WorldWideScience

Sample records for junction degradation effects

  1. Reverse degradation of nickel graphene junction by hydrogen annealing

    CERN Document Server

    Zhang, Zhenjun; Agnihotri, Pratik; Lee, Ji Ung; Lloyd, Jim R

    2016-01-01

    Metal contacts are fundamental building components for graphene based electronic devices and their properties are greatly influenced by interface quality during device fabrication, leading to resistance variation. Here we show that nickel graphene junction degrades after air exposure, due to interfacial oxidation, thus creating a tunneling barrier. Most importantly, we demonstrate that hydrogen annealing at moderate temperature (300 0C) is an effective technique to reverse the degradation.

  2. Reverse degradation of nickel graphene junction by hydrogen annealing

    Directory of Open Access Journals (Sweden)

    Zhenjun Zhang

    2016-02-01

    Full Text Available Metal contacts are fundamental building components for graphene based electronic devices and their properties are greatly influenced by interface quality during device fabrication, leading to resistance variation. Here we show that nickel graphene junction degrades after air exposure, due to interfacial oxidation, thus creating a tunneling barrier. Most importantly, we demonstrate that hydrogen annealing at moderate temperature (300 0C is an effective technique to reverse the degradation.

  3. Reverse degradation of nickel graphene junction by hydrogen annealing

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhenjun; Yang, Fan; Agnihotri, Pratik; Lee, Ji Ung; Lloyd, J. R., E-mail: jlloyd@sunypoly.edu [College of Nanoscience and Engineering, SUNY Polytechnic Institute, Albany, NY USA 12203 (United States)

    2016-02-15

    Metal contacts are fundamental building components for graphene based electronic devices and their properties are greatly influenced by interface quality during device fabrication, leading to resistance variation. Here we show that nickel graphene junction degrades after air exposure, due to interfacial oxidation, thus creating a tunneling barrier. Most importantly, we demonstrate that hydrogen annealing at moderate temperature (300 {sup 0}C) is an effective technique to reverse the degradation.

  4. Degradation of Junction Parameters of an Electrically Stressed NPN Bipolar Transistor

    OpenAIRE

    N. Toufik; F. PéLanchon; P. Mialhe

    2001-01-01

    The effect of an electrical ageing on npn bipolar transistor has been studied. The current gain decreases substantially and the electrical properties are discussed. The emitter-base junction parameters are degraded during the electrical stress experiments. Both the amplitude and the rate of this degradation depend on the stress duration. The evaluation of these parameters allows to discuss hot carrier degradation process, to estimate the stress magnitude and to control the device.

  5. Seebeck effect in molecular junctions

    Science.gov (United States)

    Zimbovskaya, Natalya A.

    2016-05-01

    Advances in the fabrication and characterization of nanoscale systems presently allow for a better understanding of their thermoelectric properties. As is known, the building blocks of thermoelectricity are the Peltier and Seebeck effects. In the present work we review results of theoretical studies of the Seebeck effect in single-molecule junctions and similar systems. The behavior of thermovoltage and thermopower in these systems is controlled by several factors including the geometry of molecular bridges, the characteristics of contacts between the bridge and the electrodes, the strength of the Coulomb interactions between electrons on the bridge, and of electron-phonon interactions. We describe the impact of these factors on the thermopower. Also, we discuss a nonlinear Seebeck effect in molecular junctions.

  6. Joint laminate degradation assessed by reflected ultrasound from the cartilage surface and osteochondral junction

    Energy Technology Data Exchange (ETDEWEB)

    Brown, C P; Crawford, R W; Oloyede, A [School of Engineering Systems, IHBI, QUT, Brisbane (Australia); Hughes, S W [School of Physical and Chemical Sciences, QUT, Brisbane (Australia)], E-mail: k.oloyede@qut.edu.au

    2008-08-07

    The ability to quantify and qualify the progression of joint degeneration is becoming increasingly important in surgery. This paper examines the patterns of relative ultrasound reflection from normal, artificially and naturally degraded cartilage-on-bone, particularly investigating the potential of the ratio of reflection coefficients from the surface and osteochondral junction in distinguishing normal from osteoarthritic tissue. To this end, the reflection coefficients from the articular surface and osteochondral junction of normal cartilage-on-bone samples were calculated and compared to samples after the removal of proteoglycans, disruption of the collagen meshwork, delipidization of the articular surface and mechanical abrasion. Our results show that the large variation across normal and degraded joint samples negates the use of an isolated bone reflection measurement and to a lesser extent, an isolated surface reflection. The relative surface to bone reflections, calculated as a ratio of reflection coefficients, provided a more consistent and statistically significant (p < 0.001) method for distinguishing each type of degradation, especially osteoarthritic degradation, and due to the complementary relationship between surface and bone reflections was found to be an effective method for distinguishing degraded from normal tissue in the osteoarthritic joint, independent of the site of initiation of the osteoarthritic process.

  7. Joint laminate degradation assessed by reflected ultrasound from the cartilage surface and osteochondral junction

    Science.gov (United States)

    Brown, C. P.; Hughes, S. W.; Crawford, R. W.; Oloyede, A.

    2008-08-01

    The ability to quantify and qualify the progression of joint degeneration is becoming increasingly important in surgery. This paper examines the patterns of relative ultrasound reflection from normal, artificially and naturally degraded cartilage-on-bone, particularly investigating the potential of the ratio of reflection coefficients from the surface and osteochondral junction in distinguishing normal from osteoarthritic tissue. To this end, the reflection coefficients from the articular surface and osteochondral junction of normal cartilage-on-bone samples were calculated and compared to samples after the removal of proteoglycans, disruption of the collagen meshwork, delipidization of the articular surface and mechanical abrasion. Our results show that the large variation across normal and degraded joint samples negates the use of an isolated bone reflection measurement and to a lesser extent, an isolated surface reflection. The relative surface to bone reflections, calculated as a ratio of reflection coefficients, provided a more consistent and statistically significant (p < 0.001) method for distinguishing each type of degradation, especially osteoarthritic degradation, and due to the complementary relationship between surface and bone reflections was found to be an effective method for distinguishing degraded from normal tissue in the osteoarthritic joint, independent of the site of initiation of the osteoarthritic process.

  8. Morphological and Chemical Analysis Of Degraded Single Junction Amorphous Silicon Module.

    Science.gov (United States)

    Osayemwenre, Gilbert; Meyer, Edson; Mamphweli, Sampson

    2017-01-01

    Photovoltaic solar modules have different defects and degradation characteristic modes. These defects/degradation modes normally heats up some regions in the PV module, depending on the degree and size of the localised heat or hot spot, the localized heat can rise above the temperature limit of the module thereby cause damage to the structural orientation. The presence of severe defect and degradation correlates with high temperature gradients that usually results in morphological damage especially under outdoor conditions. The present study investigates the effect of defect/degradation on the surface morphology of the single junction amorphous silicon modules (a-Si:H) during outdoor deployment. The observed structural damage was analysed using scanning electron microscope (SEM) and energy dispersion X-ray (EDX) to ascertain the elemental composition. Results show huge discrepancies in the chemical composition constitute alone different regions. The presence of high concentration of carbon and oxygen was found in the affected region. The authors sincerely thank GMDRC University of Fort Hare for financial support. The authors also wish to thank Eskom for financing this project.

  9. Vitamin D3 regulates the formation and degradation of gap junctions in androgen-responsive human prostate cancer cells.

    Directory of Open Access Journals (Sweden)

    Linda Kelsey

    Full Text Available 1α-25(OH2 vitamin D3 (1-25D, an active hormonal form of Vitamin D3, is a well-known chemopreventive and pro-differentiating agent. It has been shown to inhibit the growth of several prostate cancer cell lines. Gap junctions, formed of proteins called connexins (Cx, are ensembles of cell-cell channels, which permit the exchange of small growth regulatory molecules between adjoining cells. Cell-cell communication mediated by gap junctional channels is an important homeostatic control mechanism for regulating cell growth and differentiation. We have investigated the effect of 1-25D on the formation and degradation of gap junctions in an androgen-responsive prostate cancer cell line, LNCaP, which expresses retrovirally-introduced Cx32. Connexin32 is expressed by the luminal and well-differentiated cells of normal prostate and prostate tumors. Our results document that 1-25D enhances the expression of Cx32 and its subsequent assembly into gap junctions. Our results further show that 1-25D prevents androgen-regulated degradation of Cx32, post-translationally, independent of androgen receptor (AR-mediated signaling. Finally, our findings document that formation of gap junctions sensitizes Cx32-expressing LNCaP cells to the growth inhibitory effects of 1-25D and alters their morphology. These findings suggest that the growth-inhibitory effects of 1-25D in LNCaP cells may be related to its ability to modulate the assembly of Cx32 into gap junctions.

  10. High-energy electron induced gain degradation in bipolar junction transistors

    Energy Technology Data Exchange (ETDEWEB)

    Kulkarni, S.R. [Department of PG Studies in Physics, SBMJC, Jayanagar, Bangalore 560 011 (India)]. E-mail: srinivask24@hotmail.com; Ravindra, M. [Components Division, ICG, ISRO Satellite Centre, Airport Road, Bangalore 560 017 (India); Joshi, G.R. [Components Division, ICG, ISRO Satellite Centre, Airport Road, Bangalore 560 017 (India); Damle, R. [Department of Physics, Bangalore University, Bangalore 560 056 (India)]. E-mail: damleraju@yahoo.com

    2006-09-15

    This paper describes the effect of 8 MeV electron beam on the forward current gain of space borne commercial indigenous bipolar junction transistors 2N2219A (npn), 2N3019 (npn) and 2N2905A (pnp). The devices are exposed to 8 MeV electron in the biased condition. The collector characteristics and Gummel plots are obtained as a function of accumulated dose. An excess base current model as well as Messenger-Spratt equation have been used to account for the observed gain degradation. The results indicate that 8 MeV electrons of high dose rate induce gain degradation by increasing the base current as well as decrease in collector current. The current gain degradation appears to be predominantly due to displacement damage in the bulk of the transistor. Off-line measurements of the h {sub FE} of the irradiated transistors indicate that the displacement induced defect and recombination centers do not anneal even at 150 {sup o}C.

  11. Origin of the Degradation of Triple Junction Solar Cells at low Temperature

    Directory of Open Access Journals (Sweden)

    Park Seonyong

    2017-01-01

    Full Text Available The degradation of solar cells under irradiation by high energy particles (electrons, protons is the consequence of the introduction of defects trapping minority carriers, which are then not collected by the junction. However, at low temperature, defects located in the space charge region can also induce a tunneling current that results in an apparent decreases of the maximum power. The degradation produced by this tunneling current can depend on temperature, since the concentration of defects created by an irradiation is usually temperature dependent, and can be larger than the degradation associated with carrier recombination. For instance, as we shall see below, an irradiation with 1 MeV electrons at 120 K with a fluence of 3.0 × 1015 /cm2 induces a decrease of less than 10 % in the short-circuit current (Isc and open-circuit voltage (Voc of triple junction (TJ cells, but a decrease of about 40 % in the maximum power (Pmax, which implies that more than half of the total degradation of Pmax should be assigned to another loss mechanism, tunneling in this case. In this work, we demonstrate that this additional degradation must indeed be ascribed to a tunneling process and we investigate the variation of the tunneling current versus fluence induced by electron irradiation in TJ cells, in order to tentatively ascribe the tunneling components to specific sub-cells.

  12. Graphene junction field-effect transistor

    Science.gov (United States)

    Ou, Tzu-Min; Borsa, Tomoko; van Zeghbroeck, Bart

    2014-03-01

    We have demonstrated for the first time a novel graphene transistor gated by a graphene/semiconductor junction rather than an insulating gate. The transistor operates much like a semiconductor junction Field Effect Transistor (jFET) where the depletion layer charge in the semiconductor modulates the mobile charge in the channel. The channel in our case is the graphene rather than another semiconductor layer. An increased reverse bias of the graphene/n-silicon junction increases the positive charge in the depletion region and thereby reduces the total charge in the graphene. We fabricated individual graphene/silicon junctions as well as graphene jFETs (GjFETs) on n-type (4.5x1015 cm-3) silicon with Cr/Au electrodes and 3 μm gate length. As a control device, we also fabricated back-gated graphene MOSFETs using a 90nm SiO2 on a p-type silicon substrate (1019 cm-3) . The graphene was grown by APCVD on copper foil and transferred with PMMA onto the silicon substrate. The GjFET exhibited an on-off ratio of 3.75, an intrinsic graphene doping of 1.75x1012 cm-2, compared to 1.17x1013 cm-2 in the MOSFET, and reached the Dirac point at 13.5V. Characteristics of the junctions and transistors were measured as a function of temperature and in response to light. Experimental data and a comparison with simulations will be presented.

  13. Ischaemia-induced autophagy leads to degradation of gap junction protein connexin43 in cardiomyocytes.

    Science.gov (United States)

    Martins-Marques, Tania; Catarino, Steve; Zuzarte, Monica; Marques, Carla; Matafome, Paulo; Pereira, Paulo; Girão, Henrique

    2015-04-15

    GJIC (gap junction intercellular communication) between cardiomyocytes is essential for synchronous heart contraction and relies on Cx (connexin)-containing channels. Increased breakdown of Cx43 has been often associated with various cardiac diseases. However, the mechanisms whereby Cx43 is degraded in ischaemic heart remain unknown. The results obtained in the present study, using both HL-1 cells and organotypic heart cultures, show that simulated ischaemia induces degradation of Cx43 that can be prevented by chemical or genetic inhibitors of autophagy. Additionally, ischaemia-induced degradation of Cx43 results in GJIC impairment in HL-1 cells, which can be restored by autophagy inhibition. In cardiomyocytes, ubiquitin signals Cx43 for autophagic degradation, through the recruitment of the ubiquitin-binding proteins Eps15 (epidermal growth factor receptor substrate 15) and p62, that assist in Cx43 internalization and targeting to autophagic vesicles, via LC3 (light chain 3). Moreover, we establish that degradation of Cx43 in ischaemia or I/R (ischaemia/reperfusion) relies upon different molecular players. Indeed, degradation of Cx43 during early periods of ischaemia depends on AMPK (AMP-activated protein kinase), whereas in late periods of ischaemia and I/R Beclin 1 is required. In the Langendorff-perfused heart, Cx43 is dephosphorylated in ischaemia and degraded during I/R, where Cx43 degradation correlates with autophagy activation. In summary, the results of the present study provide new evidence regarding the molecular mechanisms whereby Cx43 is degraded in ischaemia, which may contribute to the development of new strategies that aim to preserve GJIC and cardiac function in ischaemic heart.

  14. Degradation of magnetic tunnel junctions with thin AlOx barrier

    Directory of Open Access Journals (Sweden)

    Tadashi Mihara, Yoshinari Kamakura, Masato Morifuji and Kenji Taniguchi

    2007-01-01

    Full Text Available The degradation of magnetic tunnel junctions (MTJs with AlOx barrier was experimentally investigated. Constant voltage stress (CVS measurement was carried out to monitor the time evolution of the conductance and tunneling magnetoresistance (TMR of MTJs. The gradual increase of the stress-induced leakage current (SILC was observed prior to the breakdown, following a power law function of stress time with an exponent of about 0.2–0.4, which is similar to the case of the ultrathin gate oxide films in MOSFETs. The measured TMR for SILC suggests that the spin-dependent current component would be involved in the early stage of degradation, while spin-independent conduction becomes dominant before the breakdown resulting in a decrease of TMR.

  15. Tunable Magnetic Proximity Effects in Graphene Junctions

    Science.gov (United States)

    Lazic, Predrag; Belashchenko, Kirill; Zutic, Igor

    2015-03-01

    The characteristic length of the magnetic proximity effects exceed the thickness of a graphene layer leading to an important, but typically overlooked, modifications of equilibrium and transport properties, as well as the implications for graphene spintronics. Using the first-principles studies that integrate a real space density functional theory (GPAW) with the state-of-the art boundary elements electrostatic code based on the Robin Hood method, we explore tunable electronic structure and magnetic proximity effects in the ferromagnet/insulator/graphene junctions. We show that the inclusion of a finite-size gate electrodes and van der Walls interaction lead to nontrivial effects that could also be important in other two-dimensional materials beyond graphene. Work supported by US ONR, NSF-DMR and Nebraska NSF MRSEC.

  16. Model of radiation-induced gain degradation of NPN bipolar junction transistor at different dose rates

    Science.gov (United States)

    Qifeng, Zhao; Yiqi, Zhuang; Junlin, Bao; Wei, Hu

    2015-06-01

    Ionizing-radiation-induced current gain degradation in NPN bipolar junction transistors is due to an increase in base current as a result of recombination at the surface of the device. A model is presented which identifies the physical mechanism responsible for current gain degradation. The increase in surface recombination velocity due to interface states results in an increase in base current. Besides, changing the surface potential along the base surface induced by the oxide-trapped charges can also lead to an increased base current. By combining the production mechanisms of oxide-trapped charges and interface states, this model can explain the fact that the current gain degradation is more severe at a low dose rate than at a high dose rate. The radiations were performed in a Co60 source up to a total dose of 70 krad(Si). The low dose rate was 0.1 rad(Si)/s and the high dose rate was 10 rad(Si)/s. The model accords well with the experimental results. Project supported by the National Natural Science Foundation of China (Nos. 61076101, 61204092).

  17. Seebeck effect in magnetic tunnel junctions.

    Science.gov (United States)

    Walter, Marvin; Walowski, Jakob; Zbarsky, Vladyslav; Münzenberg, Markus; Schäfers, Markus; Ebke, Daniel; Reiss, Günter; Thomas, Andy; Peretzki, Patrick; Seibt, Michael; Moodera, Jagadeesh S; Czerner, Michael; Bachmann, Michael; Heiliger, Christian

    2011-10-01

    Creating temperature gradients in magnetic nanostructures has resulted in a new research direction, that is, the combination of magneto- and thermoelectric effects. Here, we demonstrate the observation of one important effect of this class: the magneto-Seebeck effect. It is observed when a magnetic configuration changes the charge-based Seebeck coefficient. In particular, the Seebeck coefficient changes during the transition from a parallel to an antiparallel magnetic configuration in a tunnel junction. In this respect, it is the analogue to the tunnelling magnetoresistance. The Seebeck coefficients in parallel and antiparallel configurations are of the order of the voltages known from the charge-Seebeck effect. The size and sign of the effect can be controlled by the composition of the electrodes' atomic layers adjacent to the barrier and the temperature. The geometric centre of the electronic density of states relative to the Fermi level determines the size of the Seebeck effect. Experimentally, we realized 8.8% magneto-Seebeck effect, which results from a voltage change of about -8.7 μV K⁻¹ from the antiparallel to the parallel direction close to the predicted value of -12.1 μV K⁻¹. In contrast to the spin-Seebeck effect, it can be measured as a voltage change directly without conversion of a spin current.

  18. Autophagy enhances intestinal epithelial tight junction barrier function by targeting claudin-2 protein degradation.

    Science.gov (United States)

    Nighot, Prashant K; Hu, Chien-An Andy; Ma, Thomas Y

    2015-03-13

    Autophagy is an intracellular degradation pathway and is considered to be an essential cell survival mechanism. Defects in autophagy are implicated in many pathological processes, including inflammatory bowel disease. Among the innate defense mechanisms of intestinal mucosa, a defective tight junction (TJ) barrier has been postulated as a key pathogenic factor in the causation and progression of inflammatory bowel disease by allowing increased antigenic permeation. The cross-talk between autophagy and the TJ barrier has not yet been described. In this study, we present the novel finding that autophagy enhances TJ barrier function in Caco-2 intestinal epithelial cells. Nutrient starvation-induced autophagy significantly increased transepithelial electrical resistance and reduced the ratio of sodium/chloride paracellular permeability. Nutrient starvation reduced the paracellular permeability of small-sized urea but not larger molecules. The role of autophagy in the modulation of paracellular permeability was confirmed by pharmacological induction as well as pharmacological and genetic inhibition of autophagy. Consistent with the autophagy-induced reduction in paracellular permeability, a marked decrease in the level of the cation-selective, pore-forming TJ protein claudin-2 was observed after cell starvation. Starvation reduced the membrane presence of claudin-2 and increased its cytoplasmic, lysosomal localization. Therefore, our data show that autophagy selectively reduces epithelial TJ permeability of ions and small molecules by lysosomal degradation of the TJ protein claudin-2.

  19. Effect of Front-Side Silver Metallization on Underlying n+-p Junction in Multicrystalline Silicon Solar Cells: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, C. S.; Li, Z. G.; Moutinho, H. R.; Liang, L.; Ionkin, A.; Al-Jassim, M. M.

    2012-06-01

    We report on the effect of front-side Ag metallization on the underlying n+-p junction of multicrystalline Si solar cells. The junction quality beneath the contacts was investigated by characterizing the uniformities of the electrostatic potential and doping concentration across the junction, using scanning Kelvin probe force microscopy and scanning capacitance microscopy. We investigated cells with a commercial Ag paste (DuPont PV159) and fired at furnace setting temperatures of 800 degrees, 840 degrees, and 930 degrees C, which results in actual cell temperatures ~100 degrees C lower than the setting temperature and the three cells being under-, optimal-, and over-fired. We found that the uniformity of the junction beneath the Ag contact was significantly degraded by the over-firing, whereas the junction retained good uniformity with the optimal- and under-fire temperatures. Further, Ag crystallites with widely distributed sizes from <100 nm to several μm were found at the Ag/Si interface of the over-fired cell. Large crystallites were imaged as protrusions into Si deeper than the junction depth. However, the junction was not broken down; instead, it was reformed on the entire front of the crystallite/Si interface. We propose a mechanism of the junction-quality degradation, based on emitter Si melting at the temperature around the Ag-Si eutectic point during firing, and subsequent recrystallization with incorporation of impurities in the Ag paste and with formation of crystallographic defects during quenching.

  20. Temporal correlations and structural memory effects in break junction measurements

    DEFF Research Database (Denmark)

    Magyarkuti, A.; Lauritzen, Kasper Primdal; Balogh, Zoltan Imre

    2017-01-01

    that correlations between the opening and subsequent closing traces may indicate structural memory effects in atomic-sized metallic and molecular junctions. Applying these methods on measured and simulated gold metallic contacts as a test system, we show that the surface diffusion induced flattening of the broken......-molecule junctions, we demonstrate pronounced contact memory effects and recovery of the molecule for junctions breaking before atomic chains are formed. However, if chains are pulled the random relaxation of the chain and molecule after rupture prevents opening-closing correlations....

  1. An outdoor investigation of the absorption degradation of single-junction amorphous silicon photovoltaic module due to localized heat/hot spot formation

    Indian Academy of Sciences (India)

    Osayemwenre Gilbert O; Meyer Edson L; Mamphweli Sampson

    2016-04-01

    This paper investigates the absorbance degradation of single-junction amorphous silicon (a-Si:H) photovoltaic (PV) module, due to the presence of localized heat. The decrease in optical density is a huge challenge due to the long-term degradation of PV modules. The reduction in solar cell optical density causes a decline in its conversion efficiency. This decreases the photogenerating current, hence reduces the effective efficiency of the PV device. An infrared thermography was used for mapping the module temperature profile. Fourier transform infrared spectroscopy (FTIR) was used for the absorption characterization. The rationale behind the outdoor deployment was to deduce a practical effect of hot spot formation on the module’s absorption ability.The results show a direct correlation between localized heat and the absorption degradation.

  2. Vector spin modeling for magnetic tunnel junctions with voltage dependent effects

    Energy Technology Data Exchange (ETDEWEB)

    Manipatruni, Sasikanth, E-mail: sasikanth.manipatruni@intel.com; Nikonov, Dmitri E.; Young, Ian A. [Exploratory Integrated Circuits, Components Research, Intel Corp., Hillsboro, Oregon 97124 (United States)

    2014-05-07

    Integration and co-design of CMOS and spin transfer devices requires accurate vector spin conduction modeling of magnetic tunnel junction (MTJ) devices. A physically realistic model of the MTJ should comprehend the spin torque dynamics of nanomagnet interacting with an injected vector spin current and the voltage dependent spin torque. Vector spin modeling allows for calculation of 3 component spin currents and potentials along with the charge currents/potentials in non-collinear magnetic systems. Here, we show 4-component vector spin conduction modeling of magnetic tunnel junction devices coupled with spin transfer torque in the nanomagnet. Nanomagnet dynamics, voltage dependent spin transport, and thermal noise are comprehended in a self-consistent fashion. We show comparison of the model with experimental magnetoresistance (MR) of MTJs and voltage degradation of MR with voltage. Proposed model enables MTJ circuit design that comprehends voltage dependent spin torque effects, switching error rates, spin degradation, and back hopping effects.

  3. Efficient photocatalytic degradation of acid orange 7 on metal oxide p-n junction composites under visible light

    Science.gov (United States)

    Suk Jang, Jum; Gyu Kim, Hyun; Lee, Se-Hee

    2012-11-01

    MO(=CuO, Co3O4, NiO)/BiVO4 p-n junction composites were synthesized by urea-precipitation and wet impregnation method. The physicochemical and optical properties of the as-prepared materials were investigated by X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-visible diffuse reflectance spectra. The photocatalytic performance of the as-prepared materials was investigated for decomposition of azo dye, acid orange 7. The CuO/BiVO4 and Co3O4/BiVO4 p-n junction composite photocatalysts exhibited the higher photocatalytic degradation of acid orange 7 than those of BiVO4 and NiO/BiVO4 as-prepared samples under visible light irradiation. We also discussed the mechanism of enhanced photocatalytic activity of p-n junctioned composites based on their energy band structures.

  4. Nonequilibrium and proximity effects in superconductor-normal metal junctions

    Science.gov (United States)

    Kauppila, V. J.; Nguyen, H. Q.; Heikkilä, T. T.

    2013-08-01

    We study the consequences of nonequilibrium heating and inverse proximity effect in normal metal-insulator-superconductor-insulator-normal metal (NISIN) junctions with a simple quasi-one-dimensional model. We especially focus on observables and parameter regions that are of interest in the design of SINIS coolers with quasiparticle traps. We present numerical results calculated by solving the Usadel equation and also present analytical approximations in two limiting cases: a short junction with a non-negligible resistance in both ends and a long junction with a transparent contact at one end.

  5. Effect of surface losses on soliton propagation in Josephson junctions

    DEFF Research Database (Denmark)

    Davidson, A.; Pedersen, Niels Falsig; Pagano, S.

    1986-01-01

    We have explored numerically the effects on soliton propagation of a third order damping term in the modified sine-Gordon equation. In Josephson tunnel junctions such a term corresponds physically to quasiparticle losses within the metal electrodes of the junction. We find that this loss term pla...... the dominant role in determining the shape and stability of the soliton at high velocity. Applied Physics Letters is copyrighted by The American Institute of Physics.......We have explored numerically the effects on soliton propagation of a third order damping term in the modified sine-Gordon equation. In Josephson tunnel junctions such a term corresponds physically to quasiparticle losses within the metal electrodes of the junction. We find that this loss term plays...

  6. Neutron Radiation Effect On 2N2222 And NTE 123 NPN Silicon Bipolar Junction Transistors

    Science.gov (United States)

    Oo, Myo Min; Rashid, N. K. A. Md; Karim, J. Abdul; Zin, M. R. Mohamed; Hasbullah, N. F.

    2013-12-01

    This paper examines neutron radiation with PTS (Pneumatic Transfer System) effect on silicon NPN bipolar junction transistors (2N2222 and NTE 123) and analysis of the transistors in terms of electrical characterization such as current gain after neutron radiation. The key parameters are measured with Keithley 4200SCS. Experiment results show that the current gain degradation of the transistors is very sensitive to neutron radiation. The neutron radiation can cause displacement damage in the bulk layer of the transistor structure. The current degradation is believed to be governed by increasing recombination current between the base and emitter depletion region.

  7. Interfacial capacitance effects in magnetic tunneling junctions

    CERN Document Server

    Landry, G; Du, J; Xiao, J Q

    2001-01-01

    We have investigated the AC transport properties of magnetic tunnel junctions (MTJ) in order to characterize interfacial properties. One such property is interfacial charge accumulation, which leads to a voltage drop in the electrodes of the MTJ and the measured capacitance differing from the geometrical capacitance. Through measurement of capacitance spectra, we have extracted an interfacial capacitance of 16 mu F/cm sup 2 per interface and a screening length of 0.55 A for FeNi electrodes.

  8. Quantum-confined Stark effect in band-inverted junctions

    Science.gov (United States)

    Díaz-Fernández, A.; Domínguez-Adame, F.

    2017-09-01

    Topological phases of matter are often characterized by interface states, which were already known to occur at the boundary of a band-inverted junction in semiconductor heterostructures. In IV-VI compounds such interface states are properly described by a two-band model, predicting the appearance of a Dirac cone in single junctions. We study the quantum-confined Stark effect of interface states due to an electric field perpendicular to a band-inverted junction. We find a closed expression to obtain the interface dispersion relation at any field strength and show that the Dirac cone widens under an applied bias. Thus, the Fermi velocity can be substantially lowered even at moderate fields, paving the way for tunable band-engineered devices based on band-inverted junctions.

  9. Spin and charge thermopower effects in the ferromagnetic graphene junction

    Science.gov (United States)

    Vahedi, Javad; Barimani, Fattaneh

    2016-08-01

    Using wave function matching approach and employing the Landauer-Buttiker formula, a ferromagnetic graphene junction with temperature gradient across the system is studied. We calculate the thermally induced charge and spin current as well as the thermoelectric voltage (Seebeck effect) in the linear and nonlinear regimes. Our calculation revealed that due to the electron-hole symmetry, the charge Seebeck coefficient is, for an undoped magnetic graphene, an odd function of chemical potential while the spin Seebeck coefficient is an even function regardless of the temperature gradient and junction length. We have also found with an accurate tuning external parameter, namely, the exchange filed and gate voltage, the temperature gradient across the junction drives a pure spin current without accompanying the charge current. Another important characteristic of thermoelectric transport, thermally induced current in the nonlinear regime, is examined. It would be our main finding that with increasing thermal gradient applied to the junction the spin and charge thermovoltages decrease and even become zero for non zero temperature bias.

  10. Seebeck Effect in Magnetic Tunnel Junctions

    OpenAIRE

    Walter, Marvin; Walowski, Jakob; Zbarsky, Vladyslav; Münzenberg, Markus; Schäfers, Markus; Ebke, Daniel; Reiss, Günter; Thomas, Andy; Peretzki, Patrick; Seibt, Michael; Moodera, Jagadeesh S.; Czerner, Michael; Bachmann, Michael; Heiliger, Christian

    2011-01-01

    Creating temperature gradients in magnetic nanostructures has resulted in a new research direction, i.e., the combination of magneto- and thermoelectric effects. Here, we demonstrate the observation of one important effect of this class: the magneto-Seebeck effect. It is observed when a magnetic configuration changes the charge based Seebeck coefficient. In particular, the Seebeck coefficient changes during the transition from a parallel to an antiparallel magnetic configuration in a tunnel j...

  11. DEGRADATION OF SHAPE MEMORY EFFECT

    OpenAIRE

    VanderMeer, R.

    1982-01-01

    An important parameter for deciding whether or not a SME alloy is suitable for practical applications is the magnitude of the strain reversa1 accompanying martensite reversion. This research is concerned with elucidating metallurgical factors that cause degradation of this heat-activated recovery strain, ER. After explaining what is meant by degradation, two manifestations of degradation recently identified in near-monotectoid uranium-niobium alloys will be described. The first was associated...

  12. Ureteropelvic junction obstruction: the effect of pyeloplasty on renal function

    Energy Technology Data Exchange (ETDEWEB)

    Dowling, K.J.; Harmon, E.P.; Ortenberg, J.; Polanco, E.; Evans, B.B.

    1988-11-01

    We studied preoperatively and postoperatively 41 children who underwent pyeloplasty for correction of unilateral ureteropelvic junction obstruction. Conventional radiological studies and quantitative radioiodine hippurate renal scans were obtained to assess the effect of pyeloplasty on the appearance of the kidney and its function. Analysis of the data suggests that the degree of improvement in renal function is related primarily to the age at which the surgical correction is accomplished and whether infection has occurred preoperatively.

  13. Human cytomegalovirus immediate early proteins promote degradation of connexin 43 and disrupt gap junction communication: implications for a role in gliomagenesis.

    Science.gov (United States)

    Khan, Zahidul; Yaiw, Koon-Chu; Wilhelmi, Vanessa; Lam, Hoyin; Rahbar, Afsar; Stragliotto, Giuseppe; Söderberg-Nauclér, Cecilia

    2014-01-01

    A lack of gap junctional intercellular communication (GJIC) is common in cancer. Many oncogenic viruses have been shown to downregulate the junctional protein connexin 43 (Cx43) and reduce GJIC. Human cytomegalovirus (HCMV) is a ubiquitous, species-specific betaherpesvirus that establishes life-long latency after primary infection. It encodes two viral gene products, immediate early (IE) proteins IE1 and IE2, which are crucial in viral replication and pathogenesis of many diseases. Emerging evidence demonstrates that HCMV DNA and proteins are highly prevalent in glioblastoma multiforme (GBM) and in other tumors, but HCMV's role in tumorigenesis remains obscure. In the present study, we examined the effects of HCMV infection on Cx43 expression and GJIC as well as the viral mechanism mediating the effects in human GBM cells and tissue samples. We found that HCMV downregulated Cx43 protein, resulting in disruption of functional GJIC as assayed by fluorescent dye transfer assay. We show that both HCMV-IE72 and IE86 mediate downregulation of Cx43 by silencing RNA targeting either IE72 or IE86 coupled with ganciclovir. This finding was further validated by transfection with expression vectors encoding IE72 or IE86, and we show that viral-mediated Cx43 depletion involved proteasomal degradation. Importantly, we also observed that the Cx43 protein levels and IE staining correlated inversely in 10 human GBM tissue specimens. Thus, HCMV regulates Cx43 expression and GJIC, which may contribute to gliomagenesis.

  14. Topological insulator in junction with ferromagnets: Quantum Hall effects

    Science.gov (United States)

    Chudnovskiy, A. L.; Kagalovsky, V.

    2015-06-01

    The ferromagnet-topological insulator-ferromagnet (FM-TI-FM) junction exhibits thermal and electrical quantum Hall effects. The generated Hall voltage and transverse temperature gradient can be controlled by the directions of magnetizations in the FM leads, which inspires the use of FM-TI-FM junctions as electrical and as heat switches in spintronic devices. Thermal and electrical Hall coefficients are calculated as functions of the magnetization directions in ferromagnets and the spin-relaxation time in TI. Both the Hall voltage and the transverse temperature gradient decrease but are not completely suppressed even at very short spin-relaxation times. The Hall coefficients turn out to be independent of the spin-relaxation time for symmetric configuration of FM leads.

  15. Effect of phase noise on quantum correlations in Bose-Josephson junctions

    Energy Technology Data Exchange (ETDEWEB)

    Ferrini, G.; Minguzzi, A.; Hekking, F. W. J. [Universite Grenoble 1 and CNRS, Laboratoire de Physique et Modelisation des Milieux Condenses UMR5493, B.P. 166, F-38042 Grenoble (France); Spehner, D. [Universite Grenoble 1 and CNRS, Laboratoire de Physique et Modelisation des Milieux Condenses UMR5493, B.P. 166, F-38042 Grenoble (France); Universite Grenoble 1 and CNRS, Institut Fourier UMR5582, B.P. 74, F-38402 Saint Martin d' Heres (France)

    2011-10-15

    In a two-mode Bose-Josephson junction the dynamics induced by a sudden quench of the tunnel amplitude leads to the periodic formation of entangled states. For instance, squeezed states are formed at short times and macroscopic superpositions of phase states at later times. In atom interferometry, the two modes of the junction play the role of the two arms of a Mach-Zehnder interferometer; use of multiparticle entangled states allows the enhancement of phase sensitivity with respect to that obtained from uncorrelated atoms. Decoherence due to the presence of noise degrades quantum correlations between atoms, thus reducing phase sensitivity. We consider decoherence due to stochastic fluctuations of the energies of the two modes of the junction. We analyze its effect on squeezed states and macroscopic superpositions and calculate the squeezing parameter and the quantum Fisher information during the quenched dynamics. The latter quantity measures the amount of quantum correlations useful in interferometry. For moderate noise intensities, we show that it increases on time scales beyond the squeezing regime. This suggests multicomponent superpositions of phase states as interesting candidates for high-precision atom interferometry.

  16. Peltier effect in normal metal-insulator-heavy fermion metal junctions

    Science.gov (United States)

    Goltsev, A. V.; Rowe, D. M.; Kuznetsov, V. L.; Kuznetsova, L. A.; Min, Gao

    2003-04-01

    A theoretical study has been undertaken of the Peltier effect in normal metal-insulator-heavy fermion metal junctions. The results indicate that, at temperatures below the Kondo temperature, such junctions can be used as electronic microrefrigerators to cool the normal metal electrode and are several times more efficient in cooling than the normal metal-heavy fermion metal junctions.

  17. Transforming growth factor-β3 regulates cell junction restructuring via MAPK-mediated mRNA destabilization and Smad-dependent protein degradation of junctional adhesion molecule B (JAM-B).

    Science.gov (United States)

    Zhang, Xu; Lui, Wing-Yee

    2015-06-01

    Junctional adhesion molecule-B (JAM-B) is found between Sertoli cells at the blood-testis barrier (BTB) as well as between Sertoli and germ cells at the apical ectoplasmic specializations (ES) in the testis. The expression of JAM-B is tightly regulated to modulate the passage of spermatocytes across the BTB as well as the release of mature spermatozoa from the seminiferous epithelium. Transforming growth factor beta (TGF-β) family is implicated in the regulation of testicular cell junction dynamics during spermatogenesis. This study aims to investigate the effects of TGF-β3 on the expression of JAM-B as well as the underlying mechanisms on how TGF-β3 regulates JAM-B expression to facilitate the disassembly of the BTB and apical ES. Our results revealed that TGF-β3 suppresses JAM-B at post-transcriptional and post-translational levels. Inhibitor, siRNA knockdown and co-immunoprecipitation have shown that TGF-β3 induces JAM-B protein degradation via ubiquitin-proteasome pathway. Immunofluorescence staining further confirmed that blockage of ubiquitin-proteasome pathway could abrogate TGF-β3-induced loss of JAM-B at the cell-cell interface. siRNA knockdown and immunofluorescence staining also demonstrated that activation of Smad signaling is required for TGF-β3-induced JAM-B protein degradation. In addition, TGF-β3 reduces JAM-B mRNA levels, at least in part, via post-transcriptional regulation. mRNA stability assay has confirmed that TGF-β3 promotes the degradation of JAM-B transcript and TGF-β3-mediated mRNA destabilization requires the activation of ERK1/2 and p54 JNK signal cascades. Taken together, TGF-β3 significantly downregulates JAM-B expression via post-transcriptional and post-translational modulation and results in the disruption of BTB and apical ES.

  18. Magnetotransport effects in lateral and vertical ferromagnetic semiconductor junctions

    OpenAIRE

    Rüster, Christian

    2005-01-01

    This work is an investigation of giant magnetoresistance (GMR), tunneling magnetoresistance (TMR) and tunneling anisotropic magnetoresistance (TAMR)effects in (Ga,Mn) based ferromagnetic semiconductor junctions. Detailed results are published in the following articles: [1] C. Rüster, T. Borzenko, C. Gould, G. Schmidt, L.W. Molenkamp, X. Liu, T.J.Wojtowicz, J.K. Furdyna, Z.G. Yu and M. Flatt´e, Very Large Magnetoresistance in Lateral Ferromagnetic (Ga,Mn)As Wires with Nanoconstrictions, Physic...

  19. Study of the electrical parameters degradation of GaAs sub-cells for triple junction space solar cells by computer simulation

    Science.gov (United States)

    Cappelletti, M. A.; Casas, G. A.; Morales, D. M.; Hasperue, W.; Blancá, E. L. Peltzer y.

    2016-11-01

    In this paper, a theoretical study of the electrical parameters degradation of different n-type GaAs sub-cells for InGaP/GaAs/Ge triple junction solar cells irradiated with 1 and 5 MeV electrons has been performed by means of computer simulation. Effects of base carrier concentration upon the maximum power point, short-circuit current, open circuit voltage, diffusion current, recombination current and series resistance of these devices have been researched using the displacement damage dose method, the one-dimensional PC1D device modeling program and a home-made numerical code based on genetic algorithms. The radiative recombination lifetime, damage constant for minority-carrier lifetime and carrier removal rate models for GaAs sub-cells have been used in the simulations. An analytical model has been proposed, which is useful to describe the radiation-induced degradation of diffusion current, recombination current and series resistance. Results obtained in this work can be used to predict the radiation resistance of solar cells over a wide range of energies.

  20. Field emission current from a junction field-effect transistor

    Energy Technology Data Exchange (ETDEWEB)

    Monshipouri, Mahta; Abdi, Yaser, E-mail: y.abdi@ut.ac.ir [University of Tehran, Nano-Physics Research Laboratory, Department of Physics (Iran, Islamic Republic of)

    2015-04-15

    Fabrication of a titanium dioxide/carbon nanotube (TiO{sub 2}/CNT)-based transistor is reported. The transistor can be considered as a combination of a field emission transistor and a junction field-effect transistor. Using direct current plasma-enhanced chemical vapor deposition (DC-PECVD) technique, CNTs were grown on a p-typed (100)-oriented silicon substrate. The CNTs were then covered by TiO{sub 2} nanoparticles 2–5 nm in size, using an atmospheric pressure CVD technique. In this device, TiO{sub 2}/CNT junction is responsible for controlling the emission current. High on/off-current ratio and proper gate control are the most important advantages of device. A model based on Fowler–Nordheim equation is utilized for calculation of the emission current and the results are compared with experimental data. The effect of TiO{sub 2}/CNT hetero-structure is also investigated, and well modeled.

  1. Electrical transport measurements and degradation of graphene/n-Si Schottky junction diodes

    Energy Technology Data Exchange (ETDEWEB)

    Park, No-Won; Lee, Won-Yong; Lee, Sang-Kwon; Koh, Jung-Hyuk [Chung-Ang University, Seoul (Korea, Republic of); Kim, Dong-Joo; Kim, Gil-Sung; Hyung, Jung-Hwan; Hong, Chang-Hee [Chonbuk National University, Jeonju (Korea, Republic of); Kim, Keun-Soo [Sejong University, Seoul (Korea, Republic of)

    2015-01-15

    We report on the electrical properties, such as the ideality factors and Schottky barrier heights, that were obtained by using current density - voltage (J - V ) and capacitance - voltage (C - V ) characteristics. To fabricate circularly- and locally-contacted Au/Gr/n-Si Schottky diode, we deposited graphene through the chemical vapor deposition (CVD) growth technique, and we employed reactive ion etching to reduce the leakage current of the Schottky diodes. The average values of the barrier heights and the ideality factors from the J .V characteristics were determined to be ∼0.79 ± 0.01 eV and ∼1.80 ± 0.01, respectively. The Schottky barrier height and the doping concentration from the C - V measurements were ∼0.85 eV and ∼1.76 x 10{sup 15} cm{sup -3}, respectively. From the J - V characteristics, we obtained a relatively low reverse leakage current of ∼2.56 x 10{sup -6} mA/cm{sup -2} at -2 V, which implies a well-defined rectifying behavior. Finally, we found that the Gr/n-Si Schottky diodes that were exposed to ambient conditions for 7 days exhibited a ∼3.2-fold higher sheet resistance compared with the as-fabricated Gr/n-Si diodes, implying a considerable electrical degradation of the Gr/n-Si Schottky diodes.

  2. Coexistence of tunneling magnetoresistance and Josephson effects in SFIFS junctions

    Science.gov (United States)

    Vávra, O.; Soni, R.; Petraru, A.; Himmel, N.; Vávra, I.; Fabian, J.; Kohlstedt, H.; Strunk, Ch.

    2017-02-01

    We demonstrate an integration of tunneling magnetoresistance and the Josephson effects within one tunneling junction. Several sets of Nb-Fe-Al-Al2O3-Fe-Nb wafers with varying Al and Fe layers thickness were prepared to systematically explore the competition of TMR and Josephson effects. A coexistence of the critical current IC(dFe) and the tunneling magnetoresistance ratio T M R(dFe) is observed for iron layer dFe thickness range 1.9 and 2.9 nm. Further optimization such as thinner Al2O3 layer leads to an enhancement of the critical current and thus to an extension of the coexistence regime up to dFe≃3.9 nm Fe.

  3. Radiation effects on bipolar junction transistors and integrated circuits produced by different energy Br ions

    Science.gov (United States)

    Li, Xingji; Geng, Hongbin; Liu, Chaoming; Zhao, Zhiming; Lan, Mujie; Yang, Dezhuang; He, Shiyu

    2009-12-01

    The radiation responses of the NPN bipolar junction transistors (BJTs) and the TTL bipolar integrated circuits (ICs) have been examined using 20, 40 and 60 MeV Br ions. Key electric parameter was measured and compared after each energy irradiation. Experimental results demonstrate that the degradation in electric parameters caused by the Br ions shows a common feature for the NPN BJTs and TTL ICs, in which the degradation is strengthened with decreasing the Br ions energy. The ionizing dose ( D i) and displacement dose ( D d) as a function of the chip depth in the bipolar devices were calculated using the SRIM code, in order to analyze the radiation effects on the NPN BJTs and the Bipolar ICs. From the experiment and calculation results, it could be deduced that the Br ions mainly cause displacement damage to both the NPN BJTs and the TTL ICs, and the higher the ratio of D d/( D d+D i), the larger the degradation in electric parameters at a given total dose.

  4. Gap Junctions

    Science.gov (United States)

    Nielsen, Morten Schak; Axelsen, Lene Nygaard; Sorgen, Paul L.; Verma, Vandana; Delmar, Mario; Holstein-Rathlou, Niels-Henrik

    2013-01-01

    Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease. © 2012 American Physiological Society. Compr Physiol 2:1981-2035, 2012. PMID:23723031

  5. Gap junctions.

    Science.gov (United States)

    Nielsen, Morten Schak; Axelsen, Lene Nygaard; Sorgen, Paul L; Verma, Vandana; Delmar, Mario; Holstein-Rathlou, Niels-Henrik

    2012-07-01

    Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease. © 2012 American Physiological Society. Compr Physiol 2:1853-1872, 2012.

  6. Synthesis and photocatalytic degradation of methylene blue over p-n junction Co{sub 3}O{sub 4}/ZnO core/shell nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Chengjun; Xiao, Xuechun; Chen, Gang; Guan, Hongtao; Wang, Yude, E-mail: ydwang@ynu.edu.cn

    2015-04-01

    One-dimension (1D) Co{sub 3}O{sub 4}/ZnO core/shell nanorods (NRs) were synthesized on nickel foil substrate by means of a two-step synthetic strategy. Co{sub 3}O{sub 4} NRs were initially fabricated by a facile hydrothermal reaction and then ZnO was coated via a simple thermal decomposition. The results verified that the surface of the p-type Co{sub 3}O{sub 4} core was uniformly assembled by the n-type ZnO nanoparticles with approximate 20 nm thickness. Compared with pristine Co{sub 3}O{sub 4} NRs, Co{sub 3}O{sub 4}/ZnO core/shell NRs was exhibited to have a much higher photocatalytic properties in the decomposition of a model dye compound, methylene blue (MB), under ultraviolet irradiation. As confirmed by Photoluminescence (PL) spectra, the formation of p-n junction heterostructures gives rise to the enhanced photocatalystic performance of Co{sub 3}O{sub 4}/ZnO core/shell NRs. This study provides a general and effective method in the fabrication of 1D composition NRs with sound heterojunctions that show remarkable enhancement of photocatalytic performance. - Highlights: • 1D Co{sub 3}O{sub 4}/ZnO core/shell NRs were synthesized on nickel foil by a two-step synthetic strategy. • The thickness of ZnO coating is determined to be about 20 nm. • Co{sub 3}O{sub 4}/ZnO NRs exhibited better photocatalytic performance for MB degradation under UV irradiation. • The formation of p-n junctions confirmed by PL is a critical factor for photocatalytic enhancement. • The working mechanism for Co{sub 3}O{sub 4}/ZnO NRs as photocatalyst was proposed.

  7. Thermal electric effects in Fe|GaAs|Fe tunnel junctions

    Directory of Open Access Journals (Sweden)

    Xintao Jia

    2012-12-01

    Full Text Available We study the spin polarized thermoelectric effects on Fe|GaAs|Fe tunnel junction using a generalized Landauer-Büttiker formalism, where the energy flow is described on the same footing as the electric current. The Seebeck coefficient of tunnel junction will change sign as the GaAs thickness increases. We demonstrate the thermally induced STT on Fe|GaAs|Fe tunnel junction is robust against the interfacial defects and is non-negligible.

  8. Radiation damage effects on double-junction GaInP{sub 2}/GaAs solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yueyuan [Key Laboratory for Photonic and Electronic Bandgap Materials, Ministry of Education, School of Physics and Electronic Engineering, Harbin Normal University, Harbin 150025 (China); Hu, Jianmin, E-mail: hujianmin@foxmail.com [Key Laboratory for Photonic and Electronic Bandgap Materials, Ministry of Education, School of Physics and Electronic Engineering, Harbin Normal University, Harbin 150025 (China); Wu, Yiyong [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Xu, Jianwen; Lu, Jianfeng [Shanghai Institute of Space Power Sources, Shanghai 200233 (China); Zhao, Huijie [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Qian, Bin [Shanghai Institute of Space Power Sources, Shanghai 200233 (China)

    2014-07-01

    The radiation effects on a double-junction GaInP{sub 2}/GaAs solar cell were studied under exposures of 100 keV protons, 10 MeV protons and 1 MeV electrons, in terms of changes on electrical properties and spectral response. The results indicate that the electrical property degradation of the double-junction GaInP{sub 2}/GaAs solar cell under irradiation occurs mainly due to the damage in the GaAs sub-cell. The GaAs sub-cell damage is primarily attributed to the decrease in collection efficiency of the minority carriers coming from its base bottom. It is revealed from the cell behavior under exposure to 100 keV protons irradiation that under the AM0 illumination, there is no obvious damage defected in the tunnel junction between the GaInP{sub 2} and the GaAs sub cells. In addition, the tunnel junction between the GaInP{sub 2} and the GaAs sub-cells is stable and no boundary traps are formed.

  9. Effect of thermal-annealing on the magnetoresistance of manganite-based junctions

    Institute of Scientific and Technical Information of China (English)

    Xie Yan-Wu; Shen Bao-Gen; Sun Ji-Rong

    2008-01-01

    Thermal-annealing has been widely used in modulating the oxygen content of manganites. In this work, we have studied the effect of annealing on the transport properties and magnetoresistance of junctions composed of a La0.9Ca0.1MnO3+δ film and a Nb-doped SrTiO3 substrate. We have demonstrated that the magnetoresistance of junctions is strongly dependent on the annealing conditions: From the junction annealed-in-air to the junction annealed-in-vacuum, the magnetoresistance near 0-V bias can vary from ~-60% to~0. A possible mechanism accounting for this phenomenon is discussed.

  10. Comparison of the magneto-Peltier and magneto-Seebeck effects in magnetic tunnel junctions

    NARCIS (Netherlands)

    Shan, J.; Dejene, F. K.; Leutenantsmeyer, J. C.; Flipse, J.; Munzenberg, M.; van Wees, B. J.

    2015-01-01

    Understanding heat generation and transport processes in a magnetic tunnel junction (MTJ) is a significant step towards improving its application in current memory devices. Recent work has experimentally demonstrated the magneto-Seebeck effect in MTJs, where the Seebeck coefficient of the junction v

  11. Reinventing the PN Junction: Dimensionality Effects on Tunneling Switches

    Science.gov (United States)

    2012-05-11

    lower paraboloid represents all of the available states in k-space on the left side of the junction and the upper paraboloid represents the available...and so the paraboloids must overlap. However, as seen in the right part of the figure, they can only overlap at a single energy. Furthermore, the... paraboloids on each side of the junction only intersect at a single energy. 62 need to sum Eqn. (6.8.3) over all initial states or final

  12. Nonequilibrium and relaxation effects in tunnel superconducting junctions

    Science.gov (United States)

    Bezuglyi, E. V.; Vasenko, A. S.; Bratus', E. N.

    2017-02-01

    The specific property of a planar tunnel junction with thin-film diffusive plates and long enough leads is an essential enhancement of its transmission coefficient compared to the bare transparency of the tunnel barrier [1, 2]. In voltage-biased junctions, this creates favorable conditions for strong nonequilibrium of quasiparticles in the junction plates and leads, produced by multiparticle tunneling. We study theoretically the interplay between the nonequilibrium and relaxation processes in such junctions and found that nonequilibrium in the leads noticeably modifies the current-voltage characteristic at {eV}> 2{{Δ }}, especially the excess current, whereas strong diffusive relaxation restores the result of the classical tunnel model. At {eV}≤slant 2{{Δ }}, the diffusive relaxation decreases the peaks of the multiparticle currents. The inelastic relaxation in the junction plates essentially suppresses the n-particle currents (n> 2) by the factor n for odd and n/2 for even n. The results may be important for the problem of decoherence in Josephson-junction based superconducting qubits.

  13. Strain effect on spin polarization in a graphene junction

    Science.gov (United States)

    Cao, Zhenzhou; Lu, Ning; Qiu, Xuejun; Wang, Guofei

    2017-04-01

    We investigate the strain effect on the spin-dependent transport in a graphene junction with spin–orbit coupling and a gate voltage. We find that uniaxial strain along the armchair direction breaks the transmission probability symmetry with respect to the incident angle, reduces the spin-flipped transmission probability, and extends the transmission gap as regard to the Fermi energy, while strain along the zig-zag direction has very little effect on transmission probabilities. We analyze the spin polarization as a function of the strain magnitude, direction, voltage, and area width. Selecting the proper strain direction and magnitude for both the Klein tunneling and classical cases, the direction of the spin-polarization vector can be controlled and its magnitude is dramatically enhanced. Strain will expand the non-zero range of the magnitude of the spin-polarization vector with respect to voltage. Increasing the strain area width over a threshold, keeps the magnitude of the spin-polarization vector stable.

  14. Dryland degradation: Measurement and effects on ecosystems

    Science.gov (United States)

    Noojipady, P.; Prince, S. D.; Rishmawi, K.

    2012-12-01

    Land degradation is frequently described as a global crisis, affecting large areas globally and large numbers of people. Nevertheless, the location and severity of degradation globally with a resolution relevant to human activities is unknown. Beyond the direct stress of degradation on human livelihoods, there are important effects on the physical and biological environment. Examples include loss of potential primary production, changes in the surface water and energy balances, erosion, sediment transport and lofting of dust aerosols. Globally , degradation is mainly associated with drylands, such as the US dustbowl of the 1930s and, supposedly, ongoing loss of crop and livestock production in desert margins on all continents. The alarm over loss of land to deserts, particularly early 1980s in the African Sahel, led to the adoption of the term "desertification". Such degradation is said to have two components; a physical environment that reduces productivity; and human land use that exceeds the resilience of the land. Ecological theory suggests that land can exist in multiple stable states with transitions between them. Some experimental evidence suggests that one such state is degradation from which there can be no recovery. Clearly the occurrence of such stable degradation, where land is unable to recover when the physical conditions such as rainfall and human land use are ameliorated, is of theoretical and practical importance. The aim of this work is to contribute to the resolution of two issues: (i) are there significant areas in which land has been degraded by human actions and, (ii), have any of these areas entered a stable degraded state? Detection of the human component necessarily requires control of the physical component of degradation. We have developed a technique to detect areas that are at their potential production and to assess other areas relative to these. Satellite measurements of vegetation indices are used as a surrogate for Net Primary

  15. Anomalous Proximity Effect in the Nb-BiSb-Nb Junctions

    Energy Technology Data Exchange (ETDEWEB)

    Kasumov, A.Y.; Kononenko, O.V.; Matveev, V.N.; Borsenko, T.B.; Tulin, V.A.; Vdovin, E.E.; Khodos, I.I. [Institute of Microelectronics Technology and High Purity Materials, RAS, 142432 Chernogolovka, Moscow Region (Russia)

    1996-09-01

    An anomalous proximity effect was observed in coplanar Nb-BiSb-Nb junctions. The effect consists of a considerable increase of the critical current with an increase in the distance between the superconducting electrodes. The effect is explained by the quantum character of Cooper pair transport through the normal region. Some advantages of the application of such junctions are discussed. {copyright} {ital 1996 The American Physical Society.}

  16. Effects of LC shunting on the Shapiro steps features of Josephson junction

    Science.gov (United States)

    Shukrinov, Yu. M.; Rahmonov, I. R.; Kulikov, K. V.; Seidel, P.

    2015-05-01

    We study an effect of external radiation on the dynamics of Josephson junction shunted by an LC circuit. When the Josephson frequency is equal to the frequency of the circuit, additional stable resonant circuit branches appear in the IV-characteristic of the junction. The branches occur on the stable side of a narrow resonance peak, while the other peak side has a negative slope and is unstable. We show that the amplitude dependence of the Shapiro step width crucially changes when the Shapiro step is on the resonant circuit branch. These effects might give very important advantages for methods and technologies that exploit the response of Josephson junctions to microwave fields.

  17. Effects of some depressant drugs on synaptic responses to glutamate at the crayfish neuromuscular junction.

    OpenAIRE

    1984-01-01

    Excitatory junction currents produced by glutamate were recorded with an extracellular electrode at the neuromuscular junction of the crayfish. Pentobarbitone, phenobarbitone, diazepam, chlordiazepoxide and procaine had only minimal effects on current decay at concentrations which are highly effective in other preparations. The glutamate synapse in the crayfish appears relatively resistant to these drugs. In contrast, ether and halothane increased the rate of decay of the currents at concentr...

  18. Effects of electron radiation on shielded space triple-junction GaAs solar cells

    Institute of Scientific and Technical Information of China (English)

    Gao Xin; Yang Sheng-Sheng; Xue Yu-Xiong; Li Kai; Li Dan-Ming; Wang Yi; Wang Yun-Fei; Feng Zhan-Zu

    2009-01-01

    The displacement damage dose methodology for analysing and modelling the performance of triple-junction InGaP_2/GaAs/Ge solar cells in an electron radiation environment is presented. Degradations at different electron energies are correlated with displacement damage dose (D_d). One particular electron radiation environment, relative to a geosynchronous earth orbit (GEO), is chosen to calculate the total D_d behind the different thicknesses coverglasses to predict the performance degradation at the end of the 15-year mission.

  19. Current distribution effects in patterned non-linear magnetoresistive tunnel junctions

    CERN Document Server

    Montaigne, F; Schuhl, A

    2000-01-01

    To be used in submicronic devices like magnetic memories, magnetic tunnel junctions require low resistances. Four-probe measurements of such resistances are often altered by non-uniformity of the current distribution in the junction. The measured resistance is decreased by localised preferential conduction and increased by voltage drop in the measure electrode. Competition between these two effects is investigated as a function of the geometry. The non-linear conduction of tunnel junctions amplifies dramatically these phenomena and can modify by more than 50% the measured resistance.

  20. Effect of Barrier Width on Bias-Dependent Tunnelling in Ferromagnetic Junctions

    Institute of Scientific and Technical Information of China (English)

    LI Fei-Fei; XIAO Ming-Wen; LI Zheng-Zhong; HU An; XU Wang

    2004-01-01

    @@ We present a finite temperature theory for bias-dependent tunnelling in ferromagnetic tunnelling junctions. The effects of the barrier width d on the tunnelling magnetoresistance (TMR) and its sign change behaviour are discussed with this theory. Numerical results show that both the zero-bias TMR and the critical voltage Vc at which the TMR changes its sign decrease with the increasing barrier width for a considerably thick barrier junction. Furthermore, it is found that a minimum exists in the curve of Vc versus d if a composite junction is under oxidized.

  1. Effect of Electron-Phonon Scattering on Shot Noise in Nanoscale Junctions

    Science.gov (United States)

    Chen, Yu-Chang; di Ventra, Massimiliano

    2005-10-01

    We investigate the effect of electron-phonon inelastic scattering on shot noise in nanoscale junctions in the regime of quasiballistic transport. We predict that when the local thermal energy of the junction is larger than its lowest vibrational mode energy eVc, the inelastic contribution to shot noise (conductance) increases (decreases) with bias as V (V). The corresponding Fano factor thus increases as V. We also show that the inelastic contribution to the Fano factor saturates with increasing thermal current exchanged between the junction and the bulk electrodes to a value which, for V≫Vc, is independent of bias. These predictions can be readily tested experimentally.

  2. Radiation effects on bipolar junction transistors induced by 25 MeV carbon ions

    Science.gov (United States)

    Liu, Chaoming; Li, Xingji; Geng, Hongbin; Zhao, Zhiming; Yang, Dezhuang; He, Shiyu

    2010-12-01

    The characteristic degradation in silicon NPN bipolar junction transistors (BJTs) of 3DG112 type is examined under the irradiation with 25 MeV carbon (C) ions and various bias conditions. Different electrical parameters were measured in-situ during the exposure under each bias condition. From the experimental data, larger variation of base current ( IB) is observed after irradiation at a given value of base-emitter voltage ( VBE), while the collector current is only slightly affected by irradiation at a given VBE. The gain degradation is mostly affected by the behavior of the base current. The change in the reciprocal of current gain (Δ(1/ β)) increases linearly with increasing the C ions fluence. The degradation of the NPN BJTs under various bias conditions during irradiation was studied. Compared to the case where the terminals are grounded, at a given fluence, the change in the reciprocal of current gain varies slightly less when the base-emitter junction is forward biased. On the other hand, there is no distinction for the change in the reciprocal of current gain between the case of reverse-biased base-emitter junction and that of all terminals grounded for the NPN BJTs at a given fluence.

  3. Low-bias negative differential resistance effect in armchair graphene nanoribbon junctions

    Energy Technology Data Exchange (ETDEWEB)

    Li, Suchun [Department of Physics, Center for Advanced 2D Materials and Graphene Research Center, National University of Singapore, 2 Science Drive 3, Singapore 117551 (Singapore); Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632 (Singapore); NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, Singapore 117456 (Singapore); Gan, Chee Kwan [Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632 (Singapore); Son, Young-Woo [Korea Institute for Advanced Study, Seoul 130-722 (Korea, Republic of); Feng, Yuan Ping [Department of Physics, Center for Advanced 2D Materials and Graphene Research Center, National University of Singapore, 2 Science Drive 3, Singapore 117551 (Singapore); NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, Singapore 117456 (Singapore); Quek, Su Ying, E-mail: phyqsy@nus.edu.sg [Department of Physics, Center for Advanced 2D Materials and Graphene Research Center, National University of Singapore, 2 Science Drive 3, Singapore 117551 (Singapore); Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632 (Singapore)

    2015-01-05

    Graphene nanoribbons with armchair edges (AGNRs) have bandgaps that can be flexibly tuned via the ribbon width. A junction made of a narrower AGNR sandwiched between two wider AGNR leads was recently reported to possess two perfect transmission channels close to the Fermi level. Here, we report that by using a bias voltage to drive these transmission channels into the gap of the wider AGNR lead, we can obtain a negative differential resistance (NDR) effect. Owing to the intrinsic properties of the AGNR junctions, the on-set bias reaches as low as ∼0.2 V and the valley current almost vanishes. We further show that such NDR effect is robust against details of the atomic structure of the junction, substrate, and whether the junction is made by etching or by hydrogenation.

  4. Magnetostatic effects on switching in small magnetic tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Bapna, Mukund; Piotrowski, Stephan K.; Oberdick, Samuel D.; Majetich, Sara A., E-mail: sara@cmu.edu [Physics Department, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Li, Mingen; Chien, C.-L. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

    2016-01-11

    Perpendicular CoFeB/MgO/CoFeB magnetic tunnel junctions with diameters under 100 nm are investigated by conductive atomic force microscopy. Minor loops of the tunnel magnetoresistance as a function of applied magnetic field reveal the hysteresis of the soft layer and an offset due to the magnetostatic field of the hard layer. Within the hysteretic region, telegraph noise is observed in the tunnel current. Simulations show that in this range, the net magnetic field in the soft layer is spatially inhomogeneous, and that antiparallel to parallel switching tends to start near the edge, while parallel to antiparallel reversal favors nucleation in the interior of the soft layer. As the diameter of the tunnel junction is decreased, the average magnitude of the magnetostatic field increases, but the spatial inhomogeneity across the soft layer is reduced.

  5. Aharonov-Casher effect for plasmons in a ring of Josephson junctions

    Science.gov (United States)

    Süsstrunk, Roman; Garate, Ion; Glazman, Leonid I.

    2013-08-01

    Phase slips in a one-dimensional closed array of Josephson junctions hybridize the persistent current states and plasmon branches of excitations. The interference between phase slips passing through different junctions of the array makes the hybridization sensitive to the charges of the superconducting islands comprising the array. This in turn results in the Aharonov-Casher effect for plasmons, which in the absence of phase slips are insensitive to island charges.

  6. Effective medium theory of the space-charge region electrostatics of arrays of nanoscale junctions

    Science.gov (United States)

    Gurugubelli, Vijaya Kumar; Karmalkar, Shreepad

    2016-01-01

    We develop an Effective Medium Theory for the electrostatics of the Space-Charge Region (SCR) of Schottky and p-n junctions in arrays of nanofilms (NFs), nanowires (NWs), and nanotubes (NTs) in a dielectric ambient. The theory captures the effects of electric fields in both the semiconductor, i.e., NF/NW/NT, and the dielectric media of the array. It shows that the depletion width and the screening length characterizing the SCR tail in the array correspond to those in a bulk junction with an effective semiconductor medium, whose permittivity and doping are their weighted averages over the cross-sectional areas of the semiconductor and dielectric; the shapes of the cross-sections are immaterial. Further, the reverse bias 1 /C2 -V behavior of junctions in NF/NW/NT arrays is linear, as in bulk junctions, and is useful to extract from measurements the built-in potential, effective doping including the semiconductor-dielectric interface charge, and NF/NW/NT length. The theory is validated with numerical simulations, is useful for the experimentalist, and yields simple formulas for nano-device design which predict the following. In the limiting case of a single sheet-like NF, the junction depletion width variation with potential drop is linear rather than square-root (as in a bulk junction). In arrays of symmetric silicon p-n junctions in oxide dielectric where NF/NW thickness and separation are 5% and 100% of the bulk depletion width, respectively, the junction depletion width and the screening length are scaled up from their bulk values by the same factor of ˜2 for NF and ˜10 for NW array.

  7. From four- to two-channel Kondo effect in junctions of XY spin chains

    Directory of Open Access Journals (Sweden)

    Domenico Giuliano

    2016-08-01

    Full Text Available We consider the Kondo effect in Y-junctions of anisotropic XY models in an applied magnetic field along the critical lines characterized by a gapless excitation spectrum. We find that, while the boundary interaction Hamiltonian describing the junction can be recasted in the form of a four-channel, spin-1/2 antiferromagnetic Kondo Hamiltonian, the number of channels effectively participating in the Kondo effect depends on the chain parameters, as well as on the boundary couplings at the junction. The system evolves from an effective four-channel topological Kondo effect for a junction of XX-chains with symmetric boundary couplings into a two-channel one at a junction of three quantum critical Ising chains. The effective number of Kondo channels depends on the properties of the boundary and of the bulk. The XX-line is a “critical” line, where a four-channel topological Kondo effect can be recovered by fine-tuning the boundary parameter, while along the line in parameter space connecting the XX-line and the critical Ising point the junction is effectively equivalent to a two-channel topological Kondo Hamiltonian. Using a renormalization group approach, we determine the flow of the boundary couplings, which allows us to define and estimate the critical couplings and Kondo temperatures of the different Kondo (pair channels. Finally, we study the local transverse magnetization in the center of the Y-junction, eventually arguing that it provides an effective tool to monitor the onset of the two-channel Kondo effect.

  8. From four- to two-channel Kondo effect in junctions of XY spin chains

    Energy Technology Data Exchange (ETDEWEB)

    Giuliano, Domenico, E-mail: domenico.giuliano@fis.unical.it [Dipartimento di Fisica, Università della Calabria, Arcavacata di Rende I-87036, Cosenza (Italy); INFN, Gruppo collegato di Cosenza, Arcavacata di Rende I-87036, Cosenza (Italy); Sodano, Pasquale, E-mail: pasquale.sodano02@gmail.com [International Institute of Physics, Universidade Federal do Rio Grande do Norte, 59078-400 Natal, RN (Brazil); Departemento de Física Teorica e Experimental, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil); Tagliacozzo, Arturo, E-mail: arturo.tagliacozzo@na.infn.it [INFN, Gruppo collegato di Cosenza, Arcavacata di Rende I-87036, Cosenza (Italy); Dipartimento di Fisica, Università di Napoli “Federico II”, Monte S. Angelo-Via Cintia, I-80126 Napoli (Italy); CNR-SPIN, Monte S. Angelo-Via Cintia, I-80126 Napoli (Italy); Trombettoni, Andrea, E-mail: andreatr@sissa.it [CNR-IOM DEMOCRITOS Simulation Center, Via Bonomea 265, I-34136 Trieste (Italy); SISSA and INFN, Sezione di Trieste, Via Bonomea 265, I-34136 Trieste (Italy)

    2016-08-15

    We consider the Kondo effect in Y-junctions of anisotropic XY models in an applied magnetic field along the critical lines characterized by a gapless excitation spectrum. We find that, while the boundary interaction Hamiltonian describing the junction can be recasted in the form of a four-channel, spin-1/2 antiferromagnetic Kondo Hamiltonian, the number of channels effectively participating in the Kondo effect depends on the chain parameters, as well as on the boundary couplings at the junction. The system evolves from an effective four-channel topological Kondo effect for a junction of XX-chains with symmetric boundary couplings into a two-channel one at a junction of three quantum critical Ising chains. The effective number of Kondo channels depends on the properties of the boundary and of the bulk. The XX-line is a “critical” line, where a four-channel topological Kondo effect can be recovered by fine-tuning the boundary parameter, while along the line in parameter space connecting the XX-line and the critical Ising point the junction is effectively equivalent to a two-channel topological Kondo Hamiltonian. Using a renormalization group approach, we determine the flow of the boundary couplings, which allows us to define and estimate the critical couplings and Kondo temperatures of the different Kondo (pair) channels. Finally, we study the local transverse magnetization in the center of the Y-junction, eventually arguing that it provides an effective tool to monitor the onset of the two-channel Kondo effect.

  9. Forming a stone in pelviureteric junction obstruction: cause or effect?

    Science.gov (United States)

    Stasinou, Theodora; Bourdoumis, Andreas; Masood, Junaid

    2017-01-01

    ABSTRACT Objectives To investigate a possible causal relationship for stone formation in pelviureteric junction obstruction and to outline management options. Materials and Methods A literature search and evidence synthesis was conducted via electronic databases in the English language using the key words pelviureteric junction obstruction; urolithiasis; hyperoxaluria; laparoscopic pyeloplasty; flexible nephroscopy; percutaneous nephrolithotomy, alone or in combination. Relevant articles were analysed to extract conclusions. Results Concomitant pelviureteric junction obstruction (PUJO) and renal lithiasis has been reported only scarcely in the literature. Although PUJO has been extensively studied throughout the years, the presence of calculi in such a patient has not received equal attention and there is still doubt surrounding the pathophysiology and global management. Conclusions Metabolic risk factors appear to play an important role, enough to justify metabolic evaluation in these patients. Urinary stasis and infection are well known factors predisposing to lithiasis and contribute to some extent. The choice for treatment is not always straightforward. Management should be tailored according to degree of obstruction, renal function, patient symptoms and stone size. Simultaneous treatment is feasible with the aid of minimally invasive operative techniques and laparoscopy in particular.

  10. Modelling the effect of gap junctions on tissue-level cardiac electrophysiology

    CERN Document Server

    Bruce, Doug; Whiteley, Jonathan P

    2012-01-01

    When modelling tissue-level cardiac electrophysiology, continuum approximations to the discrete cell-level equations are used to maintain computational tractability. One of the most commonly used models is represented by the bidomain equations, the derivation of which relies on a homogenisation technique to construct a suitable approximation to the discrete model. This derivation does not explicitly account for the presence of gap junctions connecting one cell to another. It has been seen experimentally [Rohr, Cardiovasc. Res. 2004] that these gap junctions have a marked effect on the propagation of the action potential, specifically as the upstroke of the wave passes through the gap junction. In this paper we explicitly include gap junctions in a both a 2D discrete model of cardiac electrophysiology, and the corresponding continuum model, on a simplified cell geometry. Using these models we compare the results of simulations using both continuum and discrete systems. We see that the form of the action potent...

  11. Effect of junction depth on the performance of a diffused n+p silicon solar cell

    Science.gov (United States)

    Caleb Dhanasekaran, P.; Gopalam, B. S. V.

    1981-12-01

    A detailed numerical analysis of the influence of the junction depth on the performance of a diffused n+p silicon solar cell is presented. The analysis includes the effects of Fermi-Dirac statistics, band gap narrowing, a finite surface recombination velocity and the built-in field due to the impurity profile. The recombination mechanism plays a dominant role in the performance of the solar cell. The ideality factor, " a", varies from 1.006 for 0.1 μm junction depth, to 1.0135 for 2 μm junction depth. The saturation current density, Jo increases with the junction depth showing that the recombination increases in the heavily doped diffused layer of the device. The variation of the light generated current, JL, the open-circuit voltage, Voc, efficiency, η and the ideality factor, " a" are reported and analysed.

  12. Excitatory effects of Buthus C56 toxin on Drosophila larval neuromuscular junction

    Directory of Open Access Journals (Sweden)

    S. P. Gawade

    2003-01-01

    Full Text Available Buthus C56 toxin from venom of the Indian red scorpion Mesobuthus tamulus was studied for its effects on spontaneous miniature excitatory junctional potentials (MEJP on Drosophila larval neuromuscular junctions. C56 toxin was isolated on CM-Cellulose with linear gradient of ammonium acetate buffer, pH 6.0. Toxin purity was determined on SDS slab gel electrophoresis. Effective concentration of C56 toxin was based on contraction paralysis units (CPU in Drosophila 3rd instar larvae by microinjection (0.1 CPU/ml = 2 x 10-6 g/ml. The toxin-induced excitatory junctional potentials were studied for calcium dependency (0.2 mM to 1.2 mM Ca2+ in Drosophila Ringer. Excitatory junctional potential amplitude was increased with increasing calcium concentration; maximum increase in the frequency at 0.4 mM Ca2+/4 mM Mg2+ Drosophila Ringer. It was suggested that while amplitude of excitatory junctional potentials was increased with concentration, maximum frequency increase at 0.4 mMCa2+/4 mM Mg2+ Drosophila Ringer may be due to augmented Ca2+ influx in 0.4 mM Ca2+, when NMDA receptors were maximally activated in C56 toxin-treated Drosophila larval neuromuscular junction.

  13. Effects of vegetation's degradation on carbon stock, morphological ...

    African Journals Online (AJOL)

    Effects of vegetation's degradation on carbon stock, morphological, physical and ... soils to stock carbon and how degradation can influence its various properties. ... Organic matter amount was very high and proves that these soils can be ...

  14. Correlation between amplitude of spin accumulation signals investigated by Hanle effect measurement and effective junction barrier height in CoFe/MgO/n+-Si junctions

    Science.gov (United States)

    Saito, Y.; Ishikawa, M.; Sugiyama, H.; Inokuchi, T.; Hamaya, K.; Tezuka, N.

    2015-05-01

    Correlation between the amplitude of the spin accumulation signals and the effective barrier height estimated from the slope of the log (RA) - tMgO plot (RA: resistance area product, tMgO: thickness of MgO tunnel barrier) in CoFe/MgO/n+-Si junctions was investigated. The amplitude of spin accumulation signals increases with increasing effective barrier heights. This increase of the amplitude of spin accumulation is originated from the increase of the spin polarization ( P S i ) in Si. The estimated absolute values of P S i using three-terminal Hanle signals are consistent with those estimated by four-terminal nonlocal-magnetoresistance (MR) and two-terminal local-MR. To demonstrate large spin accumulation in Si bulk band and enhance the local-MR through Si channel, these results indicate that the increase of the effective barrier height at ferromagnet/(tunnel barrier)/n+-Si junction electrode is important.

  15. Full range of proximity effect probed with superconductor/graphene/superconductor junctions

    Science.gov (United States)

    Li, Chuan; Guéron, S.; Chepelianskii, A.; Bouchiat, H.

    2016-09-01

    The high tunability of the density of states of graphene makes it an ideal probe of quantum transport in different regimes. In particular, the supercurrent that can flow through a nonsuperconducting (N) material connected to two superconducting (S) electrodes, crucially depends on the length of the N relative to the superconducting coherence length. Using graphene as the N material we have investigated the full range of the superconducting proximity effect, from short to long diffusive junctions. By combining several S/graphene/S samples with different contacts and lengths, and measuring their gate-dependent critical currents (Ic) and normal state resistance RN, we compare the product e RNIc to the relevant energies, the Thouless energy in long junctions and the superconducting gap of the contacts in short junctions, over three orders of magnitude of Thouless energy. The experimental variations strikingly follow a universal law, close to the predictions of the proximity effect both in the long and short junction regime, as well as in the crossover region, thereby revealing the interplay of the different energy scales. Differences in the numerical coefficients reveal the crucial role played by the interfacial barrier between graphene and the superconducting electrodes, which reduces the supercurrent in both short and long junctions. Surprisingly, the reduction of supercurrent is independent of the gate voltage and of the nature of the electrodes. A reduced induced gap and Thouless energy are extracted, revealing the role played by the dwell time in the barrier in the short junction, and an effective increased diffusion time in the long junction. We compare our results to the theoretical predictions of Usadel equations and numerical simulations, which better reproduce experiments with imperfect NS interfaces.

  16. 0-π Transition Driven by Magnetic Proximity Effect in a Josephson Junction

    Science.gov (United States)

    Hikino, Shin-ichi; Yunoki, Seiji

    2015-02-01

    We theoretically study the Josephson effect in a superconductor/normal metal/superconductor (S/N/S) Josephson junction composed of s-wave Ss with N which is sandwiched by two ferromagnetic insulators (Fs), forming a spin valve, in the vertical direction of the junction. We show that the 0-π transition of the Josephson critical current occurs with increasing the thickness of N along the junction. This transition is due to the magnetic proximity effect (MPE) which induces ferromagnetic magnetization in the N. Moreover, we find that, even for fixed thickness of N, the proposed Josephson junction with the spin valve can be switched from π to 0 states and vice versa by varying the magnetization configuration (parallel or antiparallel) of two Fs. We also examine the effect of spin-orbit scattering on the Josephson critical current and argue that the 0-π transition found here can be experimentally observed within the current nanofabrication techniques, thus indicating a promising potential of this junction as a 0-π switching device operated reversibly with varying the magnetic configuration in the spin valve by, e.g., applying an external magnetic field. Our results not only provide possible applications in superconducting electronics but also suggest the importance of a fundamental concept of MPE in nanostructures of multilayer N/F systems.

  17. Proximity Effect in BSCCO Intrinsic Josephson Junctions Contacted with a Normal Metal Layer

    Science.gov (United States)

    Suzuki, Minoru; Koizumi, Masayuki; Ohmaki, Masayuki; Kakeya, Itsuhiro; Shukrinov, Yu. M.

    Superconductivity proximity effect is numerically evaluated based on McMillan's tunneling proximity model for a sandwich of a normal metal layer on top of the surface superconducting layer of intrinsic Josephson junctions in a Bi2Sr2CaCu2O8+δ (BSCCO) crystal. Due to the very thin thickness of 0.3 nm of the superconducting layer in IJJs, the surface layer is subject to influence of the proximity effect when the top layer is contacted with a normal metal layer. The effect manifests itself as a significant change in the characteristics of the IJJ surface Josephson junction. It is found that when the superconducting layer thickness is smaller than 0.6 nm, the pair potential reduces significantly, leading to an almost complete suppression of the critical Josephson current density for the surface junction. This result can partly explain the experimental results on the IJJ characteristics of a mesa type structure.

  18. TNF-α regulates the proteolytic degradation of ST6Gal-1 and endothelial cell-cell junctions through upregulating expression of BACE1

    Science.gov (United States)

    Deng, Xiao; Zhang, Jun; Liu, Yan; Chen, Linmu; Yu, Chao

    2017-01-01

    Endothelial dysfunction and monocyte adhesion to vascular endothelial cells are two critical steps in atherosclerosis development, and emerging evidence suggests that protein sialylation is involved in these processes. However, the mechanism underlying this phenomenon remains incompletely elucidated. In this study, we demonstrated that treatment with the proinflammatory cytokine TNF-α disrupted vascular endothelial cell-cell tight junctions and promoted monocyte endothelial cell adhesion. Western blotting and Sambucus nigra lectin (SNA) blotting analyses revealed that TNF-α treatment decreased α-2, 6-sialic acid transferase 1 (ST6Gal-I) levels and downregulated VE-Cadherin α-2, 6 sialylation. Further analysis demonstrated that TNF-α treatment upregulated β-site amyloid precursor protein enzyme 1 (BACE1) expression, thus resulting in sequential ST6Gal-I proteolytic degradation. Furthermore, our results revealed that PKC signaling cascades were involved in TNF-α-induced BACE1 upregulation. Together, these results indicated that the proinflammatory cytokine TNF-α impairs endothelial tight junctions and promotes monocyte-endothelial cell adhesion by upregulating BACE1 expression through activating PKC signaling and sequentially cleaving ST6Gal-I. Thus, inhibition of BACE1 expression may be a new approach for treating atherosclerosis. PMID:28091531

  19. Possible resonance effect of axionic dark matter in Josephson junctions.

    Science.gov (United States)

    Beck, Christian

    2013-12-06

    We provide theoretical arguments that dark-matter axions from the galactic halo that pass through Earth may generate a small observable signal in resonant S/N/S Josephson junctions. The corresponding interaction process is based on the uniqueness of the gauge-invariant axion Josephson phase angle modulo 2π and is predicted to produce a small Shapiro steplike feature without externally applied microwave radiation when the Josephson frequency resonates with the axion mass. A resonance signal of so far unknown origin observed by C. Hoffmann et al. [Phys. Rev. B 70, 180503(R) (2004)] is consistent with our theory and can be interpreted in terms of an axion mass m(a)c2=0.11  meV and a local galactic axionic dark-matter density of 0.05  GeV/cm3. We discuss future experimental checks to confirm the dark-matter nature of the observed signal.

  20. Tunnel Field-Effect Transistor with Epitaxially Grown Tunnel Junction Fabricated by Source/Drain-First and Tunnel-Junction-Last Processes

    Science.gov (United States)

    Morita, Yukinori; Mori, Takahiro; Migita, Shinji; Mizubayashi, Wataru; Tanabe, Akihito; Fukuda, Koichi; Masahara, Meishoku; Ota, Hiroyuki

    2013-04-01

    We fabricate p- and n-channel Si tunnel field-effect transistors (TFETs) with an epitaxially grown tunnel junction. In a novel source/drain-first and tunnel-junction-last fabrication process, a thin epitaxial undoped Si channel (epichannel) is deposited on a preferentially fabricated p- or n-type source area. The epichannel sandwiched by a gate insulator and a highly doped source well acts as a parallel-plate tunnel capacitor, which effectively multiplies drain current with an enlarged tunnel area. On the basis of its simple structure and easy fabrication, symmetric n- and p-transistor and complementary metal oxide semiconductor inverter operations were successfully demonstrated.

  1. Bias dependence of synergistic radiation effects induced by electrons and protons on silicon bipolar junction transistors

    Science.gov (United States)

    Liu, Chaoming; Li, Xingji; Yang, Jianqun; Ma, Guoliang; Xiao, Liyi

    2015-06-01

    Bias dependence on synergistic radiation effects caused by 110 keV electrons and 170 keV protons on the current gain of 3DG130 NPN bipolar junction transistors (BJTs) is studied in this paper. Experimental results indicate that the influence induced by 170 keV protons is always enhancement effect during the sequential irradiation. However, the influence induced by 110 keV electrons on the BJT under various bias cases is different during the sequential irradiation. The transition fluence of 110 keV electrons is dependent on the bias case on the emitter-base junction of BJT.

  2. Current voltage characteristics of intrinsic Josephson junctions with charge-imbalance effect

    Science.gov (United States)

    Shukrinov, Yu. M.; Mahfouzi, F.

    2007-09-01

    The current-voltage characteristics (IVC) of intrinsic Josephson junctions are numerically calculated taking into account the quasiparticle charge-imbalance effect. We solve numerically the full set of the equations including second order differential equations for phase differences, kinetic equations and generalized Josephson relations for a stack of Josephson junctions. The boundary conditions due to the proximity effect are used. We obtain the branch structure of IVC and investigate it as a function of disequilibrium parameter at different values of coupling constant and McCumber parameter. An increase in the disequilibrium parameter essentially changes the character of IVC at large values of McCumber parameter.

  3. Current-voltage characteristics of intrinsic Josephson junctions with charge-imbalance effect

    Energy Technology Data Exchange (ETDEWEB)

    Shukrinov, Yu.M. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Physical Technical Institute, Dushanbe 734063 (Tajikistan)], E-mail: shukrinv@theor.jinr.ru; Mahfouzi, F. [Institute for Advanced Studies in Basic Sciences, P.O. Box 45195-1159, Zanjan (Iran, Islamic Republic of)

    2007-09-01

    The current-voltage characteristics (IVC) of intrinsic Josephson junctions are numerically calculated taking into account the quasiparticle charge-imbalance effect. We solve numerically the full set of the equations including second order differential equations for phase differences, kinetic equations and generalized Josephson relations for a stack of Josephson junctions. The boundary conditions due to the proximity effect are used. We obtain the branch structure of IVC and investigate it as a function of disequilibrium parameter at different values of coupling constant and McCumber parameter. An increase in the disequilibrium parameter essentially changes the character of IVC at large values of McCumber parameter.

  4. dc Josephson Effect in s-Wave Superconductor/Ferromagnet Insulator/p-Wave Superconductor Junctions

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-Wei

    2007-01-01

    The Josephson currents in s-wave superconductor/ferromagnet insulator/p-wave superconductor(s/FI/p)junctions are calculated as a function of temperature and the phase taking into account the roughness scattering effect at interface.The phase dependence of the Josephson current I ( φ) between s-wave and px-wave superconductor is predicted to be sin(2φ).The ferromagnet scattering effect,the barrier strength,and the roughness strength at interface suppress the dc currents in s/FI/p junction.

  5. Measurement of Aharonov-Casher effect in a Josephson junction chain

    Science.gov (United States)

    Pop, Ioan Mihai; Lecocq, Florent; Pannetier, Bernard; Buisson, Olivier; Guichard, Wiebke

    2011-03-01

    We have recently measured the effect of superconducting phase-slips on the ground state of a Josephson junction chain and a rhombi chain. Here we report clear evidence of Aharonov-Casher effect in a chain of Josephson junctions. This phenomenon is the dual of the well known Aharonov-Bohm interference. Using a capacitively coupled gate to the islands of the chain, we induce oscillations of the supercurrent by tuning the polarization charges on the islands. We observe complex interference patterns for different quantum phase slip amplitudes, that we understand quantitatively as Aharonov-Casher vortex interferences. European STREP MIDAS.

  6. Spin-dependent thermoelectric effects in graphene-based superconductor junctions

    Science.gov (United States)

    Beiranvand, Razieh; Hamzehpour, Hossein

    2017-02-01

    Using the Bogoliubov-de Gennes formalism, we investigate the charge and spin-dependent thermoelectric effects in graphene-based superconductor junctions. The results demonstrate that despite normal-superconductor junctions, there is a temperature-dependent spin thermopower in both the graphene-based ferromagnetic-superconductor and ferromagnetic-Rashba spin-orbit region-superconductor junctions. It is also shown that in the presence of Rashba spin-orbit interaction, the charge and spin-dependent Seebeck coefficients reach their maximum up to 3.5 k B / e and 2.5 k B / e , respectively. Remarkably, these coefficients have a zero-point critical value with respect to the magnetic exchange field and chemical potential. This effect disappears when the Rashba coupling is absent. These results suggest that graphene-based superconductors can be used in spin-caloritronic devices.

  7. Bounds on the Effect of Progressive Structural Degradation

    DEFF Research Database (Denmark)

    Achtziger, Wolfgang; Bendsøe, Martin P; Taylor, John E.

    1997-01-01

    Problem formulations are presented for the evaluation of upper and lower bounds on the effect of progressive structural degradation. For the purposes of this study, degradation effect is measured by an increase in global structural compliance (flexibility). Thus the stated bounds are given simply...... by the maximum and minimum values, respectively, of the increase in compliance corresponding to a specified global interval of degradation. Solutions to these optimization problems identify the particular patterns of local degradation associated with the respective 'worst case' and 'least degrading...

  8. Quantum interference effects at room temperature in OPV-based single-molecule junctions

    DEFF Research Database (Denmark)

    Arroyo, Carlos R.; Frisenda, Riccardo; Moth-Poulsen, Kasper;

    2013-01-01

    Interference effects on charge transport through an individual molecule can lead to a notable modulation and suppression on its conductance. In this letter, we report the observation of quantum interference effects occurring at room temperature in single-molecule junctions based on oligo(3...

  9. Effects of neuroinflammation on glia-glia gap junctional intercellular communication: a perspective.

    Science.gov (United States)

    Kielian, Tammy; Esen, Nilufer

    2004-01-01

    Gap junctions serve as intercellular conduits that allow for the direct transfer of small molecular weight molecules (up to 1 kDa) including ions involved in cellular excitability, metabolic precursors, and second messengers. The observation of extensive intercellular coupling and large numbers of gap junctions in the central nervous system (CNS) suggests a syncytium-like organization of glial compartments. Inflammation is a hallmark of various CNS diseases such as bacterial and viral infections, multiple sclerosis, Alzheimer's disease, and cerebral ischemia. A general consequence of brain inflammation is reactive gliosis typified by astrocyte hypertrophy and proliferation of astrocytes and microglia. Changes in gap junction intercellular communication as reflected by alterations in dye coupling and connexin expression have been associated with numerous CNS inflammatory diseases, which may have dramatic implications on the survival of neuronal and glial populations in the context of neuroinflammation. A review of the effects of inflammatory products on glia-glia gap junctional communication and glial glutamate release is presented. In addition, the hypothesis of a "syncytial switch" based upon differential regulation of gap junction expression in astrocytes and microglia during normal CNS homeostasis and neuroinflammation is proposed.

  10. Direct observation of large quantum interference effect in anthraquinone solid-state junctions.

    Science.gov (United States)

    Rabache, Vincent; Chaste, Julien; Petit, Philippe; Della Rocca, Maria Luisa; Martin, Pascal; Lacroix, Jean-Christophe; McCreery, Richard L; Lafarge, Philippe

    2013-07-17

    Quantum interference in cross-conjugated molecules embedded in solid-state devices was investigated by direct current-voltage and differential conductance transport measurements of anthraquinone (AQ)-based large area planar junctions. A thin film of AQ was grafted covalently on the junction base electrode by diazonium electroreduction, while the counter electrode was directly evaporated on top of the molecular layer. Our technique provides direct evidence of a large quantum interference effect in multiple CMOS compatible planar junctions. The quantum interference is manifested by a pronounced dip in the differential conductance close to zero voltage bias. The experimental signature is well developed at low temperature (4 K), showing a large amplitude dip with a minimum >2 orders of magnitude lower than the conductance at higher bias and is still clearly evident at room temperature. A temperature analysis of the conductance curves revealed that electron-phonon coupling is the principal decoherence mechanism causing large conductance oscillations at low temperature.

  11. [Effects of nitrogen and phosphorus fertilizer on atrazine degradation and detoxification by degrading strain HB-5].

    Science.gov (United States)

    Su, Jun; Zhu, Lu-Sheng; Li, Xu-Hua; Wang, Jun; Xie, Hui; Wang, Jin-Hua; Wang, Qi; Jia, Wen-Tao

    2010-10-01

    An atrazine-degrading strain HB-5 was used as a bacteria for biodegradation. Treatments of soil with nitrogen single, phosphate single and nitrogen phosphate together with HB-5 were carried out for degradation and eco-toxicity test; then, relationship between atrazine degradation rate and soil available nitrogen, available phosphorus were discussed. Atrazine residues were determined by HPLC; available nitrogen was determined with alkaline hydrolysis diffusion method; available phosphorus was determined with 0.5 mol/L-NaHCO3 extraction and molybdenum stibium anti-color method, and toxicity test was carried out with micronucleus test of Vicia faba root tip cells. The results showed that: After separately or together application, nitrogenous and phosphorous fertilizers could significantly accelerate atrazine degradation than soil with HB-5 only. On day 5, the order of atrazine degradation was ANP > AP > AN > A; 7 days later, no statistically significant differences were found between treatments. The available nitrogen and phosphorus level in soil reduced as the degradation rate increased in the soil. The soil of eco-toxicity test results indicated that the eco-toxicity significantly reduced with the degradation of atrazine by HB-5, and the eco-toxicity on treatments of soil with fertilizer were all below the treatments without fertilizer. On day 5, the order of eco-toxicity was ANP atrazine degradation in soil but also could reduce the soil eco-toxicity effects that atrazine caused. All these results could be keystone of atrazine pollution remediation in contaminated soil in the future.

  12. Interaction of Ddc1 and RPA with single-stranded/double-stranded DNA junctions in yeast whole cell extracts: Proteolytic degradation of the large subunit of replication protein A in ddc1Δ strains.

    Science.gov (United States)

    Sukhanova, Maria V; D'Herin, Claudine; Boiteux, Serge; Lavrik, Olga I

    2014-10-01

    To characterize proteins that interact with single-stranded/double-stranded (ss/ds) DNA junctions in whole cell free extracts of Saccharomyces cerevisiae, we used [(32)P]-labeled photoreactive partial DNA duplexes containing a 3'-ss/ds-junction (3'-junction) or a 5'-ss/ds-junction (5'-junction). Identification of labeled proteins was achieved by MALDI-TOF mass spectrometry peptide mass fingerprinting and genetic analysis. In wild-type extract, one of the components of the Ddc1-Rad17-Mec3 complex, Ddc1, was found to be preferentially photocrosslinked at a 3'-junction. On the other hand, RPAp70, the large subunit of the replication protein A (RPA), was the predominant crosslinking product at a 5'-junction. Interestingly, ddc1Δ extracts did not display photocrosslinking of RPAp70 at a 5'-junction. The results show that RPAp70 crosslinked to DNA with a 5'-junction is subject to limited proteolysis in ddc1Δ extracts, whereas it is stable in WT, rad17Δ, mec3Δ and mec1Δ extracts. The degradation of the RPAp70-DNA adduct in ddc1Δ extract is strongly reduced in the presence of the proteasome inhibitor MG 132. We also addressed the question of the stability of free RPA, using anti-RPA antibodies. The results show that RPAp70 is also subject to proteolysis without photocrosslinking to DNA upon incubation in ddc1Δ extract. The data point to a novel property of Ddc1, modulating the turnover of DNA binding proteins such as RPAp70 by the proteasome.

  13. Negative differential thermal conductance and thermal rectification effects across a graphene-based superconducting junction

    Science.gov (United States)

    Zhou, Xingfei; Zhang, Zhi

    2016-05-01

    We study the heat transport in a graphene-based normal-superconducting junction by solving the Bogoliubov-de Gennes (BdG) equation. There are two effects, the competitive and cooperative effects, which come from the interaction between the temperature-dependent energy-gap function in the superconducting region and the occupation difference of quasiparticles. It is found that the competitive effect can not only bring the negative differential thermal conductance effect but also the thermal rectification effect. By contrast, the cooperative effect just causes the thermal rectification effect. Furthermore, the thermal rectification ratio and the magnitude of heat current should be seen as two inseparable signs for characterizing the thermal rectification effect. These discoveries can add more application for the graphene-based superconducting junction, such as heat diode and heat transistor, at cryogenic temperatures.

  14. Impact of exchange-correlation effects on the IV characteristics of a molecular junction

    DEFF Research Database (Denmark)

    Thygesen, Kristian Sommer

    2008-01-01

    The role of exchange-correlation effects in nonequilibrium quantum transport through molecular junctions is assessed by analyzing the IV curve of a generic two-level model using self-consistent many-body perturbation theory (second Born and GW approximations) on the Keldysh contour...

  15. Effect of Junction Temperature Swing Durations on a Lifetime of a Transfer Molded IGBT Module

    DEFF Research Database (Denmark)

    Choi, Uimin; Blaabjerg, Frede; Jorgensen, Soren

    2016-01-01

    In this paper, the effect of junction temperature swing duration on the lifetime of a transfer molded Intelligent Power IGBT Module is studied and a relevant lifetime factor is modeled. A temperature swing duration dependent lifetime factor is defined based on 38 accelerated power cycling test...

  16. Effect of gating and pressure on the electronic transport properties of crossed nanotube junctions: formation of a Schottky barrier

    Energy Technology Data Exchange (ETDEWEB)

    Havu, P; Hashemi, M J; Kaukonen, M; Nieminen, R M [Department of Applied Physics, Aalto University, PO Box 11100, FI-00076 Aalto (Finland); Seppaelae, E T [Nokia Research Center, Itaemerenkatu 11-13, FI-00180 Helsinki (Finland)

    2011-03-23

    The electronic transport properties of crossed carbon nanotube junctions are investigated using ab initio methods. The optimal atomic structures and the intertube distances of the junctions are obtained using van der Waals corrected density functional theory. The effect of gating on the intertube conductance of the junctions is explored, showing the charge accumulation to the nanotube contact and the charge depletion region at the metal-semiconductor Schottky contact. Finally, it is shown how the conductance of the junctions under the gate voltage is affected by pressure applied to the nanotube film. (fast track communication)

  17. Effect of Different Exercise Intensities on the Myotendinous Junction Plasticity.

    Directory of Open Access Journals (Sweden)

    Davide Curzi

    Full Text Available Myotendinous junctions (MTJs are anatomical regions specialized in transmission of contractile strength from muscle to tendon and, for this reason, a common site where acute injuries occur during sport activities. In this work we investigated the influence of exercise intensity on MTJ plasticity, as well as on the expression of insulin-like growth factor 1 (IGF-1 and transforming growth factor beta (TGF-β and their receptors in muscle and tendon. Three groups of rats were analyzed: control (CTRL, slow-runner (RUN-S and fast-runner (RUN-F trained using a treadmill. Ultrastructural and morphometric analyses of distal MTJs from extensor digitorum longus muscles have been performed. Contractile strength and hypertrophy were investigated by using in vivo tension recordings and muscle cross-sectional area (CSA analysis, respectively. mRNA levels of PGC-1α, vinculin, IGF-1Ea and TGF-β have been quantified in muscle belly, while IGF-1Ea, TGF-β and their receptors in tendon. Morphometry revealed an increased MTJ complexity and interaction surface between tissues in trained rats according to training intensity. CSA analysis excluded hypertrophy among groups, while muscle strength was found significantly enhanced in exercised rats in comparison to controls. In muscle tissue, we highlighted an increased mRNA expression of PGC-1α and vinculin in both trained conditions and of TGF-β in RUN-F. In tendon, we mainly noted an enhancement of TGF-β mRNA expression only in RUN-F group and a raise of Betaglycan tendon receptor mRNA levels proportional to exercise intensity. In conclusion, MTJ plasticity appears to be related to exercise intensity and molecular analysis suggests a major role played by TGF-β.

  18. Papain Degrades Tight Junction Proteins of Human Keratinocytes In Vitro and Sensitizes C57BL/6 Mice via the Skin Independent of its Enzymatic Activity or TLR4 Activation.

    Science.gov (United States)

    Stremnitzer, Caroline; Manzano-Szalai, Krisztina; Willensdorfer, Anna; Starkl, Philipp; Pieper, Mario; König, Peter; Mildner, Michael; Tschachler, Erwin; Reichart, Ursula; Jensen-Jarolim, Erika

    2015-07-01

    Papain is commonly used in food, pharmaceutical, textile, and cosmetic industries and is known to induce occupational allergic asthma. We have previously shown that the papain-like cysteine protease Dermatophagoides pteronyssinus 1 from house dust mite exhibits percutaneous sensitization potential. We aimed here to investigate the potential of papain itself in epicutaneous sensitization. The effects of papain on tight junction (TJ) proteins were tested in vitro in human primary keratinocytes. Using C57BL/6 wild-type and Toll-like receptor 4 (TLR4)-deficient mice, we analyzed the sensitization potential of papain, its effects on the skin barrier, and immune cell recruitment. Our results show that papain affects the skin barrier by increasing transepidermal water loss, degrading TJ proteins and inducing vasodilation. When topically applied, papain exhibited a high epicutaneous inflammatory potential by recruiting neutrophils, mast cells, and CD3-positive cells and by induction of a TH2-biased antibody response. However, its high potency for specific sensitization via the skin was TLR4 independent and, in spite of its capacity to degrade epidermal TJ proteins, does not rely on its enzymatic function. From our data, we conclude that papain has all features to act as a strong allergen via the skin.

  19. Effect of thioridazine on gap junction intercellular communication in connexin 43-expressing cells.

    Science.gov (United States)

    Matesic, D F; Abifadel, D N; Garcia, E L; Jann, M W

    2006-07-01

    Propagation of electrical activity between myocytes in the heart requires gap junction channels, which contribute to coordinated conduction of the heartbeat. Some antipsychotic drugs, such as thioridazine and its active metabolite, mesoridazine, have known cardiac conduction side-effects, which have resulted in fatal or nearly fatal clinical consequences in patients. The physiological mechanisms responsible for these cardiac side-effects are unknown. We tested the effect of thioridazine and mesoridazine on gap junction-mediated intercellular communication between cells that express the major cardiac gap junction subtype connexin 43. Micromolar concentrations of thioridazine and mesoridazine inhibited gap junction-mediated intercellular communication between WB-F344 epithelial cells in a dose-dependent manner, as measured by fluorescent dye transfer. Kinetic analyses demonstrated that inhibition by 10 micromol/L thioridazine occurred within 5 min, achieved its maximal effect within 1 h, and was maintained for at least 24 h. Inhibition was reversible within 1 h upon removal of the drug. Western blot analysis of connexin 43 in a membrane-enriched fraction of WB-F344 cells treated with thioridazine revealed decreased amounts of unphosphorylated connexin 43, and appearance of a phosphorylated connexin 43 band that co-migrated with a "hyperphosphorylated" connexin 43 band present in TPA-inhibited cells. When tested for its effects on cardiomyocytes isolated from neonatal rats, thioridazine decreased fluorescent dye transfer between colonies of beating myocytes. Microinjection of individual cells with fluorescent dye also showed inhibition of dye transfer in thioridazine-treated cells compared to vehicle-treated cells. In addition, thioridazine, like TPA, inhibited rhythmic beating of myocytes within 15 min of application. In light of the fact that the thioridazine and mesoridazine concentrations used in these experiments are in the range of those used clinically in

  20. Entamoeba histolytica EhCP112 Dislocates and Degrades Claudin-1 and Claudin-2 at Tight Junctions of the Intestinal Epithelium

    Directory of Open Access Journals (Sweden)

    Patricia Cuellar

    2017-08-01

    Full Text Available During intestinal invasion, Entamoeba histolytica opens tight junctions (TJs reflected by transepithelial electrical resistance (TEER dropping. To explore the molecular mechanisms underlying this, we studied in vitro and in vivo the damage produced by the recombinant E. histolytica cysteine protease (rEhCP112 on TJ functions and proteins. rEhCP112 reduced TEER in Caco-2 cells in a dose- and time-dependent manner; and EhCP112-overexpressing trophozoites provoked major epithelial injury compared to control trophozoites. rEhCP112 penetrated through the intercellular space, and consequently the ion flux increased and the TJs fence function was disturbed. However, macromolecular flux was not altered. Functional in vitro assays revealed specific association of rEhCP112 with claudin-1 and claudin-2, that are both involved in regulating ion flux and fence function. Of note, rEhCP112 did not interact with occludin that is responsible for regulating macromolecular flux. Moreover, rEhCP112 degraded and delocalized claudin-1, thus affecting interepithelial adhesion. Concomitantly, expression of the leaky claudin-2 at TJ, first increased and then it was degraded. In vivo, rEhCP112 increased intestinal epithelial permeability in the mouse colon, likely due to apical erosion and claudin-1 and claudin-2 degradation. In conclusion, we provide evidence that EhCP112 causes epithelial dysfunction by specifically altering claudins at TJ. Thus, EhCP112 could be a potential target for therapeutic approaches against amoebiasis.

  1. Effects of Biogenic Supplementation on Xenobiotic Degradation

    Directory of Open Access Journals (Sweden)

    Truong Van-Hieu

    2016-06-01

    Full Text Available Activated sludge acclimated to 2,4-D was used to degrade 2,4-D in batch reactions. Biogenic substrates of sucrose and peptone, in varying concentrations, separately and combined, were supplemented to the degradation reactions to find if, how and why biogenic supplementations were beneficial to the degradation of the xenobiotic. With the biogenic supplement as a variable and other reaction conditions, optimal constant supplementation schemes were found which suit as feasible ways for enhancing the degradation rate of 2,4-D. Among the number of supplementation combinations, the ones having optimal advantage were 50 mg/L of sucrose, 80 mg/L of peptone, each separately, and 20 mg/L sucrose and 40 mg/L peptone combined.

  2. Dicke-Josephson effect in a cross-typed triple-quantum-dot junction

    Science.gov (United States)

    Wang, Xiao-Qi; Yi, Guang-Yu; Gong, Wei-Jiang

    2016-12-01

    We investigate the Dicke-Josephson effect in a superconductor/triple-quantum-dot/superconductor junction in which the central dot is coupled to the superconductors. It is found that the Dicke effect can modulate the Josephson effect in a nontrivial way. In the noninteracting case, the Dicke effect induces a subpeak in the supercurrent spectrum around the energy zero point. When intradot interactions are taken into account, the role of the Dicke effect changes completely. Namely, it tends to suppress the π-phase current near the position of electron-hole symmetry. With the increase of the Coulomb strength, it has an opportunity to reverse the current direction. We thus conclude that the Dicke-Josephson effect is also an important part in describing the Josephson effect in coupled-dot junctions.

  3. Giant piezoelectric resistance effect of nanoscale zinc oxide tunnel junctions: first principles simulations.

    Science.gov (United States)

    Zhang, Genghong; Luo, Xin; Zheng, Yue; Wang, Biao

    2012-05-21

    Based on first principles simulations and quantum transport calculations, we have investigated in the present work the effect of the mechanical load on transport characteristics and the relative physical properties of nanoscale zinc oxide (ZnO) tunnel junctions, and verified an intrinsic giant piezoelectric resistance (GPR) effect. Our results show that the transport-relevant properties, e.g., the piezoelectric potential (piezopotential), built-in electric field, conduction band offset and electron transmission probability of the junction etc., can obviously be tuned by the applied strain. Accordingly, it is inspiring to find that the current-voltage characteristics and tunneling electro-resistance of the ZnO tunnel junction can significantly be adjusted with the strain. When the applied strain switches from -5% to 5%, an increase of more than 14 times in the tunneling current at a bias voltage of 1.1 V can be obtained. Meanwhile, an increase of up to 2000% of the electro-resistance ratio with respect to the zero strain state can be reached at the same bias voltage and with a 5% compression. According to our investigations, the giant piezoelectric resistance effect of nanoscale ZnO tunnel junctions exhibits great potential in exploiting tunable electronic devices. Furthermore, the methodology of strain engineering revealed in this work may shed light on the mechanical manipulations of electronic devices.

  4. Search for a proximity effect induced gap in gold/high T sub c junctions

    Energy Technology Data Exchange (ETDEWEB)

    Dessau, D.S.; Wells, B.O.; Shen, Z.; Spicer, W.E. (Stanford Electronics Laboratories, Stanford University, Stanford California 94305 (US)); Arko, A.J.; List, R.S. (Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (USA)); Olson, C.G. (Ames Laboratory, Iowa State University, Ames, Iowa 50011 (USA)); Eom, C.B.; Mitzi, D.B.; Kapitulnik, A.; Geballe, T.H. (Department of Applied Physics, Stanford University, Stanford, California 94305 (USA))

    1991-03-25

    We have used high-resolution photoemission spectroscopy to search for a proximity effect induced superconducting gap in gold overlayers on {ital c}-axis single crystals of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} and {ital a}-axis thin films of YBa{sub 2}Cu{sub 3}O{sub 7}. These two junction types give us a representative sampling of very well characterized near-ideal interfaces (gold/{ital c}-axis Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}) and junctions in which the geometry more strongly favors the existence of the proximity effect but the interfacial quality may not be as ideal (gold/{ital a}-axis YBa{sub 2}Cu{sub 3}O{sub 7}). In neither of these junction types did we observe any evidence for a proximity effect induced gap, and we place an upper limit of approximately 5 meV on its existence in the junctions that we have studied.

  5. Photovoltaic effect in few-layer black phosphorus PN junctions defined by local electrostatic gating.

    Science.gov (United States)

    Buscema, Michele; Groenendijk, Dirk J; Steele, Gary A; van der Zant, Herre S J; Castellanos-Gomez, Andres

    2014-01-01

    In conventional photovoltaic solar cells, photogenerated carriers are extracted by the built-in electric field of a semiconductor PN junction, defined by ionic dopants. In atomically thin semiconductors, the doping level can be controlled by the field effect, enabling the implementation of electrically tunable PN junctions. However, most two-dimensional (2D) semiconductors do not show ambipolar transport, which is necessary to realize PN junctions. Few-layer black phosphorus (b-P) is a recently isolated 2D semiconductor with direct bandgap, high mobility, large current on/off ratios and ambipolar operation. Here we fabricate few-layer b-P field-effect transistors with split gates and hexagonal boron nitride dielectric. We demonstrate electrostatic control of the local charge carrier type and density in the device. Illuminating a gate-defined PN junction, we observe zero-bias photocurrents and significant open-circuit voltages due to the photovoltaic effect. The small bandgap of the material allows power generation for illumination wavelengths up to 940 nm, attractive for energy harvesting in the near-infrared.

  6. Effect of bias condition on heavy ion radiation in bipolar junction transistors

    Institute of Scientific and Technical Information of China (English)

    Liu Chao-Ming; Li Xing-Ji; Geng Hong-Bin; Yang De-Zhuang; He Shi-Yu

    2012-01-01

    The characteristic degradations in a silicon NPN bipolar junction transistor (BJT) of 3DG142 type are examined under irradiation with 40-MeV chlorine (Cl) ions under forward,grounded,and reverse bias conditions,respectively.Different electrical parameters are in-situ measured during the exposure under each bias condition.From the experimental data,a larger variation of base current (IB) is observed after irradiation at a given value of base-emitter voltage (VBE),while the collector current is slightly affected by irradiation at a given VBE.The gain degradation is affected mostly by the behaviour of the base current.From the experimental data,the variation of current gain in the case of forward bias is much smaller than that in the other conditions.Moreover,for 3DG142 BJT,the current gain degradation in the case of reverse bias is more severe than that in the grounded case at low fluence,while at high fluence,the gain degradation in the reverse bias case becomes smaller than that in the grounded case.

  7. Effect of bias condition on heavy ion radiation in bipolar junction transistors

    Science.gov (United States)

    Liu, Chao-Ming; Li, Xing-Ji; Geng, Hong-Bin; Yang, De-Zhuang; He, Shi-Yu

    2012-08-01

    The characteristic degradations in a silicon NPN bipolar junction transistor (BJT) of 3DG142 type are examined under irradiation with 40-MeV chlorine (Cl) ions under forward, grounded, and reverse bias conditions, respectively. Different electrical parameters are in-situ measured during the exposure under each bias condition. From the experimental data, a larger variation of base current (IB) is observed after irradiation at a given value of base-emitter voltage (VBE), while the collector current is slightly affected by irradiation at a given VBE. The gain degradation is affected mostly by the behaviour of the base current. From the experimental data, the variation of current gain in the case of forward bias is much smaller than that in the other conditions. Moreover, for 3DG142 BJT, the current gain degradation in the case of reverse bias is more severe than that in the grounded case at low fluence, while at high fluence, the gain degradation in the reverse bias case becomes smaller than that in the grounded case.

  8. Radiation degradation of alginate and some results of biological effect of degraded alginate on plants

    Energy Technology Data Exchange (ETDEWEB)

    Hien, N.Q.; Hai, L.; Luan, L.Q.; Hanh, T.T. [Nuclear Research Institute, Dalat (Viet Nam); Nagasawa, Naotsugu; Yoshii, Fumio; Makuuchi, Keizo; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2000-03-01

    Radiation degradation yields (Gd) of alginate in aqueous solution with different concentration were determined by viscometry method. The relationship between Gd and the alginate concentration was found out as: Gd=33.5 x C{sup -0.68}, with C% (w/v) and dry alginate referred to C=100%. An empirical equation for preparing degraded alginate with the desired low viscometry average molecular weight (Mv) by radiation was proposed. Alginate extracted directly horn seaweed'Sagassum, degraded by radiation was used for field experiments and results of the biological effect on plants (tea, carrot, chrysanthemum) were presented. (author)

  9. Effect of intrinsic curvature and edge tension on the stability of binary mixed-membrane three-junctions

    Science.gov (United States)

    Gardner, Jasmine M.; Deserno, Markus; Abrams, Cameron F.

    2016-08-01

    We use a combination of coarse-grained molecular dynamics simulations and theoretical modeling to examine three-junctions in mixed lipid bilayer membranes. These junctions are localized defect lines in which three bilayers merge in such a way that each bilayer shares one monolayer with one of the other two bilayers. The resulting local morphology is non-lamellar, resembling the threefold symmetric defect lines in inverse hexagonal phases, but it regularly occurs during membrane fission and fusion events. We realize a system of junctions by setting up a honeycomb lattice, which in its primitive cell contains two hexagons and four three-line junctions, permitting us to study their stability as well as their line tension. We specifically consider the effects of lipid composition and intrinsic curvature in binary mixtures, which contain a fraction of negatively curved lipids in a curvature-neutral background phase. Three-junction stability results from a competition between the junction and an open edge, which arises if one of the three bilayers detaches from the other two. We show that the stable phase is the one with the lower defect line tension. The strong and opposite monolayer curvatures present in junctions and edges enhance the mole fraction of negatively curved lipids in junctions and deplete it in edges. This lipid sorting affects the two line tensions and in turn the relative stability of the two phases. It also leads to a subtle entropic barrier for the transition between junction and edge that is absent in uniform membranes.

  10. Effect of intrinsic curvature and edge tension on the stability of binary mixed-membrane three-junctions.

    Science.gov (United States)

    Gardner, Jasmine M; Deserno, Markus; Abrams, Cameron F

    2016-08-21

    We use a combination of coarse-grained molecular dynamics simulations and theoretical modeling to examine three-junctions in mixed lipid bilayer membranes. These junctions are localized defect lines in which three bilayers merge in such a way that each bilayer shares one monolayer with one of the other two bilayers. The resulting local morphology is non-lamellar, resembling the threefold symmetric defect lines in inverse hexagonal phases, but it regularly occurs during membrane fission and fusion events. We realize a system of junctions by setting up a honeycomb lattice, which in its primitive cell contains two hexagons and four three-line junctions, permitting us to study their stability as well as their line tension. We specifically consider the effects of lipid composition and intrinsic curvature in binary mixtures, which contain a fraction of negatively curved lipids in a curvature-neutral background phase. Three-junction stability results from a competition between the junction and an open edge, which arises if one of the three bilayers detaches from the other two. We show that the stable phase is the one with the lower defect line tension. The strong and opposite monolayer curvatures present in junctions and edges enhance the mole fraction of negatively curved lipids in junctions and deplete it in edges. This lipid sorting affects the two line tensions and in turn the relative stability of the two phases. It also leads to a subtle entropic barrier for the transition between junction and edge that is absent in uniform membranes.

  11. General anesthetics have differential inhibitory effects on gap junction channels and hemichannels in astrocytes and neurons.

    Science.gov (United States)

    Liu, Xinhe; Gangoso, Ester; Yi, Chenju; Jeanson, Tiffany; Kandelman, Stanislas; Mantz, Jean; Giaume, Christian

    2016-04-01

    Astrocytes represent a major non-neuronal cell population actively involved in brain functions and pathologies. They express a large amount of gap junction proteins that allow communication between adjacent glial cells and the formation of glial networks. In addition, these membrane proteins can also operate as hemichannels, through which "gliotransmitters" are released, and thus contribute to neuroglial interaction. There are now reports demonstrating that alterations of astroglial gap junction communication and/or hemichannel activity impact neuronal and synaptic activity. Two decades ago we reported that several general anesthetics inhibited gap junctions in primary cultures of astrocytes (Mantz et al., (1993) Anesthesiology 78(5):892-901). As there are increasing studies investigating neuroglial interactions in anesthetized mice, we here updated this previous study by employing acute cortical slices and by characterizing the effects of general anesthetics on both astroglial gap junctions and hemichannels. As hemichannel activity is not detected in cortical astrocytes under basal conditions, we treated acute slices with the endotoxin LPS or proinflammatory cytokines to induce hemichannel activity in astrocytes, which in turn activated neuronal hemichannels. We studied two extensively used anesthetics, propofol and ketamine, and the more recently developed dexmedetomidine. We report that these drugs have differential inhibitory effects on gap junctional communication and hemichannel activity in astrocytes when used in their respective, clinically relevant concentrations, and that dexmedetomidine appears to be the least effective on both channel functions. In addition, the three anesthetics have similar effects on neuronal hemichannels. Altogether, our observations may contribute to optimizing the selection of anesthetics for in vivo animal studies.

  12. Low-Frequency Noise Characterization of Ultra-shallow Gate N-channel Junction Field Effect Transistors

    NARCIS (Netherlands)

    Piccolo, G.; Sarubbi, F.; Vandamme, L.J.K.; Macucci, M.; Scholtes, T.L.M.; Nanver, L.K.

    2007-01-01

    A recently developed technique for ultra shallow pn junction formation has been applied for the fabrication of ring-gate n-channel junction field effect devices (JFET) devices. Several different geometries, gate formation parameters and channel doping profiles have been realized and characterized wi

  13. Effect of eccentricity on junction and junctionless based silicon nanowire and silicon nanotube FETs

    Science.gov (United States)

    Scarlet, S. Priscilla; Ambika, R.; Srinivasan, R.

    2017-07-01

    In this paper, the effect of eccentricity on Junction-based Silicon Nanowire FET, Junction-based Silicon Nanotube FET, Junctionless-based Silicon Nanowire FET, and Junctionless-based Silicon Nanotube FET is investigated. Three kinds of eccentric structures are considered here. The impact of eccentricity on effective gate oxide thickness thereby gate oxide capacitance, and effective channel width are studied using 3D numerical simulations. Average radius of an ellipse is used to generate a model which captures the impact of eccentricity on gate oxide capacitance, and verified using TCAD simulations in MOS nanowire structure. The impact of eccentricity on ON current (ION), OFF current (IOFF), ION/IOFF ratio, and Unity gain cutoff frequency are investigated. Eccentricity increases the effective gate oxide thickness, the effective channel width, ION, and IOFF but reduces ION/IOFF ratio.

  14. Correlation between amplitude of spin accumulation signals investigated by Hanle effect measurement and effective junction barrier height in CoFe/MgO/n{sup +}-Si junctions

    Energy Technology Data Exchange (ETDEWEB)

    Saito, Y., E-mail: yoshiaki.saito@toshiba.co.jp; Ishikawa, M.; Sugiyama, H.; Inokuchi, T. [Corporate Research and Development Center, Toshiba Corporation, 1, Komukai-Toshiba-cho, 212-8582 Kawasaki (Japan); Hamaya, K. [Graduate School of Engineering Science, Osaka University, 1-3, Machikaneyama-cho, Toyonaka city, Osaka 560-8531 (Japan); Tezuka, N. [Department of Materials Science, Graduate School of Engineering, Tohoku University, Sendai 980-8579 (Japan)

    2015-05-07

    Correlation between the amplitude of the spin accumulation signals and the effective barrier height estimated from the slope of the log (RA) - t{sub MgO} plot (RA: resistance area product, t{sub MgO}: thickness of MgO tunnel barrier) in CoFe/MgO/n{sup +}-Si junctions was investigated. The amplitude of spin accumulation signals increases with increasing effective barrier heights. This increase of the amplitude of spin accumulation is originated from the increase of the spin polarization (P{sub Si}) in Si. The estimated absolute values of P{sub Si} using three-terminal Hanle signals are consistent with those estimated by four-terminal nonlocal-magnetoresistance (MR) and two-terminal local-MR. To demonstrate large spin accumulation in Si bulk band and enhance the local-MR through Si channel, these results indicate that the increase of the effective barrier height at ferromagnet/(tunnel barrier)/n{sup +}-Si junction electrode is important.

  15. Effect of microwave irradiation on parametric resonance in intrinsic Josephson junctions

    OpenAIRE

    Gaafar, Mahmoud; Shukrinov, Yury

    2012-01-01

    The effect of microwave irradiation on the phase dynamics of intrinsic Josephson junctions in high temperature superconductors is investigated. We demonstrate the influence of microwave's amplitude variation on the current-voltage characteristics and on the time dependence (temporal oscillations) of the electric charge in the superconducting layers. A remarkable changing of the longitudinal plasma wavelength at parametric resonance is shown. We demonstrate an effect of the microwave radiation...

  16. Effect of microwave irradiation on parametric resonance in intrinsic Josephson junctions

    Science.gov (United States)

    Gaafar, Mahmoud; Shukrinov, Yury

    2013-08-01

    The effect of microwave irradiation on the phase dynamics of intrinsic Josephson junctions in high temperature superconductors is investigated. We demonstrate the influence of microwave’s amplitude variation on the current-voltage characteristics and on the time dependence (temporal oscillations) of the electric charge in the superconducting layers. A remarkable changing of the longitudinal plasma wavelength at parametric resonance is shown. We demonstrate an effect of the microwave radiation on the width of the parametric resonance region.

  17. Giant Peltier Effect in a Submicron-Sized Cu-Ni/Au Junction with Nanometer-Scale Phase Separation

    Science.gov (United States)

    Sugihara, Atsushi; Kodzuka, Masaya; Yakushiji, Kay; Kubota, Hitoshi; Yuasa, Shinji; Yamamoto, Atsushi; Ando, Koji; Takanashi, Koki; Ohkubo, Tadakatsu; Hono, Kazuhiro; Fukushima, Akio

    2010-06-01

    We observed a giant Peltier effect in a submicron Cu-Ni/Au junction. The Peltier coefficient was evaluated to be 480 mV at room temperature from the balance between Joule heating and the Peltier cooling effect in the junction, which is 40 times that expected from the Seebeck coefficients of bulk Au and Cu-Ni alloy. This giant cooling effect lowered the inner temperature of the junction by 160 K. Microstructure analysis with a three-dimensional atom probe suggested that the giant Peltier effect possibly originated from nanometer-scale phase separation in the Cu-Ni layer.

  18. Effect of sound on gap-junction-based intercellular signaling: Calcium waves under acoustic irradiation.

    Science.gov (United States)

    Deymier, P A; Swinteck, N; Runge, K; Deymier-Black, A; Hoying, J B

    2015-01-01

    We present a previously unrecognized effect of sound waves on gap-junction-based intercellular signaling such as in biological tissues composed of endothelial cells. We suggest that sound irradiation may, through temporal and spatial modulation of cell-to-cell conductance, create intercellular calcium waves with unidirectional signal propagation associated with nonconventional topologies. Nonreciprocity in calcium wave propagation induced by sound wave irradiation is demonstrated in the case of a linear and a nonlinear reaction-diffusion model. This demonstration should be applicable to other types of gap-junction-based intercellular signals, and it is thought that it should be of help in interpreting a broad range of biological phenomena associated with the beneficial therapeutic effects of sound irradiation and possibly the harmful effects of sound waves on health.

  19. Study of seed layer effect in nuclear battery with P-N diode junction

    Energy Technology Data Exchange (ETDEWEB)

    Uhm, Young Rang; Son, Kwang Jae; Lee, Jun Sig [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Choi, Byoung Gun [Kookmin Univ., Seoul (Korea, Republic of)

    2014-10-15

    A nuclear battery with diode junction is a device that converts nuclear radiation directly to electric power. The mechanism of a nuclear battery is same as the P-N junction diode for solar cell application. The photovoltaic is operated by converted photons to electrical energy in the junction. In betavoltaic battery, beta particles are collected and converted to electrical energy as similar principle as photovoltaic. A very low current, order of nano or micro amps, is generated in devices. If a radioisotope (RI) with a long halflife (over 50 years) is used, a lifetime of a power source is extended as long as halflife time of RI.. Some special applications require long-lived compact power sources. These include space equipment, sensors in remote locations (space, underground, etc.), and implantable medical devices. Conventionally, these sources rely on converting chemical energy to electricity. This means they require a large storage of chemical 'fuel' since the amount of energy released per reaction is small. The nuclear battery is a novel solution to solve the power needs of these applications. For the {sup 63}Ni beta-source we used, the half-life is 100.2 years. Hence, the power sources we describe could extend a system's operating life by several decades or even a century, during which time the system could gain learned behavior without worrying about the power turning off. Radioactive thin-film-based power sources also have energy density orders of magnitude higher than chemical-reaction-based energy sources. In this study, we fabricate nuclear battery using {sup 63}Ni source with diode junction, and studied seed layer effect for optimization of structure of p-n junction.

  20. Comparison of the magneto-Peltier and magneto-Seebeck effects in magnetic tunnel junctions

    Science.gov (United States)

    Shan, J.; Dejene, F. K.; Leutenantsmeyer, J. C.; Flipse, J.; Münzenberg, M.; van Wees, B. J.

    2015-07-01

    Understanding heat generation and transport processes in a magnetic tunnel junction (MTJ) is a significant step towards improving its application in current memory devices. Recent work has experimentally demonstrated the magneto-Seebeck effect in MTJs, where the Seebeck coefficient of the junction varies as the magnetic configuration changes from a parallel (P) to an antiparallel (AP) configuration. Here we report a study on its reciprocal effect, the magneto-Peltier effect, where the heat flow carried by the tunneling electrons is altered by changing the magnetic configuration of the MTJ. The magneto-Peltier signal that reflects the change in the temperature difference across the junction between the P and AP configurations scales linearly with the applied current in the small bias but is greatly enhanced in the large-bias regime, due to higher-order Joule heating mechanisms. By carefully extracting the linear response which reflects the magneto-Peltier effect, and comparing it with the magneto-Seebeck measurements performed on the same device, we observe results consistent with Onsager reciprocity. We estimate a magneto-Peltier coefficient of 13.4 mV in the linear regime using a three-dimensional thermoelectric model. Our result opens up the possibility of programmable thermoelectric devices based on the Peltier effect in MTJs.

  1. Phonon Hall Effect in Four-Terminal Junctions

    OpenAIRE

    Zhang, Lifa; Wang, Jian-Sheng; Li, Baowen

    2009-01-01

    Using an exact nonequilibrium Green's function formulism, the phonon Hall effect for paramagnetic dielectrics is studied in a four-terminal device setting. The temperature difference in the transverse direction of the heat current is calculated for two-dimensional models with the magnetic field perpendicular to the plane. We find a surprising result that the square lattice does not have the phonon Hall effect while a honeycomb lattice has. This can be explained by symmetry. The temperature di...

  2. Edge effects in the magnetic interference pattern of a ballistic SNS junction

    Science.gov (United States)

    Meier, Hendrik; Fal'ko, Vladimir I.; Glazman, Leonid I.

    2016-05-01

    We investigate the Josephson critical current Ic(Φ ) of a wide superconductor-normal metal-superconductor (SNS) junction as a function of the magnetic flux Φ threading it. Electronic trajectories reflected from the side edges alter the function Ic(Φ ) as compared to the conventional Fraunhofer-type dependence. At weak magnetic fields, B ≲Φ0/d2 , the edge effect lifts zeros in Ic(Φ ) and gradually shifts the minima of that function toward half-integer multiples of the flux quantum. At B >Φ0/d2 , the edge effect leads to an accelerated decay of the critical current Ic(Φ ) with increasing Φ . At larger fields, eventually, the system is expected to cross into a regime of "classical" mesoscopic fluctuations that is specific for wide ballistic SNS junctions with rough edges.

  3. Interaction effects in nonequilibrium transport properties of a four-terminal topological corner junction

    Science.gov (United States)

    Romeo, F.; Citro, R.

    2014-10-01

    We study the transport properties of a four-terminal corner junction made by etching a two-dimensional topological insulator to form a quantum point contact (QPC). The QPC geometry enables interboundary tunneling processes allowing for the coupling among states with different helicity, while the tight confinement in the QPC region activates charging effects leading to the Coulomb-blockade physics. Peculiar signatures of these effects are theoretically investigated using a scattering field theory modified to take into account the electron-electron interaction within a self-consistent mean field approach. The current-voltage characteristics and the current fluctuations (noise) are derived beyond the linear response regime. Universal aspects of the thermal noise of the corner junction made of helical matter are also discussed.

  4. Size and voltage dependence of effective anisotropy in sub-100-nm perpendicular magnetic tunnel junctions

    Science.gov (United States)

    Piotrowski, Stephan K.; Bapna, Mukund; Oberdick, Samuel D.; Majetich, Sara A.; Li, Mingen; Chien, C. L.; Ahmed, Rizvi; Victora, R. H.

    2016-07-01

    Magnetic tunnel junctions with perpendicular magnetic anisotropy are investigated using a conductive atomic force microscope. The 1.23 -nm Co40Fe40B20 recording layer coercivity exhibits a size dependence which suggests single-domain behavior for diameters ≤100 nm. Focusing on devices with diameters smaller than 100 nm, we determine the effect of voltage and size on the effective device anisotropy Keff using two different techniques. Keff is extracted both from distributions of the switching fields of the recording and reference layers and from measurement of thermal fluctuations of the recording layer magnetization when a field close to the switching field is applied. The results from both sets of measurements reveal that Keff increases monotonically with decreasing junction diameter, consistent with the size dependence of the demagnetization energy density. We demonstrate that Keff can be controlled with a voltage down to the smallest size measured, 64 nm.

  5. Nonideal Quantum Measurement Effects on the Switching Currents Distribution of Josephson Junctions

    CERN Document Server

    Pierro, Vincenzo

    2016-01-01

    The quantum character of Josephson junctions is ordinarily revealed through the analysis of the switching currents, i.e. the current at which a finite voltage appears: A sharp rise of the voltage signals the passage (tunnel) from a trapped state (the zero voltage solution) to a running state (the finite voltage solution). In this context, we investigate the probability distribution of the Josephson junctions switching current taking into account the effect of the bias sweeping rate and introducing a simple nonideal quantum measurements scheme. The measurements are modelled as repeated voltage samplings at discrete time intervals, that is with repeated projections of the time dependent quantum solutions on the static or the running states, to retrieve the probability distribution of the switching currents. The distribution appears to be immune of the quantum Zeno effect, and it is close to, but distinguishable from, the Wentzel-Kramers-Brillouin approximation. For energy barriers comparable to the quantum fund...

  6. Effects of Quantum Correction on Dynamical Phase Transition in a Single Species Bosonic Josephson Junction

    Institute of Scientific and Technical Information of China (English)

    TIAN Jing; QIU Hai-Bo

    2013-01-01

    In this paper,by employing Bogliubov backreaction method,we investigate quantum correction effects on dynamical phase transition in a single species bosonic Josephson junction induced by increasing nonlinear interaction.Compared with mean field theory results,we find that the transition point is shifted.The dynamical phase transition is accompanied by a change of the entanglement entropy,which is found to reach a maximum at the transition point of the mean field theory.

  7. Effect of Junction Temperature Swing Durations on a Lifetime of a Transfer Molded IGBT Module

    DEFF Research Database (Denmark)

    Choi, Uimin; Blaabjerg, Frede; Jorgensen, Soren

    2016-01-01

    In this paper, the effect of junction temperature swing duration on the lifetime of a transfer molded Intelligent Power IGBT Module is studied and a relevant lifetime factor is modeled. A temperature swing duration dependent lifetime factor is defined based on 38 accelerated power cycling test...... electrical conditions during the power cycling test. The analysis of the test results and the temperature swing duration dependent lifetime factor under different definitions and confidence levels are presented....

  8. Incidence angle and spectral effects on vertical junction silicon solar cell capacitance

    OpenAIRE

    2014-01-01

    The aim of this work is to present a theoretical study of a vertical junction silicon solar cell under monochromatic illumination. By solving the continuity equation and using a one-dimensional model in frequency modulation, we derive the analytical expressions of both excess minority carrier density and photovoltage. Based on these expressions, the solar cell capacitance was calculated; we then exhibited the effects of both illumination wavelength and incidence angle on the solar cell capaci...

  9. Evaluation of the performance degradation at PAFC effect of catalyst degradation on electrode performance

    Energy Technology Data Exchange (ETDEWEB)

    Nishizaki, K.; Uchida, H.; Watanabe, M. [Yamanashi Univ., Kofu (Japan)] [and others

    1996-12-31

    Aiming commercialization of Phosphoric Acid Fuel Cell (PAFC) power plant, many researches and developments have been contributed. Over 20000 hours operations have been demonstrated by many PAFC power plants. But there is no effective method for the estimation of lifetime of electrochemical cells without a practical long-term operation. Conducted by New Energy and Industrial Technology Development Organization (NEDO), cooperative research projects aiming development of PAFC lifetime estimation method have started since 1995 FY in Japan. As part of this project, this work has been performed to clarify basic phenomena of the performance degradation at PAFCs jointly by Yamanashi University, Phosphoric Acid Fuel Cell Technology Research Association (PAFC-TRA) and PAFC manufacturers (Toshiba Co., Mitsubishi Electric Co, Fuji Electric Co.). Among several main causes of the cell performance degradation, effects of catalyst degradation (reduction in metal surface area, dealloying, changes in catalyst support) on PAFC cathode performances are discussed in this work.

  10. Solvent effects on the AIBN forced degradation of cumene: Implications for forced degradation practices.

    Science.gov (United States)

    Nelson, Eric D; Thompson, Gina M; Yao, Ye; Flanagan, Holly M; Harmon, Paul A

    2009-03-01

    Solvent effects on the AIBN and ACVA forced degradation of cumene are explored. The degradant formation rates of the three cumene oxidative degradants, cumene hydroperoxide, acetophenone, and 2-phenyl-2-propanol are reported. The relative abundance and ratios of these three degradants provide insight into the fate of the peroxy radical oxidants generated by the forced stress system, and suggest that alkoxy radicals are actually a significant source of the observed reactivity. The presence of even 1% methanol in the forced stress solvent significantly quenches this alkoxy radical reactivity, dramatically reducing the overall degradation rate and leaving cumene hydroperoxide as the major product of the oxidation reaction. The origin of this significant solvent effect on the oxidation product distribution is shown to be related to the preferential H-atom abstraction from methanol and its trace impurities by any alkoxy radicals present in the reaction solution. The implications for these observations are explored with the intent of producing more predictive oxidative forced stress experiments.

  11. Backhopping effect in magnetic tunnel junctions: Comparison between theory and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Skowroński, Witold, E-mail: skowron@agh.edu.pl; Wrona, Jerzy; Stobiecki, Tomasz [AGH University of Science and Technology, Department of Electronics, Al. Mickiewicza 30, 30-059 Krakow (Poland); Ogrodnik, Piotr, E-mail: piotrogr@if.pw.edu.pl [Faculty of Physics, Warsaw University of Technology, Ul. Koszykowa 75, 00-662 Warsaw (Poland); Institute of Molecular Physics, Polish Academy of Sciences, Ul. Smoluchowskiego 17, 60-179 Poznań (Poland); Świrkowicz, Renata [Faculty of Physics, Warsaw University of Technology, Ul. Koszykowa 75, 00-662 Warsaw (Poland); Barnaś, Józef [Institute of Molecular Physics, Polish Academy of Sciences, Ul. Smoluchowskiego 17, 60-179 Poznań (Poland); Reiss, Günter [Thin Films and Physics of Nanostructures, Bielefeld University, 33615 Bielefeld (Germany); Dijken, Sebastiaan van [NanoSpin, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto (Finland)

    2013-12-21

    We report on magnetic switching and backhopping effects due to spin-transfer-torque in magnetic tunnel junctions. Experimental data on current-induced switching in junctions with a MgO tunnel barrier reveal random back-and-forth switching between magnetization states, which appears when the current direction favors the parallel magnetic configuration. The effect depends on the barrier thickness t{sub b} and is not observed in tunnel junctions with very thin MgO tunnel barriers, t{sub b} < 0.95 nm. The switching dependence on bias voltage and barrier thickness is explained in terms of the macrospin model, with the magnetization dynamics described by the modified Landau-Lifshitz-Gilbert equation. Numerical simulations indicate that the competition between in-plane and out-of-plane torque components can result in a non-deterministic switching behavior at high bias voltages, in agreement with experimental observations. When the barrier thickness is reduced, the overall coupling between the magnetic layers across the barrier becomes ferromagnetic, which suppresses the backhopping effect.

  12. Zeeman effects on Josephson current in d-wave superconductor/d-wave superconductor junctions

    Institute of Scientific and Technical Information of China (English)

    Liao Yan-Hua; Dong Zheng-Chao; Yin Zai-Feng; Fu Hao

    2008-01-01

    This paper solves a self-consistent equation for the d-wave superconducting gap and the effective exchange field in the mean-field approximation,and studies the Zeeman effects on the d-wave superconducting gap and thermodynamic potential.The Josephson currents in the d-wave superconductor(S)/insulating layer(I)/d-wave S junctions are calculated as a function of the temperature,exchange field,and insulating barrier strength under a Zeeman magnetic field on the two d-wave Ss.It is found that the Josephson critical currents in d-wave S/d-wave S junction to a great extent depend on the relative orientation of the effective exchange field of the two S electrodes,and the crystal orientation of the d-wave S.The exchange field under certain conditions can enhance the Josephson critical current in a d-wave S/I/d-wave S junction.

  13. Phonon Hall effect in four-terminal nano-junctions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Lifa; Wang Jiansheng; Li Baowen [Department of Physics and Centre for Computational Science and Engineering, National University of Singapore, 117546 Singapore (Singapore)], E-mail: phylibw@nus.edu.sg

    2009-11-15

    Using an exact nonequilibrium Green's function formulation, the phonon Hall effect (PHE) for paramagnetic dielectrics is studied in a nanoscale four-terminal device setting. The temperature difference in the transverse direction of the heat current is calculated for two-dimensional models with the magnetic field perpendicular to the plane. We find that there is a PHE in nanoscale paramagnetic dielectrics, the magnitude of which is comparable to millimeter scale experiments. If the dynamic matrix of the system satisfies mirror reflection symmetry, the PHE disappears. The Hall temperature difference changes sign if the magnetic field is sufficiently large or if the size increases.

  14. Effect of temperature and magnetic field on the photocurrent response of biomolecular bulk-hetero junction

    Science.gov (United States)

    Tajima, Hiroyuki; Sekiguchi, Yusuke; Matsuda, Masaki

    2012-02-01

    The photocurrent responses were investigated for the biomolecular bulk-hetero junction of chlorophyll α (Chl-α) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-1-phenyl-(6,6)C61 (PCBM) in the temperature range between 300 K and 1.5 K under the magnetic field up to 8 T. The chopped-light photocurrent decreases on lowering the temperature. Below 10 K, photocurrent decrease was observed under the applied magnetic field. Decay of the photocurrent observed at 10 K was ascribed to the formation of the charged trap under light irradiation. The magnetic field effect (MFE) observed in this device was found to be very similar to that observed in P3HT:PCBM bulk-hetero junction at low temperatures.

  15. An effect of temperature distribution on terahertz phase dynamics in intrinsic Josephson junctions

    Energy Technology Data Exchange (ETDEWEB)

    Asai, Hidehiro, E-mail: hd-asai@aist.go.jp; Kawabata, Shiro

    2013-11-15

    Highlights: •We calculate the temperature distribution in intrinsic Josephson junctions (IJJs). •We investigate the effect of temperature distribution on THz radiation from IJJs. •The Joule heating in the IJJs makes inhomogeneous temperature distribution. •The inhomogeneous temperature distribution strongly excites THz emission. -- Abstract: In this study, we numerically calculate the temperature distribution and the THz phase dynamics in the mesa-structured intrinsic Josephson junctions (IJJs) using the thermal diffusion equation and the Sine–Gordon equation. We observe that the temperature distribution has a broad peak around the center region of the IJJ mesa. Under a high external current, a “hot spot” where the temperature is locally higher than the superconducting critical temperature appears around this region. The transverse Josephson plasma wave is strongly excited by the inhomogeneous temperature distribution in the mesa. This gives rise to intense THz emission.

  16. Large lateral photovoltaic effect with ultrafast relaxation time in SnSe/Si junction

    Science.gov (United States)

    Wang, Xianjie; Zhao, Xiaofeng; Hu, Chang; Zhang, Yang; Song, Bingqian; Zhang, Lingli; Liu, Weilong; Lv, Zhe; Zhang, Yu; Tang, Jinke; Sui, Yu; Song, Bo

    2016-07-01

    In this paper, we report a large lateral photovoltaic effect (LPE) with ultrafast relaxation time in SnSe/p-Si junctions. The LPE shows a linear dependence on the position of the laser spot, and the position sensitivity is as high as 250 mV mm-1. The optical response time and the relaxation time of the LPE are about 100 ns and 2 μs, respectively. The current-voltage curve on the surface of the SnSe film indicates the formation of an inversion layer at the SnSe/p-Si interface. Our results clearly suggest that most of the excited-electrons diffuse laterally in the inversion layer at the SnSe/p-Si interface, which results in a large LPE with ultrafast relaxation time. The high positional sensitivity and ultrafast relaxation time of the LPE make the SnSe/p-Si junction a promising candidate for a wide range of optoelectronic applications.

  17. Phase retrapping in a φ Josephson junction: Onset of the butterfly effect

    Science.gov (United States)

    Menditto, R.; Sickinger, H.; Weides, M.; Kohlstedt, H.; Žonda, M.; Novotný, T.; Koelle, D.; Kleiner, R.; Goldobin, E.

    2016-05-01

    We investigate experimentally the retrapping of the phase in a φ Josephson junction upon return of the junction to the zero-voltage state. Since the Josephson energy profile U0(ψ ) in φ JJ is a 2 π periodic double-well potential with minima at ψ =±φ mod2 π , the question is at which of the two minima -φ or +φ the phase will be trapped upon return from a finite voltage state during quasistatic decrease of the bias current (tilt of the potential). By measuring the relative population of two peaks in escape histograms, we determine the probability of phase trapping in the ±φ wells for different temperatures. Our experimental results agree qualitatively with theoretical predictions. In particular, we observe an onset of the butterfly effect with an oscillating probability of trapping. Unexpectedly, this probability saturates at a value different from 50% at low temperatures.

  18. Effect of unequal injection rates on asymmetric exclusion processes with junction

    Institute of Scientific and Technical Information of China (English)

    Xiao Song; Liu Ming-Zhe; Wang Jian-Jun; Wang Hua

    2011-01-01

    In this paper, we investigate the effect of unequal injection rates on totally asymmetric simple exclusion processes (TASEPs) with a 2-input 1-output junction and parallel update. A mean-field approach is developed to deal with the junction that connects two sub-chains and the single main chain. We obtain the stationary particle currents, density profiles and phase diagrams. Interestingly, we find that the number of stationary-state phases is changeable depending on the value of α1 (α1 is the injection rate on the first sub-chain). When α1 > 1/3, there are seven stationary-state phases in the system, however when α1 < 1/3, only six stationary-state phases exist in the system. The theoretical calculations are shown to be in agreement with Monte Carlo simulations.

  19. Preliminary Studies on Chlorimuron Degradation in Soil by Effective Microogranisms

    Institute of Scientific and Technical Information of China (English)

    LIU Yaguang

    2006-01-01

    A wheat (Triticum aestivum L.) bioassay method was used for preliminary determination of chlorimuron degradation in soil by EM (effective microorganisms). Under the conditions of this study, chlorimuron half-life was greater than 30-50 days in soil containing different initial concentrations of chlorimuron. After adding EM, chlorimuron degradation half-life ranged from 10-15 days, which was about 15-30 days shorter than without EM. Chlorimuron phate and urea enhanced the ability of EM to degrade chlorimuron, but brown sugar had no significant effect.

  20. Weak Fermi Level Pinning Effect in Schottky Junction of α-MoTe2

    Science.gov (United States)

    Nakaharai, Shu; Yamamoto, Mahito; Ueno, Keiji; Tsukagoshi, Kazuhito

    Difficulty in hole injection from metal contacts to transition metal dichalcogenide (TMDC) semiconductors has been one of the most serious issues in the application of these 2D materials to future nanoelectronics, which is caused by the strong Fermi level pinning effect in the metal/TMDC Schottky junction. In this work, we found that the holes can be injected efficiently from a large work function metal of Pt to α-molybdenum ditelluride (α-MoTe2; 2H-type), a TMDC semiconductor. The Schottky barrier height for holes at the Pt/ α-MoTe2 interface was extracted to be 40 meV by the temperature dependence of back-gate modulated currents under the flat band condition at the junction, while the Schottky barrier for electrons in the junction with a small work function metal of Ti was found to be 50 meV. Considering the difference in the work functions of Pt and Ti, the Fermi level pinning effect in α-MoTe2 was found to be much weaker than that in other TMDC semiconductors such as MoS2. These results open a way to the realization of complementary type circuits in the 2D materials for future low-power consumption electronics. This work was supported by JSPS KAKENHI Grant Numbers 15K06006, 25107004.

  1. Large tunable image-charge effects in single-molecule junctions.

    Science.gov (United States)

    Perrin, Mickael L; Verzijl, Christopher J O; Martin, Christian A; Shaikh, Ahson J; Eelkema, Rienk; van Esch, Jan H; van Ruitenbeek, Jan M; Thijssen, Joseph M; van der Zant, Herre S J; Dulić, Diana

    2013-04-01

    Metal/organic interfaces critically determine the characteristics of molecular electronic devices, because they influence the arrangement of the orbital levels that participate in charge transport. Studies on self-assembled monolayers show molecule-dependent energy-level shifts as well as transport-gap renormalization, two effects that suggest that electric-field polarization in the metal substrate induced by the formation of image charges plays a key role in the alignment of the molecular energy levels with respect to the metal's Fermi energy. Here, we provide direct experimental evidence for an electrode-induced gap renormalization in single-molecule junctions. We study charge transport through single porphyrin-type molecules using electrically gateable break junctions. In this set-up, the position of the occupied and unoccupied molecular energy levels can be followed in situ under simultaneous mechanical control. When increasing the electrode separation by just a few ångströms, we observe a substantial increase in the transport gap and level shifts as high as several hundreds of meV. Analysis of this large and tunable gap renormalization based on atomic charges obtained from density functional theory confirms and clarifies the dominant role of image-charge effects in single-molecule junctions.

  2. Annealing effects and DLTS study on NPN silicon bipolar junction transistors irradiated by heavy ions

    Science.gov (United States)

    Liu, Chaoming; Li, Xingji; Yang, Jianqun; Rui, Erming

    2014-01-01

    Isochronal anneal sequences have been carried out on 3DG112 silicon NPN bipolar junction transistors (BJTs) irradiated with 20 MeV bromine (Br) heavy ions. The Gummel curve is utilized to characterize the annealing behavior of defects in both the emitter-base depletion region and the neutral base. We find that the base current (IB) decreases with the increasing annealing temperature, while the collector current (IC) remains invariable. The current gain varies slightly, when the annealing temperature (TA) is lower than 400 K, while varies rapidly at TAtransistor. Deep level transient spectroscopy (DLTS) data is used to assign the relative magnitude of each of the important defects. Based on the in situ electrical measurement and DLTS spectra, it is clear that the V2(-/0)+V-P traps are the main contribution to the degradation of current gain after the 20 MeV Br ions irradiation. The V2(-/0)+V-P peak has many of the characteristics expected for the current gain degradation.

  3. Annealing effects and DLTS study on NPN silicon bipolar junction transistors irradiated by heavy ions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chaoming; Li, Xingji, E-mail: lxj0218@hit.edu.cn; Yang, Jianqun; Rui, Erming

    2014-01-21

    Isochronal anneal sequences have been carried out on 3DG112 silicon NPN bipolar junction transistors (BJTs) irradiated with 20 MeV bromine (Br) heavy ions. The Gummel curve is utilized to characterize the annealing behavior of defects in both the emitter-base depletion region and the neutral base. We find that the base current (I{sub B}) decreases with the increasing annealing temperature, while the collector current (I{sub C}) remains invariable. The current gain varies slightly, when the annealing temperature (T{sub A}) is lower than 400 K, while varies rapidly at T{sub A}<450 K, and the current gain of the 3DG112 BJT annealing at 700 K almost restore to that of the pre-radiation transistor. Deep level transient spectroscopy (DLTS) data is used to assign the relative magnitude of each of the important defects. Based on the in situ electrical measurement and DLTS spectra, it is clear that the V{sub 2}(−/0)+V-P traps are the main contribution to the degradation of current gain after the 20 MeV Br ions irradiation. The V{sub 2}(−/0)+V-P peak has many of the characteristics expected for the current gain degradation.

  4. Effect of Single-Strand Break on Branch Migration and Folding Dynamics of Holliday Junctions

    Science.gov (United States)

    Palets, Dmytro; Lushnikov, Alexander Y.; Karymov, Mikhail A.; Lyubchenko, Yuri L.

    2010-01-01

    The Holliday junction (HJ), or four-way junction, is a central intermediate state of DNA for homologous genetic recombination and other genetic processes such as replication and repair. Branch migration is the process by which the exchange of homologous DNA regions occurs, and it can be spontaneous or driven by proteins. Unfolding of the HJ is required for branch migration. Our previous single-molecule fluorescence studies led to a model according to which branch migration is a stepwise process consisting of consecutive migration and folding steps. Folding of the HJ in one of the folded conformations terminates the branch migration phase. At the same time, in the unfolded state HJ rapidly migrates over entire homology region of the HJ in one hop. This process can be affected by irregularities in the DNA double helical structure, so mismatches almost terminate a spontaneous branch migration. Single-stranded breaks or nicks are the most ubiquitous defects in the DNA helix; however, to date, their effect on the HJ branch migration has not been studied. In addition, although nicked HJs are specific substrates for a number of enzymes involved in DNA recombination and repair, the role of this substrate specificity remains unclear. Our main goal in this work was to study the effect of nicks on the efficiency of HJ branch migration and the dynamics of the HJ. To accomplish this goal, we applied two single-molecule methods: atomic force microscopy and fluorescence resonance energy transfer. The atomic force microscopy data show that the nick does not prevent branch migration, but it does decrease the probability that the HJ will pass the DNA lesion. The single-molecule fluorescence resonance energy transfer approaches were instrumental in detailing the effects of nicks. These studies reveal a dramatic change of the HJ dynamics. The nick changes the structure and conformational dynamics of the junctions, leading to conformations with geometries that are different from those

  5. End-group Influence on the Frontier Molecular Orbital Reorganization in Molecular Junctions -- Effect on Thermopower

    Science.gov (United States)

    Balachandran, Janakiraman; Reddy, Pramod; Dunietz, Barry; Gavini, Vikram

    2014-03-01

    The frontier molecular orbital (FMO) reorganization and in turn on the thermopower of the aromatic molecules trapped between metal electrodes (aka molecular junctions) depends on two effects namely (1) the stabilization effect - due to the physical presence of the metal electrode atoms and (2) change in e-e interactions - due to end-group mediated charge transfer. The stabilization effect always reduces the FMO energies. The charge transfer effect increases the FMO energies in charge-gaining molecules, which in turn opposes the stabilization effect resulting in a small overall shift. However, the charge transfer effect decreases the FMO energies in charge-losing molecules, which in turn complements the stabilization effect resulting in a large overall downward shift. This hypothesis is validated by delineating the shifts due to stabilization and charge-transfer effects independently. Further we also demonstrate the generality of the hypothesis by applying it on a wide range of aromatic molecules with different length and end-groups. Finally, we also present computationally efficient strategies, based on the proposed mechanism, to quantitatively compute the FMO reorganization which in turn has potential for high throughput analysis of molecular junctions.

  6. Bounds on the Effect of Progressive Structural Degradation

    DEFF Research Database (Denmark)

    Achtziger, W.; Bendsøe, Martin P; Taylor, John E.

    1998-01-01

    Problem formulations are presented for the evaluation of upper and lower bounds on the effect of progressive structural degradation. For the purposes of this study, degradation effect is measured by an increase in global structural compliance (flexibility). Thus the slated bounds are given simply......, increasing values for the bound in this constraint track the evolution of local degradation. While the full exposition of the paper is written specifically for trussed structures, analogues for the more useful formulations are described as well for the treatment of continuum systems. Implementation...... of methods for computational solution are described in detail, and computational results are given for the bound solutions corresponding to evolution from a starting structure through to its fully degraded form. (C) 1998 Elsevier Science Ltd. All rights reserved....

  7. Effect of pair potential anisotropy on the electric charge transport in superconducting junctions

    Energy Technology Data Exchange (ETDEWEB)

    Herrera, W.; Nino, V. [Universidad Nacional de Colombia, Bogota (Colombia). Dept. de Fisica

    2000-07-01

    Through the solutions of the Bogoliubov-de Gennes equations we investigate the effect of the anisotropy of the pair potential on the differential conductance of N-S-I-N (N: normal metal, S: superconductor, I: insulator) junctions. We find oscillations in the conductance which in the isotropic case coincide with the Tomasch effect. The influence of different pair potential symmetries on the transport properties is analyzed in detail. In particular, different s-symmetries (isotropic, anisotropic, extended) and d-symmetries are considered. (orig.)

  8. Effect of coupling on scheme of hysteresis jumps in current-voltage characteristics of intrinsic Josephson junctions in high- superconductors

    OpenAIRE

    Shukrinov, Yu M.; Mahfouzi, F.

    2005-01-01

    We report the numerical calculations of the current-voltage characteristics of intrinsic Josephson junctions in high- superconductors. The charging effect at superconducting layers is taken into account. A set of equations is used to study the non-linear dynamics of the system. In framework of capacitively coupled Josephson junctions model we obtain the total number of branches using fixed initial conditions for phases and their derivatives. The influence of the coupling constant \\alpha on th...

  9. Effective passivation of exfoliated black phosphorus transistors against ambient degradation.

    Science.gov (United States)

    Wood, Joshua D; Wells, Spencer A; Jariwala, Deep; Chen, Kan-Sheng; Cho, EunKyung; Sangwan, Vinod K; Liu, Xiaolong; Lauhon, Lincoln J; Marks, Tobin J; Hersam, Mark C

    2014-12-10

    Unencapsulated, exfoliated black phosphorus (BP) flakes are found to chemically degrade upon exposure to ambient conditions. Atomic force microscopy, electrostatic force microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy are employed to characterize the structure and chemistry of the degradation process, suggesting that O2 saturated H2O irreversibly reacts with BP to form oxidized phosphorus species. This interpretation is further supported by the observation that BP degradation occurs more rapidly on hydrophobic octadecyltrichlorosilane self-assembled monolayers and on H-Si(111) versus hydrophilic SiO2. For unencapsulated BP field-effect transistors, the ambient degradation causes large increases in threshold voltage after 6 h in ambient, followed by a ∼ 10(3) decrease in FET current on/off ratio and mobility after 48 h. Atomic layer deposited AlOx overlayers effectively suppress ambient degradation, allowing encapsulated BP FETs to maintain high on/off ratios of ∼ 10(3) and mobilities of ∼ 100 cm(2) V(-1) s(-1) for over 2 weeks in ambient conditions. This work shows that the ambient degradation of BP can be managed effectively when the flakes are sufficiently passivated. In turn, our strategy for enhancing BP environmental stability will accelerate efforts to implement BP in electronic and optoelectronic applications.

  10. Effective Passivation of Exfoliated Black Phosphorus Transistors against Ambient Degradation

    Science.gov (United States)

    Wood, Joshua D.; Wells, Spencer A.; Jariwala, Deep; Chen, Kan-Sheng; Cho, EunKyung; Sangwan, Vinod K.; Liu, Xiaolong; Lauhon, Lincoln J.; Marks, Tobin J.; Hersam, Mark C.

    2014-12-01

    Unencapsulated, exfoliated black phosphorus (BP) flakes are found to chemically degrade upon exposure to ambient conditions. Atomic force microscopy, electrostatic force microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy are employed to characterize the structure and chemistry of the degradation process, suggesting that O2 saturated H2O irreversibly reacts with BP to form oxidized phosphorus species. This interpretation is further supported by the observation that BP degradation occurs more rapidly on hydrophobic octadecyltrichlorosilane self-assembled monolayers and on H-Si(111), versus hydrophilic SiO2. For unencapsulated BP field-effect transistors, the ambient degradation causes large increases in threshold voltage after 6 hours in ambient, followed by a ~10^3 decrease in FET current on/off ratio and mobility after 48 hours. Atomic layer deposited AlOx overlayers effectively suppress ambient degradation, allowing encapsulated BP FETs to maintain high on/off ratios of ~10^3 and mobilities of ~100 cm2/(V*s) for over two weeks in ambient. This work shows that the ambient degradation of BP can be managed effectively when the flakes are sufficiently passivated. In turn, our strategy for enhancing BP environmental stability will accelerate efforts to implement BP in electronic and optoelectronic applications.

  11. Stability of large-area molecular junctions

    NARCIS (Netherlands)

    Akkerman, Hylke B.; Kronemeijer, Auke J.; Harkema, Jan; van Hal, Paul A.; Smits, Edsger C. P.; de Leeuw, Dago M.; Blom, Paul W. M.

    The stability of molecular junctions is crucial for any application of molecular electronics. Degradation of molecular junctions when exposed to ambient conditions is regularly observed. In this report the stability of large-area molecular junctions under ambient conditions for more than two years

  12. Modeling the Effect of P-N Junction Depth on the Output of Planer and Rectangular Textured Solar Cells

    Directory of Open Access Journals (Sweden)

    F. Jahanshah

    2009-01-01

    Full Text Available Problem statement: High cost of the solar cells is one of the important limitations in extensively using of the photovoltaic panels. Thin monocrystalline silicon solar cell could be reduce the cost but lost the absorption efficiency. Surface texturing help to enhance absorption. Using of advance texturing by diffraction grating was suggested for high absorption. It is necessary to investigate the scattering effect of diffraction grating with other solar cell parameter for optimization. In first step we concentrate on p-n junction position impact by modeling. Approach: The effect of position of p-n junction on the output current for both micro rectangular texturing and planer surface in solar cell has been investigated by ray tracing. Modeling of nine pairs solar cells with the same texture and planer surfaces but with different p-n junction position are done by using Atlas software. The output short current is a criterion for determining of efficiency performance. By comparing of the short current for each pair we was find the impacts of texturing and p-n junction depth on the monocrystalline thin film. Results: Light scattering due to diffraction grating inside the silicon with rectangular depth of 5 µm and a range of 5-40 µm p-n junction depths are investigated. The difference of short current in textured to bare silicon showed the enhancement from 4-8 µA when the p-n junction depths vary from 5-45 µm. Conclusions: Comparison of short current output confirms the correlation between p-n junction depth and texturing. Advanced texturing improve the solar cell efficiency but the effectiveness change with the p-n junction depth and need a simultaneous optimization for getting the high efficiency solar cell.

  13. Effect of intravenous anesthetic propofol on synaptic vesicle exocytosis at the frog neuromuscular junction

    Institute of Scientific and Technical Information of China (English)

    Luciana Ferreira LEITE; Renato Santiago GOMEZ; Matheus de Castro FONSECA; Marcus Vinicius GOMEZ; Cristina GUATIMOSIM

    2011-01-01

    Aim: To investigate the presynaptic effects of propofol, a short-acting intravenous anesthetic, in the frog neuromuscular junction. Methods: Frog cutaneous pectoris nerve muscle preparations were prepared. A fluorescent tool (FM1-43) was used to visualize the effect of propofol on synaptic vesicle exocytosos in the frog neuromuscular junction. Results: Low concentrations of propofol, ranging from 10 to 25 μmol/L, enhanced spontaneous vesicle exocytosis monitored by FM1-43 in a Ca2+-dependent and Na+-independent fashion. Higher concentrations of propofol (50, 100, and 200 μmol/L) had no effect on spontaneous exocytosis. By contrast, higher concentrations of propofol inhibited the Na+-dependent exocytosis evoked by 4-aminopyri-dine but did not affect the Na+-independent exocytosis evoked by KCI. This action was similar and non-additive with that observed by tetrodotoxin, a Na+ channel blocker.Conclusion: Our data suggest that propofol has a dose-dependent presynaptic effect at the neuromuscular transmission which mayhelp to understand some of the clinical effects of this agent on neuromuscular function.

  14. Comparison of effective noise temperatures in YBa2BCu3O7-δ junctions

    DEFF Research Database (Denmark)

    Fischer, Gerd Michael; Mygind, Jesper; Pedersen, Niels Falsig

    1997-01-01

    The dc voltage response to 70 GHz radiation was measured for YBCO bicrystal junctions, step edge junctions and ramp edge junctions at temperatures from 4 K to 90 K. Employing the RSJ-model and assuming thermal noise, the Josephson radiation is about equal to the voltage difference of the voltage ...

  15. The effect of different electrodes on the electronic transmission of benzene junctions: Analytical approach

    Energy Technology Data Exchange (ETDEWEB)

    Mohebbi, Razie; Seyed-Yazdi, Jamileh, E-mail: j.seyedyazdi@vru.ac.ir

    2016-06-01

    In this paper we have investigated the electronic transmission of systems electrode–benzene–electrode using the Landauer approach. The effect of different electrodes made of metal (Au) and semiconductors (Si, TiO{sub 2}) is investigated. These three electrodes are compared between them and the results show that the electronic transmission of benzene junctions, when using semiconductor electrodes, is associated to a gap in transmission which is due to the electrodes band gap. As a consequence, a threshold voltage is necessary to obtain conducting channels.

  16. A novel 10-nm physical gate length double-gate junction field effect transistor

    Institute of Scientific and Technical Information of China (English)

    Hou Xiao-Yu; Huang Ru; Chen Gang; Liu Sheng; Zhang Xing; Yu Bin; Wang Yang-Yuan

    2008-01-01

    A novel double-gate (DG) junction field effect transistor (JFET) with depletion operation mode is proposed in this paper.Compared with the conventional DG MOSFET,the novel DG JFET can achieve excellent performance with square body design,which relaxes the requirement on silicon film thickness of DG devices.Moreover,due to the structural symmetry,both p-type and n-type devices can be realized on exactly the same structure,which greatly simplifies integration.It can reduce the delay by about 60% in comparison with the conventional DG MOSFETs.

  17. Nonlinear thermoelectric transport in single-molecule junctions: the effect of electron-phonon interactions

    Science.gov (United States)

    Zimbovskaya, Natalya A.

    2016-07-01

    In this paper, we theoretically analyze steady-state thermoelectric transport through a single-molecule junction with a vibrating bridge. The thermally induced charge current in the system is explored using a nonequilibrium Green function formalism. We study the combined effects of Coulomb interactions between charge carriers on the bridge and electron-phonon interactions on the thermocurrent beyond the linear response regime. It is shown that electron-vibron interactions may significantly affect both the magnitude and the direction of the thermocurrent, and vibrational signatures may appear.

  18. Coherence effects in S/I/N/I/FS tunnel junctions

    Institute of Scientific and Technical Information of China (English)

    Li Xiao-Wei

    2007-01-01

    The dc Josephson effect in superconductor/insulator/normal metal/insulator/ferromagnetic superconductor junctions has been studied. We calculate the dc Josephson current based on the Bogoliubov de Gennes equation. The Josephson current is derived as a function of exchange field in ferromagnetic superconductor, normal metal thickness and insulating barrier strength. It is found that there exists an oscillation relation between the critical Josephson current and the normal metal thickness. The oscillation amplitude decreases as the thickness of the normal metal increases or the exchange field augments.

  19. Study on Effect of Junction Temperature Swing Duration on Lifetime of Transfer Molded Power IGBT Modules

    DEFF Research Database (Denmark)

    Choi, Uimin; Blaabjerg, Frede; Jørgensen, Søren

    2017-01-01

    In this paper, the effect of junction temperature swing duration on lifetime of transfer molded power insulated gate bipolar transistor (IGBT) modules is studied and a relevant lifetime factor is modeled. This study is based on 39 accelerated power cycling test results under six different...... conditions by an advanced power cycling test setup, which allows tested modules to be operated under more realistic electrical conditions during the power cycling test. The analysis of the test results and the temperature swing duration dependent lifetime factor under different definitions and confidence...

  20. Magnetic oscillations driven by the spin Hall effect in 3-terminal magnetic tunnel junction devices.

    Science.gov (United States)

    Liu, Luqiao; Pai, Chi-Feng; Ralph, D C; Buhrman, R A

    2012-11-02

    We show that a direct current in a tantalum microstrip can induce steady-state magnetic oscillations in an adjacent nanomagnet through spin torque from the spin Hall effect (SHE). The oscillations are detected electrically via a magnetic tunnel junction (MTJ) contacting the nanomagnet. The oscillation frequency can be controlled using the MTJ bias to tune the magnetic anisotropy. In this 3-terminal device, the SHE torque and the MTJ bias therefore provide independent controls of the oscillation amplitude and frequency, enabling new approaches for developing tunable spin torque nano-oscillators.

  1. Effects of processing technologies combined with cell wall degrading enzymes on in vitro degradability of barley.

    Science.gov (United States)

    de Vries, S; Pustjens, A M; Schols, H A; Hendriks, W H; Gerrits, W J J

    2012-12-01

    Effects of processing technologies and cell wall degrading enzymes on in vitro degradation of barley were tested in a 5 × 2 factorial arrangement: 5 technologies (unprocessed, wet-milling, extrusion, autoclaving, and acid-autoclaving), with or without enzymes. Upper gastrointestinal tract digestion (Boisen incubation) and large intestinal fermentation (gas production technique) were simulated in duplicate. All technologies increased digestion of DM (13 to 43% units) and starch (22 to 51% units) during Boisen incubation, compared with the unprocessed control (P starch (≈ 20% units), and CP (≈ 10% units) in unprocessed and autoclaved barley (P starch present in the Boisen residues. In conclusion, wet-milling, extrusion, and acid-autoclaving improved in vitro starch and CP digestion in barley, which is related to the cell wall matrix disruption. Addition of xylanases and β-glucanases improved in vitro starch and CP digestion only in unprocessed barley or barley poorly affected by processing.

  2. Hall effect degradation of rail gun performance

    Science.gov (United States)

    Witalis, E. A.; Gunnarsson, Patrik

    1993-01-01

    The paper discusses the Hall effect and shows it to be significant in the low-density and high-field trailing part of a plasma armature. Without the Hall effect a simple armature model is derived. It exhibits properties expected from classical MHD theory and shows that the purely relativistic electric charge buildup on the rails is a fundamental gun property, leading to V(breech) = 1.5 V(muzzle). The mathematics involved in accounting for Hall effect phenomena is described. These are of two types: the Hall-skewing of the armature current and the superimposed plasma flow rotation. For decreasing gun current the two effects efficiently combine to eject armature plasma rearwards, thus creating conditions for arc separation and parasitic arcs.

  3. Concentrations and contractile effects of substance P in the human ampullary-isthmic junction.

    Science.gov (United States)

    Forman, A; Andersson, K E; Maigaard, S; Ulmsten, U

    1985-05-01

    From 20 women undergoing hysterectomy, strip preparations were isolated from the outer, longitudinal and the inner, circular smooth muscle layer of the ampullary-isthmic junction (AIJ), together with small arterial segments dissected as ring preparations from the root of the mesosalpinx. The specimens were mounted in organ baths and isometric tension was recorded. In addition, tissue concentrations of substance P (SP) in the ampulla, AIJ and utero-tubal junction were determined by radioimmunoassay. Tissue concentrations of SP expressed as pmol X g tissue-1 (wet weight, +/- SE) amounted to 3.09 +/- 1.40 in the utero-tubal junction, 1.08 +/- 0.299 in the AIJ and 0.742 +/- 0.299 in the ampulla. In strips of circular muscle, SP at concentrations of 10(-7) -3 X 10(-6) mol X l-1 elicited a combined phasic and tonic response and in longitudinal muscle a mainly tonic contraction was produced. In both tissues, contractions elicited by SP were rapidly abolished in calcium-free medium. Nifedipine abolished the phasic contraction elicited in circular muscle by SP while the tonic response was resistant. The contraction in longitudinal muscle was reduced by 20-30%. Vasoactive intestinal polypeptide (VIP) decreased tension in preparations contracted by SP, prostaglandin F2 alpha and K+-depolarization (124 mmol X l(-1). In unstimulated oviductal arterial preparations, SP had no effect, while the peptide induced a transient relaxation of noradrenaline contracted preparations, and slightly decreased tension of K+-depolarized vessels. The results suggest that SP may be involved in the control of motility of the human AIJ.

  4. Tunneling planer Hall effect in Ni81Fe19/Al2O3/Nix Fe1-x junction

    Institute of Scientific and Technical Information of China (English)

    陈慧余; 冯永嘉; 熊曹水

    1999-01-01

    Tunneling planer Hall (TPH) effect in Ni81Fe19/Al2O3/NixFe1-x trilayer junction is different from general planer Hall effect in single-layer film or two-layer junction. This effect concerns the spin-polarized transport, so that the TPH voltage depends on the angle between magnetic vectors of two ferromagnetic layers. The TPH effect is reported to be influenced by composition and magnetic properties of FM layers and the thickness of the insulating layer.

  5. Effect of inductive and capacitive coupling on the current-voltage characteristic and electromagnetic radiation from a system of Josephson junctions

    Science.gov (United States)

    Rahmonov, I. R.; Shukrinov, Yu. M.; Atanasova, P. Kh.; Zemlyanaya, E. V.; Bashashin, M. V.

    2017-01-01

    We have studied the current-voltage characteristic of a system of long Josephson junctions taking into account the inductive and capacitive coupling. The dependence of the average time derivative of the phase difference on the bias current and spatiotemporal dependences of the phase difference and magnetic field in each junction are considered. The possibility of branching of the current-voltage characteristic in the region of zero field step, which is associated with different numbers of fluxons in individual Josephson junctions, is demonstrated. The current-voltage characteristic of the system of Josephson junctions is compared with the case of a single junction, and it is shown that the observed branching is due to coupling between the junctions. The intensity of electromagnetic radiation associated with motion of fluxons is calculated, and the effect of coupling between junctions on the radiation power is analyzed.

  6. arXiv Effective horizons, junction conditions and large-scale magnetism

    CERN Document Server

    Giovannini, Massimo

    2017-08-05

    The quantum mechanical generation of hypermagnetic and hyperlectric fields in four-dimensional conformally flat background geometries rests on the simultaneous continuity of the effective horizon and of the extrinsic curvature across the inflationary boundary. The junction conditions for the gauge fields are derived in general terms and corroborated by explicit examples with particular attention to the limit of a sudden (but nonetheless continuous) transition of the effective horizon. After reducing the dynamics to a pair of integral equations related by duality transformations, we compute the power spectra and deduce a novel class of logarithmic corrections which turn out to be, however, numerically insignificant and overwhelmed by the conductivity effects once the gauge modes reenter the effective horizon. In this perspective the magnetogenesis requirements and the role of the postinflationary conductivity are clarified and reappraised. As long as the total duration of the inflationary phase is nearly minim...

  7. Nano-cross-junction effect on phonon transport in silicon nanowire cages

    Science.gov (United States)

    Ma, Dengke; Ding, Hongru; Meng, Han; Feng, Lei; Wu, Yue; Shiomi, Junichiro; Yang, Nuo

    2016-10-01

    Wave effects of phonons can give rise to controllability of heat conduction in nanostructures beyond that by particle scattering at surfaces and interfaces. In this paper, we propose a new class of three-dimensional nanostructures: a silicon-nanowire-cage (SiNWC) structure consisting of silicon nanowires (SiNWs) connected by nano-cross-junctions. We perform equilibrium molecular dynamics simulations and find an ultralow value of thermal conductivity of SiNWC, 0.173 W m-1K-1 , which is one order lower than that of SiNWs. By further modal analysis and atomistic Green's function calculations, we identify that the large reduction is due to significant phonon localization induced by the phonon local resonance and hybridization at the junction part in a wide range of phonon modes. This localization effect does not require the cage to be periodic, unlike the phononic crystals, and can be realized in structures that are easier to synthesize, for instance in a form of randomly oriented SiNW network.

  8. Enhanced spin Seebeck effect in a germanene p-n junction

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Jun [College of New Energy, Bohai University, Jinzhou 121013 (China); Chi, Feng [School of Physical Science and Technology, Inner Mongolia University, Huhehaote 010023 (China); College of Engineering, Bohai University, Jinzhou 121013 (China); Guo, Yong [Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China); Collaborative Innovation of Quantum Matter, Beijing (China)

    2014-12-28

    Spin Seebeck effect in a germanene p-n junction is studied by using the nonequilibrium Green's function method combined with the tight-binding Hamiltonian. We find that the thermal bias ΔT can generate spin thermopower when a local exchange field is applied on one edge of the germanene nano-ribbon. The magnitude of the spin thermopower can be modulated by the potential drop across the two terminals of the p-n junction. When the value of the potential drop is smaller than the spin-orbit interaction strength, the spin thermopower is enhanced by two orders of magnitude larger as compared to the case of zero p-n voltage. Optimal temperature corresponding to maximum spin thermopower is insensitive to the potential drop. In the p-n region, maximum spin thermopower can be obtained at relatively higher temperatures. When the value of the potential drop is larger than that of the spin-orbit interaction, however, the spin Seebeck effect decays rapidly with increasing potential drop or temperature. By optimizing the structure parameters, the magnitude of the spin thermopower can be remarkably enhanced due to the coexistence of the exchange field and the potential drop.

  9. Tunneling conductance through normal metal - superconductor junctions: effects of Rashba spin orbit coupling and magnetic field

    Science.gov (United States)

    Kapri, Priyadarshini; Ganguly, Sudin; Basu, Saurabh

    2016-10-01

    In a system consisting of a metal-(s-wave) superconductor junction, we study the conductance characteristics in presence of Rashba spin orbit coupling (RSOC) and an external magnetic field applied along the plane of the sample. With a selective inclusion of the Rashba coupling either in the metallic or in both we note that there is a distinct effect with regard to the magnitude of the Andreev peak that occurs at a biasing voltage lower than the superconducting gap energy. The height of the peak is sensitive to the RSOC (increases with increase in RSOC) for RSOC to be present only in the metallic region, (same is true when RSOC is present throughout the junction), while the peak height is fairly independent when RSOC is solely present in the superconducting region. The in-plane magnetic field has very interesting effects which show up in the form of having a conductance peak at zero bias, thereby making it possible to realize a Majorana bound state.

  10. [Mitigative effect of micribial degradation on autotoxicity of Panax ginseng].

    Science.gov (United States)

    Li, Yong; Long, Qi-Liang; Ding, Wan-Long; Zhao, Dong-Yue

    2014-08-01

    Continuously cropping obstacle restricts ginseng production and rational use of land resource severely, and autotoxicity is one of the most important factors. In our previous work, ginseng autotoxin degrading bacteria were isolated, in the present re- search, plate culturing method and traditional physiological and biochemical method were used to analyze biological indices and protective enzyme activities, in order to elucidate the mitigative effect of autotoxin degrading bacteria on autotoxicity of P. ginseng. Results indicated that, except for palmitic acid, autotoxicity of benzonic acid, diisobutyl phthalate, diisobutyl succinate, and 2,2-bis (4- hydroxyphenyl) propane on the growth of ginseng seeds was significantly alleviated after autotoxins degrading bacteria was inoculated, and which have no evident difference with control. Except for benzoic acid, enzyme activity of SOD, POD and CAT in other autotoxin degrading treatments decreased significantly. The present research showed that, microbial degradation could alleviate the autotoxicity of autotoxins on ginseng seeds effectively, and which will be helpful for the resolution of ginseng continuously cropping obstacle problem.

  11. The effects of temperature and pH bacterial degradation of latex ...

    African Journals Online (AJOL)

    The effects of temperature and pH bacterial degradation of latex paint in ... degradation of latex paint under humid condition by bacterial isolates was studied. ... can be preserved from bacterial contamination, deterioration and degradation by ...

  12. Effect of Mg-Al insertion on magnetotransport properties in epitaxial Fe/sputter-deposited MgAl2O4/Fe(001) magnetic tunnel junctions

    Science.gov (United States)

    Belmoubarik, Mohamed; Sukegawa, Hiroaki; Ohkubo, Tadakatsu; Mitani, Seiji; Hono, Kazuhiro

    2017-05-01

    We investigated the effect of an Mg-Al layer insertion at the bottom interface of epitaxial Fe/MgAl2O4/Fe(001) magnetic tunnel junctions (MTJs) on their spin-dependent transport properties. The tunnel magnetoresistance (TMR) ratio and differential conductance spectra for the parallel magnetic configuration exhibited clear dependence on the inserted Mg-Al thickness. A slight Mg-Al insertion (thickness 0.2 nm) induced a reduction of TMR ratios and featureless conductance spectra, indicating a degradation of the bottom-Fe/MgAl2O4 interface. Therefore, a minimal Mg-Al insertion was found to be effective to maximize the TMR ratio for a sputtered MgAl2O4-based MTJ.

  13. Effect of Mg-Al insertion on magnetotransport properties in epitaxial Fe/sputter-deposited MgAl2O4/Fe(001 magnetic tunnel junctions

    Directory of Open Access Journals (Sweden)

    Mohamed Belmoubarik

    2017-05-01

    Full Text Available We investigated the effect of an Mg-Al layer insertion at the bottom interface of epitaxial Fe/MgAl2O4/Fe(001 magnetic tunnel junctions (MTJs on their spin-dependent transport properties. The tunnel magnetoresistance (TMR ratio and differential conductance spectra for the parallel magnetic configuration exhibited clear dependence on the inserted Mg-Al thickness. A slight Mg-Al insertion (thickness 0.2 nm induced a reduction of TMR ratios and featureless conductance spectra, indicating a degradation of the bottom-Fe/MgAl2O4 interface. Therefore, a minimal Mg-Al insertion was found to be effective to maximize the TMR ratio for a sputtered MgAl2O4-based MTJ.

  14. Magneto Seebeck effect in Co-Fe-B/MgO/Co-Fe-B tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Walter, Marvin; Walowski, Jakob; Zbarsky, Vladyslav; Muenzenberg, Markus [I. Physikalisches Institut, Universitaet Goettingen (Germany); Drewello, Volker; Ebke, Daniel; Reiss, Guenter; Thomas, Andy [Department of Physics, Bielefeld University (Germany); Peretzki, Patrick; Seibt, Michael [IV. Physikalisches Institut, Universitaet Goettingen (Germany); Czerner, Michael; Bachmann, Michael; Heiliger, Christian [I. Physikalisches Institut, Universitaet Giessen (Germany)

    2011-07-01

    Co-Fe-B/MgO/Co-Fe-B devices showing a giant TMR effect are possible candidates for the generation of spin-currents by thermal heating. We present the observation of a magneto Seebeck effect in Co-Fe-B/MgO/Co-Fe-B magnetic tunnel junctions (MTJs). The effects could be used for thermal spin-injection and thermally driven spin-transfer torque. The samples presented in this work consist of a minimal pseudo-spin-valve stack with sputtered Ta and Co-Fe-B layers and an e-beam evaporated MgO barrier. The MTJs are heated by a diode laser which achieves powers of up to 100 mW and is focused onto the sample in a standard confocal microscope setup. The heating is simulated by finite element methods and the experimental results are compared with ab initio calculations of the magneto-thermoelectric power and of the spin-Seebeck coefficient.

  15. Numerical Simulation of Leakage Effect for Quantum NOT Operation on Three-Josephson-Junction Flux Qubit

    Institute of Scientific and Technical Information of China (English)

    WU Tao; LIU Jian-She; LI Zheng

    2006-01-01

    @@ Superconducting flux qubits with three Josephson junctions are promising candidates for the building blocks of a quantum computer. We have applied the imaginary time evolution method to study the model of this qubit accurately by calculating its wavefunctions and eigenenergies. Because such qubits are manipulated with magnetic lux microwave pulses, they might be irradiated into non-computational states, which is called the leakage effect.By the evolution of the density matrix of the qubit under either hard-shaped π-pulse or Gaussian-shaped π-pulse to carry out quantum NOT operation, it has been demonstrated that the leakage effect for a flux qubit is very small even for hard-shaped microwave pulses while Gaussian-shaped pulses may suppress the leakage effect to a negligible level.

  16. Effect of microwave irradiation on parametric resonance in intrinsic Josephson junctions

    Energy Technology Data Exchange (ETDEWEB)

    Gaafar, Mahmoud, E-mail: futech_ma7moudgaafer@yahoo.com [BLTP, JINR, Dubna, Moscow Region 141980 (Russian Federation); Department of Physics, Faculty of Science, Menoufya University (Egypt); Shukrinov, Yury [BLTP, JINR, Dubna, Moscow Region 141980 (Russian Federation); Max-Planck-Institute for the Physics of Complex Systems, 01187 Dresden (Germany)

    2013-08-15

    Highlights: ► We investigated the effect of microwave irradiation on the phase dynamics of IJJs. ► A remarkable changing of the wavelength of LPW at parametric resonance is shown. ► Appearance of an additional parametric resonance before Shapiro step is observed. -- Abstract: The effect of microwave irradiation on the phase dynamics of intrinsic Josephson junctions in high temperature superconductors is investigated. We demonstrate the influence of microwave’s amplitude variation on the current–voltage characteristics and on the time dependence (temporal oscillations) of the electric charge in the superconducting layers. A remarkable changing of the longitudinal plasma wavelength at parametric resonance is shown. We demonstrate an effect of the microwave radiation on the width of the parametric resonance region.

  17. Photoperiod-Dependent Effects of 4-tert-Octylphenol on Adherens and Gap Junction Proteins in Bank Vole Seminiferous Tubules

    Directory of Open Access Journals (Sweden)

    Anna Hejmej

    2013-01-01

    Full Text Available In the present study we evaluated in vivo and in vitro effects of 4-tert-octylphenol (OP on the expression and distribution of adherens and gap junction proteins, N-cadherin, β-catenin, and connexin 43 (Cx43, in testes of seasonally breeding rodents, bank voles. We found that in bank vole testes expression and distribution of N-cadherin, β-catenin, and Cx43 were photoperiod dependent. Long-term treatment with OP (200 mg/kg b.w. resulted in the reduction of junction proteins expressions (P<0.05, P<0.01 and their delocalization in the testes of males kept in long photoperiod, whereas in short-day animals slight increase of Cx43 (P<0.05, N-cadherin, and β-catenin (statistically nonsignificant levels was observed. Effects of OP appeared to be independent of FSH and were maintained during in vitro organ culture, indicating that OP acts directly on adherens and gap junction proteins in the testes. An experiment performed using an antiestrogen ICI 182,780 demonstrated that the biological effects of OP on β-catenin and Cx43 involve an estrogen receptor-mediated response. Taken together, in bank vole organization of adherens and gap junctions and their susceptibility to OP are related to the length of photoperiod. Alterations in cadherin/catenin and Cx43-based junction may partially result from activation of estrogen receptor α and/or β signaling pathway.

  18. Dynamic strain-induced giant electroresistance and erasing effect in ultrathin ferroelectric tunnel-junction memory

    Science.gov (United States)

    Yau, Hei-Man; Xi, Zhongnan; Chen, Xinxin; Wen, Zheng; Wu, Ge; Dai, Ji-Yan

    2017-06-01

    Strain engineering plays a critical role in ferroelectric memories. In this work, we demonstrate dynamic strain modulation on tunneling electroresistance in a four-unit-cell ultrathin BaTi O3 metal/ferroelectric/semiconductor tunnel junction by applying mechanical stress to the device. With an extra compressive strain induced by mechanical stress, which is dynamically applied beyond the lattice mismatch between the BaTi O3 layer and the Nb :SrTi O3 substrate, the ON/OFF current ratio increases significantly up to a record high value of 107, whereas a mechanical erasing effect can be observed when a tensile stress is applied. This dynamic strain engineering gives rise to an efficient modulation of ON/OFF ratio due to the variation of BaTi O3 polarization. This result sheds light on the mechanism of electroresistance in the ferroelectric tunnel junctions by providing direct evidence for polarization-induced resistive switching, and also provides another stimulus for memory state operation.

  19. Proximity effect in planar superconducting tunnel junctions containing Nb/NiCu superconductor/ferromagnet bilayers

    Science.gov (United States)

    Pepe, G. P.; Latempa, R.; Parlato, L.; Ruotolo, A.; Ausanio, G.; Peluso, G.; Barone, A.; Golubov, A. A.; Fominov, Ya. V.; Kupriyanov, M. Yu.

    2006-02-01

    We present experimental results concerning both the fabrication and characterization of superconducting tunnel junctions containing superconductor/ferromagnet (S/F) bilayers made by niobium (S) and a weak ferromagnetic Ni0.50Cu0.50 alloy. Josephson junctions have been characterized down to T=1.4K in terms of current-voltage I - V characteristics and Josephson critical current versus magnetic field. By means of a numerical deconvolution of the I - V data the electronic density of states on both sides of the S/F bilayer has been evaluated at low temperatures. Results have been compared with theoretical predictions from a proximity model for S/F bilayers in the dirty limit in the framework of Usadel equations for the S and F layers, respectively. The main physical parameters characterizing the proximity effect in the Nb/NiCu bilayer, such as the coherence length and the exchange field energy of the F metal, and the S/F interface parameters have been also estimated.

  20. Antineoplastic Effects of siRNA against TMPRSS2-ERG Junction Oncogene in Prostate Cancer.

    Directory of Open Access Journals (Sweden)

    Giorgia Urbinati

    Full Text Available TMPRSS2-ERG junction oncogene is present in more than 50% of patients with prostate cancer and its expression is frequently associated with poor prognosis. Our aim is to achieve gene knockdown by siRNA TMPRSS2-ERG and then to assess the biological consequences of this inhibition. First, we designed siRNAs against the two TMPRSS2-ERG fusion variants (III and IV, most frequently identified in patients' biopsies. Two of the five siRNAs tested were found to efficiently inhibit mRNA of both TMPRSS2-ERG variants and to decrease ERG protein expression. Microarray analysis further confirmed ERG inhibition by both siRNAs TMPRSS2-ERG and revealed one common down-regulated gene, ADRA2A, involved in cell proliferation and migration. The siRNA against TMPRSS2-ERG fusion variant IV showed the highest anti-proliferative effects: Significantly decreased cell viability, increased cleaved caspase-3 and inhibited a cluster of anti-apoptotic proteins. To propose a concrete therapeutic approach, siRNA TMPRSS2-ERG IV was conjugated to squalene, which can self-organize as nanoparticles in water. The nanoparticles of siRNA TMPRSS2-ERG-squalene injected intravenously in SCID mice reduced growth of VCaP xenografted tumours, inhibited oncoprotein expression and partially restored differentiation (decrease in Ki67. In conclusion, this study offers a new prospect of treatment for prostate cancer based on siRNA-squalene nanoparticles targeting TMPRSS2-ERG junction oncogene.

  1. A Lattice Boltzmann study of the effects of viscoelasticity on droplet formation in microfluidic cross-junctions

    CERN Document Server

    Gupta, Anupam

    2015-01-01

    Based on mesoscale lattice Boltzmann (LB) numerical simulations, we investigate the effects of viscoelasticity on the break-up of liquid threads in microfluidic cross-junctions, where droplets are formed by focusing a liquid thread of a dispersed (d) phase into another co-flowing continuous (c) immiscible phase. Working at small Capillary numbers, we investigate the effects of non-Newtonian phases in the transition from droplet formation at the cross-junction (DCJ) to droplet formation downstream of the cross-junction (DC) (Liu $\\&$ Zhang, ${\\it Phys. ~Fluids.}$ ${\\bf 23}$, 082101 (2011)). We will analyze cases with ${\\it Droplet ~Viscoelasticity}$ (DV), where viscoelastic properties are confined in the dispersed phase, as well as cases with ${\\it Matrix ~Viscoelasticity}$ (MV), where viscoelastic properties are confined in the continuous phase. Moderate flow-rate ratios $Q \\approx {\\cal O}(1)$ of the two phases are considered in the present study. Overall, we find that the effects are more pronounced in ...

  2. Analysing degradation effects in charge-redistribution SAR ADCs

    NARCIS (Netherlands)

    Khan, M.A.; Kerkhoff, Hans G.

    2013-01-01

    Aging-sensitive technology nodes that are resulting in performance degradations in their electronic system implementations require aging simulations in advance for a more dependable design. Simulating time-domain aging effects in these electronic systems, especially in complex analog and mixed-signa

  3. Analysing degradation effects in charge-redistribution SAR ADCs

    NARCIS (Netherlands)

    Khan, Muhammad Aamir; Kerkhoff, Hans G.

    2013-01-01

    Aging-sensitive technology nodes that are resulting in performance degradations in their electronic system implementations require aging simulations in advance for a more dependable design. Simulating time-domain aging effects in these electronic systems, especially in complex analog and mixed-signa

  4. Compositional Effects on Electromechanical Degradation of RAINBOW Actuators

    Science.gov (United States)

    Dausch, David E.; Wise, Stephanie A.

    1998-01-01

    The effect of ceramic composition on the electromechanical displacement degradation of RAINBOW (Reduced and Internally Biased Oxide Wafer) actuators was investigated. RAINBOWs were fabricated from commercially available PZT-5H and PZT-5A piezoelectric disks as well as from tape cast PLZT piezoelectric 7/65/35 and electrostrictive 9/65/35 compositions. Displacement properties were measured at low electric fields (10 to 13 kV/cm) under loads of 0 to 500 g, and displacement degradation as a function of time was observed over 107 cycles. The PZT-5A and PLZT 9/65/35 compositions exhibited minimal decrease in displacement when load was applied. Furthermore, these compositions retained approximately 65 percent of their initial displacement after 10(exp 7) cycles under a load of 300 g. PZT-5H and PLZT 7/65/35 degraded completely under these conditions.

  5. Effect of chemical degradation on fluxes of reactive compounds

    Directory of Open Access Journals (Sweden)

    J. Rinne

    2011-12-01

    Full Text Available In the analyses of VOC fluxes measured above plant canopies, one usually assumes the flux above canopy to equal the emission at the surface. Thus one assumes the chemical degradation to be much slower than the turbulent transport. We used a stochastic Lagrangian transport model in which the chemical degradation was described as first order decay in order to study the effect of the chemical degradation on above canopy fluxes of chemically reactive species. With the model we explored the sensitivity of the ratio of the above canopy flux to the surface emission on several parameters such as chemical lifetime of the compound, friction velocity, stability, and canopy density. Our results show that friction velocity and chemical lifetime affected the loss during transport the most. The canopy density had a significant effect if the chemically reactive compound was emitted from the forest floor. We used the results of the simulations together with oxidant data measured during HUMPPA-COPEC-2010 campaign at a Scots pine site to estimate the effect of the chemistry on fluxes of three typical biogenic VOCs, isoprene, α-pinene, and β-caryophyllene. Of these, the chemical degradation had a~major effect on the fluxes of the most reactive species β-caryophyllene, while the fluxes of α-pinene were affected during nighttime. For these two compounds representing the mono- and sesquiterpenes groups, the effect of chemical degradation had also a significant diurnal cycle with the highest chemical loss at night. The different day and night time loss terms need to be accounted for, when measured fluxes of reactive compounds are used to reveal relations between primary emission and environmental parameters.

  6. Time-resolved measurement of the tunnel magneto-Seebeck effect in a single magnetic tunnel junction.

    Science.gov (United States)

    Boehnke, Alexander; Walter, Marvin; Roschewsky, Niklas; Eggebrecht, Tim; Drewello, Volker; Rott, Karsten; Münzenberg, Markus; Thomas, Andy; Reiss, Günter

    2013-06-01

    Recently, several groups have reported spin-dependent thermoelectric effects in magnetic tunnel junctions. In this paper, we present a setup for time-resolved measurements of thermovoltages and thermocurrents of a single micro- to nanometer-scaled tunnel junction. An electrically modulated diode laser is used to create a temperature gradient across the tunnel junction layer stack. This laser modulation technique enables the recording of time-dependent thermovoltage signals with a temporal resolution only limited by the preamplifier for the thermovoltage. So far, time-dependent thermovoltage could not be interpreted. Now, with the setup presented in this paper, it is possible to distinguish different Seebeck voltage contributions to the overall measured voltage signal in the μs time regime. A model circuit is developed that explains those voltage contributions on different sample types. Further, it will be shown that a voltage signal arising from the magnetic tunnel junction can only be observed when the laser spot is directly centered on top of the magnetic tunnel junction, which allows a lateral separation of the effects.

  7. Effect of FCCP on tight junction permeability and cellular distribution of ZO-1 protein in epithelial (MDCK) cells.

    Science.gov (United States)

    Li, C X; Poznansky, M J

    1990-12-14

    The effect of the uncoupler of oxidative phosphorylation, FCCP (carbonylcyanide p-trifluoromethoxyphenylhydrazone), on the tight junction of Madin-Darby canine kidney cells was examined. FCCP induced an abrupt decrease in the transepithelial electrical resistance of the confluent monolayers over a period of 20 s. When FCCP was withdrawn from the incubation medium, the monolayer resistance recovered to close to the original level in less than 2 h. Staining of the tight junction-associated protein ZO-1 showed that the changes in transepithelial electrical resistance were accompanied by a diffusing of the protein away from cell peripheries and a reconcentration to the tight junction areas following resistance recovery. Intracellular pH was decreased by FCCP on a similar time-scale with no obvious changes in ATP levels over this time-course. These data suggest that the uncoupler FCCP has a profound effect on tight junction permeability and cellular distribution of the tight junction protein ZO-1 in the epithelial cells and that it probably acts by breaking down proton gradients and altering intracellular pH.

  8. Magneto-Seebeck effect in magnetic tunnel junctions with perpendicular anisotropy

    Science.gov (United States)

    Ning, Keyu; Liu, Houfang; Ju, Zhenyi; Fang, Chi; Wan, Caihua; Cheng, Jinglei; Liu, Xiao; Li, Linsen; Feng, Jiafeng; Wei, Hongxiang; Han, Xiufeng; Yang, Yi; Ren, Tian-Ling

    2017-01-01

    As one invigorated filed of spin caloritronics combining with spin, charge and heat current, the magneto-Seebeck effect has been experimentally and theoretically studied in spin tunneling thin films and nanostructures. Here we analyze the tunnel magneto-Seebeck effect in magnetic tunnel junctions with perpendicular anisotropy (p-MTJs) under various measurement temperatures. The large tunnel magneto-Seebeck (TMS) ratio up to -838.8% for p-MTJs at 200 K is achieved, with Seebeck coefficient S in parallel and antiparallel states of 6.7 mV/K and 62.9 mV/K, respectively. The temperature dependence of the tunnel magneto-Seebeck can be attributed to the contributing transmission function and electron states at the interface between CoFeB electrode and MgO barrier.

  9. Magneto-Seebeck effect in magnetic tunnel junctions with perpendicular anisotropy

    Directory of Open Access Journals (Sweden)

    Keyu Ning

    2017-01-01

    Full Text Available As one invigorated filed of spin caloritronics combining with spin, charge and heat current, the magneto-Seebeck effect has been experimentally and theoretically studied in spin tunneling thin films and nanostructures. Here we analyze the tunnel magneto-Seebeck effect in magnetic tunnel junctions with perpendicular anisotropy (p-MTJs under various measurement temperatures. The large tunnel magneto-Seebeck (TMS ratio up to −838.8% for p-MTJs at 200 K is achieved, with Seebeck coefficient S in parallel and antiparallel states of 6.7 mV/K and 62.9 mV/K, respectively. The temperature dependence of the tunnel magneto-Seebeck can be attributed to the contributing transmission function and electron states at the interface between CoFeB electrode and MgO barrier.

  10. Giant electrocaloric effect in asymmetric ferroelectric tunnel junctions at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yang, E-mail: liuyangphy52@gmail.com; Infante, Ingrid C.; Dkhil, Brahim, E-mail: brahim.dkhil@ecp.fr [Laboratoire Structures, Propriétés et Modélisation des Solides, UMR 8580 CNRS-Ecole Centrale Paris, Grande Voie des Vignes, Châtenay-Malabry Cedex 92295 (France); Lou, Xiaojie [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, and State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China)

    2014-02-24

    Room-temperature electrocaloric properties of Pt/BaTiO{sub 3}/SrRuO{sub 3} ferroelectric tunnel junctions (FTJs) are studied by using a multiscale thermodynamic model. It is found that there is a divergence in the adiabatic temperature change ΔT for the two opposite polarization orientations. This difference under a typical writing voltage of 3 V can reach over 1 K as the barrier thickness decreases. Thanks to the ultrahigh external stimulus, a giant electrocaloric effect (1.53 K/V) with ΔT being over 4.5 K can be achieved at room temperature, which demonstrates the perspective of FTJs as a promising solid-state refrigeration.

  11. The effects of contact configurations on the rectification of dipyrimidinyl-diphenyl diblock molecular junctions

    Institute of Scientific and Technical Information of China (English)

    Zhang Guang-Ping; Hu Gui-Chao; Li Zong-Liang; Wang Chuan-Kui

    2011-01-01

    The transport properties of a conjugated dipyrimidinyl-diphenyl diblock oligomer sandwiched between two gold electrodes,as recently reported by [Díez-Pérez et al.Nature Chem.1 635 (2009)],are theoretically investigated using the fully self-consistent nonequilibrium Green's function method combined with density functional theory.Two kinds of symmetrical anchoring geometries are considered.Calculated current-voltage curves show that the contact structure has a strong effect on the rectification behaviour of the molecular diode.For the equilateral triangle configuration,pronounced rectification behaviour comparable to the experimental measurement is revealed,and the theoretical analysis indicates that the observed rectification characteristic results from the asymmetric shift of the perturbed molecular energy levels under bias voltage.While for the tetrahedron configuration,both rectification and negative differential conductivity behaviours are observed.The calculated results further prove the close dependence of the transporting characteristics of molecular junctions on contact configuration.

  12. Zeeman and spin-orbit effects in the Andreev spectra of nanowire junctions

    Science.gov (United States)

    van Heck, B.; Väyrynen, J. I.; Glazman, L. I.

    2017-08-01

    We study the energy spectrum and the electromagnetic response of Andreev bound states in short Josephson junctions made of semiconducting nanowires. We focus on the joint effect of Zeeman and spin-orbit coupling on the Andreev level spectra. Our model incorporates the penetration of the magnetic field in the proximitized wires, which substantially modifies the spectra. We pay special attention to the occurrence of fermion-parity switches at increasing values of the field and to the magnetic field dependence of the absorption strength of microwave-induced transitions. Our calculations can be used to extract quantitative information from microwave and tunneling spectroscopy experiments, such as the recently reported measurements in Van Woerkom et al. [Nat. Phys. (2017), doi:, 10.1038/nphys4150].

  13. Annealing effect on the reproducibility of Josephson Junctions made by ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Sirena, M; Matzen, S; Bergeal, N; Lesueur, J [Laboratoire Photons Et Matiere, CNRS, ESPCI, 10 Rue Vauquelin 75231 Paris (France) (France); Faini, G [Laboratoire de Photonique et Nanostructures, Route de Nozay, 91460 Marcoussis (France) (France); Bernard, R; Briatico, J; Crete, D [UMR-CNRS/THALES, Route D128, 91767 Palaiseau (France) (France)], E-mail: martin.sirena@espci.fr

    2008-02-01

    We have studied the annealing effects on the transport properties of High Tc Josephson Junctions (JJ) made by ion irradiation. Several JJ were measured for different annealing times and the experimental data were compared to numerical simulations. We have successfully used a vacancy-interstitial annihilation mechanism to describe the evolution of the JJ coupling temperature (T{sub J}) and the homogeneity of a JJ array, related to the evolution of the defects density mean value and its distribution width. For sufficient long annealing times (t > 600 min), {delta}T{sub J} was significatively reduced. This result appears to be very encouraging for future applications where the spread in JJ characteristics has to be as low as possible.

  14. Protonation effects on electron transport through diblock molecular junctions:A theoretical study

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Diblock oligomers are widely used in molecular electronics. Based on fully self-consistent nonequilib-rium Green’s function method and density functional theory, we study the electron transport properties of the molecular junction with a dipyrimidinyl-diphenyl (PMPH) diblock molecule sandwiched between two gold electrodes. Effects of different kinds of molecule-electrode anchoring geometry and protona-tion of the PMPH molecule are studied. Protonation leads to both conductance and rectification en-hancements. However, the experimentally observed rectifying direction inversion is not found in our calculation. The preferential current direction is always from the pyrimidinyl to the phenyl side. Our calculations indicate that the protonation of the molecular wire is not the only reason of the rectification inversion.

  15. Effects of hydrogen bonding on current-voltage characteristics of molecular junctions

    Science.gov (United States)

    Kula, Mathias; Jiang, Jun; Lu, Wei; Luo, Yi

    2006-11-01

    We present a first-principles study of hydrogen bonding effect on current-voltage characteristics of molecular junctions. Three model charge-transfer molecules, 2'-amino-4,4'-di(ethynylphenyl)-1-benzenethiolate (DEPBT-D), 4,4'-di(ethynylphenyl)-2'-nitro-1-benzenethiolate (DEPBT-A), and 2'-amino-4,4'-di(ethynylphenyl)-5'-nitro-1-benzenethiolate (DEPBT-DA), have been examined and compared with the corresponding hydrogen bonded complexes formed with different water molecules. Large differences in current-voltage characteristics are observed for DEPBT-D and DEPBT-A molecules with or without hydrogen bonded waters, while relatively small differences are found for DEPBT-DA. It is predicted that the presence of water clusters can drastically reduce the conductivities of the charge-transfer molecules. The underlying microscopic mechanism has been discussed.

  16. Effects of extremely low frequency magnetic fields on gap junctional intercellular communication and its mechanism

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The study on biological effect of electromagnetic fields has been paid close attention in recent years. Gap junctional intercellular communication (GJIC) plays an important role in the maintenance of cell proliferation and differentiation, and in the multistage process of carcinogenesis. A series of researches showed that xtremely low frequency (ELF) magnetic fields not only enhance the inhibition of GJIC induced by 12-O-tetradecanoylphorbol-13-acetate, but also inhibit GJIC directly when the intensity is equal to or more than 0.4  mT, and that the mechanisms of GJIC inhibition by ELF magnetic fields are due to hyperphosphorylation of connexin 43, which is mediated by protein kinase C-activated signal transduction, and the internalization of connexin 43 from plasma membrane to cytoplasm.

  17. Veselago lensing in graphene with a p-n junction: Classical versus quantum effects

    Energy Technology Data Exchange (ETDEWEB)

    Milovanović, S. P., E-mail: slavisa.milovanovic@uantwerpen.be; Moldovan, D., E-mail: dean.moldovan@uantwerpen.be; Peeters, F. M., E-mail: francois.peeters@uantwerpen.be [Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium)

    2015-10-21

    The feasibility of Veselago lensing in graphene with a p-n junction is investigated numerically for realistic injection leads. Two different set-ups with two narrow leads are considered with absorbing or reflecting side edges. This allows us to separately determine the influence of scattering on electron focusing for the edges and the p-n interface. Both semiclassical and tight-binding simulations show a distinctive peak in the transmission probability that is attributed to the Veselago lensing effect. We investigate the robustness of this peak on the width of the injector, the position of the p-n interface, and different gate potential profiles. Furthermore, the influence of scattering by both short- and long-range impurities is considered.

  18. Near-ultraviolet lateral photovoltaic effect in Fe3O4/3C-SiC Schottky junctions.

    Science.gov (United States)

    Song, Bingqian; Wang, Xianjie; Li, Bo; Zhang, Lingli; Lv, Zhe; Zhang, Yu; Wang, Yang; Tang, Jinke; Xu, Ping; Li, Bingsheng; Yang, Yanqiang; Sui, Yu; Song, Bo

    2016-10-17

    In this paper, we report a sensitive lateral photovoltaic effect (LPE) in Fe3O4/3C-SiC Schottky junctions with a fast relaxation time at near-ultraviolet wavelengths. The rectifying behavior suggests that the large build-in electric field was formed in the Schottky junctions. This device has excellent position sensitivity as high as 67.8 mV mm-1 illuminated by a 405 nm laser. The optical relaxation time of the LPE is about 30 μs. The fast relaxation and high positional sensitivity of the LPE make the Fe3O4/3C-SiC junction a promising candidate for a wide range of ultraviolet/near-ultraviolet optoelectronic applications.

  19. Alterations of intercellular junctions in peritoneal mesothelial cells from patients undergoing dialysis: effect of retinoic Acid.

    Science.gov (United States)

    Retana, Carmen; Sanchez, Elsa; Perez-Lopez, Alejandro; Cruz, Armando; Lagunas, Jesus; Cruz, Carmen; Vital, Socorro; Reyes, Jose L

    2015-01-01

    Dialysis patients are classified according to their peritoneal permeability as low transporter (LT, low solute permeability) or high transporter (HT, high solute permeability). Tight junction (TJ) proteins are critical to maintain ions, molecules and water paracellular transport through peritoneum. Exposure to peritoneal dialysis solutions causes damage to TJ in human peritoneal mesothelial cells (HPMCs). We analyzed the quantity, distribution and function of TJ proteins: claudin-1, -2 and -8, ZO-1 and occludin, in HPMC cultures from LT and HT patients. Since all-trans retinoic acid (ATRA) might modify the expression of TJ proteins, we studied its effect on HPMCs. Control HPMCs were isolated from human omentum, while HT or LT cells were obtained from dialysis effluents. Cells were cultured in presence of ATRA 0, 50 or 100 nM. Transepithelial electrical resistance (TER) measurement, immunostaining and Western blot analyses were performed. HT exhibited lower TER than control and LT monolayers. Immunofluorescence for TJ was weak and discontinuous along the cell contour, in LT and HT. Furthermore, claudin-1, occludin and ZO-1 expressions were decreased. In all groups, claudin-2 was localized at nuclei. We observed that ATRA improved TJ distribution and increased TJ expression in HT. This retinoid did not modify claudin-2 and -8 expressions. All-trans retinoic acid decreased TER in HT, but had no effect in LT. Tight junctions were altered in HPMCs from dialyzed patients. The HT monolayer has lower TER than LT, which might be associated with the peritoneal permeability in these patients. ATRA might be a therapeutic alternative to maintain mesothelial integrity, since it improved TJ localization and expression. Copyright © 2015 International Society for Peritoneal Dialysis.

  20. An investigation of the effect of grain size on some properties of intrinsic Josephson junction

    Energy Technology Data Exchange (ETDEWEB)

    Aslan Çataltepe, Özden, E-mail: ozdenaslan@yahoo.com [Gedik University, Faculty of Engineering, Yakacık/Kartal, 34876, İstanbul (Turkey); Güven Özdemir, Zeynep [Yıldız Technical University, Physics Department, Faculty of Science and Arts, Davutpaşa Campus, Esenler 34210, İstanbul (Turkey); Onbaşli, Ülker [University of Marmara, Physics Department, Faculty of Science and Arts, Rıdvanpaşa cad.3.sok., 85/12, 34730, Göztepe, İstanbul (Turkey)

    2013-08-15

    Highlights: ► Grain size, t, determined by SEM, has a key role for intrinsic Josephson Junctions. ► Supercurrent density and Josephson penetration depth are changed with variation of t. ► HgBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub 8+x} (Hg-1223) consists of intrinsic Josephson junction array. ► The effect of t on electrodynamics parameters of Hg-1223 was investigated by SEM. -- Abstract: Some superconducting parameters of the high temperature superconductors, such as the plasma frequency and the critical transition temperature, depend on the oxygen content of the material. Since the oxygen content is effective on the grain size of the system, the under, optimally and over oxygen doped Hg-based copper oxide layered superconductors, which have the hole type superconductivity, have been investigated in this study. As is known that the concentration of hole type carriers is increased via optimally oxygen annealing. In other words, relatively higher values for the various critical parameters are achieved by the optimally oxygen doping procedure. In this work, the grain sizes of the oxygen annealed samples have been investigated by Scanning Electron Microscopy (SEM). Moreover, the magnetization data obtained via Superconducting Interference Quantum Device (SQUID) has been utilized for calculation of critical current density, which is essential parameter for determining Josephson penetration depth. The Josephson penetration depths of the systems have been calculated by Lawrence–Doniach Model for high temperature superconductors. Since plasma frequency of the system is inversely proportional to Josephson penetration depth, the plasma frequencies of the various doping profiles have also been calculated for the high temperature superconductor investigated.

  1. Elimination of the channel current effect on the characterization of MOSFET threshold voltage using junction capacitance measurements

    Science.gov (United States)

    Tomaszewski, Daniel; Głuszko, Grzegorz; Łukasiak, Lidia; Kucharski, Krzysztof; Malesińska, Jolanta

    2017-02-01

    An alternative method for an extraction of the MOSFET threshold voltage has been proposed. It is based on an analysis of the MOSFET source-bulk junction capacitance behavior as a function of the gate-source voltage. The effect of the channel current on the threshold voltage extraction is fully eliminated. For the threshold voltage and junction capacitance model parameters non-iterative methods have been used. The proposed method has been demonstrated using a series of MOS transistors manufactured using a standard CMOS technology.

  2. Veterinary Antibiotic Effects on Atrazine Degradation and Soil Microorganisms.

    Science.gov (United States)

    Nordenholt, Rebecca M; Goyne, Keith W; Kremer, Robert J; Lin, Chung-Ho; Lerch, Robert N; Veum, Kristen S

    2016-03-01

    Veterinary antibiotics (VAs) in manure applied to agricultural lands may change agrichemical degradation by altering soil microbial community structure or function. The objectives of this study were to investigate the influence of two VAs, sulfamethazine (SMZ) and oxytetracycline (OTC), on atrazine (ATZ) degradation, soil microbial enzymatic activity, and phospholipid fatty acid (PLFA) markers. Sandy loam soil with and without 5% swine manure (w/w) was amended with 0 or 500 μg kgC radiolabeled ATZ and with 0, 100, or 1000 μg kg SMZ or OTC and incubated at 25°C in the dark for 96 d. The half-life of ATZ was not significantly affected by VA treatment in the presence or absence of manure; however, the VAs significantly ( degradation by 22%, reduced ATZ mineralization by 50%, and increased the half-life of ATZ by >10 d. The VAs had limited adverse effects on the microbial enzymes β-glucosidase and dehydrogenase in soils with and without manure. In contrast, manure application stimulated dehydrogenase activity and altered chlorinated ATZ metabolite profiles. Concentrations of PLFA markers were reduced by additions of ATZ, manure, OTC, and SMZ; adverse additive effects of combined treatments were noted for arbuscular mycorrhizal fungi and actinobacteria. In this work, the VAs did not influence persistence of the ATZ parent compound or chlorinated ATZ metabolite formation and degradation. However, reduced CO evolved from VA-treated soil suggests an inhibition to the degradation of other ATZ metabolites due to an altered soil microbial community structure.

  3. Effect of organic amendments on degradation of atrazine.

    Science.gov (United States)

    Mukherjee, Irani

    2009-12-01

    Pesticide contamination of soil and ground water at or near the agricultural fields is a major problem world wide. The ability of several amendments like rice straw, manure, saw dust and charcoal were used to stimulate the degradation of atrazine in soil. Field soil fortified with pesticide at two concentration levels were amended separately with rice straw, farm yard manure, saw dust and charcoal at rates of 2.5% (w/w) and maintained at field capacity moisture regime and kept at ambient temperature 25 +/- 5 degrees C. The results indicate 89.5% degradation of atrazine in farm yard manure during 60-day period followed by rice straw, saw dust charcoal and recording 87.2% and 83.8%, 67.7%, respectively, as compared to unamended treatment where 63.3% degradation was observed. The FYM was found to be most effective in soil and enhances the degradation as compared to the other amendments. Although addition of organic manures has been an integral part of sustainable agriculture practices; the present findings give a new dimension of it's utilization for removal of persistent pesticides.

  4. Atomically thin lateral p-n junction photodetector with large effective detection area

    Science.gov (United States)

    Xu, Zai-Quan; Zhang, Yupeng; Wang, Ziyu; Shen, Yuting; Huang, Wenchao; Xia, Xue; Yu, Wenzhi; Xue, Yunzhou; Sun, Litao; Zheng, Changxi; Lu, Yuerui; Liao, Lei; Bao, Qiaoliang

    2016-12-01

    The widely used photodetector design based on atomically thin transition metal dichalcogenides (TMDs) has a lateral metal-TMD-metal junction with a fairly small, line shape photoresponsive active area at the TMD-electrode interface. Here, we report a highly efficient photodetector with extremely large photoresponsive active area based on a lateral junction of monolayer-bilayer WSe2. Impressively, the separation of the electron-hole pairs (excitons) extends onto the whole 1L-2L WSe2 junction surface. The responsivity of the WSe2 junction photodetector is over 3200 times higher than that of a monolayer WSe2 device and leads to a highest external quantum efficiency of 256% due to the efficient carrier extraction. Unlike the TMD p-n junctions modulated by dual gates or localized doping, which require complex fabrication procedures, our study establishes a simple, controllable, and scalable method to improve the photodetection performance by maximizing the active area for current generation.

  5. Analyzing the Effects of Gap Junction Blockade on Neural Synchrony via a Motoneuron Network Computational Model

    Directory of Open Access Journals (Sweden)

    Heraldo Memelli

    2012-01-01

    Full Text Available In specific regions of the central nervous system (CNS, gap junctions have been shown to participate in neuronal synchrony. Amongst the CNS regions identified, some populations of brainstem motoneurons are known to be coupled by gap junctions. The application of various gap junction blockers to these motoneuron populations, however, has led to mixed results regarding their synchronous firing behavior, with some studies reporting a decrease in synchrony while others surprisingly find an increase in synchrony. To address this discrepancy, we employ a neuronal network model of Hodgkin-Huxley-style motoneurons connected by gap junctions. Using this model, we implement a series of simulations and rigorously analyze their outcome, including the calculation of a measure of neuronal synchrony. Our simulations demonstrate that under specific conditions, uncoupling of gap junctions is capable of producing either a decrease or an increase in neuronal synchrony. Subsequently, these simulations provide mechanistic insight into these different outcomes.

  6. Effects of mechanical strain on the function of Gap junctions in osteocytes are mediated through the prostaglandin EP2 receptor.

    Science.gov (United States)

    Cherian, Priscilla P; Cheng, Benxu; Gu, Sumin; Sprague, Eugene; Bonewald, Lynda F; Jiang, Jean X

    2003-10-31

    Osteocytes embedded in the matrix of bone are thought to be mechanosensory cells that translate mechanical strain into biochemical signals that regulate bone modeling and remodeling. We have shown previously that fluid flow shear stress dramatically induces prostaglandin release and COX-2 mRNA expression in osteocyte-like MLO-Y4 cells, and that prostaglandin E2 (PGE2) released by these cells functions in an autocrine manner to regulate gap junction function and connexin 43 (Cx43) expression. Here we show that fluid flow regulates gap junctions through the PGE2 receptor EP2 activation of cAMP-dependent protein kinase A (PKA) signaling. The expression of the EP2 receptor, but not the subtypes EP1,EP3, and EP4, increased in response to fluid flow. Application of PGE2 or conditioned medium from fluid flow-treated cells to non-stressed MLO-Y4 cells increased expression of the EP2 receptor. The EP2 receptor antagonist, AH6809, suppressed the stimulatory effects of PGE2 and fluid flow-conditioned medium on the expression of the EP2 receptor, on Cx43 protein expression, and on gap junction-mediated intercellular coupling. In contrast, the EP2 receptor agonist butaprost, not the E1/E3 receptor agonist sulprostone, stimulated the expression of Cx43 and gap junction function. Fluid flow conditioned medium and PGE2 stimulated cAMP production and PKA activity suggesting that PGE2 released by mechanically stimulated cells is responsible for the activation of cAMP and PKA. The adenylate cyclase activators, forskolin and 8-bromo-cAMP, enhanced intercellular connectivity, the number of functional gap junctions, and Cx43 protein expression, whereas the PKA inhibitor, H89, inhibited the stimulatory effect of PGE2 on gap junctions. These studies suggest that the EP2 receptor mediates the effects of autocrine PGE2 on the osteocyte gap junction in response to fluid flow-induced shear stress. These data support the hypothesis that the EP2 receptor, cAMP, and PKA are critical components

  7. Effect of baclofen on the acid pocket at the gastroesophageal junction.

    Science.gov (United States)

    Scarpellini, E; Boecxstaens, V; Farré, R; Bisschops, R; Dewulf, D; Gasbarrini, A; Pauwels, A; Blondeau, K; Tack, J

    2015-07-01

    Previous studies established that a pocket of highly acidic gastric juice is present postprandially at the gastroesophageal junction in man. The GABA-B agonist baclofen inhibits postprandial reflux events through its effects on the lower esophageal sphincter (LES). The aim of the current study was to investigate whether baclofen would affect the location and the extent of the postprandial acid pocket in healthy volunteers. Twelve healthy volunteers underwent acid pocket studies on two different occasions, at least 1 week apart. LES position was determined preprandially with pull-through manometry. Dual pH electrode and manometry probe stepwise pull-through (1 cm/minute, LES-10 to +5 cm) was performed at 30-minute intervals for 150 minutes, with administration of placebo or baclofen 40 mg after the first and ingestion of a liquid meal after the second pull-through. After placebo, a significant drop in intragastric gastric pH was present at the gastroesophageal junction after the meal, reflecting the acid pocket, and this was associated with a drop in LES pressure. Baclofen did not affect the presence of the acid pocket, but prevented the postprandial drop in LES pressure, and the extent of the acid pocket above the upper margin of the manometrically located LES was significantly decreased by baclofen (1.6 ± 0.7 vs. 0.3 ± 0.4 cm at 60 minutes, 2.2 ± 0.6 vs. 0.2 ± 0.6 at 90 minutes, and 1.5 ± 0.5 vs. 0.7 ± 0.7 cm at 120 minutes, all P Baclofen does not alter the intragastric acid pocket, but limits its extension into the distal esophagus, probably through an increase in postprandial LES pressure.

  8. [Changes of perimysial junctional plates induced by excessive eccentric training and the effects of acupuncture intervention].

    Science.gov (United States)

    Kong, Mei; Zhang, Xiang; Ye, Mei-Ling; Zhang, Xue-Lin

    2017-02-25

    This study aimed to investigate the effects of acupuncture intervention on excessive eccentric training-induced changes of perimysial junctional plates (PJPs) domain. Thirty healthy male Wistar rats were randomly assigned to 5 groups: control group, four-week training group, four-week training + 1-week recovery group and four-week training + 1-week acupuncture group. Rats were subjected to continuous excessive eccentric training for 4 weeks (incline -16°, speed 16-20 m/min, 60-90 min/d, 5 day per week), and then were subjected to one-week spontaneous recovery or one-week recovery with acupuncture intervention (a piece of filiform needle for 4 min every day). The PJPs domain changes were observed under transmission electron microscopy, and the perimysial collagen network structural changes were examined by scanning electron microscopy with or without a digestion technique (NaOH). The following results were obtained: (1) Compared with control group, PJPs domain of four-week training group showed excessive shortening of sarcomere (P < 0.001), serious damage of sarcomere structure, and altered mitochondria morphology in intermyofibria and subsarcolemma; 54% degradation of sarcolemma, and increased number of caveolae (P < 0.01); reduced number of PJPs (P < 0.001). (2) In comparison with four-week training group, PJPs domain was slightly changed in four-week training + 1-week recovery group, i.e., partial recovery of sarcomere length and structure (accounting for 85.23% of control group), and recovery of intermyofibrial and subsarcolemmal mitochondria morphology; decreased sarcolemmal degradation (P < 0.001), and increased number of caveolae (P < 0.05); increased PJPs number (P < 0.001). (3) PJPs domain changed in four-week training + 1-week acupuncture group compared with four-week training + 1-week recovery group, which were substantial recovery of sarcomere length (accounting for 94.51% of control group), increased subsarcolemmal mitochondrial fusion (P

  9. Gate-tunable diode and photovoltaic effect in an organic-2D layered material p-n junction

    Science.gov (United States)

    Vélez, Saül; Ciudad, David; Island, Joshua; Buscema, Michele; Txoperena, Oihana; Parui, Subir; Steele, Gary A.; Casanova, Fèlix; van der Zant, Herre S. J.; Castellanos-Gomez, Andres; Hueso, Luis E.

    2015-09-01

    The semiconducting p-n junction is a simple device structure with great relevance for electronic and optoelectronic applications. The successful integration of low-dimensional materials in electronic circuits has opened the way forward for producing gate-tunable p-n junctions. In that context, we present here an organic (Cu-phthalocyanine)-2D layered material (MoS2) hybrid p-n junction with both gate-tunable diode characteristics and photovoltaic effect. Our proof-of-principle devices show multifunctional properties with diode rectifying factors of up to 104, while under light exposure they exhibit photoresponse with a measured external quantum efficiency of ~11%. As for their photovoltaic properties, we found open circuit voltages of up to 0.6 V and optical-to-electrical power conversion efficiency of 0.7%. The extended catalogue of known organic semiconductors and two-dimensional materials offer the prospect for tailoring the properties and the performance of the resulting devices, making organic-2D p-n junctions promising candidates for future technological applications.The semiconducting p-n junction is a simple device structure with great relevance for electronic and optoelectronic applications. The successful integration of low-dimensional materials in electronic circuits has opened the way forward for producing gate-tunable p-n junctions. In that context, we present here an organic (Cu-phthalocyanine)-2D layered material (MoS2) hybrid p-n junction with both gate-tunable diode characteristics and photovoltaic effect. Our proof-of-principle devices show multifunctional properties with diode rectifying factors of up to 104, while under light exposure they exhibit photoresponse with a measured external quantum efficiency of ~11%. As for their photovoltaic properties, we found open circuit voltages of up to 0.6 V and optical-to-electrical power conversion efficiency of 0.7%. The extended catalogue of known organic semiconductors and two-dimensional materials

  10. Nonlinear thermoelectric effects in high-field superconductor-ferromagnet tunnel junctions

    Directory of Open Access Journals (Sweden)

    Stefan Kolenda

    2016-11-01

    Full Text Available Background: Thermoelectric effects result from the coupling of charge and heat transport and can be used for thermometry, cooling and harvesting of thermal energy. The microscopic origin of thermoelectric effects is a broken electron–hole symmetry, which is usually quite small in metal structures. In addition, thermoelectric effects decrease towards low temperatures, which usually makes them vanishingly small in metal nanostructures in the sub-Kelvin regime.Results: We report on a combined experimental and theoretical investigation of thermoelectric effects in superconductor/ferromagnet hybrid structures. We investigate the dependence of thermoelectric currents on the thermal excitation, as well as on the presence of a dc bias voltage across the junction.Conclusion: Large thermoelectric effects are observed in superconductor/ferromagnet and superconductor/normal-metal hybrid structures. The spin-independent signals observed under finite voltage bias are shown to be reciprocal to the physics of superconductor/normal-metal microrefrigerators. The spin-dependent thermoelectric signals in the linear regime are due to the coupling of spin and heat transport, and can be used to design more efficient refrigerators.

  11. Field-induced inversion of resonant tunneling currents through single molecule junctions and the directional photo-electric effect

    Science.gov (United States)

    Kuperman, Maayan; Peskin, Uri

    2017-03-01

    It has been known for several decades that the electric current through tunneling junctions is affected by irradiation. In particular, photon-assisted currents by asymmetric irradiation of the two leads was demonstrated and studied extensively in tunneling junctions of different compositions and for different radiation wavelengths. In this work, this phenomenon is revisited in the context of single molecule junctions. Restricting the theoretical discussion to adiabatic periodic driving of one lead with respect to the other within a non-interacting electron formulation, the main features of specific molecules are encoded in the discrete electronic energy levels. The detailed level structure of the molecule is shown to yield new effects in the presence of asymmetric driving of the leads. In particular, when the field-free tunneling process is dominated by a single electronic level, the electric current can be suppressed to zero or flow against the direction of an applied static bias. In the presence of a second electronic level, a directional photo-electric effect is predicted, where not only the magnitude but also the direction of the steady state electric current through the tunneling junction can be changed by a monotonous increase of the field intensity. These effects are analyzed and explained by outlying the relevant theory, using analytic expressions in the wide-band limit, as well as numerical simulations beyond this limit.

  12. Experimental investigation of high cycle thermal fatigue in a T-junction piping system

    Energy Technology Data Exchange (ETDEWEB)

    Selvam, P. Karthick; Kulenovic, Rudi; Laurien, Eckart [Stuttgart Univ. (Germany). Inst. of Nuclear Technology and Energy Systems (IKE)

    2015-10-15

    High cycle thermal fatigue damage of structure in the vicinity of T-junction piping systems in nuclear power plants is of importance. Mixing of coolant streams at significant temperature differences causes thermal fluctuations near piping wall leading to gradual thermal degradation. Flow mixing in a T-junction is performed. The determined factors result in bending stresses being imposed on the piping system ('Banana effect').

  13. The effects of the antibiotic, primycin, on spontaneous transmitter release at the neuromuscular junction.

    Science.gov (United States)

    Henderson, F; Marshall, I G

    1984-01-01

    The effects of primycin, a potent ionophore in biological membranes, have been studied at the neuromuscular junction of the garter snake. Primycin in concentrations greater than 2 X 10(-7)M produced a time- and concentration-dependent depolarization of twitch muscle fibres. Primycin (10(-7)-5 X 10(-7)M) produced an increased rate of quantal release of acetylcholine, which was not maintained, and a slight reduction in quantal size. Time to onset and to peak effect of primycin were concentration-dependent whereas maximum frequency was not. Absence of extracellular Ca2+ produced a significant delay in the time to onset and to peak effect of primycin, but did not affect the peak miniature endplate potential (m.e.p.p.) frequency. Following 60 min exposure to primycin (5 X 10(-7)M), introduction of a high concentration of potassium (20 mM) produced no further increase in spontaneous release. In cut muscle preparations, exposure to primycin (10(-7)-5 X 10(-7)M) reduced peak endplate current (e.p.c.) amplitude until nerve stimulation resulted in failures or the release of one or two quanta. E.p.c. amplitude was not restored with prolonged washing. The effects of primycin on the nerve terminal are considered to be consistent with its ability to increase the permeability of membranes to calcium ions resulting in an influx of extracellular calcium, an efflux of mitochondrial calcium and eventual depletion of synaptic vesicles.

  14. Thermographic measurements of the spin Peltier effect in metal/yttrium-iron-garnet junction systems

    Science.gov (United States)

    Daimon, Shunsuke; Uchida, Ken-ichi; Iguchi, Ryo; Hioki, Tomosato; Saitoh, Eiji

    2017-07-01

    The spin Peltier effect (SPE), heat-current generation due to spin-current injection, in various metal (Pt, W, and Au single layers and Pt/Cu bilayer)/ferrimagnetic insulator [yttrium-iron-garnet (YIG)] junction systems has been investigated by means of a lock-in thermography (LIT) method. The SPE is excited by a spin current across the metal/YIG interface, which is generated by applying a charge current to the metallic layer via the spin Hall effect. The LIT method enables the thermal imaging of the SPE free from the Joule-heating contribution. Importantly, we observed spin-current-induced temperature modulation not only in the Pt/YIG and W/YIG systems, but also in the Au/YIG and Pt/Cu/YIG systems, excluding the possible contamination by anomalous Ettingshausen effects due to proximity-induced ferromagnetism near the metal/YIG interface. As demonstrated in our previous study, the SPE signals are confined only in the vicinity of the metal/YIG interface; we buttress this conclusion by reducing a spatial blur due to thermal diffusion in an infrared-emission layer on the sample surface used for the LIT measurements. We also found that the YIG-thickness dependence of the SPE is similar to that of the spin Seebeck effect measured in the same Pt/YIG sample, implying the reciprocal relation between them.

  15. Effect of paracasein degradation on sensory properties of Gouda cheese.

    Science.gov (United States)

    Cichosz, Grazyna; Zalecka, Anna; Kornacki, Mariusz

    2003-12-01

    The relation between the sensory quality of Gouda cheese and the extent of paracasein degradation, i. e., the content of soluble N, peptide N, amino acid N and amine N, was studied. The above-mentioned parameters of paracasein degradation differently determined the sensory properties of Gouda cheese. The flavour of cheese after 6-week ripening depended to the largest extent on the content of amine N and soluble N. The effect of the content of peptide N on cheese flavour was smaller but statistically significant. Also the smell of Gouda cheese was to the largest extent correlated to the content of amine N. A dependence between smell and the content of peptide N was found only in the cheeses after 4-week ripening. None of the sensory quality parameters of the examined cheeses depended on the content of amino acid N.

  16. Effect of interjunction coupling on superconducting current and charge correlations in intrinsic Josephson junctions

    Science.gov (United States)

    Shukrinov, Yu. M.; Hamdipour, M.; Kolahchi, M. R.

    2009-07-01

    Charge formations on superconducting layers and creation of the longitudinal plasma wave in the stack of intrinsic Josephson junctions change crucially the superconducting current through the stack. Investigation of the correlations of superconducting currents in neighboring Josephson junctions and the charge correlations in neighboring superconducting layers allows us to predict the additional features in the current-voltage characteristics. The charge autocorrelation functions clearly demonstrate the difference between harmonic and chaotic behavior in the breakpoint region. Use of the correlation functions gives us a powerful method for the analysis of the current-voltage characteristics of coupled Josephson junctions.

  17. Electromagnetic environment and Peltier effect in normal-metal/insulator/superconductor junction

    Science.gov (United States)

    Bardas, Athanassios

    1997-07-01

    The influence of external environment on the heat transport through a tunnel junction connecting a normal-metal and a superconductor is analyzed theoretically. It is demonstrated that at finite temperatures finite impedance of the junction electrodes, limits the maximum amount of heat that can be extracted from the normal-metal via the electric current and thus reduces the efficiency of the thermoelectric electron refrigeration. This behaviour is more pronounced for charging energies Ec of the junction, larger than the superconducting gap Δ and persists for a wide range of values of the impedance.

  18. Theoretical Study of Magnetism Induced by Proximity Effect in a Ferromagnetic Josephson Junction with a Normal Metal

    Science.gov (United States)

    Hikino, Shin-ichi

    2017-09-01

    We theoretically study the magnetism induced by the proximity effect in the normal metal of ferromagnetic Josephson junction composed of two s-wave superconductors separated by ferromagnetic metal/normal metal/ferromagnetic metal junction (S/F/N/F/S junction). We calculate the magnetization in the N by solving the Eilenberger equation. We show that the magnetization arises in the N when the product of anomalous Green’s functions of the spin-triplet even-frequency odd-parity Cooper pair and spin-singlet odd-frequency odd-parity Cooper pair in the N has a finite value. The induced magnetization M(d,θ ) can be decomposed into two parts, M(d,θ ) = MI(d) + MII(d,θ ), where d is the thickness of N and θ is superconducting phase difference between two Ss. Therefore, θ dependence of M(d,θ ) allows us to control the amplitude of magnetization by changing θ. The variation of M(d,θ ) with θ is indeed the good evidence of the magnetization induced by the proximity effect, since some methods of magnetization measurement pick up total magnetization in the S/F/N/F/S junction.

  19. Motor effect in electron transport through a molecular junction with torsional vibrations

    OpenAIRE

    Pshenichnyuk, Ivan A.; Čížek, Martin

    2010-01-01

    We propose a model for a molecular junction with internal anharmonic torsional vibrations interacting with an electric current. The Wangsness-Bloch-Redfield master equation approach is used to determine the stationary reduced density matrix of the molecule. The dependence of the current, excitation energy and angular momentum of the junction on the applied voltage is studied. Negative differential conductance is observed in the current-voltage characteristics. It is shown that a model with vi...

  20. Gate-tunable diode and photovoltaic effect in an organic-2D layered material p-n junction.

    Science.gov (United States)

    Vélez, Saül; Ciudad, David; Island, Joshua; Buscema, Michele; Txoperena, Oihana; Parui, Subir; Steele, Gary A; Casanova, Fèlix; van der Zant, Herre S J; Castellanos-Gomez, Andres; Hueso, Luis E

    2015-10-07

    The semiconducting p-n junction is a simple device structure with great relevance for electronic and optoelectronic applications. The successful integration of low-dimensional materials in electronic circuits has opened the way forward for producing gate-tunable p-n junctions. In that context, we present here an organic (Cu-phthalocyanine)-2D layered material (MoS2) hybrid p-n junction with both gate-tunable diode characteristics and photovoltaic effect. Our proof-of-principle devices show multifunctional properties with diode rectifying factors of up to 10(4), while under light exposure they exhibit photoresponse with a measured external quantum efficiency of ∼11%. As for their photovoltaic properties, we found open circuit voltages of up to 0.6 V and optical-to-electrical power conversion efficiency of 0.7%. The extended catalogue of known organic semiconductors and two-dimensional materials offer the prospect for tailoring the properties and the performance of the resulting devices, making organic-2D p-n junctions promising candidates for future technological applications.

  1. Effect of Mefloquine, a Gap Junction Blocker, on Circadian Period2 Gene Oscillation in the Mouse Suprachiasmatic Nucleus

    Directory of Open Access Journals (Sweden)

    Jinmi Koo

    2015-09-01

    Full Text Available BackgroundIn mammals, the master circadian pacemaker is localized in an area of the ventral hypothalamus known as the suprachiasmatic nucleus (SCN. Previous studies have shown that pacemaker neurons in the SCN are highly coupled to one another, and this coupling is crucial for intrinsic self-sustainability of the SCN central clock, which is distinguished from peripheral oscillators. One plausible mechanism underlying the intercellular communication may involve direct electrical connections mediated by gap junctions.MethodsWe examined the effect of mefloquine, a neuronal gap junction blocker, on circadian Period 2 (Per2 gene oscillation in SCN slice cultures prepared from Per2::luciferase (PER2::LUC knock-in mice using a real-time bioluminescence measurement system.ResultsAdministration of mefloquine causes instability in the pulse period and a slight reduction of amplitude in cyclic PER2::LUC expression. Blockade of gap junctions uncouples PER2::LUC-expressing cells, in terms of phase transition, which weakens synchrony among individual cellular rhythms.ConclusionThese findings suggest that neuronal gap junctions play an important role in synchronizing the central pacemaker neurons and contribute to the distinct self-sustainability of the SCN master clock.

  2. Effects of Ultraviolet (UV) on Degradation of Irgafos 168 and Migration of Its Degradation Products from Polypropylene Films.

    Science.gov (United States)

    Yang, Yueping; Hu, Changying; Zhong, Huaining; Chen, Xi; Chen, Rujia; Yam, Kit L

    2016-10-05

    The effects of ultraviolet (UV) irradiation on the degradation of Irgafos 168 and the migration of its two degradation products, 2,4-di-tert-butylphenol and tris(2,4-di-tert-butylphenyl)phosphate, from polypropylene (PP) were investigated. A blown film machine was used to extrude PP films containing Irgafos 168, the films were stored in the dark for 45 days, two UV treatments and sunlight exposure were applied to the films, and GC-MS was used for degradation and migration studies. Extrusion, storage, UV treatments, and sunlight exposure significantly affected concentrations of Irgafos 168 and the degradation products. 2,4-Di-tert-butylphenol was the major degradation product produced by UV irradiation, but tris(2,4-di-tert-butylphenyl)phosphate was the major degradation product produced by extrusion, storage, and sunlight exposure. The degradation products have no or little health risk, because migration study and threshold of toxicological concern (TTC) analysis show that experimental maximum migration of 2,4-di-tert-butylphenol and tris(2,4-di-tert-butylphenyl)phosphate are only 2 and 53% of the theoretical maximum migration amounts, respectively.

  3. Bipolar spin-valley diode effect in a silicene magnetic junction

    Science.gov (United States)

    Zhai, Xuechao; Zhang, Sihao; Zhao, Ying; Zhang, Xiaoyu; Yang, Zhihong

    2016-09-01

    Silicene has attracted much attention recently due to the electrons' multiple degrees of freedom, specifically for spin and valley. We here demonstrate that a bipolar spin-valley diode effect can be driven and controlled by applying longitudinal biases through a silicene ferromagnetic-field/interlayer-electric-field junction. This effect indicates that only one-spin (the other spin) electrons from one valley (the other valley) contribute to the conductance under positive (negative) biases, originating from the specific band-matching tunneling mechanism. All the forbidden channels are induced by either spin-mismatch or spin-valley dependent bandgaps. It is also found that, by reversing the direction of interlayer electric field, the conductive valley can be switched to the other while the spin orientation is reserved. Furthermore, all the possible spin-valley configurations of conductance, contributed by single spin and single valley, can be completely turned "on" or "off" only by tuning the bias and the electric field. These results suggest that silicene can be a good candidate for future quantum information processing in spin-valley logic circuits.

  4. Proximity effect in a Nb-InAs-Nb nanowire junction

    Science.gov (United States)

    Baugh, Jonathan; Gharavi, Kaveh; Holloway, Greg; Haapamaki, Chris; Lapierre, Ray R.

    2014-03-01

    Proximity effect superconductivity in semiconductor-superconductor hybrid devices contains rich physics and could be key to the realization of topological quantum information processing. We have performed a series of low temperature electronic transport measurements on an InAs nanowire contacted with Niobium leads. The channel length (~ 4 times the nanowire diameter) is shorter than the electronic phase coherence length, but longer than the elastic mean free path, leading to behaviour that can be modelled by a superconductor-normal-superconductor junction in the diffusive transport regime. A supercurrent is observed below a critical current Ic of up to ~50 nA. The critical current varies with local gate voltages and correlates with the normal state conductance, producing modulation of Ic related to universal conductance fluctuations. An applied magnetic field produces a Gaussian decay of Ic, consistent with known theory. Analysis of multiple Andreev reflection corrections to conductance indicates a contact transparency ~0.6. The full results help to shed light on the nature of proximity effect superconductivity in a quasi-one-dimensional semiconductor in the quasi-diffusive regime. Supported by NSERC, Canada Foundation for Innovation.

  5. Scanning tunneling microscope light emission: Effect of the strong dc field on junction plasmons

    Science.gov (United States)

    Kalathingal, Vijith; Dawson, Paul; Mitra, J.

    2016-07-01

    The observed energies of the localized surface plasmons (LSPs) excited at the tip-sample junction of a scanning tunneling microscope, as identified by spectral peaks in the light output, are very significantly redshifted with respect to calculations that use standard optical data for the tip and sample material, gold in this case. We argue that this anomaly depends on the extreme field in the sub-nm tunneling proximity of the tip and the sample, across which a dc bias (1-2 V) is applied. Finite element modeling analysis is presented of a gold nanosphere-plane (NS-P) combination in tunneling proximity and, crucially, in the presence of a high static electric field (˜109V /m ). It is argued that the strong dc field induces nonlinear corrections to the dielectric function of the gold via the effect of a large background polarizability through the nonlinear, χ(3 ) susceptibility contribution. When fed into the model system the modified optical data alters the LSP cavity modes of the NS-P system to indeed reveal a large redshift in energy compared to those of the virgin gold NS-P system. The net outcome may be regarded as equivalent to lowering the bulk plasmon energy, the physical interpretation being that the intense field of the tunneling environment leads to surface charge screening, effectively reducing the density of free electrons available to participate in the plasmon oscillations.

  6. Effects of Nonuniform Incident Illumination on the Thermal Performance of a Concentrating Triple Junction Solar Cell

    Directory of Open Access Journals (Sweden)

    Fahad Al-Amri

    2014-01-01

    Full Text Available A numerical heat transfer model was developed to investigate the temperature of a triple junction solar cell and the thermal characteristics of the airflow in a channel behind the solar cell assembly using nonuniform incident illumination. The effects of nonuniformity parameters, emissivity of the two channel walls, and Reynolds number were studied. The maximum solar cell temperature sharply increased in the presence of nonuniform light profiles, causing a drastic reduction in overall efficiency. This resulted in two possible solutions for solar cells to operate in optimum efficiency level: (i adding new receiver plate with higher surface area or (ii using forced cooling techniques to reduce the solar cell temperature. Thus, surface radiation exchanges inside the duct and Re significantly reduced the maximum solar cell temperature, but a conventional plain channel cooling system was inefficient for cooling the solar cell at medium concentrations when the system was subjected to a nonuniform light distribution. Nonuniformity of the incident light and surface radiation in the duct had negligible effects on the collected thermal energy.

  7. Quantum Junction Solar Cells

    KAUST Repository

    Tang, Jiang

    2012-09-12

    Colloidal quantum dot solids combine convenient solution-processing with quantum size effect tuning, offering avenues to high-efficiency multijunction cells based on a single materials synthesis and processing platform. The highest-performing colloidal quantum dot rectifying devices reported to date have relied on a junction between a quantum-tuned absorber and a bulk material (e.g., TiO 2); however, quantum tuning of the absorber then requires complete redesign of the bulk acceptor, compromising the benefits of facile quantum tuning. Here we report rectifying junctions constructed entirely using inherently band-aligned quantum-tuned materials. Realizing these quantum junction diodes relied upon the creation of an n-type quantum dot solid having a clean bandgap. We combine stable, chemically compatible, high-performance n-type and p-type materials to create the first quantum junction solar cells. We present a family of photovoltaic devices having widely tuned bandgaps of 0.6-1.6 eV that excel where conventional quantum-to-bulk devices fail to perform. Devices having optimal single-junction bandgaps exhibit certified AM1.5 solar power conversion efficiencies of 5.4%. Control over doping in quantum solids, and the successful integration of these materials to form stable quantum junctions, offers a powerful new degree of freedom to colloidal quantum dot optoelectronics. © 2012 American Chemical Society.

  8. Characteristics of the Surface-Intrinsic Josephson Junction

    Institute of Scientific and Technical Information of China (English)

    YANG Li; XU Wei-wei; YE Su-li; GUO Da-yuan; YOU Li-xing; WU Pei-heng

    2006-01-01

    During the fabrication of intrinsic Josephson junctions (IJJs) with Bi2Sr2CaCu2O8+δ(BSCCO) single crystals,the superconductivity of the surface Cu-O layer is degraded because of a deposited metal film on top of the stack.Thus,the characteristics of the surface junction consisting of the surface Cu-O double layers remarkably differ from those of the junctions deep in the stack,which will be referred to as ordinary IJJs.The electrical transport characteristics of the surface junction,such as I-V,I'c-T,and R-T,show that the critical temperature T'c of the surface junction is always lower than that of ordinary IJJs,and that the change of its critical current I'c with temperature is different from that of ordinary IIJs.Furthermore,by shunting! the surface junction resistively,we are able to observe the AC Josephson effect at 3-mm waveband.

  9. The Effect of Impact Location on Force Transmission to the Modular Junctions of Dual-Taper Modular Hip Implants.

    Science.gov (United States)

    Frisch, Nicholas B; Lynch, Jonathan R; Banglmaier, Richard F; Silverton, Craig D

    2016-09-01

    The purpose of this study was to investigate the effect that off-axis impaction has on stability of dual-taper modular implants as measured by forces delivered to and transmitted through the head-neck and neck-stem tapers, respectively. One hundred forty-four impact tests were performed using 6 different directions: one on-axis and five 10° off-axes. Four different simulations were performed measuring the head-neck only and 3 different neck angulations: 0°, 8°, and 15°. A drop tower impactor delivered both on- and off-axis impaction from a constant height. Load cells positioned in the drop mass and at the head-neck (HN) or neck-stem (NS) junction measured the impact and joint forces, respectively. Impact force of the hammer on the head ranged from 3800-4500 N. Greatest impact force delivered to the head was typically with axial impact. However, greatest force transmission to the neck-stem junction was not necessarily with axial impacts. There was limited variability in the force measured at the NS junction for all impaction directions seen in the 8° neck, whereas the 15° neck had greater forces transmitted to the NS junction with off-axes impactions directed in the proximal and posterior-proximal directions. The location of the impact significantly influences the force transmitted to the head-neck and neck-stem junctions in dual-taper modular hip implants. Although axial impacts proved superior to off-axis impacts for the straight 0° neck, greater force transmission with off-axis impacts for the angled necks suggests that off-axis impacts may potentially compromise the stability of dual-taper components. Published by Elsevier Inc.

  10. Bias voltage effects on tunneling magnetoresistance in Fe/MgAl2O4/Fe (001 ) junctions: Comparative study with Fe/MgO/Fe(001) junctions

    Science.gov (United States)

    Masuda, Keisuke; Miura, Yoshio

    2017-08-01

    We investigate bias voltage effects on the spin-dependent transport properties of Fe/MgAl 2O 4 /Fe(001) magnetic tunneling junctions (MTJs) by comparing them with those of Fe/MgO/Fe(001) MTJs. By means of the nonequilibrium Green's function method and the density functional theory, we calculate bias voltage dependencies of magnetoresistance (MR) ratios in both the MTJs. We find that in both the MTJs, the MR ratio decreases as the bias voltage increases and finally vanishes at a critical bias voltage Vc. We also find that the critical bias voltage Vc of the MgAl 2O 4 -based MTJ is clearly larger than that of the MgO-based MTJ. Since the in-plane lattice constant of the Fe/MgAl 2O 4 /Fe(001) supercell is twice that of the Fe/MgO/Fe(001) one, the Fe electrodes in the MgAl 2O 4 -based MTJs have an identical band structure to that obtained by folding the Fe band structure of the MgO-based MTJs in the Brillouin zone of the in-plane wave vector. We show that such a difference in the Fe band structure is the origin of the difference in the critical bias voltage Vc between the MgAl 2O 4 - and MgO-based MTJs.

  11. Comparison between Field Effect Transistors and Bipolar Junction Transistors as Transducers in Electrochemical Sensors

    Science.gov (United States)

    Zafar, Sufi; Lu, Minhua; Jagtiani, Ashish

    2017-01-01

    Field effect transistors (FET) have been widely used as transducers in electrochemical sensors for over 40 years. In this report, a FET transducer is compared with the recently proposed bipolar junction transistor (BJT) transducer. Measurements are performed on two chloride electrochemical sensors that are identical in all details except for the transducer device type. Comparative measurements show that the transducer choice significantly impacts the electrochemical sensor characteristics. Signal to noise ratio is 20 to 2 times greater for the BJT sensor. Sensitivity is also enhanced: BJT sensing signal changes by 10 times per pCl, whereas the FET signal changes by 8 or less times. Also, sensor calibration curves are impacted by the transducer choice. Unlike a FET sensor, the calibration curve of the BJT sensor is independent of applied voltages. Hence, a BJT sensor can make quantitative sensing measurements with minimal calibration requirements, an important characteristic for mobile sensing applications. As a demonstration for mobile applications, these BJT sensors are further investigated by measuring chloride levels in artificial human sweat for potential cystic fibrosis diagnostic use. In summary, the BJT device is demonstrated to be a superior transducer in comparison to a FET in an electrochemical sensor. PMID:28134275

  12. Brief rapid thermal treatment effect on patterned CoFeB-based magnetic tunneling junctions

    Science.gov (United States)

    Wu, Kuo-Ming; Huang, Chao-Hsien; Wang, Yung-Hung; Kao, Ming-Jer; Tsai, Ming-Jinn; Wu, Jong-Ching; Horng, Lance

    2007-05-01

    The brief thermal treatment effects on the magnetoresistance of microstructured Co60Fe20B20-based magnetic tunneling junctions have been studied. The elliptical shape of devices with long/short axis of 4/2μm was patterned out of film stack of seed layer (20)/PtMn(15)/Co60Fe20B20(3)/Al(0.7)oxide/C60Fe20B20(20)/capping layer (48) (thickness unit in nanometers) combining conventional lithography and inductively coupled plasma reactive ion beam etching technologies. The thermal annealing was carried out with device loading into a furnace with preset temperatures ranging from 100to400°C for only 5min in the absence of any external magnetic field. The magnetoresistance was found to increase with increasing annealing temperatures up to 250°C and then decrease at higher annealing temperatures. In addition, the magnetoresistance ratio of around 35%, similar to that of as-fabricated devices, sustains up to annealing temperature of 350°C. This survival of magnetoresistance at higher annealing temperature is due to boron conservation in the amorphous CoFeB ferromagnetic layer at higher annealing temperature for only a short time, which is manifested using x-ray diffractometer technique.

  13. Fabrication and characterization of GaN junction field effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, L.; Lester, L.F.; Baca, A.G.; Shul, R.J.; Chang, P.C.; Willison, C.L.; Mishra, U.K.; Denbaars, S.P.; Zolper, J.C.

    2000-01-11

    Junction field effect transistors (JFET) were fabricated on a GaN epitaxial structure grown by metal organic chemical vapor deposition. The DC and microwave characteristics, as well as the high temperature performance of the devices were studied. These devices exhibited excellent pinch-off and a breakdown voltage that agreed with theoretical predictions. An extrinsic transconductance (g{sub m}) of 48 mS/mm was obtained with a maximum drain current (I{sub D}) of 270 mA/mm. The microwave measurement showed an f{sub T} of 6 GHz and an f{sub max} of 12 GHz. Both the I{sub D} and the g{sub m} were found to decrease with increasing temperature, possibly due to lower electron mobility at elevated temperatures. These JFETs exhibited a significant current reduction after a high drain bias was applied, which was attributed to a partially depleted channel caused by trapped electrons in the semi-insulating GaN buffer layer.

  14. Applications, Prospects and Challenges of Silicon Carbide Junction Field Effect Transistor (SIC JFET

    Directory of Open Access Journals (Sweden)

    Frederick Ojiemhende Ehiagwina

    2016-09-01

    Full Text Available Properties of Silicon Carbide Junction Field Effect Transistor (SiC JFET such as high switching speed, low forward voltage drop and high temperature operation have attracted the interest of power electronic researchers and technologists, who for many years developed devices based on Silicon (Si.  A number of power system Engineers have made efforts to develop more robust equipment including circuits or modules with higher power density. However, it was realized that several available power semiconductor devices were approaching theoretical limits offered by Si material with respect to capability to block high voltage, provide low on-state voltage drop and switch at high frequencies. This paper presents an overview of the current applications of SiC JFET in circuits such as inverters, rectifiers and amplifiers. Other areas of application reviewed include; usage of the SiC JFET in pulse signal circuits and boost converters. Efforts directed toward mitigating the observed increase in electromagnetic interference were also discussed. It also presented some areas for further research, such as having more applications of SiC JFET in harsh, high temperature environment. More work is needed with regards to SiC JFET drivers so as to ensure stable and reliable operation, and reduction in the prices of SiC JFETs through mass production by industries.

  15. Comparison between Field Effect Transistors and Bipolar Junction Transistors as Transducers in Electrochemical Sensors

    Science.gov (United States)

    Zafar, Sufi; Lu, Minhua; Jagtiani, Ashish

    2017-01-01

    Field effect transistors (FET) have been widely used as transducers in electrochemical sensors for over 40 years. In this report, a FET transducer is compared with the recently proposed bipolar junction transistor (BJT) transducer. Measurements are performed on two chloride electrochemical sensors that are identical in all details except for the transducer device type. Comparative measurements show that the transducer choice significantly impacts the electrochemical sensor characteristics. Signal to noise ratio is 20 to 2 times greater for the BJT sensor. Sensitivity is also enhanced: BJT sensing signal changes by 10 times per pCl, whereas the FET signal changes by 8 or less times. Also, sensor calibration curves are impacted by the transducer choice. Unlike a FET sensor, the calibration curve of the BJT sensor is independent of applied voltages. Hence, a BJT sensor can make quantitative sensing measurements with minimal calibration requirements, an important characteristic for mobile sensing applications. As a demonstration for mobile applications, these BJT sensors are further investigated by measuring chloride levels in artificial human sweat for potential cystic fibrosis diagnostic use. In summary, the BJT device is demonstrated to be a superior transducer in comparison to a FET in an electrochemical sensor.

  16. Cochlear implantation effect on deaf children with gap junction protein beta 2 gene mutation

    Institute of Scientific and Technical Information of China (English)

    KONG Ying; LIU Sha; WANG Su-ju; Li Shu-jing; LIANG Shuang

    2013-01-01

    Background The popularization and promotion of gene diagnosis technology makes it possible to detect deafness genes for children with congenital hearing impairment,and the proportion of gap junction protein beta 2 (GJB2) gene mutations in cochlear implant patients is 26.5% We did follow-up evaluation on auditory rehabilitation effect for all 31 deaf children with GJB2 gene mutation after cochlear implantation to provide a reference for such patients.Methods Application of “the genetic deafness gene chip detection kit” and “gene complete sequence analysis” were applied to conduct detection on common genetic deafness gene mutation hotspots of the hearing impaired children with cochlear implantation.To conduct auditory rehabilitation effect evaluation on all 31 cases of patients with GJB2 genetic deafness after 3,6 and 12 months of the operation respectively.The single factor repeated measure analysis of variance (ANOVA) was applied to analysis whether there were significant difference among the results of initial consonant of a Chinese syllable recognition at 3 different stages after the operation,the results of vowel of a Chinese syllable recognition at 3 different stages after the operation,and the results of two-syllable recognition at 3 different stages after the operation.Results The 235delC is the high-incidence mutational site in 31 cases of patients with GJB2 genetic deafness,and the total detection rate is up to 90.3% (28/31).There were significant differences in the initial consonant and the vowel of a Chinese syllable recognition rate,and the two-syllable recognition rates at 3,6,and 12 months after the operation (P<0.01).Conclusion Cochlear implantation is a safe and effective measure for auditory reconstruction,enabling patients with GJB2 hereditary severe sensorineural deafness to achieve auditory speech recognition effectively.

  17. Effect of the gap junction blocker 1-heptanol on chondrogenic differentiation of mouse bone marrow mesenchymal stem cells in vitro

    Institute of Scientific and Technical Information of China (English)

    Liu Ouyang; Yukun Zhang; Shuhua Yang; Shunan Ye; Weihua Xu

    2009-01-01

    Objective:To investigate the effect of the gap junction blocker 1-heptanol on the in vitro chondrogenic differentiation of mouse bone marrow mesencbymal stem cells(MSCs) following induction by GDF-5. Methods:MSCs were isohted from mouse bone marrow and cultured in vitro. After 3 passages cells were induced to undergo chondrogenic differentiation with recombinant human GDF-5(100 ng/ml), with or without 1-heptanol(2.5 μ mol/L). The effect of 1-heptanol on MSCs proliferation was investigated using the MTT assay. Type Ⅱ collagen mRNA and protein were examined by RT-PCR and immunocytochernistry respectively, and the sulfate glycosaminoglycan was assessed by Alcian blue dye staining. Connexin43(Cx43) protein was examined by western blotting. Results:GDF-5 induced proliferation and chondrogenic differentiation of MSCs. While 1-heptanol treatment had no effect on this proliferation, it inhibited the expression of both type Ⅱ collagen mRNA and protein. The Alcian blue staining revealed that 1-heptanol also inhibited the deposition of the typical cartilage extracellular matrix promoted by recombinant GDF-5. Western blotting demonstrated that 1-heptanol had no effect on the expression of Cx43. Conclusion:Tbese results suggest that mouse bone marrow MSCs can be differentiated into a chondrogenic phenotype by GDF-5 administration in vitro. While the gap junction blocker, 1-heptanol, did not reduce gap junction Cx43, these intercellular communication pathways clearly played an important functional role in GDF-5-induced cartilage differentiation.

  18. Effect of resistance training on neuromuscular junctions of young and aged muscles featuring different recruitment patterns.

    Science.gov (United States)

    Deschenes, Michael R; Sherman, E Grace; Roby, Mackenzie A; Glass, Emily K; Harris, M Brennan

    2015-03-01

    To examine the effects of aging on neuromuscular adaptations to resistance training (i.e., weight lifting), young (9 months of age) and aged (20 months of age) male rats either participated in a 7-week ladder climbing protocol with additional weight attached to their tails or served as controls (n = 10/group). At the conclusion, rats were euthanized and hindlimb muscles were quickly removed and frozen for later analysis. Longitudinal sections of the soleus and plantaris muscles were collected, and pre- and postsynaptic features of neuromuscular junctions (NMJs) were visualized with immunofluorescence staining procedures. Cross-sections of the same muscles were histochemically stained to determine myofiber profiles (fiber type and size). Statistical analysis was by two-way ANOVA (main effects of age and treatment) with significance set at P ≤ 0.05. Results revealed that training-induced remodeling of NMJs was evident only at the postsynaptic endplate region of soleus fast-twitch myofibers. In contrast, aging was associated with pre- and postsynaptic remodeling in fast- and slow-twitch myofibers of the plantaris. Although both the soleus and the plantaris muscles failed to display either training or aging-related alterations in myofiber size, aged plantaris muscles exhibited an increased expression of type I (slow-twitch) myofibers in conjunction with a reduced percentage of type II (fast-twitch) myofibers, suggesting early stages of sarcopenia. These data demonstrate the high degree of specificity of synaptic modifications made in response to exercise and aging and that the sparsely recruited plantaris is more vulnerable to the effects of aging than the more frequently recruited soleus muscle.

  19. Effects of grinding processes on enzymatic degradation of wheat straw.

    Science.gov (United States)

    Silva, Gabriela Ghizzi D; Couturier, Marie; Berrin, Jean-Guy; Buléon, Alain; Rouau, Xavier

    2012-01-01

    The effectiveness of wheat straw fine to ultra-fine grindings at pilot scale was studied. The produced powders were characterised by their particle-size distribution (laser diffraction), crystallinity (WAXS) and enzymatic degradability (Trichoderma reesei enzymatic cocktail). A large range of wheat-straw powders was produced: from coarse (median particle size ∼800 μm) to fine particles (∼50 μm) using sieve-based grindings, then ultra-fine particles ∼20 μm by jet milling and ∼10 μm by ball milling. The wheat straw degradability was enhanced by the decrease of particle size until a limit: ∼100 μm, up to 36% total carbohydrate and 40% glucose hydrolysis yields. Ball milling samples overcame this limit up to 46% total carbohydrate and 72% glucose yields as a consequence of cellulose crystallinity reduction (from 22% to 13%). Ball milling appeared to be an effective pretreatment with similar glucose yield and superior carbohydrate yield compared to steam explosion pretreatment.

  20. Effect of asymmetric molecule-electrode coupling and molecular bias on rectification in molecular junctions

    Science.gov (United States)

    Kaur, Rupan Preet; Sawhney, Ravinder Singh; Engles, Derick

    2016-12-01

    In this research work, we compare the rectification trends of two symmetrical and one asymmetrical molecular junction formed with gold and silver electrodes bridging benzenedithiol molecule. The origin of rectification is attributed to both molecular bias drop and asymmetric molecule-electrode coupling. The electronic transport properties are computed by using semi-empirical extended Huckel method combined with non-equilibrium Green's function framework. The results are fully rationalized by analysing the distribution of molecular orbitals with changing bias voltage, available density of states and area of transmission spectra spanned within bias window, transmission eigenstates and transmission pathways. We deduce through this work that the molecular rectification is not only the property of asymmetric molecule-metal coupling, but molecular bias also plays vital role in stemming asymmetric I- V characteristics. Our results suggest how to realize molecular rectification by using different electrode materials which act as Schottky barriers in molecular junctions that emulate p-n junction diode in semiconductor electronics.

  1. Effects of feeding on luminal pH and morphology of the gastroesophageal junction of snakes.

    Science.gov (United States)

    Bessler, Scott M; Secor, Stephen M

    2012-10-01

    At the gastroesophageal junction, most vertebrates possess a functional lower esophageal sphincter (LES) which may serve to regulate the passage of liquids and food into the stomach and prevent the reflux of gastric contents into the esophagus. Snakes seemingly lack an LES and consume meals large enough to extend anteriorly from the stomach into the esophagus thereby providing the opportunity for the reflux of gastric juices. To explore whether snakes experience or can prevent gastric reflux, we examined post-feeding changes of luminal pH of the distal esophagus and stomach, the fine scale luminal pH profile at the gastroesophageal junction, and the morphology of the gastroesophageal junction for the Burmese python (Python molurus), the African brown house snake (Lamprophis fuliginosus), and the diamondback water snake (Nerodia rhombifer). For each species fasted, there was no distension of the gastroesophageal junction and only modest changes in luminal pH from the distal esophagus into the stomach. Feeding resulted in marked distension and changes in tissue morphology of the gastroesophageal junction. Simultaneously, there was a significant decrease in luminal pH of the distal esophagus for pythons and house snakes, and for all three species a steep gradient in luminal pH decreasing across a 3-cm span from the distal edge of the esophagus into the proximal edge of the stomach. The moderate acidification of the distal most portion of the esophagus for pythons and house snakes suggests that there is some anterior movement of gastric juices across the gastroesophageal junction. Given that this modest reflux of gastric fluid is localized to the most distal region of the esophagus, snakes are apparently able to prevent and protect against acid reflux in the absence of a functional LES.

  2. Droplet formation in microfluidic T-junction generators operating in the transitional regime. III. Dynamic surfactant effects.

    Science.gov (United States)

    Glawdel, Tomasz; Ren, Carolyn L

    2012-08-01

    This study extends our previous work on droplet generation in microfluidic T-junction generators to include dynamic interfacial tension effects created by the presence of surfactants. In Paper I [T. Glawdel, C. Elbuken, and C. L. Ren, Phys. Rev. E 85, 016322 (2012)], we presented experimental findings regarding the formation process in the squeezing-to-transition regime, and in Paper II [T. Glawdel, C. Elbuken, and C. L. Ren, Phys. Rev. E 85, 016323 (2012)] we developed a theoretical model that describes the performance of T-junction generators without surfactants. Here we study dynamic interfacial tension effects for two surfactants, one with a small molecular weight that adsorbs quickly, and the other with a large molecular weight that adsorbs slowly. Using the force balance developed in Paper II we extract the dynamic interfacial tension from high speed videos obtained during experiments. We then develop a theoretical model to predict the dynamic interfacial tension in microfluidic T-junction generators as a function of the surfactant properties, flow conditions, and generator design. This model is then incorporated into the overall model for generator performance to effectively predict the size of droplets produced when surfactants are present.

  3. Wide-range and fast thermally-tunable silicon photonic microring resonators using the junction field effect.

    Science.gov (United States)

    Wang, Xiaoxi; Lentine, Anthony; DeRose, Christopher; Starbuck, Andrew L; Trotter, Douglas; Pomerene, Andrew; Mookherjea, Shayan

    2016-10-03

    Tunable silicon microring resonators with small, integrated micro-heaters which exhibit a junction field effect were made using a conventional silicon-on-insulator (SOI) photonic foundry fabrication process. The design of the resistive tuning section in the microrings included a "pinched" p-n junction, which limited the current at higher voltages and inhibited damage even when driven by a pre-emphasized voltage waveform. Dual-ring filters were studied for both large (>4.9 THz) and small (850 GHz) free-spectral ranges. Thermal red-shifting was demonstrated with microsecond-scale time constants, e.g., a dual-ring filter was tuned over 25 nm in 0.6 μs 10%-90% transition time, and with efficiency of 3.2 μW/GHz.

  4. The effect of the optical system on the electrical performance of III–V concentrator triple junction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, R.D., E-mail: S206029578@nmmu.ac.za; Dyk, E.E. van; Vorster, F.J.

    2016-01-01

    High Concentrated Photovoltaic (H-CPV) technologies utilize relatively inexpensive reflective and refractive optical components for concentration to achieve high energy yield. The electrical performance of H-CPV systems is, however, dependent on the properties and configuration of the optical components. The focus of this paper is to summarize the effect of the properties of the optical system on the electrical performance of a Concentrator Triple Junction (CTJ) InGaP/InGaAs/Ge cell. Utilizing carefully designed experiments that include spectral measurements and intensity profiles in the optical plane of the CTJ cell, the influence of photon absorption, Fresnel lens properties and chromatic aberration created by the optical system on the electrical performance of a CTJ cell is shown. From the results obtained, it is concluded that good characterization and understanding of the optical system’s properties may add to improved design of future multi-junction devices.

  5. Fano-Josephson effect in the junction with DIII-class topological and s-wave superconductors

    Science.gov (United States)

    Jiang, Cui; Yi, Guang-Yu; Meng, Guang-Yi; Gong, Wei-Jiang

    2017-04-01

    We investigate the Josephson effects in the junction formed by the direct and indirect couplings between DIII-class topological and s-wave superconductors. As a result, the Josephson current is found to oscillate in period 2 π . The presence of Majorana doublet in the DIII-class superconductor renders the current finite at the case of zero phase difference, with its sign determined by the fermion parity of such a junction. In addition to the dot level and intradot Coulomb interaction, the Fano interference is an important factor to adjust the Josephson current. It is believed that these results will be helpful in understanding the transport properties of the DIII-class superconductor.

  6. Hard-hard coupling assisted anomalous magnetoresistance effect in amine-ended single-molecule magnetic junction

    Science.gov (United States)

    Tang, Y.-H.; Lin, C.-J.; Chiang, K.-R.

    2017-06-01

    We proposed a single-molecule magnetic junction (SMMJ), composed of a dissociated amine-ended benzene sandwiched between two Co tip-like nanowires. To better simulate the break junction technique for real SMMJs, the first-principles calculation associated with the hard-hard coupling between a amine-linker and Co tip-atom is carried out for SMMJs with mechanical strain and under an external bias. We predict an anomalous magnetoresistance (MR) effect, including strain-induced sign reversal and bias-induced enhancement of the MR value, which is in sharp contrast to the normal MR effect in conventional magnetic tunnel junctions. The underlying mechanism is the interplay between four spin-polarized currents in parallel and anti-parallel magnetic configurations, originated from the pronounced spin-up transmission feature in the parallel case and spiky transmission peaks in other three spin-polarized channels. These intriguing findings may open a new arena in which magnetotransport and hard-hard coupling are closely coupled in SMMJs and can be dually controlled either via mechanical strain or by an external bias.

  7. Effects of lignin on the anaerobic degradation of (ligno) cellulosic wastes by rumen microorganisms

    Energy Technology Data Exchange (ETDEWEB)

    Camp, H.J.M. op den; Verhagen, F.J.M.; Kivaisi, A.K.; Windt, F.E. de; Lubberding, H.J.; Gijzen, H.J.; Vogels, G.D.

    1988-10-01

    There appeared to be a clear correlation between the lignin content (% of TS) of several waste and natural materials and their degradability by rumen microorgansims. Materials with lignin contents higher than 25% were not degraded within 72 h. The effects of Kraft pine lignin and some lignin momomers on filter paper degradation, methane production and CMCase activity were tested. Testing these compounds in concentrations comparable to natural conditions showed minor effects. At higher concentrations p-coumaric acid strongly inhibited cellulose degradation and methane production in batch cultures. Influence of lignin compounds on degradation is discussed in relation to structural effects and enzyme or growth inhibition.

  8. Nonspecific effects of the gap junction blocker mefloquine on fast hippocampal network oscillations in the adult rat in vitro.

    Science.gov (United States)

    Behrens, C J; Ul Haq, R; Liotta, A; Anderson, M L; Heinemann, U

    2011-09-29

    It has been suggested that gap junctions are involved in the synchronization during high frequency oscillations as observed during sharp wave-ripple complexes (SPW-Rs) and during recurrent epileptiform discharges (REDs). Ripple oscillations during SPW-Rs, possibly involved in memory replay and memory consolidation, reach frequencies of up to 200 Hz while ripple oscillations during REDs display frequencies up to 500 Hz. These fast oscillations may be synchronized by intercellular interactions through gap junctions. In area CA3, connexin 36 (Cx36) proteins are present and potentially sensitive to mefloquine. Here, we used hippocampal slices of adult rats to investigate the effects of mefloquine, which blocks Cx36, Cx43 and Cx50 gap junctions on both SPW-Rs and REDs. SPW-Rs were induced by high frequency stimulation in the CA3 region while REDs were recorded in the presence of the GABA(A) receptor blocker bicuculline (5 μM). Both, SPW-Rs and REDs were blocked by the gap junction blocker carbenoxolone. Mefloquine (50 μM), which did not affect stimulus-induced responses in area CA3, neither changed SPW-Rs nor superimposed ripple oscillations. During REDs, 25 and 50 μM mefloquine exerted only minor effects on the expression of REDs but significantly reduced the amplitude of superimposed ripples by ∼17 and ∼54%, respectively. Intracellular recordings of CA3 pyramidal cells revealed that mefloquine did not change their resting membrane potential and input resistance but significantly increased the afterhyperpolarization following evoked action potentials (APs) resulting in reduced probability of AP firing during depolarizing current injection. Similarly, mefloquine caused a reduction in AP generation during REDs. Together, our data suggest that mefloquine depressed RED-related ripple oscillations by reducing high frequency discharges and not necessarily by blocking electrical coupling.

  9. Metformin prevents the effects of Pseudomonas aeruginosa on airway epithelial tight junctions and restricts hyperglycaemia-induced bacterial growth.

    Science.gov (United States)

    Patkee, Wishwanath R A; Carr, Georgina; Baker, Emma H; Baines, Deborah L; Garnett, James P

    2016-04-01

    Lung disease and elevation of blood glucose are associated with increased glucose concentration in the airway surface liquid (ASL). Raised ASL glucose is associated with increased susceptibility to infection by respiratory pathogens including Staphylococcus aureus and Pseudomonas aeruginosa. We have previously shown that the anti-diabetes drug, metformin, reduces glucose-induced S. aureus growth across in vitro airway epithelial cultures. The aim of this study was to investigate whether metformin has the potential to reduce glucose-induced P. aeruginosa infections across airway epithelial (Calu-3) cultures by limiting glucose permeability. We also explored the effect of P. aeruginosa and metformin on airway epithelial barrier function by investigating changes in tight junction protein abundance. Apical P. aeruginosa growth increased with basolateral glucose concentration, reduced transepithelial electrical resistance (TEER) and increased paracellular glucose flux. Metformin pre-treatment of the epithelium inhibited the glucose-induced growth of P. aeruginosa, increased TEER and decreased glucose flux. Similar effects on bacterial growth and TEER were observed with the AMP activated protein kinase agonist, 5-aminoimidazole-4-carboxamide ribonucleotide. Interestingly, metformin was able to prevent the P. aeruginosa-induced reduction in the abundance of tight junction proteins, claudin-1 and occludin. Our study highlights the potential of metformin to reduce hyperglycaemia-induced P. aeruginosa growth through airway epithelial tight junction modulation, and that claudin-1 and occludin could be important targets to regulate glucose permeability across airway epithelia and supress bacterial growth. Further investigation into the mechanisms regulating metformin and P. aeruginosa action on airway epithelial tight junctions could yield new therapeutic targets to prevent/suppress hyperglycaemia-induced respiratory infections, avoiding the use of antibiotics.

  10. Thermal cycling effects on adhesion of resin-bovine enamel junction among different composite resins.

    Science.gov (United States)

    Chen, Wen-Cheng; Ko, Chia-Ling; Wu, Hui-Yu; Lai, Pei-Ling; Shih, Chi-Jen

    2014-10-01

    Thermal cycling is used to mimic the changes in oral cavity temperature experienced by composite resins when used clinically. The purpose of this study is to assess the thermal cycling effects of in-house produced composite resin on bonding strength. The dicalcium phosphate anhydrous filler surfaces are modified using nanocrystals and silanization (w/NP/Si). The resin is compared with commercially available composite resins Filtek Z250, Z350, and glass ionomer restorative material GIC Fuji-II LC (control). Different composite resins were filled into the dental enamel of bovine teeth. The bond force and resin-enamel junction graphical structures of the samples were determined after thermal cycling between 5 and 55°C in deionized water for 600 cycles. After thermal cycling, the w/NP/Si 30wt%, 50wt% and Filtek Z250, Z350 groups showed higher shear forces than glass ionomer GIC, and w/NP/Si 50wt% had the highest shear force. Through SEM observations, more of the fillings with w/NP/Si 30wt% and w/NP/Si 50wt% groups flowed into the enamel tubule, forming closed tubules with the composite resins. The push-out force is proportional to the resin flow depth and uniformity. The push-out tubule pore and resin shear pattern is the most uniform and consistent in the w/NP/Si 50wt% group. Accordingly, this developed composite resin maintains great mechanical properties after thermal cycling. Thus, it has the potential to be used in a clinical setting when restoring non-carious cervical lesions. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Effects of organophosphate,carbamate and pyrethroid insecticides and their mixtures on neuromuscular junction transmission

    Institute of Scientific and Technical Information of China (English)

    HeFS; XiaoC

    2002-01-01

    To investigate the effects of organophosphorus (OP),carbamate (Carb),pyrehroid (Pyr) insecticides and their mixtures on neuromuscular junction transmission (NMJT),dimethoate(D) and phoxim(P),methomyl(M),and fenvalerate(F) were selected.Rats were intraperitoneally intoxicated by D,P,M,F,D+M,D+F,P+M,or P+F with the dosage of each LD50 respectively.The function of the NMJT was assessed with the mean consecutive differences (MCD) of the latencies of single fiber action potentials detected by stimulation single fiber electromyography(SSFEMG) at the stimulus frequency of 20 Hz.The SSFEMG was also applied to detect the function of NMJT in 40 patients with OPs and their mixtures poisoning in this study.The results showed that (1)the myasthenia occurred only in rats with OPs and their mixtures poisoning,but not in F,M intoxicated rats.The increase of MCD shown by SSFEMG and induced by OP and their mixtures indicating a post-synaptic block was well correlated with the occurrence of myasthenia both in rats and patients(P<0.001);(2)the increase of MCD in rats of OP poisoning was significant in comparison with the control and F,M intoxicated rats;but was not significantly different from those in rats intoxicated by OP mixtures;(3)the MCDs were significantly increased in IMS patients of both acute OP poisoning and OP mixtures poisoning,but showing no significant difference between the two groups of patients.It is concluded that OP is the only responsible agent for the dysfunction of neuromuscular transmission induced by single OP and OP mixture insecticides which could be sensitively detected by SSFEMG.

  12. Effect of Anti-Diffusion Oxide Layer on Enhanced Thermal Stability of Magnetic Tunnel Junctions

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zong-Zhi; ZHAO Hui; Cardoso S.; Freitas P. P.

    2006-01-01

    @@ Magnetic tunnel junctions (MTJs) with one proper oxidized FeOx layer placed between the Al oxide barrier and the top CoFe pinned layer show large tunnelling-magnetoresistance (TMR) signals as high as 39% after anneal at 380℃ .

  13. Charge transport across a mesoscopic superconductor–normal metal junction: coherence and decoherence effects

    NARCIS (Netherlands)

    Belogolovskii, M.; Golubov, A.; Grajcar, M.; Kupriyanov, M. Yu.; Seidel, P.

    2001-01-01

    We present a simple scattering approach to the charge transport across a realistic superconductor–normal injector interface of a finite transmittance that is modeled by a double-barrier mesoscopic junction. For a d-wave pairing symmetry, our calculations combine a fully quantum-mechanical scattering

  14. Numerical study of junction-angle effects on flow pattern in a river ...

    African Journals Online (AJOL)

    2016-01-01

    Jan 1, 2016 ... This complexity is not only because of their turbulence and intense ... The use of numerical models for simulating the flow in river junctions has ..... longitudinal velocity profiles in different sections of the main channel is shown ...

  15. Quantum interference effects at room temperature in OPV-based single-molecule junctions

    DEFF Research Database (Denmark)

    Arroyo, Carlos R.; Frisenda, Riccardo; Moth-Poulsen, Kasper

    2013-01-01

    )-phenylenevinylene (OPV3) derivatives, in which the central benzene ring is coupled to either para- or meta-positions. Using the break-junction technique, we find that the conductance for a single meta-OPV3 molecule wired between gold electrodes is one order of magnitude smaller than that of a para-OPV3 molecule...

  16. Spin-dependent Seebeck effects in a graphene superlattice p–n junction with different shapes

    Science.gov (United States)

    Zhou, Benhu; Zhou, Benliang; Yao, Yagang; Zhou, Guanghui; Hu, Ming

    2017-10-01

    We theoretically calculate the spin-dependent transmission probability and spin Seebeck coefficient for a zigzag-edge graphene nanoribbon p–n junction with periodically attached stubs under a perpendicular magnetic field and a ferromagnetic insulator. By using the nonequilibrium Green’s function method combining with the tight-binding Hamiltonian, it is demonstrated that the spin-dependent transmission probability and spin Seebeck coefficient for two types of superlattices can be modulated by the potential drop, the magnetization strength, the number of periods of the superlattice, the strength of the perpendicular magnetic field, and the Anderson disorder strength. Interestingly, a metal to semiconductor transition occurs as the number of the superlattice for a crossed superlattice p–n junction increases, and its spin Seebeck coefficient is much larger than that for the T-shaped one around the zero Fermi energy. Furthermore, the spin Seebeck coefficient for crossed systems can be much pronounced and their maximum absolute value can reach 528 μV K-1 by choosing optimized parameters. Besides, the spin Seebeck coefficient for crossed p–n junction is strongly enhanced around the zero Fermi energy for a weak magnetic field. Our results provide theoretical references for modulating the thermoelectric properties of a graphene superlattice p–n junction by tuning its geometric structure and physical parameters.

  17. Aharonov-Bohm–Type Effect for Vortices in Josephson-Junction Arrays

    NARCIS (Netherlands)

    Wees, B.J. van

    1990-01-01

    The dynamics of a single vortex present in a ring-shaped (Corbino geometry) two-dimensional array of low-capacity Josephson junctions is studied. The vortex is treated as a macroscopic quantum particle, whose energy levels En(Q0) are periodic functions of the externally induced gauge charge Q0 which

  18. Effect of the electromagnetic environment on current fluctuations in driven tunnel junctions

    Science.gov (United States)

    Frey, Moritz; Grabert, Hermann

    2016-07-01

    We examine current fluctuations in tunnel junctions driven by a superposition of a constant and a sinusoidal voltage source. In standard setups, the external voltage is applied to the tunneling element via an impedance providing an electromagnetic environment of the junction. The modes of this environment are excited by the time-dependent voltage and are the source of Johnson-Nyquist noise. We determine the autocorrelation function of the current flowing in the leads of the junction in the weak tunneling limit up to terms of second order in the tunneling Hamiltonian. The driven modes of the electromagnetic environment are treated exactly by means of a unitary transformation introduced recently. Particular emphasis is placed on the spectral function of the current fluctuations. The spectrum is found to comprise three contributions: a term arising from the Johnson-Nyquist noise of the environmental impedance, a part due to the shot noise of the tunneling element, and a third contribution which comes from the cross correlation between fluctuations caused by the electromagnetic environment and fluctuations of the tunneling current. All three parts of the spectral function occur already for devices under dc bias. The spectral function of ac driven tunneling elements can be determined from the result for a dc bias by means of a photoassisted tunneling relation of the Tien-Gordon type. Specific results are given for an Ohmic environment and for a junction driven through a resonator.

  19. Estimation of the effective intercellular diffusion coefficient in cell monolayers coupled by gap junctions

    DEFF Research Database (Denmark)

    Olesen, Niels Erik; Hofgaard, Johannes P; von Holstein-Rathlou, Niels-Henrik;

    2012-01-01

    A recently developed dye-based assay to study gap junction permeability is analysed. The assay is based on electroporation of dye into a large number of connexin 43 expressing cells, grown to confluency on electrically conductive slides. The subsequent intercellular spread of dye to non-electroporated...

  20. Electrochemical synthesis of FeS{sub 2} thin film: An effective material for peroxide sensing and terephthalic acid degradation

    Energy Technology Data Exchange (ETDEWEB)

    Jana, Sumanta [Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Howrah, 711103 WB (India); Mondal, Palash; Tripathi, Subhankar [Department of Chemistry, Vivekananda Mahavidyalaya, Burdwan, 713103 WB (India); Mondal, Anup [Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Howrah, 711103 WB (India); Chakraborty, Biswajit, E-mail: biswajitmailbag@gmail.com [Department of Chemistry, Vivekananda Mahavidyalaya, Burdwan, 713103 WB (India)

    2015-10-15

    Electrochemically FeS{sub 2} thin films have been synthesized on ITO substrates at room temperature (25 °C). UV–Vis, X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) were used for the characterization of nanostructure FeS{sub 2} thin films. Two probe I–V measurements convey that the material is p type and a p-n junction (diode) was found to be developed between FeS{sub 2} and ITO layer. Cyclic voltametry study shows that FeS{sub 2}/ITO electrode facilitates the reduction of hydrogen peroxide and exhibits excellent electro-catalytic activity towards its sensing. Photocatalytic study reveals that the synthesized thin films are also efficient to degrade terephthalic acid (TA). - Graphical abstract: Electrochemically FeS{sub 2} thin films have been synthesized on ITO substrate. The synthesized material is effective for the reduction of H{sub 2}O{sub 2} and the sensitivity of the material is strongly dependent on pH and temperature. Photocatalytic study reveals that the material is quite effective towards decomposition of terephthalic acid. These results indicate that the material can play a dual role as pollutant cleanup for environmental interest. - Highlights: • Electrochemically FeS{sub 2} thin films are synthesized. • The material is effective to sense the H{sub 2}O{sub 2} and degrade terephthalic acid. • It plays a dual role as pollutant cleanup for environmental interest.

  1. Environmental effect of vegetation restoration on degraded ecosystem in low subtropical China

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The environmental effect of degraded ecosystem's vegetation restoration in low subtropical China was studied. Results indicated thatthe vegetation recovery on degraded lands significantly ameliorates surrounding environment, increases species diversity, improves soilstructure, raises soil fertility, enhances productivity, and promotes regional agricultural production and social economic developmentdramatically. Through the combining engineering and biological measures, the restoration of degraded ecosystem in low subtropical area ispossible and economical. The restoration experience in Xiaoliang, Wuhua and other sites are valuable for other degraded subtropical area wasintroduced.

  2. Effect of salvianolate on intestinal epithelium tight junction protein zonula occludens protein 1 in cirrhotic rats

    Institute of Scientific and Technical Information of China (English)

    Dan-Hong Yang; Zai-Yuan Ye; Yuan-Jun Xie; Xu-Jun He; Wen-Juan Xu; Wei-Ming Zhou

    2012-01-01

    AIM:To study the effect of salvianolate on tight junctions (TJs) and zonula occludens protein 1 (ZO-1) in small intestinal mucosa of cirrhotic rats.METHODS:Cirrhosis was induced using carbon tetrachloride.Rats were randomly divided into the untreated group,low-dose salvianolate (12 mg/kg) treatment group,medium-dose salvianolate (24 mg/kg) treatment group,and high-dose salvianolate (48 mg/kg) treatment group,and were treated for 2 wk.Another 10 healthy rats served as the normal control group.Histological changes in liver tissue samples were observed under a light microscope.We evaluated morphologic indices of ileal mucosa including intestinal villi width and thickness of mucosa and intestinal wall using a pathological image analysis system.Ultrastructural changes in small intestinal mucosa were investigated in the five groups using transmission electron microscopy.The changes in ZO-1 expression,a tight junction protein,were analyzed by immunocytochemistry.The staining index was calculated as the product of the staining intensity score and the proportion of positive cells.RESULTS:In the untreated group,hepatocytes showed a disordered arrangement,fatty degeneration was extensive,swelling was obvious,and disorganized lobules were divided by collagen fibers in hepatic tissue,which were partly improved in the salvianolate treated groups.In the untreated group,abundant lymphocytes infiltrated the fibrous tissue with proliferation of bile ducts,and collagen fibers gradually decreased and damaged hepatic lobules were partly repaired following salvianolate treatment.Compared with the untreated group,no differences in intestinal villi width between the five groups were observed.The villi height as well as mucosa and intestinal wall thickness gradually thickened with salvianolate treatment and were significantly shorter in the untreated group compared with those in the salvianolate treatment groups and normal group (P < 0.01).The number of microvilli decreased and showed

  3. Effect of protein degradability on milk production of dairy ewes.

    Science.gov (United States)

    Mikolayunas-Sandrock, C; Armentano, L E; Thomas, D L; Berger, Y M

    2009-09-01

    The objective of this experiment was to determine the effect of protein degradability of dairy sheep diets on milk yield and protein utilization across 2 levels of milk production. Three diets were formulated to provide similar energy concentrations and varying concentrations of rumen-degradable protein (RDP) and rumen-undegradable protein (RUP): 12% RDP and 4% RUP (12-4) included basal levels of RDP and RUP, 12% RDP and 6% RUP (12-6) included additional RUP, and 14% RDP and 4% RUP (14-4) included additional RDP. Diets were composed of alfalfa-timothy cubes, whole and ground corn, whole oats, dehulled soybean meal, and expeller soybean meal (SoyPlus, West Central, Ralston, IA). Estimates of RDP and RUP were based on the Small Ruminant Nutrition System model (2008) and feed and orts were analyzed for Cornell N fractions. Eighteen multiparous dairy ewes in midlactation were divided by milk yield (low and high) into 2 blocks of 9 ewes each and were randomly assigned within block (low and high) to 3 pens of 3 ewes each. Dietary treatments were arranged in a 3 x 3 Latin square within each block and applied to pens for 14-d periods. We hypothesized that pens consuming high-RUP diets (12-6) would produce more milk and milk protein than the basal diet (12-4) and pens consuming high-RDP diets (14-4) would not produce more milk than the basal diet (12-4). Ewes in the high-milk-yield square consumed more dry matter and produced more milk, milk fat, and milk protein than ewes in the low-milk-yield square. There was no effect of dietary treatment on dry matter intake. Across both levels of milk production, the 12-6 diet increased milk yield by 14%, increased milk fat yield by 14%, and increased milk protein yield by 13% compared with the 14-4 and 12-4 diets. Gross N efficiency (milk protein N/intake protein N) was 11 and 15% greater in the 12-6 and 12-4 diets, respectively, compared with the 14-4 diet. Milk urea N concentration was greater in the 12-6 diet and tended to be

  4. Annealing effects and DLTS study on PNP silicon bipolar junction transistors irradiated by 20 MeV Br ions

    Science.gov (United States)

    Liu, Chaoming; Li, Xingji; Yang, Jianqun; Bollmann, Joachim

    2014-01-01

    Isochronal anneal sequences have been carried out on 3CG130 silicon PNP bipolar junction transistors (BJTs) irradiated with 20 MeV bromine (Br) heavy ions. The Gummel curve was utilized to characterize the annealing behavior of defects in both the emitter-base depletion region and the neutral base. The results show that the base current (IB) decreases with the increasing annealing temperature, while the collector current (IC) keeps invariably. The current gain varies slightly, when the annealing temperature (TA) is lower than 500 K, while varies rapidly at TA>550 K, and the current gain of the 3CG130 BJT annealing at 700 K almost restore to that of the pre-radiation transistor. The deep level transient spectroscopy (DLTS) data was used to assign the relative magnitude of each of the important defects. Based on the in situ electrical measurement and DLTS spectra, it is clear that the V2(+/0) trap is the main contribution to the degradation of current gain after the 20 MeV Br ions irradiation. The V2(+/0) peak has many characteristics expected for the current gain degradation.

  5. Annealing effects and DLTS study on PNP silicon bipolar junction transistors irradiated by 20 MeV Br ions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chaoming [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Li, Xingji, E-mail: lxj0218@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Yang, Jianqun [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Bollmann, Joachim [Institute of Electronics and Sensor Materials, TU Bergakademie, Freiberg 71691 (Germany)

    2014-01-21

    Isochronal anneal sequences have been carried out on 3CG130 silicon PNP bipolar junction transistors (BJTs) irradiated with 20 MeV bromine (Br) heavy ions. The Gummel curve was utilized to characterize the annealing behavior of defects in both the emitter-base depletion region and the neutral base. The results show that the base current (I{sub B}) decreases with the increasing annealing temperature, while the collector current (I{sub C}) keeps invariably. The current gain varies slightly, when the annealing temperature (T{sub A}) is lower than 500 K, while varies rapidly at T{sub A}>550 K, and the current gain of the 3CG130 BJT annealing at 700 K almost restore to that of the pre-radiation transistor. The deep level transient spectroscopy (DLTS) data was used to assign the relative magnitude of each of the important defects. Based on the in situ electrical measurement and DLTS spectra, it is clear that the V{sub 2}(+/0) trap is the main contribution to the degradation of current gain after the 20 MeV Br ions irradiation. The V{sub 2}(+/0) peak has many characteristics expected for the current gain degradation.

  6. Effects of age on long term memory for degraded speech

    Directory of Open Access Journals (Sweden)

    Christiane Thiel

    2016-09-01

    Full Text Available Prior research suggests that acoustical degradation impacts encoding of items into memory, especially in elderly subjects. We here aimed to investigate whether acoustically degraded items, that are initially encoded into memory, are more prone to forgetting as a function of age. Young and old participants were tested with a vocoded and unvocoded serial list learning task involving immediate and delayed free recall. We found that degraded auditory input increased forgetting of previously encoded items, especially in older participants. We further found that working memory capacity predicted forgetting of degraded information in young participants. In old participants, verbal IQ was the most important predictor for forgetting acoustically degraded information. Our data provide evidence that acoustically degraded information, even if encoded, is especially vulnerable to forgetting in old age.

  7. Effect of solvents on the enzyme mediated degradation of copolymers

    Science.gov (United States)

    Banerjee, Aditi; Chatterjee, Kaushik; Madras, Giridhar

    2015-09-01

    The biodegradation of polycaprolactone (PCL), polylactic acid (PLA), polyglycolide (PGA) and their copolymers, poly (lactide-co-glycolide) and poly (D, L-lactide-co-caprolactone) (PLCL) was investigated. The influence of different solvents on the degradation of these polymers at 37 °C in the presence of two different lipases namely Novozym 435 and the free lipase of porcine pancreas was investigated. The rate coefficients for the polymer degradation and enzyme deactivation were determined using continuous distribution kinetics. Among the homopolymers, the degradation of PGA was nearly an order of magnitude lower than that for PCL and PLA. The overall rate coefficients of the copolymers were higher than their respective homopolymers. Thus, PLCL degraded faster than either PCL or PLA. The degradation was highly dependent on the viscosity of the solvent used with the highest degradation observed in acetone. The degradation of the polymers in acetone was nearly twice that observed in dimethyl sulfoxide indicating that the degradation decreases with increase in the solvent viscosity. The degradation of the polymers in water-solvent mixtures indicated an optimal water content of 2.5 wt% of water.

  8. Effect of Polylactic Acid-Degradable Film Mulch on Soil Temperature and Cotton Yield

    Directory of Open Access Journals (Sweden)

    ZHANG Ni

    2016-03-01

    Full Text Available Concern on biodegradable plastic film is increasing because of pollution problems caused by the plastic films currently used. The objective of this field experiment is to evaluate the effect of two thicknesses of polyactic acid-degradable film on soil temperature and cotton yield. The results showed that small holes appeared in the polyactic acid-degradable film at 17~22 d after it was installed. Burst period appeared about 60 d after installation. Splits were observed in the polyactic acid-degradable film at 130 d after installation. Soil temperatures rose slowly under polyactic acid-degradable film during the cotton seedling stage. Daytime soil temperatures were 0.8℃ and 6.2℃ lower under 18μm and 15μm thick polyactic acid-degradable film than non-degradable plastic film(CK, respectively. Nighttime soil temperatures under the polyactic acid-degradable film were about 1℃ warmer than CK. There was no significant difference in cotton yields between the 18μm polyactic acid degradable film treatment and CK. In contrast, yields in the 15μm degradable plastic film treatment were 8.9% less than that in CK. This study indicated that 18μm polyactic acid degradable plastic film had good degradability and no negative effect on cotton growth. The 18μm polyactic acid degradable plastic film can replace ordinary plastic film in agricultural production.

  9. Josephson effect in multiterminal superconductor-ferromagnet junctions coupled via triplet components

    Science.gov (United States)

    Moor, Andreas; Volkov, Anatoly F.; Efetov, Konstantin B.

    2016-03-01

    On the basis of the Usadel equation we study a multiterminal Josephson junction. This junction is composed by "magnetic" superconductors Sm, which have singlet pairing and are separated from the normal n wire by spin filters so that the Josephson coupling is caused only by fully polarized triplet components. We show that there is no interaction between triplet Cooper pairs with antiparallel total spin orientations. The presence of an additional singlet superconductor S attached to the n wire leads to a finite Josephson current IQ with an unusual current-phase relation. The density of states in the n wire for different orientations of spins of Cooper pairs is calculated. We derive a general formula for the current IQ in a multiterminal Josephson contact and apply this formula for analysis of two four-terminal Josephson junctions of different structures. It is shown in particular that both the "nematic" and the "magnetic" cases can be realized in these junctions. In a two-terminal structure with parallel filter orientations and in a three-terminal structure with antiparallel filter orientations of the "magnetic" superconductors with attached additional singlet superconductor, we find a nonmonotonic temperature dependence of the critical current. Also, in these structures, the critical current shows a Riedel peak like dependence on the exchange field in the "magnetic" superconductors. Although there is no current through the S/n interface due to orthogonality of the singlet and triplet components, the phase of the order parameter in the superconuctor S is shown to affect the Josephson current in a multiterminal structure.

  10. Modeling Radiation Effects on a Triple Junction Solar Cell using Silvaco ATLAS

    Science.gov (United States)

    2012-06-01

    structure. Intrinsic semiconductors are impossible to create because at some point during the growth process impurities inadvertently contaminate the...crystal, called the seed, is placed into a liquid comprised of the same material as the seed and is slowly twisted and pulled upwards. If a doped...boundary which joins these two regions is known as the metallurgical junction. As soon as the two regions are joined, majority carrier electrons from

  11. Effect of deep dislocation levels in silicon on the properties of p-n junctions

    Energy Technology Data Exchange (ETDEWEB)

    Zakharov, A.G.; Dudko, V.G.; Nabokov, G.M.; Sechenov, D.A.

    1988-07-01

    We present the results of studies on the influence of deep levels, due to dislocations in electronic-grade silicon, on the lifetime of minority carriers and on the current-voltage and capacitance-voltage characteristics of p-n junctions. The parameters of the deep levels were determined by means of dynamic spectroscopy. The carrier lifetime in the high-resistance region of the p-n junction correlates well with the dislocation density and varies from 10/sup /minus/7/ sec to 3 /centered dot/10/sup /minus/6/ sec when the dislocation density N/sub d/ varies from 10/sup 7/ cm/sup /minus/2/ to 5 /centered dot/10/sup 3/ cm/sup /minus/2/. The voltage across the p-n junction at a high level of injection varies 1.6 to 6.2 v as a function of N/sub d/. The ionization energy of deep levels associated with dislocation in silicon is 0.44 and 0.57 eV, measured from the bottom of the conduction band.

  12. Effect of ultrasonication on anaerobic degradability of solid waste digestate.

    Science.gov (United States)

    Boni, M R; D'Amato, E; Polettini, A; Pomi, R; Rossi, A

    2016-02-01

    This paper evaluates the effect of ultrasonication on anaerobic biodegradability of lignocellulosic residues. While ultrasonication has been commonly applied as a pre-treatment of the feed substrate, in the present study a non-conventional process configuration based on recirculation of sonicated digestate to the biological reactor was evaluated at the lab-scale. Sonication tests were carried out at different applied energies ranging between 500 and 50,000kJ/kg TS. Batch anaerobic digestion tests were performed on samples prepared by mixing sonicated and untreated substrate at two different ratios (25:75 and 75:25 w/w). The results showed that when applied as a post-treatment of digestate, ultrasonication can positively affect the yield of anaerobic digestion, mainly due to the dissolution effect of complex organic molecules that have not been hydrolyzed by biological degradation. A good correlation was found between the CH4 production yield and the amount of soluble organic matter at the start of digestion tests. The maximum gain in biogas production was 30% compared to that attained with the unsonicated substrate, which was tentatively related to the type and concentration of the metabolic products.

  13. Long Range Magnetic Interaction between Josephson Junctions

    DEFF Research Database (Denmark)

    Grønbech-Jensen, Niels; Samuelsen, Mogens Rugholm

    1995-01-01

    A new model for magnetic coupling between long Josephson junctions is proposed. The coupling mechanism is a result of the magnetic fields outside the junctions and is consequently effective over long distances between junctions. We give specific expressions for the form and magnitude of the inter...

  14. Focused helium-ion beam irradiation effects on electrical transport properties of few-layer WSe2: enabling nanoscale direct write homo-junctions

    Science.gov (United States)

    Stanford, Michael G.; Pudasaini, Pushpa Raj; Belianinov, Alex; Cross, Nicholas; Noh, Joo Hyon; Koehler, Michael R.; Mandrus, David G.; Duscher, Gerd; Rondinone, Adam J.; Ivanov, Ilia N.; Ward, T. Zac; Rack, Philip D.

    2016-01-01

    Atomically thin transition metal dichalcogenides (TMDs) are currently receiving significant attention due to their promising opto-electronic properties. Tuning optical and electrical properties of mono and few-layer TMDs, such as tungsten diselenide (WSe2), by controlling the defects, is an intriguing opportunity to synthesize next generation two dimensional material opto-electronic devices. Here, we report the effects of focused helium ion beam irradiation on the structural, optical and electrical properties of few-layer WSe2, via high resolution scanning transmission electron microscopy, Raman spectroscopy, and electrical transport measurements. By controlling the ion irradiation dose, we selectively introduce precise defects in few-layer WSe2 thereby locally tuning the resistivity and transport properties of the material. Hole transport in the few layer WSe2 is degraded more severely relative to electron transport after helium ion irradiation. Furthermore, by selectively exposing material with the ion beam, we demonstrate a simple yet highly tunable method to create lateral homo-junctions in few layer WSe2 flakes, which constitutes an important advance towards two dimensional opto-electronic devices. PMID:27263472

  15. Electrical detection of the biological interaction of a charged peptide via gallium arsenide junction-field-effect transistors

    OpenAIRE

    Lee, Kangho; Nair, Pradeep R.; Alam, Muhammad A.; Janes, David B.; Wampler, Heeyeon P; Zemlyanov, Dmitry; Ivanisevic, Albena

    2008-01-01

    GaAs junction-field-effect transistors (JFETs) are utilized to achieve label-free detection of biological interaction between a probe transactivating transcriptional activator (TAT) peptide and the target trans-activation-responsive (TAR) RNA. The TAT peptide is a short sequence derived from the human immunodeficiency virus-type 1 TAT protein. The GaAs JFETs are modified with a mixed adlayer of 1-octadecanethiol (ODT) and TAT peptide, with the ODT passivating the GaAs surface from polar ions ...

  16. Stabilizing effects of estertins mercaptide (methyl acrylate) for PVC degradation

    Science.gov (United States)

    Zhang, S. H.; Liu, T. M.; Li, J. L.; Wang, C. R.; Li, C.; Wang, Z. Q.

    2016-07-01

    The thermal and UV light (ultraviolet light) stability of PVC films with estertins mercaptide (methyl acrylate), methyltins mercaptide and the compound consisted of estertins mercaptide (methyl acrylate) and hydrotalcite (2:2.5) were investigated by ageing in a circulation oven at 190 °C and irradiating with 72W UV light for 96h, respectively, and then the yellowness and transmission rate were tested by Color Quest XE. Hydrotalcite was proved to have good synergies with estertins mercaptide (methyl acrylate) on improving the thermal stability and UV light stability. The retarding effects of the heat stabilizers to PVC degradation were tested by TGA from 50°C to 600°C. The results show that temperature of HCl evolution from PVC film was improved obviously by compounding with estertins mercaptide(methyl acrylate) and hydrotalcite and estertins mercaptide(methyl acrylate) was found to have a better long term stability. Sn4+ consistence of water and seawater in which films before and after UV light irradiation were soaked for 60 days was analyzed by ICP; the results indicate that the Sn4+ consistence from the films with estertins mercaptide(methyl acrylate) as thermal stabilizer was lower than that from the film with methyltins mercaptide. The crosslink moderately by UV irradiation for PVC films can hold back the dissolution of organotin heat stabilizers from PVC products into water and seawater.

  17. Effects of microbial inhibitors on anaerobic degradation of DDT

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.S.; Chiu, T.C.; Yen, J.H. [National Taiwan Univ., Taipei (Taiwan)

    2004-09-15

    Chlorinated insecticide DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane] was extensively used for controlling pests in the agricultural field and human-being living environments in the past several decades. Due to the chemical stability, DDT was extremely persistent and recalcitrant in soils and sediments and it was banned by nations. Microorganisms usually play important roles in reducing organochlorine compounds in the environments. Under low-oxygen conditions, microbial dechlorination is thought as the onset of highly chlorinated compounds. Methanogenic and sulfate-reducing bacteria participate in microbial dechlorination under anaerobic condition has been reported. In this study, a mixed anaerobic culture enabling to dechlorinate DDT was obtained from river sediment in Taiwan. In order to understand the effect of these microorganisms on DDT dechlorination, microbial inhibitors BESA (2-bromoethanesulfonate) and molybdate, for inhibiting methanogenic and sulfate-reducing bacteria, respectively, were chosen to investigate the interaction between specific microbial communities and their degradation activities. Besides, a molecular technique, denaturing gradient gel electrophoresis (DGGE), based on analyzing the 16S rDNA of bacteria, was used for monitoring the bacterial community structure in this study.

  18. Effective Passivation of Exfoliated Black Phosphorus Transistors against Ambient Degradation

    OpenAIRE

    Wood, Joshua D.; Wells, Spencer A.; Jariwala, Deep; Chen, Kan-Sheng; Cho, EunKyung; Sangwan, Vinod K.; Liu, Xiaolong; Lauhon, Lincoln J.; Marks, Tobin J.; Hersam, Mark C.

    2014-01-01

    Unencapsulated, exfoliated black phosphorus (BP) flakes are found to chemically degrade upon exposure to ambient conditions. Atomic force microscopy, electrostatic force microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy are employed to characterize the structure and chemistry of the degradation process, suggesting that O2 saturated H2O irreversibly reacts with BP to form oxidized phosphorus species. This interpretation ...

  19. Soil degradation effect on biological activity in Mediterranean calcareous soils

    Science.gov (United States)

    Roca-Pérez, L.; Alcover-Sáez, S.; Mormeneo, S.; Boluda, R.

    2009-04-01

    Soil degradation processes include erosion, organic matter decline, compaction, salinization, landslides, contamination, sealing and biodiversity decline. In the Mediterranean region the climatological and lithological conditions, together with relief on the landscape and anthropological activity are responsible for increasing desertification process. It is therefore considered to be extreme importance to be able to measure soil degradation quantitatively. We studied soil characteristics, microbiological and biochemical parameters in different calcareous soil sequences from Valencia Community (Easter Spain), in an attempt to assess the suitability of the parameters measured to reflect the state of soil degradation and the possibility of using the parameters to assess microbiological decline and soil quality. For this purpose, forest, scrubland and agricultural soil in three soil sequences were sampled in different areas. Several sensors of the soil biochemistry and microbiology related with total organic carbon, microbial biomass carbon, soil respiration, microorganism number and enzyme activities were determined. The results show that, except microorganism number, these parameters are good indicators of a soil biological activity and soil quality. The best enzymatic activities to use like indicators were phosphatases, esterases, amino-peptidases. Thus, the enzymes test can be used as indicators of soil degradation when this degradation is related with organic matter losses. There was a statistically significant difference in cumulative O2 uptake and extracellular enzymes among the soils with different degree of degradation. We would like to thank Spanish government-MICINN for funding and support (MICINN, project CGL2006-09776).

  20. THE EFFECT OF DEGRADATION PROCESSES ON THE SERVICEABILITY OF BUILDING MATERIALS OF HISTORIC BUILDINGS

    Directory of Open Access Journals (Sweden)

    Jiří Witzany

    2016-10-01

    Full Text Available The article presents an analysis of degradation processes and partial results of an experimental research into materials and structures exposed to the effects of external environments with an emphasis on the effects of moisture and chemical degradation processes on major mechanical properties of sandstone.

  1. Effect of interface geometry on electron tunnelling in Al/Al2O3/Al junctions

    Science.gov (United States)

    Koberidze, M.; Feshchenko, A. V.; Puska, M. J.; Nieminen, R. M.; Pekola, J. P.

    2016-04-01

    We investigate how different interface geometries of an Al/Al2O3 junction, a common component of modern tunnel devices, affect electron transport through the tunnel barrier. We study six distinct Al/Al2O3 interfaces which differ in stacking sequences of the metal and the oxide surface atoms and the oxide termination. To construct model potential barrier profiles for each examined geometry, we rely on first-principles density-functional theory (DFT) calculations for the barrier heights and the shapes of the interface regions as well as on experimental data for the barrier widths. We show that even tiny variations in the atomic arrangement at the interface cause significant changes in the tunnel barrier parameters and, consequently, in electron transport properties. Especially, we find that variations in the crucial barrier heights and widths can be as large as 2 eV and 5 Å, respectively. Finally, to gain information about the average properties of the measured junction, we fit the conductance calculated within the Wentzel-Kramers-Brillouin approximation to the experimental data and interpret the fit parameters with the help of the DFT results.

  2. Inertia effects on bubble generation in thin T-junction microchannel

    Science.gov (United States)

    Sugiyama, Kazuyasu; Okubo, Hidehiko; Nabeshima, Seigo; Watamura, Tomoaki

    2016-11-01

    A numerical study on gas-liquid interface dynamics of bubble generation in a thin microchannel with a squeezed T-junction is performed. In consideration of liquid inertia, the basic equations consist of the Laplace law and the two-dimensional Euler-Darcy equation under the assumption of Hele-Shaw's flow owing to a large width-to-thickness aspect ratio of the channel cross-section. The velocity potential and the interface motion are numerically predicted by means of a boundary element method. The simulated results reasonably capture the experimentally observed behaviors that the interface pinches off at the channel junction and then a bubble forms. For a fixed liquid velocity, the generated bubble is likely to be smaller with decreasing the gas pressure, but the bubble is no longer generated at the gas pressure below a threshold. The bubble size minimized at the generation limit is arranged using the capillary, Reynolds and Weber numbers, and the results imply the significance of the liquid inertia in the bubble generation process in spite of the micrometer-scale phenomena.

  3. The effects of laparoscopic mesh fixation device on bone, costo-chondral junction and tendon site.

    Science.gov (United States)

    Ekçi, Baki; Altinli, Ediz; Dervisoglu, Sergülen; Demir, Mustafa; Tasci, Ihsan

    2011-01-01

    Osteitis pubis is one of the important complications of inguinal hernia repair surgery occurring with the placement of sutures through the periosteum. The aim of this study is to evaluate scintigraphic and histopathological alterations associated with the use of mesh fixation device on pelvic bone, cartilage and tendons in an experimental animal model. Twenty New-Zealand young male rabbits were used. A mesh fixation device was inserted at each animal's costa-chondral junction, superior anterior iliac crest, and achiles tendon. One week prior to the surgery and 16 weeks after the operation, scintigraphic evaluation was performed. Histopathological evaluation was performed at the end of study. No nuclear activity or pathological change was found at bone site (p > 0.05). Foreign body reaction was evident at the tendon and costa-chondral site (p = 0.001). In conclusion; the mesh fixation device leads to foreign body reaction in costa-chondral junction and tendon. It does not cause any nuclear activity increase.

  4. Effect of urea on degradation of terbuthylazine in soil.

    Science.gov (United States)

    Caracciolo, Anna Barra; Giuliano, Giuseppe; Grenni, Paola; Cremisini, Carlo; Ciccoli, Roberto; Ubaldi, Carla

    2005-05-01

    Pesticide and nitrate contamination of soil and groundwater from agriculture is an environmental and public health concern worldwide. The herbicide terbuthylazine (CBET) has replaced atrazine in Italy and in many other countries because the use of the latter has been banned because of its adverse environmental impacts. Unlike atrazine, knowledge about the fate of CBET in soil is still not extensive, especially regarding its transformation products, but recent monitoring data show its occurrence and that of its main metabolite, desethyl-terbuthylazine (CBAT), in groundwater above the limit of 0.1 microg/L established by European Union Directive and Italian legislation. The objective of this work was to investigate if the presence of the fertilizer urea affects CBET degradation in the soil. Laboratory CBET degradation experiments in the presence/absence of urea were performed with microbiologically active soil and sterilized soil. Terbuthylazine degradation rates under the different experimental conditions were assessed, and the formation, degradation, and transformation of the metabolite CBAT were also studied. Terbuthylazine degradation was affected by the presence of urea, in terms both of a higher disappearance time of 50% of the initial concentration and of a lower amount of CBAT formed. These findings have practical implications for the real-life assessment of the environmental fate of triazine herbicides in agricultural areas since these herbicides are frequently applied to soils receiving ureic fertilizers.

  5. The effect of operational parameters on the photocatalytic degradation of pesticide.

    Science.gov (United States)

    Choi, Euiso; Cho, Il-Hyoung; Park, Jaehong

    2004-01-01

    The photocatalytic degradation of Cartap Hydrochloride, a synthetic pesticide. has been investigated over coated TiO2 photocatalysts irradiated with a ultraviolet (UV) light. The effect of operational parameters, i.e., Cartap Hydrochloride concentration, reaction time, light intensity and additive on the degradation rate of aqueous solution of Cartap Hydrochloride has been examined. Results show that the employment of efficient photocatalysts and the selection of optimal operational parameters may lead to degradation of Cartap Hydrochloride solutions.

  6. Endoplasmic reticulum stress contributes to acetylcholine receptor degradation by promoting endocytosis in skeletal muscle cells.

    Science.gov (United States)

    Du, Ailian; Huang, Shiqian; Zhao, Xiaonan; Zhang, Yun; Zhu, Lixun; Ding, Ji; Xu, Congfeng

    2016-01-15

    After binding by acetylcholine released from a motor neuron, a nicotinic acetylcholine receptor at the neuromuscular junction produces a localized end-plate potential, which leads to muscle contraction. Improper turnover and renewal of acetylcholine receptors contributes to the pathogenesis of myasthenia gravis. In the present study, we demonstrate that endoplasmic reticulum (ER) stress contributes to acetylcholine receptor degradation in C2C12 myocytes. We further show that ER stress promotes acetylcholine receptor endocytosis and lysosomal degradation, which was dampened by blocking endocytosis or treating with lysosome inhibitor. Knockdown of ER stress proteins inhibited acetylcholine receptor endocytosis and degradation, while rescue assay restored its endocytosis and degradation, confirming the effects of ER stress on promoting endocytosis-mediated degradation of junction acetylcholine receptors. Thus, our studies identify ER stress as a factor promoting acetylcholine receptor degradation through accelerating endocytosis in muscle cells. Blocking ER stress and/or endocytosis might provide a novel therapeutic approach for myasthenia gravis.

  7. Interfacial spin-filter assisted spin transfer torque effect in Co/BeO/Co magnetic tunnel junction

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Y.-H., E-mail: yhtang@cc.ncu.edu.tw; Chu, F.-C. [Department of Physics, National Central University, Jung-Li 32001, Taiwan (China)

    2015-03-07

    The first-principles calculation is employed to demonstrate the spin-selective transport properties and the non-collinear spin-transfer torque (STT) effect in the newly proposed Co/BeO/Co magnetic tunnel junction. The subtle spin-polarized charge transfer solely at O/Co interface gives rise to the interfacial spin-filter (ISF) effect, which can be simulated within the tight binding model to verify the general expression of STT. This allows us to predict the asymmetric bias behavior of non-collinear STT directly via the interplay between the first-principles calculated spin current densities in collinear magnetic configurations. We believe that the ISF effect, introduced by the combination between wurtzite-BeO barrier and the fcc-Co electrode, may open a new and promising route in semiconductor-based spintronics applications.

  8. Effects of viscoelasticity on droplet dynamics and break-up in microfluidic T-Junctions: a lattice Boltzmann study

    CERN Document Server

    Gupta, Anupam

    2015-01-01

    The effects of viscoelasticity on the dynamics and break-up of fluid threads in microfluidic T-junctions are investigated using numerical simulations of dilute polymer solutions at changing the Capillary number ($\\mbox {Ca}$), i.e. at changing the balance between the viscous forces and the surface tension at the interface, up to $\\mbox{Ca} \\approx 3 \\times 10^{-2}$. A Navier-Stokes (NS) description of the solvent based on the lattice Boltzmann models (LBM) is here coupled to constitutive equations for finite extensible non-linear elastic dumbbells with the closure proposed by Peterlin (FENE-P model). We present the results of three-dimensional simulations in a range of $\\mbox{Ca}$ which is broad enough to characterize all the three characteristic mechanisms of breakup in the confined T-junction, i.e. ${\\it squeezing}$, ${\\it dripping}$ and ${\\it jetting}$ regimes. The various model parameters of the FENE-P constitutive equations, including the polymer relaxation time $\\tau_P$ and the finite extensibility para...

  9. Parameters effect on heterogeneous photocatalysed degradation of phenol in aqueous dispersion of TiO2

    Institute of Scientific and Technical Information of China (English)

    KASHIF Naeem; OUYANG Feng

    2009-01-01

    In this study, photocatalytic degradation of phenol selected as model compound of organic pollutant had been investigated in aqueous titanium dioxide (TiO2) dispersion under UV irradiation. The effects of various parameters such as pH, catalyst concentration, phenol concentration, anions, metal ions, electron acceptors, and surfactants on the photocatalytic degradation of phenol were investigated. The degradation kinetics was determined by the change in phenol concentration employing UV-Vis spectrometry as a function of irradiation time. The degradation kinetics of phenol follows pseudo first-order kinetics. The results showed a significant dependence of the photocatalytic degradation of phenol on the functional parameters. The probable promising roles of the additives on the degradation process were discussed.

  10. Effect of grass species on NDF ruminal degradability and ...

    African Journals Online (AJOL)

    uzivatel

    Yan & Agnew (2004) noted that despite being a major feed for ruminants across the world, the ... The extent and rate of digestion of structural carbohydrates of the cell wall, which is mainly degraded .... the equations, as NDF is by definition insoluble. ..... Prediction of the relative intake potential of grass silage by dairy cows.

  11. Veterinary antibiotic effects on atrazine degradation and soil microorganisms

    Science.gov (United States)

    Veterinary antibiotics (VAs) in manure applied to agricultural lands may change agrichemical degradation by altering soil microbial community structure or function. The objectives of this study were to investigate the influence of two VAs, sulfamethazine (SMZ) and oxytetracycline (OTC), on atrazine ...

  12. Large magnetocapacitance effect in magnetic tunnel junctions based on Debye-Fröhlich model

    Energy Technology Data Exchange (ETDEWEB)

    Kaiju, Hideo, E-mail: kaiju@es.hokudai.ac.jp; Takei, Masashi; Misawa, Takahiro; Nishii, Junji [Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido 001-0020 (Japan); Nagahama, Taro [School of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628 (Japan); Xiao, Gang [Department of Physics, Brown University, Providence, Rhode Island 02912 (United States)

    2015-09-28

    The frequency dependence of tunneling magnetocapacitance (TMC) in magnetic tunnel junctions (MTJs) is investigated theoretically and experimentally. According to the calculation based on Debye-Fröhlich model combined with Julliere formula, the TMC ratio strongly depends on the frequency and it has the maximum peak at a specific frequency. The calculated frequency dependence of TMC is in good agreement with the experimental results obtained in MgO-based MTJs with a tunneling magnetoresistance (TMR) ratio of 108%, which exhibit a large TMC ratio of 155% at room temperature. This calculation also predicts that the TMC ratio can be as large as about 1000% for a spin polarization of 87%, while the TMR ratio is 623% for the same spin polarization. These theoretical and experimental findings provide a deeper understanding on AC spin-dependent transport in the MTJs and will open up wider opportunities for device applications, such as highly sensitive magnetic sensors and impedance-tunable devices.

  13. Possible resonance effect of axionic dark matter in S/N/S Josephson junctions

    CERN Document Server

    Beck, Christian

    2013-01-01

    We provide theoretical arguments that dark matter axions from the galactic halo that pass through the earth may generate a small observable signal in resonant S/N/S Josephson junctions. The corresponding interaction process is based on uniqueness of the gauge-invariant axion Josephson phase angle modulo 2 pi and is predicted to produce a small Shapiro step-like feature without externally applied microwave radiation when the Josephson frequency resonates with the axion mass. A resonance signal of so far unknown origin observed in [C. Hoffmann et al. PRB 70, 180503(R) (2004)] is consistent with our theory and can be interpreted in terms of an axion mass of 0.11 meV and a local galactic axionic dark matter density of 0.05 GeV/cm^3. We discuss future experimental checks to confirm the dark-matter nature of the observed signal.

  14. Biological degradation and microbial function effect of norfloxacin in a soil under different conditions.

    Science.gov (United States)

    Yang, Ji-Feng; Ying, Guang-Guo; Liu, Shan; Zhou, Li-Jun; Zhao, Jian-Liang; Tao, Ran; Peng, Ping-An

    2012-01-01

    This paper investigated the degradation kinetics of norfloxacin in a soil, and its effects on soil respiration and nitrogen transformation under different conditions. Compared to the sterile control, the degradation rates of norfloxacin in the non-sterile soil were greatly enhanced, suggesting that microorganisms played a major role in the degradation. Accelerated degradation for norfloxacin in the soil was observed with decreasing concentrations (30 mg/kg to 5 mg/kg) with its half-life decreasing from 62 days to 31 days. Amending swine manure into the soil and increasing the soil moisture level enhanced the biological degradation of norfloxacin. No obvious inhibition of norfloxacin on soil respiration was observed in the soil, while only slight effect on nitrogen transformation was found. The results suggested that norfloxacin at the reported environmental concentrations (<100 mg/kg) would have little effect on microbial activity and functions in the soils.

  15. Effect of cyto/chemokine degradation in effective intercellular communication distances.

    Science.gov (United States)

    Gupta, V K

    2017-02-15

    Many complex biological processes such as cell differentiation, cell proliferation, and cell motility are governed by cell signaling. This mode of intercellular communication is of paramount importance for tissue function and ultimately for entire organism. In intercellular communication cells secrete signaling molecules such as cyto/chemokines which diffuse through the surrounding medium and eventually bind to receptors on other cells whereby the signal transduction is completed. An accurate estimation of the effective communication distances and the time scale on which signaling takes place are important for the interpretation of cell and organ physiology and ultimately in the effective and efficient chemotactically driven tissue engineering. The present study uses a solitary cell model incorporating degradation of secreted molecules to estimate the effective communication distances and the time scale on which signaling takes place. We demonstrate through our model that in presence of degradation the effective communication distances are significantly reduced.

  16. Effect of cyto/chemokine degradation in effective intercellular communication distances

    Science.gov (United States)

    Gupta, V. K.

    2017-02-01

    Many complex biological processes such as cell differentiation, cell proliferation, and cell motility are governed by cell signaling. This mode of intercellular communication is of paramount importance for tissue function and ultimately for entire organism. In intercellular communication cells secrete signaling molecules such as cyto/chemokines which diffuse through the surrounding medium and eventually bind to receptors on other cells whereby the signal transduction is completed. An accurate estimation of the effective communication distances and the time scale on which signaling takes place are important for the interpretation of cell and organ physiology and ultimately in the effective and efficient chemotactically driven tissue engineering. The present study uses a solitary cell model incorporating degradation of secreted molecules to estimate the effective communication distances and the time scale on which signaling takes place. We demonstrate through our model that in presence of degradation the effective communication distances are significantly reduced.

  17. Effects of forest fragmentation and habitat degradation on West African leaf-litter frogs

    NARCIS (Netherlands)

    Hillers, A.; Veith, M.; Rödel, M.-O.

    2008-01-01

    Habitat degradation alters the dynamics and composition of anuran assemblages in tropical forests. The effects of forest fragmentation on the composition of anuran assemblages are so far poorly known. We studied the joint influence of forest fragmentation and degradation on leaf-litter frogs. We spe

  18. Effects of forest fragmentation and habitat degradation on West African leaf-litter frogs

    NARCIS (Netherlands)

    Hillers, A.; Veith, M.; Rödel, M.-O.

    2008-01-01

    Habitat degradation alters the dynamics and composition of anuran assemblages in tropical forests. The effects of forest fragmentation on the composition of anuran assemblages are so far poorly known. We studied the joint influence of forest fragmentation and degradation on leaf-litter frogs. We

  19. Zeeman effects on d-wave superconductor and tunneling spectrum in normal-metal/d-wave superconductor tunnel junction

    Institute of Scientific and Technical Information of China (English)

    DONG Zhengchao

    2006-01-01

    We study the Zeeman effect on the d-wave superconductor and tunneling spectrum in normal-metal(N)/d-wave superconductor(S) junction by applying a Zeeman magnetic field to the S. It is shown that: (1) the Zeeman magnetic field can lead to the S gap decreasing, and with the increase in Zeeman energy, the superconducting state is changed to the normal state, exhibiting a first-order phase transition; (2) the Zeeman energy difference between the two splitting peaks in the conductance spectrum is equal to2h0 (h0 is the Zeeman energy); (3) both the barrier strength of interface scattering and the temperature can lower the magnitudes of splitting peaks, of which the barrier strength can lead to the splitting peaks becoming sharp and the temperature can smear out the peaks,however, neither of them can influence the Zeeman effect.

  20. Perpendicular magnetic anisotropy influence on voltage-driven spin-diode effect in magnetic tunnel junctions: A micromagnetic study

    Science.gov (United States)

    Frankowski, Marek; Chȩciński, Jakub; Skowroński, Witold; Stobiecki, Tomasz

    2017-05-01

    We study the influence of the perpendicular magnetic anisotropy on the voltage-induced ferromagnetic resonance in magnetic tunnel junctions (MTJs). An MTJ response to the applied radio-frequency voltage excitation is investigated using micromagnetic calculations with the free layer oriented both in-plane and out-of-plane. Our model allows for a quantitative description of the magnetic system parameters such as resonance frequency, sensitivity or quality factor and for a distinction between material-dependent internal damping and disorder-dependent effective damping. We find that the sensitivity abruptly increases up to three orders of magnitude near the anisotropy transition regime, while the quality factor declines due to effective damping increase. We attribute the origin of this behaviour to the changes of the exchange energy in the system, which is calculated using micromagnetic approach.

  1. Homo-junction ferroelectric field-effect-transistor memory device using solution-processed lithium-doped zinc oxide thin films

    KAUST Repository

    Nayak, Pradipta K.

    2012-06-22

    High performance homo-junction field-effect transistor memory devices were prepared using solution processed transparent lithium-doped zinc oxide thin films for both the ferroelectric and semiconducting active layers. A highest field-effect mobility of 8.7 cm2/Vs was obtained along with an Ion/Ioff ratio of 106. The ferroelectric thin filmtransistors showed a low sub-threshold swing value of 0.19 V/dec and a significantly reduced device operating voltage (±4 V) compared to the reported hetero-junction ferroelectrictransistors, which is very promising for low-power non-volatile memory applications.

  2. Degradation increase responses of priming effects to temperature in Tibetan alpine grasslands

    Science.gov (United States)

    Sun, Yue; Li, Qianru; Schleuss, Per; Hua, Ouyang; Kuzyakov, Yakov

    2016-04-01

    Kobresia grassland in Tibet plateau, with a rich storage of soil organic carbon (SOC), is very important to both ecosystem function and the livelihoods of local pastoral communities. But its intensive degradation in recent decades has led to unclear consequences for SOC stocks and dynamics. Kobresia grassland acts as a critical "first response region" to climate change, where the SOC decomposition is highly sensitive to temperature, and can produce positive C climate feedback. Priming effects, induced by inputs of labile organic carbon (LOC), can also affect SOC dynamic. Therefore, knowledge about how the priming effects response to temperature, and how their interactions affect SOC decomposition are central to understanding the carbon cycle of Tibet plateau under global warming. To this ends, we conducted a laboratory incubation experiment with the non-degraded soil collected from intact Kobresia patches, and degraded soil collected from crust patches, labeled with 14C-glucose in high/low level and incubated under 0 °C, 10 °C and 20 °C for 80 days. Cumulated CO2 emission increased significantly with temperature. Degraded soil showed lower CO2 emission at 0 °C, but significant higher CO2 emission at higher temperature compared to that of non-degraded soil. Priming positively responded to increasing temperature, with 78.9% increment in degraded soil and 12.9% in non-degraded soil on average, and at 20 °C, it was significant higher in degraded soil than non-degraded soil. Low-level glucose input led to the positive priming effects, while high-level glucose induced the negative priming. Higher temperature led to higher microbial activity (i.e., qCO2) and enzyme activity (i.e., β-glucosidases, chitinase, cellobiohydrolase and Xylosidase). Vmax of enzyme was significantly higher in degraded soil than in non-degraded soil, exhibiting a positive linear regression with priming effects. In conclusion, increase in temperature improved priming effects via higher microbe

  3. Effective photocatalytic degradation of atrazine over titania-coated carbon nanotubes (CNTs) coupled with microwave energy.

    Science.gov (United States)

    Chen, Hongzhe; Yang, Shaogui; Yu, Kai; Ju, Yongming; Sun, Cheng

    2011-04-14

    Microwave-assisted photocatalytic (MAPC) degradation of atrazine over nanotitania coated multiwalled carbon nanotubes (TiO(2)/MWCNTs) was investigated in this study. As a result, degradation efficiency of atrazine over TiO(2)/CNTs prepared by hydrothermal method was about 30% and 20% higher than that of titania P25 and anatase prepared hydrothermally in given time. The TiO(2)/CNTs composite samples were characterized by TGA-DSC, TEM, UV-vis DRS, XRD and BET, to explain the reason for efficient degradation and adsorption process of atrazine. Microwave thermal effect in this process was also investigated. Intermediates of degradation both in MAPC process and microwave-assisted photodegradation (MAPD) process were identified by LC/MS. It suggests that MWCNTs have special effects on atrazine degradation during MAPC process, like strong microwave absorption capability.

  4. Degradation of methyl orange through synergistic effect of zirconia nanotubes and ultrasonic wave.

    Science.gov (United States)

    Zhao, Jianling; Wang, Xixin; Zhang, Libin; Hou, Xiaorui; Li, Ying; Tang, Chengchun

    2011-04-15

    Zirconia nanotubes with a length of 25 μm, inner diameter of 80 nm, and wall thickness of 35 nm were prepared by anodization method in mixture of formamide and glycerol (volume ratio = 1:1) containing 1 wt% NH(4)F and 1 wt% H(2)O. Experiments showed that zirconia nanotubes and ultrasonic wave had synergistic degradation effect for methyl orange and the efficiency of ultrasonic wave increased by more than 7 times. The decolorization percentage was influenced by pH value of the solution. Methyl orange was easy to be degraded in acidic solution. The decolorization percentage of methyl orange reached 97.6% when degraded for 8h in 20mg/L methyl orange solution with optimal pH value 2. The reason of synergistic degradation effect for methyl orange might be that adsorption of methyl orange onto zirconia nanotubes resulted in the easy degradation of the methyl orange through ultrasonic wave.

  5. Effect of electron beam irradiation on the degradation of monochlorophenols in aqueous solution

    Institute of Scientific and Technical Information of China (English)

    ADELEKE Olukunle Francis; ZHOU Rui-min; Zu Jian-hua; Ekoko Bakambo Gracien

    2005-01-01

    Electron beam was successfully used for the degradation of 2-chlorophenol (2-CP) and 4-chlorophenol (4-CP) in aqueous solutions in this research. The effect of radiation dose on substrate degradation and dechlorination of solutions with concentration of 50 mg/L was investigated. The effect of initial concentration, pH and presence of oxygen was also investigated. The concentration of 2-CP and 4-CP remaining in solution after irradiation were measured by HPLC. The results showed that increased radiation dose led to increased degradation of the chlorophenols and increased Cl- yield. Deaeration was also found to significantly increase the rate of degradation of chlorophenols in water while degradation and dechlorination under alkaline condition was lower than at low to neutral pH.

  6. Modulatory effects of cAMP and PKC activation on gap junctional intercellular communication among thymic epithelial cells

    Directory of Open Access Journals (Sweden)

    Neves-dos-Santos Sandra

    2010-01-01

    Full Text Available Abstract Background We investigated the effects of the signaling molecules, cyclic AMP (cAMP and protein-kinase C (PKC, on gap junctional intercellular communication (GJIC between thymic epithelial cells (TEC. Results Treatment with 8-Br-cAMP, a cAMP analog; or forskolin, which stimulates cAMP production, resulted in an increase in dye transfer between adjacent TEC, inducing a three-fold enhancement in the mean fluorescence of coupled cells, ascertained by flow cytometry after calcein transfer. These treatments also increased Cx43 mRNA expression, and stimulated Cx43 protein accumulation in regions of intercellular contacts. VIP, adenosine, and epinephrine which may also signal through cyclic nucleotides were tested. The first two molecules did not mimic the effects of 8-Br-cAMP, however epinephrine was able to increase GJIC suggesting that this molecule functions as an endogenous inter-TEC GJIC modulators. Stimulation of PKC by phorbol-myristate-acetate inhibited inter-TEC GJIC. Importantly, both the enhancing and the decreasing effects, respectively induced by cAMP and PKC, were observed in both mouse and human TEC preparations. Lastly, experiments using mouse thymocyte/TEC heterocellular co-cultures suggested that the presence of thymocytes does not affect the degree of inter-TEC GJIC. Conclusions Overall, our data indicate that cAMP and PKC intracellular pathways are involved in the homeostatic control of the gap junction-mediated communication in the thymic epithelium, exerting respectively a positive and negative role upon cell coupling. This control is phylogenetically conserved in the thymus, since it was seen in both mouse and human TEC preparations. Lastly, our work provides new clues for a better understanding of how the thymic epithelial network can work as a physiological syncytium.

  7. The effects of visual degradation on face discrimination.

    Science.gov (United States)

    McCulloch, Daphne L; Loffler, Gunter; Colquhoun, Kirsty; Bruce, Natalie; Dutton, Gordon N; Bach, Michael

    2011-05-01

    People with reduced visual acuity (VA) and/or contrast sensitivity have difficulty recognizing faces and facial expressions. We have quantified these difficulties, using a synthetic face discrimination task employing both normal and artificially degraded vision. VA and contrast thresholds were measured using an optimised staircase procedure [Freiburg acuity Test (FrACT)] in 25 young adults (aged 18-24 years) with corrected visual acuity of 0.0 logMAR or better and with four levels of vision degraded with Bangerter occlusion foils. For face discrimination, male face images were synthesised from 37 cardinal points (position of eyes, width of nose, head shape etc) derived from frontal face photographs and manipulated by altering the points as a fraction of the mean head radius. Face discrimination thresholds (% difference) were measured from a simultaneous four-alternative forced choice of 'odd one out' from three identical faces and one that differed. Psychometric functions were measured for four participants with normal and degraded vision. Subsequently, the difference between faces was fixed at twice the discrimination thresholds and the size of the faces manipulated using the FrACT threshold procedure in 25 participants. Data were converted to equivalent face discrimination distances for realistic face dimensions. With normal vision, face discrimination thresholds ranged from 2.7% to 5.6%; these increased systematically and were more variable with visual degradation. When manipulating face size, face discrimination distance was highly correlated with both acuity and contrast sensitivity (r(2) = 0.77 and 0.80 respectively, p discrimination distance was reduced to 3.9 m (3.7-4.1, ±S.E.M.). Poor face discrimination has a profound impact on real-life social communication. Here we report that artificial visual degradation also adversely impacts a synthetic face recognition task. As a rule of thumb, reduction in VA of 0.3 logMAR (halving the decimal VA) reduces the

  8. The effect of the ferromagnetic metal layer on tunnelling conductance and magnetoresistance in double magnetic planar junctions

    Institute of Scientific and Technical Information of China (English)

    谢征微; 李伯臧; 李玉现

    2002-01-01

    Based on the free-electron approximation, we investigate the effect of the ferromagnetic metal layer on the tunnelling magnetoresistance (TMR) and tunnelling conductance (TC) in the double magnetic tunnel junctions (DMTJs)of the structure NM/FM/Ⅰ(S)/NM/Ⅰ(S)/FM/NM, where FM, NM and Ⅰ(S) represent the ferromagnetic metal, nonmagnetic metal and insulator (semiconductor), respectively. The FM, Ⅰ(S) and inner NM layers are of finite thickness,while the thickness of the outer NM layer is infinite. The calculated results show that, due to the spin-dependent interfacial potential barriers caused by electronic band mismatch between the various magnetic and nonmagnetic layers,the dependences of the TMR and TC on the thicknesses of the FM layers exhibit oscillations, and a much higher TMR can be obtained for suitable thicknesses of FM layers.

  9. Van der Waals metal-semiconductor junction: Weak Fermi level pinning enables effective tuning of Schottky barrier.

    Science.gov (United States)

    Liu, Yuanyue; Stradins, Paul; Wei, Su-Huai

    2016-04-01

    Two-dimensional (2D) semiconductors have shown great potential for electronic and optoelectronic applications. However, their development is limited by a large Schottky barrier (SB) at the metal-semiconductor junction (MSJ), which is difficult to tune by using conventional metals because of the effect of strong Fermi level pinning (FLP). We show that this problem can be overcome by using 2D metals, which are bounded with 2D semiconductors through van der Waals (vdW) interactions. This success relies on a weak FLP at the vdW MSJ, which is attributed to the suppression of metal-induced gap states. Consequently, the SB becomes tunable and can vanish with proper 2D metals (for example, H-NbS2). This work not only offers new insights into the fundamental properties of heterojunctions but also uncovers the great potential of 2D metals for device applications.

  10. Effectiveness of a model constructed wetland system containing Cyperus papyrus in degrading diesel oil

    Science.gov (United States)

    Harbowo, Danni Gathot; Choesin, Devi Nandita

    2014-03-01

    Synergism between wetland systems and the provision of degrading bacterial inoculum is now being developed for the recovery of areas polluted waters of pollutants. In connection with the frequent cases of diesel oil pollution in the waters of Indonesia, we need a way of water treatment as an efficient. In this study conducted a series of tests to develop an construcred wetland design that can effectively degrade diesel oil. Tested five systems: blanko (A), substrated, without bacterial inoculums, and vegetation (B); with the addition of inoculum (C); subsrated and vegetated (D); substrated and vegetated with the addition of inoculum (E). Vegetation used in this study is Cyperus papyrus because it has the ability to absorb pollutants. Inoculum used was Pseudomonas aeruginosa and Enterobacter aerogenes which is a bacteria degrading organic compounds commonly found in water. To measure the effectiveness of the system, use several indicators to see the degradation of pollutants, namely changes in viscosity, surface tension of pollutants, and the emergence of compound degradation. Based on the results of the study can be determined that the substrated and vegetated system with Cyperus papyrus inoculum (E) was considered the most capable of degrading diesel oil due to the large changes in all parameters. In the system E, 40.6% increase viscosity, surface tension decreased 32.7%, the appearance of degradation compounds with relatively 3614.7 points, and increased to 227.8% TDS. In addition the environmental conditions in the system E also supports the growth of vegetation and degrading microbes.

  11. Nonlinear damping effects in spin torque dynamics of magnetic tunnel junctions

    Science.gov (United States)

    Barsukov, Igor; Chen, Yu-Jin; Lee, Han Kyu; Goncalves, Alexandre; Katine, Jordan; Arias, Rodrigo; Ivanov, Boris; Krivorotov, Ilya

    2015-03-01

    Performance of nanoscale spin torque devices such as memory (STT-MRAM) and auto-oscillators critically depends on magnetic relaxation. It is commonly assumed that magnetization dynamics in the presence of spin torque can be understood as simple competition between antidamping arising from spin torque and Gilbert damping of the free layer. However our experiments reveal that the situation is more complex and that nonlinear damping processes in the free layer of magnetic tunnel junction (MTJ) nanopillars can strongly alter spin torque driven dynamics. We study elliptical MTJ nanopillars with in-plane magnetizations of the free layer and SAF layers by spin torque ferromagnetic resonance. We find an excitation spectrum associated with standing spin waves of the free layer. By varying the external field, the energy of a higher-order spin wave mode becomes twice the energy of the main mode. This opens up a nonlinear, resonant relaxation channel, giving rise to a damping increase of approximately 20 percent. With increasing spin torque provided by a DC bias current, we find that this relaxation channel competes with antidamping in a nonlinear manner, increasingly contributing to and even dominating the relaxation at subcritical currents.

  12. Effects of aging on the architecture of the ileocecal junction in rats

    Institute of Scientific and Technical Information of China (English)

    Maria Cícera de Brito; Renato Paulo Chopard; Diego Pulzatto Cury; Ii Sei Watanabe; Cristina Eusébio Mendes; Patricia Castelucci

    2016-01-01

    AIM: To evaluate the structural organization of the elastic and collagen fibers in the region of the ileocecal transition in 30 young and old male Wistar rats. METHODS: Histology, immunohistochemistry(IHC), transmission electron microscopy and scanning electron microscopy were employed in this study. The results demonstrated that there was a demarcation of the ileocecal region between the ileum and the cecum in both groups. RESULTS: The connective tissue fibers had different distribution patterns in the two groups. IHC revealed the presence of nitric oxide synthase, enteric neurons and smooth muscle fibers in the ileocecal junctions(ICJs) of both groups. Compared to the young group, the elderly group exhibited an increase in collagen type Ⅰ?fibers, a decrease in collagen type Ⅲ fibers, a decreased linear density of oxytalan elastic fibers, and a greater linear density of elaunin and mature elastic fibers. CONCLUSION: The results revealed changes in the patterns of distribution of collagen and elastic fibers that may lead to a possible decrease in ICJ functionality.

  13. Effects of Different Solvents on the Planar Hetero-junction Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Lin Shunquan

    2015-01-01

    Full Text Available The perovskite (CH3NH3PbI3 films on the planar hetero-junction perovskite solar cells (PHJ-PSCs are fabricated by “two-steps” process with the wet spin-coating method. The precursor (PbI2 solutions are compounded with 4 types of solvents: N-Methyl Pyrrolidone (NMP, γ-butyrolactone (GBL, Dimethyl Sulfoxide (DMSO and N, N-dimethylformamide (DMF. All the solutions have the same concentration. The influences of different precursor solvents to the micro-structures of CH3NH3PbI3 films and device performance are studied. Atomic force microscopy (AFM and scanning electron microscope (SEM are used to characterize the CH3NH3PbI3 films. The results indicate that the CH3NH3PbI3 film using DMF solvent possesses more rough morphology and thickest thickness. The monolithic PHJ-PSCs devices based on DMF solvent are tested under a standard one sun of simulated solar irradiation (AM1.5. The results show that the open-circuit voltage (Voc reaches 872mV, the short-circuit current (Jsc reaches 9.35mA/cm2, the filling factor(FF is 0.62 and the photo-current conversion efficiency (PCE is 5.05%. DMF is the best one among these 4 types of solvents for PHJ-PSCs.

  14. Perfect GMR effect in gapped graphene-based ferromagnetic normal ferromagnetic junctions

    Institute of Scientific and Technical Information of China (English)

    Hossein Karbaschi; Gholam Reza Rashedi

    2015-01-01

    We investigate the quantum transport property in gapped graphene-based ferromagnetic/normal/ferromagnetic (FG/NG/FG) junctions by using the Dirac–Bogoliubov–de Gennes equation. The graphene is fabricated on SiC and BN substrates separately, so carriers in FG/NG/FG structures are considered as massive relativistic particles. Transmission prob-ability, charge, and spin conductances are studied as a function of exchange energy of ferromagnets (h), size of graphene gap, and thickness of normal graphene region (L) respectively. Using the experimental values of Fermi energy in the normal graphene part (EFN∼400 meV) and energy gap in graphene (260 meV for SiC and 50 meV for BN substrate), it is shown that this structure can be used for both spin-up and spin-down polarized current. The latter case has different behavior of gapped FG/NG/FG from that of gapless FG/NG/FG structures. Also perfect charge giant magnetoresistance is observed in a range of EFN−mv2F

  15. Strength of the symmetry spin-filtering effect in magnetic tunnel junctions

    Science.gov (United States)

    Faleev, Sergey V.; Mryasov, Oleg N.; Parkin, Stuart S. P.

    2016-11-01

    We developed a general theory that allows us to predict the power factor n in the asymptotics of the tunneling magnetoresistance (TMR), TMR∝Nn , in the limit of large number of the tunnel barrier layers, N , for a magnetic tunnel junction (MTJ) system that has the so-called symmetry spin-filtering properties. Within this theory the only information required to determine n is the knowledge of the symmetries of the wave functions of the bulk electrode and barrier materials at the Γ point in the in-plane surface Brillouin zone. In particular, we show that for a MTJ that has the in-plane square symmetry only three values for the power factor are allowed: n =0 ,1 , and 2 for the asymptotics of the TMR enhanced due to the symmetry spin-filtering mechanism. To verify our theory we performed the density functional theory calculations of transmission functions and TMR for a Fe/MgO/Fe MTJ which confirm predicted values of the power factor n =0 ,1 , or 2 in specific ranges of energies (in particular, n =1 at the Fermi energy).

  16. Effects of gap junction inhibition on contraction waves in the murine small intestine in relation to coupled oscillator theory

    Science.gov (United States)

    Huizinga, Jan D.

    2014-01-01

    Waves of contraction in the small intestine correlate with slow waves generated by the myenteric network of interstitial cells of Cajal. Coupled oscillator theory has been used to explain steplike gradients in the frequency (frequency plateaux) of contraction waves along the length of the small intestine. Inhibition of gap junction coupling between oscillators should lead to predictable effects on these plateaux and the wave dislocation (wave drop) phenomena associated with their boundaries. It is these predictions that we wished to test. We used a novel multicamera diameter-mapping system to measure contraction along 25- to 30-cm lengths of murine small intestine. There were typically two to three plateaux per length of intestine. Dislocations could be limited to the wavefronts immediately about the terminated wave, giving the appearance of a three-pronged fork, i.e., a fork dislocation; additionally, localized decreases in velocity developed across a number of wavefronts, ending with the terminated wave, which could appear as a fork, i.e., slip dislocations. The gap junction inhibitor carbenoxolone increased the number of plateaux and dislocations and decreased contraction wave velocity. In some cases, the usual frequency gradient was reversed, with a plateau at a higher frequency than its proximal neighbor; thus fork dislocations were inverted, and the direction of propagation was reversed. Heptanol had no effect on the frequency or velocity of contractions but did reduce their amplitude. To understand intestinal motor patterns, the pacemaker network of the interstitial cells of Cajal is best evaluated as a system of coupled oscillators. PMID:25501550

  17. Assessment of Pressure Fluctuation Effect for Thermal Fatigue in a T-junction Using Thermo-Hydro Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Pyo, Jaebum; Kim, Jungwoo; Huh, Namsu [Seoul National Univ. of Science and Technology, Seoul (Korea, Republic of); Kim, Sunhye [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2013-10-15

    As a result, when evaluating thermal fatigue for the mixing tee, temperature fluctuation is dominant for this phenomenon, it can be reasonably assumed that the pressure is constant on the pipe inner wall. Recently, thermal fatigue due to mixing of the fluids having different temperatures has been considered as an important issue on the fatigue evaluation of nuclear piping. Mainly, this phenomenon occurs in a T-junction operating with the fluids consisted of different temperatures. Because of the turbulent mixing of hot and cold water, the temperature on the inner wall of the pipe fluctuates rapidly, causing the variation of thermal stresses in the pipe and resulting in high cycle thermal fatigue. In practice, cracking by high cycle thermal fatigue is reported at a T-junction in the residual heat removal system at Civaux unit 1 in France. However, because of irregular flow inside the pipe, the pressure also fluctuates rapidly as well as temperature in the inner wall of the pipe. Therefore, in this paper, three-dimensional thermo-hydro analysis was performed for the mixing tee of the shutdown cooling system of the pressurized water reactor plant, examining the pressure variation at the pipe inner wall. Based on the analysis result, this study aims at assessing the pressure fluctuation effect on the thermal fatigue. In this paper, it is verified that there is pressure fluctuation as well as temperature on the inner wall of mixing tee operating with the fluids having different temperatures. However, since the amplitude of pressure is relatively smaller than design pressure of the shutdown cooling system, the effect wouldn't be important for the thermal fatigue.

  18. Effects of magnetic field orientation and injected current density on the output of nano-structured Co/Cu/Fe junctions

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Co/Cu/Fe nano-sized sandwich thin films have been prepared by electron beam evaporation. 5 μm×5 μm Co/Cu/Fe sandwich heterojunction was made using photolithography and lift-off process. The bipolar output signal of Co/Cu/Fe junctions has been measured and analyzed. The effects of applied magnetic field angle (referring to the normal of the junction plane) and injecting spin-polarized current on the output signals have been studied, and the measured results were discussed.

  19. Effect of Mo insertion layers on the magnetoresistance and perpendicular magnetic anisotropy in Ta/CoFeB/MgO junctions

    Science.gov (United States)

    Almasi, H.; Xu, M.; Xu, Y.; Newhouse-Illige, T.; Wang, W. G.

    2016-07-01

    The effect of a thin Mo dusting layer inserted at the interface of Ta/CoFeB of perpendicular magnetic tunneling junction with MgO barriers was investigated. Unlike thick Mo layers that exhibited a strong (110) crystalline texture, the inserted Mo layer between Ta/CoFeB had little negative influence on the crystallization of CoFe (001), therefore combining the advantages of Mo as a good thermal barrier and Ta as a good boron sink. For optimized Mo dusting thickness, a large tunneling magnetoresistance of 208% was achieved in perpendicular magnetic tunneling junctions with superior thermal stability at 500 °C.

  20. Observation of the AC Josephson effect up to THZ frequencies in YBCO/PBCO/YBCO ramp-type Josephson junctions

    NARCIS (Netherlands)

    Terpstra, D.; Rijnders, A.J.H.M.; Roesthuis, F.J.G.; Blank, D.H.A.; Gerritsma, G.J.; Rogalla, H.

    1993-01-01

    We present the response to 100 GHz irradiation of high-Tc Josephson junction devices for mixer/detector applications in the (sub-) mm wave range. These devices consist of a YBCO/PBCO/YBCO ramp-type junction combined with a planar logarithmic periodic antenna. The critical current and the first two S

  1. Contribution to the theoretical and experimental study of the electron-volt effect in N-P junctions; Contribution a l'etude theorique et experimentale de l'effet electronvoltaique dans les jonctions N-P

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen Van, Dong [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1959-07-15

    The proposed aim of this work is to study the behaviour of a semi-conducting junction under the action of {beta} radiation. These studies were directed on the one hand to direct conversion of the energy radiated by a radioactive source to electric energy usable by means of N-P junctions, and on the other hand to the kinetics of defects produced in the semi-conductor crystals by high energy {beta} rays. In the first part of this work, an attempt has been made to complete the earlier theories of the electron-volt effect in junctions by analysing the effect mathematically. This has led to a single equation containing the electrical and geometric parameters of the semi-conductor and of the junction, and the properties of the incident radiation. Apart from this, the diffusion current of the charge carriers created by the bombardment has been studied in more detail, taking into account all the factors which play a part in the expression of the efficiency of charge collection of a junction. In the second part, where experiments on the irradiation of N-P junctions have been carried out with a {sup 90}Sr-{sup 90}Y source, mention is made of the particular advantages of a gallium arsenide junction capable of operating at relatively high temperatures (in the region of 100 deg. C). The third part presents the study of defects created in a semi-conductor crystal by high-energy {beta} rays, according to the method of electron-volt effect. It is shown here that from a study of the degradation of the short-circuit current of the junction it may be possible to determine the recombination level and the probabilities of electron and hole capture, as from a study of the lifetime decay of minority carriers in a crystal of known type. Experiments on the bombardment of Ge junctions by 2 MeV electrons were performed with a Van de Graaff. Very clear anomalies of the electron-volt effect at 100 deg. K were observed. An attempt was made at interpretation of these anomalies in the junction

  2. Effective rumen degradation of dry matter, crude protein and neutral detergent fibre in forage determined by near infrared reflectance spectroscopy

    DEFF Research Database (Denmark)

    Ohlsson, Christer; Houmøller, Lars P.; Weisbjerg, Martin R.

    2007-01-01

    The objective of the present study was to examine if near infrared reflectance spectroscopy (NIRS) could be used to predict degradation parameters and effective degradation from scans of original forage samples. Degradability of dry matter (DM), crude protein (CP) and neutral detergent fibre (NDF...... calculated. Near infrared reflectance spectroscopy was examined for its ability to predict degradation parameters and to make a direct prediction of effective degradation from scans of the original samples of perennial ryegrass and orchardgrass. Prediction of effective degradation of the different feed...

  3. Can we effectively degrade microcystins? - Implications on human health

    DEFF Research Database (Denmark)

    de la Cruz, Armah A; Antoniou, Maria; Hiskia, Anastasia

    2011-01-01

    in cells resulting in necrosis or apoptosis. Their cyclic structure and novel amino acids enhance their stability and persistence in the environment. Humans are primarily exposed to microcystins via drinking water consumption and accidental ingestion of recreational water. Recreational exposure by skin...... contact or inhalation to microcystins is now recognized to cause a wide range of acute illnesses which can be life-threatening. Microcystins are primarily degraded by microorganisms in the environment, while sunlight can cause the isomerization of the double bonds and hydroxylation in the presence...

  4. A nonlinear mixed-effects model for degradation data obtained from in-service inspections

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, X.-X. [Department of Civil and Environmental Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1 (Canada); Pandey, M.D. [Department of Civil and Environmental Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1 (Canada)], E-mail: mdpandey@uwaterloo.ca

    2009-02-15

    Monitoring of degradation and predicting its progression using periodic inspection data are important to ensure safety and reliability of engineering systems. Traditional regression models are inadequate in modeling the periodic inspection data, as it ignores units specific random effects and potential correlation among repeated measurements. This paper presents an advanced nonlinear mixed-effects (NLME) model, generally adopted in bio-statistical literature, for modeling and predicting degradation in nuclear piping system. The proposed model offers considerable improvement by reducing the variance associated with degradation of a specific unit, which leads to more realistic estimates of risk.

  5. Effect of actinobacteria agent inoculation methods on cellulose degradation during composting based on redundancy analysis.

    Science.gov (United States)

    Zhao, Yue; Lu, Qian; Wei, Yuquan; Cui, Hongyang; Zhang, Xu; Wang, Xueqin; Shan, Si; Wei, Zimin

    2016-11-01

    In this study, actinobacteria agent including Streptomyces sp. and Micromonospora sp. were inoculated during chicken manure composting by different inoculation methods. The effect of different treatments on cellulose degradation and the relationship between inoculants and indigenous actinobacteria were investigated during composting. The results showed that inoculation in different stages of composting all improved the actinobacteria community diversity particularly in the cooling stage of composting (M3). Moreover, inoculation could distinctly accelerate the degradation of organic matters (OM) especially celluloses. Redundancy analysis indicated that the correlation between indigenous actinobacteria and degradation of OM and cellulose were regulated by inoculants and there were significant differences between different inoculation methods. Furthermore, synergy between indigenous actinobacteria and inoculants for degradation of OM and cellulose in M3 was better than other treatments. Conclusively, we suggested an inoculation method to regulate the indigenous actinobacteria based on the relationship between inoculants and indigenous actinobacteria and degradation content.

  6. Chaos induced by coupling between Josephson junctions

    Science.gov (United States)

    Shukrinov, Yu. M.; Azemtsa-Donfack, H.; Botha, A. E.

    2015-02-01

    It is found that, in a stack of intrinsic Josephson junctions in layered high temperature superconductors under external electromagnetic radiation, the chaotic features are triggered by interjunction coupling, i.e., the coupling between different junctions in the stack. While the radiation is well known to produce chaotic effects in the single junction, the effect of interjunction coupling is fundamentally different and it can lead to the onset of chaos via a different route to that of the single junction. A precise numerical study of the phase dynamics of intrinsic Josephson junctions, as described by the CCJJ+DC model, is performed. We demonstrate the charging of superconducting layers, in a bias current interval corresponding to a Shapiro step subharmonic, due to the creation of a longitudinal plasma wave along the stack of junctions. With increase in radiation amplitude chaotic behavior sets in. The chaotic features of the coupled Josephson junctions are analyzed by calculations of the Lyapunov exponents. We compare results for a stack of junctions to the case of a single junction and prove that the observed chaos is induced by the coupling between the junctions. The use of Shapiro step subharmonics may allow longitudinal plasma waves to be excited at low radiation power.

  7. Effect of Helicobacter pylori infection on outcomes in resected gastric and gastroesophageal junction cancer.

    Science.gov (United States)

    Kolb, Jennifer M; Ozbek, Umut; Harpaz, Noam; Holcombe, Randall F; Ang, Celina

    2017-06-01

    Helicobacter pylori (H pylori) infection is a known risk factor for gastric cancer (GC) and has been linked with gastroesophageal junction (GEJ) cancer. Studies examining the relationship between H. pylori infection, GC characteristics and prognosis are limited and have yielded conflicting results. We report on the clinicopathologic characteristics and oncologic outcomes of gastric and GEJ cancer patients with and without a history of H. pylori treated at our institution. We retrospectively reviewed the medical records of patients over the age of 18 years who underwent curative resection for GEJ and GC at Mount Sinai Hospital between 2007 and 2012 who had histopathologic documentation of the presence or absence of H pylori infection. Demographic, clinical, pathologic, treatment characteristics and outcomes including recurrence-free survival (RFS) and overall survival (OS) were compared. Ninety-five patients were identified. The majority of patients were male (61%), white (36%) or Asian (34%), with median age at diagnosis 64. Tumors were stage I (51%), stage II (23%), stage III (25%), and stage IV (1%). H pylori infection status was documented at the time of cancer diagnosis in 89 (94%) patients, and following cancer diagnosis and treatment in 6 (6%) patients. Younger age at diagnosis, Asian race and Lauren histologic classification were associated with H Pylori infection. H pylori positive patients exhibited higher 5-year OS and 5-year RFS compared to H pylori negative patients, though the difference was not statistically significant in either univariate or multivariate analyses. In this retrospective series of predominantly early stage GC and GEJ cancers, H. pylori positive patients were significantly younger at cancer diagnosis and were more frequently Asian compared to H. pylori negative patients. Other demographic and histologic classifications except for Lauren histologic classification were similar between the two groups. H pylori positive patients appeared

  8. Josephson junctions with ferromagnetic interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Wild, Georg Hermann

    2012-03-04

    We report on the fabrication of superconductor/insulator/ferromagnetic metal/superconductor (Nb/AlO{sub x}/Pd{sub 0.82}Ni{sub 0.18}/Nb) Josephson junctions (SIFS JJs) with high critical current densities, large normal resistance times area products, and high quality factors. For these junctions, a transition from 0- to {pi}-coupling is observed for a thickness d{sub F}=6 nm of the ferromagnetic Pd{sub 0.82}Ni{sub 0.18} interlayer. The magnetic field dependence of the critical current of the junctions demonstrates good spatial homogeneity of the tunneling barrier and ferromagnetic interlayer. Magnetic characterization shows that the Pd{sub 0.82}Ni{sub 0.18} has an out-of-plane anisotropy and large saturation magnetization indicating negligible dead layers at the interfaces. A careful analysis of Fiske modes up to about 400 GHz provides valuable information on the junction quality factor and the relevant damping mechanisms. Whereas losses due to quasiparticle tunneling dominate at low frequencies, at high frequencies the damping is explained by the finite surface resistance of the junction electrodes. High quality factors of up to 30 around 200 GHz have been achieved. They allow to study the junction dynamics, in particular the switching probability from the zero-voltage into the voltage state with and without microwave irradiation. The experiments with microwave irradiation are well explained within semi-classical models and numerical simulations. In contrast, at mK temperature the switching dynamics without applied microwaves clearly shows secondary quantum effects. Here, we could observe for the first time macroscopic quantum tunneling in Josephson junctions with a ferromagnetic interlayer. This observation excludes fluctuations of the critical current as a consequence of an unstable magnetic domain structure of the ferromagnetic interlayer and affirms the suitability of SIFS Josephson junctions for quantum information processing.

  9. Effects of low-intensity pulsed ultrasound on new trabecular bone during bone-tendon junction healing in a rabbit model: a synchrotron radiation micro-CT study.

    Directory of Open Access Journals (Sweden)

    Hongbin Lu

    Full Text Available This study was designed to evaluate the effects of low-intensity pulsed ultrasound on bone regeneration during the bone-tendon junction healing process and to explore the application of synchrotron radiation micro computed tomography in three dimensional visualization of the bone-tendon junction to evaluate the microarchitecture of new trabecular bone. Twenty four mature New Zealand rabbits underwent partial patellectomy to establish a bone-tendon junction injury model at the patella-patellar tendon complex. Animals were then divided into low-intensity pulsed ultrasound treatment (20 min/day, 7 times/week and placebo control groups, and were euthanized at week 8 and 16 postoperatively (n = 6 for each group and time point. The patella-patellar tendon specimens were harvested for radiographic, histological and synchrotron radiation micro computed tomography detection. The area of the newly formed bone in the ultrasound group was significantly greater than that of control group at postoperative week 8 and 16. The high resolution three dimensional visualization images of the bone-tendon junction were acquired by synchrotron radiation micro computed tomography. Low-intensity pulsed ultrasound treatment promoted dense and irregular woven bone formation at week 8 with greater bone volume fraction, number and thickness of new trabecular bone but with lower separation. At week 16, ultrasound group specimens contained mature lamellar bone with higher bone volume fraction and thicker trabeculae than that of control group; however, there was no significant difference in separation and number of the new trabecular bone. This study confirms that low-intensity pulsed ultrasound treatment is able to promote bone formation and remodeling of new trabecular bone during the bone-tendon junction healing process in a rabbit model, and the synchrotron radiation micro computed tomography could be applied for three dimensional visualization to quantitatively evaluate

  10. Confocal Annular Josephson Tunnel Junctions

    Science.gov (United States)

    Monaco, Roberto

    2016-09-01

    The physics of Josephson tunnel junctions drastically depends on their geometrical configurations and here we show that also tiny geometrical details play a determinant role. More specifically, we develop the theory of short and long annular Josephson tunnel junctions delimited by two confocal ellipses. The behavior of a circular annular Josephson tunnel junction is then seen to be simply a special case of the above result. For junctions having a normalized perimeter less than one, the threshold curves in the presence of an in-plane magnetic field of arbitrary orientations are derived and computed even in the case with trapped Josephson vortices. For longer junctions, a numerical analysis is carried out after the derivation of the appropriate motion equation for the Josephson phase. We found that the system is modeled by a modified and perturbed sine-Gordon equation with a space-dependent effective Josephson penetration length inversely proportional to the local junction width. Both the fluxon statics and dynamics are deeply affected by the non-uniform annulus width. Static zero-field multiple-fluxon solutions exist even in the presence of a large bias current. The tangential velocity of a traveling fluxon is not determined by the balance between the driving and drag forces due to the dissipative losses. Furthermore, the fluxon motion is characterized by a strong radial inward acceleration which causes electromagnetic radiation concentrated at the ellipse equatorial points.

  11. Effect of Nitrogen Fertilizer on Photosynthetic Rate of Leymus chinensis in Grassland of Different Degrading Degrees

    Institute of Scientific and Technical Information of China (English)

    Mingming WANG; Yajing BAO; Zhenghai LI; Shaohuan YANG; Jingping JIAO; Yanyu GUO

    2012-01-01

    [Objective] This study aimed to investigate the effect of nitrogen fertilizer on photosynthetic rate of Leymus chinensis in the grasslands of different degrading degrees. [Method] With the L. chinensis in Inner Mongolia Baiyinxile Ranch as the research object, different rations of nitrogen fertilizer were applied to the grassland (0, 30, 50, 80 g/m^2). The effect of different gradients of nitrogen fertilizer on photo- synthetic rate of Leymus chinensis, and the effect on grasslands of different degrading degrees were analyzed. [Result] The photosynthetic rate of L. chinensis in- creased with the increase of nitrogen gradients; in the grassland communities with different degrading degrees, the responses of the photosynthetic rate of L. chinensis to nitrogen fertilizer were different, and the response in the grassland with severe degradation was the best. [Conclusion] Nitrogen fertilizer played an important role in enhancing the restoration degree of grassland.

  12. Evaluation of non-thermal effects of electricity on ascorbic acid and carotenoid degradation in acerola pulp during ohmic heating.

    Science.gov (United States)

    Jaeschke, Débora Pez; Marczak, Ligia Damasceno Ferreira; Mercali, Giovana Domeneghini

    2016-05-15

    The effect of electric field on ascorbic acid and carotenoid degradation in acerola pulp during ohmic heating was evaluated. Ascorbic acid kinetic degradation was evaluated at 80, 85, 90 and 95°C during 60 min of thermal treatment by ohmic and conventional heating. Carotenoid degradation was evaluated at 90 and 95°C after 50 min of treatment. The different temperatures evaluated showed the same effect on degradation rates. To investigate the influence of oxygen concentration on the degradation process, ohmic heating was also carried out under rich and poor oxygen modified atmospheres at 90°C. Ascorbic acid and carotenoid degradation was higher under a rich oxygen atmosphere, indicating that oxygen is the limiting reagent of the degradation reaction. Ascorbic acid and carotenoid degradation was similar for both heating technologies, demonstrating that the presence of the oscillating electric field did not influence the mechanisms and rates of reactions associated with the degradation process.

  13. Enzymatic Degradation of Dynasan 114 SLN - Effect of Surfactants and Particle Size

    Energy Technology Data Exchange (ETDEWEB)

    Olbrich, Carsten; Kayser, Oliver; Mueller, Rainer Helmut [Free University of Berlin, Department of Pharmaceutics, Biopharmaceutics and Biotechnology (Germany)], E-mail: mpharma@zedat.fu-berlin.de

    2002-04-15

    The degradation velocity of solid lipid nanoparticles (SLN) is - apart from drug diffusion - an important parameter determining drug release in vivo. To assess the effect of stabilizers systematically, Dynasan 114 SLN were produced with ionic surfactants (e.g. cholic acid sodium salt (NaCh), sodium dodecyl sulfate (SDS), cetylpyridiniumchloride (CPC)) and steric stabilizers (Tween 80, Poloxamer 188, 407 and Poloxamine 908) including a mixture of cholic acid sodium salt and Poloxamer 407. In addition, the size effects were investigated. The degradation velocity was measured using an in vitro lipase assay. SLN stabilized with lecithin and NaCh showed the fastest, Tween 80 the intermediate and the high molecular weight Poloxamer 407 the slowest degradation. Size effects were less pronounced for fast degrading particles (e.g. those stabilized with NaCh). No difference in the size range of 180-300-nm was observed, but a distinctly slower degradation of 800-nm SLN could be detected. For slowly degrading particles, more pronounced size effects were found. Size effects are more difficult to assess when the PCS diameters are similar, but small fractions of micrometer particles are present, besides the nanometer bulk population. The measured FFA formation is then a superposition of particles degrading at different speeds due to differences in the shape of the size distribution. Admixing of Poloxamer to NaCh had no delaying effect on the degradation of the Dynasan 114 SLN, indicating an influence of the nature of the lipid matrix that is affecting the stabilizers affinity to and anchoring onto the SLN surface.

  14. Enzymatic Degradation of Dynasan 114 SLN - Effect of Surfactants and Particle Size

    Science.gov (United States)

    Olbrich, Carsten; Kayser, Oliver; Müller, Rainer Helmut

    2002-04-01

    The degradation velocity of solid lipid nanoparticles (SLN) is - apart from drug diffusion - an important parameter determining drug release in vivo. To assess the effect of stabilizers systematically, Dynasan 114 SLN were produced with ionic surfactants (e.g. cholic acid sodium salt (NaCh), sodium dodecyl sulfate (SDS), cetylpyridiniumchloride (CPC)) and steric stabilizers (Tween 80, Poloxamer 188, 407 and Poloxamine 908) including a mixture of cholic acid sodium salt and Poloxamer 407. In addition, the size effects were investigated. The degradation velocity was measured using an in vitro lipase assay. SLN stabilized with lecithin and NaCh showed the fastest, Tween 80 the intermediate and the high molecular weight Poloxamer 407 the slowest degradation. Size effects were less pronounced for fast degrading particles (e.g. those stabilized with NaCh). No difference in the size range of 180-300-nm was observed, but a distinctly slower degradation of 800-nm SLN could be detected. For slowly degrading particles, more pronounced size effects were found. Size effects are more difficult to assess when the PCS diameters are similar, but small fractions of micrometer particles are present, besides the nanometer bulk population. The measured FFA formation is then a superposition of particles degrading at different speeds due to differences in the shape of the size distribution. Admixing of Poloxamer to NaCh had no delaying effect on the degradation of the Dynasan 114 SLN, indicating an influence of the nature of the lipid matrix that is affecting the stabilizers affinity to and anchoring onto the SLN surface.

  15. Hydrolytic degradation of composite resins: effects on the microhardness

    Directory of Open Access Journals (Sweden)

    Martos Josué

    2003-01-01

    Full Text Available The purpose of this investigation was to evaluate the microhardness of two laboratory-processed composites (Artglass; belleGlass and two direct placement composites (Filtek Z250; Alert, after aging in distilled water. Twenty cylinders (8 mm diameter; 2 mm height per tested material were prepared and stored in 10 ml of distilled water. Five Knoop hardness measurements were made on the surface of the specimens with a Miniload Hardness Tester under a load of 50 g for 30 s at 10 min, 24 h, 30 and 90 days. Statistical analysis was perfomed using two-way ANOVA, followed by a SNK multiple comparison test (p < 0.05. The analysis showed statistically significant difference among hardness means recorded at the different aging time and the tested materials. It may be concluded that all materials presented hydrolytic degradation due to aging in aqueous environment.

  16. Effect of Biostimulation and Bioaugmentation on Degradation of Polyurethane Buried in Soil▿

    Science.gov (United States)

    Cosgrove, L.; McGeechan, P. L.; Handley, P. S.; Robson, G. D.

    2010-01-01

    This work investigated biostimulation and bioaugmentation as strategies for removing polyurethane (PU) waste in soil. Soil microcosms were biostimulated with the PU dispersion agent “Impranil” and/or yeast extract or were bioaugmented with PU-degrading fungi, and the degradation of subsequently buried PU was determined. Fungal communities in the soil and colonizing buried PU were enumerated on solid media and were analyzed using denaturing gradient gel electrophoresis (DGGE). Biostimulation with yeast extract alone or in conjunction with Impranil increased PU degradation 62% compared to the degradation in untreated control soil and was associated with a 45% increase in putative PU degraders colonizing PU. Specific fungi were enriched in soil following biostimulation; however, few of these fungi colonized the surface of buried PU. Fungi used for soil bioaugmentation were cultivated on the surface of sterile wheat to form a mycelium-rich inoculum. Wheat, when added alone to soil, increased PU degradation by 28%, suggesting that wheat biomass had a biostimulating effect. Addition of wheat colonized with Nectria haematococca, Penicillium viridicatum, Penicillium ochrochloron, or an unidentified Mucormycotina sp. increased PU degradation a further 30 to 70%, suggesting that biostimulation and bioaugmentation were operating in concert to enhance PU degradation. Interestingly, few of the inoculated fungi could be detected by DGGE in the soil or on the surface of the PU 4 weeks after inoculation. Bioaugmentation did, however, increase the numbers of indigenous PU-degrading fungi and caused an inoculum-dependent change in the composition of the native fungal populations, which may explain the increased degradation observed. These results demonstrate that both biostimulation and bioaugmentation may be viable tools for the remediation of environments contaminated with polyurethane waste. PMID:19948849

  17. Effect of biostimulation and bioaugmentation on degradation of polyurethane buried in soil.

    Science.gov (United States)

    Cosgrove, L; McGeechan, P L; Handley, P S; Robson, G D

    2010-02-01

    This work investigated biostimulation and bioaugmentation as strategies for removing polyurethane (PU) waste in soil. Soil microcosms were biostimulated with the PU dispersion agent "Impranil" and/or yeast extract or were bioaugmented with PU-degrading fungi, and the degradation of subsequently buried PU was determined. Fungal communities in the soil and colonizing buried PU were enumerated on solid media and were analyzed using denaturing gradient gel electrophoresis (DGGE). Biostimulation with yeast extract alone or in conjunction with Impranil increased PU degradation 62% compared to the degradation in untreated control soil and was associated with a 45% increase in putative PU degraders colonizing PU. Specific fungi were enriched in soil following biostimulation; however, few of these fungi colonized the surface of buried PU. Fungi used for soil bioaugmentation were cultivated on the surface of sterile wheat to form a mycelium-rich inoculum. Wheat, when added alone to soil, increased PU degradation by 28%, suggesting that wheat biomass had a biostimulating effect. Addition of wheat colonized with Nectria haematococca, Penicillium viridicatum, Penicillium ochrochloron, or an unidentified Mucormycotina sp. increased PU degradation a further 30 to 70%, suggesting that biostimulation and bioaugmentation were operating in concert to enhance PU degradation. Interestingly, few of the inoculated fungi could be detected by DGGE in the soil or on the surface of the PU 4 weeks after inoculation. Bioaugmentation did, however, increase the numbers of indigenous PU-degrading fungi and caused an inoculum-dependent change in the composition of the native fungal populations, which may explain the increased degradation observed. These results demonstrate that both biostimulation and bioaugmentation may be viable tools for the remediation of environments contaminated with polyurethane waste.

  18. Optimizing performance of silicon-based p-n junction photodetectors by the piezo-phototronic effect.

    Science.gov (United States)

    Wang, Zhaona; Yu, Ruomeng; Wen, Xiaonan; Liu, Ying; Pan, Caofeng; Wu, Wenzhuo; Wang, Zhong Lin

    2014-12-23

    Silicon-based p-n junction photodetectors (PDs) play an essential role in optoelectronic applications for photosensing due to their outstanding compatibility with well-developed integrated circuit technology. The piezo-phototronic effect, a three-way coupling effect among semiconductor properties, piezoelectric polarizations, and photon excitation, has been demonstrated as an effective approach to tune/modulate the generation, separation, and recombination of photogenerated electron-hole pairs during optoelectronic processes in piezoelectric-semiconductor materials. Here, we utilize the strain-induced piezo-polarization charges in a piezoelectric n-ZnO layer to modulate the optoelectronic process initiated in a p-Si layer and thus optimize the performances of p-Si/ZnO NWs hybridized photodetectors for visible sensing via tuning the transport property of charge carriers across the Si/ZnO heterojunction interface. The maximum photoresponsivity R of 7.1 A/W and fastest rising time of 101 ms were obtained from these PDs when applying an external compressive strain of -0.10‰ on the ZnO NWs, corresponding to relative enhancement of 177% in R and shortening to 87% in response time, respectively. These results indicate a promising method to enhance/optimize the performances of non-piezoelectric semiconductor material (e.g., Si) based optoelectronic devices by the piezo-phototronic effect.

  19. Imaging analysis of the gliadin direct effect on tight junctions in an in vitro three-dimensional Lovo cell line culture system.

    Science.gov (United States)

    Elli, Luca; Roncoroni, Leda; Doneda, Luisa; Ciulla, Michele M; Colombo, Roberto; Braidotti, Paola; Bonura, Antonella; Bardella, Maria Teresa

    2011-02-01

    Tight junctions play a pivotal role in maintaining the integrity of the intestinal barrier. Their alteration is involved in the pathogenesis of celiac disease. Our aim was to investigate the gliadin effect on the tight junction proteins in an in vitro three-dimensional cell culture model through imaging analyses. Lovo multicellular spheroids were treated with enzymatically digested (PT) gliadin 500 μg/mL and its effect on actin, occludin and zonula occludens-1, was evaluated by means of confocal laser microscopy, transmission electron microscopy and image capture analysis. Compared to untreated spheroids, PT-gliadin-treated ones showed enlargement of the paracellular spaces (9.0±6.9 vs. 6.2±1.7 nm, p<0.05) at transmission electron microscopy and tight junction protein alterations at confocal microscopy and image analyses. In untreated cell cultures thickness of the fluorescence contour of actin, zonula occludens-1 and occludin appeared significantly larger and more intense than in the treated ones. In occludin planimetric analysis the lengths of the integral uninterrupted cellular contour appeared longer in untreated than in PT-gliadin treated spheroids (71.8±42.8 vs. 23.4±25.9 μm, p<0.01). Our data demonstrated that tight junction proteins are directly damaged by gliadin as shown by means of quantitative imaging analysis.

  20. Effect of copper ions on the degradation of thiram in aqueous solution: identification of degradation products by HPLC-MS/MS.

    Science.gov (United States)

    Filipe, Olga M S; Santos, Sónia A O; Domingues, M Rosário M; Vidal, Maria M; Silvestre, Armando J D; Santos, Eduarda B H

    2014-08-30

    The aim of this work was to examine the effect of Cu(II) on the degradation of thiram (Thi) in aqueous solutions, since the literature focused on this effect is scarce and copper based fungicides can be applied together with thiram or during the same season to agricultural crops. The effect of Cu(II) on the degradation of thiram was followed by both UV-vis and HPLC-MS/MS. When thiram is dissolved in pure water its degradation occurs very slowly, being negligible during the first 7 days. However, the presence of Cu(II) has a strong influence on the thiram degradation in aqueous solutions along time. In the presence of an excess of Cu(II), a [CuThi](2+) complex is initially formed which degrades into a complex formed between the dimethyldithiocarbamate anion (DMDTC) and Cu(II) ion, [Cu(DMDTC)](+). This complex further degrades leading to other copper complexes which were identified for the first time, by MS(n). The results obtained in the present work also demonstrated that a redox reaction involving DMDTC anions and Cu(II) ions gives rise to the formation of a Thi-Cu(I) complex. Finally, some of the complexes resulting from the degradation of [CuThi](2+) are quite persistent in solution for long periods of time (>1 month).

  1. Effects of EMF Emissions from Cables and Junction Boxes on Marine Species

    Energy Technology Data Exchange (ETDEWEB)

    Dhanak, Manhar [Florida Atlantic Univ., Boca Raton, FL (United States); Spieler, Richard [Nova Southeastern Univ., Fort Lauderdale, FL (United States); Kilfoyle, Kirk [Nova Southeastern Univ., Fort Lauderdale, FL (United States); Jermain, Robert F. [Nova Southeastern Univ., Fort Lauderdale, FL (United States); Frankenfield, John [Florida Atlantic Univ., Boca Raton, FL (United States); Ravenna, Shirley [Florida Atlantic Univ., Boca Raton, FL (United States); Dibiasio, Christopher [Florida Atlantic Univ., Boca Raton, FL (United States); Coulson, Robert [Florida Atlantic Univ., Boca Raton, FL (United States); Henderson, Ed [Florida Atlantic Univ., Boca Raton, FL (United States); Venezia, William [Naval Surface Warfare Center (NSWC), Carderock Division (United States)

    2016-09-29

    Studies have shown that diverse aquatic species are electrosensitive. Many fishes, and marine mammals, can either detect, navigate by, or are affected by electromagnetic fields (EMF) with various sensitivities, and their behavior may be impacted by unnatural EMF emissions in the water column. Sharks, rays and skates are known to have the highest sensitivity to electric fields. Electric field emissions in the range 0.5–100 micro volt/m appear to attract them, and emissions over 100 micro volt/m to repulse them. A marine hydrokinetic MHK device will have multiple components and associated multiple submarine cables on the seafloor and running through the water column and would potentially increase the level of EMF emissions to which the marine species at the site may be exposed to. There are therefore concerns amongst stakeholders that EMF emissions associated with MHK devices and their components may act as barriers to species migration, cause disorientation, change community compositions and ecosystems, and that they may attract sharks, leading to a local increase in the risk of shark attacks. However, field data to validate and model potential relationships between observed responses and the EMF emissions in situ are sparse. A program of experimental field surveys were conducted off the coast of South Florida, USA to characterize the electromagnetic field (EMF) emissions in the water column from a submarine cable, and to monitor for responses of local aquatic species. The field surveys were conducted at the South Florida Ocean Measurement Facility (SFOMF) off Fort Lauderdale, which is a cabled offshore in-water navy range. It consists of multiple active submarine power cables and a number of junction boxes, with the capability to transmit AC/DC power at a range of strength and frequencies. The site includes significant marine life activities and community structure, including highly mobile species, such as sharks, stingrays, mammals and turtles. SFOMF therefore

  2. Degraded stimulus visibility and the effects of perceptual load on distractor interference

    Directory of Open Access Journals (Sweden)

    Yaffa eYeshurun

    2013-05-01

    Full Text Available In this study we examined whether effects of perceptual load on the attentional selectivity are modulated by degradation of the visual input. According to the perceptual load theory, increasing task difficulty via degradation of stimulus visibility should not alter the typical effect of perceptual load. In previous studies only the target was degraded, resulting in increased distractor saliency. Here we combined manipulation of perceptual load with a more systematic degradation of visual information. Experiment 1 included five conditions. Three conditions involved low perceptual load + contrast reduction of: a only the target; b only the distractor; c both target and distractor. The other two conditions included non-degraded stimuli with low or high perceptual load. In Experiment 2 visibility degradation was established via manipulation of exposure duration. It included two exposure durations – 100 ms and 150 ms – for each load level (low vs. high. The results of both experiments demonstrated reliable distractor interference of a similar magnitude with both degraded and non-degraded stimuli. This finding suggests that task difficulty, when manipulated via degradation of stimulus visibility, does not play a critical role in determining the efficiency of the attentional selectivity. However, contrary to the predictions of the perceptual load theory, in both experiments distractor interference emerged under the high load condition. In Experiment 2 the high-load interference was of the same magnitude as that of the low load condition. This high-load interference is not due to the presence of a mask (Experiment 3 or a mixed design (Experiment 4. These findings suggest that perceptual load may also play a lesser role in attentional selectivity than that assigned to it by the perceptual load theory.

  3. Transfer map approach to an optical effects of energy degraders on the perfomance of fragment separators.

    Energy Technology Data Exchange (ETDEWEB)

    Erdelyi, B.; Bandura, L.; Nolen, J.; Physics

    2009-01-01

    A second order analytical and an arbitrary order numerical procedure is developed for the computation of transfer maps of energy degraders. The incorporation of the wedges into the optics of fragment separators for next-generation exotic beam facilities, their optical effects, and the optimization of their performance is studied in detail. It is shown how to place and shape the degraders in the system such that aberrations are minimized and resolving powers are maximized.

  4. Degradation of atenolol by UV/peroxymonosulfate: kinetics, effect of operational parameters and mechanism.

    Science.gov (United States)

    Liu, Xiaowei; Zhang, Tuqiao; Zhou, Yongchao; Fang, Lei; Shao, Yu

    2013-11-01

    Photoactivation of peroxymonosulfate (PMS) with UV (254nm) irradiation was used to generate the SO4(-)-based advanced oxidation process, which was adopted to degrade atenolol (ATL) in water. The second-order reaction rate constants of ATL with HO and SO4(-) were determined, and the effects of operational parameters (dose of PMS, solution pH, HCO3(-), humic acids (HA), and N2 bubbling) were evaluated as well. Finally the main transformation intermediates were identified and possible degradation pathways were proposed. The results showed that there was a linear positive correlation between the degradation rate of ATL and specific dose of PMS (1-16M PMS/M ATL). Increasing solution pH from 3 to 9 promoted elimination of ATL due to the pH-dependent effect of PMS photodecomposition, while further pH increase from 9 to 11 caused slowing down of degradation because of apparent conversion of HO to SO4(-). 1-8mM HCO3(-) exerted no more than 5.3% inhibition effect on ATL destruction, suggesting HCO3(-) was a weak inhibitor. Absorption (or complexation) and photosensitized oxidation induced by HA improved ATL degradation during the first minute of degradation process, whereas photon competition and radical scavenging effects became the leading role afterward. Bubbling with nitrogen enhanced the degradation rate due to the stripping of dissolved oxygen. Hydroxylation of aromatic ring, cleavage of ether bond, oxidation of primary and secondary amine moieties, and dimerization were involved in the degradation mechanism of ATL by UV/PMS.

  5. Molecular electronic junction transport

    DEFF Research Database (Denmark)

    Solomon, Gemma C.; Herrmann, Carmen; Ratner, Mark

    2012-01-01

    Whenasinglemolecule,oracollectionofmolecules,isplacedbetween two electrodes and voltage is applied, one has a molecular transport junction. We discuss such junctions, their properties, their description, and some of their applications. The discussion is qualitative rather than quantitative, and f...

  6. Cytokine effects on gap junction communication and connexin expression in human bladder smooth muscle cells and suburothelial myofibroblasts.

    Directory of Open Access Journals (Sweden)

    Marco Heinrich

    Full Text Available BACKGROUND: The last decade identified cytokines as one group of major local cell signaling molecules related to bladder dysfunction like interstitial cystitis (IC and overactive bladder syndrome (OAB. Gap junctional intercellular communication (GJIC is essential for the coordination of normal bladder function and has been found to be altered in bladder dysfunction. Connexin (Cx 43 and Cx45 are the most important gap junction proteins in bladder smooth muscle cells (hBSMC and suburothelial myofibroblasts (hsMF. Modulation of connexin expression by cytokines has been demonstrated in various tissues. Therefore, we investigate the effect of interleukin (IL 4, IL6, IL10, tumor necrosis factor-alpha (TNFα and transforming growth factor-beta1 (TGFβ1 on GJIC, and Cx43 and Cx45 expression in cultured human bladder smooth muscle cells (hBSMC and human suburothelial myofibroblasts (hsMF. METHODOLOGY/PRINCIPAL FINDINGS: HBSMC and hsMF cultures were set up from bladder tissue of patients undergoing cystectomy. In cytokine stimulated cultured hBSMC and hsMF GJIC was analyzed via Fluorescence Recovery after Photo-bleaching (FRAP. Cx43 and Cx45 expression was assessed by quantitative PCR and confocal immunofluorescence. Membrane protein fraction of Cx43 and Cx45 was quantified by Dot Blot. Upregulation of cell-cell-communication was found after IL6 stimulation in both cell types. In hBSMC IL4 and TGFβ1 decreased both, GJIC and Cx43 protein expression, while TNFα did not alter communication in FRAP-experiments but increased Cx43 expression. GJ plaques size correlated with coupling efficacy measured, while Cx45 expression did not correlate with modulation of GJIC. CONCLUSIONS/SIGNIFICANCE: Our finding of specific cytokine effects on GJIC support the notion that cytokines play a pivotal role for pathophysiology of OAB and IC. Interestingly, the effects were independent from the classical definition of pro- and antiinflammatory cytokines. We conclude, that

  7. Accelerated Degradation Process Analysis Based on the Nonlinear Wiener Process with Covariates and Random Effects

    Directory of Open Access Journals (Sweden)

    Li Sun

    2016-01-01

    Full Text Available It is assumed that the drift parameter is dependent on the acceleration variables and the diffusion coefficient remains the same across the whole accelerated degradation test (ADT in most of the literature based on Wiener process. However, the diffusion coefficient variation would also become obvious in some applications with the stress increasing. Aiming at the phenomenon, the paper concludes that both the drift parameter and the diffusion parameter depend on stress variables based on the invariance principle of failure mechanism and Nelson assumption. Accordingly, constant stress accelerated degradation process (CSADP and step stress accelerated degradation process (SSADP with random effects are modeled. The unknown parameters in the established model are estimated based on the property of degradation and degradation increment, separately for CASDT and SSADT, by the maximum likelihood estimation approach with measurement error. In addition, the simulation steps of accelerated degradation data are provided and simulated step stress accelerated degradation data is designed to validate the proposed model compared to other models. Finally, a case study of CSADT is conducted to demonstrate the benefits of our model in the practical engineering.

  8. Effect of copper on the degradation of pesticides cypermethrin and cyhalothrin

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The influence of coexisting copper (Cu) ion on the degradation of pesticides pyrethroid cypermethrin and cyhalothrin in soil and photodegradation in water system were studied. Serial concentrations of the pesticides with the addition of copper ion were spiked in the soil and incubated for a regular period of time, the analysis of the extracts from the soil was carried out using gas chromatography(GC). The photodegradation of pyrethroids in water system was conducted under UV irradiation. The effect of Cu2+ on the pesticides degradation was measured with half life (t0.5) of degradation. It was found that a negative correlation between the degradation of the pyrethroid pesticides in soil and Cu addition was observed. But Cu2+ could accelerate photodegradation of the pyrethroids in water. The t0.5 for cyhalothrin extended from 6.7 to 6.8 d while for cypermethrin extended from 8.1 to 10.9 d with the presence of copper ion in soil. As for photodegradation, t0.5 for cyhalothrin reduced from 173.3 to 115.5 min and for cypermethrin from 115.5 to 99.0 min. The results suggested that copper influenced the degradation of the pesticides in soil by affecting the activity of microorganisms. However,it had catalyst tendency for photodegradation in water system. The difference for the degradation efficiency of pyrethroid isomers in soil was also observed. Copper could obviously accelerate the degradation of some special isomers.

  9. Effective description of tunneling in a time-dependent potential with applications to voltage switching in Josephson junctions

    DEFF Research Database (Denmark)

    Andersen, Christian Kraglund; Mølmer, Klaus

    2013-01-01

    We propose to use a time-dependent imaginary potential to describe quantum mechanical tunneling through time-varying potential barriers. We use Gamow solutions for stationary tunneling problems to justify our choice of potential, and we apply our method to describe tunneling of a mesoscopic quantum...... variable: the phase change across a Josephson junction. The Josephson junction phase variable behaves as the position coordinate of a particle moving in a tilted washboard potential, and our general solution to the motion in such a potential with a time-dependent tilt reproduces a number of features...... associated with voltage switching in Josephson junctions. Apart from applications as artificial atoms in quantum information studies, the Josephson junction may serve as an electric field sensitive detector, and our studies provide a detailed understanding of how the voltage switching dynamics couples...

  10. Effective description of tunneling in a time-dependent potential with applications to voltage switching in Josephson junctions

    DEFF Research Database (Denmark)

    Andersen, Christian Kraglund; Mølmer, Klaus

    2013-01-01

    variable: the phase change across a Josephson junction. The Josephson junction phase variable behaves as the position coordinate of a particle moving in a tilted washboard potential, and our general solution to the motion in such a potential with a time-dependent tilt reproduces a number of features......We propose to use a time-dependent imaginary potential to describe quantum mechanical tunneling through time-varying potential barriers. We use Gamow solutions for stationary tunneling problems to justify our choice of potential, and we apply our method to describe tunneling of a mesoscopic quantum...... associated with voltage switching in Josephson junctions. Apart from applications as artificial atoms in quantum information studies, the Josephson junction may serve as an electric field sensitive detector, and our studies provide a detailed understanding of how the voltage switching dynamics couples...

  11. Catalytic effect of transition metals on microwave-induced degradation of atrazine in mineral micropores.

    Science.gov (United States)

    Hu, Erdan; Cheng, Hefa

    2014-06-15

    With their high catalytic activity for redox reactions, transition metal ions (Cu(2+) and Fe(3+)) were exchanged into the micropores of dealuminated Y zeolites to prepare effective microporous mineral sorbents for sorption and microwave-induced degradation of atrazine. Due to its ability to complex with atrazine, loading of copper greatly increased the sorption of atrazine. Atrazine sorption on iron-exchanged zeolites was also significantly enhanced, which was attributed to the hydrolysis of Fe(3+) polycations in mineral micropores and electrostatic interactions of protonated atrazine molecules with the negatively charged pore wall surface. Copper and iron species in the micropores also significantly accelerated degradation of the sorbed atrazine (and its degradation intermediates) under microwave irradiation. The catalytic effect was attributed to the easy reducibility and high oxidation activity of Cu(2+) and Fe(3+) species stabilized in the micropores of the zeolites. It was postulated that the surface species of transition metals (monomeric Cu(2+), Cu(2+)-O-Cu(2+) complexes, FeO(+), and dinuclear Fe-O-Fe-like species) in the mineral micropores were thermally activated under microwave irradiation, and subsequently formed highly reactive sites catalyzing oxidative degradation of atrazine. The transition metal-exchanged zeolites, particularly the iron-exchanged ones, were relatively stable when leached under acidic conditions, which suggests that they are reusable in sorption and microwave-induced degradation. These findings offer valuable insights on designing of effective mineral sorbents that can selectively uptake atrazine from aqueous solutions and catalyze its degradation under microwave irradiation.

  12. Effect of radiation induced crosslinking and degradation of ETFE films

    Science.gov (United States)

    Zen, H. A.; Ribeiro, G.; Geraldes, A. N.; Souza, C. P.; Parra, D. F.; Lugão, A. B.

    2013-03-01

    In this study the ETFE film with 125 μm of thickness was placed inside a nylon bag and filled with either acetylene, nitrogen or oxygen. Following the procedure, the samples were irradiated at 5, 10 and 20 kGy. The physical and chemical properties of the modified and pristine films were evaluated by rheological and thermal analyses (TG and DSC), X-ray diffraction (XRD) and infrared spectroscopy (IR-ATR). In rheological analysis the storage modulus (G') indicates opposite profiles when the atmospheres (acetylene and oxygen) are evaluated according to the absorbed dose. For the samples submitted to radiation under oxygen atmosphere it is possible to observe the degradation process with the low levels of the storage modulus. The changes in the degree of crystallinity were verified in all modified samples when compared to the pristine polymer and this behavior was confirmed by DSC analysis. A decrease in the intensity of crystalline peak by X-ray diffraction was observed.

  13. Antifirming effects of starch degrading enzymes in bread crumb.

    Science.gov (United States)

    Goesaert, Hans; Leman, Pedro; Bijttebier, Annabel; Delcour, Jan A

    2009-03-25

    Antifirming properties of amylases in bread crumb were evaluated in straight dough breadmaking and related to the amylolytically modified starch structure. Amylase properties and action mechanisms determine starch structure in the breads and, hence, how amylopectin recrystallization, starch network formation, water redistribution, and water mobility occur during breadmaking and storage. A bacterial endo-alpha-amylase mainly hydrolyzed the longer starch polymer chains internally. It thus reduced the number of connections between the crystallites in the starch networks, resulting in a softer bread crumb. However, because the enzyme had only little impact on the outer amylopectin chains, amylopectin recrystallization and the concomitant water immobilization presumably were not hindered. The loss of plasticizing water as a result of recrystallization presumably reduces the flexibility of the gluten network and results in poor crumb resilience. In contrast, in breadmaking, the Bacillus stearothermophilus maltogenic alpha-amylase acted as an exoacting amylase with more pronounced endoaction at higher temperatures. This enzyme caused extensive degradation of the crystallizable amylopectin side chains and thus limited amylopectin recrystallization and network formation during storage. As a result, it prevented the incorporation of water in the amylopectin crystallites. In this way, the different starch and gluten networks kept their flexibility, resulting in a softer crumb with good resilience.

  14. Gap Junctional Intercellular Communication: A Functional Biomarker to Assess Adverse Effects of Toxicants and Toxins, and Health Benefits of Natural Products.

    Science.gov (United States)

    Upham, Brad L; Sovadinová, Iva; Babica, Pavel

    2016-12-25

    This protocol describes a scalpel loading-fluorescent dye transfer (SL-DT) technique that measures intercellular communication through gap junction channels, which is a major intercellular process by which tissue homeostasis is maintained. Interruption of gap junctional intercellular communication (GJIC) by toxicants, toxins, drugs, etc. has been linked to numerous adverse health effects. Many genetic-based human diseases have been linked to mutations in gap junction genes. The SL-DT technique is a simple functional assay for the simultaneous assessment of GJIC in a large population of cells. The assay involves pre-loading cells with a fluorescent dye by briefly perturbing the cell membrane with a scalpel blade through a population of cells. The fluorescent dye is then allowed to traverse through gap junction channels to neighboring cells for a designated time. The assay is then terminated by the addition of formalin to the cells. The spread of the fluorescent dye through a population of cells is assessed with an epifluorescence microscope and the images are analyzed with any number of morphometric software packages that are available, including free software packages found on the public domain. This assay has also been adapted for in vivo studies using tissue slices from various organs from treated animals. Overall, the SL-DT assay can serve a broad range of in vitro pharmacological and toxicological needs, and can be potentially adapted for high throughput set-up systems with automated fluorescence microscopy imaging and analysis to elucidate more samples in a shorter time.

  15. The effect of dephasing on edge state transport through p-n junctions in HgTe/CdTe quantum wells.

    Science.gov (United States)

    Zhang, Ying-Tao; Song, Juntao; Sun, Qing-Feng

    2014-02-26

    Using the Landauer-Büttiker formula, we study the effect of dephasing on the transport properties of the HgTe/CdTe p-n junction. It is found that in the HgTe/CdTe p-n junction the topologically protected gapless helical edge states manifest a quantized 2e²/h plateau robust against dephasing, in sharp contrast to the case for the normal HgTe/CdTe quantum well. This robustness of the transport properties of the edge states against dephasing should be attributed to the special construction of the HgTe/CdTe p-n junction, which limits the gapless helical edge states to a very narrow region and thus weakens the influence of the dephasing on the gapless edge states to a large extent. Our results demonstrate that the p-n junction could be a substitute device for use in experimentally observing the robust edge states and quantized plateau. Finally, we present a feasible scheme based on current experimental methods.

  16. The effect of phytic acid on tight junctions in the human intestinal Caco-2 cell line and its mechanism.

    Science.gov (United States)

    Fu, Qingxue; Wang, Huizhen; Xia, Mengxin; Deng, Bing; Shen, Hongyi; Ji, Guang; Li, Guowen; Xie, Yan

    2015-12-01

    This study investigated the effect of phytic acid (IP6), a potential absorption enhancer of flavonoid components, on tight junction (TJ) integrity in Caco-2 cell monolayers and its possible mechanisms. Transepithelial electrical resistance (TEER) across the monolayers decreased rapidly, and the flux of fluorescein sodium (a paracellular marker) increased after treating with IP6 in a concentration-dependent manner. Confocal microscopy results showed that IP6 produced a concentration-dependent attenuation in the distribution of occludin, ZO-1, and claudin-1. Immunoblot analysis revealed that IP6 could down-regulate the expression level of these TJ proteins, which resulted in the opening of TJ. Additionally, the divalent cations Ca(2+) and Mg(2+) influenced the IP6-induced distribution of occludin, ZO-1, and claudin-1 in different directions, which enhanced barrier function. In conclusion, IP6 can decrease the integrity of Caco-2 cell monolayers by modulating the TJ proteins' localization and down-regulating the expression levels of TJ proteins including claudin-1, occludin, and ZO-1; the reduction effects of divalent cations such as Ca(2+) and Mg(2+) on the regulation of TJ induced by IP6 should be addressed. The present work will offer some useful guidance for the application of IP6 in drug delivery area. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Evaluating the effects of moving to a low maintenance ARD control strategy at the Victoria Junction coal tailings site

    Energy Technology Data Exchange (ETDEWEB)

    Ziemkiewicz, P.F. [Morgantown, WV (United States); Peckham, D.; Kehoe, A. [Enterprise Cape Breton Corp., Sydney, NS (Canada)

    2010-07-01

    The Victoria Junction Coal Preparation site located near Sydney, Nova Scotia has been a major source of acid rock drainage (ARD) to waterways and surrounding wetlands. A polymer cap placed on the pile in 2005 resulted in a rapid improvement in waterway and wetland health. An earlier water treatment system (WTS) remained in operation until an evaluation was conducted to determine if the WTS was needed to maintain water quality in the region. This paper described the acid base loading model used to develop a close-out plan for the WTS. A mass balance model was used to isolate and compare the effects of the WTS and the capping system. The effect of shutting down the WTS was monitored for 8 moths. The model used flow and net acidity rates to calculate loadings. Net acidity represented the mass of pure base expressed as a calcium carbonate equivalent needed to neutralize acid loads. Acidity was calculated base on pH and metal concentrations. Alkalinity was determined by titration. A comparison with analytical studies of collected water samples showed that the mass balance model underestimated the alkalinity produced at the site. Results of the study showed that the site is now a net alkalinity generator. 5 refs., 1 tab., 1 fig.

  18. Effects of organophosphorus pesticides and their ozonation byproducts on gap junctional intercellular communication in rat liver cell line.

    Science.gov (United States)

    Wu, Jiguo; Lin, Li; Luan, Tiangang; Chan Gilbert, Yuk Sing; Lan, Chongyu

    2007-10-01

    The effects of organophosphorus pesticides (OPs), oxons and their ozonation byproducts on gap junctional intercellular communication (GJIC) on cultured BRL cell line were investigated using scrape loading and dye transfer (SL/DT) technique. The neutral red uptake assay was used to identify the non-cytotoxic levels of diazinon, parathion and methyl-parathion applied to GJIC assay. The concentration-dependent inhibition of GJIC was observed over a range of 50-350 mg/l diazinon, parathion and methyl-parathion after 90 min incubation compared with the vehicle control. However, oxons and ozonation byproducts of OPs had no inhibition effect on GJIC at any of the concentrations tested. The inhibition of GJIC by OPs was reversible after removal of the tested pesticides followed by incubation with fresh medium. The present study suggested that the ozonation treatment could be used for the detoxification of drinking water and food crops contaminated with diazinon, parathion and methyl-parathion without formation of GJIC toxicity.

  19. Connexins: a myriad of functions extending beyond assembly of gap junction channels

    Directory of Open Access Journals (Sweden)

    Mroue Rana M

    2009-03-01

    Full Text Available Abstract Connexins constitute a large family of trans-membrane proteins that allow intercellular communication and the transfer of ions and small signaling molecules between cells. Recent studies have revealed complex translational and post-translational mechanisms that regulate connexin synthesis, maturation, membrane transport and degradation that in turn modulate gap junction intercellular communication. With the growing myriad of connexin interacting proteins, including cytoskeletal elements, junctional proteins, and enzymes, gap junctions are now perceived, not only as channels between neighboring cells, but as signaling complexes that regulate cell function and transformation. Connexins have also been shown to form functional hemichannels and have roles altogether independent of channel functions, where they exert their effects on proliferation and other aspects of life and death of the cell through mostly-undefined mechanisms. This review provides an updated overview of current knowledge of connexins and their interacting proteins, and it describes connexin modulation in disease and tumorigenesis.

  20. Connexins: a myriad of functions extending beyond assembly of gap junction channels.

    Science.gov (United States)

    Dbouk, Hashem A; Mroue, Rana M; El-Sabban, Marwan E; Talhouk, Rabih S

    2009-03-12

    Connexins constitute a large family of trans-membrane proteins that allow intercellular communication and the transfer of ions and small signaling molecules between cells. Recent studies have revealed complex translational and post-translational mechanisms that regulate connexin synthesis, maturation, membrane transport and degradation that in turn modulate gap junction intercellular communication. With the growing myriad of connexin interacting proteins, including cytoskeletal elements, junctional proteins, and enzymes, gap junctions are now perceived, not only as channels between neighboring cells, but as signaling complexes that regulate cell function and transformation. Connexins have also been shown to form functional hemichannels and have roles altogether independent of channel functions, where they exert their effects on proliferation and other aspects of life and death of the cell through mostly-undefined mechanisms. This review provides an updated overview of current knowledge of connexins and their interacting proteins, and it describes connexin modulation in disease and tumorigenesis.

  1. Aging Effects and Estimating Degradation Mechanisms of Thermally Upgraded Paper in Mineral Oil

    Science.gov (United States)

    Miyagi, Katsunori; Oe, Etsuo; Yamagata, Naoki

    The life of a transformer is limited to the deterioration of its solid insulation. Winding conductors and other solid insulation materials in oil-immersed transformers have been insulated using cellulose products. For many years, manufacturers have met the needs of special applications by designing transformers using thermally upgraded materials to achieve lighter weight, higher power density and increased life. Recently, the effect of thermally upgraded insulation on diagnostic techniques such as gas-in oil analysis, and their indication of insulation degradation have been reviewed. This paper describes evaluations of the thermal degradation characteristics and decomposition reactions in mineral transformer oil of amine-impregnated thermally upgraded paper insulation. The thermal resistance of the thermally upgraded paper is evaluated by comparison with Kraft paper insulation. Further, aging degradation mechanisms of decompositional degradation of the thermally upgraded paper due to aging in mineral transformer oil are proposed.

  2. Degradation of 4-Chlorophenol Solution by Synergetic Effect of Dual-frequency Ultrasound with Fenton Reagent

    Institute of Scientific and Technical Information of China (English)

    赵德明; 徐新华; 雷乐成; 汪大翚

    2005-01-01

    4-Chlorophenol (4-CP) solution was treated by dual-frequency ultrasound in conjunction with Fenton reagent, and obvious improvement in the 4-CP degradation rate was observed in this advanced oxidation process.Experimental results showed that ultrasonic intensity, saturating gas and pH value affected greatly the 4-CP removal rate. Among four different saturating gases (Ar, 02, air and N2), 4-CP degradation with Ar-saturated solution was the best. However, in the view of practical wastewater treatment, using oxygen as the saturating gas would be more economical. The addition of Fenton reagent followed the first-order kinetics and increased the 4-CP degradation rate.The 4-CP removal rate increased by around 126% within 15 rain treatment. The synergetic effect of dual-frequency ultrasound with Fenton reagent on 4-CP degradation was obviously observed.

  3. Singlet oxygen mediated DNA degradation by copper nanoparticles: potential towards cytotoxic effect on cancer cells

    Science.gov (United States)

    2011-01-01

    The DNA degradation potential and anti-cancer activities of copper nanoparticles of 4-5 nm size are reported. A dose dependent degradation of isolated DNA molecules by copper nanoparticles through generation of singlet oxygen was observed. Singlet oxygen scavengers such as sodium azide and Tris [hydroxyl methyl] amino methane were able to prevent the DNA degradation action of copper nanoparticles confirming the involvement of activated oxygen species in the degradation process. Additionally, it was observed that the copper nanoparticles are able to exert cytotoxic effect towards U937 and Hela cells of human histiocytic lymphoma and human cervical cancer origins, respectively by inducing apoptosis. The growth characteristics of U937 and Hela cells were studied applying various concentrations of the copper nanoparticles. PMID:21439072

  4. Synergistic effects of cellobiose dehydrogenase and manganese-dependent peroxidases during lignin degradation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The synergistic effects of cellobiose dehydrogenase (CDH) and manganese-dependent peroxidases (MnP) on the degradation of kraft pulp cellulolytic enzyme lignin (CEL) were investigated. Addition of CDH significantly increased the amount of water-soluble products reduced from CEL by MnP. CDH facilitated the reduction of the contents of methoxyl, carboxyl, phenolic hydroxyl and total hydroxyl groups of CEL by MnP. 1H-NMR analysis showed that addition of CDH also decreased further the amount of protons of CEL degraded by MnP. The results proved for the first time that CDH could promote degradation of lignin by MnP and suggest that CDH could not only promote degradation of cellulose but also is an important part of the lignin biodegradation system.

  5. Degradation analysis of photovoltaic modules based on operational data: effects of seasonal pattern and sensor drifting

    Science.gov (United States)

    Li, X. Y.

    2016-08-01

    Degradation analysis of photovoltaic (PV) modules based on real operational data is essential to the future development of the PV industry. Weather conditions and system drifting often lead to large uncontrollable fluctuations in operational data, which present great challenges for calculating degradation rates of PV modules. In this paper, we propose a new numerical two-step approach to overcome these difficulties. In particular, we will show that our method is able to eliminate effects of seasonal patterns and systematic sensor drifting in evaluating degradation rates of PV modules. The method is applied to the six-year operational data of a solar PV system installed at CA United States. We demonstrate that our approach can greatly improve the degradation calculations, compared with other widely used methods.

  6. Singlet oxygen mediated DNA degradation by copper nanoparticles: potential towards cytotoxic effect on cancer cells

    Directory of Open Access Journals (Sweden)

    Sengupta Tapas K

    2011-03-01

    Full Text Available Abstract The DNA degradation potential and anti-cancer activities of copper nanoparticles of 4-5 nm size are reported. A dose dependent degradation of isolated DNA molecules by copper nanoparticles through generation of singlet oxygen was observed. Singlet oxygen scavengers such as sodium azide and Tris [hydroxyl methyl] amino methane were able to prevent the DNA degradation action of copper nanoparticles confirming the involvement of activated oxygen species in the degradation process. Additionally, it was observed that the copper nanoparticles are able to exert cytotoxic effect towards U937 and Hela cells of human histiocytic lymphoma and human cervical cancer origins, respectively by inducing apoptosis. The growth characteristics of U937 and Hela cells were studied applying various concentrations of the copper nanoparticles.

  7. Degradation of Lix984N and its effect on interfacial emulsion

    Institute of Scientific and Technical Information of China (English)

    LIU Xiao-rong; QIU Guan-zhou; HU Yue-hua

    2006-01-01

    The organic phase separated from the interfacial crud provided by Dexing copper mine in Jiangxi, China, was analyzed by combined gas chromatography-mass spectroscopy. The results show that many kinds of emphiphiles containing such hydrophilic groups as carbonyl, carboxyl, sulphonyl or acylamine exist in organic phase. Conclusively,Lix984N would degrade gradually during a long-term contact with the acidic aqueous feed and strip reagents. Lix84 and nonylphenol as effective components of Lix984N degraded almost completely after long-term recycling. Lix984N degraded through such reactions as Beckmann rearrange, hydrolysis and sulphofication. The degradation of Lix984N would deteriorate solvent extraction and disengagement performance, and result in a more stable interfacial emulsion.

  8. EFFECT OF ENVIRONMENTAL DEGRADATION ON ANIMAL DIVERSITY IN BALI, INDONESIA

    Directory of Open Access Journals (Sweden)

    I Waya Kasa

    2015-09-01

    Full Text Available Bali is a small beautiful tropical island of Indonesia archipelago lies betweens the continent of Asia and Australia as well as the Indian and Pacific Ocean. As a tropical archipelago, of course, many kinds of biodiversity can be found over there. In the island of Bali in particular, there are typical animal diversity that could not be investigated beyond such island, such as, Bali cattle, Bali dog, Bali white starling and others. As time goes on, the existance of such biodiversity decreases in both quality and quantity. Both global warming/climate change and land use change are the main factors affecting such phenomenon. This study has been conducted by employing field observation as well as literature study. It was found that, the quality of purebred Bali cattle species decreases genetically that could be notified of smaller bodysize for both male and female. Land use change of agriculture activity to the hotels, house of living, roads and other infrastructures are the main factors for Bali cattle existancy. For typical famous bird of white starling, the problem is because of deforestation which cause natural habitat loss, due to land use change for agricultural activity and house building by local people. In case of Bali dog, the mad dog of rabies is just introduce and spreading over Bali island, whichis formerly the island of Bali has been recognised as free zone area of the rabies. As consequency, suffering dogs must be eliminated by a mass killing cause decrease total number of such poor dog. Overall, it could be concluded that environmental degradations of land use change, deforestation and desease are the main causes of biodiversity decreasing number of the Bali cattle, Bali white starling and Bali dog respectively, beside global warming/climate change natural disaster.

  9. Assessing the effect of human-induced land degradation on ecosystem function in the former homelands of South Africa

    Science.gov (United States)

    Wessels, K. J.; Prince, S. D.

    2004-12-01

    The communal homelands in north-eastern South Africa, created during the apartheid-era, are widely regarded as severely degraded as a result of human utilization. The impacts of degradation on net primary production (NPP) were studied using a time-series (1985 to 2003) of Advanced Very High Resolution Radiometer (AVHRR) NDVI and modeled NPP data for degraded rangelands identified by the National Land Cover (using Landsat TM imagery) and non-degraded rangelands within the same land capability units (LCUs). The NPP of degraded areas was significantly lower than in non-degraded parts of most of the LCUs and the difference between degraded and non-degraded areas did not diminish in years with high rainfall, although NPP in degraded areas in wet years exceeded that of non-degraded areas in drier years. Thus degraded areas had the same resilience as non-degraded areas. The Rain-Use Efficiency (RUE) of degraded areas (NPP per unit rainfall) was also consistently lower than non-degraded areas. The persistence of the effect on the NPP indicated that the degradation is stable at the time scale of 18 years. These results indicate that, while there has not been a catastrophic reduction in ecosystem function within the former homelands, degradation results in a stable state with reduced productivity and RUE. The results highlight the importance of multi-temporal analyses of ecosystem function to understanding land degradation and illustrate how long time-series of terrestrial data might be used in a national land degradation monitoring system.

  10. Modelling of Dual-Junction Solar Cells including Tunnel Junction

    Directory of Open Access Journals (Sweden)

    Abdelaziz Amine

    2013-01-01

    Full Text Available Monolithically stacked multijunction solar cells based on III–V semiconductors materials are the state-of-art of approach for high efficiency photovoltaic energy conversion, in particular for space applications. The individual subcells of the multi-junction structure are interconnected via tunnel diodes which must be optically transparent and connect the component cells with a minimum electrical resistance. The quality of these diodes determines the output performance of the solar cell. The purpose of this work is to contribute to the investigation of the tunnel electrical resistance of such a multi-junction cell through the analysis of the current-voltage (J-V characteristics under illumination. Our approach is based on an equivalent circuit model of a diode for each subcell. We examine the effect of tunnel resistance on the performance of a multi-junction cell using minimization of the least squares technique.

  11. Effects of Angiotensin Ⅱ on Expression of the Gap Junction Channel Protein Connexin 43 in Neonatal Rat Ventricular Myocytes

    Institute of Scientific and Technical Information of China (English)

    Jun Yang; Wei Wu

    2007-01-01

    To study the effects of angiotensin Ⅱ,as a mediator of cardiac hypertrophy,on expression of connexin 43 (Cx43) in cultured neonatal rat ventricular myocytes and correlation of expression of Cx43 and cardiomyocyte hypertrophy.Methods Cardiomyocytes were isolated from newborn SD rats.Angiotensin Ⅱ was added into the media to induce myocyte hypertrophy.Cultures were exposed to 10 ~6 mol/L angiotensin Ⅱ for 72 h,Cx43 expression was characterized by RT-PCR and Immunofluorescence methods.Results Immunofluorescence analysis revealed decreased Cx43 immunoreactivity in cells treated for 72 h with angiotensin Ⅱ.RT-PCR analysis demonstrated there was an obvious decrease of Cx43 mRNA level in cells exposed to angiotensin Ⅱ for 72 h.The changes of expression of connexin 43 were related to its entrance into S phase of the cell cycle.Cultured neonatal rat cardiomyocytes were exposed for 72 h to increase concentrations of angiotensin Ⅱ ( 1.0 × 10-9 ~ 1.0 × 10-6mol/L),resulting in significantly decreased Cx43 expression.Conclusions Angiotensin Ⅱ leads to a concentration-dependent decrease in Cx43 protein in cultured neonatal rat ventricular myocytes by decreasing Cx43 mRNA synthesis.Signal transduction pathways activated by angiotensin Ⅱ under pathophysiologic conditions of cardiac hypertrophy could initiate remodeling of gap junctions.

  12. The Effect of Capsaicin Derivatives on Tight-Junction Integrity and Permeability of Madin-Darby Canine Kidney Cells.

    Science.gov (United States)

    Kaiser, Mathias; Chalapala, Sudharani; Gorzelanny, Christian; Perali, Ramu Sridhar; Goycoolea, Francisco Martin

    2016-02-01

    Capsaicin is known to interfere with tight junctions (TJs) of epithelial cells and therefore to enhance paracellular permeability of poorly absorbable drugs. However, due to its low water solubility, pungency, and cytotoxicity, its pharmacologic use is limited. In this study, we investigated the effect of capsaicin derivatives of synthetic (e.g., 10-hydroxy-N-(4-hydroxy-3-methoxybenzyl)decanamide, etc.) and natural (olvanil and dihydrocapsaicin) origin on Madin-Darby Canine Kidney-C7 cells. Impedance spectroscopy was used to determine the transepithelial electrical resistance and the capacitance. Permeability assays with fluorescein isothiocyanate-dextran were carried out to evaluate the impact on cell permeability. The results show that lipophilicity could play an important role for the interference with TJ and that the mechanism is independent from the ion channel TRPV-1 and hence on the flux of calcium into the cells. In summary, we synthesized 4 derivatives of capsaicin of lower lipophilicity and compared their properties with other well-known vanilloids. We show that these compounds are able to enhance the permeability of a hydrophilic macromolecule, by opening the TJ for a shorter time than capsaicin. This behavior is dependent on the lipophilicity of the molecule. Understanding of these phenomena may lead to better control of administration of therapeutic molecules.

  13. Characterization, Modeling and Design Parameters Identification of Silicon Carbide Junction Field Effect Transistor for Temperature Sensor Applications

    Directory of Open Access Journals (Sweden)

    Sofiane Khachroumi

    2010-01-01

    Full Text Available Sensor technology is moving towards wide-band-gap semiconductors providing high temperature capable devices. Indeed, the higher thermal conductivity of silicon carbide, (three times more than silicon, permits better heat dissipation and allows better cooling and temperature management. Though many temperature sensors have already been published, little endeavours have been invested in the study of silicon carbide junction field effect devices (SiC-JFET as a temperature sensor. SiC-JFETs devices are now mature enough and it is close to be commercialized. The use of its specific properties versus temperatures is the major focus of this paper. The SiC-JFETs output current-voltage characteristics are characterized at different temperatures. The saturation current and its on-resistance versus temperature are successfully extracted. It is demonstrated that these parameters are proportional to the absolute temperature. A physics-based model is also presented. Relationships between on-resistance and saturation current versus temperature are introduced. A comparative study between experimental data and simulation results is conducted. Important to note, the proposed model and the experimental results reflect a successful agreement as far as a temperature sensor is concerned.

  14. Electrical detection of the biological interaction of a charged peptide via gallium arsenide junction-field-effect transistors

    Science.gov (United States)

    Lee, Kangho; Nair, Pradeep R.; Alam, Muhammad A.; Janes, David B.; Wampler, Heeyeon P.; Zemlyanov, Dmitry Y.; Ivanisevic, Albena

    2008-06-01

    GaAs junction-field-effect transistors (JFETs) are utilized to achieve label-free detection of biological interaction between a probe transactivating transcriptional activator (TAT) peptide and the target trans-activation-responsive (TAR) RNA. The TAT peptide is a short sequence derived from the human immunodeficiency virus-type 1 TAT protein. The GaAs JFETs are modified with a mixed adlayer of 1-octadecanethiol (ODT) and TAT peptide, with the ODT passivating the GaAs surface from polar ions in physiological solutions and the TAT peptide providing selective binding sites for TAR RNA. The devices modified with the mixed adlayer exhibit a negative pinch-off voltage (VP) shift, which is attributed to the fixed positive charges from the arginine-rich regions in the TAT peptide. Immersing the modified devices into a TAR RNA solution results in a large positive VP shift (>1 V) and a steeper subthreshold slope (˜80 mV/decade), whereas "dummy" RNA induced a small positive VP shift (˜0.3 V) without a significant change in subthreshold slopes (˜330 mV/decade). The observed modulation of device characteristics is analyzed with analytical modeling and two-dimensional numerical device simulations to investigate the electronic interactions between the GaAs JFETs and biological molecules.

  15. Acute effects of direct inhibitory pressure over the biceps brachii myotendinous junction on skeletal muscle activation and force output.

    Science.gov (United States)

    Cè, Emiliano; Longo, Stefano; McCoy, Emily; Bisconti, Angela Valentina; Tironi, Davide; Limonta, Eloisa; Rampichini, Susanna; Rabuffetti, Marco; Esposito, Fabio

    2017-08-12

    Force (F) reduction is reported with myotendinous junction (MTJ) manipulation. Autogenic inhibition reflex (AIR) activation is supposed to be the main mechanism. Still, its role remains unclear. The study aimed at assessing the effects of MTJ direct inhibitory pressure (DIP) on neuromuscular activation and F in the elbow flexor (agonist) and extensor (antagonist) muscles. After maximum voluntary contraction (MVC) assessment, thirty-five participants randomly performed submaximal contractions at 20, 40, 60, and 80% MVC. Electromyographic (EMG), mechanomyographic (MMG), and F signals were recorded. Protocol was repeated under (i) DIP (10-s pressure on the biceps brachii MTJ) with the elbow at 120° (DIP120), (ii) DIP with the elbow at 180° (DIP180), and (iii) without DIP (Ctrl). Electromechanical delay (EMD) components, EMG and MMG root mean square (RMS), and rate of force development (RFD) were calculated. Independently from the angle, DIP induced decrements in MVC, RFD, and RMS of EMG and MMG signals and lengthened the EMD components in agonist muscles (P<0.05). The DIP-induced decrease in F output of the agonist muscles seems to be possibly due to a concomitant impairment of the neuromuscular activation and a transient decrease in stiffness. After DIP, the antagonist muscle displayed no changes; therefore, the intervention of AIR remains questionable. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Effect of RF pulsing biasing on the etching of magnetic tunnel junction materials using CH3OH.

    Science.gov (United States)

    Jeon, Min Hwan; Yun, Deok Hyun; Yang, Kyung Chae; Youn, Ji Youm; Lee, Du Yeong; Shim, Tae Hun; Park, Jea Gun; Yeom, Geun Young

    2014-12-01

    The magnetic tunnel junction (MTJ)-related materials such as CoFeB, CoPt, MgO, and Ru, and W were etched using CH3OH in a pulse-biased inductively coupled plasma system and the effect of bias pulsing (100% 30% duty percentage) on the etch characteristics of the MTJ-related materials was investigated at the substrate temperature of 200 degrees C. The etch selectivity of MTJ-related materials over W was improved by using pulse-biasing possibly due to the formation of more stable and volatile etch products during the pulse-off time and the removal of the compounds more easily on the etched CoFeB surface during the pulse-on time. X-ray photoelectron spectroscopy also showed that the use of lower duty percentage decreases the residue thickness remaining on the etched MTJ materials indirectly indicated the higher volatility of the etch products by the bias pulsing. The etching of nano-patterned CoFeB masked with W also showed more anisotropic etch profile by pulse-biasing probably due to the increased the etch selectivity of CoFeB over W and the decreased redeposition of etch products on the sidewall of the CoFeB features. The most anisotropic CoFeB etch profiles could be observed by using CH3OH gas in the pulse biasing of 30% duty ratio.

  17. Effects of radiographic contrast media on the micromorphology of the junctional complex of erythrocytes visualized by immunocytology.

    Science.gov (United States)

    Franke, Ralf-Peter; Krüger, Anne; Scharnweber, Tim; Wenzel, Folker; Jung, Friedrich

    2014-09-12

    Effects of radiographic contrast media (RCM) application were demonstrated in vitro and in vivo where the injection of RCM into the A. axillaris of patients with coronary artery disease was followed by a significant and RCM-dependent decrease of erythrocyte velocity in downstream skin capillaries. Another study in pigs revealed that the deceleration of erythrocytes coincided with a significant reduction of the oxygen partial pressure in the myocardium--supplied by the left coronary artery--after the administration of RCM into this artery. Further reports showed RCM dependent alterations of erythrocytes like echinocyte formation and exocytosis, sequestration of actin or band 3 and the buckling of endothelial cells coinciding with a formation of interendothelial fenestrations leading to areas devoid of endothelial cells. Key to morphological alterations of erythrocytes is the membrane cytoskeleton, which is linked to the band 3 in the erythrocyte membrane via the junctional complex. Fundamental observations regarding the cell biological and biochemical aspects of the structure and function of the cell membrane and the membrane cytoskeleton of erythrocytes have been reported. This review focuses on recent results gained, e.g., by advanced confocal laser scanning microscopy of different double-stained structural elements of the erythrocyte membrane cytoskeleton.

  18. Tanshinone IIA increases the bystander effect of herpes simplex virus thymidine kinase/ganciclovir gene therapy via enhanced gap junctional intercellular communication.

    Science.gov (United States)

    Xiao, Jianyong; Zhang, Guangxian; Qiu, Pengxiang; Liu, Xijuan; Wu, Yingya; Du, Biaoyan; Li, Jiefen; Zhou, Jing; Li, Jingjing; Tan, Yuhui

    2013-01-01

    The bystander effect is an intriguing phenomenon by which adjacent cells become sensitized to drug treatment during gene therapy with herpes simplex virus thymidine kinase/ganciclovir (HSV-tk/GCV). This effect is reported to be mediated by gap junctional intercellular communication (GJIC), and therefore, we postulated that upregulation of genes that facilitate GJIC may enhance the HSV-tk/GCV bystander effect. Previous findings have shown Tanshinone IIA (Tan IIA), a chemical substance derived from a Chinese medicine herb, promotes the upregulation of the connexins Cx26 and Cx43 in B16 cells. Because gap junctions are formed by connexins, we hypothesized that Tan IIA might increase GJIC. Our results show that Tan IIA increased GJIC in B16 melanoma cells, leading to more efficient GCV-induced bystander killing in cells stably expressing HSV-tk. Additionally, in vivo experiments demonstrated that tumors in mice with 10% HSV-tk positive B16 cells and 90% wild-type B16 cells became smaller following treatment with the combination of GCV and Tan IIA as compared to GCV or Tan IIA alone. These data demonstrate that Tan IIA can augment the bystander effect of HSV-tk/GCV system through increased gap junction coupling, which adds strength to the promising strategy that develops connexins inducer to potentiate the effects of suicide gene therapy.

  19. Tanshinone IIA increases the bystander effect of herpes simplex virus thymidine kinase/ganciclovir gene therapy via enhanced gap junctional intercellular communication.

    Directory of Open Access Journals (Sweden)

    Jianyong Xiao

    Full Text Available The bystander effect is an intriguing phenomenon by which adjacent cells become sensitized to drug treatment during gene therapy with herpes simplex virus thymidine kinase/ganciclovir (HSV-tk/GCV. This effect is reported to be mediated by gap junctional intercellular communication (GJIC, and therefore, we postulated that upregulation of genes that facilitate GJIC may enhance the HSV-tk/GCV bystander effect. Previous findings have shown Tanshinone IIA (Tan IIA, a chemical substance derived from a Chinese medicine herb, promotes the upregulation of the connexins Cx26 and Cx43 in B16 cells. Because gap junctions are formed by connexins, we hypothesized that Tan IIA might increase GJIC. Our results show that Tan IIA increased GJIC in B16 melanoma cells, leading to more efficient GCV-induced bystander killing in cells stably expressing HSV-tk. Additionally, in vivo experiments demonstrated that tumors in mice with 10% HSV-tk positive B16 cells and 90% wild-type B16 cells became smaller following treatment with the combination of GCV and Tan IIA as compared to GCV or Tan IIA alone. These data demonstrate that Tan IIA can augment the bystander effect of HSV-tk/GCV system through increased gap junction coupling, which adds strength to the promising strategy that develops connexins inducer to potentiate the effects of suicide gene therapy.

  20. Effect of enzyme addition to forage at ensiling on silage chemical composition and NDF degradation characteristics

    DEFF Research Database (Denmark)

    Dehghani, Mohammad Reza; Weisbjerg, Martin Riis; Hvelplund, Torben

    2012-01-01

    The effect of different exogenous fibrolytic enzymes added to forages at ensiling was examined for effect on chemical composition and in vitro NDF degradability characteristics of the resulting silage. Maize stover and lucerne were used to study effect on chemical composition in experiment 1...... digestibility decreased in treated maize stover silage. Potential NDF degradability decreased due to enzyme treatments but not for all maize stover treatments. Treatments with combination of enzymes with glucanase, β-glucanase and pectinase activity mostly resulted in increases in fermentation products compared......, and two varieties of maize stover, lucerne and grass clover were used to study NDF degradation characteristics in experiment 2. Forages were treated with enzymes (500 mg crude protein of the enzyme products/kg DM) and ensiled for 60 days in vacuum-sealed bags. Samples of forage (before ensiling...

  1. Effects of environmental conditions on aerobic degradation of a commercial naphthenic acid.

    Science.gov (United States)

    Kinley, Ciera M; Gaspari, Daniel P; McQueen, Andrew D; Rodgers, John H; Castle, James W; Friesen, Vanessa; Haakensen, Monique

    2016-10-01

    Naphthenic acids (NAs) are problematic constituents in energy-derived waters, and aerobic degradation may provide a strategy for mitigating risks to aquatic organisms. The overall objective of this study was to determine the influence of concentrations of N (as ammonia) and P (as phosphate), and DO, as well as pH and temperatures on degradation of a commercial NA in bench-scale reactors. Commercial NAs provided replicable compounds necessary to compare influences of environmental conditions on degradation. NAs were quantified using high performance liquid chromatography. Microbial diversity and relative abundance were measured in treatments as explanatory parameters for potential effects of environmental conditions on microbial populations to support analytically measured NA degradation. Environmental conditions that positively influenced degradation rates of Fluka NAs included nutrients (C:N 10:1-500:1, C:P 100:1-5000:1), DO (4.76-8.43 mg L(-1)), pH (6-8), and temperature (5-25 °C). Approximately 50% removal of 61 ± 8 mg L(-1) was achieved in less than 2 d after NA introduction, achieving the method detection limit (5 mg L(-1)) by day 6 of the experiment in treatments with a C:N:P ratio of 100:10:1, DO > 8 mg L(-1), pH ∼8-9, and temperatures >23 °C. Microbial diversity was lowest in lower temperature treatments (6-16 °C), which may have resulted in observed slower NA degradation. Based on results from this study, when macro- and micronutrients were available, DO, pH, and temperature (within environmentally relevant ranges) influenced rates of aerobic degradation of Fluka NAs. This study could serve as a model for systematically evaluating environmental factors that influence NA degradation in field scenarios.

  2. Effects of Angiopoietin-2-Blocking Antibody on Endothelial Cell–Cell Junctions and Lung Metastasis

    OpenAIRE

    2012-01-01

    Background: Angiopoietin-2 (Ang2), a ligand for endothelial TEK (Tie2) tyrosine kinase receptor, is induced in hypoxic endothelial cells of tumors, where it promotes tumor angiogenesis and growth. However, the effects of Ang2 on tumor lymphangiogenesis and metastasis are poorly characterized. Methods: We addressed the effect of Ang2 on tumor progression and metastasis using systemic Ang2 overexpression in mice carrying tumor xenografts, endothelium-specific overexpression of Ang2 in VEC-t...

  3. The effect of environmental humidity on radiation-induced degradation of carrageenans.

    Science.gov (United States)

    Sen, Murat; Toprak, Deniz; Güven, Olgun

    2014-12-19

    Better understanding of the chemistry of radiation-induced degradation is becoming of increasing importance on account of the utilization of polymeric materials in a variety of radiation environments as well as beneficial uses of degraded polymers. In this report the importance of environmental humidity on the degrading effect of radiation has been considered from the point of view of controlling the molecular weights of kappa- and iota-carrageenans. These two polysaccharides were irradiated in solid form under strictly controlled environmental humidity conditions by incubating and later irradiating the samples over saturated aqueous salt solutions of NaCl, NaNO3 and MgCl2. The degradation was followed in detail by a careful gel permeation chromatographic analysis of their respective molecular weights before and after irradiation. The chain scission yield values G(S) were found to decrease with the water adsorbed from environment at every absorbed dose in the range of 5-100 kGy. On the other hand at very high water uptakes the yield of chain scission again increases especially at low doses. The decrease in degradation yield was attributed to the plastifying effect of water trapped in between the polymer chains facilitating the macroradical recombinations thus reducing the extent of chain scission. This study showed that although carrageenans were irradiated in solid form, the difference in their water uptake from changing environmental humidity has a profound effect in controlling their molecular weights by irradiation with ionizing radiation.

  4. The effect of built-in drift field and emitter recombinations on FCVD of a p- n junction diode

    Science.gov (United States)

    Jain, S. C.; Ray, U. C.

    1983-06-01

    This paper discusses the Forward Current induced open circuit Voltage Decay (FCVD) of a p- n junction diode including the effects of recombinations in the emitter as well as the built-in drift fields in the base and in the emitter. The analysis is based on the quasi-static approximation (QSA) of the carrier profiles in the emitter. It is shown that the emitter effects on FCVD is completely determined by JEO, the dark saturation current in the emitter. The value of JEO in general, depends on the heavy doping effects in the emitter, the drift field in the emitter, emitter thickness and surface recombination velocity at the emitter surface. It is shown that for a diode with retarding drift field in the base, emitter recombinations play a very significant role in FCVD. The decay time constant for large values of time in this case is given by τ eff = τ B/[1 + ƒ B2 - (a - ƒ B) 2], where a = J EO/J BO, ƒ B is the drift field parameter in the base. The higher value of a, the faster is the voltage decay. For accelerating fields in the base, the time constant for large values of time is independent of emitter recombinations and is given by τ eff = τ B/(1 + ƒ B2) . However, the decay rate for small values of time is strongly affected by emitter recombinations for both types of the field; the higher the emitter recombinations, the faster is the initial rate of the voltage decay. For extremely strong drift fields in the base, QSA in the emitter is not valid. The coupled continuity equations are solved with the conditions ƒ B2 ≫ τ B/τ E and an analytic expression for FCVD is derived. It is seen that FCVD for strong base fields is determined solely by emitter lifetime τE except for small values of time of the order of a few τE.

  5. Electrical characterization of commercial NPN bipolar junction transistors under neutron and gamma irradiation

    Directory of Open Access Journals (Sweden)

    OO Myo Min

    2014-01-01

    Full Text Available Electronics components such as bipolar junction transistors, diodes, etc. which are used in deep space mission are required to be tolerant to extensive exposure to energetic neutrons and ionizing radiation. This paper examines neutron radiation with pneumatic transfer system of TRIGA Mark-II reactor at the Malaysian Nuclear Agency. The effects of the gamma radiation from Co-60 on silicon NPN bipolar junction transistors is also be examined. Analyses on irradiated transistors were performed in terms of the electrical characteristics such as current gain, collector current and base current. Experimental results showed that the current gain on the devices degraded significantly after neutron and gamma radiations. Neutron radiation can cause displacement damage in the bulk layer of the transistor structure and gamma radiation can induce ionizing damage in the oxide layer of emitter-base depletion layer. The current gain degradation is believed to be governed by the increasing recombination current in the base-emitter depletion region.

  6. Study of the effect of the fibre mass UP2 degradation products on radionuclide mobilisation

    Energy Technology Data Exchange (ETDEWEB)

    Duro, Lara; Grive, Mireia; Gaona, Xavier; Bruno, Jordi [Amphos 21 Consulting S.L., Barcelona (Spain); Andersson, Thomas; Boren, Hans; Dario, Maarten [Linkoeping Univ., Linkoeping (Sweden); Allard, Bert; Hagberg, Jessica [Oerebro Univ., Oerebro (Sweden); Kaellstroem, Klas [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)

    2012-09-15

    This report presents a literature review and laboratory work of the degradation of the fibre UP2, as well as an assessment of the effects of its degradation products on Europium sorption onto cement, as an example of their effects on radionuclide migration. All laboratory work was performed by the Swedish groups (Linkoeping and Oerebro Universities), who also performed some of the literature review. The data interpretation was performed by the Spanish team (Amphos 21). SKB has combined the reports of these studies into this common document and has added minor editorial changes. All these changes have been accepted by the authors.

  7. Parity violation effects in the Josephson junction of a p-wave superconductor

    Science.gov (United States)

    Belov, Nikolay A.; Harman, Zoltán

    2016-10-01

    The phenomenon of the parity violation due to weak interaction may be studied with superconducting systems. Previous research considered the case of conventional superconductors. We here theoretically investigate the parity violation effect in an unconventional p-wave ferromagnetic superconductor, and find that its magnitude can be increased by three orders of magnitude, as compared to results of earlier studies. For potential experimental observations, the superconductor UGe2 is suggested, together with the description of a possible experimental scheme allowing one to effectively measure and control the phenomenon. Furthermore, we put forward a setup for a further significant enhancement of the signature of parity violation in the system considered.

  8. NUTRITIONAL COMPOSITION AND EFFECTIVE DEGRADABILITY OF FOUR FORAGE TREES GROWN FOR PROTEIN SUPPLEMENTATION

    Directory of Open Access Journals (Sweden)

    J. GUSHA

    2013-07-01

    Full Text Available The chemical composition and ruminal degradability of dry matter (DM and nitrogen (N of four browse legumes (Gliricidia sepium, C. calothyrsus, A. angustissima and Leucaena. pallida were evaluated. The in sacco degradability of protein and DM of the four browse legumes were determined using four mature Friesian- Holstein rumen-cannulated steers (440=20kg live weight. The objective of this study was to evaluate the usefulness of the browse legumes using the nylon bag technique. Nylon bags with 3g samples of dried ground legumes (3mm screen were incubated in the rumen. The incubation times were 0, 6, 12, 48, 72 and 120 hours in four cannulated Friesian- Holstein steers. The browse legumes were analysed for nutritive value in terms of dry matter (DM, crude protein (CP, acid detergent fibre (ADF, neutral detergent fibre (NDF, Ash, condensed tannin (CT, calcium (Ca2+ and Phosphorus (P. Dry matter degradability was significantly different (P<0.05 and Gliricidia was highest, followed by L. pallida then A. angustissima and C. calothyrsus in descending order. Crude protein degradability was significantly (P<0.05 lower than that of DM and was highest in L. pallida, G. sepium, A. angustissima and finally C. calothyrsus at the bottom. Effective degradability of DM in the rumen of the steers was highest with G. sepium (880g/kg DM at rumen outflow rate of 0.02/h and least with C. calothyrsus (504g/kg DM (P<0.001. Effective degradability of nitrogen was highest with L. pallida (645g/kg DM at outflow rate of 0.02/h and least with C. calothyrsus (103g/kg DM (P<0.001. The degradability profiles of these browse indicated that they can be used as alternative protein supplements.

  9. Effect of nitrogen on the degradation of cypermethrin and its metabolite 3-phenoxybenzoic acid in soil

    Institute of Scientific and Technical Information of China (English)

    XIE Wen-Jun; ZHOU Jian-Min; WANG Huo-Yan; CHEN Xiao-Qin

    2008-01-01

    Increasing use of pyrethroid insecticides has resulted in concerns regarding potential effects on human health and ecosystems.Cypermethrin and its metabolite 3-phenoxybenzoic acid (PBA) have exerted adverse biological impacts on the environment; therefore,it is critically important to develop different methods to enhance their degradation.In this study,incubation experiments were conducted using samples of an Aquic Inceptisol supplied with nitrogen (N) in the form of NH4NO3 at different levels to investigate the effect of nitrogen on the degradation of cypermethrin and PBA in soil.The results indicated that appropriate N application can promote the degradation of cypermethrin and PBA in soil.The maximum degradation rates were 80.0% for cypermethrin after 14 days of incubation in the treatment with N at a rate of 122.1 kg ha-1 and 41.0% for PBA after 60 days of incubation in the treatment with N at a rate of 182.7 kg ha-1.The corresponding rates in the treatments without nitrogen were 62.7% for cypermethrin and 27.8% for PBA.However,oversupplying N significantly reduced degradation of these compounds.Enhancement of degradation could be explained by the stimulation of microbial activity after the addition of N.In particular,dehydrogenase activities in the soil generally increased with the addition of N,except in the soil where N was applied at the highest level.The lower degradation rate measured in the treatment with an oversupply of N may be attributed to the microbial metabolism shifts induced by high N.

  10. Effective rumen degradation of dry matter, crude protein and neutral detergent fibre in forage determined by near infrared reflectance spectroscopy.

    Science.gov (United States)

    Ohlsson, C; Houmøller, L P; Weisbjerg, M R; Lund, P; Hvelplund, T

    2007-12-01

    The objective of the present study was to examine if near infrared reflectance spectroscopy (NIRS) could be used to predict degradation parameters and effective degradation from scans of original forage samples. Degradability of dry matter (DM), crude protein (CP) and neutral detergent fibre (NDF) of 61 samples of perennial ryegrass (Lolium perenne L.) and orchardgrass (Dactylis glomerata L.) was tested by using the in situ technique. The grass samples were harvested at three different stages, early vegetative growth, early reproductive growth and late reproductive growth. Degradability was described in terms of immediately rumen soluble fraction (a fraction, for DM and CP only as NDF does not contain a soluble fraction), the degradable but not soluble faction (b fraction) and the rate of degradation of the b fraction (c value). Overall effective degradability of DM, CP and NDF was also calculated. Near infrared reflectance spectroscopy was examined for its ability to predict degradation parameters and to make a direct prediction of effective degradation from scans of the original samples of perennial ryegrass and orchardgrass. Prediction of effective degradation of the different feed fractions showed different accuracy. The coefficients of determination (R(2)) from regressions of predicted vs. measured effective degradation, using a cross-validation method, were 0.92 for DM, 0.78 for CP and 0.61 for NDF. The attempt to predict the degradation parameters (a, b and c) by NIRS was less successful as the coefficients of determination for the degradation parameters were low. Concentrations of CP and NDF in the original samples were predicted by using NIRS and the validated R(2) value was 0.98 for CP and 0.92 for NDF. It is concluded that using NIRS predictions from scans of original samples is a promising method to obtain values for the effective degradation of DM, CP and NDF in ruminant feeds, but that larger calibration sets are necessary for obtaining improved

  11. A comparison of degradation in three amorphous silicon PV module technologies

    Energy Technology Data Exchange (ETDEWEB)

    Radue, C.; van Dyk, E.E. [Physics Department, PO Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa)

    2010-03-15

    Three commercial amorphous silicon modules manufactured by monolithic integration and consisting of three technology types were analysed in this study. These modules were deployed outdoors for 14 months and underwent degradation. All three modules experienced the typical light-induced degradation (LID) described by the Staebler-Wronski effect, and this was followed by further degradation. A 14 W single junction amorphous silicon module degraded by about 45% of the initial measured maximum power output (P{sub MAX}) at the end of the study. A maximum of 30% of this has been attributed to LID and the further 15% to cell mismatch and cell degradation. The other two modules, a 64 W triple junction amorphous silicon module, and a 68 W flexible triple junction amorphous silicon module, exhibited LID followed by seasonal variation in the degraded P{sub MAX}. The 64 W module showed a maximum degradation in P{sub MAX} of about 22%. This is approximately 4% more than the manufacturer allowed for the initial LID. However, the seasonal variation in P{sub MAX} seems to be centred around the manufacturer's rating ({+-}4%). The 68 W flexible module has shown a maximum decrease in P{sub MAX} of about 27%. This decrease is about 17% greater than the manufacturer allowed for the initial LID. (author)

  12. Effect of reactor's positions on polymerization and degradation in an ultrasonic field.

    Science.gov (United States)

    Kobayashi, Daisuke; Matsumoto, Hideyuki; Kuroda, Chiaki

    2008-03-01

    Ultrasonic generators are used as emulsifiers and efficient alternative initiators in polymerization processes. In this study, the effects of reactor's position on the emulsion polymerization of styrene under indirect ultrasonic irradiation were investigated, along with the effects of reactor's position on chemical and physical degradation. Both polymer yield and molecular weight were influenced by the position of the reactor. The ultrasonic irradiation could be divided into three stages, and the molecular weight of the polymer was influenced by polymerization and degradation processes. It was found that the extent of radical generation estimated by KI oxidation dosimetry and the shock wave index obtained from studies of degradation of standard polymer were useful for controlling the characteristics of the polymer generated.

  13. Mechanism and kinetics of 2-chlorophenol degradation in drinking water by photo-electrochemical synergic effect

    Institute of Scientific and Technical Information of China (English)

    SONG; Qiang; (宋; 强); QU; Jiuhui; (曲久辉)

    2003-01-01

    The synergic effect mechanism of photo-electrochemical oxidation is investigated in detail through reaction products and kinetics analysis in a photo-electric integral reactor with 2-chlorophenol (2-CP) as the model pollutant. A kinetics model is constructed for the combinatorial photo-electrochemical (CPE) degradation. A remarkable synergetic effect, which can significantly enhance the mineralization rate of the CPE process, is verified by the comparison of apparent kinetic constants. In the CPE process, complemental effects with multi-level and multi-pathway for pollutants degradation under our experimental conditions are speculated. It is proved that the degradation pathways are not only the simple summation of that of photolysis and electrolysis, but the formation of synergic effect through combination of several new acting approaches. The degradation efficiency is enhanced considerably by three factors, control of electrode poisoning by the UV irradiation, control of excitation and reaction trend of pollutants molecules by the UV irradiation, and control of activation effect and transfer trend by the oriented direct current (DC) electric field. An advanced oxidation system is set up through manifold of free radicals chain reactions in the CPE reactions, so that the aqueous organics can be mineralized fast and completely. It is proven by the kinetics analysis that the mineralization of organic pollutants is mainly attributed to the generation of very active hydroxyl radicals (OH@) in bulk solution from the CPE synergetic effect.

  14. Involvement of gap junctional intercellular communication in the bystander effect induced by broad-beam or microbeam heavy ions

    Science.gov (United States)

    Shao, Chunlin; Furusawa, Yoshiya; Kobayashi, Yasuhiko; Funayama, Tomoo

    2006-09-01

    Most of the reported bystander responses were studied by using low dose irradiation of γ-rays and light ions such as alpha-particles. In this study, primary human fibroblasts AG1522 in confluent cultures were irradiated with either broad-beam of 100 keV/μm 12C or microbeams of 380 keV/μm 20Ne and 1260 keV/μm 40Ar. When cells were irradiated with 12C ions, the induction of micronucleus (MN) had a low-dose sensitive effect, i.e. a lower dose of irradiation gave a higher yield of MN per cell-traversal. This phenomenon was further reinforced by using a microbeam to irradiate a fraction of cells within a population. Even when only a single cell was targeted with one particle of 40Ar or 20Ne, the MN yield was increased to 1.4-fold of the non-irradiated control. When the number of microbeam targeted cells increased, the MN yield per targeted-cell decreased drastically. In addition, the bystander MN induction did not vary significantly with the number and the linear energy transfer (LET) of microbeam particles. When the culture was treated with PMA, an inhibitor of gap junctional intercellular communication (GJIC), MN induction was decreased for both microbeam and broad-beam irradiations even at high-doses where all cells were hit. The present findings indicate that a GJIC-mediated signaling amplification mechanism was involved in the high-LET heavy ion irradiation induced bystander effect. Moreover, at high-doses of radiation, the bystander signals could perform a complex interaction with direct irradiation.

  15. Effect of dynamic operation on chemical degradation of a polymer electrolyte membrane fuel cell

    Science.gov (United States)

    Jung, Minjae; Williams, Keith A.

    2011-03-01

    Dynamic operation is known as one of the factors for accelerating chemical degradation of the polymer electrolyte membrane in a polymer electrolyte membrane fuel cell (PEMFC). However, little effort has been made dealing with the quantification of the degradation process. In this investigation, cyclic current operation is carried out on a fuel cell system, and the frequency effect of cyclic operation on chemical degradation is investigated. The dynamic behavior of a fuel cell system is analyzed first with the modified Randles model, where the charge double layer is modeled by three components; a charge transfer resistance (Rct), and two RC cells for the Warburg impedance. After calculating each parameter value through exponential curve fitting, the dynamic behaviors of the three components are simulated using MATLAB Simulink®. Fluoride release as a function of the frequency of cyclic operation is evaluated by measuring the concentration of fluoride ion in effluent from a fuel cell exhaust. The frequency effect on chemical degradation is explained by comparing the simulated results and the fluoride release results. Two possible reasons for the accelerated degradation at cyclic operation are also suggested.

  16. Cortical processing of degraded speech sounds: effects of distortion type and continuity.

    Science.gov (United States)

    Miettinen, Ismo; Alku, Paavo; Yrttiaho, Santeri; May, Patrick J C; Tiitinen, Hannu

    2012-04-01

    Human speech perception is highly resilient to acoustic distortions. In addition to distortions from external sound sources, degradation of the acoustic structure of the sound itself can substantially reduce the intelligibility of speech. The degradation of the internal structure of speech happens, for example, when the digital representation of the signal is impoverished by reducing its amplitude resolution. Further, the perception of speech is also influenced by whether the distortion is transient, coinciding with speech, or is heard continuously in the background. However, the complex effects of the acoustic structure and continuity of the distortion on the cortical processing of degraded speech are unclear. In the present magnetoencephalography study, we investigated how the cortical processing of degraded speech sounds as measured through the auditory N1m response is affected by variation of both the distortion type (internal, external) and the continuity of distortion (transient, continuous). We found that when the distortion was continuous, the N1m was significantly delayed, regardless of the type of distortion. The N1m amplitude, in turn, was affected only when speech sounds were degraded with transient internal distortion, which resulted in larger response amplitudes. The results suggest that external and internal distortions of speech result in divergent patterns of activity in the auditory cortex, and that the effects are modulated by the temporal continuity of the distortion.

  17. Anodic oxidation of o-nitrophenol on BDD electrode: Variable effects and mechanisms of degradation

    Energy Technology Data Exchange (ETDEWEB)

    Rabaaoui, Nejmeddine, E-mail: chimie_tunisie@yahoo.fr [Materials, Environment and Energy Laboratory (06/UR/12-01), Science Faculty of Gafsa, 2112, University of Gafsa (Tunisia); Saad, Mohamed El Khames [Materials, Environment and Energy Laboratory (06/UR/12-01), Science Faculty of Gafsa, 2112, University of Gafsa (Tunisia); Moussaoui, Younes [Materials, Environment and Energy Laboratory (06/UR/12-01), Science Faculty of Gafsa, 2112, University of Gafsa (Tunisia); Physical Organic Chemistry Laboratory, Science Faculty of Sfax, University of Sfax (Tunisia); Allagui, Mohamed Salah [Science Faculty of Gafsa, University of Gafsa (Tunisia); Bedoui, Ahmed [Materials, Environment and Energy Laboratory (06/UR/12-01), Science Faculty of Gafsa, 2112, University of Gafsa (Tunisia); Science Faculty of Gabes, 6072, University of Gabes (Tunisia); Elaloui, Elimame [Materials, Environment and Energy Laboratory (06/UR/12-01), Science Faculty of Gafsa, 2112, University of Gafsa (Tunisia); Science Faculty of Gafsa, University of Gafsa (Tunisia)

    2013-04-15

    Highlights: ► Anodic oxidation is an effective method for degrading o-nitrophenol. ► The effect of operating parameters on the degradation was investigated. ► The main intermediate products were determined by HPLC technique. ► A plausible degradation pathway of o-nitrophenol was proposed. -- Abstract: The electrochemical oxidation of pesticide, o-nitrophenol (ONP) as one kind of pesticide that is potentially dangerous and biorefractory, was studied by galvanostatic electrolysis using boron-doped diamond (BDD) as anode. The influence of several operating parameters, such as applied current density, supporting electrolyte, and initial pH value, was investigated. The best degradation occurred in the presence of Na{sub 2}SO{sub 4} (0.05 M) as conductive electrolyte. After 8 h, nearly complete degradation of o-nitrophenol was achieved (92%) using BDD electrodes at pH 3 and at current density equals 60 mA cm{sup −2}. The decay kinetics of o-nitrophenol follows a pseudo-first-order reaction. Aromatic intermediates such as catechol, resorcinol, 1,2,4-trihydroxybenzene, hydroquinone and benzoquinone and carboxylic acids such as maleic glycolic, malonic, glyoxilic and oxalic, have been identified and followed during the ONP treatment by chromatographic techniques. From these anodic oxidation by-products, a plausible reaction sequence for ONP mineralization on BDD anodes is proposed.

  18. Proximity effects in normal mental/spin-splitting material/superconductor junctions

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    We extend the Blonder, Tinkham and Klapwijk (BTK) theory to the study of the coexistence between ferromagnetism and s-wave superconductivity in ferromagnet/superconductor (F/S) structures. It is found that the ferromagnetism and s-wave superconductivity can coexist near the F/S interface, which is induced by proximity effects. On the F side, the density of states (DOS) exhibits some superconducting-like properties, and it displays a damped oscillation from '0' to 'π'states with increasing either the thickness of F film or the exchange energy. We also study the influences of the spin-polarized exchange splitting in the F and the spin-degeneracy by Rashba spin-orbit coupling (RSOC) in the two-dimensional electron gas (2DGE) on the proximity effects. It is shown that the case of Rashba spin-degeneracy is very different from that of the spin-polarized exchange splitting.

  19. Pseudospin-valve effect on transport in junctions of three-dimensional topological insulator surfaces

    Science.gov (United States)

    Roy, Sthitadhi; Roychowdhury, Krishanu; Das, Sourin

    2016-07-01

    We show that the surface states of pristine 3D topological insulators (TIs) are analogs of ferromagnetic half metals due to complete polarization of an emergent momentum independent pseudospin (SU(2)) degree of freedom on the surface. To put this claim on firm footing, we present results for TI surfaces perpendicular to the crystal growth axis, which clearly show that the tunneling conductance between two such TI surfaces of the same TI material is dominated by this half metallic behavior leading to physics reminiscent of a spin-valve. Further using the generalized tunnel magnetoresistance derived in this work we also study the tunneling current between arbitrary TI surfaces. We also perform a comprehensive study of the effect of all possible surface potentials allowed by time reversal symmetry on this spin-valve effect and show that it is robust against most of such potentials.

  20. Appearance of Spatial-Temporal Noise in Super-conducting Junction and Its Effect on Transport of Electron Pairs

    Institute of Scientific and Technical Information of China (English)

    LI Jing-Hui

    2007-01-01

    Transport of electron pairs in super-conducting junction with spatial-temporal noise is investigated.We show that the spatial-temporal noise can produce the current of the electron pairs,which stems from a symmetry breaking of the system induced by the correlation of the spatial-temporal noise with the phase difference.It is found that there is a positive current for the electron pairs,exhibiting a peak with increasing the values of some parameters of the noises.The results provide a theoretical foundation for the further investigation of the super-conducting junction.

  1. Effect of roasting on ruminal degradation, intestinal digestibility and ...

    African Journals Online (AJOL)

    The maximum AA disappeared in the SI of sheep when SBOC was .... + T1 + 111, where Yij = the response; F = overall mean; Ti = mean effect of ..... -5.6gan. 6.01". -5.65"b. 5.83'. 5.lzun. 5.42b. 5.29'. 5.47ub. 5.24" .5.7-5n. 5.26r. 5.364. 6.34''l.

  2. Coordinate transformation in the model of long Josephson junctions: geometrically equivalent Josephson junctions

    Science.gov (United States)

    Semerdzhieva, E. G.; Boyadzhiev, T. L.; Shukrinov, Yu. M.

    2005-10-01

    The transition from the model of a long Josephson junction of variable width to the model of a junction with a coordinate-dependent Josephson current amplitude is effected through a coordinate transformation. This establishes the correspondence between the classes of Josephson junctions of variable width and quasi-one-dimensional junctions with a variable thickness of the barrier layer. It is shown that for a junction of exponentially varying width the barrier layer of the equivalent quasi-one-dimensional junction has a distributed resistive inhomogeneity that acts as an attractor for magnetic flux vortices. The curve of the critical current versus magnetic field for a Josephson junction with a resistive microinhomogeneity is constructed with the aid of a numerical simulation, and a comparison is made with the critical curve of a junction of exponentially varying width. The possibility of replacing a distributed inhomogeneity in a Josephson junction by a local inhomogeneity at the end of the junction is thereby demonstrated; this can have certain advantages from a technological point of view.

  3. Prejunctional effects of the nicotinic ACh receptor agonist dimethylphenylpiperazinium at the rat neuromuscular junction.

    Science.gov (United States)

    Singh, S; Prior, C

    1998-09-01

    1. We have studied the effects of the nicotinic acetylcholine (ACh) receptor agonist dimethylphenylpiperazinium (DMPP) on the evoked release of ACh from motor terminals in the rat isolated hemidiaphragm using an electrophysiological approach. 2. DMPP (1-4 microM) had no effect on the rate of spontaneous quantal ACh release but increased the number of quanta of ACh released per impulse during 50 Hz stimulation. The DMPP-induced increase in evoked ACh release was dependent on the frequency of stimulation, being absent when it was reduced to 0.5 Hz, but was not Ca2+ dependent, being unaffected at 50 Hz by a 4-fold decrease in the extracellular Ca2+ concentration. 3. The facilitation of evoked ACh release at 50 Hz by 2 microM DMPP was abolished by 10 microM of the calmodulin antagonist W7 (N-(6-aminohexyl)-5-chloro-1-naphthalenesulphonamide hydrochloride) and, in the presence of W7, 2 microM DMPP depressed evoked ACh release at 0.5 Hz. The ability of the nicotinic ACh receptor antagonist vecuronium (1 microM) to depress evoked ACh release at 50 Hz was also abolished by 10 microM W7. 4. The present findings demonstrate, using an electrophysiological technique, that DMPP can produce changes in the evoked ACh release from rat motor nerve terminals that are consistent with the existence of facilitatory nicotinic ACh receptors on the motor nerve endings. Further, they indicate a role for calmodulin-dependent systems in this facilitatory effect of the compound.

  4. Modulation of interlayer exchange coupling strength in magnetic tunnel junctions via strain effect

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Xin, E-mail: jiangxinyj@gmail.com; Li, Zhipeng; Zheng, Yuankai; Kaiser, Christian; Diao, Zhitao; Fang, Jason; Leng, Qunwen, E-mail: Qunwen.Leng@wdc.com [Western Digital Corporation, 44100 Osgood Road, Fremont, California 94539 (United States)

    2015-09-15

    Interlayer exchange coupling of two ferromagnetic electrodes separated by a thin MgO tunnel barrier is investigated using magneto-optical Kerr effect. We find that the coupling field can be reduced by more than 40% as the thickness of a top Ta capping layer increases from 0.5 to 1.2 nm. In contrast, a similar film stack with an additional 3 nm Ru capping layer displays no such dependence on Ta thickness. Transmission electron microscopy study shows that the oxidation of the exposed Ta capping layer induces changes in the crystalline structures of the underlying films, giving rise to the observed reduction of the interlayer coupling field.

  5. Superconducting proximity effect in MBE grown Nb-InAs junctions

    Science.gov (United States)

    Kan, Carolyn; Xue, Chi; Law, Stephanie; Eckstein, James

    2013-03-01

    Several proposals for the realization of Majorana fermions rely on excellent quality proximity coupling between a superconductor and a high-mobility semiconductor. We examine the long-range proximity coupling between MBE-grown InAs and in situ grown superconducting overlayers by fabricating transport devices, and investigate the effect of substrate choice and growth conditions on the quality of the MBE InAs. GaAs is commonly available as a high quality insulating substrate. Overcoming its lattice mismatch with InAs using GaSb and AlSb layers results in locally smooth terraced surfaces, but global spiral dislocation structures also appear and have a negative impact on the InAs mobility. Growing InAs on homoepitaxial GaSb results in improved morphology and increases the mean free path. We compare the proximity effect in devices made both ways. This material is based upon work supported by the U.S. Department of Energy, Division of Materials Sciences under Award No. DE-FG02 07ER46453, through the Frederick Seitz Materials Research Laboratory at the University of Illinois at Urbana-Champaign.

  6. The effect of electrostatic heparin/collagen layer-by-layer coating degradation on the biocompatibility

    Science.gov (United States)

    Chen, Jialong; Huang, Nan; Li, Quanli; Chu, Chun H.; Li, Jun; Maitz, Manfred F.

    2016-01-01

    Electrostatic layer-by-layer coatings of heparin and collagen have been suggested before to improve the biocompatibility of blood-contacting devices. However, to our knowledge, there have been no systematic studies about the effect of degradation of this coating on its biocompatibility, anticoagulant properties and the cyto-compatibility. The purpose of this study was to design an in vitro experiment in this regard that can assess the degradation behavior and the biocompatibility change of the coating. The coating degradation in physiological saline (PS) under static and dynamic condition was monitored by DR-FTIR, SEM, AFM and water contact angle, moreover, heparin densities on the topmost surface and the release heparin every day were measured by toluidine blue O (TBO) assay. The results showed that the degradation rate of the coating in is much faster under flow and shear conditions than during static incubation, and only very limited collagen and heparin remain on the surface after 15 days incubation in dynamic condition. With the degradation, the hemocompatibility of the coating got worse, especially when incubated under dynamic conditions. The degradation products of the coating do not lead to coagulation but behave -as heparin- anticoagulant. The compatibility of the coating to endothelial cells improved within 15d incubation in static medium, but it for degradation under dynamic conditions, it improved for 5d but at 15d incubation, it was almost as low as for the bare substrate. These results highlight the necessity for appropriate testing of newly developed coatings not only in the initial state but also after extended exposure to a physiological ambient.

  7. [Effect of organic compounds on the degradation of nitrobenzene in aqueous solution by catalytic ozonation].

    Science.gov (United States)

    Zhao, Lei; Ma, Jun; Liu, Zheng-Qian; Sun, Zhi-Zhong; Hou, Yan-Jun

    2008-05-01

    We investigated the effects of organic compounds on the processes of ozonation alone and ceramic honeycomb-catalyzed ozonation for the degradation of nitrobenzene in aqueous solution, including formaldehyde, methanol, formic acid and dibutyl phthalate. The results indicated that degradation rate of ozonation alone and ceramic honeycomb-catalyzed ozonation decreased by 11.6% and 9.6% with the increase of the concentration of formaldehyde (0-12 mg x L(-1)). The degradation rates of the two processes both increased firstly and decreased subsequently with the increase of the concentration of methanol (0-16 mg x L(-1)). The degradation rate of ozonation alone reached the climax at the concentration of methanol 2 mg x L(-1), and that of ceramic honeycomb-catalyzed ozonation reached the culmination at the concentration of methanol 4 mg x L(-1) under the same experimental condition. With the increase of the concentration of formic acid (0-8 mg x L(-1)), the degradation rates also increased firstly and decreased subsequently, and those of ozonation alone and ceramic honeycomb-catalyzed ozonation reached the vertex, respectively, at the concentration of methanol 0.5 mg x L(-1) and 2 mg x L(-1). At the lower concentration, methanol and formic acid could accelerate the degradation of nitrobenzene, however, the reaction was retarded at higher concentrations of methanol and formic acid. The degradation rates of ozonation alone and ozonation/ceramic honeycomb both declined by 19.7% and 18.6% with the increase of the concentration of dibutyl phthalate (0-10 mg x L(-1)).

  8. Josephson effects in the junction formed by DIII-class topological and s-wave superconductors with an embedded quantum dot

    Science.gov (United States)

    Gao, Zhen; Wang, Xiao-Qi; Shan, Wan-Fei; Wu, Hai-Na; Gong, Wei-Jiang

    2016-01-01

    We investigate the Josephson effects in the junction formed by the indirect coupling between DIII-class topological and s-wave superconductors via an embedded quantum dot. Due to the presence of two kinds of superconductors, three dot-superconductor coupling manners are considered, respectively. As a result, the Josephson current is found to oscillate in period 2π. More importantly, the presence of Majorana doublet in the DIII-class superconductor renders the current finite at the case of zero phase difference, with its sign determined by the fermion parity of such a junction. In addition, the dot-superconductor coupling plays a nontrivial role in adjusting the Josephson current. When the s-wave superconductor couples to the dot in the weak limit, the current direction will have an opportunity to reverse. It is believed that these results will be helpful for understanding the transport properties of the DIII-class superconductor. PMID:27324426

  9. Modulation of interlayer exchange coupling strength in magnetic tunnel junctions via strain effect

    Directory of Open Access Journals (Sweden)

    Xin Jiang

    2015-09-01

    Full Text Available Interlayer exchange coupling of two ferromagnetic electrodes separated by a thin MgO tunnel barrier is investigated using magneto-optical Kerr effect. We find that the coupling field can be reduced by more than 40% as the thickness of a top Ta capping layer increases from 0.5 to 1.2 nm. In contrast, a similar film stack with an additional 3 nm Ru capping layer displays no such dependence on Ta thickness. Transmission electron microscopy study shows that the oxidation of the exposed Ta capping layer induces changes in the crystalline structures of the underlying films, giving rise to the observed reduction of the interlayer coupling field.

  10. Consistent treatment of viscoelastic effects at junctions in one-dimensional blood flow models

    Science.gov (United States)

    Müller, Lucas O.; Leugering, Günter; Blanco, Pablo J.

    2016-06-01

    While the numerical discretization of one-dimensional blood flow models for vessels with viscoelastic wall properties is widely established, there is still no clear approach on how to couple one-dimensional segments that compose a network of viscoelastic vessels. In particular for Voigt-type viscoelastic models, assumptions with regard to boundary conditions have to be made, which normally result in neglecting the viscoelastic effect at the edge of vessels. Here we propose a coupling strategy that takes advantage of a hyperbolic reformulation of the original model and the inherent information of the resulting system. We show that applying proper coupling conditions is fundamental for preserving the physical coherence and numerical accuracy of the solution in both academic and physiologically relevant cases.

  11. Long-Term Lunar Radiation Degradation Effects on Materials

    Science.gov (United States)

    Rojdev, Kristina; ORourke, Mary Jane; Koontz, Steve; Alred, John; Hill, Charles; Devivar, Rodrigo; Morera-Felix, Shakira; Atwell, William; Nutt, Steve; Sabbann, Leslie

    2010-01-01

    The National Aeronautics and Space Administration (NASA) is focused on developing technologies for extending human presence beyond low Earth orbit. These technologies are to advance the state-of-the-art and provide for longer duration missions outside the protection of Earth's magnetosphere. One technology of great interest for large structures is advanced composite materials, due to their weight and cost savings, enhanced radiation protection for the crew, and potential for performance improvements when compared with existing metals. However, these materials have not been characterized for the interplanetary space environment, and particularly the effects of high energy radiation, which is known to cause damage to polymeric materials. Therefore, a study focusing on a lunar habitation element was undertaken to investigate the integrity of potential structural composite materials after exposure to a long-term lunar radiation environment. An overview of the study results are presented, along with a discussion of recommended future work.

  12. New Photocatalysis for Effective Degradation of Organic Pollutants in Water

    Science.gov (United States)

    Zarei Chaleshtori, M.; Saupe, G. B.; Masoud, S.

    2009-12-01

    The presence of harmful compounds in water supplies and in the discharge of wastewater from chemical industries, power plants, and agricultural sources is a topic of global concern. The processes and technologies available at the present time for the treatment of polluted water are varied that include traditional water treatment processes such as biological, thermal and chemical treatment. All these water treatment processes, have limitations of their own and none is cost effective. Advanced oxidation processes have been proposed as an alternative for the treatment of this kind of wastewater. Heterogeneous photocatalysis has recently emerged as an efficient method for purifying water. TiO2 has generally been demonstrated to be the most active semiconductor material for decontamination water. One significant factor is the cost of separation TiO2, which is generally a powder having a very small particle size from the water after treatment by either sedimentation or ultrafiltration. The new photocatalyst, HTiNbO5, has been tested to determine whether its photocatalytic efficiency is good enough for use in photocatalytic water purification since it has high surface area and relatively large particle size. The larger particle sizes of the porous materials facilitate catalyst removal from a solution, after purification has taken place. It can be separated from water easily than TiO2, a significant technical improvement that might eliminate the tedious final filtration necessary with a slurry. These materials are characterized and tested as water decontamination photocatalysts. The new catalyst exhibited excellent catalytic activity, but with a strong pH dependence on the photo efficiency. These results suggest that elimination of the ion exchange character of the catalyst may greatly improve its performance at various pHs. This new research proposes to study the effects of a topotactic dehydration reaction on these new porous material catalysts.

  13. Effect of junction temperature on the large-signal properties of a 94 GHz silicon based double-drift region impact avalanche transit time device

    Institute of Scientific and Technical Information of China (English)

    Aritra Acharyya; Suranjana Banerjee; J.P.Banerjee

    2013-01-01

    The authors have developed a large-signal simulation technique extending an in-house small-signal simulation code for analyzing a 94 GHz double-drift region impact avalanche transit time device based on silicon with a non-sinusoidal voltage excitation and studied the effect of junction temperature between 300 and 550 K on the large-signal characteristics of the device for both continuous wave (CW) and pulsed modes of operation.Results show that the large-signal RF power output of the device in both CW and pulsed modes increases with the increase of voltage modulation factor up to 60%,but decreases sharply with further increase of voltage modulation factor for a particular junction temperature; while the same parameter increases with the increase of junction temperature for a particular voltage modulation factor.Heat sinks made of copper and type-ⅡA diamond are designed to carry out the steady-state and transient thermal analysis of the device operating in CW and pulsed modes respectively.Authors have adopted Olson's method to carry out the transient analysis of the device,which clearly establishes the superiority of type-ⅡA diamond over copper as the heat sink material of the device from the standpoint of the undesirable effect of frequency chirping due to thermal transients in the pulsed mode.

  14. Testing for a gap junction-mediated bystander effect in retinitis pigmentosa: secondary cone death is not altered by deletion of connexin36 from cones.

    Science.gov (United States)

    Kranz, Katharina; Paquet-Durand, François; Weiler, Reto; Janssen-Bienhold, Ulrike; Dedek, Karin

    2013-01-01

    Retinitis pigmentosa (RP) relates to a group of hereditary neurodegenerative diseases of the retina. On the cellular level, RP results in the primary death of rod photoreceptors, caused by rod-specific mutations, followed by a secondary degeneration of genetically normal cones. Different mechanisms may influence the spread of cell death from one photoreceptor type to the other. As one of these mechanisms a gap junction-mediated bystander effect was proposed, i.e., toxic molecules generated in dying rods and propagating through gap junctions induce the death of healthy cone photoreceptors. We investigated whether disruption of rod-cone coupling can prevent secondary cone death and reduce the spread of degeneration. We tested this hypothesis in two different mouse models for retinal degeneration (rhodopsin knockout and rd1) by crossbreeding them with connexin36-deficient mice as connexin36 represents the gap junction protein on the cone side and lack thereof most likely disrupts rod-cone coupling. Using immunohistochemistry, we compared the progress of cone degeneration between connexin36-deficient mouse mutants and their connexin36-expressing littermates at different ages and assessed the accompanied morphological changes during the onset (rhodopsin knockout) and later stages of secondary cone death (rd1 mutants). Connexin36-deficient mouse mutants showed the same time course of cone degeneration and the same morphological changes in second order neurons as their connexin36-expressing littermates. Thus, our results indicate that disruption of connexin36-mediated rod-cone coupling does not stop, delay or spatially restrict secondary cone degeneration and suggest that the gap junction-mediated bystander effect does not contribute to the progression of RP.

  15. Testing for a gap junction-mediated bystander effect in retinitis pigmentosa: secondary cone death is not altered by deletion of connexin36 from cones.

    Directory of Open Access Journals (Sweden)

    Katharina Kranz

    Full Text Available Retinitis pigmentosa (RP relates to a group of hereditary neurodegenerative diseases of the retina. On the cellular level, RP results in the primary death of rod photoreceptors, caused by rod-specific mutations, followed by a secondary degeneration of genetically normal cones. Different mechanisms may influence the spread of cell death from one photoreceptor type to the other. As one of these mechanisms a gap junction-mediated bystander effect was proposed, i.e., toxic molecules generated in dying rods and propagating through gap junctions induce the death of healthy cone photoreceptors. We investigated whether disruption of rod-cone coupling can prevent secondary cone death and reduce the spread of degeneration. We tested this hypothesis in two different mouse models for retinal degeneration (rhodopsin knockout and rd1 by crossbreeding them with connexin36-deficient mice as connexin36 represents the gap junction protein on the cone side and lack thereof most likely disrupts rod-cone coupling. Using immunohistochemistry, we compared the progress of cone degeneration between connexin36-deficient mouse mutants and their connexin36-expressing littermates at different ages and assessed the accompanied morphological changes during the onset (rhodopsin knockout and later stages of secondary cone death (rd1 mutants. Connexin36-deficient mouse mutants showed the same time course of cone degeneration and the same morphological changes in second order neurons as their connexin36-expressing littermates. Thus, our results indicate that disruption of connexin36-mediated rod-cone coupling does not stop, delay or spatially restrict secondary cone degeneration and suggest that the gap junction-mediated bystander effect does not contribute to the progression of RP.

  16. Possible anti-tumour-promoting activity of components in Japanese soybean fermented food, Natto: effect on gap junctional intercellular communication.

    Science.gov (United States)

    Takahashi, C; Kikuchi, N; Katou, N; Miki, T; Yanagida, F; Umeda, M

    1995-03-01

    In order to detect any protective agent against tumor formation, we examined the anti-tumor-promoting effect of a Japanese traditional soybean fermented food, Natto. Dye transfer was employed as an assay method. When fluorescent dye was microinjected into cultured BALB/3T3 cells, the dye was transformed into the neighboring cells through the gap junction. This dye transfer was blocked by the treatment with the tumor promoters 12-O-tetra-decanoylphorbol-13-acetate (TPA), a high concentration of NaCl and lithocholic acid (LCA). This reduction of the dye transfer by TPA treatment was not observed when the cells were pretreated with retinoic acid, an anti-tumor promoter. Thus, the recovery of the dye transfer in TPA-treated BALB/3T3 cells was proven to ge a good indicator for detecting some possible anti-tumor promoters. After extraction and fractionation of Natto, we obtained an active fraction (H1) which showed recovery of the dye transfer in TPA-treated cells. The fraction contained straight-chain saturated hydrocarbons. A comparison of the fraction and the authentic samples by GC analysis suggests that the H1 fraction contained straight-chain saturated hydrocarbons from around C30 to C32. Among these hydrocarbons, hentriacontane (C31) was found at the highest concentrations, and was shown to have the highest activity. Hentriacontane at a very low concentration of 0.65 ng/ml was shown to recover the dye transfer inhibited by the treatment with TPA as well as with NaCl and LCA.

  17. Effects of H pylori infection on gap-junctional intercellular communication and proliferation of gastric epithelial cells in vitro

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    AIM: To explore the effects of H pylori infection on gap-junctional intercellular communication (GJIC) and proliferation of gastric epithelial cells in vitro. METHODS: A human gastric epithelial cell line (SGC-7901) cultured on coverslips was exposed overnight to intact H pylori (CagA+ or CagA- strains) and sonicated extracts, respectively. GJIC between the cells was detected by fluorescence redistribution after photobleaching (FRAP) technique. Proliferation of SGC cells was determined by methylthiazolyl tetrazolium (MTT)assay.RESULTS: When compared with control in which cells were cultured with simple medium alone, both CagA+ and CagA- H pylori isolates could inhibit GJIC (CagA+:F = 57.98, P < 0.01; CagA-: F = 29.59, P < 0.01) and proliferation (CagA+: F = 42.65, P < 0.01; CagA-: F =58.14, P < 0.01) of SGC-7901 cells. Compared with CagA- strains, CagA+ H pylori more significantly downregulated GJIC of gastric cells (intact H pylori: t = 13.86,P < 0.01; sonicated extracts: t = 11.87, P < 0.01) and inhibited proliferation gastric cells to a lesser extent in vitro (intact H pylori: t = 3.06, P < 0.05; sonicated extracts: t = 3.94, P < 0.01).CONCLUSION: Compared with CagA- H pylori strains,CagA+ strains down-regulate GJIC of gastric epithelial cells more significantly and inhibit proliferation of gastric cells to a lesser extent in vitro. H pylori, especially CagA+ strains, may play an important role in gastric carcinogenesis.

  18. Tunneling electroresistance effect in ultrathin BiFeO3-based ferroelectric tunneling junctions

    Science.gov (United States)

    Yoong, Herng Yau; Wang, Han; Xiao, Juanxiu; Guo, Rui; Yang, Ping; Yang, Yi; Lim, Sze Ter; Wang, John; Venkatesan, T.; Chen, Jingsheng

    2016-12-01

    Tunneling electroresistance (TER) effect has been observed in high quality ultrathin BiFeO3 thin films. The growth quality of the ultrathin BiFeO3 films was confirmed using the synchrotron high resolution X-ray diffraction techniques as well as high-resolution transmission electron microscopy. Ferroelectric-based resistive switching behavior is observed down to 2 u.c. of BiFeO3 ultrathin film, which is way below the critical thickness of BiFeO3 thin films exhibiting ferroelectricity reported in the previous research works. Upon fitting mathematically using the direct tunneling model, it could be seen that there is an increase in the change in the average potential barrier height when the barrier thickness increases from 2 u.c. to 10 u.c., which also results in an increase in the TER ratio by one order of magnitude. These results are promising and pave the way for developing ultrathin BiFeO3 films to be adopted in the non-volatile memory applications.

  19. Is grazing exclusion effective in restoring vegetation in degraded alpine grasslands in Tibet, China?

    Science.gov (United States)

    Yan, Yan; Lu, Xuyang

    2015-01-01

    Overgrazing is considered one of the key disturbance factors that results in alpine grassland degradation in Tibet. Grazing exclusion by fencing has been widely used as an approach to restore degraded grasslands in Tibet since 2004. Is the grazing exclusion management strategy effective for the vegetation restoration of degraded alpine grasslands? Three alpine grassland types were selected in Tibet to investigate the effect of grazing exclusion on plant community structure and biomass. Our results showed that species biodiversity indicators, including the Pielou evenness index, the Shannon-Wiener diversity index, and the Simpson dominance index, did not significantly change under grazing exclusion conditions. In contrast, the total vegetation cover, the mean vegetation height of the community, and the aboveground biomass were significantly higher in the grazing exclusion grasslands than in the free grazed grasslands. These results indicated that grazing exclusion is an effective measure for maintaining community stability and improving aboveground vegetation growth in alpine grasslands. However, the statistical analysis showed that the growing season precipitation (GSP) plays a more important role than grazing exclusion in which influence on vegetation in alpine grasslands. In addition, because the results of the present study come from short term (6-8 years) grazing exclusion, it is still uncertain whether these improvements will be continuable if grazing exclusion is continuously implemented. Therefore, the assessments of the ecological effects of the grazing exclusion management strategy on degraded alpine grasslands in Tibet still need long term continued research.

  20. Effect of roastingo n ruminal degradation,in testinald igestibility and ...

    African Journals Online (AJOL)

    Effect of roastingo n ruminal degradation,in testinald igestibility and ... Journal Home > Vol 25, No 4 (1995) > ... R uminal proteind egradationa nd UDP-D were measuredw ith the in sltrzp olyestera ... Algeria (5); Benin (2); Botswana (3); Burkina Faso (3); Cameroon (8); Congo, Republic (1); Côte d'Ivoire (4); Egypt, Arab Rep.

  1. Modelling the effect of pH on the colour degradation of blanched broccoli

    NARCIS (Netherlands)

    Tijskens, L.M.M.; Barringer, S.A.; Biekman, E.S.A.

    2001-01-01

    In ready-to-eat salads, a low pH is often applied in the salad dressing. The effect of pH on the colour change of blanched-frozen-and-thawed broccoli was studied. Different acids were used to achieve the pH values in buffer solutions. A model on chlorophyll degradation in fruits and vegetables was

  2. Tibolone inhibits bone resorption without secondary positive effects on cartilage degradation

    Directory of Open Access Journals (Sweden)

    Byrjalsen I

    2008-11-01

    Full Text Available Abstract Background Osteoarthritis is associated with increased bone resorption and increased cartilage degradation in the subchondral bone and joint. The objective of the present study was to determine whether Tibolone, a synthetic steroid with estrogenic, androgenic, and progestogenic properties, would have similar dual actions on both bone and cartilage turnover, as reported previously with some SERMS and HRT. Methods This study was a secondary analysis of ninety-one healthy postmenopausal women aged 52–75 yrs entered a 2-yr double blind, randomized, placebo-controlled study of treatment with either 1.25 mg/day (n = 36, or 2.5 mg/day Tibolone (n = 35, or placebo (n = 20, (J Clin Endocrinol Metab. 1996 Jul;81(7:2419–22 Second void morning urine samples were collected at baseline, and at 3, 6, 12, and 24 months. Urine CrossLaps® ELISA (CTX-I and Urine CartiLaps® ELISA (CTX-II was investigated as markers of bone resorption and cartilage degradation, respectively. Results Tibolone significantly (P Conclusion These data suggest uncoupling of the bone and cartilage effects of the synthetic steroid, Tibolone. Bone resorption was significantly decreased, whereas cartilage degradation was unchanged. These effects are in contrast to those observed some SERMs with effects on both bone and cartilage degradation. These effects may in part be described by the complicated pharmacology of Tibolone on testosterone, estrogen and progesterone receptors.

  3. Is grazing exclusion effective in restoring vegetation in degraded alpine grasslands in Tibet, China?

    Directory of Open Access Journals (Sweden)

    Yan Yan

    2015-06-01

    Full Text Available Overgrazing is considered one of the key disturbance factors that results in alpine grassland degradation in Tibet. Grazing exclusion by fencing has been widely used as an approach to restore degraded grasslands in Tibet since 2004. Is the grazing exclusion management strategy effective for the vegetation restoration of degraded alpine grasslands? Three alpine grassland types were selected in Tibet to investigate the effect of grazing exclusion on plant community structure and biomass. Our results showed that species biodiversity indicators, including the Pielou evenness index, the Shannon–Wiener diversity index, and the Simpson dominance index, did not significantly change under grazing exclusion conditions. In contrast, the total vegetation cover, the mean vegetation height of the community, and the aboveground biomass were significantly higher in the grazing exclusion grasslands than in the free grazed grasslands. These results indicated that grazing exclusion is an effective measure for maintaining community stability and improving aboveground vegetation growth in alpine grasslands. However, the statistical analysis showed that the growing season precipitation (GSP plays a more important role than grazing exclusion in which influence on vegetation in alpine grasslands. In addition, because the results of the present study come from short term (6–8 years grazing exclusion, it is still uncertain whether these improvements will be continuable if grazing exclusion is continuously implemented. Therefore, the assessments of the ecological effects of the grazing exclusion management strategy on degraded alpine grasslands in Tibet still need long term continued research.

  4. Effect of humic acids on electricity generation integrated with xylose degradation in microbial fuel cells

    DEFF Research Database (Denmark)

    Huang, Liping; Angelidaki, Irini

    2008-01-01

    Pentose and humic acids (HA) are the main components of hydrolysates, the liquid fraction produced during thermohydrolysis of lignocellulosic material. Electricity generation integrated with xylose (typical pentose) degradation as well as the effect of HA on electricity production in microbial fu...

  5. Effect of radiation-degraded chitosan on growth promotion of flower plant in tissue culture

    Energy Technology Data Exchange (ETDEWEB)

    Luan, Le Quang; Ha, Vo Thi Thu; Hai, Le; Hien, Nguyen Quoc [Vietnam Atomic Energy Commission, Nuclear Research Institute, Dalat (Viet Nam); Nagasawa, Naotsugu; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2002-03-01

    Radiation is a useful tool for degradation of polysaccharides, such as starch, carrageenan, alginate and chitin/chitosan. The viscosity molecular weight (Mw) of chitosan with 80% degree of deacetylation was reduced to 1.5 x 10{sup 5} by irradiation of 50kGy in solid phase. The solution of 10% of chitosan with Mw ca. 15 x 10{sup 5} was then irradiated at doses ranging 10-250kGy for further degradation and the products were supplemented into cultural media for testing of plant growth promotion effect. The results indicated that irradiated chitosan showed a strong growth-promotion effect on the increase of the length of shoot, the length of root and fresh biomass for flower plants namely Limonium latifolium, Eustoma grandiflorum and Chrysanthemum morifolium in tissue culture. The growth-promotion effect was obtained by the treatments with 50ppm of chitosan irradiated at the doses of 75-100kGy in 10% solution. The suitable concentrations of chitosan irradiated at 100kGy are ca. 100ppm for C. morifolium, 30ppm for E. grandiflorum and 40ppm for L. latifolium. In addition, our study also indicated that the survival ratio of transferred flower plantlets treated with irradiated chitosan was improved after acclimatizing for 30 days in the greenhouse. Accordingly, it is concluded that degraded chitosan obtained by radiation degradation technique is effective as a plant growth promoter as well as irradiated alginate. (author)

  6. Degradation by synergistic effect in synthetic insulators; Degradacion por efecto sinergico en aisladores sinteticos

    Energy Technology Data Exchange (ETDEWEB)

    Garza M, Anibal; Montesinos S, Jose I. [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1991-12-31

    A study is presented of the main degradation phenomena experimented by synthetic insulators and the simultaneous participation of such phenomena to propitiate a synergistic effect. [Espanol] Se presenta un estudio de los principales fenomenos de degradacion que sufren los aisladores sinteticos y la participacion simultanea de dichos fenomenos para propiciar un efecto sinergico.

  7. Driver performance-based assessment of thermal display degradation effects

    Science.gov (United States)

    Ruffner, John W.; Massimi, Michael S.; Choi, Yoon S.; Ferrett, Donald A.

    1998-07-01

    The Driver's Vision Enhancer (DVE) is a thermal sensor and display combination currently being procured for use in U.S. Army combat and tactical wheeled vehicles. During the DVE production process, a given number of sensor or display pixels may either vary from the desired luminance values (nonuniform) or be inactive (nonresponsive). The amount and distribution of pixel luminance nonuniformity (NU) and nonresponsivity (NR) allowable in production DVEs is a significant cost factor. No driver performance-based criteria exist for determining the maximum amount of allowable NU and NR. For safety reasons, these characteristics are specified conservatively. This paper describes an experiment to assess the effects of different levels of display NU and NR on Army drivers' ability to identify scene features and obstacles using a simulated DVE display and videotaped driving scenarios. Baseline, NU, and NR display conditions were simulated using real-time image processing techniques and a computer graphics workstation. The results indicate that there is a small, but statistically insignificant decrease in identification performance with the NU conditions tested. The pattern of the performance-based results is consistent with drivers' subjective assessments of display adequacy. The implications of the results for specifying NU and NR criteria for the DVE display are discussed.

  8. Gap-junction coupling and ATP-sensitive potassium channels in human β -cell clusters: Effects on emergent dynamics

    Science.gov (United States)

    Loppini, A.; Pedersen, M. G.; Braun, M.; Filippi, S.

    2017-09-01

    The importance of gap-junction coupling between β cells in pancreatic islets is well established in mouse. Such ultrastructural connections synchronize cellular activity, confine biological heterogeneity, and enhance insulin pulsatility. Dysfunction of coupling has been associated with diabetes and altered β -cell function. However, the role of gap junctions between human β cells is still largely unexplored. By using patch-clamp recordings of β cells from human donors, we previously estimated electrical properties of these channels by mathematical modeling of pairs of human β cells. In this work we revise our estimate by modeling triplet configurations and larger heterogeneous clusters. We find that a coupling conductance in the range 0.005 -0.020 nS/pF can reproduce experiments in almost all the simulated arrangements. We finally explore the consequence of gap-junction coupling of this magnitude between β cells with mutant variants of the ATP-sensitive potassium channels involved in some metabolic disorders and diabetic conditions, translating studies performed on rodents to the human case. Our results are finally discussed from the perspective of therapeutic strategies. In summary, modeling of more realistic clusters with more than two β cells slightly lowers our previous estimate of gap-junction conductance and gives rise to patterns that more closely resemble experimental traces.

  9. Effect Factors of Benzene Adsorption and Degradation by Nano-TiO2 Immobilized on Diatomite

    Directory of Open Access Journals (Sweden)

    Lijun Cheng

    2012-01-01

    Full Text Available Difference between adsorption of benzene by diatomite and nano-TiO2 immobilized on diatomite was investigated. And effects of temperature, light intensity, relative humidity, and initial benzene concentration on adsorption and degradation of benzene by nano-TiO2 immobilized on diatomite were also studied. The experimental results showed that when initial benzene concentration was 2.2×10−3 mg L−1, it could be degraded to below safe concentration (1.1×10−4 mg L−1 after 50 h when temperature was 20°C, but it just needed 30 h at 35°C. When light intensity was 6750 Lx, it needed 30 h for benzene to be degraded to below safe concentration, but benzene could barely be degraded without light. When relative humidity was 50%, benzene could be degraded to 1.0×10−4 mg L−1 after 30 h, while its concentration could be reduced to 7.0×10−5 mg L−1 at the relative humidity of 80%.

  10. Effect of Co-substrate on Degradation of Benzothiazole in MEC

    Institute of Scientific and Technical Information of China (English)

    Huandi Huang; Jie Ding; Xianshu Liu; Guojun Xie; Dihui Song

    2016-01-01

    Due to its persistence and bio⁃toxicity, benzothiazole ( BTH ) cannot be biodegraded efficiently. Recent work has shown that removal rates of biorefractory organics can be enhanced by the addition of co⁃substrates. In this work, ethanol, acetate, propionate and butyrate were added as co⁃substrates in order to promote the degradation of BTH in microbial electrolysis cell (MEC). By probing the changes in degradation rates of BTH in the presence of different co⁃substrates, it was observed that all the four co⁃substrates can enhance the BTH degradation in MEC, both the efficiency ( EBTH ) and the rate ( RBTH ) . It was also found that acetate is more effective than others, which made the degradation efficiency of BTH up to 90% with acetate⁃C at 350 mg/L ( measuring by the carbon content of co⁃substrate, the same below) ,within 6 h and the degradation rate of BTH arrived 0.001 2/( mg·h) . The microbacteria in MEC have also been influenced by different co⁃substrates. This metabolism of the co⁃substrates enables the microbacteria on anode to generate ATP and thus grow to ensure the microbacteria activity. Therefore, this work showed that the addition of co⁃substrates such as acetate can be a novel and efficient approach for improving the elimination of BTH from wastewaters by MEC system.

  11. Promotive effect of pyridine on indole degradation by activated sludge under anoxic conditions

    Institute of Scientific and Technical Information of China (English)

    LI Yongmei; LI Wenshu; GU Guowei

    2007-01-01

    Batch experiments were carried out to investigate the promotive effect ofpyridine on indole degradation under denitrifying conditions.The seed sludge was obtained from a local coal-coking wastewater treatment facility and was acclimated in the laboratory.Indole and pyridine were supplemented to the synthetic wastewater at different ratios.The optimum ratio of chemical oxygen demand (COD) to nitrate (C/N) was 8.4-8.9 for both denitrification and indole and pyridine degradation.At a temperature of 28℃ and pH of 7.0-7.5,the nitrate reductase activity (NRA) was in the best state.The addition of pyridine could promote NRA and the degradation of indole.When the initial concentration of indole was 150 mg/L,the concentration ratio of indole to pyridine was in the range of 1-10.Under optimum C/N conditions,the degradation of indole could be described with pseudo-zero-order kinetics.There was no accumulation of nitrite during the reaction.When the concentration ratio of pyridine to indole was less than 0.25 with an increase in the pyridine proportion,there were more significant augment rates for NRA and the degradation of indole than the situation when the concentration ratio was more than 0.25.

  12. Mathematical modeling of photoinitiated coating degradation: Effects of coating glass transition temperature and light stabilizers

    DEFF Research Database (Denmark)

    Kiil, Søren; G.de With, R.A.T.M.Van Benthem

    2013-01-01

    A mathematical model, describing coating degradation mechanisms of thermoset coatings exposed to ultraviolet radiation and humidity at constant temperature, was extended to simulate the behavior of a coating with a low glass transition temperature. The effects of adding light stabilizers (a UV...... absorber and a radical scavenger) to the coating were also explored. The extended model includes photoinitiated oxidation reactions, intrafilm oxygen permeability, water absorption and diffusion, reduction of crosslink density, absorption of ultraviolet radiation, a radical scavenger reaction......, and simulates the transient development of an oxidation zone. Simulations are in good agreement with experimental data for a fast degrading epoxy-amine coating with a glass transition temperature of −50°C. It was found that the degradation rate of the non-stabilized coating was influenced significantly...

  13. Gamma ray radiation ({sup 60}Co) effect on the degradation of synthetic pesticides

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyoung Youl; Lee, Young Keun [Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

    2010-06-15

    Gamma irradiation effects on the synthetic pesticide degradation were analysed. Ten ppm of standard solutions (triflumizole, iprodione, chlorothalonil, chlorfenapyr and fipronil) was prepared and irradiated at the doses of 5, 10, 15, and 20 kGy (dose rate: 920 Gy hr{sup -1}, AECL) and analysed by HPLC. The degradation rates of chlorothalonil and iprodione at 20 kGy increased by 95% and 25% compared with the control, respectively. The general degradation rate of four pesticides except chlorfenapyr increased proportionally as a function of radiation dose. It suggested that function of residual pesticides in crop be lost by gamma ray radiation and irradiation be useful for the quality evaluation of agricultural products.

  14. Effect of anionic surfactants on the process of Fenton degradation of methyl orange.

    Science.gov (United States)

    Yang, C W; Wang, D

    2009-01-01

    Fenton process has been shown to be very successful to remove dyes from water. However, the influence of other constituents in dyeing industry wastewater, such as Sodium Dodecyl Sulphate (SDS) surfactants, has not been investigated. In this study, the effect of SDS surfactant on the kinetics of Methyl Orange degradation undergoing Fenton process was investigated. Results show that Methyl Orange degradation rate decreased as SDS concentration increased, which was attributed to the consumption of hydroxyl radicals (OH) by surfactants and the formation of Methyl Orange-SDS complex. No evidence was found that the Methyl Orange degradation pathway was affected by the presence of SDS. The kinetics modelling indicates the reaction was the first-order reaction to Methyl Orange.

  15. Degradation of soil-sorbed trichloroethylene by stabilized zero valent iron nanoparticles: Effects of sorption, surfactants, and natural organic matter

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Man [Auburn University, Auburn, Alabama; He, Feng [ORNL; Zhao, Dongye [Auburn University, Auburn, Alabama; Hao, Xiaodi [Beijing University of Civil Engineering and Architecture

    2011-01-01

    Zero valent iron (ZVI) nanoparticles have been studied extensively for degradation of chlorinated solvents in the aqueous phase, and have been tested for in-situ remediation of contaminated soil and groundwater. However, little is known about its effectiveness for degrading soil-sorbed contaminants. This work studied reductive dechlorination of trichloroethylene (TCE) sorbed in two model soils (a potting soil and Smith Farm soil) using carboxymethyl cellulose (CMC) stabilized Fe-Pd bimetallic nanoparticles. Effects of sorption, surfactants and dissolved organic matter (DOC) were determined through batch kinetic experiments. While the nanoparticles can effectively degrade soil-sorbed TCE, the TCE degradation rate was strongly limited by desorption kinetics, especially for the potting soil which has a higher organic matter content of 8.2%. Under otherwise identical conditions, {approx}44% of TCE sorbed in the potting soil was degraded in 30 h, compared to {approx}82% for Smith Farm soil (organic matter content = 0.7%). DOC from the potting soil was found to inhibit TCE degradation. The presence of the extracted SOM at 40 ppm and 350 ppm as TOC reduced the degradation rate by 34% and 67%, respectively. Four prototype surfactants were tested for their effects on TCE desorption and degradation rates, including two anionic surfactants known as SDS (sodium dodecyl sulfate) and SDBS (sodium dodecyl benzene sulfonate), a cationic surfactant hexadecyltrimethylammonium (HDTMA) bromide, and a non-ionic surfactant Tween 80. All four surfactants were observed to enhance TCE desorption at concentrations below or above the critical micelle concentration (cmc), with the anionic surfactant SDS being most effective. Based on the pseudo-first-order reaction rate law, the presence of 1 x cmc SDS increased the reaction rate by a factor of 2.5 when the nanoparticles were used for degrading TCE in a water solution. SDS was effective for enhancing degradation of TCE sorbed in Smith Farm

  16. The effect of a gap-junction blocker, carbenoxolone, on ischemic brain injury and cortical spreading depression.

    Science.gov (United States)

    Tamura, K; Alessandri, B; Heimann, A; Kempski, O

    2011-10-27

    Cortical spreading depression (CSD) has been shown to cause secondary cell loss in experimental models of brain injury and in patients, and blocking of CSD is a potential neuroprotective strategy. Here we tested the hypothesis that gap junctions affect CSD under physiological conditions as well as infarct development in a rat two-vein occlusion model suited to study pathophysiology of the penumbra (n = 71). We applied the gap junction blocker carbenoxolone (CBX) or saline intra-ventricularly. Interestingly, CBX temporarily increased systemic blood pressure and cortical blood flow (41% and 53%, 15 min after 250 μg CBX). We induced CSD with cortical microinjection of potassium chloride (KCl), counted how many spontaneous CSDs after CSD induction were elicited and measured the propagation velocity. After 250 μg CBX administration, significant 37.5 ± 6.5 additional CSDs were seen. CSD velocity increased significantly after 50 μg and 250 μg CBX. Occlusion of two adjacent cortical veins using Rose Bengal dye and fiberoptic illumination followed by 250 μg CBX or saline showed a significant more than doubling of infarct volumes 7 days after CBX. The current experiments provide evidence that CBX can accelerate the initiation and propagation of CSD suggesting opening of gap junctions is not required for CSD propagation. Blocking gap junctions worsens outcome from focal cerebral ischemia. Hence, measures intended to improve spatial buffering via astroglial gap junctions could have therapeutic potential in disease processes involving CSD. Copyright © 2011 IBRO. Published by Elsevier Ltd. All rights reserved.

  17. Thermoelectric effects of the single-spin state in the ferromagnetic-normal junction with artificial magnetic impurities

    Science.gov (United States)

    Xu, Li; Li, Zhi-Jian; Hou, Hai-Yan; Niu, Pengbin; Nie, Yi-Hang

    2016-10-01

    We theoretically analyze the thermoelectric properties of the single-spin state based on the resonant tunneling of electron in the ferromagnetic-normal junction with artificial magnetic impurities. The thermoelectric coefficients, such as electrical conductance G, thermal conductance K, thermopower S and effective figure of merit Y, have been calculated using the nonequilibrium Green function in the linear regime. It is found that the thermoelectric coefficients can achieve considerable values by adjusting key parameters of the hybrid mesoscopic structure, such as the level detuning, the interdot hopping coefficient, the external magnetic field and the angle θ. When the level detuning changes, the spectra of electrical conductance and thermal conductance exhibit the electronic Dicke-like effect in the low temperature. Two valleys of electrical conductance and thermal conductance are always located at the single-spin level of QD2 ({{\\varepsilon}2\\uparrow} and ~{{\\varepsilon}2\\downarrow} ), and can achieve the antiresonant point by adjusting the interdot hopping coefficient. Thermoelectric coefficients can achieve considerable values near valleys because the Wiedemann-Franz law is strongly violated. Thermopower S and effective figure of merit Y can get larger values in the vicinity of {{\\varepsilon}2\\uparrow} by adjusting key parameters of the hybrid mesoscopic structure, such as the level detuning, the interdot hopping coefficient and the polarization. But the thermoelectric effect is reversed by changing the angle θ. When the angle θ increases, S and Y are suppressed in the vicinity of {{\\varepsilon}2\\uparrow}, meanwhile, S and Y are enhanced in the vicinity of {{\\varepsilon}2\\downarrow}. {χ+}=\\cos \\fracθ{2}|\\uparrow >+\\sin \\fracθ{2}|\\downarrow > shows that an electron in the state {χ+} can virtually tunnel into the spin-up (or spin-down) state of the ferromagnet. The amplitude of electron tunneling is \\cos \\fracθ{2} (or \\sin \\fracθ{2

  18. Degradation of Metalaxyl and Mefenoxam and Effects on the Microbiological Properties of Tropical and Temperate Soils

    Directory of Open Access Journals (Sweden)

    Michael Spiteller

    2005-08-01

    Full Text Available The degradation of various formulations of the racemic mixture and the enantiomers (including mefenoxam of metalaxyl in typical soils from Germany and Cameroon in controlled incubation experiments was studied. The kinetics of the degradation or transformation was determined by means of reversed phase HPLC, while the enantiomeric ratios were measured by HPLC with a chiral Whelk O1 column. The dynamics of the quantitative changes in microbiological properties induced by the addition of these fungicides at their recommended field rates were determined in the soils during a 120-day incubation experiment. The degradation followed first-order kinetics (R²≥0.96. Higher metalaxyl acid metabolite concentrations were found in German than in Cameroonian soils. The enantiomers of the fungicide had different degradation rates in both soils, with half-lives ranging from 17 to 38 days. All forms of metalaxyl had lower degradation rates in the Cameroonian soil than in the German soil. The degradation of the R-enantiomer was much faster than the S-enantiomer in the German soil and slower than the S-enantiomer in the Cameroonian soil, suggesting that different microbial populations, which may be using different enzymes, have different degradation preferences. The type of soil significantly influenced the effect of these fungicides on the soil parameters studied. Incorporation of these fungicides resulted in a change in the ecophysiological status of the soil microbial community as expressed by microbial activities. The activity of phosphatases and ß-glucosidase, the mineralization and availability of N and most plant nutrients in soils were stimulated, whereas the activity of dehydrogenase and the availability of NO3-, were generally adversely affected. The soil NH4+, NO3-, and enzymes activities values in general did not correlate with the degradation of metalaxyl in both soils. However, the degradation of formulated and unformulated

  19. Degradation of metalaxyl and mefenoxam and effects on the microbiological properties of tropical and temperate soils.

    Science.gov (United States)

    Monkiedje, Adolphe; Spiteller, Michael

    2005-08-01

    The degradation of various formulations of the racemic mixture and the enantiomers (including mefenoxam) of metalaxyl in typical soils from Germany and Cameroon in controlled incubation experiments was studied. The kinetics of the degradation or transformation was determined by means of reversed phase HPLC, while the enantiomeric ratios were measured by HPLC with a chiral Whelk O1 column. The dynamics of the quantitative changes in microbiological properties induced by the addition of these fungicides at their recommended field rates were determined in the soils during a 120-day incubation experiment. The degradation followed first-order kinetics (R > or = 0.96). Higher metalaxyl acid metabolite concentrations were found in German than in Cameroonian soils. The enantiomers of the fungicide had different degradation rates in both soils, with half-lives ranging from 17 to 38 days. All forms of metalaxyl had lower degradation rates in the Cameroonian soil than in the German soil. The degradation of the R-enantiomer was much faster than the S-enantiomer in the German soil and slower than the S-enantiomer in the Cameroonian soil, suggesting that different microbial populations, which may be using different enzymes, have different degradation preferences. The type of soil significantly influenced the effect of these fungicides on the soil parameters studied. Incorporation of these fungicides resulted in a change in the ecophysiological status of the soil microbial community as expressed by microbial activities. The activity of phosphatases and fl-glucosidase, the mineralization and availability of N and most plant nutrients in soils were stimulated, whereas the activity of dehydrogenase and the availability of NO3-, were generally adversely affected. The soil NH4+, NO3-, and enzymes activities values in general did not correlate with the degradation of metalaxyl in both soils. However, the degradation of formulated and unformulated metalaxyl was positively correlated to

  20. Effect of dairy manure rate and the stabilization time of amended soils on atrazine degradation.

    Science.gov (United States)

    Aguilera, Paula; Briceño, Gabriela; Candia, Maribel; Mora, Maria de la Luz; Demanet, Rolando; Palma, Graciela

    2009-10-01

    The application rate of liquid cow manure (LCM) in the field and the stabilization time of amended soils before application of pre-plant herbicides are factors that determine their efficiency. This study includes evaluation of residual atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) in soil and amended soils with equivalent rate of 100,000; 200,000; and 300,000 L ha(-1) of LCM and the effect of pre-incubation time of amended soils on atrazine degradation. The study was carried out under controlled conditions using an Andisol with previous historical application of atrazine. The respiratory activity and fluorescein diacetate (FDA) studies indicated that the time necessary for stabilization of amended soils is over 20-30 d. During the measurement of respiratory and FDA activity, no significant differences were observed when atrazine was applied. The half-life of atrazine ranged from 5 to 8d and the relative distribution of degradation products seem to be affected by the application of LCM. The pre-incubation time of amended soil and LCM dose would not affect atrazine degradation rate, when the soil has a history of herbicide application. However, repeated applications of LCM in a long period of time could change the soil pH and increase the content of dissolved organic carbon (DOC) which could further contribute to a faster degradation of atrazine. Both effects would reduce the effectiveness of atrazine in weed control.

  1. The effect of liver esterases and temperature on remifentanil degradation in vitro.

    Science.gov (United States)

    Piazza, Ornella; Cascone, Sara; Sessa, Linda; De Robertis, Edoardo; Lamberti, Gaetano

    2016-08-20

    Remifentanil is a potent opioid metabolized by serum and tissue esterases; it is routinely administered to patients with liver failure as anaesthetic and analgo-sedative without variation in doses, even if prolonged clinical effects and respiratory depression have been observed in these patients. The aim of this study was to determine remifentanil enzymatic degradation kinetics bearing in mind the effect of liver esterases in order to trace a more accurate pharmacokinetic profile of the drug. Solution samples were taken over time and analysed to measure remifentanil concentration by HPLC. We reproduced the physiological settings, varying temperature and pH in vitro and evaluated the kinetics of degradation of remifentanil in the presence of Rhizopus Oryzae esterases, equine liver esterases and porcine liver esterases. Remifentanil kinetics of degradation was accelerated by porcine liver esterases. Remifentanil in vitro half-life decreases with increasing temperatures in the presence of porcine liver esterases. A drug model simulation considering the effect of temperature in the presence of liver esterases was developed. Remifentanil in vitro half-life decreases with increasing temperatures when porcine liver esterases are present. In this paper we propose a model for describing remifentanil degradation kinetics at various temperatures.

  2. Radiation-induced degradation of sodium alginate and its plant growth promotion effect

    Directory of Open Access Journals (Sweden)

    H.L. Abd El-Mohdy

    2017-02-01

    Full Text Available Alginate was irradiated as a solid with 60Co gamma rays in the dose range of 20–100 kGy to investigate the effect of radiation on alginates. One of the principle factors for reducing the cost is achieving the degradation at low irradiation doses which occurs with addition of chemical initiator to NaAlg during irradiation process that leads to a synergistic effect, which remarkably increases the degradation efficiency of alginate. The factors affecting the degradation process such as irradiation dose and potassium per-sulfate (KPS addition were studied. The average molecular weight of the irradiated alginate was investigated in detail by using several complementary techniques such as chromatography and viscometry. The lowest molecular weight of alginate resulted at 100 kGy and added KPS, whereas the highest one at 20 kGy in absence of KPS. Characterization of the oligoalginates obtained by radiation degradation was performed by FT-IR and UV–vis spectroscopy, XRD and TGA. The effect of water-soluble radiation-induced alginate fractions on the growth promotion of Faba bean plant was studied. The highest plant growth and seed yield compared with control occurred for plants sprayed with low molecular weight NaAlg fractions (treated with 100 kGy and added KPS.

  3. On Chip Bioelectric Impedance Spectroscopy Reveals the Effect of P-Glycoprotein Efflux Pumps on the Paracellular Impedance of Tight Junctions at the Blood-Brain Barrier.

    Science.gov (United States)

    Kraya, Ramsey; Komin, Alexander; Searson, Peter

    2016-10-01

    Bioelectric impedance spectroscopy was used to elucidate the influence of P-gp efflux pumps on the kinetics of tight junction down-regulation in confluent monolayers of Madine Darby Canine Kidney Epithelial Cells (MDCK) following administration of phenylarsine oxide (PAO), a molecule that inhibits protein tyrosine phosphatases (PTP) and induces matrix metalloproteinase activity. Matrix metalloproteinases (MMPs) and phosphatase inhibitors induce modification of occludin tight junction proteins critical for the proper function of the blood-brain barrier. The addition of PAO to MDCKII cell lines resulted in a dramatic decrease in monolayer resistance. In contrast, MDCKII-MDR1 cells transfected with the MDR1 gene treated with PAO showed an initial decrease in monolayer resistance followed by a partial recovery and subsequent decrease. This resistance decay reversal was suppressed with the addition of the P-glycoprotein (P-gp) pump inhibitor elacridar, and is attributed to PAO efflux. These results illustrate impedance spectroscopy can be used to characterize the competing kinetics of efflux and down-regulation of tight junctions. In addition, the resistance decay reversal effect can be used to evaluate P-gp pump inhibitor efficacy.

  4. Effect of Gas- and Liquid-injection Methods on Formation of Bubble and Liquid Slug at Merging Micro T-junction

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jun Kyoung [Kyungnam Univ., Changwon (Korea, Republic of); Lee, Chi Young [Pukyong Nat’l Univ., Busan (Korea, Republic of)

    2016-04-15

    In the present experimental study, the effect of gas- and liquid-injected methods on the formation of bubble and liquid slug at the merging micro T-junction of a square microchannel with dimensions 600 μm × 600 μm was investigated. Nitrogen and water were used as test fluids. The superficial velocities of the liquid and gas were in the range of 0.05 - 1 m/s, and 0.1 - 1 m/s, respectively, where the Taylor flow was observed. The bubble length, liquid slug length, bubble velocity, and bubble generation frequency were measured by analyzing the images captured using a high-speed camera. Under similar inlet superficial velocity conditions, in the case of gas injection to the main channel at the merging T-junction (T{sub g}as-liquid), the lengths of the bubble and liquid slug were longer, and the bubble generation frequency was lower than in the case of liquid injection to the main channel at the merging T-junction (T{sub l}iquid-gas). On the other hand, in both cases, the bubble velocity was almost the same. The previous correlation proposed using experimental data for T{sub l}iquid-gas had predicted the present experimental data of bubble length, bubble velocity, liquid slug length, and bubble generation frequency for T{sub g}as-liquid to be ~24%, ~9%, ~39%, ~55%, respectively.

  5. Effective degradation of organic water pollutants by atmospheric non-thermal plasma torch and analysis of degradation process.

    Science.gov (United States)

    Bansode, Avinash S; More, Supriya E; Siddiqui, Ejaz Ahmad; Satpute, Shruti; Ahmad, Absar; Bhoraskar, Sudha V; Mathe, Vikas L

    2017-01-01

    The paper reports the use of atmospheric non-thermal plasma torch as a catalyst for degradation of various organic pollutants dissolved in water. A flow of He mixed with air was used to produce the dielectric barrier discharge (DBD), at the tip of the torch, using pulsed electric excitation at 12 kV. The torch, operated at a power of 750 mW/mm(2), was seen to completely degrade the aqueous solutions of the pollutants namely methylene blue (MB), methyl orange (MO) and rhodamine-B (RB), at around 10(-4) M concentrations, the concentration of polluants is one order higher than of routinely used heterogeneous photocatalytic reactions, within 10 min of irradiation time at room temperature. UV Visible spectra of the organic dye molecules, monitored after different intervals of plasma-irradiation, ranging between 1 and 10 min, have been used as tools to quantify their sequential degradation. Further, instead of using He, only air was used to form plasma plume and used for degradation of organic dye which follow similar trend as that of He plasma. Further, Liquid Chromatography Mass Spectroscopy (LCMS) technique has been used to understand degradation pathway of methylene blue (MB) as a representative case. Total organic carbon (TOC) measurements indicates significant decrease in its content as a function of duration of plasma exposure onto methylene blue as a representative case. Toxicity studies were carried out onto Gram negative Escherichia coli. This indicated that methylene blue, without plasma treatment, shows growth inhibition, whereas with plasma treatment no inhibition was observed.

  6. Proximity effect among cellulose-degrading enzymes displayed on the Saccharomyces cerevisiae cell surface.

    Science.gov (United States)

    Bae, Jungu; Kuroda, Kouichi; Ueda, Mitsuyoshi

    2015-01-01

    Proximity effect is a form of synergistic effect exhibited when cellulases work within a short distance from each other, and this effect can be a key factor in enhancing saccharification efficiency. In this study, we evaluated the proximity effect between 3 cellulose-degrading enzymes displayed on the Saccharomyces cerevisiae cell surface, that is, endoglucanase, cellobiohydrolase, and β-glucosidase. We constructed 2 kinds of arming yeasts through genome integration: ALL-yeast, which simultaneously displayed the 3 cellulases (thus, the different cellulases were near each other), and MIX-yeast, a mixture of 3 kinds of single-cellulase-displaying yeasts (the cellulases were far apart). The cellulases were tagged with a fluorescence protein or polypeptide to visualize and quantify their display. To evaluate the proximity effect, we compared the activities of ALL-yeast and MIX-yeast with respect to degrading phosphoric acid-swollen cellulose after adjusting for the cellulase amounts. ALL-yeast exhibited 1.25-fold or 2.22-fold higher activity than MIX-yeast did at a yeast concentration equal to the yeast cell number in 1 ml of yeast suspension with an optical density (OD) at 600 nm of 10 (OD10) or OD0.1. At OD0.1, the distance between the 3 cellulases was greater than that at OD10 in MIX-yeast, but the distance remained the same in ALL-yeast; thus, the difference between the cellulose-degrading activities of ALL-yeast and MIX-yeast increased (to 2.22-fold) at OD0.1, which strongly supports the proximity effect between the displayed cellulases. A proximity effect was also observed for crystalline cellulose (Avicel). We expect the proximity effect to further increase when enzyme display efficiency is enhanced, which would further increase cellulose-degrading activity. This arming yeast technology can also be applied to examine proximity effects in other diverse fields.

  7. Planar Josephson tunnel junctions in a transverse magnetic field

    DEFF Research Database (Denmark)

    Monacoa, R.; Aarøe, Morten; Mygind, Jesper

    2007-01-01

    Traditionally, since the discovery of the Josephson effect in 1962, the magnetic diffraction pattern of planar Josephson tunnel junctions has been recorded with the field applied in the plane of the junction. Here we discuss the static junction properties in a transverse magnetic field where...... demagnetization effects imposed by the tunnel barrier and electrodes geometry are important. Measurements of the junction critical current versus magnetic field in planar Nb-based high-quality junctions with different geometry, size, and critical current density show that it is advantageous to use a transverse...

  8. Synergetic Effects of UV/Fe3+ Combined with Electrocatalysis for p-Nitrophenol Degradation

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Synergetic effects for p-nitrophenol degradation were observed in the combination of two-advanced oxidation processes,UV/Fe3+ and electrocatalysis.The enhancement of removal rate for p-nitrophenol and COD was around 123% and 278%,respectively.The possible contributions for the synergetic effects were the electrochemically regeneration of ferric ion and the role of the oxygen that formed on the anode.

  9. Effect of geometry of hydrodynamically cavitating device on degradation of orange-G.

    Science.gov (United States)

    Saharan, Virendra Kumar; Rizwani, Manav A; Malani, Aqeel A; Pandit, Aniruddha B

    2013-01-01

    In this research work, we have carried out geometric optimization of different cavitating devices using degradation of orange-G dye [OG] as a model pollutant. Three different cavitating devices viz. orifice plate, circular venturi and slit venturi were optimized and the degradation of orange-G dye was studied. The optimization of all three cavitating devices was done in terms of fluid inlet pressure to the cavitating devices and cavitation number. The effect of pH and initial concentration of the dye on the degradation rate was also studied. The geometry of cavitating device (flow cross sectional area, perimeter, shape, etc.) was found to be an important parameter in getting the maximum cavitational effect using hydrodynamic cavitation. The cavitational yield of all three cavitating devices were compared on the basis of mg of total organic carbon (TOC) reduction per unit energy supplied. The slit venturi gives almost 50% higher degradation rate and cavitational yield among all three cavitating devices studied for the same amount of energy supplied.

  10. Strain-Dependent Effect of Macroautophagy on Abnormally Folded Prion Protein Degradation in Infected Neuronal Cells.

    Directory of Open Access Journals (Sweden)

    Daisuke Ishibashi

    Full Text Available Prion diseases are neurodegenerative disorders caused by the accumulation of abnormal prion protein (PrPSc in the central nervous system. With the aim of elucidating the mechanism underlying the accumulation and degradation of PrPSc, we investigated the role of autophagy in its degradation, using cultured cells stably infected with distinct prion strains. The effects of pharmacological compounds that inhibit or stimulate the cellular signal transduction pathways that mediate autophagy during PrPSc degradation were evaluated. The accumulation of PrPSc in cells persistently infected with the prion strain Fukuoka-1 (FK, derived from a patient with Gerstmann-Sträussler-Scheinker syndrome, was significantly increased in cultures treated with the macroautophagy inhibitor 3-methyladenine (3MA but substantially reduced in those treated with the macroautophagy inducer rapamycin. The decrease in FK-derived PrPSc levels was mediated, at least in part, by the phosphatidylinositol 3-kinase/MEK signalling pathway. By contrast, neither rapamycin nor 3MA had any apparently effect on PrPSc from either the 22L or the Chandler strain, indicating that the degradation of PrPSc in host cells might be strain-dependent.

  11. Revaluating US Land Ownership and Management in Order to Effectively Combat Soil Degradation

    Science.gov (United States)

    Drohan, Patrick

    2017-04-01

    Land privatization has resulted throughout history in: a variety of governance types; wealth imbalances; fluctuating degrees of food production; industrialization; and the privatization of intellectual ideas/property. USA government strategies to combat soil degradation have in large been reactive and driven by land privatization and the entrepreneurial nature of the US economy, especially agriculture. This has led to boom and bust cycles of agriculture and soil resilience. Further straining the capability to combat soil degradation are weaknesses in land management legislation due to separation of federal and state law and unfunded mandates. Last, the sheer size of the United States may be its greatest weakness in effectively developing a coherent national soil degradation policy. The recent failure of the European Soil Directive emphasizes the continual struggle between land privatization, food production, and the generation of wealth. We suggest several new strategies to combat USA soil degradation based on existing and new land management schemes, which have the potential to more effectively buffer the unpredictable future of increasing population and climate change.

  12. Magnetic tunnel junctions (MTJs)

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    We review the giant tunnel magnetoresistance (TMR) in ferromagnetic-insulator-ferromagnetic junctions discovered in recent years, which is the magnetoresistance (MR) associated with the spin-dependent tunneling between two ferromagnetic metal films separated by an insulating thin tunnel barrier. The theoretical and experimental results including junction conductance, magnetoresistance and their temperature and bias dependences are described.

  13. Stacked Josephson Junctions

    DEFF Research Database (Denmark)

    Madsen, Søren Find; Pedersen, Niels Falsig; Christiansen, Peter Leth

    2010-01-01

    Long Josephson junctions have for some time been considered as a source of THz radiation. Solitons moving coherently in the junctions is a possible source for this radiation. Analytical computations of the bunched state and bunching-inducing methods are reviewed. Experiments showing THz radiation...

  14. Effectiveness of Ultrasound and Ultraviolet Irradiation onDegradation of Carbaryl from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    M Khoobdel

    2010-06-01

    Full Text Available Background: Carbaryl (1-naphthyl-N-methyl carbamate is a chemical in the carbamate family used chiefly as an insecticide. It is a cholinesterase inhibitor and is toxic to humans and classified as a likely human carcinogen. In the present study, the degradation of the carbaryl pesticide was investigated in the laboratory synthetic samples of tap water, in the effect of sonolysis and photolysis processes.Methods: This study was conducted during 2006-7 in Chemistry and Biochemistry of Pesticides Laboratory in Tehran University of Medical Sciences (TUMS in Iran. The carbaryl (80% was used for preparing samples. First concentration of all samples were 4 mg/l. Sonochemical examinations in ultrasound reactor was done in two 35, 130 Hz, and 100 w, and three time. Photolysis examinations has done in the effect of 400 w lamp and moderate pressure and 6 time, then the amount of pesticide in the samples has been measured by the High Performance Thin Layer Chromatography (HPTLC method.Results: The highest degradation in photolysis process after 1 hour in the 35 KHz was 35%, and in the 130 KHz was 63%. Degradation of carbaryl at 130 KHz is higher than 35 KHz at the same time. Carbaryl elimination was increased by arise frequency and exposure time. After 8 min in photolysis, 100% omitting has been showed.Conclusion: Degradation of carbaryl in high frequency ultrasound wavelength was more than low frequency. Degradation of carbaryl in water, combination of high frequency ultrasound wave length and UV irradiation was considerably more effective than ultrasound or ultraviolet irradiation alone.

  15. Electrical-field and spin-transfer torque effects in CoFeB/MgO-based perpendicular magnetic tunnel junction

    Directory of Open Access Journals (Sweden)

    Chikako Yoshida

    2016-05-01

    Full Text Available The electric-field (E dependence of the magnetoresistance (RH loops for top-pinned perpendicular CoFeB/MgO-based magnetic tunnel junctions (MTJs in the presence of a spin-transfer torque (STT-current was measured. The E effects were distinguished from the STT-current effects using a micromagnetic simulation. The coercive field (Hc decreased and the RH loop shifted as both the positive and negative bias E increased owing to the STT current. Furthermore, E-assisted switching for an MTJ with a diameter of 20 nm, which exhibited a nearly coherent magnetization reversal, was demonstrated using micromagnetic simulation.

  16. Electrical-field and spin-transfer torque effects in CoFeB/MgO-based perpendicular magnetic tunnel junction

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Chikako, E-mail: cyoshida@jp.fujitsu.com; Noshiro, Hideyuki; Yamazaki, Yuichi; Sugii, Toshihiro [Fujitsu limited, 10-1 Morinosato-Wakamiya, Atsugi, Kanagawa, 243-0197 (Japan); Furuya, Atsushi; Ataka, Tadashi; Tanaka, Tomohiro; Uehara, Yuji [Fujitsu limited, 4-1-1 Kamikodanaka, Nakahara-ku, Kawasaki, Kanagawa, 211-8588 (Japan)

    2016-05-15

    The electric-field (E) dependence of the magnetoresistance (RH) loops for top-pinned perpendicular CoFeB/MgO-based magnetic tunnel junctions (MTJs) in the presence of a spin-transfer torque (STT)-current was measured. The E effects were distinguished from the STT-current effects using a micromagnetic simulation. The coercive field (H{sub c}) decreased and the RH loop shifted as both the positive and negative bias E increased owing to the STT current. Furthermore, E-assisted switching for an MTJ with a diameter of 20 nm, which exhibited a nearly coherent magnetization reversal, was demonstrated using micromagnetic simulation.

  17. Preparation and photoelectric property of TiO{sub 2} nanoparticles with controllable phase junctions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hongmei [School of Environmental Science and Engineering, Tianjin University, Tianjin 300072 (China); Tan, Xin [School of Science, Tibet University, Lhasa 850000, Tibet (China); Yu, Tao, E-mail: yutao@tju.edu.cn [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Tianjin University-National Institute for Materials Science (TU-NIMS) Joint Research Center, Tianjin University, Tianjin 300072 (China)

    2014-12-01

    Graphical abstract: - Highlights: • A series of bicrystalline TiO{sub 2} nanoparticles with different ratio of controllable phase junctions between anatase and rutile were synthesized successfully using ionic liquid-assisted method by hydrolysis of TiCl{sub 4}. • The spatial separation capacity of photogenerated charge carriers and photocatalytic activities of the samples with different ratio of controllable phase junctions were evaluated systemically. • The best photocatalytic activity for MO degradation can reach above 99% at the sample with 27.4% rutile which also has the best photoelectric property compared with other samples. - Abstract: To explore the effect of phase composition on the photoelectric property of anatase–rutile mixed crystal nanoparticles, a series of TiO{sub 2} nanoparticles with phase junctions controlling were synthetized by hydrolysis of TiCl{sub 4} in hydrochloric acid, an ionic liquid-assisted method was used during this process. Crystalline size and the ratio of anatase to rutile of as-prepared samples were calculated by the XRD. The surface area was measured by nitrogen sorption measurements using the BET method. The micro-structure of phase junctions was characterized by TEM. Optical transmittance properties of TiO{sub 2} with controllable phase junctions were examined via ultraviolet–visible diffuse reflection spectroscopy (UV–vis DRS). The particles were manufactured into films using the doctor-blade technique on FTO glasses. To test photocurrent density, and spatial separation capacity of electron–holes pairs, photo-electro method was employed. The photocatalytic activities of the resulting samples were examined in the degradation of methyl orange (MO) under artificial solar light irradiation. Mechanisms of separation and transfer of photogenerated charge and the effect of phase composition on photoelectric property of anatase–rutile nanoparticles were discussed.

  18. Effects of black widow spider venom and Ca2+ on quantal secretion at the frog neuromuscular junction

    OpenAIRE

    1986-01-01

    A modification of the classical procedure of fluctuation analysis is used to measure the waveform, w(t), mean amplitude, (h), and mean rate of occurrence, (r), of miniature endplate potentials (MEPPs) at frog cutaneous pectoris neuromuscular junctions treated with black widow spider venom (BWSV). MEPP parameters are determined from the power spectrum of the fluctuating potential and the second (variance), third (skew), and fourth semi-invariants (cumulants) of high-pass-filtered records of th...

  19. Effects of Type I Collagen Degradation on the Durability of Three Adhesive Systems in the Early Phase of Dentin Bonding

    OpenAIRE

    Lin Hu; Yu-hong Xiao; Ming Fang; Yu Gao; Li Huang; An-qi Jia; Ji-hua Chen

    2015-01-01

    Objective This study was designed to evaluate the effects of type I collagen degradation on the durability of three adhesive systems in the early phase of dentin bonding. Methods Bonded dentin specimens were prepared using three different types of adhesive systems. Micro-tensile bond strength and degradation of collagen were tested before, and after 1 month or 4 months of aging in artificial saliva. The relationship between micro-tensile bond strength and collagen degradation was analyzed by ...

  20. Diabetes Increases Cryoinjury Size with Associated Effects on Cx43 Gap Junction Function and Phosphorylation in the Mouse Heart

    Directory of Open Access Journals (Sweden)

    Joseph A. Palatinus

    2016-01-01

    Full Text Available Diabetic patients develop larger myocardial infarctions and have an increased risk of death following a heart attack. The poor response to myocardial injury in the diabetic heart is likely related to the many metabolic derangements from diabetes that create a poor substrate in general for wound healing, response to injury and infection. Studies in rodents have implicated a role for the gap junction protein connexin 43 (Cx43 in regulating the injury response in diabetic skin wounds. In this study, we sought to determine whether diabetes alters Cx43 molecular interactions or intracellular communication in the cryoinjured STZ type I diabetic mouse heart. We found that epicardial cryoinjury size is increased in diabetic mice and this increase is prevented by preinjury insulin administration. Consistent with these findings, we found that intercellular coupling via gap junctions is decreased after insulin administration in diabetic and nondiabetic mice. This decrease in coupling is associated with a concomitant increase in phosphorylation of Cx43 at serine 368, a residue known to decrease channel conductance. Taken together, our results suggest that insulin regulates both gap junction-mediated intercellular communication and injury propagation in the mouse heart.

  1. Effects and mechanism of ozonation for degradation of sodium acetate in aqueous solution

    Directory of Open Access Journals (Sweden)

    De-min YANG

    2012-06-01

    Full Text Available The degradation efficiencies and mechanism of ozonation for the degradation of sodium acetate in aqueous solution were investigated under atmospheric pressure at room temperature (293 K. The effects of the initial pH value, reaction time, and concentrations of, , CaCl2, and Ca(OH2 on the removal rate of chemical oxygen demand (COD were studied. The results indicated that ozonation obviously improved the degradation rate of sodium acetate when the pH value of the solution was not less than 8.5. A suitable long reaction time may be helpful in increasing the COD removal rate, and a removal rate of 36.36% can be obtained after a 30-minute treatment. The COD removal rate increased firstly and decreased subsequently with the increase of the concentration (from 0 to 200 mg/L, and under the same experimental condition it reached the optimum 34.66% at the concentration of 100 mg/L. The COD removal rate was 5.26% lower when the concentration of was 200 mg/L than when there was no . The COD removal rate decreased by 15.68% when the concentration increased from 0 to 200 mg/L. has a more obvious scavenging effect in inhibiting the formation of hydroxyl radicals than . CaCl2 and Ca(OH2 could increase the degradation efficiency of sodium acetate greatly, and the COD removal rates reached 65.73% and 83.46%, respectively, after a 30-minute treatment, 29.37% and 47.10% higher, respectively, than with single ozone oxidation. It was proved that the degradation of sodium acetate in the ozonation process followed the mechanism of oxidization with hydroxyl free radicals (·OH.

  2. The opposing effects of bacterial activity and gas production on anaerobic TCE degradation in soil columns.

    Science.gov (United States)

    Singhal, Naresh; Jaffé, Peter; Maier, Walter; Jho, Eun Hea

    2007-11-01

    This laboratory study explores the effect of growth substrate concentration on the anaerobic degradation of trichloroethylene (TCE) in sand packed columns. In all columns the growth substrate rapidly degraded to gas, that formed a separate phase. Biomass accumulated in the 0-4.8 cm section of the columns in proportion to the influent growth substrate concentration and biomass concentrations in the remaining sections of all columns were similar to the column receiving the lowest substrate concentration. Increases in growth substrate concentration up to 3030 mg-CODl(-1) promoted TCE degradation, but a further increase to 14300 mg-CODl(-1) reduced the amount of TCE completely dechlorinated but did not affect the production of chlorinated TCE intermediates. The mathematical model developed here satisfactorily described the enhancement in TCE dehalogenation for substrate concentration up to 3030 mg-CODl(-1); reproducing TCE dehalogenation for 14300 mg-CODl(-1) required that the moisture content used in simulation be lowered to 0.1. The study shows that volatilization of TCE can be significant and volatilization losses should be taken into account when anaerobic activity in in-situ bioremediation applications is stimulated via addition of growth substrates. An implication of the modeling simulations is that maintaining a lower, but uniform, substrate concentration over the contaminated region may lead to faster contaminant degradation.

  3. Degradation of thiamethoxam by the synergetic effect between anodic oxidation and Fenton reactions.

    Science.gov (United States)

    Meijide, J; Gómez, J; Pazos, M; Sanromán, M A

    2016-12-05

    In this work, a comparative study using anodic oxidation, Fenton and electro-Fenton treatments was performed in order to determine the synergic effect for the removal of thiamethoxan. The results determined that electro-Fenton process showed high efficiency in comparison with Fenton or anodic oxidation. After that, this hybrid process was optimized and the influence of iron catalyst concentration and applied current intensity on the degradation and mineralization were evaluated. Degradation profiles were monitored by high performance liquid chromatography (HPLC) being satisfactorily described by pseudo-first order kinetic model. At the optimal experimental conditions (300mA and 0.2mM Fe(+2)), the complete degradation of thiamethoxam was achieved after 10min. On the other hand, mineralization of thiamethoxam was monitored by total organic carbon (TOC) decay reaching more than 92% of TOC removal after 8h. Furthermore, a plausible mineralization pathway for the thiamethoxam degradation was proposed based on the identification of by-products such as aromatic intermediates, carboxylic acids and inorganic ions released throughout electro-Fenton process.

  4. A Framework for Evaluating the Effects of Degraded Digital I and C Systems on Human Performance

    Energy Technology Data Exchange (ETDEWEB)

    OHara,J.; Gunther, B.; Hughes, N.; Barnes, V.

    2009-04-09

    New and advanced reactors will use integrated digital instrumentation and control (I&C) systems to support operators in their monitoring and control functions. Even though digital systems are typically highly reliable, their potential for degradation or failure could significantly affect operator situation awareness and performance and, consequently, impact plant safety. The U.S. Nuclear Regulatory Commission has initiated a research project to investigate the effects of degraded I&C systems on human performance and plant operations. The ultimate objective of this project is to develop the technical basis for human factors review guidance for conditions of degraded I&C, including complete failure. Based on the results of this effort, NRC will determine the need for developing new guidance or revising NUREG-0800, NUREG-0711, NUREG-0700 and other pertinent NRC review guidance. This paper reports on the first phase of the research, the development of a framework for linking degraded I&C system conditions to human performance. The framework consists of three levels: I&C subsystems, human-system interfaces, and human performance. Each level is composed of a number of discrete elements. This paper will describe the elements at each level and their integration. In the next phase of the research, the framework will be used to systematically investigate the human performance consequences of various classes of failures.

  5. EFFECT OF SOLID STATE FERMENTATION ON NUTRITIONAL CONTENT AND EVALUATION OF DEGRADABILITY IN CACTUS PEAR

    Directory of Open Access Journals (Sweden)

    TAMIRES CARVALHO DO SANTOS

    2015-01-01

    Full Text Available The process of protein enrichment of cactus pear (Nopalea cochenillifera (L. Salm Dyck by solid state fermentation with the use of Aspergillus niger and Rhyzopus sp. was studied for improving the nutritional value of this cactus species for use as animal feed. The experiments were conducted in the Agroindustrial Waste Laboratory of State University of Southwest Bahia (Brazil. To this end, we have evaluated the effects of biotransformation on the levels of protein, cellulose, hemicellulose, and lignin, as well as the potential degradability. Bioconversion was carried out using cactus pear as the only substrate, without supplementation with nitrogen, mineral and vitamin sources. The fermentation with Aspergillus niger promoted a 78% increase in/of protein content and reductions of cellulose, hemicellulose, and lignin of 40%, 36%, and 28%, respectively. Degradability, in turn, was observed to have increased by 66 % after 240 h. On the other hand, the fermentation with Rhyzopus sp. was less efficient, with a 69% increase in protein content, and reductions in cellulose, hemicellulose, and lignin contents of 30%, 28%, and 18%. In turn, degradability was seen to have increased by 51%. The fermentation of cactus pear by Aspergillus niger and Rhyzopus sp. exhibited the protein enrichment and increased protein degradability of this Cactaceae. Moreover, this is the most ever efficient micro-organism used in bioconversion. Based on the results, bioconversion of cactus is an excellent alternative to ruminant feeding in arid or semi-arid land.

  6. The effect of soil texture on the degradation of textiles associated with buried bodies.

    Science.gov (United States)

    Lowe, A C; Beresford, D V; Carter, D O; Gaspari, F; O'Brien, R C; Stuart, B H; Forbes, S L

    2013-09-10

    There are many factors which affect the rate of decomposition in a grave site including; the depth of burial, climatic conditions, physical conditions of the soil (e.g. texture, pH, moisture), and method of burial (e.g. clothing, wrappings). Clothing is often studied as a factor that can slow the rate of soft tissue decomposition. In contrast, the effect of soft tissue decomposition on the rate of textile degradation is usually reported as anecdotal evidence rather than being studied under controlled conditions. The majority of studies in this area have focused on the degradation of textiles buried directly in soil. The purpose of this study was to investigate the effect of soil texture on the degradation and/or preservation of textile materials associated with buried bodies. The study involved the burial of clothed domestic pig carcasses and control clothing in contrasting soil textures (silty clay loam, fine sand and fine sandy loam) at three field sites in southern Ontario, Canada. Graves were exhumed after 2, 12 and 14 months burial to observe the degree of degradation for both natural and synthetic textiles. Recovered textile samples were chemically analyzed using infrared (IR) spectroscopy and gas chromatography-mass spectrometry (GC-MS) to investigate the lipid decomposition by-products retained in the textiles. The findings of this study demonstrate that natural textile in contact with a buried decomposing body will be preserved for longer periods of time when compared to the same textile buried directly in soil and not in contact with a body. The soil texture did not visually impact the degree of degradation or preservation. Furthermore, the natural-synthetic textile blend was resistant to degradation, regardless of soil texture, contact with the body or time since deposition. Chemical analysis of the textiles using GC-MS correctly identified a lipid degradation profile consistent with the degree of soft tissue decomposition. Such information may be

  7. Electron transport in molecular junctions

    DEFF Research Database (Denmark)

    Jin, Chengjun

    This thesis addresses the electron transport in molecular junctions, focusing on the energy level alignment and correlation effects. Various levels of theory have been applied to study the structural and electronic effects in different molecular junctions, starting from the single particle density...... charge position are in quantitative agreement with the experiments, while pure DFT is not. This is the consequence of the accurate energy level alignment, where the DFT+∑ method corrects the self-interaction error in the standard DFT functional and uses a static image charge model to include the image...... charge effect on the energy level renormalization. Additionally, the gating of the 4,4’-bipyridine (44BP) molecule contacted to either Ni or Au electrodes has been investigated. Here it is found that the gating mechanism is conceptually different between two cases. In the case of Ni contacts where...

  8. Dose rate effects in radiation degradation of polymer-based cable materials

    Science.gov (United States)

    Plaček, V.; Bartoníček, B.; Hnát, V.; Otáhal, B.

    2003-08-01

    Cable ageing under the nuclear power plant (NPP) conditions must be effectively managed to ensure that the required plant safety and reliability are maintained throughout the plant service life. Ionizing radiation is one of the main stressors causing age-related degradation of polymer-based cable materials in air. For a given absorbed dose, radiation-induced damage to a polymer in air environment usually depends on the dose rate of the exposure. In this work, the effect of dose rate on the degradation rate has been studied. Three types of NPP cables (with jacket/insulation combinations PVC/PVC, PVC/PE, XPE/XPE) were irradiated at room temperature using 60Co gamma ray source at average dose rates of 7, 30 and 100 Gy/h with the doses up to 590 kGy. The irradiated samples have been tested for their mechanical properties, thermo-oxidative stability (using differential scanning calorimetry, DSC), and density. In the case of PVC and PE samples, the tested properties have shown evident dose rate effects, while the XPE material has shown no noticeable ones. The values of elongation at break and the thermo-oxidative stability decrease with the advanced degradation, density tends to increase with the absorbed dose. For XPE samples this effect can be partially explained by the increase of crystallinity. It was tested by the DSC determination of the crystalline phase amount.

  9. Effect of equivalent surface charge density on electrical field of positively beveled p-n junction%等效表面电荷对斜角造型p-n结表面电场的影响

    Institute of Scientific and Technical Information of China (English)

    吴春瑜; 王颖; 朱长纯

    2008-01-01

    The space-charge layer (SCL) and surface depletion area (SDA) model for beveled p-n junction is presented. Thesurface space-charge density is calculated for depletion case of beveled p-n junction. Based on the finite difference method,the effect of the equivalent surface charge density on the surface depletion area for positively beveled p-n junction is alsostudied. Thyristors passivated with polyimide (PI) or polyester improved silicon paint (SP) are fabricated to verify the effectof equivalent surface charge on the peripheral surface of beveled p-n junction. The change of leakage current is sensitive tothe surface charges. It indicates that the selection of passivation materials is a significant process to ensure the breakdownvoltage capability of beveled devices.

  10. Effects of UV on power degradation of photovoltaic modules in combined acceleration tests

    Science.gov (United States)

    Ngo, Trang; Heta, Yushi; Doi, Takuya; Masuda, Atsushi

    2016-05-01

    UV exposure and other factors such as high/low temperature, humidity and mechanical stress have been reported to degrade photovoltaic (PV) module materials. By focusing on the combined effects of UV stress and moisture on PV modules, two new acceleration tests of light irradiation and damp heat (DH) were designed and conducted. The effects of UV exposure were validated through a change in irradiation time (UV dosage) and a change of the light irradiation side (glass side vs backsheet side) in the UV-preconditioned DH and cyclic sequential tests, respectively. The chemical corrosion of finger electrodes in the presence of acetic acid generated from ethylene vinyl acetate used as an encapsulant was considered to be the main origin of degradation. The module performance characterized by electroluminescence images was confirmed to correlate with the measured acetic acid concentration and Ag finger electrode resistance.

  11. Effect of particle size and microbial phytase on phytate degradation in incubated maize and soybean meal

    DEFF Research Database (Denmark)

    Ton Nu, Mai Anh; Blaabjerg, Karoline; Poulsen, Hanne Damgaard

    2014-01-01

    by 88% in maize, 84% in maize–SBM and 75% in SBM after 2 h of incubation (Pmodel was fitted to the feeds with microbial phytase to analyse the effect......The objective of the study was to evaluate the effect of screen size (1, 2 and 3 mm) and microbial phytase (0 and 1000 FTU/kg as-fed) on phytate degradation in maize (100% maize), soybean meal (100% SBM) and maize–SBM (75% maize and 25% SBM) incubated in water for 0, 2, 4, 8 and 24 h at 38°C...... reduced APS by 48% in maize, 30% in SBM and 26% in maize–SBM. No interaction between screen size and microbial phytase on phytate degradation was observed, but the interaction between microbial phytase and incubation time was significant (P

  12. Effect of Inoculation with Effective Microorganisms and Leachate Recycle on Degradation of Municipal Refuse

    Institute of Scientific and Technical Information of China (English)

    沈东升; 何若; 朱荫湄

    2004-01-01

    Biodegradation of waste in landfill is a slow process requiring decades for completion. Accelerated degradation of municipal refuse in modulated landfill environments may alleviate or eliminate pollution to the land, water and air. In this work, nineteen effective microorganisms (EMs) were isolated from old landfill refuse by enrichment culturing techniques and used for the inoculum of municipal refuse. The preliminary experiments demonstrate that a combination of EMs inoculation in landfill with leachate recycle resulted in increased rates of decomposition and faster process stability. The concentrations of COD, VFA and SO42- in digester with EMs inoculation and leachate recycle decreased more rapidly than others. Gas production from digester with EMs inoculation and leachate recycle commenced around 32 days, which is a week shorter than with leachate recycle only. And peak cumulative gas production was obtained much earlier in digester with EMs inoculation and leachate recycle (150 days) compared to 180 days with leachate recycle only. Moreover, in the first two months, the rate of settlement in digester with EMs inoculation and leachate recycle was more rapid than others.

  13. The Effects of Degraded Vision and Automatic Combat Identification Reliability on Infantry Friendly Fire Engagements

    OpenAIRE

    Kogler, Timothy Michael

    2003-01-01

    Fratricide is one of the most devastating consequences of any military conflict. Target identification failures have been identified as the last link in a chain of mistakes that can lead to fratricide. Other links include weapon and equipment malfunctions, command, control, and communication failures, navigation failures, fire discipline failures, and situation awareness failures. This research examined the effects of degraded vision and combat identification reliability on the time-stress...

  14. Effect of inhibitors of cellular metabolism on postradiation repair and degradation of DNA in rat thymocytes

    Energy Technology Data Exchange (ETDEWEB)

    Ivannik, B.P.; Golubeva, R.V.; Proskuryakov, S.Ya.; Murzaev, V.I.; Ryabchenko, N.I.

    1979-10-01

    The viscosimetric method was used to determine the molecular weight of high polymer single-stranded DNA in alkaline nuclear lysates for the study of the effects of a number of inhibitors of synthesis of DNA (hydroxyurea), macroergic elements (2,4-dinitrophenol, EDTA) and DNAase (Na/sup +/ citrate, Ca/sup + +/ ions) on the process of repair and secondary post-radiation degradation of DNA of rat thymocytes exposed to radiation in a dosage of 3 kR.

  15. Effect of Direct Electric Current on the Cell Surface Properties of Phenol-Degrading Bacteria

    OpenAIRE

    Luo, Qishi; Wang, Hui; Zhang, Xihui; Qian, Yi

    2005-01-01

    The change in cell surface properties in the presence of electric currents is of critical concern when the potential to manipulate bacterial movement with electric fields is evaluated. In this study, the effects of different direct electric currents on the cell surface properties involved in bacterial adhesion were investigated by using a mixed phenol-degrading bacterial culture in the exponential growth phase. The traits investigated were surface hydrophobicity (measured by adherence to n-oc...

  16. Exploring effective sampling design for monitoring soil organic carbon in degraded Tibetan grasslands.

    Science.gov (United States)

    Chang, Xiaofeng; Bao, Xiaoying; Wang, Shiping; Zhu, Xiaoxue; Luo, Caiyun; Zhang, Zhenhua; Wilkes, Andreas

    2016-05-15

    The effects of climate change and human activities on grassland degradation and soil carbon stocks have become a focus of both research and policy. However, lack of research on appropriate sampling design prevents accurate assessment of soil carbon stocks and stock changes at community and regional scales. Here, we conducted an intensive survey with 1196 sampling sites over an area of 190 km(2) of degraded alpine meadow. Compared to lightly degraded meadow, soil organic carbon (SOC) stocks in moderately, heavily and extremely degraded meadow were reduced by 11.0%, 13.5% and 17.9%, respectively. Our field survey sampling design was overly intensive to estimate SOC status with a tolerable uncertainty of 10%. Power analysis showed that the optimal sampling density to achieve the desired accuracy would be 2, 3, 5 and 7 sites per 10 km(2) for lightly, moderately, heavily and extremely degraded meadows, respectively. If a subsequent paired sampling design with the optimum sample size were performed, assuming stock change rates predicted by experimental and modeling results, we estimate that about 5-10 years would be necessary to detect expected trends in SOC in the top 20 cm soil layer. Our results highlight the utility of conducting preliminary surveys to estimate the appropriate sampling density and avoid wasting resources due to over-sampling, and to estimate the sampling interval required to detect an expected sequestration rate. Future studies will be needed to evaluate spatial and temporal patterns of SOC variability. Copyright © 2016. Published by Elsevier Ltd.

  17. In-plane magnetic field effect on switching voltage and thermal stability in electric-field-controlled perpendicular magnetic tunnel junctions

    Science.gov (United States)

    Grezes, C.; Rojas Rozas, A.; Ebrahimi, F.; Alzate, J. G.; Cai, X.; Katine, J. A.; Langer, J.; Ocker, B.; Khalili Amiri, P.; Wang, K. L.

    2016-07-01

    The effect of in-plane magnetic field on switching voltage (Vsw) and thermal stability factor (Δ) are investigated in electric-field-controlled perpendicular magnetic tunnel junctions (p-MTJs). Dwell time measurements are used to determine the voltage dependence of the energy barrier height for various in-plane magnetic fields (Hin), and gain insight into the Hin dependent energy landscape. We find that both Vsw and Δ decrease with increasing Hin, with a dominant linear dependence. The results are reproduced by calculations based on a macrospin model while accounting for the modified magnetization configuration in the presence of an external magnetic field.

  18. [Effects of strong reductive approach on remediation of degraded facility vegetable soil].

    Science.gov (United States)

    Zhu, Tong-Bin; Meng, Tian-Zhu; Zhang, Jin-Bo; Cai, Zu-Cong

    2013-09-01

    High application rate of chemical fertilizers and unreasonable rotation in facility vegetable cultivation can easily induce the occurrence of soil acidification, salinization, and serious soil-borne diseases, while to quickly and effectively remediate the degraded facility vegetable soil can considerably increase vegetable yield and farmers' income. In this paper, a degraded facility vegetable soil was amended with 0, 3.75, 7.50, and 11.3 t C x hm(-2) of air-dried alfalfa and flooded for 31 days to establish a strong reductive environment, with the variations of soil physical and chemical properties and the cucumber yield studied. Under the reductive condition, soil Eh dropped quickly below 0 mV, accumulated soil NO3(-) was effectively eliminated, soil pH was significantly raised, and soil EC was lowered, being more evident in higher alfalfa input treatments. After treated with the strong reductive approach, the cucumber yield in the facility vegetable field reached 53.3-57.9 t x hm(-2), being significantly higher than that in un-treated facility vegetable field in last growth season (10.8 t x hm(-2)). It was suggested that strong reductive approach could effectively remediate the degraded facility vegetable soil in a short term.

  19. Dependence of transport properties in tunnel junction on boron doping

    Energy Technology Data Exchange (ETDEWEB)

    Shi, M.J.; Zeng, X.B.; Liu, S.Y.; Peng, W.B; Xiao, H.B; Liao, X.B.; Wang, Z.G.; Kong, G.L. [Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

    2010-04-15

    Boron-doped hydrogenated silicon films with different gaseous doping ratio (B{sub 2}H{sub 6}/SiH{sub 4}) were fabricated as recombination p layers in tunnel junctions. The measurements of I-V characteristics of the junctions and transparency spectra of p layer indicated that the best gaseous doping ratio of the recombination layer is 0.04, which is correlated to the degradation of short range order (SRO) in the inserted p thin film. The junction with such recombination layer has small resistance, near ohmic contact. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Effects of iron limitation on the degradation of toluene by Pseudomonas strains carrying the TOL (pWWO) plasmid

    NARCIS (Netherlands)

    Dinkla, IJT; Gabor, EM; Janssen, DB; Dinkla, Inez J.T.; Gabor, Esther M.

    2001-01-01

    Most aerobic biodegradation pathways for hydrocarbons involve iron-containing oxygenases. In iron-limited environments, such as the rhizosphere, this may influence the rate of degradation of hydrocarbon pollutants. We investigated the effects of iron limitation on the degradation of toluene by Pseud

  1. Effects of inorganics on the degradation of micropollutants with vacuum UV (VUV) advanced oxidation.

    Science.gov (United States)

    Duca, Clara; Imoberdorf, Gustavo; Mohseni, Madjid

    2017-02-21

    This research focused on the effects of inorganic water constituents on the efficiency of vacuum UV (VUV) for the degradation of micropollutants in surface water supplies. Atrazine was used as a model miropollutant, and bicarbonate, sulphate, and nitrate were used as the most common inorganic constituents in the water matrix. First, the absorbance of radiation at 254 and 185 nm was measured in the presence of different ions. At 254 nm, only nitrate showed a measurable absorption coefficient of [Formula: see text] = 3.51 M[Formula: see text] cm[Formula: see text], and all other ions showed a molar absorption coefficient below the detection limit. However, at 185 nm, all the ions showed high absorption coefficients, with nitrate giving the highest absorption coefficient of [Formula: see text] = 5568 M[Formula: see text] cm[Formula: see text]. Second, the hydroxyl radical (HO[Formula: see text]) scavenging effects of the same inorganic ions were evaluated; nitrate and bicarbonate showed a negative effect during the UV/H2O2 and VUV advanced oxidation processes. Sulfate was photolyzed with 185 nm UV to form HO[Formula: see text], and for this reason, it assisted the degradation of the target micropollutant, as demonstrated by increases in the degradation rate constant. An additional component of this work involved developing a method for measuring the quantum yield of atrazine at 185 nm. This made it possible to distinguish the contribution of OH radical attach from that of direct photolysis towards the degradation of atrazine.

  2. Water quality degradation effects on freshwater availability: Impacts to human activities

    Science.gov (United States)

    Peters, N.E.; Meybeck, Michel

    2000-01-01

    The quality of freshwater at any point on the landscape reflects the combined effects of many processes along water pathways. Human activities on all spatial scales affect both water quality and quantity. Alteration of the landscape and associated vegetation has not only changed the water balance, but typically has altered processes that control water quality. Effects of human activities on a small scale are relevant to an entire drainage basin. Furthermore, local, regional, and global differences in climate and water flow are considerable, causing varying effects of human activities on land and water quality and quantity, depending on location within a watershed, geology, biology, physiographic characteristics, and climate. These natural characteristics also greatly control human activities, which will, in turn, modify (or affect) the natural composition of water. One of the most important issues for effective resource management is recognition of cyclical and cascading effects of human activities on the water quality and quantity along hydrologic pathways. The degradation of water quality in one part of a watershed can have negative effects on users downstream. Everyone lives downstream of the effects of some human activity. An extremely important factor is that substances added to the atmosphere, land, and water generally have relatively long time scales for removal or clean up. The nature of the substance, including its affinity for adhering to soil and its ability to be transformed, affects the mobility and the time scale for removal of the substance. Policy alone will not solve many of the degradation issues, but a combination of policy, education, scientific knowledge, planning, and enforcement of applicable laws can provide mechanisms for slowing the rate of degradation and provide human and environmental protection. Such an integrated approach is needed to effectively manage land and water resources.

  3. Gamma Radiation Tolerance of Magnetic Tunnel Junctions

    Science.gov (United States)

    Ren, Fanghui; Jander, Albrecht; Dhagat, Pallavi; Nordman, Cathy

    2011-10-01

    Determining the radiation tolerance of magnetic tunnel junctions (MTJ), which are the storage elements of non-volatile magnetoresistive random access memories (MRAM), is important for investigating their potential application in space. In this effort, the effect of gamma radiation on MTJs with MgO tunnel barriers was studied. Experimental and control groups of samples were characterized by ex situ measurements of the magnetoresistive hysteresis loops and I-V curves. The experimental group was exposed to gamma rays from a ^60Co source. The samples initially received a dose of 5.9 Mrad (Si) after which they were again characterized electrically and magnetically. Irradiation was then continued for a cumulative dose of 10 Mrad and the devices re-measured. The result shows no change in magnetic properties such as coercivity or exchange coupling due to irradiation. After correcting for differences in temperature at the time of testing, the tunneling magnetoresistance was also found to be unchanged. Thus, it has been determined that MgO-based MTJs are highly tolerant of gamma radiation, particularly in comparison to silicon field-effect transistors which have been shown to degrade with gamma ray exposure even as low as 100 Krad [Zhiyuan Hu. et al., IEEE trans. on Nucl. Sci., vol. 58, 2011].

  4. Dynamical reentrance and geometry imposed quantization effects in Nb-AlO{sub x}-Nb Josephson junction arrays

    Energy Technology Data Exchange (ETDEWEB)

    Araujo-Moreira, Fernando M [Grupo de Materiais e Dispositivos, Centro Multidisciplinar para o Desenvolvimento de Materiais Ceramicos, Departamento de Fisica, Universidade Federal de Sao Carlos, 13565-905 Sao Carlos, SP (Brazil); Sergeenkov, Sergei [Departamento de Fisica, CCEN, Universidade Federal da ParaIba, Cidade Universitaria, 58051-970 Joao Pessoa, PB (Brazil)

    2008-04-01

    In this paper, we report on different phenomena related to the magnetic properties of artificially prepared highly ordered (periodic) two-dimensional Josephson junction arrays (2D-JJAs) of both shunted and unshunted Nb-AlO{sub x}-Nb tunnel junctions. By employing mutual-inductance measurements and using a high-sensitivity home-made bridge, we have thoroughly investigated (both experimentally and theoretically) the temperature and magnetic field dependence of complex AC susceptibility of 2D-JJAs. After a brief description of the measurement technique and the numerical simulations method, we proceed to demonstrate that the observed dynamic reentrance (DR) phenomenon is directly linked to the value of the Stewart-McCumber parameter {beta}{sub C}. By simultaneously varying the inductance related parameter {beta}{sub L}, we obtain a phase diagram {beta}{sub C}-{beta}{sub L} (which demarcates the border between the reentrant and non-reentrant behavior) and show that only arrays with sufficiently large value of {beta}{sub C} will exhibit DR behavior. The second topic of this paper is related to the step-like structure (with the number of steps n = 4 corresponding to the number of flux quanta that can be screened by the maximum critical current of the junctions) which has been observed in the temperature dependence of AC susceptibility in our unshunted 2D-JJA with {beta}{sub L} (4.2 K) = 30 and attributed to the geometric properties of the array. The steps are predicted to manifest themselves in arrays with {beta}{sub L}(T) matching a 'quantization' condition {beta}{sub L}(0) = 2{pi}(n+1). In conclusion, we demonstrate the use of the scanning SQUID microscope for imaging the local flux distribution within our unshunted arrays.

  5. Degradability of injectable calcium sulfate/mineralized collagen-based bone repair material and its effect on bone tissue regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Zonggang, E-mail: chenzg@sdu.edu.cn [National Glycoengineering Research Center, Shandong University, Jinan 250100 (China); Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Kang, Lingzhi [National Glycoengineering Research Center, Shandong University, Jinan 250100 (China); Meng, Qing-Yuan [Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Liu, Huanye [Department of Prosthodontics, School of Stomatology, China Medical University, Shenyang 110001 (China); Wang, Zhaoliang [Jinan Military General Hospital of PLA, Jinan 250031 (China); Guo, Zhongwu, E-mail: zwguo@sdu.edu.cn [National Glycoengineering Research Center, Shandong University, Jinan 250100 (China); Cui, Fu-Zhai, E-mail: cuifz@mail.tsinghua.edu.cn [Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2014-12-01

    The nHAC/CSH composite is an injectable bone repair material with controllable injectability and self-setting properties prepared by introducing calcium sulfate hemihydrate (CSH) into mineralized collagen (nHAC). When mixed with water, the nHAC/CSH composites can be transformed into mineralized collagen/calcium sulfate dihydrate (nHAC/CSD) composites. The nHAC/CSD composites have good biocompatibility and osteogenic capability. Considering that the degradation behavior of bone repair material is another important factor for its clinical applications, the degradability of nHAC/CSD composites was studied. The results showed that the degradation ratio of the nHAC/CSD composites with lower nHAC content increased with the L/S ratio increase of injectable materials, but the variety of L/S ratio had no significant effect on the degradation ratio of the nHAC/CSD composites with higher nHAC content. Increasing nHAC content in the composites could slow down the degradation of nHAC/CSD composite. Setting accelerator had no significant effect on the degradability of nHAC/CSD composites. In vivo histological analysis suggests that the degradation rate of materials can match the growth rate of new mandibular bone tissues in the implanted site of rabbit. The regulable degradability of materials resulting from the special prescriptions of injectable nHAC/CSH composites will further improve the workability of nHAC/CSD composites. - Highlights: • The nHAC/CSH composite can be as an injectable bone repair material. • The L/S ratio and nHAC content have a significant effect on material degradability. • The degradability of bone materials can be regulated to match tissue repair. • The regulable degradability will further improve the workability of bone materials.

  6. [Effects of nitrogen and phosphorous fertilization on community structure and productivity of degraded alpine meadows in northern Tibet, China].

    Science.gov (United States)

    Zong, Ning; Shi, Pei-li; Niu, Ben; Jiang, Jing; Song, Ming-hua; Zhang, Xian-zhou; He, Yong-tao

    2014-12-01

    Abstract: Fertilization is an effective management measure for recovery of degraded grasslands. To better understand the effects of fertilization on community structure and productivity of lightly and severely degraded alpine meadows, we conducted a fertilization experiment in northern Tibet since 2008. The treatments were addition of nitrogen (N) alone (50 kg N x hm(-2) x a(-1), LN; 100 kg N x hm(-2) x a(-1), HN) or addition of both phosphorus (P) and N (50 kg N x hm(-2) x a(-1) +50 kg P x hm(-2) x a(-1), LN+P; 100 kg N x hm(-2) x a(-1) +50 kg P x hm(-2) x a(-1), HN+P) in each of the two types of degraded alpine meadows. N addition alone significantly affected plant community coverage or productivity in neither the slightly nor the severely degraded alpine meadow, while addition of both N and P significantly increased plant community coverage, aboveground and below- ground biomass of the alpine meadows. This suggested that productivity of this alpine meadow is co-limited by N and P. HN and HN+P significantly decreased species richness and evenness in the lightly degraded grassland, indicating that HN was not beneficial for the lightly degraded grassland to maintain species diversity and community stability. N addition significantly reduced the root to shoot ratio in the severely degraded meadow. In the lightly degraded meadow, N addition alone, especially with a high amount (HN) , enhanced the importance values (IV) and biomass of grasses, while fertilization with both N and P increased those of sedges. In the severely degraded meadow, fertilization had little effect on IV of grasses or sedges, but improved biomass of forbs. The results suggested that LN+P could be employed in recovery of lightly degraded alpine meadows, but other management measures such as fencing and reseeding may be needed for recovery of severely degraded alpine meadows.

  7. Quantum size effects on spin-transfer torque in a double barrier magnetic tunnel junction with a nonmagnetic-metal (semiconductor) spacer

    Energy Technology Data Exchange (ETDEWEB)

    Daqiq, Reza; Ghobadi, Nader

    2016-07-15

    We study the quantum size effects of an MgO-based double barrier magnetic tunnel junction with a nonmagnetic-metal (DBMTJ-NM) (semiconductor (DBMTJ-SC)) spacer on the charge current and the spin-transfer torque (STT) components using non-equilibrium Green's function (NEGF) formalism. The results show oscillatory behavior due to the resonant tunneling effect depending on the structure parameters. We find that the charge current and the STT components in the DBMTJ-SC demonstrate the magnitude enhancement in comparison with the DBMTJ-NM. The bias dependence of the STT components in a DBMTJ-NM shows different behavior in comparison with spin valves and conventional MTJs. Therefore, by choosing a specific SC spacer with suitable thickness in a DBMTJ the charge current and the STT components significantly increase so that one can design a device with high STT and faster magnetization switching. - Highlights: • The quantum size effects are studied in double barrier magnetic tunnel junctions. • Spin torque (ST) components oscillate for increasing of middle spacer thicknesses. • Due to the resonant tunneling in the quantum well, oscillations have appeared. • By replacement a metal spacer with a semiconductor (ZnO) ST has increased. • The ST components vs. bias show gradually decreasing unlike spin valves or MTJs.

  8. Effect of dietary starch level and its rumen degradability on lamb meat fatty acid composition.

    Science.gov (United States)

    Oliveira, Maria A; Alves, Susana P; Santos-Silva, José; Bessa, Rui J B

    2017-01-01

    Forty lambs were fed one of four diets supplemented with a linseed and sunflower oil blend but differing in starch level (mid, ≈35 vs. high, ≈50%) and starch rumen degradability (mid, ≈70 vs. high, ≈80%). The effects of diet on growth, carcass traits and meat fatty acid (FA) composition, with emphasis on biohydrogenation intermediates were evaluated. Lambs stayed on trial for 5weeks until slaughter. Treatment had no effect on animal performance and carcass traits. High-degradability diets decreased (P=0.04) meat shear force compared with mid-degradability diets. Lipid content of meat was unaffected by the diet. Mid-starch diets increased (P<0.05) the saturated FA and cis-MUFA but decreased (P<0.05) the trans-MUFA, particularly the t10-18:1, when compared with high-starch diets. The t11-18:1 (0.7% of total FA) and c9,t11-18:2 (<0.3%) remained low and the 18:3n-3 remained high (1.74%) and unaffected by diet.

  9. Low-temperature carbonization and more effective degradation of carbohydrates induced by ferric trichloride.

    Science.gov (United States)

    Xia, Juan; Song, Le Xin; Dang, Zheng

    2012-07-05

    The present work is devoted to an attempt to understand the effect of an inorganic salt such as ferric trichloride (FeCl(3)) on the carbonization and degradation of carbohydrates such as β-cyclodextrin (CD), amylose, and cellulose. Our data revealed two important observations. First, the presence of FeCl(3) led to the occurrence of a low carbonization temperature of 373 K. This is a rare phenomenon, in which carbonization improvement is present even if a small amount of FeCl(3) was added. Experimental results had provided evidence for the fact that a redox process was started during the low-temperature carbonization of β-CD, causing the reduction of FeCl(3) to ferrous chloride (FeCl(2)) by carbon materials formed in the carbonization process in air. However, the reduction process of FeCl(3) produced the in situ composite nanomaterial of Fe-FeCl(2) combination in nitrogen. Second, a molecule-ion interaction emerged between FeCl(3) and the carbohydrates in aqueous solution, resulting in a more effective degradation of the carbohydrates. Moreover, our results demonstrated that FeCl(3) played the role of a catalyst during the degradation of the carbohydrates in solution. We believe that the current work not only has a significant potential application in disposal of waste carbohydrates but also could be helpful in many fields such as environmental protection, biomass energy development, and inorganic composite nanomaterials.

  10. Effect of electric intensity on the microbial degradation of petroleum pollutants in soil.

    Science.gov (United States)

    Li, Tingting; Guo, Shuhai; Wu, Bo; Li, Fengmei; Niu, Zhixin

    2010-01-01

    Electro-bioremediation is an innovative method to remedy organic-polluted soil. However, the principle of electrokinetic technology enhancing the function of microbes, especially the relationship of electric intensity and biodegradation efficiency, is poorly investigated. Petroleum was employed as a target organic pollutant at a level of 50 g/kg (mass of petroleum/mass of dry soil). A direct current power supply was used for tests with a constant direct current electric voltage (1.0 V/cm). The petroleum concentrations were measured at 3275-3285 nm after extraction using hexane, the group composition of crude oil was analyzed by column chromatography. The water content of soil was kept 25% (m/m). The results indicated the degradation process was divided into two periods: from day 1 to day 40, from day 41 to day 100. The treatment of soil with an appropriate electric field led the bacteria to have a persistent effect in the whole period of 100 days. The highest biodegradation efficiency of 45.5% was obtained after treatment with electric current and bacteria. The electric-bioremediation had a positive effect on alkane degradation. The degradation rate of alkane was 1.6 times higher in the soil exposed to electric current than that treated with bacteria for 100 days. A proper direct current could stimulate the microbial activities and accelerate the biodegradation of petroleum. There was a positive correlation between the electric intensities and the petroleum bioremediation efficiencies with a coefficient of 0.9599.

  11. Long-term effect on the solidified degraded cellulose-based waste slurry in cement matrix

    Directory of Open Access Journals (Sweden)

    Hosam El-Din Mostafa Saleh

    2009-03-01

    Full Text Available The long-term effects on solidification/stabilization (s/s of the secondary wastes, resulting from the oxidative degradation of some solid cellulosic-based wastes, in Portland Cement (CEM I have been investigated by X-ray diffraction (X-RD and Fourier transform infrared spectroscopy (FT-IR techniques. The effect of seven years leaching of the cemented waste forms obtained was carried out to assess the long-term immobilization behavior of the radionuclide in the solidified/stabilized waste that maybe exposed to fresh, ground or sea water.The results of this study confirm our previously published work that the oxidative degradation treatment of some cellulosic-based wastes is essential before incorporating into the cementitious inert matrix. In addition, the release of radionuclides from the cemented waste form is a diffusion controlling process, after the first washing out period lasting for nearly thirty days.Based on the results so far obtained it is concluded that Portland Cement could be considered as a potential inert matrix to immobilize the degraded cellulosic-based wastes for a short or long time of storage or a final disposal.

  12. Atrazine and its degradates have little effect on the corticosteroid stress response in the zebrafish.

    Science.gov (United States)

    Van Der Kraak, Glen; Matsumoto, Jacquie; Kim, Myoungwoo; Hosmer, Alan J

    2015-04-01

    The present study examined the effects of atrazine on basal and forced swimming induced changes in whole body cortisol content in adult zebrafish. Zebrafish were exposed to graded concentrations of atrazine or the atrazine degradates deisopropylatrazine (DIA), deethylatrazine (DEA) and diamino-s-chlorotriazine (DACT) for up to 10 days. Some fish were sampled for the measurement of whole body cortisol levels under basal conditions while others were sampled after being subjected to a 20 min swimming challenge in order to quantify stress induced cortisol levels. In one experiment, zebrafish were subjected to two bouts of forced swimming 3h apart to test whether prior atrazine exposure affects the ability of the fish to respond appropriately to a repeated stressor. The results demonstrated that controls not exposed to atrazine and zebrafish exposed to atrazine or the atrazine degradates at nominal concentrations of up to 100 μg/L consistently exhibited increased whole body cortisol content in response to the swimming challenge. Separate analyses revealed few changes in basal or stress induced cortisol levels following atrazine exposure. Overall, these data suggest that atrazine and some of its degradates at the concentrations tested have minimal effects on the cortisol mediated stress response in the zebrafish. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Equivalent Josephson junctions

    Science.gov (United States)

    Boyadjiev, T. L.; Semerdjieva, E. G.; Shukrinov, Yu. M.

    2008-01-01

    The magnetic field dependences of critical current are numerically constructed for a long Josephson junction with a shunt-or resistor-type microscopic inhomogeneities and compared to the critical curve of a junction with exponentially varying width. The numerical results show that it is adequate to replace the distributed inhomogeneity of a long Josephson junction by an inhomogeneity localized at one of its ends, which has certain technological advantages. It is also shown that the critical curves of junctions with exponentially varying width and inhomogeneities localized at the ends are unaffected by the mixed fluxon-antifluxon distributions of the magnetic flow. This fact may explain the improvement of the spectra of microwave radiation noted in the literature.

  14. A Study of the Characteristics of Microorganisms for Effective Degradation of Marine Oil Spills

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Four microorganism strains were isolated from coastal petroleum-polluted soil and sand samples of Bohai Sea oilfield; they were found to degrade marine oil spills effectively. The experimental results show that the degradation efficiency of crude oil with these four strains (XT-4, SZ-1-25, B-4-9, BS-3-12) is 95.97%, 96.01%, 97.99% and 98.99%, respectively, in their optimum conditions. The characteristics of bacterial biodegradation are investigated. The simulation biotreatment of oil-contaminated beach sand, with an initial oil content of 5,664mg/kg-dry-sand, shows that the residual oil content is 2,700 mg/kg-dry-sand and 2,679 mg/kg-dry-sand after 170 days' treatment with two bacteria (B-4-9, BS-3-12), respectively.

  15. Effect of vitamins on the aerobic degradation of 2-chlorophenol, 4-chlorophenol, and 4-chlorobiphenyl

    Energy Technology Data Exchange (ETDEWEB)

    Kafkewitz, D. [Rutgers Univ., Newark, NJ (United States). Dept. of Biological Science; Fava, F. [Bologna Univ. (Italy). Dept. of Applied Chemistry and Material Science; Armenante, P.M. [New Jersey Inst. of Tech., Newark, NJ (United States). Dept. of Chemical Engineering, Chemistry, and Environmental Science

    1996-12-31

    The effect of vitamins on the aerobic degradation and dechlorination of 2-chlorophenol and 4-chlorophenol by Pseudomonas pickettii, strain LD1, and 4-chlorobiphenyl by Pseudomonas sp. strain CPE1 was determined. These microorganisms are capable of using the target compounds as the sole carbon and energy source, but do not need vitamins to metabolize them. The addition to the culture medium of a vitamin solution containing biotin, folic acid, pyridoxine hydrochloride, riboflavin, thiamine hydrochloride, niacin, pantothenic acid, cyanocobalamin, p-aminobenzoic acid, and thioctic acid (total final concentration: {<=}600 ppb) resulted in a 7%-16% increase in the amount of target compounds degraded over the incubation period required for the concentration of the compound in the cultures to drop to approximately zero. A corresponding increase in the amount of chloride ion produced was also detected during the same period, indicating active (and often stoichiometric) dechlorination of the target compounds. (orig.)

  16. Preventive effects of kudzu root on bone loss and cartilage degradation in ovariectomized rat

    DEFF Research Database (Denmark)

    Luo, Yunyun

    2017-01-01

    The clinical utility of Traditional Chinese Medicine (TCM) herbs/roots extracts in osteoporosis (OP) and osteoarthritis (OA) has been described in multiple reports, but there have been few studies of TCM for preventing bone loss and cartilage degradation simultaneously. Six-month-old female Sprague......-Dawley rats each were subjected to ovariectomized (OVX) or sham surgery and treated orally once daily with herbal extracts or vehicle. Body weight was recorded weekly, and blood samples were collected from fasting animals at different time points. Biochemical markers of bone resorption and cartilage...... degradation were analyzed. Changes in bone mineral density and calcium content were determined in the femoral center and femoral telocentric end of rats. Out of 56 TCM herbs/roots extracts, only kudzu root demonstrated consistent joint protective effects. OVX resulted in a marked increase in bone resorption...

  17. Research study on high energy radiation effect and environment solar cell degradation methods

    Science.gov (United States)

    Horne, W. E.; Wilkinson, M. C.

    1974-01-01

    The most detailed and comprehensively verified analytical model was used to evaluate the effects of simplifying assumptions on the accuracy of predictions made by the external damage coefficient method. It was found that the most serious discrepancies were present in heavily damaged cells, particularly proton damaged cells, in which a gradient in damage across the cell existed. In general, it was found that the current damage coefficient method tends to underestimate damage at high fluences. An exception to this rule was thick cover-slipped cells experiencing heavy degradation due to omnidirectional electrons. In such cases, the damage coefficient method overestimates the damage. Comparisons of degradation predictions made by the two methods and measured flight data confirmed the above findings.

  18. Effect of food processing on plant DNA degradation and PCR-based GMO analysis: a review.

    Science.gov (United States)

    Gryson, Nicolas

    2010-03-01

    The applicability of a DNA-based method for GMO detection and quantification depends on the quality and quantity of the DNA. Important food-processing conditions, for example temperature and pH, may lead to degradation of the DNA, rendering PCR analysis impossible or GMO quantification unreliable. This review discusses the effect of several food processes on DNA degradation and subsequent GMO detection and quantification. The data show that, although many of these processes do indeed lead to the fragmentation of DNA, amplification of the DNA may still be possible. Length and composition of the amplicon may, however, affect the result, as also may the method of extraction used. Also, many techniques are used to describe the behaviour of DNA in food processing, which occasionally makes it difficult to compare research results. Further research should be aimed at defining ingredients in terms of their DNA quality and PCR amplification ability, and elaboration of matrix-specific certified reference materials.

  19. Fretting corrosion of CoCr alloy: Effect of load and displacement on the degradation mechanisms.

    Science.gov (United States)

    Bryant, Michael; Neville, Anne

    2017-02-01

    Fretting corrosion of medical devices is of growing concern, yet, the interactions between tribological and electrochemical parameters are not fully understood. Fretting corrosion of CoCr alloy was simulated, and the components of damage were monitored as a function of displacement and contact pressure. Free corrosion potential (Ecorr), intermittent linear polarisation resistance and cathodic potentiostatic methods were used to characterise the system. Interferometry was used to estimate material loss post rubbing. The fretting regime influenced the total material lost and the dominant degradation mechanism. At high contact pressures and low displacements, pure corrosion was dominant with wear and its synergies becoming more important as the contact pressure and displacement decreased and increased, respectively. In some cases, an antagonistic effect from the corrosion-enhanced wear contributor was observed suggesting that film formation and removal may be present. The relationship between slip mechanism and the contributors to tribocorrosion degradation is presented.

  20. Effects of soil organic matter on the development of the microbial polycyclic aromatic hydrocarbons (PAHs) degradation potentials

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Y.; Zhang, N.; Xue, M.; Lu, S.T. [Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871 (China); Tao, S., E-mail: taos@urban.pku.edu.c [Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871 (China)

    2011-02-15

    The microbial activity in soils was a critical factor governing the degradation of organic micro-pollutants. The present study was conducted to analyze the effects of soil organic matter on the development of degradation potentials for polycyclic aromatic hydrocarbons (PAHs). Most of the degradation kinetics for PAHs by the indigenous microorganisms developed in soils can be fitted with the Logistic growth models. The microbial activities were relatively lower in the soils with the lowest and highest organic matter content, which were likely due to the nutrition limit and PAH sequestration. The microbial activities developed in humic acid (HA) were much higher than those developed in humin, which was demonstrated to be able to sequester organic pollutants stronger. The results suggested that the nutrition support and sequestration were the two major mechanisms, that soil organic matter influenced the development of microbial PAHs degradation potentials. - Research highlights: PAH degradation kinetics obey Logistic model. Degradation potentials depend on soil organic carbon content. Humin inhibits the development of PAH degradation activity. Nutrition support and sequestration regulate microbial degradation capacity. - Soil organic matter regulated PAH degradation potentials through nutrition support and sequestration.