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Sample records for biochemical properties electronic

  1. Identifying the molecular functions of electron transport proteins using radial basis function networks and biochemical properties.

    Science.gov (United States)

    Le, Nguyen-Quoc-Khanh; Nguyen, Trinh-Trung-Duong; Ou, Yu-Yen

    2017-05-01

    The electron transport proteins have an important role in storing and transferring electrons in cellular respiration, which is the most proficient process through which cells gather energy from consumed food. According to the molecular functions, the electron transport chain components could be formed with five complexes with several different electron carriers and functions. Therefore, identifying the molecular functions in the electron transport chain is vital for helping biologists understand the electron transport chain process and energy production in cells. This work includes two phases for discriminating electron transport proteins from transport proteins and classifying categories of five complexes in electron transport proteins. In the first phase, the performances from PSSM with AAIndex feature set were successful in identifying electron transport proteins in transport proteins with achieved sensitivity of 73.2%, specificity of 94.1%, and accuracy of 91.3%, with MCC of 0.64 for independent data set. With the second phase, our method can approach a precise model for identifying of five complexes with different molecular functions in electron transport proteins. The PSSM with AAIndex properties in five complexes achieved MCC of 0.51, 0.47, 0.42, 0.74, and 1.00 for independent data set, respectively. We suggest that our study could be a power model for determining new proteins that belongs into which molecular function of electron transport proteins. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Hemoglobin Variants: Biochemical Properties and Clinical Correlates

    Science.gov (United States)

    Thom, Christopher S.; Dickson, Claire F.; Gell, David A.; Weiss, Mitchell J.

    2013-01-01

    Diseases affecting hemoglobin synthesis and function are extremely common worldwide. More than 1000 naturally occurring human hemoglobin variants with single amino acid substitutions throughout the molecule have been discovered, mainly through their clinical and/or laboratory manifestations. These variants alter hemoglobin structure and biochemical properties with physiological effects ranging from insignificant to severe. Studies of these mutations in patients and in the laboratory have produced a wealth of information on hemoglobin biochemistry and biology with significant implications for hematology practice. More generally, landmark studies of hemoglobin performed over the past 60 years have established important paradigms for the disciplines of structural biology, genetics, biochemistry, and medicine. Here we review the major classes of hemoglobin variants, emphasizing general concepts and illustrative examples. PMID:23388674

  3. Advanced nanoimprint patterning for functional electronics and biochemical sensing

    Science.gov (United States)

    Wang, Chao

    Nano-fabrication has been widely used for a variety of disciplines, including electronics, material science, nano-optics, and nano-biotechnology. This dissertation focuses on nanoimprint lithography (NIL) based novel nano-patterning techniques for fabricating functional structures, and discusses their applications in advanced electronics and high-sensitivity molecular sensing. In this dissertation, examples of using nano-fabricated structures for promising electronic applications are presented. For instance, 10 nm and 18 nm features are NIL-fabricated for Si/SiGe heterojunction tunneling transistors and graphene nano-ribbon transistors, using shadow evaporation and line-width shrinking techniques, respectively. An ultrafast laser melting based method is applied on flexible plastic substrates to correct defects of nano-features. Nano-texturing of sapphire substrate is developed to improve the light extraction of GaN light emitting diodes (LEDs) by 70 %. A novel multi-layer nano-patterned Si-mediated catalyst is discovered to grow straight and uniform Si nanowires with optimized properties in size, location, and crystallization on amorphous SiO2 substrate. Nano-structures are also functionalized into highly sensitive bio-chemical sensors. Plasmonic nano-bar antenna arrays are demonstrated to effectively sense infrared molecules >10 times better than conventional plasmonic sensors. As small as 20 nm wide nano-channel fluidic devices are developed to linearize and detect DNA molecules for potential DNA sequencing. An integrated fluidic system is built to incorporate plasmonic nano-structures for 30X-enhanced fluorescence detection of large DNA molecules.

  4. Electronic transport properties

    International Nuclear Information System (INIS)

    Young, W.H.

    1985-01-01

    The theory of the electron transport properties of liquid alkali metals is described. Conductivity coefficients, Boltzmann theory, Ziman theory, alkali form factors, Ziman theory and alkalis, Faber-Ziman alloy theory, Faber-Ziman theory and alkali-alkali methods, status of Ziman theory, and other transport properties, are all discussed. (UK)

  5. Recommended Nordic paediatric reference intervals for 21 common biochemical properties

    DEFF Research Database (Denmark)

    Hilsted, Linda; Rustad, Pål; Aksglæde, Lise

    2013-01-01

    healthy Danish children were collected for establishing reference intervals for 21 common biochemical properties (Alanine transaminase, Albumin, Alkaline phosphatase, Aspartate transaminase, Bilirubin, Calcium, Cholesterol, Creatinine, Creatine kinase, HDL-Cholesterol, Iron, Lactate dehydrogenase, LDL...... values of X for the properties and statistical calculations carried out as performed in the NORIP study. Thus commutable (regarding analytical method) reference intervals for 20 properties were established and for LDL-Cholesterol reference intervals were reported for the specific analytical method...... employed. The data were compared to previous studies and to those obtained from the youngest age group in the NORIP study. Marked age differences were observed for most of the properties. Several properties also showed gender-related differences, mainly at the onset of puberty. Data are presented...

  6. Electronic properties of fullerenes

    Energy Technology Data Exchange (ETDEWEB)

    Kuzmany, H [ed.; Vienna Univ. (Austria). Inst. fuer Festkoerperphysik; Fink, J [ed.; Kernforschungszentrum Karlsruhe GmbH (Germany). Inst. fuer Nukleare Festkoerperphysik; Mehring, M [ed.; Stuttgart Univ. (Germany). Physikalisches Teilinstitut 2; Roth, S [ed.; Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany)

    1993-01-01

    Since 1991, research in the field of organic carbon materials has developed at a rapid pace due to the advent of the fullerenes and related materials. These forms of carbon are considered as a missing link between the previously discussed electroactive polymers and the oxidic superconductors. It was therefore challenging to select this topic for an international winter school in Kirchberg. Although still in its infancy, research on the physics and chemistry of fullerenes and related compounds has already led to a wealth of results, which was reflected in the wide range of topics covered and the numerous discussions which emerged at the meeting. For C[sub 60] itself, preparation methods and crystal growth techniques continue to evolve, while the understanding of the electronic and structural properties of its solid state continues to pose challenges to experimental and theoretical physicists. The ever-expanding range of higher fullerens and related materials, such as nanotubes and onions, poses a daunting but exciting task for researchers. For synthetic chemists, fullerenes represent the basis of a whole new range of synthetic compounds. The prospect of a periodic table of endohedral fullerene complexes has been discussed, and exohedrally complexed metal-fullerenes have already attracted the attention of physicists. The first endohedral materials are now available. (orig.)

  7. Electronic properties of fullerenes

    International Nuclear Information System (INIS)

    Kuzmany, H.

    1993-01-01

    Since 1991, research in the field of organic carbon materials has developed at a rapid pace due to the advent of the fullerenes and related materials. These forms of carbon are considered as a missing link between the previously discussed electroactive polymers and the oxidic superconductors. It was therefore challenging to select this topic for an international winter school in Kirchberg. Although still in its infancy, research on the physics and chemistry of fullerenes and related compounds has already led to a wealth of results, which was reflected in the wide range of topics covered and the numerous discussions which emerged at the meeting. For C 60 itself, preparation methods and crystal growth techniques continue to evolve, while the understanding of the electronic and structural properties of its solid state continues to pose challenges to experimental and theoretical physicists. The ever-expanding range of higher fullerens and related materials, such as nanotubes and onions, poses a daunting but exciting task for researchers. For synthetic chemists, fullerenes represent the basis of a whole new range of synthetic compounds. The prospect of a periodic table of endohedral fullerene complexes has been discussed, and exohedrally complexed metal-fullerenes have already attracted the attention of physicists. The first endohedral materials are now available. (orig.)

  8. Collective behaviours: from biochemical kinetics to electronic circuits

    Science.gov (United States)

    Agliari, Elena; Barra, Adriano; Burioni, Raffaella; di Biasio, Aldo; Uguzzoni, Guido

    2013-12-01

    In this work we aim to highlight a close analogy between cooperative behaviors in chemical kinetics and cybernetics; this is realized by using a common language for their description, that is mean-field statistical mechanics. First, we perform a one-to-one mapping between paradigmatic behaviors in chemical kinetics (i.e., non-cooperative, cooperative, ultra-sensitive, anti-cooperative) and in mean-field statistical mechanics (i.e., paramagnetic, high and low temperature ferromagnetic, anti-ferromagnetic). Interestingly, the statistical mechanics approach allows a unified, broad theory for all scenarios and, in particular, Michaelis-Menten, Hill and Adair equations are consistently recovered. This framework is then tested against experimental biological data with an overall excellent agreement. One step forward, we consistently read the whole mapping from a cybernetic perspective, highlighting deep structural analogies between the above-mentioned kinetics and fundamental bricks in electronics (i.e. operational amplifiers, flashes, flip-flops), so to build a clear bridge linking biochemical kinetics and cybernetics.

  9. γ-Glutamyltranspeptidases: sequence, structure, biochemical properties, and biotechnological applications.

    Science.gov (United States)

    Castellano, Immacolata; Merlino, Antonello

    2012-10-01

    γ-Glutamyltranspeptidases (γ-GTs) are ubiquitous enzymes that catalyze the hydrolysis of γ-glutamyl bonds in glutathione and glutamine and the transfer of the released γ-glutamyl group to amino acids or short peptides. These enzymes are involved in glutathione metabolism and play critical roles in antioxidant defense, detoxification, and inflammation processes. Moreover, γ-GTs have been recently found to be involved in many physiological disorders, such as Parkinson's disease and diabetes. In this review, the main biochemical and structural properties of γ-GTs isolated from different sources, as well as their conformational stability and mechanism of catalysis, are described and examined with the aim of contributing to the discussion on their structure-function relationships. Possible applications of γ-glutamyltranspeptidases in different fields of biotechnology and medicine are also discussed.

  10. Biochemical and Structural Properties of Mouse Kynurenine Aminotransferase III

    Energy Technology Data Exchange (ETDEWEB)

    Han, Q.; Robinson, H; Cai, T; Tagle, D; Li, J

    2009-01-01

    Kynurenine aminotransferase III (KAT III) has been considered to be involved in the production of mammalian brain kynurenic acid (KYNA), which plays an important role in protecting neurons from overstimulation by excitatory neurotransmitters. The enzyme was identified based on its high sequence identity with mammalian KAT I, but its activity toward kynurenine and its structural characteristics have not been established. In this study, the biochemical and structural properties of mouse KAT III (mKAT III) were determined. Specifically, mKAT III cDNA was amplified from a mouse brain cDNA library, and its recombinant protein was expressed in an insect cell protein expression system. We established that mKAT III is able to efficiently catalyze the transamination of kynurenine to KYNA and has optimum activity at relatively basic conditions of around pH 9.0 and at relatively high temperatures of 50 to 60C. In addition, mKAT III is active toward a number of other amino acids. Its activity toward kynurenine is significantly decreased in the presence of methionine, histidine, glutamine, leucine, cysteine, and 3-hydroxykynurenine. Through macromolecular crystallography, we determined the mKAT III crystal structure and its structures in complex with kynurenine and glutamine. Structural analysis revealed the overall architecture of mKAT III and its cofactor binding site and active center residues. This is the first report concerning the biochemical characteristics and crystal structures of KAT III enzymes and provides a basis toward understanding the overall physiological role of mammalian KAT III in vivo and insight into regulating the levels of endogenous KYNA through modulation of the enzyme in the mouse brain.

  11. Electronic properties of graphite

    International Nuclear Information System (INIS)

    Schneider, J.

    2010-10-01

    In this thesis, low-temperature magneto-transport (T ∼ 10 mK) and the de Haas-van Alphen effect of both natural graphite and highly oriented pyrolytic graphite (HOPG) are examined. In the first part, low field magneto-transport up to B = 11 T is discussed. A Fourier analysis of the background removed signal shows that the electric transport in graphite is governed by two types of charge carriers, electrons and holes. Their phase and frequency values are in agreement with the predictions of the SWM-model. The SWM-model is confirmed by detailed band structure calculations using the magnetic field Hamiltonian of graphite. The movement of the Fermi at B > 2 T is calculated self-consistently assuming that the sum of the electron and hole concentrations is constant. The second part of the thesis deals with high field magneto-transport of natural graphite in the magnetic field range 0 ≤ B ≤ 28 T. Both spin splitting of magneto-transport features in tilted field configuration and the onset of the charge density wave (CDW) phase for different temperatures with the magnetic field applied normal to the sample plane are discussed. Concerning the Zeeman effect, the SWM calculations including the Fermi energy movement require a g-factor of g* equal to 2.5 ± 0.1 to reproduce the spin spilt features. The measurements of the charge density wave state confirm that its onset magnetic field can be described by a Bardeen-Cooper-Schrieffer (BCS)-type formula. The measurements of the de Haas-van Alphen effect are in agreement with the results of the magneto-transport measurements at low field. (author)

  12. Upgrading Laccase Production and Biochemical Properties: Strategies and Challenges.

    Science.gov (United States)

    Bertrand, Brandt; Martínez-Morales, Fernando; Trejo-Hernández, María R

    2017-07-01

    Improving laccases continues to be crucial in novel biotechnological developments and industrial applications, where they are concerned. This review breaks down and explores the potential of the strategies (conventional and modern) that can be used for laccase enhancement (increased production and upgraded biochemical properties such as stability and catalytic efficiency). The challenges faced with these approaches are briefly discussed. We also shed light on how these strategies merge and give rise to new options and advances in this field of work. Additionally, this article seeks to serve as a guide for students and academic researchers interested in laccases. This document not only gives basic information on laccases, but also provides updated information on the state of the art of various technologies that are used in this line of investigation. It also gives the readers an idea of the areas extensively studied and the areas where there is still much left to be done. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1015-1034, 2017. © 2017 American Institute of Chemical Engineers.

  13. Electronic properties of semiconductor heterostructures

    International Nuclear Information System (INIS)

    Einevoll, G.T.

    1991-02-01

    Ten papers on the electronic properties of semiconductors and semiconductor heterostructures constitute the backbone of this thesis. Four papers address the form and validity of the single-band effective mass approximation for semiconductor heterostructures. In four other papers properties of acceptor states in bulk semiconductors and semiconductor heterostructures are studied using the novel effective bond-orbital model. The last two papers deal with localized excitions. 122 refs

  14. Changes in Biochemical Properties of the Blood in Winter Swimmers.

    Science.gov (United States)

    Teleglow, Aneta; Marchewka, Jakub; Marchewka, Anna; Kulpa, Jan

    The aim of the study was to investigate the effects of winter swimming on biochemical indicators of the blood. The subjects - winter swimmers - belonged to the Krakow Walrus Club "Kaloryfer" - "The Heater". The study group consisted of 11 men, aged 30-50 years, 'walrusing' throughout the whole season from November to March. Statistically significant changes throughout the 'walrusing' season were observed for the following biochemical parameters: a decrease in sodium (mmol/1), chloride (mmol/1), alpha-2 globulin(g/1), gamma globulin (g/1), IgG (g/1), and an increase in albumin (g/1), indicator A/G, IgA (g/l ), Herpes simplex virus IgM. Seasonal effort of winter swimmers has a positive influence on biochemical blood parameters.

  15. Electronic properties of physisorbed helium

    International Nuclear Information System (INIS)

    Kossler, Sarah

    2011-01-01

    This thesis deals with electronic excitations of helium physisorbed on metal substrates. It is studied to what extent the electronic properties change compared to the gas phase due to the increased helium density and the proximity of the metal. Furthermore, the influence of different substrate materials is investigated systematically. To this end, up to two helium layers were adsorbed onto Ru (001), Pt (111), Cu (111), and Ag (111) surfaces in a custom-made cryostat. These samples were studied spectroscopically using synchrotron radiation and a time-of-flight detector. The experimental results were then analyzed in comparison with extensive theoretical model calculations.

  16. Electronic properties of physisorbed helium

    Energy Technology Data Exchange (ETDEWEB)

    Kossler, Sarah

    2011-09-22

    This thesis deals with electronic excitations of helium physisorbed on metal substrates. It is studied to what extent the electronic properties change compared to the gas phase due to the increased helium density and the proximity of the metal. Furthermore, the influence of different substrate materials is investigated systematically. To this end, up to two helium layers were adsorbed onto Ru (001), Pt (111), Cu (111), and Ag (111) surfaces in a custom-made cryostat. These samples were studied spectroscopically using synchrotron radiation and a time-of-flight detector. The experimental results were then analyzed in comparison with extensive theoretical model calculations.

  17. Electronic properties of rippled graphene

    International Nuclear Information System (INIS)

    Gui Gui; Ma Zhenqiang; Zhong Jianxin

    2012-01-01

    Short range periodic ripples in graphene have been modeled. The electronic properties of the rippled graphene have been investigated using first-principles calculations. Compared with flat graphene, there is a band gap opening in rippled graphene. Generally, the value of energy gaps increases as the height of ripples increase, but it decreases as the range of ripples enlarges. The maximum value of energy gaps in rippled graphene can reach several hundred meV, which turns rippled graphene into a good semiconductor. As a result, the magnitude of energy gaps can be tuned effectively by controlling the range and height of ripples in graphene.

  18. The Influence of Biochemical Modification on the Properties of Adhesive Compounds

    Directory of Open Access Journals (Sweden)

    Anna Rudawska

    2016-12-01

    Full Text Available The main objective of this study was to determine the effect of biochemical modification of epoxy adhesive compounds on the mechanical properties of a cured adhesive exposed to various climatic factors. The epoxy adhesive was modified by lyophilized fungal metabolites and prepared by three methods. Additionally, the adhesive compound specimens were seasoned for two months at a temperature of 50 °C and 50% humidity in a climate test chamber, Espec SH 661. The tensile strength tests of the adhesive compounds were performed using a Zwick/Roell Z150 testing machine in compliance with the DIN EN ISO 527-1 standard. The examination of the adhesive specimens was performed using two microscopes: a LEO 912AB transmission electron microscope equipped with Quantax 200 for EDS X-ray spectroscopy and a Zeiss 510 META confocal microscope coupled to an AxioVert 200M. The experiments involved the use of a CT Skyscan 1172 tomograph. The results revealed that some mechanical properties of the modified adhesives were significantly affected by both the method of preparation of the adhesive compound and the content of the modifying agent. In addition, it was found that seasoning of the modified adhesives does not lead to a decrease in some of their mechanical properties.

  19. The biochemical textural and sensory properties of frozen stored ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-08-18

    Aug 18, 2009 ... ever, freezing and storage of frozen fish may furnish favourable conditions for ...... Scallops: Biology, Ecology and Aquaculture, pp. 517-569 (Ed ... Functional properties of the myofibrillar system and their measurements.

  20. Physical and biochemical properties of green banana flour.

    Science.gov (United States)

    Suntharalingam, S; Ravindran, G

    1993-01-01

    Banana flour prepared from two cooking banana varieties, namely 'Alukehel' and 'Monthan', were evaluated for their physical and biochemical characteristics. The yields of flour averaged 31.3% for 'Alukehel' and 25.5% for 'Monthan'. The pH of the flour ranged from 5.4 to 5.7. The bulk density and particle size distribution were also measured. The average chemical composition (% dry matter) of the flours were as follows: crude protein, 3.2; crude fat, 1.3; ash, 3.7; neutral detergent fiber, 8.9; acid detergent fiber, 3.8; cellulose, 3.1; lignin, 1.0 and hemicellulose, 5.0. Carbohydrate composition indicated the flour to contain 2.8% soluble sugars, 70.0% starch and 12.0% non-starch polysaccharides. Potassium is the predominant mineral in banana flour. Fresh green banana is a good source of vitamin C, but almost 65% is lost during the preparation of flour. Oxalate content (1.1-1.6%) of banana flour is probably nutritionally insignificant. The overall results are suggestive of the potential of green bananas as a source of flour.

  1. Biochemical properties and microbial analysis of honey from North ...

    African Journals Online (AJOL)

    In the present study, physicochemical properties (pH, ash, commercial glucose, starch, reducing sugars and moisture) and microbial (yeast and enterobacterial) contaminations of 263 honey samples from North-western regions of Iran were evaluated in a 2 year period in different seasons of 2010 and 2011. Levels of ...

  2. Leaf optical properties with explicit description of its biochemical composition: direct and inverse problems

    Energy Technology Data Exchange (ETDEWEB)

    Fourty, T. [INRA, Avignon (France); Baret, F.; Jacquemoud, S.; Schmuck, G.; Verdebout, J.

    1996-05-15

    This study presents a methodology to estimate the leaf biochemical compounds specific absorption coefficients and to use them to predict leaf biochemistry. A wide range of leaves was collected including variations in species and leaf status. All the leaves were dried out. The biochemical composition was measured using classical wet chemistry techniques to determine lignin, cellulose, hemicellulose, starch, and protein contents. Concurrently, leaf reflectance and transmittance were measured with a high spectral resolution spectrophotometer in the 800–2500 nm range with approximately 1 nm spectral resolution and sampling interval. In addition, infinite reflectance achieved by stacking leaves was also measured. The PROSPECT leaf optical properties model was first inverted over a selection of wavebands in the 800–2400 nm domain to provide estimates of the scattering characteristics using leaf reflectance, transmittance, and infinite reflectance data. Then, the model was inverted again over all the wavelengths to estimate the global absorption coefficient, using the previously estimated scattering properties. The global absorption coefficient was eventually explained using the measured biochemical composition by fitting the corresponding specific absorption coefficients after substraction of the measured contribution of the residual structural water absorption. Results show that the derived specific absorption coefficients are quite robustly estimated. Further, they are in good agreement with known absorption features of each biochemical compound. The average contribution of each biochemical compound to leaf absorption feature is also evaluated. Sugar, cellulose, and hemicellulose are the main compounds that contribute to absorption. Results demonstrate the possibility of modeling leaf optical properties of dry leaves with explicit description of leaf biochemistry. Estimates of the detailed biochemical composition obtained by model inversion over the 1300–2400 nm

  3. Effects of Calcium Source on Biochemical Properties of Microbial CaCO3 Precipitation.

    Science.gov (United States)

    Xu, Jing; Du, Yali; Jiang, Zhengwu; She, Anming

    2015-01-01

    The biochemical properties of CaCO3 precipitation induced by Sporosarcina pasteurii, an ureolytic type microorganism, were investigated. Effects of calcium source on the precipitation process were examined, since calcium source plays a key role in microbiologically induced mineralization. Regardless of the calcium source type, three distinct stages in the precipitation process were identified by Ca(2+), NH4 (+), pH and cell density monitoring. Compared with stage 1 and 3, stage 2 was considered as the most critical part since biotic CaCO3 precipitation occurs during this stage. Kinetics studies showed that the microbial CaCO3 precipitation rate for calcium lactate was over twice of that for calcium nitrate, indicating that calcium lactate is more beneficial for the cell activity, which in turn determines urease production and CaCO3 precipitation. X-ray diffraction analysis confirmed the CaCO3 crystal as calcite, although scanning electron microscopy revealed a difference in crystal size and morphology if calcium source was different. The findings of this paper further suggest a promising application of microbiologically induced CaCO3 precipitation in remediation of surface and cracks of porous media, e.g., cement-based composites, particularly by using organic source of calcium lactate.

  4. Effect of ionizing radiation on biochemical and physical properties of human menisci (preliminary data)

    International Nuclear Information System (INIS)

    Uhrynowska-Tyszkiewicz, I.; Kaminski, A.

    2008-01-01

    Full text: The menisci, composed mostly of water (-70%) and collagen (-20%, predominantly type I), are integral structural components of human knee, aiding in shock absorption, joint stability, lubrication, and nutrition. Total or partial meniscectomies are associated with altered load bearing across the knee, frequently resulting in degenerative osteoarthritis. Therefore meniscal replacement has been advocated in case of extensive meniscus damage or after its removal. Among different natural and artificial materials, the use of meniscal allografts is the most promising method. However, the application of non-sterilised menisci is connected with the risk of infection disease transmission. The aim of the initial part of our study was to assess the effect of ionising radiation on biochemical properties of human menisci preserved with various methods and then irradiated with a dose 35 kGy. Twenty eight menisci from cadaveric donors were procured using standard operating procedures and then divided into the following groups: 1) fresh menisci irradiated at -70 degree C; 2) fresh menisci irradiated at room temperature (RT); 3) lyophilised menisci irradiated at -70 degree C; 4) lyophilised menisci irradiated at RT. Samples from each experimental group were irradiated with a dose of 35 kGy with 10 MeV electron accelerator. Non-irradiated menisci served as controls. Meniscal allografts were pulverised in the liquid nitrogen mill and quantitatively extracted to measure neutral soluble collagen (NSC) and acid soluble collagen (ASC) by colorimetric assay of hydroxyproline, released under extraction from tissue samples. The amount of released hydroxyproline reflects the level of collagen degradation caused by ionising radiation. As in our previous studies concerning other connective tissue allografts (bones, tendons), collagen fragmentation in menisci was also affected by preservation and sterilisation conditions. The choice of proper conditions allows one to diminish the

  5. Structural and electronic properties of L-amino acids

    Science.gov (United States)

    Tulip, P. R.; Clark, S. J.

    2005-05-01

    The structural and electronic properties of four L-amino acids alanine, leucine, isoleucine, and valine have been investigated using density functional theory (DFT) and the generalized gradient approximation. Within the crystals, it is found that the constituent molecules adopt zwitterionic configurations, in agreement with experimental work. Lattice constants are found to be in good agreement with experimentally determined values, although certain discrepancies do exist due to the description of van der Waals interactions. We find that these materials possess wide DFT band gaps in the region of 5 eV, with electrons highly localized to the constituent molecules. It is found that the main mechanisms behind crystal formation are dipolar interactions and hydrogen bonding of a primarily electrostatic character, in agreement with current biochemical understanding of these systems. The electronic structure suggests that the amine and carboxy functional groups are dominant in determining band structure.

  6. Resonance electron attachment to plant hormones and its likely connection with biochemical processes

    Energy Technology Data Exchange (ETDEWEB)

    Pshenichnyuk, Stanislav A., E-mail: sapsh@anrb.ru [Institute of Molecule and Crystal Physics, Ufa Research Centre, Russian Academy of Sciences, Prospekt Oktyabrya 151, 450075 Ufa (Russian Federation); Modelli, Alberto [Dipartimento di Chimica “G. Ciamician”, Università di Bologna, via Selmi 2, 40126 Bologna, Italy and Centro Interdipartimentale di Ricerca in Scienze Ambientali, via S. Alberto 163, 48123 Ravenna (Italy)

    2014-01-21

    Gas-phase formation of temporary negative ion states via resonance attachment of low-energy (0–6 eV) electrons into vacant molecular orbitals of salicylic acid (I) and its derivatives 3-hydroxy- (II) and 4-hydroxybenzoic acid (III), 5-cloro salicylic acid (IV) and methyl salicylate (V) was investigated for the first time by electron transmission spectroscopy. The description of their empty-level structures was supported by density functional theory and Hartree-Fock calculations, using empirically calibrated linear equations to scale the calculated virtual orbital energies. Dissociative electron attachment spectroscopy (DEAS) was used to measure the fragment anion yields generated through dissociative decay channels of the parent molecular anions of compounds I–V, detected with a mass filter as a function of the incident electron energy in the 0–14 eV energy range. The most intense negative fragment produced by DEA to isomers I–III is the dehydrogenated molecular anion [M–H]{sup −}, mainly formed at incident electron energies around 1 eV. The vertical and adiabatic electron affinities were evaluated at the B3LYP/6-31+G(d) level as the anion/neutral total energy difference. The same theoretical method was also used for evaluation of the thermodynamic energy thresholds for production of the negative fragments observed in the DEA spectra. The gas-phase DEAS data can provide support for biochemical reaction mechanisms in vivo.

  7. Resonance electron attachment to plant hormones and its likely connection with biochemical processes

    International Nuclear Information System (INIS)

    Pshenichnyuk, Stanislav A.; Modelli, Alberto

    2014-01-01

    Gas-phase formation of temporary negative ion states via resonance attachment of low-energy (0–6 eV) electrons into vacant molecular orbitals of salicylic acid (I) and its derivatives 3-hydroxy- (II) and 4-hydroxybenzoic acid (III), 5-cloro salicylic acid (IV) and methyl salicylate (V) was investigated for the first time by electron transmission spectroscopy. The description of their empty-level structures was supported by density functional theory and Hartree-Fock calculations, using empirically calibrated linear equations to scale the calculated virtual orbital energies. Dissociative electron attachment spectroscopy (DEAS) was used to measure the fragment anion yields generated through dissociative decay channels of the parent molecular anions of compounds I–V, detected with a mass filter as a function of the incident electron energy in the 0–14 eV energy range. The most intense negative fragment produced by DEA to isomers I–III is the dehydrogenated molecular anion [M–H] − , mainly formed at incident electron energies around 1 eV. The vertical and adiabatic electron affinities were evaluated at the B3LYP/6-31+G(d) level as the anion/neutral total energy difference. The same theoretical method was also used for evaluation of the thermodynamic energy thresholds for production of the negative fragments observed in the DEA spectra. The gas-phase DEAS data can provide support for biochemical reaction mechanisms in vivo

  8. Biochemical and cellular properties of Gluconacetobacter xylinus cultures exposed to different modes of rotating magnetic field

    Directory of Open Access Journals (Sweden)

    Fijałkowski Karol

    2017-06-01

    Full Text Available The aim of the present study was to evaluate the impact of a rotating magnetic field (RMF on cellular and biochemical properties of Gluconacetobacter xylinus during the process of cellulose synthesis by these bacteria. The application of the RMF during bacterial cellulose (BC production intensified the biochemical processes in G. xylinus as compared to the RMF-unexposed cultures. Moreover, the RMF had a positive impact on the growth of cellulose-producing bacteria. Furthermore, the application of RMF did not increase the number of mutants unable to produce cellulose. In terms of BC production efficacy, the most favorable properties were found in the setting where RMF generator was switched off for the first 72 h of cultivation and switched on for the further 72 h. The results obtained can be used in subsequent studies concerning the optimization of BC production using different types of magnetic fields including RMF, especially.

  9. The Influence of Biochemical Modification on the Properties of Adhesive Compounds

    OpenAIRE

    Anna Rudawska; Izabela Haniecka; Magdalena Jaszek; Monika Osińska-Jaroszuk

    2016-01-01

    The main objective of this study was to determine the effect of biochemical modification of epoxy adhesive compounds on the mechanical properties of a cured adhesive exposed to various climatic factors. The epoxy adhesive was modified by lyophilized fungal metabolites and prepared by three methods. Additionally, the adhesive compound specimens were seasoned for two months at a temperature of 50 °C and 50% humidity in a climate test chamber, Espec SH 661. The tensile strength tests of the adh...

  10. Determination of Urease Biochemical Properties of Asparagus Bean (Vigna unguiculata ssp sesquipedalis L.)

    Science.gov (United States)

    Zusfahair; Ningsih, D. R.; Fatoni, A.; Pertiwi, D. S.

    2018-04-01

    Urease is enzyme that plays a role in nitrogen metabolism during plant germination. Plants that produce a lot of urease are grains. This study used asparagus bean as source of urease. The purpose of this research is to learn the effect of germination time on the activity of urease enzyme from asparagus bean and its biochemical properties. The research was started by germination of asparagus bean on day 2, 4, 6, 8, 10 and 12. Asparagus bean sprouts were extracted using acetone and separated by centrifugation to obtain the crude extract of urease. The biochemical properties of the crude extract of urease was further determined including: the effect of temperature, pH, substrate concentration, and metal addition to urease activity. The urease activity is determined by the Nessler method. The germination time of asparagus bean in yielding urease enzyme reached the optimum activity on the 8th day with activity value of 593.7 U/mL. The biochemical properties of urease from asparagus bean have optimum activity at 35 °C, pH 7.0 and substrate concentration 0.125% with activity value of 600 U/mL. Addition of CaCl2, SnCl2 and ZnCl2 metals decrease the activity of urease.

  11. Combining phytoextraction and biochar addition improves soil biochemical properties in a soil contaminated with Cd.

    Science.gov (United States)

    Lu, Huanping; Li, Zhian; Fu, Shenglei; Méndez, Ana; Gascó, Gabriel; Paz-Ferreiro, Jorge

    2015-01-01

    The main goal of phytoremediation is to improve ecosystem functioning. Soil biochemical properties are considered as effective indicators of soil quality and are sensitive to various environmental stresses, including heavy metal contamination. The biochemical response in a soil contaminated with cadmium was tested after several treatments aimed to reduce heavy metal availability including liming, biochar addition and phytoextraction using Amaranthus tricolor L. Two biochars were added to the soil: eucalyptus pyrolysed at 600 °C (EB) and poultry litter at 400 °C (PLB). Two liming treatments were chosen with the aim of bringing soil pH to the same values as in the treatments EB and PLB. The properties studied included soil microbial biomass C, soil respiration and the activities of invertase, β-glucosidase, β-glucosaminidase, urease and phosphomonoesterase. Both phytoremediation and biochar addition improved soil biochemical properties, although results were enzyme specific. For biochar addition these changes were partly, but not exclusively, mediated by alterations in soil pH. A careful choice of biochar must be undertaken to optimize the remediation process from the point of view of metal phytoextraction and soil biological activity. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Influences of the amount of ligand on the biochemical properties of 153Sm-HEDTMP

    International Nuclear Information System (INIS)

    Yang Yuqing; Luo Shunzhong; Wang Guanquan; He Jiaheng; Pu Manfei; Bing Wenzeng

    2002-01-01

    The Effect of the amount of ligand HEDTMP on biochemical properties of 153 Sm-HEDTMP is studied. The biochemical properties include partition coefficient of 153 Sm-HEDTMP in n-octanol-water which is measured by shake-flask method, combination characteristic with BSA (bovine serum albumin) which is measured through precipitation by TCA (trichloroacetic acid) and adsorption characteristic on HA (hydroxyapatite) which is measured with the same method used in 153 Sm-EDTMP. It is found that, with the increasing in the amount of ligand, partition coefficient of 153 Sm-HEDTMP. It is found that, with the increase in the amount of ligand, partition coefficient of 153 Sm-HEDTMP in n-octanol-water decreases, so does combination percentage with BSA, but the adsorption percentage on HA shows a little and unremarkable decrease. Considering the relationships between these three biochemical properties and in vivo metabolism of 153 Sm-HEDTMP this study supports the view that an appropriate high amount of ligand should be applied in practical use

  13. Near infrared spectroscopy for determination of various physical, chemical and biochemical properties in Mediterranean soils.

    Science.gov (United States)

    Zornoza, R; Guerrero, C; Mataix-Solera, J; Scow, K M; Arcenegui, V; Mataix-Beneyto, J

    2008-07-01

    The potential of near infrared (NIR) reflectance spectroscopy to predict various physical, chemical and biochemical properties in Mediterranean soils from SE Spain was evaluated. Soil samples (n=393) were obtained by sampling thirteen locations during three years (2003-2005 period). These samples had a wide range of soil characteristics due to variations in land use, vegetation cover and specific climatic conditions. Biochemical properties also included microbial biomarkers based on phospholipid fatty acids (PLFA). Partial least squares (PLS) regression with cross validation was used to establish relationships between the NIR spectra and the reference data from physical, chemical and biochemical analyses. Based on the values of coefficient of determination (r(2)) and the ratio of standard deviation of validation set to root mean square error of cross validation (RPD), predicted results were evaluated as excellent (r(2)>0.90 and RPD>3) for soil organic carbon, Kjeldahl nitrogen, soil moisture, cation exchange capacity, microbial biomass carbon, basal soil respiration, acid phosphatase activity, β-glucosidase activity and PLFA biomarkers for total bacteria, Gram positive bacteria, actinomycetes, vesicular-arbuscular mycorrhizal fungi and total PLFA biomass. Good predictions (0.81fungi were not accurate enough to satisfactorily estimate these variables, only permitting approximate predictions (0.66biochemical soil properties for Mediterranean soils, including variables related to the composition of the soil microbial community composition.

  14. Electron relaxation properties of Ar magnetron plasmas

    Science.gov (United States)

    Xinjing, CAI; Xinxin, WANG; Xiaobing, ZOU

    2018-03-01

    An understanding of electron relaxation properties in plasmas is of importance in the application of magnetrons. An improved multi-term approximation of the Boltzmann equation is employed to study electron transport and relaxation properties in plasmas. Elastic, inelastic and nonconservative collisions between electrons and neutral particles are considered. The expressions for the transport coefficients are obtained using the expansion coefficients and the collision operator term. Numerical solutions of the matrix equations for the expansion coefficients are also investigated. Benchmark calculations of the Reid model are presented to demonstrate the accuracy of the improved multi-term approximation. It is shown that the two-term approximation is generally not accurate enough and the magnetic fields can reduce the anisotropy of the velocity distribution function. The electron relaxation properties of Ar plasmas in magnetrons for various magnetic fields are studied. It is demonstrated that the energy parameters change more slowly than the momentum parameters.

  15. European spruce bark beetle (Ips typographus, L.) green attack affects foliar reflectance and biochemical properties

    Science.gov (United States)

    Abdullah, Haidi; Darvishzadeh, Roshanak; Skidmore, Andrew K.; Groen, Thomas A.; Heurich, Marco

    2018-02-01

    The European spruce bark beetle Ips typographus, L. (hereafter bark beetle), causes major economic loss to the forest industry in Europe, especially in Norway Spruce (Picea abies). To minimise economic loss and preclude a mass outbreak, early detection of bark beetle infestation (so-called ;green attack; stage - a period at which trees are yet to show visual signs of infestation stress) is, therefore, a crucial step in the management of Norway spruce stands. It is expected that a bark beetle infestation at the green attack stage affects a tree's physiological and chemical status. However, the concurrent effect on key foliar biochemical such as foliar nitrogen and chlorophyll as well as spectral responses are not well documented in the literature. Therefore, in this study, the early detection of bark beetle green attacks is investigated by examining foliar biochemical and spectral properties (400-2000 nm). We also assessed whether bark beetle infestation affects the estimation accuracy of foliar biochemicals. An extensive field survey was conducted in the Bavarian Forest National Park (BFNP), Germany, in the early summer of 2015 to collect leaf samples from 120 healthy and green attacked trees. The spectra of the leaf samples were measured using an ASD FieldSpec3 equipped with an integrating sphere. Significant differences (p < 0.05) between healthy and infested needle samples were found in the mean reflectance spectra, with the most pronounced differences being observed in the NIR and SWIR regions between 730 and 1370 nm. Furthermore, significant differences (p < 0.05) were found in the biochemical compositions (chlorophyll and nitrogen concentration) of healthy versus green attacked samples. Our results further demonstrate that the estimation accuracy of foliar chlorophyll and nitrogen concentrations, utilising partial least square regression model, was lower for the infested compared to the healthy trees. We show that early stage of infestation reduces not only

  16. Magnetic properties of confined electron gas

    International Nuclear Information System (INIS)

    Felicio, J.R.D. de.

    1977-04-01

    The effects of confinement by a two or three-dimensional harmonic potential on the magnetic properties of a free electron gas are investigated using the grand-canonical ensemble framework. At high temperatures an extension of Darwin's, Felderhof and Raval's works is made taking into account spin effects at low temperature. A comprehensive description of the magnetic properties of a free electron gas is given. The system is regarded as finite, but the boundary condition psi=0 is not introduced. The limits of weak and strong confinement are also analysed [pt

  17. Electronic and optical properties of lead iodide

    DEFF Research Database (Denmark)

    Ahuja, R.; Arwin, H.; Ferreira da Silva, A.

    2002-01-01

    The electronic properties and the optical absorption of lead iodide (PbI2) have been investigated experimentally by means of optical absorption and spectroscopic ellipsometry, and theoretically by a full-potential linear muffin-tin-orbital method. PbI2 has been recognized as a very promising...

  18. Fauna-associated changes in chemical and biochemical properties of soil.

    Science.gov (United States)

    Tripathi, G; Sharma, B M

    2006-12-01

    To study the impacts of abundance of woodlice, termites, and mites on some functional aspects of soil in order to elucidate the specific role of soil fauna in improving soil fertility in desert. Fauna-rich sites were selected as experimental sites and adjacent areas were taken as control. Soil samples were collected from both sites. Soil respiration was measured at both sites. The soil samples were sent to laboratory, their chemical and biochemical properties were analyzed. Woodlice showed 25% decrease in organic carbon and organic matter as compared to control site. Whereas termites and mites showed 58% and 16% decrease in organic carbon and organic matter. In contrast, available nitrogen (nitrate and ammonical both) and phosphorus exhibited 2-fold and 1.2-fold increase, respectively. Soil respiration and dehydrogenase activity at the sites rich in woodlice, termites and mites produced 2.5-, 3.5- and 2-fold increases, respectively as compared to their control values. Fauna-associated increase in these biological parameters clearly reflected fauna-induced microbial activity in soil. Maximum decrease in organic carbon and increase in nitrate-nitrogen and ammonical-nitrogen, available phosphorus, soil respiration and dehydrogenase activity were produced by termites and minimum by mites reflecting termite as an efficient soil improver in desert environment. The soil fauna-associated changes in chemical (organic carbon, nitrate-nitrogen, ammonical-nitrogen, phosphorus) and biochemical (soil respiration, dehydrogenase activity) properties of soil improve soil health and help in conservation of desert pedoecosystem.

  19. Dynamic of biochemical soil properties in rainfed agave angustifolia haw. fields in semiard zone

    International Nuclear Information System (INIS)

    Cruz, A. B.; Cervantes, T. L.; Pacheco, R. P.; Martinez, M. D. L. R.; Perez, A. B.

    2015-01-01

    This study determined (a) the activity of the selected enzymes of C (invertase and cellulase), N (urease), P (acid phosphatase, AcP and alkaline phosphatase, AlkP) cycling, as well as soil microbial biomass carbon (SMBC) in the rhizosphere of Agave angustifolia Haw. (maguey espadin) cultivated in valley, hill and mountain soils in Tlacolula, Oaxaca (Mexico), and (b) changes in selected biochemical soil properties associated with seasonality and plant age. Three maguey espadin plantations with two replicates per topography were selected. Rhizosphere soil sampling was carried out for one year. AcP and urease activities were highest in mountain sites. AlkP and cellulase activities were highest in hill and mountain sites. Invertase activity and SMBC were not different among sites. Phosphatase activity showed no temporal changes. Cellulase and invertase activities were highest in December; maximum urease activity was in October and February. SMBC was highest in August. AcP activity was highest in 0-2 years old plants. AlkP activity and SMBC were highest in 2.1-4 years old plants. Urease, cellulase and invertase activity was not affected by plant age. Significant effects for the site*seasonality*plant age interaction suggest that biochemical soil properties were influenced by site. Mountain soils displayed the highest enzyme activity, which can accelerate soil organic matter turnover and contribute to the longterm sustainability of maguey espadin cropping under rainfed conditions. (author)

  20. THE SIDE-EFFECT OF ORGANIC INSECTICIDE SPINOSAD ON BIOCHEMICAL AND MICROBIOLOGICAL PROPERTIES OF CLAY SOIL

    Directory of Open Access Journals (Sweden)

    Arkadiusz Telesiński

    2015-09-01

    Full Text Available The aim of the study was to determine the effect of spinosad on soil biochemical and microbiological properties. The experiment was carried out on sandy loam with Corg content 10.91 g·kg-l. Spinosad, as Spintor 240 SC was added into soil in dosages: a recommended field dosage, and fivefold, tenfold, and twenty-fivefold higher dosages. The amount of spinosad introduced into soil was between 12.55 and 313.75 g·kg-l. Moreover, soil samples without spinosad supplement were prepared as a reference. Respective Spintor 240 SC doses were converted into 1 kg soil, taking into account 10 cm depth. After application of insecticide water emulsions, soil moisture was brought to 60% maximum holding water capacity. The soil was thoroughly mixed and stored in tightly-closed polyethylene bags at 20 °C for a period 4 weeks. During the experiment dissipation of spinosad, soil enzymes (dehydrogenase, alkaline phosphatase, acid phosphatase, urease and number of bacteria, fungi, actinomycetes were assayed. Obtained results showed, that dissipation of spinosad in soil was relatively fast – the DT50 of this insecticide was ranged between 1.11 and 2.21 days. Spinosad residues had different effects on soil microbiological and biochemical properties. However, over time the impact of this insecticide definitely decreased. This indicated that the use of spinosad in organic farming, particularly in the field dosage, does not pose a long-term threat to the soil environment.

  1. Acetylcholinesterase of the Sand Fly, Phlebotomus papatasi (Scopoli): Construction, Expression and Biochemical Properties of the G119S Orthologous Mutant

    Science.gov (United States)

    2014-12-10

    C, Pasteur N, Philips A, Fort P, Raymond M: Insecticide resistance in mosquito vectors. Nature 2003, 423:136–137. 27. Weill W, Lutfalla G, Mogensen K...Chandre F, Berthomieu A, Berticat C, Pasteur N, Philips A, Fort P, Raymond M: Corrigendum:Insecticide resistance in mosquito vectors. Nature 2003...1 biochemical properties. Comp Biochem Physiol B 2008, 150:271–277. 46. Alout H, Labbé P, Berthomieu A, Pasteur N, Weill M: Multiple duplications of

  2. Electronic properties of graphene antidot lattices

    DEFF Research Database (Denmark)

    Fürst, Joachim Alexander; Pedersen, Jesper Goor; Flindt, C.

    2009-01-01

    Graphene antidot lattices constitute a novel class of nano-engineered graphene devices with controllable electronic and optical properties. An antidot lattice consists of a periodic array of holes that causes a band gap to open up around the Fermi level, turning graphene from a semimetal...... into a semiconductor. We calculate the electronic band structure of graphene antidot lattices using three numerical approaches with different levels of computational complexity, efficiency and accuracy. Fast finite-element solutions of the Dirac equation capture qualitative features of the band structure, while full...

  3. Reconstructed Ancestral Enzymes Impose a Fitness Cost upon Modern Bacteria Despite Exhibiting Favourable Biochemical Properties.

    Science.gov (United States)

    Hobbs, Joanne K; Prentice, Erica J; Groussin, Mathieu; Arcus, Vickery L

    2015-10-01

    Ancestral sequence reconstruction has been widely used to study historical enzyme evolution, both from biochemical and cellular perspectives. Two properties of reconstructed ancestral proteins/enzymes are commonly reported--high thermostability and high catalytic activity--compared with their contemporaries. Increased protein stability is associated with lower aggregation rates, higher soluble protein abundance and a greater capacity to evolve, and therefore, these proteins could be considered "superior" to their contemporary counterparts. In this study, we investigate the relationship between the favourable in vitro biochemical properties of reconstructed ancestral enzymes and the organismal fitness they confer in vivo. We have previously reconstructed several ancestors of the enzyme LeuB, which is essential for leucine biosynthesis. Our initial fitness experiments revealed that overexpression of ANC4, a reconstructed LeuB that exhibits high stability and activity, was only able to partially rescue the growth of a ΔleuB strain, and that a strain complemented with this enzyme was outcompeted by strains carrying one of its descendants. When we expanded our study to include five reconstructed LeuBs and one contemporary, we found that neither in vitro protein stability nor the catalytic rate was correlated with fitness. Instead, fitness showed a strong, negative correlation with estimated evolutionary age (based on phylogenetic relationships). Our findings suggest that, for reconstructed ancestral enzymes, superior in vitro properties do not translate into organismal fitness in vivo. The molecular basis of the relationship between fitness and the inferred age of ancestral LeuB enzymes is unknown, but may be related to the reconstruction process. We also hypothesise that the ancestral enzymes may be incompatible with the other, contemporary enzymes of the metabolic network.

  4. A multicenter study demonstrating discordant results from electronic prostate-specific antigen biochemical failure calculation systems

    International Nuclear Information System (INIS)

    Williams, Scott G.; Pickles, Tom; Kestin, Larry; Potters, Louis; Fearn, Paul; Smith, Ryan; Pratt, Gary

    2006-01-01

    Purpose: To evaluate the interobserver variation of four electronic biochemical failure (bF) calculators using three bF definitions. Methods and Materials: The data of 1200 men were analyzed using the electronic bF calculators of four institutions. Three bF definitions were examined for their concordance of bF identification across the centers: the American Society for Therapeutic Radiology and Oncology consensus definition (ACD), the lowest prostate-specific antigen (PSA) level to date plus 2 ng/mL (L2), and a threshold of 3 ng/mL (T3). Results: Unanimous agreement regarding bF status using the ACD, L2, and T3 definitions occurred in 87.3%, 96.4%, and 92.7% of cases, respectively. Using the ACD, 63% of the variation was from one institution, which allowed the bF status to be reversed if a PSA decline was seen after bF (PSA 'bounce'). A total of 270 men had an ACD bF time variation of >2 months across the calculators, and the 5-year freedom from bF rate was 49.8-60.9%. The L2 definition had a 20.5% rate of calculated bF times; which varied by >2 months (median, 6.4; range, 2.1-75.6) and a corresponding 5-year freedom from bF rate of 55.9-61.0%. The T3 definition had a 2.0% range in the 5-year freedom from bF. Fifteen definition interpretation variations were identified. Conclusion: Reported bF results vary not only because of bF definition differences, but because of variations in how those definitions are written into computer-based calculators, with multiple interpretations most prevalent for the ACD. An algorithm to avoid misinterpretations is proposed for the L2 definition. A verification system to guarantee consistent electronic bF results requires development

  5. Electronic transport properties of phenylacetylene molecular junctions

    International Nuclear Information System (INIS)

    Liu Wen; Cheng Jie; Yan Cui-Xia; Li Hai-Hong; Wang Yong-Juan; Liu De-Sheng

    2011-01-01

    Electronic transport properties of a kind of phenylacetylene compound— (4-mercaptophenyl)-phenylacetylene are calculated by the first-principles method in the framework of density functional theory and the nonequilibrium Green's function formalism. The molecular junction shows an obvious rectifying behaviour at a bias voltage larger than 1.0 V. The rectification effect is attributed to the asymmetry of the interface contacts. Moreover, at a bias voltage larger than 2.0 V, which is not referred to in a relevant experiment [Fang L, Park J Y, Ma H, Jen A K Y and Salmeron M 2007 Langmuir 23 11522], we find a negative differential resistance phenomenon. The negative differential resistance effect may originate from the change of the delocalization degree of the molecular orbitals induced by the bias. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  6. The Determination of the Biochemical Properties of Some Monofloral Honey Samples Produced across Turkey

    Directory of Open Access Journals (Sweden)

    Aziz Gül

    2016-12-01

    Full Text Available This study was conducted in 2013 to determine the biochemical properties of 10 different monofloral honey types produced across Turkey. For the study, honey samples were obtained from beekeepers and the identity and relative percentage of dominant pollen types in samples was determined through microscopic analysis. Pollen analysis revealed that honey types chaste tree (Vitex agnus-castus and sunflower (Helianthus annuus contained high proportions of each respective pollen type. These proportions reached as high as 86%, while other honey types such as Anason had low Anasom pollen content, occurring at 45% in whole honey samples. Biochemical analysis revealed that the average honey sample quality characteristics were as followings: ash 0.37±0.04, electricity conductivity 0.79±0.07 mS/cm, moisture 19.15±0.09%, pH 3.97±0.02, acidity 29.07±0.39 meq/kg, hydroxymethylfurfural (HMF, 6.17±0.76 mg/kg, diastase 22.05±0.00, invert sugar 69.72±0.49% and sucrose 2.90±0.30%. These analyses confirmed that honey samples met standards outlined by the Turkish Food Codex Honey Standard, European Union Honey Standard and Codex Standards respectively.

  7. Electronic Properties of Disclinations in Carbon Nanostructures

    International Nuclear Information System (INIS)

    Sitenko, Yu.A.; Vlasii, N.D.; Sitenko, Yu.A.; Vlasii, N.D.

    2007-01-01

    The recent synthesis of strictly two-dimensional atomic crystals (monolayers of carbon atoms) is promising a wealth of new phenomena and possible applications in technology and industry. Such materials are characterized by the Dirac-type spectrum of quasiparticle excitations, yielding a unique example of the truly two-dimensional 'relativistic' electronic system which, in the presence of disclinations, possesses rather unusual properties. We consider the influence of disclinations on densities of states and induced vacuum quantum numbers in grapheme

  8. Electron Transport Properties of Ge nanowires

    Science.gov (United States)

    Hanrath, Tobias; Khondaker, Saiful I.; Yao, Zhen; Korgel, Brian A.

    2003-03-01

    Electron Transport Properties of Ge nanowires Tobias Hanrath*, Saiful I. Khondaker, Zhen Yao, Brian A. Korgel* *Dept. of Chemical Engineering, Dept. of Physics, Texas Materials Institute, and Center for Nano- and Molecular Science and Technology University of Texas at Austin, Austin, Texas 78712-1062 e-mail: korgel@mail.che.utexas.edu Germanium (Ge) nanowires with diameters ranging from 6 to 50 nm and several micrometer in length were grown via a supercritical fluid-liquid-solid synthesis. Parallel electron energy loss spectroscopy (PEELS) was employed to study the band structure and electron density in the Ge nanowires. The observed increase in plasmon peak energy and peak width with decreasing nanowire diameter is attributed to quantum confinement effects. For electrical characterization, Ge nanowires were deposited onto a patterned Si/SiO2 substrate. E-beam lithography was then used to form electrode contacts to individual nanowires. The influence of nanowire diameter, surface chemistry and crystallographic defects on electron transport properties were investigated and the comparison of Ge nanowire conductivity with respect to bulk, intrinsic Ge will be presented.

  9. Synthesis Properties and Electron Spin Resonance Properties of Titanic Materials

    International Nuclear Information System (INIS)

    Cho, Jung Min; Lee, Jun; Kim, Tak Hee; Sun, Min Ho; Jang, Young Bae; Cho, Sung June

    2009-01-01

    Titanic materials were synthesized by hydrothermal method of TiO 2 anatase in 10M LiOH, 10M NaOH, and 14M KOH at 130 deg. C for 30 hours. Alkaline media were removed from the synthesized products using 0.1N HCl aqueous solution. The as-prepared samples were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, Brunauer-Emmett-Teller isotherm, and electron spin resonance. Different shapes of synthesized products were observed through the typical electron microscope and indicated that the formation of the different morphologies depends on the treatment conditions of highly alkaline media. Many micropores were observed in the cubic or octahedral type of TiO 2 samples through the typical electron microscope and Langmuir adsorption-desorption isotherm of liquid nitrogen at 77 deg. K. Electron spin resonance studies have also been carried out to verify the existence of paramagnetic sites such as oxygen vacancies on the titania samples. The effect of alkali metal ions on the morphologies and physicochemical properties of nanoscale titania are discussed.

  10. The effect of high hydrostatic pressure on the physiological and biochemical properties of pepper (Capsicum annuum L.) seedlings

    Science.gov (United States)

    İşlek, Cemil; Murat Altuner, Ergin; Alpas, Hami

    2015-10-01

    High hydrostatic pressure is a non-thermal food processing technology, which also has several successful applications in different areas besides food processing. In this study, Capsicum annuum L. (pepper) seeds are subjected to 50, 100, 200 and 300 MPa pressure for 5 min at 25°C and the seedlings of HHP processed seeds are used to compare percentage of seed germination and biochemical properties such as chlorophyll a, b and a/b, proline content, total protein, carotenoid, malondialdehyde, glucose, fructose and phenolic compounds concentrations. As a result of the study, it was observed that there are remarkable changes in terms of biochemical properties especially for seedlings, whose seeds were pressurized at 200 and 300 MPa. More detailed studies are needed to put forward the mechanism behind the changes in biochemical properties.

  11. Bio-chemical properties of sandy calcareous soil treated with rice straw-based hydrogels

    Directory of Open Access Journals (Sweden)

    Houssni El-Saied

    2016-06-01

    The results obtained show that, application of the investigated hydrogels positively affects bio-chemical properties of the soil. These effects are assembled in the following: (a slightly decreasing soil pH, (b increasing cation exchange capacity (CEC of the soil indicating improvement in activating chemical reactions in the soil, (c increasing organic matter (OM, organic carbon, total nitrogen percent in the soil. Because the increase in organic nitrogen surpassed that in organic carbon, a narrower CN ratio of treated soils was obtained. This indicated the mineralization of nitrogen compounds and hence the possibility to save and provide available forms of N to growing plants, (d increasing available N, P and K in treated soil, and (e improving biological activity of the soil expressed as total count of bacteria and counts of Azotobacter sp., phosphate dissolving bacteria (PDB, fungi and actinomycetes/g soil as well as the activity of both dehydrogenase and phosphatase.

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

    Directory of Open Access Journals (Sweden)

    Xu Deng

    2014-01-01

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

  13. The Role of Compost in Stabilizing the Microbiological and Biochemical Properties of Zinc-Stressed Soil.

    Science.gov (United States)

    Strachel, Rafał; Wyszkowska, Jadwiga; Baćmaga, Małgorzata

    2017-01-01

    The progressive development of civilization and intensive industrialization has contributed to the global pollution of the natural environment by heavy metals, especially the soil. Degraded soils generally contain less organic matter, and thus, their homeostasis is more often disturbed, which in turn manifests in changes in biological and physicochemical properties of the soil. Therefore, new possibilities and solutions for possible neutralization of these contaminations are sought, inter alia, through reclamation of degraded land. At present, the use of additives supporting the reclamation process that exhibit heavy metal-sorbing properties is becoming increasingly important in soil recovery. Research was conducted to determine the role of compost in stabilizing the microbial and biochemical balance of the soil due to the significant problem of heavy metal-contaminated areas. The study was conducted on loamy sand, to which zinc was applied at the following doses: 0, 250, 500, 750, 1000, and 1250 mg Zn 2+  kg -1 DM of soil. Compost was introduced to the appropriate objects calculated on the basis of organic carbon content in the amount of 0, 10, and 20 g C org  kg -1 DM of soil. The study was conducted over a period of 20 weeks, maintaining soil moisture at 50% capillary water capacity. Zinc significantly modified soil microbiome status. The abundance of microorganisms and their biological diversity and the enzymatic activity of the soil were affected. The negative effects of contaminating zinc doses were alleviated by the introduction of compost into the soil. Organic fertilization led to microbial growth intensification and increased biochemical activity of the soil already 2 weeks after compost application. These effects persisted throughout the experiment. Therefore, it can be stated that the use of compost is an appropriate method for restoring normal functions of soil ecosystems contaminated with zinc.

  14. Development of biochemical properties in anthropic soil (the study at Třinec–Jahodná plot

    Directory of Open Access Journals (Sweden)

    Karel Marosz

    2013-01-01

    Full Text Available The properties of the anthropic soils formed at the sludge bed “Třinec-Jahodná”. The sludge bed came from a long-time depositing of fly-ash and slag layers. Therefore, the anthropic soil properties obtained their features by both a character of layered substrate and a management of the local land reclamation. The paper presented deals with the rate of an intensity of biological and biochemical soil processes in charge of the fulfilment of plant nourishment demands, and the time viewpoints focusing on the local soil development. The set of enzymatic and biological measurements were chosen for treatments of soil bodies sampled throughout 2007–2008. The study plots inside the sludge bed and the control plot were sampled; the properties of particular horizons were studied. The results proved that the twenty-year-development of soil bodies made the proper conditions for plant nutrition. The positive statement, nevertheless, is directly linked to the presence of trees and shrubs. The vegetation seems to be one of the very crucial factors for a status of the site and maintenance of soil productivity: it affects temperature amplitudes, sensitivity to erosion, a redistribution of soil water, and a humic compounds accumulation. The statistical analyses showed significantly differing results on the study plots with a shorter development and a lower rate of vegetational cover.

  15. Electronic properties of a biased graphene bilayer

    International Nuclear Information System (INIS)

    Castro, Eduardo V; Lopes dos Santos, J M B; Novoselov, K S; Morozov, S V; Geim, A K; Peres, N M R; Nilsson, Johan; Castro Neto, A H; Guinea, F

    2010-01-01

    We study, within the tight-binding approximation, the electronic properties of a graphene bilayer in the presence of an external electric field applied perpendicular to the system-a biased bilayer. The effect of the perpendicular electric field is included through a parallel plate capacitor model, with screening correction at the Hartree level. The full tight-binding description is compared with its four-band and two-band continuum approximations, and the four-band model is shown to always be a suitable approximation for the conditions realized in experiments. The model is applied to real biased bilayer devices, made out of either SiC or exfoliated graphene, and good agreement with experimental results is found, indicating that the model is capturing the key ingredients, and that a finite gap is effectively being controlled externally. Analysis of experimental results regarding the electrical noise and cyclotron resonance further suggests that the model can be seen as a good starting point for understanding the electronic properties of graphene bilayer. Also, we study the effect of electron-hole asymmetry terms, such as the second-nearest-neighbour hopping energies t' (in-plane) and γ 4 (inter-layer), and the on-site energy Δ.

  16. Electron beam crosslinked PVC : structure property relationships

    International Nuclear Information System (INIS)

    Gupta, Neeraj K.; Sabharwal, Sunil

    2001-01-01

    PVC is used extensively for its insulating properties for the manufacture of wires and cables and for other applications. Its gradual degradation, oxidation and even dehydro chlorination restricts use for long lasting period in installations such as high temperature zones, underground cables, communication systems, electro-nuclear facilities, etc. The technological properties and performance characteristics of PVC based insulation can be improved via crosslinking by high-energy electrons. PVC is however a polymer, which on irradiation predominantly undergoes degradation. To avoid degradation, it needs to be compounded with sensitizing agents or multifunctional monomers so that crosslinking is the predominant reaction. Radiation cross linkable formulations are complex mixtures of resin and various additives incorporated for achieving desired technological and performance characteristics, ease of processing and improving quality. The proper choice of additives and sensitizing agents enable low dose requirements for efficient crosslinking and improvements in various technological properties. The purposes of this work was to investigate the effect of using a binary sensitizer blend of a trifunctional monomer and a rubber in PVC, and develop suitable electron beam cross linkable formulations for wire insulation. This paper presents some aspects of the investigations and development of insulation demonstrated at industrial scale

  17. Fabrication and Electronic Properties of CZTSe

    Energy Technology Data Exchange (ETDEWEB)

    Bishop, Douglas M.; McCandless, Brian E.; Haight, Richard; Mitzi, David B.; Birkmire, Robert W.

    2014-06-09

    To solve the open circuit voltage limitation in Cu2ZnSn(SSe)4 further understanding of defects and the fundamental properties of the bulk material are needed. Although there are a number of literature reports of single crystals, the vast majority are made with a flux agent such as iodine which could potentially act as a dopant or affect defect properties in the material. In this report 2-5 mm single crystals of CZTSe of different compositions were achieved by solid state reaction of elements in a sealed ampoule below the melt temperature without a flux agent. The bulk composition of single crystals are compared to electronic and opto-electronic properties from Hall and photoluminescence (PL) measurements. Intergrain measurements showed record hole mobilities for pure CZTSe in excess of 100 cm2/Vs. PL intensity and uniformity were improved by removing inhomogeneities and surface phases through crystal polishing, followed by Br-methanol etching to remove polishing damage. Despite processing conditions more favorable to equilibrium crystal conditions, a broad PL peak is observed with significant luminescence below the band-gap similar to literature reports of band-tailing. A more detailed publication of results and further experiments will be reported in an upcoming Journal of Photovoltaics.

  18. High resolution of heterogeneity among human neutrophil granules: physical, biochemical, and ultrastructural properties of isolated fractions.

    Science.gov (United States)

    Rice, W G; Kinkade, J M; Parmley, R T

    1986-08-01

    Previous studies on the fractionation of human neutrophil granules have identified two major populations: myeloperoxidase (MPO)-containing azurophil, or primary, granules and MPO-deficient specific, or secondary, granules. Peripheral blood neutrophils from individual donors were lysed in sucrose-free media by either hypotonic shock or nitrogen cavitation. Using a novel two-gradient Percoll density centrifugation system, the granule-rich postnuclear supernatant was rapidly (ten minutes) and reproducibly resolved into 13 granule fractions (L1 through L8 and H1 through H5). Granule flotation and recentrifugation experiments on both continuous, self-generated and multiple-step gradients using individual and mixed isolated fractions demonstrated that the banding patterns were isopycnic and nonartifactual. Isolated granules were intact based on the findings that biochemical latency of several granule enzymes was greater than 95%, and thin-sectioned electron micrographs demonstrated intact granule profiles. Biochemical analyses of the granule marker proteins MPO, beta-glucuronidase, lysozyme, and lactoferrin indicated that a number of the fractions were related to the major azurophil and specific granule populations. Lactoferrin was found in ten of 13 fractions (L1 through L8, H1 to H2), whereas MPO was found in every fraction. Consistent with these biochemical data, all fractions exhibited varying degrees of heterogeneity based on ultrastructural morphology and cytochemistry, including diaminobenzidine (DAB) reactivity for peroxidase and periodate-thiocarbohydrazide-silver proteinate (PA-TCH-SP) staining for complex glycoconjugates. A variable but significant percentage (23% to 70%) of the granules in fractions L1 through L8 and H1 and H2 showed DAB reactivity, while about 90% of the granules in fractions H3 through H5 were peroxidase positive. These results demonstrated that DAB-reactive granules spanned the entire range of granule size and density. Ultrastructural PA

  19. Electronic transport properties of (fluorinated) metal phthalocyanine

    KAUST Repository

    Fadlallah, M M; Eckern, U; Romero, A H; Schwingenschlö gl, Udo

    2015-01-01

    The magnetic and transport properties of the metal phthalocyanine (MPc) and F16MPc (M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn and Ag) families of molecules in contact with S–Au wires are investigated by density functional theory within the local density approximation, including local electronic correlations on the central metal atom. The magnetic moments are found to be considerably modified under fluorination. In addition, they do not depend exclusively on the configuration of the outer electronic shell of the central metal atom (as in isolated MPc and F16MPc) but also on the interaction with the leads. Good agreement between the calculated conductance and experimental results is obtained. For M = Ag, a high spin filter efficiency and conductance is observed, giving rise to a potentially high sensitivity for chemical sensor applications.

  20. Electronic transport properties of (fluorinated) metal phthalocyanine

    KAUST Repository

    Fadlallah, M M

    2015-12-21

    The magnetic and transport properties of the metal phthalocyanine (MPc) and F16MPc (M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn and Ag) families of molecules in contact with S–Au wires are investigated by density functional theory within the local density approximation, including local electronic correlations on the central metal atom. The magnetic moments are found to be considerably modified under fluorination. In addition, they do not depend exclusively on the configuration of the outer electronic shell of the central metal atom (as in isolated MPc and F16MPc) but also on the interaction with the leads. Good agreement between the calculated conductance and experimental results is obtained. For M = Ag, a high spin filter efficiency and conductance is observed, giving rise to a potentially high sensitivity for chemical sensor applications.

  1. Structural and electronic properties of thallium compounds

    International Nuclear Information System (INIS)

    Paliwal, Neetu; Srivastava, Vipul

    2016-01-01

    The tight binding linear muffin-tin-orbital (TB-LMTO) method within the local density approximation (LDA has been used to calculate structural and electronic properties of thallium pnictides TlX (X=Sb, Bi) at high pressure. As a function of volume, the total energy is evaluated. Apart from this, the lattice parameter (a_0), bulk modulus (B_0), band structure (BS) and density of states (DOS) are calculated. From energy band diagram we observed metallic behaviour in TlSb and TlBi compounds. The values of equilibrium lattice constants and bulk modulus are agreed well with the available data.

  2. Structural and electronic properties of thallium compounds

    Energy Technology Data Exchange (ETDEWEB)

    Paliwal, Neetu, E-mail: neetumanish@gmail.com [Department of Physics, AISECT University Bhopal, 464993 (India); Srivastava, Vipul [Department of Engineering Physics, NRI Institute of Research & Technology, Raisen Road, Bhopal, 462021 (India)

    2016-05-06

    The tight binding linear muffin-tin-orbital (TB-LMTO) method within the local density approximation (LDA has been used to calculate structural and electronic properties of thallium pnictides TlX (X=Sb, Bi) at high pressure. As a function of volume, the total energy is evaluated. Apart from this, the lattice parameter (a{sub 0}), bulk modulus (B{sub 0}), band structure (BS) and density of states (DOS) are calculated. From energy band diagram we observed metallic behaviour in TlSb and TlBi compounds. The values of equilibrium lattice constants and bulk modulus are agreed well with the available data.

  3. Effect of polyamines on biochemical properties in gamma irradiated Okra (Abelmoschus esculentus L.) varieties

    International Nuclear Information System (INIS)

    Bhushan, Himanshu; Shukla, Pradeep K.; Ramteke, Pramod W.; Misra, Pragati

    2014-01-01

    Gamma rays are electromagnetic radiations and can be useful for the alteration of physiological characters. In plant systems, gamma ray induced free radicals can damage or modify important components of plant cells and also modulate the morphological, anatomical and biochemical characters of the cell and the plant therein. Polyamine possesses protective role against unfavorable conditions because of its highest positive charge due to presence of amine groups. In plants polyamines are involved in organ development, flowering, fruit ripening, and senescence and stress responses. Okra (Abelmoschus esculentus L.) has captured a prominent position among vegetables and in India; it is grown on an area of 3.6 lakh hectares with a production of 34.2 lakh tones. Keeping these facts in mind, an experiment was conducted to study the effect of polyamines on biochemical properties in gamma irradiated Okra (Abelmoschus esculentus L.) varieties. Seeds of four Okra varieties (namely Kaveri 49, Kaveri 54, Deepika and OH2324) were expose to different levels of gamma radiation (T 1 = 200 Gy, T 2 = 400 Gy, T 3 = 600 Gy, and T 4 = 800 Gy) using 60 Co as source at National Botanical Research Institute (NBRI) research institute of CSIR at Lucknow. These plants were also subjected to an exogenous application of 1 mM spermine and 1 mM spermidineas foliar spray. The results showed that application of Polyamines (spermine and spermidine) increased Chlorophyll α content, Chlorophyll b content (mg/g fresh weight) in gamma treated plants as compared to control. Application of polyamines also increased enzymatic and non-enzymatic antioxidants (proline, ascorbte peroxidase and glutathione reductase) level in gamma treated plants as compared to control. Carotenoid and protein content showed variations under polyamine treatment. In general, variety Deepika was relatively tolerant to gamma radiation among all the varieties, whereas, Kaveri 49 and Kaveri 54 were relatively sensitive to gamma

  4. Dynamic properties of electrons in solids by neutron scattering

    International Nuclear Information System (INIS)

    Lovesey, S.W.

    1980-12-01

    Illustrative cases of the use of neutron scattering in the study of the electronic properties of materials discussed here include scattering by localised electrons, narrow band materials and electron plasmas. (U.K.)

  5. Soil biochemical properties of grassland ecosystems under anthropogenic emission of nitrogen compounds

    Science.gov (United States)

    Kudrevatykh, Irina; Ivashchenko, Kristina; Ananyeva, Nadezhda

    2016-04-01

    Inflow of pollutants in terrestrial ecosystems nowadays increases dramatically, that might be led to disturbance of natural biogeochemical cycles and landscapes structure. Production of nitrogen fertilizers is one of the air pollution sources, namely by nitrogen compounds (NH4+, NO3-, NO2-). Air pollution by nitrogen compounds of terrestrial ecosystems might be affected on soil biochemical properties, which results increasing mineral nitrogen content in soil, changing soil P/N and Al/Ca ratios, and, finally, the deterioration of soil microbial community functioning. The research is focused on the assessment of anthropogenic emission of nitrogen compounds on soil properties of grassland ecosystems in European Russia. Soil samples (Voronic Chernozem Pachic, upper 10 cm mineral layer, totally 10) were taken from grassland ecosystem: near (5-10 m) nitrogen fertilizer factory (NFF), and far from it (20-30 km, served as a control) in Tula region. In soil samples the NH4+ and NO3- (Kudeyarov's photocolorimetric method), P, Ca, Al (X-ray fluorescence method) contents were measured. Soil microbial biomass carbon (Cmic) was analyzed by substrate-induced respiration method. Soil microbial respiration (MR) was assessed by CO2 rate production. Soil microbial metabolic quotient (qCO2) was calculated as MR/Cmic ratio. Near NFF the soil ammonium and nitrate nitrogen contents were a strongly varied, variation coefficient (CV) was 42 and 86This study was supported by Russian Foundation of Basic Research Grant No. 14-04-00098, 15-44-03220, 15-04-00915.

  6. Chemical, Biochemical, and Microbiological Properties of Soils from Abandoned and Extensively Cultivated Olive Orchards

    Directory of Open Access Journals (Sweden)

    A. M. Palese

    2013-01-01

    Full Text Available The abandonment of olive orchards is a phenomenon of great importance triggered mainly by economic and social causes. The aim of this study was to investigate some chemical, biochemical, and microbiological properties in a soil of a southern olive grove abandoned for 25 years. In order to define the effect of the long-term land abandonment on soil properties, an adjacent olive grove managed according to extensive practices was taken as reference (essentially minimum tillage and no fertilization. Soil organic matter, total nitrogen, and pH were significantly higher in the abandoned olive grove due to the absence of tillage and the natural inputs of organic matter at high C/N ratio which, inter alia, increased the number of cellulolytic bacteria and stimulated the activity of β-glucosidase, an indicator of a more advanced stage of soil evolution. The soil of the abandoned olive orchard showed a lower number of total bacteria and fungi and a lower microbial diversity, measured by means of the Biolog method, as a result of a sort of specialization trend towards low quality organic substrates. From this point of view, the extensive cultivation management seemed to not induce a disturbance to microbiological communities.

  7. Chemical, Biochemical, and Microbiological Properties of Soils from Abandoned and Extensively Cultivated Olive Orchards

    Science.gov (United States)

    Palese, A. M.; Magno, R.; Casacchia, T.; Curci, M.; Baronti, S.; Miglietta, F.; Crecchio, C.; Xiloyannis, C.; Sofo, A.

    2013-01-01

    The abandonment of olive orchards is a phenomenon of great importance triggered mainly by economic and social causes. The aim of this study was to investigate some chemical, biochemical, and microbiological properties in a soil of a southern olive grove abandoned for 25 years. In order to define the effect of the long-term land abandonment on soil properties, an adjacent olive grove managed according to extensive practices was taken as reference (essentially minimum tillage and no fertilization). Soil organic matter, total nitrogen, and pH were significantly higher in the abandoned olive grove due to the absence of tillage and the natural inputs of organic matter at high C/N ratio which, inter alia, increased the number of cellulolytic bacteria and stimulated the activity of β-glucosidase, an indicator of a more advanced stage of soil evolution. The soil of the abandoned olive orchard showed a lower number of total bacteria and fungi and a lower microbial diversity, measured by means of the Biolog method, as a result of a sort of specialization trend towards low quality organic substrates. From this point of view, the extensive cultivation management seemed to not induce a disturbance to microbiological communities. PMID:24348166

  8. Muscle fiber population and biochemical properties of whole body muscles in Thoroughbred horses.

    Science.gov (United States)

    Kawai, Minako; Minami, Yoshio; Sayama, Yukiko; Kuwano, Atsutoshi; Hiraga, Atsushi; Miyata, Hirofumi

    2009-10-01

    We examine the muscle fiber population and metabolic properties of skeletal muscles from the whole body in Thoroughbred horses. Postmortem samples were taken from 46 sites in six Thoroughbred horses aged between 3 and 6 years. Fiber type population was determined on muscle fibers stained with monoclonal antibody to each myosin heavy chain isoform and metabolic enzyme activities were determined spectrophotometrically. Histochemical analysis demonstrated that most of the muscles had a high percentage of Type IIa fibers. In terms of the muscle characteristic in several parts of the horse body, the forelimb muscles had a higher percentage of Type IIa fiber and a significantly lower percentage of Type IIx fiber than the hindlimb muscles. The muscle fiber type populations in the thoracic and trunk portion were similar to those in the hindlimb portion. Biochemical analysis indicated high succinate dehydrogenase activity in respiratory-related muscle and high phosphofructokinase activity in hindlimbs. We suggested that the higher percentage of Type IIa fibers in Thoroughbred racehorses is attributed to training effects. To consider further the physiological significance of each part of the body, data for the recruitment pattern of each muscle fiber type during exercise are needed. The muscle fiber properties in this study combined with the recruitment data would provide fundamental information for physiological and pathological studies in Thoroughbred horses.

  9. Effect of electromagnetic fields on some biomechanical and biochemical properties of rat’s blood

    Science.gov (United States)

    Mohaseb, M. A.; Shahin, F. A.; Ali, F. M.; Baieth, H. A.

    2017-06-01

    In order to study the effect of electromagnetic fields (0.3 mT, 50 Hz) on some biomechanical and biochemical properties of rats’ blood, healthy thirty male albino rats of 150 ± 10 g were divided into three equal groups namely A, B1, B2. Group A used as a control group, group B1 was continuously exposed to a magnetic field of (0.3 mT, 50 Hz) for a period of 21 days for direct effect studies. Group B2 was continuously exposed to the same magnetic field for the same period of time, then was housed away from the magnetic field for a period of 45 days for delayed effects studies. After examination, the results indicated that the apparent viscosity and the consistency index increased significantly and very high significantly for groub B1 and B2 compared to control at Pbone marrow functions. These results are supported by the blood film image, where irregularities and deformations in the RBCs membranes had been occurred. We conclude that the cell membrane properties are highly affected by the extremely low frequency (ELF) magnetic fields, which proved to be biologically toxic.

  10. Electronic and transport properties of kinked graphene

    DEFF Research Database (Denmark)

    Rasmussen, Jesper Toft; Gunst, Tue; Bøggild, Peter

    2013-01-01

    Local curvature, or bending, of a graphene sheet is known to increase the chemical reactivity presenting an opportunity for templated chemical functionalisation. Using first-principles calculations based on density functional theory (DFT), we investigate the reaction barrier reduction for the ads......Local curvature, or bending, of a graphene sheet is known to increase the chemical reactivity presenting an opportunity for templated chemical functionalisation. Using first-principles calculations based on density functional theory (DFT), we investigate the reaction barrier reduction...... for the adsorption of atomic hydrogen at linear bends in graphene. We find a significant barrier lowering (≈15%) for realistic radii of curvature (≈20 Å) and that adsorption along the linear bend leads to a stable linear kink. We compute the electronic transport properties of individual and multiple kink lines......, and demonstrate how these act as efficient barriers for electron transport. In particular, two parallel kink lines form a graphene pseudo-nanoribbon structure with a semimetallic/semiconducting electronic structure closely related to the corresponding isolated ribbons; the ribbon band gap translates...

  11. Electronic properties of lithium titanate ceramic

    International Nuclear Information System (INIS)

    Padilla-Campos, Luis; Buljan, Antonio

    2001-01-01

    Research on tritium breeder material is fundamental to the development of deuterium-tritium type fusion reactors for producing clean, non contaminating, electrical energy, since only energy and helium, a harmless gas, are produced from the fusion reaction. Lithium titanate ceramic is one of the possible candidates for the tritium breeder material. This last material is thought to form part of the first wall of the nucleus of the reactor which will provide the necessary tritium for the fusion and will also serve as a shield. Lithium titanate has advantageous characteristics compared to other materials. Some of these are low activation under the irradiation of neutrons, good thermal stability, high density of lithium atoms and relatively fast tritium release at low temperatures. However, there are still several physical and chemical properties with respect to the tritium release mechanism and mechanical properties that have not been studied at all. This work presents a theoretical study of the electronic properties of lithium titanate ceramic and the corresponding tritiated material. Band calculations using the Extended H kel Tight-Binding approach were carried out. Results show that after substituting lithium for tritium atoms, the electronic states for the latter appear in the middle of prohibited band gap which it is an indication that the tritiated material should behave as a semiconductor, contrary to Li 2 TiO 3 which is a dielectric isolator. A study was also carried out to determine the energetically most favorable sites for the substitution of lithium for tritium atoms. Additionally, we analyzed possible pathways for the diffusion of a tritium atom within the crystalline structure of the Li 2 TiO 3

  12. Microbial community, and biochemical and physiological properties of Korean traditional black raspberry (Robus coreanus Miquel) vinegar.

    Science.gov (United States)

    Song, Nho-Eul; Cho, Sung-Ho; Baik, Sang-Ho

    2016-08-01

    The aim of this study was to elucidate the changes in microbial community and biochemical and physiological properties of traditional Muju black raspberry (Robus coreanus Miquel) vinegar (TMBV) during fermentation by culture-independent methods. During vinegar fermentation, ethanol produced up to 120 g L(-1) until day 35, with continuously increasing yeast concentration to a total of log 7.6 CFU mL(-1) . After day 35, acetic acid bacteria (AAB) concentrations rose to log 5.8 CFU mL(-1) until day 144. Denaturing gradient gel electrophoresis analysis showed that Saccharomyces cerevisiae was detected until day 87 of the fermentation, at which point Acetobacter pasteurianus gradually took over as the dominant species. Total sugar was reduced to 6.6 °Brix and total acidity produced up to 44 g L(-1) . In this study, we established the physicochemical analysis and growth dynamics of yeast and AAB during alcoholic and acetic acid fermentation of black raspberry by a traditional method. Overall, S. cerevisiae and A. pasteurianus species appeared to dominate the TMBV fermentation. In conclusion, this study demonstrated a suitable fermentation system for TMBV by the static surface method. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  13. Effect of irradiation on physiological and biochemical properties of Bt rice seedlings

    International Nuclear Information System (INIS)

    Wang Zhonghua; Chen Xiaojian; Bao Xusheng; Chen Yuling; Gu Qinqin

    2011-01-01

    The seeds of two varieties of Bt rice were treated by 60 Co γ-rays at the doses of 50, 100, 150, 250 and 350 Gy, respectively, their original parent was used as control material. The seedlings cultured from above seeds were used to detect the root activity, seedling growth, chlorophyll content,activities of phenylalanine ammonialyase (PAL), polyphenol oxidase (PPO), catalase(CAT), superoxide dismutase (SOD) and amylase to investigate the effect of irradiation treatment on the physiological and biochemical properties of Bt rice. The results showed that root activity, chlorophyll content, activities of PAL, PPO, CAT, SOD of Bt rice seedlings and amylase of germinating seeds were lower than those of the control group after irradiation treatment of < 250 Gy, but the differences were not significant, which was similar to those of original parent. Meanwhile, it was found that with dose increasing, the seedling height was increased, suggesting that irradiation treatment could stimulate the seedling growth. Therefore, Bt transgene can not change the irradiation sensitivity of rice and the conventional method of rice can be used in Bt rice irradiation mutation breeding. (authors)

  14. General and biochemical properties of forest soils on serpentinized areas of Galicia

    International Nuclear Information System (INIS)

    Pena, Wagner; Briceno, Jorge A.; Leiros de la Pena, Maria del Carmen

    2005-01-01

    The use agricultural and forest soils is normal in the territory of the Autonomous Community of Galicia for submitting the physical, chemical and agroclimatic optimum. The region has areas by the characteristics of the environment has been impossible to use agricultural and forestry. Serpentinite soils developed on frequently drew attention to the high degree of infertility, caused by nutrient deficiency and excess toxic metal content. The results of general physical and chemical properties have been analyzed of the total metal content and biochemical parameters of 28 soils on serpentinite in A Coruna Galicia, Spain. The infertility of soil organic matter, nutrients and low microbial activity and biochemistry have been caused by high level of pH and nutritional imbalance due to the high content of Mg 2+ . OM (organic matter) content, total N, soluble P and exchangeable K + , were lower due to the underdevelopment of vegetation and the potential toxic effects that have metal on the biological activity in the middle. (author) [es

  15. Quality and biochemical properties of artificially hibernated crucian carp for waterless preservation.

    Science.gov (United States)

    Mi, Hongbo; Qian, Chunlu; Mao, Linchun

    2012-12-01

    The aim of this study was to explore the artificial hibernation of crucian carp for waterless preservation and to characterize the quality and biochemical properties during and after the hibernation. Anesthetized crucian carp using eugenol were stored at 8 °C with 90 % oxygen and 95-100 % relative humidity for 38 h and then transferred to fresh water to recover. Liquid loss and cooking loss had no significant changes (p > 0.05). The total volatile basic nitrogen content and 2-thiobarbituric acid value in hibernated fish were significantly higher (p 0.05). Both ACP and AKP activities decreased upon the fish recovered, but only the ACP activity returned to normal. However, there were increased serum glucose concentration, GOT and GPT activities in recovered fish. On the basis of these findings, it can be concluded that the artificially hibernated life of crucian carp was 38 h by the combination of anaesthetizing and low temperature. The muscle quality would not be influenced, and most of the stress responses would disappear after hibernated fish recovered.

  16. Characteristic Variations and Similarities in Biochemical, Molecular, and Functional Properties of Glyoxalases across Prokaryotes and Eukaryotes.

    Science.gov (United States)

    Kaur, Charanpreet; Sharma, Shweta; Hasan, Mohammad Rokebul; Pareek, Ashwani; Singla-Pareek, Sneh L; Sopory, Sudhir K

    2017-03-30

    The glyoxalase system is the ubiquitous pathway for the detoxification of methylglyoxal (MG) in the biological systems. It comprises two enzymes, glyoxalase I (GLYI) and glyoxalase II (GLYII), which act sequentially to convert MG into d-lactate, thereby helping living systems get rid of this otherwise cytotoxic byproduct of metabolism. In addition, a glutathione-independent GLYIII enzyme activity also exists in the biological systems that can directly convert MG to d-lactate. Humans and Escherichia coli possess a single copy of GLYI (encoding either the Ni- or Zn-dependent form) and GLYII genes, which through MG detoxification provide protection against various pathological and disease conditions. By contrast, the plant genome possesses multiple GLYI and GLYII genes with a role in abiotic stress tolerance. Plants possess both Ni 2+ - and Zn 2+ -dependent forms of GLYI, and studies on plant glyoxalases reveal the various unique features of these enzymes distinguishing them from prokaryotic and other eukaryotic glyoxalases. Through this review, we provide an overview of the plant glyoxalase family along with a comparative analysis of glyoxalases across various species, highlighting similarities as well as differences in the biochemical, molecular, and physiological properties of these enzymes. We believe that the evolution of multiple glyoxalases isoforms in plants is an important component of their robust defense strategies.

  17. Electric and magnetic fields do not modify the biochemical properties of FRTL-5 cells.

    Science.gov (United States)

    Dimida, A; Ferrarini, E; Agretti, P; De Marco, G; Grasso, L; Martinelli, M; Longo, I; Giulietti, D; Ricci, A; Galimberti, M; Siervo, B; Licitra, G; Francia, F; Pinchera, A; Vitti, P; Tonacchera, M

    2011-03-01

    Electric and magnetic fields (EMF) might be involved in human disease and numerous research and scientific reviews have been conducted to address this question. In particular thyroid structural and functional alterations caused by various forms of non-ionizing radiation have been described. The aim of this study was to analyze the possible effects of EMF on thyroid, in particular we analyzed the effects caused by a GSM (Global System for Mobile Communications) signal (900 MHz) on cultured thyroid cells (FRTL- 5). The experimental setup was designed in order to expose samples to a radiofrequency wave in well-controlled conditions. We used the FRTL-5 cell line, an epithelial monoclonal continuous cell line derived from Fisher rat thyroid tissue growing as monolayer, expressing the TSH receptor and the sodium-iodide symporter (NIS). FRTL-5 were subsequently irradiate for 24, 48, and 96 h with EMF (800-900 MHz, power-frequency of mobile communication systems) and iodide uptake and cAMP production were measured. The irradiation of cells with EMF at 900 Mhz for 24, 48, and 96 h did not influence the level of cAMP production and was not able to modify iodide accumulation in FRTL- 5 cells with respect to basal conditions. In conclusion, EMF do not seem to be able to interfere with the biochemical properties of FRTL-5 cells in vitro.

  18. Electronic and conformational properties of 2,3-benzodiazepine derivates

    International Nuclear Information System (INIS)

    Pelaggi, M.; Girlanda, R.; Chimirri, A.; Gitto, R.

    1996-01-01

    The molecular geometric and electronic structures of 2,3-benzodiazepine derivates have been studied by means of the MNDO-PM3 method. A number of electronic properties have been computed and examined in order to find indication of the role of the electronic characteristics of the different molecules and their pharmacological properties. Theoretical data indicate that both electronic and structural properties appear responsible for the varying degree of anticonvulsant activity exhibited by compounds 1-4

  19. Electronic and conformational properties of 2,3-benzodiazepine derivates

    Energy Technology Data Exchange (ETDEWEB)

    Pelaggi, M.; Girlanda, R. [Messina Univ. (Italy). Dip. di Fisica della Materia e Fisica dell`Ambiente; Chimirri, A.; Gitto, R. [Messina Univ. (Italy). Dip. Farmaco-Chimico

    1996-04-01

    The molecular geometric and electronic structures of 2,3-benzodiazepine derivates have been studied by means of the MNDO-PM3 method. A number of electronic properties have been computed and examined in order to find indication of the role of the electronic characteristics of the different molecules and their pharmacological properties. Theoretical data indicate that both electronic and structural properties appear responsible for the varying degree of anticonvulsant activity exhibited by compounds 1-4.

  20. Immunodominant role of CCHA subunit of Concholepas hemocyanin is associated with unique biochemical properties.

    Science.gov (United States)

    Becker, María Inés; Fuentes, Alejandra; Del Campo, Miguel; Manubens, Augusto; Nova, Esteban; Oliva, Harold; Faunes, Fernando; Valenzuela, María Antonieta; Campos-Vallette, Marcelo; Aliaga, Alvaro; Ferreira, Jorge; De Ioannes, Alfredo E; De Ioannes, Pablo; Moltedo, Bruno

    2009-03-01

    Hemocyanin, the oxygen transporter metallo-glycoprotein from mollusks, shows strong relationship between its notable structural features and intrinsic immunomodulatory effects. Here we investigated the individual contribution of CCHA and CCHB subunits from Concholepas hemocyanin (CCH) to in vivo humoral immune response and their pre-clinical evaluation as immunotherapeutic agent in a mice bladder cancer model, in relation to their biochemical properties. To this end, subunits were purified and well characterized. Homogeneous subunits were obtained by anionic exchange chromatography, and its purity assessed by electrophoretic and immunochemical methods. While each CCH subunit contains eight functional units showing partial cross reaction, the vibrational spectral analysis showed several spectral differences, suggesting structural differences between them. In addition, we demonstrated differences in the carbohydrate content: CCHA had a 3.6% w/w sugar with both N- and O-linked moieties. In turn, CCHB had a 2.5% w/w sugar with N-linked, while O-linked moieties were nearly absent. Considering these differences, it was not possible to predict a priori whether the immunogenic and immunotherapeutic properties of subunits might be similar. Surprisingly, both subunits by itself induced a humoral response, and showed an antitumor effect in the bladder carcinoma cell line MBT-2. However, when immunologic parameters were analyzed, CCHA showed better efficiency than CCHB. No allergic reactions or any toxic effects were observed in mice treated with CCHA, sustaining its potential therapeutic use. Our study supports that CCHA subunit accounts for the most important features involved in the immunogenicity of CCH, such as better hydrophilicity and higher content of carbohydrates.

  1. Chemical and biochemical properties of Araucaria angustifolia (Bert. Ktze. forest soils in the state of São Paulo

    Directory of Open Access Journals (Sweden)

    Fernanda de Carvalho

    2012-08-01

    Full Text Available Araucaria angustifolia, commonly named Araucaria, is a Brazilian native species that is intensively exploited due to its timber quality. Therefore, Araucaria is on the list of species threatened by extinction. Despite the importance of soil for forest production, little is known about the soil properties of the highly fragmented Araucaria forests. This study was designed to investigate the use of chemical and biological properties as indicators of conservation and anthropogenic disturbance of Araucaria forests in different sampling periods. The research was carried out in two State parks of São Paulo: Parque Estadual Turístico do Alto do Ribeira and Parque Estadual de Campos de Jordão. The biochemical properties carbon and nitrogen in microbial biomass (MB-C and MB-N, basal respiration (BR, the metabolic quotient (qCO2 and the following enzyme activities: β-glucosidase, urease, and fluorescein diacetate hydrolysis (FDA were evaluated. The sampling period (dry or rainy season influenced the results of mainly MB-C, MB-N, BR, and qCO2. The chemical and biochemical properties, except K content, were sensitive indicators of differences in the conservation and anthropogenic disturbance stages of Araucaria forests. Although these forests differ in biochemical and chemical properties, they are efficient in energy use and conservation, which is shown by their low qCO2, suggesting an advanced stage of succession.

  2. Soya bean Gα proteins with distinct biochemical properties exhibit differential ability to complement Saccharomyces cerevisiae gpa1 mutant.

    Science.gov (United States)

    Roy Choudhury, Swarup; Wang, Yuqi; Pandey, Sona

    2014-07-01

    Signalling pathways mediated by heterotrimeric G-proteins are common to all eukaryotes. Plants have a limited number of each of the G-protein subunits, with the most elaborate G-protein network discovered so far in soya bean (Glycine max, also known as soybean) which has four Gα, four Gβ and ten Gγ proteins. Biochemical characterization of Gα proteins from plants suggests significant variation in their properties compared with the well-characterized non-plant proteins. Furthermore, the four soya bean Gα (GmGα) proteins exhibit distinct biochemical activities among themselves, but the extent to which such biochemical differences contribute to their in vivo function is also not known. We used the yeast gpa1 mutant which displays constitutive signalling and growth arrest in the pheromone-response pathway as an in vivo model to evaluate the effect of distinct biochemical activities of GmGα proteins. We showed that specific GmGα proteins can be activated during pheromone-dependent receptor-mediated signalling in yeast and they display different strengths towards complementation of yeast gpa1 phenotypes. We also identified amino acids that are responsible for differential complementation abilities of specific Gα proteins. These data establish that specific plant Gα proteins are functional in the receptor-mediated pheromone-response pathway in yeast and that the subtle biochemical differences in their activity are physiologically relevant.

  3. Properties of electronic emissions of semiconductors III-IV in a status of negative electron affinity

    International Nuclear Information System (INIS)

    Piaget, Claude

    1977-01-01

    This research thesis reports the use of various properties (electron emission, photo emission, secondary electron emission) to highlight the relationships between various solid properties (optical, electronic, structural properties), surfaces (clean or covered with adsorbates such as caesium and oxygen) and emission properties (quantum efficiency, energy distribution, and so on). The first part addresses applications, performance, physical properties and technological processes, and also problems related to the physics and chemistry of surfaces and adsorption layers. The second part reports a study of the main electron transport properties in emitters displaying a negative electron affinity, for example GaP. Some aspects of electron excitation by ultra-violet radiations and high energy electrons are studied from UV photo-emission properties and secondary electron emission. Then GaAs and similar pseudo-binary compounds are studied

  4. Electronic processes in organic electronics bridging nanostructure, electronic states and device properties

    CERN Document Server

    Kudo, Kazuhiro; Nakayama, Takashi; Ueno, Nobuo

    2015-01-01

    The book covers a variety of studies of organic semiconductors, from fundamental electronic states to device applications, including theoretical studies. Furthermore, innovative experimental techniques, e.g., ultrahigh sensitivity photoelectron spectroscopy, photoelectron yield spectroscopy, spin-resolved scanning tunneling microscopy (STM), and a material processing method with optical-vortex and polarization-vortex lasers, are introduced. As this book is intended to serve as a textbook for a graduate level course or as reference material for researchers in organic electronics and nanoscience from electronic states, fundamental science that is necessary to understand the research is described. It does not duplicate the books already written on organic electronics, but focuses mainly on electronic properties that arise from the nature of organic semiconductors (molecular solids). The new experimental methods introduced in this book are applicable to various materials (e.g., metals, inorganic and organic mater...

  5. Extraordinary electronic properties in uncommon structure types

    Science.gov (United States)

    Ali, Mazhar Nawaz

    In this thesis I present the results of explorations into several uncommon structure types. In Chapter 1 I go through the underlying idea of how we search for new compounds with exotic properties in solid state chemistry. The ideas of exploring uncommon structure types, building up from the simple to the complex, using chemical intuition and thinking by analogy are discussed. Also, the history and basic concepts of superconductivity, Dirac semimetals, and magnetoresistance are briefly reviewed. In chapter 2, the 1s-InTaS2 structural family is introduced along with the discovery of a new member of the family, Ag0:79VS2; the synthesis, structure, and physical properties of two different polymorphs of the material are detailed. Also in this chapter, we report the observation of superconductivity in another 1s structure, PbTaSe2. This material is especially interesting due to it being very heavy (resulting in very strong spin orbit coulping (SOC)), layered, and noncentrosymmetric. Electronic structure calculations reveal the presence of a bulk 3D Dirac cone (very similar to graphene) that is gapped by SOC originating from the hexagonal Pb layer. In Chapter 3 we show the re-investigation of the crystal structure of the 3D Dirac semimetal, Cd3As2. It is found to be centrosymmetric, rather than noncentrosymmetric, and as such all bands are spin degenerate and there is a 4-fold degenerate bulk Dirac point at the Fermi level, making Cd3As2 a 3D electronic analog to graphene. Also, for the first time, scanning tunneling microscopy experiments identify a 2x2 surface reconstruction in what we identify as the (112) cleavage plane of single crystals; needle crystals grow with a [110] long axis direction. Lastly, in chapter 4 we report the discovery of "titanic" (sadly dubbed ⪉rge, nonsaturating" by Nature editors and given the acronym XMR) magnetoresistance (MR) in the non-magnetic, noncentrosymmetric, layered transition metal dichalcogenide WTe2; over 13 million% at 0.53 K in

  6. Electronic properties of superlattices on quantum rings.

    Science.gov (United States)

    da Costa, D R; Chaves, A; Ferreira, W P; Farias, G A; Ferreira, R

    2017-04-26

    We present a theoretical study of the one-electron states of a semiconductor-made quantum ring (QR) containing a series of piecewise-constant wells and barriers distributed along the ring circumference. The single quantum well and the superlattice cases are considered in detail. We also investigate how such confining potentials affect the Aharonov-Bohm like oscillations of the energy spectrum and current in the presence of a magnetic field. The model is simple enough so as to allow obtaining various analytical or quasi-analytical results. We show that the well-in-a-ring structure presents enhanced localization features, as well as specific geometrical resonances in its above-barrier spectrum. We stress that the superlattice-in-a-ring structure allows giving a physical meaning to the often used but usually artificial Born-von-Karman periodic conditions, and discuss in detail the formation of energy minibands and minigaps for the circumferential motion, as well as several properties of the superlattice eigenstates in the presence of the magnetic field. We obtain that the Aharonov-Bohm oscillations of below-barrier miniband states are reinforced, owing to the important tunnel coupling between neighbour wells of the superlattice, which permits the electron to move in the ring. Additionally, we analysis a superlattice-like structure made of a regular distribution of ionized impurities placed around the QR, a system that may implement the superlattice in a ring idea. Finally, we consider several random disorder models, in order to study roughness disorder and to tackle the robustness of some results against deviations from the ideally nanostructured ring system.

  7. Fruit development, pigmentation and biochemical properties of wax apple as affected by localized Application of GA3 under field conditions

    OpenAIRE

    Khandaker, Mohammad Moneruzzaman; Boyce, Amru Nasrulhaq; Osman, Normaniza; Golam, Faruq; Rahman, M. Motior; Sofian-Azirun, M.

    2013-01-01

    This study investigated the effects of gibberellin (GA3) on the fruit development, pigmentation and biochemical properties of wax apple. The wax apple trees were rubbing treated with 0, 20, 50 and 100 mgGA3/l under field conditions. The localized application (rubbing) of 50 mg GA3/l significantly increased the fruit set, fruit length and diameter, color development, weight and yieldcompared to the control. In addition, GA3 treatments significantly reduced the fruit drop. With regard to the fr...

  8. Electronic properties of high Tc superconductors

    International Nuclear Information System (INIS)

    Rojo, A.G.

    1989-01-01

    Using analytical and numerical methods, the electronic properties of the copper-oxygen plane in the normal phase of high Tc superconductors are described. Using the slave-boson technique in the saddle point, a theory of the metal insulator transition which generalizes the notions of a Mott insulator to the case of more than a single band for those planes is presented. A phase-diagram is obtained in the parameter space and effective masses, optical gaps and metallization are calculated as a function of the number of carriers. Based on the experimental evidence, the theory permits classification of superconducting compounds as charge transfer insulators in the stoichiometric case. The insulator state is characterized by a non-zero optical gap and a divergent effective mass which corresponds to the breakage of a Fermi-liquid scheme. The results obtained are applicable to metal-transition-oxides whose behaviour has been traditionally controversial and it is concluded that it is necessary to broaden the meaning of a Mott insulator to the case of more than a single band to better understand them. Based on the ideas of group renormalization in a real space, a lattice approximation is presented, which allows: a) To complement the treatment of slave-bosons in phase diagrams and optical gaps; b) Identification of an attraction mechanism between carriers originating from purely repulsive interactions. Numerical calculations in small clusters show the existence of a pairing mechanism showing a superconducting instability from a charge transfer insulator. (Author) [es

  9. The impact of atrazine on several biochemical properties of chernozem soil

    Directory of Open Access Journals (Sweden)

    LJ. RADIVOJEVIC

    2008-10-01

    Full Text Available The impact of the pesticide atrazine on biochemical processes in soil was investigated. Atrazine loadings of 8.0, 40.0 and 80.0 mg/kg soil were laboratory tested in an experiment set up on a clay loam soil. Dehydrogenase activity, change in biomass carbon, soil respiration and metabolic coefficient were examined. The samples were collected for analysis 1, 7, 14, 21, 30 and 60 days after atrazine application. The acquired data indicated that the effect of atrazine on the biochemical activity of the soil depended on its application rate and duration of activity, and the effect was either stimulating or inhibiting. However, the detected changes were found to be transient, indicating that there is no real risk of the compound disrupting the balance of biochemical processes in soil.

  10. Identification and Biochemical Properties of Two New Acetylcholinesterases in the Pond Wolf Spider (Pardosa pseudoannulata.

    Directory of Open Access Journals (Sweden)

    Xiangkun Meng

    Full Text Available Acetylcholinesterase (AChE, an important neurotransmitter hydrolase in both invertebrates and vertebrates, is targeted by organophosphorus and carbamate insecticides. In this study, two new AChEs were identified in the pond wolf spider Pardosa pseudoannulata, an important predatory natural enemy of several insect pests. In total, four AChEs were found in P. pseudoannulata (including two AChEs previously identified in our laboratory. The new putative AChEs PpAChE3 and PpAChE4 contain most of the common features of the AChE family, including cysteine residues, choline binding sites, the conserved sequence 'FGESAG' and conserved aromatic residues but with a catalytic triad of 'SDH' rather than 'SEH'. Recombinant enzymes expressed in Sf9 cells showed significant differences in biochemical properties compared to other AChEs, such as the optimal pH, substrate specificity, and catalytic efficiency. Among three test substrates, PpAChE1, PpAChE3 and PpAChE4 showed the highest catalytic efficiency (Vmax/KM for ATC (acetylthiocholine iodide, with PpAChE3 exhibiting a clear preference for ATC based on the VmaxATC/VmaxBTC ratio. In addition, the four PpAChEs were more sensitive to the AChE-specific inhibitor BW284C51, which acts against ATC hydrolysis, than to the BChE-specific inhibitor ISO-OMPA, which acts against BTC hydrolysis, with at least a 8.5-fold difference in IC50 values for each PpAChE. PpAChE3, PpAChE4, and PpAChE1 were more sensitive than PpAChE2 to the tested Carb insecticides, and PpAChE3 was more sensitive than the other three AChEs to the tested OP insecticides. Based on all the results, two new functional AChEs were identified from P. pseudoannulata. The differences in AChE sequence between this spider and insects enrich our knowledge of invertebrate AChE diversity, and our findings will be helpful for understanding the selectivity of insecticides between insects and natural enemy spiders.

  11. Electron impact phenomena and the properties of gaseous ions

    CERN Document Server

    Field, F H; Massey, H S W; Brueckner, Keith A

    1970-01-01

    Electron Impact Phenomena and the Properties of Gaseous Ions, Revised Edition deals with data pertaining to electron impact and to molecular gaseous ionic phenomena. This book discusses electron impact phenomena in gases at low pressure that involve low-energy electrons, which result in ion formation. The text also describes the use of mass spectrometers in electron impact studies and the degree of accuracy obtained when measuring electron impact energies. This book also reviews relatively low speed electrons and the transitions that result in the ionization of the atomic system. This text the

  12. Extension of a biochemical model for the generalized stoichiometry of electron transport limited C3 photosynthesis

    NARCIS (Netherlands)

    Yin, X.; Oijen, van M.; Schapendonk, A.H.C.M.

    2004-01-01

    The widely used steady-state model of Farquhar et al. (Planta 149: 78-90, 1980) for C-3 photosynthesis was developed on the basis of linear whole-chain (non-cyclic) electron transport. In this model, calculation of the RuBP-regeneration limited CO2-assimilation rate depends on whether it is

  13. Valence electronic properties of porphyrin derivatives.

    Science.gov (United States)

    Stenuit, G; Castellarin-Cudia, C; Plekan, O; Feyer, V; Prince, K C; Goldoni, A; Umari, P

    2010-09-28

    We present a combined experimental and theoretical investigation of the valence electronic structure of porphyrin-derived molecules. The valence photoemission spectra of the free-base tetraphenylporphyrin and of the octaethylporphyrin molecule were measured using synchrotron radiation and compared with theoretical spectra calculated using the GW method and the density-functional method within the generalized gradient approximation. Only the GW results could reproduce the experimental data. We found that the contribution to the orbital energies due to electronic correlations has the same linear behavior in both molecules, with larger deviations in the vicinity of the HOMO level. This shows the importance of adequate treatment of electronic correlations in these organic systems.

  14. Biochemical studies on antibiotic production from Streptomyces sp.: Taxonomy, fermentation, isolation and biological properties

    OpenAIRE

    Houssam M. Atta

    2015-01-01

    Tunicamycin is a nucleotide antibiotic which was isolated from the fermentation broth of a Streptomyces strain No. T-4. According to the morphological, cultural, physiological and biochemical characteristics, and 16S rDNA sequence analysis, strain T-4 was identified as Streptomyces torulosus. It is active in vitro against some microbial pathogenic viz: Staphylococcus aureus, NCTC 7447; Micrococcus lutea, ATCC 9341; Bacillus subtilis, NCTC 10400; B. pumilus, NCTC; Klebsiella pneumonia, NCIMB 9...

  15. Soil biochemical properties and microbial resilience in agroforestry systems: effects on wheat growth under controlled drought and flooding conditions.

    Science.gov (United States)

    Rivest, David; Lorente, Miren; Olivier, Alain; Messier, Christian

    2013-10-01

    Agroforestry is increasingly viewed as an effective means of maintaining or even increasing crop and tree productivity under climate change while promoting other ecosystem functions and services. This study focused on soil biochemical properties and resilience following disturbance within agroforestry and conventional agricultural systems and aimed to determine whether soil differences in terms of these biochemical properties and resilience would subsequently affect crop productivity under extreme soil water conditions. Two research sites that had been established on agricultural land were selected for this study. The first site included an 18-year-old windbreak, while the second site consisted in an 8-year-old tree-based intercropping system. In each site, soil samples were used for the determination of soil nutrient availability, microbial dynamics and microbial resilience to different wetting-drying perturbations and for a greenhouse pot experiment with wheat. Drying and flooding were selected as water stress treatments and compared to a control. These treatments were initiated at the beginning of the wheat anthesis period and maintained over 10 days. Trees contributed to increase soil nutrient pools, as evidenced by the higher extractable-P (both sites), and the higher total N and mineralizable N (tree-based intercropping site) found in the agroforestry compared to the conventional agricultural system. Metabolic quotient (qCO2) was lower in the agroforestry than in the conventional agricultural system, suggesting higher microbial substrate use efficiency in agroforestry systems. Microbial resilience was higher in the agroforestry soils compared to soils from the conventional agricultural system (windbreak site only). At the windbreak site, wheat growing in soils from agroforestry system exhibited higher aboveground biomass and number of grains per spike than in conventional agricultural system soils in the three water stress treatments. At the tree

  16. The electronic properties of mixed metal oxides

    International Nuclear Information System (INIS)

    Cussen, E.J.

    1999-01-01

    The properties of Fe and Mn in a variety of perovskite-related crystal structures have been studied by X-ray and neutron diffraction, magnetometry, high resolution electron microscopy and Moessbauer spectroscopy. The structure of Sr 2 FeTaO 6 is of the GdFeO 3 type with a disordered arrangement of Fe and Ta over the octahedrally coordinated sites in contrast to the partial ordering, 0.795(6)Fe/0.205(6)Sb, observed in Sr 2 FeSbO 6 . Sr 2 FeTaO 6 is a spin glass below 23 K whereas Sr 2 FeSbO 6 forms a type I antiferromagnetically ordered phase below T N = 37(2) K with an ordered moment of 3.06(9) μ B Fe -1 at 1.5 K on the Fe-rich site. Susceptibility measurements in the magnetically dilute series Sr 2 Fe 1-x Ga x TaO 6 indicate that magnetic ordering in these Fe 3+ perovskites is partially controlled by next-nearest-neighbour superexchange. A new 15R perovskite structure containing face-sharing dimers of octahedra linked to one another by vertices or bridging octahedra has been - found for the composition SrMn 0.915(5) Fe 0.085(5) O 2.979(3) . The Mn 4+ cations align antiferromagnetically below T N = 220(5) K showing an ordered moment of 2.25(3) μ B at 3 K. The Fe cations remain disordered to 3 K. This composition forms a 6-layered hexagonal perovskite in the temperature range 1200 6 Mn 4 MO 15 (M = Cu, Zn) form pseudo 1-dimensional phases related to Ba 6 Ni 5 O 15 . The trigonal prismatic sites in this structure are preferentially occupied by Zn/Cu; the latter is displaced from the centre of the trigonal prism to give pseudo square-planar coordination. At 1.7 K antiferromagnetic superexchange within a highly frustrated crystal structure leads to a magnetic structure exhibiting rotation of 120 deg. between spins in neighbouring chains. The magnetic moments refined to 0.7(1) and 0.6(1) μ B per octahedral site in the Cu and Zn compounds respectively. The magnetic susceptibilities have been rationalised in terms of 1-dimensional ordering of the octahedrally

  17. Correlation of CVD Diamond Electron Emission with Film Properties

    Science.gov (United States)

    Bozeman, S. P.; Baumann, P. K.; Ward, B. L.; Nemanich, R. J.; Dreifus, D. L.

    1996-03-01

    Electron field emission from metals is affected by surface morphology and the properties of any dielectric coating. Recent results have demonstrated low field electron emission from p-type diamond, and photoemission measurements have identified surface treatments that result in a negative electron affinity (NEA). In this study, the field emission from diamond is correlated with surface treatment, surface roughness, and film properties (doping and defects). Electron emission measurements are reported on diamond films synthesized by plasma CVD. Ultraviolet photoemission spectroscopy indicates that the CVD films exhibit a NEA after exposure to hydrogen plasma. Field emission current-voltage measurements indicate "threshold voltages" ranging from approximately 20 to 100 V/micron.

  18. Effect of electron beam on the properties of electron-acoustic rogue waves

    Science.gov (United States)

    El-Shewy, E. K.; Elwakil, S. A.; El-Hanbaly, A. M.; Kassem, A. I.

    2015-04-01

    The properties of nonlinear electron-acoustic rogue waves have been investigated in an unmagnetized collisionless four-component plasma system consisting of a cold electron fluid, Maxwellian hot electrons, an electron beam and stationary ions. It is found that the basic set of fluid equations is reduced to a nonlinear Schrodinger equation. The dependence of rogue wave profiles and the associated electric field on the carrier wave number, normalized density of hot electron and electron beam, relative cold electron temperature and relative beam temperature are discussed. The results of the present investigation may be applicable in auroral zone plasma.

  19. Spectrum properties of electrons in solids

    International Nuclear Information System (INIS)

    Avron, J.

    1975-11-01

    The electron spectra in the one-particle Bloch model is discussed. The presence of hamiltonian bands is proved, especially for the Dirac and Schrodinger hamiltonians. The analyticity of the quasimomentum k is described as well as the stability of the bands in singular disturbances. (B.G.)

  20. Size-dependent electronic properties of metal nanostructures

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Size-dependent electronic properties of metal nanostructures. G.U. Kulkarni. Chemistry and Physics of Materials Unit. Jawaharlal Nehru Centre for Advanced Scientific Research. Bangalore, India. kulkarni@jncasr.ac.in.

  1. Manganites in Perovskite Superlattices: Structural and Electronic Properties

    KAUST Repository

    Jiwuer, Jilili

    2016-01-01

    Perovskite manganites are widely investigated compounds due to the discovery of the colossal magnetoresistance effect in 1994. They have a broad range of structural, electronic, magnetic properties and potential device applications in sensors

  2. Density functional study of : Electronic and optical properties

    Indian Academy of Sciences (India)

    K C Bhamu

    3Department of Physics, Swami Keshvanand Insitute of Technology, Management and Gramothan, ... Published online 20 June 2017. Abstract. This paper focusses on the electronic and optical properties of scandium-based silver delafossite.

  3. Comparison of clot lysis activity and biochemical properties of originator tenecteplase (Metalyse® with those of an alleged biosimilar

    Directory of Open Access Journals (Sweden)

    Werner eKliche

    2014-02-01

    Full Text Available The bioengineered tissue plasminogen activator tenecteplase is an important treatment modality of acute myocardial infarction recommended by international guidelines. Following introduction of originator tenecteplase (brand names Metalyse® and TNKase®, a ‘biosimilar’ tenecteplase became available for commercial use in India under the brand name Elaxim® in the absence of Indian biosimilar guidelines which came into force from September 15th, 2012. Based on a report of biochemical and fibrinolytical differences between Metalyse and Elaxim, we have systematically compared them in a range of routine quality testing assays. As compared to Metalyse, Elaxim exhibited less clot lysis activity and contained less of the two-chain form of tenecteplase. Even upon full in vitro conversion to the two-chain form Elaxim exhibited less clot lysis activity. This was linked to differences in sialic acid content and glycosylation pattern with Elaxim exhibiting less bi- and more tetra-antennary glycosylation, leading to different charge heterogeneity profile. Regarding purity, Elaxim contained more tenecteplase aggregates and, in contrast to Metalyse, considerable amounts of Chinese hamster ovary cell protein. Taken together these data demonstrate that Metalyse and Elaxim differ considerably in clot lysis activity and biochemical properties. These data question whether Elaxim indeed can be considered a ‘biosimilar’ of Metalyse, i.e. whether and to which extent the clinical efficacy and safety properties of Metalyse can be extrapolated to Elaxim in the absence of comparative clinical data.

  4. Structure, Electronic and Nonlinear Optical Properties of Furyloxazoles and Thienyloxazoles

    International Nuclear Information System (INIS)

    Dagli, Ozlem; Gok, Rabia; Bahat, Mehmet; Ozbay, Akif

    2016-01-01

    Geometry optimization, electronic and nonlinear optical properties of isomers of furyloxazole and thienyloxazole molecules are carried out at the B3LYP/6-311++G(2d,p) level. The conformational analysis of 12 compounds have been studied as a function of torsional angle between rings. Electronic and NLO properties such as dipole moment, energy gap, polarizability and first hyperpolarizability were also calculated. (paper)

  5. The electronic properties of semiconductor quantum dots

    International Nuclear Information System (INIS)

    Barker, J.A.

    2000-10-01

    This work is an investigation into the electronic behaviour of semiconductor quantum dots, particularly self-assembled quantum dot arrays. Processor-efficient models are developed to describe the electronic structure of dots, deriving analytic formulae for the strain tensor, piezoelectric distribution and diffusion- induced evolution of the confinement potential, for dots of arbitrary initial shape and composition profile. These models are then applied to experimental data. Transitions due to individual quantum dots have a narrow linewidth as a result of their discrete density of states. By contrast, quantum dot arrays exhibit inhomogeneous broadening which is generally attributed to size variations between the individual dots in the ensemble. Interpreting the results of double resonance spectroscopy, it is seen that variation in the indium composition of the nominally InAs dots is also present. This result also explains the otherwise confusing relationship between the spread in the ground-state and excited-state transition energies. Careful analysis shows that, in addition to the variations in size and composition, some other as yet unidentified broadening mechanism must also be present. The influence of rapid thermal annealing on dot electronic structure is also considered, finding that the experimentally observed blue-shift and narrowing of the photoluminescence linewidth may both be explained in terms of normal In/Ga interdiffusion. InAs/GaAs self-assembled quantum dots are commonly assumed to have a pyramidal geometry, so that we would expect the energy separation of the ground-state electron and hole levels in the dot to be largest at a positive applied field. This should also be the case for any dot of uniform composition whose shape tapers inwards from base to top, counter to the results of experimental Stark-shift spectroscopy which show a peak transition energy at a negative applied field. It is demonstrated that this inversion of the ground state

  6. influence of the substitution on the electronic properties of perylene ...

    African Journals Online (AJOL)

    Preferred Customer

    The higher performance found in single crystal OFETs compared to thin-film. OFETs is related to the high ... Influence of substitution on electronic properties of perylene-3,4:9,10-bis(dicarboximides). Bull. Chem. Soc. .... be good n-type materials for OFETs due to the efficient electron injection from common gold electrode, ca.

  7. ELECTRONIC PUBLISHING AND THE EVOLVING INTERNATIONAL INTELLECTUAL PROPERTY REGIME

    OpenAIRE

    D. Langenberg

    2000-01-01

    As we leave the Industrial Age behind us and move into the Information Age, the transition from “bricks and mortar” commerce to electronic commerce and from paper to electronic publishing pose major challenges for international intellectual property regimes. Electronic commerce has taken off. Whatever concerns about consumer acceptance there were five years ago have given way to “click and mortar” business models where e-commerce has an established role complementing traditional commerce. The...

  8. Impact of radiation treatment on chemical, biochemical and sensory properties, and microbiological quality of mackerel

    Science.gov (United States)

    Pinter, Nino; Maltar-Strmečki, Nadica; Kozačinski, Lidija; Njari, Bela; Cvrtila Fleck, Željka

    2015-12-01

    The effect of gamma radiation on shelf-life of mackerel (Scomber scombrus) was studied. Changes in raw fish stored at 4 °C were investigated simultaneously, by performing sensory evaluation, chemical analysis (pH value and NH3 concentration), and biochemical analyses of histamine concentration and microbiological quality. Analyses showed that preservation by gamma irradiation prolonged the freshness and sustainability without any unintended sensory changes. Furthermore, increasing the dose during the 10 days of storage considerably reduced the concentration of histamine, but only slightly reduced the concentration of ammonia (NH3). Bacterial examinations showed that gamma radiation decreased the total number of bacteria. Our results indicated that the shelf-life of mackerel stored at 4 °C can be prolonged by irradiation with a dose of 3 kGy.

  9. Electron spin resonance dosimetric properties of bone

    International Nuclear Information System (INIS)

    Caracelli, I.; Terrile, M.C.; Mascarenhas, S.

    1986-01-01

    The characteristics of electron spin resonance (ESR) dosimetry using bovine bone samples are described. The number of paramagnetic centers created by gamma radiation in the inorganic bone matrix was measured as a function of absorbed dose. The minimum detectable dose was 0.5 Gy for 60Co gamma rays. The response was linear up to the maximum dose studied (30 Gy) and independent of dose rate up to the maximum dose rate used (1.67 Gy min-1). For different bone samples the reproducibility was 5%. This method may be valuable for nuclear accident dosimetry

  10. Two phosphodiesterases from Ustilago maydis share structural and biochemical properties with non-fungal phosphodiesterases

    Directory of Open Access Journals (Sweden)

    Charu eAgarwal

    2010-11-01

    Full Text Available The dependence of Protein Kinase A (PKA activity on cAMP levels is an important facet of the dimorphic switch between budding and filamentous growth as well as for pathogenicity in some fungi. To better understand these processes in the pathogenic fungus Ustilago maydis, we characterized the structure and biochemical functions of two phosphodiesterase (PDE genes. Phosphodiesterases are enzymes involved in cAMP turnover and thus, contribute to the regulation of the cAMP-PKA signaling pathway. Two predicted homologues of PDEs were identified in the genome of U. maydis and hypothesized to be involved in cAMP turnover, thus regulating activity of the PKA catalytic subunit. Both umpde1 and umpde2 genes contain domains associated with phosphodiesterase activity predicted by InterPro analysis. Biochemical characterization of recombinantly produced UmPde1 (U. maydis Phosphodiesterase I and UmPde2 demonstrated that both enzymes have phosphodiesterase activity in vitro, yet neither was inhibited by the phosphodiesterase inhibitor IBMX. Moreover, UmPde1 is specific for cAMP, while UmPde2 has broader substrate specificity, utilizing cAMP and cGMP as substrates. In addition, UmPde2 was also found to have nucleotide phosphatase activity that was higher with GMP compared to AMP. These results demonstrate that UmPde1 is a bona fide phosphodiesterase, while UmPde2 has more general activity as a cyclic nucleotide phosphodiesterase and/or GMP/AMP phosphatase. Thus, UmPde1 and UmPde2 likely have important roles in cell morphology and development and share some characteristics with a variety of non-fungal phosphodiesterases.

  11. Electronic and magnetic properties of ultrathin rhodium nanowires

    CERN Document Server

    Wang Bao Lin; Ren-Yun; Sun Hou Qian; Chen Xiao Shuang; Zhao Ji Jun

    2003-01-01

    The structures of ultrathin rhodium nanowires are studied using empirical molecular dynamics simulations with a genetic algorithm. Helical multishell cylindrical and pentagonal packing structures are found. The electronic and magnetic properties of the rhodium nanowires are calculated using an spd tight-binding Hamiltonian in the unrestricted Hartree-Fock approximation. The average magnetic moment and electronic density of states are obtained. Our results indicate that the electronic and magnetic properties of the rhodium nanowires depend not only on the size of the wire but also on the atomic structure. In particular, centred pentagonal and hexagonal structures can be unusually ferromagnetic.

  12. Electronic and ground state properties of ThTe

    Energy Technology Data Exchange (ETDEWEB)

    Bhardwaj, Purvee, E-mail: purveebhardwaj@gmail.com; Singh, Sadhna, E-mail: drsadhna100@gmail.com [High Pressure Research Lab. Department of Physics Barkatullah University, Bhopal (MP) 462026 (India)

    2016-05-06

    The electronic properties of ThTe in cesium chloride (CsCl, B2) structure are investigated in the present paper. To study the ground state properties of thorium chalcogenide, the first principle calculations have been calculated. The bulk properties, including lattice constant, bulk modulus and its pressure derivative are obtained. The calculated equilibrium structural parameters are in good agreement with the available experimental and theoretical results.

  13. Variable electronic properties of lateral phosphorene-graphene heterostructures.

    Science.gov (United States)

    Tian, Xiaoqing; Liu, Lin; Du, Yu; Gu, Juan; Xu, Jian-Bin; Yakobson, Boris I

    2015-12-21

    Phosphorene and graphene have a tiny lattice mismatch along the armchair direction, which can result in an atomically sharp in-plane interface. The electronic properties of the lateral heterostructures of phosphorene/graphene are investigated by the first-principles method. Here, we demonstrate that the electronic properties of this type of heterostructure can be highly tunable by the quantum size effects and the externally applied electric field (Eext). At strong Eext, Dirac Fermions can be developed with Fermi velocities around one order smaller than that of graphene. Undoped and hydrogen doped configurations demonstrate three drastically different electronic phases, which reveal the strongly tunable potential of this type of heterostructure. Graphene is a naturally better electrode for phosphorene. The transport properties of two-probe devices of graphene/phosphorene/graphene exhibit tunnelling transport characteristics. Given these results, it is expected that in-plane heterostructures of phosphorene/graphene will present abundant opportunities for applications in optoelectronic and electronic devices.

  14. Electronic structure and properties of superheavy elements

    International Nuclear Information System (INIS)

    Pershina, V.

    2015-01-01

    Spectacular developments in the relativistic quantum theory and computational algorithms in the last few decades allowed for accurate calculations of properties of the superheavy elements (SHE) and their compounds. Often conducted in a close link to the experimental research, these investigations helped predict and interpret an outcome of sophisticated and expensive experiments with single atoms. Most of the works, particularly those related to the experimental studies, are overviewed in this publication. The role of relativistic effects being of paramount importance for the heaviest elements is elucidated.

  15. Atomic structures and electronic properties of phosphorene grain boundaries

    International Nuclear Information System (INIS)

    Guo, Yu; Zhou, Si; Bai, Yizhen; Zhao, Jijun; Zhang, Junfeng

    2016-01-01

    Grain boundary (GB) is one main type of defects in two-dimensional (2D) crystals, and has significant impact on the physical properties of 2D materials. Phosphorene, a recently synthesized 2D semiconductor, possesses a puckered honeycomb lattice and outstanding electronic properties. It is very interesting to know the possible GBs present in this novel material, and how their properties differ from those in the other 2D materials. Based on first-principles calculations, we explore the atomic structure, thermodynamic stability, and electronic properties of phosphorene GBs. A total of 19 GBs are predicted and found to be energetically stable with formation energies much lower than those in graphene. These GBs do not severely affect the electronic properties of phosphorene: the band gap of perfect phosphorene is preserved, and the electron mobilities are only moderately reduced in these defective systems. Our theoretical results provide vital guidance for experimental tailoring the electronic properties of phosphorene as well as the device applications using phosphorene materials. (paper)

  16. Investigation of electronic transport properties of some liquid transition metals

    Science.gov (United States)

    Patel, H. P.; Sonvane, Y. A.; Thakor, P. B.

    2018-04-01

    We investigated electronic transport properties of some liquid transition metals (V, Cr, Mn, Fe, Co and Pt) using Ziman formalism. Our parameter free model potential which is realized on ionic and atomic radius has been incorporated with the Hard Sphere Yukawa (HSY) reference system to study the electronic transport properties like electrical resistivity (ρ), thermal conductivity (σ) and thermo electrical power (Q). The screening effect on aforesaid properties has been studied by using different screening functions. The correlations of our results and others data with in addition experimental values are profoundly promising to the researchers working in this field. Also, we conclude that our newly constructed parameter free model potential is capable to explain the aforesaid electronic transport properties.

  17. Electrical properties of gallium arsenide irradiated with electrons and neutrons

    International Nuclear Information System (INIS)

    Kol'chenko, T.I.; Lomako, V.M.

    1975-01-01

    A study was made of changes in the electrical properties of GaAs doped with Te, S, Se, Si, Ge, Sn (n 0 approximately 10 16 -10 18 cm -3 ) and irradiated either with 2.5-28 MeV electrons or with fast reactor neutrons. An analysis of changes in the electron density indicated that the rate of carrier removal by electron bombardment was independent of the dopant but was governed by isolated radiation defects. The change in the mobility due to irradiation with 2.5-10 MeV electrons was also governed by isolated defects. When the electron energy was increased to 28 MeV the main contribution to the change in the mobility was made by defect clusters. In the neutron-irradiation case the changes in the carrier density and mobility were mainly due to defect clusters and the nature of changes in the electrical properties was again independent of the dopant

  18. Modular evolution of glutathione peroxidase genes in association with different biochemical properties of their encoded proteins in invertebrate animals

    Directory of Open Access Journals (Sweden)

    Zo Young-Gun

    2009-04-01

    Full Text Available Abstract Background Phospholipid hydroperoxide glutathione peroxidases (PHGPx, the most abundant isoforms of GPx families, interfere directly with hydroperoxidation of lipids. Biochemical properties of these proteins vary along with their donor organisms, which has complicated the phylogenetic classification of diverse PHGPx-like proteins. Despite efforts for comprehensive analyses, the evolutionary aspects of GPx genes in invertebrates remain largely unknown. Results We isolated GPx homologs via in silico screening of genomic and/or expressed sequence tag databases of eukaryotic organisms including protostomian species. Genes showing strong similarity to the mammalian PHGPx genes were commonly found in all genomes examined. GPx3- and GPx7-like genes were additionally detected from nematodes and platyhelminths, respectively. The overall distribution of the PHGPx-like proteins with different biochemical properties was biased across taxa; selenium- and glutathione (GSH-dependent proteins were exclusively detected in platyhelminth and deuterostomian species, whereas selenium-independent and thioredoxin (Trx-dependent enzymes were isolated in the other taxa. In comparison of genomic organization, the GSH-dependent PHGPx genes showed a conserved architectural pattern, while their Trx-dependent counterparts displayed complex exon-intron structures. A codon for the resolving Cys engaged in reductant binding was found to be substituted in a series of genes. Selection pressure to maintain the selenocysteine codon in GSH-dependent genes also appeared to be relaxed during their evolution. With the dichotomized fashion in genomic organizations, a highly polytomic topology of their phylogenetic trees implied that the GPx genes have multiple evolutionary intermediate forms. Conclusion Comparative analysis of invertebrate GPx genes provides informative evidence to support the modular pathways of GPx evolution, which have been accompanied with sporadic

  19. Electronic structure and optical properties of solid C60

    International Nuclear Information System (INIS)

    Mattesini, M.; Ahuja, R.; Sa, L.; Hugosson, H.W.; Johansson, B.; Eriksson, O.

    2009-01-01

    The electronic structure and the optical properties of face-centered-cubic C 60 have been investigated by using an all-electron full-potential method. Our ab initio results show that the imaginary dielectric function for high-energy values looks very similar to that of graphite, revealing close electronic structure similarities between the two systems. We have also identified the origin of different peaks in the dielectric function of fullerene by means of the calculated electronic density of states. The computed optical spectrum compares fairly well with the available experimental data for the Vis-UV absorption spectrum of solid C 60 .

  20. Possible Impact of Antioxidant Properties of Cocoa (Theobroma Cacao L.) Against Irradiation - Induced Some Biochemical Disorders in Rats

    International Nuclear Information System (INIS)

    Farag, M.F.S.; Darwish, M.M.

    2016-01-01

    Man is exposed to natural radiations either from cosmic or terrestrial origins. Furthermore, it is well known that the gamma irradiation of animals induce biochemical alterations which depend mostly on oxidative stress. This work aimed at evaluating the radioprotective efficiency of Cocoa (Theobroma cacao L.) against whole body γ-irradiation of rats. The virtue of cocoa aqueous extract (CAE) was given to rats at a dose of 1 g/ kg for 6 weeks to determine changes in hepatic marker enzymes, lipid profile and antioxidant status. The animals exposed to γ-rays exhibited a pronounced increment in serum aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP) and gamma glutamyl transpeptidase (γ GT), total cholesterol (TC), triglycerides (TG), low density lipoprotein cholesterol (LDL-C) and liver thiobarbituric acid reactive substance (TBARS). On the other hand, a significant decline was demonstrated in high density lipoprotein cholesterol (HDL-C). A decrease of hepatic reduced glutathione (GSH) content, superoxides dismutase (SOD) and catalase (CAT) activities was sustained. The CAE administered orally to rats has significantly modulated all the radiation-induced biochemical alterations. These findings revealed that cocoa would exert radio-protective properties

  1. Biochemical and structural properties of cyanases from Arabidopsis thaliana and Oryza sativa.

    Directory of Open Access Journals (Sweden)

    Dan Qian

    Full Text Available Cyanate is toxic to all organisms. Cyanase converts cyanate to CO₂ and NH₃ in a bicarbonate-dependent reaction. The biophysical functions and biochemical characteristics of plant cyanases are poorly studied, although it has been investigated in a variety of proteobacteria, cyanobacteria and fungi. In this study, we characterised plant cyanases from Arabidopsis thaliana and Oryza sativa (AtCYN and OsCYN. Prokaryotic-expressed AtCYN and OsCYN both showed cyanase activity in vitro. Temperature had a similar influence on the activity of both cyanases, but pH had a differential impact on AtCYN and OsCYN activity. Homology modelling provided models of monomers of AtCYN and OsCYN, and a coimmunoprecipitation assay and gel filtration indicated that AtCYN and OsCYN formed homodecamers. The analysis of single-residue mutants of AtCYN indicated that the conserved catalytic residues also contributed to the stability of the homodecamer. KCNO treatment inhibited Arabidopsis germination and early seedling growth. Plants containing AtCYN or OsCYN exhibited resistance to KCNO stress, which demonstrated that one role of cyanases in plants is detoxification. Transcription level of AtCYN was higher in the flower than in other organs of Arabidopsis. AtCYN transcription was not significantly affected by KCNO treatment in Arabidopsis, but was induced by salt stress. This research broadens our knowledge on plant detoxification of cyanate via cyanase.

  2. Biochemical studies on antibiotic production from Streptomyces sp.: Taxonomy, fermentation, isolation and biological properties

    Directory of Open Access Journals (Sweden)

    Houssam M. Atta

    2015-01-01

    Full Text Available Tunicamycin is a nucleotide antibiotic which was isolated from the fermentation broth of a Streptomyces strain No. T-4. According to the morphological, cultural, physiological and biochemical characteristics, and 16S rDNA sequence analysis, strain T-4 was identified as Streptomyces torulosus. It is active in vitro against some microbial pathogenic viz: Staphylococcus aureus, NCTC 7447; Micrococcus lutea, ATCC 9341; Bacillus subtilis, NCTC 10400; B. pumilus, NCTC; Klebsiella pneumonia, NCIMB 9111; Escherichia coli, NCTC 10416; Pseudomonas aeruginosa, ATCC 10145; Saccharomyces cerevisiae ATCC 9763; Candida albicans, IMRU 3669; Aspergillus flavus, IMI 111023; Aspergillus niger IMI 31276; Aspergillus fumigatus ATCC 16424; Fusarium oxysporum; Rhizoctonia solani; Alternaria alternata; Botrytis fabae and Penicillium chrysogenium. The production media were optimized for maximum yield of secondary metabolites. The metabolites were extracted using n-butanol (1:1, v/v at pH 7.0. The chemical structural analysis with UV, IR, and MS spectral analyses confirmed that the compound produced by Streptomyces torulosus, T-4 is tunicamycin antibiotic.

  3. Textural and biochemical properties of cobia (Rachycentron canadum) sashimi tenderised with the ultrasonic water bath.

    Science.gov (United States)

    Chang, Hung-Chia; Wong, Ren-Xian

    2012-06-01

    The present study investigated the tenderisation effects ultrasound processing (UT) on farmed cobia sashimi. Age-treated cobia trunk muscles (AT) were used as the control. The pH, total volatile base nitrogen, trimethylamine nitrogen, thiobarbituric acid reactive substances, ATP catabolism components, K 1 value, and texture were evaluated. The texture of AT sashimi reached the optimal firmness range with 8.53N at day 7. However, AT samples could not be served raw after day 7 because of their poor freshness indexes, including a TVBN value of 18.53g/100g, a TMAN value of 3.25mg/100g, and a TBARS value 0.983MDAmg/100g. Moreover, the K 1 value of AT sashimi was 20.21% at day 5. UT was employed to efficiently tenderise cobia sashimi with an initial firmness of 9.70-7.82N after 90min of treatment. The results of this study indicate that UT accelerates the biochemical reaction rate, as evidenced by the increases in the TVBN, TMAN, and TBARS contents; however, these values were very low. The results of this study could provide basic information for the development of a novel ultrasonic tenderisation technique in raw seafood designed for restaurants and consumers. Copyright © 2011 Elsevier Ltd. All rights reserved.

  4. Obtaining edaphic biostimulants/biofertilizers from sewage sludge using fermentative processes. Short-time effects on soil biochemical properties.

    Science.gov (United States)

    Rodríguez-Morgado, Bruno; Caballero, Pablo; Paneque, Patricia; Gómez, Isidoro; Parrado, Juan; Tejada, Manuel

    2017-10-28

    In this manuscript, we study the manufacture and effect on soils of different edaphic biostimulants/biofertilizers (BS) obtained from sewage sludge using Bacillus licheniformis as biological tool. These BS consist of different combinations of organic matter, bacteria and enzymes that were subjected to several treatments. These BS were applied in soil in order to observe their influence on the biochemical properties (enzymatic activities and ergosterol content). Dehydrogenase, urease, β-glucosidase, phosphatase activities and ergosterol content were measured at different incubation days. Only dehydrogenase activity and ergosterol content were significantly stimulated after the application of BS1 and BS4. Rest of the extracellular activities were not stimulated probably because B. licheniformis practically has digested all organic substrates during fermentation process.

  5. Long-term application of bioorganic fertilizers improved soil biochemical properties and microbial communities of an apple orchard soil

    Directory of Open Access Journals (Sweden)

    Wang Lei

    2016-11-01

    Full Text Available Soil biochemical properties and microbial communities are usually considered as important indicators of soil health because of their association with plant nutrition. In this study, we investigated the impact of long-term application of bioorganic fertilizer (BOF on soil biochemical properties and microbial communities in the apple orchard soil of the Loess Plateau. The experiment included three treatments: (1 control without fertilization (CK; (2 chemical fertilizer application (CF; and (3 bioorganic fertilizer application (BOF. The high throughput sequencing was used to examine the bacterial and fungal communities in apple orchard soil. The results showed that the BOF treatment significantly increased the apple yield during the experimental time (2009-2015. The application of BOF significantly increased the activities of catalase and invertase compared to those in CK and CF treatments. The high throughput sequencing data showed that the application of BOF changed the microbial community composition of all soil depths considered (0-20cm, 20-40cm, and 40-60cm, e.g., the relative abundance of bio-control bacteria (Xanthomonadales, Lysobacter, Pseudomonas and Bacillus, Proteobacteria, Bacteroidetes, Ohtaekwangia, Ilyonectria and Lecanicillium was increased while that of Acidobacteria, Chloroflexi, Gp4, Gp6 and Sphaerobacter was decreased. The increase in apple yield after the application of BOF might be due to increase in organic matter, total nitrogen and catalase and invertase activities of soil and change in the bacterial community composition by enriching Bacillus, Pseudomonas, Lysobacter and Ohtaekwangia. These results further enhance the understanding on how BOFs alter soil microbial community composition to stimulate soil productivity.

  6. Characterisation and biochemical properties of predominant lactic acid bacteria from fermenting cassava for selection as starter cultures.

    Science.gov (United States)

    Kostinek, M; Specht, I; Edward, V A; Pinto, C; Egounlety, M; Sossa, C; Mbugua, S; Dortu, C; Thonart, P; Taljaard, L; Mengu, M; Franz, C M A P; Holzapfel, W H

    2007-03-20

    A total of 375 lactic acid bacteria were isolated from fermenting cassava in South Africa, Benin, Kenya and Germany, and were characterised by phenotypic and genotypic tests. These could be divided into five main groups comprising strains of facultatively heterofermentative rods, obligately heterofermentative rods, heterofermentative cocci, homofermentative cocci and obligately homofermentative rods, in decreasing order of predominance. Most of the facultatively heterofermentative rods were identified by phenotypic tests as presumptive Lactobacillus plantarum-group strains, which also comprised the most predominant bacteria (54.4% of strains) isolated in the study. The next predominant group of lactic acid bacteria (14.1% of total isolates) consisted of obligately heterofermentative rods belonging either to the genus Lactobacillus or Weissella, followed by the heterofermentative cocci (13.9% of isolates) belonging to the genera Weissella or Leuconostoc. Homofermentative cocci were also isolated (13.3% of isolates). Biochemical properties such as production of alpha-amylase, beta-glucosidase, tannase, antimicrobials (presumptive bacteriocin and H(2)O(2)-production), acidification and fermentation of the indigestible sugars raffinose and stachyose, were evaluated in vitro for selection of potential starter strains. A total of 32 strains with one or more desirable biochemical properties were pre-selected and identified using rep-PCR fingerprinting in combination with 16S rRNA sequencing of representative rep-PCR cluster isolates. Of these strains, 18 were identified as L. plantarum, four as Lactobacillus pentosus, two each as Leuconostoc fallax, Weissella paramesenteroides and Lactobacillus fermentum, one each as Leuconostoc mesenteroides subsp. mesenteroides and Weissella cibaria, while two remained unidentified but could be assigned to the L. plantarum-group. These strains were further investigated for clonal relationships, using RAPD-PCR with three primers, and of

  7. Electronic transport properties of nanostructured MnSi-films

    Science.gov (United States)

    Schroeter, D.; Steinki, N.; Scarioni, A. Fernández; Schumacher, H. W.; Süllow, S.; Menzel, D.

    2018-05-01

    MnSi, which crystallizes in the cubic B20 structure, shows intriguing magnetic properties involving the existence of skyrmions in the magnetic phase diagram. Bulk MnSi has been intensively investigated and thoroughly characterized, in contrast to MnSi thin film, which exhibits widely varying properties in particular with respect to electronic transport. In this situation, we have set out to reinvestigate the transport properties in MnSi thin films by means of studying nanostructure samples. In particular, Hall geometry nanostructures were produced to determine the intrinsic transport properties.

  8. Biochemical Properties of Soluble and Bound Peroxidases from Artichoke Heads and Leaves

    Directory of Open Access Journals (Sweden)

    Angela Cardinali

    2009-01-01

    Full Text Available Soluble (SP, ionically bound (IBP and covalently bound (CBP peroxidases (POD from artichoke leaves and heads have been characterized for the main biochemical parameters. The three PODs, in both leaves and heads, showed the major apparent catalytic efficiency (vmax,app/Km,app towards ferulic acid, even though, in some cases, they showed higher affinity (Km,app for other substrates. In leaves, SP and IBP showed higher Km,app for ferulic and chlorogenic acids, and CBP for ferulic and caffeic acids. In heads, SP showed higher Km,app for chlorogenic acid, IBP for caffeic and ferulic acids, and CBP for ferulic acid. It was shown that pH optimum for PODs ranged between 5.0 and 6.0 in leaves. In heads, pH optimum for SP and IBP was 5.5, while CBP presented a very low activity in a wide pH range. All PODs showed high thermal stability but different ability to regenerate: the bound forms were more able to regenerate than the soluble one. The results obtained show that (i CBP from heads is able to work under very different cellular conditions, (ii all PODs, in both tissues, have a high apparent catalytic efficiency for ferulic acid, which could explain the effective involvement of POD in lignin biosynthesis, (iii in heads, high Km,app of SP for chlorogenic acid, particularly abundant in artichoke, could justify the possible involvement of PODs in browning mechanism, and (iv in heat-processed artichoke, the ability of PODs to regenerate could contribute to oxidation and loss of product quality.

  9. Biocompatibility of a novel cyanoacrylate based tissue adhesive: cytotoxicity and biochemical property evaluation.

    Directory of Open Access Journals (Sweden)

    Young Ju Lee

    Full Text Available Cyanoacrylate (CA is most widely used as a medical and commercial tissue adhesive because of easier wound closure, good cosmetic results and little discomfort. But, CA-based tissue adhesives have some limitations including the release of cytotoxic chemicals during biodegradation. In previous study, we made prepolymerized allyl 2-CA (PACA based tissue adhesive, resulting in longer chain structure. In this study, we investigated a biocompatibility of PACA as alternative tissue adhesive for medical application, comparing with that of Dermabond® as commercial tissue adhesive. The biocompatibility of PACA was evaluated for short-term (24 hr and long-term (3 and 7 days using conventional cytotoxicity (WST, neutral red, LIVE/DEAD and TUNEL assays, hematoxylin-eosin (H&E and Masson trichrome (MT staining. Besides we examined the biochemical changes in cells and DNA induced by PACA and Dermabond® utilizing Raman spectroscopy which could observe the denaturation and conformational changes in protein, as well as disintegration of the DNA/RNA by cell death. In particular, we analyzed Raman spectrum using the multivariate statistical methods including principal component analysis (PCA and support vector machine (SVM. As a result, PACA and Dermabond® tissue adhesive treated cells and tissues showed no difference of the cell viability values, histological analysis and Raman spectral intensity. Also, the classification analysis by means of PCA-SVM classifier could not discriminate the difference between the PACA and Dermabond® treated cells and DNA. Therefore we suggest that novel PACA might be useful as potential tissue adhesive with effective biocompatibility.

  10. Metal contamination disturbs biochemical and microbial properties of calcareous agricultural soils of the Mediterranean area.

    Science.gov (United States)

    de Santiago-Martín, Ana; Cheviron, Natalie; Quintana, Jose R; González, Concepción; Lafuente, Antonio L; Mougin, Christian

    2013-04-01

    Mediterranean climate characteristics and carbonate are key factors governing soil heavy-metal accumulation, and low organic matter (OM) content could limit the ability of microbial populations to cope with resulting stress. We studied the effects of metal contamination on a combination of biological parameters in soils having these characteristics. With this aim, soils were spiked with a mixture of cadmium, copper, lead, and zinc, at the two limit values proposed by current European legislation, and incubated for ≤12 months. Then we measured biochemical (phosphatase, urease, β-galactosidase, arylsulfatase, and dehydrogenase activities) and microbial (fungal and bacterial DNA concentration by quantitative polymerase chain reaction) parameters. All of the enzyme activities were strongly affected by metal contamination and showed the following inhibition sequence: phosphatase (30-64 %) soils was attributed to the different proportion of fine mineral fraction, OM, crystalline iron oxides, and divalent cations in soil solution. The decrease of fungal DNA concentration in metal-spiked soils was negligible, whereas the decrease of bacterial DNA was ~1-54 % at the lowest level and 2-69 % at the highest level of contamination. The lowest bacterial DNA decrease occurred in soils with the highest OM, clay, and carbonate contents. Finally, regarding the strong inhibition of the biological parameters measured and the alteration of the fungal/bacterial DNA ratio, we provide strong evidence that disturbance on the system, even within the limiting values of contamination proposed by the current European Directive, could alter key soil processes. These limiting values should be established according to soil characteristics and/or revised when contamination is produced by a mixture of heavy metals.

  11. Biochemical and Molecular Study of Carpobrotus edulis Bioactive Properties and Their Effects on Dugesia sicula (Turbellaria, Tricladida) Regeneration.

    Science.gov (United States)

    Meddeb, Emna; Charni, Mohamed; Ghazouani, Tesnime; Cozzolino, Autilia; Fratianni, Florinda; Raboudi, Faten; Nazzaro, Filomena; Fattouch, Sami

    2017-07-01

    The traditional medicinal properties of Carpobrotus edulis are well recognized, particularly in Tunisia where it is used for wound healing. Thus, in this study, biochemical and molecular properties of its leaves' bioactive aqueous-acetone extract were investigated. The total phenolic content (TPC) of the extract was estimated to be 184 ± 5 mg/100 g of fresh matter (FM). The qualitative and quantitative polyphenolic profile was determined by ultra performance liquid chromatography with diode array detection (UPLC-DAD) and showed that chlorogenic acid was the major compound (43.7%). The extract exhibits potent antioxidant capacities with IC50 = 56.19 and 58.91 μg/ml, as accessed via the anionic DPPH and cationic ABTS radical scavenging assays, respectively. The extract has high antibacterial properties, especially against the Gram+ Staphylococcus aureus and Bacillus cereus strains. To investigate the extract effect on regeneration, the flatworm Dugesia sicula Lepori, 1948, was used as a model. The macroscopic analysis of planarian cultures in ordinary medium containing phenolic extract at non-toxic concentrations illustrated that the extract caused morphological changes. Additionally, the molecular study through the fluorescence-activated cell sorting (FACS) technique showed that C. edulis polyphenols can harm the stem cells' development. These results emphasize the ecotoxicological impact of phenolic rejections in the environment on flatworms' physiology.

  12. Surface properties and microporosity of polyhydroxybutyrate under scanning electron microscopy

    International Nuclear Information System (INIS)

    Raouf, A.A.; Samsudin, A.R.; Samian, R.; Akool, K.; Abdullah, N.

    2004-01-01

    This study was designed to investigate the surface properties especially surface porosity of polyhydroxybutyrate (PHB) using scanning electron microscopy. PHB granules were sprinkled on the double-sided sticky tape attached on a SEM aluminium stub and sputtered with gold (10nm thickness) in a Polaron SC515 Coater, following which the samples were placed into the SEM specimen chamber for viewing and recording. Scanning electron micrographs with different magnification of PHB surface revealed multiple pores with different sizes. (Author)

  13. Optical properties and electron transport in low-dimensional nanostructures

    Czech Academy of Sciences Publication Activity Database

    Král, Karel; Menšík, Miroslav

    2011-01-01

    Roč. 54, 2-2 (2011), s. 4-13 ISSN 0021-3411 R&D Projects: GA MŠk(CZ) OC10007 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z40500505 Keywords : quantum dots * electron -photon interaction * optical properties * electron relaxation * DNA molecule Subject RIV: BE - The oretical Physics http://elibrary.ru/contents.asp?issueid=1010336

  14. Electronic properties of graphene-based bilayer systems

    Energy Technology Data Exchange (ETDEWEB)

    Rozhkov, A.V., E-mail: arozhkov@gmail.com [CEMS, RIKEN, Saitama 351-0198 (Japan); Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, 125412 Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141700 (Russian Federation); Sboychakov, A.O. [CEMS, RIKEN, Saitama 351-0198 (Japan); Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, 125412 Moscow (Russian Federation); Rakhmanov, A.L. [CEMS, RIKEN, Saitama 351-0198 (Japan); Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, 125412 Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141700 (Russian Federation); All-Russia Research Institute of Automatics, Moscow, 127055 (Russian Federation); Nori, Franco, E-mail: fnori@riken.jp [CEMS, RIKEN, Saitama 351-0198 (Japan); Physics Department, The University of Michigan, Ann Arbor, MI 48109-1040 (United States)

    2016-08-23

    This article reviews the theoretical and experimental work related to the electronic properties of bilayer graphene systems. Three types of bilayer stackings are discussed: the AA, AB, and twisted bilayer graphene. This review covers single-electron properties, effects of static electric and magnetic fields, bilayer-based mesoscopic systems, spin–orbit coupling, dc transport and optical response, as well as spontaneous symmetry violation and other interaction effects. The selection of the material aims to introduce the reader to the most commonly studied topics of theoretical and experimental research in bilayer graphene.

  15. Fundamentals of the Physics of Solids Volume 2: Electronic Properties

    CERN Document Server

    Sólyom, Jenő

    2009-01-01

    This book is the second of a single-authored, three-volume series that aims to deliver a comprehensive and self-contained account of the vast field of solid-state physics. It goes far beyond most classic texts in the presentation of the properties of solids and experimentally observed phenomena, along with the basic concepts and theoretical methods used to understand them and the essential features of various experimental techniques. The first volume deals with the atomic and magnetic structure and dynamics of solids, the second with those electronic properties that can be understood in the one-particle approximation, and the third with the effects due to interactions and correlations between electrons. This volume is devoted to the electronic properties of metals and semiconductors in the independent-electron approximation. After a brief discussion of the free-electron models by Drude and Sommerfeld, the methods for calculating and measuring the band structure of Bloch electrons moving in the periodic potent...

  16. Pasture degradation modifies soil organic matter properties and biochemical functioning in Tibetan grasslands

    Science.gov (United States)

    Spielvogel, Sandra; Steingräber, Laura; Schleuß, Per; Kuzyakov, Yakov; Guggenberger, Georg

    2015-04-01

    degradation stages 1, 2 and 3 although OC contents and composition in the subsoil changed progressively from stage 1 to 4. Only the PLFA profiles of stage 4 differed from those of the other subsoils, suggesting that microbial communities were mainly controlled by other factors than C and N contents and SOM composition. These findings were also confirmed by the activities of β-glucosidase, xylanase, amino-peptidases and proteases. Those enzyme activities were highest in the subsoil of degradation stage 4, whereas degradation stages 2 and 3 showed low enzyme activities in the subsoil if related to soil OC amount and composition. We conclude that pasture degradation decreases not only mechanical protection of soil surface by Kobresia root mats, but also changes their biochemical and microbial functions.

  17. Properties of Trapped Electron Bunches in a Plasma Wakefield Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Kirby, Neil; /SLAC

    2009-10-30

    Plasma-based accelerators use the propagation of a drive bunch through plasma to create large electric fields. Recent plasma wakefield accelerator (PWFA) experiments, carried out at the Stanford Linear Accelerator Center (SLAC), successfully doubled the energy for some of the 42 GeV drive bunch electrons in less than a meter; this feat would have required 3 km in the SLAC linac. This dissertation covers one phenomenon associated with the PWFA, electron trapping. Recently it was shown that PWFAs, operated in the nonlinear bubble regime, can trap electrons that are released by ionization inside the plasma wake and accelerate them to high energies. These trapped electrons occupy and can degrade the accelerating portion of the plasma wake, so it is important to understand their origins and how to remove them. Here, the onset of electron trapping is connected to the drive bunch properties. Additionally, the trapped electron bunches are observed with normalized transverse emittance divided by peak current, {epsilon}{sub N,x}/I{sub t}, below the level of 0.2 {micro}m/kA. A theoretical model of the trapped electron emittance, developed here, indicates that the emittance scales inversely with the square root of the plasma density in the non-linear 'bubble' regime of the PWFA. This model and simulations indicate that the observed values of {epsilon}{sub N,x}/I{sub t} result from multi-GeV trapped electron bunches with emittances of a few {micro}m and multi-kA peak currents. These properties make the trapped electrons a possible particle source for next generation light sources. This dissertation is organized as follows. The first chapter is an overview of the PWFA, which includes a review of the accelerating and focusing fields and a survey of the remaining issues for a plasma-based particle collider. Then, the second chapter examines the physics of electron trapping in the PWFA. The third chapter uses theory and simulations to analyze the properties of the trapped

  18. Baking properties and biochemical composition of wheat flour with bran and shorts.

    Science.gov (United States)

    Kaprelyants, Leonid; Fedosov, Sergey; Zhygunov, Dmytro

    2013-11-01

    Bran, being a by-product of grain grinding, is characterised by a high biological value and is thus widely used in food production. In this study, different streams of bran and shorts from the wheat graded milling process were incorporated into wheat flour at levels of 5, 11, 17 and 23% (w/w) to investigate their influence on the nutritional and baking properties of flour. Bran and shorts streams improved the baking properties of flour blends. The best result in the case of graded flour blends with different bran products was obtained at the 95:5 ratio. The products containing peripheral parts of grain had higher proteolytic enzyme and superoxide dismutase activities and lower trypsin inhibitor content and β-amylase activity compared with graded flour. Streams of wheat milled fractions including peripheral parts of grain increase the content of bioactive substances and dietary fibre in blends with wheat graded flour. © 2013 Society of Chemical Industry.

  19. Electronic structure properties of UO2 as a Mott insulator

    Science.gov (United States)

    Sheykhi, Samira; Payami, Mahmoud

    2018-06-01

    In this work using the density functional theory (DFT), we have studied the structural, electronic and magnetic properties of uranium dioxide with antiferromagnetic 1k-, 2k-, and 3k-order structures. Ordinary approximations in DFT, such as the local density approximation (LDA) or generalized gradient approximation (GGA), usually predict incorrect metallic behaviors for this strongly correlated electron system. Using Hubbard term correction for f-electrons, LDA+U method, as well as using the screened Heyd-Scuseria-Ernzerhof (HSE) hybrid functional for the exchange-correlation (XC), we have obtained the correct ground-state behavior as an insulator, with band gaps in good agreement with experiment.

  20. Electronic properties of bromine-doped carbon nanotubes

    CERN Document Server

    Jhi, S H; Cohen, M L

    2002-01-01

    Intercalation of bromine molecules (Br2) into single-wall carbon nanotube (SWNT) ropes is studied using the ab initio pseudopotential density functional method. Electronic and vibrational properties of the SWNT and Br2 are studied for various bromine concentrations. A drastic change in the charge transfer, bromine stretching-mode, and bromine bond-length is observed when the bromine-bromine distance decreases. Calculated electronic structures show that, at high bromine concentrations, the bromine ppsigma level broadens due to the interbromine interaction. These states overlap with the electronic bands of the SWNT near the Fermi level which results in a substantial charge transfer from carbon to bromine.

  1. Correlating substituent parameter values to electron transport properties of molecules

    International Nuclear Information System (INIS)

    Vedova-Brook, Natalie; Matsunaga, Nikita; Sohlberg, Karl

    2004-01-01

    There are a vast number of organic compounds that could be considered for use in molecular electronics. Because of this, the need for efficient and economical screening tools has emerged. We demonstrate that the substituent parameter values (σ), commonly found in advanced organic chemistry textbooks, correlate strongly with features of the charge migration process, establishing them as useful indicators of electronic properties. Specifically, we report that ab initio derived electronic charge transfer values for 16 different substituted aromatic molecules for molecular junctions correlate to the σ values with a correlation coefficient squared (R 2 ) of 0.863

  2. Charge-transfer properties in the gas electron multiplier

    International Nuclear Information System (INIS)

    Han, Sanghyo; Kim, Yongkyun; Cho, Hyosung

    2004-01-01

    The charge transfer properties of a gas electron multiplier (GEM) were systematically investigated over a broad range of electric field configurations. The electron collection efficiency and the charge sharing were found to depend on the external fields, as well as on the GEM voltage. The electron collection efficiency increased with the collection field up to 90%, but was essentially independent of the drift field strength. A double conical GEM has a 10% gain increase with time due to surface charging by avalanche ions whereas this effect was eliminated with the cylindrical GEM. The positive-ion feedback is also estimated. (author)

  3. One-Electron Theory of Metals. Cohesive and Structural Properties

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt

    The work described in the report r.nd the 16 accompanying publications is based upon a one-electron theory obtained within the local approximation to density-functional theory, and deals with the ground state of metals as obtained from selfconsistent electronic-structure calculations performed...... by means of the Linear Muffin-Tin Orbital (LMTO) method. It has been the goal of the work to establish how well this one-electron approach describes physical properties such as the crystal structures of the transition metals, the structural phase transitions in the alkali, alkaline earth, and rare earth...

  4. A Review on the Role of Vibrational Spectroscopy as An Analytical Method to Measure Starch Biochemical and Biophysical Properties in Cereals and Starchy Foods

    Directory of Open Access Journals (Sweden)

    D. Cozzolino

    2014-12-01

    Full Text Available Starch is the major component of cereal grains and starchy foods, and changes in its biophysical and biochemical properties (e.g., amylose, amylopectin, pasting, gelatinization, viscosity will have a direct effect on its end use properties (e.g., bread, malt, polymers. The use of rapid and non-destructive methods to study and monitor starch properties, such as gelatinization, retrogradation, water absorption in cereals and starchy foods, is of great interest in order to improve and assess their quality. In recent years, near infrared reflectance (NIR and mid infrared (MIR spectroscopy have been explored to predict several quality parameters, such as those generated by instrumental methods commonly used in routine analysis like the rapid visco analyser (RVA or viscometers. In this review, applications of both NIR and MIR spectroscopy to measure and monitor starch biochemical (amylose, amylopectin, starch and biophysical properties (e.g., pasting properties will be presented and discussed.

  5. Biochemical and biomechanical properties of the pacemaking sinoatrial node extracellular matrix are distinct from contractile left ventricular matrix.

    Directory of Open Access Journals (Sweden)

    Jessica M Gluck

    Full Text Available Extracellular matrix plays a role in differentiation and phenotype development of its resident cells. Although cardiac extracellular matrix from the contractile tissues has been studied and utilized in tissue engineering, extracellular matrix properties of the pacemaking sinoatrial node are largely unknown. In this study, the biomechanical properties and biochemical composition and distribution of extracellular matrix in the sinoatrial node were investigated relative to the left ventricle. Extracellular matrix of the sinoatrial node was found to be overall stiffer than that of the left ventricle and highly heterogeneous with interstitial regions composed of predominantly fibrillar collagens and rich in elastin. The extracellular matrix protein distribution suggests that resident pacemaking cardiomyocytes are enclosed in fibrillar collagens that can withstand greater tensile strength while the surrounding elastin-rich regions may undergo deformation to reduce the mechanical strain in these cells. Moreover, basement membrane-associated adhesion proteins that are ligands for integrins were of low abundance in the sinoatrial node, which may decrease force transduction in the pacemaking cardiomyocytes. In contrast to extracellular matrix of the left ventricle, extracellular matrix of the sinoatrial node may reduce mechanical strain and force transduction in pacemaking cardiomyocytes. These findings provide the criteria for a suitable matrix scaffold for engineering biopacemakers.

  6. Biochemical composition and antioxidant properties of Lavandula angustifolia Miller essential oil are shielded by propolis against UV radiations.

    Science.gov (United States)

    Gismondi, Angelo; Angelo, Gismondi; Canuti, Lorena; Lorena, Canuti; Grispo, Marta; Marta, Grispo; Canini, Antonella; Antonella, Canini

    2014-01-01

    UV radiations are principal causes of skin cancer and aging. Suntan creams were developed to protect epidermis and derma layers against photodegradation and photooxidation. The addition of antioxidant plant extracts (i.e. essential oil) to sunscreens is habitually performed, to increase their UV protective effects and to contrast pro-radical and cytotoxic compounds present in these solutions. According to these observations, in the present work, the alteration of chemical composition and bioactive properties of Lavandula angustifolia Miller essential oil, exposed to UV light, was investigated. UV induced a significant deterioration of lavender oil biochemical profile. Moreover, the antioxidant activity of this solution, in in vitro tests and directly on B16-F10 melanoma cells, greatly decreased after UV treatment. Our results also showed that essential oil was shielded from UV stress by propolis addition. Even after UV treatment, bee glue highly protected lavender oil secondary metabolites from degradation and also preserved their antiradical properties, both in in vitro antioxidant assays and in cell oxidative damage evaluations. This research proposed propolis as highly efficient UV protective and antiradical additive for sunscreens, cosmetics and alimentary or pharmaceutical products containing plant extracts. © 2013 The American Society of Photobiology.

  7. Nutrient-deprivation autophagy factor-1 (NAF-1: biochemical properties of a novel cellular target for anti-diabetic drugs.

    Directory of Open Access Journals (Sweden)

    Sagi Tamir

    Full Text Available Nutrient-deprivation autophagy factor-1 (NAF-1 (synonyms: Cisd2, Eris, Miner1, and Noxp70 is a [2Fe-2S] cluster protein immune-detected both in endoplasmic reticulum (ER and mitochondrial outer membrane. It was implicated in human pathology (Wolfram Syndrome 2 and in BCL-2 mediated antagonization of Beclin 1-dependent autophagy and depression of ER calcium stores. To gain insights about NAF-1 functions, we investigated the biochemical properties of its 2Fe-2S cluster and sensitivity of those properties to small molecules. The structure of the soluble domain of NAF-1 shows that it forms a homodimer with each protomer containing a [2Fe-2S] cluster bound by 3 Cys and one His. NAF-1 has shown the unusual abilities to transfer its 2Fe-2S cluster to an apo-acceptor protein (followed in vitro by spectrophotometry and by native PAGE electrophoresis and to transfer iron to intact mitochondria in cell models (monitored by fluorescence imaging with iron fluorescent sensors targeted to mitochondria. Importantly, the drug pioglitazone abrogates NAF-1's ability to transfer the cluster to acceptor proteins and iron to mitochondria. Similar effects were found for the anti-diabetes and longevity-promoting antioxidant resveratrol. These results reveal NAF-1 as a previously unidentified cell target of anti-diabetes thiazolidinedione drugs like pioglitazone and of the natural product resveratrol, both of which interact with the protein and stabilize its labile [2Fe-2S] cluster.

  8. Layered Black Phosphorus: Strongly Anisotropic Magnetic, Electronic, and Electron-Transfer Properties.

    Science.gov (United States)

    Sofer, Zdeněk; Sedmidubský, David; Huber, Štěpán; Luxa, Jan; Bouša, Daniel; Boothroyd, Chris; Pumera, Martin

    2016-03-01

    Layered elemental materials, such as black phosphorus, exhibit unique properties originating from their highly anisotropic layered structure. The results presented herein demonstrate an anomalous anisotropy for the electrical, magnetic, and electrochemical properties of black phosphorus. It is shown that heterogeneous electron transfer from black phosphorus to outer- and inner-sphere molecular probes is highly anisotropic. The electron-transfer rates differ at the basal and edge planes. These unusual properties were interpreted by means of calculations, manifesting the metallic character of the edge planes as compared to the semiconducting properties of the basal plane. This indicates that black phosphorus belongs to a group of materials known as topological insulators. Consequently, these effects render the magnetic properties highly anisotropic, as both diamagnetic and paramagnetic behavior can be observed depending on the orientation in the magnetic field. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Properties of Commercial PVC Films with Respect to Electron Dosimetry

    DEFF Research Database (Denmark)

    Miller, Arne; Liqing, Xie

    The properties of three commercially available polyvinyl chloride (PVC) film supplies and one made without additives were tested with respect to their application as routine dose monitors at electron accelerators. Dose fractionation was found to increase the response and the post-irradiation heat...

  10. Anomalous optical and electronic properties of dense sodium

    International Nuclear Information System (INIS)

    Li Dafang; Liu Hanyu; Wang Baotian; Shi Hongliang; Zhu Shaoping; Yan Jun; Zhang Ping

    2010-01-01

    Based on the density functional theory, we systematically study the optical and electronic properties of the insulating dense sodium phase (Na-hp4) reported recently (Ma et al., 2009). The structure is found optically anisotropic. Through Bader analysis, we conclude that ionicity exists in the structure and becomes stronger with increasing pressure.

  11. Electronic properties and Compton profiles of silver iodide

    Indian Academy of Sciences (India)

    We have carried out an extensive study of electronic properties of silver iodide in - and -phases. The theoretical Compton profiles, energy bands, density of states and anisotropies in momentum densities are computed using density functional theories. We have also employed full-potential linearized augmented ...

  12. Structural, elastic, electronic and optical properties of bi-alkali ...

    Indian Academy of Sciences (India)

    The structural parameters, elastic constants, electronic and optical properties of the bi-alkali ... and efficient method for the calculation of the ground-state ... Figure 2. Optimization curve (E–V) of the bi-alkali antimonides: (a) Na2KSb, (b) Na2RbSb, (c) Na2CsSb, .... ical shape of the charge distributions in the contour plots.

  13. Structural, energetic and electronic properties of intercalated boron ...

    Indian Academy of Sciences (India)

    2National Institute for R&D of Isotopic and Molecular Technologies, Cluj-Napoca 400 293, Romania. MS received 8 November 2010; revised 28 March 2012. Abstract. The effects of chirality and the intercalation of transitional metal atoms inside single walled BN nano- tubes on structural, energetic and electronic properties ...

  14. Morphology and electronic properties of the pentacene on cobalt interface

    NARCIS (Netherlands)

    Tiba, M. V.; Koopmans, B.; Jonkman, Harry; de Jonge, W.J.M.

    2006-01-01

    In this paper, we report the structural and electronic properties of pentacene thin films grown on a polycrystalline Co film using atomic force microscopy and ultraviolet photoemission spectroscopy (UPS), respectively. Investigation of this type of interface is of importance for the engineering of

  15. Electronic structure and optical properties of thorium monopnictides

    Indian Academy of Sciences (India)

    Unknown

    Indian Academy of Sciences. 165. Electronic structure and optical properties of thorium monopnictides. S KUMAR* and S AULUCK†. Physics Department, Institute of Engineering and Technology, M.J.P. Rohilkhand University, Bareilly 243 006,. India. †Department of Physics, Indian Institute of Technology, Roorkee 247 667, ...

  16. Tailoring electronic properties of multilayer phosphorene by siliconization

    Science.gov (United States)

    Malyi, Oleksandr I.; Sopiha, Kostiantyn V.; Radchenko, Ihor; Wu, Ping; Persson, Clas

    Controlling a thickness dependence of electronic properties for two-dimensional (2d) materials is among primary goals for their large-scale applications. Herein, employing a first-principles computational approach, we predict that Si interaction with multilayer phosphorene (2d-P) can result in the formation of highly stable 2d-SiP and 2d-SiP$_2$ compounds with a weak interlayer interaction. Our analysis demonstrates that these systems are semiconductors with band gap energies that can be governed by varying the thickness and stacking order. Specifically, siliconization of phosphorene allows to design 2d-SiP$_x$ materials with significantly weaker thickness dependence of electronic properties than that in 2d-P and to develop ways for their tailoring. We also reveal the spatial dependence of electronic properties for 2d-SiP$_x$ highlighting difference in effective band gaps for different layers. Particularly, our results show that central layers in the multilayer 2d systems determine overall electronic properties, while the role of the outermost layers is noticeably smaller.

  17. Biochemical properties of bioplastics made from wheat gliadins cross-linked with cinnamaldehyde.

    Science.gov (United States)

    Balaguer, M Pau; Gómez-Estaca, Joaquín; Gavara, Rafael; Hernandez-Munoz, Pilar

    2011-12-28

    The aim of this work has been to study the modification of gliadin films with cinnamaldehyde as a potential cross-linker agent. The molecular weight profile and cross-linking density showed that cinnamaldehyde increased reticulation in the resulting films. The participation of free amino groups of the protein in the newly created entanglements could be a possible mechanism of connection between the polypeptidic chains. The combination of a Schiff base and a Michael addition is a feasible approach to understanding this mechanism. The protein solubility in different media pointed to lower participation by both noncovalent and disulfide bonds in stabilizing the structure of the cross-linked films. The new covalent bonds formed by the cinnamaldehyde treatment hampered water absorption and weight loss, leading to more water-resistant matrices which had not disintegrated after 5 months. The properties of this novel bioplastic could be modified to suit the intended application by using cinnamaldehyde, a naturally occurring compound.

  18. Machine learning of molecular electronic properties in chemical compound space

    Science.gov (United States)

    Montavon, Grégoire; Rupp, Matthias; Gobre, Vivekanand; Vazquez-Mayagoitia, Alvaro; Hansen, Katja; Tkatchenko, Alexandre; Müller, Klaus-Robert; Anatole von Lilienfeld, O.

    2013-09-01

    The combination of modern scientific computing with electronic structure theory can lead to an unprecedented amount of data amenable to intelligent data analysis for the identification of meaningful, novel and predictive structure-property relationships. Such relationships enable high-throughput screening for relevant properties in an exponentially growing pool of virtual compounds that are synthetically accessible. Here, we present a machine learning model, trained on a database of ab initio calculation results for thousands of organic molecules, that simultaneously predicts multiple electronic ground- and excited-state properties. The properties include atomization energy, polarizability, frontier orbital eigenvalues, ionization potential, electron affinity and excitation energies. The machine learning model is based on a deep multi-task artificial neural network, exploiting the underlying correlations between various molecular properties. The input is identical to ab initio methods, i.e. nuclear charges and Cartesian coordinates of all atoms. For small organic molecules, the accuracy of such a ‘quantum machine’ is similar, and sometimes superior, to modern quantum-chemical methods—at negligible computational cost.

  19. Machine learning of molecular electronic properties in chemical compound space

    International Nuclear Information System (INIS)

    Montavon, Grégoire; Müller, Klaus-Robert; Rupp, Matthias; Gobre, Vivekanand; Hansen, Katja; Tkatchenko, Alexandre; Vazquez-Mayagoitia, Alvaro; Anatole von Lilienfeld, O

    2013-01-01

    The combination of modern scientific computing with electronic structure theory can lead to an unprecedented amount of data amenable to intelligent data analysis for the identification of meaningful, novel and predictive structure–property relationships. Such relationships enable high-throughput screening for relevant properties in an exponentially growing pool of virtual compounds that are synthetically accessible. Here, we present a machine learning model, trained on a database of ab initio calculation results for thousands of organic molecules, that simultaneously predicts multiple electronic ground- and excited-state properties. The properties include atomization energy, polarizability, frontier orbital eigenvalues, ionization potential, electron affinity and excitation energies. The machine learning model is based on a deep multi-task artificial neural network, exploiting the underlying correlations between various molecular properties. The input is identical to ab initio methods, i.e. nuclear charges and Cartesian coordinates of all atoms. For small organic molecules, the accuracy of such a ‘quantum machine’ is similar, and sometimes superior, to modern quantum-chemical methods—at negligible computational cost. (paper)

  20. Substitutionally doped phosphorene: electronic properties and gas sensing.

    Science.gov (United States)

    Suvansinpan, Nawat; Hussain, Fayyaz; Zhang, Gang; Chiu, Cheng Hsin; Cai, Yongqing; Zhang, Yong-Wei

    2016-02-12

    Phosphorene, a new elemental two-dimensional material, has attracted increasing attention owing to its intriguing electronic properties. In particular, pristine phospohorene, due to its ultrahigh surface-volume ratio and high chemical activity, has been shown to be promising for gas sensing (Abbas et al 2015 ACS Nano 9 5618). To further enhance its sensing ability, we perform first-principles calculations based on density functional theory to study substitutionally doped phosphorene with 17 different atoms, focusing on structures, energetics, electronic properties and gas sensing. Our calculations reveal that anionic X (X = O, C and S) dopants have a large binding energy and highly dispersive electronic states, signifying the formation of covalent X-P bonds and thus strong structural stability. Alkali atom (Li and Na) doping is found to donate most of the electrons in the outer s-orbital by forming ionic bonds with P, and the band gap decreases by pushing down the conduction band, suggesting that the optical and electronic properties of the doped phosphorene can be tailored. For doping with VIIIB-group (Fe, Co and Ni) elements, a strong affinity is predicted and the binding energy and charge transfer are correlated strongly with their electronegativity. By examining NO molecule adsorption, we find that these metal doped phosphorenes (MDPs) in general exhibit a significantly enhanced chemical activity compared with pristine phosphorene. Our study suggests that substitutionally doped phosphorene shows many intriguing electronic and optic properties different from pristine phosphorene and MDPs are promising in chemical applications involving molecular adsorption and desorption processes, such as materials growth, catalysis, gas sensing and storage.

  1. Intellectual property in consumer electronics, software and technology startups

    CERN Document Server

    Halt, Jr , Gerald B; Stiles, Amber R; Fesnak, Robert

    2014-01-01

    This book provides a comprehensive guide to procuring, utilizing and monetizing intellectual property rights, tailored for readers in the high-tech consumer electronics and software industries, as well as technology startups.  Numerous, real examples, case studies and scenarios are incorporated throughout the book to illustrate the topics discussed.  Readers will learn what to consider throughout the various creative phases of a product’s lifespan from initial research and development initiatives through post-production.  Readers will gain an understanding of the intellectual property protections afforded to U.S. corporations, methods to pro-actively reduce potential problems, and guidelines for future considerations to reduce legal spending, prevent IP theft, and allow for greater profitability from corporate innovation and inventiveness. • Offers a comprehensive guide to intellectual property for readers in high-tech consumer electronics, software and technology startups; • Uses real case studies...

  2. Properties of the electron cloud in a high-energy positron and electron storage ring

    International Nuclear Information System (INIS)

    Harkay, K.C.; Rosenberg, R.A.

    2003-01-01

    Low-energy, background electrons are ubiquitous in high-energy particle accelerators. Under certain conditions, interactions between this electron cloud and the high-energy beam can give rise to numerous effects that can seriously degrade the accelerator performance. These effects range from vacuum degradation to collective beam instabilities and emittance blowup. Although electron-cloud effects were first observed two decades ago in a few proton storage rings, they have in recent years been widely observed and intensely studied in positron and proton rings. Electron-cloud diagnostics developed at the Advanced Photon Source enabled for the first time detailed, direct characterization of the electron-cloud properties in a positron and electron storage ring. From in situ measurements of the electron flux and energy distribution at the vacuum chamber wall, electron-cloud production mechanisms and details of the beam-cloud interaction can be inferred. A significant longitudinal variation of the electron cloud is also observed, due primarily to geometrical details of the vacuum chamber. Such experimental data can be used to provide realistic limits on key input parameters in modeling efforts, leading ultimately to greater confidence in predicting electron-cloud effects in future accelerators.

  3. Urban waste compost: Effects on physical, chemical, and biochemical soil properties

    Energy Technology Data Exchange (ETDEWEB)

    Giusquiani, P.L.; Gigliotti, G.; Businelli, D. [Istituto di Chimica Agraria dell`Universita, Perugia (Italy)] [and others

    1995-01-01

    A long-term field experiment was conducted to determine the effect of the additions of urban waste compost on the physical and chemical properties and enzymatic activities in a calcareous soil (Fluventic Xerochrept). Total Porosity (pores >50 pm measured on thin soil sections from undisturbed samples by image analysis) was greater in the plots treated with compost than the control plots due to a larger amount of elongated pores. In the amended plots total and humified organic C, Pb, Cu, and Zn showed a significant increase compared with nonamended plots. Enzymatic activities (L-asparaginase, arylsulphatase, dehydrogenase, phosphodiesterase, and alkaline phosphomonoesterase) were significantly enhanced by the compost addition thus indicating no inhibiting influence of the heavy metals present. The increased levels of the arylsulphatase, dehydrogenase, phosphodiesterase, and phosphomonoesterase activities were significantly correlated with total porosity: the first three with pores ranging from 50 to 1000 {mu}m, mainly with pores 50 to 200 {mu}m in size and phosphomonoesterase only with pores whose size was <500 {mu}m. L-asparaginase activity was not correlated with porosity. Only arylsulphatase, dehydrogenase, and phosphodiesterase were negatively correlated with bulk density. 44 refs., 4 figs., 6 tabs.

  4. Biochemical Properties and Mechanism of Action of Enterocin LD3 Purified from Enterococcus hirae LD3.

    Science.gov (United States)

    Gupta, Aabha; Tiwari, Santosh Kumar; Netrebov, Victoria; Chikindas, Michael L

    2016-09-01

    Enterocin LD3 was purified using activity-guided multistep chromatography techniques such as cation-exchange and gel-filtration chromatography. The preparation's purity was tested using reverse-phase ultra-performance liquid chromatography. The specific activity was tested to be 187.5 AU µg(-1) with 13-fold purification. Purified enterocin LD3 was heat stable up to 121 °C (at 15 psi pressure) and pH 2-6. The activity was lost in the presence of papain, reduced by proteinase K, pepsin and trypsin, but was unaffected by amylase and lipase, suggesting proteinaceous nature of the compound and no role of carbohydrate and lipid moieties in the activity. MALDI-TOF/MS analysis of purified enterocin LD3 resolved m/z 4114.6, and N-terminal amino acid sequence was found to be H2NQGGQANQ-COOH suggesting a new bacteriocin. Dissipation of membrane potential, loss of internal ATP and bactericidal effect were recorded when indicator strain Micrococcus luteus was treated with enterocin LD3. It inhibited Gram-positive and Gram-negative bacteria including human pathogens such as Staphylococcus aureus, Pseudomonas fluorescens, Pseudomonas aeruginosa, Salmonella typhi, Shigella flexneri, Listeria monocytogenes, Escherichia coli O157:H7, E. coli (urogenic, a clinical isolate) and Vibrio sp. These properties of purified enterocin LD3 suggest its applications as a food biopreservative and as an alternative to clinical antibiotics.

  5. Biochemical Properties and Neuroprotective Effects of Compounds in Various Species of Berries

    Directory of Open Access Journals (Sweden)

    Erin Kelly

    2017-12-01

    Full Text Available Several species of berries, such as blueberries (Vaccinium angustifolium and lingonberries (Vaccinium vitis-idaea L., have attracted much scientific attention in recent years, especially due to their reported antioxidant and anti-inflammatory properties. Berries, as with other types of plants, have developed metabolic mechanisms to survive various environmental stresses, some of which involve reactive oxygen species. In addition, the fruits and leaves of berries have high amounts of polyphenols, such as flavonoids, which act as potent antioxidants. These compounds could potentially be beneficial for brain aging and neurodegenerative disorders. There are now several studies documenting the beneficial effects of various berries in cell models of neurotoxicity as well as in vivo models of neurodegenerative disease. In the current review, we discuss the metabolic strategies that plants and animals have developed in order to combat reactive oxygen species. We then discuss issues of bioavailability of various compounds in mammals and provide a synopsis of studies demonstrating the neuroprotective ability of berries and polyphenols. We also summarize findings from our own research group. For example, we have detected various polyphenols in samples of blueberries and lingonberries and have found that the leaves have a much higher antioxidant capacity than the fruits. Extracts from these species have also demonstrated neuroprotective effects in cellular models of toxicity and inflammation, which are being further pursued in animal models.

  6. Biochemical properties of mammalian TREX1 and its association with DNA replication and inherited inflammatory disease.

    Science.gov (United States)

    Lindahl, Tomas; Barnes, Deborah E; Yang, Yun-Gui; Robins, Peter

    2009-06-01

    The major DNA-specific 3'-5' exonuclease of mammalian cells is TREX1 (3' repair exonuclease 1; previously called DNase III). The human enzyme is encoded by a single exon and, like many 3' exonucleases, exists as a homodimer. TREX1 degrades ssDNA (single-stranded DNA) more efficiently than dsDNA (double-stranded DNA), and its catalytic properties are similar to those of Escherichia coli exonuclease X. However, TREX1 is only found in mammals and has an extended C-terminal domain containing a leucine-rich sequence required for its association with the endoplasmic reticulum. In normal S-phase and also in response to genotoxic stress, TREX1 at least partly redistributes to the cell nucleus. In a collaborative project, we have demonstrated TREX1 enzyme deficiency in Aicardi-Goutières syndrome. Subsequently, we have shown that AGS1 cells exhibit chronic ATM (ataxia telangiectasia mutated)-dependent checkpoint activation, and these TREX1-deficient cells accumulate ssDNA fragments of a distinct size generated during DNA replication. Other groups have shown that the syndromes of familial chilblain lupus as well as systemic lupus erythematosus, and the distinct neurovascular disorder retinal vasculopathy with cerebral leukodystrophy, can be caused by dominant mutations at different sites within the TREX1 gene.

  7. Biochemical properties of Cu/Zn-superoxide dismutase from fungal strain Aspergillus niger 26

    Science.gov (United States)

    Dolashki, Aleksandar; Abrashev, Radoslav; Stevanovic, Stefan; Stefanova, Lilyana; Ali, Syed Abid; Velkova, Ludmila; Hristova, Rumyana; Angelova, Maria; Voelter, Wolfgang; Devreese, Bart; Van Beeumen, Jozef; Dolashka-Angelova, Pavlina

    2008-12-01

    The fungal strain Aspergillus niger produces two superoxide dismutases, Cu/Zn-SOD and Mn-SOD. The primary structure of the Cu/Zn-SOD has been determined by Edman degradation of peptide fragments derived from proteolytic digests. A single chain of the protein, consisting of 153 amino acid residues, reveals a very high degree of structural homology with the amino acid sequences of other Aspergillus Cu/Zn-SODs. The molecular mass of ANSOD, measured by MALDI-MS and ESI-MS, and calculated by its amino acid sequence, was determined to be 15 821 Da. Only one Trp residue, at position 32, and one disulfide bridge were identified. However, neither a Tyr residue nor a carbohydrate chain occupying an N-linkage site (-Asn-Ile-Thr-) were found. Studies on the temperature and pH dependence of fluorescence, and on the temperature dependence of CD spectroscopic properties, confirmed that the enzyme is very stable, which can be explained by the stabilising effect of the disulfide bridge. The enzyme retains about 53% of its activity after incubation for a period of 30 min at 60 °C, and 15% at 85 °C.

  8. Combining measurements to estimate properties and characterization extent of complex biochemical mixtures; applications to Heparan Sulfate

    Science.gov (United States)

    Pradines, Joël R.; Beccati, Daniela; Lech, Miroslaw; Ozug, Jennifer; Farutin, Victor; Huang, Yongqing; Gunay, Nur Sibel; Capila, Ishan

    2016-04-01

    Complex mixtures of molecular species, such as glycoproteins and glycosaminoglycans, have important biological and therapeutic functions. Characterization of these mixtures with analytical chemistry measurements is an important step when developing generic drugs such as biosimilars. Recent developments have focused on analytical methods and statistical approaches to test similarity between mixtures. The question of how much uncertainty on mixture composition is reduced by combining several measurements still remains mostly unexplored. Mathematical frameworks to combine measurements, estimate mixture properties, and quantify remaining uncertainty, i.e. a characterization extent, are introduced here. Constrained optimization and mathematical modeling are applied to a set of twenty-three experimental measurements on heparan sulfate, a mixture of linear chains of disaccharides having different levels of sulfation. While this mixture has potentially over two million molecular species, mathematical modeling and the small set of measurements establish the existence of nonhomogeneity of sulfate level along chains and the presence of abundant sulfate repeats. Constrained optimization yields not only estimations of sulfate repeats and sulfate level at each position in the chains but also bounds on these levels, thereby estimating the extent of characterization of the sulfation pattern which is achieved by the set of measurements.

  9. Magnetic and electronic properties of some actinide intermetallic compounds

    International Nuclear Information System (INIS)

    Yaar, Ilan

    1992-06-01

    The electronic structure and magnetic properties of the light actinide intermetallic compounds are often related to interplay between localized and itinerant (band like) behavior of the 5f- electrons. In the present work, the properties of some actinide, mainly Np, intermetallic compounds were studied by Mossbauer effect, ac and dc susceptibility, X-ray and Neutron diffraction techniques. 1. NpX 2 (X=Ga,Si) - Both compounds order ferromagnetically at TC=55(2) and 48(2) K respectively. A comparison of our data with the results for other NpX 2 (X=Al,As,Sb,Tl) compounds indicates that NpGa 2 is a highly localized 5f electron system, whereas in NpSi 2 the 5f electrons are partially delocalized. The magnetic properties of NpX 2 compounds can neither be consistently explained within the conventional crystal electric field picture (CEF) nor by takink into account hybridization dressing of local spin density models. 2. NpX 3 (X=Ga,Si,In,Al) in the cubic AuCu 3 (Pm3m) crystallographic structure - From the Mossbauer isomer shift (IS) data we argue that the Np ion in the NpX 3 family is close to the formal 3+ (5I 4 ) charge state. The magnetic moment of the Np in NpSi 3 is totally suppressed whereas in NpGa 3 and NpAl 3 a localized (narrow band) moment is established. However, in NpIn 3 at 4.2 K, a modulated magnetic moment (0-1.5μB) is observed. Comparing the magnetic behavior of the NpX 3 family (X=Si,Ge,Ga, Al,In and Sn), we find an impressive variation of the magnetic properties, from temperature independent paramagnetism (TIP), localized and modulated ordered moments, to the formation of a concentrated Kondo lattice. Hybridization of 5f electrons with ligand electrons appears to play a crucial role in establishing these magnetic properties. However, at present a consistent theoretical picture can not be drawn. 3. XFe 4 Al 8 (X=Ho,Np,U) spin galss (SG) systems in the ThMn 12 (I 4 /mmm) crystallographic structure - Localized and itinerant behaviour of the f electrons

  10. PR2ALIGN: a stand-alone software program and a web-server for protein sequence alignment using weighted biochemical properties of amino acids.

    Science.gov (United States)

    Kuznetsov, Igor B; McDuffie, Michael

    2015-05-07

    Alignment of amino acid sequences is the main sequence comparison method used in computational molecular biology. The selection of the amino acid substitution matrix best suitable for a given alignment problem is one of the most important decisions the user has to make. In a conventional amino acid substitution matrix all elements are fixed and their values cannot be easily adjusted. Moreover, most existing amino acid substitution matrices account for the average (dis)similarities between amino acid types and do not distinguish the contribution of a specific biochemical property to these (dis)similarities. PR2ALIGN is a stand-alone software program and a web-server that provide the functionality for implementing flexible user-specified alignment scoring functions and aligning pairs of amino acid sequences based on the comparison of the profiles of biochemical properties of these sequences. Unlike the conventional sequence alignment methods that use 20x20 fixed amino acid substitution matrices, PR2ALIGN uses a set of weighted biochemical properties of amino acids to measure the distance between pairs of aligned residues and to find an optimal minimal distance global alignment. The user can provide any number of amino acid properties and specify a weight for each property. The higher the weight for a given property, the more this property affects the final alignment. We show that in many cases the approach implemented in PR2ALIGN produces better quality pair-wise alignments than the conventional matrix-based approach. PR2ALIGN will be helpful for researchers who wish to align amino acid sequences by using flexible user-specified alignment scoring functions based on the biochemical properties of amino acids instead of the amino acid substitution matrix. To the best of the authors' knowledge, there are no existing stand-alone software programs or web-servers analogous to PR2ALIGN. The software is freely available from http://pr2align.rit.albany.edu.

  11. Biochemical and physical kernel properties of a standard maize hybrid in different TopCross™ Blends

    Directory of Open Access Journals (Sweden)

    Jelena Vancetovic

    Full Text Available ABSTRACT A pilot experiment was undertaken in order to examine high oil populations of maize (Zea mays L. to be used as pollinators in TopCross blends with commercial ZP341 standard hybrid. Five high oil populations (HOPs from the Maize Research Institute (MRI gene bank were chosen for this research, according to their high grain oil content, synchrony between silking of ZP341 and anthesis of the populations and good agronomic performances in 2012. Selfing of ZP341 and HOPs, as well as crosses of ZP341 cmsS sterile × HOPs were carried out in 2013. Oil content, fatty acid composition, protein and tryptophan content, and physical characteristics of the obtained kernels were measured. Four HOPs showed significant positive influence on the oil content in the TopCrosses (TC, 16.85 g kg−1 on average. Oleic acid, which is the principal monounsaturated fatty acid, was significantly lower in all HOPs and all TCs, while selfed ZP341 had almost twice the average value typical for standard maize. However, this decrease in TCs was in a narrow range from 1 % (in TC-3 to 5 % (in TC-4 and the oleic content of TCs was on average higher by 60 % compared to the typical standard maize. Different favorable and unfavorable significant changes were detected in fatty acid compositions, protein and tryptophan contents and physical kernel properties for each potential TC combination. Results indicate differences in gene effects present in different TC combinations and underscore the need to examine each potential TC blend by conducting similar simple experiments.

  12. Comparison of biochemical properties of liver arginase from streptozocin-induced diabetic and control mice.

    Science.gov (United States)

    Spolarics, Z; Bond, J S

    1989-11-01

    Arginase activity is elevated in livers of diabetic animals compared to controls and there is evidence that this is due in part to increased specific activity (activity/mg arginase protein). To investigate the molecular basis of this increased activity, the physicochemical and kinetic properties of hepatic arginase from diabetic and control mice were compared. Two types of arginase subunits with molecular weights of 35,000 and 38,000 were found in both the diabetic and control animals and the subunits in these animals had similar, multiple ionic forms. Kinetic parameters of purified preparations of arginase for arginine (apparent Km and Vmax values) and the thermal stability of these preparations from diabetics and controls were also similar. Furthermore, no difference was found in the distribution of arginase activity among different subcellular liver fractions. Separation of basic and acidic oligomeric forms of arginase by fast-protein liquid chromatography resulted in a slightly different distribution of activity among the forms in the normal and diabetic group. The apparent Km values for Mn2+ of the basic form of the enzyme were 25 and 33 microM for the enzyme from normal and diabetic animals, respectively; for acidic forms, for which two apparent Km values were measured, the values were 8 and 197 microM for arginase from controls and 35 and 537 microM from diabetics. These results indicate that in diabetes, while no marked changes in the physicochemical characteristics of arginase are obvious, some changes are found in the interaction of arginase with its cofactor Mn.

  13. The study of the biochemical properties of Nigelia Sativa L. and their use as radiation protectors

    International Nuclear Information System (INIS)

    Rzayev, N.R; Guliyev, N.T.; Kiseleva, T.L; Pavlova, L.A; Bereza, N.S.

    2012-01-01

    Full text : Recently in order to protect organisms from the of radiation effect radio protectors have been applied principally concerning to sulfur compounds, aminothioles and indolilalkins. Due to the long-term exploitations and misuse of soil under man-made factor the area of eroded soils has significantly increased. Consequently, cultivation and pasture areas have decreased. Recently the use of synthetic medicinal preparations has increased in order to meet the demands of people. Race mates are not observed in natural substances. The presence of race mates and isomers in human organism causes different diseases. Therefore its required to set new soils in operation and cultivate highly-productive species. The seeds and seed oil have been used as a diuretic, appetitive, hemorrhagic and anti dandruff therapy in folk medicine. The seeds have also been used traditionally for centuries in the Middle East, Far East, and some Mediterranean and European countries for the treatment of deferent ailments such as diabetes, hypertension, cardiac diseases, hemorrhoids, and sexual diseases and a s an abortifacient. Essential oil plants are potential radio protectors. Many plants are applied according to radio protector features of essential oils. Radiotherapy is one of the most common therapies for treating human cancers. Several studies have indicated that irradiation induces reactive oxygen species which play an important role in radiation damage of the cell. In the scientific literature there results as alcoholic and non-alcoholic beverages have been used to treat burns radioactive substances and their removal from the body. Our progress in the preparation of liqueurs, sadofos, soft drinks from plants, will allow the successful use. Clean oil of sea buck thorn, black cumin and basil have strong radio protective properties. The production of these oils without determinant of impurities has been tested in laboratory conditions, the implementations of this technology

  14. First principles study of electronic properties, interband transitions and electron energy loss of α-graphyne

    Science.gov (United States)

    Behzad, Somayeh

    2016-04-01

    The electronic and optical properties of α-graphyne sheet are investigated by using density functional theory. The results confirm that α-graphyne sheet is a zero-gap semimetal. The optical properties of the α-graphyne sheet such as dielectric function, refraction index, electron energy loss function, reflectivity, absorption coefficient and extinction index are calculated for both parallel and perpendicular electric field polarizations. The optical spectra are strongly anisotropic along these two polarizations. For (E ∥ x), absorption edge is at 0 eV, while there is no absorption below 8 eV for (E ∥ z).

  15. Mechanical and electronic properties of Janus monolayer transition metal dichalcogenides

    Science.gov (United States)

    Shi, Wenwu; Wang, Zhiguo

    2018-05-01

    The mechanical and electronic properties of Janus monolayer transition metal dichalcogenides MXY (M  =  Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W; X/Y  =  S, Se, Te) were investigated using density functional theory. Results show that breaking the out-of-plane structural symmetry can be used to tune the electronic and mechanical behavior of monolayer transition metal dichalcogenides. The band gaps of monolayer WXY and MoXY are in the ranges of 0.16–1.91 and 0.94–1.69 eV, respectively. A semiconductor to metallic phase transition occurred in Janus monolayer MXY (M  =  Ti, Zr and Hf). The monolayers MXY (M  =  V, Nb, Ta and Cr) show metallic characteristics, which show no dependence on the structural symmetry breaking. The mechanical properties of MXY depended on the composition. Monolayer MXY (M  =  Mo, Ti, Zr, Hf and W) showed brittle characteristic, whereas monolayer CrXY and VXY are with ductile characteristic. The in-plane stiffness of pristine and Janus monolayer MXY are in the range between 22 and 158 N m‑1. The tunable electronic and mechanical properties of these 2D materials would advance the development of ultra-sensitive detectors, nanogenerators, low-power electronics, and energy harvesting and electromechanical systems.

  16. Carbon nanotube on Si(001): structural and electronic properties

    International Nuclear Information System (INIS)

    Orellana, W.; Fazzio, A.; Miwa, R.W.

    2003-01-01

    Full text: The promising nanoscale technology based on carbon nanotubes has attracted much attention due to the unique electronic, chemical and mechanical properties of the nanotubes. Single-wall carbon nanotubes (SWCNs) provide an ideal atomically uniform one dimensional (1D) conductors, having a strong electronic confinement around its circumference, which can be retained up to room temperature[1]. This interesting property may lead one to consider SWCNs as 1D conductors for the development of nanoscale electronic devices. In this work the structural and electronic properties of the contact between a metallic (6,6) SWCN adsorbed on a silicon (001) surface are studied from first-principles total-energy calculations. We consider two adsorption sites for the tube on the Si(001) surface: on the top of the Si-dimer rows and on the surface 'trench' between two consecutive dimer rows. Our results show a chemical bond between the nanotube and Si(001) when the tube is located along the 'trench', which corresponds to the only bound structure. We find a binding energy per tube length of 0.21 eV/angstrom. We also verified that the binding energy depends on the rotation of the tube. Typically, a rotation of 15 deg can reduce the binding energy up to 0.07 eV/angstrom. Our calculated electronic properties indicate that the most stable structure shows a subband associated to the tube/surface bond that cross the Fermi level. This result indicates an enhanced metallic behavior along the tube/surface contact characterizing a 1D quantum wire. The charge transfer between the Si surface and the tube is also discussed. [1] Z. Yao, C. Dekker, and P. Avouris in Carbon Nanotubes, M. S. Dresselhaus, G. Dresselhaus, and P. Avouris Eds., (Springer, Berlin 2001), p. 147. (author)

  17. Electronic properties and phase transitions in low-dimensional semiconductors

    International Nuclear Information System (INIS)

    Panich, A M

    2008-01-01

    We present the first review of the current state of the literature on electronic properties and phase transitions in TlX and TlMX 2 (M = Ga, In; X = Se, S, Te) compounds. These chalcogenides belong to a family of the low-dimensional semiconductors possessing chain or layered structure. They are of significant interest because of their highly anisotropic properties, semi- and photoconductivity, nonlinear effects in their I-V characteristics (including a region of negative differential resistance), switching and memory effects, second harmonic optical generation, relaxor behavior and potential applications for optoelectronic devices. We review the crystal structure of TlX and TlMX 2 compounds, their transport properties under ambient conditions, experimental and theoretical studies of the electronic structure, transport properties and semiconductor-metal phase transitions under high pressure, and sequences of temperature-induced structural phase transitions with intermediate incommensurate states. The electronic nature of the ferroelectric phase transitions in the above-mentioned compounds, as well as relaxor behavior, nanodomains and possible occurrence of quantum dots in doped and irradiated crystals is discussed. (topical review)

  18. Measurements of Lunar Dust Charging Properties by Electron Impact

    Science.gov (United States)

    Abbas, Mian M.; Tankosic, Dragana; Craven, Paul D.; Schneider, Todd A.; Vaughn, Jason A.; LeClair, Andre; Spann, James F.; Norwood, Joseph K.

    2009-01-01

    Dust grains in the lunar environment are believed to be electrostatically charged predominantly by photoelectric emissions resulting from solar UV radiation on the dayside, and on the nightside by interaction with electrons in the solar wind plasma. In the high vacuum environment on the lunar surface with virtually no atmosphere, the positive and negative charge states of micron/submicron dust grains lead to some unusual physical and dynamical dust phenomena. Knowledge of the electrostatic charging properties of dust grains in the lunar environment is required for addressing their hazardous effect on the humans and mechanical systems. It is well recognized that the charging properties of individual small micron size dust grains are substantially different from the measurements on bulk materials. In this paper we present the results of measurements on charging of individual Apollo 11 and Apollo 17 dust grains by exposing them to mono-energetic electron beams in the 10-100 eV energy range. The charging/discharging rates of positively and negatively charged particles of approx. 0.1 to 5 micron radii are discussed in terms of the sticking efficiencies and secondary electron yields. The secondary electron emission process is found to be a complex and effective charging/discharging mechanism for incident electron energies as low as 10-25 eV, with a strong dependence on particle size. Implications of the laboratory measurements on the nature of dust grain charging in the lunar environment are discussed.

  19. Electronic, mechanical and dielectric properties of silicane under tensile strain

    International Nuclear Information System (INIS)

    Jamdagni, Pooja; Sharma, Munish; Ahluwalia, P. K.; Kumar, Ashok; Thakur, Anil

    2015-01-01

    The electronic, mechanical and dielectric properties of fully hydrogenated silicene i.e. silicane in stable configuration are studied by means of density functional theory based calculations. The band gap of silicane monolayer can be flexibly reduced to zero when subjected to bi-axial tensile strain, leading to semi-conducting to metallic transition, whereas the static dielectric constant for in-plane polarization increases monotonically with increasing strain. Also the EEL function show the red shift in resonance peak with tensile strain. Our results offer useful insight for the application of silicane monolayer in nano-optical and electronics devices

  20. Acoustic and electronic properties of one-dimensional quasicrystals

    International Nuclear Information System (INIS)

    Nori, F.; Rodriguez, J.P.

    1986-01-01

    We study the acoustic and electronic properties of one-dimensional quasicrystals. Both numerical (nonperturbative) and analytical (perturbative) results are shown. The phonon and electronic spectra exhibit a self-similar hierarchy of gaps and many localized states in the gaps. We study quasiperiodic structures with any number of layers and several types of boundary conditions. We discuss the connection between our phonon model and recent experiments on quasiperiodic GaAs-AlAs superlattices. We predict the existence of many gap states localized at the surfaces

  1. Effects of gamma irradiation on the biochemical properties of walnut and pistachio nut in Syria, first phase: just after irradiation

    International Nuclear Information System (INIS)

    Karajoli, M.; Moussa, A.; Al-Kaed, A.; Othman, I.

    1997-05-01

    The report describes a preliminary study that led to explore the possibility of preserving and extending the storage life of walnut and pistachio nut by gamma radiation. Syrian walnut and pistachio nut were irradiated in a Gamma cell (dose rate 0.08 kGy/min). Radiation doses used were 0.50 and 1.00 kGy and the samples were stored at room temperature (25 to 30 Centigrade) after packaging in polyethylene pouches. Fungi infestation was determined before and after gamma radiation treatment. A radiation dose of 1.00 kGy completely inhibited fungi infestation. The present study has, therefore, been conducted to investigate the effects of gamma radiation on the Biochemical properties of walnut and pistachio nut just after irradiation (first phase). Chemical analyses have shown the phosphorus and total proteins value decrease at 0.50 and 1.00 kGy and some significant changes were observed in carbohydrates. A slight decrease in the amount of converted sugars was also observed. Fats in walnut are less vulnerable to gamma radiation than pistachio nut due certainly to the high amount in unsaturated oleic and linoleic acids. In conclusion the effect of gamma radiation on walnut and pantheistic appears nutritionally significant in pistachio nut and less in walnut. More investigations are necessary after a long time of storage to prove their intact nutritional quality and eventually their good digestibility. (author). 6 refs., 6 figs., 22 tabs

  2. effects of gamma irradiation on the biochemical properties of walnut and pistachio nut in Syria, first phase: just after irradiation

    International Nuclear Information System (INIS)

    Othman, I.; Karajoli, M.; Moussa, A.; Al-Kaed, A.

    1998-01-01

    The report describes a preliminary study that led to explore the possibility of preserving and extending the storage life of walnut and pistachio nut by gamma radiation. Syrian walnut and pistachio nut were irradiated in a Gamma cell (dose rate 0.08 kGy/min). Radiation doses used were 0.50 and 1.00 kGy and the samples were stored at room temperature (25 to 30 Centigrade) after packaging in polyethylene pouches. Fungi infestation was determined before and after gamma radiation treatment. A radiation dose of 1.00 kGy completely inhibited fungi infestation. The present study has, therefore, been conducted to investigate the effects of gamma radiation on the Biochemical properties of walnut and pistachio nut just after irradiation (first phase). Chemical analyses have shown the phosphorus and total proteins value decrease at 0.50 and 1.00 kGy and some significant changes were observed in carbohydrates. A slight decrease in the amount of converted sugars was also observed. Fats in walnut are less vulnerable to gamma radiation than pistachio nut due certainly to the high amount in unsaturated oleic and linoleic acids. In conclusion the effect of gamma radiation on walnut and pantheistic appears nutritionally significant in pistachio nut and less in walnut. More investigations are necessary after a long time of storage to prove their intact nutritional quality and eventually their good digestibility. (author). 6 refs

  3. Effects of gamma irradiation on the biochemical properties of walnut and pistachio nut in Syria, first phase: just after irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Karajoli, M; Moussa, A; Al-Kaed, A; Othman, I [Atomic Energy Commission, Radiation Technology Unit, Irradiation Plant, Damascus (Syrian Arab Republic)

    1997-05-01

    The report describes a preliminary study that led to explore the possibility of preserving and extending the storage life of walnut and pistachio nut by gamma radiation. Syrian walnut and pistachio nut were irradiated in a Gamma cell (dose rate 0.08 kGy/min). Radiation doses used were 0.50 and 1.00 kGy and the samples were stored at room temperature (25 to 30 Centigrade) after packaging in polyethylene pouches. Fungi infestation was determined before and after gamma radiation treatment. A radiation dose of 1.00 kGy completely inhibited fungi infestation. The present study has, therefore, been conducted to investigate the effects of gamma radiation on the Biochemical properties of walnut and pistachio nut just after irradiation (first phase). Chemical analyses have shown the phosphorus and total proteins value decrease at 0.50 and 1.00 kGy and some significant changes were observed in carbohydrates. A slight decrease in the amount of converted sugars was also observed. Fats in walnut are less vulnerable to gamma radiation than pistachio nut due certainly to the high amount in unsaturated oleic and linoleic acids. In conclusion the effect of gamma radiation on walnut and pantheistic appears nutritionally significant in pistachio nut and less in walnut. More investigations are necessary after a long time of storage to prove their intact nutritional quality and eventually their good digestibility. (author). 6 refs., 6 figs., 22 tabs.

  4. Effects of gamma irradiation on the biochemical properties of walnut and pistachio nut in Syria, first phase: just after irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Othman, I; Karajoli, M; Moussa, A; Al-Kaed, A [Atomic Energy commission, Radiation Technology Unit, Damascus, (Syrian Arab Republic)

    1998-03-01

    The report describes a preliminary study that led to explore the possibility of preserving and extending the storage life of walnut and pistachio nut by gamma radiation. Syrian walnut and pistachio nut were irradiated in a Gamma cell (dose rate 0.08 kGy/min). Radiation doses used were 0.50 and 1.00 kGy and the samples were stored at room temperature (25 to 30 Centigrade) after packaging in polyethylene pouches. Fungi infestation was determined before and after gamma radiation treatment. A radiation dose of 1.00 kGy completely inhibited fungi infestation. The present study has, therefore, been conducted to investigate the effects of gamma radiation on the Biochemical properties of walnut and pistachio nut just after irradiation (first phase). Chemical analyses have shown the phosphorus and total proteins value decrease at 0.50 and 1.00 kGy and some significant changes were observed in carbohydrates. A slight decrease in the amount of converted sugars was also observed. Fats in walnut are less vulnerable to gamma radiation than pistachio nut due certainly to the high amount in unsaturated oleic and linoleic acids. In conclusion the effect of gamma radiation on walnut and pantheistic appears nutritionally significant in pistachio nut and less in walnut. More investigations are necessary after a long time of storage to prove their intact nutritional quality and eventually their good digestibility. (author). 6 refs.

  5. Fruit development, pigmentation and biochemical properties of wax apple as affected by localized Application of GA3 under field conditions

    Directory of Open Access Journals (Sweden)

    Mohammad Moneruzzaman Khandaker

    2013-02-01

    Full Text Available This study investigated the effects of gibberellin (GA3 on the fruit development, pigmentation and biochemical properties of wax apple. The wax apple trees were rubbing treated with 0, 20, 50 and 100 mgGA3/l under field conditions. The localized application (rubbing of 50 mg GA3/l significantly increased the fruit set, fruit length and diameter, color development, weight and yieldcompared to the control. In addition, GA3 treatments significantly reduced the fruit drop. With regard to the fruit quality, 50 mg/l GA3 treatment increased the juice content, K+, TSS, total sugar and sugar acid ratio of wax apple fruits. In addition, higher vitamin C, phenol, flavonoid, anthocyanin, carotene content, PAL and antioxidant activities were recorded in the treated fruits. There was a positive correlation between the peel colour and TSS content and between the PAL activity and anthocyanin formation in the GA3-treated fruit. It was concluded that rubbing with 50 mg/L GA3 at inflorescence developing point of phloem once a week from the tiny inflorescence bud until the flower opening resulted in better yield and quality of wax apple fruits and could be an effective technique to safe the environment from excessive spray.

  6. Soil restoration under pasture after lignite mining - management effects on soil biochemical properties and their relationships with herbage yields

    Energy Technology Data Exchange (ETDEWEB)

    Ross, D.J.; Speir, T.W.; Cowling, J.C.; Feltham, C.W. (DSIR, Lower Hutt (New Zealand))

    1992-01-01

    The recovery of soil biochemical properties under grazed, grass-clover pasture after simulated lignite mining was studied over a 5-year period in a mesic Typic Dystrochrept soil at Waimumu, Southland, New Zealand. Restoration procedures involved four replacement treatments, after A,B and C horizon materials had been separately removed, from all except the control, and stockpiled for 2-3 weeks. Replacement treatment markedly influenced the recovery of herbage production and soil organic C and total N contents, N mineralization, microbial biomass (as indicated by mineral-N flush) and invertase and sulphatase activities. The effectiveness of replacement treatments decreased in the order: 1. control (no stripping or replacement). 2. A,B and C horizon materials replaced in the same order. 3. A,B and C horizon materials each mixed with an equal amount of siltstone overburden and replaced in order, 4. A and B horizon materials mixed before replacing over C horizon materials. Ripping increased herbage production, net N mineralization and microbial biomass. Fertilizer N also stimulated herbage production but depressed clover growth. Increases in soil invertase and, to a lesser extent, sulphatase activity were closely related to changes in herbage production. Microbial biomass increased more rapidly than soil organic C in early stages in the trial. Rates of net N mineralization suggest that N availability would have limited pasture growth.

  7. Seasonal Patterns of Soil Respiration and Related Soil Biochemical Properties under Nitrogen Addition in Winter Wheat Field

    Science.gov (United States)

    Liang, Guopeng; Houssou, Albert A.; Wu, Huijun; Cai, Dianxiong; Wu, Xueping; Gao, Lili; Li, Jing; Wang, Bisheng; Li, Shengping

    2015-01-01

    Understanding the changes of soil respiration under increasing N fertilizer in cropland ecosystems is crucial to accurately predicting global warming. This study explored seasonal variations of soil respiration and its controlling biochemical properties under a gradient of Nitrogen addition during two consecutive winter wheat growing seasons (2013–2015). N was applied at four different levels: 0, 120, 180 and 240 kg N ha-1 year-1 (denoted as N0, N12, N18 and N24, respectively). Soil respiration exhibited significant seasonal variation and was significantly affected by soil temperature with Q10 ranging from 2.04 to 2.46 and from 1.49 to 1.53 during 2013–2014 and 2014–2015 winter wheat growing season, respectively. Soil moisture had no significant effect on soil respiration during 2013–2014 winter wheat growing season but showed a significant and negative correlation with soil respiration during 2014–2015 winter wheat growing season. Soil respiration under N24 treatment was significantly higher than N0 treatment. Averaged over the two growing seasons, N12, N18 and N24 significantly increased soil respiration by 13.4, 16.4 and 25.4% compared with N0, respectively. N addition also significantly increased easily extractable glomalin-related soil protein (EEG), soil organic carbon (SOC), total N, ammonium N and nitrate N contents. In addition, soil respiration was significantly and positively correlated with β-glucosidase activity, EEG, SOC, total N, ammonium N and nitrate N contents. The results indicated that high N fertilization improved soil chemical properties, but significantly increased soil respiration. PMID:26629695

  8. Seasonal Patterns of Soil Respiration and Related Soil Biochemical Properties under Nitrogen Addition in Winter Wheat Field.

    Science.gov (United States)

    Liang, Guopeng; Houssou, Albert A; Wu, Huijun; Cai, Dianxiong; Wu, Xueping; Gao, Lili; Li, Jing; Wang, Bisheng; Li, Shengping

    2015-01-01

    Understanding the changes of soil respiration under increasing N fertilizer in cropland ecosystems is crucial to accurately predicting global warming. This study explored seasonal variations of soil respiration and its controlling biochemical properties under a gradient of Nitrogen addition during two consecutive winter wheat growing seasons (2013-2015). N was applied at four different levels: 0, 120, 180 and 240 kg N ha(-1) year(-1) (denoted as N0, N12, N18 and N24, respectively). Soil respiration exhibited significant seasonal variation and was significantly affected by soil temperature with Q10 ranging from 2.04 to 2.46 and from 1.49 to 1.53 during 2013-2014 and 2014-2015 winter wheat growing season, respectively. Soil moisture had no significant effect on soil respiration during 2013-2014 winter wheat growing season but showed a significant and negative correlation with soil respiration during 2014-2015 winter wheat growing season. Soil respiration under N24 treatment was significantly higher than N0 treatment. Averaged over the two growing seasons, N12, N18 and N24 significantly increased soil respiration by 13.4, 16.4 and 25.4% compared with N0, respectively. N addition also significantly increased easily extractable glomalin-related soil protein (EEG), soil organic carbon (SOC), total N, ammonium N and nitrate N contents. In addition, soil respiration was significantly and positively correlated with β-glucosidase activity, EEG, SOC, total N, ammonium N and nitrate N contents. The results indicated that high N fertilization improved soil chemical properties, but significantly increased soil respiration.

  9. Electronic and chemical properties of barium and indium clusters

    International Nuclear Information System (INIS)

    Onwuagba, B.N.

    1992-11-01

    The ground state electronic and chemical properties of divalent barium and trivalent indium are investigated in a self-consistent manner using the spin-polarized local density approximation in the framework of Density Functional Theory. A jellium model is adopted in the spirit of Gunnarsson and Lundqvist exchange and correlation energies and the calculated properties primarily associated with the s-p orbitals in barium and p orbitals in indium provide deepened insight towards the understanding of the mechanisms to the magic numbers in both clusters. (author). 21 refs, 5 figs

  10. Exploring the morphological and electronic properties of silicene superstructures

    International Nuclear Information System (INIS)

    Grazianetti, Carlo; Chiappe, Daniele; Cinquanta, Eugenio; Tallarida, Grazia; Fanciulli, Marco; Molle, Alessandro

    2014-01-01

    Silicene, the Si counterpart of graphene, grows on Ag(111) forming domains. Investigation, by means of scanning tunneling microscopy, of morphological properties is carried out by considering post-deposition process. Particular attention is here addressed to the post-deposition annealing temperature, which plays an important role in determining the resulting morphology. On the other hand, electronic properties are probed by scanning tunneling spectroscopy and a position-dependent local density of states results, which can be understood in terms of symmetry breaking in the honeycomb lattice.

  11. Exploring the morphological and electronic properties of silicene superstructures

    Energy Technology Data Exchange (ETDEWEB)

    Grazianetti, Carlo, E-mail: carlo.grazianetti@mdm.imm.cnr.it [Laboratorio MDM, IMM-CNR, via C. Olivetti 2, I-20864 Agrate Brianza, MB (Italy); Dipartimento di Scienza dei Materiali, Università degli Studi di Milano Bicocca, via R. Cozzi 53, I-20126 Milano, MI (Italy); Chiappe, Daniele; Cinquanta, Eugenio; Tallarida, Grazia [Laboratorio MDM, IMM-CNR, via C. Olivetti 2, I-20864 Agrate Brianza, MB (Italy); Fanciulli, Marco [Laboratorio MDM, IMM-CNR, via C. Olivetti 2, I-20864 Agrate Brianza, MB (Italy); Dipartimento di Scienza dei Materiali, Università degli Studi di Milano Bicocca, via R. Cozzi 53, I-20126 Milano, MI (Italy); Molle, Alessandro, E-mail: alessandro.molle@mdm.imm.cnr.it [Laboratorio MDM, IMM-CNR, via C. Olivetti 2, I-20864 Agrate Brianza, MB (Italy)

    2014-02-01

    Silicene, the Si counterpart of graphene, grows on Ag(111) forming domains. Investigation, by means of scanning tunneling microscopy, of morphological properties is carried out by considering post-deposition process. Particular attention is here addressed to the post-deposition annealing temperature, which plays an important role in determining the resulting morphology. On the other hand, electronic properties are probed by scanning tunneling spectroscopy and a position-dependent local density of states results, which can be understood in terms of symmetry breaking in the honeycomb lattice.

  12. Microscopical Studies of Structural and Electronic Properties of Semiconductors

    CERN Multimedia

    2002-01-01

    The electronic and structural properties of point defects in semiconductors, e.g. radiation defects, impurities or passivating defects can excellently be studied by the hyperfine technique of Perturbed Angular Correlation (PAC). The serious limitation of this method, the small number of chemically different radioactive PAC probe atoms can be widely overcome by means of ISOLDE. Providing shortliving isotopes, which represent common dopants as well as suitable PAC probe atoms, the ISOLDE facility enables a much broader application of PAC to problems in semiconductor physics.\\\\ Using the probe atom $^{111m}$ Cd , the whole class of III-V compounds becomes accessible for PAC investigations. First successful experiments in GaAs, InP and GaP have been performed, concerning impurity complex formation and plasma induced defects. In Si and Ge, the electronic properties~-~especially their influence on acceptor-donor interaction~-~could be exemplarily st...

  13. Study of electronic and structural properties of CaS

    International Nuclear Information System (INIS)

    Mirfenderski, M.; Akbarzdeh, H.; Mokhtari, A.

    2003-01-01

    The electronic and structural properties of CaS are calculated using full potential linearized augmented plane wave method within the local density approximation and generalized gradient approximation for the exchange -correlation energy. For both structures, NaCl structure (B1) and CsCl structure (B2), the obtained values for lattice parameters, bulk modulus and its pressure derivative and transition pressure are in reasonable agreement with the experimental values. For electronic properties, the obtained value for band gap is smaller than the experimental value as well as other calculated results based on density functional theory. Engel and Vosko calculated an exchange potential for some atoms within the so-called optimize-potential model and then used the virial relation and constructed a new exchange-correlation functional. We used that functional and obtained reasonable results for band gap. Finally we investigated the possibility for a third phase ( Zinc Blend structure) for this crystal

  14. Structural and electronic properties of GaAsBi

    International Nuclear Information System (INIS)

    Achour, H.; Louhibi, S.; Amrani, B.; Tebboune, A.; Sekkal, N.

    2008-05-01

    The structural and electronic properties of the GaAs 1-x Bi x ternary alloy are investigated by means of two first principles and full potential methods, the linear augmented plane waves (FPLAPW) method and a recent version of the full potential linear muffin-tin orbitals method (FPLMTO) which enables an accurate treatment of the interstitial regions. In particular, we have found that the maximal GaBi mole fraction x for which GaBixAs 1-x remains a semiconductor is probably around x = 0.5. The electronic properties of (GaAs) m /(GaBi) n quantum well superlattices (SLs) have also been calculated and it is found that such SLs are semiconductors when m is larger or equal to n. (author)

  15. Elastic properties and electron transport in InAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Migunov, Vadim

    2013-02-22

    The electron transport and elastic properties of InAs nanowires grown by chemical vapor deposition on InAs (001) substrate were studied experimentally, in-situ in a transmission electron microscope (TEM). A TEM holder allowing the measurement of a nanoforce while simultaneous imaging nanowire bending was used. Diffraction images from local areas of the wire were recorded to correlate elastic properties with the atomic structure of the nanowires. Another TEM holder allowing the application of electrical bias between the nanowire and an apex of a metallic needle while simultaneous imaging the nanowire in TEM or performing electron holography was used to detect mechanical vibrations in mechanical study or holographical observation of the nanowire inner potential in the electron transport studies. The combination of the scanning probe methods with TEM allows to correlate the measured electric and elastic properties of the nanowires with direct identification of their atomic structure. It was found that the nanowires have different atomic structures and different stacking fault defect densities that impacts critically on the elastic properties and electric transport. The unique methods, that were applied in this work, allowed to obtain dependencies of resistivity and Young's modulus of left angle 111 right angle -oriented InAs nanowires on defect density and diameter. It was found that the higher is the defect density the higher are the resistivity and the Young's modulus. Regarding the resistivity, it was deduced that the stacking faults increase the scattering of the electrons in the nanowire. These findings are consistent with the literature, however, the effect described by the other groups is not so pronounced. This difference can be attributed to the significant incompleteness of the physical models used for the data analysis. Regarding the elastic modulus, there are several mechanisms affecting the elasticity of the nanowires discussed in the thesis. It

  16. Electronic structure and magnetic properties of Pd sub(3)Fe

    International Nuclear Information System (INIS)

    Kuhnen, C.A.

    1988-01-01

    In this work we study the electronic and magnetic properties of the Pd sub(3)Fe alloy. For the ordered phase of Pd sub(3)Fe we employed the Linear Muffin-Tin Orbitals Method, with the atomic sphere approximation, which is a first principles method and includes spin polarization. The theoretical results for the thermal and magnetic properties show good agreement with experience. Here we explain the formation of the localized magnetic moments from completely itinerant electrons. We investigate the influence of the hydrogen in the physical properties of the compound Pd sub(3)Fe, where we obtain a drastic reduction in the magnetic moments at the Pd and Fe sites. This reduction is confirmed by experience. The self consistent potentials of the Pd sub(3)Fe compound were used for an analysis of the influence of the disorder in the electronic structure of Pd sub(3)Fe alloy. To this end, we employ a spin polarized version of the Green's Function Method with the Coherent Potential Approximation (or KKR-CPA). The results obtained show that in random ferromagnetic alloys different degrees of disorder occurs for the different spin directions. The formation of the magnetic moments in these alloys were explained from the existence of 'virtual crystal' states for spin up electrons and 'split band' states for spin down electrons. Finally we employ the muffin-tin orbitals to calculate the X-ray photoemission spectra of the Pd sub(3)Fe and Pd sub(3)FeH compounds, which allows us a direct comparison between theory and experiment. (author)

  17. Size-dependent electronic properties of metal nanostructures

    Indian Academy of Sciences (India)

    Table of contents. Size-dependent electronic properties of metal nanostructures · Slide 2 · Slide 3 · Slide 4 · Slide 5 · Slide 6 · Slide 7 · Slide 8 · Slide 9 · Slide 10 · Slide 11 · Slide 12 · Slide 13 · Slide 14 · Slide 15 · Slide 16 · Slide 17 · Slide 18 · Slide 19 · Nanocrystalline film at liquid-liquid interface · Slide 21 · Slide 22.

  18. Structural and electronic properties of hydrosilylated silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Baumer, A.

    2005-11-15

    The structural and electronic properties of alkyl-terminated Si surfaces prepared by thermallyinduced hydrosilylation have been studied in detail in the preceding chapters. Various surfaces have been used for the functionalization ranging from crystalline Si over amorphous hydrogenated Si to nanoscaled materials such as Si nanowires and nanoparticles. In each case, the alkyl-terminated surfaces have been compared to the native oxidized and H-terminated surfaces. (orig.)

  19. Local electronic and electrical properties of functionalized graphene nano flakes

    International Nuclear Information System (INIS)

    Chutia, Arunabhiram; Sahnoun, Riadh; Deka, Ramesh C.; Zhu, Zhigang; Tsuboi, Hideyuki; Takaba, Hiromitsu; Miyamoto, Akira

    2011-01-01

    Based on experimental findings models of amorphous graphene related carbon materials were generated using graphene nano flakes. On the optimized structures detailed local electronic properties were investigated using density functional theory. The electrical conductivities of all these models were also estimated using an in-house program based on tight-binding method. The calculated electrical conductivity values of all the models agreed well with the trend of calculated energy gap and graphitic character.

  20. Comparing Effects Of GAMMA And Electron Beam Irradiation On Microbiological And Biochemical Characters Of Selected Egyptian Aromatic Herbs

    International Nuclear Information System (INIS)

    FARAG, S.A.; YUSSEF, B.M.; SHAMS EL DIEEN, N.M.; ABDALLA, M.

    2009-01-01

    Selected Egyptian aromatic herbs (AH) which face demand for exporting abroad, such as spearmint (Mentha viridis Linn.), rosemary (Rosmarinus officinalis L.) and marjoram (Origanum majorana L.), were exposed to gamma and electron beam (EB) irradiation at different doses (5 and 10 kGy). The evaluation of irradiation efficiency was based on microbiological and biochemical studies including changes in volatile compounds and antioxidative activity. The microbiological assay revealed presence of high load levels in raw AH with log of total bacteria of rosemary (6.862 cfu.g-1) and spearmint (6.762 cfu.g -1 ) while marjoram was the lowest one (5.771 cfu.g -1 ). The highest levels of the log of total molds and yeast counts were observed in marjoram (5.097 cfu.g -1 ) while the less levels were observed in rosemary and spearmint. Using gamma irradiation was more effective than EB in decontamination of microbes either in reducing numbers to safe levels at 5 kGy or completely elimination at high dose (10 kGy) in all tested samples. Some specific bacteria were present in AH such as Enterococcus faecalis, Bacillus cereus and Clostridium perfringens at different levels whereas the log of E. faecalis was detected only in marjoram and spearmint with heavy load as 4.554 and 3.427 cfu.g -1 , respectively, while rosemary was less than 2 cfu.g -1 . Irradiation with both sources at 5 kGy reduced the count by about 2 log cycles in marjoram and 1 log cycle in spearmint. No colonies of the same microbe were detected at high dose (10 kGy) in all herbs with exception of marjoram. The log of B. cereus contamination was higher in spearmint than marjoram then rosemary. Irradiation of AH at 5 kGy reduced these values whereas high dose (10 kGy) caused complete elimination of B. cereus.GLC analysis of AH volatile oils showed presence of 22 compounds in spearmint included mainly carvon specific smells of spearmint besides monoterpens as α- -pinen (1.6%), Β-pinen (2.06%), limonene (4.75%). Also

  1. Electronic and magnetic properties of pristine and hydrogenated borophene nanoribbons

    Science.gov (United States)

    Meng, Fanchen; Chen, Xiangnan; Sun, Songsong; He, Jian

    2017-07-01

    The groundbreaking works in graphene and graphene nanoribbons (GNRs) over the past decade, and the very recent discovery of borophene naturally draw attention to the yet-to-be-explored borophene nanoribbons (BNRs). We herein report a density functional theory (DFT) study of the electronic and magnetic properties of BNRs. The foci are the impact of orientation (denoted as BxNRs and ByNRs with their respective periodic orientations along x- and y-axis), ribbon width (Nx, Ny=4-15), and hydrogenation effects on the geometric, electronic and magnetic properties of BNRs. We found that the anisotropic quasi-planar geometric structure of BNR and the edge states largely govern its electronic and magnetic properties. In particular, pristine ByNRs adopt a magnetic ground state, either anti-ferromagnetic (AFM) or ferromagnetic (FM) depending on the ribbon width, while pristine BxNRs are non-magnetic (NM). Upon hydrogenation, all BNRs exhibit NM. Interestingly, both pristine and hydrogenated ByNRs undergo a metal-semiconductor-metal transition at Ny=7, while all BxNRs remain metallic.

  2. Electronic properties of carbon nanotubes with polygonized cross sections

    International Nuclear Information System (INIS)

    Charlier, J.; Lambin, P.; Ebbesen, T.

    1996-01-01

    The electronic properties of carbon nanotubes having polygonized cross sections instead of purely circular ones, such as recently observed using transmission electron microscopy, are investigated with plane-wave ab initio pseudopotential local-density-functional calculations and simple tight-binding models. Strong σ * -π * hybridization effects occur in zigzag nanotubes due to the high curvature located near the edges of the polygonal cross-section prism. These effects, combined with a lowering of symmetry, dramatically affect the electronic properties of the nanotubes. It is found that modified low-lying conduction-band states are introduced either into the bandgap of insulating nanotubes, or below the degenerate states that form the top of the valence band of metallic nanotubes, leading the corresponding nanostructures to be metals, semimetals, or at least very-small-gap semiconductors. The degree of the polygon representing the cross section of the tube, and the sharpness of the edge angles, are found to be major factors in the hybridization effect, and consequently govern the electronic behavior at the Fermi level. copyright 1996 The American Physical Society

  3. Organic and inorganic amendment application on mercury-polluted soils: effects on soil chemical and biochemical properties.

    Science.gov (United States)

    García-Sánchez, Mercedes; Klouza, Martin; Holečková, Zlata; Tlustoš, Pavel; Száková, Jiřina

    2016-07-01

    On the basis of a previous study performed in our laboratory, the use of organic and inorganic amendments can significantly modify the Hg mobility in soil. We have compared the effectiveness of organic and inorganic amendments such as digestate and fly ash, respectively, reducing the Hg mobility in Chernozem and Luvisol soils differing in their physicochemical properties. Hence, the aim of this work was to compare the impact of digestate and fly ash application on the chemical and biochemical parameters in these two mercury-contaminated soils in a model batch experiment. Chernozem and Luvisol soils were artificially contaminated with Hg and then incubated under controlled conditions for 21 days. Digestate and fly ash were applied to both soils in a dose of 10 and 1.5 %, respectively, and soil samples were collected after 1, 7, 14, and 21 days of incubation. The presence of Hg in both soils negatively affected to processes such as nitrification, provoked a decline in the soil microbial biomass C (soil microbial biomass C (MBC)), and the microbial activities (arylsulfatase, and β-glucosaminidase) in both soils. Meanwhile, the digestate addition to Chernozem and Luvisol soils contaminated with Hg improved the soil chemical properties (pH, dissolved organic carbon (DOC), N (Ntot), inorganic-N forms (N-NH4 (+) and N-NO3 (-))), as consequence of high content in C and N contained in digestate. Likewise, the soil MBC and soil microbial activities (dehydrogenase, arylsulfatase, and β-glucosaminidase) were greatly enhanced by the digestate application in both soils. In contrast, fly ash application did not have a remarkable positive effect when compared to digestate in Chernozem and Luvisol soil contaminated with mercury. These results may indicate that the use of organic amendments such as digestate considerably improved the soil health in Chernozem and Luvisol compared with fly ash, alleviating the detrimental impact of Hg. Probably, the chemical properties present in

  4. Improvement of carbon fiber surface properties using electron beam irradiation

    International Nuclear Information System (INIS)

    Pino, E.S.; Machado, L.D.B.; Giovedi, C.

    2007-01-01

    Carbon fiber-reinforced advance composites have been used for structural applications, mainly on account of their mechanical properties. The main factor for a good mechanical performance of carbon fiber-reinforced composite is the interfacial interaction between its components, which are carbon fiber and polymeric matrix. The aim of this study is to improve the surface properties of the carbon fiber using ionizing radiation from an electron beam to obtain better adhesion properties in the resultant composite. EB radiation was applied on the carbon fiber itself before preparing test specimens for the mechanical tests. Experimental results showed that EB irradiation improved the tensile strength of carbon fiber samples. The maximum value in tensile strength was reached using doses of about 250 kGy. After breakage, the morphology aspect of the tensile specimens prepared with irradiated and non-irradiated car- bon fibers were evaluated. SEM micrographs showed modifications on the carbon fiber surface. (authors)

  5. Electronic structure and optical properties of AIN under high pressure

    International Nuclear Information System (INIS)

    Li Zetao; Dang Suihu; Li Chunxia

    2011-01-01

    We have calculated the electronic structure and optical properties of Wurtzite structure AIN under different high pressure with generalized gradient approximation (GGA) in this paper. The total energy, density of state, energy band structure and optical absorption and reflection properties under high pressure are calculated. By comparing the changes of the energy band structure, we obtained AIN phase transition pressure for 16.7 GPa, which is a direct band structure transforming to an indirect band structure. Meanwhile, according to the density of states distribution and energy band structure, we analyzed the optical properties of AIN under high-pressure, the results showed that the absorption spectra moved from low-energy to high-energy. (authors)

  6. Electronic and Optical Properties of Twisted Bilayer Graphene

    Science.gov (United States)

    Huang, Shengqiang

    The ability to isolate single atomic layers of van der Waals materials has led to renewed interest in the electronic and optical properties of these materials as they can be fundamentally different at the monolayer limit. Moreover, these 2D crystals can be assembled together layer by layer, with controllable sequence and orientation, to form artificial materials that exhibit new features that are not found in monolayers nor bulk. Twisted bilayer graphene is one such prototype system formed by two monolayer graphene layers placed on top of each other with a twist angle between their lattices, whose electronic band structure depends on the twist angle. This thesis presents the efforts to explore the electronic and optical properties of twisted bilayer graphene by Raman spectroscopy and scanning tunneling microscopy measurements. We first synthesize twisted bilayer graphene with various twist angles via chemical vapor deposition. Using a combination of scanning tunneling microscopy and Raman spectroscopy, the twist angles are determined. The strength of the Raman G peak is sensitive to the electronic band structure of twisted bilayer graphene and therefore we use this peak to monitor changes upon doping. Our results demonstrate the ability to modify the electronic and optical properties of twisted bilayer graphene with doping. We also fabricate twisted bilayer graphene by controllable stacking of two graphene monolayers with a dry transfer technique. For twist angles smaller than one degree, many body interactions play an important role. It requires eight electrons per moire unit cell to fill up each band instead of four electrons in the case of a larger twist angle. For twist angles smaller than 0.4 degree, a network of domain walls separating AB and BA stacking regions forms, which are predicted to host topologically protected helical states. Using scanning tunneling microscopy and spectroscopy, these states are confirmed to appear on the domain walls when inversion

  7. Manganites in Perovskite Superlattices: Structural and Electronic Properties

    KAUST Repository

    Jilili, Jiwuer

    2016-07-13

    Perovskite oxides have the general chemical formula ABO3, where A is a rare-earth or alkali-metal cation and B is a transition metal cation. Perovskite oxides can be formed with a variety of constituent elements and exhibit a wide range of properties ranging from insulators, metals to even superconductors. With the development of growth and characterization techniques, more information on their physical and chemical properties has been revealed, which diversified their technological applications. Perovskite manganites are widely investigated compounds due to the discovery of the colossal magnetoresistance effect in 1994. They have a broad range of structural, electronic, magnetic properties and potential device applications in sensors and spintronics. There is not only the technological importance but also the need to understand the fundamental mechanisms of the unusual magnetic and transport properties that drive enormous attention. Manganites combined with other perovskite oxides are gaining interest due to novel properties especially at the interface, such as interfacial ferromagnetism, exchange bias, interfacial conductivity. Doped manganites exhibit diverse electrical properties as compared to the parent compounds. For instance, hole doped La0.7Sr0.3MnO3 is a ferromagnetic metal, whereas LaMnO3 is an antiferromagnetic insulator. Since manganites are strongly correlated systems, heterojunctions composed of manganites and other perovskite oxides are sunject to complex coupling of the spin, orbit, charge, and lattice degrees of freedom and exhibit unique electronic, magnetic, and transport properties. Electronic reconstructions, O defects, doping, intersite disorder, magnetic proximity, magnetic exchange, and polar catastrophe are some effects to explain these interfacial phenomena. In our work we use first-principles calculations to study the structural, electronic, and magnetic properties of manganite based superlattices. Firstly, we investigate the electronic

  8. Hydration effects on the electronic properties of eumelanin building blocks

    International Nuclear Information System (INIS)

    Assis Oliveira, Leonardo Bruno; Fonseca, Tertius L.; Costa Cabral, Benedito J.; Coutinho, Kaline; Canuto, Sylvio

    2016-01-01

    Theoretical results for the electronic properties of eumelanin building blocks in the gas phase and water are presented. The building blocks presently investigated include the monomeric species DHI (5,6-dihydroxyindole) or hydroquinone (HQ), DHICA (5,6-dihydroxyindole-2-carboxylic acid), indolequinone (IQ), quinone methide (MQ), two covalently bonded dimers [HM ≡ HQ + MQ and IM ≡ IQ + MQ], and two tetramers [HMIM ≡ HQ + IM, IMIM ≡ IM + IM]. The electronic properties in water were determined by carrying out sequential Monte Carlo/time dependent density functional theory calculations. The results illustrate the role played by hydrogen bonding and electrostatic interactions in the electronic properties of eumelanin building blocks in a polar environment. In water, the dipole moments of monomeric species are significantly increased ([54–79]%) relative to their gas phase values. Recently, it has been proposed that the observed enhancement of the higher-energy absorption intensity in eumelanin can be explained by excitonic coupling among eumelanin protomolecules [C.-T. Chen et al., Nat. Commun. 5, 3859 (2014)]. Here, we are providing evidence that for DHICA, IQ, and HMIM, the electronic absorption toward the higher-energy end of the spectrum ([180–220] nm) is enhanced by long-range Coulombic interactions with the water environment. It was verified that by superposing the absorption spectra of different eumelanin building blocks corresponding to the monomers, dimers, and tetramers in liquid water, the behaviour of the experimental spectrum, which is characterised by a nearly monotonic decay from the ultraviolet to the infrared, is qualitatively reproduced. This result is in keeping with a “chemical disorder model,” where the broadband absorption of eumelanin pigments is determined by the superposition of the spectra associated with the monomeric and oligomeric building blocks.

  9. Hydration effects on the electronic properties of eumelanin building blocks

    Energy Technology Data Exchange (ETDEWEB)

    Assis Oliveira, Leonardo Bruno [Instituto de Física da Universidade Federal de Goiás, 74690-900 Goiânia, GO (Brazil); Departamento de Física - CEPAE, Universidade Federal de Goiás, 74690-900 Goiânia, GO (Brazil); Escola de Ciências Exatas e da Computação, Pontifícia Universidade Católica de Goiás, 74605-010 Goiânia, GO (Brazil); Fonseca, Tertius L. [Instituto de Física da Universidade Federal de Goiás, 74690-900 Goiânia, GO (Brazil); Costa Cabral, Benedito J., E-mail: ben@cii.fc.ul.pt [Grupo de Física Matemática da Universidade de Lisboa and Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa (Portugal); Coutinho, Kaline; Canuto, Sylvio [Instituto de Física da Universidade de São Paulo, CP 66318, 05314-970 São Paulo, SP (Brazil)

    2016-08-28

    Theoretical results for the electronic properties of eumelanin building blocks in the gas phase and water are presented. The building blocks presently investigated include the monomeric species DHI (5,6-dihydroxyindole) or hydroquinone (HQ), DHICA (5,6-dihydroxyindole-2-carboxylic acid), indolequinone (IQ), quinone methide (MQ), two covalently bonded dimers [HM ≡ HQ + MQ and IM ≡ IQ + MQ], and two tetramers [HMIM ≡ HQ + IM, IMIM ≡ IM + IM]. The electronic properties in water were determined by carrying out sequential Monte Carlo/time dependent density functional theory calculations. The results illustrate the role played by hydrogen bonding and electrostatic interactions in the electronic properties of eumelanin building blocks in a polar environment. In water, the dipole moments of monomeric species are significantly increased ([54–79]%) relative to their gas phase values. Recently, it has been proposed that the observed enhancement of the higher-energy absorption intensity in eumelanin can be explained by excitonic coupling among eumelanin protomolecules [C.-T. Chen et al., Nat. Commun. 5, 3859 (2014)]. Here, we are providing evidence that for DHICA, IQ, and HMIM, the electronic absorption toward the higher-energy end of the spectrum ([180–220] nm) is enhanced by long-range Coulombic interactions with the water environment. It was verified that by superposing the absorption spectra of different eumelanin building blocks corresponding to the monomers, dimers, and tetramers in liquid water, the behaviour of the experimental spectrum, which is characterised by a nearly monotonic decay from the ultraviolet to the infrared, is qualitatively reproduced. This result is in keeping with a “chemical disorder model,” where the broadband absorption of eumelanin pigments is determined by the superposition of the spectra associated with the monomeric and oligomeric building blocks.

  10. Biochemical characterization and anti-inflammatory properties of an isothiocyanate-enriched moringa (Moringa oleifera) seed extract.

    Science.gov (United States)

    Jaja-Chimedza, Asha; Graf, Brittany L; Simmler, Charlotte; Kim, Youjin; Kuhn, Peter; Pauli, Guido F; Raskin, Ilya

    2017-01-01

    Moringa oleifera Lam. is a tropical plant, used for centuries as food and traditional medicine. The aim of this study was to develop, validate and biochemically characterize an isothiocyanate-enriched moringa seed extract (MSE), and to compare the anti-inflammatory effects of MSE-containing moringa isothiocyanate-1 (MIC-1) with a curcuminoid-enriched turmeric extract (CTE), and a material further enriched in its primary phytochemical, curcumin (curcumin-enriched material; CEM). MSE was prepared by incubating ground moringa seeds with water to allow myrosinase-catalyzed enzymatic formation of bioactive MIC-1, the predominant isothiocyanate in moringa seeds. Optimization of the extraction process yielded an extract of 38.9% MIC-1. Phytochemical analysis of MSE revealed the presence of acetylated isothiocyanates, phenolic glycosides unique to moringa, flavonoids, fats and fatty acids, proteins and carbohydrates. MSE showed a reduction in the carrageenan-induced rat paw edema (33% at 500 mg/kg MIC-1) comparable to aspirin (27% at 300 mg/kg), whereas CTE did not have any significant effect. In vitro, MIC-1 at 1 μM significantly reduced the production of nitric oxide (NO) and at 5 μM, the gene expression of LPS-inducible nitric oxide synthase (iNOS) and interleukins 1β and 6 (IL-1β and IL-6), whereas CEM did not show any significant activity at all concentrations tested. MIC-1 (10μM) was also more effective at upregulating the nuclear factor (erythroid-derived 2)-like 2 (Nrf2) target genes NAD(P)H:quinone oxidoreductase 1 (NQO1), glutathione S-transferase pi 1 (GSTP1), and heme oxygenase 1 (HO1) than the CEM. Thus, in contrast to CTE and CEM, MSE and its major isothiocyanate MIC-1 displayed strong anti-inflammatory and antioxidant properties in vivo and in vitro, making them promising botanical leads for the mitigation of inflammatory-mediated chronic disorders.

  11. Biochemical characterization and anti-inflammatory properties of an isothiocyanate-enriched moringa (Moringa oleifera seed extract.

    Directory of Open Access Journals (Sweden)

    Asha Jaja-Chimedza

    Full Text Available Moringa oleifera Lam. is a tropical plant, used for centuries as food and traditional medicine. The aim of this study was to develop, validate and biochemically characterize an isothiocyanate-enriched moringa seed extract (MSE, and to compare the anti-inflammatory effects of MSE-containing moringa isothiocyanate-1 (MIC-1 with a curcuminoid-enriched turmeric extract (CTE, and a material further enriched in its primary phytochemical, curcumin (curcumin-enriched material; CEM. MSE was prepared by incubating ground moringa seeds with water to allow myrosinase-catalyzed enzymatic formation of bioactive MIC-1, the predominant isothiocyanate in moringa seeds. Optimization of the extraction process yielded an extract of 38.9% MIC-1. Phytochemical analysis of MSE revealed the presence of acetylated isothiocyanates, phenolic glycosides unique to moringa, flavonoids, fats and fatty acids, proteins and carbohydrates. MSE showed a reduction in the carrageenan-induced rat paw edema (33% at 500 mg/kg MIC-1 comparable to aspirin (27% at 300 mg/kg, whereas CTE did not have any significant effect. In vitro, MIC-1 at 1 μM significantly reduced the production of nitric oxide (NO and at 5 μM, the gene expression of LPS-inducible nitric oxide synthase (iNOS and interleukins 1β and 6 (IL-1β and IL-6, whereas CEM did not show any significant activity at all concentrations tested. MIC-1 (10μM was also more effective at upregulating the nuclear factor (erythroid-derived 2-like 2 (Nrf2 target genes NAD(PH:quinone oxidoreductase 1 (NQO1, glutathione S-transferase pi 1 (GSTP1, and heme oxygenase 1 (HO1 than the CEM. Thus, in contrast to CTE and CEM, MSE and its major isothiocyanate MIC-1 displayed strong anti-inflammatory and antioxidant properties in vivo and in vitro, making them promising botanical leads for the mitigation of inflammatory-mediated chronic disorders.

  12. Characterization of the Effects of Hyperbaric Oxygen on the Biochemical and Optical Properties of the Bovine Lens.

    Science.gov (United States)

    Lim, Julie C; Vaghefi, Ehsan; Li, Bo; Nye-Wood, Mitchell G; Donaldson, Paul J

    2016-04-01

    To assess the morphologic, biochemical, and optical properties of bovine lenses treated with hyperbaric oxygen. Lenses were exposed to hyperbaric nitrogen (HBN) or hyperbaric oxygen (HBO) for 5 or 15 hours, lens transparency was assessed using bright field microscopy and lens morphology was visualized using confocal microscopy. Lenses were dissected into the outer cortex, inner cortex, and core, and glutathione (GSH) and malondialdehyde (MDA) measured. Gel electrophoresis and Western blotting were used to detect high molecular weight aggregates (HMW) and glutathione mixed protein disulfides (PSSG). T2-weighted MRI was used to measure lens geometry and map the water/protein ratio to allow gradient refractive index (GRIN) profiles to be calculated. Optical modeling software calculated the change in lens optical power, and an anatomically correct model of the light pathway of the bovine eye was used to determine the effects of HBN and HBO on focal length and overall image quality. Lenses were transparent and lens morphology similar between HBN- and HBO-treated lenses. At 5- and 15-hour HBO exposure, GSH and GSSG were depleted and MDA increased in the core. Glutathione mixed protein disulfides were detected in the outer and inner cortex only with no appearance of HMW. Optical changes were detectable only with 15-hour HBO treatment with a decrease in the refractive index of the core, slightly reduced lens thickness, and an increase in optimal focal length, consistent with a hyperopic shift. This system may serve as a model to study changes that occur with advanced aging rather than nuclear cataract formation per se.

  13. Correlation properties of surface and percolation transfer of electrons

    International Nuclear Information System (INIS)

    Bakunin, O.G.

    2002-01-01

    In this work was received equation, connecting correlatively properties of surface with electrons distribution function. Usually for equilibrium is necessary a large number of collisions. Collisions are 'destroying' correlations. In case rare collisions large importance have correlations and 'memory' effects. Non-Markov's character of emitting particles by surface lead to strongly nonequilibrium condition of 'gas'. Here kinetic equation of diffusive form does not apply. Classical kinetic equation are described only conditions near to equilibrium. This work offers to use ideas anomal diffusion in phase-space. The correlation properties of surface describe by correlations of velocities of emitting electrons: B(t). We offer to use functional equation for probability collision instead of kinetic equation: ∫ 0 ν 0 W noncoll F(ν) dv = 1 - B(t). This functional allow to consider 'memory' effects. It is important for consideration of electrons and clusters near surfaces. Distribution function become direct connected with correlations. In classical Kubo-Mory theory of transfer is necessary to get nondivergences integral: D ∝ ∫ 0 ∞ B(t). In considering case we can use even 'power function'. It was used 'slow' correlation function as Kohlraush in calculations. The information about kinetics and correlations properties are containing in one functional equation. It was received solution of this equation in form Levy function: F(ν) ∝ 1/ν α exp(-1/ν). The solution of this form can not be get with help asymptotic methods of kinetic theory. Asymptotics of solution have scale-invariant character F(V) ∝ 1/V α . This indicate on fractal properties phase-space. (author)

  14. Quasiparticle properties of a coupled quantum-wire electron-phonon system

    DEFF Research Database (Denmark)

    Hwang, E. H.; Hu, Ben Yu-Kuang; Sarma, S. Das

    1996-01-01

    We study leading-order many-body effects of longitudinal-optical phonons on electronic properties of one-dimensional quantum-wire systems. We calculate the quasiparticle properties of a weakly polar one-dimensional electron gas in the presence of both electron-phonon and electron-electron interac......We study leading-order many-body effects of longitudinal-optical phonons on electronic properties of one-dimensional quantum-wire systems. We calculate the quasiparticle properties of a weakly polar one-dimensional electron gas in the presence of both electron-phonon and electron......-electron interactions, The leading-order dynamical screening approximation (GW approximation) is used to obtain the electron self-energy, the quasiparticle spectral function, and the quasiparticle damping rate in our calculation by treating electrons and phonons on an equal footing. Our theory includes effects (within...... theoretical results for quasiparticle properties....

  15. Local Electronic And Dielectric Properties at Nanosized Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Bonnell, Dawn A. [Univ. of Pennsylvania, Philadelphia, PA (United States)

    2015-02-23

    Final Report to the Department of Energy for period 6/1/2000 to 11/30/2014 for Grant # DE-FG02-00ER45813-A000 to the University of Pennsylvania Local Electronic And Dielectric Properties at Nanosized Interfaces PI: Dawn Bonnell The behavior of grain boundaries and interfaces has been a focus of fundamental research for decades because variations of structure and composition at interfaces dictate mechanical, electrical, optical and dielectric properties in solids. Similarly, the consequence of atomic and electronic structures of surfaces to chemical and physical interactions are critical due to their implications to catalysis and device fabrication. Increasing fundamental understanding of surfaces and interfaces has materially advanced technologies that directly bear on energy considerations. Currently, exciting developments in materials processing are enabling creative new electrical, optical and chemical device configurations. Controlled synthesis of nanoparticles, semiconducting nanowires and nanorods, optical quantum dots, etc. along with a range of strategies for assembling and patterning nanostructures portend the viability of new devices that have the potential to significantly impact the energy landscape. As devices become smaller the impact of interfaces and surfaces grows geometrically. As with other nanoscale phenomena, small interfaces do not exhibit the same properties as do large interfaces. The size dependence of interface properties had not been explored and understanding at the most fundamental level is necessary to the advancement of nanostructured devices. An equally important factor in the behavior of interfaces in devices is the ability to examine the interfaces under realistic conditions. For example, interfaces and boundaries dictate the behavior of oxide fuel cells which operate at extremely high temperatures in dynamic high pressure chemical environments. These conditions preclude the characterization of local properties during fuel cell

  16. Design of materials configurations for enhanced phononic and electronic properties

    Science.gov (United States)

    Daraio, Chiara

    The discovery of novel nonlinear dynamic and electronic phenomena is presented for the specific cases of granular materials and carbon nanotubes. This research was conducted for designing and constructing optimized macro-, micro- and nano-scale structural configurations of materials, and for studying their phononic and electronic behavior. Variation of composite arrangements of granular elements with different elastic properties in a linear chain-of-sphere, Y-junction or 3-D configurations led to a variety of novel phononic phenomena and interesting physical properties, which can be potentially useful for security, communications, mechanical and biomedical engineering applications. Mechanical and electronic properties of carbon nanotubes with different atomic arrangements and microstructures were also investigated. Electronic properties of Y-junction configured carbon nanotubes exhibit an exciting transistor switch behavior which is not seen in linear configuration nanotubes. Strongly nonlinear materials were designed and fabricated using novel and innovative concepts. Due to their unique strongly nonlinear and anisotropic nature, novel wave phenomena have been discovered. Specifically, violations of Snell's law were detected and a new mechanism of wave interaction with interfaces between NTPCs (Nonlinear Tunable Phononic Crystals) was established. Polymer-based systems were tested for the first time, and the tunability of the solitary waves speed was demonstrated. New materials with transformed signal propagation speed in the manageable range of 10-100 m/s and signal amplitude typical for audible speech have been developed. The enhancing of the mitigation of solitary and shock waves in 1-D chains were demonstrated and a new protective medium was designed for practical applications. 1-D, 2-D and 3-D strongly nonlinear system have been investigated providing a broad impact on the whole area of strongly nonlinear wave dynamics and creating experimental basis for new

  17. Electronic structure and physicochemical properties of selected penicillins

    Science.gov (United States)

    Soriano-Correa, Catalina; Ruiz, Juan F. Sánchez; Raya, A.; Esquivel, Rodolfo O.

    Traditionally, penicillins have been used as antibacterial agents due to their characteristics and widespread applications with few collateral effects, which have motivated several theoretical and experimental studies. Despite the latter, their mechanism of biological action has not been completely elucidated. We present a theoretical study at the Hartree-Fock and density functional theory (DFT) levels of theory of a selected group of penicillins such as the penicillin-G, amoxicillin, ampicillin, dicloxacillin, and carbenicillin molecules, to systematically determine the electron structure of full ?-lactam antibiotics. Our results allow us to analyze the electronic properties of the pharmacophore group, the aminoacyl side-chain, and the influence of the substituents (R and X) attached to the aminoacyl side-chain at 6? (in contrast with previous studies focused at the 3? substituents), and to corroborate the results of previous studies performed at the semiempirical level, solely on the ?-lactam ring of penicillins. Besides, several density descriptors are determined with the purpose of analyzing their link to the antibacterial activity of these penicillin compounds. Our results for the atomic charges (fitted to the electrostatic potential), the bond orders, and several global reactivity descriptors, such as the dipole moments, ionization potential, hardness, and the electrophilicity index, led us to characterize: the active sites, the effect of the electron-attracting substituent properties and their physicochemical features, which altogether, might be important to understand the biological activity of these type of molecules.

  18. Electronic and optical properties of diamond/organic semiconductor heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Gajewski, Wojciech; Garrido, Jose; Niedermeier, Martin; Stutzmann, Martin [Walter Schottky Institute, TU Muenchen, Am Coulombwall 3, 85748 Garching (Germany); Williams, Oliver; Haenen, Ken [Institute for Materials Research, University of Hasselt, Wetenschapspark 1, BE-3590 Diepenbeek (Belgium)

    2007-07-01

    Different diamond substrates (single crystalline: SCD, poly-crystalline: PCD and nano-crystalline: NCD) were used to investigate the electronic and optical properties of the diamond/organic semiconductor heterostructures. Layers of a poly[ethynyl-(2-decyloxy-5methoxy)benzene] - PEB, pentacene and 4-nitro-biphenyl-4-diazonium cations - Ph-Ph-NO{sub 2} were prepared by spin coating, thermal evaporation and grafting, respectively. The measurements of the electronic transport along the organic layer were performed using a Hg probe as well as Hall effect measurements in the temperature range 70-400 K. The I-V characteristics of the B-doped diamond/organic semiconductor heterostructures were measured at room temperature by means of the Hg probe. Undoped IIa and undoped PCD films were used for a study of the optical and optoelectronic properties of prepared heterostructures. The influence of the organic layer homogeneity and layer thickness on the optical properties will be discussed. Furthermore, preliminary data on perpendicular and parallel transport in the heterostructures layer will be reported.

  19. Electronic and thermodynamic properties of transition metal elements and compounds

    International Nuclear Information System (INIS)

    Haeglund, J.

    1993-01-01

    This thesis focuses on the use of band-structure calculations for studying thermodynamic properties of solids. We discuss 3d-, 4d- and 5d-transition metal carbides and nitrides. Through a detailed comparison between theoretical and experimental results, we draw conclusions on the character of the atomic bonds in these materials. We show how electronic structure calculations can be used to give accurate predictions for bonding energies. Part of the thesis is devoted to the application of the generalized gradient approximation in electronic structure calculations on transition metals. For structures with vibrational disorder, we present a method for calculating averaged phonon frequencies without using empirical information. For magnetic excitations, we show how a combined use of theoretical results and experimental data can yield information on magnetic fluctuations at high temperatures. The main results in the thesis are: Apart for an almost constant shift, theoretically calculated bonding energies for transition metal carbides and nitrides agree with experimental data or with values from analysis of thermochemical information. The electronic spectrum of transition metal carbides and nitrides can be separated into bonding, antibonding and nonbonding electronic states. The lowest enthalpy of formation for substoichiometric vanadium carbide VC 1-X at zero temperature and pressure occurs for a structure containing vacancies (x not equal to 0). The generalized gradient approximation improves theoretical calculated cohesive energies for 3d-transition metals. Magnetic phase transitions are sensitive to the description of exchange-correlation effects in electronic structure calculations. Trends in Debye temperatures can be successfully analysed in electronic structure calculations on disordered lattices. For the elements, there is a clear dependence on the crystal structure (e.g., bcc, fcc or hcp). Chromium has fluctuating local magnetic moments at temperatures well above

  20. Electronic and magnetic properties of intermetallic compound YCo5

    International Nuclear Information System (INIS)

    Zhang, G.W.; Feng, Y.P.; Ong, C.K.

    1998-01-01

    The electronic and magnetic properties of the intermetallic compound YCo 5 have been studied using density functional theory with the local spin density approximation. The calculated magnetic moments of Y, Co(2c) and Co(3g) are -0.61, 1.68 and 2.04 μ B , respectively, and the total magnetic moment is about 8.87 μ B per formula unit, which agrees well with the previous experimental results. The dependence of the magnetic moments of Y, Co(2c) and Co(3g) on the lattice spacing has been investigated. The local electronic structure of Y, Co(2c) and Co(3g) are discussed in detail. The local magnetic susceptibilities of Y, Co(2c) and Co(3g) are calculated. Based on our results, YCo 5 was found to have characteristic of a strong ferromagnet. (orig.)

  1. Electronic, phononic, and thermoelectric properties of graphyne sheets

    International Nuclear Information System (INIS)

    Sevinçli, Hâldun; Sevik, Cem

    2014-01-01

    Electron, phonon, and thermoelectric transport properties of α-, β-, γ-, and 6,6,12-graphyne sheets are compared and contrasted with those of graphene. α-, β-, and 6,6,12-graphynes, with direction dependent Dirac dispersions, have higher electronic transmittance than graphene. γ-graphyne also attains better electrical conduction than graphene except at its band gap. Vibrationally, graphene conducts heat much more efficiently than graphynes, a behavior beyond an atomic density differences explanation. Seebeck coefficients of the considered Dirac materials are similar but thermoelectric power factors decrease with increasing effective speeds of light. γ-graphyne yields the highest thermoelectric efficiency with a thermoelectric figure of merit as high as ZT = 0.45, almost an order of magnitude higher than that of graphene

  2. Electronic properties of Be and Al by Compton scattering technique

    International Nuclear Information System (INIS)

    Aguiar, J.C.; Di Rocco, H.O.

    2011-01-01

    In this work, electronic properties of beryllium and aluminum are examined by using Compton scattering technique. The method is based on the irradiation of samples using a beam narrow of mono- energetic photons of 59.54 keV product of radioactive decay of Am -241 . Scattered radiation is collected by a high resolution semiconductor detector positioned at an angle of 90°. The measured spectrum is commonly called Compton profile and contains useful information about the electronic structure of the material. The experimental results are compared with theoretical calculations such as density functional theory showing a good agreement. However, these results show some discrepancies with many libraries used in codes such as Monte Carlo simulation. Since these libraries are based on the values tabulated by Biggs, Mendelsohn and Mann 1975 thus overestimating the scattered radiation on the material. (authors) [es

  3. Electronic structure and optical properties of metal doped tetraphenylporphyrins

    Science.gov (United States)

    Shah, Esha V.; Roy, Debesh R.

    2018-05-01

    A density functional scrutiny on the structure, electronic and optical properties of metal doped tetraphenylporphyrins MTPP (M=Fe, Co, Ni) is performed. The structural stability of the molecules is evaluated based on the electronic parameters like HOMO-LUMO gap (HLG), chemical hardness (η) and binding energy of the central metal atom to the molecular frame etc. The computed UltraViolet-Visible (UV-Vis) optical absorption spectra for all the compounds are also compared. The molecular structures reported are the lowest energy configurations. The entire calculations are carried out with a widely reliable functional, viz. B3LYP with a popular basis set which includes a scaler relativistic effect, viz. LANL2DZ.

  4. Electronic transport properties of carbon nanotube metal-semiconductor-metal

    Directory of Open Access Journals (Sweden)

    F Khoeini

    2008-07-01

    Full Text Available  In this work, we study electronic transport properties of a quasi-one dimensional pure semi-conducting Zigzag Carbon Nanotube (CNT attached to semi-infinite clean metallic Zigzag CNT leads, taking into account the influence of topological defect in junctions. This structure may behave like a field effect transistor. The calculations are based on the tight-binding model and Green’s function method, in which the local density of states(LDOS in the metallic section to semi-conducting section, and muli-channel conductance of the system are calculated in the coherent and linear response regime, numerically. Also we have introduced a circuit model for the system and investigated its current. The theoretical results obtained, can be a base, for developments in designing nano-electronic devices.

  5. Electronic properties of polycrystalline graphene under large local strain

    International Nuclear Information System (INIS)

    He, Xin; Tang, Ning; Duan, Junxi; Mei, Fuhong; Meng, Hu; Lu, Fangchao; Xu, Fujun; Yang, Xuelin; Gao, Li; Wang, Xinqiang; Shen, Bo; Ge, Weikun

    2014-01-01

    To explore the transport properties of polycrystalline graphene under large tensile strain, a strain device has been fabricated using piezocrystal to load local strain onto graphene, up to 22.5%. Ionic liquid gate whose capability of tuning carrier density being much higher than that of a solid gate is used to survey the transfer characteristics of the deformed graphene. The conductance of the Dirac point and field effect mobility of electrons and holes is found to decrease with increasing strain, which is attributed to the scattering of the graphene grain boundaries, the strain induced change of band structure, and defects. However, the transport gap is still not opened. Our study is helpful to evaluate the application of graphene in stretchable electronics.

  6. Electronic, magnetic, and magnetocrystalline anisotropy properties of light lanthanides

    Science.gov (United States)

    Hackett, Timothy A.; Baldwin, D. J.; Paudyal, D.

    2017-11-01

    Theoretical understanding of interactions between localized and mobile electrons and the crystal environment in light lanthanides is important because of their key role in much needed magnetic anisotropy in permanent magnet materials that have a great impact in automobile and wind turbine applications. We report electronic, magnetic, and magnetocrystalline properties of these basic light lanthanide elements studied from advanced density functional theory (DFT) calculations. We find that the inclusion of onsite 4f electron correlation and spin orbit coupling within the full-potential band structure is needed to understand the unique magnetocrystalline properties of these light lanthanides. The onsite electron correlation, spin orbit coupling, and full potential for the asphericity of charge densities must be taken into account for the proper treatment of 4f states. We find the variation of total energy as a function of lattice constants that indicate multiple structural phases in Ce contrasting to a single stable structure obtained in other light lanthanides. The 4f orbital magnetic moments are partially quenched as a result of crystalline electric field splitting that leads to magnetocrystalline anisotropy. The charge density plots have similar asphericity and environment in Pr and Nd indicating similar magnetic anisotropy. However, Ce and Sm show completely different asphericity and environment as both orbital moments are significantly quenched. In addition, the Fermi surface structures exemplified in Nd indicate structural stability and unravel a cause of anisotropy. The calculated magnetocrystalline anisotropy energy (MAE) reveals competing c-axis and in-plane anisotropies, and also predicts possibilities of unusual structural deformations in light lanthanides. The uniaxial magnetic anisotropy is obtained in the double hexagonal closed pack structures of the most of the light lanthanides, however, the anisotropy is reduced or turned to planar in the low symmetry

  7. Study of optical and electronic properties of nickel from reflection electron energy loss spectra

    Science.gov (United States)

    Xu, H.; Yang, L. H.; Da, B.; Tóth, J.; Tőkési, K.; Ding, Z. J.

    2017-09-01

    We use the classical Monte Carlo transport model of electrons moving near the surface and inside solids to reproduce the measured reflection electron energy-loss spectroscopy (REELS) spectra. With the combination of the classical transport model and the Markov chain Monte Carlo (MCMC) sampling of oscillator parameters the so-called reverse Monte Carlo (RMC) method was developed, and used to obtain optical constants of Ni in this work. A systematic study of the electronic and optical properties of Ni has been performed in an energy loss range of 0-200 eV from the measured REELS spectra at primary energies of 1000 eV, 2000 eV and 3000 eV. The reliability of our method was tested by comparing our results with the previous data. Moreover, the accuracy of our optical data has been confirmed by applying oscillator strength-sum rule and perfect-screening-sum rule.

  8. Electronic properties of pristine and modified single-walled carbon nanotubes

    International Nuclear Information System (INIS)

    Kharlamova, M V

    2013-01-01

    The current status of research on the electronic properties of filled single-walled carbon nanotubes (SWCNTs) is reviewed. SWCNT atomic structure and electronic properties are described, and their correlation is discussed. Methods for modifying the electronic properties of SWCNTs are considered. SWCNT filling materials are systematized. Experimental and theoretical data on the electronic properties of filled SWCNTs are analyzed. Possible application areas for filled SWCNTs are explored. (reviews of topical problems)

  9. Investigation of new superhard carbon allotropes with promising electronic properties

    Energy Technology Data Exchange (ETDEWEB)

    Kvashnina, Yulia A.; Kvashnin, Alexander G. [Technological Institute for Superhard and Novel Carbon Materials, 7a Centralnaya Street, Troitsk, Moscow 142190 (Russian Federation); Moscow Institute of Physics and Technology, 9 Institutsky Lane, 141700 Dolgoprudny (Russian Federation); Sorokin, Pavel B., E-mail: psorokin@iph.krasn.ru [Technological Institute for Superhard and Novel Carbon Materials, 7a Centralnaya Street, Troitsk, Moscow 142190 (Russian Federation); Moscow Institute of Physics and Technology, 9 Institutsky Lane, 141700 Dolgoprudny (Russian Federation); Emanuel Institute of Biochemical Physics of RAS, 4 Kosigina St., Moscow 119334 (Russian Federation)

    2013-11-14

    During the systematic search for a new superhard carbon allotrope, we predicted three structures with promising physical properties. Our electronic structure calculations show that these materials have a semiconducting band gap and a high carrier mobility comparable with diamond. The simulated x-ray diffraction patterns of the proposed materials are in a good agreement with the experimental X-ray spectra. Evaluated phase transition pressures from graphite to the new proposed carbon phases are smaller than 25 GPa and close to the experimental values.

  10. Structural, electronic and optical properties of carbon nitride

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, M L [California Univ., Berkeley (United States). Dept. of Physics

    1996-05-01

    Carbon nitride was proposed as a superhard material and a structural prototype, {beta}-C{sub 3}N{sub 4}, was examined using several theoretical models. Some reports claiming experimental verifications have been made recently. The current status of the theory and experiment is reviewed, and a detailed discussion is presented of calculations of the electronic and optical properties of this material. These calculations predict that {beta}-C{sub 3}N{sub 4} will have a minimum gap which is indirect at 6.4{+-}0.5 eV. A discussion of the possibility of carbon nitride nanotubes is also presented. (orig.)

  11. Electronic properties of single-walled chiral carbon nanotube

    International Nuclear Information System (INIS)

    Mensah, S.Y.; Allotey, F.K.A.; Mensah, N.G.; Nkrumah, G.

    2001-09-01

    The electronic properties of single-walled chiral carbon nanotube has been studied using the model based on infinitely long carbon atoms wrapped along a base helix of single-walled carbon nanotubes(SWNTs). The problem is solved semiclassically, and current density J, resistivity ρ, thermopower α z , and electrical power factor P calculated. It is noted that the current density j displays negative differential conductivity, whiles the resistivity ρ increases with increasing electrical field. ρ also slowly increases at low temperatures and then gradually increases with increasing temperature. The thermopower α z shows interesting behaviour. Very intriguing is the electrical power factor which shows relatively large values. (author)

  12. Quantum oscillations and the electronic transport properties in multichain nanorings

    International Nuclear Information System (INIS)

    Racolta, D.

    2009-01-01

    We consider a system of multichain nanorings in static electric and magnetic field. The magnetic field induces characteristic phase changes. These phase shifts produce interference phenomena in the case of nanosystems for which the coherence length is larger than the sample dimension. We obtain energy solutions that are dependent on the number of sites N α characterizing a chain, of phase on the phase φ α and on the applied voltage. We found rich oscillations structures exhibited by the magnetic flux and we established the transmission probability. This proceeds by applying Landauer conductance formulae which opens the way to study electronic transport properties. (authors)

  13. Stability and electronic properties of silicene on WSe2

    KAUST Repository

    Zhu, Jiajie

    2015-03-17

    Many semiconducting substrates, such as GaS and MgBr2, have been explored for silicene. However, large lattice mismatches, complicated control of terminal layers and small band gaps are critical limiting factors. First-principles results on the stability and electronic properties of silicene on WSe2 show that the energy barriers for lateral translation between the two subsystems are very small due to weak van der Waals interactions. For the same reason, the Dirac physics of silicene is preserved. It turns out that the induced band gap is sufficient to withstand thermal fluctuations. This journal is © The Royal Society of Chemistry 2015.

  14. Quantum theory of the optical and electronic properties of semiconductors

    CERN Document Server

    Haug, Hartmut

    1990-01-01

    The current technological revolution in the development of computing devices has created a demand for a textbook on the quantum theory of the electronic and optical properties of semiconductors and semiconductor devices. This book successfully fulfills this need. Based on lectures given by the authors, it is a comprehensive introduction for researchers or graduate-level students to the subject. Certain sections can also serve as a graduate-level textbook for use in solid state physics courses or for more specialized courses. The final chapters establish a direct link to current research in sem

  15. Structure and Electronic Properties of Cerium Orthophosphate: Theory and Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Adelstein, Nicole; Mun, B. Simon; Ray, Hannah; Ross Jr, Phillip; Neaton, Jeffrey; De Jonghe, Lutgard

    2010-07-27

    Structural and electronic properties of cerium orthophosphate (CePO{sub 4}) are calculated using density functional theory (DFT) with the local spin-density approximation (LSDA+U), with and without gradient corrections (GGA-(PBE)+U), and compared to X-ray diffraction and photoemission spectroscopy measurements. The density of states is found to change significantly as the Hubbard parameter U, which is applied to the Ce 4f states, is varied from 0 to 5 eV. The calculated structural properties are in good agreement with experiment and do not change significantly with U. Choosing U = 3 eV for LDSA provides the best agreement between the calculated density of states and the experimental photoemission spectra.

  16. Stability and electronic properties of low-dimensional nanostructures

    Science.gov (United States)

    Guan, Jie

    As the devices used in daily life become smaller and more concentrated, traditional three-dimensional (3D) bulk materials have reached their limit in size. Low-dimensional nanomaterials have been attracting more attention in research and getting widely applied in many industrial fields because of their atomic-level size, unique advanced properties, and varied nanostructures. In this thesis, I have studied the stability and mechanical and electronic properties of zero-dimensional (0D) structures including carbon fullerenes, nanotori, metallofullerenes and phosphorus fullerenes, one-dimensional (1D) structures including carbon nanotubes and phosphorus nanotubes, as well as two-dimensional (2D) structures including layered transition metal dichalcogenides (TMDs), phosphorene and phosphorus carbide (PC). I first briefly introduce the scientific background and the motivation of all the work in this thesis. Then the computational techniques, mainly density functional theory (DFT), are reviewed in Chapter 2. In Chapter 3, I investigate the stability and electronic structure of endohedral rare-earth metallofullerene La C60 and the trifluoromethylized La C60(CF3)n with n ≤ 5. Odd n is preferred due to the closed-shell electronic configuration or large HOMO-LUMO gap, which is also meaningful for the separation of C 60-based metallofullerenes. Mechanical and electronic properties of layered materials including TMDs and black phosphorus are studied in Chapter 4 and 5. In Chapter 4, a metallic NbSe2/semiconducting WSe2 bilayer is investigated and besides a rigid band shift associated with charge transfer, the presence of NbSe2 does not modify the electronic structure of WSe2. Structural similarity and small lattice mismatch results in the heterojunction being capable of efficiently transferring charge acrossthe interface. In Chapter 5, I investigate the dependence of stability and electronic band structure on the in-layer strain in bulk black phosphorus. In Chapters 6, 7 and

  17. Electronic properties of a new structured Sin/O superlattice

    Directory of Open Access Journals (Sweden)

    S. Yu

    2016-11-01

    Full Text Available Silicon is a material which dominants the semiconductor industry and has a well-established processing technology based on it. However, silicon has an indirect-bandgap and is not efficient in light emitting. This limits its applications in optoelectronics. In this paper, we proposed a new structural model for the silicon-based superlattice, i.e., the Sin/O one. The model consists of alternating films of n-layers of Si and a monolayer of oxygen along z-direction, together with a surface cell of Si(001 (2×1 reconstruction in the x-y plane. The importance of employing such a Si(001 (2×1 reconstruction is that all the electrons at interface can be strongly bonded. Our results showed interesting electronic properties, e.g., the band folding and large band gap of bulk Si, when the thickness of the silicon layers was increased (but still thin. Our structure might also offer other interesting properties.

  18. Strain, stabilities and electronic properties of hexagonal BN bilayers

    Science.gov (United States)

    Fujimoto, Yoshitaka; Saito, Susumu

    Hexagonal boron nitride (h-BN) atomic layers have been regarded as fascinating materials both scientifically and technologically due to the sizable band gap. This sizable band-gap nature of the h-BN atomic layers would provide not only new physical properties but also novel nano- and/or opto-electronics applications. Here, we study the first-principles density-functional study that clarifies the biaxial strain effects on the energetics and the electronic properties of h-BN bilayers. We show that the band gaps of the h-BN bilayers are tunable by applying strains. Furthermore, we show that the biaxial strains can produce a transition from indirect to direct band gaps of the h-BN bilayer. We also discuss that both AA and AB stacking patterns of h-BN bilayer become feasible structures because h-BN bilayers possess two different directions in the stacking patterns. Supported by MEXT Elements Strategy Initiative to Form Core Research Center through Tokodai Institute for Element Strategy, JSPS KAKENHI Grant Numbers JP26390062 and JP25107005.

  19. Electronic and magnetic properties of MnAu nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Masrour, R., E-mail: rachidmasrour@hotmail.com [Laboratory of Materials, Processes, Environment and Quality, Cady Ayyed University, National School of Applied Sciences, Safi 46000 (Morocco); LMPHE (URAC 12), Faculty of Science, Mohammed V-Agdal University, Rabat (Morocco); Hlil, E.K. [Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9 (France); Hamedoun, M. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Benyoussef, A. [LMPHE (URAC 12), Faculty of Science, Mohammed V-Agdal University, Rabat (Morocco); Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Hassan II Academy of Science and Technology, Rabat (Morocco); Mounkachi, O; El moussaoui, H. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco)

    2014-03-15

    Self-consistent ab initio calculations, based on DFT (Density Functional Theory) approach and using FLAPW (Full potential Linear Augmented Plane Wave) method, are performed to investigate both electronic and magnetic properties of the MnAu nanoparticles. Polarized spin is included in calculations within the framework of the antiferromagnetic. The Mn magnetic moments where considered to be along c axes. Obtained data from ab initio calculations are used as input for the high temperature series expansions (HTSEs) calculations to compute other magnetic parameters. The zero-field high temperature static susceptibility series of the magnetic moment (m) and nearest-neighbour Heisenberg and XY models on a MnAu nanoparticles is thoroughly analyzed by means of a power series coherent anomaly method (CAM) for different nanoparticles. The exchanges interactions between the magnetic atoms are obtained for MnAu nanoparticles. - Highlights: • The electronic properties of the MnAu nanoparticles are studied using the DFT and FLAPW. • Magnetic moment is computed. • The ab initio calculations are used as input for HTSEs to compute other magnetic parameters. • The exchanges interactions and blocking temperature are obtained for MnAu nanoparticles.

  20. Electronic and magnetic properties of MnAu nanoparticles

    International Nuclear Information System (INIS)

    Masrour, R.; Hlil, E.K.; Hamedoun, M.; Benyoussef, A.; Mounkachi, O; El moussaoui, H.

    2014-01-01

    Self-consistent ab initio calculations, based on DFT (Density Functional Theory) approach and using FLAPW (Full potential Linear Augmented Plane Wave) method, are performed to investigate both electronic and magnetic properties of the MnAu nanoparticles. Polarized spin is included in calculations within the framework of the antiferromagnetic. The Mn magnetic moments where considered to be along c axes. Obtained data from ab initio calculations are used as input for the high temperature series expansions (HTSEs) calculations to compute other magnetic parameters. The zero-field high temperature static susceptibility series of the magnetic moment (m) and nearest-neighbour Heisenberg and XY models on a MnAu nanoparticles is thoroughly analyzed by means of a power series coherent anomaly method (CAM) for different nanoparticles. The exchanges interactions between the magnetic atoms are obtained for MnAu nanoparticles. - Highlights: • The electronic properties of the MnAu nanoparticles are studied using the DFT and FLAPW. • Magnetic moment is computed. • The ab initio calculations are used as input for HTSEs to compute other magnetic parameters. • The exchanges interactions and blocking temperature are obtained for MnAu nanoparticles

  1. Electronic structure and magnetic properties of zigzag blue phosphorene nanoribbons

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Tao; Hong, Jisang, E-mail: hongj@pknu.ac.kr [Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2015-08-07

    We investigated the electronic structure and magnetism of zigzag blue phosphorene nanoribbons (ZBPNRs) using first principles density functional theory calculations by changing the widths of ZBPNRs from 1.5 to 5 nm. In addition, the effect of H and O passivation was explored as well. The ZBPNRs displayed intra-edge antiferromagnetic ground state with a semiconducting band gap of ∼0.35 eV; and this was insensitive to the edge structure relaxation effect. However, the edge magnetism of ZBPNRs disappeared with H-passivation. Moreover, the band gap of H-passivated ZBPNRs was greatly enhanced because the calculated band gap was ∼1.77 eV, and this was almost the same as that of two-dimensional blue phosphorene layer. For O-passivated ZBPNRs, we also found an intra-edge antiferromagnetic state. Besides, both unpassivated and O-passivated ZBPNRs preserved almost the same band gap. We predict that the electronic band structure and magnetic properties can be controlled by means of passivation. Moreover, the edge magnetism can be also modulated by the strain. Nonetheless, the intrinsic physical properties are size independent. This feature can be an advantage for device applications because it may not be necessary to precisely control the width of the nanoribbon.

  2. Mechanical properties and electronic structures of Fe-Al intermetallic

    Energy Technology Data Exchange (ETDEWEB)

    Liu, YaHui; Chong, XiaoYu; Jiang, YeHua, E-mail: jiangyehua@kmust.edu.cn; Zhou, Rong; Feng, Jing, E-mail: jingfeng@kmust.edu.cn

    2017-02-01

    Using the first-principles calculations, the elastic properties, anisotropy properties, electronic structures, Debye temperature and stability of Fe-Al (Fe{sub 3}Al, FeAl, FeAl{sub 2}, Fe{sub 2}Al{sub 5} and FeAl{sub 3}) binary compounds were calculated. The formation enthalpy and cohesive energy of these Fe-Al compounds are negative, and show they are thermodynamically stable structures. Fe{sub 2}Al{sub 5} has the lowest formation enthalpy, which shows the Fe{sub 2}Al{sub 5} is the most stable of Fe-Al binary compounds. These Fe-Al compounds display disparate anisotropy due to the calculated different shape of the 3D curved surface of the Young’s modulus and anisotropic index. Fe{sub 3}Al has the biggest bulk modulus with the value 233.2 GPa. FeAl has the biggest Yong’s modulus and shear modulus with the value 296.2 GPa and 119.8 GPa, respectively. The partial density of states, total density of states and electron density distribution maps of the binary Fe-Al binary compounds are analyzed. The bonding characteristics of these Fe-Al binary compounds are mainly combination by covalent bond and metallic bonds. Meanwhile, also exist anti-bond effect. Moreover, the Debye temperatures and sound velocity of these Fe-Al compounds are explored.

  3. Thermal equilibrium properties of an intense relativistic electron beam

    International Nuclear Information System (INIS)

    Davidson, R.C.; Uhm, H.S.

    1979-01-01

    The thermal equilibrium properties of an intense relativistic electron beam with distribution function f 0 /sub b/=Z -1 /sub b/exp[-(H-β/sub b/cP/sub z/-ω/sub b/P/sub theta/) /T] are investigated. This choice of f 0 /sub b/ allows for a mean azimuthal rotation of the beam electrons (when ω/sub b/not =0), and corresponds to an important generalization of the distribution function first analyzed by Bennett. Beam equilibrium properties, including axial velocity profile V 0 /sub z/b(r), azimuthal velocity profile V 0 /sub thetab/(r), beam temperature profile T 0 /sub b/(r), beam density profile n 0 /sub b/(r), and equilibrium self-field profiles, are calculated for a broad range of system parameters. For appropriate choice of beam rotation velocity ω/sub b/, it is found that radially confined equilibrium solutions [with n 0 /sub b/(r→infinity) =0] exist even in the absence of a partially neutralizing ion background that weakens the repulsive space-charge force. The necessary and sufficient conditions for radially confined equilibria are ω - /sub b/ + /sub b/ for 0 2 /sub b/p /ω 2 /sub b/c) (1-f-β 2 /sub b/) 2 /sub b/p/ω 2 /sub b/c) (1-f-β 2 /sub b/) <0

  4. Electronic and optical properties of Fe, Pd, and Ti studied by reflection electron energy loss spectroscopy

    International Nuclear Information System (INIS)

    Tahir, Dahlang; Kraaer, Jens; Tougaard, Sven

    2014-01-01

    We have studied the electronic and optical properties of Fe, Pd, and Ti by reflection electron energy-loss spectroscopy (REELS). REELS spectra recorded for primary energies in the range from 300 eV to 10 keV were corrected for multiple inelastically scattered electrons to determine the effective inelastic-scattering cross section. The dielectric functions and optical properties were determined by comparing the experimental inelastic-electron scattering cross section with a simulated cross section calculated within the semi-classical dielectric response model in which the only input is Im(−1/ε) by using the QUEELS-ε(k,ω)-REELS software package. The complex dielectric functions ε(k,ω), in the 0–100 eV energy range, for Fe, Pd, and Ti were determined from the derived Im(−1/ε) by Kramers-Kronig transformation and then the refractive index n and extinction coefficient k. The validity of the applied model was previously tested and found to give consistent results when applied to REELS spectra at energies between 300 and 1000 eV taken at widely different experimental geometries. In the present paper, we provide, for the first time, a further test on its validity and find that the model also gives consistent results when applied to REELS spectra in the full range of primary electron energies from 300 eV to 10000 eV. This gives confidence in the validity of the applied method.

  5. Modifying the Electronic Properties of Nano-Structures Using Strain

    International Nuclear Information System (INIS)

    Lamba, V K; Engles, D

    2012-01-01

    We used density-functional theory based Non equilibrium green function simulations to study the effects of strain and quantum confinement on the electronic properties of Germanium and Silicon NWs along the [110] direction, such as the energy gap and the effective masses of the electron and hole. The diameters of the NWs being studied in a range of 3-20 Å. On basis of our calculation we conclude that the Ge [110] NWs possess a direct band gap, while Si [110] NWs possess indirect band gap at nanoscale. The band gap is almost a linear function of strain when the diameter of Ge NWs D 15 Å; and for Si it is linear in behaviour. On doping silicon wire we found that the bandgap shows parabolic behaviour for change in strain. We also concluded that the band gap and the effective masses of charge carries (i.e. electron and hole) changes by applying the strain to the NWs. Our results suggested that strain can be used to tune the band structures of NWs, which may help in de sign of future nanoelectronic devices.

  6. Use of gamma radiation to prevent infectivity of meat-borne parasites and effect of irradiation on the biochemical and its properties of meats

    International Nuclear Information System (INIS)

    Zahran, D.A.H.

    2002-01-01

    The pre-liminary study performed indicated that the least effective irradiation dose to control the infectivity of Trichinela spirales was 0.2 kGy, by which neither worms nor encysted larvae were found in the laboratory animals on the 3rd, 7th and 21st day post infection. The effect of this effective irradiation dose on the biochemical constituents and acceptability of beef and pork meat was evaluated. The results showed that there was no significant differences in the biochemical constituents and organoleptic properties between unirradiated and irradiated meats. By GC-MS analysis no new fatty acids were found in beef and pork lipids by using 0.2 kGy irradiation dose. By amino acids analysis, 17 amino acids were detected on all unirradiated and irradiated samples. 0.2 kGy irradiation dose almost had no effect on the amino acids profiles. However, some of the mino acids slightly increased and others slightly decreased. It could be concluded that low irradiation dose used approved to be efficient in controlling infectivity of meat-borne parasites with minimal changes in organoleptic properties and biochemical constitution of meat

  7. Acetylcholinesterases of Rhipicephalus (Boophilus) microplus and Phlebotomus papatasi: Gene identification, expression and biochemical properties of recombinant proteins

    Science.gov (United States)

    Rhipicephalus (Boophilus) microplus (Bm) is a vector of bovine babesiosis and anaplasmosis. Tick resistance to organophosphate (OP) acaricide involves acetylcholinesterase (AChE) insensitivity to OP and metabolic detoxification. In vitro expression of Bm genes encoding AChE allowed biochemical chara...

  8. [Physical properties of f electron systems]: Progress report, February 1987-January 1988

    International Nuclear Information System (INIS)

    Riseborough, P.S.

    1988-01-01

    This paper discusses the progress in research on f electron systems. The major properties discussed in this paper are: magnetic properties, transport properties, heavy fermion superconductivity, and photo-emission spectroscopy

  9. Influence of the kind of peat and the depth of sampling on the biochemical properties of Tagan peatland

    Science.gov (United States)

    Wojciech Szajdak, Lech; Inisheva, Lydia I.

    2010-05-01

    The upper layer of a peat bog in which organic matter decomposes aerobically much more rapidly than in the underlying, anaerobic catotelm. As litter accumulates at the surface the size of the catotelm increases, because the thickness of the acrotelm is limited to depth at which aerobic respiration can occur. Although the rate of decomposition per unit volume of material is much greater in the acrotelm than in the catotelm, a point is reached at which the difference in volume between the two layers is such that the total rate of decomposition in the catotelm is equal to that in the acrotelm. This limits the thickness to which the bog can grow. Should there be a climate change (e.g. an increase in precipitation) growth can resume. Bogs therefore preserve a record of climatic conditions. Soils samples were taken from four places marked as No 1, 2, 3 and 4 each from two depth 0-25 and 50-75 cm of the peatland Tagan. Peatlands Tagan is located near Tomsk, West Siberia, Russia. Place No 1 in both layers represents grasses peat with the degree of the decomposition ranged from 25 to 35% (pH 6.31-7.95). Point 2 is characterized by wooden and wooden grasses peat with 35% degree of the decomposition (pH 5.16-9.31. There is buckbean peat in the points 3 and 4 (pH 6.4-6.49). However, 1.5 m depth of sapropel is located in point 4. The activity of the following enzymes: xanthine oxidase, phenolic oxidase, peroxidase, urease, nitrate reductase were measured and two forms of organic carbon (total organic carbon and dissolved organic carbon) and two form of iron Fe(II) and Fe(III) were determined in these samples. These enzymes participate in several biochemical pathways in soil connected with redox potential. The concentrations of indole-3-acetic acid, very famous fitohormone were also measured. It was observed in all places of sampling significant increase of the total organic carbon with an increase of the depth. However, the quantity of dissolved organic carbon closely decreased

  10. Fracture toughness properties of similar and dissimilar electron beam welds

    International Nuclear Information System (INIS)

    Kocak, M.; Junghans, E.

    1994-01-01

    The weldability aspects, tensile and Crack Tip Opening Displacement (CTOD) toughness properties of 9Cr1MoNbV (P91) martensitic steel with austenitic 316L steel were evaluated for electron beam (EB) welds on 35 mm thick pates. The effects of mechanical heterogeneity (mis-matching) at the vicinity of the crack tip of dissimilar three point bend specimens on the CTOD fracture toughness values was also discussed. The CTOD tests were performed on similar and dissimilar EB welds of austenitic and tempered martensitic P91 steels at room temperature. Dilution of austenitic with martensitic steel resulted in predominantly martensitic EB weld metal, exhibiting rather high yield strength and hardness. Nevertheless, the weld metal produced high CTOD toughness values due to the beneficial effect of the lower strength austenitic steel part of the specimen in which crack deviation occured (mis-match effect). The coarse grained HAZ of the P91 steel side exhibits extremely poor CTOD toughness properties in the as-welded condition at room temperature. The CTOD values obtained are believed to be representing the intrinsic property of this zone since the distance of the crack tip to the weaker austenitic steel part of the SENB specimens was too large to cause an effective stress relaxation at the crack tip. Further post weld heat treatment at 750 C for two hours improved the CTOD toughness marginally. (orig.)

  11. Electronic properties of thermally formed thin iron oxide films

    International Nuclear Information System (INIS)

    Wielant, J.; Goossens, V.; Hausbrand, R.; Terryn, H.

    2007-01-01

    The oxide layer, present between an organic coating and the substrate, guarantees adhesion of the coating and plays a determinating role in the delamination rate of the organic coating. The purpose of this study is to compare the resistive and semiconducting properties of thermal oxides formed on steel in two different atmospheres at 250 deg. C: an oxygen rich atmosphere, air, and an oxygen deficient atmosphere, N 2 . In N 2 , a magnetite layer grows while in air a duplex oxide film forms composed by an inner magnetite layer and a thin outer hematite scale. The heat treatment for different amounts of time at high temperature was used as method to sample the thickness variation and change in electronic and semiconducting properties of the thermal oxide layers. Firstly, linear voltammetric measurements were performed to have a first insight in the electrochemical behavior of the thermal oxides in a borate buffer solution. Electrochemical impedance spectroscopy in the same buffer combined with the Mott-Schottky analysis were used to determine the semiconducting properties of the thermal oxides. By spectroscopic ellipsometry (SE) and atomic force microscopy (AFM), respectively, the thickness and roughness of the oxide layers were determined supporting the physical interpretation of the voltammetric and EIS data. These measurements clearly showed that oxide layers with different constitution, oxide resistance, flatband potential and doping concentration can be grown by changing the atmosphere

  12. Electronic property measurements for piezoelectric ceramics. Technical notes

    International Nuclear Information System (INIS)

    Cain, M.; Stewart, M.; Gee, M.

    1998-01-01

    A series of measurement notes are presented, with emphasis placed on the technical nature of the testing methodology, for the determination of key electronic properties for piezoelectric ceramic materials that are used as sensors and actuators. The report is segmented into 'sections' that may be read independently from the rest of the report. The following measurement issues are discussed: Polarisation/Electric field (PE) loop measurements including a discussion of commercial and an in-house constructed system that measures PE loops; Dielectric measurements at low and high stress application, including some thermal and stress dependency modelling of piezo materials properties, developed at NPL; Strain measurement techniques developed at CMMT; Charge measurement techniques suitable for PE loop and other data acquisition; PE loop measurement and software analysis developed at CMMT and Manchester University. The primary objective of this report is to provide a framework on which the remainder of the testing procedures are to be developed for measurements of piezoelectric properties at high stress and stress rate. These procedures will be the subject of a future publication. (author)

  13. Organic/metal interfaces. Electronic and structural properties

    Energy Technology Data Exchange (ETDEWEB)

    Duhm, Steffen

    2008-07-17

    This work addresses several important topics of the field of organic electronics. The focus lies on organic/metal interfaces, which exist in all organic electronic devices. Physical properties of such interfaces are crucial for device performance. Four main topics have been covered: (i) the impact of molecular orientation on the energy levels, (ii) energy level tuning with strong electron acceptors, (iii) the role of thermodynamic equilibrium at organic/ organic homo-interfaces and (iv) the correlation of interfacial electronic structure and bonding distance. To address these issues a broad experimental approach was necessary: mainly ultraviolet photoelectron spectroscopy was used, supported by X-ray photoelectron spectroscopy, metastable atom electron spectroscopy, X-ray diffraction and X-ray standing waves, to examine vacuum sublimed thin films of conjugated organic molecules (COMs) in ultrahigh vacuum. (i) A novel approach is presented to explain the phenomenon that the ionization energy in molecular assemblies is orientation dependent. It is demonstrated that this is due to a macroscopic impact of intramolecular dipoles on the ionization energy in molecular assemblies. Furthermore, the correlation of molecular orientation and conformation has been studied in detail for COMs on various substrates. (ii) A new approach was developed to tune hole injection barriers ({delta}{sub h}) at organic/metal interfaces by adsorbing a (sub-) monolayer of an organic electron acceptor on the metal electrode. Charge transfer from the metal to the acceptor leads to a chemisorbed layer, which reduces {delta}{sub h} to the COM overlayer. This concept was tested with three acceptors and a lowering of {delta}{sub h} of up to 1.2 eV could be observed. (iii) A transition from vacuum-level alignment to molecular level pinning at the homo-interface between a lying monolayer and standing multilayers of a COM was observed, which depended on the amount of a pre-deposited acceptor. The

  14. Synthesis Properties and Electron Spin Resonance Properties of Titanic Materials (abstract)

    Science.gov (United States)

    Cho, Jung Min; Lee, Jun; Kim, Tak Hee; Sun, Min Ho; Jang, Young Bae; Cho, Sung June

    2009-04-01

    Titanic materials were synthesized by hydrothermal method of TiO2 anatase in 10M LiOH, 10M NaOH, and 14M KOH at 130° C for 30 hours. Alkaline media were removed from the synthesized products using 0.1N HCl aqueous solution. The as-prepared samples were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, Brunauer-Emmett-Teller isotherm, and electron spin resonance. Different shapes of synthesized products were observed through the typical electron microscope and indicated that the formation of the different morphologies depends on the treatment conditions of highly alkaline media. Many micropores were observed in the cubic or octahedral type of TiO2 samples through the typical electron microscope and Langmuir adsorption-desorption isotherm of liquid nitrogen at 77° K. Electron spin resonance studies have also been carried out to verify the existence of paramagnetic sites such as oxygen vacancies on the titania samples. The effect of alkali metal ions on the morphologies and physicochemical properties of nanoscale titania are discussed.

  15. Molecular Data for a Biochemical Model of DNA Radiation Damage: Electron Impact Ionization and Dissociative Ionization of DNA Bases and Sugar-Phosphate Backbone

    Science.gov (United States)

    Dateo, Christopher E.; Fletcher, Graham D.

    2004-01-01

    As part of the database for building up a biochemical model of DNA radiation damage, electron impact ionization cross sections of sugar-phosphate backbone and DNA bases have been calculated using the improved binary-encounter dipole (iBED) model. It is found that the total ionization cross sections of C3'- and C5'-deoxyribose-phospate, two conformers of the sugar-phosphate backbone, are close to each other. Furthermore, the sum of the ionization cross sections of the separate deoxyribose and phosphate fragments is in close agreement with the C3'- and C5'-deoxyribose-phospate cross sections, differing by less than 10%. Of the four DNA bases, the ionization cross section of guanine is the largest, then in decreasing order, adenine, thymine, and cytosine. The order is in accordance with the known propensity of oxidation of the bases by ionizing radiation. Dissociative ionization (DI), a process that both ionizes and dissociates a molecule, is investigated for cytosine. The DI cross section for the formation of H and (cytosine-Hl)(+), with the cytosine ion losing H at the 1 position, is also reported. The threshold of this process is calculated to be 17.1 eV. Detailed analysis of ionization products such as in DI is important to trace the sequential steps in the biochemical process of DNA damage.

  16. Molecular data for a biochemical model of DNA damage: Electron impact ionization and dissociative ionization cross sections of DNA bases and sugar-phosphate backbone

    International Nuclear Information System (INIS)

    Huo, Winifred M.; Dateo, Christopher E.; Fletcher, Graham D.

    2006-01-01

    As part of the database for building up a biochemical model of DNA radiation damage, electron impact ionization cross sections of sugar-phosphate backbone and DNA bases have been calculated using the improved binary-encounter dipole (iBED) model. It is found that the total ionization cross sections of C 3 ' - and C 5 ' -deoxyribose-phosphate, two conformers of the sugar-phosphate backbone, are close to each other. Furthermore, the sum of the ionization cross sections of the separate deoxyribose and phosphate fragments is in close agreement with the C 3 ' - and C 5 ' -deoxyribose-phosphate cross sections, differing by less than 10%, an indication that a building-up principle may be applicable. Of the four DNA bases, the ionization cross section of guanine is the largest, then in decreasing order, adenine, thymine, and cytosine. The order is in accordance with the known propensity of oxidation of the bases by ionizing radiation. Dissociative ionization (DI), a process that both ionizes and dissociates a molecule, is investigated for cytosine. The DI cross section for the formation of H and (cytosine-H1) + , with the cytosine ion losing H at the 1 position, is also reported. The threshold of this process is calculated to be 16.9eV. Detailed analysis of ionization products such as in DI is important to trace the sequential steps in the biochemical process of DNA damage

  17. Electronic Structure Approach to Tunable Electronic Properties of Hybrid Organic-Inorganic Perovskites

    Science.gov (United States)

    Liu, Garnett; Huhn, William; Mitzi, David B.; Kanai, Yosuke; Blum, Volker

    We present a study of the electronic structure of layered hybrid organic-inorganic perovskite (HOIP) materials using all-electron density-functional theory. Varying the nature of the organic and inorganic layers should enable systematically fine-tuning the carrier properties of each component. Using the HSE06 hybrid density functional including spin-orbit coupling (SOC), we validate the principle of tuning subsystem-specific parts of the electron band structures and densities of states in CH3NH3PbX3 (X=Cl, Br, I) compared to a modified organic component in layered (C6H5C2H4NH3) 2PbX4 (X=Cl, Br, I) and C20H22S4N2PbX4 (X=Cl, Br, I). We show that tunable shifts of electronic levels indeed arise by varying Cl, Br, I as the inorganic components, and CH3NH3+ , C6H5C2H4NH3+ , C20H22S4N22 + as the organic components. SOC is found to play an important role in splitting the conduction bands of the HOIP compounds investigated here. The frontier orbitals of the halide shift, increasing the gap, when Cl is substituted for Br and I.

  18. Effect of protonation on the electronic properties of DNA base pairs: applications for molecular electronics.

    Science.gov (United States)

    Mallajosyula, Sairam S; Pati, Swapan K

    2007-10-11

    Protonation of DNA basepairs is a reversible phenomenon that can be controlled by tuning the pH of the system. Under mild acidic conditions, the hydrogen-bonding pattern of the DNA basepairs undergoes a change. We study the effect of protonation on the electronic properties of the DNA basepairs to probe for possible molecular electronics applications. We find that, under mild acidic pH conditions, the A:T basepair shows excellent rectification behavior that is, however, absent in the G:C basepair. The mechanism of rectification has been discussed using a simple chemical potential model. We also consider the noncanonical A:A basepair and find that it can be used as efficient pH dependent molecular switch. The switching action in the A:A basepair is explained in the light of pi-pi interactions, which lead to efficient delocalization over the entire basepair.

  19. Atomistic simulations of divacancy defects in armchair graphene nanoribbons: Stability, electronic structure, and electron transport properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jun [College of Physical Science and Technology, Yangtze University, Jingzhou, Hubei 434023 (China); Zeng, Hui, E-mail: zenghui@yangtzeu.edu.cn [College of Physical Science and Technology, Yangtze University, Jingzhou, Hubei 434023 (China); Wei, Jianwei [College of Optoelectronic Information, Chongqing University of Technology, Chongqing 400054 (China); Li, Biao; Xu, Dahai [College of Physical Science and Technology, Yangtze University, Jingzhou, Hubei 434023 (China)

    2014-01-17

    Using the first principles calculations associated with nonequilibrium Green's function, we have studied the electronic structures and quantum transport properties of defective armchair graphene nanoribbon (AGNR) in the presence of divacancy defects. The triple pentagon–triple heptagon (555–777) defect in the defective AGNR is energetically more favorable than the pentagon–octagon–pentagon (5–8–5) defect. Our calculated results reveal that both 5–8–5-like defect and 555–777-like defect in AGNR could improve the electron transport. It is anticipated that defective AGNRs can exhibit large range variations in transport behaviors, which are strongly dependent on the distributions of the divacancy defect.

  20. Electronic properties of antiferromagnetic UBi2 metal by exact exchange for correlated electrons method

    Directory of Open Access Journals (Sweden)

    E Ghasemikhah

    2012-03-01

    Full Text Available This study investigated the electronic properties of antiferromagnetic UBi2 metal by using ab initio calculations based on the density functional theory (DFT, employing the augmented plane waves plus local orbital method. We used the exact exchange for correlated electrons (EECE method to calculate the exchange-correlation energy under a variety of hybrid functionals. Electric field gradients (EFGs at the uranium site in UBi2 compound were calculated and compared with the experiment. The EFGs were predicted experimentally at the U site to be very small in this compound. The EFG calculated by the EECE functional are in agreement with the experiment. The densities of states (DOSs show that 5f U orbital is hybrided with the other orbitals. The plotted Fermi surfaces show that there are two kinds of charges on Fermi surface of this compound.

  1. Electronic properties of semiconductor surfaces and metal/semiconductor interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Tallarida, M.

    2005-05-15

    This thesis reports investigations of the electronic properties of a semiconductor surface (silicon carbide), a reactive metal/semiconductor interface (manganese/silicon) and a non-reactive metal/semiconductor interface (aluminum-magnesium alloy/silicon). The (2 x 1) reconstruction of the 6H-SiC(0001) surface has been obtained by cleaving the sample along the (0001) direction. This reconstruction has not been observed up to now for this compound, and has been compared with those of similar elemental semiconductors of the fourth group of the periodic table. This comparison has been carried out by making use of photoemission spectroscopy, analyzing the core level shifts of both Si 2p and C 1s core levels in terms of charge transfer between atoms of both elements and in different chemical environments. From this comparison, a difference between the reconstruction on the Si-terminated and the C-terminated surface was established, due to the ionic nature of the Si-C bond. The growth of manganese films on Si(111) in the 1-5 ML thickness range has been studied by means of LEED, STM and photoemission spectroscopy. By the complementary use of these surface science techniques, two different phases have been observed for two thickness regimes (<1 ML and >1 ML), which exhibit a different electronic character. The two reconstructions, the (1 x 1)-phase and the ({radical}3 x {radical}3)R30 -phase, are due to silicide formation, as observed in core level spectroscopy. The growth proceeds via island formation in the monolayer regime, while the thicker films show flat layers interrupted by deep holes. On the basis of STM investigations, this growth mode has been attributed to strain due to lattice mismatch between the substrate and the silicide. Co-deposition of Al and Mg onto a Si(111) substrate at low temperature (100K) resulted in the formation of thin alloy films. By varying the relative content of both elements, the thin films exhibited different electronic properties

  2. Modelling of electronic and vibrational properties of carbon nanostructures

    Science.gov (United States)

    Margine, Elena Roxana

    The main goals of this dissertation work are the analysis and prediction of the properties of nanoscale carbon materials which hold great potential for nanotechnological applications such as strong conductive composites, field-effect transistors, diodes, rechargeable batteries, etc. Some of these exciting applications are already being actively developed, however their design via trial-and-error experimentation is often difficult and expensive. State-of-the-art simulation methods can be used as a powerful tool to streamline the path to practical implementations. In this thesis I use ab initio quantum-mechanical calculations to explore the response of nanoscale carbon materials to doping. A brief overview of the theoretical methods and of some basic concepts on carbon nanotubes are given in the first two chapters. In Chapter 3 we study the effect of doping in double-walled carbon nanotubes. These systems can be considered as nanoscale capacitors since they have two conducting (or semi-conducting) shells. The experimental work of our collaborators demonstrated for the first time that such a capacitor can be realized by the adsorption of bromine anions at the surface of the outer tube. Our theoretical analysis of the experimental results revealed that this quantum system, surprisingly, behaves exactly as the classical Faraday cage: the electric charge always resides on the outside surface of the conductor, even when the pristine tubes are not metallic. In Chapter 4 I present our findings on the phonon frequencies' response to electron doping in single-walled carbon nanotubes. It is well established that when graphite is doped with electrons, carbon-carbon bonds lengthen and all vibrational frequencies soften. However, in semiconducting carbon nanotubes, the frequency of one mode increases at low levels of alkali doping. Having carefully modelled the process with ab initio methods we conclude that the unusual behavior of the vibrational mode depends on which electronic

  3. Electronic structure and properties of uranyl compounds. Problems of electron-donor conception

    International Nuclear Information System (INIS)

    Glebov, V.A.

    1982-01-01

    Comparison of the series of the ligand mutual substitution in the uranyl compounds with the ligand series of d-elements and with the uranyl ''covalent model'', is made. The data on ionization potentials of the ligand higher valent levels and on the structure of some uranyl nitrate compounds are considered. It is concluded that the mechanism of the ligand effect on the properties of uranyl grouping is more complex, than it is supposed in the traditional representations on the nature of electron-donor interactions in the uranyl compounds

  4. Electronic Properties of Graphene-PtSe2 Contacts.

    Science.gov (United States)

    Sattar, Shahid; Schwingenschlögl, Udo

    2017-05-10

    In this article, we study the electronic properties of graphene in contact with monolayer and bilayer PtSe 2 using first-principles calculations. It turns out that there is no charge transfer between the components because of the weak van der Waals interaction. We calculate the work functions of monolayer and bilayer PtSe 2 and analyze the band bending at the contact with graphene. The formation of an n-type Schottky contact with monolayer PtSe 2 and a p-type Schottky contact with bilayer PtSe 2 is demonstrated. The Schottky barrier height is very low in the bilayer case and can be reduced to zero by 0.8% biaxial tensile strain.

  5. Electronic Properties of Graphene–PtSe2 Contacts

    KAUST Repository

    Sattar, Shahid

    2017-04-26

    In this article, we study the electronic properties of graphene in contact with monolayer and bilayer PtSe2 using first-principles calculations. It turns out that there is no charge transfer between the components because of the weak van der Waals interaction. We calculate the work functions of monolayer and bilayer PtSe2 and analyze the band bending at the contact with graphene. The formation of an n-type Schottky contact with monolayer PtSe2 and a p-type Schottky contact with bilayer PtSe2 is demonstrated. The Schottky barrier height is very low in the bilayer case and can be reduced to zero by 0.8% biaxial tensile strain.

  6. Structural and electronic properties of carbon nanotubes under hydrostatic pressures

    International Nuclear Information System (INIS)

    Zhang Ying; Cao Juexian; Yang Wei

    2008-01-01

    We studied the structural and electronic properties of carbon nanotubes under hydrostatic pressures based on molecular dynamics simulations and first principles band structure calculations. It is found that carbon nanotubes experience a hard-to-soft transition as external pressure increases. The bulk modulus of soft phase is two orders of magnitude smaller than that of hard phase. The band structure calculations show that band gap of (10, 0) nanotube increases with the increase of pressure at low pressures. Above a critical pressure (5.70GPa), band gap of (10, 0) nanotube drops rapidly and becomes zero at 6.62GPa. Moreover, the calculated charge density shows that a large pressure can induce an sp 2 -to-sp 3 bonding transition, which is confirmed by recent experiments on deformed carbon nanotubes

  7. Electronic Properties of Graphene–PtSe2 Contacts

    KAUST Repository

    Sattar, Shahid; Schwingenschlö gl, Udo

    2017-01-01

    In this article, we study the electronic properties of graphene in contact with monolayer and bilayer PtSe2 using first-principles calculations. It turns out that there is no charge transfer between the components because of the weak van der Waals interaction. We calculate the work functions of monolayer and bilayer PtSe2 and analyze the band bending at the contact with graphene. The formation of an n-type Schottky contact with monolayer PtSe2 and a p-type Schottky contact with bilayer PtSe2 is demonstrated. The Schottky barrier height is very low in the bilayer case and can be reduced to zero by 0.8% biaxial tensile strain.

  8. Electronic properties of field aligned CrO2 powders

    International Nuclear Information System (INIS)

    Tripathy, D.; Adeyeye, A.O.

    2005-01-01

    We have investigated in detail the electronic transport properties of half metallic CrO 2 powder-based devices, fabricated using optical lithography and field alignment technique. A transition in the conduction mechanism from spin-dependent intergranular tunneling to inelastic hopping was observed at 215 K. This transition temperature shifts to 230 K in the presence of 10 kOe field cooling due to reduction of the spin-independent hopping conductance channel. I-V characteristics exhibit strong temperature dependence and are non-linear even at room temperature. Our experimental results are in good agreement with a simple theoretical model. A novel 'double switching' phenomenon was observed in the I-V curves below the transition temperature

  9. Role of lutein in alleviating the effects of electron beam radiation induced hematological and biochemical changes in Swiss albino mice

    International Nuclear Information System (INIS)

    Vidya, V.; Krishna, A.P.; Patil, Shrikant; Fernandes, Ronald

    2016-01-01

    Lutein is a naturally occurring xanthophyll pigment derived from α-carotene. It is abundantly present in Tagetes erecta L. (marigold) and also present in a few vegetables, fruits and in animal sources. Lutein was evaluated for its protective role in electron beam radiation induced damages in Swiss albino mice. The drug was optimized for its radioprotective activity

  10. Electron Transport Chain Is Biochemically Linked to Pilus Assembly Required for Polymicrobial Interactions and Biofilm Formation in the Gram-Positive Actinobacterium Actinomyces oris

    Directory of Open Access Journals (Sweden)

    Belkys C. Sanchez

    2017-06-01

    Full Text Available The Gram-positive actinobacteria Actinomyces spp. are key colonizers in the development of oral biofilms due to the inherent ability of Actinomyces to adhere to receptor polysaccharides on the surface of oral streptococci and host cells. This receptor-dependent bacterial interaction, or coaggregation, requires a unique sortase-catalyzed pilus consisting of the pilus shaft FimA and the coaggregation factor CafA forming the pilus tip. While the essential role of the sortase machine SrtC2 in pilus assembly, biofilm formation, and coaggregation has been established, little is known about trans-acting factors contributing to these processes. We report here a large-scale Tn5 transposon screen for mutants defective in Actinomyces oris coaggregation with Streptococcus oralis. We obtained 33 independent clones, 13 of which completely failed to aggregate with S. oralis, and the remainder of which exhibited a range of phenotypes from severely to weakly defective coaggregation. The former had Tn5 insertions in fimA, cafA, or srtC2, as expected; the latter were mapped to genes coding for uncharacterized proteins and various nuo genes encoding the NADH dehydrogenase subunits. Electron microscopy and biochemical analyses of mutants with nonpolar deletions of nuo genes and ubiE, a menaquinone C-methyltransferase-encoding gene downstream of the nuo locus, confirmed the pilus and coaggregation defects. Both nuoA and ubiE mutants were defective in oxidation of MdbA, the major oxidoreductase required for oxidative folding of pilus proteins. Furthermore, supplementation of the ubiE mutant with exogenous menaquinone-4 rescued the cell growth and pilus defects. Altogether, we propose that the A. oris electron transport chain is biochemically linked to pilus assembly via oxidative protein folding.

  11. Edge effects on the electronic properties of phosphorene nanoribbons

    International Nuclear Information System (INIS)

    Peng, Xihong; Copple, Andrew; Wei, Qun

    2014-01-01

    Two dimensional few-layer black phosphorus crystal structures have recently been fabricated and have demonstrated great potential in electronic applications. In this work, we employed first principles density functional theory calculations to study the edge and quantum confinement effects on the electronic properties of the phosphorene nanoribbons (PNR). Different edge functionalization groups, such as H, F, Cl, OH, O, S, and Se, in addition to a pristine case were studied for a series of ribbon widths up to 3.5 nm. It was found that the armchair-PNRs (APNRs) are semiconductors for all edge groups considered in this work. However, the zigzag-PNRs (ZPNRs) show either semiconductor or metallic behavior in dependence on their edge chemical species. Family 1 edges (i.e., H, F, Cl, OH) form saturated bonds with P atoms in the APNRs and ZPNRs, and the edge states keep far away from the band gap. However, Family 2 edges (pristine, O, S, Se) form weak unsaturated bonds with the p z orbital of the phosphorus atoms and bring edge states within the band gap of the ribbons. For the ZPNRs, the edge states of Family 2 are present around the Fermi level within the band gap, which close up the band gap of the ZPNRs. For the APNRs, these edge states are located at the bottom of the conduction band and result in a reduced band gap.

  12. Electronic and magnetic properties of small rhodium clusters

    Energy Technology Data Exchange (ETDEWEB)

    Soon, Yee Yeen; Yoon, Tiem Leong [School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Lim, Thong Leng [Faculty of Engineering and Technology, Multimedia University, Melaka Campus, 75450 Melaka (Malaysia)

    2015-04-24

    We report a theoretical study of the electronic and magnetic properties of rhodium-atomic clusters. The lowest energy structures at the semi-empirical level of rhodium clusters are first obtained from a novel global-minimum search algorithm, known as PTMBHGA, where Gupta potential is used to describe the atomic interaction among the rhodium atoms. The structures are then re-optimized at the density functional theory (DFT) level with exchange-correlation energy approximated by Perdew-Burke-Ernzerhof generalized gradient approximation. For the purpose of calculating the magnetic moment of a given cluster, we calculate the optimized structure as a function of the spin multiplicity within the DFT framework. The resultant magnetic moments with the lowest energies so obtained allow us to work out the magnetic moment as a function of cluster size. Rhodium atomic clusters are found to display a unique variation in the magnetic moment as the cluster size varies. However, Rh{sub 4} and Rh{sub 6} are found to be nonmagnetic. Electronic structures of the magnetic ground-state structures are also investigated within the DFT framework. The results are compared against those based on different theoretical approaches available in the literature.

  13. Electronic transport properties of copper and gold at atomic scale

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadzadeh, Saeideh

    2010-11-23

    The factors governing electronic transport properties of copper and gold atomic-size contacts are theoretically examined in the present work. A two-terminal conductor using crystalline electrodes is adopted. The non-equilibrium Green's function combined with the density functional tight-binding method is employed via gDFTB simulation tool to calculate the transport at both equilibrium and non-equilibrium conditions. The crystalline orientation, length, and arrangement of electrodes have very weak influence on the electronic characteristics of the considered atomic wires. The wire width is found to be the most effective geometric aspect determining the number of conduction channels. The obtained conductance oscillation and linear current-voltage curves are interpreted. To analyze the conduction mechanism in detail, the transmission channels and their decomposition to the atomic orbitals are calculated in copper and gold single point contacts. The presented results offer a possible explanation for the relation between conduction and geometric structure. Furthermore, the results are in good agreement with available experimental and theoretical studies. (orig.)

  14. Structural and electronic properties of La C[sub 82

    Energy Technology Data Exchange (ETDEWEB)

    Laasonen, K.; Andreoni, W.; Parrinello, M. (Zurich Research Lab., Rueschlikon (Switzerland))

    1992-12-18

    The structural and electronic properties of the La C[sub 82] fullerene have been investigated by means of the Car-Parrinello method, which is based on the local density approximation of the density functional theory. The topological arrangement of the C[sub 82] cage was assumed to be a C[sub 3v] symmetry isomer. Three configurations were considered, one with the lanthanum atom at the center of the cluster, one with it along the threefold axis, and one with it at a low-symmetry, highly coordinated site. The structure was fully relaxed and it was found that the last of these configurations is energetically preferred. In this position, the lanthanum atom is nearly in a La[sup 3+] state and the unpaired electron is somewhat delocalized on the cage, in agreement with available experimental data. This arrangement suggests that the chemical shifts of the 5s and 5p lanthanum states can be used as a structural probe and as a way of further validating this picture. It is argued that this conclusion is not affected by the assumed fullerene structure.

  15. Edge effects on the electronic properties of phosphorene nanoribbons

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Xihong, E-mail: xihong.peng@asu.edu [School of Letters and Sciences, Arizona State University, Mesa, Arizona 85212 (United States); Copple, Andrew [Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States); Wei, Qun [School of Letters and Sciences, Arizona State University, Mesa, Arizona 85212 (United States); School of Physics and Optoelectronic Engineering, Xidian University, Xi' an 710071 (China)

    2014-10-14

    Two dimensional few-layer black phosphorus crystal structures have recently been fabricated and have demonstrated great potential in electronic applications. In this work, we employed first principles density functional theory calculations to study the edge and quantum confinement effects on the electronic properties of the phosphorene nanoribbons (PNR). Different edge functionalization groups, such as H, F, Cl, OH, O, S, and Se, in addition to a pristine case were studied for a series of ribbon widths up to 3.5 nm. It was found that the armchair-PNRs (APNRs) are semiconductors for all edge groups considered in this work. However, the zigzag-PNRs (ZPNRs) show either semiconductor or metallic behavior in dependence on their edge chemical species. Family 1 edges (i.e., H, F, Cl, OH) form saturated bonds with P atoms in the APNRs and ZPNRs, and the edge states keep far away from the band gap. However, Family 2 edges (pristine, O, S, Se) form weak unsaturated bonds with the p{sub z} orbital of the phosphorus atoms and bring edge states within the band gap of the ribbons. For the ZPNRs, the edge states of Family 2 are present around the Fermi level within the band gap, which close up the band gap of the ZPNRs. For the APNRs, these edge states are located at the bottom of the conduction band and result in a reduced band gap.

  16. Acetylcholinesterase of the Sand Fly, Phlebotomus papatasi (Scopoli): cDNA Sequence, Baculovirus Expression, and Biochemical Properties

    Science.gov (United States)

    2013-01-01

    Iraq: 6. Evaluation of insecticides for the control of sand flies. J Med Entomol 2011, 48:584–599. 16. Hemingway J, Ranson H: Insecticide resistance...leishmaniasis in Morocco. Parasit Vectors 2012, 5:51. 18. Surendran SN, Karunaratne SHPP, Adams Z, Hemingway J, Hawkes NJ: Molecular and biochemical...2002, 37:213–218. 45. Vontas JG, Hejazi MJ, Hawkes NJ, Cosmidis N, Loukas M, Hemingway J: Resistance-associated point mutations of organophosphate

  17. Electronic, structural, and optical properties of crystalline yttria

    International Nuclear Information System (INIS)

    Xu, Y.; Gu, Z.; Ching, W.Y.

    1997-01-01

    The electronic structure of crystalline Y 2 O 3 is investigated by first-principles calculations within the local-density approximation (LDA) of the density-functional theory. Results are presented for the band structure, the total density of states (DOS), the atom- and orbital-resolved partial DOS, effective charges, bond order, and charge-density distributions. Partial covalent character in the Y-O bonding is shown, and the nonequivalency of the two Y sites is demonstrated. The calculated electronic structure is compared with a variety of available experimental data. The total energy of the crystal is calculated as a function of crystal volume. A bulk modulus B of 183 Gpa and a pressure coefficient B ' of 4.01 are obtained, which are in good agreement with compression data. An LDA band gap of 4.54 eV at Γ is obtained which increases with pressure at a rate of dE g /dP=0.012eV/Gpa at the equilibrium volume. Also investigated are the optical properties of Y 2 O 3 up to a photon energy of 20 eV. The calculated complex dielectric function and electron-energy-loss function are in good agreement with experimental data. A static dielectric constant of var-epsilon(0)=3.20 is obtained. It is also found that the bottom of the conduction band consists of a single band, and direct optical transition at Γ between the top of the valence band and the bottom of the conduction band may be symmetry forbidden. copyright 1997 The American Physical Society

  18. The identification and biochemical properties of the catalytic specificity of a serine peptidase secreted by Aspergillus fumigatus Fresenius.

    Science.gov (United States)

    da Silva, Ronivaldo Rodrigues; Caetano, Renato Cesar; Okamoto, Debora Nona; de Oliveira, Lilian Caroline Goncalves; Bertolin, Thiago Carlos; Juliano, Maria Aparecida; Juliano, Luiz; de Oliveira, Arthur H C; Rosae, Jose C; Cabral, Hamilton

    2014-07-01

    Aspergillus fumigatus is a saprophytic fungus as well as a so-called opportunist pathogen. Its biochemical potential and enzyme production justify intensive studies about biomolecules secreted by this microorganism. We describe the alkaline serine peptidase production, with optimum activity at 50°C and a pH of 7.5 and a reduction in proteolytic activity in the presence of the Al(+3) ions. When using intramolecularly quenched fluorogenic substrates, the highest catalytic efficiency was observed with the amino acid leucine on subsite S'(3) (60,000 mM(-1)s(-1)) and preference to non-polar amino acids on subsite S(3). In general, however, the peptidase shows non-specificity on other subsites studied. According to the biochemical characteristics, this peptidase may be an important biocatalyst for the hydrolysis of an enormous variety of proteins and can constitute an essential molecule for the saprophytic lifestyle or invasive action of the opportunistic pathogen. The peptidase described herein exhibits an estimated molecular mass of 33 kDa. Mass spectrometry analysis identified the sequence GAPWGLGSISHK displaying similarities to that of serine peptidase from Aspergillus fumigatus. These data may lead to a greater understanding of the advantageous biochemical potential, biotechnological interest, and trends of this fungus in spite of being an opportunist pathogen.

  19. Geometry, electronic structures and optical properties of phosphorus nanotubes

    International Nuclear Information System (INIS)

    Hu, Tao; Hashmi, Arqum; Hong, Jisang

    2015-01-01

    Using a first principles approach, we investigated the geometry, electronic structures, and optical properties of phosphorus nanotubes (PNTs). Two possible 1D configurations, the so-called α-PNTs and β-PNTs, are proposed, which are structurally related to blue and black phosphorus monolayers, respectively. Hereby, we predict that both armchair and zigzag geometries can be synthesized in α-PNTs, but the zigzag form of β-PNT is highly unfavorable because of large strain and conformation energies. The band gap of α-PNTs is expected to be ∼2.67 eV, and this is insensitive to the chirality when the tube’s inner diameter is larger than 1.3 nm, while the armchair β-PNTs have a much smaller band gap. Interestingly, we find nearly flat band structures in the zigzag α-PNT system. This may indicate that an excited particle–hole pair has a huge effective mass. We also find asymmetric optical properties with respect to the polarization direction. The armchair α-PNT for parallel polarization shows a large refractive index of 2.6 near the ultraviolet wavelength, and also we find that the refractive index can be even smaller than 1 in certain frequency ranges. The zigzag tubes show very weak reflectivity for parallel polarization, while the armchair tube displays high reflectivity. (paper)

  20. Electronic properties of disordered Weyl semimetals at charge neutrality

    Science.gov (United States)

    Holder, Tobias; Huang, Chia-Wei; Ostrovsky, Pavel M.

    2017-11-01

    Weyl semimetals have been intensely studied as a three-dimensional realization of a Dirac-like excitation spectrum where the conduction bands and valence bands touch at isolated Weyl points in momentum space. Like in graphene, this property entails various peculiar electronic properties. However, recent theoretical studies have suggested that resonant scattering from rare regions can give rise to a nonzero density of states even at charge neutrality. Here, we give a detailed account of this effect and demonstrate how the semimetallic nature is suppressed at the lowest scales. To this end, we develop a self-consistent T -matrix approach to investigate the density of states beyond the limit of weak disorder. Our results show a nonvanishing density of states at the Weyl point, which exhibits a nonanalytic dependence on the impurity density. This unusually strong effect of rare regions leads to a revised estimate for the conductivity close to the Weyl point and emphasizes possible deviations from semimetallic behavior in dirty Weyl semimetals at charge neutrality even with very low impurity concentration.

  1. Electronic properties and optical absorption of a phosphorene quantum dot

    Science.gov (United States)

    Liang, F. X.; Ren, Y. H.; Zhang, X. D.; Jiang, Z. T.

    2018-03-01

    Using the tight-binding Hamiltonian approach, we theoretically study the electronic and optical properties of a triangular phosphorene quantum dot (PQD) including one normal zigzag edge and two skewed armchair edges (ZAA-PQD). It is shown that the energy spectrum can be classified into the filled band (FB), the zero-energy band (ZB), and the unfilled band (UB). Numerical calculations of the FB, ZB, and UB probability distributions show that the FB and the UB correspond to the bulk states, while the ZB corresponds to the edge states, which appear on all of the three edges of the ZAA-PQD sharply different from the other PQDs. We also find that the strains and the electric fields can affect the energy levels inhomogeneously. Then the optical properties of the ZAA-PQD are investigated. There appear some strong low-energy optical absorption peaks indicating its sensitive low-energy optical response that is absent in other PQDs. Moreover, the strains and the electric fields can make inhomogeneous influences on the optical spectrum of the ZAA-PQD. This work may provide a useful reference for designing the electrical, mechanical, and optical PQD devices.

  2. Beyond leaf color: Comparing camera-based phenological metrics with leaf biochemical, biophysical, and spectral properties throughout the growing season of a temperate deciduous forest

    Science.gov (United States)

    Yang, Xi; Tang, Jianwu; Mustard, John F.

    2014-03-01

    Plant phenology, a sensitive indicator of climate change, influences vegetation-atmosphere interactions by changing the carbon and water cycles from local to global scales. Camera-based phenological observations of the color changes of the vegetation canopy throughout the growing season have become popular in recent years. However, the linkages between camera phenological metrics and leaf biochemical, biophysical, and spectral properties are elusive. We measured key leaf properties including chlorophyll concentration and leaf reflectance on a weekly basis from June to November 2011 in a white oak forest on the island of Martha's Vineyard, Massachusetts, USA. Concurrently, we used a digital camera to automatically acquire daily pictures of the tree canopies. We found that there was a mismatch between the camera-based phenological metric for the canopy greenness (green chromatic coordinate, gcc) and the total chlorophyll and carotenoids concentration and leaf mass per area during late spring/early summer. The seasonal peak of gcc is approximately 20 days earlier than the peak of the total chlorophyll concentration. During the fall, both canopy and leaf redness were significantly correlated with the vegetation index for anthocyanin concentration, opening a new window to quantify vegetation senescence remotely. Satellite- and camera-based vegetation indices agreed well, suggesting that camera-based observations can be used as the ground validation for satellites. Using the high-temporal resolution dataset of leaf biochemical, biophysical, and spectral properties, our results show the strengths and potential uncertainties to use canopy color as the proxy of ecosystem functioning.

  3. Modifying the electronic and optical properties of carbon nanotubes

    Science.gov (United States)

    Kinder, Jesse M.

    The intrinsic electronic and optical properties of carbon nanotubes make them promising candidates for circuit elements and LEDs in nanoscale devices. However, applied fields and interactions with the environment can modify these intrinsic properties. This dissertation is a theoretical study of perturbations to an ideal carbon nanotube. It illustrates how transport and optical properties of carbon nanotubes can be adversely affected or intentionally modified by the local environment. The dissertation is divided into three parts. Part I analyzes the effect of a transverse electric field on the single-electron energy spectrum of semiconducting carbon nanotubes. Part II analyzes the effect of the local environment on selection rules and decay pathways relevant to dark excitons. Part III is a series of 26 appendices. Two different models for a transverse electric field are introduced in Part I. The first is a uniform field perpendicular to the nanotube axis. This model suggests the field has little effect on the band gap until it exceeds a critical value that can be tuned with strain or a magnetic field. The second model is a transverse field localized to a small region along the nanotube axis. The field creates a pair of exponentially localized bound states but has no effect on the band gap for particle transport. Part II explores the physics of dark excitons in carbon nanotubes. Two model calculations illustrate the effect of the local environment on allowed optical transitions and nonradiative recombination pathways. The first model illustrates the role of inversion symmetry in the optical spectrum. Broken inversion symmetry may explain low-lying peaks in the exciton spectrum of boron nitride nanotubes and localized photoemission around impurities and interfaces in carbon nanotubes. The second model in Part II suggests that free charge carriers can mediate an efficient nonradiative decay process for dark excitons in carbon nanotubes. The appendices in Part III

  4. Electronic, Optical, and Thermal Properties of Reduced-Dimensional Semiconductors

    Science.gov (United States)

    Huang, Shouting

    Reduced-dimensional materials have attracted tremendous attention because of their new physics and exotic properties, which are of great interests for fundamental science. More importantly, the manipulation and engineering of matter on an atomic scale yield promising applications for many fields including nanoelectronics, nanobiotechnology, environments, and renewable energy. Because of the unusual quantum confinement and enhanced surface effect of reduced-dimensional materials, traditional empirical models suffer from necessary but unreliable parameters extracted from previously-studied bulk materials. In this sense, quantitative, parameter-free approaches are highly useful for understanding properties of reduced-dimensional materials and, furthermore, predicting their novel applications. The first-principles density functional theory (DFT) is proven to be a reliable and convenient tool. In particular, recent progress in many-body perturbation theory (MBPT) makes it possible to calculate excited-state properties, e.g., quasiparticle (QP) band gap and optical excitations, by the first-principles approach based on DFT. Therefore, during my PhD study, I employed first-principles calculations based on DFT and MBPT to systematically study fundamental properties of typical reduced-dimensional semiconductors, i.e., the electronic structure, phonons, and optical excitations of core-shell nanowires (NWs) and graphene-like two-dimensional (2D) structures of current interests. First, I present first-principles studies on how to engineer band alignments of nano-sized radial heterojunctions, Si/Ge core-shell NWs. Our calculation reveals that band offsets in these one-dimensional (1D) nanostructures can be tailored by applying axial strain or varying core-shell sizes. In particular, the valence band offset can be efficiently tuned across a wide range and even be diminished via applied strain. Two mechanisms contribute to this tuning of band offsets. Furthermore, varying the

  5. Proposed ultraviolet free-electron laser at Brookhaven National Laboratory: A source for time-resolved biochemical spectroscopy

    International Nuclear Information System (INIS)

    Johnson, E.D.; Sutherland, J.C.; Laws, W.R.

    1992-01-01

    Brookhaven National Laboratory is designing an ultraviolet free- electron laser (UV-FEL) user facility that will provide pico-second and sub-picosecond pulses of coherent ultraviolet radiation for wavelengths from 300 to 75 nm. Pulse width will be variable from abut 7 ps to ∼ 200 fs, with repetition rates as high as 10 4 Hz, single pulse energies > 1 mJ and hence peak pulse power >200 MW and average beam power > 10 W. The facility will be capable of ''pump-probe'' experiments utilizing the FEL radiation with: (1) synchronized auxiliary lasers, (2) a second, independently tunable FEL beam, or (3) broad-spectrum, high-intensity x-rays from the adjacent National Synchrotron Light Source. The UV-FEL consists of a high repetition rate recirculating superconducting linear accelerator which feeds pulses of electrons to two magnetic wigglers. Within these two devices, photons from tunable ''conventional'' laser would be frequency multiplied and amplified. By synchronously tuning the seed laser and modulating the energy of the electron beam, tuning of as much as 60% in wavelength is possible between alternating pulses supplied to different experimental stations, with Fourier transform limited resolution. Thus, up to four independent experiments may operate at one time, each with independent control of the wavelength and pulse duration. The UV-FEL will make possible new avenues of inquiry in time studies of diverse field including chemical, surface, and solid state physics, biology and materials science. The experimental area is scheduled to include a station dedicated to biological research. The complement of experimental and support facilities required by the biology station will be determined by the interests of the user community. 7 refs., 5 figs

  6. Improvement of carbon fibre surface properties using electron beam irradiation

    International Nuclear Information System (INIS)

    Eddy Segura Pino; Luci Diva Brocardo Machado; Claudia Giovedi

    2006-01-01

    Carbon fiber-reinforced advance composites have been used for structural applications, mainly due to their mechanical properties, and additional features such as high strength-to-weight ratio, stiffness-to-weight ratio, corrosion resistance and wear properties. The main factor for a good mechanical performance of carbon fiber-reinforced composite is the interfacial interaction between the components that are fiber and polymeric matrix. The greatest challenge is to improve adhesion between components having elasticity modulus which differ by orders of magnitude and furthermore they are immiscible in each other. Another important factor is the sizing material on the carbon fiber, which protects the carbon fiber filaments and must be compatible with the matrix material in order to improve the adhesion process. The interaction of ionizing radiation from electron beam can induce in the irradiated material the formation of very active centers and free radicals. Further evolution of these active species can significantly modify structure and properties not only in the irradiated polymeric matrix but also on the fiber surface. So that, fiber and matrix play an important role in the production of chemical bonds, which promote better adhesion between both materials improving the composite mechanical performance. The aim of this work was to improve the surface properties of the carbon fiber surface using ionizing radiation from an electron beam in order to obtain improvement of the adhesion properties in the resulted composite. Commercial carbon fiber roving of high tensile strength with 12 000 filaments named 12 k, and sizing material of epoxy resin modified by ester groups was studied. EB irradiation has been carried out at the Institute for Nuclear and Energy Research (IPEN) facilities using a 1.5 MeV 37.5 kW Dynamitron electron accelerator model JOB-188. Rovings of carbon fibers with 1.78 g cm -3 density and 0.13 mm thickness were irradiated with 0.555 MeV, 6.43 mA and

  7. Predicting and analyzing DNA-binding domains using a systematic approach to identifying a set of informative physicochemical and biochemical properties

    Science.gov (United States)

    2011-01-01

    Background Existing methods of predicting DNA-binding proteins used valuable features of physicochemical properties to design support vector machine (SVM) based classifiers. Generally, selection of physicochemical properties and determination of their corresponding feature vectors rely mainly on known properties of binding mechanism and experience of designers. However, there exists a troublesome problem for designers that some different physicochemical properties have similar vectors of representing 20 amino acids and some closely related physicochemical properties have dissimilar vectors. Results This study proposes a systematic approach (named Auto-IDPCPs) to automatically identify a set of physicochemical and biochemical properties in the AAindex database to design SVM-based classifiers for predicting and analyzing DNA-binding domains/proteins. Auto-IDPCPs consists of 1) clustering 531 amino acid indices in AAindex into 20 clusters using a fuzzy c-means algorithm, 2) utilizing an efficient genetic algorithm based optimization method IBCGA to select an informative feature set of size m to represent sequences, and 3) analyzing the selected features to identify related physicochemical properties which may affect the binding mechanism of DNA-binding domains/proteins. The proposed Auto-IDPCPs identified m=22 features of properties belonging to five clusters for predicting DNA-binding domains with a five-fold cross-validation accuracy of 87.12%, which is promising compared with the accuracy of 86.62% of the existing method PSSM-400. For predicting DNA-binding sequences, the accuracy of 75.50% was obtained using m=28 features, where PSSM-400 has an accuracy of 74.22%. Auto-IDPCPs and PSSM-400 have accuracies of 80.73% and 82.81%, respectively, applied to an independent test data set of DNA-binding domains. Some typical physicochemical properties discovered are hydrophobicity, secondary structure, charge, solvent accessibility, polarity, flexibility, normalized Van Der

  8. Nanostructured hybrid films containing nanophosphor: Fabrication and electronic spectral properties

    Energy Technology Data Exchange (ETDEWEB)

    Camacho, S.A. [Instituto de Biociencias, Letras e Ciencias Exatas, UNESP - Univ Estadual Paulista, Rua Cristovao Colombo, 2265, 15054-000 Sao Jose do Rio Preto, SP (Brazil); Aoki, P.H.B.; Constantino, C.J.L. [Faculdade de Ciencias e Tecnologia, UNESP - Univ Estadual Paulista, Rua Roberto Simonsen, 305, 19060-900 Presidente Prudente, SP (Brazil); Aroca, R.F. [Materials and Surface Science Group, University of Windsor, Windsor, Ont., Canada N9B3P4 (Canada); Pires, A.M., E-mail: anapires@fct.unesp.br [Faculdade de Ciencias e Tecnologia, UNESP - Univ Estadual Paulista, Rua Roberto Simonsen, 305, 19060-900 Presidente Prudente, SP (Brazil)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Hybrid film containing the cationic polyelectrolyte PAH and Y{sub 2}O{sub 3}: Er, Yb nanophosphor. Black-Right-Pointing-Pointer LbL film growth was monitored by absorbance x concentration in UV-Vis absorption. Black-Right-Pointing-Pointer FTIR indicated existence of secondary interactions between PAH - nanophosphor layers. Black-Right-Pointing-Pointer The morphology and the spatial distribution of the LbL film were analyzed by Raman. Black-Right-Pointing-Pointer We observed intense electronic emission lines from doping ions in the micro-Raman. - Abstract: The intensive research of the optical properties of rare-earth ions is due to the high quantum efficiency of their emission, very narrow bands, and excellent fluorescence monochromaticity. The photoluminescence data presented here show that the nanophosphor remains a green emitter in Layer-by-Layer (LbL) films leading to potential application in optical devices or biological labeling. The LbL technique, an established method for thin film fabrication with molecular architecture control, is used in the manufacture of a hybrid film containing the cationic polyelectrolyte poly (allylamine hydrochloride) (PAH) and Y{sub 2}O{sub 3}: Er, Yb nanophosphor. The spectroscopic properties of this luminescent nanomaterial are extracted from the spectral data of the powder, cast film and LbL films. The growth of the LbL film was monitored by absorbance versus concentration plots in ultraviolet-visible (UV-Vis) absorption spectroscopy. The presence of both PAH and nanophosphor in the LbL film was confirmed by Fourier transform infrared (FTIR) absorption spectroscopy. The FTIR data also ruled out the existence of chemical interactions between the PAH and nanophosphor layers, which means that secondary interactions (like Van der Waals forces) might be the driving forces for LbL film growth. The morphology and the spatial distribution of the LbL film components along the film surface were

  9. Noncovalent Intermolecular Interactions in Organic Electronic Materials: Implications for the Molecular Packing vs Electronic Properties of Acenes

    KAUST Repository

    Sutton, Christopher; Risko, Chad; Bredas, Jean-Luc

    2015-01-01

    Noncovalent intermolecular interactions, which can be tuned through the toolbox of synthetic chemistry, determine not only the molecular packing but also the resulting electronic, optical, and mechanical properties of materials derived from π

  10. Phenozan Influence on the Physiological-Biochemical Parameters of the Young Minks Leading to Their Advanced Properties

    Directory of Open Access Journals (Sweden)

    Nikolai A. Balakirev

    2016-01-01

    Full Text Available The antioxidant influence on the physiological-biochemical parameters of productive animals is one of the most important directions in modern animal science. Phenozan is a synthetic antioxidant with high biological activities including those for animals. The positive effects of phenozan on the physiological-biochemical parameters of the mink blood were found. These effects are leading to the intensive growth, strong health, enhancement of the mink fur quality, and so forth. The total amount of the erythrocytes in the mink blood increased by about 4-5% due to phenozan inclusion in the mink diet. Even a more significant increase was found in hemoglobin content in the mink blood and erythrocytes (by about 9.5% and 8.8%, resp. due to phenozan inclusion of 100 mg/day, whereas it was found only by about 6.1–5.3% or 5.5–0.3%, owing to phenozan inclusion of 50 or 150 mg/day. For many other parameters the optimal phenozan concentration was about 100 mg/day per head according to the result obtained for all studied animal groups. Thus, phenozan can be successfully used as a biologically active compound for mink nutrition and is recommended for other farm animals.

  11. Culture of Desmodesmus communis (E.Hegewald E.Hegewald and Its Determination of the Biochemical Properties

    Directory of Open Access Journals (Sweden)

    Rıza Akgül

    2017-04-01

    Full Text Available In this study, culture medium and growth conditions were detected for Desmodesmus communis (E. Hegewald E. Hegewald (Sphaeropleales with KF470792 Accession Number that isolated from Thrace inland water (Bahçedere Stream, Tekirdağ, Turkey and determined by molecular taxonomy techniques. The microalgae was cultured under detected conditions (nutrients, pH, temperature, light density and aeration and when the culture was reached to stationary phase microalgae biomass was harvested for biochemical analysis. Total protein, total lipid, fatty acid and amino acid compositions, vitamin E amounts and variety were detected. Cell density was 9.76x105 colony/ml; dry biomass was 0.762 g/l; chlorophyll-a was 13.3 mg/l in BG11 culture medium (7.5 pH, 24±2ºC, 500 ml/min. aeration. According to biochemical analysis; total protein amount was 42.59% (dw/w; total lipid amount was 5.23% (dw/w and vitamin E amount was 3694.24 µg/glipid. The most abundant fatty acid was linolenic acid (35.18%; amino acid was glutamic acid (46.9 mg/g.

  12. Properties of short-range and long-range correlation energy density functionals from electron-electron coalescence

    International Nuclear Information System (INIS)

    Gori-Giorgi, Paola; Savin, Andreas

    2006-01-01

    The combination of density-functional theory with other approaches to the many-electron problem through the separation of the electron-electron interaction into a short-range and a long-range contribution is a promising method, which is raising more and more interest in recent years. In this work some properties of the corresponding correlation energy functionals are derived by studying the electron-electron coalescence condition for a modified (long-range-only) interaction. A general relation for the on-top (zero electron-electron distance) pair density is derived, and its usefulness is discussed with some examples. For the special case of the uniform electron gas, a simple parametrization of the on-top pair density for a long-range only interaction is presented and supported by calculations within the ''extended Overhauser model.'' The results of this work can be used to build self-interaction corrected short-range correlation energy functionals

  13. Hemostatic properties of the free-electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Cram, G.P. Jr.; Copeland, M.L. [Department of Neurosurgery, Vanderbilt University Medical Center, Nashville, TN 37235 (United States)

    1998-09-02

    We have investigated the hemostatic properties of the free-electron laser (FEL) and compared these properties to the most commonly used commercial lasers in neurosurgery, CO{sub 2} and Nd:YAG, using an acute canine model. Arterial and venous vessels, of varying diameters from 0.1 to 1.0 mm, were divided with all three lasers. Analysis of five wavelengths of the FEL (3.0, 4.5, 6.1, 6.45, and 7.7 microns) resulted in bleeding without evidence of significant coagulation, regardless of whether the vessel was an artery or vein. Hemorrhage from vessels less than 0.4 mm diameter was subsequently easily controlled with Gelfoam registered (topical hemostatic agent) alone, whereas larger vessels required bipolar electrocautery. No significant charring, or contraction of the surrounding parenchyma was noted with any of the wavelengths chosen from FEL source. The CO{sub 2} laser, in continuous mode, easily coagulated vessels with diameters of 4 mm and less, while larger vessels displayed significant bleeding requiring bipolar electrocautery for control. Tissue charring was noted with application of the CO{sub 2} laser. In super pulse mode, the CO{sub 2} laser exhibited similar properties, including significant charring of the surrounding parenchyma. The Nd:YAG coagulated all vessels tested up to 1.4 mm, which was the largest diameter cortical artery found, however this laser displayed significant and extensive contraction and retraction of the surrounding parenchyma. In conclusion, the FEL appears to be a poor hemostatic agent. Our results did not show any benefit of the FEL over current conventional means of achieving hemostasis. However, control of hemorrhage was easily achieved with currently used methods of hemostasis, namely Gelfoam registered or bipolar electrocuatery. Although only cortical vessels in dogs were tested, we feel this data can be applied to all animals, including humans, and the peripheral, as well as central, vasculature, as our data on the CO{sub 2} and

  14. Hemostatic properties of the free-electron laser

    International Nuclear Information System (INIS)

    Cram, G.P. Jr.; Copeland, M.L.

    1998-01-01

    We have investigated the hemostatic properties of the free-electron laser (FEL) and compared these properties to the most commonly used commercial lasers in neurosurgery, CO 2 and Nd:YAG, using an acute canine model. Arterial and venous vessels, of varying diameters from 0.1 to 1.0 mm, were divided with all three lasers. Analysis of five wavelengths of the FEL (3.0, 4.5, 6.1, 6.45, and 7.7 microns) resulted in bleeding without evidence of significant coagulation, regardless of whether the vessel was an artery or vein. Hemorrhage from vessels less than 0.4 mm diameter was subsequently easily controlled with Gelfoam registered (topical hemostatic agent) alone, whereas larger vessels required bipolar electrocautery. No significant charring, or contraction of the surrounding parenchyma was noted with any of the wavelengths chosen from FEL source. The CO 2 laser, in continuous mode, easily coagulated vessels with diameters of 4 mm and less, while larger vessels displayed significant bleeding requiring bipolar electrocautery for control. Tissue charring was noted with application of the CO 2 laser. In super pulse mode, the CO 2 laser exhibited similar properties, including significant charring of the surrounding parenchyma. The Nd:YAG coagulated all vessels tested up to 1.4 mm, which was the largest diameter cortical artery found, however this laser displayed significant and extensive contraction and retraction of the surrounding parenchyma. In conclusion, the FEL appears to be a poor hemostatic agent. Our results did not show any benefit of the FEL over current conventional means of achieving hemostasis. However, control of hemorrhage was easily achieved with currently used methods of hemostasis, namely Gelfoam registered or bipolar electrocuatery. Although only cortical vessels in dogs were tested, we feel this data can be applied to all animals, including humans, and the peripheral, as well as central, vasculature, as our data on the CO 2 and Nd:YAG appear to closely

  15. Phonon spectra, electronic, and thermodynamic properties of WS2 nanotubes.

    Science.gov (United States)

    Evarestov, Robert A; Bandura, Andrei V; Porsev, Vitaly V; Kovalenko, Alexey V

    2017-11-15

    Hybrid density functional theory calculations are performed for the first time on the phonon dispersion and thermodynamic properties of WS 2 -based single-wall nanotubes. Symmetry analysis is presented for phonon modes in nanotubes using the standard (crystallographic) factorization for line groups. Symmetry and the number of infra-red and Raman active modes in achiral WS 2 nanotubes are given for armchair and zigzag chiralities. It is demonstrated that a number of infrared and Raman active modes is independent on the nanotube diameter. The zone-folding approach is applied to find out an impact of curvature on electron and phonon band structure of nanotubes rolled up from the monolayer. Phonon frequencies obtained both for layers and nanotubes are used to compute the thermal contributions to their thermodynamic functions. The temperature dependences of energy, entropy, and heat capacity of nanotubes are estimated with respect to those of the monolayer. The role of phonons in the stability estimation of nanotubes is discussed based on Helmholtz free energy calculations. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  16. Improvement in properties of plastic teeth by electron beam irradiation

    International Nuclear Information System (INIS)

    Sano, Yuko; Ishikawa, Shun-ichi; Seguchi, Tadao

    2011-01-01

    Improvement of the comfort and esthetics of artificial plastic teeth is desirable for the recently increasing numbers of elderly in society. Plastic teeth made of polycarbonate (PC) were modified by electron beam (EB) irradiation under specific conditions, and the change in the chemical properties of the PC was investigated. The water absorption, glucose attachment, level of bis-phenol-A (BPA) extraction, maltose adhesion, and mucin adhesion on the PC teeth were measured before and after EB irradiation. EB irradiation to a dose of 3.5 kGy at 150 o C in a nitrogen gas atmosphere reduced the water absorption by 20%, glucose absorption by 40%, maltose adhesion by 20%, and the amount of various amino acids, formed as the hydrolysis products of mucin, adhering on the PC teeth were reduced by 60-99%. The BPA content was lower than the detection limit for analysis of both the original and the EB irradiated PC teeth. - Highlights: → Radiation improvement of polycarbonate for plastic teeth by EB irradiation 3.5 kGy at 150 o C in inert gas. → Water and glucose absorption and maltose adhesion on PC teeth were much reduced. → Bis-phenol-A content from PC teeth was lower than the detection limit after irradiation.

  17. Structure, electronic properties, and aggregation behavior of hydroxylated carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    López-Oyama, A. B.; Silva-Molina, R. A.; Ruíz-García, J.; Guirado-López, R. A., E-mail: guirado@ifisica.uaslp.mx [Instituto de Física “Manuel Sandoval Vallarta,” Universidad Autónoma de San Luis Potosí, Álvaro Obregón 64, 78000 San Luis Potosí, San Luis Potosí (Mexico); Gámez-Corrales, R. [Departamento de Física, Universidad de Sonora, Apartado Postal 5-088, 83190, Hermosillo, Sonora (Mexico)

    2014-11-07

    We present a combined experimental and theoretical study to analyze the structure, electronic properties, and aggregation behavior of hydroxylated multiwalled carbon nanotubes (OH–MWCNT). Our MWCNTs have average diameters of ∼2 nm, lengths of approximately 100–300 nm, and a hydroxyl surface coverage θ∼0.1. When deposited on the air/water interface the OH–MWCNTs are partially soluble and the floating units interact and link with each other forming extended foam-like carbon networks. Surface pressure-area isotherms of the nanotube films are performed using the Langmuir balance method at different equilibration times. The films are transferred into a mica substrate and atomic force microscopy images show that the foam like structure is preserved and reveals fine details of their microstructure. Density functional theory calculations performed on model hydroxylated carbon nanotubes show that low energy atomic configurations are found when the OH groups form molecular islands on the nanotube's surface. This patchy behavior for the OH species is expected to produce nanotubes having reduced wettabilities, in line with experimental observations. OH doping yields nanotubes having small HOMO–LUMO energy gaps and generates a nanotube → OH direction for the charge transfer leading to the existence of more hole carriers in the structures. Our synthesized OH–MWCNTs might have promising applications.

  18. Properties of TBCCO 2212 thin films for electronic applications

    International Nuclear Information System (INIS)

    Andreone, A.; Cassinese, A.; Palomba, F.; Pica, G.; Salluzzo, M.; Malandrino, G.; Ancarani, V.; Fragala, I.L.

    1999-01-01

    The authors report on the synthesis and structural and electrical characterization of high quality Tl 2 Ba 2 Ca 1 Cu 2 O x superconducting thin films. The samples have been prepared ex-situ by a combined approach of metal-Organic Chemical Vapor Deposition (MOCVD) and thallium vapor diffusion. The films have been grown on 10x10 mm 2 (100) LaAlO 3 substrates. X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analyses (EDX) have investigated the morphological and compositional nature of the films. The transport properties have been measured using both a four-probes and an inductive method. The highest critical temperature and critical current density are 104 K and 1 x 10 6 A/cm 2 respectively. The microwave response of two samples has been studied using a microstrip resonator technique. The best surface resistance values are below 200 μΩ at 1.2 GHz and 4.2 K. Measurements of the field dependence of the surface resistance have been performed

  19. Electronic structure, phase transitions and diffusive properties of elemental plutonium

    Science.gov (United States)

    Setty, Arun; Cooper, B. R.

    2003-03-01

    We present a SIC-LDA-LMTO based study of the electronic structure of the delta, alpha and gamma phases of plutonium, and also of the alpha and gamma phases of elemental cerium. We find excellent agreement with the experimental densities and magnetic properties [1]. Furthermore, detailed studies of the computational densities of states for delta plutonium, and comparison with the experimental photoemission spectrum [2], provide evidence for the existence of an unusual fluctuating valence state. Results regarding the vacancy formation and self-diffusion in delta plutonium will be presented. Furthermore, a study of interface diffusion between plutonium and steel (technologically relevant in the storage of spent fuel) or other technologically relevant alloys will be included. Preliminary results regarding gallium stabilization of delta plutonium, and of plutonium alloys will be presented. [1] M. Dormeval et al., private communication (2001). [2] A. J. Arko, J. J. Joyce, L. Morales, J. Wills, and J. Lashley et. al., Phys. Rev. B, 62, 1773 (2000). [3] B. R. Cooper et al, Phil. Mag. B 79, 683 (1999); B.R. Cooper, Los Alamos Science 26, 106 (2000)); B.R. Cooper, A.K. Setty and D.L.Price, to be published.

  20. Structural phase transition and electronic properties in samarium chalcogenides

    Energy Technology Data Exchange (ETDEWEB)

    Panwar, Y. S., E-mail: yspanwar2011@gmail.com [Department of Physics, Govt. New Science College Dewas-455001 (India); Aynyas, Mahendra [Department of Physics, C.S.A. Govt. P.G. College, Sehore, 466001 (India); Pataiya, J.; Sanyal, Sankar P. [Department of Physics, Barkatullah University, Bhopal, 462026 (India)

    2016-05-06

    The electronic structure and high pressure properties of samarium monochalcogenides SmS, SmSe and SmTe have been reported by using tight binding linear muffin-tin-orbital (TB-LMTO) method within the local density approximation (LDA). The total energy as a function of volume is evaluated. It is found that these monochalcogenides are stable in NaCl-type structure under ambient pressure. We predict a structural phase transition from NaCl-type (B{sub 1}-phase) structure to CsCl-type (B{sub 2}-type) structure for these compounds. Phase transition pressures were found to be 1.7, 4.4 and 6.6 GPa, for SmS, SmSe and SmTe respectively. Apart from this, the lattice parameter (a{sub 0}), bulk modulus (B{sub 0}), band structure (BS) and density of states (DOS) are calculated. From energy band diagram we observed that these compounds exhibit metallic character. The calculated values of equilibrium lattice parameter and phase transition pressure are in general good agreement with available data.

  1. Dynamical photo-induced electronic properties of molecular junctions

    Science.gov (United States)

    Beltako, K.; Michelini, F.; Cavassilas, N.; Raymond, L.

    2018-03-01

    Nanoscale molecular-electronic devices and machines are emerging as promising functional elements, naturally flexible and efficient, for next-generation technologies. A deeper understanding of carrier dynamics in molecular junctions is expected to benefit many fields of nanoelectronics and power devices. We determine time-resolved charge current flowing at the donor-acceptor interface in molecular junctions connected to metallic electrodes by means of quantum transport simulations. The current is induced by the interaction of the donor with a Gaussian-shape femtosecond laser pulse. Effects of the molecular internal coupling, metal-molecule tunneling, and light-donor coupling on photocurrent are discussed. We then define the time-resolved local density of states which is proposed as an efficient tool to describe the absorbing molecule in contact with metallic electrodes. Non-equilibrium reorganization of hybridized molecular orbitals through the light-donor interaction gives rise to two phenomena: the dynamical Rabi shift and the appearance of Floquet-like states. Such insights into the dynamical photoelectronic structure of molecules are of strong interest for ultrafast spectroscopy and open avenues toward the possibility of analyzing and controlling the internal properties of quantum nanodevices with pump-push photocurrent spectroscopy.

  2. Electronic structure properties of deep defects in hBN

    Science.gov (United States)

    Dev, Pratibha; Prdm Collaboration

    In recent years, the search for room-temperature solid-state qubit (quantum bit) candidates has revived interest in the study of deep-defect centers in semiconductors. The charged NV-center in diamond is the best known amongst these defects. However, as a host material, diamond poses several challenges and so, increasingly, there is an interest in exploring deep defects in alternative semiconductors such as hBN. The layered structure of hBN makes it a scalable platform for quantum applications, as there is a greater potential for controlling the location of the deep defect in the 2D-matrix through careful experiments. Using density functional theory-based methods, we have studied the electronic and structural properties of several deep defects in hBN. Native defects within hBN layers are shown to have high spin ground states that should survive even at room temperature, making them interesting solid-state qubit candidates in a 2D matrix. Partnership for Reduced Dimensional Material (PRDM) is part of the NSF sponsored Partnerships for Research and Education in Materials (PREM).

  3. Magnetostructural, mechanical and electronic properties of manganese tetraboride

    Directory of Open Access Journals (Sweden)

    Yongcheng Liang

    2015-11-01

    Full Text Available Magnetostructural stabilities, mechanical behaviors and electronic structures of various phases of manganese tetraboride (MnB4 have been investigated systematically by density functional theory (DFT based first-principles methods. It is found that MnB4 undergoes temperature-induced phase transitions from the nonmagnetic (NM monoclinic mP20 structure to the ferromagnetic (FM orthorhombic oP10 structure at 438 K, then to the antiferromagnetic (AFM orthorhombic oP10 structure at 824 K. We reveal that the NM insulating mP20 phase stabilizes by the Peierls distortion breaking the structural degeneracy, while the FM and AFM metallic oP10 phases stabilize by the Stoner magnetism lifting the spin degeneracy. Furthermore, the calculated mechanical properties show that the NM mP20, FM oP10, and AFM oP10 phases exhibit low compressibility and high hardness, which originate from their three-dimensional covalent boron networks. Therefore, this unique temperature-assisted insulator-metal transition, strong stiffness and high hardness suggest that MnB4 may find promising technological applications as thermoelectric switches and field effect transistors at the extreme conditions.

  4. Optical properties of electron-irradiated gallium phosphide

    International Nuclear Information System (INIS)

    Brailovskii, E.Yu.; Grigoryan, N.E.; Eritsyan, G.N.

    1980-01-01

    Results of optical absorption and photoconductivity measurements in the 0.1 to 2.4 eV range of GaP crystals irradiated with 7.5 and 50 MeV electrons are presented. The absorption of irradiated crystals near the edge can be represented by two exponential regions. In the free carrier absorption region one can observe as a result of irradiation a decrease of the power index p in the dependence α proportional to lambdap. Photoconductivity with long-time relaxation takes place in the spectral interval where the additional absorption is observed. The quenching of residual conductivity can be observed at hν=1.0eV. Variations in absorption and photoconductivity are attributed to the 'tails' of density states near the zone edges arising at introduction of both point defects and disordered regions. At hν=2.1eV one can observe a resonance band which is attributed to intra-centre transitions on point defects. A recovery of the optical properties of GaP at annealing is studied. In heavily irradiated GaP crystals point defects can form gatherings which display themselves as disordered regions. (author)

  5. Electronic properties of interfaces produced by silicon wafer hydrophilic bonding

    Energy Technology Data Exchange (ETDEWEB)

    Trushin, Maxim

    2011-07-15

    The thesis presents the results of the investigations of electronic properties and defect states of dislocation networks (DNs) in silicon produced by wafers direct bonding technique. A new insight into the understanding of their very attractive properties was succeeded due to the usage of a new, recently developed silicon wafer direct bonding technique, allowing to create regular dislocation networks with predefined dislocation types and densities. Samples for the investigations were prepared by hydrophilic bonding of p-type Si (100) wafers with same small misorientation tilt angle ({proportional_to}0.5 ), but with four different twist misorientation angles Atw (being of < , 3 , 6 and 30 , respectively), thus giving rise to the different DN microstructure on every particular sample. The main experimental approach of this work was the measurements of current and capacitance of Schottky diodes prepared on the samples which contained the dislocation network at a depth that allowed one to realize all capabilities of different methods of space charge region spectroscopy (such as CV/IV, DLTS, ITS, etc.). The key tasks for the investigations were specified as the exploration of the DN-related gap states, their variations with gradually increasing twist angle Atw, investigation of the electrical field impact on the carrier emission from the dislocation-related states, as well as the establishing of the correlation between the electrical (DLTS), optical (photoluminescence PL) and structural (TEM) properties of DNs. The most important conclusions drawn from the experimental investigations and theoretical calculations can be formulated as follows: - DLTS measurements have revealed a great difference in the electronic structure of small-angle (SA) and large-angle (LA) bonded interfaces: dominating shallow level and a set of 6-7 deep levels were found in SA-samples with Atw of 1 and 3 , whereas the prevalent deep levels - in LA-samples with Atw of 6 and 30 . The critical twist

  6. Electron donating and acid-base properties of cerium oxide and its mixed oxides with alumina

    International Nuclear Information System (INIS)

    Sugunan, S.; Jalaja, J.M.

    1994-01-01

    The electron donating properties of cerium oxide activated at 300, 500 and 800 degC and of its mixed oxides with alumina were examined based on the adsorption of electron acceptors exhibiting different electron affinities. The surface acidity/basicity of the oxides was determined by titrimetry; the H 0,max values are given. The limit of electron transfer from the oxide surface lies within the region of 1.77 and 2.40 eV in terms of the electron affinity of the electron acceptor. Cerium oxide promotes the electron donor nature of alumina while leaving the limit of electron transfer unchanged. 2 tabs., 4 figs., 13 refs

  7. Biochemical properties of the plasma of rats with the experimentally induced hepatitis after oral administration of sodium diclofenac

    Directory of Open Access Journals (Sweden)

    V. Gryshchenko

    2017-04-01

    Full Text Available We conducted an analysis of the metabolic activity of the liver and defined the peculiarities of biochemical parameters and macroelement composition of blood plasma of rats with experimentally induced toxic hepatitis. Hepatopathology was modeled by oral administration of sodium diclofenac at a dose of 12.5 mg/kg of body mass to rats during 14 days. For the preparation of plasma, rat blood was collected from the abdominal aorta into test-tubes with heparin, and then it was centrifuged at 1500 rev./min for 15–20 min. Then we studied biochemical parameters of blood indicators (level of total protein, albumin, total and conjugated bilirubin, glucose, creatinine, urea, triacylglycerols, cholesterol, thymol test value, activities of ALT, AST, LP and GGT, amylase and lipase and also its macroelement composition: concentration of sodium, potassium, phosphorus, calcium, magnesium and chlorine using automatic biochemical analyzer «BioSystem A15» (Spain according to the recommendations of the International Federation of Clinical Chemistry (IFCC Experts Panel. The results of the introduction in the laboratory rats of drug-induced toxic hepatitis indicate a decrease of metabolic activity of hepatocytes under this hepatopathology. The results showed a decrease in total protein by 17%, albumin by 11%, glucose by 6% , triacylglycerols by 53%, cholesterol by 54%, and an appreciable increase in thymol test value (by a factor of 2.8. Besides this, disruption of the liver pigment function, development of cytolytic syndrome and intrahepatic cholestasis were revealed in the affected animals. The increased activity of the studied blood enzymes (ALT by 28%, AST by 45%, LP by 30%, GGT by a factor of 2.1 confirmed these disruptions. The increase in AST/ALT by 12% ratio confirmed destructive changes in cell membranes, including mitochondrial membranes, caused by metabolic changes under the toxic influence of sodium diclofenac. The increased activities of α-amylase by

  8. Research of the Electron Cyclotron Emission with Vortex Property excited by high power high frequency Gyrotron

    Science.gov (United States)

    Goto, Yuki; Kubo, Shin; Tsujimura, Tohru; Takubo, Hidenori

    2017-10-01

    Recently, it has been shown that the radiation from a single electron in cyclotron motion has vortex property. Although the cyclotron emission exists universally in nature, the vortex property has not been featured because this property is normally cancelled out due to the randomness in gyro-phase of electrons and the development of detection of the vortex property has not been well motivated. In this research, we are developing a method to generate the vortex radiation from electrons in cyclotron motion with controlled gyro-phase. Electron that rotates around the uniform static magnetic field is accelerated by right-hand circular polarized (RHCP) radiation resonantly when the cyclotron frequency coincides with the applied RHCP radiation frequency. A large number of electrons can be coherently accelerated in gyro-phase by a RHCP high power radiation so that these electrons can radiate coherent emission with vortex feature. We will show that vortex radiation created by purely rotating electrons for the first time.

  9. Electronic properties of assemblies of zno quantum dots

    NARCIS (Netherlands)

    Roest, Aarnoud Laurens

    2003-01-01

    Electron transport in an assembly of ZnO quantum dots has been studied using an electrochemically gated transistor. The electron mobility shows a step-wise increase as a function of the electron occupation per quantum dot. When the occupation number is below two, transport occurs by tunnelling

  10. NMR studies of actinide carbide and nitride electronic properties

    International Nuclear Information System (INIS)

    Boutard, Jean-Louis

    1976-12-01

    N.M.R. studies applied to 13 C and 15 N in the solid solutions ThCsub(1-x)Nsub(x), UCsub(1-x)Nsub(x) and in the compounds ThCsub(1-x) and U 2 C 3 , were undertaken to study carbon and nitrogen contribution to chemical bonds and magnetism. For THORIUM MONOCARBIDE AND CARBONITRIDE: ThCsub(1-x) and ThCsub(1-x)Nsub(x), the very strong orbital contribution to the frequency shift reveals an important covalent character of the valence band 6d metal and 2p metalloid states. The ThCsub(1-x) band structure stoichiometry variation is due to 6dγ metal states appearing at the Fermi level and is in-opposition to a rigid band model. A non-saturated bond mechanism is suggested. For URANIUM CARBONITRIDE: UCsub(1-x)Nsub(x), in the concentration range in which no magnetic order appears at low temperature (x<0.90), the results are in opposition to a localized 5f 2 configuration model, and show that the uranium fundamental state is non-magnetic. Nevertheless two qualitatively different behaviors exist: nitrogen concentration lower than 40%: and nitrogen concentration higher than 40%. A model is proposed to account for those domains: it relies on the 5f-2p hybridization parameter which is maximum on 2p band edge (UC) and almost nul for UN. For URANIUM SESQUICARBIDE: U 2 C 3 : the N.M.R. line observation at 4.2 K indicates a non-magnetic fundamental state although the magnetic susceptibility presents a maximum at 60 K. Spin fluctuations in 5f bands are proposed to describe the electronic properties of this compound. [fr

  11. Somatic embryogenesis, scanning electron microscopy, histology and biochemical analysis at different developing stages of embryogenesis in six date palm (Phoenix dactylifera L.) cultivars.

    Science.gov (United States)

    Aslam, Junaid; Khan, Saeed Ahmad; Cheruth, Abdul Jaleel; Mujib, Abdul; Sharma, Maheshwar Pershad; Srivastava, Prem Shanker

    2011-10-01

    An efficient somatic embryogenesis system has been established in six date palm (Phoenix dactylifera L.) cultivars (Barhee, Zardai, Khalasah, Muzati, Shishi and Zart). Somatic embryogenesis (SE) was growth regulators and cultivars dependent. Friable embryogenic callus was induced from excised shoot tips on MS medium supplemented with various auxins particularly 2,4-dichlorophenoxyacetic acid (2,4-D, 1.5 mg 1(-l)). Suspension culture increased embryogenesis potentiality. Only a-naphthaleneacetic acid (NAA, 0.5 mg 1(-1)) produced somatic embryos in culture. Somatic embryos germinated and converted into plantlets in N(6)-benzyladenine (BAP, 0.75 mg 1(-l)) added medium following a treatment with thidiazuron (TDZ, 1.0 mg 1(-l)) for maturation. Scanning electron microscopy showed early stages of somatic embryo particularly, globular types, and was in masses. Different developing stages of embryogenesis (heart, torpedo and cotyledonary) were observed under histological preparation of embryogenic callus. Biochemical screening at various stages of somatic embryogenesis (embryogenic callus, somatic embryos, matured, germinated embryos and converted plantlets) of date palm cultivars has been conducted and discussed in detail. The result discussed in this paper indicates that somatic embryos were produced in numbers and converted plantlets can be used as a good source of alternative propagation. Genetic modification to the embryo precursor cell may improve the fruit quality and yield further.

  12. Electronic Structure and Optical Properties Of EuIn2P2

    KAUST Repository

    Singh, Nirpendra

    2011-10-25

    The electronic structures and, optical and magneto‐optical properties of a newly found Zintl compound EuIn2P2 have been investigated within the density‐functional theory using the highly precise full‐potential linear‐augmented‐plane‐wave method. Results of detailed investigation of the electronic structure and related properties are reported.

  13. Electronic transport properties of pentacene single crystals upon exposure to air

    NARCIS (Netherlands)

    Jurchescu, OD; Baas, J; Palstra, TTM; Jurchescu, Oana D.

    2005-01-01

    We report the effect of air exposure on the electronic properties of pentacene single crystals. Air can diffuse reversibly in and out of the crystals and influences the physical properties. We discern two competing mechanisms that modulate the electronic transport. The presence of oxygen increases

  14. Electronic properties in a quantum well structure of Weyl semimetal

    International Nuclear Information System (INIS)

    You, Wen-Long; Zhou, Jiao-Jiao; Wang, Xue-Feng; Oleś, Andrzej M.

    2016-01-01

    We investigate the confined states and transport of three-dimensional Weyl electrons around a one-dimensional external rectangular electrostatic potential. The confined states with finite transverse wave vector exist at energies higher than the half well depth or lower than the half barrier height. The rectangular potential appears completely transparent to the normal incident electrons but not otherwise. The tunneling transmission coefficient is sensitive to their incident angle and shows resonant peaks when their energy coincides with the confined spectra. In addition, for the electrons in the conduction (valence) band through a potential barrier (well), the transmission spectrum has a gap of width increasing with the incident angle. Interestingly, the electron linear zero-temperature conductance over the potential can approach zero when the Fermi energy is aligned to the top and bottom energies of the potential, when only electron beams normal to the potential interfaces can pass through. The considered structure can be used to collimate the Weyl electron beams.

  15. Deducing Electron Properties from Hard X-Ray Observations

    Science.gov (United States)

    Kontar, E. P.; Brown, J. C.; Emslie, A. G.; Hajdas, W.; Holman, G. D.; Hurford, G. J.; Kasparova, J.; Mallik, P. C. V.; Massone, A. M.; McConnell, M. L.; hide

    2011-01-01

    X-radiation from energetic electrons is the prime diagnostic of flare-accelerated electrons. The observed X-ray flux (and polarization state) is fundamentally a convolution of the cross-section for the hard X-ray emission process(es) in question with the electron distribution function, which is in turn a function of energy, direction, spatial location and time. To address the problems of particle propagation and acceleration one needs to infer as much information as possible on this electron distribution function, through a deconvolution of this fundamental relationship. This review presents recent progress toward this goal using spectroscopic, imaging and polarization measurements, primarily from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). Previous conclusions regarding the energy, angular (pitch angle) and spatial distributions of energetic electrons in solar flares are critically reviewed. We discuss the role and the observational evidence of several radiation processes: free-free electron-ion, free-free electron-electron, free-bound electron-ion, photoelectric absorption and Compton backscatter (albedo), using both spectroscopic and imaging techniques. This unprecedented quality of data allows for the first time inference of the angular distributions of the X-ray-emitting electrons and improved model-independent inference of electron energy spectra and emission measures of thermal plasma. Moreover, imaging spectroscopy has revealed hitherto unknown details of solar flare morphology and detailed spectroscopy of coronal, footpoint and extended sources in flaring regions. Additional attempts to measure hard X-ray polarization were not sufficient to put constraints on the degree of anisotropy of electrons, but point to the importance of obtaining good quality polarization data in the future.

  16. Electronic properties of asymmetrical quantum dots dressed by laser field

    Energy Technology Data Exchange (ETDEWEB)

    Kibis, O.V. [Department of Applied and Theoretical Physics, Novosibirsk State Technical University, Karl Marx Avenue 20, 630092 Novosibirsk (Russian Federation); Slepyan, G.Ya.; Maksimenko, S.A. [Institute for Nuclear Problems, Belarus State University, Bobruyskaya St. 11, 220050 Minsk (Belarus); Hoffmann, A. [Institut fuer Festkoerperphysik, Technische Universitaet Berlin, Hardenbergstrasse 36, 10623 Berlin (Germany)

    2012-05-15

    In the present paper, we demonstrate theoretically that the strong non-resonant interaction between asymmetrical quantum dots (QDs) and a laser field results in harmonic oscillations of their band gap. It is shown that such oscillations change the spectrum of elementary electron excitations in QDs: in the absence of the laser pumping there is only one resonant electron frequency, but QDs dressed by the laser field have a set of electron resonant frequencies. One expects that this modification of elementary electron excitations in QDs can be observable in optical experiments. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Electronic structure and chemical properties of superheavy elements

    Energy Technology Data Exchange (ETDEWEB)

    Pershina, V [Gesellschaft fuer Schwerionenforschung (GSI), Helmholtzzentrum fuer Schwerionenforschung Gmbh (Germany)

    2009-12-31

    Relativistic electronic structure calculations of superheavy elements (Z>=104) are analyzed. Preference is given to those related to experimental research. The role of relativistic effects is discussed.

  18. Prokaryotic diversity and biochemical properties in aging artificial pit mud used for the production of Chinese strong flavor liquor.

    Science.gov (United States)

    Sun, Zhongke; Chen, Can; Hou, Xiaoge; Zhang, Jie; Tian, Fengshou; Li, Chengwei

    2017-10-01

    At present, artificial pit mud (APM) is widely used in Chinese liquor-making industry and plays a particular role in the production of Chinese strong flavor liquor (CSFL). However, APM frequently ages during fermentation, thus becoming unsuitable for sustainable use due to its low-quality. The reasons behind, and results of, APM aging during the production of CSFL are not yet understood. Sequencing the V4 region of the 16S rRNA gene shows that prokaryotic diversity is significantly decreased (Shannon's diversity index, P  aging APM. On the phylum level, the increase of Firmicutes and decrease of Proteobacteria are the main consequences of APM aging during the production of CSFL. The counting of cultivatable bacteria confirmed that there was a large increase in Lactobacilli and aerobic spore-forming bacteria in aging low-quality APM (more than twofold). Unexpectedly, the total number of caproic acid-producing bacteria, mainly Clostridia , did not change significantly between the two kinds of APM. Furthermore, biochemical analysis indicates that the pH and the levels of NH 4 + and K + are decreased in aging low-quality APM ( P  aging can be controlled potentially by adjustment of environmental factors and/or supplementation of diminished or missed microorganisms.

  19. Analyzing the performance of PROSPECT model inversion based on different spectral information for leaf biochemical properties retrieval

    Science.gov (United States)

    Sun, Jia; Shi, Shuo; Yang, Jian; Du, Lin; Gong, Wei; Chen, Biwu; Song, Shalei

    2018-01-01

    Leaf biochemical constituents provide useful information about major ecological processes. As a fast and nondestructive method, remote sensing techniques are critical to reflect leaf biochemistry via models. PROSPECT model has been widely applied in retrieving leaf traits by providing hemispherical reflectance and transmittance. However, the process of measuring both reflectance and transmittance can be time-consuming and laborious. Contrary to use reflectance spectrum alone in PROSPECT model inversion, which has been adopted by many researchers, this study proposes to use transmission spectrum alone, with the increasing availability of the latter through various remote sensing techniques. Then we analyzed the performance of PROSPECT model inversion with (1) only transmission spectrum, (2) only reflectance and (3) both reflectance and transmittance, using synthetic datasets (with varying levels of random noise and systematic noise) and two experimental datasets (LOPEX and ANGERS). The results show that (1) PROSPECT-5 model inversion based solely on transmission spectrum is viable with results generally better than that based solely on reflectance spectrum; (2) leaf dry matter can be better estimated using only transmittance or reflectance than with both reflectance and transmittance spectra.

  20. Biochemical Properties of a New Cold-Active Mono- and Diacylglycerol Lipase from Marine Member Janibacter sp. Strain HTCC2649

    Directory of Open Access Journals (Sweden)

    Dongjuan Yuan

    2014-06-01

    Full Text Available Mono- and di-acylglycerol lipase has been applied to industrial usage in oil modification for its special substrate selectivity. Until now, the reported mono- and di-acylglycerol lipases from microorganism are limited, and there is no report on the mono- and di-acylglycerol lipase from bacteria. A predicted lipase (named MAJ1 from marine Janibacter sp. strain HTCC2649 was purified and biochemical characterized. MAJ1 was clustered in the family I.7 of esterase/lipase. The optimum activity of the purified MAJ1 occurred at pH 7.0 and 30 °C. The enzyme retained 50% of the optimum activity at 5 °C, indicating that MAJ1 is a cold-active lipase. The enzyme activity was stable in the presence of various metal ions, and inhibited in EDTA. MAJ1 was resistant to detergents. MAJ1 preferentially hydrolyzed mono- and di-acylglycerols, but did not show activity to triacylglycerols of camellia oil substrates. Further, MAJ1 is low homologous to that of the reported fungal diacylglycerol lipases, including Malassezia globosa lipase 1 (SMG1, Penicillium camembertii lipase U-150 (PCL, and Aspergillus oryzae lipase (AOL. Thus, we identified a novel cold-active bacterial lipase with a sn-1/3 preference towards mono- and di-acylglycerides for the first time. Moreover, it has the potential, in oil modification, for special substrate selectivity.

  1. Electronic transport properties of 4f shell elements of liquid metal using hard sphere Yukawa system

    Science.gov (United States)

    Patel, H. P.; Sonvane, Y. A.; Thakor, P. B.

    2018-04-01

    The electronic transport properties are analyzed for 4f shell elements of liquid metals. To examine the electronic transport properties like electrical resistivity (ρ), thermal conductivity (σ) and thermo electrical power (Q), we used our own parameter free model potential with the Hard Sphere Yukawa (HSY) reference system. The screening effect on aforesaid properties has been examined by using different screening functions like Hartree (H), Taylor (T) and Sarkar (S). The correlations of our resultsand other data with available experimental values are intensely promising. Also, we conclude that our newly constructed parameter free model potential is capable of explaining the above mentioned electronic transport properties.

  2. Electronic properties of T graphene-like C-BN sheets: A density functional theory study

    Science.gov (United States)

    Majidi, R.

    2015-11-01

    We have used density functional theory to study the electronic properties of T graphene-like C, C-BN and BN sheets. The planar T graphene with metallic property has been considered. The results show that the presence of BN has a considerable effect on the electronic properties of T graphene. The T graphene-like C-BN and BN sheets show semiconducting properties. The energy band gap is increased by enhancing the number of BN units. The possibility of opening and controlling band gap opens the door for T graphene in switchable electronic devices.

  3. Effects of a Wildfire on Selected Physical, Chemical and Biochemical Soil Properties in a Pinus massoniana Forest in South China

    Directory of Open Access Journals (Sweden)

    Li Xue

    2014-11-01

    Full Text Available Pinus massoniana forests bordering South China are often affected by wildfires. Fires cause major changes in soil properties in many forest types but little is known about the effects of fire on soil properties in these P. massoniana forests. Such knowledge is important for providing a comprehensive understanding of wildfire effects on soil patterns and for planning appropriate long-term forest management in these forests. Changes in soil physical properties, carbon, nutrients, and enzymes were investigated in a P. massoniana forest along a wildfire-induced time span consisting of an unburned soil, and soils 0, one, four, and seven years post-fire. Soil (0–10 cm was collected from burned and unburned sites immediately and one, four, and seven years after a wildfire. The wildfire effects on soil physical and chemical properties and enzyme activities were significantly different among treatment variation, time variation, and treatment-by-time interaction. Significant short-term effects on soil physical, chemical, and biological properties were found, which resulted in a deterioration of soil physical properties by increasing soil bulk density and decreasing macropores and capillary moisture. Soil pH increased significantly in the soil one-year post-fire. Carbon, total nitrogen (N and phosphorus (P, and available N and P increased significantly immediately and one year after the wildfire and decreased progressively to concentrations lower than in the unburned soil. Total potassium (K and exchangeable K increased immediately after the wildfire and then continuously decreased along the burned time-span. Urease, acid phosphatase, and catalase activities significantly decreased compared to those in the unburned soil. In fire-prone P. massoniana forests, wildfires may significantly influence soil physical properties, carbon, nutrients, and enzyme activity.

  4. Electronic and magnetic properties of UPdSn: the itinerant 5f electrons approach

    CERN Document Server

    Sandratskii, L M

    1997-01-01

    Density functional theory, modified to include spin-orbit coupling and an effective orbital field to simulate Hound's second rule, is applied to investigate the magnetic structure and electronic properties of the compound Upends. Our theoretical results are in overall good agreement with experiment. Thus both theory and experiment find the magnetic structure of Upends to be non collinear, the calculated magnetic U-moments being in very good agreement with the measurements. Also, the calculated density of states is found to simulate closely the photoemission spectrum and the very low experimental value of 5 mJ mol sup - sup 1 K sup - sup 2 for the specific heat gamma is reproduced reasonably well by the calculated value of 7.5 mJ mol sup - sup 1 K sup - sup 2. Furthermore, the interconnection of the magnetic structure with the crystal structure is investigated. Here theory and experiment agree concerning the planar non collinear antiferromagnetic configuration in the orthorhombic crystal structure and for the ...

  5. Electronic properties of Mn-phthalocyanine–C60 bulk heterojunctions: Combining photoemission and electron energy-loss spectroscopy

    International Nuclear Information System (INIS)

    Roth, Friedrich; Herzig, Melanie; Knupfer, Martin; Lupulescu, Cosmin; Darlatt, Erik; Gottwald, Alexander; Eberhardt, Wolfgang

    2015-01-01

    The electronic properties of co-evaporated mixtures (blends) of manganese phthalocyanine and the fullerene C 60 (MnPc:C 60 ) have been studied as a function of the concentration of the two constituents using two supplementary electron spectroscopic methods, photoemission spectroscopy (PES) and electron energy-loss spectroscopy (EELS) in transmission. Our PES measurements provide a detailed picture of the electronic structure measured with different excitation energies as well as different mixing ratios between MnPc and C 60 . Besides a relative energy shift, the occupied electronic states of the two materials remain essentially unchanged. The observed energy level alignment is different compared to that of the related CuPc:C 60 bulk heterojunction. Moreover, the results from our EELS investigations show that, despite the rather small interface interaction, the MnPc related electronic excitation spectrum changes significantly by admixing C 60 to MnPc thin films

  6. Electronic structure and optical properties of thorium monopnictides

    Indian Academy of Sciences (India)

    We have calculated the electronic density of states (DOS) and dielectric function for the ThX (X = P, As and Sb) using the linear muffin tin orbital method within atomic sphere approximation (LMTO–ASA) including the combined correction terms. The calculated electronic DOS of ThSb has been compared with the available ...

  7. Electronic structure and equilibrium properties of hcp titanium

    Indian Academy of Sciences (India)

    The electronic structures of hexagonal-close-packed divalent titanium (3-d) and zirconium (4-d) transition metals are studied by using a non-local model potential method. From the present calculation of energy bands, Fermi energy, density of states and the electronic heat capacity of these two metals are determined and ...

  8. First principle study of structural, electronic and fermi surface properties of aluminum praseodymium

    Science.gov (United States)

    Shugani, Mani; Aynyas, Mahendra; Sanyal, S. P.

    2018-05-01

    We present a structural, Electronic and Fermi surface properties of Aluminum Praseodymium (AlPr) using First-principles density functional calculation by using full potential linearized augmented plane wave (FP-LAPW) method within generalized gradient approximation (GGA). The ground state properties along with electronic and Fermi surface properties are studied. It is found that AlPr is metallic and the bonding between Al and Pr is covalent.

  9. Study of 60 Co gamma radiation effects on the biochemical, biological and immunological properties of the Bothrops jararaca venom

    International Nuclear Information System (INIS)

    Guarnieri, M.C.

    1992-01-01

    Gamma radiation, by including different modifications on the toxic, enzymatic and immunological activities of proteins, could be an useful implement for detoxification of snake venoms. The present work was done to study the mechanism of action and effects of gamma rays on the Bothrops jararaca venom, determining the radiation dose that attenuates the toxic and enzymatic activities maintaining the immunological properties of venom, and also the most important free radicals on this process. The results of immuno diffusion, immunoblotting, immunoprecipitation, immunization of mice and rabbits, and neutralization tests, showed the maintenance of antigenic and immunogenic properties and decrease of neutralizing capacity of antibodies induced by 3,000 and 4,000 Gy irradiated venom. Since the immunological properties were the most radioresistant, it was possible to determine the dose of 2,000 Gy, as the ideal radiation dose in the treatment of venoms aiming the improvement of the immunization schedule to obtain bothropic antisera. (author). 164 refs, 19 tabs, 54 figs

  10. Influence of different metal ions on the ultrastructure, biochemical properties, and protein localization of the K562 cell nuclear matrix.

    Science.gov (United States)

    Neri, L M; Bortul, R; Zweyer, M; Tabellini, G; Borgatti, P; Marchisio, M; Bareggi, R; Capitani, S; Martelli, A M

    1999-06-01

    The higher order of chromatin organization is thought to be determined by the nuclear matrix, a mainly proteinaceous structure that would act as a nucleoskeleton. The matrix is obtained from isolated nuclei by a series of extraction steps involving the use of high salt and nonspecific nucleases, which remove chromatin and other loosely bound components. It is currently under debate whether these structures, isolated in vitro by unphysiological extraction buffers, correspond to a nucleoskeleton existing in vivo. In most cell types investigated, the nuclear matrix does not spontaneously resist these extractions steps; rather, it must be stabilized before the application of extracting agents. In this study nuclei, isolated from K562 human erythroleukemia cells, were stabilized by incubation with different metal ions (Ca2+, Cu2+, Zn2+, Cd2+), and the matrix was obtained by extraction with 2 M NaCl. By means of ultrastructural analysis of the resulting structures, we determined that, except for Ca2+, all the other metals induced a stabilization of the matrix, which retained the inner fibrogranular network and residual nucleoli. The biochemical composition, analyzed by two-dimensional gel electrophoresis separation, exhibited a distinct matrix polypeptide pattern, characteristic of each type of stabilizing ion employed. We also investigated to what extent metal ions could maintain in the final structures the original distribution of three inner matrix components, i.e. NuMA, topoisomerase IIalpha, and RNP. Confocal microscopy analysis showed that only NuMa, and, to a lesser extent, topoisomerase IIalpha, were unaffected by stabilization with divalent ions. On the contrary, the fluorescent RNP patterns detected in the resulting matrices were always disarranged, irrespective of the stabilization procedure. These results indicate that several metal ions are powerful stabilizing agents of the nuclear matrix prepared from K562 erythroleukemia cells and also strengthen the

  11. New pbysical methods used in the study of composition, electronic properties and surface phenomena of solid substances. I. Electronic spectroscopies

    International Nuclear Information System (INIS)

    Toderean, A; Ilonca, Gh.

    1981-01-01

    The discovery of different kinds of interactions between solids and fotonic, respectively electronic and ionic beams, leads to the development of many new, very sensitive, physical methods for the study of solids. This monograph tries to present some of these methods, useful in compositional analysis, in the study of electronic properties and of the surface processes of solid substances. This is done from the point of view both of physical phenomena underlying them and of the information obtainable with such methods. But the whole monograph is limited only to the methods based on the electronic properties of the elements existing in the solid probes studied and this paper presents only those of them in which the detected beam is an electronic one, like: ELS, DAPS, ILS, AES, AEAPS, INS, TSS, XPS and UPS. (authors)

  12. Electronic structure and properties of rare earth and actinide intermetallics

    International Nuclear Information System (INIS)

    Kirchmayr, H.R.

    1984-01-01

    There are 188 contributions, experimental and theoretical, a few on rare earth and actinide elements but mostly on rare earth and actinide intermetallic compounds and alloys. The properties dealt with include 1) crystal structure, 2) magnetic properties and magnetic structure, 3) magnetic phase transformations and valence fluctuations, 4) electrical properties and superconductivity and their temperature, pressure and magnetic field dependence. A few papers deal with crystal growth and novel measuring methods. (G.Q.)

  13. Stability, electronic and thermodynamic properties of aluminene from first-principles calculations

    International Nuclear Information System (INIS)

    Yuan, Junhui; Yu, Niannian; Xue, Kanhao; Miao, Xiangshui

    2017-01-01

    Highlights: • We have predicted two NEW stable phases of atomic layer aluminum, buckled and 8-Pmmn aluminene. • We have revealed the electronic structures and bonding characteristics of aluminene. • Thermodynamic properties of aluminene were investigated based on phonon properties. - Abstract: Using first-principles calculations based on density functional theory (DFT), we have investigated the structure stability and electronic properties of both buckled and 8-Pmmn phase aluminene. Phonon dispersion analysis reveals that the buckled and 8-Pmmn aluminene are dynamically stable. The band structure shows that both the buckled and 8-Pmmn aluminene exhibit metallic behavior. Finally, the thermodynamic properties are investigated based on phonon properties.

  14. Stability, electronic and thermodynamic properties of aluminene from first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Junhui [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Yu, Niannian [School of Science, Wuhan University of Technology, Wuhan, Hubei 430070 (China); Xue, Kanhao, E-mail: xkh@hust.edu.cn [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Miao, Xiangshui [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

    2017-07-01

    Highlights: • We have predicted two NEW stable phases of atomic layer aluminum, buckled and 8-Pmmn aluminene. • We have revealed the electronic structures and bonding characteristics of aluminene. • Thermodynamic properties of aluminene were investigated based on phonon properties. - Abstract: Using first-principles calculations based on density functional theory (DFT), we have investigated the structure stability and electronic properties of both buckled and 8-Pmmn phase aluminene. Phonon dispersion analysis reveals that the buckled and 8-Pmmn aluminene are dynamically stable. The band structure shows that both the buckled and 8-Pmmn aluminene exhibit metallic behavior. Finally, the thermodynamic properties are investigated based on phonon properties.

  15. Relativistic effects on inner-shell electron properties

    International Nuclear Information System (INIS)

    Desclaux, J.P.

    1976-01-01

    The influence of relativistic effects on hydrogen-like systems is first reviewed. After having considered one-electron systems, the influence of the other electrons is to be taken into account when considering inner ionization energy and ionization cross sections. Two-hole states in inner shells being then dealt with, the problem of angular momentum coupling among electrons can no longer be neglected. In an other way, this implies that wave functions are to be built on a jj basis instead of a ls one. Ksub(α)sup(h) hypersatellite spectra and KLL Auger transition energies are successively discussed

  16. Elucidation and control of electronic properties related to organic semiconductors

    International Nuclear Information System (INIS)

    Yamane, Hiroyuki; Ueno, Nobuo; Seki, Kazuhiko

    2009-01-01

    The electronic structure of organic solids and interfaces plays a crucial role in the performance of optoelectronic devices using organic semiconductors such as light-emitting diodes, field-effect transistors, and photovoltaic cells. The functionality of these organic devices is seriously dominated by the geometric structure, which varies depending on the molecular structure and the sample preparation condition. Due to the rapid progress in sample preparation methods and surface science techniques, we can now discuss in detail the correlation of the electronic structure with the geometric structure of organic solids, films, and interfaces. This paper reviews the recent progress of studies in the geometric and electronic structures related to organic semiconductors. (author)

  17. Structural and electronic properties of ion-implanted superconductors

    International Nuclear Information System (INIS)

    Bernas, H.; Nedellec, P.

    1980-01-01

    Recent work on ion implanted superconductors is reviewed. In situ x-ray, channeling, resistivity, and electron tunneling experiments now approach the relation between lattice order (or disorder) and superconductivity

  18. Shape-dependent electronic properties of blue phosphorene nano-flakes

    Energy Technology Data Exchange (ETDEWEB)

    Bhatia, Pradeep; Swaroop, Ram; Kumar, Ashok, E-mail: ashok@cup.ac.in [Center for Physical Sciences, School of Basic and Applied Sciences, Central University of Punjab, Bathinda-151001 (India)

    2016-05-06

    In recent year’s considerable attention has been given to the first principles method for modifying and controlling electronic properties of nano-materials. We performed DFT-based calculations on the electronic properties of zigzag-edged nano-flakes of blue phosphorene with three possible shapes namely rectangular, triangular and hexagonal. We observed that HOMO-LUMO gap of zigzag phosphorene nano-flakes with different shapes is ∼2.9 eV with H-passivations and ∼0.7 – 1.2 eV in pristine cases. Electronic properties of blue phosphorene nano-flakes show the strong dependence on their shape. We observed that distributions of molecular orbitals were strongly affected by the different shapes. Zigzag edged considered nanostructures are non-magnetic and semiconducting in nature. The shape dependent electronic properties may find applications in tunable nano-electronics.

  19. Quasirelativism, narrowband properties and forced dynamics of electrons in solids

    CERN Document Server

    Pavlov, B S; Strepetov, A V

    2002-01-01

    The narrow-zone semiconductors, which are applied for creating the quantum networks, characterized by small effective masses of electrons at the Fermi level and consequently by high electron mobility in the lattice. The obviously soluble model, clarifying one of the possible mechanisms for the small effective masses origination, is constructed in the proposed work. The other mathematical model, constructed in this work, describes the possible mechanism for controlling the alternating quantum current by the one-dimensional lattice through a travelling wave

  20. Hydration effect on the electronic transport properties of oligomeric phenylene ethynylene molecular junctions

    International Nuclear Information System (INIS)

    Zong-Liang, Li; Huai-Zhi, Li; Yong, Ma; Guang-Ping, Zhang; Chuan-Kui, Wang

    2010-01-01

    A first-principles computational method based on the hybrid density functional theory is developed to simulate the electronic transport properties of oligomeric phenylene ethynylene molecular junctions with H 2 O molecules accumulated in the vicinity as recently reported by Na et al. [Nanotechnology 18 424001 (2007)]. The numerical results show that the hydrogen bonds between the oxygen atoms of the oligomeric phenylene ethynylene molecule and H 2 O molecules result in the localisation of the molecular orbitals and lead to the lower transition peaks. The H 2 O molecular chains accumulated in the vicinity of the molecular junction can not only change the electronic structure of the molecular junctions, but also open additional electronic transport pathways. The obvious influence of H 2 O molecules on the electronic structure of the molecular junction and its electronic transport properties is thus demonstrated. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  1. Enhanced Electronic Properties of SnO2 via Electron Transfer from Graphene Quantum Dots for Efficient Perovskite Solar Cells.

    Science.gov (United States)

    Xie, Jiangsheng; Huang, Kun; Yu, Xuegong; Yang, Zhengrui; Xiao, Ke; Qiang, Yaping; Zhu, Xiaodong; Xu, Lingbo; Wang, Peng; Cui, Can; Yang, Deren

    2017-09-26

    Tin dioxide (SnO 2 ) has been demonstrated as an effective electron-transporting layer (ETL) for attaining high-performance perovskite solar cells (PSCs). However, the numerous trap states in low-temperature solution processed SnO 2 will reduce the PSCs performance and result in serious hysteresis. Here, we report a strategy to improve the electronic properties in SnO 2 through a facile treatment of the films with adding a small amount of graphene quantum dots (GQDs). We demonstrate that the photogenerated electrons in GQDs can transfer to the conduction band of SnO 2 . The transferred electrons from the GQDs will effectively fill the electron traps as well as improve the conductivity of SnO 2 , which is beneficial for improving the electron extraction efficiency and reducing the recombination at the ETLs/perovskite interface. The device fabricated with SnO 2 :GQDs could reach an average power conversion efficiency (PCE) of 19.2 ± 1.0% and a highest steady-state PCE of 20.23% with very little hysteresis. Our study provides an effective way to enhance the performance of perovskite solar cells through improving the electronic properties of SnO 2 .

  2. Electronic properties of epitaxial 6H silicon carbide

    International Nuclear Information System (INIS)

    Wessels, B.W.; Gatos, H.C.

    1977-01-01

    The electrical conductivity and Hall coefficient were measured in the temperature range from 78 to 900 K for n-type epitaxially grown 6H silicon carbide. A many-valley model of the conduction band was used in the analysis of electron concentration as a function of temperature. From this analysis, the density of states mass to the free electron mass ratio per ellipsoid was calculated to be 0.45. It was estimated that the constant energy surface of the conduction band consists of three ellipsoids. The ionization energy of the shallowest nitrogen donor was found to be 105 meV, when the valley-orbit interaction was taken into account. The electron scattering mechanisms in the epitaxial layers were analyzed and it was shown that the dominant mechanism limiting electron mobility at high temperatures is inter-valley scattering and at low temperatures (200K), impurity and space charge scattering. A value of 360 cm 2 /V sec was calculated for the maximum room temperature Hall mobility expected for electrons in pure 6H SiC. The effect of epitaxial growth temperature on room temperature Hall mobility was also investigated. (author)

  3. Dynamical and electronic properties of rare-earth aluminides

    Science.gov (United States)

    Sharma, Ramesh; Sharma, Yamini

    2018-04-01

    Rare-earth dialuminides belong to a large family of compounds that stabilize in cubic MgCu2 structure. A large number of these compounds are superconducting, amongst these YAl2, LaAl2 and LuAl2 have been chosen as reference materials for studying 4f-electron systems. In order to understand the role of the RE atoms, we have applied the FPLAPW and PAW methods within the density functional theory (DFT). Our results show that the contribution of RE atoms is dominant in both electronic structure and phonon dispersion. The anomalous behavior of superconducting LaAl2 is well explained from an analysis of the electron localization function (ELF), Bader charge analysis, density of electronic states as well as the dynamical phonon vibrational modes. The interaction of phonon modes contributed by low frequency vibrations of La atoms with the high density La 5d-states at EF in LaAl2 lead to strong electron-phonon coupling.

  4. Electronic properties of single-molecule junction: Effect of the molecular distortion

    International Nuclear Information System (INIS)

    Gao, W.; Zhao, M.; Jiang, Q.

    2009-01-01

    For a model system consisting of a benzenedithio (BDT) molecule sandwiched between two Au plates, the electronic properties as a function of different BDT geometry are investigated using density functional theory. The distorted BDT structures are got through stretching the electrode distance. The corresponding electronic properties, including the spatial distribution of the frontier orbits, the gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital levels and density of states at the Fermi energy are determined. It reveals that the molecular distortion essentially determines electronic structures. The result should be beneficial to understand the stress-dependent or structure-dependent transport mechanism of electrons of the BDT junction.

  5. High seeding density of human chondrocytes in agarose produces tissue-engineered cartilage approaching native mechanical and biochemical properties.

    Science.gov (United States)

    Cigan, Alexander D; Roach, Brendan L; Nims, Robert J; Tan, Andrea R; Albro, Michael B; Stoker, Aaron M; Cook, James L; Vunjak-Novakovic, Gordana; Hung, Clark T; Ateshian, Gerard A

    2016-06-14

    Animal cells have served as highly controllable model systems for furthering cartilage tissue engineering practices in pursuit of treating osteoarthritis. Although successful strategies for animal cells must ultimately be adapted to human cells to be clinically relevant, human chondrocytes are rarely employed in such studies. In this study, we evaluated the applicability of culture techniques established for juvenile bovine and adult canine chondrocytes to human chondrocytes obtained from fresh or expired osteochondral allografts. Human chondrocytes were expanded and encapsulated in 2% agarose scaffolds measuring ∅3-4mm×2.3mm, with cell seeding densities ranging from 15 to 90×10(6)cells/mL. Subsets of constructs were subjected to transient or sustained TGF-β treatment, or provided channels to enhance nutrient transport. Human cartilaginous constructs physically resembled native human cartilage, and reached compressive Young's moduli of up to ~250kPa (corresponding to the low end of ranges reported for native knee cartilage), dynamic moduli of ~950kPa (0.01Hz), and contained 5.7% wet weight (%/ww) of glycosaminoglycans (≥ native levels) and 1.5%/ww collagen. We found that the initial seeding density had pronounced effects on tissue outcomes, with high cell seeding densities significantly increasing nearly all measured properties. Transient TGF-β treatment was ineffective for adult human cells, and tissue construct properties plateaued or declined beyond 28 days of culture. Finally, nutrient channels improved construct mechanical properties, presumably due to enhanced rates of mass transport. These results demonstrate that our previously established culture system can be successfully translated to human chondrocytes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. BIOTECHNOLOGICAL APPROACHES FOR CONSERVATION OF THE ENDANGERED SPECIES Crambe koktebelica (JUNGE N. BUSCH AND EFFECT OF ASEPTIC IN VITRO CULTIVATION ON ITS BIOCHEMICAL PROPERTIES

    Directory of Open Access Journals (Sweden)

    Pushkarova

    2016-08-01

    Full Text Available The aim of the study was to establish efficient protocols of seed surface sterilization with further multiplication in vitro for threatened species Crambe koktebelica (Junge N. Busch and to show the effect of biotechnological approach (in vitro cultivation of biodiversity conservation on plants biochemical properties. Seed surface sterilization was carried out according to the original method with further microclonal multiplication of aseptic sprouts from lateral buds on the Murashige and Skoog (MS medium supplemented with different concentrations of growth regulators. Fatty acid content was determined using Gas chromatography-mass spectrophotometry of fatty acid ethers. Antioxidant activity was determined using 2.2-diphenyl-1-picrylhydrazyl radical scavenging method. Total soluble protein content was measured using Bradford method and polyfructan content determination was based upon ketosugars ability to color in the acidic environment with resorcinol. Plants that were grown under in vitro and in vivo conditions and seeds were used in this research. Efficient protocol of surface sterilization that resulted in 45% of aseptic seed material 50% of which has sprouted was elaborated for C. koktebelica as well as fast microclonal multiplication methods that provided with up to 5.25 ± 0.50 new formed plantlets from 1 lateral bud (on the MS medium that contained 1 mg/L of 6-benzylaminopurine. It was also shown that aseptic cultivation benefits to saturated fatty acid accumulation and increases protein content but on the other hand it reduces unsaturated fatty acid amount and polyfructan content as well as antioxidant activity of plant material. Obtained data confirms the prospect of biotechnology approach to biodiversity conservation and suggest the necessity of father in vitro cultivation effect on biochemical composition of plant study.

  7. Electronic and gas sensing properties of soluble phthalocyanines

    Czech Academy of Sciences Publication Activity Database

    Pochekaylov, Sergey; Rais, David; Nešpůrek, Stanislav; Rakušan, J.; Karásková, M.

    2009-01-01

    Roč. 27, č. 3 (2009), s. 781-795 ISSN 0137-1339. [International Conference on Electtrical and Related Properties of Organic Solids /11./. Wroclaw, 13.07.2008-17.07.2008] R&D Projects: GA AV ČR KAN400720701 Institutional research plan: CEZ:AV0Z40500505 Keywords : substituted phthalocyanine * nitrogen dioxide sensor * optical properties Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.384, year: 2009

  8. Electronic structure and physical properties of 13C carbon composite

    OpenAIRE

    Zhmurikov, Evgenij

    2015-01-01

    This review is devoted to the application of graphite and graphite composites in science and technology. Structure and electrical properties, as so technological aspects of producing of high-strength artificial graphite and dynamics of its destruction are considered. These type of graphite are traditionally used in the nuclear industry. Author was focused on the properties of graphite composites based on carbon isotope 13C. Generally, the review relies on the original results and concentrates...

  9. Shape dependent electronic properties of wurzite GaN nanowire

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Pankaj, E-mail: pankajs@iiitm.ac.in; Kumar, Avaneesh, E-mail: avaneeshk7@ymail.com; Sharma, Varun, E-mail: sunny2013@gmail.com [Nanomaterials Research Group, ABV-Indian Institute of Information Technology and Management (IIITM), Gwalior-474015 (India); Jaiswal, Neeraj K., E-mail: neerajkumar.phd@gmail.com [Discipline of Physics, PDPM-Indian Institute of Information Technology, Design and Manufacturing (IIITDM), Jabalpur-482005 (India)

    2016-05-06

    In the present work, energetic stability and electronic behavior of triangular and square shaped wurzite GaN NW oriented along [1100] and [11 2 0] direction has been investigated by employing ab-initio DFT calculation. Structural analysis suggests that triangular shaped NW undergoes strong surface reconstruction compared to square shaped NW. However, binding energy reveals that square shaped NW is energetically more feasible than triangular NW. Further, from electronic band structure we observe that both structures are metallic with higher metallicity for triangular shaped NW.

  10. Biochemical characterization of Helichrysum italicum (Roth) G.Don subsp. italicum (Asteraceae) from Montenegro: phytochemical screening, chemotaxonomy, and antioxidant properties.

    Science.gov (United States)

    Kladar, Nebojša V; Anačkov, Goran T; Rat, Milica M; Srđenović, Branislava U; Grujić, Nevena N; Šefer, Emilia I; Božin, Biljana N

    2015-03-01

    The chemical composition and antioxidant properties of the essential oil and EtOH extract of immortelle (Helichrysum italicum (Roth) G.Don subsp. italicum, Asteraceae) collected in Montenegro were evaluated. The essential oil was characterized by GC/MS analysis, and the content of total phenolics and flavonoids in the EtOH extract was determined using the FolinCiocalteu reagent. The free-radical-scavenging capacity (RSC) of both the essential oil and the EtOH extract was assessed with the 2,2-diphenyl-1-pycrylhydrazyl (DPPH) method. Moreover, the inhibition of hydroxyl radical ((.) OH) generation by the EtOH extract of immortelle was evaluated for the first time here. Neryl acetate (28.2%) and γ-curcumene (18.8%) were the main compounds in the essential oil, followed by neryl propionate (9.1%) and ar-curcumene (8.3%). The chemical composition of the oils of the examined and additional 16 selected Helichrysum italicum taxa described in literature were compared using principal component (PCA) and cluster (CA) analyses. The results of the statistical analyses implied the occurrence of at least four different main and three subchemotypes of essential oils. Considering the antioxidant properties, the EtOH extract of immortelle exhibited similar potential as propyl gallate and quercetin, while the essential oil exhibited relatively weak DPPH(.) -scavenging capacity. Copyright © 2015 Verlag Helvetica Chimica Acta AG, Zürich.

  11. Study of the effects of ionizing radiation on the biochemical and biological properties of garlic (Allium sativum)

    International Nuclear Information System (INIS)

    Meddeb, Wiem

    2008-01-01

    Garlic is used since sevral hundred years to deal with various health issues. During last decades sevral works was interested to specify these problems, in this work we studied the effects of the gamma irradiation on the physico-chemical and biological properties of Allium sativum. This study was undertaken on the bulb irradiated by implying amounts of differents irradiation from 140 to 260Gy. First we proceeded to analyse the effects of these irradiations on the composition of garlic such as : allicin, protein, reducing sugars, total sugars, triglycerides and polyphenols. Second we tested the effect of these extracts radiotreated on the cell multiplication and the enzymatic activity of salmonella Hadar. The obtained results showed that the irradiated garlic extracts, present a slight nonsignificant reduction in the allicine proteinn sugar reducers, triglyceride and polyphenols concentration. However, this reduction is significant during application of the amount 260Ky. In addition, a deterioration of the growth observed after treatment by different concentrations of aqueous irradiated garlic extract. This inhibition is dependent on the concentration of aqueous extract of garlic used and the used irradiation dose. These observations would be in favor that the irradiations induce a slight midification of physico-chemical properties and they affect the anbacterial activity against salmonella Hdar. (Author)

  12. Fcγ1 fragment of IgG1 as a powerful affinity tag in recombinant Fc-fusion proteins: immunological, biochemical and therapeutic properties.

    Science.gov (United States)

    Soleimanpour, Saman; Hassannia, Tahereh; Motiee, Mahdieh; Amini, Abbas Ali; Rezaee, S A R

    2017-05-01

    Affinity tags are vital tools for the production of high-throughput recombinant proteins. Several affinity tags, such as the hexahistidine tag, maltose-binding protein, streptavidin-binding peptide tag, calmodulin-binding peptide, c-Myc tag, glutathione S-transferase and FLAG tag, have been introduced for recombinant protein production. The fragment crystallizable (Fc) domain of the IgG1 antibody is one of the useful affinity tags that can facilitate detection, purification and localization of proteins and can improve the immunogenicity, modulatory effects, physicochemical and pharmaceutical properties of proteins. Fcγ recombinant forms a group of recombinant proteins called Fc-fusion proteins (FFPs). FFPs are widely used in drug discovery, drug delivery, vaccine design and experimental research on receptor-ligand interactions. These fusion proteins have become successful alternatives to monoclonal antibodies for drug developments. In this review, the physicochemical, biochemical, immunological, pharmaceutical and therapeutic properties of recombinant FFPs were discussed as a new generation of bioengineering strategies.

  13. Ab-initio investigations of the electronic properties of bulk wurtzite Beryllia and its derived nanofilms

    International Nuclear Information System (INIS)

    Goumri-Said, Souraya; Kanoun, Mohammed Benali

    2010-01-01

    In this Letter we investigate the electronic properties of the bulk and the nanofilm BeO in wurtzite structure. We performed a first-principles pseudo-potential method within the generalized gradient approximation. We will give more importance to the changes in band structure and density of states between the bulk structure and its derived nanofilms. The bonding characterization will be investigated via the analysis Mulliken population and charge density contours. It is found that the nanofilm retains the same properties as its bulk structure with slight changes in electronic properties and band structure which may offer some unusual transport properties.

  14. Investigation of the electronic, magnetic and optical properties of newest carbon allotrope

    Science.gov (United States)

    Kazemi, Samira; Moradian, Rostam

    2018-05-01

    We investigate triple properties of monolayer pentagon graphene that include electronic, magnetic and optical properties based on density functional theory (DFT). Our results show that in the electronic and magnetic properties this structure with a direct energy gap of about 2.2 eV along Γ - Γ direction and total magnetic moment of 0.0013 μB per unit cell is almost a non-magnetic semiconductor. Also, its optical properties show that if this allotrope used in solar cell technology, its efficiency in the low energy will be better, because, in the range of energy, its loss energy function and reflectivity will be minimum.

  15. Ab-initio investigations of the electronic properties of bulk wurtzite Beryllia and its derived nanofilms

    KAUST Repository

    Goumri-Said, Souraya

    2010-08-01

    In this Letter we investigate the electronic properties of the bulk and the nanofilm BeO in wurtzite structure. We performed a first-principles pseudo-potential method within the generalized gradient approximation. We will give more importance to the changes in band structure and density of states between the bulk structure and its derived nanofilms. The bonding characterization will be investigated via the analysis Mulliken population and charge density contours. It is found that the nanofilm retains the same properties as its bulk structure with slight changes in electronic properties and band structure which may offer some unusual transport properties. © 2010 Elsevier B.V. All rights reserved.

  16. Molecular fingerprints in the electronic properties of crystalline organic semiconductors

    DEFF Research Database (Denmark)

    Ciuchi, S.; Hatch, R.C.; Höchst, H.

    2012-01-01

    bands can be achieved in organic semiconductors provided that one properly accounts for the coupling to molecular vibrational modes and the presence of disorder. Our findings rationalize the growing experimental evidence that even the best band structure theories based on a many-body treatment...... of electronic interactions cannot reproduce the experimental photoemission data in this important class of materials....

  17. Properties of the scattering amplitude for electron-atom collisions

    International Nuclear Information System (INIS)

    Combes, J.M.; Tip, A.

    1983-02-01

    For the scattering of an electron by an atom finiteness of the amplitude at non threshold energies is proved in the framework of the N-body Schroedinger equation. It is also shown that both the direct and exchange amplitudes have analytic continuations for complex values of incident momentum, with pole or cut singularities on the imaginary axis

  18. Electronic and chemical properties of graphene-based structures:

    DEFF Research Database (Denmark)

    Vanin, Marco

    In the present thesis several aspects of graphene-based structures have been investigated using density functional theory calculations to solve the electronic structure problem. A review of the implementation of a localized basis-set within the projector augmented wave method - the way of describ...... are attractive candidates although issues regarding the poisoning of the active site remain to be addressed....

  19. Electronic structure and equilibrium properties of hcp titanium and ...

    Indian Academy of Sciences (India)

    -d) and zirco- nium (4-d) transition metals are studied by using a non-local model potential method. From the present calculation of energy bands, Fermi energy, density of states and the electronic heat capacity of these two metals are ...

  20. Electronic structure and mechanical properties of plasma nitrided ferrous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Portolan, E. [Centro de Ciencias Exatas e Tecnologia, Universidade de Caxias do Sul, 95070-560 Caxias do Sul-RS (Brazil); Baumvol, I.J.R. [Centro de Ciencias Exatas e Tecnologia, Universidade de Caxias do Sul, 95070-560 Caxias do Sul-RS (Brazil); Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Porto Alegre 91509-970 (Brazil); Figueroa, C.A., E-mail: cafiguer@ucs.br [Centro de Ciencias Exatas e Tecnologia, Universidade de Caxias do Sul, 95070-560 Caxias do Sul-RS (Brazil)

    2009-04-15

    The electronic structures of the near-surface regions of two different nitrided steels (AISI 316 and 4140) were investigated using X-ray photoelectron spectroscopy. Photoelectron groups from all main chemical elements involved were addressed for steel samples with implanted-N concentrations in the range 16-32 at.%. As the implanted-N concentrations were increased, rather contrasting behaviors were observed for the two kinds of steel. The N1s photoelectrons had spectral shifts toward lower (nitrided AISI 316) or higher (nitrided AISI 4140) binding energies, whereas the Fe2p{sub 3/2} photoelectron spectrum remains at a constant binding energy (nitrided AISI 316) or shifts toward higher binding energies (AISI 4140). These trends are discussed in terms of the metallic nitride formation and the overlapping of atomic orbitals. For nitrided AISI 316, a semi-classical approach of charge transfer between Cr and N is used to explain the experimental facts (formation of CrN), while for nitrided AISI 4140 we propose that the interaction between orbitals 4s from Fe and 2p from N promotes electrons to the conduction band increasing the electrical attraction of the N1s and Fe2p electrons in core shells (formation of FeN{sub x}). The increase in hardness of the steel upon N implantation is attributed to the localization of electrons in specific bonds, which diminishes the metallic bond character.

  1. Electronic structure and mechanical properties of plasma nitrided ferrous alloys

    Science.gov (United States)

    Portolan, E.; Baumvol, I. J. R.; Figueroa, C. A.

    2009-04-01

    The electronic structures of the near-surface regions of two different nitrided steels (AISI 316 and 4140) were investigated using X-ray photoelectron spectroscopy. Photoelectron groups from all main chemical elements involved were addressed for steel samples with implanted-N concentrations in the range 16-32 at.%. As the implanted-N concentrations were increased, rather contrasting behaviors were observed for the two kinds of steel. The N1s photoelectrons had spectral shifts toward lower (nitrided AISI 316) or higher (nitrided AISI 4140) binding energies, whereas the Fe2p 3/2 photoelectron spectrum remains at a constant binding energy (nitrided AISI 316) or shifts toward higher binding energies (AISI 4140). These trends are discussed in terms of the metallic nitride formation and the overlapping of atomic orbitals. For nitrided AISI 316, a semi-classical approach of charge transfer between Cr and N is used to explain the experimental facts (formation of CrN), while for nitrided AISI 4140 we propose that the interaction between orbitals 4s from Fe and 2p from N promotes electrons to the conduction band increasing the electrical attraction of the N1s and Fe2p electrons in core shells (formation of FeN x). The increase in hardness of the steel upon N implantation is attributed to the localization of electrons in specific bonds, which diminishes the metallic bond character.

  2. Electronic structure and mechanical properties of plasma nitrided ferrous alloys

    International Nuclear Information System (INIS)

    Portolan, E.; Baumvol, I.J.R.; Figueroa, C.A.

    2009-01-01

    The electronic structures of the near-surface regions of two different nitrided steels (AISI 316 and 4140) were investigated using X-ray photoelectron spectroscopy. Photoelectron groups from all main chemical elements involved were addressed for steel samples with implanted-N concentrations in the range 16-32 at.%. As the implanted-N concentrations were increased, rather contrasting behaviors were observed for the two kinds of steel. The N1s photoelectrons had spectral shifts toward lower (nitrided AISI 316) or higher (nitrided AISI 4140) binding energies, whereas the Fe2p 3/2 photoelectron spectrum remains at a constant binding energy (nitrided AISI 316) or shifts toward higher binding energies (AISI 4140). These trends are discussed in terms of the metallic nitride formation and the overlapping of atomic orbitals. For nitrided AISI 316, a semi-classical approach of charge transfer between Cr and N is used to explain the experimental facts (formation of CrN), while for nitrided AISI 4140 we propose that the interaction between orbitals 4s from Fe and 2p from N promotes electrons to the conduction band increasing the electrical attraction of the N1s and Fe2p electrons in core shells (formation of FeN x ). The increase in hardness of the steel upon N implantation is attributed to the localization of electrons in specific bonds, which diminishes the metallic bond character.

  3. Noncovalent Intermolecular Interactions in Organic Electronic Materials: Implications for the Molecular Packing vs Electronic Properties of Acenes

    KAUST Repository

    Sutton, Christopher

    2015-10-30

    Noncovalent intermolecular interactions, which can be tuned through the toolbox of synthetic chemistry, determine not only the molecular packing but also the resulting electronic, optical, and mechanical properties of materials derived from π-conjugated molecules, oligomers, and polymers. Here, we provide an overview of the theoretical underpinnings of noncovalent intermolecular interactions and briefly discuss the computational chemistry approaches used to understand the magnitude of these interactions. These methodologies are then exploited to illustrate how noncovalent intermolecular interactions impact important electronic properties-such as the electronic coupling between adjacent molecules, a key parameter for charge-carrier transport-through a comparison between the prototype organic semiconductor pentacene with a series of N-substituted heteropentacenes. Incorporating an understanding of these interactions into the design of organic semiconductors can assist in developing novel materials systems from this fascinating molecular class. © 2015 American Chemical Society.

  4. Effects of Shock and Turbulence Properties on Electron Acceleration

    Science.gov (United States)

    Qin, G.; Kong, F.-J.; Zhang, L.-H.

    2018-06-01

    Using test particle simulations, we study electron acceleration at collisionless shocks with a two-component model turbulent magnetic field with slab component including dissipation range. We investigate the importance of the shock-normal angle θ Bn, magnetic turbulence level {(b/{B}0)}2, and shock thickness on the acceleration efficiency of electrons. It is shown that at perpendicular shocks the electron acceleration efficiency is enhanced with the decrease of {(b/{B}0)}2, and at {(b/{B}0)}2=0.01 the acceleration becomes significant due to a strong drift electric field with long time particles staying near the shock front for shock drift acceleration (SDA). In addition, at parallel shocks the electron acceleration efficiency is increasing with the increase of {(b/{B}0)}2, and at {(b/{B}0)}2=10.0 the acceleration is very strong due to sufficient pitch-angle scattering for first-order Fermi acceleration, as well as due to the large local component of the magnetic field perpendicular to the shock-normal angle for SDA. On the other hand, the high perpendicular shock acceleration with {(b/{B}0)}2=0.01 is stronger than the high parallel shock acceleration with {(b/{B}0)}2=10.0, the reason might be the assumption that SDA is more efficient than first-order Fermi acceleration. Furthermore, for oblique shocks, the acceleration efficiency is small no matter whether the turbulence level is low or high. Moreover, for the effect of shock thickness on electron acceleration at perpendicular shocks, we show that there exists the bendover thickness, L diff,b. The acceleration efficiency does not noticeably change if the shock thickness is much smaller than L diff,b. However, if the shock thickness is much larger than L diff,b, the acceleration efficiency starts to drop abruptly.

  5. Super heavy element Copernicium: Cohesive and electronic properties revisited

    Science.gov (United States)

    Gyanchandani, Jyoti; Mishra, Vinayak; Dey, G. K.; Sikka, S. K.

    2018-01-01

    First principles scalar relativistic (SR) calculations with and without including the spin orbit (SO) interactions have been performed for solid Copernicium (Cn) to determine its ground state equilibrium structure, volume, bulk modulus, pressure derivative of the bulk modulus, density of states and band structure. Both SR and SR+SO calculations have been performed with 6p levels treated as part of core electrons and also as part of valence electrons. These calculations have been performed for the rhombohedral, BCT, FCC, HCP, BCC and SC structures. Results have been compared with the results for Hg which is lighter homologue of Cn in the periodic table. We find hcp to be the stable crystal structure at SR level of theory and also at SR+SO level of theory when the 6p electrons are treated as part of core electrons. With 6p as part of valence electrons, SR+SO level of computations, however, yield bcc structure to be the most stable structure. Equilibrium volume (V0) of the most stable crystal structure at SR level of theory viz. hcp structure is 188.66 a.u.3whereas its value for the bcc structure, the equilibrium ground state structure at SR+SO level of theory is 165.71 a.u.3 i.e a large change due to relativistic effects is seen. The density of states at Fermi level is much smaller in Cn than in Hg, making it a poorer metal than mercury. In addition the cohesive energy of Cn is computed to be almost two times that of Hg for SR+SO case.

  6. Innovation and development of exhibition electronic-commerce based on the properties of electronic-commerce

    Science.gov (United States)

    Zhang, Jiankang

    2017-06-01

    There are two roadmaps of accomplishing exhibition electronic-commerce innovation and development. The first roadmap is that the exhibition organizers should seek mutual benefit cooperation with professional electronic-commerce platform of correspondent area with exhibition projects, thus help exhibitors realize their market object. The second roadmap is to promote innovation and development of electronic-commerce (Business-to-Customer) between both exhibitors and purchasers. Exhibition electronic-commerce must focus on innovative development in the following functions: market research and information service; advertising and business negotiation; online trading and online payment. With the aid of electronic-commerce, exhibition enterprise could have distinctive strengths such as transactions with virtualization, transparency, high efficiency and low cost, enhancing market link during enterprise research and development, promoting the efficiency of internal team collaboration and the individuation of external service, and optimizing resource allocation.

  7. Silicon-germanium (Sige) nanostructures production, properties and applications in electronics

    CERN Document Server

    Usami, N

    2011-01-01

    Nanostructured silicon-germanium (SiGe) provides the prospect of novel and enhanced electronic device performance. This book reviews the materials science and technology of SiGe nanostructures, including crystal growth, fabrication of nanostructures, material properties and applications in electronics.$bNanostructured silicon-germanium (SiGe) opens up the prospects of novel and enhanced electronic device performance, especially for semiconductor devices. Silicon-germanium (SiGe) nanostructures reviews the materials science of nanostructures and their properties and applications in different electronic devices. The introductory part one covers the structural properties of SiGe nanostructures, with a further chapter discussing electronic band structures of SiGe alloys. Part two concentrates on the formation of SiGe nanostructures, with chapters on different methods of crystal growth such as molecular beam epitaxy and chemical vapour deposition. This part also includes chapters covering strain engineering and mo...

  8. Electron transport properties in InAs four-terminal ballistic junctions under weak magnetic fields

    International Nuclear Information System (INIS)

    Koyama, M.; Fujiwara, K.; Amano, N.; Maemoto, T.; Sasa, S.; Inoue, M.

    2009-01-01

    We report on the electron transport properties based on ballistic electrons under magnetic fields in four-terminal ballistic junctions fabricated on an InAs/AlGaSb heterostructure. The four-terminal junction structure is composed of two longitudinal stems with two narrow wires slanted with 30 degree from the perpendicular axis. The electron focusing peak was obtained with the bend resistance measurement. Then it was investigated the nonlinear electron transport property of potential difference between longitudinal stems due to ballistic electrons with applying direct current from narrow wires. Observed nonlinearity showed clear rectification effects which have negative polarity regardless of input voltage polarity. Although this nonlinearity was qualitatively changed due to the Lorentz force under magnetic fields, the degradation of ballistic effects on nonlinear properties were observed when the current increased to higher strength. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Electronic properties of diphenyl-s-tetrazine and some related oligomers. An spectroscopic and theoretical study

    Science.gov (United States)

    Moral, Mónica; García, Gregorio; Peñas, Antonio; Garzón, Andrés; Granadino-Roldán, José M.; Melguizo, Manuel; Fernández-Gómez, Manuel

    2012-10-01

    This work presents a theoretical and spectroscopic study on the electronic and structural properties of the diphenyl-s-tetrazine molecule (Ph2Tz) and some oligomeric derivatives. Ph2Tz was synthesized through a variation of Pinner-type reaction which uses N-acetylcysteine as catalyst. Insight into the structure and electronic properties of the title compound was obtained through IR, Raman, UV-Vis spectra in different solvents, and theoretical calculations. Theoretical studies have been extended to different n-mers derivatives up to an ideal molecular wire through the oligomeric approximation, predicting this way electronic properties such as LUMO energy levels, electron affinity and reorganization energy in order to assess their possible applications in molecular electronics.

  10. First principles study of electronic, elastic and thermal properties of lutetium intermetallics

    International Nuclear Information System (INIS)

    Pagare, Gitanjali; Chouhan, Sunil Singh; Soni, Pooja; Sanyal, S.P.; Rajagopalan, M.

    2011-01-01

    In the present work, the electronic, elastic and thermal properties of lutetium intermetallics LuX have been studied theoretically by using first principles calculations based on density functional theory (DFT) with the generalized gradient approximation (GCA)

  11. Proton disorder in cubic ice: Effect on the electronic and optical properties

    International Nuclear Information System (INIS)

    Garbuio, Viviana; Pulci, Olivia; Cascella, Michele; Kupchak, Igor; Seitsonen, Ari Paavo

    2015-01-01

    The proton disorder in ice has a key role in several properties such as the growth mode, thermodynamical properties, and ferroelectricity. While structural phase transitions from proton disordered to proton ordered ices have been extensively studied, much less is known about their electronic and optical properties. Here, we present ab initio many body perturbation theory-based calculations of the electronic and optical properties of cubic ice at different levels of proton disorder. We compare our results with those from liquid water, that acts as an example of a fully (proton- and oxygen-)disordered system. We find that by increasing the proton disorder, a shrinking of the electronic gap occurs in ice, and it is smallest in the liquid water. Simultaneously, the excitonic binding energy decreases, so that the final optical gaps result to be almost independent on the degree of proton disorder. We explain these findings as an interplay between the local dipolar disorder and the electronic correlation

  12. Structural, Electronic, Magnetic, and Vibrational Properties of Graphene and Silicene: A First-Principles Perspective

    KAUST Repository

    Kaloni, Thaneshwor P.

    2013-01-01

    This thesis covers the structural, electronic, magnetic, and vibrational properties of graphene and silicene. In Chapter I, we will start with an introduction to graphene and silicene. In Chapter II, we will briefly discuss about the methodology (i

  13. Ab-initio investigations of the electronic properties of bulk wurtzite Beryllia and its derived nanofilms

    KAUST Repository

    Goumri-Said, Souraya; Kanoun, Mohammed

    2010-01-01

    In this Letter we investigate the electronic properties of the bulk and the nanofilm BeO in wurtzite structure. We performed a first-principles pseudo-potential method within the generalized gradient approximation. We will give more importance

  14. Surface electronic and structural properties of nanostructured titanium oxide grown by pulsed laser deposition

    NARCIS (Netherlands)

    Fusi, M.; Maccallini, E.; Caruso, T.; Casari, C. S.; Bassi, A. Li; Bottani, C. E.; Rudolf, P.; Prince, K. C.; Agostino, R. G.

    Titanium oxide nanostructured thin films synthesized by pulsed laser deposition (PLD) were here characterized with a multi-technique approach to investigate the relation between surface electronic, structural and morphological properties. Depending on the growth parameters, these films present

  15. Structural and optical properties of electron beam evaporated CdSe ...

    Indian Academy of Sciences (India)

    electronic applications such as photo detection or solar energy conversion, due to its optical and electrical properties, as well as its good chemical and mechanical stability. In order to explore the possibility of using this in optoelectronics, ...

  16. Relativistic properties of spherical diodes with a radial electron flux

    International Nuclear Information System (INIS)

    Chetvertkov, V.I.

    1987-01-01

    Forward and backward electron diodes with concentric spherical electrodes (inner cathode, outer anode or vice versa) are considered under the assumption that the emission is limited by the space charge and the guiding magnetic field is predominantly radial within a region of solid angle α f < 4π bounding the electron flux. The Poisson equations for the relativistic factor γ are solved for generalized model dependences. Ultrarelativistic and new nonrelativistic solutions are found, and analytic approximations to the solution near the cathode are used to carry out numerical calculations. The characteristics of forward and backward diodes turn out to be related to the exact solutions for a planar diode. Accurate approximations are found for calculating the diode parameters in a wide range of voltages; they can also be used to check the validity of the 3/2 laws and the ultrarelativistic solutions

  17. Temperature dependence of electronic transport property in ferroelectric polymer films

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, X.L.; Wang, J.L., E-mail: jlwang@mail.sitp.ac.cn; Tian, B.B.; Liu, B.L.; Zou, Y.H.; Wang, X.D.; Sun, S.; Sun, J.L., E-mail: jlsun@mail.sitp.ac.cn; Meng, X.J.; Chu, J.H.

    2014-10-15

    Highlights: • The ferroelectric polymer was fabricated by Langmuir–Blodgett method. • The electrons as the dominant injected carrier were conformed in the ferroelectric polymer films. • The leakage current conduction mechanisms in ferroelectric polymer were investigated. - Abstract: The leakage current mechanism of ferroelectric copolymer of polyvinylidene fluoride with trifluoroethylene prepared by Langmuir–Blodgett was investigated in the temperature range from 100 K to 350 K. The electron as the dominant injected carrier was observed in the ferroelectric copolymer films. The transport mechanisms in copolymer strongly depend on the temperature and applied voltage. From 100 K to 200 K, Schottky emission dominates the conduction. With temperature increasing, the Frenkel–Poole emission instead of the Schottky emission to conduct the carrier transport. When the temperature gets to 260 K, the leakage current becomes independent of temperature, and the space charge limited current conduction was observed.

  18. Echo 7: Magnetospheric properties determined by artificial electron beams

    International Nuclear Information System (INIS)

    Nemzek, R.J.

    1990-01-01

    The sounding rocket Echo 7 was launched from the Poker Flat Research Range. An on-board accelerator injected high-power electron beams into the magnetospheric tail near L = 6.5. After mirroring at the southern conjugate point, about 20 percent of the initial beam electrons returned to the North as Conjugate Echoes, where detectors (scintillators and spectrometers) on four subpayloads measured their energy and bounce time. The other 80 percent of the beam was pitch angle diffused by wave near the equatorial plane either into the conjugate atmosphere or up to mirror points above the payload. Comparison of measured values to calculations showed that the actual magnetosphere during the flight was well-described by the Tsyganenko-Usmanov model magnetosphere with a Kp value of 2- or 2+. Analysis of echo energies yielded values for the highly variable magnetospheric convection electric field

  19. Protonated serotonin: Geometry, electronic structures and photophysical properties

    Science.gov (United States)

    Omidyan, Reza; Amanollahi, Zohreh; Azimi, Gholamhassan

    2017-07-01

    The geometry and electronic structures of protonated serotonin have been investigated by the aim of MP2 and CC2 methods. The relative stabilities, transition energies and geometry of sixteen different protonated isomers of serotonin have been presented. It has been predicted that protonation does not exhibit essential alteration on the S1 ← S0 electronic transition energy of serotonin. Instead, more complicated photophysical nature in respect to its neutral analogue is suggested for protonated system owing to radiative and non-radiative deactivation pathways. In addition to hydrogen detachment (HD), hydrogen/proton transfer (H/PT) processes from ammonium to indole ring along the NH+⋯ π hydrogen bond have been predicted as the most important photophysical consequences of SERH+ at S1 excited state. The PT processes is suggested to be responsible for fluorescence of SERH+ while the HD driving coordinate is proposed for elucidation of its nonradiative deactivation mechanism.

  20. Allenylidene Complexes of Ruthenium: Synthesis, Spectroscopy and Electron Transfer Properties

    Czech Academy of Sciences Publication Activity Database

    Winter, R. F.; Záliš, Stanislav

    2004-01-01

    Roč. 248, 15/16 (2004), s. 1565-1583 ISSN 0010-8545 R&D Projects: GA ČR GA203/03/0821; GA MŠk OC D14.20 Institutional research plan: CEZ:AV0Z4040901 Keywords : spectroscopy * allenylidine complexes of ruthenium * electron transfer Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 6.446, year: 2004

  1. Magnetic properties of metallic impurities with strongly correlated electrons

    Czech Academy of Sciences Publication Activity Database

    Janiš, Václav; Ringel, Matouš

    2009-01-01

    Roč. 115, č. 1 (2009), s. 30-35 ISSN 0587-4246 R&D Projects: GA ČR GA202/07/0644 Institutional research plan: CEZ:AV0Z10100520 Keywords : And erson impurity * strong electron correlations * spin-polarized solution * three-channel parquet equations * magnetic field Subject RIV: BE - Theoretical Physics Impact factor: 0.433, year: 2009 http://przyrbwn.icm.edu.pl/APP/ABSTR/115/a115-1-5.html

  2. Schizosaccharomyces pombe Rad22A and Rad22B have similar biochemical properties and form multimeric structures

    Energy Technology Data Exchange (ETDEWEB)

    Vries, Femke A.T. de [Department of Toxicogenetics, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden (Netherlands); Zonneveld, Jose B.M. [Department of Toxicogenetics, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden (Netherlands); Groot, Anton J. de [Department of Toxicogenetics, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden (Netherlands); Koning, Roman I. [Department of Molecular Cell Biology, Leiden University Medical Center, Leiden (Netherlands); Zeeland, Albert A. van [Department of Toxicogenetics, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden (Netherlands); Pastink, Albert [Department of Toxicogenetics, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden (Netherlands)]. E-mail: A.Pastink@lumc.nl

    2007-02-03

    The Saccharomyces cerevisiae Rad52 protein has a crucial role in the repair of DNA double-strand breaks by homologous recombination. In vitro, Rad52 displays DNA binding and strand annealing activities and promotes Rad51-mediated strand exchange. Schizosaccharomyces pombe has two Rad52 homologues, Rad22A and Rad22B. Whereas rad22A deficient strains exhibit severe defects in repair and recombination, rad22B mutants have a much less severe phenotype. To better understand the role of Rad22A and Rad22B in double-strand break repair, both proteins were purified to near homogeneity. Using gel retardation and filter binding assays, binding of Rad22A and Rad22B to short single-stranded DNAs was demonstrated. Binding of Rad22A to double-stranded oligonucleotides or linearized plasmid molecules containing blunt ends or short single-stranded overhangs could not be detected. Rad22B also does not bind efficiently to short duplex oligonucleotides but binds readily to DNA fragments containing 3'-overhangs. Rad22A as well as Rad22B efficiently promote annealing of complementary single-stranded DNAs. In the presence of Rad22A annealing of complementary DNAs is almost 90%. Whereas in reactions containing Rad22B the maximum level of annealing is 60%, most likely due to inhibition of the reaction by duplex DNA. Gel-filtration experiments and electron microscopic analyses indicate self-association of Rad22A and Rad22B and the formation of multimeric structures as has been observed for Rad52 in yeast and man.

  3. DFT study on structure, electronic properties, and reactivity of cis ...

    Indian Academy of Sciences (India)

    bases (HSAB) principle. HSAB principle states that,. 'hard acids prefer to coordinate with hard bases and soft acids prefer to coordinate with soft bases for both their thermodynamic and kinetic properties'.24,25. The relationship between OC–Fe–CO bond angles and backbonding to CO for the isomers discussed above.

  4. Electronic structure and magnetic properties of KCrSe2

    NARCIS (Netherlands)

    Fang, C.M.; Tolsma, P.R.; Groot, R.A. de; Wiegers, G.A.; Haas, C.; vanBruggen, C.F.; deGroot, R.A.

    1996-01-01

    KCrSe2 characterized by x-ray powder diffraction is a layered compound isostructural with NaCrSe2: a = 3.80 Angstrom; c = 22.19 Angstrom; space group R (3) over bar m. The magnetic properties are similar to those of NaCrSe2 but with ari even more pronounced difference between the intralayer and

  5. Biochemical properties and crystal structure of ethylmethylglyoxal bis(guanylhydrazone) sulfate--an extremely powerful novel inhibitor of adenosylmethionine decarboxylase.

    Science.gov (United States)

    Elo, H; Mutikainen, I; Alhonen-Hongisto, L; Laine, R; Jänne, J; Lumme, P

    1986-01-01

    Ethylmethylglyoxal bis(guanylhydrazone) (EMGBG) sulfate, an analog of the well-known anti-leukemic drug methylglyoxal bis(guanylhydrazone), was synthesized. It was shown to be an extremely powerful competitive inhibitor of eukaryotic S-adenosylmethionine decarboxylase, with an apparent Ki value 12 nM. Thus, it appears to be the most powerful known inhibitor of the enzyme, being almost an order of magnitude more powerful than the corresponding ethylglyoxal derivative. It neither inhibited the proliferation of mouse L1210 leukemia cells in vitro, nor did it potentiate the growth inhibition produced by alpha-difluoromethyl ornithine. In this respect, its properties are closely related to those of dimethylglyoxal, ethylglyoxal and propylglyoxal bis(guanylhydrazones), while in striking contrast to those of the antiproliferative glyoxal and methylglyoxal analogs. EMGBG also inhibited intestinal diamine oxidase activity (Ki 0.7 microM). EMGBG sulfate was crystallized from water, giving orthorhombic crystals (space group Pbcn). Their crystal and molecular structure was determined by X-ray diffraction methods. The carbon-nitrogen double bonds between the ethylmethylglyoxal part and the aminoguanidine moieties were found to have the same configuration as they are known to have in the salts of glyoxal, methylglyoxal and propylglyoxal bis(guanylhydrazones). The glyoxal bis(guanylhydrazone) chain of the EMGBG cation deviated strongly from planarity, thus differing dramatically from the corresponding chains of the glyoxal, methylglyoxal and propylglyoxal analogs.

  6. Physicochemical, biochemical and sensory properties for the characterization of Petrovská klobása (traditional fermented sausage

    Directory of Open Access Journals (Sweden)

    Ikonić Predrag M.

    2010-01-01

    Full Text Available A study was carried out on a typical homemade Petrovská klobasá in order to characterize this traditional dry-fermented sausage, to provide a basis for establishing the quality standard and protecting designation of origin. This paper reviews the chemical composition, some physicochemical, proteolytic and sensory parameters of Petrovská klobasá made by five manufacturers chosen as representatives. Beside the differences between sausages made by different manufacturers the main properties of this traditional product were though recognized. Compared to other dry-fermented sausages Petrovská klobasá is characterized by a high content of protein (23.36-30.45% and low contents of NaCl (2.99-3.28%. With some minor exceptions, the values of other chemical parameters are within the range of those observed for various dry-cured sausages. Weight loss during the processing is high (up to 45.71% and pH value (~ 5.4 corresponds to the values for this parameter in other European traditional fermented sausages. Contents of different nitrogen fractions show that Petrovská klobasá undergoes significant proteolytic changes. At the end of ripening, Petrovská klobasá is characterized by aromatic and spicy-hot flavor, dark-red color and hard consistency.

  7. Biochemical and biological properties of the binding of human fibrinogen to M protein in group A streptococci

    International Nuclear Information System (INIS)

    Whitnack, E.; Beachey, E.H.

    1985-01-01

    Fibrinogen is known to bind to group A streptococci and precipitate with extracts containing streptococcal M protein. The authors have previously shown that the binding of fibrinogen to M-positive streptococci prevents opsonization by complement and protects that organism from phagocytosis in nonimmune blood. In the present study, they used 3 H-labeled fibrinogen, a highly purified peptide fragment of type 24 M protein (pep M24), and anti-pep M sera to show that fibrinogen binds to M-positive streptococci with high affinity; occupation of the high-affinity binding sites suffices to protect the organism from phagocytosis; proteolytic treatments that remove M protein from streptococcal cells abolish binding; binding is competitively inhibited by anti-pep M sera; pep M24 precipitates fibrinogen; and binding to type 24 cells is inhibited by pep M24. They conclude that M protein is the cell surface structure principally responsible for binding fibrinogen on the surface of M-positive streptococci and that this binding contributes to the known antiopsonic property of M proteins

  8. Microbial mat of the thermal springs Kuchiger Republic of Buryatia: species composition, biochemical properties and electrogenic activity in biofuel cell

    Science.gov (United States)

    Aleksandrovich Yuriev, Denis; Viktorovna Zaitseva, Svetlana; Olegovna Zhdanova, Galina; Yurievich Tolstoy, Mikhail; Dondokovna Barkhutova, Darima; Feodorovna Vyatchina, Olga; Yuryevna Konovalova, Elena; Iosifovich Stom, Devard

    2018-02-01

    Electrogenic, molecular and some other properties of a microbial mat isolated from the Kuchiger hot spring (Kurumkansky District, Republic of Buryatia) were studied. Molecular analysis showed that representatives of Proteobacteria (85.5 % of the number of classified bacterial sequences) prevailed in the microbial mat of the Kuchiger springs, among which sulfur bacteria of the genus Thiothrix were the most numerous. In the microbial mat there were bacteria from the families Rhodocyclaceae, Comamonadaceae and Flavobacteriaceae. Phylum Bacteroidetes, Cyanobacteria/Chloroplast, Fusobacteria, Fibrobacteres, Acidobacteria, Chlorobi, Spirochaetes, Verrucomicrobia, Firmicutes, Deinococcus-Thermus, Chloroflexi and Actinobacteria are also noted in the composition of the microbial mat. Under the experimental conditions using Kuchiger-mat 16 as bioagents, glucose and peptone as substrates, the power of BFC was 240 and 221 mW / m2, respectively. When replacing the substrate with sodium acetate, the efficiency of the BFC was reduced by a factor of 10 (20 mW / m2). The prospects of using a microbial mat “Kuchiger-16” as an electrogen in BFC when utilizing alkaline waste water components to generate electricity are discussed.

  9. Interplay of electronic and geometry shell effects in properties of neutral and charged Sr clusters

    DEFF Research Database (Denmark)

    Lyalin, Andrey; Solov'yov, Ilia; Solov'yov, Andrey V.

    2007-01-01

    that the size evolution of structural and electronic properties of strontium clusters is governed by an interplay of the electronic and geometry shell closures. Influence of the electronic shell effects on structural rearrangements can lead to violation of the icosahedral growth motif of strontium clusters......The optimized structure and electronic properties of neutral, singly, and doubly charged strontium clusters have been investigated using ab initio theoretical methods based on density-functional theory. We have systematically calculated the optimized geometries of neutral, singly, and doubly...... charged strontium clusters consisting of up to 14 atoms, average bonding distances, electronic shell closures, binding energies per atom, the gap between the highest occupied and the lowest unoccupied molecular orbitals, and spectra of the density of electronic states (DOS). It is demonstrated...

  10. Electronic properties of diphenyl-s-tetrazine and some related oligomers. An spectroscopic and theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Moral, Monica; Garcia, Gregorio [Departamento de Quimica Fisica y Analitica, Facultad de Ciencias Experimentales, Universidad de Jaen, Campus las Lagunillas, E23071 Jaen (Spain); Penas, Antonio [Departamento de Quimica Inorganica y Organica, Facultad de Ciencias Experimentales, Universidad de Jaen, Campus las Lagunillas, E23071 Jaen (Spain); Garzon, Andres; Granadino-Roldan, Jose M. [Departamento de Quimica Fisica y Analitica, Facultad de Ciencias Experimentales, Universidad de Jaen, Campus las Lagunillas, E23071 Jaen (Spain); Melguizo, Manuel [Departamento de Quimica Inorganica y Organica, Facultad de Ciencias Experimentales, Universidad de Jaen, Campus las Lagunillas, E23071 Jaen (Spain); Fernandez-Gomez, Manuel, E-mail: mfg@ujaen.es [Departamento de Quimica Fisica y Analitica, Facultad de Ciencias Experimentales, Universidad de Jaen, Campus las Lagunillas, E23071 Jaen (Spain)

    2012-10-26

    Highlights: Black-Right-Pointing-Pointer We study properties of Ph{sub 2}Tz and (PhTz){sub n}Ph as candidates for organic electronics. Black-Right-Pointing-Pointer The synthesis of Ph{sub 2}Tz was performed through a modified Pinner-type reaction. Black-Right-Pointing-Pointer IR/Raman spectra allowed to conclude that Ph{sub 2}Tz is nearly planar in liquid phase. Black-Right-Pointing-Pointer Electronic structure was studied by UV-Vis/TD-DFT methods in different solvents. Black-Right-Pointing-Pointer Bandgap, E{sub LUMO}, electron mobility predict some n-type character for limit polymer. -- Abstract: This work presents a theoretical and spectroscopic study on the electronic and structural properties of the diphenyl-s-tetrazine molecule (Ph{sub 2}Tz) and some oligomeric derivatives. Ph{sub 2}Tz was synthesized through a variation of Pinner-type reaction which uses N-acetylcysteine as catalyst. Insight into the structure and electronic properties of the title compound was obtained through IR, Raman, UV-Vis spectra in different solvents, and theoretical calculations. Theoretical studies have been extended to different n-mers derivatives up to an ideal molecular wire through the oligomeric approximation, predicting this way electronic properties such as LUMO energy levels, electron affinity and reorganization energy in order to assess their possible applications in molecular electronics.

  11. Electronic properties and orbital-filling mechanism in Rb-intercalated copper phthalocyanine

    NARCIS (Netherlands)

    Evangelista, F.; Gotter, R.; Mahne, N.; Nannarone, S.; Ruocco, A.; Rudolf, P.

    2008-01-01

    The evolution of the electronic properties of a thin film of copper phthalocyanine deposited on Al(100) and progressively intercalated with rubidium atoms was followed by photoemission and X-ray absorption spectroscopies. Electron donation from the Rb atoms to the C32H16N8Cu molecules results in the

  12. Electronic properties of diphenyl-s-tetrazine and some related oligomers. An spectroscopic and theoretical study

    International Nuclear Information System (INIS)

    Moral, Mónica; García, Gregorio; Peñas, Antonio; Garzón, Andrés; Granadino-Roldán, José M.; Melguizo, Manuel; Fernández-Gómez, Manuel

    2012-01-01

    Highlights: ► We study properties of Ph 2 Tz and (PhTz) n Ph as candidates for organic electronics. ► The synthesis of Ph 2 Tz was performed through a modified Pinner-type reaction. ► IR/Raman spectra allowed to conclude that Ph 2 Tz is nearly planar in liquid phase. ► Electronic structure was studied by UV–Vis/TD-DFT methods in different solvents. ► Bandgap, E LUMO , electron mobility predict some n-type character for limit polymer. -- Abstract: This work presents a theoretical and spectroscopic study on the electronic and structural properties of the diphenyl-s-tetrazine molecule (Ph 2 Tz) and some oligomeric derivatives. Ph 2 Tz was synthesized through a variation of Pinner-type reaction which uses N-acetylcysteine as catalyst. Insight into the structure and electronic properties of the title compound was obtained through IR, Raman, UV–Vis spectra in different solvents, and theoretical calculations. Theoretical studies have been extended to different n-mers derivatives up to an ideal molecular wire through the oligomeric approximation, predicting this way electronic properties such as LUMO energy levels, electron affinity and reorganization energy in order to assess their possible applications in molecular electronics.

  13. Properties of the transfer matrices of deflecting magnet systems for free electron laser

    International Nuclear Information System (INIS)

    Takao, Masaru

    1993-01-01

    The oscillation of the free electron laser (FEL) requires the high current and low emittance electron beam. The beam transport system should be achromatic and isochronous to preserve the brightness and the emittance of the electron beam. In this paper we clarify the algebraic properties of the transfer matrices of the magnetic deflection system, which is a key component in the beam transport line. (author)

  14. Effect of Vermicompost and Nitroxin on Vegetative Growth and some Biochemical Properties of Rosemary Herb (Rosmarinus officinalis L.

    Directory of Open Access Journals (Sweden)

    Farzaneh Nourbakhsh

    2017-02-01

    Full Text Available Introduction: Rosemary (Rosmarinus officinalis L. is a perennial, ever green and fragrant plant belongs to Lamiaceae family. Vegetative parts of this plant have essential oil and compounds with anti oxidant and antibacterial properties which are used extensively in pharmaceutical, food and cosmetic industries. The use of biofertilizers such as vermicompost and Nitroxin could have beneficial effect on production of rosemary by increasing the production of plant growth hormones and the availability of macro and micro nutrients in growing media. Materials and Methods: The effect of vermicompost and Nitroxin biofertilizers was investigated on growth, yield, the amounts of photosynthetic pigments, flavonoid, essential oil percentage and yield of rosemary. The experiment was based on a randomized complete block design with two factors, including vermicompost (0, 10, 20, 30 and 40% w/w and Nitroxin (inoculated and non-inoculated with Nitroxin with four replications. This research was done at Sari Agricultural Sciences and Natural Resources University, Sari, Iran, in 2012-2013. Uniform one-year old rooted rosemary cuttings were selected for this experiment. Before planting, rooted cuttings were treated in diluted Nitroxin solution in water (1:10 for 10 minutes. After planting, rosemary plants were fertilized twice by Nitroxin for every 45 days according to the producing company recommendation. During growth period, irrigation was done according to plants requirement. At the end of experiment, parameters such as plant height, shoot fresh and dry weight, root dry weight, chlorophyll a, total chlorophyll, leaf flavonoid and essential oil yield were measured. Data was analyzed using standard analysis of variance (ANOVA using the general linear models procedure of SAS, (version 9.1; SAS Institute, Cary, N.C.. Differences among means were tested by least significant difference (LSD (p ≤ 0.05. Results and Discussion: Obtained results showed that the

  15. Immobilization of Lecitase® Ultra onto a novel polystyrene DA-201 resin: characterization and biochemical properties.

    Science.gov (United States)

    Liu, Ning; Fu, Min; Wang, Yong; Zhao, Qiangzhong; Sun, Weizheng; Zhao, Mouming

    2012-11-01

    A simple, rapid, and economic method of enzyme immobilization was developed for phospholipase Lecitase® ultra (LU) via interfacial adsorption. The effect of nature of the polystyrene supports and the kinetic behavior and stability of immobilized lecitase® ultra (IM-LU) were evaluated. Six macroporous resins (AB-8, X-5, DA-201, NKA-9, D101, D4006) and two anion resins (D318 and D201) were studied as the supports. DA-201 resin was selected because of its best immobilization effect for LU. Immobilization conditions were investigated, including immobilization time, pH, and enzyme concentration. IM-LU with a lipase activity of 1,652.4 ± 8.6 U/g was obtained. The adsorption process was modeled by Langmuir and Freundlich equations, and the experimental data were better fit for the former one. The kinetic constant (K (m)) values were found to be 192.7 ± 2.2 mM for the free LU and 249.3 ± 5.4 mM for the IM-LU, respectively. The V (max) value of free LU (169.5 ± 4.3 mM/min) was higher than that of the IM-LU (53.8 ± 1.5 mM/min). Combined strategies of scanning electron micrograph, thermogravimetric analysis, and Fourier transform infrared (FTIR) spectroscopy were employed to characterize the IM-LU. FTIR spectroscopy showed that the secondary conformation of the enzyme had changed after immobilization, through which a decrease of α-helix content and an increase of β-sheet content were observed. The IM-LU possessed an improved thermal stability as well as metal ionic tolerance when compared with its free form. The reusability of IM-LU was also evaluated through catalyzing esterification reaction between oleic acid and glycerol. It exhibited approximately 70 % of relative esterification efficiency after six successive cycles. This immobilized enzyme on hydrophobic support may well be used for the synthesis of structural lipids in lipid area.

  16. Effects of interfacial Fe electronic structures on magnetic and electronic transport properties in oxide/NiFe/oxide heterostructures

    International Nuclear Information System (INIS)

    Liu, Qianqian; Chen, Xi; Zhang, Jing-Yan; Yang, Meiyin; Li, Xu-Jing; Jiang, Shao-Long; Liu, Yi-Wei; Cao, Yi; Wu, Zheng-Long; Feng, Chun; Ding, Lei; Yu, Guang-Hua

    2015-01-01

    Highlights: • The magnetic and transport properties of oxide/NiFe/oxide films were studied. • The oxide (SiO 2 , MgO and HfO 2 ) has different elemental electronegativity. • Redox reaction at different NiFe/oxide interface is dependent on the oxide layer. • Different interfacial electronic structures shown by XPS influence the properties. - Abstract: We report that the magnetic and electronic transport properties in oxide/NiFe(2 nm)/oxide film (oxide = SiO 2 , MgO or HfO 2 ) are strongly influenced by the electronic structure of NiFe/oxide interface. Magnetic measurements show that there exist magnetic dead layers in the SiO 2 sandwiched film and MgO sandwiched film, whereas there is no magnetic dead layer in the HfO 2 sandwiched film. Furthermore, in the ultrathin SiO 2 sandwiched film no magnetoresistance (MR) is detected, while in the ultrathin MgO sandwiched film and HfO 2 sandwiched film the MR ratios reach 0.35% and 0.88%, respectively. The investigation by X-ray photoelectron spectroscopy reveals that the distinct interfacial redox reactions, which are dependent on the oxide layers, lead to the variation of magnetic and transport properties in different oxide/NiFe/oxide heterostructures

  17. Photon and electron interaction properties of ICRP reference man

    International Nuclear Information System (INIS)

    White, D.R.; Fitzgerald, M.; Ingram, D.

    1977-01-01

    The latest report of the Task Group of Committee 2 on Reference Man contains a comprehensive tabulation of the concentrations of 51 elements in 81 organs, tissues and tissue components. A comparison of the summation of the masses of the elements present in the tissue to the quoted total masses, has indicated discrepancies in excess of 20% for 12 tissues. The errors were generally due to data relating to the elements C, H, N or O being omitted, but certain skeletal systems were without calcium. Consequently, calculations were performed on 69 organs and tissues. Partial and total mass attenuation and energy absorption coefficients for 33 energies within the range 10 keV - 100 MeV, have been calculated using published elemental cross sections. Data were derived by the use of the conventional 'mixture rule', by summing over 51 elements. Photoelectric K, L 1 , L 2 and L 3 absorption edges for the high atomic number elements present were also considered in the analysis. Electron collision and radiation mass stopping powers, angular scattering powers and ranges have also been calculated for the same 33 energies from 10 keV - 100 MeV and for the same 69 tissues and organs. All of the tissues and organs have been categorised according to the basic fat/water/protein compositions and the magnitudes of the derived photon and electron data. The analysis has indicated a number of results of importance in radiation dosimetry. These include differences in excess of 30% in the photon interaction data at low energies for cortical bone compared to similar data for an earlier published formulation and significant K-edge discontinuities from iodine present in the thyroid. A review of this work will be given and comparisons made with interaction data derived from the previous reference Man document that was published in 1959. The implications of both the photon and the electron results in radiation dosimetry will be discussed

  18. Effect of Holstein phonons on the electronic properties of graphene

    International Nuclear Information System (INIS)

    Stauber, T; Peres, N M R

    2008-01-01

    We obtain the self-energy of the electronic propagator due to the presence of Holstein polarons within the first Born approximation. This leads to a renormalization of the Fermi velocity of 1%. We further compute the optical conductivity of the system at the Dirac point and at finite doping within the Kubo formula. We argue that the effects due to Holstein phonons are negligible and that the Boltzmann approach, which does not include inter-band transitions and can thus not treat optical phonons due to their high energy of ℎω 0 ∼ 0.1-0.2 eV, remains valid

  19. Effect of Holstein phonons on the electronic properties of graphene

    OpenAIRE

    Stauber, T.; Peres, N. M. R.

    2007-01-01

    We obtain the self-energy of the electronic propagator due to the presence of Holstein polarons within the first Born approximation. This leads to a renormalization of the Fermi velocity of one percent. We further compute the optical conductivity of the system at the Dirac point and at finite doping within the Kubo-formula. We argue that the effects due to Holstein phonons are negligible and that the Boltzmann approach which does not include inter-band transition and can thus not treat optica...

  20. Electronic transport properties in [n]cycloparaphenylenes molecular devices

    Science.gov (United States)

    Hu, Lizhi; Guo, Yandong; Yan, Xiaohong; Zeng, Hongli; Zhou, Jie

    2017-07-01

    The electronic transport of [n]cycloparaphenylenes ([n]CPPs) is investigated based on nonequilibrium Green's function formalism in combination with the density-functional theory. Negative differential resistance (NDR) phenomenon is observed. Further analysis shows that the reduction of the transmission peak induced by the bias changing near Fermi energy results in the NDR effect. Replacing the electrode (from carbon chain to Au electrode), doping with N atom and changing the size of the nanohoop (n = 5, 6, 8, 10) have also been studied and the NDR still exists, suggesting the NDR behavior is the intrinsic feature of such [n]CPPs systems, which would be quite useful in future nanoelectronic devices.

  1. effect of gamma irradiation on the biochemical and microbiological properties of the volatile constituents of coriander fruits

    International Nuclear Information System (INIS)

    Abdelaleem, M.A.

    2008-01-01

    This study was carried out to examine how irradiation can enrich the application of both coriander fruits (irradiated or not irradiated) at dose 2, 4 and 8 kGy and their essential oil at dose 4, 8 and 12 kGy as antimicrobial, antioxidant and enrich biological effect. The data could be summarized as follow:The essential oil content of irradiated coriander at dose 8 kGy was the lowest content. Moreover, the storage period of coriander fruits 12 months reduce the essential oil content to reach 0.33% in irradiated coriander at dose 8 kGy and 0.35 % in unirradiated coriander. The results found that the irradiation at dose 8 kGy eliminate most of microbial contamination of coriander fruits. In addition, 4 kGy was sufficient dose to lower the microbial load up to 0.1 x 10 2 cfu/g. Thus, 4 kGy was not only a typical dose for decontaminating coriander fruits, but also keeping the quality and sensory characteristics of coriander fruits and its essential oil.The essential oil content obtained by supercritical fluid extraction was 0.6%. Chemical properties of essential oil from irradiated coriander acid value and ester number was increased related to irradiation dose and highly increased related to storage period. While, physical properties were not showed any differences compared to control samples.GC/MS analysis represented that Linalool was 57.21% in control, increased to 63.69% and 60.24% in essential oil obtained from irradiated coriander fruits and irradiated essential oil.The threshold level of coriander essential oil added to sunflower oil was 0.1%. Oxidative stability period of sunflower oil free from antioxidants was 224 hr, while addition of 0.02% BHT to sunflower oil increased the oxidative stability to 125 %. While, addition of 0.05%, 0.1% and 0.2% essential oil obtained from irradiated coriander fruits caused detectable increments in the relative stability percentage of sunflower oil by 113.8%, 117.8% and 119.6%, respectively. The results illustrated that

  2. Electronic transport properties of fullerene functionalized carbon nanotubes: Ab initio and tight-binding calculations

    DEFF Research Database (Denmark)

    Fürst, Joachim Alexander; Hashemi, J.; Markussen, Troels

    2009-01-01

    Fullerene functionalized carbon nanotubes-NanoBuds-form a novel class of hybrid carbon materials, which possesses many advantageous properties as compared to the pristine components. Here, we report a theoretical study of the electronic transport properties of these compounds. We use both ab init...

  3. The effect of impurities on the electronic properties of MgO

    Energy Technology Data Exchange (ETDEWEB)

    Jalili, Seifollah [Department of Chemistry, K.N. Toosi University of Technology, P.O. Box 16315-1618, Tehran (Iran, Islamic Republic of); Computational Physical Sciences Research Laboratory, Department of Nano-Science, Institute for Studies in Theoretical Physics and Mathematics (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of)], E-mail: sjalili@nano.ipm.ac.ir; Majidi, Roya [Department of Physics, Shahid Beheshti University, Tehran (Iran, Islamic Republic of)

    2008-10-01

    The effect of impurities on the electronic properties of MgO is investigated using the full potential linearized augmented plane-wave plus local-orbitals method based on density functional theory. The electronic band structures and density of states of MgO in the presence of Ca, Li, and Na impurities were calculated. It is found that increasing the amount of Ca impurity decreases the energy band gap and increases the width of the upper part of the valence band. Some of the considered impurities (Li and Na) change the electronic properties of MgO extensively.

  4. The effect of impurities on the electronic properties of MgO

    International Nuclear Information System (INIS)

    Jalili, Seifollah; Majidi, Roya

    2008-01-01

    The effect of impurities on the electronic properties of MgO is investigated using the full potential linearized augmented plane-wave plus local-orbitals method based on density functional theory. The electronic band structures and density of states of MgO in the presence of Ca, Li, and Na impurities were calculated. It is found that increasing the amount of Ca impurity decreases the energy band gap and increases the width of the upper part of the valence band. Some of the considered impurities (Li and Na) change the electronic properties of MgO extensively

  5. Influence of electron irradiation on the structural and thermal properties of silk fibroin films

    Energy Technology Data Exchange (ETDEWEB)

    Asha, S.; Sangappa,; Sanjeev, Ganesh, E-mail: ganeshanjeev@rediffmail.com [Department of Studies in Physics, Mangalore University, Mangalagangotri, Mangalore - 574 199 (India)

    2015-06-24

    Radiation-induced changes in Bombyx mori silk fibroin (SF) films under electron irradiation were investigated and correlated with dose. SF films were irradiated in air at room temperature using 8 MeV electron beam in the range 0-150 kGy. Various properties of the irradiated SF films were studied using X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Electron irradiation was found to induce changes in the physical and thermal properties, depending on the radiation dose.

  6. Impact of preharvest and postharvest alginate treatments enriched with vanillin on postharvest decay, biochemical properties, quality and sensory attributes of table grapes.

    Science.gov (United States)

    Konuk Takma, Dilara; Korel, Figen

    2017-04-15

    Alginate solution enriched with vanillin as a bioactive compound was investigated for improving preharvest and postharvest quality and safety of table grapes. Alginate treatments with or without vanillin as preharvest spray and postharvest coating were implemented on table grapes of Alphonse Lavalleé and Razaki cultivars. Fungal decay, biochemical properties, quality and sensory attributes were evaluated at day of preharvest treatment, at harvesting and during 35days of storage at 4±2°C. Alginate treatments with or without vanillin were effective in preventing weight and firmness losses. Total soluble solids, titratable acidity, and color of grapes coated with alginate coatings with or without vanillin showed minor changes compared to control grapes. Alginate coating incorporating vanillin provided significant reduction (1.73log CFU/g) in yeast-mold growth. Moreover, the coatings maintained greater total phenolic content and antioxidant activity compared to others during postharvest storage. In terms of sensory attributes, appearance was ranked as the highest for alginate coating without vanillin due to glossiness of alginate. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. The perspective effects of various seed coating substances on rice seed variety Khao Dawk Mali 105 storability II: the case study of chemical and biochemical properties.

    Science.gov (United States)

    Thobunluepop, P; Pan-in, W; Pawelzik, E; Vearasilp, S

    2009-04-01

    The aim of this study was to investigate the effects of seed coating substances; chemical fungicide (CA) and biological fungicide polymers [chitosan-lignosulphonate polymer (CL) and eugenol incorporated into chitosan-lignosulphonate polymer (E+CL)] on chemical and biochemical changes of rice seeds cv. KDML 105, which have been studied during storage for 12 months. CA significantly affected the rice seed chemical properties and the associated seed deterioration. After 12 months storage, protein content decreased accompanied by declined of lipid content, increased free fatty acids and activated lipoxygenase enzyme. In the case of biological fungicide coated seeds, the antioxidative scavenging enzymes were ascorbate peroxidase and superoxide dismutase and a high antioxidant activity protected them. Moreover, the sugar content was positive correlated with seed germination and vigor. The biological coated seeds were found to maintain high sugar contents inside the seeds, which resulted high seed storability significantly. In contrast, under fungicide stress (CA), those compounds were lost that directly affected seed vigor during storage.

  8. Structure-property effects on mechanical, friction and wear properties of electron modified PTFE filled EPDM composite

    Directory of Open Access Journals (Sweden)

    2009-01-01

    Full Text Available Tribological properties of Ethylene-Propylene-Diene-rubber (EPDM containing electron modified Polytetrafluoroethylene (PTFE have been investiagted with the help of pin on disk tribometer without lubrication for a testing time of 2 hrs in atmospheric conditions at a sliding speed and applied normal load of 0.05 m•s–1 and FN = 1 N, respectively. Radiation-induced chemical changes in electron modified PTFE powders were analyzed using Electron Spin Resonance (ESR and Fourier Transform Infrared (FTIR specroscopy to characterize the effects of compatibility and chemical coupling of modified PTFE powders with EPDM on mechanical, friction and wear properties. The composites showed different friction and wear behaviour due to unique morphology, dispersion behaviour and radiation functionalization of PTFE powders. In general, EPDM reinforced with electron modified PTFE powder demonstrated improvement both in mechanical and tribological properties. However, the enhanced compatibility of PTFE powder resulting from the specific chemical coupling of PTFE powder with EPDM has been found crucial for mechanical, friction and wear properties.

  9. Electronic and optical properties of 2D graphene-like ZnS: DFT calculations

    International Nuclear Information System (INIS)

    Lashgari, Hamed; Boochani, Arash; Shekaari, Ashkan; Solaymani, Shahram; Sartipi, Elmira; Mendi, Rohollah Taghavi

    2016-01-01

    Graphical abstract: - Highlights: • DFT has been applied to investigate the optical properties of 2D-ZnS and 3D-ZnS. • The electronic and the optical properties of 3D-ZnS and 2D-ZnS are compared. • At visible range of energies the transparency of 2D-ZnS is more than the 3D. - Abstract: Density-functional theory has been applied to investigate the electronic and optical properties of graphene-like two-dimensional ZnS in the (0001) direction of its Wurtzite phase. A comparison with 3D-ZnS has been carried out within the PBE- and EV-GGA. The electronic properties of 2D- and 3D-ZnS have been derived by the examination of the electronic band structures and density of states. The optical properties have been determined through the study of the dielectric function, reflectivity, electron loss function, refractive and extinction indices, the absorption index and optical conductivity. It is found that the transparency of 2D-ZnS is greater than the 3D over the visible range. A thorough study of the dielectric function has been performed so that the peaks and the transition bands have been specified. The electron loss function demonstrates that the plasmonic frequency for 2D- and 3D-ZnS is accrued at 11.22 and 19.93 eV within the PBE-GGA, respectively.

  10. Electronic and optical properties of finite carbon nanotubes in an electric field

    International Nuclear Information System (INIS)

    Chen, R B; Lee, C H; Chang, C P; Lin, M F

    2007-01-01

    The effects, caused by the geometric structure and an electric field (E), on the electronic and optical properties of quasi-zero-dimensional finite carbon nanotubes are explored by employing the tight-binding model coupled with curvature effects. Electronic properties (state energies, symmetry of electronic states, energy spacing and state degeneracy) are significantly affected by the magnitude and the direction of the electric field and the geometric structure (radius, length and chirality). The electric field, by lowering the symmetry of finite carbon nanotubes, modifies the electronic properties. Thus, the optical excitation spectra, excited by electric polarization parallel to the nanotube axis, exhibit rich delta-function-like peaks, which reveal the characteristics of the electronic properties. Therefore it follows that geometric structure and E influence the low-energy absorption spectra, i.e. the change of frequency of the first peak, the alternation of the peak height and the production of the new peaks. There are more absorption peaks when E is oriented closer to the cross-section plane. Moreover, the very complicated optical absorption spectra are characteristic for the individual chiral carbon nanotube due to its specific geometric structure. Above all, the predicted absorption spectra and the associated electronic properties could be verified by optical measurements

  11. Sr2CeO4: Electronic and structural properties

    International Nuclear Information System (INIS)

    Rocha, Leonardo A.; Schiavon, Marco A.; Nascimento, Clebio S.; Guimarães, Luciana; Góes, Márcio S.; Pires, Ana M.; Paiva-Santos, Carlos O.

    2014-01-01

    Highlights: • Sr 2 CeO 4 it was obtained from the heat treatment of Ce 3+ -doped strontium oxalate. • Rietveld analysis made it possible to obtain information about crystalline structure. • Experimental band gap value was compared with theoretical obtained by Sparkle/PM7. • The materials obtained shows intense photoluminescence and scintillator properties. - Abstract: This work presents on the preparation and photoluminescent properties of Sr 2 CeO 4 obtained from the heat treatment of Ce(III)-doped strontium oxalate (10, 25 and 33 mol%). The oxalate precursors were heat treated at 1100 °C for 12 h. The structure of this photoluminescent material was evaluated by the Rietveld method. The route used in this work to prepare the materials showed to be viable when compared to other synthesis reported in the literature. The Sr 2 CeO 4 material showed a broad and intense band emission with a maximum around 485 nm. The quantitative phase analysis showed that the Sr 2 CeO 4 photoluminescent phase is the majority one compared to the impurity phases of SrCeO 3 and SrCO 3 . From all results it was possible to verify a complete elimination of the CeO 2 phase for the sample obtained from the heat treatment of oxalate precursor containing 33 mol% of cerium(III). The material showed excellent properties for possible candidate as scintillator materials, and in the improvement of efficiency of solar cells when excited in the UV–vis region. The CIE chromaticity diagram it is also reported in this work

  12. Electrical properties of irradiated PVA film by using ion/electron beam

    Science.gov (United States)

    Abdelrahman, M. M.; Osman, M.; Hashhash, A.

    2016-02-01

    Ion/electron beam bombardment has shown great potential for improving the surface properties of polymers. Low-energy charged (ion/electron) beam irradiation of polymers is a good technique to modify properties such as electrical conductivity, structural behavior, and their mechanical properties. This paper reports on the effect of nitrogen and electron beam irradiation on the electrical properties of polyvinyl alcohol (PVA) films. PVA films of 4 mm were exposed to a charged (ion/electron) beam for different treatment times (15, 30, and 60 minutes); the beam was produced from a dual beam source using nitrogen gas with the other ion/electron source parameters optimized. The dielectric loss tangent tan δ , electrical conductivity σ , and dielectric constant ɛ ^' } in the frequency range 100 Hz-100 kHz were measured at room temperature. The variation of dielectric constant and loss tangent as a function of frequency was also studied at room temperature. The dielectric constant was found to be strongly dependent on frequency for both ion and electron beam irradiation doses. The real (ɛ ^' }) and imaginary (ɛ ^' ' }) parts of the dielectric constant decreased with frequency for all irradiated and non-irradiated samples. The AC conductivity showed an increase with frequency for all samples under the influence of both ion and electron irradiation for different times. Photoluminescence (PL) spectral changes were also studied. The formation of clusters and defects (which serve as non-radiative centers on the polymer surface) is confirmed by the decrease in the PL intensity.

  13. Structural, electronic and elastic properties of heavy fermion YbRh2 Laves phase compound

    Science.gov (United States)

    Pawar, Harsha; Shugani, Mani; Aynyas, Mahendra; Sanyal, Sankar P.

    2018-05-01

    The structural, electronic and elastic properties of YbRh2 Laves phase intermetallic compound which crystallize in cubic (MgCu2-type) structure have been investigated using ab-initio full potential linearized augmented plane wave (FP- LAPW) method with LDA and LDA+U approximation. The calculated ground state properties such as lattice parameter (a0), bulk modulus (B) and its pressure derivative (B') are in good agreement with available experimental and theoretical data. The electronic properties are analyzed from band structures and density of states. Elastic constants are predicted first time for this compound which obeys the stability criteria for cubic system.

  14. The thermal and mechanical properties of electron beam-irradiated polylactide

    International Nuclear Information System (INIS)

    Kuk, In Seol; Jung, Chan Hee; Hwang, In Tae; Choi, Jae Hak; Nho, Young Chang

    2010-01-01

    The effect of electron beam irradiation on the thermal and mechanical properties of polylactide (PLA) was investigated in this research. PLA films were irradiated by electron beams at different absorption doses ranging from 20 to 200 kGy. The thermal and mechanical properties of the irradiated PLA films were investigated by means of differential scanning calorimeter, thermogravimetric analyzer, universal testing machine, dynamic mechanical analyzer, and thermal mechanical analyzer. The results revealed that the chain scission of the PLA predominated over the crosslinking during the irradiation, which considerably deteriorated the thermal and mechanical properties of the PLA

  15. Transport properties of electrons in fractal magnetic-barrier structures

    Science.gov (United States)

    Sun, Lifeng; Fang, Chao; Guo, Yong

    2010-09-01

    Quantum transport properties in fractal magnetically modulated structures are studied by the transfer-matrix method. It is found that the transmission spectra depend sensitively not only on the incident energy and the direction of the wave vector but also on the stage of the fractal structures. Resonance splitting, enhancement, and position shift of the resonance peaks under different magnetic modulation are observed at four different fractal stages, and the relationship between the conductance in the fractal structure and magnetic modulation is also revealed. The results indicate the spectra of the transmission can be considered as fingerprints for the fractal structures, which show the subtle correspondence between magnetic structures and transport behaviors.

  16. Effect of Soil Salinity, Type and Amount of Nitrogen Fertilizer on Yield and Biochemical Properties of Mustard (Brassica rapa L.

    Directory of Open Access Journals (Sweden)

    S Tandisseh

    2017-03-01

    Full Text Available Introduction Soil salinity is a major limiting factor in agricultural development within Iran. Nitrogen is the most important nutrient that its uptake is limited over other elements under saline conditions due to decrease in the permeability of plant roots, soil microbial activity and mineralization of organic compounds and nitrate uptake by high concentrations of chloride anions in the root zone of the plant. Mustard plant has a good compatibility to weather conditions and since there is an extreme need of vegetable oilseed in our country and also wide extent of saline soils in Iran, this study was conducted to determine the best type and amount of nitrogen fertilizers between calcium nitrate and ammonium sulfate under saline conditions. Materials and Methods A greenhouse experiment was conducted in a completely randomized design (factorial with three replications in February 2012 in the Research greenhouse of the Ferdowsi University of Mashhad. The treatments were consisted of two types of nitrogen fertilizer (calcium nitrate and ammonium sulfate, each with three levels of N (40, 80 and 120 mg per kg of soil in three levels of soil salinity (C0= control, C1= 5 and C2= 10dS m-1. Experimental soil (control collected from agricultural experimental station was leached by salt solutions containing salts of calcium chloride, magnesium chloride and sodium sulfate with specified concentrations and ratios during 50 days to reach the similar salt concentrations of leached water consisting the desired levels of salinity. The seeds of mustard were planted at a depth of one centimeter in soil of each pot and were irrigated with tap water to field capacity (by weight. Plants were harvested after 5 months and plant fresh and dry weights and nitrogen concentration and uptake of plant were measured by the Kjeldahl method. Irrigation water and physical and chemical properties of soil before and after harvest were determined. Data obtained were analyzed using

  17. Electron beam properties and impedance characterization for storage rings used for free electron lasers

    International Nuclear Information System (INIS)

    Dattoli, G.; Mezi, L.; Renieri, A.; Migliorati, M.; Walker, R.

    2000-01-01

    Good electron beam qualities and stability are the crucial features of Storage Rings dedicated to synchrotron radiation sources or to Free Electron Laser. Most of these characteristics depends on the coupling of the e-beam with the machine environment, which can be in turn modelled in terms of a characteristic impedance, whose absolute value and structure can be used to specify both the stability (longitudinal and transverse) of the beam and its qualities (energy spread, bunch length, peak current ...). In this paper are considered two specific examples of Storage Rings used for FEL operation and analyze their performances by means of semi analytical and numerical methods. The analysis is aimed at clarifying the dependence of beam energy spread and bunch length on beam current and at providing a set of parameters useful for the optimization of Free Electron Laser or synchrotron radiation sources [it

  18. Influence of external effects on the electron silicon properties

    International Nuclear Information System (INIS)

    Orazgulyev, B.; Bigozha, O.D.

    2005-01-01

    It is noted, that study of angular dependence of longitudinal piezo-resistance of n-type silicon presents the both scientific and practical interest because the obtained data could serve the ground for creating a high-sensitive piezo-sensors. Measurement of angular dependence allows objectively estimate the errors of anisotropy parameter determination, constant of deformation potential caused of mistakes in maintenance of crystallographic directions during the samples production process. In the case of X||J||[111] at one-axis deformation a new kind of piezo-effect in electron silicon is revealed. It is explained by transformation of iso-energy rotation ellipsoid into three-axis ellipsoid at presence of shear silicon crystal deformation

  19. Experimental Investigation of Charging Properties of Interstellar Type Silica Dust Grains by Secondary Electron Emissions

    Science.gov (United States)

    Tankosic, D.; Abbas, M. M.

    2013-01-01

    The dust charging by electron impact is an important dust charging processes in astrophysical and planetary environments. Incident low energy electrons are reflected or stick to the grains charging the dust grains negatively. At sufficiently high energies electrons penetrate the grains, leading to excitation and emission of electrons referred to as secondary electron emission (SEE). Available classical theoretical models for calculations of SEE yields are generally applicable for neutral, planar, or bulk surfaces. These models, however, are not valid for calculations of the electron impact charging properties of electrostatically charged micron/submicron-size dust grains in astrophysical environments. Rigorous quantum mechanical models are not yet available, and the SEE yields have to be determined experimentally for development of more accurate models for charging of individual dust grains. At the present time, very limited experimental data are available for charging of individual micron-size dust grains, particularly for low energy electron impact. The experimental results on individual, positively charged, micron-size lunar dust grains levitated carried out by us in a unique facility at NASA-MSFC, based on an electrodynamic balance, indicate that the SEE by electron impact is a complex process. The electron impact may lead to charging or discharging of dust grains depending upon the grain size, surface potential, electron energy, electron flux, grain composition, and configuration (Abbas et al, 2010, 2012). In this paper, we discuss SEE charging properties of individual micron-size silica microspheres that are believed to be analogs of a class of interstellar dust grains. The measurements indicate charging of the 0.2m silica particles when exposed to 25 eV electron beams and discharging when exposed to higher energy electron beams. Relatively large size silica particles (5.2-6.82m) generally discharge to lower equilibrium potentials at both electron energies

  20. Synthesis and electrical properties of silver nanoplates for electronic applications

    Directory of Open Access Journals (Sweden)

    Xiong Nana

    2015-06-01

    Full Text Available In this paper, silver nanoplates of 100 to 500 nm size were synthesized by reduction of silver nitrate with N,Ndimethylformamide, using poly(vinylpyrolidone as a surfactant and ferric chloride as a controlling agent, at 120 to 160 °C for 5 to 24 hours. The influence of the concentration of ferric chloride, the reaction temperature and reaction time on the morphology of the product has been investigated by transmission electron microscopy, scanning electron microscopy and UV-Vis spectroscopy. The results indicated that the products obtained at the low reaction temperature and short reaction time in the presence of FeCl3 in the reaction solution were in the form of silver nanoplates, whose morphology was mainly triangular and hexagonal. In addition, the size and thickness of the nanoplates increased with increasing of the FeCl3 concentration. At a high reaction temperature and long reaction time, the truncated triangle and hexagonal nanoplates were mainly produced. Furthermore, the sintering behavior of nanoplates was studied and the results showed that sintering of the silver nanoplates started at 180 °C, and a typical sintering behavior was observed at higher temperatures. The incorporation of the silver nanoplates into the polymer matrix with micro-sized silver flakes led to an increase in the matrix resistivity in almost all cases, especially at high fractions and low curing temperatures. The curing temperature had an influence on the resistivity of the conductive adhesives filled with micro-sized silver flakes and silver nanoplates due to sintering of the silver nanoplates.

  1. Novel silicon allotropes: Stability, mechanical, and electronic properties

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Qingyang; Chai, Changchun; Zhao, Yingbo; Yang, Yintang; Yu, Xinhai; Liu, Yang; Zhang, Junqin [Key Laboratory of Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi' an 710071 (China); Wei, Qun, E-mail: weiaqun@163.com; Yao, Ronghui [School of Physics and Optoelectronic Engineering, Xidian University, Xi' an 710071 (China); Yan, Haiyan [College of Chemistry and Chemical Engineering, Baoji University of Arts and Sciences, Baoji 721013 (China); Xing, Mengjiang [Faculty of Information Engineering and Automation, Kunming University of Science and Technology, Kunming 650051 (China)

    2015-11-14

    One quasi-direct gap phase (Amm2) and three indirect gap phases (C2/m-16, C2/m-20, and I-4) of silicon allotropes are proposed. The detailed theoretical study on the structure, density of states, elastic properties, sound velocities, and Debye temperature of these four phases is carried out by using first principles calculations. The elastic constants of these four phases are calculated by strain-stress method. The elastic constants and the phonon calculations manifest all novel silicon allotropes in this paper are mechanically and dynamically stable at ambient condition. The B/G values indicate that these four phases of silicon are brittle materials at ambient pressure. The anisotropy properties show that C2/m-20 phase exhibits a larger anisotropy in its elastic modulus, shear elastic anisotropic factors, and several anisotropic indices than others. We have found that the Debye temperature of the four novel silicon allotropes gradually reduces in the order of C2/m-20 > Amm2 > C2/m-16 > I-4 at ambient pressure.

  2. Investigations on the structure – Property relationships of electron beam welded Inconel 625 and UNS 32205

    International Nuclear Information System (INIS)

    Devendranath Ramkumar, K.; Sridhar, R.; Periwal, Saurabh; Oza, Smitkumar; Saxena, Vimal; Hidad, Preyas; Arivazhagan, N.

    2015-01-01

    Highlights: • Joining of dissimilar metals of Inconel 625 and UNS S32205 using electron beam welding. • Detailed structure – property relationship of dissimilar welds. • Improved metallurgical and tensile properties from the EB welding. - Abstract: The metallurgical and mechanical properties of electron beam welded Ni based superalloy Inconel 625 and UNS S32205 duplex stainless steel plates have been investigated in the present study. Interface microstructure studies divulged the absence of any grain coarsening effects or the formation of any secondary phases at the heat affected zone (HAZ) of the electron beam (EB) weldments. Tensile studies showed that the fracture occurred at the weld zone in all the trials and the average weld strength was reported to be 850 MPa. Segregation of Mo rich phases was witnessed at the inter-dendritic arms of the fusion zone. The study recommended the use of EB welding for joining these dissimilar metals by providing detailed structure – property relationships

  3. Electronic and Optical Properties of CuO Based on DFT+U and GW Approximation

    International Nuclear Information System (INIS)

    Ahmad, F; Agusta, M K; Dipojono, H K

    2016-01-01

    We report ab initio calculations of electronic structure and optical properties of monoclinic CuO based on DFT+U and GW approximation. CuO is an antiferromagnetic material with strong electron correlations. Our calculation shows that DFT+U and GW approximation sufficiently reliable to investigate the material properties of CuO. The calculated band gap of DFT+U for reasonable value of U slightly underestimates. The use of GW approximation requires adjustment of U value to get realistic result. Hybridization Cu 3dxz, 3dyz with O 2p plays an important role in the formation of band gap. The calculated optical properties based on DFT+U and GW corrections by solving Bethe-Salpeter are in good agreement with the calculated electronic properties and the experimental result. (paper)

  4. Theoretical study of electronic transport properties of a graphene-silicene bilayer

    Energy Technology Data Exchange (ETDEWEB)

    Berdiyorov, G. R. [Qatar Environment and Energy Research Institute, Qatar Foundation, P.O. Box 5825, Doha (Qatar); Bahlouli, H. [Department of Physics, King Fahd University of Petroleum and Minerals, 31261 Dhahran (Saudi Arabia); Saudi Center for Theoretical Physics, 31261 Dhahran (Saudi Arabia); Peeters, F. M. [Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium)

    2015-06-14

    Electronic transport properties of a graphene-silicene bilayer system are studied using density-functional theory in combination with the nonequilibrium Green's function formalism. Depending on the energy of the electrons, the transmission can be larger in this system as compared to the sum of the transmissions of separated graphene and silicene monolayers. This effect is related to the increased electron density of states in the bilayer sample. At some energies, the electronic states become localized in one of the layers, resulting in the suppression of the electron transmission. The effect of an applied voltage on the transmission becomes more pronounced in the layered sample as compared to graphene due to the larger variation of the electrostatic potential profile. Our findings will be useful when creating hybrid nanoscale devices where enhanced transport properties will be desirable.

  5. The biochemical properties of the Arabidopsis ecto-nucleoside triphosphate diphosphohydrolase AtAPY1 contradict a direct role in purinergic signaling.

    Directory of Open Access Journals (Sweden)

    Carolin Massalski

    Full Text Available The Arabidopsis E-NTPDase (ecto-nucleoside triphosphate diphosphohydrolase AtAPY1 was previously shown to be involved in growth and development, pollen germination and stress responses. It was proposed to perform these functions through regulation of extracellular ATP signals. However, a GFP-tagged version was localized exclusively in the Golgi and did not hydrolyze ATP. In this study, AtAPY1 without the bulky GFP-tag was biochemically characterized with regard to its suggested role in purinergic signaling. Both the full-length protein and a soluble form without the transmembrane domain near the N-terminus were produced in HEK293 cells. Of the twelve nucleotide substrates tested, only three--GDP, IDP and UDP--were hydrolyzed, confirming that ATP was not a substrate of AtAPY1. In addition, the effects of pH, divalent metal ions, known E-NTPDase inhibitors and calmodulin on AtAPY1 activity were analyzed. AtAPY1-GFP extracted from transgenic Arabidopsis seedlings was included in the analyses. All three AtAPY1 versions exhibited very similar biochemical properties. Activity was detectable in a broad pH range, and Ca(2+, Mg(2+ and Mn(2+ were the three most efficient cofactors. Of the inhibitors tested, vanadate was the most potent one. Surprisingly, sulfonamide-based inhibitors shown to inhibit other E-NTPDases and presumed to inhibit AtAPY1 as well were not effective. Calmodulin stimulated the activity of the GFP-tagless membranous and soluble AtAPY1 forms about five-fold, but did not alter their substrate specificities. The apparent Km values obtained with AtAPY1-GFP indicate that AtAPY1 is primarily a GDPase. A putative three-dimensional structural model of the ecto-domain is presented, explaining the potent inhibitory potential of vanadate and predicting the binding mode of GDP. The found substrate specificity classifies AtAPY1 as a nucleoside diphosphatase typical of N-terminally anchored Golgi E-NTPDases and negates a direct function in

  6. Electronic and Spectral Properties of RRhSn (R = Gd, Tb) Intermetallic Compounds

    Science.gov (United States)

    Knyazev, Yu. V.; Lukoyanov, A. V.; Kuz'min, Yu. I.; Gupta, S.; Suresh, K. G.

    2018-02-01

    The investigations of electronic structure and optical properties of GdRhSn and TbRhSn were carried out. The calculations of band spectrum, taking into account the spin polarization, were performed in a local electron density approximation with a correction for strong correlation effects in 4f shell of rare earth metal (LSDA + U method). The optical studies were done by ellipsometry in a wide range of wavelengths, and the set of spectral and electronic characteristics was determined. It was shown that optical absorption in a region of interband transitions has a satisfactory explanation within a scope of calculations of density of electronic states carried out.

  7. Electronic properties of iron impurity in hcp metals from Moessbauer studies

    International Nuclear Information System (INIS)

    Janot, C.; Delcroix, P.

    1975-01-01

    Moessbauer spectroscopy was used in quantitative investigating the electronic properties of iron impurities in hexagonal close-packed metals. Beryllium of the highest commercially obtainable purity containing about 300 ppm residual impurities was used as a host element. Experimental evidence is given for the existence of localized electronic states which have non-spherical distribution and obviously contribute especially to the electric field gradient. Iron impurity seems to retain the same electronic behaviour as long as the host hcp metal is a normal one (Mg, Cd, Zn), but the localized electronic states seem to disappear when the host is a transition hcp metal (Co, Ti, Sc, Zr, etc.). (Z.S.)

  8. Humidity effects on the electronic transport properties in carbon based nanoscale device

    International Nuclear Information System (INIS)

    He, Jun; Chen, Ke-Qiu

    2012-01-01

    By applying nonequilibrium Green's functions in combination with the density functional theory, we investigate the effect of humidity on the electronic transport properties in carbon based nanoscale device. The results show that different humidity may form varied localized potential barrier, which is a very important factor to affect the stability of electronic transport in the nanoscale system. A mechanism for the humidity effect is suggested. -- Highlights: ► Electronic transport in carbon based nanoscale device. ► Humidity affects the stability of electronic transport. ► Different humidity may form varied localized potential barrier.

  9. γ-irradiation effect on electronic properties in hydrogenated amorphous silicon

    International Nuclear Information System (INIS)

    Shirafuji, J.; Nagata, S.; Shirakawa, K.

    1986-01-01

    γ-irradiation effect on electron transport and photoelectric properties in glow-discharge hydrogenated amorphous silicon is investigated mainly by means of time-of-flight measurement. Although the electron transport changes from non-dispersive to dispersive when the total dose on γ-rays is increased, the electron mobility at room temperature is affected only slightly by γ-irradiation. The γ-irradiation introduces dominantly Si dangling bonds, allowing to study the recombination characteristic as a function of dangling bond density under controllable conditions. It is found that the electron recombination lifetime is inversely proportional to the dangling bond density. (author)

  10. Physical characterization of functionalized spider silk: electronic and sensing properties

    Directory of Open Access Journals (Sweden)

    Eden Steven, Jin Gyu Park, Anant Paravastu, Elsa Branco Lopes, James S Brooks, Ongi Englander, Theo Siegrist, Papatya Kaner and Rufina G Alamo

    2011-01-01

    Full Text Available This work explores functional, fundamental and applied aspects of naturally harvested spider silk fibers. Natural silk is a protein polymer where different amino acids control the physical properties of fibroin bundles, producing, for example, combinations of β-sheet (crystalline and amorphous (helical structural regions. This complexity presents opportunities for functional modification to obtain new types of material properties. Electrical conductivity is the starting point of this investigation, where the insulating nature of neat silk under ambient conditions is described first. Modification of the conductivity by humidity, exposure to polar solvents, iodine doping, pyrolization and deposition of a thin metallic film are explored next. The conductivity increases exponentially with relative humidity and/or solvent, whereas only an incremental increase occurs after iodine doping. In contrast, iodine doping, optimal at 70 °C, has a strong effect on the morphology of silk bundles (increasing their size, on the process of pyrolization (suppressing mass loss rates and on the resulting carbonized fiber structure (that becomes more robust against bending and strain. The effects of iodine doping and other functional parameters (vacuum and thin film coating motivated an investigation with magic angle spinning nuclear magnetic resonance (MAS-NMR to monitor doping-induced changes in the amino acid-protein backbone signature. MAS-NMR revealed a moderate effect of iodine on the helical and β-sheet structures, and a lesser effect of gold sputtering. The effects of iodine doping were further probed by Fourier transform infrared (FTIR spectroscopy, revealing a partial transformation of β-sheet-to-amorphous constituency. A model is proposed, based on the findings from the MAS-NMR and FTIR, which involves iodine-induced changes in the silk fibroin bundle environment that can account for the altered physical properties. Finally, proof

  11. Physical characterization of functionalized spider silk: electronic and sensing properties

    Energy Technology Data Exchange (ETDEWEB)

    Steven, Eden; Brooks, James S [Department of Physics and National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac, Tallahassee, FL 32310 (United States); Park, Jin Gyu [FAMU-FSU Department of Industrial and Manufacturing Engineering, High-Performance Materials Institute, Florida State University, 2005 Levy Ave., Tallahassee, FL 32310 (United States); Paravastu, Anant; Siegrist, Theo; Kaner, Papatya; Alamo, Rufina G [FAMU-FSU Department of Chemical and Biomedical Engineering and National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac, Tallahassee, FL 32310 (United States); Branco Lopes, Elsa [Departamento de Quimica, Instituto Tecnologico e Nuclear/CFMC-UL, P-2686-953 Sacavem (Portugal); Englander, Ongi, E-mail: esteven@magnet.fsu.edu [FAMU-FSU Department of Mechanical Engineering and National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac, Tallahassee, Florida 32310 (United States)

    2011-10-15

    This work explores functional, fundamental and applied aspects of naturally harvested spider silk fibers. Natural silk is a protein polymer where different amino acids control the physical properties of fibroin bundles, producing, for example, combinations of {beta}-sheet (crystalline) and amorphous (helical) structural regions. This complexity presents opportunities for functional modification to obtain new types of material properties. Electrical conductivity is the starting point of this investigation, where the insulating nature of neat silk under ambient conditions is described first. Modification of the conductivity by humidity, exposure to polar solvents, iodine doping, pyrolization and deposition of a thin metallic film are explored next. The conductivity increases exponentially with relative humidity and/or solvent, whereas only an incremental increase occurs after iodine doping. In contrast, iodine doping, optimal at 70 deg. C, has a strong effect on the morphology of silk bundles (increasing their size), on the process of pyrolization (suppressing mass loss rates) and on the resulting carbonized fiber structure (that becomes more robust against bending and strain). The effects of iodine doping and other functional parameters (vacuum and thin film coating) motivated an investigation with magic angle spinning nuclear magnetic resonance (MAS-NMR) to monitor doping-induced changes in the amino acid-protein backbone signature. MAS-NMR revealed a moderate effect of iodine on the helical and {beta}-sheet structures, and a lesser effect of gold sputtering. The effects of iodine doping were further probed by Fourier transform infrared (FTIR) spectroscopy, revealing a partial transformation of {beta}-sheet-to-amorphous constituency. A model is proposed, based on the findings from the MAS-NMR and FTIR, which involves iodine-induced changes in the silk fibroin bundle environment that can account for the altered physical properties. Finally, proof

  12. Physical characterization of functionalized spider silk: electronic and sensing properties

    International Nuclear Information System (INIS)

    Steven, Eden; Brooks, James S; Park, Jin Gyu; Paravastu, Anant; Siegrist, Theo; Kaner, Papatya; Alamo, Rufina G; Branco Lopes, Elsa; Englander, Ongi

    2011-01-01

    This work explores functional, fundamental and applied aspects of naturally harvested spider silk fibers. Natural silk is a protein polymer where different amino acids control the physical properties of fibroin bundles, producing, for example, combinations of β-sheet (crystalline) and amorphous (helical) structural regions. This complexity presents opportunities for functional modification to obtain new types of material properties. Electrical conductivity is the starting point of this investigation, where the insulating nature of neat silk under ambient conditions is described first. Modification of the conductivity by humidity, exposure to polar solvents, iodine doping, pyrolization and deposition of a thin metallic film are explored next. The conductivity increases exponentially with relative humidity and/or solvent, whereas only an incremental increase occurs after iodine doping. In contrast, iodine doping, optimal at 70 deg. C, has a strong effect on the morphology of silk bundles (increasing their size), on the process of pyrolization (suppressing mass loss rates) and on the resulting carbonized fiber structure (that becomes more robust against bending and strain). The effects of iodine doping and other functional parameters (vacuum and thin film coating) motivated an investigation with magic angle spinning nuclear magnetic resonance (MAS-NMR) to monitor doping-induced changes in the amino acid-protein backbone signature. MAS-NMR revealed a moderate effect of iodine on the helical and β-sheet structures, and a lesser effect of gold sputtering. The effects of iodine doping were further probed by Fourier transform infrared (FTIR) spectroscopy, revealing a partial transformation of β-sheet-to-amorphous constituency. A model is proposed, based on the findings from the MAS-NMR and FTIR, which involves iodine-induced changes in the silk fibroin bundle environment that can account for the altered physical properties. Finally, proof-of-concept applications of

  13. Equilibrium and stability properties of relativistic electron rings and E-layers

    International Nuclear Information System (INIS)

    Uhm, H.

    1976-01-01

    Equilibrium and stability properties of magnetically confined partially-neutralized thin electron ring and E-layer are investigated using the Vlasov-Maxwell equations. The analysis is carried out within the context of the assumption that the minor dimensions (a,b) of the system are much less than the collisionless skin depth (c/antiω/sub p/). The equilibrium configuration of the E-layer is assumed to be an infinitely long, azimuthally symmetric hollow electron beam which is aligned parallel to a uniform axial magnetic field. On the other hand, the electron ring is located at the midplane of an externally imposed mirror field which acts to confine the ring both axially and radially. The equilibrium properties of the E-layer and electron ring are obtained self-consistently for several choices of equilibrium electron distribution function. The negative-mass instability analysis is carried out for the relativistic E-layer equilibrium in which all of the electrons have the same transverse energy and a spread in canonical angular momentum, assuming a fixed ion background. The ion resonance instability properties are investigated for a relativistic nonneutral E-layer aligned parallel to a uniform magnetic field and located between two ground coaxial cylindrical conductors. The stability properties of a nonrelativistic electron ring is investigated within the framework of the linearized Vlasov-Poisson equations. The dispersion relation is obtained for the self-consistent electron distribution function in which all electrons have the same value of energy an the same value of canonical angular momentum. The positive ions in the electron ring are assumed to form an immobile partially neutralizing background. The stability criteria as well as the instability growth rates are derived and discussed including the effect of geometrical configuration of the system. Equilibrium space-charge effects play a significant role in stability behavior

  14. Electronic computer prediction of properties of binary refractory transition metal compounds on the base of their simplificated electronic structure

    International Nuclear Information System (INIS)

    Kutolin, S.A.; Kotyukov, V.I.

    1979-01-01

    An attempt is made to obtain calculation equations of macroscopic physico-chemical properties of transition metal refractory compounds (density, melting temperature, Debye characteristic temperature, microhardness, standard formation enthalpy, thermo-emf) using the method of the regression analysis. Apart from the compound composition the argument of the regression equation is the distribution of electron bands of d-transition metals, created by the energy electron distribution in the simplified zone structure of transition metals and approximated by Chebishev polynoms, by the position of Fermi energy on the map of distribution of electron band energy depending upon the value of quasi-impulse, multiple to the first, second and third Brillouin zone for transition metals. The maximum relative error of the regressions obtained as compared with the literary data is 15-20 rel.%

  15. All-electron study of ultra-incompressible superhard material ReB2: structural and electronic properties

    International Nuclear Information System (INIS)

    Yan-Ling, Li; Guo-Hua, Zhong; Zhi, Zeng

    2009-01-01

    This paper investigates the structural and electronic properties of rhenium diboride by first-principles calculation based on density functional theory. The obtained results show that the calculated equilibrium structural parameters of ReB 2 are in excellent agreement with experimental values. The calculated bulk modulus is 361 GPa in comparison with that of the experiment. The compressibility of ReB 2 is lower than that of well-known OsB 2 . The anisotropy of the bulk modulus is confirmed by c/a ratio as a function of pressure curve and the bulk modulus along different axes along with the electron density distribution. The high bulk modulus is attributed to the strong covalent bond between Re-d and B-p orbitals and the wider pseudogap near the Fermi level, which could be deduced from both electron charge density distribution and density of states. The band structure and density of states of ReB 2 exhibit that this material presents metallic behavior. The good metallicity and ultra-incompressibility of ReB 2 might suggest its potential application as pressure-proof conductors. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  16. Transmission properties of Dirac electrons through Cantor monolayer graphene superlattices

    Directory of Open Access Journals (Sweden)

    R. Rodríguez-González

    2014-01-01

    Full Text Available En este trabajo usamos el método de la matriz de transferencia para estudiar el tunelamiento de los electrones de Dirac a través de superredes aperiodicas en grafeno. Consideramos una hoja de grafeno depositada encima de bloques de sustratos de Óxido de Silicio (SiO2 y Carburo de Silicio (SiC, en los cuales aplicamos la serie de Cantor. Calculamos la transmitancia para diferentes parámetros fundamentales tales como: ancho de partida, energía de incidencia, ángulo de incidencia y número de generación de la serie de Cantor. En este caso, la transmitancia como función de la energía presenta rasgos autosimilares al variar el número de generación. También computamos la distribución angular de la transmitancia para energías fijas econtrando un patrón autosimilar entre generaciones. Por último, calculamos los factores de escala para algunos espectros de la transmitancia, los cuales efectivamente muestran escalabilidad.

  17. Study on time of flight property of electron optical systems by differential algebraic method

    International Nuclear Information System (INIS)

    Cheng Min; Tang Tiantong; Yao Zhenhua

    2002-01-01

    Differential algebraic method is a powerful and promising technique in computer numerical analysis. When applied to nonlinear dynamics systems, the arbitrary high-order transfer properties of the systems can be computed directly with high precision. In this paper, the principle of differential algebra is applied to study on the time of flight (TOF) property of electron optical systems and their arbitrary order TOF transfer properties can be numerically calculated out. As an example, TOF transfer properties of a uniform magnetic sector field analyzer have been studied by differential algebraic method. Relative errors of the first-order and second-order TOF transfer coefficients of the magnetic sector field analyzer are of the order 10 -11 or smaller compared with the analytic solutions. It is proved that differential algebraic TOF method is of high accuracy and very helpful for high-order TOF transfer property analysis of electron optical systems. (author)

  18. Modulation of electronic and magnetic properties in InSe nanoribbons: edge effect

    Science.gov (United States)

    Wu, Meng; Shi, Jun-jie; Zhang, Min; Ding, Yi-min; Wang, Hui; Cen, Yu-lang; Guo, Wen-hui; Pan, Shu-hang; Zhu, Yao-hui

    2018-05-01

    Quite recently, the two-dimensional (2D) InSe nanosheet has become a hot material with great promise for advanced functional nano-devices. In this work, for the first time, we perform first-principles calculations on the structural, electronic, magnetic and transport properties of 1D InSe nanoribbons with/without hydrogen or halogen saturation. We find that armchair ribbons, with various edges and distortions, are all nonmagnetic semiconductors, with a direct bandgap of 1.3 (1.4) eV for bare (H-saturated) ribbons, and have the same high electron mobility of about 103 cm2V‑1s‑1 as the 2D InSe nanosheet. Zigzag InSe nanoribbons exhibit metallic behavior and diverse intrinsic ferromagnetic properties, with the magnetic moment of 0.5–0.7 μ B per unit cell, especially for their single-edge spin polarization. The edge spin orientation, mainly dominated by the unpaired electrons of the edge atoms, depends sensitively on the edge chirality. Hydrogen or halogen saturation can effectively recover the structural distortion, and modulate the electronic and magnetic properties. The binding energy calculations show that the stability of InSe nanoribbons is analogous to that of graphene and better than in 2D InSe nanosheets. These InSe nanoribbons, with novel electronic and magnetic properties, are thus very promising for use in electronic, spintronic and magnetoresistive nano-devices.

  19. Electronic properties of electron and hole in type-II semiconductor nano-heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Rahul, K. Suseel [Department of Physics, Central University of Kerala, Riverside Transit Campus, Kasaragod, Kerala. India (India); Department of Physics, Sri Vyasa NSS College, Wadakkancheri, Thrissur, Kerala, PIN:680623. India (India); Souparnika, C. [Department of Physics, Sri Vyasa NSS College, Wadakkancheri, Thrissur, Kerala, PIN:680623. India (India); Salini, K.; Mathew, Vincent, E-mail: vincent@cukerala.ac.in [Department of Physics, Central University of Kerala, Riverside Transit Campus, Kasaragod, Kerala. India (India)

    2016-05-06

    In this project, we record the orbitals of electron and hole in type-II (CdTe/CdSe/CdTe/CdSe) semiconductor nanocrystal using effective mass approximation. In type-II the band edges of both valance and conduction band are higher than that of shell. So the electron and hole get confined in different layers of the hetero-structure. The energy eigen values and eigen functions are calculated by solving Schrodinger equation using finite difference matrix method. Based on this we investigate the effect of shell thickness and well width on energy and probability distribution of ground state (1s) and few excited states (1p,1d,etc). Our results predict that, type-II quantum dots have significant importance in photovoltaic applications.

  20. Electronic properties of electron and hole in type-II semiconductor nano-heterostructures

    Science.gov (United States)

    Rahul, K. Suseel; Souparnika, C.; Salini, K.; Mathew, Vincent

    2016-05-01

    In this project, we record the orbitals of electron and hole in type-II (CdTe/CdSe/CdTe/CdSe) semiconductor nanocrystal using effective mass approximation. In type-II the band edges of both valance and conduction band are higher than that of shell. So the electron and hole get confined in different layers of the hetero-structure. The energy eigen values and eigen functions are calculated by solving Schrodinger equation using finite difference matrix method. Based on this we investigate the effect of shell thickness and well width on energy and probability distribution of ground state (1s) and few excited states (1p,1d,etc). Our results predict that, type-II quantum dots have significant importance in photovoltaic applications.

  1. Electronic properties in a two-dimensional disordered electron liquid: Spin-valley interplay

    International Nuclear Information System (INIS)

    Burmistrov, I. S.; Chtchelkatchev, N. M.

    2008-01-01

    We report a detailed study of the influence of the spin and valley splittings on such physical observables of the two-dimensional disordered electron liquid as resistivity and spin and valley susceptibilities. We explain qualitatively the nonmonotonic dependence of the resistivity on temperature in the presence of a parallel magnetic field. In the presence of either spin or valley splitting we predict a temperature dependence of the resistivity with two maximum points

  2. Interface engineering for oxide electronics: tuning electronic properties by atomically controlled growth

    NARCIS (Netherlands)

    Huijben, Mark

    2006-01-01

    The main aim of this thesis is to develop a controlled growth with atomic precision for the realization of artificial perovskite structures, to exploit the exceptional physical properties of complex oxide materials such as high-temperature superconductors and conducting interfaces between band

  3. Thermoluminescence, infrared reflectivity and electron paramagnetic resonance properties of hemimorphite

    Energy Technology Data Exchange (ETDEWEB)

    Gallegos, E.A. [Institute of Physics, University of Sao Paulo, Rua do Matao, Travessa R, 187, CEP 05508-900, Sao Paulo, SP (Brazil); Cano, N.F. [Institute of Physics, University of Sao Paulo, Rua do Matao, Travessa R, 187, CEP 05508-900, Sao Paulo, SP (Brazil)], E-mail: nilocano@dfn.if.usp.br; Watanabe, S.; Chubaci, J.F.D. [Institute of Physics, University of Sao Paulo, Rua do Matao, Travessa R, 187, CEP 05508-900, Sao Paulo, SP (Brazil)

    2009-01-15

    Silicate mineral hemimorphite has been investigated concerning its TL, IR and EPR properties. A broad TL peak around 180 deg. C and a weaker and narrower peak around 360 deg. C were found in a sample annealed at 600 deg. C for 1 h and then irradiated. The deconvolution using the CGCD method revealed peaks around 132, 169, 222 and 367 deg. C. The reflectivity measurements showed several bands in the NIR region due to H{sub 2}O, OH and Al-OH complexes. No band was observed in the visible region. The thermal treatments were carried out from {approx}110 to 940 deg. C and dehydration was observed, first causing a diminishing optical absorption in general and the disappearance of water and hydroxyl absorption bands. The EPR spectrum of natural hemimorphite, presented Cu{sup 2+} signals at g = 2.4 and g = 2.1 plus E{sub 1}' signal superposed to Fe{sup 3+} signal around g = 2.0.

  4. Polyimide-Epoxy Composites with Superior Bendable Properties for Application in Flexible Electronics

    Science.gov (United States)

    Lee, Sangyoup; Yoo, Taewon; Han, Youngyu; Kim, Hanglim; Han, Haksoo

    2017-08-01

    The need for flexible electronics with outstanding bending properties is increasing due to the demand for wearable devices and next-generation flexible or rollable smartphones. In addition, the requirements for flexible or rigid-flexible electronics are sharply increasing to achieve the design of space-saving electronic devices. In this regard, coverlay (CL) film is a key material used in the bending area of flexible electronics, albeit infrequently. Because flexible electronics undergo folding and unfolding numerous times, CL films with superior mechanical and bending properties are required so that the bending area can endure such severe stress. However, because current CL films are only used for a designated bending area in the flexible electronics panel, their highly complicated and expensive manufacturing procedure is a disadvantage. In addition, the thickness of CL films must be decreased to satisfy the ongoing requirement for increasingly thin products. However, due to the limitations of the two-layer structure of existing CL films, the manufacturing process cannot be made more cost effective by simply applying more thin film onto the board. To address this problem, we have developed liquid coverlay inks (LCIs) with superior bendable properties, in comparison with CL films, when applied onto flexible electronics using a screen-printing method. The results show that LCIs have the potential to become one of the leading candidates to replace existing CL films because of their lower cost and faster manufacturing process.

  5. Outline of irradiation service equipment and properties of its electron beam

    International Nuclear Information System (INIS)

    Kagehira, K.; Shakudo, T.

    2002-01-01

    Current ethylene oxide sterilization becomes a subject of discussion on the safety for workers' health. On the other hand, demands for sterilization of disposable health care products and food packaging materials are increasing. On this situation, it is progressing to switch to radiation sterilization witch is easy to adapt to requirements of ISO validation, in particular to electron beam sterilization using electron accelerator, which is safer and easier to control. Our company started electron beam treatment service such as pasteurization, disinfestation, and improvement of polymers as well as sterilization, with introducing a high energy and high power electron accelerator. In this paper, basics of e-beam sterilization, outline of the irradiation service plant and the electron accelerator, and the properties of its electron beam are described. (author)

  6. Outline of irradiation service equipment and properties of its electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Kagehira, K.; Shakudo, T. [Nuclear Fuel Industries, Ltd., Osaka (Japan)

    2002-10-01

    Current ethylene oxide sterilization becomes a subject of discussion on the safety for workers' health. On the other hand, demands for sterilization of disposable health care products and food packaging materials are increasing. On this situation, it is progressing to switch to radiation sterilization witch is easy to adapt to requirements of ISO validation, in particular to electron beam sterilization using electron accelerator, which is safer and easier to control. Our company started electron beam treatment service such as pasteurization, disinfestation, and improvement of polymers as well as sterilization, with introducing a high energy and high power electron accelerator. In this paper, basics of e-beam sterilization, outline of the irradiation service plant and the electron accelerator, and the properties of its electron beam are described. (author)

  7. GGA+U investigations of impurity d-electrons effects on the electronic and magnetic properties of ZnO

    KAUST Repository

    Ul Haq, Bakhtiar

    2014-08-01

    Stimulation of novel features in ZnO by impurity electrons has attracted a remarkable attention of researchers from the past decade. Consequently, ZnO has found several applications in the field of spintronics and optoelectronics. We report, the effect of 3d-(V, Ag) electrons on the properties of ZnO in stable wurtzite (WZ) and metastable zincblende (ZB) phase using the density functional theory. Introduction of V-3d electrons was found to induce a high magnetic moment value of 5.22 in WZ and 3.26 in the ZB phase, and moreover transform the semiconductor character of ZnO into a metallic nature. Ag-d electrons result in the p-type half-metallic nature of ZnO with a weak ferromagnetic background. Our calculations for ground-state magnetic ordering show that ZnO in the presence of impure 3d-(V, Ag) electrons favors ferromagnetic ordering, and obey the double exchange mechanism. However, impurity atoms have very marginal effect on the lattice parameters of ZnO, thereby exposing its potential to absorb the impurity atoms in high concentration. © 2014 Elsevier B.V. All rights reserved.

  8. Electronic and optical properties of doped oxides for energy conversion

    International Nuclear Information System (INIS)

    Silva, Antonio Ferreira da

    2016-01-01

    Full text: Photocatalytic materials have gained remarkable attention in the field of solar fuel production, which is a promising approach for efficient solar energy conversion and storage . Among other oxides, doped BiNb(Ta)O 4 , ZnO , SnO 2 , WO 3 and TiO 2 have been identified as potential photocatalytic materials due to their appropriate band gap energies. We have used high quality materials as for instance by the citrate method according to reference [1], a modified ion beam assisted deposition technique [2] and as titanium dioxide nanotubes (TiO 2 -NTs) arrays synthesized by electrochemical anodization [3]. We present the optical properties spectra of these materials using the X-ray Photoelectron Spectroscopy (XPS), Ellipsometry and first principles approach by DFT respectively [1,2]. In this work, position of reduction and oxidation level with respect to the vacuum level are identified for these materials. We can conclude that some of them are good candidates for the production of hydrogen by splitting of water in the presence of sunlight and for efficient solar energy conversion as well. [1] C. G. Almeida, R. B. Araujo, R. G. Yoshimura, A. J. S. Mascarenhas, A. Ferreira da Silva, C. M.Araujo, L. A. Silva,Int. J. Hyd. Energy 39, 1220 (2014). [2] M. Kumar, G.Baldissera, C.Persson, D.G.F.David ,M.V.S.da Silva , J.A.Freitas Jr., J.G. Tischler , J.F.D.Chubaci, M.Matsuoka , A.Ferreira da Silva, , J. of Crystal Growth 403, 124 (2014). [3] J. R. Gonzalez et all., Nanotechnology (2016 in press). (author)

  9. Electronic and optical properties of doped oxides for energy conversion

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Antonio Ferreira da, E-mail: ferreira.fis@gmail.com [Universidade Federal da Bahia (UFBA), Salvador (Brazil)

    2016-07-01

    Full text: Photocatalytic materials have gained remarkable attention in the field of solar fuel production, which is a promising approach for efficient solar energy conversion and storage . Among other oxides, doped BiNb(Ta)O{sub 4}, ZnO , SnO{sub 2}, WO{sub 3} and TiO{sub 2} have been identified as potential photocatalytic materials due to their appropriate band gap energies. We have used high quality materials as for instance by the citrate method according to reference [1], a modified ion beam assisted deposition technique [2] and as titanium dioxide nanotubes (TiO{sub 2}-NTs) arrays synthesized by electrochemical anodization [3]. We present the optical properties spectra of these materials using the X-ray Photoelectron Spectroscopy (XPS), Ellipsometry and first principles approach by DFT respectively [1,2]. In this work, position of reduction and oxidation level with respect to the vacuum level are identified for these materials. We can conclude that some of them are good candidates for the production of hydrogen by splitting of water in the presence of sunlight and for efficient solar energy conversion as well. [1] C. G. Almeida, R. B. Araujo, R. G. Yoshimura, A. J. S. Mascarenhas, A. Ferreira da Silva, C. M.Araujo, L. A. Silva,Int. J. Hyd. Energy 39, 1220 (2014). [2] M. Kumar, G.Baldissera, C.Persson, D.G.F.David ,M.V.S.da Silva , J.A.Freitas Jr., J.G. Tischler , J.F.D.Chubaci, M.Matsuoka , A.Ferreira da Silva, , J. of Crystal Growth 403, 124 (2014). [3] J. R. Gonzalez et all., Nanotechnology (2016 in press). (author)

  10. Stability and electronic structure of carbon capsules with superior gas storage properties: A theoretical study

    International Nuclear Information System (INIS)

    Manna, Arun K.; Pati, Swapan K.

    2013-01-01

    Highlights: • Stability and electronic structure of various carbon capsules are studied. • Effects of capsule’s sizes on electronic and optical properties are explored. • Changes in cohesive and formation energy and electronic gap are discussed. • Capsule’s gas storage propensity is addressed using DFT and ab initio MD. • Capsule’s optical absorptions are discussed with and without stored gas molecules. - Abstract: Structures, electronic and optical properties of carbon nanocapsules of varying sizes (length and diameter) are studied using first-principles density functional theory. Based on calculated cohesive energy, formation energy, electronic gap and extent of orbital delocalization, we examine structural stability and changes in low-energy physics of these carbon capsules. We find that both cohesive and formation energy decrease with increase in capsule’s sizes, indicating their greater structural rigidity and favorable formation feasibility. The electronic gap also decreases with increase in capsule’s sizes due to the larger electronic delocalization. The simulated optical absorption spectra show lowering of low-energy peak positions with increase in the capsule’s dimensions, consistent with the reduction in electronic gap. Additionally, we also provide an estimate of gas storage capacity for the larger carbon capsule (C 460 ) considered. We find 7.69 wt.% and 28.08 wt.% storage propensity for hydrogen and carbon dioxide gases, respectively, which clearly suggests their potential use as light storage materials

  11. Opto-electronic and quantum transport properties of semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Sabathil, M.

    2005-01-01

    In this work a novel and efficient method for the calculation of the ballistic transport properties of open semiconductor nanostructures connected to external reservoirs is presented. It is based on the Green's function formalism and reduces the effort to obtain the transmission and the carrier density to a single solution of a hermitian eigenvalue problem with dimensions proportional to the size of the decoupled device and the multiple inversion of a small matrix with dimensions proportional to the size of the contacts to the leads. Using this method, the 4-band GaAs hole transport through a 2-dimensional three-terminal T-junction device, and the resonant tunneling current through a 3-dimensional InAs quantum dot molecule embedded into an InP heterostructure have been calculated. The further extension of the method into a charge self-consistent scheme enables the efficient prediction of the IV-characteristics of highly doped nanoscale field effect transistors in the ballistic regime, including the influence of quasi bound states and the exchange-correlation interaction. Buettiker probes are used to emulate the effect of inelastic scattering on the current for simple 1D devices, systematically analyzing the dependence of the density of states and the resulting self-consistent potential on the scattering strength. The second major topic of this work is the modeling of the optical response of quantum confined neutral and charged excitons in single and coupled self-assembled InGaAs quantum dots. For this purpose the existing device simulator nextnano{sup 3} has been extended to incorporate particle-particle interactions within the means of density functional theory in local density approximation. In this way the exciton transition energies for neutral and charged excitons as a function of an externally applied electric field have been calculated, revealing a systematic reduction of the intrinsic dipole with the addition of extra holes to the exciton, a finding

  12. Electronic properties of hafnium oxide: A contribution from defects and traps

    Energy Technology Data Exchange (ETDEWEB)

    Gritsenko, Vladimir A., E-mail: grits@isp.nsc.ru; Perevalov, Timofey V.; Islamov, Damir R., E-mail: damir@isp.nsc.ru

    2016-02-15

    In the present article, we give a review of modern data and latest achievements pertaining to the study of electronic properties of oxygen vacancies in hafnium oxide. Hafnium oxide is a key dielectric for use in many advanced silicon devices. Oxygen vacancies in hafnium oxide largely determine the electronic properties of the material. We show that the electronic transitions between the states due to oxygen vacancies largely determine the optical absorption and luminescent properties of hafnium oxide. We discuss the role of oxygen vacancies as traps that facilitate charge transport in hafnium oxide films. Also, we demonstrate the fact that the electrical conductivity in hafnium oxide is controlled by the phonon-assisted tunnelling of charge carriers between traps that were identified as oxygen vacancies.

  13. Mechanical and thermal properties of commercial multilayer PET/PP film irradiated with electron-beam

    International Nuclear Information System (INIS)

    Ortiz, Angel V.; Nogueira, Beatriz R.; Oliveira, Vitor M.; Moura, Esperidiana A.B.

    2009-01-01

    The effects of electron-beam irradiation on mechanical and thermal properties, for one commercial flexible food packaging multilayer structure, were studied. The laminated poly(ethylene terephthalate) (PET)/ polypropylene (PP) structure was irradiated up to 60 kGy, using a 1.5 MeV electron beam accelerator, at room temperature in the presence of air. Mechanical properties showed significant changes (p < 0.05). In addition, the DSC analysis, after treatment, showed that the fusion enthalpy and crystallinity of the PET/PP structure components presented significant changes (p < 0.05) with the electron-beam radiation doses applied. It was observed an increase in PP crystallinity while the PET crystallinity decreases. Such decrease in PET crystallinity indicates the predominance of a cross-linking process on the irradiated PET layer; responsible for the increase in some mechanical properties of the studied film. (author)

  14. First-principles investigation on structural and electronic properties of antimonene nanoribbons and nanotubes

    Science.gov (United States)

    Nagarajan, V.; Chandiramouli, R.

    2018-03-01

    The electronic properties of antimonene nanotubes and nanoribbons hydrogenated along the zigzag and armchair borders are investigated with the help of density functional theory (DFT) method. The structural stability of antimonene nanostructures is confirmed with the formation energy. The electronic properties of hydrogenated zigzag and armchair antimonene nanostructures are studied in terms of highest occupied molecular orbital (HOMO) & lowest unoccupied molecular orbital (LUMO) gap and density of states (DOS) spectrum. Moreover, due to the influence of buckled orientation, hydrogen passivation and width of antimonene nanostructures, the HOMO-LUMO gap widens in the range of 0.15-0.41 eV. The findings of the present study confirm that the electronic properties of antimonene nanostructures can be tailored with the influence of width, orientation of the edges, passivation with hydrogen and morphology of antimonene nanostructures (nanoribbons, nanotubes), which can be used as chemical sensor and for spintronic devices.

  15. Cloning and determination of biochemical properties of protective and broadly conserved vaccine antigens from the genome of extraintestinal pathogenic Escherichia coli into pET28a vector

    Directory of Open Access Journals (Sweden)

    Jamil Kheirvari Khezerloo

    2017-12-01

    Full Text Available Urinary tract infections are one of the most common infectious diseases that lead to significant health problems in the world. Urinary tract infections are referred to any infection in any part of the renal system. Uropathogenic Escherichia coli, Proteus mirabilis, and Klebsiella are main organisms that are involved in these infections. After identifying same protective and conserved virulence sequences in these microorganisms with similarity upper than 80%, sequences of synthetic gene was provided by bioinformatics techniques and ordered from Thermo Fisher Scientific Company. PCR amplification of this gene was performed by specific primers designed for this purpose. Construction of gene was performed by overlap PCR. The synthetic gene was cloned into pET28a vector. Our gene was amplified in E. coli Top10 tested. To confirm cloning, three methods including colony PCR, digestion and sequencing were used. First, two techniques were performed using horizontal electrophoresis, and also the synthetic gene showed significant homology with the sequence (99% Identified in sequencing. Sequencing of this gene showed that fusion was constructed correctly. Determination of biochemical properties such as 3D structure, Ramachandran and comparison of Non-redundant Set of PDB structure was done by bioinformatic software and had exact and expectable results. A large part of the health system in the world is occupied by a urinary tract infection and governments spend a huge amount of money for the treatment and recovery of patients with these infections. On the other hands, antibiotic resistance in the not-far future will be a disaster for medical societies. This is the most important reason for the emergence of vaccine production against urinary tract infections.

  16. Ab initio structural and electronic properties of hydrogenated silicon nanoclusters in the ground and excited state

    International Nuclear Information System (INIS)

    Degoli, Elena; Bisi, O.; Ossicini, Stefano; Cantele, G.; Ninno, D.; Luppi, Eleonora; Magri, Rita

    2004-01-01

    Electronic and structural properties of small hydrogenated silicon nanoclusters as a function of dimension are calculated from ab initio technique. The effects induced by the creation of an electron-hole pair are discussed in detail, showing the strong interplay between the structural and optical properties of the system. The distortion induced on the structure after an electronic excitation of the cluster is analyzed together with the role of the symmetry constraint during the relaxation. We point out how the overall effect is that of significantly changing the electronic spectrum if no symmetry constraint is imposed to the system. Such distortion can account for the Stokes shift and provides a possible structural model to be linked to the four-level scheme invoked in the literature to explain recent results for the optical gain in silicon nanoclusters. Finally, formation energies for clusters with increasing dimension are calculated and their relative stability discussed

  17. Electronic structures and magnetic/optical properties of metal phthalocyanine complexes

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Shintaro; Suzuki, Atsushi, E-mail: suzuki@mat.usp.ac.jp; Oku, Takeo [Department of Materials Science, The University of Shiga Prefecture. 2500 Hassaka, Hikone, Shiga 522-8533 (Japan)

    2016-02-01

    Electronic structures and magnetic / optical properties of metal phthalocyanine complexes were studied by quantum calculations using density functional theory. Effects of central metal and expansion of π orbital on aromatic ring as conjugation system on the electronic structures, magnetic, optical properties and vibration modes of infrared and Raman spectra of metal phthalocyanines were investigated. Electron and charge density distribution and energy levels near frontier orbital and excited states were influenced by the deformed structures varied with central metal and charge. The magnetic parameters of chemical shifts in {sup 13}C-nuclear magnetic resonance ({sup 13}C-NMR), principle g-tensor, A-tensor, V-tensor of electric field gradient and asymmetry parameters derived from the deformed structures with magnetic interaction of nuclear quadruple interaction based on electron and charge density distribution with a bias of charge near ligand under crystal field.

  18. Structural and electronic properties of in-plane phase engineered WSe2: A DFT study

    Science.gov (United States)

    Bhart, Ankush; Kapoor, Pooja; Sharma, Munish; Sharma, Raman; Ahluwalia, P. K.

    2018-04-01

    We present first principal investigations on structural and electronic properties of in-plane phase engineered WSe2 with armchair type interface. The 2H and 1T phases of WSe2, joined along x-direction is a natural metal-semiconductor heterostructure and therefore shows potential for applications in 2D electronics and opto-electronics. The electronic properties transit towards metallic 1T region. No inflections across interface shows negligible mismatch strain which is unlike what has been reported for MoS2. Charge density analysis shows charge accumulation on 1T domain. This can lead to reduction of Schottky barrier heights at the metal-semiconductor junction. STM analysis confirms transition of 1T phase towards distorted 1T' structure. The present results provide essential insights for nano-devices using 2D hybrid materials.

  19. Interpolation of property-values between electron numbers is inconsistent with ensemble averaging

    Energy Technology Data Exchange (ETDEWEB)

    Miranda-Quintana, Ramón Alain [Laboratory of Computational and Theoretical Chemistry, Faculty of Chemistry, University of Havana, Havana (Cuba); Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Ayers, Paul W. [Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1 (Canada)

    2016-06-28

    In this work we explore the physical foundations of models that study the variation of the ground state energy with respect to the number of electrons (E vs. N models), in terms of general grand-canonical (GC) ensemble formulations. In particular, we focus on E vs. N models that interpolate the energy between states with integer number of electrons. We show that if the interpolation of the energy corresponds to a GC ensemble, it is not differentiable. Conversely, if the interpolation is smooth, then it cannot be formulated as any GC ensemble. This proves that interpolation of electronic properties between integer electron numbers is inconsistent with any form of ensemble averaging. This emphasizes the role of derivative discontinuities and the critical role of a subsystem’s surroundings in determining its properties.

  20. Chemical and biochemical properties of Stagnic Albeluvisols organic matter as result of long-term agricultural management and native forest ecosystem

    Science.gov (United States)

    Astover, Alar; Kõlli, Raimo; Wojciech Szajdak, Lech

    2010-05-01

    Soil organic matter (SOM) is considered to be as the most important factor in soil forming, development and continuous functioning. Sequestrated into SOM organic carbon concentrations, pools and residence time in soil, as well acting intensity of interconnected with SOM edaphon are soil type specific or characteristic to certain soil types. In depending on soil moisture regime, calcareousness and clay content for each soil type certain soil organic carbon (SOC) retaining capacity and its vertical distribution pattern are characteristic. However, land use change (crop rotation, continuous cropping, no-tillage, melioration, rewetting) has greatest influence mainly on fabric of epipedon and biological functions of soil cover. Stagnic Albeluvisols are largely distributed at Tartu County. They form here more than half from arable soils. The establishment of long-term field trial and forest research area in these regions for biochemical analysis of Stagnic Albeluvisols' organic matter is in all respects justified. In 1989, an international long-term experiment on the organic nitrogen or IOSDV (Internationale Organische Stickstoffdauerdiingungsversuche) with three-field crop rotation (potato - spring wheat - spring barley) was started at Eerika near Tartu (58° 22.5' N; 26° 39.8' E) on Stagnic Albeluvisol. The main aims of this study were to determine the long-term effects of cropping systems on physico-chemical properties of soils and their productivity. The design of this field experiment is similar to other European network of IOSDV experiments. Before the establishment of this experiment in 1989 it was in set-aside state (5-6 years) as field-grass fallow. It was used as arable land in condition of state farm during 1957-83. Average agrochemical characteristics of the plough horizon of soil in the year of establishment were the following: humus content 17.1 g kg-1, total nitrogen content 0.9 g kg-1, C:N ratio 11 and pHKCl 6.3. DL soluble phosphorus content was 44 mg

  1. Dielectric properties of electron irradiated PbZrO 3 thin films

    Indian Academy of Sciences (India)

    The present paper deals with the study of the effects of electron (8 MeV) irradiation on the dielectric and ferroelectric properties of PbZrO3 thin films grown by sol–gel technique. The films were (0.62 m thick) subjected to electron irradiation using Microtron accelerator (delivered dose 80, 100, 120 kGy). The films were well ...

  2. Electronic structure and spectral properties of heavy actinides Pu, Am, Cm and Bk

    International Nuclear Information System (INIS)

    Shick, Alexander B; Kolorenc, Jindrich; Lichtenstein, Alexander I; Havela, Ladislav

    2010-01-01

    Selected electronic properties of Pu, Am, Cm and Bk are calculated with the aid of charge self-consistent LDA + Hubbard I method. Presented all-electron calculations are performed in the full-potential LAPW basis and incorporate spin-orbit interaction. The results are found to be in good agreement with experimental valence photoelectron spectra as well as with core XAS/EELS spectra of heavy actinides.

  3. Lattice dynamics and electronic properties of superconducting Nbsub(x)Vsub(1-x)N compounds

    International Nuclear Information System (INIS)

    Geibel, C.; Rietschel, H.; Pelizzone, M.; Junod, A.; Muller, J.

    1982-01-01

    The Nbsub(x)Vsub(1-x)N-system presents a pronounced minimum in Tsub(c) at the composition Nbsub(0.5)Vsub(0.5)N. We investigated the structural, the electronic properties and the lattice dynamics of these compounds to study whether this minimum is induced by structural defects, a decrease of the electron-phonon-coupling or by spin fluctuations. (orig.)

  4. Nonlinear and Nonsymmetric Single-Molecule Electronic Properties Towards Molecular Information Processing.

    Science.gov (United States)

    Tamaki, Takashi; Ogawa, Takuji

    2017-09-05

    This review highlights molecular design for nonlinear and nonsymmetric single-molecule electronic properties such as rectification, negative differential resistance, and switching, which are important components of future single-molecule information processing devices. Perspectives on integrated "molecular circuits" are also provided. Nonlinear and nonsymmetric single-molecule electronics can be designed by utilizing (1) asymmetric molecular cores, (2) asymmetric anchoring groups, (3) an asymmetric junction environment, and (4) asymmetric electrode materials. This review mainly focuses on the design of molecular cores.

  5. Optical and electronic properties of polyvinyl alcohol doped with pairs of mixed valence metal ions

    International Nuclear Information System (INIS)

    Bulinski, Mircea; Kuncser, Victor; Plapcianu, Carmen; Krautwald, Stefan; Franke, Hilmar; Rotaru, P; Filoti, George

    2004-01-01

    The electronic mechanisms induced by the UV exposure of thin films of polyvinyl alcohol doped with pairs of mixed valence metal ions were studied in relation to their optical behaviour by Moessbauer spectroscopy and optical absorption. The results obtained definitely point to the role of each element from the pair in the electronic mechanism involved, with influence on the optical properties regarding applications in real-time holography and integrated optics

  6. Study of beam transverse properties of a thermionic electron gun for application to a compact THz free electron laser

    International Nuclear Information System (INIS)

    Hu, Tongning; Qin, Bin; Tan, Ping; Chen, Qushan; Yang, Lei; Pei, Yuanji; Li, Ji

    2014-01-01

    A novel thermionic electron gun adopted for use in a high power THz free electron laser (FEL) is proposed in this paper. By optimization of the structural and radiofrequency (RF) parameters, the physical design of the gun is performed using dynamic calculations. Velocity bunching is used to minimize the bunch's energy spread, and the dynamic calculation results indicate that high quality beams can be provided. The transverse properties of the beams generated by the gun are also analyzed. The novel RF focusing effects of the resonance cavity are investigated precisely and are used to establish emittance compensation, which enables the injector length to be reduced. In addition, the causes of the extrema of the beam radius and the normalized transverse emittance are analyzed and interpreted, respectively, and slice simulations are performed to illustrate how the RF focusing varies along the bunch length and to determine the effects of that variation on the emittance compensation. Finally, by observation of the variations of the beam properties in the drift tube behind the electron gun, prospective assembly scenarios for the complete THz-FEL injector are discussed, and a joint-debugging process for the injector is implemented

  7. Electronic and Optical Properties of Aluminum Oxide Before and After Surface Reduction by Ar+ Bombardment

    Directory of Open Access Journals (Sweden)

    D. Tahir

    2014-08-01

    Full Text Available The electronic and optical properties of a-Al2O3 after induced by 3-keV Ar+ sputtering have been studied quantitatively by use of reflection electron energy loss spectroscopy (REELS spectra. The band gap values of a-Al2O3 was determined from the onset values of the energy loss spectrum to the background level of REELS spectra as a function of time Ar+ bombardment. The bandgap changes from 8.4 eV before sputtering to 6.2 eV after 4 minutes of sputtering.The optical properties of α-Al2O3 thin films have been determined by comparing the experimental cross section obtained from reflection electron energy loss spectroscopy with the theoretical inelastic scattering cross section, deduced from the simulated energy loss function (ELF by using QUEELS-ε(k-REELS software. The peak assignments are based on ELF and compared with reported data on the electronic structure of α-Al2O3 obtained using different techniques. The results demonstrate that the electronic and optical properties before and after surface reduction will provide further understanding in the fundamental properties of α-Al2O3 which will be useful in the design, modeling and analysis of devices applications performance.

  8. Electronic Structure and Optical Properties of Co and Fe doped ZnO

    Directory of Open Access Journals (Sweden)

    Li Chunping

    2016-01-01

    Full Text Available First-principle ultrasoft pseudo potential approach of the plane wave based on density functional theory has been used for studying the electronic characterization and optical properties of ZnO and Fe, Co doped ZnO. The results show that the doping impurities change the lattice parameters a little, but bring more changes in the electronic structures. The band gaps are broadened by doping. And the Fermi level accesses to the conduction band which will lead the system to show the character of metallic properties. The dielectric function and absorption peaks are identified and the changes compared to pure ZnO are analyzed in detail.

  9. Structural and electronic properties of GaAs and GaP semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Rani, Anita [Guru Nanak College for girls, Sri Muktsar Sahib, Punjab (India); Kumar, Ranjan [Department of Physics, Panjab University, Chandigarh-160014 (India)

    2015-05-15

    The Structural and Electronic properties of Zinc Blende phase of GaAs and GaP compounds are studied using self consistent SIESTA-code, pseudopotentials and Density Functional Theory (DFT) in Local Density Approximation (LDA). The Lattice Constant, Equillibrium Volume, Cohesive Energy per pair, Compressibility and Band Gap are calculated. The band gaps calcultated with DFT using LDA is smaller than the experimental values. The P-V data fitted to third order Birch Murnaghan equation of state provide the Bulk Modulus and its pressure derivatives. Our Structural and Electronic properties estimations are in agreement with available experimental and theoretical data.

  10. Electronic Properties of Functional Biomolecules at Metal/Aqueous Solution Interfaces

    DEFF Research Database (Denmark)

    Zhang, Jingdong; Chi, Qijin; Kuznetsov, A.M.

    2002-01-01

    in electronic properties and stochastic single-molecule features and can be probed by new methods which approach the single-molecule level. Olle of these is in situ scanning tunneling microscopy (STM) in which single-molecule electronic properties directly in aqueous solution are probed. In situ STM combined...... with physical electrochemistry, single-crystal electrodes, and spectroscopic methods is now a new dimension in interfacial bioelectrochemistry. We overview first same approaches to spectroscopic single-molecule imaging, including fluorescence spectroscopy, chemical reaction dynamics, atomic force microscopy...

  11. Spinel ferrite nanocrystals embedded inside ZnO: magnetic, electronic andmagneto-transport properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shengqiang; Potzger, K.; Xu, Qingyu; Kuepper, K.; Talut, G.; Marko, D.; Mucklich, A.; Helm, M.; Fassbender, J.; Arenholz, E.; Schmidt, H.

    2009-08-21

    In this paper we show that spinel ferrite nanocrystals (NiFe{sub 2}O{sub 4}, and CoFe{sub 2}O{sub 4}) can be texturally embedded inside a ZnO matrix by ion implantation and post-annealing. The two kinds of ferrites show different magnetic properties, e.g. coercivity and magnetization. Anomalous Hall effect and positive magnetoresistance have been observed. Our study suggests a ferrimagnet/semiconductor hybrid system for potential applications in magneto-electronics. This hybrid system can be tuned by selecting different transition metal ions (from Mn to Zn) to obtain various magnetic and electronic properties.

  12. Electronic, vibrational and related properties of group IV metal oxides by ab initio calculations

    International Nuclear Information System (INIS)

    Leite Alves, H.W.; Silva, C.C.; Lino, A.T.; Borges, P.D.; Scolfaro, L.M.R.; Silva, E.F. da

    2008-01-01

    We present our theoretical results for the structural, electronic, vibrational and optical properties of MO 2 (M = Sn, Zr, Hf and Ti) obtained by first-principles calculations. Relativistic effects are demonstrated to be important for a realistic description of the detailed structure of the electronic frequency-dependent dielectric function, as well as of the carrier effective masses. Based on our results, we found that the main contribution of the high values calculated for the oxides dielectric constants arises from the vibrational properties of these oxides, and the vibrational static dielectric constant values diminish with increasing pressure

  13. Unique Intramolecular Electronic Communications in Mono-ferrocenylpyrimidine Derivatives: Correlation between Redox Properties and Structural Nature

    International Nuclear Information System (INIS)

    Xiang, Debo; Noel, Jerome; Shao, Huibo; Dupas, Georges; Merbouh, Nabyl; Yu, Hua-Zhong

    2015-01-01

    Highlights: • Unique intramolecular electronic communications (electron withdrawing and π-bond delocalization effects) exist in the mono-ferrocenylpyrimidine derivatives. • The redox potential shift correlates the pyrimidine ring torsion angle with the extent of electron delocalization. • The correlation between redox properties and structural nature in mono-ferrocenylpyrimidine derivatives is evident. - Abstract: The correlation between redox properties and structural nature in a complete set of mono-ferrocenylpyrimidine derivatives (2-ferrocenylpyrimidine, 2-FcPy; 4-ferrocenylpyrimidine, 4-FcPy; 5-ferrocenylpyrimidine, 5-FcPy) was evaluated by investigating the intramolecular electronic communications. Both conventional electrochemical measurements in organic solvents and thin-film voltammetric studies of these compounds were carried out. It was discovered that their formal potentials are significantly different from each other, and shift negatively in the order of 4-FcPy > 5-FcPy > 2-FcPy. This result suggests that the intramolecular electronic communication is dictated by the delocalization effect of the π-bonding systems in 2-FcPy, and that the electron-withdrawing effect of the nitrogen atoms in the pyrimidine ring plays the key role in 4-FcPy and 5-FcPy. The single crystal X-ray structure analyis and Density Functional Theory (DFT) calculation provided additional evidence (e.g., different torsion angles between the cyclopentadienyl and pyrimidine rings) to support the observed correlation between the redox properties and structural nature

  14. Structural, Electronic, Magnetic, and Vibrational Properties of Graphene and Silicene: A First-Principles Perspective

    KAUST Repository

    Kaloni, Thaneshwor P.

    2013-11-01

    This thesis covers the structural, electronic, magnetic, and vibrational properties of graphene and silicene. In Chapter I, we will start with an introduction to graphene and silicene. In Chapter II, we will briefly discuss about the methodology (i. e. density functional theory)In Chapter III, we will introduce band gap opening in graphene either by introducing defects/doping or by creating superlattices with h-BN substrate. In Chapter IV, we will focus on the structural and electronic properties of K and Ge-intercalated graphene on SiC(0001). In addition, the enhancement of the superconducting transition temperature in Li-decorated graphene supported by h-BN substrate will be discussed. In Chapter V, we will discuss the vibrational properties of free-standing silicene. In addition, superlattices of silicene with h-BN as well as the phase transition in silicene by applying an external electric field will be discussed. The electronic and magnetic properties transition metal decorated silicene will be discussed, in particular the realization of the quantum anomalous Hall effect will be addressed. Furthermore, the structural, electronic, and magnetic properties of Mn decorated silicene supported by h-BN substrate will be discussed. The conclusion is included in Chapters VI. Finally, we will end with references and a list of publications for this thesis.

  15. Investigation of the Electronic Properties of Cadmium Zinc Telluride (CZT) Detectors using a Nuclear Microprobe

    International Nuclear Information System (INIS)

    BRUNETT, BRUCE A.; DOYLE, BARNEY L.; JAMES, RALPH B.; VIZKELETHY, GYORGY; WALSH, DAVID S.

    1999-01-01

    The electronic transport properties of Cadmium Zinc Telluride (CZT) determine the charge collection efficiency (i.e. the signal quality) of CZT detectors. These properties vary on both macroscopic and microscopic scale and depend on the presence of impurities and defects introduced during the crystal growth. Ion Beam Induced Charge Collection (IBICC) is a proven method to measure the charge collection efficiency. Using an ion microbeam, the charge collection efficiency can be mapped with submicron resolution, and the map of electronic properties (such as drift length) can be calculated from the measurement. A more sophisticated version of IBICC, the Time Resolved IBICC (TRIBICC) allows them to determine the mobility and the life time of the charge carriers by recording and analyzing the transient waveform of the detector signal. Furthermore, lateral IBICC and TRIBICC can provide information how the charge collection efficiency depends on the depth where the charge carriers are generated. This allows one to deduce information on the distribution of the electric field and transport properties of the charge carriers along the detector axis. IBICC and TRIBICC were used at the Sandia microbeam facility to image electronic properties of several CZT detectors. From the lateral TRIBICC measurement the electron and hole drift length profiles were calculated

  16. Contribution of Brazil nut shell fiber and electron-beam irradiation in thermomechanical properties of HDPE

    International Nuclear Information System (INIS)

    Polato, Pamella; Lorusso, Leandro Alex; Souza, Clecia de Moura; Moura, Esperidiana Augusta Barretos de; Chinellato, Anne; Rosa, Ricardo de

    2010-01-01

    In the present work, the influence of electron-beam irradiation on thermo-mechanical properties of HDPE and HDPE/Brazil nut shell fiber composite was investigated. The materials were irradiated at radiation dose 50 kGy using a 1.5 MeV electron beam accelerator, at room temperature in presence of air. The irradiated and non-irradiated samples were submitted to thermo-mechanical tests and the correlation between their properties was discussed. The results showed that the incorporation of Brazil nut shell fiber represented a significant gain (p < 0,05) in tensile strength at break, flexural strength, flexural module, Vicat softening temperature and heat distortion temperature (HDT) properties of the HDPE. In addition, the irradiated HDPE/Brazil nut shell fiber composite presented a significant increase (p < 0.05) in this properties compared with irradiated HDPE. (author)

  17. Electronic and magnetic properties of digitally Ti doped InP: A first principles study

    International Nuclear Information System (INIS)

    Rahman, Gul; Cho, Sunglae; Hong, Soon Cheol

    2008-01-01

    Using the full-potential linearized augmented plane wave method within the generalized gradient approximation, we study the electronic and the magnetic properties of digitally Ti doped InP. It is quite interesting that digitally Ti-doped InP system shows half metallic ferromagnetism even though both bulk zinc blende TiP and InP are paramagnetic. We also investigate the electronic and the magnetic properties as a function of spacer layer thickness. Their properties such as exchange coupling constant and atomic projected density of states are more or less independent of the InP thickness. Spin density contour maps indicate that the spin-polarization is confined within the TiP plane. The system may show a highly anisotropic property in spin-polarized transport. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. A computational study of the electronic properties of one-dimensional armchair phosphorene nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Sheng; Zhu, Hao; Eshun, Kwesi; Arab, Abbas; Badwan, Ahmad; Li, Qiliang [Department of Electrical and Computer Engineering, George Mason University, Fairfax, Virginia 22033 (United States)

    2015-10-28

    We have performed a comprehensive first-principle computational study of the electronic properties of one-dimensional phosphorene nanotubes (PNTs), and the strain effect on the mechanical and electrical properties of PNTs, including the elastic modulus, energy bandstructure, and carrier effective mass. The study has demonstrated that the armchair PNTs have semiconducting properties along the axial direction and the carrier mobility can be significantly improved by compressive strain. The hole mobility increases from 40.7 cm{sup 2}/V s to 197.0 cm{sup 2}/V s as the compressive strain increases to −5% at room temperature. The investigations of size effect on armchair PNTs indicated that the conductance increases significantly as the increasing diameter. Overall, this study indicated that the PNTs have very attractive electronic properties for future application in nanomaterials and devices.

  19. Electronic band structure and optical properties of antimony selenide under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Abhijit, B.K.; Jayaraman, Aditya; Molli, Muralikrishna, E-mail: muralikrishnamolli@sssihl.edu.in [Department of Physics, Sri Sathya Sai Institute of Higher Learning, Prasanthinilayam, 515 134 (India)

    2016-05-23

    In this work we present the optical properties of Antimony Selenide (Sb{sub 2}Se{sub 3}) under ambient conditions and under pressure of 9.2 GPa obtained using first principles calculations. We investigated the electronic band structure using the FP-LAPW method within the sphere of the density functional theory. Optical properties like refractive index, absorption coefficient and optical conductivity are calculated using the WIEN2k code.

  20. Tunable electronic transport properties of silicon-fullerene-linked nanowires: Semiconductor, conducting wire, and tunnel diode

    OpenAIRE

    Nishio, Kengo; Ozaki, Taisuke; Morishita, Tetsuya; Mikami, Masuhiro

    2010-01-01

    We explore the possibility of controllable tuning of the electronic transport properties of silicon-fullerene-linked nanowires by encapsulating guest atoms into their cages. Our first-principles calculations demonstrate that the guest-free nanowires are semiconductors, and do not conduct electricity. The iodine or sodium doping improves the transport properties, and makes the nanowires metallic. In the junctions of I-doped and Na-doped NWs, the current travels through the boundary by quantum ...

  1. Phosphorene Oxide: Stability and electronic properties of a novel 2D material

    OpenAIRE

    Wang, Gaoxue; Pandey, Ravindra; Karna, Shashi P.

    2014-01-01

    Phosphorene, the monolayer form of the (black) phosphorus, was recently exfoliated from its bulk counterpart. Phosphorene oxide, by analogy to graphene oxide, is expected to have novel chemical and electronic properties, and may provide an alternative route to synthesis of phosphorene. In this letter, we investigate physical and chemical properties of the phosphorene oxide including its formation by the oxygen adsorption on the bare phosphorene. Analysis of the phonon dispersion curves finds ...

  2. Characterization of the Structural, Mechanical, and Electronic Properties of Fullerene Mixtures: A Molecular Simulations Description

    KAUST Repository

    Tummala, Naga Rajesh

    2017-10-06

    We investigate mixtures of fullerenes and fullerene derivatives, the most commonly used electron accepting materials in organic solar cells, by using a combination of molecular dynamics and density functional theory methods. Our goal is to describe how mixing affects the molecular packing, mechanical properties, and electronic parameters (site energy disorder, electronic couplings) of interest for solar-cell applications. Specifically, we consider mixtures of: (i) C60 and C70; (ii) C60, C70, and C84, and (iii) PC61BM and PC71BM.

  3. Ab initio calculation of the electronic and optical properties of solid pentacene

    International Nuclear Information System (INIS)

    Tiago, Murilo L.; Northrup, John E.; Louie, Steve G.

    2002-01-01

    The optical and electronic properties of crystalline pentacene are studied, using a first-principles Green's-function approach. The quasiparticle energies are calculated within the GW approximation and the electron-hole excitations are computed by solving the Bethe-Salpeter equation. We investigate the role of polymorphism on the electronic energy gap and linear optical spectrum by studying two different crystalline phases: the solution-phase structure and the vapor-phase structure. charge-transfer excitons are found to dominate the optical spectrum. Excitons with sizable binding energies are predicted for both phases

  4. Calculation of dynamic and electronic properties of perfect and defect crystals by semiempirical quantum mechanical methods

    International Nuclear Information System (INIS)

    Zunger, A.

    1975-07-01

    Semiempirical all-valence-electron LCAO methods, that were previously used to study the electronic structure of molecules are applied to three problems in solid state physics: the electronic band structure of covalent crystals, point defect problems in solids and lattice dynamical study of molecular crystals. Calculation methods for the electronic band structure of regular solids are introduced and problems regarding the computation of the density matrix in solids are discussed. Three models for treating the electronic eigenvalue problem in the solid, within the proposed calculation schemes, are discussed and the proposed models and calculation schemes are applied to the calculation of the electronic structure of several solids belonging to different crystal types. The calculation models also describe electronic properties of deep defects in covalent insulating crystals. The possible usefulness of the semieipirical LCAO methods in determining the first order intermolecular interaction potential in solids and an improved model for treating the lattice dynamics and related thermodynamical properties of molecular solids are presented. The improved lattice dynamical is used to compute phonon dispersion curves, phonon density of states, stable unit cell structure, lattice heat capacity and thermal crystal parameters, in α and γ-N 2 crystals, using the N 2 -N 2 intermolecular interaction potential that has been computed from the semiempirical LCAO methods. (B.G.)

  5. State-specific transport properties of electronically excited Ar and C

    Science.gov (United States)

    Istomin, V. A.; Kustova, E. V.

    2018-05-01

    In the present study, a theoretical model of state-resolved transport properties in electronically excited atomic species developed earlier is applied to argon and carbon atomic species. It is shown that for Ar and C, similarly to the case of atomic nitrogen and oxygen, the Slater-like models can be applied to calculate diameters of electronically excited atoms. Using the Slater-like model it is shown that for half-filled N (2 px1py1pz1) and full-filled Ar (3 px2py2pz2) electronic shells the growth of atomic radius goes slowly compared to C (2 px1py1) and O (2 px2py1pz1). The effect of collision diameters on the transport properties of Ar and C is evaluated. The influence of accounted number of electronic levels on the transport coefficients is examined for the case of Boltzmann distributions over electronic energy levels. It is emphasized that in the temperature range 1000-14000 K, for Boltzmann-like distributions over electronic states the number of accounted electronic levels do not influence the transport coefficients. Contrary to this, for higher temperatures T > 14000 K this effect becomes of importance, especially for argon.

  6. Metallurgical Mechanisms Controlling Mechanical Properties of Aluminum Alloy 2219 Produced By Electron Beam Freeform Fabrication

    Science.gov (United States)

    Domack, Marcia S.; Taminger, Karen M. B.; Begley, Matthew

    2006-01-01

    The electron beam freeform fabrication (EBF3) layer-additive manufacturing process has been developed to directly fabricate complex geometry components. EBF3 introduces metal wire into a molten pool created on the surface of a substrate by a focused electron beam. Part geometry is achieved by translating the substrate with respect to the beam to build the part one layer at a time. Tensile properties have been demonstrated for electron beam deposited aluminum and titanium alloys that are comparable to wrought products, although the microstructures of the deposits exhibit features more typical of cast material. Understanding the metallurgical mechanisms controlling mechanical properties is essential to maximizing application of the EBF3 process. In the current study, mechanical properties and resulting microstructures were examined for aluminum alloy 2219 fabricated over a range of EBF3 process variables. Material performance was evaluated based on tensile properties and results were compared with properties of Al 2219 wrought products. Unique microstructures were observed within the deposited layers and at interlayer boundaries, which varied within the deposit height due to microstructural evolution associated with the complex thermal history experienced during subsequent layer deposition. Microstructures exhibited irregularly shaped grains, typically with interior dendritic structures, which were described based on overall grain size, morphology, distribution, and dendrite spacing, and were correlated with deposition parameters. Fracture features were compared with microstructural elements to define fracture paths and aid in definition of basic processing-microstructure-property correlations.

  7. Incorporation of digestate selectively affects physical, chemical and biochemical properties along with CO2 emissions in two contrasting agricultural soils in the Mediterranean area.

    Science.gov (United States)

    Badagliacca, Giuseppe; Petrovičová, Beatrix; Zumbo, Antonino; Romeo, Maurizio; Gullì, Tommaso; Martire, Luigi; Monti, Michele; Gelsomino, Antonio

    2017-04-01

    Soil incorporation of digestate represents a common practice to dispose the solid residues from biogas producing plants. Although the digestate constitutes a residual biomass rich in partially decomposed organic matter and nutrients, whose content is often highly variable and unbalanced, its potential fertilizer value can vary considerably depending on the recipient soil properties. The aim of the work was to assess short-term changes in the fertility status of two contrasting agricultural soils in Southern Italy (Calabria), olive grove on a clay acid soil (Typic Hapludalfs) and citrus grove on a sandy loam slightly calcareous soil (Typic Xerofluvents), respectively located along the Tyrrhenian or the Ionian coast. An amount of 30 t ha-1 digestate was incorporated into the soil by ploughing. Unamended tilled soil was used as control. The following soil physical, chemical and biochemical variables were monitored during the experimental period: aggregate stability, pH, electrical conductivity, organic C, total N, Olsen-P, N-NH4+, N-NO3-, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and the mineralization quotient (qM). Moreover, in the olive grove soil CO2 emissions have been continuously measured at field scale for 5 months after digestate incorporation. Digestate application in both site exerted a significant positive effect on soil aggregate stability with a greater increase in clay than in sandy loam soil. Over the experimental period, digestate considerably affected the nutrient availability, namely Olsen-P, N-NH4+, N-NO3-, along with the electrical conductivity. The soil type increased significantly the soil N-NH4+ content, which was always higher in the olive than in citrus grove soil. N-NO3- content was markedly increased soon after the organic amendment, followed by a seasonal decline more evident in the sandy loam soil. Moreover, soil properties as CaCO3 content and the pH selectively affected the Olsen-P dynamics. No appreciable

  8. Effects of deformation on the electronic properties of B-C-N nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Azevedo, S., E-mail: sazevedo@fisica.ufpb.br [Departamento de Fisica, Universidade Federal da Paraiba, Caixa Postal 5008, 58059-900 Joao Pessoa-PB (Brazil); Rosas, A. [Departamento de Fisica, Universidade Federal da Paraiba, Caixa Postal 5008, 58059-900 Joao Pessoa-PB (Brazil); Machado, M. [Departamento de Fisica, Universidade Federal de Pelotas, Caixa Postal 354, 96010-900 Pelotas-RS (Brazil); Kaschny, J.R. [Instituto Federal da Bahia-Campus Vitoria da Conquista, Av. Amazonas 3150, 45030-220 Vitoria da Conquista-BA (Brazil); Chacham, H. [Departamento de Fisica, ICEX, Universidade Federal de Minas Gerais, Caixa Postal 702, 30123-970 Belo Horizonte-MG (Brazil)

    2013-01-15

    We apply first-principles methods, using density functional theory, to investigate the effects of flattening deformation on the electronic properties of BC{sub 2}N and C-doped BNNTs. Four different types of BC{sub 2}N structures are considered. Two of them are semiconductors, and the radial compression produces a significant reduction of the energy band gap. The other two types of structures are metallic, and the effect of radial compression is quite distinct. For one of them it is found the opening of a small band gap, and for the other one no changes are observed. For C-doped tubes, it is also found that the electronic properties undergo significant modifications when subjected to radial compression. - Graphical Abstract: We apply first-principles methods, using density functional theory, to investigate the effects of flattening deformation on the electronic properties of BC{sub 2}N and C-doped BNNTs. Four different types of BC{sub 2}N structures are considered. Two of them are semiconductors, and the radial compression produces a significant reduction of the energy band gap. The other two types of structures are metallic, and the effect of radial compression is quite distinct. For one of them it is found the opening of a small band gap, and for the other one no changes are observed. For C-doped tubes, it is also found that the electronic properties undergo significant modifications when subjected to radial compression. Highlights: Black-Right-Pointing-Pointer We investigated electronic properties of flattened BC{sub 2}N nanotubes. Black-Right-Pointing-Pointer The electronic states depend strongly on compression. Black-Right-Pointing-Pointer It is studied flattened BN nanotubes doped with a carbon atom. Black-Right-Pointing-Pointer The flattened C-doped structures, presents a significant reduction of the gap.

  9. The electronic and optical properties of warm dense nitrous oxide using quantum molecular dynamics simulations

    International Nuclear Information System (INIS)

    Zhang Yujuan; Wang Cong; Zhang Ping

    2012-01-01

    First-principles molecular-dynamics simulations based on density-functional theory have been used to study the electronic and optical properties of fluid nitrous oxide under extreme conditions. Systematic descriptions of pair-correlation function, atomic structure, and the charge density distribution are used to investigate the dissociation of fluid nitrous oxide. The electrical and optical properties are derived from the Kubo-Greenwood formula. It is found that the nonmetal-metal transition for fluid nitrous oxide can be directly associated to the dissociation and has significant influence on the optical properties of the fluid.

  10. Physical properties of LDPE/ethylene-1-butene copolymer film irradiated by electron beam

    International Nuclear Information System (INIS)

    Kim, Jeong Il; Nho, Young Chang

    2004-01-01

    In this study, ethylene-1-butene copolymer (EBP) was blended with LDPE to improve the mechanical properties as the packaging materials. After they were irradiated by electron beam, their physical properties such as tensile strength, elongation, modulus, peel strength, DSC, DMA were examined. The results showed that the addition of EBP to LDPE exerted significant effects on the mechanical properties such as the tensile strength and peel strength. The addition of EBP led to a maximum increase in peel strength of ∼430%. The addition of 10 - 25 w% EBP in LDPE was sufficient to enhance the peel strength significantly. (author)

  11. Electronic and optical properties of AgAlO{sub 2}: A first-principles study

    Energy Technology Data Exchange (ETDEWEB)

    Bhamu, K.C., E-mail: kcbhamu85@gmail.com; Priolkar, K.R.

    2017-04-01

    In this paper, we present electronic and optical properties of silver-based delafossite compound AgAlO{sub 2} (AAO). For the electronic properties, we have computed band structure and density of states. The origin of band structure is elucidated in terms of density of states. A significant contribution in band structure comes from Ag-4d and O-2p states around the Fermi level. The estimated band gap shows the indirect semiconducting nature of AAO having the band gap value of 2.34 eV. For the optical properties, we have calculated frequency dependent dielectric functions. The peaks in the imaginary component of dielectric function are explained by electronic transitions in the dispersion relation. Our computed results are in agreement with those available in the literature. The wide band gap and hence transparency for the UV and visible incident light photons makes AAO a precious material for transparent electronics. - Highlights: • Applied different-different types of exchange-correlations and potentials. • Becke–Johnson with Hubbard potential (BJ + U) is better for 2H-AgAlO{sub 2}. • Band gap is in reasonable agreement with experimentally reported. • Origin of energy bands is elucidated in terms of density of states. • 2H-AgAlO{sub 2} is a promising candidate for transparent electronics.

  12. Electronic and optical properties of AgAlO_2: A first-principles study

    International Nuclear Information System (INIS)

    Bhamu, K.C.; Priolkar, K.R.

    2017-01-01

    In this paper, we present electronic and optical properties of silver-based delafossite compound AgAlO_2 (AAO). For the electronic properties, we have computed band structure and density of states. The origin of band structure is elucidated in terms of density of states. A significant contribution in band structure comes from Ag-4d and O-2p states around the Fermi level. The estimated band gap shows the indirect semiconducting nature of AAO having the band gap value of 2.34 eV. For the optical properties, we have calculated frequency dependent dielectric functions. The peaks in the imaginary component of dielectric function are explained by electronic transitions in the dispersion relation. Our computed results are in agreement with those available in the literature. The wide band gap and hence transparency for the UV and visible incident light photons makes AAO a precious material for transparent electronics. - Highlights: • Applied different-different types of exchange-correlations and potentials. • Becke–Johnson with Hubbard potential (BJ + U) is better for 2H-AgAlO_2. • Band gap is in reasonable agreement with experimentally reported. • Origin of energy bands is elucidated in terms of density of states. • 2H-AgAlO_2 is a promising candidate for transparent electronics.

  13. Measuring the Electronic Properties of DNA-Specific Schottky Diodes Towards Detecting and Identifying Basidiomycetes DNA

    Science.gov (United States)

    Periasamy, Vengadesh; Rizan, Nastaran; Al-Ta’ii, Hassan Maktuff Jaber; Tan, Yee Shin; Tajuddin, Hairul Annuar; Iwamoto, Mitsumasa

    2016-01-01

    The discovery of semiconducting behavior of deoxyribonucleic acid (DNA) has resulted in a large number of literatures in the study of DNA electronics. Sequence-specific electronic response provides a platform towards understanding charge transfer mechanism and therefore the electronic properties of DNA. It is possible to utilize these characteristic properties to identify/detect DNA. In this current work, we demonstrate a novel method of DNA-based identification of basidiomycetes using current-voltage (I-V) profiles obtained from DNA-specific Schottky barrier diodes. Electronic properties such as ideality factor, barrier height, shunt resistance, series resistance, turn-on voltage, knee-voltage, breakdown voltage and breakdown current were calculated and used to quantify the identification process as compared to morphological and molecular characterization techniques. The use of these techniques is necessary in order to study biodiversity, but sometimes it can be misleading and unreliable and is not sufficiently useful for the identification of fungi genera. Many of these methods have failed when it comes to identification of closely related species of certain genus like Pleurotus. Our electronics profiles, both in the negative and positive bias regions were however found to be highly characteristic according to the base-pair sequences. We believe that this simple, low-cost and practical method could be useful towards identifying and detecting DNA in biotechnology and pathology. PMID:27435636

  14. Properties of commercial PVC-films with respect to electron dosimetry

    International Nuclear Information System (INIS)

    Miller, A.; Liqing, X.

    1985-05-01

    The properties of three commercially available polyvinyl chloride (PVC) film supplies and one made without additives were tested with respects to their application as routine dose monitors at electron accelerators. Dose fractionation was found to increase the response and the post-irradiation heat treatment was very critical for some of the films. (author)

  15. Electronic and optical properties of new multifunctional materials via half-substituted hematite: First principles calculations

    KAUST Repository

    Yang, Hua; Mi, Wenbo; Bai, Haili; Cheng, Yingchun

    2012-01-01

    Electronic structure and optical properties of α-FeMO 3 systems (M = Sc, Ti, V, Cr, Cu, Cd or In) have been investigated using first principles calculations. All of the FeMO 3 systems have a large net magnetic moment. The ground state of pure α-Fe 2

  16. Electron beam induced modifications in flexible biaxially oriented polyethylene terephthalate sheets: Improved mechanical and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhary, N. [Accelerator & Pulse Power Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India); Koiry, S.P. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India); Singh, A., E-mail: asb_barc@yahoo.com [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India); Tillu, A.R. [Accelerator & Pulse Power Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India); Jha, P.; Samanta, S.; Debnath, A.K. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India); Aswal, D.K., E-mail: dkaswal@yahoo.com [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India); Mondal, R.K. [Radiation Technology Development Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India); Acharya, S.; Mittal, K.C. [Accelerator & Pulse Power Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India)

    2017-03-01

    In the present work, we have studied the effects of electron beam irradiation (with dose ranging from 2 to 32 kGy) on mechanical and electrical properties of biaxially oriented polyethylene terephthalate (BOPET) sheets. The sol-gel analysis, Fourier transformation infra-red (FTIR), X-ray photoelectron spectroscopy (XPS) characterizations of the irradiated BOPET sheets suggest partial cross-linking of PET chains through the diethylene glycol (DEG). The mechanical properties of BOPET, such as, tensile strength, Young's modulus and electrical resistivity shows improvement with increasing dose and saturate for doses >10 kGy. The improved mechanical properties and high electrical resistivity of electron beam modified BOPET sheets may have additional advantages in applications, such as, packaging materials for food irradiation, medical product sterilization and electronic industries. - Graphical abstract: Irradiation of BOPET by electron beam leads to the formation of diethylene glycol that crosslink's the PET chains, resulting in improved mechanical properties and enhanced electrical resistivity. - Highlights: • BOPET exhibit improved tensile strength/Young's modulus after e-beam exposure. • Electrical resistivity of BOPET increases after e-beam exposure. • Cross-linking of PET chains through diethylene glycol was observed after e-beam exposure.

  17. First principles results of structural and electronic properties of ZnS

    Indian Academy of Sciences (India)

    We present results of the study of ZnS (1 ≤ ≤ 9) clusters, using the density functional formalism and projector augmented wave method within the generalized gradient approximation. Along with the structural and electronic properties, nature of bonding and overall stability of clusters has been studied.

  18. Conformational, IR spectroscopic and electronic properties of conium alkaloids and their adducts with C60 fullerene

    Science.gov (United States)

    Zabolotnyi, M. A.; Prylutskyy, Yu I.; Poluyan, N. A.; Evstigneev, M. P.; Dovbeshko, G. I.

    2016-08-01

    Conformational, IR spectroscopic and electronic properties of the components of Conium alkaloids (Conium maculatum) in aqueous environment were determined by model calculations and experiment. With the help of FT-IR spectroscopy the possibility of formation of an adduct between γ-coniceine alkaloid and C60 fullerene was demonstrated, which is important for further application of conium analogues in biomedical purposes.

  19. Influence of electron beam irradiation on the impact properties of polystyrene/EPDM rubber blends

    NARCIS (Netherlands)

    Gisbergen, van J.G.M.; Sanden, van der M.C.M.; Haan, de J.W.; Ven, van de L.J.M.; Lemstra, P.J.

    1991-01-01

    The influence of electron beam (EB) irradiation on the impact properties of compatibilized polystyrene/ethylene-propylene-diene-monomer (PSIEPDM) blends was studied. The change in impact value upon irradiation proved to be strongly dependent on the type of compatibilizer used. Using a

  20. Electronic Structure and Optical Properties Of EuIn2P2

    KAUST Repository

    Singh, Nirpendra; Schwingenschlö gl, Udo; Rhee, J. Y.

    2011-01-01

    The electronic structures and, optical and magneto‐optical properties of a newly found Zintl compound EuIn2P2 have been investigated within the density‐functional theory using the highly precise full‐potential linear‐augmented‐plane‐wave method