduced by using our specific design

Cartilage oligomeric matrix protein enhances matrix assembly during chondrogenesis of human mesenchymal stem cells.

Science.gov (United States)

Haleem-Smith, Hana; Calderon, Raul; Song, Yingjie; Tuan, Rocky S; Chen, Faye H

2012-04-01

Cartilage oligomeric matrix protein/thrombospondin-5 (COMP/TSP5) is an abundant cartilage extracellular matrix (ECM) protein that interacts with major cartilage ECM components, including aggrecan and collagens. To test our hypothesis that COMP/TSP5 functions in the assembly of the ECM during cartilage morphogenesis, we have employed mesenchymal stem cell (MSC) chondrogenesis in vitro as a model to examine the effects of COMP over-expression on neo-cartilage formation. Human bone marrow-derived MSCs were transfected with either full-length COMP cDNA or control plasmid, followed by chondrogenic induction in three-dimensional pellet or alginate hydrogel culture. MSC chondrogenesis and ECM production was estimated based on quantitation of sulfated glycosaminoglycan (sGAG) accumulation, immunohistochemistry of the presence and distribution of cartilage ECM proteins, and real-time RT-PCR analyis of mRNA expression of cartilage markers. Our results showed that COMP over-expression resulted in increased total sGAG content during the early phase of MSC chondrogenesis, and increased immuno-detectable levels of aggrecan and collagen type II in the ECM of COMP-transfected pellet and alginate cultures, indicating more abundant cartilaginous matrix. COMP transfection did not significantly increase the transcript levels of the early chondrogenic marker, Sox9, or aggrecan, suggesting that enhancement of MSC cartilage ECM was effected at post-transcriptional levels. These findings strongly suggest that COMP functions in mesenchymal chondrogenesis by enhancing cartilage ECM organization and assembly. The action of COMP is most likely mediated not via direct changes in cartilage matrix gene expression but via interactions of COMP with other cartilage ECM proteins, such as aggrecan and collagens, that result in enhanced assembly and retention.

CARTILAGE OLIGOMERIC MATRIX PROTEIN ENHANCES MATRIX ASSEMBLY DURING CHONDROGENESIS OF HUMAN MESENCHYMAL STEM CELLS

Science.gov (United States)

Haleem-Smith, Hana; Calderon, Raul; Song, Yingjie; Tuan, Rocky S.; Chen, Faye H.

2011-01-01

Cartilage oligomeric matrix protein/thrombospondin-5 (COMP/TSP5) is an abundant cartilage extracellular matrix (ECM) protein that interacts with major cartilage ECM components, including aggrecan and collagens. To test our hypothesis that COMP/TSP5 functions in the assembly of the ECM during cartilage morphogenesis, we have employed mesenchymal stem cell (MSC) chondrogenesis in vitro as a model to examine the effects of COMP over-expression on neo-cartilage formation. Human bone marrow-derived MSCs were transfected with either full-length COMP cDNA or control plasmid, followed by chondrogenic induction in three-dimensional pellet or alginate-hydrogel culture. MSC chondrogenesis and ECM production was estimated based on quantitation of sulfated glycosaminoglycan (sGAG) accumulation, immunohistochemistry of the presence and distribution of cartilage ECM proteins, and real-time RT-PCR analyis of mRNA expression of cartilage markers. Our results showed that COMP over-expression resulted in increased total sGAG content during the early phase of MSC chondrogenesis, and increased immuno-detectable levels of aggrecan and collagen type II in the ECM of COMP-transfected pellet and alginate cultures, indicating more abundant cartilaginous matrix. COMP transfection did not significantly increase the transcript levels of the early chondrogenic marker, Sox9, or aggrecan, suggesting that enhancement of MSC cartilage ECM was effected at post-transcriptional levels. These findings strongly suggest that COMP functions in mesenchymal chondrogenesis by enhancing cartilage ECM organization and assembly. The action of COMP is most likely mediated not via direct changes in cartilage matrix gene expression but via interactions of COMP with other cartilage ECM proteins, such as aggrecan and collagens, that result in enhanced assembly and retention. PMID:22095699

Near-field enhanced femtosecond laser nano-drilling of glass substrate

International Nuclear Information System (INIS)

Zhou, Y.; Hong, M.H.; Fuh, J.Y.H.; Lu, L.; Lukyanchuk, B.S.; Wang, Z.B.

2008-01-01

Particle mask assisted near-field enhanced femtosecond laser nano-drilling of transparent glass substrate was demonstrated in this paper. A particle mask was fabricated by self-assembly of spherical 1 μm silica particles on the substrate surface. Then the samples were exposed to femtosecond laser (800 nm, 100 fs) and characterized by field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). The nano-hole array was found on the glass surface. The hole sizes were measured from 200 to 300 nm with an average depth of 150 nm and increased with laser fluence. Non-linear triple-photon absorption and near-field enhancement were the main mechanisms of the nano-feature formation. Calculations based on Mie theory shows an agreement with experiment results. More debris, however, was found at high laser fluence. This can be attributed to the explosion of silica particles because the focusing point is inside the 1 μm particle. The simulation predicts that the focusing point will move outside the particle if the particle size increases. The experiment performed under 6.84 μm silica particles verified that no debris was formed. And for all the samples, no cracks were found on the substrate surface because of ultra-short pulse width of femtosecond laser. This method has potential applications in nano-patterning of transparent glass substrate for nano-structure device fabrication

NADP+ enhances cholera and pertussis toxin-catalyzed ADP-ribosylation of membrane proteins

International Nuclear Information System (INIS)

Kawai, Y.; Whitsel, C.; Arinze, I.J.

1986-01-01

Cholera or pertussis toxin-catalyzed [ 32 P]ADP-ribosylation is frequently used to estimate the concentration of the stimulatory (Ns) or inhibitory (Ni) guanine nucleotide regulatory proteins which modulate the activity of adenylate cyclase. With this assay, however, the degradation of the substrate, NAD + , by endogenous enzymes such as NAD + -glycohydrolase (NADase) present in the test membranes can influence the results. In this study the authors show that both cholera and pertussis toxin-catalyzed [ 32 P]ADP-ribosylation of liver membrane proteins is markedly enhanced by NADP + . The effect is concentration dependent; with 20 μM [ 32 P]NAD + as substrate maximal enhancement is obtained at 0.5-1.0 mM NADP + . The enhancement of [ 32 P]ADP-ribosylation by NADP + was much greater than that by other known effectors such as Mg 2+ , phosphate or isoniazid. The effect of NADP + on ADP-ribosylation may occur by inhibition of the degradation of NAD + probably by acting as an alternate substrate for NADase. Among inhibitors tested (NADP + , isoniazid, imidazole, nicotinamide, L-Arg-methyl-ester and HgCl 2 ) to suppress NADase activity, NADP + was the most effective and, 10 mM, inhibited activity of the enzyme by about 90%. In membranes which contain substantial activities of NADase the inclusion of NADP + in the assay is necessary to obtain maximal ADP-ribosylation

Mass spectrometry for identification of proteins that specifically bind to a distal enhancer of the Oct4 gene

Science.gov (United States)

Bakhmet, E. I.; Nazarov, I. B.; Artamonova, T. O.; Khodorkovsky, M. A.; Tomilin, A. N.

2017-11-01

Transcription factor Oct4 is a marker of pluripotent stem cells and has a significant role in their self-renewal. Oct4 gene is controlled by three cis-regulatory elements - proximal promoter, proximal enhancer and distal enhancer. All of these elements are targets for binding of regulatory proteins. Distal enhancer is in our research focus because of its activity in early stages of embryonic development. There are two main sequences called site 2A and site 2B that are presented in distal enhancer. For this moment proteins which bind to a site 2A (CCCCTCCCCCC) remain unknown. Using combination of in vitro method electrophoretic mobility shift assay (EMSA) and mass spectromery we identified several candidates that can regulate Oct4 gene expression through site 2A.

Enhanced Hydrophilicity and Protein Adsorption of Titanium Surface by Sodium Bicarbonate Solution

Directory of Open Access Journals (Sweden)

Shengnan Jia

2015-01-01

Full Text Available The aim of this study was to investigate a novel and convenient method of chemical treatment to modify the hydrophilicity of titanium surfaces. Sand-blasted and acid-etched (SLA titanium surfaces and machined titanium surfaces were treated with sodium bicarbonate (NaHCO3 solution. The wetting behavior of both kinds of surfaces was measured by water contact angle (WCA test. The surface microstructure was assessed with scanning electron microscopy (SEM and three-dimensional (3D optical microscopy. The elemental compositions of the surfaces were analyzed by X-ray photoelectron spectroscopy (XPS. The protein adsorption analysis was performed with fibronectin. Results showed that, after 1 M NaHCO3 treatment, the hydrophilicity of both SLA and machined surfaces was enhanced. No significant microstructural change presented on titanium surfaces after NaHCO3 treatment. The deprotonation and ion exchange activities might cause the enhanced hydrophilicity of titanium surfaces. The increased protein adsorption of NaHCO3-treated SLA surfaces might indicate their improved tissue-integration in clinical use.

Enhanced detection of single-cell-secreted proteins using a fluorescent immunoassay on the protein-G-terminated glass substrate

Directory of Open Access Journals (Sweden)

Jeong Y

2015-11-01

Full Text Available Yoon Jeong,1,2 Kwan Hong Lee,1,2 Hansoo Park,3 Jonghoon Choi1,2 1Department of Bionano Technology, Graduate School, Hanyang University, Seoul, 2Department of Bionano Engineering, Hanyang University ERICA, Ansan, 3School of Integrative Engineering, Chung-Ang University, Seoul, South Korea Abstract: We present an evaluation of protein-G-terminated glass slides that may contain a suitable substrate for aligning the orientation of antibodies to obtain better binding moiety to the target antigen. The results of the protein-G-terminated slides were compared with those obtained with epoxy-based slides to evaluate signal enhancement for human immunoglobulin G (IgG targets, and an increase in the average fluorescence intensity was observed for the lowest measurable amount of IgG target in the assay using protein-G-terminated slides. Applying this strategy for signal amplification to single-cell assays improves the limits of detection for human IgG protein and cytokines (interleukin-2 and interferon-γ captured from hybridomas. Our data indicate that protein-G-terminated slides have a higher binding capacity for antigens and have better spot-to-spot consistency than that of traditional epoxy-based slides. These properties would be beneficial in the detection of fine amounts of single-cell-secreted proteins, which may provide key insights into cell–cell communication and immune responses. Keywords: microwell array, antibody’s orientation, single cell analysis, secreted cytokine, protein-G-terminated surface

Enhance and Maintain Chondrogenesis of Synovial Fibroblasts by Cartilage Extracellular Matrix Protein Matrilins

Science.gov (United States)

Pei, Ming; Luo, Junming; Chen, Qian

2008-01-01

Summary Objective Cartilage-specific extracellular matrix (ECM) proteins have been proposed to play key roles in modulating cellular phenotypes during chondrogenesis of mesenchymal stem cells. Matrilin (MATN) 1 and 3 are among the most up-regulated ECM proteins during chondrogenesis. The aim of this study was to analyze their roles in chondrogenesis of mesenchymal fibroblasts from synovium. Methods Primary synovial fibroblasts (SFBs) were purified from porcine synovium and incubated in pellet culture for 18 days. Chondrogenesis of SFB was analyzed by histological staining with safranin-O/fast green, and by quantifying glycosaminoglycans with dimethylmethylene blue assay. The mRNA levels of chondrogenic markers including collagen II, aggrecan, and Sox 9 were quantified by real-time RT-PCR, while the protein levels of Col II and matrilins were determined by western blot analysis. Results SFBs underwent chondrogenesis after incubation with TGF-β1 for three days; however, this process was attenuated during the subsequent incubation period. Expression of a MATN1 or 3 cDNA maintained and further enhanced chondrogenesis of SFBs as shown by increased cartilaginous matrix areas, elevated amount of glycosaminoglycans, and stimulated expression of chondrogenic markers. Conclusion Our findings suggest a novel function for MATN1 and 3 to maintain and enhance chondrogenesis of mesenchymal fibroblasts initiated by TGF-β. Our results also support a critical role of cartilage-specific ECM proteins to modulate cellular phenotypes in the microenvironment during chondrogenic differentiation. PMID:18282772

Enhancing and maintaining chondrogenesis of synovial fibroblasts by cartilage extracellular matrix protein matrilins.

Science.gov (United States)

Pei, M; Luo, J; Chen, Q

2008-09-01

Cartilage-specific extracellular matrix (ECM) proteins have been proposed to play key roles in modulating cellular phenotypes during chondrogenesis of mesenchymal stem cells. Matrilin (MATN)1 and MATN3 are among the most up-regulated ECM proteins during chondrogenesis. The aim of this study was to analyze their roles in chondrogenesis of mesenchymal fibroblasts from synovium. Primary synovial fibroblasts (SFBs) were purified from porcine synovium and incubated in pellet culture for 18 days. Chondrogenesis of SFB was analyzed by histological staining with safranin-O/fast green, and by quantifying glycosaminoglycans (GAG) with dimethylmethylene blue assay. The mRNA levels of chondrogenic markers including collagen II, aggrecan, and Sox 9 were quantified by real-time reverse transcription polymerase chain reaction, while the protein levels of Col II and MATNs were determined by western blot analysis. SFBs underwent chondrogenesis after incubation with transforming growth factor-beta1 (TGF-beta1) for 3 days; however, this process was attenuated during the subsequent incubation period. Expression of a Matn1 or Matn3 cDNA maintained and further enhanced chondrogenesis of SFBs as shown by increased cartilaginous matrix areas, elevated amount of GAG, and stimulated expression of chondrogenic markers. Our findings suggest a novel function for MATN1 and MATN3 to maintain and enhance chondrogenesis of mesenchymal fibroblasts initiated by TGF-beta. Our results also support a critical role of cartilage-specific ECM proteins to modulate cellular phenotypes in the microenvironment during chondrogenic differentiation.

Magnetic field action on outdoor and indoor cultures of Spirulina: Evaluation of growth, medium consumption and protein profile.

Science.gov (United States)

Deamici, Kricelle Mosquera; Santos, Lucielen Oliveira; Costa, Jorge Alberto Vieira

2018-02-01

This study aimed at evaluating whether a magnetic field (MF) affects the growth of Spirulina sp. when applied to it at different exposure times in indoor and outdoor culture systems. The effects of MF on chlorophyll content, medium consumption and protein profile were also investigated. In raceway tanks, a 25 mT MF was applied for 24 h or for 1 h d -1 . MF for 24 h to outdoor assays increased biomass concentration and chlorophyll-a content besides altering the protein profile. Outdoor Spirulina growth was higher (∼3.65 g L -1 ) than the growth found in indoor assays (∼1.80 g L -1 ), while nitrogen and phosphorus consumption was not enhanced by the application of MF. This is the first study that investigated the influence of MF on outdoor microalga assays, and the results showed that MF affected the metabolism of Spirulina cultured in raceways, especially when it was grown outdoors in uncontrolled environmental conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enhanced field emission from carbon nanotubes by hydrogen plasma treatment

International Nuclear Information System (INIS)

Zhi, C.Y.; Bai, X.D.; Wang, E.G.

2002-01-01

The field emission capability of the carbon nanotubes (CNTs) has been improved by hydrogen plasma treatment, and the enhanced emission mechanism has been studied systematically using Fourier-transform infrared spectroscopy, Raman, and transmission electron microscopy. The hydrogen concentration in the samples increases with increasing plasma treatment duration. A C δ- -H δ+ dipole layer may form on CNTs' surface and a high density of defects results from the plasma treatment, which is likely to make the external surface of CNTs more active to emit electrons after treatment. In addition, the sharp edge of CNTs' top, after removal of the catalyst particles, may increase the local electronic field more effectively. The present study suggests that hydrogen plasma treatment is a useful method for improving the field electron emission property of CNTs

Protein and starch concentrates of air-classified field pea and zero-tannin faba bean for weaned pigs.

Science.gov (United States)

Gunawardena, C K; Zijlstra, R T; Goonewardene, L A; Beltranena, E

2010-08-01

Air-classified pulse (non-oilseed legume) protein and starch may replace specialty protein and starch feedstuffs in diets for weaned pigs. In Exp. 1, three specialty protein sources (5% soy protein concentrate, 5% corn gluten meal, and 5% menhaden meal in the control diet) were replaced with 16% zero-tannin hulled or dehulled faba bean, or 17.5% field pea protein concentrate. In total, 192 group-housed pigs (2 gilts and 2 barrows per pen; BW = 7.5 +/- 1.4 kg) were fed wheat-based diets (3.60 Mcal/kg of DE and 3.3 g of standardized ileal digestible Lys/Mcal DE) over 28 d for 12 pen observations per each of 4 diets. Overall, protein source did not affect ADFI, ADG, or G:F. Apparent total tract digestibility (ATTD) of DM, GE, and P was greater (P bean and field pea protein concentrate diets than the diet with 3 specialty protein sources. In Exp. 2, faba bean and field pea starch concentrates were compared with corn, wheat, tapioca, and potato starch as dietary energy sources. In total, 36 individually housed barrows (BW = 8.0 +/- 1.5 kg) were fed 1 of 6 diets for 15 d. Feces and urine were collected from d 8 to 14, and jugular blood was sampled after overnight fast and refeeding on d 15. Starch source did not affect N retention as a percentage of N intake. For d 0 to 14, ADFI of pigs fed field pea starch was greater (P bean starch. Pigs fed tapioca, field pea, wheat, or corn starch grew faster (P bean or potato starch. For d 0 to 14, pigs fed corn or wheat starch had a 0.1 greater (P bean, field pea, or potato starch. The ATTD of DM, GE, CP, and starch and the DE value of potato starch were much less (P bean, wheat, and potato starch, respectively. However, postprandial plasma insulin tended to be 844 and 577 pmol/L greater (P bean and corn starch, respectively, than for pigs fed potato starch. The high insulin response of pigs fed faba starch could not be explained. In conclusion, air-classified pulse protein concentrates can replace specialty protein feedstuffs in

Proteomic identification of the related immune-enhancing proteins in shrimp Litopenaeus vannamei stimulated with vitamin C and Chinese herbs.

Science.gov (United States)

Qiao, Jie; Du, Zhiheng; Zhang, Yueling; Du, Hong; Guo, Lingling; Zhong, Mingqi; Cao, Jingsong; Wang, Xiuying

2011-12-01

Recently, strong interest has been focused on immunostimulants to reducing the diseases in shrimp aquaculture. However, information regarding to the related immune-enhancing proteins in shrimps is not available yet. In this study, vitamin C (Vc), Chinese herbs (CH), and the mixture of vitamin C and Chinese herbs (Mix) were tested for their enhancement on shrimp's immune activity. Compared with those in the control group, values of phenoloxidase (PO), superoxide dismutase (SOD) and antibacterial (Ua) activity in the Mix-treated group were improved significantly 12 or 24 days after the treatment. The cumulative mortality was also lower in the Mix-treated group after infection with Vibrio parahemolyticus. Furthermore, comparative proteomic approach was used to assess the protein expression profile in shrimps. Approximately 220-290 and 300-400 protein spots were observed in the 2-DE gels. Among them, 29 and 28 altered proteins from hemocytes and hepatopancreas, respectively, were subjected to matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS) analysis. The results revealed that the main altered proteins showed high homologies with Litopenaeus vannamei hemocyanin, hemolymph clottable protein, hemoglobin beta, cytosolic MnSOD, trypsin, cathepsin I(L) and zinc proteinase Mpc1. Together, these studies found Vc and CH were suitable immunostimulants to shrimp L. vannamei, and 7 altered proteins could be involved in the enhanced immune activities. Copyright © 2011 Elsevier Ltd. All rights reserved.

Enhancing the Functional Content of Eukaryotic Protein Interaction Networks

Science.gov (United States)

Pandey, Gaurav; Arora, Sonali; Manocha, Sahil; Whalen, Sean

2014-01-01

Protein interaction networks are a promising type of data for studying complex biological systems. However, despite the rich information embedded in these networks, these networks face important data quality challenges of noise and incompleteness that adversely affect the results obtained from their analysis. Here, we apply a robust measure of local network structure called common neighborhood similarity (CNS) to address these challenges. Although several CNS measures have been proposed in the literature, an understanding of their relative efficacies for the analysis of interaction networks has been lacking. We follow the framework of graph transformation to convert the given interaction network into a transformed network corresponding to a variety of CNS measures evaluated. The effectiveness of each measure is then estimated by comparing the quality of protein function predictions obtained from its corresponding transformed network with those from the original network. Using a large set of human and fly protein interactions, and a set of over GO terms for both, we find that several of the transformed networks produce more accurate predictions than those obtained from the original network. In particular, the measure and other continuous CNS measures perform well this task, especially for large networks. Further investigation reveals that the two major factors contributing to this improvement are the abilities of CNS measures to prune out noisy edges and enhance functional coherence in the transformed networks. PMID:25275489

Reovirus FAST Protein Enhances Vesicular Stomatitis Virus Oncolytic Virotherapy in Primary and Metastatic Tumor Models

Directory of Open Access Journals (Sweden)

Fabrice Le Boeuf

2017-09-01

Full Text Available The reovirus fusion-associated small transmembrane (FAST proteins are the smallest known viral fusogens (∼100–150 amino acids and efficiently induce cell-cell fusion and syncytium formation in multiple cell types. Syncytium formation enhances cell-cell virus transmission and may also induce immunogenic cell death, a form of apoptosis that stimulates immune recognition of tumor cells. These properties suggest that FAST proteins might serve to enhance oncolytic virotherapy. The oncolytic activity of recombinant VSVΔM51 (an interferon-sensitive vesicular stomatitis virus [VSV] mutant encoding the p14 FAST protein (VSV-p14 was compared with a similar construct encoding GFP (VSV-GFP in cell culture and syngeneic BALB/c tumor models. Compared with VSV-GFP, VSV-p14 exhibited increased oncolytic activity against MCF-7 and 4T1 breast cancer spheroids in culture and reduced primary 4T1 breast tumor growth in vivo. VSV-p14 prolonged survival in both primary and metastatic 4T1 breast cancer models, and in a CT26 metastatic colon cancer model. As with VSV-GFP, VSV-p14 preferentially replicated in vivo in tumors and was cleared rapidly from other sites. Furthermore, VSV-p14 increased the numbers of activated splenic CD4, CD8, natural killer (NK, and natural killer T (NKT cells, and increased the number of activated CD4 and CD8 cells in tumors. FAST proteins may therefore provide a multi-pronged approach to improving oncolytic virotherapy via syncytium formation and enhanced immune stimulation.

Plasmon field enhancement oscillations induced by strain-mediated coupling between a quantum dot and mechanical oscillator.

Science.gov (United States)

He, Yong

2017-06-23

We utilize the surface plasmon field of a metal nanoparticle (MNP) to show strain-mediated coupling in a quantum dot-mechanical resonator hybrid system including a quantum dot (QD) embedded within a conical nanowire (NW) and a MNP in the presence of an external field. Based on the numerical solutions of the master equation, we find that a slow oscillation, originating from the strain-mediated coupling between the QD and the NW, appears in the time evolution of the plasmon field enhancement. The results show that the period (about [Formula: see text]) of the slow oscillation is equal to that of the mechanical resonator of NW, which suggests that the time-resolved measurement of the plasmon field enhancement can be easily achieved based on the current experimental conditions. Its amplitude increases with the increasing strain-mediated coupling strength, and under certain conditions there is a linear relationship between them. The slow oscillation of the plasmon field enhancement provides valuable tools for measurements of the mechanical frequency and the strain-mediated coupling strength.

Pharmacological Inhibition of Protein Kinase G1 Enhances Bone Formation by Human Skeletal Stem Cells Through Activation of RhoA-Akt Signaling

DEFF Research Database (Denmark)

Kermani, Abbas Jafari; Siersbaek, Majken S; Chen, Li

2015-01-01

for several malignant and nonmalignant conditions. We screened a library of kinase inhibitors to identify small molecules that enhance bone formation by human skeletal (stromal or mesenchymal) stem cells (hMSC). We identified H-8 (known to inhibit protein kinases A, C, and G) as a potent enhancer of ex vivo......Development of novel approaches to enhance bone regeneration is needed for efficient treatment of bone defects. Protein kinases play a key role in regulation of intracellular signal transduction pathways, and pharmacological targeting of protein kinases has led to development of novel treatments...

Enhanced binding by dextran-grafting to Protein A affinity chromatographic media.

Science.gov (United States)

Zhao, Lan; Zhu, Kai; Huang, Yongdong; Li, Qiang; Li, Xiunan; Zhang, Rongyue; Su, Zhiguo; Wang, Qibao; Ma, Guanghui

2017-04-01

Dextran-grafted Protein A affinity chromatographic medium was prepared by grafting dextran to agarose-based matrix, followed by epoxy-activation and Protein A coupling site-directed to sulfhydryl groups of cysteine molecules. An enhancement of both the binding performance and the stability was achieved for this dextran-grafted Protein A chromatographic medium. Its dynamic binding capacity was 61 mg immunoglobulin G/mL suction-dried gel, increased by 24% compared with that of the non-grafted medium. The binding capacity of dextran-grafted medium decreased about 7% after 40 cleaning-in-place cycles, much lower than that of the non-grafted medium as decreased about 15%. Confocal laser scanning microscopy results showed that immunoglobulin G was bound to both the outside and the inside of dextran-grafted medium faster than that of non-grafted one. Atomic force microscopy showed that this dextran-grafted Protein A medium had much rougher surface with a vertical coordinate range of ±80 nm, while that of non-grafted one was ±10 nm. Grafted dextran provided a more stereo surface morphology and immunoglobulin G molecules were more easily to be bound. This high-performance dextran-grafted Protein A affinity chromatographic medium has promising applications in large-scale antibody purification. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Using a verbal prompt to increase protein consumption in a hospital setting: a field study

NARCIS (Netherlands)

Zanden, van der L.D.T.; Essen, van H.; Kleef, van E.; Wijk, de R.A.; Trijp, van J.C.M.

2015-01-01

Background: Sufficient protein intake among hospitalized patients may contribute to faster recovery and a decrease in healthcare costs. Nevertheless, hospitalized patients are often found to consume too little protein. This field study explored the success of a small, inexpensive intervention

Enhanced field emission properties of carbon nanotube bundles confined in SiO2 pits

Science.gov (United States)

Lim, Yu Dian; Grapov, Dmitry; Hu, Liangxing; Kong, Qinyu; Tay, Beng Kang; Labunov, Vladimir; Miao, Jianmin; Coquet, Philippe; Aditya, Sheel

2018-02-01

It has been widely reported that carbon nanotubes (CNTs) exhibit superior field emission (FE) properties due to their high aspect ratios and unique structural properties. Among the various types of CNTs, random growth CNTs exhibit promising FE properties due to their reduced inter-tube screening effect. However, growing random growth CNTs on individual catalyst islands often results in spread out CNT bundles, which reduces overall field enhancement. In this study, significant improvement in FE properties in CNT bundles is demonstrated by confining them in microfabricated SiO2 pits. Growing CNT bundles in narrow (0.5 μm diameter and 2 μm height) SiO2 pits achieves FE current density of 1-1.4 A cm-2, which is much higher than for freestanding CNT bundles (76.9 mA cm-2). From the Fowler Nordheim plots, confined CNT bundles show a higher field enhancement factor. This improvement can be attributed to the reduced bundle diameter by SiO2 pit confinement, which yields bundles with higher aspect ratios. Combining the obtained outcomes, it can be conclusively summarized that confining CNTs in SiO2 pits yields higher FE current density due to the higher field enhancement of confined CNTs.

Generalized monitor unit calculation for the Varian enhanced dynamic wedge field

International Nuclear Information System (INIS)

Liu Chihray; Kim, Siyong; Kahler, Darren L.; Palta, Jatinder R.

2003-01-01

The generalized monitor unit (MU) calculation equation for the Varian enhanced dynamic wedge (EDW) is derived. The assumption of this MU calculation method is that the wedge factor of the EDW at the center of the field is a function of field size, the position of the center of the field in the wedge direction, and the final position of the moving jaw. The wedge factors at the center of the field in both symmetric and asymmetric fields are examined. The difference between calculated and measured wedge factors is within 1.0%. The method developed here is easy to implement. The only datum required in addition to the standard set of conventional physical wedge implementation data is the off-axis output factor for the open field in the reference condition. The off-center point calculation is also examined. For the off-center point calculation, the dose profile in the wedge direction for the largest EDW field is used to obtain the relative off-center ratio in any smaller wedge field. The accuracy of the off-center point calculation decreases when the point of calculation is too close to the field edge

A novel cold-inducible zinc finger protein from soybean, SCOF-1, enhances cold tolerance in transgenic plants.

Science.gov (United States)

Kim, J C; Lee, S H; Cheong, Y H; Yoo, C M; Lee, S I; Chun, H J; Yun, D J; Hong, J C; Lee, S Y; Lim, C O; Cho, M J

2001-02-01

Cold stress on plants induces changes in the transcription of cold response genes. A cDNA clone encoding C2H2-type zinc finger protein, SCOF-1, was isolated from soybean. The transcription of SCOF-1 is specifically induced by low temperature and abscisic acid (ABA) but not by dehydration or high salinity. Constitutive overexpression of SCOF-1 induced cold-regulated (COR) gene expression and enhanced cold tolerance of non-acclimated transgenic Arabidopsis and tobacco plants. SCOF-1 localized to the nucleus but did not bind directly to either C-repeat/dehydration (CRT/DRE) or ABA responsive element (ABRE), cis-acting DNA regulatory elements present in COR gene promoters. However, SCOF-1 greatly enhanced the DNA binding activity of SGBF-1, a soybean G-box binding bZIP transcription factor, to ABRE in vitro. SCOF-1 also interacted with SGBF-1 in a yeast two-hybrid system. The SGBF-1 transactivated the beta-glucuronidase reporter gene driven by the ABRE element in Arabidopsis leaf protoplasts. Furthermore, the SCOF-1 enhanced ABRE-dependent gene expression mediated by SGBF-1. These results suggest that SCOF-1 may function as a positive regulator of COR gene expression mediated by ABRE via protein-protein interaction, which in turn enhances cold tolerance of plants.

The HIV1 protein Vpr acts to enhance constitutive DCAF1-dependent UNG2 turnover.

Directory of Open Access Journals (Sweden)

Xiaoyun Wen

Full Text Available The HIV1 protein Vpr assembles with and acts through an ubiquitin ligase complex that includes DDB1 and cullin 4 (CRL4 to cause G2 cell cycle arrest and to promote degradation of both uracil DNA glycosylase 2 (UNG2 and single-strand selective mono-functional uracil DNA glycosylase 1 (SMUG1. DCAF1, an adaptor protein, is required for Vpr-mediated G2 arrest through the ubiquitin ligase complex. In work described here, we used UNG2 as a model substrate to study how Vpr acts through the ubiquitin ligase complex. We examined whether DCAF1 is essential for Vpr-mediated degradation of UNG2 and SMUG1. We further investigated whether Vpr is required for recruiting substrates to the ubiquitin ligase or acts to enhance its function and whether this parallels Vpr-mediated G2 arrest.We found that DCAF1 plays an important role in Vpr-independent UNG2 and SMUG1 depletion. UNG2 assembled with the ubiquitin ligase complex in the absence of Vpr, but Vpr enhanced this interaction. Further, Vpr-mediated enhancement of UNG2 degradation correlated with low Vpr expression levels. Vpr concentrations exceeding a threshold blocked UNG2 depletion and enhanced its accumulation in the cell nucleus. A similar dose-dependent trend was seen for Vpr-mediated cell cycle arrest.This work identifies UNG2 and SMUG1 as novel targets for CRL4(DCAF1-mediated degradation. It further shows that Vpr enhances rather than enables the interaction between UNG2 and the ubiquitin ligase. Vpr augments CRL4(DCAF1-mediated UNG2 degradation at low concentrations but antagonizes it at high concentrations, allowing nuclear accumulation of UNG2. Further, the protein that is targeted to cause G2 arrest behaves much like UNG2. Our findings provide the basis for determining whether the CRL4(DCAF1 complex is alone responsible for cell cycle-dependent UNG2 turnover and will also aid in establishing conditions necessary for the identification of additional targets of Vpr-enhanced degradation.

Observation of enhanced field-free molecular alignment by two laser pulses

DEFF Research Database (Denmark)

Bisgaard, Christer; Poulsen, Mikael Dahlerup; Peronne, Emmanuel

2004-01-01

We show experimentally that field-free alignment of iodobenzene molecules, induced by a single, intense, linearly polarized 1.4-ps-long laser pulse, can be strongly enhanced by dividing the pulse into two optimally synchronized pulses of the same duration. For a given total energy of the two...

Towards phonon photonics: scattering-type near-field optical microscopy reveals phonon-enhanced near-field interaction

International Nuclear Information System (INIS)

Hillenbrand, Rainer

2004-01-01

Diffraction limits the spatial resolution in classical microscopy or the dimensions of optical circuits to about half the illumination wavelength. Scanning near-field microscopy can overcome this limitation by exploiting the evanescent near fields existing close to any illuminated object. We use a scattering-type near-field optical microscope (s-SNOM) that uses the illuminated metal tip of an atomic force microscope (AFM) to act as scattering near-field probe. The presented images are direct evidence that the s-SNOM enables optical imaging at a spatial resolution on a 10 nm scale, independent of the wavelength used (λ=633 nm and 10 μm). Operating the microscope at specific mid-infrared frequencies we found a tip-induced phonon-polariton resonance on flat polar crystals such as SiC and Si 3 N 4 . Being a spectral fingerprint of any polar material such phonon-enhanced near-field interaction has enormous applicability in nondestructive, material-specific infrared microscopy at nanoscale resolution. The potential of s-SNOM to study eigenfields of surface polaritons in nanostructures opens the door to the development of phonon photonics--a proposed infrared nanotechnology that uses localized or propagating surface phonon polaritons for probing, manipulating and guiding infrared light in nanoscale devices, analogous to plasmon photonics

Direct spectroscopic evidence for competition between thermal molecular agitation and magnetic field in a tetrameric protein in aqueous solution

Science.gov (United States)

Calabrò, Emanuele; Magazù, Salvatore

2018-05-01

Samples of a typical tetrameric protein, the hemoglobin, at the concentration of 150 mg/ml in bidistilled water solution, were exposed to a uniform magnetic field at 200 mT at different temperatures of 15∘C, 40∘C and 65∘C. Fourier Transform Infrared Spectroscopy was used to analyze the response of the secondary structure of the protein to both stress agents, heating and static magnetic field. The most relevant result which was observed was the significant increasing in intensity of the Amide I band after exposure to the uniform magnetic field at the room temperature of 15∘C. This result can be explained assuming that protein's α-helices aligned along the direction of the applied magnetic field due to their large dipole moment, inducing the alignment of the entire protein. Increasing of temperature up to 40∘C and 65∘C induced a significant reduction of the increasing in intensity of the Amide I band. This effect may be easily explained assuming that Brownian motion of the protein in water solution caused by thermal molecular agitation increased with increasing of temperature, contrasting the effect of the torque of the magnetic field applied to the protein in water solution.

Balancing Near-Field Enhancement, Absorption, and Scattering for Effective Antenna-Reactor Plasmonic Photocatalysis.

Science.gov (United States)

Li, Kun; Hogan, Nathaniel J; Kale, Matthew J; Halas, Naomi J; Nordlander, Peter; Christopher, Phillip

2017-06-14

Efficient photocatalysis requires multifunctional materials that absorb photons and generate energetic charge carriers at catalytic active sites to facilitate a desired chemical reaction. Antenna-reactor complexes are an emerging multifunctional photocatalytic structure where the strong, localized near field of the plasmonic metal nanoparticle (e.g., Ag) is coupled to the catalytic properties of the nonplasmonic metal nanoparticle (e.g., Pt) to enable chemical transformations. With an eye toward sustainable solar driven photocatalysis, we investigate how the structure of antenna-reactor complexes governs their photocatalytic activity in the light-limited regime, where all photons need to be effectively utilized. By synthesizing core@shell/satellite (Ag@SiO 2 /Pt) antenna-reactor complexes with varying Ag nanoparticle diameters and performing photocatalytic CO oxidation, we observed plasmon-enhanced photocatalysis only for antenna-reactor complexes with antenna components of intermediate sizes (25 and 50 nm). Optimal photocatalytic performance was shown to be determined by a balance between maximized local field enhancements at the catalytically active Pt surface, minimized collective scattering of photons out of the catalyst bed by the complexes, and minimal light absorption in the Ag nanoparticle antenna. These results elucidate the critical aspects of local field enhancement, light scattering, and absorption in plasmonic photocatalyst design, especially under light-limited illumination conditions.

Sub-microanalysis of solid samples with near-field enhanced atomic emission spectroscopy

Science.gov (United States)

Wang, Xiaohua; Liang, Zhisen; Meng, Yifan; Wang, Tongtong; Hang, Wei; Huang, Benli

2018-03-01

A novel approach, which we have chosen to name it as near-field enhanced atomic emission spectroscopy (NFE-AES), was proposed by introducing a scanning tunnelling microscope (STM) system into a laser-induced breakdown spectrometry (LIBS). The near-field enhancement of a laser-illuminated tip was utilized to improve the lateral resolution tremendously. Using the hybrid arrangement, pure metal tablets were analyzed to verify the performance of NFE-AES both in atmosphere and in vacuum. Due to localized surface plasmon resonance (LSPR), the incident electromagnetic field is enhanced and confined at the apex of tip, resulting in sub-micron scale ablation and elemental emission signal. We discovered that the signal-to-noise ratio (SNR) and the spectral resolution obtained in vacuum condition are better than those acquired in atmospheric condition. The quantitative capability of NFE-AES was demonstrated by analyzing Al and Pb in Cu matrix, respectively. Submicron-sized ablation craters were achieved by performing NFE-AES on a Si wafer with an Al film, and the spectroscopic information from a crater of 650 nm diameter was successfully obtained. Due to its advantage of high lateral resolution, NFE-AES imaging of micro-patterned Al lines on an integrated circuit of a SIM card was demonstrated with a sub-micron lateral resolution. These results reveal the potential of the NFE-AES technique in sub-microanalysis of solids, opening an opportunity to map chemical composition at sub-micron scale.

Tumor protein 53-induced nuclear protein 1 (TP53INP1 enhances p53 function and represses tumorigenesis

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Jeyran eShahbazi

2013-05-01

Full Text Available Tumor protein 53-induced nuclear protein 1 (TP53INP1 is a stress-induced p53 target gene whose expression is modulated by transcription factors such as p53, p73 and E2F1. TP53INP1 gene encodes two isoforms of TP53INP1 proteins, TP53INP1α and TP53INP1β, both of which appear to be key elements in p53 function. When associated with homeodomain-interacting protein kinase-2 (HIPK2, TP53INP1 phosphorylates p53 protein at Serine 46, enhances p53 protein stability and its transcriptional activity, leading to transcriptional activation of p53 target genes such as p21, PIG-3 and MDM2, cell growth arrest and apoptosis upon DNA damage stress. The anti-proliferative and pro-apoptotic activities of TP53INP1 indicate that TP53INP1 has an important role in cellular homeostasis and DNA damage response. Deficiency in TP53INP1 expression results in increased tumorigenesis; while TP53INP1 expression is repressed during early stages of cancer by factors such as miR-155. This review aims to summarize the roles of TP53INP1 in blocking tumor progression through p53-dependant and p53-independent pathways, as well as the elements which repress TP53INP1 expression, hence highlighting its potential as a therapeutic target in cancer treatment.

Amagnetic field-enhanced filtration/sorption Device and its potential for inexpensive water and wastewater treatment

International Nuclear Information System (INIS)

Navratil, J.D.

2000-01-01

A magnetic field-enhanced filtration/sorption device is described for removal of radioactive and heavy metals from water and wastewater. The device consists of a column of supported magnetite surrounded by a movable permanent magnet. The mineral magnetite, or synthetically prepared iron ferrite (Fe O Fe 2 O 3 ), is typically supported on various materials to permit adequate water passage through the column. In the presence of the external magnetic field, enhanced capacity was observed in using supported magnetite for removal of actinides and heavy metals from wastewater. The enhanced capacity is primarily due to magnetic filtration of colloidal and submicron particles along with some complex and ion exchange sorption mechanisms. The loaded magnetite can easily be regenerated by the removal of the magnetic field and use of a regenerating solution. This paper will review previous work on the use of iron oxides for wastewater treatment and discuss the development and potential of the magnetic filtration/sorption process for water and wastewater treatment

Involvement of protein kinase C in the modulation of morphine-induced analgesia and the inhibitory effects of exposure to 60-hz magnetic fields in the land snail, Cepaea nemoralis

Energy Technology Data Exchange (ETDEWEB)

Kavaliers, M.; Ossenkopp, K.P. (Univ. of Western Ontario, London (Canada))

1990-02-26

One of the more consistent and dramatic effects of exposure to magnetic fields is the attenuation of morphine-induced analgesia. Results of previous studies have implicated alterations in calcium channel functioning and Ca{sup ++} flux in the mediation of these effects. It is generally accepted that Ca{sup ++}-activated-phospholipid-dependent protein kinase (Protein kinase C; PKC) plays an important role in relaying trans-membrane signaling in diverse Ca{sup ++} dependent cellular processes. In experiment 1 we observed that morphine-induced analgesia in the land snail, Cepaea nemoralis, as measured by the latency of an avoidance behavior to a warmed surface, was reduced by the PKC activator, SC-9, and was enhanced by the PKC inhibitors, H-7 and H-9. In contrast, HA-10004, a potent inhibitor of other protein kinases, but only a very weak inhibitor of PKC, had no effect on morphine-induced analgesia. In experiment 2 exposure of snails for 30 minutes to a 1.0 gauss (rms) 60-Hz magnetic field reduced morphine-induced analgesia. This inhibitory effect of the magnetic field was reduced by the PKC inhibitors, H-7 and H-9, and was augmented by the PKC activator SC-9. These results suggest that: (i) PKC is involved in the modulation of morphine-induced analgesia and, (ii) the inhibitory effects of magnetic fields involve PKC.

Band-to-Band Tunneling-Dominated Thermo-Enhanced Field Electron Emission from p-Si/ZnO Nanoemitters.

Science.gov (United States)

Huang, Zhizhen; Huang, Yifeng; Xu, Ningsheng; Chen, Jun; She, Juncong; Deng, Shaozhi

2018-06-13

Thermo-enhancement is an effective way to achieve high performance field electron emitters, and enables the individually tuning on the emission current by temperature and the electron energy by voltage. The field emission current from metal or n-doped semiconductor emitter at a relatively lower temperature (i.e., current saturation was observed in the thermo-enhanced field emission measurements. The emission current density showed about ten-time enhancement (from 1.31 to 12.11 mA/cm 2 at 60.6 MV/m) by increasing the temperature from 323 to 623 K. The distinctive performance did not agree with the interband excitation mechanism but well-fit to the band-to-band tunneling model. The strong thermo-enhancement was proposed to be benefit from the increase of band-to-band tunneling probability at the surface portion of the p-Si/ZnO nanojunction. This work provides promising cathode for portable X-ray tubes/panel, ionization vacuum gauges and low energy electron beam lithography, in where electron-dose control at a fixed energy is needed.

Carbon nanotubes-assisted polyacrylamide gel electrophoresis for enhanced separation of human serum proteins and application in liverish diagnosis.

Science.gov (United States)

Jiang, Fubin; Wang, Yanan; Hu, Xinfang; Shao, Na; Na, Na; Delanghe, Joris R; Ouyang, Jin

2010-11-01

The application of pore-gradient polyacrylamide gel electrophoresis (PG-PAGE) incorporated with carbon nanotube modified by Triton X-100 and carboxylation so as to improve the separation of human serum proteins is reported. The novel PG-PAGE was made by adding water-soluble single-walled carbon nanotubes (CNTs) when preparing the polyacrylamide gel. Significant improvements in separation of complement C3 protein and haptoglobin (Hp) in human serum were achieved. It was estimated that the interactions between the hydrophilic groups on the proteins and the surface of the CNTs result in different adsorption kinetics of complement C3 and Hp subtype on the nanoparticles incorporated in the gel, thus enhancing the separation of the two proteins in serum. This new CNT matrix-assisted PG-PAGE method for enhanced separation of complement C3 and Hp in human serum was successfully applied to distinguish the samples from liverish patients and healthy people.

Enhancing Membrane Protein Identification Using a Simplified Centrifugation and Detergent-Based Membrane Extraction Approach.

Science.gov (United States)

Zhou, Yanting; Gao, Jing; Zhu, Hongwen; Xu, Jingjing; He, Han; Gu, Lei; Wang, Hui; Chen, Jie; Ma, Danjun; Zhou, Hu; Zheng, Jing

2018-02-20

Membrane proteins may act as transporters, receptors, enzymes, and adhesion-anchors, accounting for nearly 70% of pharmaceutical drug targets. Difficulties in efficient enrichment, extraction, and solubilization still exist because of their relatively low abundance and poor solubility. A simplified membrane protein extraction approach with advantages of user-friendly sample processing procedures, good repeatability and significant effectiveness was developed in the current research for enhancing enrichment and identification of membrane proteins. This approach combining centrifugation and detergent along with LC-MS/MS successfully identified higher proportion of membrane proteins, integral proteins and transmembrane proteins in membrane fraction (76.6%, 48.1%, and 40.6%) than in total cell lysate (41.6%, 16.4%, and 13.5%), respectively. Moreover, our method tended to capture membrane proteins with high degree of hydrophobicity and number of transmembrane domains as 486 out of 2106 (23.0%) had GRAVY > 0 in membrane fraction, 488 out of 2106 (23.1%) had TMs ≥ 2. It also provided for improved identification of membrane proteins as more than 60.6% of the commonly identified membrane proteins in two cell samples were better identified in membrane fraction with higher sequence coverage. Data are available via ProteomeXchange with identifier PXD008456.

Enhancer-binding proteins with a forkhead-associated domain and the sigma(54) regulon in Myxococcus xanthus fruiting body development

DEFF Research Database (Denmark)

Jelsbak, Lars; Givskov, Michael Christian; Kaiser, D.

2005-01-01

-binding proteins. Here we report the finding of an unusual group of 12 genes encoding sigma(54)-dependent enhancer-binding proteins containing a forkhead-associated (FHA) domain as their N-terminal sensory domain. FHA domains in other proteins recognize phosphothreonine residues. An insertion mutation in one...... donor cell. Because FHA domains respond to phosphothreonine-containing proteins, these results suggest a regulatory link to the abundant Ser/Thr protein kinases in M. xanthus....

Studies on Some Biophysical Properties of the Serum Protein of Mice blood exposed to an electric field

International Nuclear Information System (INIS)

Hanafy, M.S.

2005-01-01

As an indication of the effect of the electric field on each of the dielectric properties and the molecular structure of the serum protein of the mice blood, an electric field of a 6 kv/m strength and 50 Hz frequency was directed to three groups of mice for exposure periods 30, 45 and 60 days respectively, and investigated directly. Another group was exposed to also 60 days, but investigated after 30 days from switching off the electric field for delayed effect studies. The molecular structure of the serum protein was studied by measuring each of the dielectric relaxation and the electric conductivity in the frequency range 0.15 MHz at 4 ± 0.5 degree C and the dielectric increment (Δ), relaxation time (τ) and average molecular radii (τ) were calculated for all groups. The absorption spectra of the extracted protein were also measured in the wavelength range 200 600 nm. Moreover, electrophoresis of enzymes B-esterase, lactate and Malate dehydrogenase extracted from the blood serum of exposed mice were taken by using the gel electrophoresis technique. The results indicated that exposure of the animals to 50 H, 6 kv/m electric field resulted in the decrease of serum protein permittivity values and increase its conductivity a fact that indicates pronounced changes in the molecular structure of total serum protein the exposed mice. In addition, the intensity of the absorption spectral bands of serum protein of exposed mice were found to decrease relative to unexposed mice. Also the enzymes B-esterase and lactate dehydrogenase were slightly affected by exposing to the electric field whereas their number of bands and their intensities changed relative to the unexposed mice but the malate dehydrogenase was not affected

Experimental Demonstration of Anomalous Field Enhancement in All-Dielectric Transition Magnetic Metamaterials.

Science.gov (United States)

Sun, Jingbo; Liu, Xiaoming; Zhou, Ji; Kudyshev, Zhaxylyk; Litchinitser, Natalia M

2015-11-04

Anomalous field enhancement accompanied by resonant absorption phenomenon was originally discussed in the context of plasma physics and in applications related to radio-communications between the ground and spacecraft returning to Earth. Indeed, there is a critical period of time when all communications are lost due to the reflection/absorption of electromagnetic waves by the sheath of plasma created by a high speed vehicle re-entering the atmosphere. While detailed experimental studies of these phenomena in space are challenging, the emergence of electromagnetic metamaterials enables researchers exceptional flexibility to study them in the laboratory environment. Here, we experimentally demonstrated the strong localized field enhancement of magnetic field for an electromagnetic wave propagating in Mie-resonance-based inhomogeneous metamaterials with magnetic permeability gradually changing from positive to negative values. Although these experiments were performed in the microwave frequency range, the proposed all-dielectric approach to transition metamaterials can be extended to terahertz, infrared, and visible frequencies. We anticipate that these results, besides most basic science aspects, hold the potential for numerous applications, including low-intensity nonlinear transformation optics, topological photonics, and the broader area of surface and interface science.

Effects on DPPH inhibition of egg-white protein polypeptides treated by pulsed electric field technology.

Science.gov (United States)

Wang, Ke; Wang, Jia; Liu, Bolong; Lin, Songyi; Zhao, Ping; Liu, Jingbo; Jones, Gregory; Huang, Hsiang-Chi

2013-05-01

Egg-white protein polypeptides are potentially used as a functional ingredient in food products. In this study, the effects on DPPH inhibition of egg-white protein polypeptides ranging from 10 to 30 kDa treated by pulsed electric field (PEF) technology were investigated. 2, 2-Diphenyl-1-picrylhydrazyl (DPPH) inhibition (%) was used to evaluate the antioxidant activity of polypeptides. In order to develop and optimize a pulsed electric field (PEF) mathematical model for improving the antioxidant activity, we have investigated three variables, including concentration (6, 8 and 10 mg mL(-1)), electric field intensity (10, 20 and 30 kV cm(-1)) and pulse frequency (2000, 2350 and 2700 Hz) and subsequently optimized them by response surface methodology (RSM). The concentration (8 mg mL(-1)), electric field intensity (10 kV cm(-1)) and pulse frequency (2000 Hz) were found to be the optimal conditions under which the DPPH inhibition increased 28.44%, compared to the sample without PEF treatment. Both near-infrared spectroscopy (NIR) and mid-infrared spectroscopy (MIR) were used to analyze the change of functional groups. The results showed that PEF technology could improve the antioxidant activity of antioxidant polypeptides from egg-white protein under the optimized conditions. © 2012 Society of Chemical Industry.

Topology Optimized Nanostrips for Electric Field Enhancements

DEFF Research Database (Denmark)

Vester-Petersen, Joakim; Christiansen, Rasmus E.; Julsgaard, Brian

This work addresses efficiency improvements of solar cells by manipulating the spectrum of sunlight to bettermatch the range of efficient current generation. The intrinsic transmission losses in crystalline silicon can effectivelybe reduced using photon upconversion in erbium ions in which low...... energy photons are converted to higher energy photons able to bridge the band gap energy and contribute the energy generation. The upconversion process in erbium is inefficient under the natural solar irradiation, and without any electric field enhancements of the incident light, the process...... is negligible for photo-voltaic applications. However, the probability for upconversion can be increased by focusing the incident light onto the erbium ions using optimized metal nanostructures[1, 2, 3]. The aim of this work is to increase the photon upconversion yield by optimizing the design of metalic...

Protein 8-class secondary structure prediction using conditional neural fields.

Science.gov (United States)

Wang, Zhiyong; Zhao, Feng; Peng, Jian; Xu, Jinbo

2011-10-01

Compared with the protein 3-class secondary structure (SS) prediction, the 8-class prediction gains less attention and is also much more challenging, especially for proteins with few sequence homologs. This paper presents a new probabilistic method for 8-class SS prediction using conditional neural fields (CNFs), a recently invented probabilistic graphical model. This CNF method not only models the complex relationship between sequence features and SS, but also exploits the interdependency among SS types of adjacent residues. In addition to sequence profiles, our method also makes use of non-evolutionary information for SS prediction. Tested on the CB513 and RS126 data sets, our method achieves Q8 accuracy of 64.9 and 64.7%, respectively, which are much better than the SSpro8 web server (51.0 and 48.0%, respectively). Our method can also be used to predict other structure properties (e.g. solvent accessibility) of a protein or the SS of RNA. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhanced colon cancer chemoprevention of curcumin by nanoencapsulation with whey protein.

Science.gov (United States)

Jayaprakasha, Guddadarangavvanahally K; Chidambara Murthy, Kotamballi N; Patil, Bhimanagouda S

2016-10-15

To improve bioavailability and enhance colon cancer prevention ability of curcumin, whey protein was used to nanoencapsulate at three different ratios such as 70:30, 50:50 and 35:65 for the first time. The drug loading, entrapment efficiency and structural changes of curcumin was confirmed by quantitative NMR spectroscopy. The nanoparticles prepared using the three ratios had an average diameters of 236.5±8.8, 212±3.4, and 187±11.4nm, as well as zeta (ζ) potentials of -13.1,-9.26, and -4.63mV, respectively, at pH 7.0. The cytotoxicity assay was performed for human colon and prostate cancer (SW480 and LNCap) by MTT assay and results showed significantly higher cytotoxicity of nanoencapsulated curcumin (NEC) (equivalent to 30.91, 20.70 and 16.86µM of NEC-1, 2 and 3 respectively), as compared to plain curcumin at 50µM after 72h of treatment. Cytotoxicity was also confirmed by microscopy of treated cells stained with acridine orange and propidium iodide. The cells treated with 50µM of curcumin, 30.91µM (NEC-1), 20.70µM (NEC-2) and 16.86µM (NEC-3) showed enhanced activation of p53 and elevated bax/Bcl2 expression (NEC-3), increased cytochrome-c in cytosol (NEC-2) confirming the enhanced cytotoxicity. To confirm the increased bioavailability, the intracellular curcumin was measured using fluorescence intensity. The fluorescent signal for intracellular curcumin was increased by 12, 30, and 21% for NEC-1, NEC-2, and NEC-3 respectively as compared to plain curcumin at 4h. Based on these results, we conclude that nanoencapsulated curcumin with whey protein will have potential to be considered for clinical applications for future studies. Copyright © 2016 Elsevier B.V. All rights reserved.

Fatty-acid binding proteins modulate sleep and enhance long-term memory consolidation in Drosophila.

Directory of Open Access Journals (Sweden)

Jason R Gerstner

2011-01-01

Full Text Available Sleep is thought to be important for memory consolidation, since sleep deprivation has been shown to interfere with memory processing. However, the effects of augmenting sleep on memory formation are not well known, and testing the role of sleep in memory enhancement has been limited to pharmacological and behavioral approaches. Here we test the effect of overexpressing the brain-type fatty acid binding protein (Fabp7 on sleep and long-term memory (LTM formation in Drosophila melanogaster. Transgenic flies carrying the murine Fabp7 or the Drosophila homologue dFabp had reduced baseline sleep but normal LTM, while Fabp induction produced increases in both net sleep and LTM. We also define a post-training consolidation "window" that is sufficient for the observed Fabp-mediated memory enhancement. Since Fabp overexpression increases consolidated daytime sleep bouts, these data support a role for longer naps in improving memory and provide a novel role for lipid-binding proteins in regulating memory consolidation concurrently with changes in behavioral state.

Numerical simulation of positive streamer development in thundercloud field enhanced near raindrops

DEFF Research Database (Denmark)

Babich, L. P.; Bochkov, E. I.; Kutsyk, I. M.

2016-01-01

As the threshold field strength for the breakdown in air significantly exceeds the maximum measured thundercloud strength 3 kV/cm/atm, the problem of lightning initiation remains unclear. According to the popular idea, lightning can be initiated from streamer discharges developed in the enhanced...

CCAAT/enhancer-binding proteins regulate expression of the human steroidogenic acute regulatory protein (StAR) gene.

Science.gov (United States)

Christenson, L K; Johnson, P F; McAllister, J M; Strauss, J F

1999-09-10

Two putative CCAAT/enhancer-binding protein (C/EBP) response elements were identified in the proximal promoter of the human steroidogenic acute regulatory protein (StAR) gene, which encodes a key protein-regulating steroid hormone synthesis. Expression of C/EBPalpha and -beta increased StAR promoter activity in COS-1 and HepG2 cells. Cotransfection of C/EBPalpha or -beta and steroidogenic factor 1, a transcription factor required for cAMP regulation of StAR expression, into COS-1 augmented 8-bromoadenosine 3':5'-cyclic monophosphate (8-Br-cAMP)-stimulated promoter activity. When the putative C/EBP response elements were mutated, individually or together, a pronounced decline in basal StAR promoter activity in human granulosa-lutein cells resulted, but the fold stimulation of promoter activity by 8-Br-cAMP was unaffected. Recombinant C/EBPalpha and -beta bound to the two identified sequences but not the mutated elements. Human granulosa-lutein cell nuclear extracts also bound these elements but not the mutated sequences. An antibody to C/EBPbeta, but not C/EBPalpha, supershifted the nuclear protein complex associated with the more distal element. The complex formed by nuclear extracts with the proximal element was not supershifted by either antibody. Western blot analysis revealed the presence of C/EBPalpha and C/EBPbeta in human granulosa-lutein cell nuclear extracts. C/EBPbeta levels were up-regulated 3-fold by 8-Br-cAMP treatment. Our studies demonstrate a role for C/EBPbeta as well as yet to be identified proteins, which can bind to C/EBP response elements, in the regulation of StAR gene expression and suggest a mechanism by which C/EBPbeta participates in the cAMP regulation of StAR gene transcription.

Salivary protein histatin 3 regulates cell proliferation by enhancing p27{sup Kip1} and heat shock cognate protein 70 ubiquitination

Energy Technology Data Exchange (ETDEWEB)

Imamura, Yasuhiro, E-mail: yimamura@po.mdu.ac.jp [Department of Pharmacology, Matsumoto Dental University, Shiojiri, Nagano 399-0781 (Japan); Wang, Pao-Li [Department of Bacteriology, Osaka Dental University, Hirakata, Osaka 573-1121 (Japan); Masuno, Kazuya [Department of Dental Education Innovation, Osaka Dental University, Hirakata, Osaka 573-1121 (Japan); Sogawa, Norio [Department of Pharmacology, Matsumoto Dental University, Shiojiri, Nagano 399-0781 (Japan)

2016-02-05

Histatins are salivary proteins with antimicrobial activities. We previously reported that histatin 3 binds to heat shock cognate protein 70 (HSC70), which is constitutively expressed, and induces DNA synthesis stimulation and promotes human gingival fibroblast (HGF) survival. However, the underlying mechanisms of histatin 3 remain largely unknown. Here, we found that the KRHH sequence of histatin 3 at the amino acid positions 5–8 was essential for enhancing p27{sup Kip1} (a cyclin-dependent kinase inhibitor) binding to HSC70 that occurred in a dose-dependent manner; histatin 3 enhanced the binding between p27{sup Kip1} and HSC70 during the G{sub 1}/S transition of HGFs as opposed to histatin 3-M(5–8) (substitution of KRHH for EEDD in histatin 3). Histatin 3, but not histatin 3-M(5–8), stimulated DNA synthesis and promoted HGF survival. Histatin 3 dose-dependently enhanced both p27{sup Kip1} and HSC70 ubiquitination, whereas histatin 3-M(5–8) did not. These findings provide further evidence that histatin 3 may be involved in the regulation of cell proliferation, particularly during G{sub 1}/S transition, via the ubiquitin–proteasome system of p27{sup Kip1} and HSC70. - Highlights: • KRHH amino acid sequence was required in histatin 3 to bind HSC70. • Histatin 3 enhanced HSC70 binding to p27{sup Kip1} during the G{sub 1}/S transition in HGFs. • KRHH sequence stimulated DNA synthesis and promoted cell survival. • Histatin 3 dose-dependently enhanced both p27{sup Kip1} and HSC70 ubiquitination. • Histatin 3 stimulates cell proliferation via the ubiquitin–proteasome system.

Ester carbonyl vibration as a sensitive probe of protein local electric field.

Science.gov (United States)

Pazos, Ileana M; Ghosh, Ayanjeet; Tucker, Matthew J; Gai, Feng

2014-06-10

The ability to quantify the local electrostatic environment of proteins and protein/peptide assemblies is key to gaining a microscopic understanding of many biological interactions and processes. Herein, we show that the ester carbonyl stretching vibration of two non-natural amino acids, L-aspartic acid 4-methyl ester and L-glutamic acid 5-methyl ester, is a convenient and sensitive probe in this regard, since its frequency correlates linearly with the local electrostatic field for both hydrogen-bonding and non-hydrogen-bonding environments. We expect that the resultant frequency-electric-field map will find use in various applications. Furthermore, we show that, when situated in a non-hydrogen-bonding environment, this probe can also be used to measure the local dielectric constant (ε). For example, its application to amyloid fibrils formed by Aβ(16-22) revealed that the interior of such β-sheet assemblies has an ε value of approximately 5.6. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Using modified soy protein to enhance foaming of egg white protein.

Science.gov (United States)

Wang, Guang; Troendle, Molly; Reitmeier, Cheryll A; Wang, Tong

2012-08-15

It is well known that the foaming properties of egg white protein are significantly reduced when a small amount of yolk is mixed in the white. To improve foaming properties of yolk-contaminated egg white protein, soy protein isolate (SPI) and egg proteins were modified to make basic proteins, and effects of these modified proteins on egg white foaming were evaluated in a model and an angel cake system. SPI and egg yolk proteins were modified to have an isoelectric point of 10, and sonication was used to increase protein dispersibility after the ethyl esterification reaction. However, only the addition of sonicated and modified SPI (SMSPI) showed improvement of foaming in the 5% egg protein model system with 0.4% yolk addition. SMSPI was then used in making angel food cake to examine whether the cake performance reduction due to yolk contamination of the white would be restored by such alkaline protein. Cake performance was improved when cream of tartar was used together with SMSPI. Basic soy protein can be made and used to improve egg white foaming properties and cake performance. Copyright © 2012 Society of Chemical Industry.

Field-induced stacking transition of biofunctionalized trilayer graphene

Energy Technology Data Exchange (ETDEWEB)

Masato Nakano, C. [Flintridge Preparatory School, La Canada, California 91011 (United States); Sajib, Md Symon Jahan; Samieegohar, Mohammadreza; Wei, Tao [Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont, Texas 77710 (United States)

2016-02-01

Trilayer graphene (TLG) is attracting a lot of attention as their stacking structures (i.e., rhombohedral vs. Bernal) drastically affect electronic and optical properties. Based on full-atom molecular dynamics simulations, we here predict electric field-induced rhombohedral-to-Bernal transition of TLG tethered with proteins. Furthermore, our simulations show that protein's electrophoretic mobility and diffusivity are enhanced on TLG surface. This phenomenon of controllable TLG stacking transition will contribute to various applications including biosensing.

Development and Validation of an Enhanced Coupled-Field Model for PZT Cantilever Bimorph Energy Harvester

Directory of Open Access Journals (Sweden)

Long Zhang

2013-01-01

Full Text Available The power source with the limited life span has motivated the development of the energy harvesters that can scavenge the ambient environment energy and convert it into the electrical energy. With the coupled field characteristics of structure to electricity, piezoelectric energy harvesters are under consideration as a means of converting the mechanical energy to the electrical energy, with the goal of realizing completely self-powered sensor systems. In this paper, two previous models in the literatures for predicting the open-circuit and close-circuit voltages of a piezoelectric cantilever bimorph (PCB energy harvester are first described, that is, the mechanical equivalent spring mass-damper model and the electrical equivalent circuit model. Then, the development of an enhanced coupled field model for the PCB energy harvester based on another previous model in the literature using a conservation of energy method is presented. Further, the laboratory experiments are carried out to evaluate the enhanced coupled field model and the other two previous models in the literatures. The comparison results show that the enhanced coupled field model can better predict the open-circuit and close-circuit voltages of the PCB energy harvester with a proof mass bonded at the free end of the structure in order to increase the energy-harvesting level of the system.

Optical rectification using geometrical field enhancement in gold nano-arrays

Science.gov (United States)

Piltan, S.; Sievenpiper, D.

2017-11-01

Conversion of photons to electrical energy has a wide variety of applications including imaging, solar energy harvesting, and IR detection. A rectenna device consists of an antenna in addition to a rectifying element to absorb the incident radiation within a certain frequency range. We designed, fabricated, and measured an optical rectifier taking advantage of asymmetrical field enhancement for forward and reverse currents due to geometrical constraints. The gold nano-structures as well as the geometrical parameters offer enhanced light-matter interaction at 382 THz. Using the Taylor expansion of the time-dependent current as a function of the external bias and oscillating optical excitation, we obtained responsivities close to quantum limit of operation. This geometrical approach can offer an efficient, broadband, and scalable solution for energy conversion and detection in the future.

Thermo-enhanced field emission from ZnO nanowires: Role of defects and application in a diode flat panel X-ray source

Energy Technology Data Exchange (ETDEWEB)

Zhang, Zhipeng; Chen, Daokun; Chen, Wenqing; Chen, Yicong; Song, Xiaomeng; Zhan, Runze; Deng, Shaozhi; Xu, Ningsheng; Chen, Jun, E-mail: stscjun@mail.sysu.edu.cn

2017-03-31

Highlights: • A thermo-enhanced field emission phenomenon was observed from dendritic ZnO nanowires under the temperature of 323–723 K. • Defect-assisted field emission mechanism was proposed and quantitative calculation fits well with the experiment results. • The mechanism was verified by the field emission from ZnO nanowires with different defect concentrations. • A diode X-ray source making use of thermo-enhanced field emission phenomenon was proposed for separate tuning of dose and energy. - Abstract: A thermo-enhanced field emission phenomenon was observed from ZnO nanowires. The field emission current increased by almost two orders of magnitude under a constant applied electric field, and the turn-on field decreased from 6.04 MV/m to 5.0 MV/m when the temperature increased from 323 to 723 K. The Poole–Frenkel electron excitation from the defect-induced trapping centers to the conduction band under high electric fields is believed to be the primary cause of the observed phenomenon. The experimental results fit well with the proposed physical model. The field emission from ZnO nanowires with different defect concentrations further confirmed the role of defects. Using the thermo-enhanced field emission phenomenon, a diode flat panel X-ray source was demonstrated, for which the energy and dose can be separately tuned. The thermo-enhanced field emission phenomenon observed from ZnO nanowires could be an effective way to realize a large area flat panel multi-energy X-ray source.

Enhanced upper critical fields in binary Nb-Ti alloys

International Nuclear Information System (INIS)

Hariharan, Y.; Sastry, V.S.; Janawadkar, M.P.; Radhakrishnan, T.S.

1986-01-01

The authors report the enhancement of H/sub c2/ in quenched and suitably heat treated binary Nb-65 at % Ti alloys. The inherent metastability of the bcc β phase and its instability towards athermal ω are used to realise high values of normal state resistivity ε/sub n/. The consequences of this on the upper critical field have been experimentally determined by the measurement of dH/sub c2//dT at T/sub c/ and of T/sub c/. These together with our similar measurements on Nb-83 at % Ti alloy to which at 1 at % N was added (to retain it in the β phase) are analysed in terms of the existing theories for upper critical fields. It is shown that a peak in H/sub c2/(o) occurs at 17 - 18 T when ε/sub n/ has a value of approximately 100 μΩcm

An automated wide-field time-gated optically sectioning fluorescence lifetime imaging multiwell plate reader for high-content analysis of protein-protein interactions

Science.gov (United States)

Alibhai, Dominic; Kumar, Sunil; Kelly, Douglas; Warren, Sean; Alexandrov, Yuriy; Munro, Ian; McGinty, James; Talbot, Clifford; Murray, Edward J.; Stuhmeier, Frank; Neil, Mark A. A.; Dunsby, Chris; French, Paul M. W.

2011-03-01

We describe an optically-sectioned FLIM multiwell plate reader that combines Nipkow microscopy with wide-field time-gated FLIM, and its application to high content analysis of FRET. The system acquires sectioned FLIM images in fluorescent protein. It has been applied to study the formation of immature HIV virus like particles (VLPs) in live cells by monitoring Gag-Gag protein interactions using FLIM FRET of HIV-1 Gag transfected with CFP or YFP. VLP formation results in FRET between closely packed Gag proteins, as confirmed by our FLIM analysis that includes automatic image segmentation.

Feeding value of field pea as a protein source in forage-based diets fed to beef cattle.

Science.gov (United States)

Soto-Navarro, S A; Encinias, A M; Bauer, M L; Lardy, G P; Caton, J S

2012-02-01

Three studies were conducted to evaluate the feasibility of field peas as a protein source in diets for beef cattle. In the first study, 4 cultivars of field pea were incubated in situ to determine rate and extent of CP disappearance. Results indicate that field pea cultivars vary in CP content (22.6, 26.1, 22.6, and 19.4%, DM basis for Profi, Arvika, Carneval, and Trapper, respectively). Soluble protein fraction ranged from 34.9% for Trapper to 54.9% for Profi. Degradable CP fraction was greater (P = 0.01) for Trapper compared with the other cultivars, and no differences (P ≥ 0.25) were observed among Profi, Arvika, and Carneval. Rate of CP degradation differed (P ≤ 0.03) for all cultivars, with Profi being the greatest and Trapper the smallest (10.8, 10.0, 8.1, and 6.3 ± 1.4%/h for Profi, Carneval, Arvika, and Trapper, respectively). Estimated RDP was not different (P = 0.21) for all 4 cultivars. In the second study, 30 crossbred beef steers (301 ± 15 kg) were individually fed and used to evaluate effects of field pea processing (whole, rolled, or ground) on steer performance. Diets contained 40% field pea grain. Growing steers consuming whole field pea had greater ADG (P = 0.08) than those consuming processed field pea (1.69, 1.52, and 1.63 ± 0.05 kg/d, for whole, rolled, and ground, respectively). However, DMI (kg/d and as % of BW) and G:F were not different (P ≥ 0.24). In the third study, 35 individually fed gestating beef cows (694 ± 17 kg) were used to evaluate the use of field pea as a protein supplement for medium quality grass hay (9.3% CP). Treatments consisted of whole field peas at 1) 0 g (CON), 2) 680 g (FP680), 3) 1,360 g (FP1360), and 4) 2,040 g (FP2040), and 5) 1,360 g of 74% barley and 26% canola meal (BCM). Total intake (forage + supplement) of gestating beef cows increased with increasing field pea level (linear, P = 0.01; supplemented vs. nonsupplemented, P = 0.01). In summary, protein quantity and rate of ruminal protein degradation

Enhanced self-magnetic field by atomic polarization in partially stripped plasma produced by a short and intense laser pulse

International Nuclear Information System (INIS)

Hu Qianglin; Liu Shibing; Jiang, Y.J.; Zhang Jie

2005-01-01

The enhancement and redistribution of a self-generated quasistatic magnetic field, due to the presence of the polarization field induced by partially ionized atoms, are analytically revealed when a linearly polarized intense and short pulse laser propagates in a partially stripped plasma with higher density. In particular, the shorter wavelength of the laser pulse can evidently intensify the amplitude of the magnetic field. These enhancement and redistribution of the magnetic field are considered physically as a result of the competition of the electrostatic field (electron-ion separation) associated with the plasma wave, the atomic polarization field, and the pondoromotive potential associated with the laser field. This competition leads to the generation of a positive, large amplitude magnetic field in the zone of the pulse center, which forms a significant difference in partially and fully stripped plasmas. The numerical result shows further that the magnetic field is resonantly modulated by the plasma wave when the pulse length is the integer times the plasma wavelength. This apparently implies that the further enhancement and restructure of the large amplitude self-magnetic field can evidently impede the acceleration and stable transfer of the hot-electron beam

Rice Dwarf Virus P2 Protein Hijacks Auxin Signaling by Directly Targeting the Rice OsIAA10 Protein, Enhancing Viral Infection and Disease Development.

Directory of Open Access Journals (Sweden)

Lian Jin

2016-09-01

Full Text Available The phytohormone auxin plays critical roles in regulating myriads of plant growth and developmental processes. Microbe infection can disturb auxin signaling resulting in defects in these processes, but the underlying mechanisms are poorly understood. Auxin signaling begins with perception of auxin by a transient co-receptor complex consisting of an F-box transport inhibitor response 1/auxin signaling F-box (TIR1/AFB protein and an auxin/indole-3-acetic acid (Aux/IAA protein. Auxin binding to the co-receptor triggers ubiquitination and 26S proteasome degradation of the Aux/IAA proteins, leading to subsequent events, including expression of auxin-responsive genes. Here we report that Rice dwarf virus (RDV, a devastating pathogen of rice, causes disease symptoms including dwarfing, increased tiller number and short crown roots in infected rice as a result of reduced sensitivity to auxin signaling. The RDV capsid protein P2 binds OsIAA10, blocking the interaction between OsIAA10 and OsTIR1 and inhibiting 26S proteasome-mediated OsIAA10 degradation. Transgenic rice plants overexpressing wild-type or a dominant-negative (degradation-resistant mutant of OsIAA10 phenocopy RDV symptoms are more susceptible to RDV infection; however, knockdown of OsIAA10 enhances the resistance of rice to RDV infection. Our findings reveal a previously unknown mechanism of viral protein reprogramming of a key step in auxin signaling initiation that enhances viral infection and pathogenesis.

Elastodynamic cloaking and field enhancement for soft spheres

Science.gov (United States)

Diatta, Andre; Guenneau, Sebastien

2016-11-01

We propose a spherical cloak described by a non-singular asymmetric elasticity tensor {C} depending upon a small parameter η, that defines the softness of a region one would like to conceal from elastodynamic waves. By varying η, we generate a class of soft spheres dressed by elastodynamic cloaks, which are shown to considerably reduce the scattering of the soft spheres. Importantly, such cloaks also provide some wave protection except for a countable set of frequencies, for which some large elastic field enhancement can be observed within the soft spheres. Through an investigation of trapped modes in elasticity, we supply a good approximation of such Mie-type resonances by some transcendental equation. Our results, unlike previous studies that focused merely on the invisibility aspects, shed light on potential pitfalls of elastodynamic cloaks for earthquake protection designed via geometric transforms: a seismic cloak needs to be designed in such a way that its inner resonances differ from eigenfrequencies of the building one wishes to protect. In order to circumvent this downfall of field enhancement inside the cloaked area, we introduce a novel generation of cloaks, named here, mixed cloaks. Such mixed cloaks consist of a shell that detours incoming waves, hence creating an invisibility region, and of a perfectly matched layer (PML, located at the inner boundary of the cloaks) that absorbs residual wave energy in such a way that aforementioned resonances in the soft sphere are strongly attenuated. The designs of mixed cloaks with a non-singular elasticity tensor combined with an inner PML and non-vanishing density bring seismic cloaks one step closer to a practical implementation. Note in passing that the concept of mixed cloaks also applies in the case of singular cloaks and can be translated in other wave areas for a similar purpose (i.e. to smear down inner resonances within the invisibility region).

Leucine stimulates protein synthesis in skeletal muscle of neonatal pigs by enhancing mTORC1 activation.

Science.gov (United States)

Suryawan, Agus; Jeyapalan, Asumthia S; Orellana, Renan A; Wilson, Fiona A; Nguyen, Hanh V; Davis, Teresa A

2008-10-01

Skeletal muscle in the neonate grows at a rapid rate due in part to an enhanced sensitivity to the postprandial rise in amino acids, particularly leucine. To elucidate the molecular mechanism by which leucine stimulates protein synthesis in neonatal muscle, overnight-fasted 7-day-old piglets were treated with rapamycin [an inhibitor of mammalian target of rapamycin (mTOR) complex (mTORC)1] for 1 h and then infused with leucine for 1 h. Fractional rates of protein synthesis and activation of signaling components that lead to mRNA translation were determined in skeletal muscle. Rapamycin completely blocked leucine-induced muscle protein synthesis. Rapamycin markedly reduced raptor-mTOR association, an indicator of mTORC1 activation. Rapamycin blocked the leucine-induced phosphorylation of mTOR, S6 kinase 1 (S6K1), and eukaryotic initiation factor (eIF)4E-binding protein-1 (4E-BP1) and formation of the eIF4E.eIF4G complex and increased eIF4E.4E-BP1 complex abundance. Rapamycin had no effect on the association of mTOR with rictor, a crucial component for mTORC2 activation, or G protein beta-subunit-like protein (GbetaL), a component of mTORC1 and mTORC2. Neither leucine nor rapamycin affected the phosphorylation of AMP-activated protein kinase (AMPK), PKB, or tuberous sclerosis complex (TSC)2, signaling components that reside upstream of mTOR. Eukaryotic elongation factor (eEF)2 phosphorylation was not affected by leucine or rapamycin, although current dogma indicates that eEF2 phosphorylation is mTOR dependent. Together, these in vivo data suggest that leucine stimulates muscle protein synthesis in neonates by enhancing mTORC1 activation and its downstream effectors.

Enhancing bioactive peptide release and identification using targeted enzymatic hydrolysis of milk proteins.

Science.gov (United States)

Nongonierma, Alice B; FitzGerald, Richard J

2018-06-01

Milk proteins have been extensively studied for their ability to yield a range of bioactive peptides following enzymatic hydrolysis/digestion. However, many hurdles still exist regarding the widespread utilization of milk protein-derived bioactive peptides as health enhancing agents for humans. These mostly arise from the fact that most milk protein-derived bioactive peptides are not highly potent. In addition, they may be degraded during gastrointestinal digestion and/or have a low intestinal permeability. The targeted release of bioactive peptides during the enzymatic hydrolysis of milk proteins may allow the generation of particularly potent bioactive hydrolysates and peptides. Therefore, the development of milk protein hydrolysates capable of improving human health requires, in the first instance, optimized targeted release of specific bioactive peptides. The targeted hydrolysis of milk proteins has been aided by a range of in silico tools. These include peptide cutters and predictive modeling linking bioactivity to peptide structure [i.e., molecular docking, quantitative structure activity relationship (QSAR)], or hydrolysis parameters [design of experiments (DOE)]. Different targeted enzymatic release strategies employed during the generation of milk protein hydrolysates are reviewed herein and their limitations are outlined. In addition, specific examples are provided to demonstrate how in silico tools may help in the identification and discovery of potent milk protein-derived peptides. It is anticipated that the development of novel strategies employing a range of in silico tools may help in the generation of milk protein hydrolysates containing potent and bioavailable peptides, which in turn may be used to validate their health promoting effects in humans. Graphical abstract The targeted enzymatic hydrolysis of milk proteins may allow the generation of highly potent and bioavailable bioactive peptides.

Two-photon imaging of field enhancement by groups of gold nanostrip antennas

DEFF Research Database (Denmark)

Novikov, Sergey M.; Beermann, Jonas; Sondergaard, Thomas

2009-01-01

Resonant field enhancement by groups of 16 nm thin gold nanostrip antennas consisting of four strips (widths of 70, 100, and 130 nm) and fixed gap (50, 100, 150, or 200 nm) between them and positioned on a quartz substrate is investigated by reflection spectroscopy and two-photon photoluminescenc...

The influence of magnetic fields on protein crystal growth and quality; Zum Einfluss magnetischer Felder auf das Wachstum und die Qualitaet von Proteinkristallen

Energy Technology Data Exchange (ETDEWEB)

Meents, Alke

2005-08-01

Magnetic fields can affect protein crystal growth in several ways. In homogeneous magnetic fields molecules and crystallites line up themselves along the magnetic field direction due to their magnetic anisotropy. Inhomogeneous magnetic fields exert a force on diamagnetic and paramagnetic compounds towards regions of lower or higher field strength. This effect can be used to create a microgravity-like environment for diamagnetic proteins and an environment comparable to hypergravity for paramagnetic proteins. Crystallization in homogeneous magnetic fields and a microgravity-like environment are reported to have a positive effect on crystal quality. The aim of this work was to systematically investigate the effect of protein crystallization in magnetic fields on the crystal quality by comparing a large number of crystals grown under identical conditions with- and without magnetic fields. Crystal quality was determined by means of high resolution rocking-curve measurements. Furthermore in certain cases complete diffraction datasets were collected. Any possible influence of magnetic fields on the mosaicity and the quality of the diffraction data was evaluated statistically by applying Wilcoxon-Ranksum tests. To investigate the effect of protein crystallization in homogeneous magnetic fields the diamagnetic proteins Thaumatin, Trypsin, and Lysozyme and paramagnetic Myoglobin were crystallized in magnetic fields of 5 T, 8.8 T, and 15.8 T. The analysis of crystal mosaicity and quality of the diffraction data of the diamagnetic proteins did not reveal a significant influence on the crystal quality. In contrast the crystals of paramagnetic Myoglobin grew up to 14 times larger than the ones in the control experiment. In addition they had a significant lower mosaicity, and diffracted to a higher resolution than ever reported before. Special pole pieces for an existing magnet were designed and build to grow protein crystals in an inhomogeneous magnetic field The experimental

Mapping of gold nanostructure-enhanced near fields via laser scanning second-harmonic generation and ablation

DEFF Research Database (Denmark)

Fiutowski, Jacek; Maibohm, Christian; Kostiučenko, Oksana

2012-01-01

The optical near-field of metal films can be modified in a straightforward manner by incorporating nanostructures on the surface. The corresponding field enhancement, which may be due to the lightning rod effect as well as the excitation of plasmon modes, results in a local change of the optical ...

Structural control of metamaterial oscillator strength and electric field enhancement at terahertz frequencies

DEFF Research Database (Denmark)

Keiser, G. R.; Seren, H. R.; Strikwerda, Andrew C.

2014-01-01

The design of artificial nonlinear materials requires control over internal resonant charge densities and local electric field distributions. We present a MM design with a structurally controllable oscillator strength and local electric field enhancement at terahertz frequencies. The MM consists...... of a split ring resonator (SRR) array stacked above an array of closed conducting rings. An in-plane, lateral shift of a half unit cell between the SRR and closed ring arrays results in an increase of the MM oscillator strength by a factor of 4 and a 40% change in the amplitude of the resonant electric field...

Enhanced production of recombinant proteins with Corynebacterium glutamicum by deletion of insertion sequences (IS elements).

Science.gov (United States)

Choi, Jae Woong; Yim, Sung Sun; Kim, Min Jeong; Jeong, Ki Jun

2015-12-29

In most bacteria, various jumping genetic elements including insertion sequences elements (IS elements) cause a variety of genetic rearrangements resulting in harmful effects such as genome and recombinant plasmid instability. The genetic stability of a plasmid in a host is critical for high-level production of recombinant proteins, and in this regard, the development of an IS element-free strain could be a useful strategy for the enhanced production of recombinant proteins. Corynebacterium glutamicum, which is a workhorse in the industrial-scale production of various biomolecules including recombinant proteins, also has several IS elements, and it is necessary to identify the critical IS elements and to develop IS element deleted strain. From the cultivation of C. glutamicum harboring a plasmid for green fluorescent protein (GFP) gene expression, non-fluorescent clones were isolated by FACS (fluorescent activated cell sorting). All the isolated clones had insertions of IS elements in the GFP coding region, and two major IS elements (ISCg1 and ISCg2 families) were identified. By co-cultivating cells harboring either the isolated IS element-inserted plasmid or intact plasmid, it was clearly confirmed that cells harboring the IS element-inserted plasmids became dominant during the cultivation due to their growth advantage over cells containing intact plasmids, which can cause a significant reduction in recombinant protein production during cultivation. To minimize the harmful effects of IS elements on the expression of heterologous genes in C. glutamicum, two IS element free C. glutamicum strains were developed in which each major IS element was deleted, and enhanced productivity in the engineered C. glutamicum strain was successfully demonstrated with three models: GFP, poly(3-hydroxybutyrate) [P(3HB)] and γ-aminobutyrate (GABA). Our findings clearly indicate that the hopping of IS elements could be detrimental to the production of recombinant proteins in C

A study on enhancing policy transparency in the nuclear field

Energy Technology Data Exchange (ETDEWEB)

Cheon, S. W. [Korea Institute for National Unification, Seoul (Korea)

2000-11-01

Enhancing transparency in the nuclear field is a pending issue for the South Korea's nuclear community. International suspicions and mistrust of ROK's nuclear activities have been obstacles to the developments of South Korea's nuclear industry. South Korea's efforts have not been sufficient enough to ensure international community that its nuclear program will be used solely for peaceful purposes. Therefore, the purpose of this study is to conduct a positive and creative research on the issue of transparency and provide policy options that are conducive to developing of South Korea's nuclear industry. Based on an in-depth study on transparency of national policies, this study presents a package of detail policy measures that can contribute to enhancing transparency in the nuclear filed. 75 refs., 2 tabs. (Author)

Geometrical enhancement of the electric field: Application of fractional calculus in nanoplasmonics

Science.gov (United States)

Baskin, E.; Iomin, A.

2011-12-01

We developed an analytical approach, for a wave propagation in metal-dielectric nanostructures in the quasi-static limit. This consideration establishes a link between fractional geometry of the nanostructure and fractional integro-differentiation. The method is based on fractional calculus and permits to obtain analytical expressions for the electric-field enhancement.

Field-effect enhanced triboelectric colloidal quantum dot flexible sensor

Science.gov (United States)

Meng, Lingju; Xu, Qiwei; Fan, Shicheng; Dick, Carson R.; Wang, Xihua

2017-10-01

Flexible electronics, which is of great importance as fundamental sensor and communication technologies for many internet-of-things applications, has established a huge market encroaching into the trillion-dollar market of solid state electronics. For the capability of being processed by printing or spraying, colloidal quantum dots (CQDs) play an increasingly important role in flexible electronics. Although the electrical properties of CQD thin-films are expected to be stable on flexible substrates, their electrical performance could be tuned for applications in flexible touch sensors. Here, we report CQD touch sensors employing polydimethylsiloxane (PDMS) triboelectric films. The electrical response of touching activity is enhanced by incorporating CQD field-effect transistors into the device architecture. Thanks to the use of the CQD thin film as a current amplifier, the field-effect CQD touch sensor shows a fast response to various touching materials, even being bent to a large curvature. It also shows a much higher output current density compared to a PDMS triboelectric touch sensor.

50 Hz electric field effects on protein carbonyl (PCO), heme oxygenase-1 (HO-1) and hydroxyproline levels

International Nuclear Information System (INIS)

Ozgur, Elcin; Goknur, Guler; Seyhan, Nesrin

2008-01-01

Full text: Non-ionizing electromagnetic field (EMF) radiation sources, such as power lines and other Extremely Low Frequency (ELF) sources have become one of the most ubiquitous components of the spectrum of the human environment, and the possibility that they may have hazardous effects on human health is a major a public concern. Although it is well documented that EMFs have biological effects, the degree to which these exposures constitute a human health hazard is not clear yet. Today relation between production of oxidative stress resulted by reactive oxygen species and electrical stimulus, also the protective effects of antioxidant treatments are mentioned in many researches. In this study, it was aimed to determine both oxidation of proteins and protein collagen levels under 50 Hz 12 kV/m vertical Electric (E) Field exposure and the N-Acetylcysteine (NAC) administration which is a well-known antioxidant. To this end, protein carbonyl levels (PCO) as bio-markers of oxidative stress and Heme oxygenase-1 (HO-1), an enzyme that catalyzes the degradation of heme analyzed to figure out the protein oxidation. Hydroxyproline level, a major component of the protein collagen was measured in order to express the level of collagen in lung tissue. Guinea pigs, weighted 250-300 g, were used in the study. A total forty male guinea pigs were randomly divided into four groups which are composed of 10 guinea pigs each for groups: 1) Group I (Sham); 2) Group II (NAC-administrated group); 3) Group III (E Field Exposure group); 4) Group IV (NAC administrated + E Field exposed group). One week exposure period for 8 hours per daily was conducted for each exposure groups (Group III, Group IV ). The electric field exposure period was from 9 a.m. to 5 p.m. After the last exposure day, the guinea pigs were anesthetized by the injection of ketamine and xylazine. The guinea pigs were killed by decapitation. Statistical analyses were carried out using SPSS software (SPSS 11.5 for windows

Field enhancement due to anomalous skin effect inside a target

International Nuclear Information System (INIS)

Ma, G.; Tan, W.

1996-01-01

A new method based on Fourier transformation to study the skin effects is presented. Using this method, the field amplitude in plasma is represented in terms of electric conductivity, and the normal and anomalous skin effects are described through one formula by omitting the plasma dispersion or not. The results are in agreement with other publications [e.g., J. P. Matte and K. Aguenaou, Phys. Rev. A 45, 2558 (1992)] for equivalent parameters. But for deeper positions inside a target, which have not been studied by others, it is found that the field amplitude is considerably enhanced due to an anomalous skin effect, even for constant collision frequency. In addition, the skin absorptions and some calculations on an anomalous skin effect for different collision frequencies are also presented. copyright 1996 American Institute of Physics

The kinesin spindle protein inhibitor filanesib enhances the activity of pomalidomide and dexamethasone in multiple myeloma

OpenAIRE

Hernández-García, Susana; San-Segundo, Laura; González-Méndez, Lorena; Corchete, Luis A; Misiewicz-Krzeminska, Irena; Martín-Sánchez, Montserrat; López-Iglesias, Ana-Alicia; Algarín, Esperanza Macarena; Mogollón, Pedro; Díaz-Tejedor, Andrea; Paíno, Teresa; Tunquist, Brian; Mateos, María-Victoria; Gutiérrez, Norma C; Díaz-Rodriguez, Elena

2017-01-01

[EN]Kinesin spindle protein inhibition is known to be an effective therapeutic approach in several malignancies. Filanesib (ARRY-520), an inhibitor of this protein, has demonstrated activity in heavily pre-treated multiple myeloma patients. The aim of the work herein was to investigate the activity of filanesib in combination with pomalidomide plus dexamethasone backbone, and the mechanisms underlying the potential synergistic effect. The ability of filanesib to enhance the activity of pomali...

How sensitive are nanosecond molecular dynamics simulations of proteins to changes in the force field?

NARCIS (Netherlands)

Villa, Alessandra; Fan, Hao; Wassenaar, Tsjerk; Mark, Alan E.

2007-01-01

The sensitivity of molecular dynamics simulations to variations in the force field has been examined in relation to a set of 36 structures corresponding to 31 proteins simulated by using different versions of the GROMOS force field. The three parameter sets used (43a1, 53a5, and 53a6) differ

Protein domain recurrence and order can enhance prediction of protein functions

KAUST Repository

Abdel Messih, Mario A.

2012-09-07

Motivation: Burgeoning sequencing technologies have generated massive amounts of genomic and proteomic data. Annotating the functions of proteins identified in this data has become a big and crucial problem. Various computational methods have been developed to infer the protein functions based on either the sequences or domains of proteins. The existing methods, however, ignore the recurrence and the order of the protein domains in this function inference. Results: We developed two new methods to infer protein functions based on protein domain recurrence and domain order. Our first method, DRDO, calculates the posterior probability of the Gene Ontology terms based on domain recurrence and domain order information, whereas our second method, DRDO-NB, relies on the nave Bayes methodology using the same domain architecture information. Our large-scale benchmark comparisons show strong improvements in the accuracy of the protein function inference achieved by our new methods, demonstrating that domain recurrence and order can provide important information for inference of protein functions. The Author(s) 2012. Published by Oxford University Press.

Self-consistent field theory of protein adsorption in a non-Gaussian polyelectrolyte brush

NARCIS (Netherlands)

Biesheuvel, P.M.; Leermakers, F.A.M.; Stuart, M.A.C.

2006-01-01

To describe adsorption of globular protein molecules in a polyelectrolyte brush we use the strong-stretching approximation of the Edwards self-consistent field equation, combined with corrections for a non-Gaussian brush. To describe chemical potentials in this mixture of (globular) species of

Energy transfer between surface-immobilized light-harvesting chlorophyll a/b complex (LHCII) studied by surface plasmon field-enhanced fluorescence spectroscopy (SPFS).

Science.gov (United States)

Lauterbach, Rolf; Liu, Jing; Knoll, Wolfgang; Paulsen, Harald

2010-11-16

The major light-harvesting chlorophyll a/b complex (LHCII) of the photosynthetic apparatus in green plants can be viewed as a protein scaffold binding and positioning a large number of pigment molecules that combines rapid and efficient excitation energy transfer with effective protection of its pigments from photobleaching. These properties make LHCII potentially interesting as a light harvester (or a model thereof) in photoelectronic applications. Most of such applications would require the LHCII to be immobilized on a solid surface. In a previous study we showed the immobilization of recombinant LHCII on functionalized gold surfaces via a 6-histidine tag (His tag) in the protein moiety. In this work the occurrence and efficiency of Förster energy transfer between immobilized LHCII on a functionalized surface have been analyzed by surface plasmon field-enhanced fluorescence spectroscopy (SPFS). A near-infrared dye was attached to some but not all of the LHC complexes, serving as an energy acceptor to chlorophylls. Analysis of the energy transfer from chlorophylls to this acceptor dye yielded information about the extent of intercomplex energy transfer between immobilized LHCII.

Glutamic Acid as Enhancer of Protein Synthesis Kinetics in Hepatocytes from Old Rats.

Science.gov (United States)

Brodsky, V Y; Malchenko, L A; Butorina, N N; Lazarev Konchenko, D S; Zvezdina, N D; Dubovaya, T K

2017-08-01

Dense cultures of hepatocytes from old rats (~2 years old, body weight 530-610 g) are different from similar cultures of hepatocytes from young rats by the low amplitude of protein synthesis rhythm. Addition of glutamic acid (0.2, 0.4, or 0.6 mg/ml) into the culture medium with hepatocytes of old rats resulted in increase in the oscillation amplitudes of the protein synthesis rhythm to the level of young rats. A similar action of glutamic acid on the protein synthesis kinetics was observed in vivo after feeding old rats with glutamic acid. Inhibition of metabotropic receptors of glutamic acid with α-methyl-4-carboxyphenylglycine (0.01 mg/ml) abolished the effect of glutamic acid. The amplitude of oscillation of the protein synthesis rhythm in a cell population characterizes synchronization of individual oscillations caused by direct cell-cell communications. Hence, glutamic acid, acting as a receptor-dependent transmitter, enhanced direct cell-cell communications of hepatocytes that were decreased with aging. As differentiated from other known membrane signaling factors (gangliosides, norepinephrine, serotonin, dopamine), glutamic acid can penetrate into the brain and thus influence the communications and protein synthesis kinetics that are disturbed with aging not only in hepatocytes, but also in neurons.

Photochemical Synthesis of Silver Nanodecahedrons and Related Nanostructures for Plasmonic Field Enhancement Applications

Science.gov (United States)

Lu, Haifei

Noble-metal nanocrystals have received considerable attention in recent years for their size and shape dependent localized surface Plasmon resonances (LSPR). Various applications based on colloidal nanoparticles, such as surface enhanced Raman scattering (SERS), surface enhanced fluorescence (SEF), plasmonic sensing, photothermal therapy etc., have been broadly explored in the field of biomedicine, because of their extremely large optical scattering and absorption cross sections, as well as giant electric field enhancement on their surface. However, despite its high chemical stability, gold exhibits quite large losses and electric field enhancement is comparatively weaker than silver. Silver nanoparticles synthesized by the traditional technique only cover an LSPR ranged from 420~500 nm. On the other hand, the range of 500~660 nm, which is covered by several easily available commercial laser lines, very limited colloidal silver nanostructures with controllable size and shape have been reported, and realization of tuning the resonance to longer wavelengths is very important for the practical applications. In this thesis, a systematic study on photochemical synthesis of silver nanodecahedrons (NDs) and related nanostructures, and their plasmonic field enhancements are presented. First, the roles of chemicals and the light source during the formation of silver nanoparticles have been studied. We have also developed a preparation route for the production size-controlled silver nanodecahedrons (LSPR range 420 ~ 660 nm) in high purity. Indeed our experiments indicate that both the chemicals and the light sources can affect the shape and purity of final products. Adjusting the molar ratio between sodium citrate and silver nitrate can help to control the crystal structure following rapid reduction from sodium borohydride. Light from a blue LED (465 nm) can efficiently transform the polyvinylpyrrolidone stabilized small silver nanoparticles into silver NDs through photo

Enhanced Field Emission from Argon Plasma-Treated Ultra-sharp α-Fe2O3Nanoflakes

Directory of Open Access Journals (Sweden)

Zhang JX

2009-01-01

Full Text Available Abstract Hematite nanoflakes have been synthesized by a simple heat oxide method and further treated by Argon plasmas. The effects of Argon plasma on the morphology and crystal structures of nanoflakes were investigated. Significant enhancement of field-induced electron emission from the plasma-treated nanoflakes was observed. The transmission electron microscopy investigation shows that the plasma treatment effectively removes amorphous coating and creates plenty of sub-tips at the surface of the nanoflakes, which are believed to contribute the enhancement of emission. This work suggests that plasma treatment technique could be a direct means to improve field-emission properties of nanostructures.

Cationization of immunoglobulin G results in enhanced organ uptake of the protein after intravenous administration in rats and primate

International Nuclear Information System (INIS)

Triguero, D.; Buciak, J.L.; Pardridge, W.M.

1991-01-01

Cationization of proteins in general enhances the cellular uptake of these macromolecules, and cationized antibodies are known to retain antigen binding properties. Therefore, cationized antibodies may be therapeutic and allow for intracellular immunization. The present studies test the hypothesis that the tissue uptake of cationized immunoglobulin G (IgG) after intravenous administration may be greatly increased relative to the uptake of native proteins. The pharmacokinetics of cationized immunoglobulin G clearance from blood, and the volume of distribution of the cationized or native protein (albumin, IgG) for 10 organs was measured both in anesthetized rats and in an anesthetized adult Macaca irus cynomologous monkey. Initial studies on brain showed that serum factors inhibited uptake of 125I-cationized IgG, but not 3H-cationized IgG. The blood-brain barrier permeability surface area product for 3H-cationized IgG was 0.57 ± 0.04 microliters min-1 g-1. The ratio of the volume of distribution of the 3-H-cationized IgG compared to 3H-labeled native albumin ranged from 0.9 (testis) to 15.7 (spleen) in the rat at 3 hr after injection, and a similarly enhanced organ uptake was observed in the primate. In conclusion, these studies demonstrate that cationization of immunoglobulin greatly increases organ uptake of the plasma protein compared to native immunoglobulins, and suggest that cationization of monoclonal antibodies may represent a potential new strategy for enhancing the intracellular delivery of these proteins

Identification and characterization of the related immune-enhancing proteins in crab Scylla paramamosain stimulated with rhubarb polysaccharides.

Science.gov (United States)

Cao, Jingsong; Wang, Zehuan; Zhang, Yueling; Qu, Fengliang; Guo, Lingling; Zhong, Mingqi; Li, Shengkang; Zou, Haiying; Chen, Jiehui; Wang, Xiuying

2014-02-01

Recently, considerable interest has been focused on immunostimulants to reduce diseases in crab aquaculture. However, information regarding to the related immune-enhancing proteins in crabs is not available yet. In this study, rhubarb polysaccharides were tested for enhancement of the immune activity in crab Scylla paramamosain. Compared with those in the control group, values of, phenoloxidase (PO), alkaline phosphatase (AKP) and alkaline phosphatasein (ACP) activity in the, experimental group were improved significantly 4 d after the treatment. Furthermore, 15 and 17 altered proteins from haemocytes and hepatopancreas, respectively, were found in rhubarb polysaccharide-treated crabs using 2-DE approach. Of these, hemocyanin, chymotrypsin, cryptocyanin, C-type lectin receptor, and ferritin protein were identified by mass spectrometry. In addition, RT-PCR, analysis showed that the mRNA levels of hemocyanin and chymotrypsin increased about 2.4- and 1.4-fold in the experiment group. Moreover, the hemocyanin gene in S. paramamosain (SpHMC) was, cloned and characterized. SpHMC contains one open reading frame of 2022 bp and encodes a polypeptide of 673 amino acids. It is clustered into one branch along with crab hemocyanin in a phylogenetic tree. The mRNA transcripts of SpHMC were detected mainly in the tissues of, hepatopancreas, hemocyte and intestines, and its levels were up-regulated significantly in hemocytes, of S. paramamosain treated with Vibrio parahemolyticus, Beta streptococcus or poly I:C for 6-48 h. Taken together, these studies found 5 related immune-enhancing proteins and a novel heomcyanin homologue with potential pathogen-resistant activities in crab. Copyright © 2013 Elsevier Ltd. All rights reserved.

Enhanced Temperature During Grain Filling Reduces Protein Concentration of Durum Wheat

Directory of Open Access Journals (Sweden)

Franco Miglietta

2011-02-01

Full Text Available Durum wheat is cultivated over more than 13 millions of hectares (ha world wide and Italy is the main European producer with 3.5 millions tons per year. The protein concentration of durum wheat is very important, it ensures high nutritional value and is highly appreciated by the pasta production industries. The protein concentration of wheat is determined during the grain filling period when carbon and nitrogen compounds are translocated into the grains. Air temperature affects translocation rates and contributes to final protein concentration of wheat grains. Two common commercial varieties of durum and bread wheat were exposed from anthesis to harvest, to a source of infrared radiation in the field. This allowed to investigate the relative effect of temperature on translocation of carbon and nitrogen compound during grain filling. The heat treatment imposed affected marginally dry mass accumulation of the grains in bread wheat and didn’t affect dry mass in durum wheat. Grain protein was affected by heat treatment in durum but not in bread wheat. Carbon accumulation rate was higher for durum than for bread wheat. The protein concentration was greater in durum than in bread wheat and we can assume that the absolute nitrogen accumulation rates were higher for the former species. Such difference may be either caused by a faster nitrogen uptake rate and translocation or a more efficient relocation of nitrogen accumulated in reserve organs.

Enhancement of proton acceleration field in laser double-layer target interaction

International Nuclear Information System (INIS)

Gu, Y. J.; Kong, Q.; Li, X. F.; Yu, Q.; Wang, P. X.; Kawata, S.; Izumiyama, T.; Ma, Y. Y.

2013-01-01

A mechanism is proposed to enhance a proton acceleration field in laser plasma interaction. A double-layer plasma with different densities is illuminated by an intense short pulse. Electrons are accelerated to a high energy in the first layer by the wakefield. The electrons accelerated by the laser wakefield induce the enhanced target normal sheath (TNSA) and breakout afterburner (BOA) accelerations through the second layer. The maximum proton energy reaches about 1 GeV, and the total charge with an energy higher than 100 MeV is about several tens of μC/μm. Both the acceleration gradient and laser energy transfer efficiency are higher than those in single-target-based TNSA or BOA. The model has been verified by 2.5D-PIC simulations

Fast Ignition Thermonuclear Fusion: Enhancement of the Pellet Gain by the Colossal-Magnetic-Field Shells

Science.gov (United States)

Stefan, V. Alexander

2013-10-01

The fast ignition fusion pellet gain can be enhanced by a laser generated B-field shell. The B-field shell, (similar to Earth's B-field, but with the alternating B-poles), follows the pellet compression in a frozen-in B-field regime. A properly designed laser-pellet coupling can lead to the generation of a B-field shell, (up to 100 MG), which inhibits electron thermal transport and confines the alpha-particles. In principle, a pellet gain of few-100s can be achieved in this manner. Supported in part by Nikola Tesla Labs, Stefan University, 1010 Pearl, La Jolla, CA 92038-1007.

Aggregation of egg white proteins with pulsed electric fields and thermal processes.

Science.gov (United States)

Wu, Li; Zhao, Wei; Yang, Ruijin; Yan, Wenxu; Sun, Qianyan

2016-08-01

Pulsed electric field (PEF) processing is progressing towards application for liquid egg to ensure microbial safety. However, it usually causes protein aggregation, and the mechanism is still unclear. In this study, egg white protein was applied to investigate the changes in protein structure and mechanism of aggregates formation and a comparison was made with thermal treatment. Soluble protein content decreased with the increase of turbidity after both treatments. Fluorescence intensity and free sulfhydryl content were increased after being treated at 70 °C for 4 min. Less-remarkable changes of hydrophobicity were observed after PEF treatments (30 kV cm(-1) , 800 µs). Soluble and insoluble aggregates were observed by thermal treatment, and disulfide bonds were the main binding forces. The main components of insoluble aggregates formed by thermal treatment were ovotransferrin (30.58%), lysozyme (18.47%) and ovalbumin (14.20%). While only insoluble aggregates were detected during PEF processes, which consists of ovotransferrin (11.86%), lysozyme (21.11%) and ovalbumin (31.07%). Electrostatic interaction played a very important role in the aggregates formation. PEF had a minor impact on the structure of egg white protein. PEF had insignificant influence on heat-sensitive protein, indicating that PEF has potential in processing food with high biological activity and heat sensitive properties. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

Transcriptional activation of the mouse obese (ob) gene by CCAAT/enhancer binding protein alpha

DEFF Research Database (Denmark)

Hwang, C S; Mandrup, S; MacDougald, O A

1996-01-01

Like other adipocyte genes that are transcriptionally activated by CCAAT/enhancer binding protein alpha (C/EBP alpha) during preadipocyte differentiation, expression of the mouse obese (ob) gene is immediately preceded by the expression of C/EBP alpha. While the 5' flanking region of the mouse ob...... gene contains several consensus C/EBP binding sites, only one of these sites appears to be functional. DNase I cleavage inhibition patterns (footprinting) of the ob gene promoter revealed that recombinant C/EBP alpha, as well as a nuclear factor present in fully differentiated 3T3-L1 adipocytes...... to a consensus C/EBP binding site at nucleotides -55 to -47 generated a specific protein-oligonucleotide complex that was supershifted by antibody against C/EBP alpha. Probes corresponding to two upstream consensus C/EBP binding sites failed to generate protein-oligonucleotide complexes. Cotransfection of a C...

Enhancement on field emission characteristics of pulsed laser deposited diamondlike carbon films using Au precoatings

International Nuclear Information System (INIS)

Chuang, F.Y.; Sun, C.Y.; Cheng, H.F.; Lin, I.N.

1997-01-01

Using Au precoatings has been observed to significantly enhance the field emission properties of diamondlike carbon (DLC) films deposited on Si substrates. The electron emission can be turned on at a low field as 7 V/μm and a large emission current density as 2000 μA/cm 2 can be obtained at 20 V/μm applied field. However, preannealing the Au-coated Si substrates at 500 degree C for 30 min is necessary to achieve such a performance. Microscopic examination on surface and cross-sectional morphologies of the DLC/Au/Si films using atomic force microscopy and scanning electron microscopy, respectively, in conjunction with the elemental depth profile examination of these films using secondary ion mass spectroscopy, indicated that substantial interdiffusion between DLC, Au, and Si layers has occurred. Such kind of reaction is proposed to lower the resistance for electrons to transport across the interfaces and, thereafter, enhances the field emission properties of the DLC/Au/Si films. copyright 1997 American Institute of Physics

Stabilizing salt-bridge enhances protein thermostability by reducing the heat capacity change of unfolding.

Directory of Open Access Journals (Sweden)

Chi-Ho Chan

Full Text Available Most thermophilic proteins tend to have more salt bridges, and achieve higher thermostability by up-shifting and broadening their protein stability curves. While the stabilizing effect of salt-bridge has been extensively studied, experimental data on how salt-bridge influences protein stability curves are scarce. Here, we used double mutant cycles to determine the temperature-dependency of the pair-wise interaction energy and the contribution of salt-bridges to ΔC(p in a thermophilic ribosomal protein L30e. Our results showed that the pair-wise interaction energies for the salt-bridges E6/R92 and E62/K46 were stabilizing and insensitive to temperature changes from 298 to 348 K. On the other hand, the pair-wise interaction energies between the control long-range ion-pair of E90/R92 were negligible. The ΔC(p of all single and double mutants were determined by Gibbs-Helmholtz and Kirchhoff analyses. We showed that the two stabilizing salt-bridges contributed to a reduction of ΔC(p by 0.8-1.0 kJ mol⁻¹ K⁻¹. Taken together, our results suggest that the extra salt-bridges found in thermophilic proteins enhance the thermostability of proteins by reducing ΔC(p, leading to the up-shifting and broadening of the protein stability curves.

Nitrogen detected TROSY at high field yields high resolution and sensitivity for protein NMR

International Nuclear Information System (INIS)

Takeuchi, Koh; Arthanari, Haribabu; Shimada, Ichio; Wagner, Gerhard

2015-01-01

Detection of 15 N in multidimensional NMR experiments of proteins has sparsely been utilized because of the low gyromagnetic ratio (γ) of nitrogen and the presumed low sensitivity of such experiments. Here we show that selecting the TROSY components of proton-attached 15 N nuclei (TROSY 15 N H ) yields high quality spectra in high field magnets (>600 MHz) by taking advantage of the slow 15 N transverse relaxation and compensating for the inherently low 15 N sensitivity. The 15 N TROSY transverse relaxation rates increase modestly with molecular weight but the TROSY gain in peak heights depends strongly on the magnetic field strength. Theoretical simulations predict that the narrowest line width for the TROSY 15 N H component can be obtained at 900 MHz, but sensitivity reaches its maximum around 1.2 GHz. Based on these considerations, a 15 N-detected 2D 1 H– 15 N TROSY-HSQC ( 15 N-detected TROSY-HSQC) experiment was developed and high-quality 2D spectra were recorded at 800 MHz in 2 h for 1 mM maltose-binding protein at 278 K (τ c  ∼ 40 ns). Unlike for 1 H detected TROSY, deuteration is not mandatory to benefit 15 N detected TROSY due to reduced dipolar broadening, which facilitates studies of proteins that cannot be deuterated, especially in cases where production requires eukaryotic expression systems. The option of recording 15 N TROSY of proteins expressed in H 2 O media also alleviates the problem of incomplete amide proton back exchange, which often hampers the detection of amide groups in the core of large molecular weight proteins that are expressed in D 2 O culture media and cannot be refolded for amide back exchange. These results illustrate the potential of 15 N H -detected TROSY experiments as a means to exploit the high resolution offered by high field magnets near and above 1 GHz

PROTEIN L-ISOASPARTYL METHYLTRANSFERASE2 is differentially expressed in chickpea and enhances seed vigor and longevity by reducing abnormal isoaspartyl accumulation predominantly in seed nuclear proteins.

Science.gov (United States)

Verma, Pooja; Kaur, Harmeet; Petla, Bhanu Prakash; Rao, Venkateswara; Saxena, Saurabh C; Majee, Manoj

2013-03-01

PROTEIN l-ISOASPARTYL METHYLTRANSFERASE (PIMT) is a widely distributed protein-repairing enzyme that catalyzes the conversion of abnormal l-isoaspartyl residues in spontaneously damaged proteins to normal aspartyl residues. This enzyme is encoded by two divergent genes (PIMT1 and PIMT2) in plants, unlike many other organisms. While the biological role of PIMT1 has been elucidated, the role and significance of the PIMT2 gene in plants is not well defined. Here, we isolated the PIMT2 gene (CaPIMT2) from chickpea (Cicer arietinum), which exhibits a significant increase in isoaspartyl residues in seed proteins coupled with reduced germination vigor under artificial aging conditions. The CaPIMT2 gene is found to be highly divergent and encodes two possible isoforms (CaPIMT2 and CaPIMT2') differing by two amino acids in the region I catalytic domain through alternative splicing. Unlike CaPIMT1, both isoforms possess a unique 56-amino acid amino terminus and exhibit similar yet distinct enzymatic properties. Expression analysis revealed that CaPIMT2 is differentially regulated by stresses and abscisic acid. Confocal visualization of stably expressed green fluorescent protein-fused PIMT proteins and cell fractionation-immunoblot analysis revealed that apart from the plasma membrane, both CaPIMT2 isoforms localize predominantly in the nucleus, while CaPIMT1 localizes in the cytosol. Remarkably, CaPIMT2 enhances seed vigor and longevity by repairing abnormal isoaspartyl residues predominantly in nuclear proteins upon seed-specific expression in Arabidopsis (Arabidopsis thaliana), while CaPIMT1 enhances seed vigor and longevity by repairing such abnormal proteins mainly in the cytosolic fraction. Together, our data suggest that CaPIMT2 has most likely evolved through gene duplication, followed by subfunctionalization to specialize in repairing the nuclear proteome.

Electric field enhanced adsorption and diffusion of adatoms in MoS{sub 2} monolayer

Energy Technology Data Exchange (ETDEWEB)

Shi, Wenwu [School of Physical Electronics, Center for Public Security Information and Equipment Integration Technology, University of Electronic Science and Technology of China, Chengdu, 610054 (China); Wang, Zhiguo, E-mail: zgwang@uestc.edu.cn [School of Physical Electronics, Center for Public Security Information and Equipment Integration Technology, University of Electronic Science and Technology of China, Chengdu, 610054 (China); Li, Zhijie [School of Physical Electronics, Center for Public Security Information and Equipment Integration Technology, University of Electronic Science and Technology of China, Chengdu, 610054 (China); Fu, Y.Q., E-mail: richard.fu@northumbria.ac.uk [School of Physical Electronics, Center for Public Security Information and Equipment Integration Technology, University of Electronic Science and Technology of China, Chengdu, 610054 (China); Faculty of Engineering and Environment, University of Northumbria, Newcastle upon Tyne, NE1 8ST (United Kingdom)

2016-11-01

A new phenomenon, electric field enhanced adsorption and diffusion of lithium, magnesium and aluminum ions in a MoS{sub 2} monolayer, was investigated using density functional theory in this study. With the electric field increased from 0 to 0.8 V/Å, the adsorption energies of the Li, Mg and Al atoms in the MoS{sub 2} monolayer were decreased from −2.01 to −2.49 eV, from −0.80 to −1.28 eV, and −2.71 to −3.01 eV, respectively. The corresponding diffusion barriers were simultaneously decreased from 0.23 to 0.08 eV, from 0.15 to 0.10 eV, and 0.24 to 0.21 eV for the Li, Mg and Al ions, respectively. We concluded that the external electric field can increase the charging speed of rechargeable ion batteries based on the MoS{sub 2} anode materials. - Highlights: • Effect of electric field on the adsorption and diffusion were investigated. • Adsorption energies of the adatoms in the MoS{sub 2} monolayer were enhanced. • Diffusion barriers of the adatoms in the MoS{sub 2} monolayer were decreased. • Electric field can be used to realize a fast charging rate of rechargeable ion batteries.

Investigation of various cavity configurations for metamaterial-enhanced field-localizing wireless power transfer

Science.gov (United States)

Bui, Huu Nguyen; Pham, Thanh Son; Ngo, Viet; Lee, Jong-Wook

2017-09-01

Controlling power to an unintended area is an important issue for enabling wireless power transfer (WPT) systems. The control allows us to enhance efficiency as well as suppress unnecessary flux leakage. The flux leakage from WPT can be reduced effectively via selective field localization. To realize field localization, we propose the use of cavities formed on a single metamaterial slab that acts as a defected metasurface. The cavity is formed by strong field confinement using a hybridization bandgap (HBG), which is created by wave interaction with a two-dimensional array of local resonators on the metasurface. This approach using an HBG demonstrates strong field localization around the cavity regions. Motivated by this result, we further investigate various cavity configurations for different sizes of the transmitter (Tx) and receiver (Rx) resonators. Experiments show that the area of field localization increases with the number of cavities, confirming the successful control of different cavity configurations on the metasurface. Transmission measurements of different cavities show that the number of cavities is an important parameter for efficiency, and excess cavities do not enhance the efficiency but increase unnecessary power leakage. Thus, there exists an optimum number of cavities for a given size ratio between the Tx and Rx resonators. For a 6:1 size ratio, this approach achieves efficiency improvements of 3.69× and 1.59× compared to free space and a uniform metasurface, respectively. For 10:1 and 10:2 size ratios, the efficiency improvements are 3.26× and 1.98× compared to free space and a uniform metasurface, respectively.

Coupling detergent lysis/clean-up methodology with intact protein fractionation for enhanced proteome characterization

Energy Technology Data Exchange (ETDEWEB)

Sharma, Ritin [ORNL; Dill, Brian [ORNL; Chourey, Karuna [ORNL; Shah, Manesh B [ORNL; Verberkmoes, Nathan C [ORNL; Hettich, Robert {Bob} L [ORNL

2012-01-01

The expanding use of surfactants for proteome sample preparations has prompted the need to systematically optimize the application and removal of these MS-deleterious agents prior to proteome measurements. Here we compare four different detergent clean-up methods (Trichloroacetic acid (TCA) precipitation, Chloroform/Methanol/Water (CMW) extraction, commercial detergent removal spin column method (DRS) and filter-aided sample preparation(FASP)) with respect to varying amounts of protein biomass in the samples, and provide efficiency benchmarks with respect to protein, peptide, and spectral identifications for each method. Our results show that for protein limited samples, FASP outperforms the other three clean-up methods, while at high protein amount all the methods are comparable. This information was used in a dual strategy of comparing molecular weight based fractionated and unfractionated lysates from three increasingly complex samples (Escherichia coli, a five microbial isolate mixture, and a natural microbial community groundwater sample), which were all lysed with SDS and cleaned up using FASP. The two approaches complemented each other by enhancing the number of protein identifications by 8%-25% across the three samples and provided broad pathway coverage.

Enhanced expression of Gqα and PLC-β1 proteins contributes to vascular smooth muscle cell hypertrophy in SHR: role of endogenous angiotensin II and endothelin-1.

Science.gov (United States)

Atef, Mohammed Emehdi; Anand-Srivastava, Madhu B

2014-07-01

Vascular Gqα signaling has been shown to contribute to cardiac hypertrophy. In addition, angiotensin II (ANG II) was shown to induce vascular smooth muscle cell (VSMC) hypertrophy through Gqα signaling; however, the studies on the role of Gqα and PLC-β1 proteins in VSMC hypertrophy in animal model are lacking. The present study was therefore undertaken to examine the role of Gqα/PLC-β1 proteins and the signaling pathways in VSMC hypertrophy using spontaneously hypertensive rats (SHR). VSMC from 16-wk-old SHR and not from 12-wk-old SHR exhibited enhanced levels of Gqα/PLC-β1 proteins compared with age-matched Wistar-Kyoto (WKY) rats as determined by Western blotting. However, protein synthesis as determined by [(3)H]leucine incorporation was significantly enhanced in VSMC from both 12- and 16-wk-old SHR compared with VSMC from age-matched WKY rats. Furthermore, the knockdown of Gqα/PLC-β1 in VSMC from 16-wk-old SHR by antisense and small interfering RNA resulted in attenuation of protein synthesis. In addition, the enhanced expression of Gqα/PLC-β1 proteins, enhanced phosphorylation of ERK1/2, and enhanced protein synthesis in VSMC from SHR were attenuated by the ANG II AT1 and endothelin-1 (ET-1) ETA receptor antagonists losartan and BQ123, respectively, but not by the ETB receptor antagonist BQ788. In addition, PD98059 decreased the enhanced expression of Gqα/PLC-β1 and protein synthesis in VSMC from SHR. These results suggest that the enhanced levels of endogenous ANG II and ET-1 through the activation of AT1 and ETA receptors, respectively, and MAP kinase signaling, enhanced the expression of Gqα/PLC-β1 proteins in VSMC from 16-wk-old SHR and result in VSMC hypertrophy. Copyright © 2014 the American Physiological Society.

Development of an Enhanced Two-Phase Production System at the Geysers Geothermal Field; FINAL

International Nuclear Information System (INIS)

Steven Enedy

2001-01-01

A method was developed to enhance geothermal steam production from two-phase wells at THE Geysers Geothermal Field. The beneficial result was increased geothermal production that was easily and economically delivered to the power plant

Time variation of fluorescence lifetime in enhanced cyan fluorescence protein

International Nuclear Information System (INIS)

Lee, Soonhyouk; Kim, Soo Yong; Park, Kyoungsook; Jeong, Jinyoung; Chung, Bong Hyun; Kim, Sok Won

2010-01-01

The lifetime variations of enhanced cyan fluorescence protein (ECFP) in relatively short integration time bins were studied via time-correlated single photon counting (TCSPC) measurement. We observed that minimum photon counts are necessary for the lifetime estimation to achieve a certain range of variance. The conditions to decrease the variance of lifetime were investigated and the channel width of the measurement of TCSPC data was found to be another important factor for the variance of lifetime. Though the lifetime of ECFP is best fit by a double exponential, a mono exponential fit for the same integration time is more stable. The results may be useful in the analysis of photophysical dynamics for ensemble molecules in short measurement time windows.

Discovery of Enhanced Magnetoelectric Coupling through Electric Field Control of Two-Magnon Scattering within Distorted Nanostructures.

Science.gov (United States)

Xue, Xu; Zhou, Ziyao; Dong, Guohua; Feng, Mengmeng; Zhang, Yijun; Zhao, Shishun; Hu, Zhongqiang; Ren, Wei; Ye, Zuo-Guang; Liu, Yaohua; Liu, Ming

2017-09-26

Electric field control of dynamic spin interactions is promising to break through the limitation of the magnetostatic interaction based magnetoelectric (ME) effect. In this work, electric field control of the two-magnon scattering (TMS) effect excited by in-plane lattice rotation has been demonstrated in a La 0.7 Sr 0.3 MnO 3 (LSMO)/Pb(Mn 2/3 Nb 1/3 )-PbTiO 3 (PMN-PT) (011) multiferroic heterostructure. Compared with the conventional strain-mediated ME effect, a giant enhancement of ME effect up to 950% at the TMS critical angle is precisely determined by angular resolution of the ferromagnetic resonance (FMR) measurement. Particularly, a large electric field modulation of magnetic anisotropy (464 Oe) and FMR line width (401 Oe) is achieved at 173 K. The electric-field-controllable TMS effect and its correlated ME effect have been explained by electric field modulation of the planar spin interactions triggered by spin-lattice coupling. The enhancement of the ME effect at various temperatures and spin dynamics control are promising paradigms for next-generation voltage-tunable spintronic devices.

Calculated shape dependence of electromagnetic field in tip-enhanced Raman scattering by using a monopole antenna model

Science.gov (United States)

Kitahama, Yasutaka; Itoh, Tamitake; Suzuki, Toshiaki

2018-05-01

To evaluate the shape of an Ag tip with regard to tip-enhanced Raman scattering (TERS) signal, the enhanced electromagnetic (EM) field and scattering spectrum, arising from surface plasmon resonance at the apex of the tip, were calculated using a finite-difference time domain (FDTD) method. In the calculated forward scattering spectra from the smooth Ag tip, the band appeared within the visible region, similar to the experimental results and calculation for a corrugated Ag cone. In the FDTD calculation of TERS, the Ag tip acting as a monopole antenna was adopted by insertion of a perfect electric conductor between the root of the tip and a top boundary surface of the calculation space. As a result, the EM field was only enhanced at the apex. The shape dependence i.e. the EM field calculated at the apex with various curvatures on the different tapered tips, obtained using the monopole antenna model, was different from that simulated using a conventional dipole antenna model.

Enhancement and suppression in the visual field under perceptual load.

Science.gov (United States)

Parks, Nathan A; Beck, Diane M; Kramer, Arthur F

2013-01-01

The perceptual load theory of attention proposes that the degree to which visual distractors are processed is a function of the attentional demands of a task-greater demands increase filtering of irrelevant distractors. The spatial configuration of such filtering is unknown. Here, we used steady-state visual evoked potentials (SSVEPs) in conjunction with time-domain event-related potentials (ERPs) to investigate the distribution of load-induced distractor suppression and task-relevant enhancement in the visual field. Electroencephalogram (EEG) was recorded while subjects performed a foveal go/no-go task that varied in perceptual load. Load-dependent distractor suppression was assessed by presenting a contrast reversing ring at one of three eccentricities (2, 6, or 11°) during performance of the go/no-go task. Rings contrast reversed at 8.3 Hz, allowing load-dependent changes in distractor processing to be tracked in the frequency-domain. ERPs were calculated to the onset of stimuli in the load task to examine load-dependent modulation of task-relevant processing. Results showed that the amplitude of the distractor SSVEP (8.3 Hz) was attenuated under high perceptual load (relative to low load) at the most proximal (2°) eccentricity but not at more eccentric locations (6 or 11°). Task-relevant ERPs revealed a significant increase in N1 amplitude under high load. These results are consistent with a center-surround configuration of load-induced enhancement and suppression in the visual field.

Enhancement and Suppression in the Visual Field under Perceptual Load

Directory of Open Access Journals (Sweden)

Nathan A Parks

2013-05-01

Full Text Available The perceptual load theory of attention proposes that the degree to which visual distractors are processed is a function of the attentional demands of a task – greater demands increase filtering of irrelevant distractors. The spatial configuration of such filtering is unknown. Here, we used steady-state visual evoked potentials (SSVEPs in conjunction with time-domain event-related potentials (ERPs to investigate the distribution of load-induced distractor suppression and task-relevant enhancement in the visual field. Electroencephalogram (EEG was recorded while subjects performed a foveal go/no-go task that varied in perceptual load. Load-dependent distractor suppression was assessed by presenting a contrast reversing ring at one of three eccentricities (2°, 6°, or 11° during performance of the go/no-go task. Rings contrast reversed at 8.3 Hz, allowing load-dependent changes in distractor processing to be tracked in the frequency-domain. ERPs were calculated to the onset of stimuli in the load task to examine load-dependent modulation of task-relevant processing. Results showed that the amplitude of the distractor SSVEP (8.3Hz was attenuated under high perceptual load (relative to low load at the most proximal (2° eccentricity but not at more eccentric locations (6˚ or 11˚. Task-relevant ERPs revealed a significant increase in N1 amplitude under high load. These results are consistent with a center-surround configuration of load-induced enhancement and suppression in the visual field.

Pulsed electric field pretreatment of rapeseed green biomass (stems) to enhance pressing and extractives recovery.

Science.gov (United States)

Yu, X; Gouyo, T; Grimi, N; Bals, O; Vorobiev, E

2016-01-01

The objective of this study was to investigate the effects of pulsed electric field (PEF) pretreatment on the valorization of extractives (proteins and polyphenols) from rapeseed green biomass (stems) by pressing. The effect of pressure, electric field strength and pulse number on the juice expression yield, total polyphenols and total proteins content in the expressed juices were studied. Experiments conducted under optimal conditions (E = 8 kV/cm, tPEF = 2 ms, P = 10 bar) permitted to increase the juice expressed yield from 34% to 81%. Significant increases in total polyphenols content (0.48 vs. 0.10 g GAE/100g DM), in total proteins content (0.14 vs. 0.07 g BSA/100g DM) and in consolidation coefficient (9.0 × 10(-8) vs. 2.2 × 10(-8)m(2)/s) were also observed after PEF pretreatment. The recovered press cake was well dehydrated with an increase of dry matter content from 8.8% to 53.0%. Copyright © 2015 Elsevier Ltd. All rights reserved.

Flexible method for fabricating protein patterns on superhydrophobic platforms controlled by magnetic field.

Science.gov (United States)

Wang, Jian; Li, Hao; Zou, Haoyang; Wang, Chenmiao; Zhang, Hao; Mano, João F; Song, Wenlong

2017-02-28

Inspired by the rolling of water droplets on lotus leaves, we developed a novel, magnetic field-controlled patterning method for water-soluble proteins and other functional materials on superhydrophobic platforms. This simple method can be used to fabricate biochips and open micro-fluidic devices in a simple way.

Magnetic field enhanced photothermal effect of Fe3O4 nanoparticles

Science.gov (United States)

Pan, Pengfei; Lin, Yawen; Gan, Zhixing; Luo, Xiaobin; Zhou, Weiping; Zhang, Ning

2018-03-01

Photothermal and magnetothermal effects are promising in hyperthermia for cancer therapy. However, the development of safe treatments with limited side-effects requires a relatively-high thermal efficiency triggered by mild near-infrared (NIR) light and alternating magnetic field (HAC), which remains a formidable challenge. In this work, a magnetic field enhanced photothermal effect (MFEP) of Fe3O4 nanoparticles is proposed and investigated systematically. The results suggest remarkable temperature increments of 9.59 to 36.90 °C under irradiation of NIR with different light power densities (808 nm, 0-6.98 W/cm2) combined with a certain magnetic field (HAC = 1.5 kA/m at 90 kHz). The rise of temperature induced by MFEP is substantially larger than the sum of isolated photothermal and magnetothermal effects, which is attributed to the hot-phonon bottleneck effect. The MFEP of Fe3O4 nanoparticles could serve as an effective treatment for cancer therapy in the future.

Mosquito salivary gland protein preservation in the field for immunological and biochemical analysis

Directory of Open Access Journals (Sweden)

Almeras L

2011-03-01

Full Text Available Abstract Mosquito salivary proteins are involved in several biological processes that facilitate their blood feeding and have also been reported to elicit an IgG response in vertebrates. A growing number of studies have focused on this immunological response for its potential use as a biological marker of exposure to arthropod bites. As mosquito saliva collection is extremely laborious and inefficient, most research groups prefer to work on mosquito salivary glands (SGs. Thus, SG protein integrity is a critical factor in obtaining meaningful data from immunological and biochemical analysis. Current methodologies rely on an immediate freezing of SGs after their collection. However, the maintenance of samples in a frozen environment can be hard to achieve in field conditions. In this study, SG proteins from two mosquito species (Aedes aegypti and Anopheles gambiae s.s. stored in different media for 5 days at either +4°C or room temperature (RT were evaluated at the quantitative (i.e., ELISA and qualitative (i.e., SDS-PAGE and immunoblotting levels. Our results indicated that PBS medium supplemented with an anti-protease cocktail seems to be the best buffer to preserve SG antigens for 5 days at +4°C for ELISA analysis. Conversely, cell-lysis buffer (Urea-Thiourea-CHAPS-Tris was best at preventing protein degradation both at +4°C and RT for further qualitative analysis. These convenient storage methods provide an alternative to freezing and are expected to be applicable to other biological samples collected in the field.

Transitionless Enhanced Confinement and the Role of Radial Electric Field Shear

International Nuclear Information System (INIS)

Coppi, B.; Ernst, D.R.; Bell, M.G.; Bell, R.E.; Budny, R.V.

1999-01-01

Evidence for the role of radial electric field shear in enhanced confinement regimes attained without sharp bifurcations or transitions is presented. Temperature scans at constant density, created in the reheat phase following deuterium pellet injection into supershot plasmas in the Tokamak Fusion Test Reactor [J.D. Strachan, et al., Phys. Rev. Lett. 58 (1987) 1004] are simulated using a first-principles transport model. The slow reheat of the ion temperature profile, during which the temperature nearly doubles, is not explained by relatively comprehensive models of transport due to Ion Temperature Gradient Driven Turbulence (ITGDT), which depends primarily on the (unchanging) electron density gradient. An extended model, including the suppression of toroidal ITGDT by self-consistent radial electric field shear, does reproduce the reheat phase

Ripening of pepper (Capsicum annuum) fruit is characterized by an enhancement of protein tyrosine nitration.

Science.gov (United States)

Chaki, Mounira; Álvarez de Morales, Paz; Ruiz, Carmelo; Begara-Morales, Juan C; Barroso, Juan B; Corpas, Francisco J; Palma, José M

2015-09-01

Pepper (Capsicum annuum, Solanaceae) fruits are consumed worldwide and are of great economic importance. In most species ripening is characterized by important visual and metabolic changes, the latter including emission of volatile organic compounds associated with respiration, destruction of chlorophylls, synthesis of new pigments (red/yellow carotenoids plus xanthophylls and anthocyanins), formation of pectins and protein synthesis. The involvement of nitric oxide (NO) in fruit ripening has been established, but more work is needed to detail the metabolic networks involving NO and other reactive nitrogen species (RNS) in the process. It has been reported that RNS can mediate post-translational modifications of proteins, which can modulate physiological processes through mechanisms of cellular signalling. This study therefore examined the potential role of NO in nitration of tyrosine during the ripening of California sweet pepper. The NO content of green and red pepper fruit was determined spectrofluorometrically. Fruits at the breaking point between green and red coloration were incubated in the presence of NO for 1 h and then left to ripen for 3 d. Profiles of nitrated proteins were determined using an antibody against nitro-tyrosine (NO2-Tyr), and profiles of nitrosothiols were determined by confocal laser scanning microscopy. Nitrated proteins were identified by 2-D electrophoresis and MALDI-TOF/TOF analysis. Treatment with NO delayed the ripening of fruit. An enhancement of nitrosothiols and nitroproteins was observed in fruit during ripening, and this was reversed by the addition of exogenous NO gas. Six nitrated proteins were identified and were characterized as being involved in redox, protein, carbohydrate and oxidative metabolism, and in glutamate biosynthesis. Catalase was the most abundant nitrated protein found in both green and red fruit. The RNS profile reported here indicates that ripening of pepper fruit is characterized by an enhancement of S

Quantitative electrical detection of immobilized protein using gold nanoparticles and gold enhancement on a biochip

International Nuclear Information System (INIS)

Lei, Kin Fong

2011-01-01

Electrical detection of the concentration of protein immobilized on a biochip is demonstrated. The concentration of the direct immobilized protein can be determined by the resistance values measured by an ohm-meter directly. Indium tin oxide interdigitated electrodes were utilized as the detection sites on the biochip. Protein, i.e. antibody, of certain concentration was first immobilized on the detection site. Gold nanoparticles were then applied to indicate the immobilized protein. Since the gold nanoparticles were tiny, a detectable electrical signal could not be generated. Hence, a gold enhancement process was performed for signal amplification. Gold nanoparticles were enlarged physically, such that a conductive metal layer was formed on the detection site. The presence and concentration of protein can be determined by the resistance value across the electrode measured by an ohm-meter. An immobilized protein concentration ranging from 50 to 1000 ng ml −1 can be detected quantitatively by the resistance values from 4300 to 1700 Ω. The proposed technique is potentially extended for the detection of immunoassay on the biochip. Since the protocol of the electrical detection does not involve sophisticated equipment, it can therefore be used for the development of a portable immunoassay device

The experimental research of a field-enhanced multichannel oil switch

International Nuclear Information System (INIS)

Zhao, R.; Zeng, N.; Yang, D.; Jiang, X.; Wang, X.

1993-01-01

This paper describes the performance of a field enhanced multichannel oil switch which is used as the main switch of HEAVEN-LIGHT II intense pulsed electron beam accelerator at CIAE. The switch experiments have been carried out with different inductance of the solenoid inductor in series with a self-closing axial gap and position and diameter of the trigger disc. The experiments using water as a breakdown medium of the switch have been done to compare with oil switch. These experimental results and conclusions are presented in the paper

Enhanced deterministic phase retrieval using a partially developed speckle field

DEFF Research Database (Denmark)

Almoro, Percival F.; Waller, Laura; Agour, Mostafa

2012-01-01

A technique for enhanced deterministic phase retrieval using a partially developed speckle field (PDSF) and a spatial light modulator (SLM) is demonstrated experimentally. A smooth test wavefront impinges on a phase diffuser, forming a PDSF that is directed to a 4f setup. Two defocused speckle...... intensity measurements are recorded at the output plane corresponding to axially-propagated representations of the PDSF in the input plane. The speckle intensity measurements are then used in a conventional transport of intensity equation (TIE) to reconstruct directly the test wavefront. The PDSF in our...

Regulation of the Drosophila Enhancer of split and invected-engrailed gene complexes by sister chromatid cohesion proteins.

Directory of Open Access Journals (Sweden)

Cheri A Schaaf

2009-07-01

Full Text Available The cohesin protein complex was first recognized for holding sister chromatids together and ensuring proper chromosome segregation. Cohesin also regulates gene expression, but the mechanisms are unknown. Cohesin associates preferentially with active genes, and is generally absent from regions in which histone H3 is methylated by the Enhancer of zeste [E(z] Polycomb group silencing protein. Here we show that transcription is hypersensitive to cohesin levels in two exceptional cases where cohesin and the E(z-mediated histone methylation simultaneously coat the entire Enhancer of split and invected-engrailed gene complexes in cells derived from Drosophila central nervous system. These gene complexes are modestly transcribed, and produce seven of the twelve transcripts that increase the most with cohesin knockdown genome-wide. Cohesin mutations alter eye development in the same manner as increased Enhancer of split activity, suggesting that similar regulation occurs in vivo. We propose that cohesin helps restrain transcription of these gene complexes, and that deregulation of similarly cohesin-hypersensitive genes may underlie developmental deficits in Cornelia de Lange syndrome.

Hall effect enhanced low-field sensitivity in a three-contact extraordinary magnetoresistance sensor

KAUST Repository

Sun, Jian

2012-06-06

An extraordinary magnetoresistance (EMR) device with a 3-contact geometry has been fabricated and characterized. A large enhancement of the output sensitivity at low magnetic fields compared to the conventional EMR device has been found, which can be attributed to an additional influence coming from the Hall effect. Output sensitivities of 0.19 mV/T at zero-field and 0.2 mV/T at 0.01 T have been measured in the device, which is equivalent to the ones of the conventional EMR sensors with a bias of ∼0.04 T. The exceptional performance of EMR sensors in the high field region is maintained in the 3-contact device.

Differential expression of candidate salivary effector proteins in field collections of Hessian fly, Mayetiola destructor

Science.gov (United States)

Johnson, A J; Shukle, R H; Chen, M-S; Srivastava, S; Subramanyam, S; Schemerhorn, B J; Weintraub, P G; Abdel Moniem, H E M; Flanders, K L; Buntin, G D; Williams, C E

2015-01-01

Evidence is emerging that some proteins secreted by gall-forming parasites of plants act as effectors responsible for systemic changes in the host plant, such as galling and nutrient tissue formation. A large number of secreted salivary gland proteins (SSGPs) that are the putative effectors responsible for the physiological changes elicited in susceptible seedling wheat by Hessian fly, Mayetiola destructor (Say), larvae have been documented. However, how the genes encoding these candidate effectors might respond under field conditions is unknown. The goal of this study was to use microarray analysis to investigate variation in SSGP transcript abundance amongst field collections from different geographical regions (southeastern USA, central USA, and the Middle East). Results revealed significant variation in SSGP transcript abundance amongst the field collections studied. The field collections separated into three distinct groups that corresponded to the wheat classes grown in the different geographical regions as well as to recently described Hessian fly populations. These data support previous reports correlating Hessian fly population structure with micropopulation differences owing to agro-ecosystem parameters such as cultivation of regionally adapted wheat varieties, deployment of resistance genes and variation in climatic conditions. PMID:25528896

Double-chimera proteins to enhance recruitment of endothelial cells and their progenitor cells.

Science.gov (United States)

Behjati, M; Kazemi, M; Hashemi, M; Zarkesh-Esfahanai, S H; Bahrami, E; Hashemi-Beni, B; Ahmadi, R

2013-08-20

Enhanced attraction of selective vascular reparative cells is of great importance in order to increase vascular patency after endovascular treatments. We aimed to evaluate efficient attachment of endothelial cells and their progenitors on surfaces coated with mixture of specific antibodies, L-selectin and VE-cadherin, with prohibited platelet attachment. The most efficient conditions for coating of L-selectin-Fc chimera and VE-cadherin-Fc chimera proteins were first determined by protein coating on ELISA plates. The whole processes were repeated on titanium substrates, which are commonly used to coat stents. Endothelial progenitor cells (EPCs) and human umbilical vein endothelial cells (HUVECs) were isolated and characterized by flow cytometry. Cell attachment, growth, proliferation, viability and surface cytotoxicity were evaluated using nuclear staining and MTT assay. Platelet and cell attachment were evaluated using scanning electron microscopy. Optimal concentration of each protein for surface coating was 50 ng/ml. The efficacy of protein coating was both heat and pH independent. Calcium ions had significant impact on simultaneous dual-protein coating (P<0.05). Coating stability data revealed more than one year stability for these coated proteins at 4°C. L-selectin and VE-cadherin (ratio of 50:50) coated surface showed highest EPC and HUVEC attachment, viability and proliferation compared to single protein coated and non-coated titanium surfaces (P<0.05). This double coated surface did not show any cytotoxic effect. Surfaces coated with L-selectin and VE-cadherin are friendly surface for EPC and endothelial cell attachment with less platelet attachment. These desirable factors make the L-selectin and VE-cadherin coated surfaces perfect candidate endovascular device. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Optimising the Use of TRIzol-extracted Proteins in Surface Enhanced Laser Desorption/ Ionization (SELDI Analysis

Directory of Open Access Journals (Sweden)

Perlaky Laszlo

2006-03-01

Full Text Available Abstract Background Research with clinical specimens is always hampered by the limited availability of relevant samples, necessitating the use of a single sample for multiple assays. TRIzol is a common reagent for RNA extraction, but DNA and protein fractions can also be used for other studies. However, little is known about using TRIzol-extracted proteins in proteomic research, partly because proteins extracted from TRIzol are very resistant to solubilization. Results To facilitate the use of TRIzol-extracted proteins, we first compared the ability of four different common solubilizing reagents to solubilize the TRIzol-extracted proteins from an osteosarcoma cell line, U2-OS. Then we analyzed the solubilized proteins by Surface Enhanced Laser Desorption/ Ionization technique (SELDI. The results showed that solubilization of TRIzol-extracted proteins with 9.5 M Urea and 2% CHAPS ([3-[(3-cholamidopropyl-dimethylammonio]propanesulfonate] (UREA-CHAPS was significantly better than the standard 1% SDS in terms of solubilization efficiency and the number of detectable ion peaks. Using three different types of SELDI arrays (CM10, H50, and IMAC-Cu, we demonstrated that peak detection with proteins solubilized by UREA-CHAPS was reproducible (r > 0.9. Further SELDI analysis indicated that the number of ion peaks detected in TRIzol-extracted proteins was comparable to a direct extraction method, suggesting many proteins still remain in the TRIzol protein fraction. Conclusion Our results suggest that UREA-CHAPS performed very well in solubilizing TRIzol-extracted proteins for SELDI applications. Protein fractions left over after TRIzol RNA extraction could be a valuable but neglected source for proteomic or biochemical analysis when additional samples are not available.

Label-Free Detection of Glycan-Protein Interactions for Array Development by Surface-Enhanced Raman Spectroscopy (SERS)

NARCIS (Netherlands)

Li, Xiuru; Martin, Sharon J H; Chinoy, Zoeisha S; Liu, Lin; Rittgers, Brandon; Dluhy, Richard A; Boons, Geert-Jan

2016-01-01

A glyco-array platform has been developed, in which glycans are attached to plasmonic nanoparticles through strain-promoted azide-alkyne cycloaddition. Glycan-protein binding events can then be detected in a label-free manner employing surface-enhanced Raman spectroscopy (SERS). As proof of concept,

Time-domain electric field enhancement on micrometer scale in coupled split ring resonator upon terahertz radiation

DEFF Research Database (Denmark)

Lange, Simon Lehnskov; Iwaszczuk, Krzysztof; Hoffmann, Matthias

2016-01-01

We present here a novel design for a coupled split ring resonator antenna optimized for time-domain electric field enhancement in the 0.1 to 1 terahertz (THz) range. The antenna is designed to be sensitive to the incident field polarization and seeks to avoid metal damage due to electron bombardm...

Enhanced exchange bias fields for CoO/Co bilayers: influence of antiferromagnetic grains and mechanisms

Energy Technology Data Exchange (ETDEWEB)

Chang, Cheng-Hsun-Tony; Chang, Shin-Chen [Department of Physics, National Taiwan Normal University, Taipei 116, Taiwan (China); Tsay, Jyh-Shen, E-mail: jstsay@phy.ntnu.edu.tw [Department of Physics, National Taiwan Normal University, Taipei 116, Taiwan (China); Yao, Yeong-Der [Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan (China)

2017-05-31

Highlights: • An antiferromagnetic grain model on exchange bias phenomena is proposed. • Grain size and grain density are considered. • For smaller grain size, the dependence of t{sub CoO} on T{sub B} showed a less pronounced variation. • An increased grain density is responsible for the enhancement in the exchange bias fields. - Abstract: The emergence and optimization of devices that can be applied to spintronics have attracted considerable interest, and both experimental and theoretical approaches have been used in studies of exchange bias phenomena. A survey of the literature indicates that great efforts have been devoted to improving exchange bias fields, while only limited attempts have been made to control the temperature dependence of exchange bias. In this study, the influence of antiferromagnetic grains on exchange bias phenomena in CoO/Co bilayers on a semiconductor surface was investigated. Based on an antiferromagnetic grain model, a correlation between grain size, grain density, blocking temperature, and the exchange bias field was established. For crystallites with a smaller median diameter, the dependence of the thickness of the CoO layer on blocking temperature showed a less pronounced variation. This is due to the larger thermal agitation of the atomic spin moments in the grain, which causes a weaker exchange coupling between atomic spin moments. The enhanced density of antiferromagnetic/ferromagnetic pinning sites resulting from an increased grain density is responsible for the enhancement in the exchange bias fields. The results reported herein provide insights into our knowledge related to controlling the temperature dependence of exchange bias and related mechanisms.

Dynamic contrast-enhanced imaging of the wrist in rheumatoid arthritis: dedicated low-field (0.25-T) versus high-field (3.0-T) MRI

Energy Technology Data Exchange (ETDEWEB)

Lee, Ryan K.L.; Griffith, James F.; Wang, D.F.; Yeung, David K.W. [The Chinese University of Hong Kong, Department of Imaging and Interventional Radiology, Prince Of Wales Hospital, Hong Kong, SAR (China); Shi, L. [The Chinese University of Hong Kong, Department of Medicine and Therapeutics, Division of Neurology, Hong Kong, SAR (China); Li, Edmund K.; Tam, L.S. [The Chinese University of Hong Kong, Department of Medicine, Division of Rheumatology, Prince Of Wales Hospital, Hong Kong, SAR (China)

2015-08-15

To compare the assessment of wrist synovitis severity, synovial volume and synovial perfusion parameters on a dedicated low-field (0.25-T) to that of a high-field (3-T) whole-body MR system in patients with rheumatoid arthritis (RA). Twenty-one patients (mean age 50.0 ± 9.8 years) with active RA were recruited prospectively. Dynamic contrast-enhanced MRI examination of the most severely affected wrist was performed at both 0.25 T and 3 T. Three MRI-derived parameters, synovitis severity (RAMRIS grade), synovial volume (ml{sup 3}) and synovial perfusion indices (maximum enhancement and enhancement slope), were compared. Comparing 0.25- and 3-T MRI, there was excellent agreement for semiquantitative assessment (r: 0.80, p < 0.00001) of synovitis (RAMRIS) as well as quantitative assessment (r: 0.94, p < 0.00001) of synovial volume. Good agreement for synovial Emax (r: 0.6, p = 0.002) and fair agreement (r: 0.5, p = 0.02) for synovial Eslope was found. Imaging of the RA wrist at 0.25 T yields excellent correlation with 3 T with regard to the synovitis activity score (RAMRIS) and synovial volume measurement. Fair to good correlation between low- (0.25-T) and high-field (3-T) MR systems was found for perfusion parameters, being better for Emax than for Eslope. (orig.)

DNA-modified electrodes fabricated using copper-free click chemistry for enhanced protein detection.

Science.gov (United States)

Furst, Ariel L; Hill, Michael G; Barton, Jacqueline K

2013-12-31

A method of DNA monolayer formation has been developed using copper-free click chemistry that yields enhanced surface homogeneity and enables variation in the amount of DNA assembled; extremely low-density DNA monolayers, with as little as 5% of the monolayer being DNA, have been formed. These DNA-modified electrodes (DMEs) were characterized visually, with AFM, and electrochemically, and were found to facilitate DNA-mediated reduction of a distally bound redox probe. These low-density monolayers were found to be more homogeneous than traditional thiol-modified DNA monolayers, with greater helix accessibility through an increased surface area-to-volume ratio. Protein binding efficiency of the transcriptional activator TATA-binding protein (TBP) was also investigated on these surfaces and compared to that on DNA monolayers formed with standard thiol-modified DNA. Our low-density monolayers were found to be extremely sensitive to TBP binding, with a signal decrease in excess of 75% for 150 nM protein. This protein was detectable at 4 nM, on the order of its dissociation constant, with our low-density monolayers. The improved DNA helix accessibility and sensitivity of our low-density DNA monolayers to TBP binding reflects the general utility of this method of DNA monolayer formation for DNA-based electrochemical sensor development.

Characterization of the nutritional value of air-classified protein and starch fractions of field pea and zero-tannin faba bean in grower pigs.

Science.gov (United States)

Gunawardena, C K; Zijlstra, R T; Beltranena, E

2010-02-01

Most pulse (nonoilseed legume) seed flours can be fractionated rapidly and economically by air classification into protein and starch concentrates. The nutritional value of air-classified field pea and faba bean concentrates requires characterization to assess the feeding opportunity for pigs. Thus, the objectives were to characterize the apparent total tract digestibility (ATTD) of DM, OM, energy, starch, CP, fat, and ash; apparent ileal digestibility of CP and starch; standardized ileal digestibility (SID) of AA; and the SID AA, DE, and NE content of air-classified zero-tannin faba bean and field pea protein and starch concentrates in grower pigs. Pulse protein and starch concentrates were compared with soy protein concentrate and corn starch, respectively, as corresponding standards. The corn starch diet served as an N-free diet to correct for basal endogenous AA losses. In a Youden square design, 8 ileal-cannulated barrows (24.9 +/- 2.3 kg of BW) were fed 6 diets over 7 periods at 3 times the maintenance DE requirement. Periods encompassed a 5-d diet acclimation, 3-d feces collection, and 3-d ileal digesta collection. The ATTD of GE was 2% greater (P bean than soy and was intermediate for field pea protein (95.6, 93.7, and 94.9%, respectively). The ATTD of GE was 3.6% greater (P bean starch (96.2, 95.1, and 92.3%, respectively). The DE content of faba bean was 5.0% greater (P soy protein (4.47, 4.23, and 4.26 Mcal/kg, respectively). The DE content of faba bean and field pea was 1.7% greater (P bean than field pea and soy protein (3.08, 2.94, and 2.92 Mcal/kg, respectively). The NE content for field pea starch was 2.0% greater (P bean starch (2.68, 2.63, and 2.61 Mcal/kg, respectively). Protein concentrates had a 14 and 11% greater (P bean and field pea protein than soy protein (95.5, 92.6, and 88.7%, respectively). The SID of Lys was 6.0% greater (P bean than field pea starch. Nutrient digestibility and digestible nutrient profiles indicated that air

Introduction to current and future protein therapeutics: a protein engineering perspective.

Science.gov (United States)

Carter, Paul J

2011-05-15

Protein therapeutics and its enabling sister discipline, protein engineering, have emerged since the early 1980s. The first protein therapeutics were recombinant versions of natural proteins. Proteins purposefully modified to increase their clinical potential soon followed with enhancements derived from protein or glycoengineering, Fc fusion or conjugation to polyethylene glycol. Antibody-based drugs subsequently arose as the largest and fastest growing class of protein therapeutics. The rationale for developing better protein therapeutics with enhanced efficacy, greater safety, reduced immunogenicity or improved delivery comes from the convergence of clinical, scientific, technological and commercial drivers that have identified unmet needs and provided strategies to address them. Future protein drugs seem likely to be more extensively engineered to improve their performance, e.g., antibodies and Fc fusion proteins with enhanced effector functions or extended half-life. Two old concepts for improving antibodies, namely antibody-drug conjugates and bispecific antibodies, have advanced to the cusp of clinical success. As for newer protein therapeutic platform technologies, several engineered protein scaffolds are in early clinical development and offer differences and some potential advantages over antibodies. Copyright © 2011 Elsevier Inc. All rights reserved.

A relativistic self-consistent model for studying enhancement of space charge limited field emission due to counter-streaming ions

International Nuclear Information System (INIS)

Lin, M. C.; Lu, P. S.; Chang, P. C.; Ragan-Kelley, B.; Verboncoeur, J. P.

2014-01-01

Recently, field emission has attracted increasing attention despite the practical limitation that field emitters operate below the Child-Langmuir space charge limit. By introducing counter-streaming ion flow to neutralize the electron charge density, the space charge limited field emission (SCLFE) current can be dramatically enhanced. In this work, we have developed a relativistic self-consistent model for studying the enhancement of SCLFE by a counter-streaming ion current. The maximum enhancement is found when the ion effect is saturated, as shown analytically. The solutions in non-relativistic, intermediate, and ultra-relativistic regimes are obtained and verified with 1-D particle-in-cell simulations. This self-consistent model is general and can also serve as a benchmark or comparison for verification of simulation codes, as well as extension to higher dimensions

Enhancement of adsorption and diffusion of lithium in single-walled carbon nanotubes by external electric field

Energy Technology Data Exchange (ETDEWEB)

Shi, Wenwu; Wang, Zhiguo, E-mail: zgwang@uestc.edu.cn; Fu, Y.Q., E-mail: richard.fu@northumbria.ac.uk [University of Electronic Science and Technology of China, School of Physical Electronics, Center for Public Security Information and Equipment Integration Technology (China)

2016-11-15

Effects of an external transverse electric field on the adsorption and diffusion of Li atoms on the single-walled carbon nanotubes (CNTs) were investigated using density functional theory. Results showed that the adsorption energy was significantly enhanced by applying the electric field. As the external electric field was increased from 0.0 to 0.6 V/Å, the adsorption energies were decreased from −1.37 to −2.31, −1.32 to −2.46, and −1.33 to −2.63 eV for the Li atoms adsorbed on (6,6), (8,8), and (10,10) CNTs, respectively. Meanwhile, the diffusion barriers of the Li atoms on the CNTs were also decreased as the external electric field was applied. When the external electric field was increased from 0.0 to 0.6 V/Å, the energy barriers were decreased from 0.42, 0.40, and 0.39 eV to 0.20, 0.17, and 0.15 eV for Li diffusion in the (6,6), (8,8), and (10,10) CNTs, respectively. The results proved that an external electric field can be applied to enhance the adsorption and diffusion of Li atoms on the CNTs (used as the anode) for lithium ion batteries.

Enhancement of adsorption and diffusion of lithium in single-walled carbon nanotubes by external electric field

International Nuclear Information System (INIS)

Shi, Wenwu; Wang, Zhiguo; Fu, Y.Q.

2016-01-01

Effects of an external transverse electric field on the adsorption and diffusion of Li atoms on the single-walled carbon nanotubes (CNTs) were investigated using density functional theory. Results showed that the adsorption energy was significantly enhanced by applying the electric field. As the external electric field was increased from 0.0 to 0.6 V/Å, the adsorption energies were decreased from −1.37 to −2.31, −1.32 to −2.46, and −1.33 to −2.63 eV for the Li atoms adsorbed on (6,6), (8,8), and (10,10) CNTs, respectively. Meanwhile, the diffusion barriers of the Li atoms on the CNTs were also decreased as the external electric field was applied. When the external electric field was increased from 0.0 to 0.6 V/Å, the energy barriers were decreased from 0.42, 0.40, and 0.39 eV to 0.20, 0.17, and 0.15 eV for Li diffusion in the (6,6), (8,8), and (10,10) CNTs, respectively. The results proved that an external electric field can be applied to enhance the adsorption and diffusion of Li atoms on the CNTs (used as the anode) for lithium ion batteries.

Electrostatics of proteins in dielectric solvent continua. I. An accurate and efficient reaction field description.

Science.gov (United States)

Bauer, Sebastian; Mathias, Gerald; Tavan, Paul

2014-03-14

We present a reaction field (RF) method which accurately solves the Poisson equation for proteins embedded in dielectric solvent continua at a computational effort comparable to that of an electrostatics calculation with polarizable molecular mechanics (MM) force fields. The method combines an approach originally suggested by Egwolf and Tavan [J. Chem. Phys. 118, 2039 (2003)] with concepts generalizing the Born solution [Z. Phys. 1, 45 (1920)] for a solvated ion. First, we derive an exact representation according to which the sources of the RF potential and energy are inducible atomic anti-polarization densities and atomic shielding charge distributions. Modeling these atomic densities by Gaussians leads to an approximate representation. Here, the strengths of the Gaussian shielding charge distributions are directly given in terms of the static partial charges as defined, e.g., by standard MM force fields for the various atom types, whereas the strengths of the Gaussian anti-polarization densities are calculated by a self-consistency iteration. The atomic volumes are also described by Gaussians. To account for covalently overlapping atoms, their effective volumes are calculated by another self-consistency procedure, which guarantees that the dielectric function ε(r) is close to one everywhere inside the protein. The Gaussian widths σ(i) of the atoms i are parameters of the RF approximation. The remarkable accuracy of the method is demonstrated by comparison with Kirkwood's analytical solution for a spherical protein [J. Chem. Phys. 2, 351 (1934)] and with computationally expensive grid-based numerical solutions for simple model systems in dielectric continua including a di-peptide (Ac-Ala-NHMe) as modeled by a standard MM force field. The latter example shows how weakly the RF conformational free energy landscape depends on the parameters σ(i). A summarizing discussion highlights the achievements of the new theory and of its approximate solution particularly by

Electrostatics of proteins in dielectric solvent continua. I. An accurate and efficient reaction field description

Energy Technology Data Exchange (ETDEWEB)

Bauer, Sebastian; Mathias, Gerald; Tavan, Paul, E-mail: paul.tavan@physik.uni-muenchen.de [Lehrstuhl für BioMolekulare Optik, Ludwig–Maximilians Universität München, Oettingenstr. 67, 80538 München (Germany)

2014-03-14

We present a reaction field (RF) method which accurately solves the Poisson equation for proteins embedded in dielectric solvent continua at a computational effort comparable to that of an electrostatics calculation with polarizable molecular mechanics (MM) force fields. The method combines an approach originally suggested by Egwolf and Tavan [J. Chem. Phys. 118, 2039 (2003)] with concepts generalizing the Born solution [Z. Phys. 1, 45 (1920)] for a solvated ion. First, we derive an exact representation according to which the sources of the RF potential and energy are inducible atomic anti-polarization densities and atomic shielding charge distributions. Modeling these atomic densities by Gaussians leads to an approximate representation. Here, the strengths of the Gaussian shielding charge distributions are directly given in terms of the static partial charges as defined, e.g., by standard MM force fields for the various atom types, whereas the strengths of the Gaussian anti-polarization densities are calculated by a self-consistency iteration. The atomic volumes are also described by Gaussians. To account for covalently overlapping atoms, their effective volumes are calculated by another self-consistency procedure, which guarantees that the dielectric function ε(r) is close to one everywhere inside the protein. The Gaussian widths σ{sub i} of the atoms i are parameters of the RF approximation. The remarkable accuracy of the method is demonstrated by comparison with Kirkwood's analytical solution for a spherical protein [J. Chem. Phys. 2, 351 (1934)] and with computationally expensive grid-based numerical solutions for simple model systems in dielectric continua including a di-peptide (Ac-Ala-NHMe) as modeled by a standard MM force field. The latter example shows how weakly the RF conformational free energy landscape depends on the parameters σ{sub i}. A summarizing discussion highlights the achievements of the new theory and of its approximate solution

Two Year Field Study to Evaluate the Efficacy of Mamestra brassicae Nucleopolyhedrovirus Combined with Proteins Derived from Xestia c-nigrum Granulovirus

Directory of Open Access Journals (Sweden)

Chie Goto

2015-03-01

Full Text Available Japan has only three registered baculovirus biopesticides despite its long history of studies on insect viruses. High production cost is one of the main hindrances for practical use of baculoviruses. Enhancement of insecticidal effect is one possible way to overcome this problem, so there have been many attempts to develop additives for baculoviruses. We found that alkaline soluble proteins of capsules (GVPs of Xestia c-nigrum granulovirus can increase infectivity of some viruses including Mamestra brassicae nucleopolyhedrovirus (MabrNPV, and previously reported that MabrNPV mixed with GVPs was highly infectious to three important noctuid pests of vegetables in the following order, Helicoverpa armigera, M. brassicae, and Autographa nigrisigna. In this study, small-plot experiments were performed to assess concentrations of MabrNPV and GVPs at three cabbage fields and a broccoli field for the control of M. brassicae. In the first experiment, addition of GVPs (10 µg/mL to MabrNPV at 106 OBs/mL resulted in a significant increase in NPV infection (from 53% to 66%. In the second experiment, the enhancing effect of GVP on NPV infection was confirmed at 10-times lower concentrations of MabrNPV. In the third and fourth experiments, a 50% reduction in GVPs (from 10 µg/mL to 5 µg/mL did not result in a lowering of infectivity of the formulations containing MabrNPV at 105 OBs/mL. These results indicate that GVPs are promising additives for virus insecticides.

Correlations of filtration flux enhanced by electric fields in crossflow microfiltration

Energy Technology Data Exchange (ETDEWEB)

Okada, K.; Nagase, Y. [Kurashiki University of Science and the Arts, Okayama (Japan). Department of Chemical Technology; Ohnishi, Y.; Nishihan, A.; Akagi, Y. [Okayama University of Science, Okayama (Japan). Department of Applied Chemistry

1997-12-01

The steady state filtration flux in electrically-enhanced crossflow microfiltration is estimated using a correlation equation proposed for several kinds of suspensions. Baker`s yeast and Rhodotorula glutinis were used as model samples of microbial cells, and PMMA particles were used as samples of non-living solids. Application of the electric field in crossflow microfiltration is a useful method for improving the filtration flux of these samples. High flux levels for the cells were achieved when an electric field above 3000 V/m was applied. The effect of the electric field in increasing the filtration flux of the steady state was analyzed theoretically using a force balance model where the viscous drag force, F{sub J}, the electrophoretic force, F{sub E}, and the re-entraining force, F{sub B}, were considered to act on a particle on the membrane surface under a steady state of filtration, respectively. From force balance analysis, it is found that on application of an electric field, the electro-osmotic effect can be neglected in the present study, so that the filtration flux of the steady state, J{sub ES}, can be presented by, J{sub ES}=U{sub EP}E+J{sub OS} where U{sub EP} is the electrophoretic mobility of particles and E is the electric field applied. J{sub OS} is the filtration flux in the absence of an electric field, which is correlated with the operating parameters for suspensions tested. 22 refs., 7 figs., 1 tab.

Enhancing the performance of the light field microscope using wavefront coding.

Science.gov (United States)

Cohen, Noy; Yang, Samuel; Andalman, Aaron; Broxton, Michael; Grosenick, Logan; Deisseroth, Karl; Horowitz, Mark; Levoy, Marc

2014-10-06

Light field microscopy has been proposed as a new high-speed volumetric computational imaging method that enables reconstruction of 3-D volumes from captured projections of the 4-D light field. Recently, a detailed physical optics model of the light field microscope has been derived, which led to the development of a deconvolution algorithm that reconstructs 3-D volumes with high spatial resolution. However, the spatial resolution of the reconstructions has been shown to be non-uniform across depth, with some z planes showing high resolution and others, particularly at the center of the imaged volume, showing very low resolution. In this paper, we enhance the performance of the light field microscope using wavefront coding techniques. By including phase masks in the optical path of the microscope we are able to address this non-uniform resolution limitation. We have also found that superior control over the performance of the light field microscope can be achieved by using two phase masks rather than one, placed at the objective's back focal plane and at the microscope's native image plane. We present an extended optical model for our wavefront coded light field microscope and develop a performance metric based on Fisher information, which we use to choose adequate phase masks parameters. We validate our approach using both simulated data and experimental resolution measurements of a USAF 1951 resolution target; and demonstrate the utility for biological applications with in vivo volumetric calcium imaging of larval zebrafish brain.

Tip enhancement

CERN Document Server

Kawata, Satoshi

2007-01-01

This book discusses the recent advances in the area of near-field Raman scattering, mainly focusing on tip-enhanced and surface-enhanced Raman scattering. Some of the key features covered here are the optical structuring and manipulations, single molecule sensitivity, analysis of single-walled carbon nanotubes, and analytic applications in chemistry, biology and material sciences. This book also discusses the plasmonic materials for better enhancement, and optical antennas. Further, near-field microscopy based on second harmonic generation is also discussed. Chapters have been written by some of the leading scientists in this field, who present some of their recent work in this field.·Near-field Raman scattering·Tip-enhanced Raman spectroscopy·Surface-enhanced Raman spectroscopy·Nano-photonics·Nanoanalysis of Physical, chemical and biological materials beyond the diffraction limits·Single molecule detection

Fluctuation reduction and enhanced confinement in the MST reversed-field pinch

International Nuclear Information System (INIS)

Chapman, B.E.

1997-10-01

Plasmas with a factor of ≥3 improvement in energy confinement have been achieved in the MST reversed-field pinch (RFP). These plasmas occur spontaneously, following sawtooth crashes, subject to constraints on, eg, toroidal magnetic field reversal and wall conditioning. Possible contributors to the improved confinement include a reduction of core-resonant, global magnetic fluctuations and a reduction of electrostatic fluctuations over the entire plasma edge. One feature of these plasmas is a region of strong ExB flow shear in the edge. Never before observed in conjunction with enhanced confinement in the RFP, such shear is common in enhanced confinement discharges in tokamaks and stellarators. Another feature of these plasmas is a new type of discrete dynamo event. Like sawtooth crashes, a common form of discrete dynamo, these events correspond to bursts of edge parallel current. The reduction of electrostatic fluctuations in these plasmas occurs within and beyond the region of strong ExB flow shear, similar to what is observed in tokamaks and stellarators. However, the reductions in the MST include fluctuations whose correlation lengths are larger than the width of the shear region. The reduction of the global magnetic fluctuations is most likely due to flattening of the μ=μ 0 rvec J· rvec B/B 2 profile. Flattening can occur, eg, due to the new type of discrete dynamo event and reduced edge resistivity. Enhanced confinement plasmas are also achieved in the MST when auxiliary current is applied to flatten the μ profile and reduce magnetic fluctuations. Unexpectedly, these plasmas also exhibit a region (broader than in the case above) of strong ExB flow shear in the edge, an edge-wide reduction of electrostatic fluctuations, and the new type of discrete dynamo event. Auxiliary current drive has historically been viewed as the principal route to fusion reactor viability for the RFP

Leucine supplementation of a chronically restricted protein and energy diet enhances mTOR pathway activation but not muscle protein synthesis in neonatal pigs.

Science.gov (United States)

Manjarín, Rodrigo; Columbus, Daniel A; Suryawan, Agus; Nguyen, Hanh V; Hernandez-García, Adriana D; Hoang, Nguyet-Minh; Fiorotto, Marta L; Davis, Teresa

2016-01-01

Suboptimal nutrient intake represents a limiting factor for growth and long-term survival of low-birth weight infants. The objective of this study was to determine if in neonates who can consume only 70 % of their protein and energy requirements for 8 days, enteral leucine supplementation will upregulate the mammalian target of rapamycin (mTOR) pathway in skeletal muscle, leading to an increase in protein synthesis and muscle anabolism. Nineteen 4-day-old piglets were fed by gastric tube 1 of 3 diets, containing (kg body weight(-1) · day(-1)) 16 g protein and 190 kcal (CON), 10.9 g protein and 132 kcal (R), or 10.8 g protein + 0.2 % leucine and 136 kcal (RL) at 4-h intervals for 8 days. On day 8, plasma AA and insulin levels were measured during 6 post-feeding intervals, and muscle protein synthesis rate and mTOR signaling proteins were determined at 120 min post-feeding. At 120 min, leucine was highest in RL (P protein synthesis, phosphorylation of S6 kinase (p-S6K1) and 4E-binding protein (p-4EBP1), and activation of eukaryotic initiation factor 4 complex (eIF4E · eIF4G). RL increased (P ≤ 0.01) p-S6K1, p-4EBP1 and eIF4E · eIF4G compared to R. In conclusion, when protein and energy intakes are restricted for 8 days, leucine supplementation increases muscle mTOR activation, but does not improve body weight gain or enhance skeletal muscle protein synthesis in neonatal pigs.

Nitrogen detected TROSY at high field yields high resolution and sensitivity for protein NMR

Energy Technology Data Exchange (ETDEWEB)

Takeuchi, Koh [National Institute for Advanced Industrial Science and Technology, Molecular Profiling Research Center for Drug Discovery (Japan); Arthanari, Haribabu [Harvard Medical School, Department of Biochemistry and Molecular Pharmacology (United States); Shimada, Ichio, E-mail: shimada@iw-nmr.f.u-tokyo.ac.jp [National Institute for Advanced Industrial Science and Technology, Molecular Profiling Research Center for Drug Discovery (Japan); Wagner, Gerhard, E-mail: gerhard-wagner@hms.harvard.edu [Harvard Medical School, Department of Biochemistry and Molecular Pharmacology (United States)

2015-12-15

Detection of {sup 15}N in multidimensional NMR experiments of proteins has sparsely been utilized because of the low gyromagnetic ratio (γ) of nitrogen and the presumed low sensitivity of such experiments. Here we show that selecting the TROSY components of proton-attached {sup 15}N nuclei (TROSY {sup 15}N{sub H}) yields high quality spectra in high field magnets (>600 MHz) by taking advantage of the slow {sup 15}N transverse relaxation and compensating for the inherently low {sup 15}N sensitivity. The {sup 15}N TROSY transverse relaxation rates increase modestly with molecular weight but the TROSY gain in peak heights depends strongly on the magnetic field strength. Theoretical simulations predict that the narrowest line width for the TROSY {sup 15}N{sub H} component can be obtained at 900 MHz, but sensitivity reaches its maximum around 1.2 GHz. Based on these considerations, a {sup 15}N-detected 2D {sup 1}H–{sup 15}N TROSY-HSQC ({sup 15}N-detected TROSY-HSQC) experiment was developed and high-quality 2D spectra were recorded at 800 MHz in 2 h for 1 mM maltose-binding protein at 278 K (τ{sub c} ∼ 40 ns). Unlike for {sup 1}H detected TROSY, deuteration is not mandatory to benefit {sup 15}N detected TROSY due to reduced dipolar broadening, which facilitates studies of proteins that cannot be deuterated, especially in cases where production requires eukaryotic expression systems. The option of recording {sup 15}N TROSY of proteins expressed in H{sub 2}O media also alleviates the problem of incomplete amide proton back exchange, which often hampers the detection of amide groups in the core of large molecular weight proteins that are expressed in D{sub 2}O culture media and cannot be refolded for amide back exchange. These results illustrate the potential of {sup 15}N{sub H}-detected TROSY experiments as a means to exploit the high resolution offered by high field magnets near and above 1 GHz.

Enhanced fatty acid oxidation and FATP4 protein expression after endurance exercise training in human skeletal muscle

DEFF Research Database (Denmark)

Jeppesen, Jacob; Jordy, Andreas B; Sjøberg, Kim A

2012-01-01

; however, it is not known whether this involves up-regulation of FATP1 and FATP4 protein. Therefore, the aim of this project was to investigate FATP1 and FATP4 protein expression in the vastus lateralis muscle from healthy human individuals and to what extent FATP1 and FATP4 protein expression were......FATP1 and FATP4 appear to be important for the cellular uptake and handling of long chain fatty acids (LCFA). These findings were obtained from loss- or gain of function models. However, reports on FATP1 and FATP4 in human skeletal muscle are limited. Aerobic training enhances lipid oxidation...

Deep recurrent conditional random field network for protein secondary prediction

DEFF Research Database (Denmark)

Johansen, Alexander Rosenberg; Sønderby, Søren Kaae; Sønderby, Casper Kaae

2017-01-01

Deep learning has become the state-of-the-art method for predicting protein secondary structure from only its amino acid residues and sequence profile. Building upon these results, we propose to combine a bi-directional recurrent neural network (biRNN) with a conditional random field (CRF), which...... of the labels for all time-steps. We condition the CRF on the output of biRNN, which learns a distributed representation based on the entire sequence. The biRNN-CRF is therefore close to ideally suited for the secondary structure task because a high degree of cross-talk between neighboring elements can...

Mammalian-enabled (MENA) protein enhances oncogenic potential and cancer stem cell-like phenotype in hepatocellular carcinoma cells.

Science.gov (United States)

Hu, Kunpeng; Huang, Pinzhu; Luo, Hui; Yao, Zhicheng; Wang, Qingliang; Xiong, Zhiyong; Lin, Jizong; Huang, He; Xu, Shilei; Zhang, Peng; Liu, Bo

2017-08-01

Mammalian-enabled (MENA) protein is an actin-regulatory protein that influences cell motility and adhesion. It is known to play a role in tumorigenicity of hepatocellular carcinoma (HCC) but the underlying molecular mechanism remains unknown. This study aimed to investigate the oncogenic potential of MENA and its capacity to regulate cancer stem cell (CSC)-like phenotypes in HCC cells. Real-time-PCR and western blot were used to assess mRNA and protein levels of target genes in human HCC tissue specimens and HCC cell lines, respectively. Stable MENA-overexpressing HCC cells were generated from HCC cell lines. Transwell cell migration and colony formation assays were employed to evaluate tumorigenicity. Ectopic expression of MENA significantly enhanced cell migration and colony-forming ability in HCC cells. Overexpression of MENA upregulated several hepatic progenitor/stem cell markers in HCC cells. A high MENA protein level was associated with high mRNA levels of MENA, CD133, cytokeratin 19 (CK19), and epithelial cell adhesion molecule (EpCAM) in human HCC tissues. Overexpression of MENA enhanced epithelial-to-mesenchymal transition (EMT) markers, extracellular signal-regulated kinases (ERK) phosphorylation, and the level of β-catenin in HCC cells. This study demonstrated that overexpression of MENA in HCC cells promoted stem cell markers, EMT markers, and tumorigenicity. These effects may involve, at least partially, the ERK and β-catenin signaling pathways.

Entropic potential field formed for a linear-motor protein near a filament: Statistical-mechanical analyses using simple models.

Science.gov (United States)

Amano, Ken-Ichi; Yoshidome, Takashi; Iwaki, Mitsuhiro; Suzuki, Makoto; Kinoshita, Masahiro

2010-07-28

We report a new progress in elucidating the mechanism of the unidirectional movement of a linear-motor protein (e.g., myosin) along a filament (e.g., F-actin). The basic concept emphasized here is that a potential field is entropically formed for the protein on the filament immersed in solvent due to the effect of the translational displacement of solvent molecules. The entropic potential field is strongly dependent on geometric features of the protein and the filament, their overall shapes as well as details of the polyatomic structures. The features and the corresponding field are judiciously adjusted by the binding of adenosine triphosphate (ATP) to the protein, hydrolysis of ATP into adenosine diphosphate (ADP)+Pi, and release of Pi and ADP. As the first step, we propose the following physical picture: The potential field formed along the filament for the protein without the binding of ATP or ADP+Pi to it is largely different from that for the protein with the binding, and the directed movement is realized by repeated switches from one of the fields to the other. To illustrate the picture, we analyze the spatial distribution of the entropic potential between a large solute and a large body using the three-dimensional integral equation theory. The solute is modeled as a large hard sphere. Two model filaments are considered as the body: model 1 is a set of one-dimensionally connected large hard spheres and model 2 is a double helical structure formed by two sets of connected large hard spheres. The solute and the filament are immersed in small hard spheres forming the solvent. The major findings are as follows. The solute is strongly confined within a narrow space in contact with the filament. Within the space there are locations with sharply deep local potential minima along the filament, and the distance between two adjacent locations is equal to the diameter of the large spheres constituting the filament. The potential minima form a ringlike domain in model 1

Multitriggered Tumor-Responsive Drug Delivery Vehicles Based on Protein and Polypeptide Coassembly for Enhanced Photodynamic Tumor Ablation.

Science.gov (United States)

Zhang, Ning; Zhao, Fenfang; Zou, Qianli; Li, Yongxin; Ma, Guanghui; Yan, Xuehai

2016-11-01

Tumor-responsive nanocarriers are highly valuable and demanded for smart drug delivery particularly in the field of photodynamic therapy (PDT), where a quick release of photosensitizers in tumors is preferred. Herein, it is demonstrated that protein-based nanospheres, prepared by the electrostatic assembly of proteins and polypeptides with intermolecular disulfide cross-linking and surface polyethylene glycol coupling, can be used as versatile tumor-responsive drug delivery vehicles for effective PDT. These nanospheres are capable of encapsulation of various photosensitizers including Chlorin e6 (Ce6), protoporphyrin IX, and verteporfin. The Chlorin e6-encapsulated nanospheres (Ce6-Ns) are responsive to changes in pH, redox potential, and proteinase concentration, resulting in multitriggered rapid release of Ce6 in an environment mimicking tumor tissues. In vivo fluorescence imaging results indicate that Ce6-Ns selectively accumulate near tumors and the quick release of Ce6 from Ce6-Ns can be triggered by tumors. In tumors the fluorescence of released Ce6 from Ce6-Ns is observed at 0.5 h postinjection, while in normal tissues the fluorescence appeared at 12 h postinjection. Tumor ablation is demonstrated by in vivo PDT using Ce6-Ns and the biocompatibility of Ce6-Ns is evident from the histopathology imaging, confirming the enhanced in vivo PDT efficacy and the biocompatibility of the assembled drug delivery vehicles. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Specific Increase of Protein Levels by Enhancing Translation Using Antisense Oligonucleotides Targeting Upstream Open Frames.

Science.gov (United States)

Liang, Xue-Hai; Shen, Wen; Crooke, Stanley T

2017-01-01

A number of diseases are caused by low levels of key proteins; therefore, increasing the amount of specific proteins in human bodies is of therapeutic interest. Protein expression is downregulated by some structural or sequence elements present in the 5' UTR of mRNAs, such as upstream open reading frames (uORF). Translation initiation from uORF(s) reduces translation from the downstream primary ORF encoding the main protein product in the same mRNA, leading to a less efficient protein expression. Therefore, it is possible to use antisense oligonucleotides (ASOs) to specifically inhibit translation of the uORF by base-pairing with the uAUG region of the mRNA, redirecting translation machinery to initiate from the primary AUG site. Here we review the recent findings that translation of specific mRNAs can be enhanced using ASOs targeting uORF regions. Appropriately designed and optimized ASOs are highly specific, and they act in a sequence- and position-dependent manner, with very minor off-target effects. Protein levels can be increased using this approach in different types of human and mouse cells, and, importantly, also in mice. Since uORFs are present in around half of human mRNAs, the uORF-targeting ASOs may thus have valuable potential as research tools and as therapeutics to increase the levels of proteins for a variety of genes.

Interface control: A modified rooting technique for enhancing field emission from multiwall carbon nanotube based bulk emitters

Energy Technology Data Exchange (ETDEWEB)

Lahiri, Indranil [Nanomaterials and Device Lab, Department of Mechanical and Materials Engineering, Florida International University, 10555 West Flagler Street, Miami, FL 33174 (United States); Choi, Wonbong, E-mail: choiw@fiu.edu [Nanomaterials and Device Lab, Department of Mechanical and Materials Engineering, Florida International University, 10555 West Flagler Street, Miami, FL 33174 (United States)

2011-08-15

The unique properties of carbon nanotubes (CNTs) have raised hopes that these materials might find wide application as cold cathodes in various electron sources. The excellent field emission properties shown by CNT-based field emitters has further stimulated this expectation. However, efficient performance of a practical field emitter, which comprises a large number of randomly or regularly oriented CNTs, is restricted primarily due to poor junctions formed between CNTs and substrates. This study is aimed at enhancing the junction performance by way of a modified 'rooting' technique-interface control. In this process, the interface between CNTs and substrate has been tailored with different metals in an attempt to improve the CNT-substrate junction performance. Multiwall carbon nanotubes (MWCNTs) were synthesized on different interface-controlled substrates, i.e. Cu, Al, W, Si and low-temperature co-fired ceramic. All the samples produced mat-type, randomly oriented MWCNT structures. Among the four different substrates studied, MWCNT-based field emitters on Cu substrate demonstrated the best field emission response, in terms of low turn-on field, high emission current, good field enhancement factor and excellent stability in long-term operation. Emitter structures and their field emission behavior were correlated and it was shown that interface control, as an advanced 'rooting' process, plays an important role in determining the emission response from a bulk field emitter.

Interface control: A modified rooting technique for enhancing field emission from multiwall carbon nanotube based bulk emitters

International Nuclear Information System (INIS)

Lahiri, Indranil; Choi, Wonbong

2011-01-01

The unique properties of carbon nanotubes (CNTs) have raised hopes that these materials might find wide application as cold cathodes in various electron sources. The excellent field emission properties shown by CNT-based field emitters has further stimulated this expectation. However, efficient performance of a practical field emitter, which comprises a large number of randomly or regularly oriented CNTs, is restricted primarily due to poor junctions formed between CNTs and substrates. This study is aimed at enhancing the junction performance by way of a modified 'rooting' technique-interface control. In this process, the interface between CNTs and substrate has been tailored with different metals in an attempt to improve the CNT-substrate junction performance. Multiwall carbon nanotubes (MWCNTs) were synthesized on different interface-controlled substrates, i.e. Cu, Al, W, Si and low-temperature co-fired ceramic. All the samples produced mat-type, randomly oriented MWCNT structures. Among the four different substrates studied, MWCNT-based field emitters on Cu substrate demonstrated the best field emission response, in terms of low turn-on field, high emission current, good field enhancement factor and excellent stability in long-term operation. Emitter structures and their field emission behavior were correlated and it was shown that interface control, as an advanced 'rooting' process, plays an important role in determining the emission response from a bulk field emitter.

[Influence of extremely low frequency magnetic field on total protein and -sh groups concentrations in liver homogenates].

Science.gov (United States)

Ciejka, Elżbieta; Kowalczyk, Agata; Gorąca, Anna

2014-01-01

Free radicals are atoms, molecules or their fragments, whose excess leads to the development of oxidative stress, the cause of many neoplastic, neurodegenerative and inflammatory diseases, as well as aging of organisms. Industrial pollution, tobacco smoke, ionizing radiation, ultrasound and magnetic fields are the major exogenous sources of free radicals. The low frequency mag- netic field is commonly applied in physiotherapy. The aim of the present study was to evaluate the effect of extremely low frequency magnetic field (1L.F-MF) on the concentration ofsullhydryl groups (-SH) and proteins in liver tissues of experimental animals de- pending on the time of exposure to the field. Twenty one Sprague-D)awley male rats, aged 3-4 months were randomly divided into 3 experimental groups (each containing 7 animals): controls (group I), the rats exposed to IEI.F-MF of 40 Hz, 7 mT (this kind of the ELF-MF is mostly used in magnetotherapy), 30 min/day for 2 weeks (group II) and the rats exposed to 40 Hz, 7 mT for 60 min/day for 2 weeks (group III). The concentrations of proteins and sulfhydryl groups in the liver tissues were determined after exposure to magnetic fields. Exposure to low magnetic field: 40 Hz, 7 mT for 30 min/day and 60 min/day for 2 weeks caused a significant increase in the concentration of-SH groups and total protein levels in the liver tissues. The study results suggest that exposure to magnetic fields leads to the development of adaptive mechanisms to maintain the balance in the body oxidation-reduction and in the case of the studied parameters does not depend on the time of exposure.

Highly thermostable fluorescent proteins

Science.gov (United States)

Bradbury, Andrew M [Santa Fe, NM; Waldo, Geoffrey S [Santa Fe, NM; Kiss, Csaba [Los Alamos, NM

2011-03-22

Thermostable fluorescent proteins (TSFPs), methods for generating these and other stability-enhanced proteins, polynucleotides encoding such proteins, and assays and method for using the TSFPs and TSFP-encoding nucleic acid molecules are provided. The TSFPs of the invention show extremely enhanced levels of stability and thermotolerance. In one case, for example, a TSFP of the invention is so stable it can be heated to 99.degree. C. for short periods of time without denaturing, and retains 85% of its fluorescence when heated to 80.degree. C. for several minutes. The invention also provides a method for generating stability-enhanced variants of a protein, including but not limited to fluorescent proteins.

The enhanced cyan fluorescent protein: a sensitive pH sensor for fluorescence lifetime imaging.

Science.gov (United States)

Poëa-Guyon, Sandrine; Pasquier, Hélène; Mérola, Fabienne; Morel, Nicolas; Erard, Marie

2013-05-01

pH is an important parameter that affects many functions of live cells, from protein structure or function to several crucial steps of their metabolism. Genetically encoded pH sensors based on pH-sensitive fluorescent proteins have been developed and used to monitor the pH of intracellular compartments. The quantitative analysis of pH variations can be performed either by ratiometric or fluorescence lifetime detection. However, most available genetically encoded pH sensors are based on green and yellow fluorescent proteins and are not compatible with multicolor approaches. Taking advantage of the strong pH sensitivity of enhanced cyan fluorescent protein (ECFP), we demonstrate here its suitability as a sensitive pH sensor using fluorescence lifetime imaging. The intracellular ECFP lifetime undergoes large changes (32 %) in the pH 5 to pH 7 range, which allows accurate pH measurements to better than 0.2 pH units. By fusion of ECFP with the granular chromogranin A, we successfully measured the pH in secretory granules of PC12 cells, and we performed a kinetic analysis of intragranular pH variations in living cells exposed to ammonium chloride.

Enhanced protein loading on a planar Si(111)-H surface with second generation NTA

Science.gov (United States)

Liu, Xiang; Han, Huan-Mei; Liu, Hong-Bo; Xiao, Shou-jun

2010-08-01

A Si(111)-H surface was modified via a direct reaction between Si-H and 1-undecylenic acid (UA) under microwave irradiation to form molecular monolayers with terminal carboxyl groups. After esterifying carboxylic acid being esterified with N-hydroxysuccinimide (NHS), aminobutyl nitrilotriacetic acid (ANTA) was bound to the silicon surface through amidation (pH = 8.0) between its primary amino group and NHS-ester, producing nitrilotriacetic acid (NTA) anions. Then hexa-histidine tagged thioredoxin-urodilatin (his-tagged protein) and FITC-labeled hexa-histidine tagged thioredoxin-urodilatin (FITC-his-tagged protein) can be anchored after NTA was coordinated with Ni 2+. Furthermore, the NTA-terminated chip was acidified with 0.1 M HCl and subsequently esterified with NHS and then amidated with ANTA again to produce a second generation NTA. Thus the surface density of nitrilotriacetic acid anions was improved and resultantly that of anchored proteins was also enhanced through the iterative reactions. Both multiple transmission-reflection infrared spectroscopy (MTR-IR) and fluorescence scanning measurements demonstrated a proximate 1.63 times of anchored proteins on the second generation NTA/Ni 2+ as that on the first generation NTA/Ni 2+ monolayer.

Sensitivity enhanced NMR spectroscopy by quenching scalar coupling mediated relaxation: Application to the direct observation of hydrogen bonds in 13C/15N-labeled proteins

Energy Technology Data Exchange (ETDEWEB)

Liu Aizhuo; Hu Weidong; Qamar, Seema; Majumdar, Ananya [Memorial Sloan-Kettering Cancer Center, Cellular Biochemistry and Biophysics Program (United States)

2000-05-15

In this paper, we demonstrate that the sensitivity of triple-resonance NMR experiments can be enhanced significantly through quenching scalar coupling mediated relaxation by using composite-pulse decoupling (CPD) or an adiabatic decoupling sequence on aliphatic, in particular alpha-carbons in {sup 13}C/{sup 15}N-labeled proteins. The CPD-HNCO experiment renders 50% sensitivity enhancement over the conventional CT-HNCO experiment performed on a 12 kDa FK506 binding protein, when a total of 266 ms of amide nitrogen-carbonyl carbon defocusing and refocusing periods is employed. This is a typical time period for the direct detection of hydrogen bonds in proteins via trans-hydrogen bond {sup 3h}J{sub NC'} couplings. The experimental data fit theoretical analysis well. The significant enhancement in sensitivity makes the experiment more applicable to larger-sized proteins without resorting to perdeuteration.

Actinidin enhances protein digestion in the small intestine as assessed using an in vitro digestion model.

Science.gov (United States)

Kaur, Lovedeep; Rutherfurd, Shane M; Moughan, Paul J; Drummond, Lynley; Boland, Mike J

2010-04-28

This paper describes an in vitro study that tests the proposition that actinidin from green kiwifruit influences the digestion of proteins in the small intestine. Different food proteins, from sources including soy, meat, milk, and cereals, were incubated in the presence or absence of green kiwifruit extract (containing actinidin) using a two-stage in vitro digestion system consisting of an incubation with pepsin at stomach pH (simulating gastric digestion) and then with added pancreatin at small intestinal pH, simulating upper tract digestion in humans. The digests from the small intestinal stage (following the gastric digestion phase) were subjected to gel electrophoresis (SDS-PAGE) to assess loss of intact protein and development of large peptides during the in vitro simulated digestion. Kiwifruit extract influenced the digestion patterns of all of the proteins to various extents. For some proteins, actinidin had little impact on digestion. However, for other proteins, the presence of kiwifruit extract resulted in a substantially greater loss of intact protein and different peptide patterns from those seen after digestion with pepsin and pancreatin alone. In particular, enhanced digestion of whey protein isolate, zein, gluten, and gliadin was observed. In addition, reverse-phase HPLC (RP-HPLC) analysis showed that a 2.5 h incubation of sodium caseinate with kiwifruit extract alone resulted in approximately 45% loss of intact protein.

A Plasmodium Promiscuous T Cell Epitope Delivered within the Ad5 Hexon Protein Enhances the Protective Efficacy of a Protein Based Malaria Vaccine.

Directory of Open Access Journals (Sweden)

Jairo Andres Fonseca

Full Text Available A malaria vaccine is a public health priority. In order to produce an effective vaccine, a multistage approach targeting both the blood and the liver stage infection is desirable. The vaccine candidates also need to induce balanced immune responses including antibodies, CD4+ and CD8+ T cells. Protein-based subunit vaccines like RTS,S are able to induce strong antibody response but poor cellular reactivity. Adenoviral vectors have been effective inducing protective CD8+ T cell responses in several models including malaria; nonetheless this vaccine platform exhibits a limited induction of humoral immune responses. Two approaches have been used to improve the humoral immunogenicity of recombinant adenovirus vectors, the use of heterologous prime-boost regimens with recombinant proteins or the genetic modification of the hypervariable regions (HVR of the capsid protein hexon to express B cell epitopes of interest. In this study, we describe the development of capsid modified Ad5 vectors that express a promiscuous Plasmodium yoelii T helper epitope denominated PyT53 within the hexon HVR2 region. Several regimens were tested in mice to determine the relevance of the hexon modification in enhancing protective immune responses induced by the previously described protein-based multi-stage experimental vaccine PyCMP. A heterologous prime-boost immunization regime that combines a hexon modified vector with transgenic expression of PyCMP followed by protein immunizations resulted in the induction of robust antibody and cellular immune responses in comparison to a similar regimen that includes a vector with unmodified hexon. These differences in immunogenicity translated into a better protective efficacy against both the hepatic and red blood cell stages of P. yoelii. To our knowledge, this is the first time that a hexon modification is used to deliver a promiscuous T cell epitope. Our data support the use of such modification to enhance the immunogenicity

Plasma-treated polystyrene film that enhances binding efficiency for sensitive and label-free protein biosensing

Energy Technology Data Exchange (ETDEWEB)

Guo, Bihong [National Center for NanoScience and Technology, No. 11 Beiyitiao, Zhongguancun, Beijing 100190 (China); Li, Shaopeng [National Center for NanoScience and Technology, No. 11 Beiyitiao, Zhongguancun, Beijing 100190 (China); Department of Chemistry, Tsinghua University, Beijing 100084 (China); Song, Lusheng [National Center for NanoScience and Technology, No. 11 Beiyitiao, Zhongguancun, Beijing 100190 (China); Yang, Mo; Zhou, Wenfei; Tyagi, Deependra [National Center for NanoScience and Technology, No. 11 Beiyitiao, Zhongguancun, Beijing 100190 (China); University of Chinese Academy of Sciences, Yuquan Rd., 19(A), Beijing 100049 (China); Zhu, Jinsong, E-mail: jizhu88@gmail.com [National Center for NanoScience and Technology, No. 11 Beiyitiao, Zhongguancun, Beijing 100190 (China)

2015-08-01

Highlights: • A simple and robust plasma-treated ultrathin polystyrene film surface was developed for protein biosensing. • The surface was optimized by evaluating up to 120 types of fabrication parameters with high-throughput analytical methods. • The optimized surface showed a 620% improvement of the protein detection signal and 210% protein binding per immobilized protein ligand compared with a self-assembled monolayer surface. - Abstract: A plasma-treated ultrathin polystyrene (PS) film surface was explored as a simple, robust, and low-cost surface chemistry solution for protein biosensing applications. This surface could dramatically improve the binding efficiency of the protein–protein interactions, which is defined as the binding signal per immobilized ligand. The PS-modified protein biosensor was readily fabricated by spin coating and plasma treatment. Various parameters for fabrication, including the concentration of the PS solution, rate of spin coating, and duration of plasma treatment, were systematically optimized based on the improvement of fluorescence signal yielded by the microfluidic network-aided fluorescence immunoassay. The performance of the label-free protein detection on the optimized surfaces was further evaluated by surface plasmon resonance imaging (SPRi). PS surfaces with optimal fabrication parameters exhibited up to an 620% enhancement of the protein binding response and approximately 210% of the protein binding per immobilized protein ligand compared with a self-assembled monolayer (SAM) surface of 11-mercapto undecanoic acid (MUA). The relationship between the fabrication parameters used and changes to the surface chemistry and the morphological properties were characterized with atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). It was revealed that the morphological changes observed in the plasma-treated PS film were the dominant factor for the

Field test for treatment verification of an in-situ enhanced bioremediation study

International Nuclear Information System (INIS)

Taur, C.K.; Chang, S.C.

1995-01-01

Due to a leakage from a 12-inch pressurized diesel steel pipe four years ago, an area of approximately 30,000 square meters was contaminated. A pilot study applying the technology of in-situ enhanced bioremediation was conducted. In the study, a field test kit and on-site monitoring equipment were applied for site characterization and treatment verification. Physically, the enhanced bioremediation study consisted of an air extraction and air supply system, and a nutrition supply network. Certain consistent sampling methodology was employed. Progress was verified by daily monitoring and monthly verification. The objective of this study was to evaluate the capabilities of indigenous microorganisms to biodegrade the petroleum hydrocarbons with provision of oxygen and nutrients. Nine extraction wells and eight air sparging wells were installed. The air sparging wells injected the air into geoformation and the extraction wells provided the underground air circulation. The soil samples were obtained monthly for treatment verification by a Minuteman drilling machine with 2.5-foot-long hollow-stem augers. The samples were analyzed on site for TPH-diesel concentration by a field test kit manufactured by HNU-Hanby, Houston, Texas. The analytical results from the field test kit were compared with the results from an environmental laboratory. The TVPH concentrations of the air extracted from the vadose zone by a vacuum blower and the extraction wells were routinely monitored by a Foxboro FID and Cosmos XP-311A combustible air detector. The daily monitoring of TVPH concentrations provided the reliable data for assessing the remedial progress

The potential of chitosan in enhancing peptide and protein absorption across the TR146 cell culture model-an in vitro model of the buccal epithelium

DEFF Research Database (Denmark)

Portero, Ana; Remuñán-López, Carmen; Nielsen, Hanne Mørck

2002-01-01

To investigate the potential of chitosan (CS) to enhance buccal peptide and protein absorption, the TR146 cell culture model, a model of the buccal epithelium, was used.......To investigate the potential of chitosan (CS) to enhance buccal peptide and protein absorption, the TR146 cell culture model, a model of the buccal epithelium, was used....

Enhancement of electron emission and long-term stability of tip-type carbon nanotube field emitters via lithium coating

International Nuclear Information System (INIS)

Kim, Jong-Pil; Chang, Han-Beet; Kim, Bu-Jong; Park, Jin-Seok

2013-01-01

Carbon nanotubes (CNTs) were deposited on conical tip-type substrates via electrophoresis and coated with lithium (Li) thin films with diverse thicknesses via electroplating. For the as-deposited (i.e., without Li coating) CNT, the turn-on (or triggering) electric field was 0.92 V/μm, and the emission current, which was generated at an applied field of 1.2 V/μm was 56 μA. In the case of the 4.7 nm-thick Li-coated CNT, the turn-on field decreased to 0.65 V/μm and the emission current at the same applied field increased more than ten times to 618 μA. The analysis based on the Kelvin probe measurement and Fowler–Nordheim theory indicated that the coating of Li caused a loss in the structural-aspect-ratio of the CNTs and it reduced their effective work functions from 5.36 eV to 4.90 eV, which led to a great improvement of their electron emission characteristics. The results obtained in this study also showed that the long-term emission stability could be enhanced by the coating of thin Li films on CNTs. - Highlights: ► CNTs are deposited via electrophoretic deposition (EPD). ► Thin films of Li are coated on CNTs via electroplating, without plasma damage. ► Li coating enhanced field emission properties and emission stability of CNTs. ► The effective work functions and field enhancement factors of CNTs are evaluated

Prediction of thermodynamic instabilities of protein solutions from simple protein–protein interactions

International Nuclear Information System (INIS)

D’Agostino, Tommaso; Solana, José Ramón; Emanuele, Antonio

2013-01-01

Highlights: ► We propose a model of effective protein–protein interaction embedding solvent effects. ► A previous square-well model is enhanced by giving to the interaction a free energy character. ► The temperature dependence of the interaction is due to entropic effects of the solvent. ► The validity of the original SW model is extended to entropy driven phase transitions. ► We get good fits for lysozyme and haemoglobin spinodal data taken from literature. - Abstract: Statistical thermodynamics of protein solutions is often studied in terms of simple, microscopic models of particles interacting via pairwise potentials. Such modelling can reproduce the short range structure of protein solutions at equilibrium and predict thermodynamics instabilities of these systems. We introduce a square well model of effective protein–protein interaction that embeds the solvent’s action. We modify an existing model [45] by considering a well depth having an explicit dependence on temperature, i.e. an explicit free energy character, thus encompassing the statistically relevant configurations of solvent molecules around proteins. We choose protein solutions exhibiting demixing upon temperature decrease (lysozyme, enthalpy driven) and upon temperature increase (haemoglobin, entropy driven). We obtain satisfactory fits of spinodal curves for both the two proteins without adding any mean field term, thus extending the validity of the original model. Our results underline the solvent role in modulating or stretching the interaction potential

SELECTION AND TREATMENT OF STRIPPER GAS WELLS FOR PRODUCTION ENHANCEMENT, MOCANE-LAVERNE FIELD, OKLAHOMA

Energy Technology Data Exchange (ETDEWEB)

Scott Reeves; Buckley Walsh

2003-08-01

In 1996, Advanced Resources International (ARI) began performing R&D targeted at enhancing production and reserves from natural gas fields. The impetus for the effort was a series of field R&D projects in the early-to-mid 1990's, in eastern coalbed methane and gas shales plays, where well remediation and production enhancement had been successfully demonstrated. As a first step in the R&D effort, an assessment was made of the potential for restimulation to provide meaningful reserve additions to the U.S. gas resource base, and what technologies were needed to do so. That work concluded that: (1) A significant resource base did exist via restimulation (multiples of Tcf). (2) The greatest opportunities existed in non-conventional plays where completion practices were (relatively) complex and technology advancement was rapid. (3) Accurate candidate selection is the greatest single factor that contributes to a successful restimulation program. With these findings, a field-oriented program targeted at tight sand formations was initiated to develop and demonstrate successful candidate recognition technology. In that program, which concluded in 2001, nine wells were restimulated in the Green River, Piceance and East Texas basins, which in total added 2.9 Bcf of reserves at an average cost of $0.26/Mcf. In addition, it was found that in complex and heterogeneous reservoirs (such as tight sand formations), candidate selection procedures should involve a combination of fundamental engineering and advanced pattern recognition approaches, and that simple statistical methods for identifying candidate wells are not effective. In mid-2000, the U.S. Department of Energy (DOE) awarded ARI an R&D contract to determine if the methods employed in that project could also be applied to stripper gas wells. In addition, the ability of those approaches to identify more general production enhancement opportunities (beyond only restimulation), such as via artificial lift and compression

Protein nanoparticles for therapeutic protein delivery.

Science.gov (United States)

Herrera Estrada, L P; Champion, J A

2015-06-01

Therapeutic proteins can face substantial challenges to their activity, requiring protein modification or use of a delivery vehicle. Nanoparticles can significantly enhance delivery of encapsulated cargo, but traditional small molecule carriers have some limitations in their use for protein delivery. Nanoparticles made from protein have been proposed as alternative carriers and have benefits specific to therapeutic protein delivery. This review describes protein nanoparticles made by self-assembly, including protein cages, protein polymers, and charged or amphipathic peptides, and by desolvation. It presents particle fabrication and delivery characterization for a variety of therapeutic and model proteins, as well as comparison of the features of different protein nanoparticles.

Both core and F proteins of hepatitis C virus could enhance cell proliferation in transgenic mice

Energy Technology Data Exchange (ETDEWEB)

Hu, Wen-Ta [Graduate Institute of Medical Biotechnology, Tzu Chi University, Hualien, Taiwan (China); Li, Hui-Chun [Department of Biochemistry, Tzu Chi University, Hualien, Taiwan (China); Lee, Shen-Kao; Ma, Hsin-Chieh; Yang, Chee-Hing; Chen, Hung-Ling [Graduate Institute of Medical Biotechnology, Tzu Chi University, Hualien, Taiwan (China); Lo, Shih-Yen, E-mail: losylo@mail.tcu.edu.tw [Graduate Institute of Medical Biotechnology, Tzu Chi University, Hualien, Taiwan (China); Department of Laboratory Medicine, Buddhist Tzu Chi General Hospital, Hualien, Taiwan (China)

2013-05-24

Highlights: •HCV core and F proteins could induce hepatocyte proliferation in the transgenic mice. •β-Catenin signaling pathway was activated by core protein in the transgenic mice. •β-Catenin signaling pathway was activated by myc-F protein in the transgenic mice. •Expression of SMA protein was enhanced by core but not myc-F protein. -- Abstract: The role of the protein encoded by the alternative open reading frame (ARF/F/core+1) of the Hepatitis C virus (HCV) genome in viral pathogenesis remains unknown. The different forms of ARF/F/core+1 protein were labile in cultured cells, a myc-tag fused at the N-terminus of the F protein made it more stable. To determine the role of core and F proteins in HCV pathogenesis, transgenic mice with either protein expression under the control of Albumin promoter were generated. Expression of core protein and F protein with myc tag (myc-F) could be detected by Western blotting analysis in the livers of these mice. The ratio of liver to body weight is increased for both core and myc-F transgenic mice compared to that of wild type mice. Indeed, the proliferating cell nuclear antigen protein, a proliferation marker, was up-regulated in the transgenic mice with core or myc-F protein. Further analyses by microarray and Western blotting suggested that β-catenin signaling pathway was activated by either core or myc-F protein in the transgenic mice. These transgenic mice were further treated with either Diethynitrosamine (a tumor initiator) or Phenobarbital (a tumor promoter). Phenobarbital but not Diethynitrosamine treatment could increase the liver/body weight ratio of these mice. However, no tumor formation was observed in these mice. In conclusion, HCV core and myc-F proteins could induce hepatocyte proliferation in the transgenic mice possibly through β-catenin signaling pathway.

Both core and F proteins of hepatitis C virus could enhance cell proliferation in transgenic mice

International Nuclear Information System (INIS)

Hu, Wen-Ta; Li, Hui-Chun; Lee, Shen-Kao; Ma, Hsin-Chieh; Yang, Chee-Hing; Chen, Hung-Ling; Lo, Shih-Yen

2013-01-01

Highlights: •HCV core and F proteins could induce hepatocyte proliferation in the transgenic mice. •β-Catenin signaling pathway was activated by core protein in the transgenic mice. •β-Catenin signaling pathway was activated by myc-F protein in the transgenic mice. •Expression of SMA protein was enhanced by core but not myc-F protein. -- Abstract: The role of the protein encoded by the alternative open reading frame (ARF/F/core+1) of the Hepatitis C virus (HCV) genome in viral pathogenesis remains unknown. The different forms of ARF/F/core+1 protein were labile in cultured cells, a myc-tag fused at the N-terminus of the F protein made it more stable. To determine the role of core and F proteins in HCV pathogenesis, transgenic mice with either protein expression under the control of Albumin promoter were generated. Expression of core protein and F protein with myc tag (myc-F) could be detected by Western blotting analysis in the livers of these mice. The ratio of liver to body weight is increased for both core and myc-F transgenic mice compared to that of wild type mice. Indeed, the proliferating cell nuclear antigen protein, a proliferation marker, was up-regulated in the transgenic mice with core or myc-F protein. Further analyses by microarray and Western blotting suggested that β-catenin signaling pathway was activated by either core or myc-F protein in the transgenic mice. These transgenic mice were further treated with either Diethynitrosamine (a tumor initiator) or Phenobarbital (a tumor promoter). Phenobarbital but not Diethynitrosamine treatment could increase the liver/body weight ratio of these mice. However, no tumor formation was observed in these mice. In conclusion, HCV core and myc-F proteins could induce hepatocyte proliferation in the transgenic mice possibly through β-catenin signaling pathway

Localization of ENHANCER OF TRY AND CPC1 protein in Arabidopsis root epidermis.

Science.gov (United States)

Tominaga-Wada, Rumi; Kurata, Tetsuya; Wada, Takuji

2017-07-01

CAPRICE (CPC) is a R3-type MYB transcription factor, which induces root-hair cell differentiation in Arabidopsis thaliana. The CPC homologous gene ENHANCER TRY AND CPC1 (ETC1) has a similar function to CPC, and acts in concert with CPC. The CPC protein moves between root epidermal cells, from hairless cells to the neighboring cells, and promotes root-hair differentiation. Therefore, ETC1 is predicted to have movement ability similar to that of CPC. In this study, we generated ETC1:ETC1:GFP and CPC:ETC1:GFP transgenic plants to clarify whether ETC1 exhibits cell-to-cell movement. Transgenic plants showed many-root-haired and trichome-less phenotypes, similar to those observed in CPC:CPC:GFP plants, suggesting a similar function of ETC1 and CPC. However, the ETC1:GFP fusion protein located exclusively to the hairless cells in both ETC1:ETC1:GFP and CPC:ETC1:GFP transgenic plants. These results indicate that, unexpectedly, the ETC1 protein cannot move in the root epidermis from hairless cells to the neighboring cells. Copyright © 2017 Elsevier GmbH. All rights reserved.

On the origin of pre-reversal enhancement of the zonal equatorial electric field

Directory of Open Access Journals (Sweden)

M. C. Kelley

2009-05-01

Full Text Available In November 2004, a large and variable interplanetary electric field (IEF was felt in the reference frame of the Earth. This electric field penetrated to the magnetic equator and, when the Jicamarca Radio Observatory (JRO was in the dusk sector, resulted in a reversal of the normal zonal component of the field. In turn, this caused a counter-electrojet (CEJ, a westward current rather than the usual eastward current. At the time of the normal pre-reversal enhancement (PRE of the eastward field, the Jicamarca incoherent scatter radar (ISR observed that the westward component became even more westward. Two of the three current explanations for the PRE depend on the neutral wind patterns. However, this unique event was such that the neutral wind-driven dynamos could not have changed. The implication is that the Haerendel-Eccles mechanism, which involves partial closure of the equatorial electrojet (EEJ after sunset, must be the dominant mechanism for the PRE.

Maltose binding protein-fusion enhances the bioactivity of truncated forms of pig myostatin propeptide produced in E. coli.

Directory of Open Access Journals (Sweden)

Sang Beum Lee

Full Text Available Myostatin (MSTN is a potent negative regulator of skeletal muscle growth. MSTN propeptide (MSTNpro inhibits MSTN binding to its receptor through complex formation with MSTN, implying that MSTNpro can be a useful agent to improve skeletal muscle growth in meat-producing animals. Four different truncated forms of pig MSTNpro containing N-terminal maltose binding protein (MBP as a fusion partner were expressed in E. coli, and purified by the combination of affinity chromatography and gel filtration. The MSTN-inhibitory capacities of these proteins were examined in an in vitro gene reporter assay. A MBP-fused, truncated MSTNpro containing residues 42-175 (MBP-Pro42-175 exhibited the same MSTN-inhibitory potency as the full sequence MSTNpro. Truncated MSTNpro proteins containing either residues 42-115 (MBP-Pro42-115 or 42-98 (MBP-Pro42-98 also exhibited MSTN-inhibitory capacity even though the potencies were significantly lower than that of full sequence MSTNpro. In pull-down assays, MBP-Pro42-175, MBP-Pro42-115, and MBP-Pro42-98 demonstrated their binding to MSTN. MBP was removed from the truncated MSTNpro proteins by incubation with factor Xa to examine the potential role of MBP on MSTN-inhibitory capacity of those proteins. Removal of MBP from MBP-Pro42-175 and MBP-Pro42-98 resulted in 20-fold decrease in MSTN-inhibitory capacity of Pro42-175 and abolition of MSTN-inhibitory capacity of Pro42-98, indicating that MBP as fusion partner enhanced the MSTN-inhibitory capacity of those truncated MSTNpro proteins. In summary, this study shows that MBP is a very useful fusion partner in enhancing MSTN-inhibitory potency of truncated forms of MSTNpro proteins, and MBP-fused pig MSTNpro consisting of amino acid residues 42-175 is sufficient to maintain the full MSTN-inhibitory capacity.

Field analysis and enhancement of multi-pole magnetic components fabricated on printed circuit board

International Nuclear Information System (INIS)

Chiu, K.-C.; Chen, C.-S.

2007-01-01

A multi-pole magnetic component magnetized with a fine magnetic pole pitch of less than 1 mm is very difficult to achieve by using traditional methods. Moreover, it requires a precise mechanical process and a complicated magnetization system. Different fine magnetic pole pitches of 300, 350 and 400 μm have been accomplished on 9-pole magnetic components through the printed circuit board (PCB) manufacturing technology. Additionally, another fine magnetic pole pitch of 500 μm was also fabricated on a dual-layered (DL) wire circuit structure to investigate the field enhancement. After measurements, a gain factor of 1.37 was obtained in the field strength. The field variations among different magnetic pole pitches were analyzed in this paper

Comparison of field-enhanced and pressure-assisted field-enhanced sample injection techniques for the analysis of water-soluble vitamins using CZE.

Science.gov (United States)

Liu, Qingqing; Liu, Yaling; Guan, Yu; Jia, Li

2009-04-01

A new online concentration method, namely pressure-assisted field-enhanced sample injection (PA-FESI), was developed and compared with FESI for the analysis of water-soluble vitamins by CZE with UV detection. In PA-FESI, negative voltage and positive pressure were simultaneously applied to initialize PA-FESI. PA-FESI uses the hydrodynamic flow generated by the positive pressure to counterbalance the reverse EOF in the capillary column during electrokinetic sample injection, which allowed a longer injection time than usual FESI mode without compromising the separation efficiency. Using the PA-FESI method, the LODs of the vitamins were at ng/mL level based on the S/N of 3 and the RSDs of migration time and peak area for each vitamin (1 microg/mL) were less than 5.1%. The developed method was applied to the analysis of water-soluble vitamins in corns.

Enhancement of crystal homogeneity of protein crystals under application of an external alternating current electric field

Energy Technology Data Exchange (ETDEWEB)

Koizumi, H.; Uda, S.; Fujiwara, K.; Nozawa, J. [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577 (Japan); Tachibana, M. [Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama, 236-0027 (Japan); Kojima, K. [Department of Education, Yokohama Soei University, 1 Miho-tyou, Midori-ku, Yokohama, 226-0015 (Japan)

2014-10-06

X-ray diffraction rocking-curve measurements were performed on tetragonal hen egg white (HEW) lysozyme crystals grown with and without the application of an external alternating current (AC) electric field. The crystal quality was assessed by the full width at half maximum (FWHM) value for each rocking curve. For two-dimensional maps of the FWHMs measured on the 440 and the 12 12 0 reflection, the crystal homogeneity was improved under application of an external electric field at 1 MHz, compared with that without. In particular, the significant improvement of the crystal homogeneity was observed for the 12 12 0 reflection.

Jc enhancement by La-Al-O doping in Y-Ba-Cu-O films both in self-field and under magnetic field

DEFF Research Database (Denmark)

Xu, Yan; Suo, Hong-Li; Yue, Zhao

2016-01-01

a good epitaxial growth relationship with LAO. Compared with a pure YBCO film, the Jc value of a 5.0% LAO-doped sample is enhanced more than three times in self-field 77 K and seven times at 77 K and 1.5 T, respectively. These results indicate that LAO doping can effectively enhance the Jc of YBCO films...... toward YBCO. A series of YBCO films with different LAO doping contents was fabricated on LAO single-crystal substrates by metal organic deposition. We observed by X-ray diffractometer measurements and scanning electron microscopy observations that although a large amount of LAO is added, YBCO still keeps...

Surface-enhanced Raman spectroscopy of saliva proteins for the noninvasive differentiation of benign and malignant breast tumors

Science.gov (United States)

Feng, Shangyuan; Huang, Shaohua; Lin, Duo; Chen, Guannan; Xu, Yuanji; Li, Yongzeng; Huang, Zufang; Pan, Jianji; Chen, Rong; Zeng, Haishan

2015-01-01

The capability of saliva protein analysis, based on membrane protein purification and surface-enhanced Raman spectroscopy (SERS), for detecting benign and malignant breast tumors is presented in this paper. A total of 97 SERS spectra from purified saliva proteins were acquired from samples obtained from three groups: 33 healthy subjects; 33 patients with benign breast tumors; and 31 patients with malignant breast tumors. Subtle but discernible changes in the mean SERS spectra of the three groups were observed. Tentative assignments of the saliva protein SERS spectra demonstrated that benign and malignant breast tumors led to several specific biomolecular changes of the saliva proteins. Multiclass partial least squares–discriminant analysis was utilized to analyze and classify the saliva protein SERS spectra from healthy subjects, benign breast tumor patients, and malignant breast tumor patients, yielding diagnostic sensitivities of 75.75%, 72.73%, and 74.19%, as well as specificities of 93.75%, 81.25%, and 86.36%, respectively. The results from this exploratory work demonstrate that saliva protein SERS analysis combined with partial least squares–discriminant analysis diagnostic algorithms has great potential for the noninvasive and label-free detection of breast cancer. PMID:25609959

Magnetic nanoparticles stimulation to enhance liquid-liquid two-phase mass transfer under static and rotating magnetic fields

Energy Technology Data Exchange (ETDEWEB)

Azimi, Neda; Rahimi, Masoud, E-mail: masoudrahimi@yahoo.com

2017-01-15

Rotating magnetic field (RMF) was applied on a micromixer to break the laminar flow and induce chaotic flow to enhance mass transfer between two-immiscible organic and aqueous phases. The results of RMF were compared to those of static magnetic field (SMF). For this purpose, experiments were carried out in a T-micromixer at equal volumetric flow rates of organic and aqueous phases. Fe{sub 3}O{sub 4} nanoparticles were synthesized by co-precipitation technique and they were dissolved in organic phase. Results obtained from RMF and SMF were compared in terms of overall volumetric mass transfer coefficient (K{sub L}a) and extraction efficiency (E) at various Reynolds numbers. Generally, RMF showed higher effect in mass transfer characteristics enhancement compared with SMF. The influence of rotational speeds of magnets (ω) in RMF was investigated, and measurable enhancements of K{sub L}a and E were observed. In RMF, the effect of magnetic field induction (B) was investigated. The results reveal that at constant concentration of nanoparticles, by increasing of B, mass transfer characteristics will be enhanced. The effect of various nanoparticles concentrations (ϕ) within 0.002–0.01 (w/v) on K{sub L}a and E at maximum induction of RMF (B=76 mT) was evaluated. Maximum values of K{sub L}a (2.1±0.001) and E (0.884±0.001) were achieved for the layout of RMF (B=76 mT), ω=16 rad/s and MNPs concentration of 0.008–0.01 (w/v). - Highlights: • Magnetic nanoparticles used for mixing of two immiscible liquids in a micromixer. • Extraction efficiency of rotating magnetic field (RMF) is compared with static one. • In RMF, the effect of the angular speed on KLa and E enhancement is reported. • In RMF, at a selected magnet distance effect of nanoparticle concentration is reported.

Enhancing the productivity of soluble green fluorescent protein ...

African Journals Online (AJOL)

Protein sequences might have been evolved against different environmental pressures, which results in non-optimum properties in their stability, activity and folding efficiency. Directed evolution and consensus-based engineering of proteins are the protein engineering principles for the re-evolution of such natural proteins ...

HTLV-1 Tax protein recruitment into IKKε and TBK1 kinase complexes enhances IFN-I expression.

Science.gov (United States)

Diani, Erica; Avesani, Francesca; Bergamo, Elisa; Cremonese, Giorgia; Bertazzoni, Umberto; Romanelli, Maria Grazia

2015-02-01

The Tax protein expressed by human T-cell leukemia virus type 1 (HTLV-1) plays a pivotal role in the deregulation of cellular pathways involved in the immune response, inflammation, cell survival, and cancer. Many of these effects derive from Tax multiple interactions with host factors, including the subunits of the IKK-complex that are required for NF-κB activation. IKKɛ and TBK1 are two IKK-related kinases that allow the phosphorylation of interferon regulatory factors that trigger IFN type I gene expression. We observed that IKKɛ and TBK1 recruit Tax into cellular immunocomplexes. We also found that TRAF3, which regulates cell receptor signaling effectors, forms complexes with Tax. Transactivation analyses revealed that expression of Tax, in presence of IKKɛ and TBK1, enhances IFN-β promoter activity, whereas the activation of NF-κB promoter is not modified. We propose that Tax may be recruited into the TBK1/IKKɛ complexes as a scaffolding-adaptor protein that enhances IFN-I gene expression. Copyright © 2014 Elsevier Inc. All rights reserved.

Beam Dynamics Simulations of Optically-Enhanced Field Emission from Structured Cathodes

Energy Technology Data Exchange (ETDEWEB)

Seymour, A. [Northern Illinois U.; Grote, D. [LLNL, Livermore; Mihalcea, D. [Northern Illinois U.; Piot, P. [Fermilab; Vay, J.-L. [LBNL, Berkeley

2014-01-01

Structured cathodes - cathodes with a segmented emission surface - are finding an increasing number of applications and can be combined with a variety of emission mechanisms, including photoemission and field emission. These cathodes have been used to enhance the quantum efficiency of metallic cathodes when operated as plasmonic cathodes, have produced high-current electron bunches though field emission from multiple tips, and can be used to form beams with transverse segmentations necessary for improving the performance of accelerator-based light sources. In this report we present recent progress towards the development of finite-difference time-domain particle-in-cell simulations using the emission process in structured cathodes based on the WARP framework. The simulations give further insight on the localized source of the emitted electrons which could be used for additional high-fidelity start-to-end simulations of electron accelerators that employ this type of electron source.

Enhanced Field Emission Studies on Niobium Surfaces Relevant to High Field Superconducting Radio-Frequency Devices

Energy Technology Data Exchange (ETDEWEB)

Wang, Tong [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)

2002-09-18

Enhanced field emission (EFE) presents the main impediment to higher acceleration gradients in superconducting niobium (Nb) radiofrequency cavities for particle accelerators. The strength, number and sources of EFE sites strongly depend on surface preparation and handling. The main objective of this thesis project is to systematically investigate the sources of EFE from Nb, to evaluate the best available surface preparation techniques with respect to resulting field emission, and to establish an optimized process to minimize or eliminate EFE. To achieve these goals, a scanning field emission microscope (SFEM) was designed and built as an extension to an existing commercial scanning electron microscope (SEM). In the SFEM chamber of ultra high vacuum, a sample is moved laterally in a raster pattern under a high voltage anode tip for EFE detection and localization. The sample is then transferred under vacuum to the SEM chamber equipped with an energy-dispersive x-ray spectrometer for individual emitting site characterization. Compared to other systems built for similar purposes, this apparatus has low cost and maintenance, high operational flexibility, considerably bigger scan area, as well as reliable performance. EFE sources from planar Nb have been studied after various surface preparation, including chemical etching and electropolishing, combined with ultrasonic or high-pressure water rinse. Emitters have been identified, analyzed and the preparation process has been examined and improved based on EFE results. As a result, field-emission-free or near field-emission-free surfaces at ~140 MV/m have been consistently achieved with the above techniques. Characterization on the remaining emitters leads to the conclusion that no evidence of intrinsic emitters, i.e., no fundamental electric field limit induced by EFE, has been observed up to ~140 MV/m. Chemically etched and electropolished Nb are compared and no significant difference is observed up to ~140 MV/m. To

Enhanced Field Emission Studies on Niobium Surfaces Relevant to High Field Superconducting Radio-Frequency Devices

International Nuclear Information System (INIS)

Tong Wang

2002-01-01

Enhanced field emission (EFE) presents the main impediment to higher acceleration gradients in superconducting niobium (Nb) radio frequency cavities for particle accelerators. The strength, number and sources of EFE sites strongly depend on surface preparation and handling. The main objective of this thesis project is to systematically investigate the sources of EFE from Nb, to evaluate the best available surface preparation techniques with respect to resulting field emission, and to establish an optimized process to minimize or eliminate EFE. To achieve these goals, a scanning field emission microscope (SFEM) was designed and built as an extension to an existing commercial scanning electron microscope (SEM). In the SFEM chamber of ultra high vacuum, a sample is moved laterally in a raster pattern under a high voltage anode tip for EFE detection and localization. The sample is then transferred under vacuum to the SEM chamber equipped with an energy-dispersive x-ray spectrometer for individual emitting site characterization. Compared to other systems built for similar purposes, this apparatus has low cost and maintenance, high operational flexibility, considerably bigger scan area, as well as reliable performance. EFE sources from planar Nb have been studied after various surface preparation, including chemical etching and electropolishing, combined with ultrasonic or high-pressure water rinse. Emitters have been identified, analyzed and the preparation process has been examined and improved based on EFE results. As a result, field-emission-free or near field-emission-free surfaces at ∼140 MV/m have been consistently achieved with the above techniques. Characterization on the remaining emitters leads to the conclusion that no evidence of intrinsic emitters, i.e., no fundamental electric field limit induced by EFE, has been observed up to ∼140 MV/m. Chemically etched and electropolished Nb are compared and no significant difference is observed up to ∼140 MV

Enhancement of the guide field during the current sheet formation in the three-dimensional magnetic configuration with an X line

International Nuclear Information System (INIS)

Frank, Anna; Bugrov, Sergey; Markov, Vladimir

2009-01-01

Results are presented from studies of the formation of current sheets during exciting a current aligned with the X line of the 3D magnetic configuration, in the CS-3D device. Enhancement of the guide field (parallel to the X line) was directly observed for the first time, on the basis of magnetic measurements. After the current sheet formation, the guide field inside the sheet exceeds its initial value, as well as the field outside. It is convincingly demonstrated that an enhancement of the guide field is due to its transportation by plasma flows on the early stage of the sheet formation. The in-plane plasma currents, which produce the excess guide field, are comparable to the total current along the X line that initiates the sheet itself.

Conductivity enhancement induced by casting of polymer electrolytes under a magnetic field

International Nuclear Information System (INIS)

Kovarsky, R.; Golodnitsky, D.; Peled, E.; Khatun, S.; Stallworth, P.E.; Greenbaum, S.; Greenbaum, A.

2011-01-01

Highlights: ► Ordering of polymer electrolytes under applied magnetic field. ► Positive effect of nanosize ferromagnetic filler. ► Structure-ion conductivity interrelationship. - Abstract: We recently presented a procedure for orienting the polyethylene-oxide (PEO) helices in a direction perpendicular to the film plane by casting the polymer electrolytes (PE) under a magnetic field (MF). Here we study the influence of magnetic fields of different strengths and configurations on the structural properties and ionic conductivity of concentrated LiCF 3 SO 3 (LiTf) and LiAsF 6 :P(EO) pristine and composite polymer electrolytes containing γ-Fe 2 O 3 nanoparticles. Some data of LiI:P(EO) system are shown for comparison. We suggest that the effect of type of salt (LiI, LiTf and LiAsF 6 ) on the structure–conductivity relationship of the polymer electrolytes cast under magnetic field is closely connected to the crystallinity of the PEO–LiX system. It was found that the higher the content of the crystalline phase and the size of spherulites in the typically cast salt-polymer system, the stronger the influence of the magnetic field on the conductivity enhancement when the electrolyte is cast and dried under MF. Casting of the PE from a high-dielectric-constant solvent results in disentanglement of the PEO chains, which facilitates even more the perpendicular orientation of helices under applied MF. The enhancement of ionic conductivity was appreciably higher in the PEs cast under strong NdFeB magnets than under SmCo. Both bulk (intrachain) and grain-boundary conductivities increase when a MF is applied, but the improvement in the grain-boundary conductivity – associated with ion-hopping between polymer chains – is more pronounced. For LiAsF 6 :(PEO) 3 at 65 °C, the interchain conductivity increased by a factor of 75, while the intrachain conductivity increased by a factor of 11–14. At room temperature, the SEI resistance of these PEs, cast under NdFeB HMF

Incorporating deep learning with convolutional neural networks and position specific scoring matrices for identifying electron transport proteins.

Science.gov (United States)

Le, Nguyen-Quoc-Khanh; Ho, Quang-Thai; Ou, Yu-Yen

2017-09-05

In several years, deep learning is a modern machine learning technique using in a variety of fields with state-of-the-art performance. Therefore, utilization of deep learning to enhance performance is also an important solution for current bioinformatics field. In this study, we try to use deep learning via convolutional neural networks and position specific scoring matrices to identify electron transport proteins, which is an important molecular function in transmembrane proteins. Our deep learning method can approach a precise model for identifying of electron transport proteins with achieved sensitivity of 80.3%, specificity of 94.4%, and accuracy of 92.3%, with MCC of 0.71 for independent dataset. The proposed technique can serve as a powerful tool for identifying electron transport proteins and can help biologists understand the function of the electron transport proteins. Moreover, this study provides a basis for further research that can enrich a field of applying deep learning in bioinformatics. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Characterizing AISI 1045 steel surface duplex-treated by alternating current field enhanced pack aluminizing and nitriding

Science.gov (United States)

Xie, Fei; Zhang, Ge; Pan, Jianwei

2018-02-01

Thin cases and long treating time are shortcomings of conventional duplex treatment of aluminizing followed by nitriding (DTAN). Alternating current field (ACF) enhanced DTAN was carried out on AISI 1045 steel by applying an ACF to treated samples and treating agents with a pair of electrodes for overcoming those shortcomings. By investigating cases' structures, phases, composition and hardness distributions of differently treated samples, preliminary studies were made on characterizations of the ACF enhanced duplex treatment to AISI 1045 steel. The results show that, with the help of the ACF, the surface Al-rich phase Al5Fe2 formed in conventional pack aluminizing can be easily avoided and the aluminizing process is dramatically promoted. The aluminizing case can be nitrided either with conventional pack nitriding or ACF enhanced pack nitriding. By applying ACF to pack nitriding, the diffusion of nitrogen into the aluminizing case is promoted. AlN, Fe2∼3N and solid solution of N in iron are efficiently formed as a result of reactions of N with the aluminizing case. A duplex treated case with an effective thickness of more than 170 μm can be obtained by the alternating current field enhanced 4 h pack aluminizing plus 4 h pack nitriding.

DeepCNF-D: Predicting Protein Order/Disorder Regions by Weighted Deep Convolutional Neural Fields

Directory of Open Access Journals (Sweden)

Sheng Wang

2015-07-01

Full Text Available Intrinsically disordered proteins or protein regions are involved in key biological processes including regulation of transcription, signal transduction, and alternative splicing. Accurately predicting order/disorder regions ab initio from the protein sequence is a prerequisite step for further analysis of functions and mechanisms for these disordered regions. This work presents a learning method, weighted DeepCNF (Deep Convolutional Neural Fields, to improve the accuracy of order/disorder prediction by exploiting the long-range sequential information and the interdependency between adjacent order/disorder labels and by assigning different weights for each label during training and prediction to solve the label imbalance issue. Evaluated by the CASP9 and CASP10 targets, our method obtains 0.855 and 0.898 AUC values, which are higher than the state-of-the-art single ab initio predictors.

Determination of microturbulence enhanced electron collisionality in magnetized coaxial accelerator channels by direct magnetic field measurement

International Nuclear Information System (INIS)

Black, D.C.; Mayo, R.M.; Caress, R.W.

1997-01-01

A miniature magnetic probe array, consisting of 10 spatially separated coils, has been used to obtain profile information on the time varying magnetic field within the 2.54 cm wide flow channel of the coaxial plasma source experiment (CPS-1) [R. M. Mayo et al., Plasma Sources Sci. Technol. 4, 47 (1995)]. The magnetic field data have been used, together with a resistive, Hall magnetohydrodynamic (MHD) model of applied field distortion by the flowing plasma, to obtain estimates of the microturbulent enhancement to electron collisionality within the CPS-1 flow channel. These measurements provide direct experimental evidence of anomalous electron collisionality, a previously predicted effect in these devices. The anomaly parameter, a=ν an /ν cl , determined both from the distortion of contours of constant magnetic flux, and from local B θ and B z measurements scales with the classical electron magnetization parameter (Ω cl =ω ce /ν e cl ), indicating that collisionality plays a strong role in determining the level of anomalous transport in the plasma. When this anomaly parameter scaling is cast in terms of the ratio ν e cl /ω lh , it is found that the resistivity enhancement scales with ν e cl /ω lh , and becomes significant at ν e cl /ω lh ≤1, suggesting that a lower hybrid drift instability may be the responsible mechanism for enhanced transport. copyright 1997 American Institute of Physics

High-field EPR on membrane proteins - crossing the gap to NMR.

Science.gov (United States)

Möbius, Klaus; Lubitz, Wolfgang; Savitsky, Anton

2013-11-01

In this review on advanced EPR spectroscopy, which addresses both the EPR and NMR communities, considerable emphasis is put on delineating the complementarity of NMR and EPR concerning the measurement of molecular interactions in large biomolecules. From these interactions, detailed information can be revealed on structure and dynamics of macromolecules embedded in solution- or solid-state environments. New developments in pulsed microwave and sweepable cryomagnet technology as well as ultrafast electronics for signal data handling and processing have pushed to new horizons the limits of EPR spectroscopy and its multifrequency extensions concerning the sensitivity of detection, the selectivity with respect to interactions, and the resolution in frequency and time domains. One of the most important advances has been the extension of EPR to high magnetic fields and microwave frequencies, very much in analogy to what happens in NMR. This is exemplified by referring to ongoing efforts for signal enhancement in both NMR and EPR double-resonance techniques by exploiting dynamic nuclear or electron spin polarization via unpaired electron spins and their electron-nuclear or electron-electron interactions. Signal and resolution enhancements are particularly spectacular for double-resonance techniques such as ENDOR and PELDOR at high magnetic fields. They provide greatly improved orientational selection for disordered samples that approaches single-crystal resolution at canonical g-tensor orientations - even for molecules with small g-anisotropies. Exchange of experience between the EPR and NMR communities allows for handling polarization and resolution improvement strategies in an optimal manner. Consequently, a dramatic improvement of EPR detection sensitivity could be achieved, even for short-lived paramagnetic reaction intermediates. Unique structural and dynamic information is thus revealed that can hardly be obtained by any other analytical techniques. Micromolar

Enhanced performance of thermal-assisted electron field emission based on barium oxide nanowire

Energy Technology Data Exchange (ETDEWEB)

Cui, Yunkang [Department of Mathematics and Physics, Nanjing Institute of technology, Nanjing, 211167 (China); Chen, Jing, E-mail: chenjingmoon@gmail.com [School of Electronic Science & Engineering, Southeast University, Nanjing, 210096 (China); Zhang, Yuning; Zhang, Xiaobing; Lei, Wei; Di, Yunsong [School of Electronic Science & Engineering, Southeast University, Nanjing, 210096 (China); Zhang, Zichen, E-mail: zz241@ime.ac.cn [Integrated system for Laser applications Group, Institute of Microelectronics of Chinese Academy of Sciences, 100029, Beijing (China)

2017-02-28

Highlights: • A possible mechanism for thermal-assisted electric field was demonstrated. • A new path for the architecture of the novel nanomaterial and methodology for its potential application in the field emission device area was provided. • The turn-on field, the threshold field and the field emission current density were largely related to the temperature of the cathode. • The relationship between the work function of emitter material and the temperature of emitter was found. - Abstract: In this paper, thermal-assisted field emission properties of barium oxide (BaO) nanowire synthesized by a chemical bath deposition method were investigated. The morphology and composition of BaO nanowire were characterized by field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SED), X-ray diffraction (XRD), and energy dispersive X-ray spectrometer (EDX) respectively. The turn-on field, threshold field and the emission current density could be affected relatively due to the thermal-assisted effect when the electric field was applied, in the meanwhile, the turn-on field for BaO nanowire was measured to be decreased from 1.12 V/μm to 0.66 V/μm when the temperature was raised from 293 K to 593 K, whereas for the threshold field was found to decrease from 3.64 V/μm to 2.12 V/μm. The improved performance was demonstrated due to the reduced work function of the BaO nanowire as the agitation temperature increasing, leading to the higher probability of electrons tunneling through the energy barrier and enhancement of the field emission properties of BaO emitters.

Enhanced performance of thermal-assisted electron field emission based on barium oxide nanowire

International Nuclear Information System (INIS)

Cui, Yunkang; Chen, Jing; Zhang, Yuning; Zhang, Xiaobing; Lei, Wei; Di, Yunsong; Zhang, Zichen

2017-01-01

Highlights: • A possible mechanism for thermal-assisted electric field was demonstrated. • A new path for the architecture of the novel nanomaterial and methodology for its potential application in the field emission device area was provided. • The turn-on field, the threshold field and the field emission current density were largely related to the temperature of the cathode. • The relationship between the work function of emitter material and the temperature of emitter was found. - Abstract: In this paper, thermal-assisted field emission properties of barium oxide (BaO) nanowire synthesized by a chemical bath deposition method were investigated. The morphology and composition of BaO nanowire were characterized by field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SED), X-ray diffraction (XRD), and energy dispersive X-ray spectrometer (EDX) respectively. The turn-on field, threshold field and the emission current density could be affected relatively due to the thermal-assisted effect when the electric field was applied, in the meanwhile, the turn-on field for BaO nanowire was measured to be decreased from 1.12 V/μm to 0.66 V/μm when the temperature was raised from 293 K to 593 K, whereas for the threshold field was found to decrease from 3.64 V/μm to 2.12 V/μm. The improved performance was demonstrated due to the reduced work function of the BaO nanowire as the agitation temperature increasing, leading to the higher probability of electrons tunneling through the energy barrier and enhancement of the field emission properties of BaO emitters.

Application of pulsed-magnetic field enhances non-viral gene delivery in primary cells from different origins

Energy Technology Data Exchange (ETDEWEB)

Kamau Chapman, Sarah W. [Institute of Veterinary Biochemistry and Molecular Biology, University of Zurich, Winterthurerstr. 190, 8057 Zurich (Switzerland); Hassa, Paul O. [Institute of Veterinary Biochemistry and Molecular Biology, University of Zurich, Winterthurerstr. 190, 8057 Zurich (Switzerland); European Molecular Biology Laboratory (EMBL) Heidelberg, Meyerhofstrasse 1, 69117 Heidelberg (Germany); Koch-Schneidemann, Sabine; Rechenberg, Brigitte von [Musculoskeletal Research Unit, Equine Hospital, Vetsuisse Faculty Zurich, University of Zurich, Winterthurerstr. 260, 8057 Zurich (Switzerland); Hofmann-Amtenbrink, Margarethe [MatSearch, Chemin Jean Pavillard 14, 1009 Pully (Switzerland); Steitz, Benedikt; Petri-Fink, Alke; Hofmann, Heinrich [Laboratory of Powder Technology, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne (Switzerland); Hottiger, Michael O. [Institute of Veterinary Biochemistry and Molecular Biology, University of Zurich, Winterthurerstr. 190, 8057 Zurich (Switzerland)], E-mail: hottiger@vetbio.uzh.ch

2008-04-15

Primary cell lines are more difficult to transfect when compared to immortalized/transformed cell lines, and hence new techniques are required to enhance the transfection efficiency in these cells. We isolated and established primary cultures of synoviocytes, chondrocytes, osteoblasts, melanocytes, macrophages, lung fibroblasts, and embryonic fibroblasts. These cells differed in several properties, and hence were a good representative sample of cells that would be targeted for expression and delivery of therapeutic genes in vivo. The efficiency of gene delivery in all these cells was enhanced using polyethylenimine-coated polyMAG magnetic nanoparticles, and the rates (17-84.2%) surpassed those previously achieved using other methods, especially in cells that are difficult to transfect. The application of permanent and pulsating magnetic fields significantly enhanced the transfection efficiencies in synoviocytes, chondrocytes, osteoblasts, melanocytes and lung fibroblasts, within 5 min of exposure to these magnetic fields. This is an added advantage for future in vivo applications, where rapid gene delivery is required before systemic clearance or filtration of the gene vectors occurs.

Influence of extremely low frequency magnetic field on total protein and –SH groups concentrations in liver homogenates

Directory of Open Access Journals (Sweden)

Elżbieta Ciejka

2014-10-01

Full Text Available Background: Free radicals are atoms, molecules or their fragments, whose excess leads to the development of oxidative stress, the cause of many neoplastic, neurodegenerative and inflammatory diseases, as well as aging of organisms. Industrial pollution, tobacco smoke, ionizing radiation, ultrasound and magnetic fields are the major exogenous sources of free radicals. The low frequency magnetic field is commonly applied in physiotherapy. The aim of the present study was to evaluate the effect of extremely low frequency magnetic field (ELF-MF on the concentration of sulfhydryl groups (–SH and proteins in liver tissues of experimental animals depending on the time of exposure to the field. Material and Methods: Twenty one Sprague-Dawley male rats, aged 3–4 months were randomly divided into 3 experimental groups (each containing 7 animals: controls (group I, the rats exposed to ELF-MF of 40 Hz, 7 mT (this kind of the ELF-MF is mostly used in magnetotherapy, 30 min/day for 2 weeks (group II and the rats exposed to 40 Hz, 7 mT for 60 min/day for 2 weeks (group III. The concentrations of proteins and sulfhydryl groups in the liver tissues were determined after exposure to magnetic fields. Results: Exposure to low magnetic field: 40 Hz, 7 mT for 30 min/day and 60 min/day for 2 weeks caused a significant increase in the concentration of –SH groups and total protein levels in the liver tissues. Conclusions: The study results suggest that exposure to magnetic fields leads to the development of adaptive mechanisms to maintain the balance in the body oxidation-reduction and in the case of the studied parameters does not depend on the time of exposure. Med Pr 2014;65(5:639–644

Enhancement of inflammatory protein expression and nuclear factor Κb (NF-Κb) activity by trichostatin A (TSA) in OP9 preadipocytes.

Science.gov (United States)

Sato, Taiki; Kotake, Daisuke; Hiratsuka, Masahiro; Hirasawa, Noriyasu

2013-01-01

The production of inflammatory proteins such as interleukin-6 (IL-6) by preadipocytes and mature adipocytes is closely associated with the impairment of systemic glucose homeostasis. However, precisely how the production is regulated and the roles of histone deacetylases (HDACs) remain largely unknown. The aim of this study was to establish whether HDAC inhibitors affect the expression of inflammatory proteins in pre/mature adipocytes, and, if so, to determine the mechanism involved. Trichostatin A (TSA), an HDAC inhibitor, enhanced lipopolysaccharide (LPS)-induced production of IL-6 in OP9 preadipocytes but not the mature adipocytes. Moreover, TSA also enhanced palmitic acid-induced IL-6 production and the expression of inflammatory genes induced by LPS in preadipocytes. Although TSA did not affect TLR4 mRNA expression or the activation of MAPKs, a reporter gene assay revealed that the LPS-induced increase in nuclear factor κB (NF-κB) activity was enhanced by TSA. Moreover, TSA increased the level of NF-κB p65 acetylation at lysine 310 and duration of its translocation into the nucleus, which leads to enhancement of NF-κB activity and subsequently expression of inflammatory genes. These findings shed new light on the regulatory roles of HDACs in preadipocytes in the production of inflammatory proteins.

Automated sequence- and stereo-specific assignment of methyl-labeled proteins by paramagnetic relaxation and methyl–methyl nuclear overhauser enhancement spectroscopy

International Nuclear Information System (INIS)

Venditti, Vincenzo; Fawzi, Nicolas L.; Clore, G. Marius

2011-01-01

Methyl-transverse relaxation optimized spectroscopy is rapidly becoming the preferred NMR technique for probing structure and dynamics of very large proteins up to ∼1 MDa in molecular size. Data interpretation, however, necessitates assignment of methyl groups which still presents a very challenging and time-consuming process. Here we demonstrate that, in combination with a known 3D structure, paramagnetic relaxation enhancement (PRE), induced by nitroxide spin-labels incorporated at only a few surface-exposed engineered cysteines, provides fast, straightforward and robust access to methyl group resonance assignments, including stereoassignments for the methyl groups of leucine and valine. Neither prior assignments, including backbone assignments, for the protein, nor experiments that transfer magnetization between methyl groups and the protein backbone, are required. PRE-derived assignments are refined by 4D methyl–methyl nuclear Overhauser enhancement data, eliminating ambiguities and errors that may arise due to the high sensitivity of PREs to the potential presence of sparsely-populated transient states.

Automated sequence- and stereo-specific assignment of methyl-labeled proteins by paramagnetic relaxation and methyl-methyl nuclear overhauser enhancement spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Venditti, Vincenzo; Fawzi, Nicolas L.; Clore, G. Marius, E-mail: mariusc@mail.nih.gov [National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Laboratory of Chemical Physics (United States)

2011-11-15

Methyl-transverse relaxation optimized spectroscopy is rapidly becoming the preferred NMR technique for probing structure and dynamics of very large proteins up to {approx}1 MDa in molecular size. Data interpretation, however, necessitates assignment of methyl groups which still presents a very challenging and time-consuming process. Here we demonstrate that, in combination with a known 3D structure, paramagnetic relaxation enhancement (PRE), induced by nitroxide spin-labels incorporated at only a few surface-exposed engineered cysteines, provides fast, straightforward and robust access to methyl group resonance assignments, including stereoassignments for the methyl groups of leucine and valine. Neither prior assignments, including backbone assignments, for the protein, nor experiments that transfer magnetization between methyl groups and the protein backbone, are required. PRE-derived assignments are refined by 4D methyl-methyl nuclear Overhauser enhancement data, eliminating ambiguities and errors that may arise due to the high sensitivity of PREs to the potential presence of sparsely-populated transient states.

Cooperative Enhancement Mechanisms of Low Energy Nuclear Reactions Using Superlow Energy External Fields

OpenAIRE

Gareev, F. A.; Zhidkova, I. E.

2006-01-01

We proposed a new mechanism of LENR: cooperative processes in whole system - nuclei+atoms+condensed matter can occur at smaller threshold energies then corresponding ones on free constituents. The cooperative processes can be induced and enhanced by low energy external fields. The excess heat is the emission of internal energy and transmutations at LENR are the result of redistribution inner energy of whole system.

Genetic incorporation of the protein transduction domain of Tat into Ad5 fiber enhances gene transfer efficacy

Directory of Open Access Journals (Sweden)

Siegal Gene P

2007-10-01

Full Text Available Abstract Background Human adenovirus serotype 5 (Ad5 has been widely explored as a gene delivery vector for a variety of diseases. Many target cells, however, express low levels of Ad5 native receptor, the Coxsackie-Adenovirus Receptor (CAR, and thus are resistant to Ad5 infection. The Protein Transduction Domain of the HIV Tat protein, namely PTDtat, has been shown to mediate protein transduction in a wide range of cells. We hypothesize that re-targeting Ad5 vector via the PTDtat motif would improve the efficacy of Ad5-mediated gene delivery. Results In this study, we genetically incorporated the PTDtat motif into the knob domain of Ad5 fiber, and rescued the resultant viral vector, Ad5.PTDtat. Our data showed the modification did not interfere with Ad5 binding to its native receptor CAR, suggesting Ad5 infection via the CAR pathway is retained. In addition, we found that Ad5.PTDtat exhibited enhanced gene transfer efficacy in all of the cell lines that we have tested, which included both low-CAR and high-CAR decorated cells. Competitive inhibition assays suggested the enhanced infectivity of Ad5.PTDtat was mediated by binding of the positively charged PTDtat peptide to the negatively charged epitopes on the cells' surface. Furthermore, we investigated in vivo gene delivery efficacy of Ad5.PTDtat using subcutaneous tumor models established with U118MG glioma cells, and found that Ad5.PTDtat exhibited enhanced gene transfer efficacy compared to unmodified Ad5 vector as analyzed by a non-invasive fluorescence imaging technique. Conclusion Genetic incorporation of the PTDtat motif into Ad5 fiber allowed Ad5 vectors to infect cells via an alternative PTDtat targeting motif while retaining the native CAR-mediated infection pathway. The enhanced infectivity was demonstrated in both cultured cells and in in vivo tumor models. Taken together, our study identifies a novel tropism expanded Ad5 vector that may be useful for clinical gene therapy

Templating Biomineralization: Surface Directed Protein Self-assembly and External Magnetic Field Stimulation of Osteoblasts

Science.gov (United States)

Ba, Xiaolan

Biomineralization is a wide-spread phenomenon in the biological systems, which is the process of mineral formation by organisms through interaction between its organic contents and the inorganic minerals. The process is essential in a broad spectrum of biological phenomena ranging from bone and tooth formation to pathological mineralization under hypoxic conditions or cancerous formations. In this thesis I studied biomineralization at the earliest stages in order to obtain a better understanding of the fundamental principals involved. This knowledge is essential if we want to engineer devices which will increase bone regeneration or prevent unwanted mineral deposits. Extracellular matrix (ECM) proteins play an essential role during biomineralization in bone and engineered tissues. In this dissertation, I present an approach to mimic the ECM in vitro to probe the interactions of these proteins with calcium phosphate mineral and with each other. Early stage of mineralization is investigated by mechanical properties of the protein fibers using Scanning Probe Microscopy (SPM) and Shear Modulation Force Microscopy (SMFM). The development of mineral crystals on the protein matrices is also characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Grazing Incidence X-ray Diffraction (GIXRD). The results demonstrate complementary actions of the two ECM proteins to collect cations and template calcium phosphate mineral, respectively. Magnets have been clinically used as an "induction source" in various bone or orthodontic treatments. However, the mechanism and effects of magnetic fields remain unclear. In this dissertation, I also undertake the present investigation to study the effects of 150 mT static magnetic fields (SMF) on ECM development and cell biomineralization using MC3T3-E1 osteobalst-like cells. Early stage of biomineralization is characterized by SPM, SMFM and confocal laser scanning microscopy (CSLM). Late stage of

Does an Intrinsic Magnetic Field Inhibit or Enhance Planetary Ionosphere Outflow and Loss?

Science.gov (United States)

Strangeway, R. J.; Russell, C. T.; Luhmann, J. G.; Moore, T. E.; Foster, J. C.; Barabash, S. V.; Nilsson, H.

2017-12-01

A characteristic feature of the planets Earth, Venus and Mars is the observation of the outflow of ionospheric ions, most notably oxygen. The oxygen ion outflow is frequently assumed to be a proxy for the loss of water from the planetary atmosphere. In terms of global outflow rates for the Earth the rate varies from 1025 to 1026 s-1, depending on geomagnetic activity. For both Venus and Mars global rates of the order 5x1024 s-1 have been reported. Venus and Mars do not have a large-scale intrinsic magnetic field, and there are several pathways for atmospheric and ionospheric loss. At Mars, because of its low gravity, neutral oxygen can escape through dissociative recombination. At Venus only processes related to the solar wind interaction with the planet such as sputtering and direct scavenging of the ionosphere by the solar wind can result in oxygen escape. At the Earth the intrinsic magnetic field forms a barrier to the solar wind, but reconnection of the Earth's magnetic field with the Interplanetary Magnetic Field allows solar wind energy and momentum to be transferred into the magnetosphere, resulting in ionospheric outflows. Observations of oxygen ions at the dayside magnetopause suggest that at least some of these ions escape. In terms of the evolution of planetary atmospheres how the solar-wind driven escape rates vary for magnetized versus umagnetized planets is also not clear. An enhanced solar wind dynamic pressure will increase escape from the unmagnetized planets, but it may also result in enhanced reconnection at the Earth, increasing outflow and loss rates for the Earth as well. Continued improvement in our understanding of the different pathways for ionospheric and atmospheric loss will allow us to determine how effective an intrinsic planetary field is in preserving a planetary atmosphere, or if we have to look for other explanations as to why the atmospheres of Venus and Mars have evolved to their desiccated state.

Enzastaurin (LY317615), a Protein Kinase C Beta Selective Inhibitor, Enhances Antiangiogenic Effect of Radiation

International Nuclear Information System (INIS)

Willey, Christopher D.; Xiao Dakai; Tu Tianxiang; Kim, Kwang Woon; Moretti, Luigi; Niermann, Kenneth J.; Tawtawy, Mohammed N.; Quarles, Chad C. Ph.D.; Lu Bo

2010-01-01

Purpose: Angiogenesis has generated interest in oncology because of its important role in cancer growth and progression, particularly when combined with cytotoxic therapies, such as radiotherapy. Among the numerous pathways influencing vascular growth and stability, inhibition of protein kinase B(Akt) or protein kinase C(PKC) can influence tumor blood vessels within tumor microvasculature. Therefore, we wanted to determine whether PKC inhibition could sensitize lung tumors to radiation. Methods and Materials: The combination of the selective PKCβ inhibitor Enzastaurin (ENZ, LY317615) and ionizing radiation were used in cell culture and a mouse model of lung cancer. Lung cancer cell lines and human umbilical vascular endothelial cells (HUVEC) were examined using immunoblotting, cytotoxic assays including cell proliferation and clonogenic assays, and Matrigel endothelial tubule formation. In vivo, H460 lung cancer xenografts were examined for tumor vasculature and proliferation using immunohistochemistry. Results: ENZ effectively radiosensitizes HUVEC within in vitro models. Furthermore, concurrent ENZ treatment of lung cancer xenografts enhanced radiation-induced destruction of tumor vasculature and proliferation by IHC. However, tumor growth delay was not enhanced with combination treatment compared with either treatment alone. Analysis of downstream effectors revealed that HUVEC and the lung cancer cell lines differed in their response to ENZ and radiation such that only HUVEC demonstrate phosphorylated S6 suppression, which is downstream of mTOR. When ENZ was combined with the mTOR inhibitor, rapamycin, in H460 lung cancer cells, radiosensitization was observed. Conclusion: PKC appears to be crucial for angiogenesis, and its inhibition by ENZ has potential to enhance radiotherapy in vivo.

MEAL-BASED ENHANCEMENT OF PROTEIN QUALITY AND QUANTITY DURING WEIGHT LOSS IN OBESE OLDER ADULTS WITH MOBILITY LIMITATIONS: RATIONALE AND DESIGN FOR THE MEASUR-UP TRIAL

Science.gov (United States)

McDonald, Shelley R.; Starr, Kathryn N. Porter; Mauceri, Luisa; Orenduff, Melissa; Granville, Esther; Ocampo, Christine; Payne, Martha E.; Pieper, Carl F.; Bales, Connie W.

2015-01-01

Obese older adults with even modest functional limitations are at a disadvantage for maintaining their independence into late life. However, there is no established intervention for obesity in older individuals. The Measuring Eating, Activity and Strength: Understanding the Response --Using Protein (MEASUR-UP) trial is a randomized controlled pilot study of obese women and men aged ≥60 years with mild to moderate functional impairments. Changes in body composition (lean and fat mass) and function (Short Physical Performance Battery) in an enhanced protein weight reduction (Protein) arm will be compared to those in a traditional weight loss (Control) arm. The Protein intervention is based on evidence that older adults achieve optimal rates of muscle protein synthesis when consuming about 25-30 grams of high quality protein per meal; these participants will consume −30 g of animal protein at each meal via a combination of provided protein (beef) servings and diet counseling. This trial will provide information on the feasibility and efficacy of enhancing protein quantity and quality in the context of a weight reduction regimen and determine the impact of this intervention on body weight, functional status, and lean muscle mass. We hypothesize that the enhancement of protein quantity and quality in the Protein arm will result in better outcomes for function and/or lean muscle mass than in the Control arm. Ultimately, we hope our findings will help identify a safe weight loss approach that can delay or prevent late life disability by changing the trajectory of age-associated functional impairment associated with obesity. PMID:25461495

Dynamic regulation of GDP binding to G proteins revealed by magnetic field-dependent NMR relaxation analyses.

Science.gov (United States)

Toyama, Yuki; Kano, Hanaho; Mase, Yoko; Yokogawa, Mariko; Osawa, Masanori; Shimada, Ichio

2017-02-22

Heterotrimeric guanine-nucleotide-binding proteins (G proteins) serve as molecular switches in signalling pathways, by coupling the activation of cell surface receptors to intracellular responses. Mutations in the G protein α-subunit (Gα) that accelerate guanosine diphosphate (GDP) dissociation cause hyperactivation of the downstream effector proteins, leading to oncogenesis. However, the structural mechanism of the accelerated GDP dissociation has remained unclear. Here, we use magnetic field-dependent nuclear magnetic resonance relaxation analyses to investigate the structural and dynamic properties of GDP bound Gα on a microsecond timescale. We show that Gα rapidly exchanges between a ground-state conformation, which tightly binds to GDP and an excited conformation with reduced GDP affinity. The oncogenic D150N mutation accelerates GDP dissociation by shifting the equilibrium towards the excited conformation.

Parallel force assay for protein-protein interactions.

Science.gov (United States)

Aschenbrenner, Daniela; Pippig, Diana A; Klamecka, Kamila; Limmer, Katja; Leonhardt, Heinrich; Gaub, Hermann E

2014-01-01

Quantitative proteome research is greatly promoted by high-resolution parallel format assays. A characterization of protein complexes based on binding forces offers an unparalleled dynamic range and allows for the effective discrimination of non-specific interactions. Here we present a DNA-based Molecular Force Assay to quantify protein-protein interactions, namely the bond between different variants of GFP and GFP-binding nanobodies. We present different strategies to adjust the maximum sensitivity window of the assay by influencing the binding strength of the DNA reference duplexes. The binding of the nanobody Enhancer to the different GFP constructs is compared at high sensitivity of the assay. Whereas the binding strength to wild type and enhanced GFP are equal within experimental error, stronger binding to superfolder GFP is observed. This difference in binding strength is attributed to alterations in the amino acids that form contacts according to the crystal structure of the initial wild type GFP-Enhancer complex. Moreover, we outline the potential for large-scale parallelization of the assay.

An experimental method to determine the electrostatic field enhancement factor of a practical conductor surface

DEFF Research Database (Denmark)

McAllister, Iain Wilson; Crichton, George C

1989-01-01

A method of determining the field enhancement factor of a practical conductor is presented. The method is developed from a modified theory of discharge onset in a gaseous medium. This modification incorporates the influence of conductor surface roughness. Onset data from an experimental study...

The silencing suppressor (NSs) protein of the plant virus Tomato spotted wilt virus enhances heterologous protein expression and baculovirus pathogenicity in cells and lepidopteran insects.

Science.gov (United States)

de Oliveira, Virgínia Carla; da Silva Morgado, Fabricio; Ardisson-Araújo, Daniel Mendes Pereira; Resende, Renato Oliveira; Ribeiro, Bergmann Morais

2015-11-01

In this work, we showed that cell death induced by a recombinant (vAcNSs) Autographa californica multiple nucleopolyhedrovirus (AcMNPV) expressing the silencing suppressor (NSs) protein of Tomato spotted wilt virus (TSWV) was enhanced on permissive and semipermissive cell lines. The expression of a heterologous gene (firefly luciferase) during co-infection of insect cells with vAcNSs and a second recombinant baculovirus (vAgppolhfluc) was shown to increase when compared to single vAgppolhfluc infections. Furthermore, the vAcNSs mean time-to-death values were significantly lower than those for wild-type AcMNPV on larvae of Spodoptera frugiperda and Anticarsia gemmatalis. These results showed that the TSWV-NSs protein could efficiently increase heterologous protein expression in insect cells as well as baculovirus pathogenicity and virulence, probably by suppressing the gene-silencing machinery in insects.

Enhanced electrocatalytic CO2 reduction via field-induced reagent concentration

Science.gov (United States)

Liu, Min; Pang, Yuanjie; Zhang, Bo; de Luna, Phil; Voznyy, Oleksandr; Xu, Jixian; Zheng, Xueli; Dinh, Cao Thang; Fan, Fengjia; Cao, Changhong; de Arquer, F. Pelayo García; Safaei, Tina Saberi; Mepham, Adam; Klinkova, Anna; Kumacheva, Eugenia; Filleter, Tobin; Sinton, David; Kelley, Shana O.; Sargent, Edward H.

2016-09-01

Electrochemical reduction of carbon dioxide (CO2) to carbon monoxide (CO) is the first step in the synthesis of more complex carbon-based fuels and feedstocks using renewable electricity. Unfortunately, the reaction suffers from slow kinetics owing to the low local concentration of CO2 surrounding typical CO2 reduction reaction catalysts. Alkali metal cations are known to overcome this limitation through non-covalent interactions with adsorbed reagent species, but the effect is restricted by the solubility of relevant salts. Large applied electrode potentials can also enhance CO2 adsorption, but this comes at the cost of increased hydrogen (H2) evolution. Here we report that nanostructured electrodes produce, at low applied overpotentials, local high electric fields that concentrate electrolyte cations, which in turn leads to a high local concentration of CO2 close to the active CO2 reduction reaction surface. Simulations reveal tenfold higher electric fields associated with metallic nanometre-sized tips compared to quasi-planar electrode regions, and measurements using gold nanoneedles confirm a field-induced reagent concentration that enables the CO2 reduction reaction to proceed with a geometric current density for CO of 22 milliamperes per square centimetre at -0.35 volts (overpotential of 0.24 volts). This performance surpasses by an order of magnitude the performance of the best gold nanorods, nanoparticles and oxide-derived noble metal catalysts. Similarly designed palladium nanoneedle electrocatalysts produce formate with a Faradaic efficiency of more than 90 per cent and an unprecedented geometric current density for formate of 10 milliamperes per square centimetre at -0.2 volts, demonstrating the wider applicability of the field-induced reagent concentration concept.

Importance of the CMAP Correction to the CHARMM22 Protein Force Field: Dynamics of Hen Lysozyme

OpenAIRE

Buck, Matthias; Bouguet-Bonnet, Sabine; Pastor, Richard W.; MacKerell, Alexander D.

2005-01-01

The recently developed CMAP correction to the CHARMM22 force field (C22) is evaluated from 25 ns molecular dynamics simulations on hen lysozyme. Substantial deviations from experimental backbone root mean-square fluctuations and N-H NMR order parameters obtained in the C22 trajectories (especially in the loops) are eliminated by the CMAP correction. Thus, the C22/CMAP force field yields improved dynamical and structural properties of proteins in molecular dynamics simulations.

The Scavenger Protein Apoptosis Inhibitor of Macrophages (AIM) Potentiates the Antimicrobial Response against Mycobacterium tuberculosis by Enhancing Autophagy

Science.gov (United States)

Sanjurjo, Lucía; Amézaga, Núria; Vilaplana, Cristina; Cáceres, Neus; Marzo, Elena; Valeri, Marta; Cardona, Pere-Joan; Sarrias, Maria-Rosa

2013-01-01