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Sample records for carrier concentration dependence

  1. Concentration dependent carriers dynamics in CsPbBr3 perovskite nanocrystals film with transient grating

    Science.gov (United States)

    Wang, Yinghui; Wang, Yanting; Dev Verma, Sachin; Tan, Mingrui; Liu, Qinghui; Yuan, Qilin; Sui, Ning; Kang, Zhihui; Zhou, Qiang; Zhang, Han-Zhuang

    2017-05-01

    The concentration dependence of the carrier dynamics is a key parameter to describe the photo-physical properties of semiconductor films. Here, we investigate the carrier dynamics in the CsPbBr3 perovskite nanocrystal film by employing the transient grating (TG) technique with continuous bias light. The concentration of initial carriers is determined by the average number of photons per nanocrystals induced by pump light (⟨N⟩). The multi-body interaction would appear and accelerate the TG dynamics with ⟨N⟩. When ⟨N⟩ is more than 3.0, the TG dynamics slightly changes, which implies that the Auger recombination would be the highest order multi-body interaction in carrier recombination dynamics. The concentration of non-equilibrium carriers in the film is controlled by the average number of photons per nanocrystals excited by continuous bias light (⟨nne⟩). Increasing ⟨nne⟩ would improve the trapping-detrapping process by filling the trapping state, which would accelerate the carrier diffusion and add the complexity of the mono-molecular recombination mechanism. The results should be useful to further understand the mechanism of carrier dynamics in the CsPbBr3 perovskite nanocrystal film and of great importance for the operation of the corresponding optoelectronic devices.

  2. Carrier concentration dependence of the tunability of the dipole resonance peak in optically excited metamaterials

    Science.gov (United States)

    Chatzakis, Ioannis; Luo, Liang; Wang, Jigang; Shen, Nian Hai; Koschny, Thomas; Soukoulis, Costas

    2011-03-01

    Currently, there is strong interest to explore the dynamic control of the electromagnetic properties of metamaterials, which have important implications on their optoelectronic applications. While the design, fabrication and photo-doping of metamaterial/semiconductor structures have been actively pursued, some fundamental issues related to highly photo-excited states, their dynamic tuning and temporal evolution remain open. Using optical-pump terahertz probe spectroscopy, we report on the pump fluence dependence of the electric dipole resonance tunability in metamaterials. We find a previously undiscovered large non-monotonic variation on the strength of the dipole resonance peak with the photo-injected carrier concentration.

  3. Charge-carrier concentration dependence of the hopping mobility in organic materials with Gaussian disorder

    Science.gov (United States)

    Coehoorn, R.; Pasveer, W. F.; Bobbert, P. A.; Michels, M. A. J.

    2005-10-01

    It has recently been demonstrated that the hopping mobility in semiconducting organic materials depends on the charge-carrier concentration. We have analyzed this effect within the framework of six existing semianalytical models, for the case of a Gaussian density of states (DOS). These models were either not applied earlier to the case of a Gaussian DOS, or are shown to require a major modification. The mobility is constant below a certain concentration, which decreases with increasing ratio ŝ of the width of the DOS over the thermal energy kBT , and it increases for larger concentrations. At very high concentrations final state effects limit this increase or even give rise to a decrease. An analytical expression is given for the mobility, μ , in the form of the product of the mobility in the low concentration limit times a concentration (c) and ŝ -dependent enhancement factor. Depending on c , ln(μ) varies approximately linearly with 1/T or with 1/T2 . This finding may lead to a solution for the long-standing controversy between polaron-based and disorder-based hopping models.

  4. Carrier concentration dependence of band gap shift in n-type ZnO:Al films

    Science.gov (United States)

    Lu, J. G.; Fujita, S.; Kawaharamura, T.; Nishinaka, H.; Kamada, Y.; Ohshima, T.; Ye, Z. Z.; Zeng, Y. J.; Zhang, Y. Z.; Zhu, L. P.; He, H. P.; Zhao, B. H.

    2007-04-01

    Al-doped ZnO (AZO) thin films have been prepared by mist chemical vapor deposition and magnetron sputtering. The band gap shift as a function of carrier concentration in n-type zinc oxide (ZnO) was systematically studied considering the available theoretical models. The shift in energy gap, evaluated from optical absorption spectra, did not depend on sample preparations; it was mainly related to the carrier concentrations and so intrinsic to AZO. The optical gap increased with the electron concentration approximately as ne2/3 for ne≤4.2×1019 cm-3, which could be fully interpreted by a modified Burstein-Moss (BM) shift with the nonparabolicity of the conduction band. A sudden decrease in energy gap occurred at 5.4-8.4×1019 cm-3, consistent with the Mott criterion for a semiconductor-metal transition. Above the critical values, the band gap increased again at a different rate, which was presumably due to the competing BM band-filling and band gap renormalization effects, the former inducing a band gap widening and the latter an offsetting narrowing. The band gap narrowing (ΔEBGN) derived from the band gap renormalization effect did not show a good ne1/3 dependence predicated by a weakly interacting electron-gas model, but it was in excellent agreement with a perturbation theory considering different many-body effects. Based on this theory a simple expression, ΔEBGN=Ane1/3+Bne1/4+Cne1/2, was deduced for n-type ZnO, as well as p-type ZnO, with detailed values of A, B, and C coefficients. An empirical relation once proposed for heavily doped Si could also be used to describe well this gap narrowing in AZO.

  5. Carrier concentration dependence of structural disorder in thermoelectric Sn1−xTe

    Directory of Open Access Journals (Sweden)

    Mattia Sist

    2016-09-01

    Full Text Available SnTe is a promising thermoelectric and topological insulator material. Here, the presumably simple rock salt crystal structure of SnTe is studied comprehensively by means of high-resolution synchrotron single-crystal and powder X-ray diffraction from 20 to 800 K. Two samples with different carrier concentrations (sample A = high, sample B = low have remarkably different atomic displacement parameters, especially at low temperatures. Both samples contain significant numbers of cation vacancies (1–2% and ordering of Sn vacancies possibly occurs on warming, as corroborated by the appearance of multiple phases and strain above 400 K. The possible presence of disorder and anharmonicity is investigated in view of the low thermal conductivity of SnTe. Refinement of anharmonic Gram–Charlier parameters reveals marginal anharmonicity for sample A, whereas sample B exhibits anharmonic effects even at low temperature. For both samples, no indications are found of a low-temperature rhombohedral phase. Maximum entropy method (MEM calculations are carried out, including nuclear-weighted X-ray MEM calculations (NXMEM. The atomic electron densities are spherical for sample A, whereas for sample B the Te electron density is elongated along the 〈100〉 direction, with the maximum being displaced from the lattice position at higher temperatures. Overall, the crystal structure of SnTe is found to be defective and sample-dependent, and therefore theoretical calculations of perfect rock salt structures are not expected to predict the properties of real materials.

  6. DFT Study on the Carrier Concentration and Temperature-Dependent Thermoelectric Properties of Antimony Selenide

    Directory of Open Access Journals (Sweden)

    Aditya Jayaraman

    2016-01-01

    Full Text Available We present the thermoelectric properties of Antimony Selenide (Sb2Se3 obtained using first principles calculations. We investigated the electronic band structure using the FP-LAPW method within the sphere of the density functional theory. Thermoelectric properties were calculated using BoltzTrap code using the constant relaxation time (τ approximation at three different temperatures 300 K, 600 K, and 800 K. Seebeck coefficient (S was found to decrease with increasing temperature, electrical conductivity (σ/τ was almost constant in the entire temperature range, and electronic thermal conductivity (κ/τ increased with increasing temperature. With increase in temperature S decreased from 1870 μV/K (at 300 K to 719 μV/K (at 800 K, electronic thermal conductivity increased from 1.56 × 1015 W/m K s (at 300 K to 3.92 × 1015 W/m K s (at 800 K, and electrical conductivity decreased from 22 × 1019/Ω m s (at 300 K to 20 × 1019/Ω m s (at 800 K. The thermoelectric properties were also calculated for different hole concentrations and the optimum concentration for a good thermoelectric performance over a large range of temperatures (from 300 K to 1000 K was found for hole concentration around 1019 cm−3.

  7. Naturally occurring proteinaceous nanoparticles in Coptidis Rhizoma extract act as concentration-dependent carriers that facilitate berberine absorption.

    Science.gov (United States)

    Ma, Bing-Liang; Yin, Chun; Zhang, Bo-Kai; Dai, Yan; Jia, Yi-Qun; Yang, Yan; Li, Qiao; Shi, Rong; Wang, Tian-Ming; Wu, Jia-Sheng; Li, Yuan-Yuan; Lin, Ge; Ma, Yue-Ming

    2016-01-29

    Pharmacological activities of some natural products diminish and even disappear after purification. In this study, we explored the mechanisms underlying the decrease of acute oral toxicity of Coptidis Rhizoma extract after purification. The water solubility, in vitro absorption, and plasma exposure of berberine (the major active compound) in the Coptidis Rhizoma extract were much better than those of pure berberine. Scanning electron microscopy, laser scanning confocal microscopy (LSCM), and dynamic light scattering experiments confirmed that nanoparticles attached to very fine precipitates existed in the aqueous extract solution. The LSCM experiment showed that the precipitates were absorbed with the particles by the mouse intestine. High-speed centrifugation of the extract could not remove the nanoparticles and did not influence plasma exposure or acute oral toxicity. However, after extract dilution, the attached precipitates vanished, although the nanoparticles were preserved, and there were no differences in the acute oral toxicity and plasma exposure between the extract and pure berberine. The nanoparticles were then purified and identified as proteinaceous. Furthermore, they could absorb co-dissolved berberine. Our results indicate that naturally occurring proteinaceous nanoparticles in Coptidis Rhizoma extract act as concentration-dependent carriers that facilitate berberine absorption. These findings should inspire related studies in other natural products.

  8. Dependence of surface plasmon-phonon-polariton in 4 H-SiC on free carrier concentration

    Science.gov (United States)

    Karakachian, H.; Kazan, M.

    2017-03-01

    In this paper, we present a thorough study of the characteristics of the surface modes that result from coupling between plasmon electronic oscillation modes, phonon modes, and electromagnetic modes. The Fourier transform of p-polarized reflectivity measurements were carried out on different 4 H-SiC epilayers differing in their free carrier concentration. The reflectivity measurements were performed with appropriate care to record reflectivity spectra averaged over a wide range of incidence angles. The complex infrared dielectric functions of the measured samples were determined by correcting the values obtained from the conventional Kramers-Kronig conversion technique with reference to Fresnel equations for reflectivity. The obtained dielectric functions were used to compute the effect of the free carrier concentration and the resulting plasmon electronic oscillation on the dispersion spectrum, lifetime, mean propagation length of the bulk, and surface plasmon-phonon-polariton modes. The effect of the free carrier concentration on the temporal coherence of surface plasmon-phonon-polariton is investigated, showing a potential practical method for enhancing the temporal coherence of SiC based thermal sources.

  9. Determination of carrier concentration dependent electron effective mass and scattering time of n-ZnO thin film by terahertz time domain spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tang, J.; Tay, C. B. [Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore); NUSNNI-Nanocore, National University of Singapore, Singapore 117576 (Singapore); Deng, L. Y. [Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore); Zhang, X. H.; Chai, J. W. [Institute of Materials and Research Engineering, Agency for Science, Technology and Research, 3 Research Link, Singapore 117602 (Singapore); Qin, H. [Department of Chemical and Bioengineering, National University of Singapore, Singapore 117542 (Singapore); Liu, H. W. [Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Venkatesan, T. [NUSNNI-Nanocore, National University of Singapore, Singapore 117576 (Singapore); Chua, S. J., E-mail: elecsj@nus.edu.sg [Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore); NUSNNI-Nanocore, National University of Singapore, Singapore 117576 (Singapore); Institute of Materials and Research Engineering, Agency for Science, Technology and Research, 3 Research Link, Singapore 117602 (Singapore)

    2014-01-21

    We demonstrated a novel and widely accessible method for determining the electron effective mass and scattering time of ZnO films with different carrier concentrations by combining terahertz time-domain spectroscopy with Hall measurement. The terahertz time domain spectroscopy (THz-TDS) transmission spectra (0.1–2THz) were well described by Drude model. It is found that electron effective mass varied from 0.23m{sub 0} to 0.26m{sub 0} as the electron concentration changes from 5.9 × 10{sup 17} cm{sup −3} to 4.0 × 10{sup 19} cm{sup −3}. The carrier concentration dependent characteristic is ascribed to the non-parabolicity of conduction band. Free carrier localization mechanism explained the discrepancy in mobilities obtained from THz-TDS and Hall measurements.

  10. Temperature Dependent Luminescent Decay Properties of CdTe Quantum Dot Monolayers: Impact of Concentration on Carrier Trapping

    CERN Document Server

    Murphy, Graham P; Bradley, A Louise

    2016-01-01

    We have investigated the temperature dependence of the photoluminescence spectra and average photoluminescence decay rate of CdTe quantum dot monolayers of different sizes as a function of concentration in the range 77 K to 296 K. It is shown that a simple three level analytic model involving bright and dark exciton states can only describe the lower temperature data but is unable to satisfactorily fit the data over the full temperature range. An extended model which includes external trap states is necessary to fit the data above approximately 150 K. Parameters for the model are obtained using both temporal and spectral data. The model indicates that the efficiency of interaction with trap states increases as the QD monolayer concentration increases, which is likely due to an increase in the density of available traps.

  11. Resistivity, carrier concentration, and carrier mobility of electrochemically deposited CdTe films

    OpenAIRE

    Takahashi, Makoto; Uosaki, Kohei; Kita, Hideaki; Yamaguchi, Shoji

    1986-01-01

    The electrical type, resistivity, and donor or acceptor concentration of CdTe films deposited electrochemically at various potentials were measured. The carrier mobilities of the films were determined from these results. The deposition potential dependence of the mobility was small and the deposition potential dependence of the resistivity was mainly controlled by the deposition potential dependence of the donor or acceptor concentration. The carrier mobilities were very small compared with t...

  12. Terahertz carrier dynamics and dielectric properties of GaN epilayers with different carrier concentrations

    Science.gov (United States)

    Guo, H. C.; Zhang, X. H.; Liu, W.; Yong, A. M.; Tang, S. H.

    2009-09-01

    Using terahertz time-domain spectroscopy, we measured the complex conductivity and dielectric function of n-type GaN with various carrier concentrations on sapphire substrate. The measured complex conductivity, which is due to the free carriers, is well fitted by simple Drude model. The contribution from the lattice vibration to the complex dielectric function increases with the decrease in free carrier concentration. A better fitting of the frequency-dependent complex dielectric response was obtained by considering both of the Drude and the classical damped oscillator model.

  13. Simplified 2DEG carrier concentration model for composite barrier AlGaN/GaN HEMT

    Energy Technology Data Exchange (ETDEWEB)

    Das, Palash, E-mail: d.palash@gmail.com; Biswas, Dhrubes, E-mail: d.palash@gmail.com [Indian Institute of Technology Kharagpur, Kharagpur - 721302, West Bengal (India)

    2014-04-24

    The self consistent solution of Schrodinger and Poisson equations is used along with the total charge depletion model and applied with a novel approach of composite AlGaN barrier based HEMT heterostructure. The solution leaded to a completely new analytical model for Fermi energy level vs. 2DEG carrier concentration. This was eventually used to demonstrate a new analytical model for the temperature dependent 2DEG carrier concentration in AlGaN/GaN HEMT.

  14. Dispersion and polarization dependence of mobile carrier optical nonlinearities

    Science.gov (United States)

    Rustagi, K. C.

    1984-06-01

    Based on the author's earlier work, it is shown that the proper inclusion of carrier scattering should strongly modify the frequency and polarization dependence of optical nonlinearities due to mobile carriers in semiconductors. When the momentum relaxation is much faster than the energy relaxation, the intensity dependent refractive index is enhanced, the induced birefringence becomes a sharp function of the difference frequency ωa-ωb, and a collision induced stimulated Raman effect becomes important.

  15. Influence of carrier flow on the temperature-dependent capacitance-voltage profiles of heterojunction structures

    Science.gov (United States)

    Kwon, S. D.; Lim, H.; Shin, H. K.; Choe, Byung-Doo

    1996-10-01

    We suggest a model which can explain the shifting of carrier concentration peaks in the temperature-dependent capacitance-voltage carrier profiles of heterojunction (HJ) structures. The shift of concentration peaks, which was frequently observed in the inverted isotype HJs was previously attributed to the traps at the heterointerface. The main feature of our model is the role of band offset as a limiter to the test signal current. The model can explain the difference of the peak shift in the carrier profiles of the normal and inverted type HJs. According to this model, the peak shifts at low temperatures occur naturally for the inverted type HJs.

  16. Spectral dependence of carrier lifetimes in silicon for photovoltaic applications

    Science.gov (United States)

    Roller, John F.; Li, Yu-Tai; Dagenais, Mario; Hamadani, Behrang H.

    2016-12-01

    Charge carrier lifetimes in photovoltaic-grade silicon wafers were measured by a spectral-dependent, quasi-steady-state photoconductance technique. Narrow bandwidth light emitting diodes were used to excite excess charge carriers within the material, and the effective lifetimes of these carriers were measured as a function of wavelength and intensity. The dependence of the effective lifetime on the excitation wavelength was then analyzed within the context of an analytical model relating effective lifetime to the bulk lifetime and surface recombination velocity of the material. The agreement between the model and the experimental data provides validation for this technique to be used at various stages of the solar cell production line to investigate the quality of the passivation layers and the bulk properties of the material.

  17. Temperature dependence of carrier capture by defects in gallium arsenide

    Energy Technology Data Exchange (ETDEWEB)

    Wampler, William R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Modine, Normand A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-08-01

    This report examines the temperature dependence of the capture rate of carriers by defects in gallium arsenide and compares two previously published theoretical treatments of this based on multi phonon emission (MPE). The objective is to reduce uncertainty in atomistic simulations of gain degradation in III-V HBTs from neutron irradiation. A major source of uncertainty in those simulations is poor knowledge of carrier capture rates, whose values can differ by several orders of magnitude between various defect types. Most of this variation is due to different dependence on temperature, which is closely related to the relaxation of the defect structure that occurs as a result of the change in charge state of the defect. The uncertainty in capture rate can therefore be greatly reduced by better knowledge of the defect relaxation.

  18. Ohm's Law for a Bipolar Semiconductor: The Role of Carrier Concentration and Energy Nonequilibria

    Science.gov (United States)

    Lashkevych, Igor; Titov, Oleg Yu.; Gurevich, Yuri G.

    2016-09-01

    The effective linear electrical conductivity of a nondegenerate bipolar semiconductor, sandwiched between two metals, is investigated taking into account both its nonequilibrium charge carriers (both electrons and holes) and nonequilibrium temperature. We stress that even in the linear perturbative approximation both carrier concentration and energy nonequilbria arise automatically when an electrical current flows. The expression for the effective electrical conductivity is obtained and shown to depend on the electron and hole electrical conductivity, the thermal conductivity, the bandgap, charge carriers lifetimes, and both bulk and surface recombination rates. The effective electrical conductivity is equal to the classical result, i.e., the sum of the electron and hole electrical conductivities, only if the surface recombination rate at the interface is sufficiently strong or the charge carrier lifetime is sufficiently small. In this article, partial cases are considered, specifically, semiconductors with small and large thermal conductivities, semiconductors with monopolar electron and monopolar holes, strong and weak surface recombination rates, and small and large charge carrier lifetimes. Expressions for the effective electrical conductivity are obtained in all partial cases.

  19. Ohm's Law for a Bipolar Semiconductor: The Role of Carrier Concentration and Energy Nonequilibria

    Science.gov (United States)

    Lashkevych, Igor; Titov, Oleg Yu.; Gurevich, Yuri G.

    2017-01-01

    The effective linear electrical conductivity of a nondegenerate bipolar semiconductor, sandwiched between two metals, is investigated taking into account both its nonequilibrium charge carriers (both electrons and holes) and nonequilibrium temperature. We stress that even in the linear perturbative approximation both carrier concentration and energy nonequilbria arise automatically when an electrical current flows. The expression for the effective electrical conductivity is obtained and shown to depend on the electron and hole electrical conductivity, the thermal conductivity, the bandgap, charge carriers lifetimes, and both bulk and surface recombination rates. The effective electrical conductivity is equal to the classical result, i.e., the sum of the electron and hole electrical conductivities, only if the surface recombination rate at the interface is sufficiently strong or the charge carrier lifetime is sufficiently small. In this article, partial cases are considered, specifically, semiconductors with small and large thermal conductivities, semiconductors with monopolar electron and monopolar holes, strong and weak surface recombination rates, and small and large charge carrier lifetimes. Expressions for the effective electrical conductivity are obtained in all partial cases.

  20. Carrier-dependent magnetic anisotropy of Gd-adsorbed graphene

    Science.gov (United States)

    Lu, Yuan; Zhou, Tie-ge; Shao, Bin; Zuo, Xu; Feng, Min

    2016-05-01

    Using first-principles calculation based on density functional theory, we study the magnetic anisotropy of Gd-adsorbed graphene and its dependence on carrier accumulation. We show that carrier accumulation not only impacts the magnitude of magnetic anisotropy but also switches its sign. Hole accumulation enhances the perpendicular anisotropy up to ˜16 meV per Gd atom, while electron accumulation switches the anisotropy from perpendicular to in-plane direction. Moreover, we find that the first order perturbation of spin-orbit coupling interaction induces a pseudo-gap at Γ for the perpendicular magnetization, which leads to the the anomalous magnetic anisotropy for the neutral composite. Our findings pave the way for magneto-electric materials based on rare-earth-decorated graphene for voltage-controlled spintronics.

  1. Temperature-dependent coherent carrier transport in quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Talukder, Muhammad Anisuzzaman; Menyuk, Curtis R, E-mail: anisuzzaman@umbc.edu [Department of Computer Science and Electrical Engineering, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States)

    2011-08-15

    The temperature dependence of coherent carrier transport in quantum cascade lasers (QCLs) is studied in this paper. It was found that coherent carrier transport in QCLs decreases as the temperature increases because the coherence between the injector and active region energy levels decays at a faster rate with increasing temperature. Calculations show that the coherence time decreases by at least a factor of two as the temperature increases from 100 K to room temperature. Electron transport from the injector regions into the active regions and vice versa is a highly coherent process that becomes less efficient with decreasing coherence time and hence becomes less efficient with increasing temperature. As a consequence, when the temperature increases, the population of the upper lasing levels in active regions decreases, the population of the lower lasing levels increases and performance suffers.

  2. Carrier-dependent magnetic anisotropy of Gd-adsorbed graphene

    Directory of Open Access Journals (Sweden)

    Yuan Lu

    2016-05-01

    Full Text Available Using first-principles calculation based on density functional theory, we study the magnetic anisotropy of Gd-adsorbed graphene and its dependence on carrier accumulation. We show that carrier accumulation not only impacts the magnitude of magnetic anisotropy but also switches its sign. Hole accumulation enhances the perpendicular anisotropy up to ∼16 meV per Gd atom, while electron accumulation switches the anisotropy from perpendicular to in-plane direction. Moreover, we find that the first order perturbation of spin-orbit coupling interaction induces a pseudo-gap at Γ for the perpendicular magnetization, which leads to the the anomalous magnetic anisotropy for the neutral composite. Our findings pave the way for magneto-electric materials based on rare-earth-decorated graphene for voltage-controlled spintronics.

  3. Concentration-Dependent Carbon Diffusivity in Austenite

    Science.gov (United States)

    Gu, Xiaoting; Michal, Gary M.; Ernst, Frank; Kahn, Harold; Heuer, Arthur H.

    2014-08-01

    The diffusion coefficient of carbon in austenite depends on the local carbon concentration. This concentration dependence is particularly noticeable during low-temperature "paraequilibrium" carburization. A critical review of the extensive literature on this topic reveals that an early paper by Asimow provides an excellent description of this substantial concentration dependence. The present analysis suggests that the marked concentration dependence of carbon diffusivity is most likely due to interstitial carbon decreasing the activation energy for carbon jumps from one interstitial site to its neighbor.

  4. Carrier-Envelope-Phase Dependent Dissociation of Hydrogen

    CERN Document Server

    Xu, Han; Laban, D E; Wallace, W C; Kielpinski, D; Sang, R T; Litvinyuk, I V

    2012-01-01

    We studied dependence of dissociative ionization in H2 on carrier-envelope phase (CEP) of few-cycle (6fs) near-infrared (NIR) laser pulses. For low-energy channels, we present the first experimental observation of CEP dependence for total dissociation yield and the highest dwgree of asymmetry reported to date (40%). The observed modulations in both asymmetry and total yield could be understood in terms of interference between different n-photon dissociation pathways - n and (n+1) photon channels for asymmetry, n and (n+2) photon channels for yield - as suggested by the general theory of CEP effects (Roudnev and Esry, Phys. Rev. Lett. 99, 220406 (2007), [1]). The yield modulation is found to be Pi-periodic in CEP, with its phase strongly dependent on fragment kinetic energy (and reversing its sign within the studied energy range), indicating that the dissociation does not simply follow the CEP dependence of maximum electric field, as a naive intuition might suggest. We also find that a positively chirped pulse...

  5. Charge carrier effective mass and concentration derived from combination of Seebeck coefficient and 125Te NMR measurements in complex tellurides

    Science.gov (United States)

    Levin, E. M.

    2016-06-01

    Thermoelectric materials utilize the Seebeck effect to convert heat to electrical energy. The Seebeck coefficient (thermopower), S , depends on the free (mobile) carrier concentration, n , and effective mass, m*, as S ˜m*/n2 /3 . The carrier concentration in tellurides can be derived from 125Te nuclear magnetic resonance (NMR) spin-lattice relaxation measurements. The NMR spin-lattice relaxation rate, 1 /T1 , depends on both n and m* as 1 /T1˜(m*)3/2n (within classical Maxwell-Boltzmann statistics) or as 1 /T1˜(m*)2n2 /3 (within quantum Fermi-Dirac statistics), which challenges the correct determination of the carrier concentration in some materials by NMR. Here it is shown that the combination of the Seebeck coefficient and 125Te NMR spin-lattice relaxation measurements in complex tellurides provides a unique opportunity to derive the carrier effective mass and then to calculate the carrier concentration. This approach was used to study A gxS bxG e50-2xT e50 , well-known GeTe-based high-efficiency tellurium-antimony-germanium-silver thermoelectric materials, where the replacement of Ge by [Ag+Sb] results in significant enhancement of the Seebeck coefficient. Values of both m* and n derived using this combination show that the enhancement of thermopower can be attributed primarily to an increase of the carrier effective mass and partially to a decrease of the carrier concentration when the [Ag+Sb] content increases.

  6. Probing the carrier concentration profiles in phosphorus-implanted germanium using infrared spectroscopic ellipsometry

    Science.gov (United States)

    D'Costa, Vijay Richard; Yeo, Yee-Chia

    2015-02-01

    Spectroscopic ellipsometry with photon energy in the 0.045-0.65 eV range was used to investigate germanium samples implanted with 30 keV phosphorus ions and annealed at 700 °C. The infrared response of implanted layers is dominated by free carrier absorption which is modeled using a Drude oscillator. The carrier concentration profiles were modeled using an error function, and compared with those obtained by electrochemical capacitance-voltage profiling and secondary ion mass spectrometry. In the flat region of the carrier concentration profile, average carrier concentration and mobility of 1.40 × 1019 cm-3 and 336 cm2V-1s-1, respectively, were obtained. A phosphorus diffusivity of ˜1.2 × 10-13 cm2/s was obtained. The mobility versus carrier concentration relationships obtained for the implanted samples are close to the empirical relationship for bulk Ge.

  7. Carrier-dependent temporal processing in an auditory interneuron.

    Science.gov (United States)

    Sabourin, Patrick; Gottlieb, Heather; Pollack, Gerald S

    2008-05-01

    Signal processing in the auditory interneuron Omega Neuron 1 (ON1) of the cricket Teleogryllus oceanicus was compared at high- and low-carrier frequencies in three different experimental paradigms. First, integration time, which corresponds to the time it takes for a neuron to reach threshold when stimulated at the minimum effective intensity, was found to be significantly shorter at high-carrier frequency than at low-carrier frequency. Second, phase locking to sinusoidally amplitude modulated signals was more efficient at high frequency, especially at high modulation rates and low modulation depths. Finally, we examined the efficiency with which ON1 detects gaps in a constant tone. As reflected by the decrease in firing rate in the vicinity of the gap, ON1 is better at detecting gaps at low-carrier frequency. Following a gap, firing rate increases beyond the pre-gap level. This "rebound" phenomenon is similar for low- and high-carrier frequencies.

  8. Graded Carrier Concentration Absorber Profile for High Efficiency CIGS Solar Cells

    Directory of Open Access Journals (Sweden)

    Antonino Parisi

    2015-01-01

    Full Text Available We demonstrate an innovative CIGS-based solar cells model with a graded doping concentration absorber profile, capable of achieving high efficiency values. In detail, we start with an in-depth discussion concerning the parametrical study of conventional CIGS solar cells structures. We have used the wxAMPS software in order to numerically simulate cell electrical behaviour. By means of simulations, we have studied the variation of relevant physical and chemical parameters—characteristic of such devices—with changing energy gap and doping density of the absorber layer. Our results show that, in uniform CIGS cell, the efficiency, the open circuit voltage, and short circuit current heavily depend on CIGS band gap. Our numerical analysis highlights that the band gap value of 1.40 eV is optimal, but both the presence of Molybdenum back contact and the high carrier recombination near the junction noticeably reduce the crucial electrical parameters. For the above-mentioned reasons, we have demonstrated that the efficiency obtained by conventional CIGS cells is lower if compared to the values reached by our proposed graded carrier concentration profile structures (up to 21%.

  9. Interplay between carrier and cationic defect concentration in ferromagnetism of anatase Ti1-xTaxO2 thin films

    Directory of Open Access Journals (Sweden)

    A. Roy Barman

    2012-03-01

    Full Text Available Thin films of Ta incorporated TiO2 grown by pulsed laser deposition under specific growth conditions show room temperature ferromagnetism. Ta introduces carriers and concomitantly cationic defects, the combination of which leads to ferromagnetism. In this paper, we report on the dependence of the carrier and cationic defect density (compensation on various parameters such as oxygen growth pressure, temperature and Ta concentration. Most likely, the Ti vacancies act as magnetic centers and the free electrons help with the exchange leading to ferromagnetism via Ruderman-Kittel-Kasuya-Yosida mechanism.

  10. Charge carrier mobility and concentration as a function of composition in AgPO3-AgI glasses.

    Science.gov (United States)

    Rodrigues, Ana Candida Martins; Nascimento, Marcio Luis Ferreira; Bragatto, Caio Barca; Souquet, Jean-Louis

    2011-12-21

    Conductivity data of the xAgI(1 - x)AgPO(3) system (0 ≤ x ≤ 0.5) were collected in the liquid and glassy states. The difference in the dependence of ionic conductivity on temperature below and above their glass transition temperatures (T(g)) is interpreted by a discontinuity in the charge carrier's mobility mechanisms. Charge carrier displacement occurs through an activated mechanism below T(g) and through a Vogel-Fulcher-Tammann-Hesse mechanism above this temperature. Fitting conductivity data with the proposed model allows one to determine separately the enthalpies of charge carrier formation and migration. For the five investigated compositions, the enthalpy of charge carrier formation is found to decrease, with x, from 0.86 to 0.2 eV, while the migration enthalpy remains constant at ≈0.14 eV. Based on these values, the charge carrier mobility and concentration in the glassy state can then be calculated. Mobility values at room temperature (≈10(-4) cm(2) V(-1) s(-1)) do not vary significantly with the AgI content and are in good agreement with those previously measured by the Hall-effect technique. The observed increase in ionic conductivity with x would thus only be due to an increase in the effective charge carrier concentration. Considering AgI as a weak electrolyte, the change in the effective charge carrier concentration is justified and is correlated to the partial free energy of silver iodide forming a regular solution with AgPO(3).

  11. Concentration of erythrocyte-based magnetic carriers in the bloodstream

    Energy Technology Data Exchange (ETDEWEB)

    Danilov, Y.N.; Il' ina, M.B.; Makharudov, S.Y.; Orekhov, A.N.; Rodchenko, S.A.; Samokhin, G.P.

    1986-04-01

    The writers postulated that magnetic erythrocytes (ME), injected into the bloodstream, may be concentrated in an assigned region of the vascular bed with the aid of the field of a permanent magnet. To test this hypothesis, erythrocytes ''loaded'' with colloidal magnetite were used, and concentrated in experiments in vitro and in vivo. For the experiments in vivo ME were labeled with sodium pertechnetate (Na /SUP 99n/ TcO4) was estimated in ME with a Rackgamma 1270 counter by determining radioactivity in the ME suspension and in the supernatant. For the experiment in vivo, a midline laparotomy was performed on a dog weighing 14 kg under intravenous hexobarbital anesthesia. The distribution of ME was recorded by means of a gamma-camera.

  12. Investigation of Cu2ZnSnS4 thin-film solar cells with carrier concentration gradient

    Science.gov (United States)

    Xu, Jiaxiong

    2016-11-01

    To investigate the effect of carrier concentration gradient on Cu2ZnSnS4 (CZTS) thin-film solar cells, the properties of CZTS solar cells were studied by numerical method. The photovoltaic performances of carrier concentration gradient CZTS solar cells were calculated by the solutions of Poisson's equation, continuity equation, and current density equation using AFors-Het v2.4 program. The carrier concentration gradient was changed to analyze its effect. Compared with CZTS solar cells without carrier concentration gradient, the photovoltaic performances of CZTS solar cells can be enhanced by using carrier concentration gradient absorber. The carrier concentration gradient can extend the distribution region of built-in electric field, which is beneficial to the drift of photo-generated carriers. However, the carrier concentration gradient also affects the recombination and series resistances of solar cells. When the defect density of CZTS layer is high, the photo-generated carriers are affected significantly by recombination, resulting in slight effect of carrier concentration gradient. Therefore, the defect density should be reduced to enhance the effect of carrier concentration gradient on improving conversion efficiency of CZTS thin-film solar cells.

  13. Electron spin resonance study of Er-concentration effect in GaAs;Er,O containing charge carriers

    Energy Technology Data Exchange (ETDEWEB)

    Elmasry, F. [Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501 (Japan); Okubo, S. [Molecular Photoscience Research Center, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501 (Japan); Ohta, H., E-mail: hoht@kobe-u.ac.jp [Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501 (Japan); Molecular Photoscience Research Center, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501 (Japan); Fujiwara, Y. [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2014-05-21

    Er-concentration effect in GaAs;Er,O containing charge carriers (n-type, high resistance, p-type) has been studied by X-band Electron spin resonance (ESR) at low temperature (4.7 K < T < 18 K). Observed A, B, and C types of ESR signals were identical to those observed previously in GaAs:Er,O without carrier. The local structure around Er-2O centers is not affected by carriers because similar angular dependence of g-values was observed in both cases (with/without carrier). For temperature dependence, linewidth and lineshape analysis suggested the existence of Er dimers with antiferromagnetic exchange interaction of about 7 K. Moreover, drastic decrease of ESR intensity for C signal in p-type sample was observed and it correlates with the decrease of photoluminescence (PL) intensity. Possible model for the Er-2O trap level in GaAs:Er,O is discussed from the ESR and PL experimental results.

  14. Characteristics of THz carrier dynamics in GaN thin film and ZnO nanowires by temperature dependent terahertz time domain spectroscopy measurement

    Science.gov (United States)

    Balci, Soner; Baughman, William; Wilbert, David S.; Shen, Gang; Kung, Patrick; Kim, Seongsin Margaret

    2012-12-01

    We present a comprehensive study of the characteristics of carrier dynamics using temperature dependent terahertz time domain spectroscopy. By utilizing this technique in combination with numerical calculations, the complex refractive index, dielectric function, and conductivity of n-GaN, undoped ZnO NWs, and Al-doped ZnO NWs were obtained. The unique temperature dependent behaviors of major material parameters were studied at THz frequencies, including plasma frequency, relaxation time, carrier concentration and mobility. Frequency and temperature dependent carrier dynamics were subsequently analyzed in these materials through the use of the Drude and the Drude-Smith models.

  15. Estimation of background carrier concentration in fully depleted GaN films

    Science.gov (United States)

    Chandrasekar, Hareesh; Singh, Manikant; Raghavan, Srinivasan; Bhat, Navakanta

    2015-11-01

    Buffer leakage is an important parasitic loss mechanism in AlGaN/GaN high electron mobility transistors (HEMTs) and hence various methods are employed to grow semi-insulating buffer layers. Quantification of carrier concentration in such buffers using conventional capacitance based profiling techniques is challenging due to their fully depleted nature even at zero bias voltages. We provide a simple and effective model to extract carrier concentrations in fully depleted GaN films using capacitance-voltage (C-V) measurements. Extensive mercury probe C-V profiling has been performed on GaN films of differing thicknesses and doping levels in order to validate this model. Carrier concentrations as extracted from both the conventional C-V technique for partially depleted films having the same doping concentration, and Hall measurements show excellent agreement with those predicted by the proposed model thus establishing the utility of this technique. This model can be readily extended to estimate background carrier concentrations from the depletion region capacitances of HEMT structures and fully depleted films of any class of semiconductor materials.

  16. Home built equipment for measuring Hall coefficient and charge carrier concentration, mobility and resistivity

    DEFF Research Database (Denmark)

    Borup, Kasper Andersen; Christensen, Mogens; Blichfeld, Anders Bank;

    2011-01-01

    We present here a home built setup for measuring the specific resistivity, hall coefficient, and charge carrier concentration and mobility at elevated temperatures. The system is optimized for measurements of samples ranging between doped semiconductors and high resistivity metals and uses the van...

  17. Concentration Dependent Structure of Block Copolymer Solutions

    Science.gov (United States)

    Choi, Soohyung; Bates, Frank S.; Lodge, Timothy P.

    2015-03-01

    Addition of solvent molecules into block copolymer can induce additional interactions between the solvent and both blocks, and therefore expands the range of accessible self-assembled morphologies. In particular, the distribution of solvent molecules plays a key role in determining the microstructure and its characteristic domain spacing. In this study, concentration dependent structures formed by poly(styrene-b-ethylene-alt-propylene) (PS-PEP) solution in squalane are investigated using small-angle X-ray scattering. This reveals that squalane is essentially completely segregated into the PEP domains. In addition, the conformation of the PS block changes from stretched to nearly fully relaxed (i.e., Gaussian conformation) as amounts of squalane increases. NRF

  18. Analysis of carrier concentration, lifetime, and electron mobility on p-type HgCdTe

    Science.gov (United States)

    Yoo, Sang Dong; Kwack, Kae Dal

    1998-03-01

    Minority carrier transport characteristics of vacancy-doped p-type HgCdTe such as carrier concentration, lifetime, and mobility are investigated. In the calculation of the carrier concentration two acceptor levels—a donor level and a trap level—were taken into account. The acceptor levels have been described by two models—two independent singly ionized levels and a divalent level with two ionization energies. When each model was examined by calculating electron mobility as a function of temperature, the latter was found to be more accurate. Electron mobility as a function of majority carrier concentration was also presented for both n-type and p-type HgCdTe with 0.225 Cd mole fraction. Steady state electron lifetime was computed assuming the acceptor levels and the trap level would act as Schokley-Read-Hall type recombination centers. The calculated results using the divalent acceptor model were in good agreement with the experimental data.

  19. Simultaneous measurement of doping concentration and carrier lifetime in silicon using terahertz time-domain transmission

    Science.gov (United States)

    Lenz, M.; Matheisen, C.; Nagel, M.; Knoch, J.

    2017-02-01

    In this work, we present a measurement approach enabling the simultaneous determination of sheet resistance and carrier lifetime in semiconductor samples. It is based on a classic Terahertz (THz) time-domain transmission spectroscopy scheme extended by quasi-steady state optical excitation. The carrier lifetime is determined by contactless THz probing of the increase in sheet conductance associated with quasi-steady-state excitation. Combining a successive etch-back of the surface with repeated THz measurements yields a depth profile of the doping concentration and the carrier lifetime, which is important for the optimization of the emitter of solar cells, for instance. The viability of our approach is demonstrated by investigating a phosphorous doped emitter of a silicon solar cell with the THz approach and comparing the results with electrochemical capacitance voltage measurements.

  20. Role of carrier concentration in swift heavy ion irradiation induced surface modifications

    Science.gov (United States)

    Gupta, Sushant; Ganesan, V.; Sulania, Indra; Das, B.

    2017-10-01

    Highly conducting SnO2 thin films were prepared by chemical spray pyrolysis technique. One set of as-deposited films were annealed in air for 2 h at 850 °C. These as-deposited and annealed SnO2 thin films were irradiated using gold ions with energy of 120 MeV at different fluences ranging from 1 × 1011 to 3 × 1013 ions/cm2. Electrical measurement shows that as-deposited SnO2 films are in conducting state with n = 3.164 ×1020cm-3 and annealed SnO2 films are in insulating state. The amorphized latent tracks are created only above a certain threshold value of Se, which directly depends on the free electron concentration (n). The electronic energy loss (Se) of 120 MeV Au9+ ions in SnO2 is greater than the threshold energy loss (Seth) required for the latent track/molten zone formation in annealed SnO2 thin film, but is less than Seth required for as-deposited SnO2 film. Therefore, the latent tracks/molten zones are formed in the annealed SnO2 film and not in the as-deposited SnO2 film. Thermal spike model is used for the calculation of threshold energy loss and radius of melted zone. The possible mechanism of the structural changes and surface microstructure evolutions is briefly discussed in the light of ion's energy relaxation processes and target's conductivity. The atomic force microscopy (AFM) study of films shows that the morphologies of irradiated films are linked with carrier concentration of target materials.

  1. Spin-dependent charge carrier recombination in PCBM

    Science.gov (United States)

    Morishita, Hiroki; Baker, William; Waters, David; Baarda, Rachel; Lupton, John; Boehme, Christoph; Utah Spin Electronics Group Collaboration; Lupton Group Collaboration

    2013-03-01

    We present room temperature pulsed electrically detected magnetic resonance (pEDMR) measurements on [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) (electron acceptor) thin film unipolar and bipolar devices. Our study aimed at identifying the dominating spin-dependent transport and recombination processes therein. Experimentally, the devices were operated under a constant positive bias, and the resultant transient current response was then monitored after the application of a short resonant microwave pulse excitation. The measurements did not reveal any observable signal for unipolar electron devices which suggests that spin-dependent transport mechanisms are not dominant in PCBM. However, under bipolar injection, at least two pronounced spin-dependent signals were detected whose magnitudes increased as the devices degraded upon exposure to air. Electrical detection of spin-Rabi beat oscillation revealed that one of these two signals is due to weakly coupled pairs of spins with s =1/2. We therefore attribute this signal to electron-hole recombination. This observation shows that while PCBM is a poor hole conductor, hole injection can be significant.

  2. Effects of Carrier Gas Conditions on Concentration of Alcohol Aqueous Solution by Ultrasonic Atomization

    Science.gov (United States)

    Yasuda, Keiji; Tanaka, Naofumi; Rong, Lei; Nakamura, Masaaki; Li, Li; Oda, Akiyoshi; Kawase, Yasuhito

    2003-05-01

    The effects of carrier gas conditions on the concentration of ethanol by ultrasonic atomization are examined. With increasing height from vessel bottom to gas inlet and outlet, the ethanol content in the accompanied liquid increases and the flow rate of alcohol decreases. The ethanol content in the accompanied liquid becomes lower as the gas velocity becomes higher. The attachment of a demister is effective for the increase of the content in the accompanied liquid.

  3. Effect of interfacial lattice mismatch on bulk carrier concentration and band gap of InN

    Energy Technology Data Exchange (ETDEWEB)

    Kuyyalil, Jithesh [FOTON, UMR 6082, INSA, F-35708 Rennes (France); Tangi, Malleswararao; Shivaprasad, S. M. [Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore-560064 (India)

    2012-10-15

    The issue of ambiguous values of the band gap (0.6 to 2 eV) of InN thin film in literature has been addressed by a careful experiment. We have grown wurtzite InN films by PA-MBE simultaneously on differently modified c-plane sapphire substrates and characterized by complementary structural and chemical probes. Our studies discount Mie resonances caused by metallic In segregation at grain boundaries as the reason for low band gap values ( Almost-Equal-To 0.6 eV) and also the formation of Indium oxides and oxynitrides as the cause for high band gap value ( Almost-Equal-To 2.0 eV). It is observed that polycrystallinity arising from azimuthal miss-orientation of c-oriented wurtzite InN crystals increases the carrier concentration and the band gap values. We have reviewed the band gap, carrier concentration, and effective mass of InN in literature and our own measurements, which show that the Moss-Burstein relation with a non-parabolic conduction band accounts for the observed variation of band gap with carrier concentration.

  4. Effect of free-carrier concentration and optical injection on carrier lifetimes in undoped and iodine doped CdMgTe/CdSeTe double heterostructures grown by molecular beam epitaxy

    Science.gov (United States)

    Sohal, S.; Edirisooriya, M.; Ogedengbe, O. S.; Petersen, J. E.; Swartz, C. H.; LeBlanc, E. G.; Myers, T. H.; Li, J. V.; Holtz, M.

    2016-12-01

    Time-resolved and time integrated photoluminescence (PL) studies are reported for undoped and doped CdMgTe/CdSeTe double heterostructures (DHs) grown by molecular beam epitaxy. Undoped DHs are studied with absorber layer thickness varying from 0.5 to 2.5 µm. The n-type free-carrier concentration is varied ~7  ×  1015, 8.4  ×  1016, and 8.4  ×  1017 cm-3 using iodine as a dopant in different absorber layer thicknesses (0.25-2.0 µm). Optical injection is varied from 1  ×  1010 to 3  ×  1011 photons/pulse/cm2, corresponding to the initial injection of photo-carriers up to ~8  ×  1015 cm-3, to examine the effects of excess carrier concentration on the PL lifetimes. Undoped DHs exhibit an initial rapid decay followed by a slower dependence with carrier lifetimes up to ~485 ns. The dependence of carrier lifetimes on the thickness of the absorber layers (0.5-2.5 µm) suggests interface recombination velocities ({{v}\\operatorname{int}}~ ) ~ 1288 and 238 cm s-1 in the initial and later decay times, respectively, corresponding to high and low photo-carrier concentrations. The Shockley-Read-Hall model is used to describe the results in which variations are observed in {{v}\\operatorname{int}}~ for undoped DHs. The lifetimes of doped DHs show a consistent trend with thickness. The {{v}\\operatorname{int}}~ ~ 80-200 cm s-1 is estimated for doping n ~ 7  ×  1015 cm-3 and 240-410 cm s-1 for n ~ 8.4  ×  1016 cm-3. The observed decrease in carrier lifetimes with increasing n is consistent with growing importance of the radiative recombination rate due to the excess carrier concentration. The effect of carrier concentration on the PL spectrum is also discussed.

  5. Reassessment of the carrier concentration in GeTe-based thermoelectric materials by ^125Te NMR

    Science.gov (United States)

    Levin, E. M.; Acton, J. D.; Schmidt-Rohr, K.

    2012-02-01

    Ge1-xAgx/2Sbx/2Te p-type thermoelectric materials (``TAGS-n'') were studied extensively in the 1970s and then again recently. They exhibit an unusual combination of large thermopower, S, and high hole concentration, p, reported based on the Hall effect data, which has not been explained. To solve this puzzle, we have synthesized GeTe, GeTe:Bi, and TAGS-n with n = 97, 94, 90, and 85 and studied XRD, thermopower, electrical resistivity, thermal conductivity, and ^125Te NMR. Most importantly, we have determined the carrier concentrations using ^125Te NMR spin-lattice relaxation and Knight shift. In GeTe and GeTe:Bi, we found that carrier concentrations generally agree with the values reported from Hall effect. In TAGS-n, they are much lower but agree better with the values expected from S vs. p for GeTe-based materials, solving the puzzle partially. The NMR vs. Hall effect discrepancy in TAGS-n can be due to the presence not only of holes but also electrons generated by Sb atoms, which results in artificially high hole concentration from Hall effect. Even though the true hole concentration is lower than reported, the thermopower of TAGS-n is still significantly larger than that of GeTe and GeTe:Bi at similar carrier concentration. This can be explained by energy filtering enhanced by potential barriers formed due to Ag-Sb pairs in the TAGS-n lattice.

  6. Strong Asymmetric Charge Carrier Dependence in Inelastic Electron Tunneling Spectroscopy of Graphene Phonons.

    Science.gov (United States)

    Natterer, Fabian D; Zhao, Yue; Wyrick, Jonathan; Chan, Yang-Hao; Ruan, Wen-Ying; Chou, Mei-Yin; Watanabe, Kenji; Taniguchi, Takashi; Zhitenev, Nikolai B; Stroscio, Joseph A

    2015-06-19

    The observation of phonons in graphene by inelastic electron tunneling spectroscopy has been met with limited success in previous measurements arising from weak signals and other spectral features which inhibit a clear distinction between phonons and miscellaneous excitations. Utilizing a back-gated graphene device that allows adjusting the global charge carrier density, we introduce an averaging method where individual tunneling spectra at varying charge carrier density are combined into one representative spectrum. This method improves the signal for inelastic transitions while it suppresses dispersive spectral features. We thereby map the total graphene phonon density of states, in good agreement with density functional calculations. Unexpectedly, an abrupt change in the phonon intensity is observed when the graphene charge carrier type is switched through a variation of the back-gate electrode potential. This sudden variation in phonon intensity is asymmetric in the carrier type, depending on the sign of the tunneling bias.

  7. Origin of Meyer-Neldel type compensation behavior in organic semiconductors at large carrier concentrations: Disorder versus thermodynamic description

    Science.gov (United States)

    Fishchuk, I. I.; Kadashchuk, A.; Mityashin, A.; Gavrilyuk, M. M.; Köhler, A.; Bässler, H.; Genoe, J.; Sitter, H.; Sariciftci, N. S.

    2014-12-01

    We have extended an effective medium approximation theory [Fishchuk, Kadashchuk, Genoe, Ullah, Sitter, Singh, Sariciftci, and Bässler, Phys. Rev. B 81, 045202 (2010), 10.1103/PhysRevB.81.045202] to investigate how polaron formation affects the Meyer-Neldel (MN) compensation behavior observed for temperature-dependent charge-carrier transport in disordered organic semiconductors at large carrier concentrations, as realized in organic field-effect transistors (OFETs). We show that the compensation behavior in organic semiconductor thin films can be consistently described for both nonpolaronic and polaronic hopping transport in the framework of the disorder formalism using either Miller-Abrahams or polaron Marcus rates, respectively, provided that the polaron binding energy is small compared to the width of the density of states (DOS) distribution in the system. We argue that alternative models based on thermodynamic reasoning, like the multiexcitation entropy (MEE) model, which assumes charge transport dominated by polarons with multiphonon processes and ignores the energy disorder, are inherently not applicable to describe adequately the charge-carrier transport in disordered organic semiconductors. We have suggested and realized a test experiment based on measurements of the compensation behavior for the temperature-dependent conductivity and mobility in OFET devices to check the applicability of these models. We point out that the MN behavior observed in thin-film OFETs has nothing to do with the genuine MN rule predicted by the MEE approach, but rather it is an apparent effect arising as a consequence of the functional dependence of the partial filling of the DOS in a disordered system with hopping transport. This fact is fully supported by experimental results. The apparent MN energy was found to depend also on the shape of the DOS distribution and polaron binding energy.

  8. Frequency Dependent Harmonic Powers in a Modified Uni-Traveling Carrier (MUTC) Photodetector

    Science.gov (United States)

    2017-01-27

    Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/5651--17-9712 Frequency Dependent Harmonic Powers in a Modified Uni-Traveling Carrier...TELEPHONE NUMBER (include area code) b. ABSTRACT c. THIS PAGE 18. NUMBER OF PAGES 17. LIMITATION OF ABSTRACT Frequency Dependent Harmonic Powers in a...N. Hutchinson (202) 767-9549 Fiber optics Analog photonics We use a drift-diffusion model to study frequency dependent harmonic powers in a

  9. Access to residual carrier concentration in ZnO nanowires by calibrated scanning spreading resistance microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, L., E-mail: lin.wang@insa-lyon.fr; Brémond, G. [Institut des Nanotechnologies de Lyon (INL), Université de Lyon, CNRS UMR 5270, INSA Lyon, Bat. Blaise Pascal, 7 Avenue Jean Capelle, 69621 Villeurbanne (France); Chauveau, J. M. [Centre de Recherche sur l' Hétéro-Epitaxie et ses Applications (CRHEA), CNRS UPR10, rue Bernard Grégory 06560 Valbonne Sophia Antipolis (France); Physics Department, University of Nice Sophia Antipolis (UNS), Parc Valrose, 06103 Nice (France); Brenier, R. [Institut Lumière Matière (ILM), Université de Lyon, CNRS UMR 5306, Université Claude Bernard Lyon 1, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne (France); Sallet, V.; Jomard, F.; Sartel, C. [Groupe d' Étude de la Matière Condensée (GEMaC), CNRS-Université de Versailles St Quentin en Yvelines, Université Paris-Saclay, 45 Avenue des Etats-Unis, 78035 Versailles (France)

    2016-03-28

    Scanning spreading resistance microscopy (SSRM) was performed on non-intentionally doped (nid) ZnO nanowires (NWs) grown by metal-organic chemical vapor deposition in order to measure their residual carrier concentration. For this purpose, an SSRM calibration profile has been developed on homoepitaxial ZnO:Ga multilayer staircase structures grown by molecular beam epitaxy. The Ga density measured by SIMS varies in the 1.7 × 10{sup 17 }cm{sup −3} to 3 × 10{sup 20 }cm{sup −3} range. From measurements on such Ga doped multi-layers, a monotonic decrease in SSRM resistance with increasing Ga density was established, indicating SSRM being a well-adapted technique for two dimensional dopant/carrier profiling on ZnO at nanoscale. Finally, relevant SSRM signal contrasts were detected on nid ZnO NWs, and the residual carrier concentration is estimated in the 1–3 × 10{sup 18 }cm{sup −3} range, in agreement with the result from four-probe measurements.

  10. Reduction of background carrier concentration and lifetime improvement for 4H-SiC C-face epitaxial growth

    Science.gov (United States)

    Nishio, Johji; Kushibe, Mitsuhiro; Asamizu, Hirokuni; Kitai, Hidenori; Kojima, Kazutoshi

    2017-08-01

    Reduction of background carrier concentration was investigated for 4H-SiC C-face epitaxial growth in order to realize ultrahigh-voltage power devices. The quantitative contribution of each epitaxial growth parameter was studied, and it has been found that the growth rate increase and the pressure decrease were more effective than the C/Si ratio. Optimizing the parameters has made it possible to achieve a background carrier concentration of 7.6 × 1013 cm-3 within the whole area of specular 3-in. wafers. In addition to the background carrier concentration reduction, it has been confirmed that small epitaxial film thickness variation, low surface defect density and carrier lifetime fulfill the requirements for the devices. Moreover, in-process propane annealing has been found effective in improving the carrier lifetime. As a result, the longest lifetime value to date of 1.6 µs was obtained for a C-face epitaxial film.

  11. Geometry dependence of Auger carrier capture rates into cone-shaped self-assembled quantum dots

    DEFF Research Database (Denmark)

    Magnúsdóttir, Ingibjörg; Bischoff, Svend; Uskov, A.V.;

    2003-01-01

    We calculate carrier capture rates into cone- and truncated-cone-shaped quantum dots mediated by Auger processes. It is demonstrated that the capture rates depend strongly on both dot size and shape. The importance of phonon-mediated versus the Auger-mediated capture processes is discussed....

  12. Concentration dependent hydrogen diffusion in tungsten

    Science.gov (United States)

    Ahlgren, T.; Bukonte, L.

    2016-10-01

    The diffusion of hydrogen in tungsten is studied as a function of temperature, hydrogen concentration and pressure using Molecular Dynamics technique. A new analysis method to determine diffusion coefficients that accounts for the random oscillation of atoms around the equilibrium position is presented. The results indicate that the hydrogen migration barrier of 0.25 eV should be used instead of the presently recommended value of 0.39 eV. This conclusion is supported by both experiments and density functional theory calculations. Moreover, the migration volume at the saddle point for H in W is found to be positive: ΔVm ≈ 0.488 Å3, leading to a decrease in the diffusivity at high pressures. At high H concentrations, a dramatic reduction in the diffusion coefficient is observed, due to site blocking and the repulsive H-H interaction. The results of this study indicates that high flux hydrogen irradiation leads to much higher H concentrations in tungsten than expected.

  13. Doping concentration dependence of the photoluminescence spectra of n-type GaAs nanowires

    Science.gov (United States)

    Arab, Shermin; Yao, Maoqing; Zhou, Chongwu; Daniel Dapkus, P.; Cronin, Stephen B.

    2016-05-01

    In this letter, the photoluminescence spectra of n-type doped GaAs nanowires, grown by the metal organic chemical vapor deposition method, are measured at 4 K and 77 K. Our measurements indicate that an increase in carrier concentration leads to an increase in the complexity of the doping mechanism, which we attribute to the formation of different recombination centers. At high carrier concentrations, we observe a blueshift of the effective band gap energies by up to 25 meV due to the Burstein-Moss shift. Based on the full width at half maximum (FWHM) of the photoluminescence peaks, we estimate the carrier concentrations for these nanowires, which varies from 6 × 1017 cm-3 (lightly doped), to 1.5 × 1018 cm-3 (moderately doped), to 3.5 × 1018 cm-3 (heavily doped) as the partial pressure of the disilane is varied from 0.01 sccm to 1 sccm during the growth process. We find that the growth temperature variation does not affect the radiative recombination mechanism; however, it does lead to a slight enhancement in the optical emission intensities. For GaAs nanowire arrays measured at room temperature, we observe the same general dependence of band gap, FWHM, and carrier concentration on doping.

  14. Viscosity of magnetite–toluene nanofluids: Dependence on temperature and nanoparticle concentration

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Rahul [Department of Mechanical Engineering, Iowa State University, Ames, IA (United States); Sanchez, Oswaldo [Department of Mathematical Sciences, Morningside College, Sioux City, IA (United States); Ghosh, Suvojit [Department of Engineering Physics, McMaster University, Hamilton, ON (Canada); Kadimcherla, Naveen [Department of Mechanical Engineering, Iowa State University, Ames, IA (United States); Sen, Swarnendu [Department of Mechanical Engineering, Jadavpur University, Kolkata, West Bengal (India); Balasubramanian, Ganesh, E-mail: bganesh@iastate.edu [Department of Mechanical Engineering, Iowa State University, Ames, IA (United States)

    2015-10-23

    Highlights: • Viscosity of magnetite in toluene nanofluid increases monotonically with particle concentration. • Clusters formed at higher particle concentration are monodisperse. • With increasing temperature, viscosity decreases due less fraction of immobile fluid molecules. - Abstract: We examine the dependence of the viscosity of nanofluids, comprised of magnetite nanoparticles dispersed in toluene, on particle concentration and temperature. The nanofluid viscosity increases monotonically with particle concentration. We show that although the nanoparticles aggregate to form clusters with increasing concentration, the cluster size is fairly monodisperse and hence the viscosity can be expressed as a function of only the particle concentration. The viscosity of the nanofluid is found to decrease with temperature, similarly to the characteristics of the carrier liquid. We describe these dependencies through an empirical correlation, since the observations are useful to employ such nanofluids in engineering applications.

  15. Biological evaluation of 5-fluorouracil nanoparticles for cancer chemotherapy and its dependence on the carrier, PLGA

    Directory of Open Access Journals (Sweden)

    Lekha Nair K

    2011-08-01

    drug concentrations is more favorable than regular administration of higher concentration of the drug; our results clearly indicate the potential of 5-FU-loaded PLGA nanoparticles with dependence on carrier combination as controlled release formulation to multiplex the therapeutic effect of cancer chemotherapy.Keywords: 5-FU, poly (D, L-lactic-co-glycolic acid, controlled release

  16. Stimulated Raman Scattering in a Weakly Polar Ⅲ-Ⅴ Semiconductor: Effect of dc Magnetic Field and Free Carrier Concentration

    Institute of Scientific and Technical Information of China (English)

    M. Singh; P. Aghamkar; P. K. Sen

    2007-01-01

    @@ Using the hydrodynamic model of semiconductor plasmas, we perform an analytical investigation of stimulated Raman scattering (SRS) of an electromagnetic pump wave in a transversely magnetized weakly polar semiconductor arising from electron-density perturbations and molecular vibrations of the medium both produced at the longitudinal optical phonon frequency. Assuming that the origin of SRS lies in the third-order susceptibility of the medium, we investigate the growth rate of Stokes mode. The dependence of stimulated Raman gain on the external dc magnetic field strength and free carrier concentration is reported. The possibility of the occurrence of optical phase conjugation via SRS is also studied. The steady-state Raman gain is found to be greatly enhanced by the presence of the strong external dc magnetic field.

  17. Hole traps associated with high-concentration residual carriers in p-type GaAsN grown by chemical beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Elleuch, Omar, E-mail: mr.omar.elleuch@gmail.com; Wang, Li; Lee, Kan-Hua; Demizu, Koshiro; Ikeda, Kazuma; Kojima, Nobuaki; Ohshita, Yoshio; Yamaguchi, Masafumi [Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya 468-8511 (Japan)

    2015-01-28

    The hole traps associated with high background doping in p-type GaAsN grown by chemical beam epitaxy are studied based on the changes of carrier concentration, junction capacitance, and hole traps properties due to the annealing. The carrier concentration was increased dramatically with annealing time, based on capacitance–voltage (C–V) measurement. In addition, the temperature dependence of the junction capacitance (C–T) was increased rapidly two times. Such behavior is explained by the thermal ionization of two acceptor states. These acceptors are the main cause of high background doping in the film, since the estimated carrier concentration from C–T results explains the measured carrier concentration at room temperature using C–V method. The acceptor states became shallower after annealing, and hence their structures are thermally unstable. Deep level transient spectroscopy (DLTS) showed that the HC2 hole trap was composed of two signals, labeled HC21 and HC22. These defects correspond to the acceptor levels, as their energy levels obtained from DLTS are similar to those deduced from C–T. The capture cross sections of HC21 and HC22 are larger than those of single acceptors. In addition, their energy levels and capture cross sections change in the same way due to the annealing. This tendency suggests that HC21 and HC22 signals originate from the same defect which acts as a double acceptor.

  18. Charge carrier density dependence of the hole mobility in poly(p-phenylene vinylene)

    OpenAIRE

    Tanase, C; Blom, PWM; De Leeuw, DM; de Meijer, EJ

    2004-01-01

    The hole transport in various poly(p-phenylene vinylene) (PPV) derivatives has been investigated in field-effect transistors (FETs) and light-emitting diodes (LEDs) as a function of temperature and applied bias. The discrepancy between the experimental hole mobilities extracted from FETs and LEDs based on a single disordered polymeric semiconductor originates from the strong dependence of the hole mobility on the charge carrier density. The microscopic charge transport parameters are directly...

  19. Compensation of native donor doping in ScN: Carrier concentration control and p-type ScN

    Science.gov (United States)

    Saha, Bivas; Garbrecht, Magnus; Perez-Taborda, Jaime A.; Fawey, Mohammed H.; Koh, Yee Rui; Shakouri, Ali; Martin-Gonzalez, Marisol; Hultman, Lars; Sands, Timothy D.

    2017-06-01

    Scandium nitride (ScN) is an emerging indirect bandgap rocksalt semiconductor that has attracted significant attention in recent years for its potential applications in thermoelectric energy conversion devices, as a semiconducting component in epitaxial metal/semiconductor superlattices and as a substrate material for high quality GaN growth. Due to the presence of oxygen impurities and native defects such as nitrogen vacancies, sputter-deposited ScN thin-films are highly degenerate n-type semiconductors with carrier concentrations in the (1-6) × 1020 cm-3 range. In this letter, we show that magnesium nitride (MgxNy) acts as an efficient hole dopant in ScN and reduces the n-type carrier concentration, turning ScN into a p-type semiconductor at high doping levels. Employing a combination of high-resolution X-ray diffraction, transmission electron microscopy, and room temperature optical and temperature dependent electrical measurements, we demonstrate that p-type Sc1-xMgxN thin-film alloys (a) are substitutional solid solutions without MgxNy precipitation, phase segregation, or secondary phase formation within the studied compositional region, (b) exhibit a maximum hole-concentration of 2.2 × 1020 cm-3 and a hole mobility of 21 cm2/Vs, (c) do not show any defect states inside the direct gap of ScN, thus retaining their basic electronic structure, and (d) exhibit alloy scattering dominating hole conduction at high temperatures. These results demonstrate MgxNy doped p-type ScN and compare well with our previous reports on p-type ScN with manganese nitride (MnxNy) doping.

  20. Electrical and thermal transport properties of Y bxCo4Sb12 filled skutterudites with ultrahigh carrier concentrations

    Directory of Open Access Journals (Sweden)

    Yulong Li

    2015-11-01

    Full Text Available For filled skutterudites, element Yb is one of the most common and important fillers. However, the optimal carrier concentration range in Y bxCo4Sb12 filled skutterudites has not been determined as a result of the low Yb filling fraction limit. In this study, a non-equilibrium fabrication process (MS-SPS process, consisting of a melt-spinning method and a spark plasma sintering technique, has been applied to prepare Y bxCo4Sb12 samples. The Yb filling fraction is successfully extended to 0.35, which provides the possibility to clarify the optimal carrier concentration range for Yb-filled skutterudites. High carrier concentrations, with a maximum of around 1 × 1021 cm−3, were achieved in the MS-SPS Y bxCo4Sb12 samples due to the significantly enhanced Yb filling fractions. The phase compositions, lattice parameters, electrical and thermal transport properties of the MS-SPS Y bxCo4Sb12 samples with high carrier concentrations were systematically investigated. An optimal carrier concentration range of around 5 ∼ 6 × 1020 cm−3, corresponding to the actual Yb filling fraction of around 0.21∼0.26, has been determined, which displays the highest thermoelectric performance in Y bxCo4Sb12 thermoelectric materials.

  1. Contactless Spectral-dependent Charge Carrier Lifetime Measurements in Silicon Photovoltaic Materials

    Science.gov (United States)

    Roller, John; Hamadani, Behrang; Dagenais, Mario

    Charge carrier lifetime measurements in bulk or unfinished photovoltaic (PV) materials allow for a more accurate estimate of power conversion efficiency in completed solar cells. In this work, carrier lifetimes in PV-grade silicon wafers are obtained by way of quasi-steady state photoconductance measurements. These measurements use a contactless RF system coupled with varying narrow spectrum input LEDs, ranging in wavelength from 460 nm to 1030 nm. Spectral dependent lifetime measurements allow for determination of bulk and surface properties of the material, including the intrinsic bulk lifetime and the surface recombination velocity. The effective lifetimes are fit to an analytical physics-based model to determine the desired parameters. Passivated and non-passivated samples are both studied and are shown to have good agreement with the theoretical model.

  2. Synthesis of Concentrated Methylcyclohexane as Hydrogen Carrier through Photoelectrochemical Conversion of Toluene and Water.

    Science.gov (United States)

    Kageshima, Yosuke; Minegishi, Tsutomu; Hisatomi, Takashi; Takata, Tsuyoshi; Kubota, Jun; Domen, Kazunari

    2017-02-22

    A photoelectrochemical (PEC) cell consisting of a Pt-loaded carbon black (Pt/C)-based membrane electrode assembly (MEA) and a particulate SrTiO3 photoanode effected selective PEC conversion of toluene and water into methylcyclohexane (MCH) at concentrations up to >99 vol %. This cell exhibited 100 % faradaic efficiency (FE) and 18 % incident-photon-to-current conversion efficiency (IPCE) at 320 nm without an external bias voltage in the PEC hydrogenation of pure toluene. It was also found that strong alkaline conditions are beneficial with the present MEA to suppress the competitive side reaction of hydrogen evolution, resulting in a high FE of 94 % even during MCH production from 1 vol % toluene in MCH. This study successfully demonstrated that the present PEC system is capable of producing concentrated MCH as a promising hydrogen carrier and that MCH production from toluene and water represents a means of artificial photosynthesis. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Hyaluronic acid concentration-mediated changes in structure and function of porous carriers for corneal endothelial cell sheet delivery.

    Science.gov (United States)

    Lai, Jui-Yang

    2016-02-01

    In this study, the effects of hyaluronic acid (HA) concentrations (0.05-1.25wt.%) on the properties of porous carriers for corneal endothelial tissue engineering were investigated. The pore size and porosity gradually increased with decreasing solid content. However, at relatively low HA concentration (i.e., 0.05wt.%), the material samples contained small interior pores and a dense surface skin layer, probably due to no gas bubble effect on the stirring processing of porous microstructures of freeze-dried polysaccharide hydrogels. The carriers prepared from 0.25wt.% HA solution had the highest freezable water content and oxygen and glucose permeability among the samples evaluated. Results of cell viability assays and quantitative real-time reverse transcription polymerase chain reaction analyses showed that the HA concentration-related alteration of porous microstructure dictates the compatibility of biopolymer carriers with corneal endothelial cell (CEC) cultures. In vivo studies demonstrated that the CEC sheet/HA carrier construct implants are therapeutically efficacious in the reconstruction of endothelial scrape-wounded corneas. It is concluded that the polysaccharide concentration is the major factor for affecting the processing of carriers and their structure and function. Porous hydrogels prepared from 0.25wt.% HA solution are capable of delivering bioengineered CEC sheets to the posterior surface of cornea.

  4. Modelling temperature and concentration dependent solid/liquid interfacial energies

    Science.gov (United States)

    Lippmann, Stephanie; Jung, In-Ho; Paliwal, Manas; Rettenmayr, Markus

    2016-01-01

    Models for the prediction of the solid/liquid interfacial energy in pure substances and binary alloys, respectively, are reviewed and extended regarding the temperature and concentration dependence of the required thermodynamic entities. A CALPHAD-type thermodynamic database is used to introduce temperature and concentration dependent melting enthalpies and entropies for multicomponent alloys in the temperature range between liquidus and solidus. Several suitable models are extended and employed to calculate the temperature and concentration dependent interfacial energy for Al-FCC with their respective liquids and compared with experimental data.

  5. Observation of diameter dependent carrier distribution in nanowire-based transistors

    Energy Technology Data Exchange (ETDEWEB)

    Schulze, A; Hantschel, T; Eyben, P; Verhulst, A S; Rooyackers, R; Vandooren, A; Mody, J; Nazir, A; Leonelli, D; Vandervorst, W, E-mail: Andreas.Schulze@imec.be [IMEC, Kapeldreef 75, 3001 Leuven (Belgium)

    2011-05-06

    The successful implementation of nanowire (NW) based field-effect transistors (FET) critically depends on quantitative information about the carrier distribution inside such devices. Therefore, we have developed a method based on high-vacuum scanning spreading resistance microscopy (HV-SSRM) which allows two-dimensional (2D) quantitative carrier profiling of fully integrated silicon NW-based tunnel-FETs (TFETs) with 2 nm spatial resolution. The key elements of our characterization procedure are optimized NW cleaving and polishing steps, the use of in-house fabricated ultra-sharp diamond tips, measurements in high vacuum and a dedicated quantification procedure accounting for the Schottky-like tip-sample contact affected by surface states. In the case of the implanted TFET source regions we find a strong NW diameter dependence of conformality, junction abruptness and gate overlap, quantitatively in agreement with process simulations. In contrast, the arsenic doped drain regions reveal an unexpected NW diameter dependent dopant deactivation. The observed lower drain doping for smaller diameters is reflected in the device characteristics by lower TFET off-currents, as measured experimentally and confirmed by device simulations.

  6. The Concentration Dependence of the Galaxy-Halo Connection

    CERN Document Server

    Lehmann, Benjamin V; Becker, Matthew R; Skillman, Samuel W; Wechsler, Risa H

    2015-01-01

    Empirical methods for connecting galaxies to their dark matter halos have become essential in interpreting measurements of the spatial statistics of galaxies. Among the most successful of these methods is the technique of subhalo abundance matching, which has to date been used to associate galaxy properties with a small set of halo properties. We generalize this set of halo properties to allow variable dependence on halo concentration, and parameterize the degree of concentration dependence with a single parameter. This parameter provides a smooth interpolation between abundance matching to peak halo mass and to peak halo circular velocity. We characterize the influence of this parameter on two-point clustering, the satellite fraction, and the degree of galaxy assembly bias. We also evaluate the degeneracies between the concentration dependence and the scatter in the abundance matching relation. We show that low redshift clustering measurements from SDSS prefer a moderate amount of concentration dependence --...

  7. Interplay between hopping and band transport in high-mobility disordered semiconductors at large carrier concentrations: The case of the amorphous oxide InGaZnO

    Science.gov (United States)

    Fishchuk, I. I.; Kadashchuk, A.; Bhoolokam, A.; de Jamblinne de Meux, A.; Pourtois, G.; Gavrilyuk, M. M.; Köhler, A.; Bässler, H.; Heremans, P.; Genoe, J.

    2016-05-01

    We suggest an analytic theory based on the effective medium approximation (EMA) which is able to describe charge-carrier transport in a disordered semiconductor with a significant degree of degeneration realized at high carrier concentrations, especially relevant in some thin-film transistors (TFTs), when the Fermi level is very close to the conduction-band edge. The EMA model is based on special averaging of the Fermi-Dirac carrier distributions using a suitably normalized cumulative density-of-state distribution that includes both delocalized states and the localized states. The principal advantage of the present model is its ability to describe universally effective drift and Hall mobility in heterogeneous materials as a function of disorder, temperature, and carrier concentration within the same theoretical formalism. It also bridges a gap between hopping and bandlike transport in an energetically heterogeneous system. The key assumption of the model is that the charge carriers move through delocalized states and that, in addition to the tail of the localized states, the disorder can give rise to spatial energy variation of the transport-band edge being described by a Gaussian distribution. It can explain a puzzling observation of activated and carrier-concentration-dependent Hall mobility in a disordered system featuring an ideal Hall effect. The present model has been successfully applied to describe experimental results on the charge transport measured in an amorphous oxide semiconductor, In-Ga-Zn-O (a-IGZO). In particular, the model reproduces well both the conventional Meyer-Neldel (MN) compensation behavior for the charge-carrier mobility and inverse-MN effect for the conductivity observed in the same a-IGZO TFT. The model was further supported by ab initio calculations revealing that the amorphization of IGZO gives rise to variation of the conduction-band edge rather than to the creation of localized states. The obtained changes agree with the one we

  8. Ellipsometry characterization of polycrystalline ZnO layers with the modeling of carrier concentration gradient: Effects of grain boundary, humidity, and surface texture

    Energy Technology Data Exchange (ETDEWEB)

    Sago, Keisuke; Fujiwara, Hiroyuki, E-mail: fujiwara@gifu-u.ac.jp [Center of Innovative Photovoltaic Systems (CIPS), Gifu University, 1-1 Yanagido, Gifu 501-1193 (Japan); Kuramochi, Hideto; Iigusa, Hitoshi; Utsumi, Kentaro [Tokyo Research Laboratory, TOSOH Co., Ltd., 2743-1 Hayakawa, Ayase-shi, Kanagawa 252-1123 (Japan)

    2014-04-07

    Spectroscopic ellipsometry (SE) has been applied to study the effects of grain boundary, humidity, and surface texture on the carrier transport properties of Al-doped ZnO layers fabricated by dc and rf magnetron sputtering. In the SE analysis, the variation in the free carrier absorption toward the growth direction, induced by the ZnO grain growth on foreign substrates, has been modeled explicitly by adopting a multilayer model in which the optical carrier concentration (N{sub opt}) varies continuously with a constant optical mobility (μ{sub opt}). The effect of the grain boundary has been studied by comparing μ{sub opt} with Hall mobility (μ{sub Hall}). The change in μ{sub Hall}/μ{sub opt} indicates a sharp structural transition of the ZnO polycrystalline layer at a thickness of d ∼ 500 nm, which correlates very well with the structure confirmed by transmission electron microscopy. In particular, below the transition thickness, the formation of the high density grain boundary leads to the reduction in the μ{sub Hall}/μ{sub opt} ratio as well as N{sub opt}. As a result, we find that the thickness dependence of the carrier transport properties is almost completely governed by the grain boundary formation. On the other hand, when the ZnO layer is exposed to wet air at 85 °C, μ{sub Hall} reduces drastically with a minor variation of μ{sub opt} due to the enhanced grain boundary scattering. We have also characterized textured ZnO:Al layers prepared by HCl wet etching by SE. The analysis revealed that the near-surface carrier concentration increases slightly after the etching. We demonstrate that the SE technique can be applied to distinguish various rough textured structures (size ∼ 1 μm) of the ZnO layers prepared by the HCl etching.

  9. Concentration and mobility of charge carriers in thin polymers at high temperature determined by electrode polarization modeling

    Science.gov (United States)

    Diaham, Sombel; Locatelli, Marie-Laure

    2012-07-01

    Charge carrier concentration (n0) and effective mobility (μeff) are reported in two polymer films (dielectric spectroscopy data. It is shown that the glass transition temperature (Tg) occurrence has a strong influence on the temperature dependence of n0 and μeff. We carry out that n0 presents two distinct Arrhenius-like behaviors below and above Tg, while μeff exhibits a Vogel-Fulcher-Tamman behavior only above Tg whatever the polymer under study. For polyimide films, n0 varies from 1 × 1014 to 4 × 1016 cm-3 and μeff from 1 × 10-8 to 2 × 10-6 cm2 V-1 s-1 between 200 °C to 400 °C. Poly(amide-imide) films show n0 values between 6 × 1016 and 4 × 1018 cm-3 from 270 °C to 400 °C, while μeff varies between 1 × 10-10 and 2 × 10-7 cm2 V-1 s-1. Considering the activation energies of these physical parameters in the temperature range of investigation, n0 and μeff values appear as coherent with those reported in the literature at lower temperature (Polyimide films appear as good candidates due to nS values less than 1011 cm-2 up to 300 °C.

  10. Optomechanically induced carrier-envelope-phase-dependent effects and their analytical solutions

    Science.gov (United States)

    Ma, Jinyong; Gan, Jinghui; Guccione, Giovanni; Campbell, Geoff T.; Buchler, Ben C.; Lü, Xinyou; Wu, Ying; Lam, Ping Koy

    2017-06-01

    To date, investigations of carrier-envelope-phase (CEP)-dependent effects have been limited to optical pulses with few cycles and high intensity and have not been reported for other types of pulses. Optomechanical systems are shown to have the potential to go beyond these limits. We present an approach using optomechanics to extend the concept of the traditional CEP in the few-cycle regime to mechanical pulses and develop a two-step model to give a physical insight. By adding an auxiliary continuous optical field, we show that a CEP-dependent effect appears even in the multicycle regime of mechanical pulses. We obtain the approximated analytical solutions providing full understanding for these optomechanically induced CEP-dependent effects. In addition, our findings show that one can draw on the optomechanical interaction to revive the CEP-dependent effects on optical pulses with an arbitrary number of cycles and without specific intensity requirements. The effects of CEP, broadly extended to encompass few- and multicycle optical and mechanical pulses, may stimulate a variety of applications in the preparation of a CEP-stabilized pulse, the generation of ultrasonic pulses with a desired shape, the linear manipulation of optical combs, and more.

  11. Compositional dependence of charge carrier transport in kesterite Cu2ZnSnS4 solar cells

    Science.gov (United States)

    Just, Justus; Nichterwitz, Melanie; Lützenkirchen-Hecht, Dirk; Frahm, Ronald; Unold, Thomas

    2016-12-01

    Cu2ZnSnS4 solar cells deposited by thermal co-evaporation have been characterized structurally and electronically to determine the dependence of the electronic properties on the elemental composition of the kesterite phase, which can significantly deviate from the total sample composition. To this end, the kesterite phase content and composition were determined by a combination of X-ray fluorescence and X-ray absorption measurements. The electronic properties, such as carrier density and minority carrier diffusion length, were determined by electron beam induced current measurements and capacitance-voltage profiling. The charge-carrier transport properties are found to strongly depend on the Cu/(Sn+Zn) ratio of the kesterite phase. For the Cu-poor sample, a minority carrier diffusion length of 270 nm and a total collection length of approx. 500 nm are deduced, indicating that current collection should not be an issue in thin devices.

  12. A General Formula for Ion Concentration-Dependent Electrical Conductivities in Polymer Electrolytes

    Directory of Open Access Journals (Sweden)

    Mahardika P. Aji

    2012-01-01

    Full Text Available Problem statement: The aim of this study is to develop a model for describing the effect of ion concentration on the electrical conductivity of polymer electrolytes by considering two mechanisms simultaneously: Enhancements of ion concentration and amorphous phase. Approach: The problems based on new observations in polymer electrolyte when ion concentration in the polymer electrolytes was increased, both the fraction of amorphous phase and the charge carriers increase simultaneously. The model was based on the assumption when ions were inserted into the polymer host, there was an optimum distance between ions at which the ions move easily throughout the polymer. The average distance between ions in the polymer depends on the ion concentration. And we also considered the effect of ion concentration on the amorphous phase in the polymer. Results: We inspected the validity of the model by comparing the model predictions with various experimental data. The new analytical expressions for the electrical conductivity dependent of ion concentration was developed by considering two mechanisms simultaneously in polymer electrolytes, i.e., enhancement of the carries concentration and amorphous phase fraction. Interestingly, most of fitting parameters were not arbitrarily selected, but were derived from the appropriate experimental data. Conclusion: The model can be used to explain the conductivity behavior of other polymer electrolyte systems by selecting appropriately less number of parameters. This model result is fully supported by available experimental data.

  13. Two Dimensional Cahn-Hilliard Equation with Concentration Dependent Mobility and Gradient Dependent Potential

    Institute of Scientific and Technical Information of China (English)

    HUANG RUI; YIN JING-XUE; WANG LIANG-WEI

    2011-01-01

    In this paper we consider the initial boundary value problem of CahnHilliard equation with concentration dependent mobility and gradient dependent potential. By the Lp type estimates and the theory of Morrey spaces, we prove the H(o)der continuity of the solutions. Then we obtain the existence of global classical solutions. The present work can be viewed as an extension to the previous work on the Cahn-Hilliard equation with concentration dependent mobility and potential.

  14. Measuring the mobility of single crystalline wires and its dependence on temperature and carrier density

    Energy Technology Data Exchange (ETDEWEB)

    Amorim, Cleber A; Berengue, Olivia M; Kamimura, Hanay; Chiquito, Adenilson J [NanO LaB-Departamento de Fisica, Universidade Federal de Sao Carlos, CEP 13565-905, CP 676, Sao Carlos, Sao Paulo (Brazil); Leite, Edson R, E-mail: amorim@df.ufscar.br [Laboratorio Interdisciplinar de EletroquImica e Ceramicas, Departamento de Quimica, Universidade Federal de Sao Carlos, CEP 13565-905, CP 676, Sao Carlos, Sao Paulo (Brazil)

    2011-05-25

    Kinetic transport parameters are fundamental for the development of electronic nanodevices. We present new results for the temperature dependence of mobility and carrier density in single crystalline In{sub 2}O{sub 3} samples and the method of extraction of these parameters which can be extended to similar systems. The data were obtained using a conventional Hall geometry and were quantitatively described by the semiconductor transport theory characterizing the electron transport as being controlled by the variable range hopping mechanism. A comprehensive analysis is provided showing the contribution of ionized impurities (low temperatures) and acoustic phonon (high temperatures) scattering mechanisms to the electron mobility. The approach presented here avoids common errors in kinetic parameter extraction from field effect data, serving as a versatile platform for direct investigation of any nanoscale electronic materials.

  15. Size-dependent optical properties and carriers dynamics in CdSe/ZnS quantum dots

    Institute of Scientific and Technical Information of China (English)

    Ma Guo-Hong; Wang Wen-Jun; Gao Xue-Xi; Ma Hong-Liang

    2008-01-01

    Size-dependence of optical properties and energy relaxation in CdSe/ZnS quantum dots (QDs) were investigated by two-colour femtosecond (fs) pump-probe (400/800 nm) and picosecond time-resolved photoluminescence (ps TRPL)experiments. Pump-probe measurement results show that there are two components for the excited carriers relaxation,the fast one with a time constant of several ps arises from the Auger-type recombination, which shows almost particle sizeindependence. The slow relaxation component with a time constant of several decades of ns can be clearly determined with ps TRPL spectroscopy in which the slow relaxation process shows strong particle size-dependence. The decay time constants increase from 21 to 34ns with the decrease of particle size from 3.2 to 2.1 nm. The room-temperature decay lifetime is due to the thermal mixing of bright and dark excitons, and the size-dependence of slow relaxation process can be explained very well in terms of simple three-level model.

  16. Percolation velocity dependence on local concentration in bidisperse granular flows

    Science.gov (United States)

    Jones, Ryan P.; Xiao, Hongyi; Deng, Zhekai; Umbanhowar, Paul B.; Lueptow, Richard M.

    The percolation velocity, up, of granular material in size or density bidisperse mixtures depends on the local concentration, particle size ratio, particle density ratio, and shear rate, γ ˙. Discrete element method computational results were obtained for bounded heap flows with size ratios between 1 and 3 and for density ratios between 1 and 4. The results indicate that small particles percolate downward faster when surrounded by large particles than large particles percolate upward when surrounded by small particles, as was recently observed in shear-box experiments. Likewise, heavy particles percolate downward faster when surrounded by light particles than light particles percolate upward when surrounded by heavy particles. The dependence of up / γ ˙ on local concentration results in larger percolation flux magnitudes at high concentrations of large (or light) particles compared to high concentrations of small (or heavy) particles, while local volumetric flux is conserved. The dependence of up / γ ˙ on local concentration can be incorporated into a continuum model, but the impact on global segregation patterns is usually minimal. Partially funded by Dow Chemical Company and NSF Grant No. CBET-1511450.

  17. Serum concentration of sFas and sFasL in healthy HBsAg carriers, chronic viral hepatitis B and C patients

    Institute of Scientific and Technical Information of China (English)

    Tadeusz Wojciech Lapinski; Oksana Kowalczuk; Danuta Prokopowicz; Lech Chyczewski

    2004-01-01

    AIM: To estimate the amount of apoptosis among healthy HBsAg carriers, patients with chronic HBV infection treated with lamk udine and patients with chronic HCV infection treated with interferon alpha and ribavirin. Activity of apoptosis was evaluated by serum sFas/sFasL concentration measurement.Moreover dependence between apoptosis and HBV-DNA or HCV-RNA levels was studied.METHODS: Eighty-six persons were included into study: 34healthy HBsAg carriers, 33 patients with chronic HBV infection and 19 patients with chronic HCV infection. Serum levels of sFas/sFasL were measured by ELISA assay. HBV-DNA and HCV-RNA were measured by RT-PCR assay. Levels of sFas/sFasL were determined before and 2 and 12 wk after therapy in patients with chronic hepatitis B and C infection.HBV-DNA or HCV-RNA was detected before treatment and 6 mo after treatment.RESULTS: Twenty-four (71%) healthy HBsAg carriers showed HBV-DNA over 105/mL, which was comparable to the patients with chronic hepatitis B. Independently from HBV-DNA levels,the concentration of sFas among healthy HBsAg carriers was comparable to healthy persons. Among patients with chronic hepatitis B and C, the concentration of sFas was significantly higher in comparison to healthy HBsAg carriers and healthy persons. In chronic hepatitis B patients the concentration of sFas was decreased during lamivudine treatment. Among chronic hepatitis C patients the concentration of sFas was increased during IFN alpha and ribavirin treatment. sFasL was not detected in control group. Furthermore sFasL occurred more frequently in chronic hepatitis C patients in comparison to chronic hepatitis B patients.CONCLUSION: There are no correlations between apoptosis and HBV-DNA levels. However ther is an association between apoptosis and activity of inflammation in patients with chronic HBV infection. Apoptosis can be increased in patients with chronic hepatitis C by effective treatment which may be a result of apoptosis stimulation by IFN-α.

  18. Crystal growth and electronic properties of a 3D Rashba material, BiTeI, with adjusted carrier concentrations.

    Science.gov (United States)

    Kanou, Manabu; Sasagawa, Takao

    2013-04-03

    3D Rashba materials can be a leading player in spin-related novel phenomena, ranging from the metallic extreme (unconventional superconductivity) to the transport intermediate (spin Hall effects) to the novel insulating variant (3D topological insulating states). As the essential backbone for both fundamental and applied research of such a 3D Rashba material, this study established the growth of sizeable single crystals of a candidate compound BiTeI with adjusted carrier concentrations. Three techniques (standard vertical Bridgman, modified horizontal Bridgman, and vapour transport) were employed, and BiTeI crystals (>1 × 1 × 0.2 mm(3)) with fundamentally different electronic states from metallic to insulating were successfully grown by the chosen technique. The 3D Rashba electronic states, including the Fermi surface topology, for the corresponding carrier concentrations of the obtained BiTeI crystals were revealed by relativistic first-principles calculations.

  19. High carrier mobility of Sn-doped polycrystalline-Ge films on insulators by thickness-dependent low-temperature solid-phase crystallization

    Science.gov (United States)

    Sadoh, Taizoh; Kai, Yuki; Matsumura, Ryo; Moto, Kenta; Miyao, Masanobu

    2016-12-01

    To realize the advanced thin-film transistors (TFTs), high-carrier-mobility semiconductor films on insulator structures should be fabricated with low-temperature processing conditions (≤500 °C). To achieve this, we investigated the solid-phase crystallization of amorphous-GeSn films on insulating substrates under a wide range of Sn concentrations (0%-20%), film thicknesses (30-500 nm), and annealing temperatures (380-500 °C). Our results reveal that a Sn concentration close to the solid solubility of Sn in Ge (˜2%) is effective in increasing the grain-size of poly-GeSn. In addition, we discovered that the carrier mobility depends on the film thickness, where the mobilities are determined by the counterbalance between two different carrier scattering mechanisms. Here, vacancy-related defects dominate the carrier scattering near the insulating substrates (≤˜120 nm), and grain-size determined by bulk nucleation dominates the grain-boundary scattering of thick films (≥˜200 nm). Consequently, we obtained the maximum mobilities in samples with a Sn concentration of 2% and a film thickness of 200 nm. The effect of increasing the grain-size of poly-GeSn by lowering the annealing temperature was also clarified. By combining these results, a very high carrier mobility of 320 cm2/Vs was obtained at a low temperature of 380 °C. This mobility is about 2.5 times as high as previously reported data for Ge and GeSn films grown at low temperatures (≤500 °C). Our technique therefore opens up the possibility of high-speed TFTs for use in the next generation of electronics.

  20. Optimizing the Dopant and Carrier Concentration of Ca5Al2Sb6 for High Thermoelectric Efficiency

    Science.gov (United States)

    Yan, Yuli; Zhang, Guangbiao; Wang, Chao; Peng, Chengxiao; Zhang, Peihong; Wang, Yuanxu; Ren, Wei

    2016-01-01

    The effects of doping on the transport properties of Ca5Al2Sb6 are investigated using first-principles electronic structure methods and Boltzmann transport theory. The calculated results show that a maximum ZT value of 1.45 is achieved with an optimum carrier concentration at 1000 K. However, experimental studies have shown that the maximum ZT value is no more than 1 at 1000 K. By comparing the calculated Seebeck coefficient with experimental values, we find that the low dopant solubility in this material is not conductive to achieve the optimum carrier concentration, leading a smaller experimental value of the maximum ZT. Interestingly, the calculated dopant formation energies suggest that optimum carrier concentrations can be achieved when the dopants and Sb atoms have similar electronic configurations. Therefore, it might be possible to achieve a maximum ZT value of 1.45 at 1000 K with suitable dopants. These results provide a valuable theoretical guidance for the synthesis of high-performance bulk thermoelectric materials through dopants optimization. PMID:27406178

  1. Effects of Ge substitution in GeTe by Ag or Sb on the Seebeck coefficient and carrier concentration derived from 125Te NMR

    Science.gov (United States)

    Levin, E. M.

    2016-01-01

    GeTe, a self-doping p -type semiconductor where the high free hole concentration is determined by Ge vacancies is a well-known base for high-efficiency A gxS bxG e50 -2 xT e50 (a tellurium-antimony-germanium-silver series) thermoelectric materials. Here it is shown that the replacement of Ge by Ag in GeTe (a A gxG e50 -xT e50 system) significantly decreases the Seebeck coefficient, whereas the replacement by Sb (S bxG e50 -xT e50 ) increases it. These effects can be attributed to a change in carrier concentration and consistent with 125Te NMR spin-lattice relaxation measurements and NMR signal position, which is mostly dependent on the Knight shift. Opposite changes in carrier concentration in A gxG e50 -xT e50 and S bxG e50 -xT e50 can be explained by different valence electron configurations of Ag and Sb compared to that of Ge, which results in a different local electron imbalance and/or in a change in Ge vacancy formation energy and affects the total carrier concentration. Comparison of our data for GeTe, A g2G e48T e50 , and S b2G e48T e50 with those for A g2S b2G e46T e50 shows that the effects from Ag and Sb compensate for each other and supports the formation of [Ag +Sb ] atomic pairs suggested earlier based on theoretical calculations.

  2. Solute concentration-dependent contact angle hysteresis and evaporation stains.

    Science.gov (United States)

    Li, Yueh-Feng; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2014-07-08

    The presence of nonvolatile solutes in a liquid drop on a solid surface can affect the wetting properties. Depending on the surface-activity of the solutes, the extent of contact angle hysteresis (CAH) can vary with their concentration and the pattern of the evaporation stain is altered accordingly. In this work, four types of concentration-dependent CAH and evaporation stains are identified for a water drop containing polymeric additives on polycarbonate. For polymers without surface-activity such as dextran, advancing and receding contact angles (θa and θr) are independent of solute concentrations, and a concentrated stain is observed in the vicinity of the drop center after complete evaporation. For polymers with weak surface-activity such as poly(ethylene glycol) (PEG), both θa and θr are decreased by solute addition, and the stain pattern varies with increasing PEG concentration, including a concentrated stain and a mountain-like island. For polymers with intermediate surface-activity such as sodium polystyrenesulfonate (NaPSS), θa descends slightly, but θr decreases significantly after the addition of a substantial amount of NaPSS, and a ring-like stain pattern is observed. Moreover, the size of the ring stain can be controlled by NaPSS concentration. For polymers with strong surface-activity such as poly(vinylpyrrolidone) (PVP), θa remains essentially a constant, but θr is significantly lowered after the addition of a small amount of PVP, and the typical ring-like stain is seen.

  3. 3-Dimensional Cahn-Hilliard Equation with Concentration Dependent Mobility and Gradient Dependent Potential

    Institute of Scientific and Technical Information of China (English)

    Rui HUANG; Yang CAO

    2011-01-01

    In this paper we investigate the initial boundary value problem of Cahn-Hilliard equation with concentration dependent mobility and gradient dependent potential. By the energy method and the theory of Campanato spaces, we prove the existence and the uniqueness of classical solutions in 3-dimensional space.

  4. Method for producing high carrier concentration p-Type transparent conducting oxides

    Science.gov (United States)

    Li, Xiaonan; Yan, Yanfa; Coutts, Timothy J.; Gessert, Timothy A.; Dehart, Clay M.

    2009-04-14

    A method for producing transparent p-type conducting oxide films without co-doping plasma enhancement or high temperature comprising: a) introducing a dialkyl metal at ambient temperature and a saturated pressure in a carrier gas into a low pressure deposition chamber, and b) introducing NO alone or with an oxidizer into the chamber under an environment sufficient to produce a metal-rich condition to enable NO decomposition and atomic nitrogen incorporation into the formed transparent metal conducting oxide.

  5. Kinetic energy dependence of carrier diffusion in a GaAs epilayer studied by wavelength selective PL imaging

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, S.; Su, L. Q.; Kon, J.; Gfroerer, T.; Wanlass, M. W.; Zhang, Y.

    2017-05-01

    Photoluminescence (PL) imaging has been shown to be an efficient technique for investigating carrier diffusion in semiconductors. In the past, the measurement was typically carried out by measuring at one wavelength (e.g., at the band gap) or simply the whole emission band. At room temperature in a semiconductor like GaAs, the band-to-band PL emission may occur in a spectral range over 200 meV, vastly exceeding the average thermal energy of about 26 meV. To investigate the potential dependence of the carrier diffusion on the carrier kinetic energy, we performed wavelength selective PL imaging on a GaAs double hetero-structure in a spectral range from about 70 meV above to 50 meV below the bandgap, extracting the carrier diffusion lengths at different PL wavelengths by fitting the imaging data to a theoretical model. The results clearly show that the locally generated carriers of different kinetic energies mostly diffuse together, maintaining the same thermal distribution throughout the diffusion process. Potential effects related to carrier density, self-absorption, lateral wave-guiding, and local heating are also discussed.

  6. Thickness dependent charge transfer states and dark carriers density in vacuum deposited small molecule organic photocell

    Science.gov (United States)

    Shekhar, Himanshu; Tzabari, Lior; Solomeshch, Olga; Tessler, Nir

    2016-10-01

    We have investigated the influence of the active layer thickness on the balance of the internal mechanisms affecting the efficiency of copper phthalocyanine - fullerene (C60) based vacuum deposited bulk heterojunction organic photocell. We fabricated a range of devices for which we varied the thickness of the active layer from 40 to 120 nm and assessed their performance using optical and electrical characterization techniques. As reported previously for phthalocyanine:C60, the performance of the device is highly dependent on the active layer thickness and of all the thicknesses we tried, the 40 nm thin active layer device showed the best solar cell characteristic parameters. Using the transfer matrix based optical model, which includes interference effects, we calculated the optical power absorbed in the active layers for the entire absorption band, and we found that this cannot explain the trend with thickness. Measurement of the cell quantum efficiency as a function of light intensity showed that the relative weight of the device internal processes changes when going from 40 nm to 120 nm thick active layer. Electrical modeling of the device, which takes different internal processes into account, allowed to quantify the changes in the processes affecting the generation - recombination balance. Sub gap external quantum efficiency and morphological analysis of the surface of the films agree with the model's result. We found that as the thickness grows the density of charge transfer states and of dark carriers goes up and the uniformity in the vertical direction is reduced.

  7. Analysis of thermoelectric properties of amorphous InGaZnO thin film by controlling carrier concentration

    Directory of Open Access Journals (Sweden)

    Yuta Fujimoto

    2015-09-01

    Full Text Available We have investigated the thermoelectric properties of amorphous InGaZnO (a-IGZO thin films optimized by adjusting the carrier concentration. The a-IGZO films were produced under various oxygen flow ratios. The Seebeck coefficient and the electrical conductivity were measured from 100 to 400 K. We found that the power factor (PF at 300 K had a maximum value of 82 × 10−6 W/mK2, where the carrier density was 7.7 × 1019 cm−3. Moreover, the obtained data was analyzed by fitting the percolation model. Theoretical analysis revealed that the Fermi level was located approximately above the potential barrier when the PF became maximal. The thermoelectric properties were controlled by the relationship between the position of Fermi level and the height of potential energy barriers.

  8. Temperature dependence of carrier spin polarization determined from current-induced domain wall motion in a Co/Ni nanowire

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, K.; Koyama, T.; Hiramatsu, R.; Kobayashi, K.; Ono, T. [Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Chiba, D. [Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho Kawaguchi, Saitama 322-0012 (Japan); Fukami, S. [Green Innovation Research Laboratories, NEC Corporation, 34 Miyukigaoka, Tsukuba, Ibaraki 305-8501 (Japan); Center for Spintronics Integrated Systems, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Tanigawa, H.; Suzuki, T. [RENESAS Electronics Corporation, Sagamihara, Kanagawa 252-5298 (Japan); Ohshima, N. [NEC Energy Device Ltd., 1120 Shimokuzawa, Chuo-ku, Sagamihara, Kanagawa 252-5298 (Japan); Ishiwata, N. [Green Innovation Research Laboratories, NEC Corporation, 34 Miyukigaoka, Tsukuba, Ibaraki 305-8501 (Japan); Nakatani, Y. [University of Electro-communications, Chofu, Tokyo 182-8585 (Japan)

    2012-05-14

    We have investigated the temperature dependence of the current-induced magnetic domain wall (DW) motion in a perpendicularly magnetized Co/Ni nanowire at various temperatures and with various applied currents. The carrier spin polarization was estimated from the measured domain wall velocity. We found that it decreased more with increasing temperature from 100 K to 530 K than the saturation magnetization did.

  9. Spectral Dependence of Nanocrystal Photoionization Probability: The Role of Hot-Carrier Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Padilha, Lazaro A. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Robel, Istvan [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Lee, Doh C. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Nagpal, Prashant [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Pietryga, Jeffrey M. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Klimov, Victor I. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

    2011-01-01

    We conduct measurements of photocharging of PbSe and PbS nanocrystal quantum dots (NQDs) as a function of excitation energy (ℏω). We observe a rapid growth of the degree of photocharging with increasing ℏω, which indicates an important role of hot-carrier transfer in the photoionization process. The corresponding spectral dependence exhibits two thresholds that mark the onsets of weak and strong photocharging. Interestingly, both thresholds are linked to the NQD band gap energy (Eg) and scale as ~1.5Eg and ~3Eg, indicating that the onsets of photoionization are associated with specific nanocrystal states (tentatively, 1P and 2P, respectively) and are not significantly dependent on the energy of external acceptor sites. For all samples, the hot-electron transfer probability increases by nearly 2 orders of magnitude as photon energy increases from 1.5 to 3.5 eV, although at any given wavelength the photoionization probability shows significant sample-to-sample variations (~10–6 to 10–3 for 1.5 eV and ~10–4 to 10–1 for 3.5 eV). In addition to the effect of the NQD size, these variations are likely due to differences in the properties of the NQD surface and/or the number and identity of external acceptor trap sites. The charge-separated states produced by photoionization are characterized by extremely long lifetimes (20 to 85 s) that become longer with increasing NQD size.

  10. Mechanism of Concentration Dependence of Water Diffusivity in Polyacrylate Gels

    Science.gov (United States)

    Mani, Sriramvignesh; Khabaz, Fardin; Khare, Rajesh

    Membrane based separation processes offer an energy efficient alternative to traditional distillation based separation processes. In this work, we focus on the molecular mechanisms underlying the process of separation of dilute ethanol-water mixture using polyacrylate gels as pervaporation membranes. The diffusivities of the components in swollen gels exhibit concentration dependence. We have used molecular dynamics (MD) simulations to study the correlation between the dynamics of solvent (water and ethanol) molecules, polymer dynamics and solvent structure in the swollen gel systems as a function of solvent concentration. Three different polyacrylate gels were studied: (1) poly n-butyl acrylate (PBA), (2) copolymer of butyl acrylate and 2-hydroxyethyl acrylate P(BA50-HEA50), and (3) poly 2-hydroxyethyl acrylate (PHEA). Simulation results show that solvent concentration has a significant effect on local structure of the solvent molecules and chain dynamics; these factors (local structure and chain dynamics), in turn, affect the diffusivity of these molecules. At low concentration, solvent molecules are well dispersed in the gel matrix and form hydrogen bonds with the polymer. Solvent mobility is correlated with polymer mobility in this configuration and consequently water and ethanol molecules exhibit slower dynamics, this effect is especially significant in PHEA gel. At high solvent concentration, water molecules form large clusters in the system accompanied by enhancement in mobility of both the gel network and the solvent molecules.

  11. Effects of Ge replacement in GeTe by Ag or Sb on the Seebeck coefficient and carrier concentration modified by local electron imbalance

    Science.gov (United States)

    Levin, E. M.; Howard, A.; Straszheim, W. E.

    2015-03-01

    XRD, SEM, EDS, 125Te NMR, Seebeck coefficient, and electrical resistivity of AgxGe50-xTe50 and SbxGe50-xTe50 alloys have been studied. Replacement of Ge in GeTe by Sb significantly increases the Seebeck coefficient, while replacement by Ag decreases it. These effects can be attributed to a change in carrier concentration observed via 125Te NMR spin-lattice relaxation measurements and NMR signal position, which mostly depends on the Knight shift. Variation in carrier concentration in AgxGe50-xTe50 and SbxGe50-xTe50 can be attributed to different electron configurations of valence electrons of Ag (4d105s1) and Sb (5s25p3) compared to that of Ge (4s24p2) resulting in local electron imbalances and changing the concentration of charge carrier (holes) generated by Ge vacancies. In contrast, our 125Te NMR and Seebeck coefficient data for Ag2Sb2Ge46Te50 are similar to those observed for GeTe. This shows that effects from Ag and Sb compensate each other and indicates the existence of [Ag +Sb] pairs. The effects of Ge replacement in GeTe by Ag, Sb, or [Ag +Sb] on rhombohedral lattice distortion also have been analyzed. Interplay between the Seebeck coefficient and electrical resistivity in these alloys results in variation of power factor; the value of 45 mW/cm K2, the highest among known tellurides, was found for Sb2Ge48Te50.

  12. Effect of carrier and particle concentration on ultrasound properties of magnetic nanofluids.

    Science.gov (United States)

    Patel, Jay Kumar; Parekh, Kinnari

    2015-01-01

    Ultrasound wave propagation in nanofluids and its rheological behavior has been studied as a function of solid volume fraction, temperature and magnetic field for magnetic nanofluids synthesized in kerosene and transformer oil. Ultrasonic velocity decreases while viscosity increases with increasing volume fraction. The attenuation of ultrasonic wave is explained using dipolar coupling co-efficient which favors oligomer structures with increasing number density of particles. The structure formation increases further with increase in magnetic field which is prominent in transformer oil compared to kerosene. This difference can be due to the structural difference between these two carriers.

  13. Sonophoresis Using Ultrasound Contrast Agents: Dependence on Concentration.

    Directory of Open Access Journals (Sweden)

    Donghee Park

    Full Text Available Sonophoresis can increase skin permeability to various drugs in transdermal drug delivery. Cavitation is recognized as the predominant mechanism of sonophoresis. Recently, a new logical approach to enhance the efficiency of transdermal drug delivery was tried. It is to utilize the engineered microbubble and its resonant frequency for increase of cavitation activity. Actively-induced cavitation with low-intensity ultrasound (less than ~1 MPa causes disordering of the lipid bilayers and the formation of aqueous channels by stable cavitation which indicates a continuous oscillation of bubbles. Furthermore, the mutual interactions of microbubble determined by concentration of added bubble are also thought to be an important factor for activity of stable cavitation, even in different characteristics of drug. In the present study, we addressed the dependence of ultrasound contrast agent concentration using two types of drug on the efficiency of transdermal drug delivery. Two types of experiment were designed to quantitatively evaluate the efficiency of transdermal drug delivery according to ultrasound contrast agent concentration. First, an experiment of optical clearing using a tissue optical clearing agent was designed to assess the efficiency of sonophoresis with ultrasound contrast agents. Second, a Franz diffusion cell with ferulic acid was used to quantitatively determine the amount of drug delivered to the skin sample by sonophoresis with ultrasound contrast agents. The maximum enhancement ratio of sonophoresis with a concentration of 1:1,000 was approximately 3.1 times greater than that in the ultrasound group without ultrasound contrast agent and approximately 7.5 times greater than that in the control group. These results support our hypothesis that sonophoresis becomes more effective in transdermal drug delivery due to the presence of engineered bubbles, and that the efficiency of transdermal drug delivery using sonophoresis with

  14. Aircraft Carriers

    DEFF Research Database (Denmark)

    Nødskov, Kim; Kværnø, Ole

    There are many indications that China is actively researching the design of an aircraft carrier. It is unknown whether China will initiate the actual acquisition of a carrier, but the indications that are available of their research into aircraft carriers and carrier-capable aircraft, as well...... as their purchases of aircraft carrier systems, makes it more than likely that the country is preparing such an acquisition. China has territorial disputes in the South China Sea over the Spratly Islands and is also worried about the security of its sea lines of communications, by which China transports the majority...... of its foreign trade, as well as its oil imports, upon which the country is totally dependent. China therefore has good reasons for acquiring an aircraft carrier to enable it to protect its national interests. An aircraft carrier would also be a prominent symbol of China’s future status as a great power...

  15. Carrier-Density-Dependent Electron Spin Relaxation in GaAs/AlGaAs Multi Quantum Wells

    Institute of Scientific and Technical Information of China (English)

    SHOU Qian; WU Yu; LIU Lu-Ning; WEN Jin-Hui; LAI Tian-Shu; LIN Wei-Zhu

    2005-01-01

    @@ The carrier-density-dependent electron spin relaxation processes in GaAs/AlGaAs multi quantum wells are investigated by a femtosecond pump probe experiment. The spin relaxation time presents two distinguishable trends with the increasing excitation density. It increases from 60ps to 70ps with carrier densities from 1 × 1017 cm-3to 5 × 1017 cm-3 and gradually saturates up to ~80ps at 4 × 1018 cm-3. The experimental results are attributed to the combined competition between collision intensification and scattering potential screening and provide a good experimental confirmation for the theoretical D'yakonov-Perel' mechanism descriptions.

  16. Carrier-Envelop Phase-Dependent Effect on Photoelectron Angular Distribution in Single-Cycle Laser Pulses

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jie; ZHANG Jing-Tao; SUN Zhen-Rong; XU Zhi-Zhan

    2004-01-01

    @@ Using a nonperturbative scattering theory, we study the photoelectron angular distributions (PADs) of Kr atoms irradiated by an infinite sequence of intense single-cycle pulses of circular polarization. We demonstrate the inversion asymmetry of PADs and the dependence of PADs on the carrier-envelop phase of the single-cycle pulses. The inversion asymmetry is caused by the interference between transition channels where the different channels are characterized by different combinations of absorbed-photon numbers in the ionization process. Our results provide a possible method to determine the value of carrier-envelop phase by the detected PADs.

  17. Coherent quantum transport in disordered systems: II. Temperature dependence of carrier diffusion coefficients from the time-dependent wavepacket diffusion method

    Science.gov (United States)

    Zhong, Xinxin; Zhao, Yi; Cao, Jianshu

    2014-04-01

    The time-dependent wavepacket diffusion method for carrier quantum dynamics (Zhong and Zhao 2013 J. Chem. Phys. 138 014111), a truncated version of the stochastic Schrödinger equation/wavefunction approach that approximately satisfies the detailed balance principle and scales well with the size of the system, is applied to investigate the carrier transport in one-dimensional systems including both the static and dynamic disorders on site energies. The predicted diffusion coefficients with respect to temperature successfully bridge from band-like to hopping-type transport. As demonstrated in paper I (Moix et al 2013 New J. Phys. 15 085010), the static disorder tends to localize the carrier, whereas the dynamic disorder induces carrier dynamics. For the weak dynamic disorder, the diffusion coefficients are temperature-independent (band-like property) at low temperatures, which is consistent with the prediction from the Redfield equation, and a linear dependence of the coefficient on temperature (hopping-type property) only appears at high temperatures. In the intermediate regime of dynamic disorder, the transition from band-like to hopping-type transport can be easily observed at relatively low temperatures as the static disorder increases. When the dynamic disorder becomes strong, the carrier motion can follow the hopping-type mechanism even without static disorder. Furthermore, it is found that the memory time of dynamic disorder is an important factor in controlling the transition from the band-like to hopping-type motions.

  18. Ion concentration dependent tRNA folding energy landscapes

    Science.gov (United States)

    Li, Rongzhong; Cho, Samuel

    2013-03-01

    The RNA folding is highly dependent on the ionic conditions of its environment in the cell because the surrounding ions electrostatically screen the charged phosphates that line the RNA backbone. Recent studies (Cho, Pincus, and Thirumalai, PNAS, 2007; Biyun, Cho, and Thirumalai, JACS, 2011) demonstrated that the coarse-grained model we use accurately captures the RNA folding mechanisms by incorporating a Debye-Huckel potential to screen the electrostatics. We compare the ion-concentration dependent tRNA folding mechanism to the classical thermodynamic melting profiles of Crothers and co-workers, and we observe excellent agreement. We also supported our findings by performing empirical force field MD simulations with CHARMM and AMBER, and we observe remarkably comparable qualitative similarities between the average base-base distances from simulations and the empirically measured base-stacking potentials from the well-known Turner's Rules.

  19. Concentration-Dependent Diffusion Instability in Reactive Miscible Fluids

    CERN Document Server

    Bratsun, Dmitry; Mizev, Alexey; Mosheva, Elena

    2015-01-01

    We report new chemoconvective pattern formation phenomena observed in a two-layer system of miscible fluids filling a vertical Hele-Shaw cell. We show both experimentally and theoretically that the concentration-dependent diffusion coupled with the frontal acid-base neutralization can give rise to formation of the local unstable zone low in density resulting in a perfectly regular cell-type convective pattern. The described effect gives an example of yet another powerful mechanism which allows the reaction-diffusion processes to govern the flow of reacting fluids under gravity condition.

  20. Concentration-dependent diffusion instability in reactive miscible fluids

    Science.gov (United States)

    Bratsun, Dmitry; Kostarev, Konstantin; Mizev, Aleksey; Mosheva, Elena

    2015-07-01

    We report on chemoconvective pattern formation phenomena observed in a two-layer system of miscible fluids filling a vertical Hele-Shaw cell. We show both experimentally and theoretically that the concentration-dependent diffusion coupled with frontal acid-base neutralization can give rise to the formation of a local unstable zone low in density, resulting in a perfectly regular cell-type convective pattern. The described effect gives an example of yet another powerful mechanism which allows the reaction-diffusion processes to govern the flow of reacting fluids under gravity conditions.

  1. Carrier density dependence of plasmon-enhanced nonradiative energy transfer in a hybrid quantum well-quantum dot structure.

    Science.gov (United States)

    Higgins, L J; Karanikolas, V D; Marocico, C A; Bell, A P; Sadler, T C; Parbrook, P J; Bradley, A L

    2015-01-26

    An array of Ag nanoboxes fabricated by helium-ion lithography is used to demonstrate plasmon-enhanced nonradiative energy transfer in a hybrid quantum well-quantum dot structure. The nonradiative energy transfer, from an InGaN/GaN quantum well to CdSe/ZnS nanocrystal quantum dots embedded in an ~80 nm layer of PMMA, is investigated over a range of carrier densities within the quantum well. The plasmon-enhanced energy transfer efficiency is found to be independent of the carrier density, with an efficiency of 25% reported. The dependence on carrier density is observed to be the same as for conventional nonradiative energy transfer. The plasmon-coupled energy transfer enhances the QD emission by 58%. However, due to photoluminescence quenching effects an overall increase in the QD emission of 16% is observed.

  2. Characterization of naproxen-loaded solid SMEDDSs prepared by spray drying: the effect of the polysaccharide carrier and naproxen concentration.

    Science.gov (United States)

    Čerpnjak, Katja; Zvonar, Alenka; Vrečer, Franc; Gašperlin, Mirjana

    2015-05-15

    The purpose of this study was to prepare solid SMEDDS (sSMEDDS) particles produced by spray-drying using maltodextrin (MD), hypromellose (HPMC), and a combination of the two as a solid carrier. Naproxen (NPX) as the model drug was dissolved (at 6% concentration) or partially suspended (at 18% concentration) in a liquid SMEDDS composed of Miglyol(®) 812, Peceol™, Gelucire(®) 44/14, and Solutol(®) HS 15. Among the sSMEDDSs tested, the MD-based sSMEDDSs (with a granular, smooth-surfaced, microspherical appearance) preserved the self-microemulsifying properties of liquid SMEDDSs and exhibited dissolution profiles similar to those of liquid SMEDDSs, irrespective of the concentration of NPX. In contrast, HPMC-based sSMEDDSs (irregular-shaped microparticles) exhibited slightly prolonged release times due to the polymeric nature of the carrier. Differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), and Raman mapping analysis confirmed molecularly dissolved NPX (at 6% of drug loading), whereas at 18% NPX loading drug is partially molecularly dissolved and partially in the crystalline state.

  3. Variation of carrier concentration and interface trap density in 8MeV electron irradiated c-Si solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, Sathyanarayana, E-mail: asharao76@gmail.com; Rao, Asha, E-mail: asharao76@gmail.com [Department of Physics, Mangalore Institute of Technology and Engineering, Moodabidri, Mangalore-574225 (India); Krishnan, Sheeja [Department of Physics, Sri Devi Institute of Technology, Kenjar, Mangalore-574142 (India); Sanjeev, Ganesh [Microtron Centre, Department of Physics, Mangalore University, Mangalagangothri-574199 (India); Suresh, E. P. [Solar Panel Division, ISRO Satellite Centre, Bangalore-560017 (India)

    2014-04-24

    The capacitance and conductance measurements were carried out for c-Si solar cells, irradiated with 8 MeV electrons with doses ranging from 5kGy – 100kGy in order to investigate the anomalous degradation of the cells in the radiation harsh environments. Capacitance – Voltage measurements indicate that there is a slight reduction in the carrier concentration upon electron irradiation due to the creation of radiation induced defects. The conductance measurement results reveal that the interface state densities and the trap time constant increases with electron dose due to displacement damages in c-Si solar cells.

  4. Dependency of soil activity concentration on soil -biota concentration ratio of radionuclides for earthworm

    Energy Technology Data Exchange (ETDEWEB)

    Keum, Dong Kwon; Kim, Byeong Ho; Jun, In; Lim, Kwang Muk; Choi, Yong Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-05-15

    The transfer of radionuclides to wildlife (non-human biota) is normally quantified using an equilibrium concentration ratio (CR{sub eq}), defined as the radionuclide activity concentration in the whole organism (fresh weight) divided by that in the media (dry weight for soil). The present study describes the effect of soil radionuclide activity concentration on the transfer of {sup 137}Cs, {sup 85}Sr and {sup 65}Zn to a functionally important wildlife group, annelids, using a commonly studied experimental worm (E.andrei). Time-dependent whole body concentration ratios of {sup 137}Cs, {sup 85}Sr and {sup 65}Zn for the earthworm were experimentally measured for artificially contaminated soils with three different activity concentrations for each radionuclide which were considerably higher than normal background levels. Two parameters of a first order kinetic model, the equilibrium concentration ratio (CR{sub eq}) and the effective loss rate constant (k), were estimated by comparison of experimental CR results with the model prediction

  5. Determination of the carrier concentration in CdSe crystals from the effective infrared absorption coefficient measured by means of the photothermal infrared radiometry

    Energy Technology Data Exchange (ETDEWEB)

    Pawlak, M. [Nicolaus Copernicus University, Faculty of Physics, Astronomy and Informatics, Institute of Physics, Torun (Poland)

    2014-11-11

    In this paper, a non-contact method that allows to determine the carrier concentration in CdSe crystals is presented. The method relies on the measurement of the effective infrared absorption coefficient by means of the photothermal infrared radiometry (PTR). In order to obtain the effective infrared absorption coefficient and thermal diffusivity, the frequency characteristics of the PTR signal were analyzed in the frame of a one-dimensional heat transport model for infrared semitransparent crystals. The carrier concentrations were estimated using a theory introduced by Ruda and a recently proposed normalization procedure for the PTR signal. The deduced carrier concentrations of the investigated CdSe crystals are in reasonable agreement with those obtained using Hall measurements and infrared spectroscopy. The method presented in this paper can also be applied to other semiconductors with the carrier concentration in the range of 10{sup 14}-10{sup 17} cm{sup -3}. (orig.)

  6. Determination of the carrier concentration in CdSe crystals from the effective infrared absorption coefficient measured by means of the photothermal infrared radiometry

    Science.gov (United States)

    Pawlak, M.

    2015-01-01

    In this paper, a non-contact method that allows to determine the carrier concentration in CdSe crystals is presented. The method relies on the measurement of the effective infrared absorption coefficient by means of the photothermal infrared radiometry (PTR). In order to obtain the effective infrared absorption coefficient and thermal diffusivity, the frequency characteristics of the PTR signal were analyzed in the frame of a one-dimensional heat transport model for infrared semitransparent crystals. The carrier concentrations were estimated using a theory introduced by Ruda and a recently proposed normalization procedure for the PTR signal. The deduced carrier concentrations of the investigated CdSe crystals are in reasonable agreement with those obtained using Hall measurements and infrared spectroscopy. The method presented in this paper can also be applied to other semiconductors with the carrier concentration in the range of 1014-1017 cm-3.

  7. Characterization of cross-linked porous gelatin carriers and their interaction with corneal endothelium: biopolymer concentration effect.

    Directory of Open Access Journals (Sweden)

    Jui-Yang Lai

    Full Text Available Cell sheet-mediated tissue regeneration is a promising approach for corneal reconstruction. However, the fragility of bioengineered corneal endothelial cell (CEC monolayers allows us to take advantage of cross-linked porous gelatin hydrogels as cell sheet carriers for intraocular delivery. The aim of this study was to further investigate the effects of biopolymer concentrations (5-15 wt% on the characteristic and safety of hydrogel discs fabricated by a simple stirring process combined with freeze-drying method. Results of scanning electron microscopy, porosity measurements, and ninhydrin assays showed that, with increasing solid content, the pore size, porosity, and cross-linking index of carbodiimide treated samples significantly decreased from 508±30 to 292±42 µm, 59.8±1.1 to 33.2±1.9%, and 56.2±1.6 to 34.3±1.8%, respectively. The variation in biopolymer concentrations and degrees of cross-linking greatly affects the Young's modulus and swelling ratio of the gelatin carriers. Differential scanning calorimetry measurements and glucose permeation studies indicated that for the samples with a highest solid content, the highest pore wall thickness and the lowest fraction of mobile water may inhibit solute transport. When the biopolymer concentration is in the range of 5-10 wt%, the hydrogels have high freezable water content (0.89-0.93 and concentration of permeated glucose (591.3-615.5 µg/ml. These features are beneficial to the in vitro cultivation of CECs without limiting proliferation and changing expression of ion channel and pump genes such as ATP1A1, VDAC2, and AQP1. In vivo studies by analyzing the rabbit CEC morphology and count also demonstrate that the implanted gelatin discs with the highest solid content may cause unfavorable tissue-material interactions. It is concluded that the characteristics of cross-linked porous gelatin hydrogel carriers and their triggered biological responses are in relation to biopolymer

  8. Dosage prediction via estimation of shell thickness and concentration of drug carrier with microbubbles.

    Science.gov (United States)

    Lu, S J; Chuang, C Y; Tsao, Jenho

    2007-01-01

    For drug delivery applications, dosage prediction before release and estimation after release are required functions. In this study, we attempted to establish a method to evaluate liposome concentrations and liposome shell thickness for dosage prediction. We use the Trilling model with parameter of phospholipids bilayers to simulate the frequency responses under the different acoustic pressure and establish an experimental protocol to evaluate the liposome concentrations and the liposome shell thickness. Our results illustrate the changes on the signal strength for different concentrations and show that it is relatively stable to estimate the concentrations when the cycles are lower (15 cycles). Besides, it is verified that the second harmonic signal is more sensitive in analyzing different concentrations. On the other hand, it is proved that the liposome shell thickness affect signal strength and thinner thickness will increase the second harmonic response. Therefore, in accordance with the theoretical and experimental results, we would be able to estimate the concentration and the shell thickness of the liposomes. By numerical analysis methods, dosage prediction would be built.

  9. Power dependence of terahertz carrier frequency in a plasma-based two-color generation process

    Science.gov (United States)

    Zhao, Ji; Zhang, Liang-Liang; Luo, Yi-Man; Wu, Tong; Zhang, Cun-Lin; Zhao, Yue-Jin

    2014-12-01

    We conduct a frequency spectrum experiment to investigate terahertz (THz) emissions from laser-induced air plasma under different laser incident powers. The frequency spectra are measured using both air-biased-coherent detection and a Michelson interferometer. The red-shift of the THz pulse carrier frequency is observed as a response to increased pump power. These phenomena are related to plasma collisions and can be explained by the plasma collision model. Based on these findings, it is apparent that the tuning of the THz carrier frequency can be achieved through regulation of the pump beam.

  10. Magnetic-Phase Dependence of the Spin Carrier Mean Free Path in Graphene Nanoribbons

    Science.gov (United States)

    Li, Jing; Niquet, Yann-Michel; Delerue, Christophe

    2016-06-01

    We show theoretically that the intrinsic (phonon-limited) carrier mobility in graphene nanoribbons is considerably influenced by the presence of spin-polarized edge states. When the coupling between opposite edges switches from antiferromagnetic to ferromagnetic with increasing carrier density, the current becomes spin polarized and the mean free path rises from 10 nm to micrometers. In the ferromagnetic state, the current flows through one majority-spin channel which is ballistic over micrometers and several minority-spin channels with mean free paths as low as 1 nm. These features predicted in technology-relevant conditions could be nicely exploited in spintronic devices.

  11. Concentration-dependent RDX uptake and remediation by crop plants.

    Science.gov (United States)

    Chen, Diejun; Liu, Z Lewis; Banwart, Wanye

    2011-07-01

    The potential RDX contamination of food chain from polluted soil is a significant concern in regards to both human health and environment. Using a hydroponic system and selected soils spiked with RDX, this study disclosed that four crop plant species maize (Zea mays), sorghum (Sorghum sudanese), wheat (Triticum aestivum), and soybean (Glycine max) were capable of RDX uptake with more in aerial parts than roots. The accumulation of RDX in the plant tissue is concentration-dependent up to 21 mg RDX/L solution or 100 mg RDX/kg soil but not proportionally at higher RDX levels from 220 to 903 mg/kg soil. While wheat plant tissue harbored the highest RDX concentration of 2,800 μg per gram dry biomass, maize was able to remove a maximum of 3,267 μg RDX from soil per pot by five 4-week plants at 100 mg/kg of soil. Although RDX is toxic to plants, maize, sorghum, and wheat showed reasonable growth in the presence of the chemical, whereas soybeans were more sensitive to RDX. Results of this study facilitate assessment of the potential invasion of food chain by RDX-contaminated soils.

  12. Concentration and length dependence of DNA looping in transcriptional regulation.

    Directory of Open Access Journals (Sweden)

    Lin Han

    Full Text Available In many cases, transcriptional regulation involves the binding of transcription factors at sites on the DNA that are not immediately adjacent to the promoter of interest. This action at a distance is often mediated by the formation of DNA loops: Binding at two or more sites on the DNA results in the formation of a loop, which can bring the transcription factor into the immediate neighborhood of the relevant promoter. These processes are important in settings ranging from the historic bacterial examples (bacterial metabolism and the lytic-lysogeny decision in bacteriophage, to the modern concept of gene regulation to regulatory processes central to pattern formation during development of multicellular organisms. Though there have been a variety of insights into the combinatorial aspects of transcriptional control, the mechanism of DNA looping as an agent of combinatorial control in both prokaryotes and eukaryotes remains unclear. We use single-molecule techniques to dissect DNA looping in the lac operon. In particular, we measure the propensity for DNA looping by the Lac repressor as a function of the concentration of repressor protein and as a function of the distance between repressor binding sites. As with earlier single-molecule studies, we find (at least two distinct looped states and demonstrate that the presence of these two states depends both upon the concentration of repressor protein and the distance between the two repressor binding sites. We find that loops form even at interoperator spacings considerably shorter than the DNA persistence length, without the intervention of any other proteins to prebend the DNA. The concentration measurements also permit us to use a simple statistical mechanical model of DNA loop formation to determine the free energy of DNA looping, or equivalently, the for looping.

  13. Charge Carriers in Planar and Meso-Structured Organic-Inorganic Perovskites: Mobilities, Lifetimes, and Concentrations of Trap States.

    Science.gov (United States)

    Hutter, Eline M; Eperon, Giles E; Stranks, Samuel D; Savenije, Tom J

    2015-08-06

    Efficient solar cells have been obtained using thin films of solution-processed organic-inorganic perovskites. However, there remains limited knowledge about the relationship between preparation route and optoelectronic properties. We use complementary time-resolved microwave conductivity (TRMC) and photoluminescence (PL) measurements to investigate the charge carrier dynamics in thin planar films of CH3NH3PbI(3-x)Cl(x), CH3NH3PbI3, and their meso-structured analogues. High mobilities close to 30 cm(2)/(V s) and microsecond-long lifetimes are found in thin films of CH3NH3PbI(3-x)Cl(x), compared to lifetimes of only a few hundred nanoseconds in CH3NH3PbI3 and meso-structured perovskites. We describe our TRMC and PL experiments with a global kinetic model, using one set of kinetic parameters characteristic for each sample. We find that the trap density is less than 5 × 10(14) cm(-3) in CH3NH3PbI(3-x)Cl(x), 6 × 10(16) cm(-3) in the CH3NH3PbI3 thin film and ca. 10(15) cm(-3) in both meso-structured perovskites. Furthermore, our results imply that band-to-band recombination is enhanced by the presence of dark carriers resulting from unintentional doping of the perovskites. Finally, our general approach to determine concentrations of trap states and dark carriers is also highly relevant to other semiconductor materials.

  14. Investigation of field-dependent charge carrier generation and recombination in polymer based solar cells by transient extraction currents

    Energy Technology Data Exchange (ETDEWEB)

    Kniepert, Juliane; Blakesley, James; Neher, Dieter [University of Potsdam (Germany)

    2011-07-01

    There is an ongoing discussion as to whether photoinduced charge transfer in P3HT:PCBM solar cells leads to fully separated electrons and holes, independent of an electric field, or Coulombically bound interfacial charge pairs. While recent studies by R.A. Marsh et al. with transient absorption spectroscopy gave clear evidence for the formation and field-induced dissociation of bound polaron pairs, measurements by I.A. Howard et al. were in favour of hot exciton dissociation. Here, we present the results of bias-dependent Time Delayed Collection Field (TDCF) measurements to access directly the density of free charge carriers in P3HT:PCBM blends coated from dichlorobenzene. Solvent annealing was applied to yield a phase-separated morphology and the corresponding solar cells exhibit high values for the external quantum efficiency and fill factor. Our setup allowed us to follow the generation and recombination of photogenerated charges with a so far unattained time resolution of 40 ns. Our experiments show that the number of collected carriers is independent of the applied bias during pulsed illumination implying that extractable carriers in P3HT:PCBM blends are not generated by the field-assisted separation of bound polaron pairs. In addition, our experiments support the view that bimolecular recombination of free carriers is strongly suppressed in phase-separated P3HT:PBCM blends.

  15. Local composition and carrier concentration in Pb0.7Ge0.3Te and Pb0.5Ge0.5Te alloys from 125Te NMR and microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Levin, E M [Ames Laboratory; Kramer, M J [Ames Laboratory; Schmidt-Rohr, K [Ames Laboratory

    2014-11-01

    Pb0.7Ge0.3Te and Pb0.5Ge0.5Te alloys, (i) quenched from 923 K or (ii) quenched and annealed at 573 K for 2 h, have been studied by 125Te NMR, X-ray diffraction, electron and optical microscopy, as well as energy dispersive spectroscopy. Depending on the composition and thermal treatment history, 125Te NMR spectra exhibit different resonance frequencies and spin-lattice relaxation times, which can be assigned to different phases in the alloy. Quenched and annealed Pb0.7Ge0.3Te alloys can be considered as solid solutions but are shown by NMR to have components with various carrier concentrations. Quenched and annealed Pb0.5Ge0.5Te alloys contain GeTe- and PbTe-based phases with different compositions and charge carrier concentrations. Based on the analysis of non-exponential 125Te NMR spin-lattice relaxation, the fractions and carrier concentrations of the various phases have been estimated. Our data show that alloying of PbTe with Ge results in the formation of chemically and electronically inhomogeneous systems. 125Te NMR can be used as an efficient probe to detect the local composition in equilibrium as well as non-equilibrium states, and to determine the local carrier concentrations in complex multiphase tellurides.

  16. Carrier concentration effect and other structure-related parameters on lattice thermal conductivity of Si nanowires

    Indian Academy of Sciences (India)

    IBRAHIM N QADER; M S OMAR

    2017-06-01

    Lattice thermal conductivity (LTC) of Si bulk and nanowires (NWs) with diameter 22, 37, 50, 56, 98 and 115 nm was investigated in the temperature range 3–300 K using a modified Callaway model that contains both longitudinal and transverse modes. Using proper equations, mean bond length, lattice parameter, unit cell volume, mass density, melting temperature, longitudinal and transverse Debye temperature and group velocity for all transverse and longitudinal modes were calculated for each NW diameter mentioned. Surface roughness, Gruneisen parameter and impurity were used as adjustable parameters to fit theoretical results with experimental curves. In addition, values of electron concentration and dislocation density were determined. There are some phonon scattering mechanisms assumed, which are Umklapp and normal processes, imperfections, phonon confinement, NW boundaries, electrons scattering and dislocation. Dislocationdensity less than 10$^{14}$ m$^{−2}$ for NWs and 10$^{12}$ m$^{−2}$ for bulk has no effect on LTC. Also, electron concentration less than 10$^{22}$ m$^{−3}$ for NWs and 10$^{16}$ m$^{−3}$ for the bulk has no effect. On increasing dislocation density and electron concentration, LTC comparably decreases.

  17. Species dependent studies of no-carrier-added {sup 93m}Mo: A green method

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, Swadesh, E-mail: swadeshchem@rediffmail.co [Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India); Nayak, Dalia [Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India)

    2010-10-15

    The present paper reports a combination of radioanalytical and green methodology for the ultra-trace scale speciation of molybdenum. The differential attitude of iron-doped calcium alginate (Fe-CA) and chitosan biopolymers towards no-carrier-added {sup 93m}Mo radionuclide was studied to develop environmentally sustainable speciation methodology in ultra-trace scale. The affinity of {sup 93m}Mo towards the Fe-CA beads is greater than that of chitosan. Species information was obtained by comparing the adsorption profile of {sup 93m}Mo on Fe-CA and chitosan biopolymer with the software code CHEAQS PRO program. From the experimental results it is concluded that no-carrier-added {sup 93m}Mo radionuclide form mononuclear species instead of polynuclear species in aqueous solution. Use of biodegradable, non-toxic biopolymer makes this method a step forward towards green chemistry.

  18. Dopant and carrier concentration in silicon, in equilibrium with SiP precipitates

    Energy Technology Data Exchange (ETDEWEB)

    Solmi, S.; Parisini, A.; Armigliato, A.; Angelucci, R. [CNR-Istituto LAMEL, Bologna (Italy)] [and others

    1995-08-01

    The methods recently reported to study the equilibria hi the Si-As system, were extended to the Si-P. On this line the behaviour of Silicon slices very heavily implanted with 1.5 x 10{sup 17} P{sup +}/cm{sup 2}, was followed by transmission electron microscopy (TEM) and secondary neutral mass spectrometry (SNMS) after annealing at 800, 850, 900 and 1000 C. Precipitation of large monoclinic, and partially orthorhombic, SiP takes place hi the most heavily doped region. From the shape of the SNMS profiles in the dissolution stage of these precipitates, we determined for the First time, the concentration C{sub e} of P hi equilibrium with the conjugate phase: C. = 2.45 x 10{sup 23} exp (- 0.62/ kT) cm{sup -3}, were kT is in eV.

  19. Salicylic acid transport in Ricinus communis involves a pH-dependent carrier system in addition to diffusion.

    Science.gov (United States)

    Rocher, Françoise; Chollet, Jean-François; Legros, Sandrine; Jousse, Cyril; Lemoine, Rémi; Faucher, Mireille; Bush, Daniel R; Bonnemain, Jean-Louis

    2009-08-01

    Despite its important functions in plant physiology and defense, the membrane transport mechanism of salicylic acid (SA) is poorly documented due to the general assumption that SA is taken up by plant cells via the ion trap mechanism. Using Ricinus communis seedlings and modeling tools (ACD LogD and Vega ZZ softwares), we show that phloem accumulation of SA and hydroxylated analogs is completely uncorrelated with the physicochemical parameters suitable for diffusion (number of hydrogen bond donors, polar surface area, and, especially, LogD values at apoplastic pHs and Delta LogD between apoplast and phloem sap pH values). These and other data (such as accumulation in phloem sap of the poorly permeant dissociated form of monohalogen derivatives from apoplast and inhibition of SA transport by the thiol reagent p-chloromercuribenzenesulfonic acid [pCMBS]) lead to the following conclusions. As in intestinal cells, SA transport in Ricinus involves a pH-dependent carrier system sensitive to pCMBS; this carrier can translocate monohalogen analogs in the anionic form; the efficiency of phloem transport of hydroxylated benzoic acid derivatives is tightly dependent on the position of the hydroxyl group on the aromatic ring (SA corresponds to the optimal position) but moderately affected by halogen addition in position 5, which is known to increase plant defense. Furthermore, combining time-course experiments and pCMBS used as a tool, we give information about the localization of the SA carrier. SA uptake by epidermal cells (i.e. the step preceding the symplastic transport to veins) insensitive to pCMBS occurs via the ion-trap mechanism, whereas apoplastic vein loading involves a carrier-mediated mechanism (which is targeted by pCMBS) in addition to diffusion.

  20. Salicylic Acid Transport in Ricinus communis Involves a pH-Dependent Carrier System in Addition to Diffusion1[OA

    Science.gov (United States)

    Rocher, Françoise; Chollet, Jean-François; Legros, Sandrine; Jousse, Cyril; Lemoine, Rémi; Faucher, Mireille; Bush, Daniel R.; Bonnemain, Jean-Louis

    2009-01-01

    Despite its important functions in plant physiology and defense, the membrane transport mechanism of salicylic acid (SA) is poorly documented due to the general assumption that SA is taken up by plant cells via the ion trap mechanism. Using Ricinus communis seedlings and modeling tools (ACD LogD and Vega ZZ softwares), we show that phloem accumulation of SA and hydroxylated analogs is completely uncorrelated with the physicochemical parameters suitable for diffusion (number of hydrogen bond donors, polar surface area, and, especially, LogD values at apoplastic pHs and Δ LogD between apoplast and phloem sap pH values). These and other data (such as accumulation in phloem sap of the poorly permeant dissociated form of monohalogen derivatives from apoplast and inhibition of SA transport by the thiol reagent p-chloromercuribenzenesulfonic acid [pCMBS]) lead to the following conclusions. As in intestinal cells, SA transport in Ricinus involves a pH-dependent carrier system sensitive to pCMBS; this carrier can translocate monohalogen analogs in the anionic form; the efficiency of phloem transport of hydroxylated benzoic acid derivatives is tightly dependent on the position of the hydroxyl group on the aromatic ring (SA corresponds to the optimal position) but moderately affected by halogen addition in position 5, which is known to increase plant defense. Furthermore, combining time-course experiments and pCMBS used as a tool, we give information about the localization of the SA carrier. SA uptake by epidermal cells (i.e. the step preceding the symplastic transport to veins) insensitive to pCMBS occurs via the ion-trap mechanism, whereas apoplastic vein loading involves a carrier-mediated mechanism (which is targeted by pCMBS) in addition to diffusion. PMID:19493970

  1. Resonance effects in thickness-dependent ultrafast carrier and phonon dynamics of topological insulator Bi2Se3

    Science.gov (United States)

    Kim, Sung; Shin, Dong Hee; Kim, Ju Hwan; Jang, Chan Wook; Park, Jun Woo; Lee, Hosun; Choi, Suk-Ho; Kim, Seung Hyun; Yee, Ki-Ju; Bansal, Namrata; Oh, Seongshik

    2016-01-01

    Resonance effects in the thickness-dependent ultrafast carrier and phonon dynamics of topological insulator Bi2Se3 are found irrespective of the kind of substrate by measuring thickness-dependent abrupt changes of pump-probe differential-reflectivity signals (ΔR/R) from Bi2Se3 thin films on four different substrates of poly- and single-crystalline (sc-) ZnO, sc-GaN and SiO2. The absolute peak intensity of the ΔR/R is maximized at ∼t C (6 ∼ 9 quintuple layers), which is not directly related to but is very close to the critical thickness below which the energy gap opens. The intensities of the two phonon modes deduced from the oscillatory behaviors superimposed on the ΔR/R profiles are also peaked at ∼t C for the four kinds of substrates, consistent with the thickness-dependent Raman-scattering behaviors. These resonant effects and others are discussed based on possible physical mechanisms including the effects of three-dimensional carrier depletion and intersurface coupling.

  2. Strain dependent ultrafast carrier dynamics in EuTiO3 films

    Science.gov (United States)

    Li, Zhong-guo; Zhao, Run; Li, Weiwei; Wang, Haiyan; Yang, Hao; Song, Ying-lin

    2014-10-01

    The photocarrier relaxation dynamics of EuTiO3 films have been investigated using femtosecond transient absorption spectroscopy. Two kinds of EuTiO3 films, with and without strain, have been included. In both films, the decay dynamics of 2p-3dt2g transition has a fast (˜2 ps) and slow (ns) components which are independent of the strain. Remarkably, the transient photobleaching of 4f-3dt2g transition is found to be enhanced considerably in the strained film, accompanied with a subnanosecond carrier lifetime. This behavior can be linked to the strain induced band structure modulation. Our results reveal the dynamical interactions in EuTiO3, identifying the critical roles of strain in photo induced phenomena.

  3. Study of carrier recombination transient characteristics in MOCVD grown GaN dependent on layer thickness

    Directory of Open Access Journals (Sweden)

    E. Gaubas

    2013-11-01

    Full Text Available The MOCVD grown GaN epi-layers of different thickness have been examined in order to clarify a role of surface recombination, to separate an impact of radiative and non-radiative recombination and disorder factors. The microwave probed –photoconductivity (MW-PC and spectrally resolved photo-luminescence (PL transients were simultaneously recorded under ultraviolet (UV light 354 nm pulsed 500 ps excitation. The MW-PC transients exhibited the carrier decay components associated with carrier decay within micro-crystals and the disordered structure on the periphery areas surrounding crystalline columns. Three PL bands were resolved within PL spectrum, namely, the exciton ascribed UV-PL band edge for hν>3.3 eV, blue B-PL band for 2.5 < hν < 3.0 eV and yellow Y-PL band with hν < 2.4 eV. It has been obtained that intensity of UV-PL band increases with excitation density, while intensity of B-PL band is nearly invariant. However, intensity of the Y-PL increases with reduction of the excitation density. The Y-PL can be associated with trapping centers. A reduction of UV excitation density leads to a decrease of the relative amplitude of the asymptotic component within the MW-PC transients and to an increase of the amplitude as well as duration of the yellow spectral band (Y-PL asymptotic component. Fractional index α with values 0.5 < α < 0.8 was evaluated for the stretched-exponent component which fits the experimental transients determined by the disordered structure ascribed to the periphery areas surrounding the crystalline columns.

  4. Particle size- and concentration-dependent separation of magnetic nanoparticles

    Science.gov (United States)

    Witte, Kerstin; Müller, Knut; Grüttner, Cordula; Westphal, Fritz; Johansson, Christer

    2017-04-01

    Small magnetic nanoparticles with a narrow size distribution are of great interest for several biomedical applications. When the size of the particles decreases, the magnetic moment of the particles decreases. This leads to a significant increase in the separation time by several orders of magnitude. Therefore, in the present study the separation processes of bionized nanoferrites (BNF) with different sizes and concentrations were investigated with the commercial Sepmag Q system. It was found that an increasing initial particle concentration leads to a reduction of the separation time for large nanoparticles due to the higher probability of building chains. Small nanoparticles showed exactly the opposite behavior with rising particle concentration up to 0.1 mg(Fe)/ml. For higher iron concentrations the separation time remains constant and the measured Z-average decreases in the supernatant at same time intervals. At half separation time a high yield with decreasing hydrodynamic diameter of particles can be obtained using higher initial particle concentrations.

  5. Carrier trapping induced abnormal temperature dependent photoluminescence properties of novel sandwiched structure InGaN quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    He, Juan; Li, Ding; Rajabi, K.; Yang, Wei; Hu, Xiaodong [State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Liu, Lei [Suzhou Institute of Nano-tech and Nano-bionics, CAS, Suzhou 215125 (China)

    2014-04-15

    A dual-wavelength LED sample with novel sandwiched structure in high-In-content MQWs is studied by temperature dependent photoluminescence (TDPL) and the abnormal temperature dependence of emission intensity is obtained. The novel MQWs structure which contains staggered quantum wells and an ultra-thin InN interlayer in the wells shows better luminescence property than the reference sample which has conventional quantum wells. Under 325 nm continuous wave laser excitation the LED sample of novel structure exhibits unexpected increasing luminescence intensity as temperature goes up from 140 K to 220 K and reaches its maximum at 220 K. This could be attributed to (1) the carrier redistribution and the novel sandwiched MQWs' high carrier trapping capability; (2) the intrinsic emission property of the MQWs enhanced by improvement of electron-hole overlap and reduction of quantum confined Stark effect (QCSE) and compositional fluctuation. TDPL under 405 nm laser excitation is also measured to support this view. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Dependency of water concentration on ethanolysis of trioleoylglycerol by lipases

    DEFF Research Database (Denmark)

    Piyatheerawong, W.; Iwasaki, Y; Xu, Xuebing

    2004-01-01

    The effects of water concentration on ethanolysis of trioleoylglycerol catalyzed by four different lipases were studied. The target product of the ethanolysis was 2-monooleoylglycerol (2-MO). Novozym 435 (a commercially available preparation of immobilized Candida antarctica lipase B, CALB......) exhibited both the highest product yield and the reaction rate at very low (less than 1 wt.%) free water concentration. Its catalytic activity did not drop even in dry state, i.e. in the system of dry CALB in dry ethanol (water concentration was ca. 0.1 wt.%). In contrast, other three immobilized lipases...... tested (Rhizomucor miehei lipase, Burkholderia cepacia lipase and Thermomyces lanuginosus lipase) required larger amounts of free water (ca. 7-9 wt.%) for their best performance and exhibited no ethanolysis reaction at low free water concentrations. The CALB's anomalous behavior was also observed...

  7. Tb3+concentration dependent optical properties and energy transfer in

    Institute of Scientific and Technical Information of China (English)

    曹春燕

    2013-01-01

    By controlling the concentration of Tb3+, a series of GdF3 samples were synthesized by a hydrothermal method without any surfactant. The samples were characterized by X-ray diffraction (XRD) patterns, field emission scanning electron microscopy (FE-SEM) images, photoluminescence (PL) excitation and emission spectra as well as luminescent dynamic decay curves. The opti-cal properties of Tb3+, the concentration quenching phenomenon of Tb3+, and the energy transfer from host Gd3+to Tb3+were inves-tigated and discussed based on the concentration of Tb3+in the GdF3 samples. The experimental results suggested that the optical properties of Tb3+and the energy transfer from host Gd3+to Tb3+could be adjusted by the concentration of Tb3+in the samples.

  8. Depth profiling of strain and carrier concentration by cleaved surface scanning of GaN Gunn-diode: confocal Raman microscopy

    Science.gov (United States)

    Belyaev, A. E.; Strelchuk, V. V.; Nikolenko, A. S.; Romanyuk, A. S.; Mazur, Yu I.; Ware, M. E.; DeCuir, E. A., Jr.; Salamo, G. J.

    2013-10-01

    Confocal micro-Raman spectroscopy was applied to study the cleaved surface of vertical GaN Gunn-diode structure grown by molecular-beam epitaxy. The analysis of lateral scanning along the cleaved edge reveals the depth profile of elastic strain, quality of the crystal structure, and the concentration of charge carriers. Results are compared with that of axial confocal Raman depth profiling normal to the structure's surface. Decrease of compressive strain near the cleaved edge in the direction from the substrate to the structure's surface and in the growth plane towards the cleaved edge is shown. The decrease in charge carrier concentration in the undoped n0-GaN channel region in comparison with the n+-GaN contact region is identified. Peculiarities of the resulting spatial profiles of free charge carriers and their correlation with the initial doping profile are discussed.

  9. Temperature dependence of DNA condensation at high ionic concentration

    Science.gov (United States)

    Mao, Wei; Gao, Qingqing; Liu, Yanhui; Fan, Yangtao; Hu, Lin; Xu, Houqiang

    2016-08-01

    A series of experiments pointed out that compact states of DNA condensed by multivalent cation prefer higher temperature. The condensed DNA takes elongated coil or compact globule states and the population of the compact globule states increases with an increase in temperature. At the same time, a recent experimental work carried out in buffer solution without multivalent cation points out that DNA persistence length strongly depends on the temperature. DNA persistence length is a key parameter for quantitative interpretation of the conformational properties of DNA and related to the bending rigidity of DNA. It is necessary to revolve the effects of temperature dependence of persistence length on DNA condensation, and a model including the temperature dependence of persistence length and strong correlation of multivalent cation on DNA is provided. The autocorrelation function of the tangent vectors is found as an effective way to detect the temperature dependence of toroid conformations. With an increase in temperature, the first periodic oscillation in the autocorrelation function shifts left and the number of segments containing the first periodic oscillation decreases gradually. According to the experiments mentioned above, the long-axis length is defined to estimate the temperature dependence of condensation process further. At the temperatures defined in experiments mentioned above, the relation between long-axis length and temperature matches the experimental results.

  10. Concentration dependent differential activity of signalling molecules in Caenorhabditis elegans

    Science.gov (United States)

    Caenorhabditis elegans employs specific glycosides of the dideoxysugar ascarylose (the ‘ascarosides’) for monitoring population density/ dauer formation and finding mates. A synergistic blend of three ascarosides, called ascr#2, ascr#3 and ascr#4 acts as a dauer pheromone at a high concentration na...

  11. Excitation-wavelength-dependent small polaron trapping of photoexcited carriers in α-Fe2O3

    Science.gov (United States)

    Carneiro, Lucas M.; Cushing, Scott K.; Liu, Chong; Su, Yude; Yang, Peidong; Alivisatos, A. Paul; Leone, Stephen R.

    2017-08-01

    Small polaron formation is known to limit ground-state mobilities in metal oxide photocatalysts. However, the role of small polaron formation in the photoexcited state and how this affects the photoconversion efficiency has yet to be determined. Here, transient femtosecond extreme-ultraviolet measurements suggest that small polaron localization is responsible for the ultrafast trapping of photoexcited carriers in haematite (α-Fe2O3). Small polaron formation is evidenced by a sub-100 fs splitting of the Fe 3p core orbitals in the Fe M2,3 edge. The small polaron formation kinetics reproduces the triple-exponential relaxation frequently attributed to trap states. However, the measured spectral signature resembles only the spectral predictions of a small polaron and not the pre-edge features expected for mid-gap trap states. The small polaron formation probability, hopping radius and lifetime varies with excitation wavelength, decreasing with increasing energy in the t2g conduction band. The excitation-wavelength-dependent localization of carriers by small polaron formation is potentially a limiting factor in haematite's photoconversion efficiency.

  12. Concentration dependence of dynamic moduli of heat-induced soy protein gels

    NARCIS (Netherlands)

    Renkema, J.M.S.; Vliet, van T.

    2004-01-01

    The concentration dependence of dynamic moduli of soy protein gels was studied for different protein preparations (soy protein isolate), purified glycinin and a -conglycinin rich fraction) at various pHs and salt concentrations. The concentration dependence of the storage modulus of glycinin and

  13. Conformation-dependent accessibility of Cys-136 and Cys-155 of the mitochondrial rat carnitine/acylcarnitine carrier to membrane-impermeable SH reagents.

    Science.gov (United States)

    Giangregorio, Nicola; Tonazzi, Annamaria; Indiveri, Cesare; Palmieri, Ferdinando

    2007-11-01

    During substrate translocation mitochondrial carriers cycle between the cytoplasmic-state (c-state) with substrate-binding site open to the intermembrane space and matrix-state (m-state) with the binding site open to the mitochondrial matrix. Here, the accessibility of Cys-58, Cys-136 and Cys-155 of the rat mitochondrial carnitine/acylcarnitine carrier (CAC) to membrane-impermeable SH reagents was examined as a function of the conformational state. Reconstituted mutant CACs containing the combinations Cys-58/Cys-136, Cys-58/Cys-155, and Cys-136/Cys-155 transport carnitine with a ping-pong mechanism like the wild-type, since increasing substrate concentrations on one side of the membrane decreased the apparent affinity for the substrate on the other side. In view of this mechanism, the effect of SH reagents on the transport activity of mutant CACs was tested by varying the substrate concentration inside or outside the proteoliposomes, keeping the substrate concentration on the opposite side constant. The reagents MTSES, MTSEA and fluorescein-5-maleimide did not affect the carnitine/carnitine exchange activity of the mutant carrier with only Cys-58 in contrast to mutant carriers with Cys-58/Cys-136, Cys-58/Cys-155 or Cys-136/Cys-155. In the latter, the inhibitory effect of the reagents was more pronounced when the intraliposomal carnitine concentration was increased, favouring the m-state of the carrier, whereas the effect was less when the concentration of carnitine was increased in the external compartment of the proteoliposomes, favouring the c-state. Moreover, the mutant carrier proteins with Cys-136/Cys-155, Cys-58/Cys-136 or Cys-58/Cys-155 were more fluorescent when extracted from fluorescein-5-maleimide-treated proteoliposomes containing 15 mM internal carnitine as compared to 2.5 mM. These results are discussed in terms of conformational changes of the carrier occurring during substrate translocation.

  14. Hydrologic and biologic influences on stream network nutrient concentrations: Interactions of hydrologic turnover and concentration-dependent nutrient uptake

    Science.gov (United States)

    Mallard, John; McGlynn, Brian; Covino, Tim

    2016-04-01

    Stream networks lie in a crucial landscape position between terrestrial ecosystems and downstream water bodies. As such, whether inferring terrestrial watershed processes from watershed outlet nutrient signals or predicting the effect of observed terrestrial processes on stream nutrient signals, it is requisite to understand how stream networks can modulate terrestrial nutrient inputs. To date integrated understanding and modeling of physical and biological influences on nutrient concentrations at the stream network scale have been limited. However, watershed scale groundwater - surface water exchange (hydrologic turnover), concentration-variable biological uptake, and the interaction between the two can strongly modify stream water nutrient concentrations. Stream water and associated nutrients are lost to and replaced from groundwater with distinct nutrient concentrations while in-stream nutrients can also be retained by biological processes at rates that vary with concentration. We developed an empirically based network scale model to simulate the interaction between hydrologic turnover and concentration-dependent nutrient uptake across stream networks. Exchange and uptake parameters were measured using conservative and nutrient tracer addition experiments in the Bull Trout Watershed, central Idaho. We found that the interaction of hydrologic turnover and concentration-dependent uptake combined to modify and subsequently stabilize in-stream concentrations, with specific concentrations dependent on the magnitude of hydrologic turnover, groundwater concentrations, and the shape of nutrient uptake kinetic curves. We additionally found that by varying these physical and biological parameters within measured ranges we were able to generate a spectrum of stream network concentration distributions representing a continuum of shifting magnitudes of physical and biological influences on in-stream concentrations. These findings elucidate the important and variable role of

  15. Efficient conversion of high concentration of glycerol to Monacolin K by solid-state fermentation of Monascus purpureus using bagasse as carrier.

    Science.gov (United States)

    Lu, Li-Ping; Zhang, Bo-Bo; Xu, Gan-Rong

    2013-03-01

    High concentration of glycerol was used as the sole carbon source for efficient production of Monacolin K (MK) by solid-state fermentation (SSF) of Monascus purpureus 9901 using agricultural residue (bagasse), as an inert carrier. A comparative study showed that MK production in SSF was about 5.5 times higher than that of submerged fermentation when 26 % of glycerol was used, which may be due to the formation of glycerol concentration gradients in the inert carrier and less catabolite repression in SSF. For enhancement of MK yield in SSF, the effects of different influential variables, such as glycerol concentration, nitrogen source and its concentration, initial moisture content, inoculum size and particle size of bagasse, were systematically examined. All the factors mentioned above had an effect on the MK production in SSF to some extent. The maximal yield of MK (12.9 mg/g) was achieved with 26 % glycerol, 5 % soybean meal, 51 % initial moisture content, 20 % inoculum size and 1 mm particle size of bagasse. The results in this study may expand our understanding on the application of SSF using agricultural residue as carrier for production of useful microbial metabolites, especially the efficient conversion of high concentration of glycerol to MK by Monascus purpureus.

  16. Size-Dependent Biexciton Quantum Yields and Carrier Dynamics of Quasi-Two-Dimensional Core/Shell Nanoplatelets.

    Science.gov (United States)

    Ma, Xuedan; Diroll, Benjamin T; Cho, Wooje; Fedin, Igor; Schaller, Richard D; Talapin, Dmitri V; Gray, Stephen K; Wiederrecht, Gary P; Gosztola, David J

    2017-09-05

    Quasi-two-dimensional nanoplatelets (NPLs) possess fundamentally different excitonic properties from zero-dimensional quantum dots. We study lateral size-dependent photon emission statistics and carrier dynamics of individual NPLs using second-order photon correlation (g((2))(τ)) spectroscopy and photoluminescence (PL) intensity-dependent lifetime analysis. Room-temperature radiative lifetimes of NPLs can be derived from maximum PL intensity periods in PL time traces. It first decreases with NPL lateral size and then stays constant, deviating from the electric dipole approximation. Analysis of the PL time traces further reveals that the single exciton quantum yield in NPLs decreases with NPL lateral size and increases with protecting shell thickness, indicating the importance of surface passivation on NPL emission quality. Second-order photon correlation (g((2))(τ)) studies of single NPLs show that the biexciton quantum yield is strongly dependent on the lateral size and single exciton quantum yield of the NPLs. In large NPLs with unity single exciton quantum yield, the corresponding biexciton quantum yield can reach unity. These findings reveal that by careful growth control and core-shell material engineering, NPLs can be of great potential for light amplification and integrated quantum photonic applications.

  17. Concentration dependence of Li+/Na+ diffusion in manganese hexacyanoferrates

    Science.gov (United States)

    Takachi, Masamitsu; Fukuzumi, Yuya; Moritomo, Yutaka

    2016-06-01

    Manganese hexacyanoferrates (Mn-HCFs) with a jungle-gym-type structure are promising cathode materials for Li+/Na+ secondary batteries (LIBs/SIBs). Here, we investigated the diffusion constants D Li/D Na of Li+/Na+ against the Li+/Na+ concentration x Na/x Li and temperature (T) of A 1.32Mn[Fe(CN)6]0.833.6H2O (A = Li and Na). We evaluated the activation energy E\\text{a}\\text{Li}/E\\text{a}\\text{Na} of D Li/D Na against x Na/x Li. We found that E\\text{a}\\text{Na} steeply increases with x Na from 0.41 eV at x Na = 0.69 to 0.7 eV at 1.1. The increase in E\\text{a}\\text{Na} is ascribed to the occupancy effect of the Na+ site. The increase in E\\text{a}\\text{Li} is suppressed, probably because the number of Li+ sites is three times that of Na+ sites.

  18. Size and dopant-concentration dependence of photoluminescence properties of ion-implanted phosphorus- and boron-codoped Si nanocrystals

    Science.gov (United States)

    Nakamura, Toshihiro; Adachi, Sadao; Fujii, Minoru; Sugimoto, Hiroshi; Miura, Kenta; Yamamoto, Shunya

    2015-04-01

    We investigate the nanocrystallite-size and dopant-concentration dependence of the photoluminescence (PL) properties of heavily phosphorus- (P) and boron- (B) codoped Si nanocrystals (Si NCs), prepared using a combination of sputtering and ion implantation techniques. We find that the heavily doped Si NC exhibits three exotic luminescence bands, A, B, and C. The peak energy of band A redshifts with increasing dopant concentration. This band is due to the band-to-band transition at the reduced Si-NC band gap caused by the formation of impurity bands together with band-tailing effects. The PL redshift becomes large when the nanocrystallite size decreases, suggesting the occurrence of the quantum-confinement-induced carrier doping effect. The peak energies of bands B and C are independent of both the concentration and size, indicating that these bands are due to transitions between defect- and/or impurity-related localized states. Band A shows stronger thermal quenching than the PL band in pure (undoped) Si NCs, the magnitude of which depends on the dopant concentration. The stronger thermal quenching in band A is probably due to the thermally induced migration of electrons in the impurity band.

  19. Non-carrier nanoparticles adjuvant modular protein vaccine in a particle-dependent manner.

    Directory of Open Access Journals (Sweden)

    Arjun Seth

    Full Text Available Nanoparticles are increasingly used to adjuvant vaccine formulations due to their biocompatibility, ease of manufacture and the opportunity to tailor their size, shape, and physicochemical properties. The efficacy of similarly-sized silica (Si-OH, poly (D,L-lactic-co-glycolic acid (PLGA and poly caprolactone (PCL nanoparticles (nps to adjuvant recombinant capsomere presenting antigenic M2e modular peptide from Influenza A virus (CapM2e was investigated in vivo. Formulation of CapM2e with Si-OH or PLGA nps significantly boosted the immunogenicity of modular capsomeres, even though CapM2e was not actively attached to the nanoparticles prior to injection (i.e., formulation was by simple mixing. In contrast, PCL nps showed no significant adjuvant effect using this simple-mixing approach. The immune response induced by CapM2e alone or formulated with nps was antibody-biased with very high antigen-specific antibody titer and less than 20 cells per million splenocytes secreting interferon gamma. Modification of silica nanoparticle surface properties through amine functionalization and pegylation did not lead to significant changes in immune response. This study confirms that simple mixing-based formulation can lead to effective adjuvanting of antigenic protein, though with antibody titer dependent on nanoparticle physicochemical properties.

  20. Scaling dependence of memory windows and different carrier charging behaviors in Si nanocrystal nonvolatile memory devices

    Science.gov (United States)

    Yu, Jie; Chen, Kun-ji; Ma, Zhong-yuan; Zhang, Xin-xin; Jiang, Xiao-fan; Wu, Yang-qing; Huang, Xin-fan; Oda, Shunri

    2016-09-01

    Based on the charge storage mode, it is important to investigate the scaling dependence of memory performance in silicon nanocrystal (Si-NC) nonvolatile memory (NVM) devices for its scaling down limit. In this work, we made eight kinds of test key cells with different gate widths and lengths by 0.13-μm node complementary metal oxide semiconductor (CMOS) technology. It is found that the memory windows of eight kinds of test key cells are almost the same of about 1.64 V @ ± 7 V/1 ms, which are independent of the gate area, but mainly determined by the average size (12 nm) and areal density (1.8 × 1011/cm2) of Si-NCs. The program/erase (P/E) speed characteristics are almost independent of gate widths and lengths. However, the erase speed is faster than the program speed of test key cells, which is due to the different charging behaviors between electrons and holes during the operation processes. Furthermore, the data retention characteristic is also independent of the gate area. Our findings are useful for further scaling down of Si-NC NVM devices to improve the performance and on-chip integration. Project supported by the State Key Development Program for Basic Research of China (Grant No. 2010CB934402) and the National Natural Science Foundation of China (Grant Nos. 11374153, 61571221, and 61071008).

  1. Ultrasmall gold nanoparticles as carriers for nucleus-based gene therapy due to size-dependent nuclear entry.

    Science.gov (United States)

    Huo, Shuaidong; Jin, Shubin; Ma, Xiaowei; Xue, Xiangdong; Yang, Keni; Kumar, Anil; Wang, Paul C; Zhang, Jinchao; Hu, Zhongbo; Liang, Xing-Jie

    2014-06-24

    The aim of this study was to determine the size-dependent penetration ability of gold nanoparticles and the potential application of ultrasmall gold nanoparticles for intranucleus delivery and therapy. We synthesized gold nanoparticles with diameters of 2, 6, 10, and 16 nm and compared their intracellular distribution in MCF-7 breast cancer cells. Nanoparticles smaller than 10 nm (2 and 6 nm) could enter the nucleus, whereas larger ones (10 and 16 nm) were found only in the cytoplasm. We then investigated the possibility of using ultrasmall 2 nm nanoparticles as carriers for nuclear delivery of a triplex-forming oligonucleotide (TFO) that binds to the c-myc promoter. Compared to free TFO, the nanoparticle-conjugated TFO was more effective at reducing c-myc RNA and c-myc protein, which resulted in reduced cell viability. Our result demonstrated that the entry of gold nanoparticles into the cell nucleus is critically dependent on the size of the nanoparticles. We developed a strategy for regulating gene expression, by directly delivering TFOs into the nucleus using ultrasmall gold nanoparticles. More importantly, guidelines were provided to choose appropriate nanocarriers for different biomedical purposes.

  2. Effects of low-temperature (120 °C) annealing on the carrier concentration and trap density in amorphous indium gallium zinc oxide thin film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae-sung; Piao, Mingxing; Jang, Ho-Kyun; Kim, Gyu-Tae, E-mail: gtkim@korea.ac.kr [School of Electrical Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Oh, Byung Su [School of Electrical Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Samsung Display Company, Yongin (Korea, Republic of); Joo, Min-Kyu [School of Electrical Engineering, Korea University, Seoul 136-701 (Korea, Republic of); IMEP-LAHC, Grenoble INP, Minatec, CS 50257, 38016 Grenoble (France); Ahn, Seung-Eon [School of Electrical Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Samsung Advanced Institute of Technology, Samsung Electronics Corporations, Yongin 446-712 (Korea, Republic of)

    2014-12-28

    We report an investigation of the effects of low-temperature annealing on the electrical properties of amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs). X-ray photoelectron spectroscopy was used to characterize the charge carrier concentration, which is related to the density of oxygen vacancies. The field-effect mobility was found to decrease as a function of the charge carrier concentration, owing to the presence of band-tail states. By employing the transmission line method, we show that the contact resistance did not significantly contribute to the changes in device performance after annealing. In addition, using low-frequency noise analyses, we found that the trap density decreased by a factor of 10 following annealing at 120 °C. The switching operation and on/off ratio of the a-IGZO TFTs improved considerably after low-temperature annealing.

  3. Rapid evaluation of doping-spike carrier concentration levels in millimetre-wave GaAs Gunn diodes with hot-electron injection

    Science.gov (United States)

    Farrington, N. E. S.; Carr, M. W.; Missous, M.

    2010-12-01

    This paper describes a novel method for fast, accurate evaluation of doping-spike carrier concentrations in hot-electron injected GaAs Gunn diodes. The technique relies on current asymmetry measurements obtained using pulsed-dc testing of on-wafer quasi-planar Gunn diode test structures, which removes the need for full device fabrication. Small changes in carrier concentration can easily be detected (at a nominal value of 1 × 1018 cm-3) and a greater sensitivity than conventional techniques is demonstrated at the doping levels used. In addition, test structure fabrication can be integrated into the initial Gunn diode front side production process allowing a rapid in-process test to be carried out thus leading to a significant reduction in material characterization cycle time.

  4. Estimation of free carrier concentrations in high-quality heavily doped GaN:Si micro-rods by photoluminescence and Raman spectroscopy

    Science.gov (United States)

    Mohajerani, M. S.; Khachadorian, S.; Nenstiel, C.; Schimpke, T.; Avramescu, A.; Strassburg, M.; Hoffmann, A.; Waag, A.

    2016-03-01

    The controlled growth of highly n-doped GaN micro rods is one of the major challenges in the fabrication of recently developed three-dimensional (3D) core-shell light emitting diodes (LEDs). In such structures with a large active area, higher electrical conductivity is needed to achieve higher current density. In this contribution, we introduce high quality heavily-doped GaN:Si micro-rods which are key elements of the newly developed 3D core-shell LEDs. These structures were grown by metal-organic vapor phase epitaxy (MOVPE) using selective area growth (SAG). We employed spatially resolved micro-Raman and micro-photoluminescence (PL) in order to directly determine a free-carrier concentration profile in individual GaN micro-rods. By Raman spectroscopy, we analyze the low-frequency branch of the longitudinal optical (LO)-phonon-plasmon coupled modes and estimate free carrier concentrations from ≍ 2.4 × 1019 cm-3 up to ≍ 1.5 × 1020 cm-3. Furthermore, free carrier concentrations are determined by estimating Fermi energy level from the near band edge emission measured by low-temperature PL. The results from both methods reveal a good consistency.

  5. THE EFFECT OF CONCENTRATION OF CARRIER, pH AND TIME OF EXTRACTION ON SEPARATION'S FACTOR OF PENICILLIN G - PHENYL ACETATE BY REACTIVE EXTRACTION

    Directory of Open Access Journals (Sweden)

    Imam Santoso

    2010-06-01

    Full Text Available The aim of this research is to study the effect of concentration carrier, pH and time of extraction on separation's factor of penicillin g - phenyl acetate by reactive extraction technique. The 10 mL  aqueous  solution with variation of  pH : 5, 6 contains 0.001 M penicillin G and 0.001 M phenyl acetate has been extracted with 10 mL n-butyl acetate contains dioctylamine as carrier. Variation concentration  of carrier were 0.000; 0.002; 0.004; 0.006 and 0.008 M. Variation time of extraction were 1, 5, 10, 15 and 20 min. The penicillin G and phenyl acetate that dissolved in organic phase ha been  reextracted with 10 mL aqueous with variation of pH : 7, 8. The optimum condition obtained as follow : concentration dioctylamine was 0.002M ; pH the first phase water was 5 and the second phase water was 8 ; and the time of extraction was 10 min.   Keywords: Separation factor, Reactive extraction

  6. Carrier phase dependence in the ionization of Rydberg atoms by short radio-frequency pulses: A model system for high order harmonic generation

    NARCIS (Netherlands)

    Gurtler, A.; Robicheaux, F.; Vrakking, M.J.J.; Zande, W.J. van der; Noordam, L.D.

    2004-01-01

    We report time-resolved electron emission in experiments on ionization of rubidium Rydberg atoms (n=90) by few-cycle radio-frequency (RF) (1-10 MHz) pulses. The electron emission occurs in multiple bursts and strongly depends on the carrier-envelope phase as well as the duration and amplitude of the

  7. Membrane topology of the sodium ion-dependent citrate carrier of Klebsiella pneumoniae - Evidence for a new structural class of secondary transporters

    NARCIS (Netherlands)

    vanGeest, M; Lolkema, JS

    1996-01-01

    The predicted secondary structure model of the sodium ion-dependent citrate carrier of Klebsiella pneumoniae (CitS) presents the la-transmembrane helix motif observed for many secondary transporters, Biochemical evidence presented in this paper is not consistent with this model. N-terminal and C-ter

  8. TRANSPORT OF CITRATE CATALYZED BY THE SODIUM-DEPENDENT CITRATE CARRIER OF KLEBSIELLA-PNEUMONIAE IS OBLIGATORILY COUPLED TO THE TRANSPORT OF 2 SODIUM-IONS

    NARCIS (Netherlands)

    LOLKEMA, JS; ENEQUIST, H; VANDERREST, ME

    1994-01-01

    Aerobically grown Escherichia coli GM48 harboring plasmid pKScitS that codes for the sodium-dependent citrate carrier from Klebsiella pneumoniae (CitS) allows initial-rate measurements of citrate uptake in whole cells. The cation stoichiometry and selectivity of CitS was studied using this experimen

  9. Transport of citrate catalyzed by the sodium-dependent citrate carrier of Klebsiella pneumoniae is obligatorily coupled to the transport of two sodium ions

    NARCIS (Netherlands)

    Lolkema, Juke S.; Enequist, Hans; Rest, Michel E. van der

    1994-01-01

    Aerobically grown Escherichia coli GM48 harboring plasmid pKScitS that codes for the sodium-dependent citrate carrier from Klebsiella pneumoniae (CitS) allows initial-rate measurements of citrate uptake in whole cells. The cation stoichiometry and selectivity of CitS was studied using this experimen

  10. Membrane Topology of the Sodium Ion-dependent Citrate Carrier of Klebsiella pneumoniae. Evidence for a New Structural Class of Secondary Transporters

    NARCIS (Netherlands)

    Geest, Marleen van; Lolkema, Juke S.

    1996-01-01

    The predicted secondary structure model of the sodium ion-dependent citrate carrier of Klebsiella pneumoniae (CitS) presents the 12-transmembrane helix motif observed for many secondary transporters. Biochemical evidence presented in this paper is not consistent with this model. N-terminal and C-ter

  11. Dielectric functions and carrier concentrations of Hg{sub 1−x}Cd{sub x}Se films determined by spectroscopic ellipsometry

    Energy Technology Data Exchange (ETDEWEB)

    Lee, A. J.; Peiris, F. C., E-mail: peirisf@kenyon.edu [Department of Physics, Kenyon College, Gambier, Ohio 43022 (United States); Brill, G.; Doyle, K. [U.S. Army Research Laboratory, Adelphi, Maryland 20783-1197 (United States); Myers, T. H. [Department of Physics, Texas State University, San Marcos, Texas 78666 (United States)

    2015-08-17

    Spectroscopic ellipsometry, ranging from 35 meV to 6 eV, was used to determine the dielectric functions of a series of molecular beam epitaxy-grown Hg{sub 1−x}Cd{sub x}Se thin films deposited on both ZnTe/Si(112) and GaSb(112) substrates. The fundamental band gap as well as two higher-order electronic transitions blue-shift with increasing Cd composition in Hg{sub 1−x}Cd{sub x}Se, as expected. Representing the free carrier absorption with a Drude oscillator, we found that the effective masses of Hg{sub 1−x}Cd{sub x}Se (grown on ZnTe/Si) vary between 0.028 and 0.050 times the free electron mass, calculated using the values of carrier concentration and the mobility obtained through Hall measurements. Using these effective masses, we determined the carrier concentrations of Hg{sub 1−x}Cd{sub x}Se samples grown on GaSb, which is of significance as films grown on such doped-substrates posit ambiguous results when measured by conventional Hall experiments. These models can serve as a basis for monitoring Cd-composition during sample growth through in-situ spectroscopic ellipsometry.

  12. Hollow superparamagnetic iron oxide nanoshells as a hydrophobic anticancer drug carrier: intracelluar pH-dependent drug release and enhanced cytotoxicity.

    Science.gov (United States)

    Zhu, Xiao-Ming; Yuan, Jing; Leung, Ken Cham-Fai; Lee, Siu-Fung; Sham, Kathy W Y; Cheng, Christopher H K; Au, Doris W T; Teng, Gao-Jun; Ahuja, Anil T; Wang, Yi-Xiang J

    2012-09-21

    With curcumin and doxorubicin (DOX) base as model drugs, intracellular delivery of hydrophobic anticancer drugs by hollow structured superparamagnetic iron oxide (SPIO) nanoshells (hydrodynamic diameter: 191.9 ± 2.6 nm) was studied in glioblastoma U-87 MG cells. SPIO nanoshell-based encapsulation provided a stable aqueous dispersion of the curcumin. After the SPIO nanoshells were internalized by U-87 MG cells, they localized at the acidic compartments of endosomes and lysosomes. In endosome/lysosome-mimicking buffers with a pH of 4.5-5.5, pH-dependent drug release was observed from curcumin or DOX loaded SPIO nanoshells (curcumin/SPIO or DOX/SPIO). Compared with the free drug, the intracellular curcumin content delivered via curcumin/SPIO was 30 fold higher. Increased intracellular drug content for DOX base delivered via DOX/SPIO was also confirmed, along with a fast intracellular DOX release that was attributed to its protonation in the acidic environment. DOX/SPIO enhanced caspase-3 activity by twofold compared with free DOX base. The concentration that induced 50% cytotoxic effect (CC(50)) was 0.05 ± 0.03 μg ml(-1) for DOX/SPIO, while it was 0.13 ± 0.02 μg ml(-1) for free DOX base. These results suggested SPIO nanoshells might be a promising intracellular carrier for hydrophobic anticancer drugs.

  13. Concentration dependent toxicokinetics of copper in the red flour beetle Tribolium castaneum (Coleoptera: Tenebrionidae).

    Science.gov (United States)

    Bednarska, Agnieszka J; Stępień, Katarzyna

    2015-11-01

    To predict internal metal concentrations in animals under specific environmental exposures, the relationship between the exposure concentrations and values of toxicokinetic parameters must be known. At high exposure levels, the availability of carriers transporting metal ions through cellular membranes may become limited, thereby decreasing the assimilation rates (k A ). Furthermore, increased metal concentrations in food may result in greater damage to the gut and reduce the assimilation efficiency and/or increase the elimination rate (k E ). Therefore, k A should decrease and k E should increase with increasing metal concentrations. In fact, our study on Tribolium castaneum exposed to Cu at 500, 1000, 2000 and 4000 mg kg(-1) of dry flour showed that with increasing Cu concentrations, k A decreased from 0.0042 day(-1) at 500 mg kg(-1) to 0.0026 day(-1) at 4000 mg kg(-1) in females and from 0.0029 to 0.001 day(-1) in males and k E increased from 0.027 to 0.064 day(-1) and from 0.018 to 0.04 day(-1) in females and males, respectively. Significant differences in k A between the sexes were observed at 2000 and 4000 mg kg(-1), whereas significant differences between treatments were found for k A in males. Copper was efficiently regulated by T. castaneum: an eightfold increase in exposure concentrations resulted in only a ca. twofold increase in the internal concentration. No Cu effect on the respiratory metabolism of T. castaneum was found.

  14. Density-dependent dynamical coexistence of excitons and free carriers in the organolead perovskite C H3N H3Pb I3

    Science.gov (United States)

    Wang, Wei; Li, Yu; Wang, Xiangyuan; Lv, Yanping; Wang, Shufeng; Wang, Kai; Shi, Yantao; Xiao, Lixin; Chen, Zhijian; Gong, Qihuang

    2016-10-01

    The high efficiency of perovskite solar cells benefits from the high density of photoinduced free carriers. We studied how exciton and free carriers, as the two major photoproducts, coexist inside the C H3N H3Pb I3 perovskite. A new density-resolved spectroscopic method was developed for this purpose. The density-dependent coexistence of excitons and free carriers over a wide density range was experimentally observed. The quantitative analysis on the density-resolved spectra revealed a moderate exciton binding energy of 24 ± 2 meV. The results effectively proved that the strong ionic polarization inside the perovskite has a negligible contribution to exciton formation. The spectra also efficiently uncovered the effective mass of electron-hole pairs. Our spectroscopic method and the results profoundly enrich the understanding of the photophysics in perovskite materials for photovoltaic applications.

  15. Characterization of temperature-dependent carrier transport in disordered indium-tin-oxide/poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate)/polyfluorene/Ca/Al polymer structures

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Joe-Air [Department of Bio-Industrial Mechatronics Engineering, National Taiwan University, 1, Sec. 4, Roosevelt Road, Taipei 106, Taiwan (China); Wang, Jen-Cheng; Fang, Chia-Hui [Graduate Institute of Electro-Optical Engineering and Department of Electronic Engineering, Chang Gung University, 259 Wen-Hwa 1st Road, Kwei-Shan, Tao-Yuan 333, Taiwan (China); Wu, Ya-Fen [Department of Electronic Engineering, Ming Chi University of Technology, No. 84, Gongzhuan Road, Taishan Dist., New Taipei City 243, Taiwan (China); Teng, Jen-Wei; Chen, Yu-Ting [Graduate Institute of Electro-Optical Engineering and Department of Electronic Engineering, Chang Gung University, 259 Wen-Hwa 1st Road, Kwei-Shan, Tao-Yuan 333, Taiwan (China); Fan, Ping-Lin [Department of Digital Technology Design and Graduate School of Toy and Game Design, National Taipei University of Education, No. 134, Sec. 2, Heping E. Road, Taipei 106, Taiwan (China); Nee, Tzer-En, E-mail: neete@mail.cgu.edu.tw [Graduate Institute of Electro-Optical Engineering and Department of Electronic Engineering, Chang Gung University, 259 Wen-Hwa 1st Road, Kwei-Shan, Tao-Yuan 333, Taiwan (China)

    2011-04-29

    The temperature-dependent electrical characteristics of polyfluorene-based polymer structures over a temperature range from 200 to 300 K are systematically investigated in this study. Initially, using the definitions of the Berthelot-type model, it is found that the sample exhibits a higher Berthelot-type temperature T{sub B} with high driving voltage, indicating that carrier transport in a disordered system manifests Berthelot-type behaviors. The ideal current density-voltage curve for the polymer structures given the carrier transmit mechanism is further elucidated by taking into account the ohmic conduction, trap charge limited current, and Mott and Gurney model of space charge limited current. The proposed procedure is simple and can be used to characterize the material with reasonable accuracy. We also study the density of the traps H{sub t}, and the characteristic energy of the distribution E{sub t} to better understand the carrier-transport process in organic materials and structures.

  16. Underpotential Deposition of Silver on Pt(111). Part 1. Concentration Dependence

    Science.gov (United States)

    1990-01-01

    AD-A236 692 Underpotential Deposition of Silver on Pt(111): Part I. Concentration Dependence r T ~.J.F. Rodriguez, D.L. Taylor and H.D. Abruhla* EL...dependence of the underpotential deposition of silver on well-defined Pt(111) electrodes. Electrochemical as well as ultra high vacuum surface...silver are deposited at underpotentials but the stability of the second layer is a strong function of the silver ion concentration in solution. When

  17. Tuning the carrier concentration using Zintl chemistry in Mg3Sb2, and its implications for thermoelectric figure-of-merit.

    Science.gov (United States)

    Bhardwaj, A; Chauhan, N S; Goel, S; Singh, Vijeta; Pulikkotil, J J; Senguttuvan, T D; Misra, D K

    2016-02-17

    Zintl compounds are potential candidates for efficient thermoelectric materials, because typically they are small band gap semiconductors. In addition, such compounds allow fine tuning of the carrier concentration by chemical doping for the optimization of thermoelectric performance. Herein, such tunability is demonstrated in Mg3Sb2-based Zintl compounds via Zn(2+) doping at the Mg(2+) site of the anionic framework (Mg2Sb2)(2-), in the series Mg3-xZnxSb2 (0 ≤ x ≤ 0.1). The materials have been successfully synthesized using the spark plasma sintering (SPS) technique. X-ray diffraction (XRD) analysis confirms a single solid solution phase of Mg3-xZnxSb2 (0 ≤ x ≤ 0.1). The thermoelectric properties are characterized by the Seebeck coefficient, electrical conductivity, and thermal conductivity measurements from 323 K to 773 K. Isoelectronic Zn substitution at the Mg site presents the controlled variation in the carrier concentration for optimizing the high power factor and reduced thermal conductivity. These results lead to a substantial increase in ZT of 0.37 at 773 K for a composition with x = 0.10 which is ∼42% higher than undoped Mg3Sb2. The electronic transport data for the Mg3-xZnxSb2 (0 ≤ x ≤ 0.1) compound are analyzed using a single parabolic band model predicting that Mg2.9Zn0.1Sb2 exhibits a near-optimal carrier concentration for high ZT. The electronic structure of transport properties of these disordered Mg3-xZnxSb2 (0 ≤ x ≤ 0.1) is also studied using density functional theory and the results obtained are in good agreement with experimental results. The low cost, lightness and non-toxicity of the constituent elements make these materials ideal for mid-temperature thermoelectric applications.

  18. Thickness-dependent carrier transport and optically enhanced transconductance gain in III-VI multilayer InSe

    Science.gov (United States)

    Ho, Ching-Hwa

    2016-06-01

    Multilayer InSe with a thickness above ˜20 nm, is a direct semiconductor with a peak absorption wavelength approaching λ = 1000 nm, which is a promising candidate for solar-energy conversion and 2D optoelectronics devices. We present herein the experimental observations of thickness-dependent conductivity and photoconductive-responsivity spectrum in multilayer InSe as well as optically enhanced transconductance gain in the multilayer InSe metal-semiconductor-field-effect transistor (MESFET) illuminated by a halogen lamp. The voltage-current (V-I) measurement result shows multilayer InSe belongs to a p-type semiconductor, which can form a p-channel FET device. Thickness (t) dependent conductivity (σ) of multilayer InSe reveals about six-order variation from 5076 (Ω-cm)-1 (t = 5 nm) to 2.56 × 10-3 (Ω-cm)-1 (t = 184 μm, bulk) following a relationship of σ ∝ t -1.38. The highest conductivity in a thin InSe (e.g. t = 5 nm) is due to the increase of carrier density when the thickness is decreased. The photoresponsivity spectrum of a Ag-InSe-Ag multilayer photoconductor demonstrates a prominent peak absorption at 1.1 ˜ 1.3 eV, matches well with the direct-free-exciton energy of the InSe. A multilayer p-InSe MESFET was tested by V-I measurement. The transconductance was measured and determined to be {g}m={≤ft|\\tfrac{\\partial {{{I}}}{{D}}}{\\partial {{{V}}}{{G}}}\\right|}{{{V}}{{SD}}={{2V}}} = ({1.25 +/- 0.008})× {10}-4≤ft(\\tfrac{{{A}}}{{{V}}}\\right). The gm value will enhance about three times when the MESFET was placed under the illumination of a tungsten halogen lamp of a lower power density ˜0.5 mW · cm-2. All the experimental results demonstrate multilayer InSe a promising 2D material available for microelectronics and optoelectronics applications.

  19. Ultra-low carrier concentration and surface-dominant transport in antimony-doped Bi2Se3 topological insulator nanoribbons

    KAUST Repository

    Hong, Seung Sae

    2012-03-27

    A topological insulator is the state of quantum matter possessing gapless spin-locking surface states across the bulk band gap, which has created new opportunities from novel electronics to energy conversion. However, the large concentration of bulk residual carriers has been a major challenge for revealing the property of the topological surface state by electron transport measurements. Here we report the surface-state-dominant transport in antimony-doped, zinc oxide-encapsulated Bi2Se3 nanoribbons with suppressed bulk electron concentration. In the nanoribbon with sub-10-nm thickness protected by a zinc oxide layer, we position the Fermi levels of the top and bottom surfaces near the Dirac point by electrostatic gating, achieving extremely low two-dimensional carrier concentration of 2×10 11cm-2. The zinc oxide-capped, antimony-doped Bi 2Se3 nanostructures provide an attractive materials platform to study fundamental physics in topological insulators, as well as future applications. © 2012 Macmillan Publishers Limited. All rights reserved.

  20. AgI alloying in SnTe boosts the thermoelectric performance via simultaneous valence band convergence and carrier concentration optimization

    Science.gov (United States)

    Banik, Ananya; Biswas, Kanishka

    2016-10-01

    SnTe, a Pb-free analogue of PbTe, was earlier assumed to be a poor thermoelectric material due to excess p-type carrier concentration and large energy separation between light and heavy hole valence bands. Here, we report the enhancement of the thermoelectric performance of p-type SnTe by Ag and I co-doping. AgI (1-6 mol%) alloying in SnTe modulates its electronic structure by increasing the band gap of SnTe, which results in decrease in the energy separation between its light and heavy hole valence bands, thereby giving rise to valence band convergence. Additionally, iodine doping in the Te sublattice of SnTe decreases the excess p-type carrier concentration. Due to significant decrease in hole concentration and reduction of the energy separation between light and heavy hole valence bands, significant enhancement in Seebeck coefficient was achieved at the temperature range of 600-900 K for Sn1-xAgxTe1-xIx samples. A maximum thermoelectric figure of merit, zT, of ~1.05 was achieved at 860 K in high quality crystalline ingot of p-type Sn0.95Ag0.05Te0.95I0.05.

  1. Correlation between Defect Concentration and Carrier Lifetime of GaAs Grown by Molecular Beam Epitaxy at Different Temperatures

    Science.gov (United States)

    Lin, Gong-Ru; Liu, Tze-An; Pan, Ci-Ling

    2001-11-01

    A pump-probe study of GaAs grown by molecular beam epitaxy at low temperatures (LT-GaAs) is performed. Ultrashort carrier lifetimes of the as-grown LT-GaAs increase from Schokley-Read-Hall model. The decreasing trend in the amplitudes of continuous-wave and transient reflectivities (Δ R/R) as a function of the growth temperature for the LT-GaAs is explained as an induced absorption caused by dense arsenic antisite defects. The sign of the transient Δ R/R reversed for LT-GaAs grown at 200°C. This is tentatively attributed to the band gap renormalization effect.

  2. Overcoming the concentration-dependence of responsive probes for magnetic resonance imaging

    Science.gov (United States)

    Ekanger, Levi A.

    2015-01-01

    In magnetic resonance imaging, contrast agents are molecules that increase the contrast-to-noise ratio of non-invasively acquired images. The information gained from magnetic resonance imaging can be increased using responsive contrast agents that undergo chemical changes, and consequently changes to contrast enhancement, for example in response to specific biomarkers that are indicative of diseases. A major limitation with modern responsive contrast agents is concentration-dependence that requires the concentration of contrast agent to be known: an extremely challenging task in vivo. Here, we review advances in several strategies aimed at overcoming the concentration-dependent nature of responsive contrast agents. PMID:25579206

  3. Formation energy of vacancies in FeCr alloys: Dependence on Cr concentration

    Energy Technology Data Exchange (ETDEWEB)

    Rio, Emma del, E-mail: emma.delrio@upm.e [Instituto de Fusion Nuclear, Universidad Politecnica de Madrid, C/Jose Gutierrez Abascal, 2, 28006 Madrid (Spain); Sampedro, Jesus M. [Instituto de Fusion Nuclear, Universidad Politecnica de Madrid, C/Jose Gutierrez Abascal, 2, 28006 Madrid (Spain); Dogo, Harun [Materials Science and Technology Division, MST-8, Los Alamos National Laboratory, POB 1663, Los Alamos, NM (United States); Caturla, Maria J., E-mail: MJ.Caturla@ua.e [Dept. de Fisica Aplicada, Facultad de Ciencias, Fase II, Universidad de Alicante, Alicante E-03690 (Spain); Caro, Magdalena [Materials Science and Technology Division, MST-8, Los Alamos National Laboratory, POB 1663, Los Alamos, NM (United States); Caro, Alfredo, E-mail: caro@lanl.go [Materials Science and Technology Division, MST-8, Los Alamos National Laboratory, POB 1663, Los Alamos, NM (United States); Perlado, J. Manuel [Instituto de Fusion Nuclear, Universidad Politecnica de Madrid, C/Jose Gutierrez Abascal, 2, 28006 Madrid (Spain)

    2011-01-01

    A modified version of the concentration-dependent model (CDM) potential (A. Caro et al., Phys. Rev. Lett. 95 (2005) 075702) has been developed to study defects in Fe-Cr for different Cr concentrations. A comparison between this new potential and DFT results for a variety of point defect configurations is performed in order to test its reliability for radiation damage studies. The effect of Cr concentration on the vacancy formation energy in Fe-Cr alloys is analyzed in detail. This study shows a linear dependence of the vacancy formation energy on Cr concentration for values above 6% of Cr. However, the formation energy deviates from the linear interpolation in the region below 6% Cr concentration. In order to understand this behavior, the influence of the relative positions between Cr atoms and vacant sites on the vacancy formation energy has been studied.

  4. Diffusion of Hydrogen in Proton Implanted Silicon: Dependence on the Hydrogen Concentration

    CERN Document Server

    Faccinelli, Martin; Jelinek, Moriz; Wuebben, Thomas; Laven, Johannes G; Schulze, Hans-Joachim; Hadley, Peter

    2016-01-01

    The reported diffusion constants for hydrogen in silicon vary over six orders of magnitude. This spread in measured values is caused by the different concentrations of defects in the silicon that has been studied. Hydrogen diffusion is slowed down as it interacts with impurities. By changing the material properties such as the crystallinity, doping type and impurity concentrations, the diffusivity of hydrogen can be changed by several orders of magnitude. In this study the influence of the hydrogen concentration on the temperature dependence of the diffusion in high energy proton implanted silicon is investigated. We show that the Arrhenius parameters, which describe this temperature dependence decrease with increasing hydrogen concentration. We propose a model where the relevant defects that mediate hydrogen diffusion become saturated with hydrogen at high concentrations. When the defects that provide hydrogen with the lowest energy positions in the lattice are saturated, hydrogen resides at energetically le...

  5. Evolution of High-Temperature Superconductivity from a Low-T_{c} Phase Tuned by Carrier Concentration in FeSe Thin Flakes.

    Science.gov (United States)

    Lei, B; Cui, J H; Xiang, Z J; Shang, C; Wang, N Z; Ye, G J; Luo, X G; Wu, T; Sun, Z; Chen, X H

    2016-02-19

    We report the evolution of superconductivity in an FeSe thin flake with systematically regulated carrier concentrations by the liquid-gating technique. With electron doping tuned by the gate voltage, high-temperature superconductivity with an onset at 48 K can be achieved in an FeSe thin flake with T_{c} less than 10 K. This is the first time such high temperature superconductivity in FeSe is achieved without either an epitaxial interface or external pressure, and it definitely proves that the simple electron-doping process is able to induce high-temperature superconductivity with T_{c}^{onset} as high as 48 K in bulk FeSe. Intriguingly, our data also indicate that the superconductivity is suddenly changed from a low-T_{c} phase to a high-T_{c} phase with a Lifshitz transition at a certain carrier concentration. These results help to build a unified picture to understand the high-temperature superconductivity among all FeSe-derived superconductors and shed light on the further pursuit of a higher T_{c} in these materials.

  6. Negative BOLD response and serotonin concentration within rostral subgenual portion of the anterior cingulate cortex for long-allele carriers during perceptual processing of emotional tasks

    Science.gov (United States)

    Hadi, Shamil M.; Siadat, Mohamad R.; Babajani-Feremi, Abbas

    2012-03-01

    We investigated the effect of synaptic serotonin concentration on hemodynamic responses. The stimuli paradigm involved the presentation of fearful and threatening facial expressions to a set of 24 subjects who were either5HTTLPR long- or short-allele carriers (12 of each type in each group). The BOLD signals of the rACC from subjects of each group were averaged to increase the signal-to-noise ratio. We used a Bayesian approach to estimate the parameters of the underlying hemodynamic model. Our results, during this perceptual processing of emotional task, showed a negative BOLD signal in the rACC in the subjects with long-alleles. In contrast, the subjects with short-alleles showed positive BOLD signals in the rACC. These results suggest that high synaptic serotonin concentration in the rACC inhibits neuronal activity in a fashion similar to GABA, and a consequent negative BOLD signal ensues.

  7. Concentration dependent switch in the kinetic pathway of lysozyme fibrillation: Spectroscopic and microscopic analysis

    Science.gov (United States)

    Kiran Kumar, E.; Prasad, Deepak Kumar; Prakash Prabhu, N.

    2017-08-01

    Formation of amyloid fibrils is found to be a general tendency of many proteins. Investigating the kinetic mechanisms and structural features of the intermediates and the final fibrillar state is essential to understand their role in amyloid diseases. Lysozyme, a notable model protein for amyloidogenic studies, readily formed fibrils in vitro at neutral pH in the presence of urea. It, however, showed two different kinetic pathways under varying urea concentrations when probed with thioflavin T (ThT) fluorescence. In 2 M urea, lysozyme followed a nucleation-dependent fibril formation pathway which was not altered by varying the protein concentration from 2 mg/ml to 8 mg/ml. In 4 M urea, the protein exhibited concentration dependent change in the mechanism. At lower protein concentrations, lysozyme formed fibrils without any detectable nuclei (nucleation-independent polymerization pathway). When the concentration of the protein was increased above 3 mg/ml, the protein followed nucleation-dependent polymerization pathway as observed in the case of 2 M urea condition. This was further verified using microscopic images of the fibrils. The kinetic parameters such as lag time, elongation rate, and fibrillation half-time, which were derived from ThT fluorescence changes, showed linear dependency against the initial protein concentration suggested that under the nucleation-dependent pathway conditions, the protein followed primary-nucleation mechanism without any significant secondary nucleation events. The results also suggested that the differences in the initial protein conformation might alter the mechanism of fibrillation; however, at the higher protein concentrations lysozyme shifted to nucleation-dependent pathway.

  8. The association between etanercept serum concentration and psoriasis severity is highly age-dependent.

    Science.gov (United States)

    Detrez, Iris; Van Steen, Kristel; Segaert, Siegfried; Gils, Ann

    2017-06-01

    The association between etanercept serum concentration and psoriasis disease severity is poorly investigated, and currently etanercept serum concentration monitoring that is aiming to optimize the psoriasis treatment lacks evidence. In this prospective study, we investigated the relation between etanercept exposure and disease severity via measuring etanercept concentrations at five consecutive time points in 56 psoriasis patients. Disease severity assessments included the Psoriasis Area and Severity Index (PASI), body surface area (BSA) and Physician Global Assessment (PGA), and etanercept and anti-etanercept antibody concentrations were determined every 3 months for a period of 1 year. The present study demonstrated that the association between etanercept concentration and psoriasis severity is age-dependent: when patients were stratified into three groups, patients in the youngest age group (-50 years) showed a lower PASI at a higher etanercept concentration (β = -0.26), whereas patients in the oldest age group (+59 years) showed the opposite trend (β =0.22). Similar age effects were observed in the relation of etanercept concentration with BSA (P=0.02) and PGA (P=0.02). The influence of age and length of time in therapy on the etanercept concentration-disease severity relation was unaffected by body mass index (BMI) or any other possible confounder. Incidence of anti-etanercept antibodies was low (2%). The age-dependent relation between etanercept serum concentrations is both unexpected and intriguing and needs further investigation. © 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

  9. Composition-dependent hot carrier relaxation dynamics in cesium lead halide (CsPbX{sub 3}, X=Br and I) perovskite nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Heejae; Jung, Seok Il; Kim, Hyo Jin; Cha, Wonhee; Sim, Eunji; Kim, Dongho [Department of Chemistry, Yonsei University, Seoul (Korea, Republic of); Koh, Weon-Kyu [Device Laboratory, Samsung Advanced Institute of Technology, Suwon (Korea, Republic of); Kim, Jiwon [School of Integrated Technology and Underwood International College, Yonsei University, Incheon (Korea, Republic of)

    2017-04-03

    Cesium-based perovskite nanocrystals (NCs) have outstanding photophysical properties improving the performances of lighting devices. Fundamental studies on excitonic properties and hot-carrier dynamics in perovskite NCs further suggest that these materials show higher efficiencies compared to the bulk form of perovskites. However, the relaxation rates and pathways of hot-carriers are still being elucidated. By using ultrafast transient spectroscopy and calculating electronic band structures, we investigated the dependence of halide in Cs-based perovskite (CsPbX{sub 3} with X=Br, I, or their mixtures) NCs on the hot-carrier relaxation processes. All samples exhibit ultrafast (<0.6 ps) hot-carrier relaxation dynamics with following order: CsPbBr{sub 3} (310 fs)>CsPbBr{sub 1.5}I{sub 1.5} (380 fs)>CsPbI{sub 3} NC (580 fs). These result accounts for a reduced light emission efficiency of CsPbI{sub 3} NC compared to CsPbBr{sub 3} NC. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Electron Spin Resonance Study of Interface Trap States and Charge Carrier Concentration in Rubrene Single-Crystal Field-Effect Transistors

    Science.gov (United States)

    Tsuji, Masaki; Arai, Norimichi; Marumoto, Kazuhiro; Takeya, Jun; Shimoi, Yukihiro; Tanaka, Hisaaki; Kuroda, Shin-ichi; Takenobu, Taishi; Iwasa, Yoshihiro

    2011-08-01

    Field-induced charge carriers at the semiconductor/dielectric interface of rubrene single-crystal field-effect transistors (RSC-FETs) were studied by ESR. We fabricated bottom-contact RSC-FETs to be used for ESR measurements by laminating RSCs onto SiO2 and polymer/SiO2 gate dielectric surfaces. The observed ESR spectra depict a minimal dependence on gate voltage, whose result is in sharp contrast to those obtained using RSC-FETs fabricated by the deposition of a parylene C gate dielectric. This behavior indicates that few deep trap levels are generated by the lamination technique. The dependence of ESR intensity on drain voltage was also investigated using gradual channel approximation.

  11. Spectrotemporal modulation sensitivity for hearing-impaired listeners: dependence on carrier center frequency and the relationship to speech intelligibility.

    Science.gov (United States)

    Mehraei, Golbarg; Gallun, Frederick J; Leek, Marjorie R; Bernstein, Joshua G W

    2014-07-01

    Poor speech understanding in noise by hearing-impaired (HI) listeners is only partly explained by elevated audiometric thresholds. Suprathreshold-processing impairments such as reduced temporal or spectral resolution or temporal fine-structure (TFS) processing ability might also contribute. Although speech contains dynamic combinations of temporal and spectral modulation and TFS content, these capabilities are often treated separately. Modulation-depth detection thresholds for spectrotemporal modulation (STM) applied to octave-band noise were measured for normal-hearing and HI listeners as a function of temporal modulation rate (4-32 Hz), spectral ripple density [0.5-4 cycles/octave (c/o)] and carrier center frequency (500-4000 Hz). STM sensitivity was worse than normal for HI listeners only for a low-frequency carrier (1000 Hz) at low temporal modulation rates (4-12 Hz) and a spectral ripple density of 2 c/o, and for a high-frequency carrier (4000 Hz) at a high spectral ripple density (4 c/o). STM sensitivity for the 4-Hz, 4-c/o condition for a 4000-Hz carrier and for the 4-Hz, 2-c/o condition for a 1000-Hz carrier were correlated with speech-recognition performance in noise after partialling out the audiogram-based speech-intelligibility index. Poor speech-reception and STM-detection performance for HI listeners may be related to a combination of reduced frequency selectivity and a TFS-processing deficit limiting the ability to track spectral-peak movements.

  12. Why the partition coefficient of ionic liquids is concentration-dependent.

    Science.gov (United States)

    Köddermann, Thorsten; Reith, Dirk; Arnold, A

    2013-09-19

    The partition coefficient of a substance measures its solubility in octanol compared with water and is widely used to estimate toxicity. If a substance is hardly soluble in octanol, then it is practically impossible for it to enter (human) cells and therefore is less likely to be toxic. For novel drugs it might be important to penetrate the cell through the membrane or even integrate into it. While for most simple substances the partition coefficient is concentration-independent at low concentrations, this is not true for a few important classes of complex molecules, such as ionic liquids or tensides. We present a simple association-dissociation model for concentration dependence of the partition coefficient of ionic liquids. Atomistic computer simulations serve to parametrize our model by calculating solvation free energies in water and octanol using thermodynamic integration. We demonstrate the validity of the method by reproducing the concentration-independent partition coefficients of small alcohols and the concentration-dependent partition coefficient of a commonly used ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C4MIM][NTf2]. The concentration dependence is accurately predicted in a concentration range of several orders of magnitude.

  13. Determination of the concentration dependent diffusion coefficient of nitrogen in expanded austenite

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Somers, Marcel A. J.

    2008-01-01

    The concentration dependent diffusion coefficient of nitrogen in expanded austenite was determined from of the rate of retracting nitrogen from thin initially N-saturated coupons. Nitrogen saturated homogeneous foils of expanded austenite were obtained by nitriding AISI 304 and AISI 316 in pure...... ammonia at 693 K and 718 K. Denitriding experiments were performed by equilibrating the foils with a successively lower nitrogen activity, as imposed by a gas mixture of ammonia and hydrogen. The concentration dependent diffusion coefficient of nitrogen in expanded austenite was approximated...... in the composition range where nitrogen can be extracted by hydrogen gas at the diffusion temperature. Numerical simulation of the denitriding experiments shows that the thus determined concentration dependent diffusion coefficients are an accurate approximation of the actual diffusivity of nitrogen in expanded...

  14. Direction of separation and dependence of feed concentration in liquid thermogravitational columns

    Energy Technology Data Exchange (ETDEWEB)

    Ecenarro, O.; Madariaga, J.A.; Navarro, J.; Santamaria, C.M. (Univ. Pais Vasco, Bilbao (Spain)); Carrion, J.A.; Saviron, J.M. (Univ. de Zaragoza (Spain))

    1991-08-01

    The direction of separation in a thermogravitational column was studied for 12 binary mixtures with the following components: Benzene, toluene, n-hexane, n-heptane, cyclohexane, carbon tetrachloride, tetrabromoethane, and tetrachloroethane. The separation sign is governed by the density of the components. A study was also made of the effect of feed concentration on the separation value. The shape of the curve relating separation and charge concentration was found to depend strongly on molecular mobility and molecular structure.

  15. Evaluation of light dependence of monoterpene emission and its effect on surface ozone concentration

    Science.gov (United States)

    Nishimura, Hiroshi; Shimadera, Hikari; Kondo, Akira; Bao, Hai; Shrestha, Kundan Lal; Inoue, Yoshio

    2015-03-01

    This study evaluated the effect of light intensity on monoterpene emission from the three dominant coniferous tree species in Japan (Cryptomeria japonica, Chamaecyparis obtusa and Pinus densiflora). Monoterpene emission experiments were conducted by using a growth chamber where temperature and light intensity can be controlled. In the experiments, air temperature was set at 30 °C and light intensity was set at 0, 500, 700, 850, 1200, and 1400 μmol m-2s-1. Because monoterpene emissions from the three tree species similarly increased with increasing light intensity, a new empirical equation considering light dependence was proposed to estimate monoterpene emission. In addition, monoterpene emission in the Kinki region of Japan was estimated with and without light dependence using meteorological field produced by the Weather Research and Forecasting model (WRF) in summer 2010. The monoterpene emissions estimated with light dependence were larger than those without light dependence in the daytime under clear sky conditions and consistently smaller in the nighttime. In order to evaluate the effect of light dependence of monoterpene emission on ozone concentration in the Kinki region, two cases of air quality simulations by the Community Multiscale Air Quality model (CMAQ) were conducted using the monoterpene emission data estimated with and without light dependence. Comparisons of the two cases showed that the monoterpene emission changes due to light dependence slightly but systematically affected ozone concentrations. Monoterpene generally played a role of reducing ozone concentration in the CMAQ simulations. Consequently, because of the light dependence, the mean daily maximum ozone concentrations decreased by 0.3 ppb on average with a maximum of 2.2 ppb, and the mean daily minimum values increased by 0.4 ppb on average with a maximum of 1.8 ppb in the Kinki region in summer 2010.

  16. Probing the Salt Concentration Dependent Nucelobase Distribution in a Single-Stranded DNA-Single-Walled Carbon Nanotube Hybrid with Molecular Dynamics.

    Science.gov (United States)

    Ghosh, Soumadwip; Patel, Nisheet; Chakrabarti, Rajarshi

    2016-01-28

    The hybrids of single-walled carbon nanotube (SWCNT) and single stranded DNA (ssDNA) are novel nanoscale materials having remarkable applications in nanotechnology. The absorption of nucleobases on the surface of a SWCNT depends strongly on the ionic strength of the medium. In this paper, using atomistic molecular dynamics we have shown that at low salt concentration ssDNA wraps on the surface of SWCNT through hydrophobic π-π stacking between the DNA bases and the sp(2)-hybridized carbon atoms of the carbon nanotube. At high salt concentration, however, the DNA molecule adopts a partially folded structure and the ssDNA-SWCNT wrapping gets weakened significantly due to the self-stacking of the DNA bases. Our study can find relevance in CNT mediated gene delivery processes where subsequent unwrapping of the gene from its carrier is anticipated across the cell membrane regulated by an existing salt concentration gradient.

  17. Na + concentration dependence of intermolecular distance in 3,4,9,10-perylenetetracarboxylic dianhydride dimer

    Science.gov (United States)

    Fujii, Kazuhito

    2010-01-01

    We have discussed the Na + concentration dependence of the intermolecular distance of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) dimers in aqueous solution of NaOH. We have particularly focused on the S10-S00 transition of the PTCDA dimers which is sensitive to the intermolecular distance and we have found that the S10 state is split for the higher lying sublevel and the lower lying sublevel with the increase of the Na + concentrations. From the energy shift of the lower lying sublevel, we have estimated the intermolecular distance of the PTCDA dimer, that changes from 7.5 to 4.9 Å by the Na + concentration.

  18. Concentration-dependent fluorescence live-cell imaging and tracking of intracellular nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Ji Hye; Joo, Sang-Woo [Department of Chemistry, Soongsil University, Seoul 156-743 (Korea, Republic of); Cho, Keunchang [Logos Biosystems, Incorporated, Anyang 431-070 (Korea, Republic of); Lee, So Yeong, E-mail: leeso@snu.ac.kr, E-mail: sjoo@ssu.ac.kr [Laboratory of Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 151-742 (Korea, Republic of)

    2011-06-10

    Using live-cell imaging techniques we investigated concentration-dependent intracellular movements of fluorescence nanoparticles (NPs) in real-time after their entry into HeLa cells via incubation. Intracellular particle traces appeared to be a mixture of both random and fairly unidirectional movements of the particles. At rather low concentrations of NPs, a majority of the non-random intracellular particle trajectories are assumed to mostly go along microtubule networks after endocytosis, as evidenced from the inhibition test with nocodazole. On the other hand, as the concentrations of NPs increased, random motions were more frequently observed inside the cells.

  19. A numerical investigation of oxygen concentration dependence on biodegradation rate laws in vapor intrusion.

    Science.gov (United States)

    Yao, Yijun; Shen, Rui; Pennel, Kelly G; Suuberg, Eric M

    2013-12-01

    In subsurface vapor intrusion, aerobic biodegradation has been considered as a major environmental factor that determines the soil gas concentration attenuation factors for contaminants such as petroleum hydrocarbons. The site investigation has shown that oxygen can play an important role in this biodegradation rate, and this paper explores the influence of oxygen concentration on biodegradation reactions included in vapor intrusion (VI) models. Two different three dimensional (3-D) numerical models of vapor intrusion were explored for their sensitivity to the form of the biodegradation rate law. A second order biodegradation rate law, explicitly including oxygen concentration dependence, was introduced into one model. The results indicate that the aerobic/anoxic interface depth is determined by the ratio of contaminant source vapor to atmospheric oxygen concentration, and that the contaminant concentration profile in the aerobic zone was significantly influenced by the choice of rate law.

  20. Growth hormone stimulation of serum insulin concentration in cattle: nutritional dependency and potential mechanisms.

    Science.gov (United States)

    Feng, J; Gu, Z; Wu, M; Gwazdauskas, F C; Jiang, H

    2009-08-01

    Previous studies on the effect of growth hormone (GH) on serum insulin concentration in cattle had generated seemingly conflicting results, and little was known about the mechanism by which GH affects serum insulin concentration in cattle, if it does. In this study, we determined whether the effect of GH on serum insulin concentration in cattle could be affected by the nutritional levels of the animal and whether GH increased serum insulin concentration in cattle by directly stimulating insulin release or insulin gene expression in the pancreatic islets. Administration of recombinant bovine GH increased serum insulin concentration in nonlactating, nonpregnant beef cows fed a daily concentrate meal in addition to ad libitum hay, but it had no effect in those cows fed hay only. Both GH treatments for 1 and 24h increased insulin concentrations in cultures of pancreatic islets isolated from growing cattle. Growth hormone treatment for 24h increased insulin mRNA expression in cultured bovine pancreatic islets. Growth hormone treatment for 16h increased reporter gene expression directed by a approximately 1,500-bp bovine insulin gene promoter in a rat insulin-producing beta cell line. Taken together, these results suggest that exogenous GH can increase serum insulin concentration in cattle, but this effect depends on the nutritional levels of fed cattle, and that GH increases serum insulin concentration in cattle by stimulating both insulin release and insulin gene expression in the pancreatic islets.

  1. Serum cholecystokinin concentrations in dogs with naturally acquired pituitary-dependent hyperadrenocorticism.

    Science.gov (United States)

    Noh, Sungjun; Kim, Hye-Sun; Chang, Jinhwa; Kang, Ji-Houn; Chang, Dongwoo; Yang, Mhan-Pyo

    2016-10-01

    OBJECTIVE To determine serum cholecystokinin (CCK) concentrations in dogs with pituitary-dependent hyperadrenocorticism (PDH) and to evaluate associations among CCK concentration, PDH, and gallbladder mucocele (GBM). ANIMALS 14 client-owned dogs with PDH and 14 healthy dogs. PROCEDURES Dogs were separated into 4 groups: healthy dogs without gallbladder sludge (group A; n = 7), healthy dogs with gallbladder sludge (group B; 7), dogs with PDH and gallbladder sludge (group C; 8), and dogs with PDH and GBM (group D; 6). Serum CCK concentrations were then measured before and 1, 2, and 4 hours after consumption of a high-fat meal. Concentrations in dogs with PDH were also measured before and after trilostane treatment. Results were compared among groups and assessment points. RESULTS Preprandial serum CCK concentrations in group C were significantly lower than those in groups A, B, and D, but no significant differences in postprandial CCK concentrations were identified among the groups 1, 2, or 4 hours after the meal. With respect to trilostane treatment of dogs with PDH, no significant differences were identified between pre- and post-trilostane serum CCK concentrations in group C or D. Median CCK concentration after trilostane treatment was higher in group D than in group C, but this difference was not significant. CONCLUSIONS AND CLINICAL RELEVANCE The outcomes in this study did not support the hypothesis that a low circulating CCK concentration affects the development of GBM in dogs with PDH.

  2. Glymphatic clearance controls state-dependent changes in brain lactate concentration

    DEFF Research Database (Denmark)

    Lundgaard, Iben; Lu, Minh Lon; Yang, Ezra

    2016-01-01

    Brain lactate concentration is higher during wakefulness than in sleep. However, it is unknown why arousal is linked to an increase in brain lactate and why lactate declines within minutes of sleep. Here, we show that the glymphatic system is responsible for state-dependent changes in brain lacta...

  3. Concentration-Dependant Changes of PCB Patterns in Fish-Eating Mammals

    DEFF Research Database (Denmark)

    Boon, J.P.; van der Meer, J.; Allchin, C.R.

    1997-01-01

    - and meta-positions and with one ortho-chlorine substituent generally increased in the order otter cetaceans (harbor porpoise, common dolphin) ... in the order cetaceans cetaceans, the pinnipeds, and the otter. Within-species CB patterns differed in a concentration-dependent manner...

  4. Convective-diffusive Cahn-Hilliard Equation with Concentration Dependent Mobility

    Institute of Scientific and Technical Information of China (English)

    刘长春; 尹景学

    2003-01-01

    In this paer,we study the global existence of classical solutions for the convective-diffusive Cahn-Hilliard Equation with concentration dependent mobility.Based on the Schauder type estimates,we establish the global existence of classical solutions.

  5. Confinement dependent chemotaxis in two-photon polymerized linear migration constructs with highly definable concentration gradients

    DEFF Research Database (Denmark)

    Hjortø, Gertrud Malene; Olsen, Mark Holm; Svane, Inge Marie

    2015-01-01

    Dendritic cell chemotaxis is known to follow chemoattractant concentration gradients through tissue of heterogeneous pore sizes, but the dependence of migration velocity on pore size and gradient steepness is not fully understood. We enabled chemotaxis studies for at least 42 hours at confinement...

  6. Estimation of Collection Efficiency Depended on Feed Particle Concentration for Axial Flow Cyclone Dust Collector

    Institute of Scientific and Technical Information of China (English)

    AkiraOgawa

    1999-01-01

    A cyclone dust collector is applied in many industries.Especially the axial flow cyclone is the most simple construction and if keeps high reliability for maintenance.On the other hand,the collection efficiency of the cyclone depends not only on the inlet gas velocity but also on the feed particle concentration.The collection efficiency increases with increasing feed particle concentration.However until now the problem of how to estimate the collection efficiency depended on the feed particle concentration is remained except the investigation by Muschelknautz & Brunner[6],Therefore in this paper one of the estimate method for the collection efficiency of the axial flow cyclones is proposed .The application to the geometrically similar type of cyclone of the body diameters D1=30,50,69and 99mm showed in good agreement with the experimental results of the collection efficiencies which were described in detail in the paper by ogawa & Sugiyama[8].

  7. Concentration-dependent effects of fullerenol on cultured hippocampal neuron viability

    Directory of Open Access Journals (Sweden)

    Zha YY

    2012-06-01

    Full Text Available Ying-ying Zha,1 Bo Yang,1 Ming-liang Tang,2 Qiu-chen Guo,1 Ju-tao Chen,1 Long-ping Wen,3 Ming Wang11CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, University of Science and Technology of China, Hefei, 2Suzhou Institute of NanoTech and NanoBionics, Chinese Academy of Sciences, Suzhou, 3Laboratory of Nano-biology, School of Life Sciences, University of Science and Technology of China, Hefei, People's Republic of ChinaBackground: Recent studies have shown that the biological actions and toxicity of the water-soluble compound, polyhydroxyfullerene (fullerenol, are related to the concentrations present at a particular site of action. This study investigated the effects of different concentrations of fullerenol on cultured rat hippocampal neurons.Methods and results: Fullerenol at low concentrations significantly enhanced hippocampal neuron viability as tested by MTT assay and Hoechst 33342/propidium iodide double stain detection. At high concentrations, fullerenol induced apoptosis confirmed by Comet assay and assessment of caspase proteins.Conclusion: These findings suggest that fullerenol promotes cell death and protects against cell damage, depending on the concentration present. The concentration-dependent effects of fullerenol were mainly due to its influence on the reduction-oxidation pathway.Keywords: fullerenol, nanomaterial, neurotoxicity, neuroprotection, hippocampal neuron

  8. Concentration Dependent Speciation and Mass Transport Properties of Switchable Polarity Solvents

    Energy Technology Data Exchange (ETDEWEB)

    Aaron D. Wilson; Christopher J. Orme

    2014-12-01

    Tertiary amine switchable polarity solvents (SPS) consisting of predominantly water, tertiary amine, and tertiary ammonium and bicarbonate ions were produced at various concentrations for three different amines: N,N-dimethylcyclohexylamine, N,N-dimethyloctylamine, and 1 cyclohexylpiperidine. For all concentrations, physical properties were measured including viscosity, molecular diffusion coefficients, freezing point depression, and density. Based on these measurements a variation on the Mark Houwink equation was developed to predict the viscosity of any tertiary amine SPS as a function of concentration using the amine’s molecular mass. The observed physical properties allowed the identification of solution state speciation of non-osmotic SPS, where the amine to carbonic acid ratio is significantly greater than one. These results indicate that at most concentrations the stoichiometric excess amine is involved in solvating a proton with two amines. The physical properties of osmotic SPS have consistent concentration dependence behavior over a wide range of concentrations; this consistence suggests osmotic pressures based on low concentrations freezing point studies can be reliably extrapolated to higher concentrations.

  9. Concentration-dependent rheological properties of ECM hydrogel for intracerebral delivery to a stroke cavity.

    Science.gov (United States)

    Massensini, Andre R; Ghuman, Harmanvir; Saldin, Lindsey T; Medberry, Christopher J; Keane, Timothy J; Nicholls, Francesca J; Velankar, Sachin S; Badylak, Stephen F; Modo, Michel

    2015-11-01

    Biomaterials composed of mammalian extracellular matrix (ECM) promote constructive tissue remodeling with minimal scar tissue formation in many anatomical sites. However, the optimal shape and form of ECM scaffold for each clinical application can vary markedly. ECM hydrogels have been shown to promote chemotaxis and differentiation of neuronal stem cells, but minimally invasive delivery of such scaffold materials to the central nervous system (CNS) would require an injectable form. These ECM materials can be manufactured to exist in fluid phase at room temperature, while forming hydrogels at body temperature in a concentration-dependent fashion. Implantation into the lesion cavity after a stroke could hence provide a means to support endogenous repair mechanisms. Herein, we characterize the rheological properties of an ECM hydrogel composed of urinary bladder matrix (UBM) that influence its delivery and in vivo interaction with host tissue. There was a notable concentration-dependence in viscosity, stiffness, and elasticity; all characteristics important for minimally invasive intracerebral delivery. An efficient MRI-guided injection with drainage of fluid from the cavity is described to assess in situ hydrogel formation and ECM retention at different concentrations (0, 1, 2, 3, 4, and 8mg/mL). Only ECM concentrations >3mg/mL gelled within the stroke cavity. Lower concentrations were not retained within the cavity, but extensive permeation of the liquid phase ECM into the peri-infarct area was evident. The concentration of ECM hydrogel is hence an important factor affecting gelation, host-biomaterial interface, as well intra-lesion distribution. Extracellular matrix (ECM) hydrogel promotes constructive tissue remodeling in many tissues. Minimally invasive delivery of such scaffold materials to the central nervous system (CNS) would require an injectable form that exists in fluid phase at room temperature, while forming hydrogels at body temperature in a

  10. Upconversion NaYF4 Nanoparticles for Size Dependent Cell Imaging and Concentration Dependent Detection of Rhodamine B

    Directory of Open Access Journals (Sweden)

    Shigang Hu

    2015-01-01

    Full Text Available Upconversion nanoparticles (UCNPs based on NaYF4 nanocrystals with strong upconversion luminescence are synthesized by the solvothermal method. The emission color of these NaYF4 upconversion nanoparticles can be easily modulated by the doping. These NaYF4 upconversion nanocrystals can be employed as fluorescence donors to pump fluorescent organic molecules. For example, the efficient luminescence resonant energy transfer (LRET can be achieved by controlling the distance between NaYF4:Yb3+/Er3+ UCNPs and Rhodamine B (RB. NaYF4:Yb3+/Er3+ UCNPs can emit green light at the wavelength of ~540 nm while RB can efficiently absorb the green light of ~540 nm to emit red light of 610 nm. The LRET efficiency is highly dependent on the concentration of NaYF4 upconversion fluorescent donors. For the fixed concentration of 3.2 µg/mL RB, the optimal concentration of NaYF4:Yb3+/Er3+ UCNPs is equal to 4 mg/mL which generates the highest LRET signal ratio. In addition, it is addressed that the upconversion nanoparticles with diameter of 200 nm are suitable for imaging the cells larger than 10 µm with clear differentiation between cell walls and cytoplasm.

  11. Communication: Modeling of concentration dependent water diffusivity in ionic solutions: Role of intermolecular charge transfer.

    Science.gov (United States)

    Yao, Yi; Berkowitz, Max L; Kanai, Yosuke

    2015-12-28

    The translational diffusivity of water in solutions of alkali halide salts depends on the identity of ions, exhibiting dramatically different behavior even in solutions of similar salts of NaCl and KCl. The water diffusion coefficient decreases as the salt concentration increases in NaCl. Yet, in KCl solution, it slightly increases and remains above bulk value as salt concentration increases. Previous classical molecular dynamics simulations have failed to describe this important behavior even when polarizable models were used. Here, we show that inclusion of dynamical charge transfer among water molecules produces results in a quantitative agreement with experiments. Our results indicate that the concentration-dependent diffusivity reflects the importance of many-body effects among the water molecules in aqueous ionic solutions. Comparison with quantum mechanical calculations shows that a heterogeneous and extended distribution of charges on water molecules around the ions due to ion-water and also water-water charge transfer plays a very important role in controlling water diffusivity. Explicit inclusion of the charge transfer allows us to model accurately the difference in the concentration-dependent water diffusivity between Na(+) and K(+) ions in simulations, and it is likely to impact modeling of a wide range of systems for medical and technological applications.

  12. Frontal Metabolite Concentration Deficits in Opiate Dependence Relate to Substance Use, Cognition, and Self-Regulation

    Science.gov (United States)

    Murray, Donna E; Durazzo, Timothy C; Schmidt, Thomas P; Abé, Christoph; Guydish, Joseph; Meyerhoff, Dieter J

    2016-01-01

    Objective Proton magnetic resonance spectroscopy (1H MRS) in opiate dependence showed abnormalities in neuronal viability and glutamate concentration in the anterior cingulate cortex (ACC). Metabolite levels in dorsolateral prefrontal cortex (DLPFC) or orbitofrontal cortex (OFC) and their neuropsychological correlates have not been investigated in opiate dependence. Methods Single-volume proton MRS at 4 Tesla and neuropsychological testing were conducted in 21 opiate-dependent individuals (OD) on buprenorphine maintenance therapy. Results were compared to 28 controls (CON) and 35 alcohol-dependent individuals (ALC), commonly investigated treatment-seekers providing context for OD evaluation. Metabolite concentrations were measured from ACC, DLPFC, OFC and parieto-occipital cortical (POC) regions. Results Compared to CON, OD had lower concentrations of N-acetylaspartate (NAA), glutamate (Glu), creatine +phosphocreatine (Cr) and myo-Inositol (mI) in the DLPFC and lower NAA, Cr, and mI in the ACC. OD, ALC, and CON were equivalent on metabolite levels in the POC and γ-aminobutyric acid (GABA) concentration did not differ between groups in any region. In OD, prefrontal metabolite deficits in ACC Glu as well as DLPFC NAA and choline containing metabolites (Cho) correlated with poorer working memory, executive and visuospatial functioning; metabolite deficits in DLPFC Glu and ACC GABA and Cr correlated with substance use measures. In the OFC of OD, Glu and choline-containing metabolites were elevated and lower Cr concentration related to higher nonplanning impulsivity. Compared to 3 week abstinent ALC, OD had significant DLPFC metabolite deficits. Conclusion The anterior frontal metabolite profile of OD differed significantly from that of CON and ALC. The frontal lobe metabolite abnormalities in OD and their neuropsychological correlates may play a role in treatment outcome and could be explored as specific targets for improved OD treatment. PMID:27695638

  13. Generation-dependent charge carrier transport in Cu(In,Ga)Se2/CdS/ZnO thin-film solar-cells

    Science.gov (United States)

    Nichterwitz, Melanie; Caballero, Raquel; Kaufmann, Christian A.; Schock, Hans-Werner; Unold, Thomas

    2013-01-01

    Cross section electron-beam induced current (EBIC) and illumination-dependent current voltage (IV) measurements show that charge carrier transport in Cu(In,Ga)Se2 (CIGSe)/CdS/ZnO solar-cells is generation-dependent. We perform a detailed analysis of CIGSe solar cells with different CdS layer thicknesses and varying Ga-content in the absorber layer. In conjunction with numerical simulations, EBIC and IV data are used to develop a consistent model for charge and defect distributions with a focus on the heterojunction region. The best model to explain our experimental data is based on a p+ layer at the CIGSe/CdS interface leading to generation-dependent transport in EBIC at room temperature. Acceptor-type defect states at the CdS/ZnO interface cause a significant reduction of the photocurrent in the red-light illuminated IV characteristics at low temperatures (red kink effect). Shallow donor-type defect states at the p+ layer/CdS interface of some grains of the absorber layer are responsible for grain specific, i.e., spatially inhomogeneous, charge carrier transport observed in EBIC.

  14. Concentration and size dependence of peak wavelength shift on quantum dots in colloidal suspension

    Science.gov (United States)

    Rinehart, Benjamin S.; Cao, Caroline G. L.

    2016-08-01

    Quantum dots (QDs) are semiconductor nanocrystals that have significant advantages over organic fluorophores, including their extremely narrow Gaussian emission bands and broad absorption bands. Thus, QDs have a wide range of potential applications, such as in quantum computing, photovoltaic cells, biological sensing, and electronics. For these applications, aliasing provides a detrimental effect on signal identification efficiency. This can be avoided through characterization of the QD fluorescence signals. Characterization of the emissivity of CdTe QDs as a function of concentration (1 to 10 mg/ml aqueous) was conducted on 12 commercially available CdTe QDs (emission peaks 550 to 730 nm). The samples were excited by a 50-mW 405-nm laser with emission collected via a free-space CCD spectrometer. All QDs showed a redshift effect as concentration increased. On average, the CdTe QDs exhibited a maximum shift of +35.6 nm at 10 mg/ml and a minimum shift of +27.24 nm at 1 mg/ml, indicating a concentration dependence for shift magnitude. The concentration-dependent redshift function can be used to predict emission response as QD concentration is changed in a complex system.

  15. Catalytic conversion reactions in nanoporous systems with concentration-dependent selectivity: Statistical mechanical modeling

    Science.gov (United States)

    García, Andrés; Wang, Jing; Windus, Theresa L.; Sadow, Aaron D.; Evans, James W.

    2016-05-01

    Statistical mechanical modeling is developed to describe a catalytic conversion reaction A →Bc or Bt with concentration-dependent selectivity of the products, Bc or Bt, where reaction occurs inside catalytic particles traversed by narrow linear nanopores. The associated restricted diffusive transport, which in the extreme case is described by single-file diffusion, naturally induces strong concentration gradients. Furthermore, by comparing kinetic Monte Carlo simulation results with analytic treatments, selectivity is shown to be impacted by strong spatial correlations induced by restricted diffusivity in the presence of reaction and also by a subtle clustering of reactants, A .

  16. Longitudinal dispersion with time-dependent source concentration in semi-infinite aquifer

    Indian Academy of Sciences (India)

    Mritunjay Kumar Singh; Nav Kumar Mahato; Premlata Singh

    2008-12-01

    An analytical solution is obtained to predict the contaminant concentration along unsteady ground-water flow in semi-in finite aquifer. Initially,the aquifer is not supposed to be solute free ,i.e.,aquifer is not clean.A time-dependent source concentration is considered at the origin of the aquifer and at the other end of the aquifer, it is supposed to be zero. The time-dependent forms of unsteady velocities are considered in which one such form ,i.e., sinusoidal form represents the seasonal pattern in a year in tropical regions. The Laplace Transformation Technique (LTT)is used to get an analytical solution and a graphical representation is made through MATLAB.

  17. Ionic concentration- and pH-dependent electrophoretic mobility as studied by single colloid electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Semenov, I; Papadopoulos, P; Kremer, F [Institute for Experimental Physics I (MOP), University of Leipzig, Linnestrasse 5, 04103 Leipzig (Germany); Stober, G, E-mail: friedrich.kremer@physik.uni-leipzig.d [Institute of Atmospheric Physics, University of Rostock, Schlossstrasse 6, 18225 Kuehlungsborn (Germany)

    2010-12-15

    Optical tweezers are employed to measure separately the complex electrophoretic mobility of a single colloid and the complex electroosmotic response of the surrounding medium in a specially designed microfluidic cell. Using the very same colloid both quantities are determined in dependence on the concentration of the aqueous salt solution (10{sup -5}-10{sup -1} mol l{sup -1}), the valence of the ions (K{sup +}, Ca{sup 2+}) and the pH (2.5-8.5). A pronounced effect is observed for all these examined parameters. The dependence on ion concentration agrees qualitatively-for the monovalent case-with the predictions of the standard electrokinetic model.

  18. Concentration and crystallite size dependence of the photoluminescence in YAG:Ce3+ nanophosphor

    Science.gov (United States)

    Ovalle, Raquel; Arredondo, Alejandro; Diaz-Torres, Luis A.; Salas, Pedro; Angeles, Carlos; Rodriguez, Ruben A.; Meneses, Marco A.; De la Rosa, Elder

    2004-10-01

    Nanocrystalline yttrium aluminum garnet doped with Cerium (YAG:Ce3+), was synthesized by means of a modified sol-gel method that consists of a mixture of salts in an aqueous media. Structure and morphology were characterized by X-ray diffraction and Transmission Electron Microscopy. Single crystalline phase were obtained and the crystallite size range from 26 nm to 96 nm depending on the annealing temperature (from 800 to 1150 °C, respectively). The photoluminescence dependence on the crystallite size and ion concentration was performed. The experimental results show that the best ion concentration where the highest luminescence was obtained correspond to 0.1 mol% and that increases as the crystallite size increases. The feasibility of the modified sol-gel method for the preparation of nanocrystalline YAG is discussed.

  19. Concentration and Temperature Dependences of YBO3:Bi3+ Luminescence under Vacuum Ultraviolet Excitation

    Institute of Scientific and Technical Information of China (English)

    CHEN Lei; JIANG Yang; ZHANG Guo-Bin; WU Can; YANG Guang-Tao; WANG Chun; LI Guo-Hua

    2008-01-01

    Bi3+ doped YBO3 phosphors are prepared by solid state reaction and their luminescent properties are invest gated by using synchrotron radiation instrument.Concentration and temperature dependences of YBO3:Bi3+luminescence under VUV/UV excitation is observed.The emission and excitation spectra are assigned,and th mechanism for these phenomena is explored,which result from the energy transfer between Bi3+ ions occupyin different sites in YB03 crystal lattice.

  20. Dopant concentration dependence of the response of SiC Schottky diodes to light ions

    Energy Technology Data Exchange (ETDEWEB)

    De Napoli, M. [Dipartimento di Fisica e Astronomia, Universita degli Studi di Catania, Via S. Sofia 64, I-95123 Catania (Italy); Laboratori Nazionali del Sud, Via S. Sofia 62, I-95123 Catania (Italy); Giacoppo, F. [Laboratori Nazionali del Sud, Via S. Sofia 62, I-95123 Catania (Italy); Dipartimento di Fisica, Universita degli Studi di Messina, Via Salita Sperone 31, I-98166 Messina (Italy); Raciti, G. [Dipartimento di Fisica e Astronomia, Universita degli Studi di Catania, Via S. Sofia 64, I-95123 Catania (Italy); Isituto Nazionale di Fisica Nucleare, Sezione di Catania, Via S. Sofia 64, I-95123 Catania (Italy)], E-mail: raciti@lns.infn.it; Rapisarda, E. [Dipartimento di Fisica e Astronomia, Universita degli Studi di Catania, Via S. Sofia 64, I-95123 Catania (Italy); Isituto Nazionale di Fisica Nucleare, Sezione di Catania, Via S. Sofia 64, I-95123 Catania (Italy)

    2009-03-11

    The responses of Silicon Carbide (SiC) Schottky diodes of different dopant concentration to {sup 12}C ions at 14.2, 28.1 and 37.6 MeV incident energies are compared. The relation between the applied reverse bias and the thickness of the depleted epitaxial region is studied for different dopant concentrations. The experimental data show that SiC diodes with lower dopant concentration need lower reverse bias to be depleted. Moreover it has been observed that the energy resolution, measured as a function of the applied reverse bias and of the ions incident energies, does not depend on the dopant concentration. The radiation damage, produced by irradiating SiC diodes of different dopant concentration with {sup 16}O ions at 35.2 MeV, was evaluated by measuring the degradation of both the signal pulse-height and the energy resolution as a function of the {sup 16}O fluence. Diodes having a factor 20 lower dopant concentration exhibit a radiation hardness reduced by 60%. No inversion in the signal at the breakdown fluence was observed for {sup 16}O ions stopped inside the diode epitaxial region.

  1. Nonmonotonous concentration behaviour of T sub c in Van-Hove scenario

    CERN Document Server

    Kozlov, A N

    2002-01-01

    Dependence of T sub c on doping in the Hubbard model with a low- repulsion in the range of carrier concentration, where the Cooper amplitude depends on the system vicinity to spin density wave transition, is considered. It is shown that in the Van Hove scenario in the range of optimal doping nonmonotonous dependence of T sub c on carrier concentration is observed

  2. Improved estimation of sediment source contributions by concentration-dependent Bayesian isotopic mixing model

    Science.gov (United States)

    Ram Upadhayay, Hari; Bodé, Samuel; Griepentrog, Marco; Bajracharya, Roshan Man; Blake, Will; Cornelis, Wim; Boeckx, Pascal

    2017-04-01

    The implementation of compound-specific stable isotope (CSSI) analyses of biotracers (e.g. fatty acids, FAs) as constraints on sediment-source contributions has become increasingly relevant to understand the origin of sediments in catchments. The CSSI fingerprinting of sediment utilizes CSSI signature of biotracer as input in an isotopic mixing model (IMM) to apportion source soil contributions. So far source studies relied on the linear mixing assumptions of CSSI signature of sources to the sediment without accounting for potential effects of source biotracer concentration. Here we evaluated the effect of FAs concentration in sources on the accuracy of source contribution estimations in artificial soil mixture of three well-separated land use sources. Soil samples from land use sources were mixed to create three groups of artificial mixture with known source contributions. Sources and artificial mixture were analysed for δ13C of FAs using gas chromatography-combustion-isotope ratio mass spectrometry. The source contributions to the mixture were estimated using with and without concentration-dependent MixSIAR, a Bayesian isotopic mixing model. The concentration-dependent MixSIAR provided the closest estimates to the known artificial mixture source contributions (mean absolute error, MAE = 10.9%, and standard error, SE = 1.4%). In contrast, the concentration-independent MixSIAR with post mixing correction of tracer proportions based on aggregated concentration of FAs of sources biased the source contributions (MAE = 22.0%, SE = 3.4%). This study highlights the importance of accounting the potential effect of a source FA concentration for isotopic mixing in sediments that adds realisms to mixing model and allows more accurate estimates of contributions of sources to the mixture. The potential influence of FA concentration on CSSI signature of sediments is an important underlying factor that determines whether the isotopic signature of a given source is observable

  3. A Novel Technique to Determine Concentration-Dependent Solvent Dispersion in Vapex

    Directory of Open Access Journals (Sweden)

    Hadil Abukhalifeh

    2009-10-01

    Full Text Available Vapex (vapor extraction of heavy oil and bitumen is a promising recovery technology because it consumes low energy, and is very environmentally-friendly. The dispersion of solvents into heavy oil and bitumen is a crucial transport property governing Vapex. The accurate determination of solvent dispersion in Vapex is essential to effectively predict the amount and time scale of oil recovery as well to optimize the field operations. In this work, a novel technique is developed to experimentally determine the concentration-dependent dispersion coefficient of a solvent in Vapex process. The principles of variational calculus are utilized in conjunction with a mass transfer model of the experimental Vapex process. A computational algorithm is developed to optimally compute solvent dispersion as a function of its concentration in heavy oil. The developed technique is applied to Vapex utilizing propane as a solvent. The results show that dispersion of propane is a unimodal function of its concentration in bitumen.

  4. Temperature-dependent transformation thermotics for unsteady states: Switchable concentrator for transient heat flow

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ying, E-mail: 13110290008@fudan.edu.cn [Department of Mechanics and Engineering Science, Fudan University, Shanghai 200433 (China); Shen, Xiangying, E-mail: 13110190068@fudan.edu.cn [Department of Physics, State Key Laboratory of Surface Physics, and Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 (China); Huang, Jiping, E-mail: jphuang@fudan.edu.cn [Department of Physics, State Key Laboratory of Surface Physics, and Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 (China); Ni, Yushan, E-mail: niyushan@fudan.edu.cn [Department of Mechanics and Engineering Science, Fudan University, Shanghai 200433 (China)

    2016-04-22

    For manipulating heat flow efficiently, recently we established a theory of temperature-dependent transformation thermotics which holds for steady-state cases. Here, we develop the theory to unsteady-state cases by considering the generalized Fourier's law for transient thermal conduction. As a result, we are allowed to propose a new class of intelligent thermal metamaterial — switchable concentrator, which is made of inhomogeneous anisotropic materials. When environmental temperature is below or above a critical value, the concentrator is automatically switched on, namely, it helps to focus heat flux in a specific region. However, the focusing does not affect the distribution pattern of temperature outside the concentrator. We also perform finite-element simulations to confirm the switching effect according to the effective medium theory by assembling homogeneous isotropic materials, which bring more convenience for experimental fabrication than inhomogeneous anisotropic materials. This work may help to figure out new intelligent thermal devices, which provide more flexibility in controlling heat flow, and it may also be useful in other fields that are sensitive to temperature gradient, such as the Seebeck effect. - Highlights: • Established the unsteady-state temperature dependent transformation thermotics. • A thermal concentrator with switchable functionality. • An effective-medium design for experimental realization.

  5. Iron oxyhydroxide nanoparticles formed by forced hydrolysis: dependence of phase composition on solution concentration.

    Science.gov (United States)

    Fu, Dong; Keech, Peter G; Sun, Xueliang; Wren, J Clara

    2011-11-07

    Nanoparticles of single-phase lepidocrocite (γ-FeOOH) and goethite (α-FeOOH) have been synthesized by forced hydrolysis of ferric nitrate with no other additives, and the particles have been characterized by XRD, FT-IR and TEM. At low Fe(NO(3))(3) concentrations the hydrolysis product is predominantly γ-FeOOH, while at high concentrations it is α-FeOOH. These particles are nanometers in size and fall within narrow particle size distributions. The dependence of the oxyhydoxide phase on ferric nitrate concentration is attributed to two thermodynamic factors, the enthalpy of formation and the surface enthalpy of hydration at the oxide-water interface (which is a function of surface area). Two potential mechanisms for the phase-specific growth are proposed that explain the solution concentration dependence of the phase formed. Three other common nanoscale particles (α-Fe(2)O(3), Fe(3)O(4) and γ-Fe(2)O(3)) have also been prepared by relatively simple thermal/chemical treatment of the γ-FeOOH nanoparticles.

  6. Physics-Based Compact Model for CIGS and CdTe Solar Cells: From Voltage-Dependent Carrier Collection to Light-Enhanced Reverse Breakdown: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xingshu; Alam, Muhammad Ashraful; Raguse, John; Garris, Rebekah; Deline, Chris; Silverman, Timothy

    2015-10-15

    In this paper, we develop a physics-based compact model for copper indium gallium diselenide (CIGS) and cadmium telluride (CdTe) heterojunction solar cells that attributes the failure of superposition to voltage-dependent carrier collection in the absorber layer, and interprets light-enhanced reverse breakdown as a consequence of tunneling-assisted Poole-Frenkel conduction. The temperature dependence of the model is validated against both simulation and experimental data for the entire range of bias conditions. The model can be used to characterize device parameters, optimize new designs, and most importantly, predict performance and reliability of solar panels including the effects of self-heating and reverse breakdown due to partial-shading degradation.

  7. Convective instability in a two-layer system of reacting fluids with concentration-dependent diffusion

    Science.gov (United States)

    Aitova, E. V.; Bratsun, D. A.; Kostarev, K. G.; Mizev, A. I.; Mosheva, E. A.

    2016-12-01

    The development of convective instability in a two-layer system of miscible fluids placed in a narrow vertical gap has been studied theoretically and experimentally. The upper and lower layers are formed with aqueous solutions of acid and base, respectively. When the layers are brought into contact, the frontal neutralization reaction begins. We have found experimentally a new type of convective instability, which is characterized by the spatial localization and the periodicity of the structure observed for the first time in the miscible systems. We have tested a number of different acid-base systems and have found a similar patterning there. In our opinion, it may indicate that the discovered effect is of a general nature and should be taken into account in reaction-diffusion-convection problems as another tool with which the reaction can govern the movement of the reacting fluids. We have shown that, at least in one case (aqueous solutions of nitric acid and sodium hydroxide), a new type of instability called as the concentration-dependent diffusion convection is responsible for the onset of the fluid flow. It arises when the diffusion coefficients of species are different and depend on their concentrations. This type of instability can be attributed to a variety of double-diffusion convection. A mathematical model of the new phenomenon has been developed using the system of reaction-diffusion-convection equations written in the Hele-Shaw approximation. It is shown that the instability can be reproduced in the numerical experiment if only one takes into account the concentration dependence of the diffusion coefficients of the reagents. The dynamics of the base state, its linear stability and nonlinear development of the instability are presented. It is also shown that by varying the concentration of acid in the upper layer one can achieve the occurrence of chemo-convective solitary cell in the bulk of an almost immobile fluid. Good agreement between the

  8. Serum fructosamine concentration as measure of blood glucose control in type I (insulin dependent) diabetes mellitus.

    Science.gov (United States)

    Baker, J R; Metcalf, P A; Holdaway, I M; Johnson, R N

    1985-01-01

    Serum fructosamine activity was studied in 42 patients with type I (insulin dependent) diabetes mellitus and 30 non-diabetic volunteers as an index of blood glucose control. There was a significant correlation both between fructosamine and glycosylated haemoglobin values (r = 0.82) and between fructosamine and the fasting C peptide concentration (r = -0.81). Test results in 14 of the diabetics reflected the mean plasma glucose concentration calculated from 25 serial estimations in a single 24 hour period (r = 0.75; p less than 0.01) but not the mean amplitude of glycaemic excursion (r = 0.23; p greater than 0.05). Fructosamine concentrations measured in these multiple blood specimens did not change significantly throughout the day (mean coefficient of variation 4.1%) despite wide variability of the respective plasma glucose concentrations (mean coefficient of variation 36.2%). It is concluded that a single random serum sample analysed for fructosamine concentration provides a simple and reliable assessment of glucose homoeostasis in patients with type I diabetes mellitus. PMID:3917816

  9. Reduced plasma aldosterone concentrations in randomly selected patients with insulin-dependent diabetes mellitus.

    LENUS (Irish Health Repository)

    Cronin, C C

    2012-02-03

    Abnormalities of the renin-angiotensin system have been reported in patients with diabetes mellitus and with diabetic complications. In this study, plasma concentrations of prorenin, renin, and aldosterone were measured in a stratified random sample of 110 insulin-dependent (Type 1) diabetic patients attending our outpatient clinic. Fifty-four age- and sex-matched control subjects were also examined. Plasma prorenin concentration was higher in patients without complications than in control subjects when upright (geometric mean (95% confidence intervals (CI): 75.9 (55.0-105.6) vs 45.1 (31.6-64.3) mU I-1, p < 0.05). There was no difference in plasma prorenin concentration between patients without and with microalbuminuria and between patients without and with background retinopathy. Plasma renin concentration, both when supine and upright, was similar in control subjects, in patients without complications, and in patients with varying degrees of diabetic microangiopathy. Plasma aldosterone was suppressed in patients without complications in comparison to control subjects (74 (58-95) vs 167 (140-199) ng I-1, p < 0.001) and was also suppressed in patients with microvascular disease. Plasma potassium was significantly higher in patients than in control subjects (mean +\\/- standard deviation: 4.10 +\\/- 0.36 vs 3.89 +\\/- 0.26 mmol I-1; p < 0.001) and plasma sodium was significantly lower (138 +\\/- 4 vs 140 +\\/- 2 mmol I-1; p < 0.001). We conclude that plasma prorenin is not a useful early marker for diabetic microvascular disease. Despite apparently normal plasma renin concentrations, plasma aldosterone is suppressed in insulin-dependent diabetic patients.

  10. Inhibition of bacterial surface colonization by immobilized silver nanoparticles depends critically on the planktonic bacterial concentration.

    Science.gov (United States)

    Wirth, Stacy M; Bertuccio, Alex J; Cao, Feng; Lowry, Gregory V; Tilton, Robert D

    2016-04-01

    Immobilization of antimicrobial silver nanoparticles (AgNPs) on surfaces has been proposed as a method to inhibit biofouling or as a possible route by which incidental releases of AgNPs may interfere with biofilms in the natural environment or in wastewater treatment. This study addresses the ability of planktonic Pseudomonas fluorescens bacteria to colonize surfaces with pre-adsorbed AgNPs. The ability of the AgNP-coated surfaces to inhibit colonization was controlled by the dissolved silver in the system, with a strong dependence on the initial planktonic cell concentration in the suspension, i.e., a strong inoculum effect. This dependence was attributed to a decrease in dissolved silver ion bioavailability and toxicity caused by its binding to cells and/or cell byproducts. Therefore, when the initial cell concentration was high (∼1×10(7)CFU/mL), an excess of silver binding capacity removed most of the free silver and allowed both planktonic growth and surface colonization directly on the AgNP-coated surface. When the initial cell concentration was low (∼1×10(5)CFU/mL), 100% killing of the planktonic cell inoculum occurred and prevented colonization. When an intermediate initial inoculum concentration (∼1×10(6)CFU/mL) was sufficiently large to prevent 100% killing of planktonic cells, even with 99.97% initial killing, the planktonic population recovered and bacteria colonized the AgNP-coated surface. In some conditions, colonization of AgNP-coated surfaces was enhanced relative to silver-free controls, and the bacteria demonstrated a preferential attachment to AgNP-coated, rather than bare, surface regions. The degree to which the bacterial concentration dictates whether or not surface-immobilized AgNPs can inhibit colonization has significant implications both for the design of antimicrobial surfaces and for the potential environmental impacts of AgNPs.

  11. Understanding different efficiency droop behaviors in InGaN-based near-UV, blue and green light-emitting diodes through differential carrier lifetime measurements

    CERN Document Server

    Wang, Lai; Wang, Jiaxing; Hao, Zhibiao; Luo, Yi; Sun, Changzheng; Han, Yanjun; Xiong, Bing; Wang, Jian; Li, Hongtao

    2016-01-01

    Efficiency droop effect under high injection in GaN-based light emitting diodes (LEDs) strongly depends on wavelength, which is still not well understood. In this paper, through differential carrier lifetime measurements on commercialized near-UV, blue, and green LEDs, their different efficiency droop behaviors are attributed to different carrier lifetimes, which are prolonged as wavelength increases. This relationship between carrier lifetime and indium composition of InGaN quantum well is believed owing to the polarization-induced quantum confinement Stark effect. Long carrier lifetime not only increases the probability of carrier leakage, but also results in high carrier concentration in quantum well. In other words, under the same current density, the carrier concentration in active region in near-UV LED is the lowest while that in green one is the highest. If considering the efficiency droop depending on carrier concentration, the behaviors of LEDs with different wavelengths do not show any abnormality. ...

  12. Dependence of aggregation behavior on concentration in triblock copolymer solutions: The effect of chain architecture

    Energy Technology Data Exchange (ETDEWEB)

    Han, Xiang-Gang, E-mail: xghan0@163.com; Zhang, Xue-Feng [Key Laboratory of Integrated Exploitation of Bayan Obo Multi-Metal Resources School of Mathematics, Physics and Biological Engineering, Inner Mongolia University of Science and Technology, Baotou 014010 (China)

    2015-12-07

    Using the self-consistent field lattice technique, the effects of concentration and hydrophobic middle block length (where the chain length remains constant) on aggregation behavior are studied in amphiphilic symmetric triblock copolymer solutions. The heat capacity peak for the unimer-micelle transition and the distribution peaks for the different degrees of aggregation for micelles and small aggregates (submicelles) are calculated. Analysis of the conducted computer simulations shows that the transition broadness dependence on concentration is determined by the hydrophobic middle block length, and this dependence is distinctly different when the length of the hydrophobic middle block changes. Different size for small aggregates simultaneously appear in the transition region. As temperature decreases, the number of different size small aggregates for the large hydrophobic middle block length first ascends and then descends in aggregation degree order. These results indicate that any transition broadness change with concentration is related to the mechanism of fragmentation and fusion. These results are helpful for interpreting the aggregation process of amphiphilic copolymers at equilibrium.

  13. Synthesis and concentration dependent antibacterial activities of CuO nanoflakes

    Energy Technology Data Exchange (ETDEWEB)

    Pandiyarajan, T.; Udayabhaskar, R. [Department of Physics, National Institute of Technology, Tiruchirappalli 620 015 (India); Vignesh, S.; James, R. Arthur [Department of Marine Science, Bharathidasan University, Tiruchirappalli 620 024 (India); Karthikeyan, B., E-mail: balkarin@yahoo.com [Department of Physics, National Institute of Technology, Tiruchirappalli 620 015 (India)

    2013-05-01

    We report, synthesis and antibacterial activities of CuO nanoflakes. CuO nanoparticles are prepared at room temperature through sol–gel method. X-ray diffraction studies show the particles are monoclinic (crystalline) in nature. Scanning electron microscopy (SEM) images clearly show that the prepared particles are flake like in structure. Fourier transform infrared (FTIR) spectra exhibits three different bands that correspond to the A{sub u} and B{sub u} modes. Antibacterial studies were performed on Shigella flexneri, Staphylococcus aureus, Staphylococcus epidermidis, Salmonella typhimurium, Bacillus subtilis, Escherichia coli, Vibrio cholera, Pseudomonas aeruginosa and Aeromonas liquefaciens bacterial strains. Among these bacterial strains, S. flexneri and B. subtilis are most sensitive to copper oxide nanoparticles than the positive control (Penicillin G) and S. typhimurium strain shows the less sensitive. Results show that sensitivity is highly dependent on the concentrations of CuO nanoflakes. - Highlights: ► CuO nanoflakes are prepared through simple sol–gel method at room temperature. ► Bacterial strains are highly affected by CuO nanoflakes than the positive control. ► Zone of inhibition increases with an increase of CuO concentrations. ► Sensitivity is highly dependent on the concentrations of CuO nanoflakes.

  14. Concentration-Dependent Diversifcation Effects of Free Cholesterol Loading on Macrophage Viability and Polarization

    Directory of Open Access Journals (Sweden)

    Xiaoyang Xu

    2015-08-01

    Full Text Available Background/Aims: The accumulation of free cholesterol in atherosclerotic lesions has been well documented in both animals and humans. In studying the relevance of free cholesterol buildup in atherosclerosis, contradictory results have been generated, indicating that free cholesterol produces both pro- and anti-atherosclerosis effects in macrophages. This inconsistency might stem from the examination of only select concentrations of free cholesterol. In the present study, we sought to investigate the implication of excess free cholesterol loading in the pathophysiology of atherosclerosis across a broad concentration range from (in µg/ml 0 to 60. Methods: Macrophage viability was determined by measuring formazan formation and flow cytometry viable cell counting. The polarization of M1 and M2 macrophages was differentiated by FACS (Fluorescence-Activated Cell Sorting assay. The secretion of IL-1β in macrophage culture medium was measured by ELISA kit. Macrophage apoptosis was detected by flow cytometry using a TUNEL kit. Results: Macrophage viability was increased at the treatment of lower concentrations of free cholesterol from (in µg/ml 0 to 20, but gradually decreased at higher concentrations from 20 to 60. Lower free cholesterol loading induced anti-inflammatory M2 macrophage polarization. The activation of the PPARγ (Peroxisome Proliferator-Activated Receptor gamma nuclear factor underscored the stimulation of this M2 phenotype. Nevertheless, higher levels of free cholesterol resulted in pro-inflammatory M1 activation. Moreover, with the application of higher free cholesterol concentrations, macrophage apoptosis and secretion of the inflammatory cytokine IL-1β increased significantly. Conclusion: These results for the first time demonstrate that free cholesterol could render concentration-dependent diversification effects on macrophage viability, polarization, apoptosis and inflammatory cytokine secretions, thereby reconciling the pros

  15. Dependence of microbial magnetite formation on humic substance and ferrihydrite concentrations

    Science.gov (United States)

    Piepenbrock, Annette; Dippon, Urs; Porsch, Katharina; Appel, Erwin; Kappler, Andreas

    2011-11-01

    the formation of either dissolved Fe(II), i.e. Fe 2+, in HEPES buffered medium or Fe(II) carbonate (siderite) in bicarbonate buffered medium. Besides the different identity of the Fe(II) compound formed at the end of Fe(III) reduction, there was no difference in the maximum rate and extent of microbial iron reduction and magnetite formation during FH reduction in the two buffer systems used. Our findings indicate that microbial magnetite formation during iron reduction depends on the geochemical conditions and can be of minor importance at low FH concentrations or be inhibited by adsorption of HS to the FH surface. Such scenarios could occur in soils with low iron mineral or high organic matter content.

  16. Photolysis of Caged-GABA Rapidly Terminates Seizures In Vivo: Concentration and Light Intensity Dependence.

    Science.gov (United States)

    Wang, Dan; Yu, Zhixin; Yan, Jiaqing; Xue, Fenqin; Ren, Guoping; Jiang, Chenxi; Wang, Weimin; Piao, Yueshan; Yang, Xiaofeng

    2017-01-01

    The therapy of focal epilepsy remains unsatisfactory for as many as 25% of patients. The photolysis of caged-γ-aminobutyric acid (caged-GABA) represents a novel and alternative option for the treatment of intractable epilepsy. Our previous experimental results have demonstrated that the use of blue light produced by light-emitting diode to uncage ruthenium-bipyridine-triphenylphosphine-c-GABA (RuBi-GABA) can rapidly terminate paroxysmal seizure activity both in vitro and in vivo. However, the optimal concentration of RuBi-GABA, and the intensity of illumination to abort seizures, remains unknown. The aim of this study was to explore the optimal anti-seizure effects of RuBi-GABA by using implantable fibers to introduce blue light into the neocortex of a 4-aminopyridine-induced acute seizure model in rats. We then investigated the effects of different combinations of RuBi-GABA concentrations and light intensity upon seizure. Our results show that the anti-seizure effect of RuBi-GABA has obvious concentration and light intensity dependence. This is the first example of using an implantable device for the photolysis of RuBi-GABA in the therapy of neocortical seizure, and an optimal combination of RuBi-GABA concentration and light intensity was explored. These results provide important experimental data for future clinical translational studies.

  17. Lethal body concentrations and accumulation patterns determine time-dependent toxicity of cadmium in soil arthropods

    Energy Technology Data Exchange (ETDEWEB)

    Crommentuijn, T.; Doodeman, C.J.A.M.; Doornekamp, A.; Pol, J.J.C. van der; Bedaux, J.J.M.; Gestel, C.A.M. van (Vrije Univ., Amsterdam (Netherlands))

    1994-11-01

    Time-dependent toxicity in bioassays is usually explained in terms of uptake and elimination kinetics of the toxicant. By comparing different species with essentially different accumulation kinetics, a firm test of this concept may be made. This article compares the sensitivity of six soil arthropods, the collembolans Orchesella cincta and Tomocerus minor, the oribatid mite Platynothrus peltifer, the isopods Porcellio scaber and Oniscus asellus, and the diplopod Cylindroiulus britannicus, when exposed to cadmium in the food. Survival was determined at various time intervals; accumulation of cadmium in the animals was measured at one time interval. Kinetic-based toxicity models were fitted to the data, and estimates were obtained for lethal body concentration, uptake rate constant, elimination rate constant, and ultimate LC50. Two different accumulation patterns could be discerned; these were correlated with time-survival relationships. One, species that have the possibility to eliminate cadmium will reach an equilibrium for the internal concentration and also an ultimate LC50. Two, species that are unable to eliminate cadmium but store it in the body will have an ultimate LC50 equal to zero. For these species the time in which the lethal body concentration is reached is more important. Taxonomically related species appeared to have comparable accumulation patterns, but lethal body concentrations differed. It is concluded that knowledge of the accumulation pattern is indispensable for the evaluation of species' sensitivities to toxicants.

  18. Is sensitization with nicotinamide and carbogen dependent on nicotinamide concentration at the time of irradiation?

    Science.gov (United States)

    Rojas, A; Stratford, M R L; Bentzen, S M; Denekamp, J

    2004-07-01

    To determine whether tumour radiosensitization and the therapeutic benefit of administering carbogen with nicotinamide depend upon irradiating at the time of peak drug concentration. Local tumour control of CaNT tumours in CBA mice and acute skin reactions in albino WHT mice were assessed after treatment with 10 X-ray fractions in air, carbogen alone or combined with 0.1, 0.2 or 0.5 mg g(-1) nicotinamide, injected 15, 30 or 60 min before irradiation. Plasma and tumour drug pharmacokinetics were performed. Nicotinamide was rapidly taken up into tumours; a six- and threefold higher concentration was obtained with 0.5 mg g(-1) compared with 0.1 and 0.2 mg g(-1), respectively. Tumour, but not skin, radiosensitization increased as the dose of nicotinamide increased (p = 0.03), but at each dose level there was no significant difference in radiosensitivity when irradiations were done at or after the time of peak concentration. An almost eightfold increase in plasma levels increased tumour enhancement ratios from 1.74 to 1.92 (p skin radiosensitivity was independent of time of nicotinamide administration. Higher drug concentrations were not mirrored by proportionally higher enhancement ratios. Lower plasma levels than previously suggested significantly enhanced tumour radiosensitivity relative to carbogen alone. The clinical implications of these findings are discussed.

  19. Concentration-dependent apparent partition coefficients of ionic liquids possessing ethyl- and bi-sulphate anions.

    Science.gov (United States)

    Jain, Preeti; Kumar, Anil

    2016-01-14

    This study deals with the concentration dependent apparent partition coefficients log P of the ethyl and bisulfate-based ionic liquids. It is observed that the bisulfate-based ionic liquids show different behaviour with respect to concentration as compared to ethyl sulphate-based ionic liquids. It is significant and useful analysis for the further implementation of alkyl sulfate based ionic liquids as solvents in extraction processes. The log P values of the ethyl sulphate-based ionic liquids were noted to vary linearly with the concentration of the ionic liquid, whereas a flip-flop trend with the concentration for the log P values of the bisulphate-based ionic liquids was observed due to the difference in hydrogen bond accepting basicity and possibility of aggregate formation of these anions. The π-π interactions between the imidazolium and pyridinium rings were seen to affect the log P values. The alkyl chain length of anions was also observed to influence the log P values. The hydrophobicity of ionic liquid changes with the alkyl chain in the anion in the order; [HSO4](-) < [EtSO4](-) < [BuSO4](-).

  20. Concentration-dependence of the explosion characteristics of chlorine dioxide gas.

    Science.gov (United States)

    Jin, Ri-ya; Hu, Shuang-qi; Zhang, Yin-ghao; Bo, Tao

    2009-07-30

    The explosion characteristics of chlorine dioxide gas have been studied for the first time in a cylindrical exploder with a shell capacity of 20 L. The experimental results have indicated that the lower concentration limit for the explosive decomposition of chlorine dioxide gas is 9.5% ([ClO(2)]/[air]), whereas there is no corresponding upper concentration limit. Under the experimental conditions, and within the explosion limits, the pressure of explosion increases with increasing concentration of chlorine dioxide gas; the maximum pressure of explosion relative to the initial pressure was measured as 0.024 MPa at 10% ClO(2) and 0.641 MPa at 90% ClO(2). The induction time (the time from the moment of sparking to explosion) has also been found to depend on the concentration of chlorine dioxide gas; thus, at 10% ClO(2) the induction time was 2195 ms, but at 90% ClO(2) the induction time was just 8 ms. The explosion reaction mechanism of ClO(2) is of a degenerate chain-branching type involving the formation of a stable intermediate (Cl(2)O(3)), from which the chain-branching occurs. Chain initiation takes place at the point of ignition and termination takes place at the inner walls of the exploder.

  1. Rheology of a primary and secondary sewage sludge mixture: dependency on temperature and solid concentration.

    Science.gov (United States)

    Baroutian, Saeid; Eshtiaghi, Nicky; Gapes, Daniel J

    2013-07-01

    The main objective of this study was to investigate the rheology of mixed primary and secondary sludge and its dependency on solid content and temperature. Results of this study showed that the temperature and solid concentration are critical parameters affecting the mixed sludge rheology. It was found that the yield stress increases with an increase in the sludge solid content and decreases with increasing temperature. The rheological behaviour of sludges was modelled using the Herschel-Bulkley model. The results of the model showed a good agreement with experimental data. Depending on the total solid content, the average error varied between 3.25% and 6.22%. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Determination of Concentration Dependent Diffusion Coefficients of Carbon in Expanded Austenite

    DEFF Research Database (Denmark)

    Hummelshøj, Thomas Strabo; Christiansen, Thomas; Somers, Marcel A. J.

    2008-01-01

    Abstract. In the present paper various experimental procedures to experimentally determine the concentration dependent diffusion coefficient of carbon in expanded austenite are evaluated. To this end thermogravimetric carburization was simulated for various experimental conditions and the evaluated...... composition dependent diffusivity of carbon derived from the simulated experiments was compared with the input data. The most promising procedure for an accurate determination is shown to be stepwise gaseous carburizing of thin foils in a gaseous atmosphere; the finer the stepsize, the more accurate...... the approximation of the diffusivity. Thermogravimetry was applied to continuously monitor the weight change of thin foils of AISI 316 during carburizing in CO-H2 gas mixtures for one of the simulated experimental procedures....

  3. Copper nanoparticles exert size and concentration dependent toxicity on somatosensory neurons of rat

    Science.gov (United States)

    PRABHU, BADANAVALU M.; ALI, SYED F.; MURDOCK, RICHARD C.; HUSSAIN, SABER M.; SRIVATSAN, MALATHI

    2010-01-01

    Metal nanoparticles, due to their unique properties and important applications in optical, magnetic, thermal, electrical, sensor devices and cosmetics, are beginning to be widely manufactured and used. This new and rapidly growing field of technology warrants a thorough examination of the material’s bio-compatibility and safety. Ultra-small particles may adversely affect living cells and organisms since they can easily penetrate the body through skin contact, inhalation and ingestion. Retrograde transport of copper nanoparticles from nerve endings on the skin can reach the somatosensory neurons in dorsal root ganglion (DRG). Since copper nanoparticles have industrial and healthcare applications, we determined the concentration and size-dependant effects of their exposure on survival of DRG neurons of rat in cell culture. The neurons were exposed to copper nanoparticles of increasing concentrations (10–100 μM) and sizes (40, 60 and 80 nm) for 24 h. Light microscopy, histochemical staining for copper, lactate dehydrogenase (LDH) assay for cell death, and MTS [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay for cell viability were performed to measure the resultant toxicity and cell survival. DRG neurons exposed to copper nanoparticles displayed vacuoles and detachment of some neurons from the substratum. Neurons also exhibited disrupted neurite network. LDH and MTS assays revealed that exposure to copper nanoparticles had significant toxic effect with all the sizes tested when compared to unexposed control cultures. Further analysis of the results showed that copper nanoparticles of smaller size and higher concentration exerted the maximum toxic effects. Rubeanic acid staining showed intracellular deposition of copper. These results demonstrate that copper nanoparticles are toxic in a size- and concentration-dependent manner to DRG neurons. PMID:20543894

  4. Dependence of nitrogen concentration in type Ib diamonds on synthesis temperature

    Institute of Scientific and Technical Information of China (English)

    TIAN Yu; JIA XiaoPeng; ZANG ChuanYi; LI ShangSheng; XIAO HongYu; ZHANG YaFei; HUANG GuoFeng; LI Rui; HAN QiGang; MA LiQiu; LI Yong; CHEN XiaoZhou; ZHANG Chong; MA HongAn

    2009-01-01

    Type Ib diamonds were grown by the temperature gradient method (TGM) at 5.5 GPa and 1500-1560 K in a china-type cubic anvil high pressure apparatus using Ni70Mn25Co5 alloy as solvent/catalyst. The concentration of nitrogen (CN) in type Ib diamonds synthesized at different synthesis temperatures was measured by a Fourier transform infrared (FTIR) spectrometer. The dependence of CN in diamond on synthesis temperature was studied. For the type Ib diamonds synthesized using Ni70Mn25Co5 as catalyst, its CN decreases along with the increase of synthesis temperature.

  5. Temperature-Dependent Electrical Properties and Carrier Transport Mechanisms of TMAH-Treated Ni/Au/Al2O3/GaN MIS Diode

    Science.gov (United States)

    Reddy, M. Siva Pratap; Puneetha, Peddathimula; Reddy, V. Rajagopal; Lee, Jung-Hee; Jeong, Seong-Hoon; Park, Chinho

    2016-11-01

    The temperature-dependent electrical properties and carrier transport mechanisms of tetramethylammonium hydroxide (TMAH)-treated Ni/Au/Al2O3/GaN metal-insulator-semiconductor (MIS) diodes have been investigated by current-voltage ( I- V) and capacitance-voltage ( C- V) measurements. The experimental results reveal that the barrier height ( I- V) increases whereas the ideality factor decreases with increasing temperature. The TMAH-treated Ni/Au/Al2O3/GaN MIS diode showed nonideal behaviors which indicate the presence of a nonuniform distribution of interface states ( N SS) and effect of series resistance ( R S). The obtained R S and N SS were found to decrease with increasing temperature. Furthermore, it was found that different transport mechanisms dominated in the TMAH-treated Ni/Au/Al2O3/GaN MIS diode. At 150 K to 250 K, Poole-Frenkel emission (PFE) was found to be responsible for the reverse leakage, while Schottky emission (SE) was the dominant mechanism at high electric fields in the temperature range from 300 K to 400 K. Feasible energy band diagrams and possible carrier transport mechanisms for the TMAH-treated Ni/Au/Al2O3/GaN MIS diode are discussed based on PFE and SE.

  6. Light-Induced ESR Studies of Quadrimolecular Recombination Kinetics of Photogenerated Charge Carriers in Regioregular Poly(3-alkylthiophene)/C60 Composites: Alkyl Chain Dependence

    Science.gov (United States)

    Tanaka, Hisaaki; Hasegawa, Naoki; Sakamoto, Tomotaka; Marumoto, Kazuhiro; Kuroda, Shin-ichi

    2007-08-01

    Light-induced ESR (LESR) measurements have been performed on the composites of regioregular poly(3-alkylthiophene) (RR-P3AT) and C60 by using polymers having different alkyl chains (CmH2m+1 with m=6, 8, 10, 12). The quadrimolecular recombination (QR) kinetics of photogenerated charge carriers, previously reported, have been confirmed for all the composites from the excitation power (Iex) dependence of the LESR intensity showing an ˜Iex0.25 dependence. The time decay of LESR intensity is also consistent with the QR model. Considering that only bimolecular recombination is observed in regiorandom polymer composites, the occurrence of QR strongly suggests the formation of doubly charged states, either bipolarons or polaron pairs on the regioregular polymer chains. On the other hand, the QR rate constant γ has been found to exhibit weak alkyl chain dependence, contrary to the case of the field-effect mobility of pure regioregular polymers with systematic alkyl chain dependence. This implies the significant contribution of the polymer and fullerene interface in determining γ.

  7. Optical monitoring of the concentration profile of submicron latex particles in flow through a translucent water-permeable tube: demonstration of flow-dependent concentration polarization of plasma proteins at a blood/endothelium boundary

    Science.gov (United States)

    Wada, Shigeo; Iwai, Toshiaki; Karino, Takeshi

    1999-05-01

    It is well accepted that hemodynamics plays an important role in atherogenesis in man. However, the precise mechanisms have not been elucidated yet. Recently, Karino and his coworkers hypothesized that flow-dependent concentration polarization of low-density lipoproteins (LDL: a carrier of cholesterol) may occur at a blood/endothelium boundary, leading to a high risk of atherogenesis in regions of slow flow and low wall shear rate where the concentration of LDL builds up. In this study, we attempted to confirm experimentally their predictions by measuring optically the concentration profile of polystyrene microspheres (used as a model of LDL) flowing in steady flow through a dialyses tube (used as a model of an artery) by transversing a laser beam across the tube and detecting the intensity of the transmitted light. It was found that surface concentration of the microsphere certainly increases with decreasing the flow rate (hence wall shear rate) and it occurs even under the conditions of a very low water filtration velocity encountered in normal arteries in vivo, thus giving a strong support to the hypothesis proposed by Karino et al.

  8. Carrier-density dependence of photoluminescence from localized states in InGaN/GaN quantum wells in nanocolumns and a thin film

    Energy Technology Data Exchange (ETDEWEB)

    Shimosako, N., E-mail: n-shimosako@sophia.jp; Inose, Y.; Satoh, H.; Kinjo, K.; Nakaoka, T.; Oto, T. [Department of Engineering and Applied Sciences, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554 (Japan); Kishino, K.; Ema, K. [Department of Engineering and Applied Sciences, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554 (Japan); Sophia Nanotechnology Research Center, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554 (Japan)

    2015-11-07

    We have measured and analyzed the carrier-density dependence of photoluminescence (PL) spectra and the PL efficiency of InGaN/GaN multiple quantum wells in nanocolumns and in a thin film over a wide excitation range. The localized states parameters, such as the tailing parameter, density and size of the localized states, and the mobility edge density are estimated. The spectral change and reduction of PL efficiency are explained by filling of the localized states and population into the extended states around the mobility edge density. We have also found that the nanocolumns have a narrower distribution of the localized states and a higher PL efficiency than those of the film sample although the In composition of the nanocolumns is higher than that of the film.

  9. Concentration influence on temperature-dependent luminescence properties of samarium substituted strontium tetraborate

    Energy Technology Data Exchange (ETDEWEB)

    Sakirzanovas, Simas, E-mail: simas.sakirzanovas@chf.vu.lt [Department of General and Inorganic Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius (Lithuania); Department of Chemical Engineering, University of Applied Sciences Muenster, Stegerwaldstr. 39, 48565 Steinfurt (Germany); Katelnikovas, Artu-bar ras, E-mail: arturas.katelnikovas@fh-muenster.de [Department of General and Inorganic Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius (Lithuania); Department of Chemical Engineering, University of Applied Sciences Muenster, Stegerwaldstr. 39, 48565 Steinfurt (Germany); Dutczak, Danuta, E-mail: dutczak@fh-muenster.de [Department of Chemical Engineering, University of Applied Sciences Muenster, Stegerwaldstr. 39, 48565 Steinfurt (Germany); Kareiva, Aivaras, E-mail: aivaras.kareiva@chf.vu.lt [Department of General and Inorganic Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius (Lithuania); Juestel, Thomas, E-mail: tj@fh-muenster.de [Department of Chemical Engineering, University of Applied Sciences Muenster, Stegerwaldstr. 39, 48565 Steinfurt (Germany)

    2012-01-15

    The series of divalent samarium substituted strontium tetraborate (Sr{sub 1-x}Sm{sub x}B{sub 4}O{sub 7}) polycrystalline samples were prepared by the conventional solid-state reaction. The phase formation of the samples was investigated by X-ray powder diffraction measurements. The luminescence spectra and decay curves of the Sm{sup 2+} ions were measured. Temperature dependent Sm{sup 2+} luminescence properties were investigated. The f-d and {sup 5}D{sub 1}-{sup 7}F{sub J} transitions appeared at 350 K and increased with increase in the temperature while the intensity of {sup 5}D{sub 0}-{sup 7}F{sub J} transitions decreased. The emission spectra pointed out that Sm{sup 2+} occupies of C{sub 2v} or lower symmetry site. The photoluminescence decay times of strontium tetraborate doped with different concentrations of Sm{sup 2+} was investigated as a function of temperature in the range of 100-500 K. However, no obvious concentration quenching was observed. - Highlights: > Strontium tetraborate stabilizes divalent samarium. > Temperature dependent Sm{sup 2+} luminescence. > Sm{sup 2+} degeneracy is removed in low symmetry site. > Well resolved emission of Sm{sup 2+} under UV excitation.

  10. Dependence of the dielectric constant of electrolyte solutions on ionic concentration

    CERN Document Server

    Gavish, Nir

    2012-01-01

    We study the dependence of the static dielectric constant of aqueous electrolyte solutions upon the concentration of salt in the solution and temperature. The model takes into account the orientation of the solvent dipoles due to the electric field created by ions, the ionic response to an applied field, and the effect of thermal fluctuations. The analysis suggests that the formation of ion pairs by a small fraction of disassociated ions can have a significant effect on the static dielectric constant. The model predicts the dielectric has the functional dependence $\\varepsilon(c)=\\varepsilon_w-\\beta L(3\\alpha c/\\beta)$ where $L$ is the Langevin function, $c$ is the salt concentration, $\\varepsilon_w$ is the dielectric of the pure water, $\\alpha$ is the total excess polarization of the ions and $\\beta$ is the relative difference between the water dipole moment and the effective dipole moment of ion pairs as weighted by the density of ion pairs and their structural rigidity. The functional form gives an extreme...

  11. Temperature response of soil respiration is dependent on concentration of readily decomposable C

    Directory of Open Access Journals (Sweden)

    A. A. Larionova

    2007-12-01

    Full Text Available Temperature acclimation of soil organic matter (SOM decomposition is one of the major uncertainties in predicting soil CO2 efflux associated with the increase in global mean temperature. A reasonable explanation for an apparent acclimation proposed by Davidson and colleagues (2006 based on Michaelis-Menten kinetics suggests that temperature sensitivity decreases when both maximal activity of respiratory enzymes (Vmax and half-saturation constant (Ks cancel each other upon temperature increase. We tested the hypothesis of the canceling effect by the mathematical simulation of data obtained in incubation experiments with forest and arable soils. Our data support the hypothesis and suggest that concentration of readily decomposable C substrate (as glucose equivalents and temperature dependent substrate release are the important factors controlling temperature sensitivity of soil respiration. The highest temperature sensitivity of soil respiration was observed when substrate release was temperature dependent and C substrate concentration was much lower than Ks. Increase of substrate content to the half-saturation constant by glucose addition resulted in temperature acclimation associated with the canceling effect. Addition of the substrate to the level providing respiration at a maximal rate Vmax leads to the acclimation of the whole microbial community as such. However, growing microbial biomass was more sensitive to the temperature alterations. This study improves our understanding of the instability of temperature sensitivity of soil respiration under field conditions, attributing this phenomenon to changes in concentration of readily decomposable C substrate.

  12. Reinforcing effect for corn oil stimulus was concentration dependent in an operant task in mice.

    Science.gov (United States)

    Yoneda, Takeshi; Taka, Yuichi; Okamura, Maya; Mizushige, Takafumi; Matsumura, Shigenobu; Manabe, Yasuko; Tsuzuki, Satoshi; Inoue, Kazuo; Fushiki, Tohru

    2007-11-30

    Corn oil is reported to elicit a conditioned place preference (CPP) in a CPP test in mice. To further investigate a reinforcing effect of corn oil, we studied whether the corn oil acts as a reinforcer under a progressive ratio (PR) schedule in the operant task. BALB/c mice were trained to lever press for sucrose and corn oil. After reaching a stable break-point for 100% corn oil, the PR test was conducted for various concentrations of corn oil (0%-100%). The reinforcing effect of corn oil was increased in a concentration-dependent manner under the PR schedule. A mineral oil and 0.3% xanthan gum as vehicles did not show any reinforcing effect in the PR test, suggesting that oily and viscous texture was not related to the reinforcing property of corn oil. The break-point for corn oil was attenuated by pretreatment with (-)-sulpiride, a D(2) antagonist, in the PR test. On the other hand, SCH23390, a D(1) antagonist, did not influence the break-point. Furthermore, the pretreatment with (-)-sulpiride or SCH23390 did not influence the intake of corn oil in a one-bottle test for 30 min, suggesting that the dopaminergic system is involved in the reinforcing effect but not the consumption of corn oil in mice. In conclusion, operant response to corn oil is concentration-dependently enhanced under the PR schedule. This reinforcing effect of corn oil is at least partly mediated through the dopaminergic systems via D(2) receptors.

  13. Concentration-dependent toxicity of iron oxide nanoparticles mediated by increased oxidative stress

    Directory of Open Access Journals (Sweden)

    Saba Naqvi

    2010-11-01

    Full Text Available Saba Naqvi1, Mohammad Samim2, MZ Abdin3, Farhan Jalees Ahmed4, AN Maitra5, CK Prashant6, Amit K Dinda61Faculty of Engineering and Interdisciplinary Sciences, 2Department of Chemistry, 3Department of Biotechnology, Faculty of Science, 4Department of Pharmaceutics, Faculty of Pharmacy, Jamia Hamdard, Hamdard University, 5Department of Chemistry, University of Delhi, 6Department of Pathology, All India Institute of Medical Sciences, New Delhi, IndiaAbstract: Iron oxide nanoparticles with unique magnetic properties have a high potential for use in several biomedical, bioengineering and in vivo applications, including tissue repair, magnetic resonance imaging, immunoassay, drug delivery, detoxification of biologic fluids, cell sorting, and hyperthermia. Although various surface modifications are being done for making these nonbiodegradable nanoparticles more biocompatible, their toxic potential is still a major concern. The current in vitro study of the interaction of superparamagnetic iron oxide nanoparticles of mean diameter 30 nm coated with Tween 80 and murine macrophage (J774 cells was undertaken to evaluate the dose- and time-dependent toxic potential, as well as investigate the role of oxidative stress in the toxicity. A 15–30 nm size range of spherical nanoparticles were characterized by transmission electron microscopy and zeta sizer. MTT assay showed >95% viability of cells in lower concentrations (25–200 µg/mL and up to three hours of exposure, whereas at higher concentrations (300–500 µg/mL and prolonged (six hours exposure viability reduced to 55%–65%. Necrosis-apoptosis assay by propidium iodide and Hoechst-33342 staining revealed loss of the majority of the cells by apoptosis. H2DCFDDA assay to quantify generation of intracellular reactive oxygen species (ROS indicated that exposure to a higher concentration of nanoparticles resulted in enhanced ROS generation, leading to cell injury and death. The cell membrane injury

  14. Autoinducer 2: a concentration-dependent signal for mutualistic bacterial biofilm growth

    Science.gov (United States)

    Rickard, A.H.; Palmer, R.J.; Blehert, D.S.; Campagna, S.R.; Semmelhack, M.F.; Egland, P.G.; Bassler, B.L.; Kolenbrander, P.E.

    2006-01-01

    4,5-dihydroxy-2,3-pentanedione (DPD), a product of the LuxS enzyme in the catabolism of S-ribosylhomocysteine, spontaneously cyclizes to form autoinducer 2 (AI-2). AI-2 is proposed to be a universal signal molecule mediating interspecies communication among bacteria. We show that mutualistic and abundant biofilm growth in flowing saliva of two human oral commensal bacteria, Actinomyces naeslundii T14V and Streptococcus oralis 34, is dependent upon production of AI-2 by S. oralis 34. A luxS mutant of S. oralis 34 was constructed which did not produce AI-2. Unlike wild-type dual-species biofilms, A. naeslundii T14V and an S. oralis 34 luxS mutant did not exhibit mutualism and generated only sparse biofilms which contained a 10-fold lower biomass of each species. Restoration of AI-2 levels by genetic or chemical (synthetic AI-2 in the form of DPD) complementation re-established the mutualistic growth and high biomass characteristic for the wild-type dual-species biofilm. Furthermore, an optimal concentration of DPD was determined, above and below which biofilm formation was suppressed. The optimal concentration was 100-fold lower than the detection limit of the currently accepted AI-2 assay. Thus, AI-2 acts as an interspecies signal and its concentration is critical for mutualism between two species of oral bacteria grown under conditions that are representative of the human oral cavity. ?? 2006 Blackwell Publishing Ltd.

  15. Concentration Dependent Ion-Protein Interaction Patterns Underlying Protein Oligomerization Behaviours

    Science.gov (United States)

    Batoulis, Helena; Schmidt, Thomas H.; Weber, Pascal; Schloetel, Jan-Gero; Kandt, Christian; Lang, Thorsten

    2016-04-01

    Salts and proteins comprise two of the basic molecular components of biological materials. Kosmotropic/chaotropic co-solvation and matching ion water affinities explain basic ionic effects on protein aggregation observed in simple solutions. However, it is unclear how these theories apply to proteins in complex biological environments and what the underlying ionic binding patterns are. Using the positive ion Ca2+ and the negatively charged membrane protein SNAP25, we studied ion effects on protein oligomerization in solution, in native membranes and in molecular dynamics (MD) simulations. We find that concentration-dependent ion-induced protein oligomerization is a fundamental chemico-physical principle applying not only to soluble but also to membrane-anchored proteins in their native environment. Oligomerization is driven by the interaction of Ca2+ ions with the carboxylate groups of aspartate and glutamate. From low up to middle concentrations, salt bridges between Ca2+ ions and two or more protein residues lead to increasingly larger oligomers, while at high concentrations oligomers disperse due to overcharging effects. The insights provide a conceptual framework at the interface of physics, chemistry and biology to explain binding of ions to charged protein surfaces on an atomistic scale, as occurring during protein solubilisation, aggregation and oligomerization both in simple solutions and membrane systems.

  16. A NOVEL INTERPRETATION OF CONCENTRATION DEPENDENCE OF VISCOSITY OF DILUTE POLYMER SOLUTION

    Institute of Scientific and Technical Information of China (English)

    Yan Pan; Rong-shi Cheng

    2000-01-01

    The concentration dependence of the reduced viscosity of dilute polymer solution is interpreted in the light of a new concept of the self-association of polymer chains in dilute solution. The apparent self-association constant is defined as the molar association constant divided by the molar mass of individual polymer chain and is numerically interconvertible with the Huggins coefficient. The molar association constant is directly proportional to the effective hydrodynamic volume of the polymer chain in solution and is irrespective of the chain architecture. The effective hydrodynamic volume accounts for the non-spherical conformation of a short polymer chain in solution and is a product of a shape factor and hydrodynamic volume. The observed enhancement of Huggins coefficient for short chain and branched polymer is satisfactorily interpreted by the concept of self-association. The concept of self-association allows us to predict the existence of a boundary concentration Cs (dynamic contact concentration) which divides the dilute polymer solution into two regions.

  17. Marangoni instabilities in two-layer systems due to concentration dependent transfer properties

    Science.gov (United States)

    Trevelyan, P. M. J.; Pimienta, V.; Eckert, K.; de Wit, A.

    2008-11-01

    We consider a Hele-Shaw cell containing two immiscible liquids. A chemical species initially dissolved in an organic phase crosses the interface into the aqueous phase. In the aqueous phase this chemical reactant is involved in a reaction producing a surfactant which undergoes micellisation when the critical micelle concentration is reached. These micelles increase solubility which in turn increases the transfer rate and hence favours additional formation of micelles. To model such an autocatalytic increase of solubility, we consider here that the partition coefficient is a function of the surfactant concentration. Through the solutal Marangoni effect, this surfactant can induce tangential stresses leading to interfacial motion. The aim of our study is to theoretically examine the conditions for an instability in such a system. In particular, we seek to understand whether Marangoni effects can be observed because of a concentration dependent partition coefficient in a system that would be stable in the case of a constant partition coefficient according to the classical stability conditions of Sternling and Scriven (AIChE J., 5, p.514, 1959).

  18. A theory on bubble-size dependence of the critical electrolyte concentration for inhibition of coalescence.

    Science.gov (United States)

    Chan, Benjamin S; Tsang, Ying Hang

    2005-06-01

    The interaction of pairs of bubbles with equal diameters grown on adjacent capillaries in aqueous magnesium sulfate solutions is studied by varying electrolyte concentration and bubble diameter by Tsang, Koh and Koch [Y.H. Tsang, Y.-H. Koh, D.L. Koch, J. Colloid Interface Sci. 275 (2004) 290] (referred to as TKK hereafter). They find that the critical concentration to prevent coalescence, Ct, increases as the equivalent diameter, deq, decreases. In fact, Ct is found to scale as deq(-1.2). This dependence is stronger than that predicted by Prince and Blanch (Ct approximately deq(-0.5)) (referred to as PB [M.J. Prince, H.W. Blanch, AIChE J. 36 (1990) 1425] hereafter) on the basis of a postulation that lubrication pressure due to Marangoni stresses inhibit coalescence. TKK postulate instead that bubbles are stabilized by hydration structures. We further illustrate here that when hydration force term is added to the equation of motion of the film thinning process, predicted values of critical concentration are found to scale as deq(-1). The current prediction shows a much better agreement with the experimental results than that proposed by PB. This suggests previous assumption that immobility of the interface by Marangoni effect as the dominant mechanism of inhibition of coalescence in an electrolytic solution is inaccurate [M.J. Prince, H.W. Blanch, AIChE J. 36 (1990) 1425, G. Marrucci, Chem. Eng. Sci. 24 (1969) 975].

  19. High blood ketone body concentration in type 2 non-insulin dependent diabetic patients.

    Science.gov (United States)

    Avogaro, A; Crepaldi, C; Miola, M; Maran, A; Pengo, V; Tiengo, A; Del Prato, S

    1996-02-01

    To assess the metabolic disturbances, and, in particular, the occurrence of high blood ketone body concentration in post-absorptive Type 2 (non-insulin-dependent) diabetic patients as compared to a matched normal population, a study was carried out in a group of 78 Type 2 diabetic outpatients matched for age and sex and in 78 normal individuals. In all subjects we measured HbA1c, and fasting levels of glucose, FFA, lactate, pyruvate, glycerol, alanine, 3-hydroxybutyrate, acetoacetate, uric acid, total cholesterol, triglycerides, creatinine, growth hormone, cortisol, glucagon, free insulin, and C-peptide. Multistix strips were used for urine ketone determination. As expected HbA1c, and plasma glucose were higher in Type 2 diabetics. This was associated with multiple metabolic disturbances as shown by higher circulating concentrations of FFA, glycerol and gluconeogenic precursors. Similarly, blood levels of ketones (351 +/- 29 vs 159 +/- 15 umol/l; P growth hormone. Plasma glucagon levels were higher in Type 2 diabetics. Blood ketone body levels were directly correlated with both plasma glucose and FFA concentrations. These observations clearly show that Type 2 diabetes is a pathologic condition characterised by multiple metabolic disturbances which are fully apparent in the basal state. Furthermore, we emphasise that Type 2 diabetic patients, though not insulin deficient, may present a significant increase in their fasting levels of ketone bodies.

  20. Dependence of carrier doping on the impurity potential in transition-metal-substituted FeAs-based superconductors.

    Science.gov (United States)

    Ideta, S; Yoshida, T; Nishi, I; Fujimori, A; Kotani, Y; Ono, K; Nakashima, Y; Yamaichi, S; Sasagawa, T; Nakajima, M; Kihou, K; Tomioka, Y; Lee, C H; Iyo, A; Eisaki, H; Ito, T; Uchida, S; Arita, R

    2013-03-01

    In order to examine to what extent the rigid-band-like electron doping scenario is applicable to the transition metal-substituted Fe-based superconductors, we have performed angle-resolved photoemission spectroscopy studies of Ba(Fe(1-x)Ni(x))(2)As(2) (Ni-122) and Ba(Fe(1-x)Cu(x))(2)As(2) (Cu-122), and compared the results with Ba(Fe(1-x)Co(x))(2)As(2) (Co-122). We find that Ni 3d-derived features are formed below the Fe 3d band and that Cu 3d-derived ones further below it. The electron and hole Fermi surface (FS) volumes are found to increase and decrease with substitution, respectively, qualitatively consistent with the rigid-band model. However, the total extra electron number estimated from the FS volumes (the total electron FS volume minus the total hole FS volume) is found to decrease in going from Co-, Ni-, to Cu-122 for a fixed nominal extra electron number, that is, the number of electrons that participate in the formation of FS decreases with increasing impurity potential. We find that the Néel temperature T(N) and the critical temperature T(c) maximum are determined by the FS volumes rather than the nominal extra electron concentration or the substituted atom concentration.

  1. Both RIG-I and MDA5 detect alphavirus replication in concentration-dependent mode

    Energy Technology Data Exchange (ETDEWEB)

    Akhrymuk, Ivan; Frolov, Ilya; Frolova, Elena I., E-mail: evfrolova@UAB.edu

    2016-01-15

    Alphaviruses are a family of positive-strand RNA viruses that circulate on all continents between mosquito vectors and vertebrate hosts. Despite a significant public health threat, their biology is not sufficiently investigated, and the mechanisms of alphavirus replication and virus–host interaction are insufficiently understood. In this study, we have applied a variety of experimental systems to further understand the mechanism by which infected cells detect replicating alphaviruses. Our new data strongly suggest that activation of the antiviral response by alphavirus-infected cells is determined by the integrity of viral genes encoding proteins with nuclear functions, and by the presence of two cellular pattern recognition receptors (PRRs), RIG-I and MDA5. No type I IFN response is induced in their absence. The presence of either of these PRRs is sufficient for detecting virus replication. However, type I IFN activation in response to pathogenic alphaviruses depends on the basal levels of RIG-I or MDA5. - Highlights: • Both RIG-I and MDA5 detect alphavirus replication. • Alphavirus-induced transcriptional shutoff affects type I IFN induction. • Sensing of alphavirus replication by RIG-I and MDA5 depends on their concentrations. • High basal level of RIG-I and MDA5 allows IFN induction by pathogenic alphaviruses. • This dependence determines the discrepancy between the in vivo and in vitro data.

  2. Interfacial Layer Growth Condition Dependent Carrier Transport Mechanisms in HfO2/SiO2 Gate Stacks

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, S. K.; Misra, D.

    2012-06-04

    The temperature and field dependent leakage current in HfO{sub 2}/SiO{sub 2} gate stack for in situ steam grown and chemical interfacial layers (ILs) are studied in the temperature range of 20 C to 105 C. Poole-Frenkel mechanism in high field whereas Ohmic conduction in low field region are dominant for both devices. Leakage current decreases whereas both trap energy level ({phi}{sub t}) and activation energy (E{sub a}) increase for chemically grown IL devices. The trap level energy, ({phi}{sub t}) -0.2 eV, indicates that doubly charged oxygen vacancies (V{sup 2-}) are the active electron traps which contribute to the leakage current in these gate stacks.

  3. Mechanism Underlying Time-dependent Cross-phenomenon between Concentration-response Curves and Concentration Addition Curves: A Case Study of Sulfonamides-Erythromycin mixtures on Escherichia coli

    Science.gov (United States)

    Sun, Haoyu; Ge, Hongming; Zheng, Min; Lin, Zhifen; Liu, Ying

    2016-09-01

    Previous studies have identified a phenomenon in which the concentration-response curves (CRCs) for mixtures cross the curves for concentration addition model when predicting or judging joint toxic actions. However, mechanistic investigations of this phenomenon are extremely limited. In this study, a similar phenomenon was observed when we determined the joint toxic actions of sulfonamides (SAs) and erythromycin (ERY) on Escherichia coli (E. coli), which we named the “cross-phenomenon”, and it was characterized by antagonism in the low-concentration range, addition in the medium-concentration range, and synergism in the high-concentration range. The mechanistic investigation of the cross-phenomenon was as follows: SAs and ERY could form a double block to inhibit the bacterial growth by exhibiting a synergistic effect; however, the hormetic effect of SAs on E. coli led to antagonism in the low-concentration range, resulting from the stimulation of sdiA mRNA expression by SAs, which increased the expression of the efflux pump (AcrAB-TolC) to discharge ERY. Furthermore, this cross-phenomenon was observed to be a time-dependent process induced by the increase of both the concentration and extent of stimulation of sdiA mRNA with exposure time. This work explains the dose-dependent and time-dependent cross-phenomenon and provides evidence regarding the interaction between hormesis and cross-phenomenon.

  4. Carbon quantum dot-based field-effect transistors and their ligand length-dependent carrier mobility.

    Science.gov (United States)

    Kwon, Woosung; Do, Sungan; Won, Dong Chan; Rhee, Shi-Woo

    2013-02-01

    We report electrical measurements of films of carbon quantum dots (CQDs) that serve as the channels of field-effects transistors (FETs). To investigate the dependence of the field-effect mobility on ligand length, colloidal CQDs are synthesized and ligand-exchanged with several primary amines of different ligand lengths. We measure current as a function of gate voltage and find that the devices show ambipolar conductivity, with electron and hole mobilities as high as 8.49 × 10(-5) and 3.88 × 10(-5) cm(2) V(-1) s(-1), respectively. The electron mobilities are consistently 2-4 times larger than the hole mobilities. Furthermore, the mobilities decrease exponentially with the increase of the ligand length, which is well-described by the Miller-Abrahams model for nearest-neighbor hopping. Our results provide a theoretical basis to examine charge transport in CQD films and offer new prospects for the fabrication of high-mobility CQD-based optoelectronic devices, including solar cells, light-emitting devices, and optical sensors.

  5. Scale dependence of mechanics and dynamics of active gels with increasing motor concentration

    CERN Document Server

    Sonn-Segev, Adar; Roichman, Yael

    2016-01-01

    The cytoskeleton protein actin assembles into large bundles when supporting stresses in the cell, but grows into a fine branched network to induce cell motion. Such self-organization processes are studied in artificial networks of cytoskeleton proteins with thick actin bundles and large motor protein aggregates to enable optical observation. The effect of motor aggregate size on the cytoskeleton mechanical properties is studied here in networks comprised of much smaller motor assemblies. Large motor protein clusters are known to increase the stiffness of actin based networks by introducing tension and additional cross-linking cites. We find that these effects are universal to actin gels regardless of actin bundle thickness and motor aggregate size and are relevant, therefore, to a wide range of cytoskeleton based cellular processes. In contrast, motor induced active fluctuations depend significantly on motor assembly size, featuring unique non-Gaussian statistics at high concentrations of small assemblies.

  6. Concentration dependences of the physicochemical properties of a water-acetone system

    Science.gov (United States)

    Fedyaeva, O. A.; Poshelyuzhnaya, E. G.

    2017-01-01

    Concentration dependences of the UV spectrum, refractive index, specific electrical conductivity, boiling point, pH, surface tension, and heats of dissolution of a water-acetone system on the amount of acetone in the water are studied. It is found that the reversible protolytic interaction of the components occurs in all such solutions, resulting in the formation of hydroxyl and acetonium ions. It is shown that shifts of the equilibrium between the molecules and ions in the solution leads to extreme changes in their electrical properties. It is concluded that the formation of acetone solutions of water is accompanied by heat absorption, while the formation of aqueous solutions of acetone is accompanied by heat release.

  7. The effect of cromoglycate on time-dependent histamine and serotonin concentrations in stored blood products.

    Science.gov (United States)

    Konca, Kamuran; Tiftik, E Naci; Aslan, Gönül; Kanik, Arzu; Yalçin, Atilla

    2006-04-01

    Biogenic amines, having vascular and inflammatory effects, are accepted as a potential threat for some non-hemolytic transfusion reactions. The aim of this study was to investigate time-dependent histamine/serotonin levels in stored blood products and to see whether cromoglycate has any effect on these mediators. Either for platelet or whole blood, 10-fold concentrations of cromoglycate (1 microg ml(-1), 10 microg ml(-1), 100 microg ml(-1)) with controls prepared as pairs of replicate bags collected from two healthy subjects, separately. By using enzyme immunoassay, histamine and serotonin levels were determined in platelet or blood replicates. Histamine levels increased significantly with time but serotonin remained unchanged during the storage of platelet or blood specimens. Cromoglycate had no effect on these biogenic amines except an increase of serotonin in whole blood specimens containing 100 microg ml(-1) of it. So, cromoglycate cannot protect blood products against rising levels of histamine or serotonin.

  8. Concentrations of phytochelatins and glutathione found in natural assemblages of seaweeds depend on species and metal concentrations of the habitat.

    Science.gov (United States)

    Pawlik-Skowrońska, Barbara; Pirszel, Jacek; Brown, Murray T

    2007-07-20

    The occurrence of the metal-complexing thiol peptides, phytochelatins (PC) in natural populations of brown, red and green seaweeds (marine macroalgae) was studied. Concentrations of PCs and their precursor glutathione (GSH) were measured in seaweeds collected from locations in south-west England with different levels of contamination by trace metals, to evaluate their role under natural environmental conditions. The non-protein thiols were identified and quantified in seaweed extracts by HPLC and the molecular structures of PCs were confirmed by LC-ESIMS. The capacity for production of PCs of representative seaweeds under Cd and Zn exposure was also assessed, experimentally. The concentrations of metals/metalloids (As, Cu, Cd, Pb and Zn) accumulated by the seaweeds were determined by ICP-MS. For the first time, PCs are reported in native Phaeophyceae (Fucus spp.), Rhodophyceae (Solieria chordalis) and Chlorophyceae (Rhizoclonium tortuosum) but not in thalli of Ulva spp. and Codium fragile (Chlorophyceae). The concentrations of PCs in brown and red seaweeds correlated with the contamination history of sampling sites and total metal burden of thalli. The highest concentrations of metals (5.6-7.1micromolg(-1) DW), PCs (200-240nmolSHg(-1)DW) and GSH (1,550-3,960nmolSHg(-1)DW), and the longest PC chain lengths (PC(2-4)) were found in Fucus spp. collected from the most contaminated site. A combination of PC-production and maintenance of high concentrations of GSH allows Fucus spp. and R. tortuosum (2,000nmolGSHg(-1)DW) to thrive in highly contaminated environments whereas in Ulva spp. high concentrations of GSH (1,000-1,500nmolSHg(-1)DW) together with thick cells walls and a high polysaccharide content appear to be responsible for metal-resistance. The lack of production of PCs in these green macroalgae suggests lower intracellular metal accumulation rather than an inability for synthesizing PCs. The higher concentrations of Cu (approximately 3.4micromolg(-1)DW) found in

  9. Concentration-dependent activation of dopamine receptors differentially modulates GABA release onto orexin neurons

    Science.gov (United States)

    Linehan, Victoria; Trask, Robert B.; Briggs, Chantalle; Rowe, Todd M.; Hirasawa, Michiru

    2017-01-01

    Dopamine (DA) and orexin neurons play important roles in reward and food intake. There are anatomical and functional connections between these two cell groups, where orexin peptides stimulate DA neurons in the ventral tegmental area and DA inhibits orexin neurons in the hypothalamus. However, the cellular mechanisms underlying DA action on orexin neurons remain incompletely understood. Therefore, the effect of DA on inhibitory transmission to orexin neurons was investigated in rat brain slices using whole cell patch clamp technique. We found that DA modulated the frequency of spontaneous and miniature IPSCs (mIPSCs) in a concentration dependent, bidirectional manner. Low (1 μM) and high concentrations (100 μM) of DA decreased and increased IPSC frequency, respectively. These effects did not accompany a change in mIPSC amplitude and persisted in the presence of G protein signaling inhibitor GDPβS in the pipette, suggesting that DA acts presynaptically. The decrease in mIPSC frequency was mediated by D2 receptors, whereas the increase required co-activation of D1 and D2 receptors and subsequent activation of phospholipase C. In summary, our results suggest that DA has complex effects on GABAergic transmission to orexin neurons, involving cooperation of multiple receptor subtypes. The direction of dopaminergic influence on orexin neurons is dependent on the level of DA in the hypothalamus. At low levels DA disinhibits orexin neurons whereas at high levels it facilitates GABA release, which may act as negative feedback to curb the excitatory orexinergic output to DA neurons. These mechanisms may have implications for consummatory and motivated behaviours. PMID:26036709

  10. Concentration-dependent activation of dopamine receptors differentially modulates GABA release onto orexin neurons.

    Science.gov (United States)

    Linehan, Victoria; Trask, Robert B; Briggs, Chantalle; Rowe, Todd M; Hirasawa, Michiru

    2015-08-01

    Dopamine (DA) and orexin neurons play important roles in reward and food intake. There are anatomical and functional connections between these two cell groups: orexin peptides stimulate DA neurons in the ventral tegmental area and DA inhibits orexin neurons in the hypothalamus. However, the cellular mechanisms underlying the action of DA on orexin neurons remain incompletely understood. Therefore, the effect of DA on inhibitory transmission to orexin neurons was investigated in rat brain slices using the whole-cell patch-clamp technique. We found that DA modulated the frequency of spontaneous and miniature IPSCs (mIPSCs) in a concentration-dependent bidirectional manner. Low (1 μM) and high (100 μM) concentrations of DA decreased and increased IPSC frequency, respectively. These effects did not accompany a change in mIPSC amplitude and persisted in the presence of G-protein signaling inhibitor GDPβS in the pipette, suggesting that DA acts presynaptically. The decrease in mIPSC frequency was mediated by D2 receptors whereas the increase required co-activation of D1 and D2 receptors and subsequent activation of phospholipase C. In summary, our results suggest that DA has complex effects on GABAergic transmission to orexin neurons, involving cooperation of multiple receptor subtypes. The direction of dopaminergic influence on orexin neurons is dependent on the level of DA in the hypothalamus. At low levels DA disinhibits orexin neurons whereas at high levels it facilitates GABA release, which may act as negative feedback to curb the excitatory orexinergic output to DA neurons. These mechanisms may have implications for consummatory and motivated behaviours.

  11. Formulation and in vitro evaluation of polymeric enteric nanoparticles as dermal carriers with pH-dependent targeting potential.

    Science.gov (United States)

    Sahle, Fitsum Feleke; Balzus, Benjamin; Gerecke, Christian; Kleuser, Burkhard; Bodmeier, Roland

    2016-09-20

    pH-sensitive nanoparticles which release in a controlled fashion on the skin or dissolve in the hair follicle could significantly improve treatment effectiveness and make transfollicular drug delivery a success. Dexamethasone-loaded Eudragit® L 100 nanoparticles were prepared by nanoprecipitation from an organic drug-polymer solution. Their toxicity potential was assessed using isolated human fibroblasts. pH-dependent swelling and erosion kinetics of the nanoparticles were investigated by dynamic light scattering and viscosity measurements and its effect on drug release was assessed in vitro with Franz diffusion cells. Stable, 100-550nm-sized dexamethasone-loaded Eudragit® L 100 nanoparticles with drug loading capacity and entrapment efficiency as high as 8.3% and 85%, respectively, were obtained by using polyvinyl alcohol as a stabilizer and ethanol as organic solvent. The nanoparticles showed little or no toxicity on isolated normal human fibroblasts. Dexamethasone existed in the nanoparticles as solid solution or in amorphous form. The nanoparticles underwent extensive swelling and slow drug release in media with a low buffer capacity (as low as 10mM) and a higher pH or at a pH close to the dissolution pH of the polymer (pH6) and a higher buffer capacity. In 40mM buffer and above pH6.8, the nanoparticles eroded fast or dissolved completely and thus released the drug rapidly. pH-sensitive nanoparticles which potentially release in a controlled manner on the stratum corneum but dissolve in the hair follicle could be prepared.

  12. Inverse size scaling of the nucleolus by a concentration-dependent phase transition.

    Science.gov (United States)

    Weber, Stephanie C; Brangwynne, Clifford P

    2015-03-01

    Just as organ size typically increases with body size, the size of intracellular structures changes as cells grow and divide. Indeed, many organelles, such as the nucleus [1, 2], mitochondria [3], mitotic spindle [4, 5], and centrosome [6], exhibit size scaling, a phenomenon in which organelle size depends linearly on cell size. However, the mechanisms of organelle size scaling remain unclear. Here, we show that the size of the nucleolus, a membraneless organelle important for cell-size homeostasis [7], is coupled to cell size by an intracellular phase transition. We find that nucleolar size directly scales with cell size in early C. elegans embryos. Surprisingly, however, when embryo size is altered, we observe inverse scaling: nucleolar size increases in small cells and decreases in large cells. We demonstrate that this seemingly contradictory result arises from maternal loading of a fixed number rather than a fixed concentration of nucleolar components, which condense into nucleoli only above a threshold concentration. Our results suggest that the physics of phase transitions can dictate whether an organelle assembles, and, if so, its size, providing a mechanistic link between organelle assembly and cell size. Since the nucleolus is known to play a key role in cell growth, this biophysical readout of cell size could provide a novel feedback mechanism for growth control.

  13. Model for Adsorption of Ligands to Colloidal Quantum Dots with Concentration-Dependent Surface Structure

    Energy Technology Data Exchange (ETDEWEB)

    Morris-cohen, Adam J [Northwestern University, Evanston; Vasilenko, Vladislav [Northwestern University, Evanston; Amin, Victor A [Northwestern University, Evanston; Reuter, Matthew G [ORNL; Weiss, Emily A [Northwestern University, Evanston

    2012-01-01

    A study of the adsorption equilibrium of solution-phase CdS quantum dots (QDs) and acid-derivatized viologen ligands (N-[1-heptyl],N'-[3-carboxypropyl]-4,4'-bipyridinium dihexafluorophosphate, V{sup 2+}) reveals that the structure of the surfaces of the QDs depends on their concentration. This adsorption equilibrium is monitored through quenching of the photoluminescence of the QDs by V{sup 2+} upon photoinduced electron transfer. When modeled with a simple Langmuir isotherm, the equilibrium constant for QD-V{sup 2+} adsorption, K{sub a}, increases from 6.7 x 10{sup 5} to 8.6 x 10{sup 6} M{sup -1} upon decreasing the absolute concentration of the QDs from 1.4 x 10{sup 6} to 5.1 x 10{sup 8} M. The apparent increase in K{sub a} upon dilution results from an increase in the mean number of available adsorption sites per QD from 1.1 (for [QD] = 1.4 x 10{sup 6} M) to 37 (for [QD] = 5.1 x 10{sup 8} M) through desorption of native ligands from the surfaces of the QDs and through disaggregation of soluble QD clusters. A new model based on the Langmuir isotherm that treats both the number of adsorbed ligands per QD and the number of available binding sites per QD as binomially distributed quantities is described. This model yields a concentration-independent value for K{sub a} of 8.7 x 10{sup 5} M{sup -1} for the QD-V{sup 2+} system and provides a convenient means for quantitative analysis of QD-ligand adsorption in the presence of competing surface processes.

  14. alpha-Synuclein fission yeast model: concentration-dependent aggregation without plasma membrane localization or toxicity.

    Science.gov (United States)

    Brandis, Katrina A; Holmes, Isaac F; England, Samantha J; Sharma, Nijee; Kukreja, Lokesh; DebBurman, Shubhik K

    2006-01-01

    Despite fission yeast's history of modeling salient cellular processes, it has not yet been used to model human neurodegeneration-linked protein misfolding. Because alpha-synuclein misfolding and aggregation are linked to Parkinson's disease (PD), here, we report a fission yeast (Schizosaccharomyces pombe) model that evaluates alpha-synuclein misfolding, aggregation, and toxicity and compare these properties with those recently characterized in budding yeast (Saccharomyces cerevisiae). Wild-type alpha-synuclein and three mutants (A30P, A53T, and A30P/A53T) were expressed with thiamine-repressible promoters (using vectors of increasing promoter strength: pNMT81, pNMT41, and pNMT1) to test directly in living cells the nucleation polymerization hypothesis for alpha-synuclein misfolding and aggregation. In support of the hypothesis, wild-type and A53T alpha-synuclein formed prominent intracellular cytoplasmic inclusions within fission yeast cells in a concentration- and time-dependent manner, whereas A30P and A30P/A53T remained diffuse throughout the cytoplasm. A53T alpha-synuclein formed aggregates faster than wild-type alpha-synuclein and at a lower alpha-synuclein concentration. Unexpectedly, unlike in budding yeast, wild-type and A53T alpha-synuclein did not target to the plasma membrane in fission yeast, not even at low alpha-synuclein concentrations or as a precursor step to forming aggregates. Despite alpha-synuclein's extensive aggregation, it was surprisingly nontoxic to fission yeast. Future genetic dissection might yield molecular insight into this protection against toxicity. We speculate that alpha-synuclein toxicity might be linked to its membrane binding capacity. To conclude, S. pombe and S. cerevisiae model similar yet distinct aspects of alpha-synuclein biology, and both organisms shed insight into alpha-synuclein's role in PD pathogenesis.

  15. Tricho- and atrichoblast cell files show distinct PIN2 auxin efflux carrier exploitations and are jointly required for defined auxin-dependent root organ growth.

    Science.gov (United States)

    Löfke, Christian; Scheuring, David; Dünser, Kai; Schöller, Maria; Luschnig, Christian; Kleine-Vehn, Jürgen

    2015-08-01

    The phytohormone auxin is a vital growth regulator in plants. In the root epidermis auxin steers root organ growth. However, the mechanisms that allow adjacent tissues to integrate growth are largely unknown. Here, the focus is on neighbouring epidermal root tissues to assess the integration of auxin-related growth responses. The pharmacologic, genetic, and live-cell imaging approaches reveal that PIN2 auxin efflux carriers are differentially controlled in tricho- and atrichoblast cells. PIN2 proteins show lower abundance at the plasma membrane of trichoblast cells, despite showing higher rates of intracellular trafficking in these cells. The data suggest that PIN2 proteins display distinct cell-type-dependent trafficking rates to the lytic vacuole for degradation. Based on this insight, it is hypothesized that auxin-dependent processes are distinct in tricho- and atrichoblast cells. Moreover, genetic interference with epidermal patterning supports this assumption and suggests that tricho- and atrichoblasts have distinct importance for auxin-sensitive root growth and gravitropic responses.

  16. THE DEPENDENCE OF GLYCEROL ACCUMULATION AND STARCH HYDROLYZATES FERMENTATION FROM WORT CONCENTRATION

    Directory of Open Access Journals (Sweden)

    Оliynichuk S. Т.

    2015-08-01

    Full Text Available The purpose of this work is to study the dependence of ethanol accumulation by-products and secondary products (glycerol and propionic acid during the fermentation in the case of increasing the wort concentration from 12 to 21% by weight of sugar as an example of commonly used in the alcohol industry the commercial dry yeast company “Danisco” and experimental osmophilic strain Saccharomyces cerevisiae DS-02-E, isolated from a concentrated (80% DM of rye malt wort which spontaneously fermented. The enzyme preparations “AMYLEX 4T”, “ALPHALASE AFP” and “DIAZYME SSF” were used for the liquefaction and saccharification of starch wort. The finished industrial of both yeast strains were added to the fermentation flasks in an amount of 10% by volume of the primary wort. In the mature brew the unfermented carbohydrates content was determined by colorimetric method with anthrone reagent, alcohol — by glass areometer-alcoholometer, acidity — potentiometrically, the concentration of dry matter — by areometer, glycerol content — by photocolorimetry method. In the brew distillate a volatile impurities content, namely propionic acid, was determined using gas chromatography. Statistical processing of the results of three series of experiments were carried out by calculating the arithmetical mean value of 5 measurements, their standard deviations and errors. To determine the probable differences between the mean values were used Student’s t test. Differences were considered statistically significant at P < 0.05. Reduction for accumulation of glycerol (between 38 till 53% at higher concentrations of nutrient medium in the case of the yeast Saccharomyces cerevisiae DS-02-E as compared with commercial dry yeast, reduction the formation of unwanted by-product of fermentation — propionic acid (up to 34%, a better ability of the experimental strain to accumulate sugar of wort and to accumulate ethanol (up to 0.1–0.25% vol. were shown. It

  17. Assessment of gold nanoparticles as a size-dependent vaccine carrier for enhancing the antibody response against synthetic foot-and-mouth disease virus peptide

    Science.gov (United States)

    Chen, Yu-Shiun; Hung, Yao-Ching; Lin, Wei-Hsu; Huang, Guewha Steven

    2010-05-01

    To assess the ability of gold nanoparticles (GNPs) to act as a size-dependent carrier, a synthetic peptide resembling foot-and-mouth disease virus (FMDV) protein was conjugated to GNPs ranging from 2 to 50 nm in diameter (2, 5, 8, 12, 17, 37, and 50 nm). An extra cysteine was added to the C-terminus of the FMDV peptide (pFMDV) to ensure maximal conjugation to the GNPs, which have a high affinity for sulfhydryl groups. The resultant pFMDV-GNP conjugates were then injected into BALB/c mice. Immunization with pFMDV-keyhole limpet hemocyanin (pFMDV-KLH) conjugate was also performed as a control. Blood was obtained from the mice after 4, 6, 8, and 10 weeks and antibody titers against both pFMDV and the carriers were measured. For the pFMDV-GNP immunization, specific antibodies against the synthetic peptide were detected in the sera of mice injected with 2, 5, 8, 12, and 17 nm pFMDV-GNP conjugates. Maximal antibody binding was noted for GNPs of diameter 8-17 nm. The pFMDV-GNPs induced a three-fold increase in the antibody response compared to the response to pFMDV-KLH. However, sera from either immunized mouse group did not exhibit an antibody response to GNPs, while the sera from pFMDV-KLH-immunized mice presented high levels of binding activity against KLH. Additionally, the uptake of pFMDV-GNP in the spleen was examined by inductively coupled plasma mass spectroscopy (ICP-MS) and transmission electron microscopy (TEM). The quantity of GNPs that accumulated in the spleen correlated to the magnitude of the immune response induced by pFMDV-GNP. In conclusion, we demonstrated the size-dependent immunogenic properties of pFMDV-GNP conjugates. Furthermore, we established that GNPs ranging from 8 to 17 nm in diameter may be ideal for eliciting a focused antibody response against a synthetic pFMDV peptide.

  18. Assessment of gold nanoparticles as a size-dependent vaccine carrier for enhancing the antibody response against synthetic foot-and-mouth disease virus peptide

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yu-Shiun [Department of Materials Science and Engineering, National Chiao Tung University, 1001 University Road, EE137, Hsinchu 300, Taiwan (China); Hung, Yao-Ching [Department of Obstetrics and Gynecology, School of Medicine, China Medical University and Hospital, 91 Hsueh-Shih Road, Taichung 40402, Taiwan (China); Lin, Wei-Hsu [Institute of Nanotechnology, National Chiao Tung University, 1001 University Road, Hsinchu 300, Taiwan (China); Huang, Guewha Steven, E-mail: gstevehuang@mail.nctu.edu.tw [Department of Materials Science and Engineering, Institute of Nanotechnology, National Chiao Tung University, 1001 University Road, Hsinchu 300, Taiwan, Republic of China (China)

    2010-05-14

    To assess the ability of gold nanoparticles (GNPs) to act as a size-dependent carrier, a synthetic peptide resembling foot-and-mouth disease virus (FMDV) protein was conjugated to GNPs ranging from 2 to 50 nm in diameter (2, 5, 8, 12, 17, 37, and 50 nm). An extra cysteine was added to the C-terminus of the FMDV peptide (pFMDV) to ensure maximal conjugation to the GNPs, which have a high affinity for sulfhydryl groups. The resultant pFMDV-GNP conjugates were then injected into BALB/c mice. Immunization with pFMDV-keyhole limpet hemocyanin (pFMDV-KLH) conjugate was also performed as a control. Blood was obtained from the mice after 4, 6, 8, and 10 weeks and antibody titers against both pFMDV and the carriers were measured. For the pFMDV-GNP immunization, specific antibodies against the synthetic peptide were detected in the sera of mice injected with 2, 5, 8, 12, and 17 nm pFMDV-GNP conjugates. Maximal antibody binding was noted for GNPs of diameter 8-17 nm. The pFMDV-GNPs induced a three-fold increase in the antibody response compared to the response to pFMDV-KLH. However, sera from either immunized mouse group did not exhibit an antibody response to GNPs, while the sera from pFMDV-KLH-immunized mice presented high levels of binding activity against KLH. Additionally, the uptake of pFMDV-GNP in the spleen was examined by inductively coupled plasma mass spectroscopy (ICP-MS) and transmission electron microscopy (TEM). The quantity of GNPs that accumulated in the spleen correlated to the magnitude of the immune response induced by pFMDV-GNP. In conclusion, we demonstrated the size-dependent immunogenic properties of pFMDV-GNP conjugates. Furthermore, we established that GNPs ranging from 8 to 17 nm in diameter may be ideal for eliciting a focused antibody response against a synthetic pFMDV peptide.

  19. The Complete Solution of Fick's Second Law of Diffusion with Time-dependent Diffusion Coefficient and Surface Concentration

    DEFF Research Database (Denmark)

    Mejlbro, Leif

    1996-01-01

    Fick's Second Law of Diffusion with time-dependent diffusioncoefficient and surface concentration is solved. Mimicking the classicalsolution, special time-dependent surface concentration functions areconsidered. These models are used in giving estimates of the lifetimeof the structure, when...... the concrete cover is given, as well as estimatesof the thickness of the concrete cover, when the expected lifetime is given.*Note: Book tilte: Durability of Concrete in Saline Environment...

  20. Investigating thermal donors in n-type Cz silicon with carrier density imaging

    Directory of Open Access Journals (Sweden)

    Yu Hu

    2012-09-01

    Full Text Available A new method to map the thermal donor concentration in silicon wafers using carrier density imaging is presented. A map of the thermal donor concentration is extracted with high resolution from free carrier density images of a silicon wafer before and after growth of thermal donors. For comparison, free carrier density mapping is also performed using the resistivity method together with linear interpolation. Both methods reveal the same distribution of thermal donors indicating that the carrier density imaging technique can be used to map thermal donor concentration. The interstitial oxygen concentration can also be extracted using the new method in combination with Wijaranakula's model. As part of this work, the lifetime at medium injection level is correlated to the concentration of thermal donors in the as-grown silicon wafer. The recombination rate is found to depend strongly on the thermal donor concentration except in the P-band region.

  1. Concentration-dependent, size-independent toxicity of citrate capped AuNPs in Drosophila melanogaster.

    Directory of Open Access Journals (Sweden)

    Giuseppe Vecchio

    Full Text Available The expected potential benefits promised by nanotechnology in various fields have led to a rapid increase of the presence of engineered nanomaterials in a high number of commercial goods. This is generating increasing questions about possible risks for human health and environment, due to the lack of an in-depth assessment of the physical/chemical factors responsible for their toxic effects. In this work, we evaluated the toxicity of monodisperse citrate-capped gold nanoparticles (AuNPs of different sizes (5, 15, 40, and 80 nm in the model organism Drosophila melanogaster, upon ingestion. To properly evaluate and distinguish the possible dose- and/or size-dependent toxicity of the AuNPs, we performed a thorough assessment of their biological effects, using two different dose-metrics. In the first approach, we kept constant the total surface area of the differently sized AuNPs (Total Exposed Surface area approach, TES, while, in the second approach, we used the same number concentration of the four different sizes of AuNPs (Total Number of Nanoparticles approach, TNN. We observed a significant AuNPs-induced toxicity in vivo, namely a strong reduction of Drosophila lifespan and fertility performance, presence of DNA fragmentation, as well as a significant modification in the expression levels of genes involved in stress responses, DNA damage recognition and apoptosis pathway. Interestingly, we found that, within the investigated experimental conditions, the toxic effects in the exposed organisms were directly related to the concentration of the AuNPs administered, irrespective of their size.

  2. Effects of spray-drying and choice of solid carriers on concentrations of Labrasol® and Transcutol® in solid self-microemulsifying drug delivery systems (SMEDDS).

    Science.gov (United States)

    Li, Liang; Yi, Tao; Lam, Christopher Wai-Kei

    2013-01-02

    Solid self-microemulsifying drug delivery systems (SMEDDS) have been used increasingly for improving the bioavailability of hydrophobic drugs. Labrasol® and Transcutol® are used widely as surfactant and solubilizer in the formulation of solid SMEDDS. We investigated the effects of spray-drying and the use of different solid carriers on concentrations of Labrasol® and Transcutol® in solid SMEDDS with scutellarin as the formulated drug. Liquid and gas chromatography tandem mass spectrometry (LC-MS and GC-MS) methods were developed for measuring low concentrations of Labrasol® and Transcutol®. In the preparation of solid SMEDDS, lactose, hydroxypropylmethyl cellulose (HPMC) and microcrystalline cellulose (MCC) were used as solid carriers. Judging from the retention ratios of Labrasol® and Transcutol®, the droplet size of solid SMEDDS increased after spray-drying of liquid SMEDDS, and concentrations of these excipients decreased after the solidifying procedure. In such reduction, Lactose and HPMC were found to preserve Labrasol® and Transcutol® better than MCC during spray-drying, and the resultant droplet sizes were smaller than that of MCC. Labrasol® and Transcutol® showed good thermal stability at 60 °C degree for 10 days. It can be concluded that spray-drying could increase the droplet size of solid SMEDDS and decreased the concentration of Labrasol® and Transcutol® therein, while water-soluble solid carriers could preserve Labrasol® and Transcutol® better than insoluble carriers in the solid SMEDDS.

  3. Elevated CO{sub 2} response of photosynthesis depends on ozone concentration in aspen

    Energy Technology Data Exchange (ETDEWEB)

    Noormets, Asko, E-mail: anoorme@ncsu.ed [Michigan Technological University, School of Forest Resources and Environmental Science, Houghton, MI 49931 (United States); Kull, Olevi; Sober, Anu [University of Tartu, Institute of Botany and Ecology, Tartu, Estonia (United States); Kubiske, Mark E. [US Forest Service, Northern Research Lab, Rhinelander, WI 54501 (United States); Karnosky, David F. [Michigan Technological University, School of Forest Resources and Environmental Science, Houghton, MI 49931 (United States)

    2010-04-15

    The effect of elevated CO{sub 2} and O{sub 3} on apparent quantum yield (phi), maximum photosynthesis (P{sub max}), carboxylation efficiency (V{sub cmax}) and electron transport capacity (J{sub max}) at different canopy locations was studied in two aspen (Populus tremuloides) clones of contrasting O{sub 3} tolerance. Local light climate at every leaf was characterized as fraction of above-canopy photosynthetic photon flux density (%PPFD). Elevated CO{sub 2} alone did not affect phi or P{sub max}, and increased J{sub max} in the O{sub 3}-sensitive, but not in the O{sub 3}-tolerant clone. Elevated O{sub 3} decreased leaf chlorophyll content and all photosynthetic parameters, particularly in the lower canopy, and the negative impact of O{sub 3} increased through time. Significant interaction effect, whereby the negative impact of elevated O{sub 3} was exaggerated by elevated CO{sub 2} was seen in Chl, N and J{sub max}, and occurred in both O{sub 3}-tolerant and O{sub 3}-sensitive clones. The clonal differences in the level of CO{sub 2} x O{sub 3} interaction suggest a relationship between photosynthetic acclimation and background O{sub 3} concentration. - Photosynthetic acclimation to elevated CO{sub 2} depends on the background oxidant levels.

  4. Experimental Study on Surface Reactions of Heavy Metal Ions With Quartz—Aqueous Ion Concentration Dependence

    Institute of Scientific and Technical Information of China (English)

    吴宏海; 吴大清; 等

    1999-01-01

    Adsorption of divalent metal ions,including Cu2+,Pb2+,Zn2+,Cd2+ and Ni2+,on quartz surface was measured as a function of metal ion concentration at 30℃under condi tions of solution pH=6.5 and ion strength I=0.1mol/L.Results of the experimental measuements can be described very well by adsorption isoterm dquations of Freudlich.The correlation coefficients(r)of adsorption isotherm lines are>0.96.Moreover,the exprimental data were interpreted on the basis of surface complexation model.Te experimental results showed that the monodentate-coordinated metal ion surface complex species(SOM+)are predominant over the bidentate-coordinated metal ion surface complex species[(SO)2M]formed only by the ions Cu2+,Zn2+ and Ni2+,And the relevant apparent surface complexation constants are lgKM=2.2-3.3 in order of KCd≥KPb>KZn>KNi≥KCu,and lgβM=5.8-6.8 in oder of βNi>βZn>βCu.Therefore,the reactive ability of the ions onto mineral surface of quartz follows the order of Cd>Pb>Zn>Ni>Cu under the above-mentioned solution conditions.The apparent surface complexation constants,influenced by the surface potential,surface species and hydrolysis of metal ions,depend mainly on the Born solvation coefficeient of the metal ions.

  5. Electronic structure and carrier transfer in B-DNA monomer polymers and dimer polymers: Stationary and time-dependent aspects of wire model vs. extended ladder model

    CERN Document Server

    Lambropoulos, K; Morphis, A; Kaklamanis, K; Lopp, R; Theodorakou, M; Tassi, M; Simserides, C

    2016-01-01

    We employ two Tight-Binding (TB) approaches to study the electronic structure and hole or electron transfer in B-DNA monomer polymers and dimer polymers made up of $N$ monomers (base pairs): (I) at the base-pair level, using the on-site energies of base pairs and the hopping integrals between successive base pairs, i.e., a wire model and (II) at the single-base level, using the on-site energies of the bases and the hopping integrals between neighboring bases, i.e., an \\textit{extended} ladder model since we also include diagonal hoppings. We solve a system of $MD$ ("matrix dimension") coupled equations [(I) $MD$ = $N$, (II) $MD$ = $2N$] for the time-independent problem, and a system of $MD$ coupled $1^\\text{st}$ order differential equations for the time-dependent problem. We study the HOMO and the LUMO eigenspectra, the occupation probabilities, the Density of States (DOS) and the HOMO-LUMO gap as well as the mean over time probabilities to find the carrier at each site [(I) base pair or (II) base)], the Four...

  6. Concentration dependence of molal conductivity and dielectric constant of 1-alcohol electrolytes using the compensated arrhenius formalism.

    Science.gov (United States)

    Fleshman, Allison M; Petrowsky, Matt; Frech, Roger

    2013-05-02

    The molal conductivity of liquid electrolytes with low static dielectric constants (ε(s) Arrhenius formalism (CAF) to the molal conductivity, Λ, of a family of 1-alcohol electrolytes over a broad concentration range. A scaling procedure is applied that results in an energy of activation (E(a)) and an exponential prefactor (Λ0) that are both concentration dependent. It is shown that the increasing molal conductivity in region II results from the combined effect of (1) a decrease in the energy of activation calculated from the CAF, and (2) an inherent concentration dependence in the exponential prefactor that is partly due to the dielectric constant.

  7. Electron concentration dependence of optical band gap shift in Ga-doped ZnO thin films by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yaqin [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Tang, Wu, E-mail: tang@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Zhang, Lan [State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Zhao, Junliang [Shanghai Juntech Co. Ltd., 1378 Xingxian Road, Shanghai 201815 (China)

    2014-08-28

    Ga-doped ZnO (GZO) thin films were deposited on glass substrates by a radio frequency magnetron sputtering technique. The optical properties of the deposited GZO films were evaluated using an optical transmission measurement. The optical band gap increased from 3.32 eV to 3.45 eV with the increasing carrier density from 2.0 × 10{sup 20} cm{sup −3} to 3.24 × 10{sup 20} cm{sup −3}. Based on the experimental results, the optical band gap as a function of carrier density is systematically investigated with four available theoretical models taken into consideration. The blueshift of the optical band gap in GZO films can be well interpreted with a complex model which combines the Burstein–Moss effect, the band gap renormalization effect and the nonparabolic nature of conduction band. In addition, the BM contribution is almost offset by the BGR effect in both conduction band and valence band due to the approximate equality between electron and hole effective masses in GZO films with a nonparabolic conduction band. The tunability of optical band gap in GZO thin films by carrier density offers a number of potential advantages in the development of semiconductor optoelectronic devices. - Highlights: • The effects of electron concentration on optical band gap were analyzed. • The measured optical band gap corresponded well with the calculated ones. • The Burstein–Moss (BM) and band gap renormalization (BGR) effects were considered. • Nonparabolic conduction band parameters were used in theoretical analysis. • The BM effect was offset by the BGR effect in both conduction band and valence band.

  8. Widely Tunable Infrared Antennas Using Free Carrier Refraction.

    Science.gov (United States)

    Lewi, Tomer; Iyer, Prasad P; Butakov, Nikita A; Mikhailovsky, Alexander A; Schuller, Jon A

    2015-12-01

    We demonstrate tuning of infrared Mie resonances by varying the carrier concentration in doped semiconductor antennas. We fabricate spherical silicon and germanium particles of varying sizes and doping concentrations. Single-particle infrared spectra reveal electric and magnetic dipole, quadrupole, and hexapole resonances. We subsequently demonstrate doping-dependent frequency shifts that follow simple Drude models, culminating in the emergence of plasmonic resonances at high doping levels and long wavelengths. These findings demonstrate the potential for actively tuning infrared Mie resonances by optically or electrically modulating charge carrier densities, thus providing an excellent platform for tunable metamaterials.

  9. STUDY ON THE CONCENTRATION DEPENDENCE OF ORIENTATION OF POLYSTYRENE ON SILVER BY THE SERS TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    Dong-hui Zhang; Jin-gui Qin; Jing-shu Shen; You Wang; Wan-jun Liu

    2000-01-01

    Polystyrene films were adsorbed onto a silver surface from dichloromethane solutions with concentrations of 0.1 to 12 wt%, and then studied by the surface enhanced Raman technique. A critical concentration for coil interpenetration was observed.

  10. Concentration-dependent inhibitory and stimulating effects of amphiphilic ammonium salts upon photosynthetic activity of spinach chloroplasts.

    Science.gov (United States)

    Sersen, F; Král'ová, K

    1996-02-01

    The effects of piperidinopropylesters of 2-, 3- and 4-alkoxy substituted phenylcarbamic acids (PPACs) on oxygen evolution rate (OER) in spinach chloroplasts were investigated. PPAGs show concentration-dependent effects, namely OER inhibition at higher effector concentrations and OER stimulation at lower concentrations, i.e. below the inhibitory concentration range. The inhibitory efficiency of PPACs showed dependence on the alkyl chain length of the alkoxy substituent as well as on the position of this substituent on the benzene ring. Using EPR spectroscopy and fluorescence measurements it was confirmed that the site of PPAC inhibitory action is the donor side of photosystem 2, where D1 and D2 proteins are situated, namely the intermediates Z+/Y+, and the manganese cluster containing protein as well. The stimulating effects of PPACs on OER in spinach chloroplasts at relatively low effector concentrations are caused by photophosphorylation uncoupling due to protonophore properties of the effectors.

  11. Shielding effects in polymer-polymer reactions. V. Concentration dependence of contact formation between star-branched and linear chains.

    Science.gov (United States)

    Nardai, Michael M; Zifferer, Gerhard

    2013-07-19

    By use of the Dissipative Particle Dynamics (DPD) simulation technique mixtures of star-branched (arm number F = 4) and linear chains in athermal (good) solvent are analyzed regarding probabilities for intermolecular contacts of various reactive sites within different polymer coils. The accompanying sterical hindrances are described in the framework of shielding factors in order to investigate reactions and side reactions in radical polymerization and other techniques that involve polymer-polymer coupling. The shielding factors are studied as a function of total concentration from high dilution up to the bulk for different chain lengths of star-shaped and linear chains. Results indicate that their concentration dependence can be described by a power law for systems above the overlap concentration, whereas the chain length dependence vanishes when extrapolating to infinite chain lengths in that concentration range. Also the influence of the ratio of star chains and linear chains is studied for various concentrations.

  12. Size- and concentration-dependent deposition of fluorescent silica colloids in saturated sand columns: transport experiments and modeling.

    Science.gov (United States)

    Vitorge, Elsa; Szenknect, Stéphanie; Martins, Jean M F; Gaudet, Jean-Paul

    2013-08-01

    This study investigates the size and concentration effects on the transport of silica colloids in columns of sandy aquifer material. Colloid transport experiments were performed with specifically developed fluorescent labeled silica colloids in columns of a repacked natural porous medium under hydro-geochemical conditions representative of sandy aquifers. Breakthrough curves and vertical deposition profiles of colloids were measured for various colloid concentrations and sizes. The results showed that for a given colloid concentration injected, deposition increased when increasing the size of the colloids. For a given colloid size, retention was also shown to be highly concentration-dependent with a non-monotonous pattern presenting low and high concentration specificities. Deposition increases when increasing both size and injected concentration, until a threshold concentration is reached, above which retention decreases, thus increasing colloid mobility. Results observed above the threshold concentration agree with a classical blocking mechanism typical of a high concentration regime. Results observed at lower colloid concentrations were not modeled with a classical blocking model and a depth- and time-dependent model with a second order kinetic law was necessary to correctly fit the experimental data in the entire range of colloid concentrations with a single set of parameters for each colloidal size. The colloid deposition mechanisms occuring at low concentrations were investigated through a pore structure analysis carried out with Mercury Intrusion Porosimetry and image analysis. The determined pore size distribution permitted estimation of the maximal retention capacity of the natural sand as well as some low flow zones. Altogether, these results stress the key role of the pore space geometry of the sand in controlling silica colloids deposition under hydro-geochemical conditions typical of sandy aquifers. Our results also showed originally that colloid

  13. A new insight into fecal hemoglobin concentration-dependent predictor for colorectal neoplasia.

    Science.gov (United States)

    Yen, Amy Ming-Fang; Chen, Sam Li-Sheng; Chiu, Sherry Yueh-Hsia; Fann, Jean Ching-Yuan; Wang, Po-En; Lin, Sheng-Che; Chen, Yao-Der; Liao, Chao-Sheng; Yeh, Yen-Po; Lee, Yi-Chia; Chiu, Han-Mo; Chen, Hsiu-Hsi

    2014-09-01

    We sought to assess how much of the variation in incidence of colorectal neoplasia is explained by baseline fecal hemoglobin concentration (FHbC) and also to assess the additional predictive value of conventional risk factors. We enrolled subjects aged 40 years and over who attended screening for colorectal cancer with the fecal immunochemical test (FIT) in Keelung community-based integrated screening program. The accelerated failure time model was used to train the clinical weights of covariates in the prediction model. Datasets from two external communities were used for external validation. The area under curve (AUC) for the model containing only FHbC was 83.0% (95% CI: 81.5-84.4%), which was considerably greater than the one containing only conventional risk factors (65.8%, 95% CI: 64.2-67.4%). Adding conventional risk factors did not make significant additional contribution (p = 0.62, AUC = 83.5%, 95% CI: 82.1-84.9%) to the predictive model with FHbC only. Males showed a stronger linear dose-response relationship than females, yielding gender-specific FHbC predictive models. External validation confirms these results. The high predictive ability supported by a dose-dependent relationship between baseline FHbC and the risk of developing colorectal neoplasia suggests that FHbC may be useful for identifying cases requiring closer postdiagnosis clinical surveillance as well as being an early indicator of colorectal neoplasia risk in the general population. Our findings may also make contribution to the development of the FHbC-guided screening policy but its pros and cons in connection with cost and effectiveness of screening should be evaluated before it can be applied to population-based screening for colorectal cancer.

  14. Temperature dependence of photoluminescence spectra of bilayer two-dimensional electron gases in LaAlO3/SrTiO3 superlattices: coexistence of Auger recombination and single-carrier trapping

    Directory of Open Access Journals (Sweden)

    H. J. Harsan Ma

    2015-06-01

    Full Text Available We report emerging photoluminescence (PL of bilayer two-dimensional electron gases (2DEG in LaAlO3/SrTiO3 (LAO/STO systems. A strong blue PL emerges in bilayer-2DEGs in LAO/STO/LAO/STO which doesn’t show in LAO/STO. PL band in bilayer-2DEGs includes both nearly temperature independent Auger recombination and temperature dependent free electron trapping while it crossovers from Auger recombination to single carrier trapping in LAO/STO. The PL signal of free electron trapping appears at high temperatures and it is much stronger than Auger recombination in the conducting channel in bilayer 2DEGs. This observation shows that high mobility carriers dominate the carrier dynamics in bilayer-2DEGs in LAO/STO superlattices.

  15. 居民低压集中抄表系统组网方式%Briefly on the networking method of low voltage power carrier concentrated meter reading, system

    Institute of Scientific and Technical Information of China (English)

    刘铀

    2011-01-01

    The existing low voltage concentrated meter reading way is analyzed. From the present situation and necessity,this paper further expounds the diversity of network mode, introduces the advantages and disadvantages of RS485, power broadband carrier, narrowband carrier and wireless, and puts forward hybrid network mode without wasting existing equipment.%分析了现有的低压居民集中抄表方式,从现状、必要性上进一步阐述了组网方式的多样性,详细介绍了RS485、电力宽带载波、窄带载波、无线四种方式的优缺点,提出了在不浪费现有设备的情况下的混合组网方式。

  16. Forsterite Carbonation in Wet-scCO2: Dependence on Adsorbed Water Concentration

    Science.gov (United States)

    Loring, J.; Benezeth, P.; Qafoku, O.; Thompson, C.; Schaef, T.; Bonneville, A.; McGrail, P.; Felmy, A.; Rosso, K.

    2013-12-01

    Capturing and storing CO2 in basaltic formations is one of the most promising options for mitigating atmospheric CO2 emissions resulting from the burning of fossil fuels. These geologic reservoirs have high reactive potential for CO2-mineral trapping due to an abundance of divalent-cation containing silicates, such as forsterite (Mg2SiO4). Recent studies have shown that carbonation of these silicates under wet scCO2 conditions, e. g. encountered near a CO2 injection well, proceeds along a different pathway and is more effective than in CO2-saturated aqueous fluids. The presence of an adsorbed water film on the forsterite surface seems to be key to reactivity towards carbonation. In this study, we employed in situ high pressure IR spectroscopy to investigate the dependence of adsorbed water film thickness on forsterite carbonation chemistry. Post reaction ex situ SEM, TEM, TGA, XRD, and NMR measurements will also be discussed. Several IR titrations were performed of forsterite with water at 50 °C and 90 bar scCO2. Aliquots of water were titrated at 4-hour reaction-time increments. Once a desired total water concentration was reached, data were collected for about another 30 hours. One titration involved 10 additions, which corresponds to 6.8 monolayers of adsorbed water. Clearly, a carbonate was precipitating, and its spectral signature matched magnesite. Another titration involved 8 aliquots, or up to 4.4 monolayers of water. The integrated absorbance under the CO stretching bands of carbonate as a function of time after reaching 4.4 monolayers showed an increase and then a plateau. We are currently unsure of the identity of the carbonate that precipitated, but it could be an amorphous anhydrous phase or magnesite crystals with dimensions of only several nanometers. A third titration only involved 3 additions, or up to 1.6 monolayers of water. The integrated absorbance under the CO stretching bands of carbonate as a function of time after reaching 1.6 monolayers

  17. A molecular dynamic model for analyzing concentrations of electrolytes: Fractional molar dependences of microstructure properties

    Science.gov (United States)

    Khalansky, D.; Popova, E.; Gladyshev, P.; Dushanov, E.; Kholmurodov, Kh.

    2014-12-01

    electrolyte concentration: 16, 8, and 1 mol/kg. Energies of diffusion activation are calculated using the Arrhenius equation, thereby constructing temperature dependence graphs of diffusion coefficients for all four electrolyte systems. The observed diffusion properties of the electrolyte systems are found to correlate well with the energy and structural radial distribution data.

  18. Implementation of depth-dependent soil concentrations in multimedia mass balance models.

    NARCIS (Netherlands)

    Hollander, A.; Hessels, L.; Voogt, P De; Meent, D. van de

    2004-01-01

    In standard multimedia mass balance models, the soil compartment is modeled as a box with uniform concentrations, which often does not correspond with actual field situations. Therefore, the theoretically expected decrease of soil concentrations with depth was implemented in the multimedia model Sim

  19. Implementation of depth-dependent soil concentrations in multimedia mass balance models

    NARCIS (Netherlands)

    Hollander, A.; Hessels, L.; de Voogt, P.; van de Meent, D.

    2004-01-01

    In standard multimedia mass balance models, the soil compartment is modeled as a box with uniform concentrations, which often does not correspond with actual field situations. Therefore, the theoretically expected decrease of soil concentrations with depth was implemented in the multimedia model Sim

  20. Time- and concentration-dependent effects of resveratrol in HL-60 and HepG2 cells

    DEFF Research Database (Denmark)

    Stervbo, Ulrik; Vang, Ole; Bonnesen, Christine

    2006-01-01

    , an increase in nuclear size and granularity was observed in the G1 and S phases of HL-60 treated and HepG2-treated cells. Apoptosis was also stimulated by resveratrol in a concentration-dependent manner in HL-60 and HepG2 cells. In conclusion, resveratrol inhibits cell proliferation in a concentration......- and time-dependent manner by interfering with different stages of the cell cycle. Furthermore, resveratrol treatment causes stimulation of apoptosis as well as an increase in nuclear size and granularity....

  1. Hormone-dependent aggression in male rats is proportional to serum testosterone concentration but sexual behavior is not.

    Science.gov (United States)

    Albert, D J; Jonik, R H; Watson, N V; Gorzalka, B B; Walsh, M L

    1990-09-01

    Male hooded rats were castrated and implanted with Silastic capsules (1.57 mm i.d.; 3.18 mm o.d.) having a testosterone-filled space 0, 7, 22, 60, or 90 mm long. All animals were returned to their original group cages for a three-week period to allow hormone concentrations and behavioral tendencies to stabilize. Each male was then housed with an intact female in a large cage. Aggression by the male toward an unfamiliar male was tested at weekly intervals for three weeks. Sexual behavior with an estrogen/progesterone-primed ovariectomized female was tested on each of the subsequent two weeks. Serum testosterone was measured during the following week. The frequency of aggression was correlated with serum testosterone concentration up to the normal level and did not increase with higher serum testosterone concentrations. In contrast, sexual behavior was virtually absent in animals with no testosterone replacement and normal in all other groups. These results demonstrate a clear dissociation in the dependence of hormone-dependent aggression and sexual behavior on serum testosterone concentration. In a male cohabiting with a female, sexual experience activates hormone-dependent aggression toward an unfamiliar male but the level of aggression that develops depends on the serum testosterone concentration in the resident male.

  2. Serum fructosamine concentrations in patients with type II (non-insulin-dependent) diabetes mellitus during changes in management.

    Science.gov (United States)

    Baker, J R; Johnson, R N; Scott, D J

    1984-01-01

    The serum fructosamine concentration was examined as a new means to monitor metabolic control in non-insulin-dependent diabetes during changes in management. Weekly fructosamine estimations were compared with glycosylated haemoglobin (HbA1c), 24 hour urinary glucose, and fasting plasma glucose concentrations in a 17 week study entailing withdrawal and reinstitution of oral treatment. The serum fructosamine concentration was more sensitive than the other measurements in detecting a deterioration in diabetic control after stopping oral hypoglycaemic drugs. The response to reinstitution of treatment was not significant in the first three weeks (p = 0.266), despite a highly significant reduction in fasting plasma glucose (p = 0.001) and 24 hour urinary glucose concentrations (p = 0.012). Compared with HbA1c, concentrations of fructosamine appeared more useful in monitoring short term (three to six weeks) changes after alterations in management of diabetes. Additional advantages were lower cost and technical simplicity of measurement. PMID:6426612

  3. Concentrations of Chemical Elements in Willow Biomass Depend on Clone, Site and Management in the Field

    DEFF Research Database (Denmark)

    Liu, Na; Jørgensen, Uffe; Lærke, Poul Erik

    2016-01-01

    Eight willow (Salix) clones (Inger, Klara, Linnea, Resolution, Stina, Terra Nova, Tora, Tordis) were planted on two soil types in Denmark. The biomass quality was evaluated after 3 years of growth by measuring differences in concentrations of 14 elements associated with ash behavior during...... to 22, 27, 35, and 23 % higher concentrations of K, S, Ca, and total ash than the other clones. In addition to clone and site, appropriate management could further improve the fuel quality of willow biomass. When shoots of Inger were harvested annually (1-year shoots) high concentrations of K and Cl...... plant densities (8000 and 12,000 trees ha−1) of the clones Inger and Tora after the first 3-year rotation when grown at the site with a coarse sandy soil. The study indicates considerable diversity in concentration of elements within commercially available willow cultivars and suggests breeders...

  4. Hematotoxicity and concentration-dependent conjugation of phenol in mice following inhalation exposure to benzene.

    Science.gov (United States)

    Wells, M S; Nerland, D E

    1991-04-01

    Benzene is metabolized to one or more hematotoxic species. Saturation of benzene metabolism could limit the production of toxic species. Saturation of phase II enzymes involved in the conjugation of the phenolic metabolites of benzene also could affect the hematotoxicity of benzene. To investigate the latter possibility, we exposed male Swiss mice, via the inhalation route, to various concentrations of benzene for 6 h per day for 5 days. Following termination of the final exposure the mice were killed and the levels of phenylsulfate and phenylglucuronide in the blood determined. Spleen weights were recorded and the number of white blood cells counted. At low benzene exposure concentrations phenylsulfate is the major conjugated form of phenol in the blood. At high exposure concentrations, phenylglucuronide is the predominant species. The reductions in spleen weight and white blood cell numbers correlated with the concentration of phenylsulfate in the blood, but are most probably not causally related.

  5. Metabolic pathways and activity-dependent modulation of glutamate concentration in the human brain.

    Science.gov (United States)

    Mangia, Silvia; Giove, Federico; Dinuzzo, Mauro

    2012-11-01

    Glutamate is one of the most versatile molecules present in the human brain, involved in protein synthesis, energy production, ammonia detoxification, and transport of reducing equivalents. Aside from these critical metabolic roles, glutamate plays a major part in brain function, being not only the most abundant excitatory neurotransmitter, but also the precursor for γ-aminobutyric acid, the predominant inhibitory neurotransmitter. Regulation of glutamate levels is pivotal for normal brain function, as abnormal extracellular concentration of glutamate can lead to impaired neurotransmission, neurodegeneration and even neuronal death. Understanding how the neuron-astrocyte functional and metabolic interactions modulate glutamate concentration during different activation status and under physiological and pathological conditions is a challenging task, and can only be tentatively estimated from current literature. In this paper, we focus on describing the various metabolic pathways which potentially affect glutamate concentration in the brain, and emphasize which ones are likely to produce the variations in glutamate concentration observed during enhanced neuronal activity in human studies.

  6. Changes in concentration of visfatin during four weeks of inpatient treatment of alcohol dependent males

    Directory of Open Access Journals (Sweden)

    Damian Czarnecki

    2015-09-01

    Conclusions: The dynamic of change in the concentration of visfatin during four weeks of abstinence is not associated with a reduction in craving for alcohol at the time and is associated with alcohol drinking and liver functioning.

  7. Concentration-Dependent Effects of Caspofungin on the Metabolic Activity of Aspergillus Species▿

    OpenAIRE

    2006-01-01

    The minimum effective concentration (MEC) used to assess the in vitro antifungal activity of caspofungin against Aspergillus spp. is a qualitative endpoint requiring microscopic examination of hyphae. We therefore developed a tool for the quantitative assessment of caspofungin activity against Aspergillus spp. at clinically applicable concentrations. Susceptibility to caspofungin (0.008 to 8 μg/ml) was studied for 9 A. fumigatus, 8 A. flavus, and 12 A. terreus isolates based on the Clinical a...

  8. Concentration dependent luminescence studies on Eu{sup 3+} doped telluro fluoroborate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Vijayakumar, R. [Department of Physics, Gandhigram Rural University, Gandhigram 624302 (India); Maheshvaran, K. [Department of Physics, K.S. Rangasamy College of Technology, Trichengode 637215 (India); Sudarsan, V. [Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Marimuthu, K., E-mail: mari_ram2000@yahoo.com [Department of Physics, Gandhigram Rural University, Gandhigram 624302 (India)

    2014-10-15

    Eu{sup 3+} doped telluro fluoroborate glasses with the chemical composition (40–x)B{sub 2}O{sub 3}+15TeO{sub 2}+15Li{sub 2}CO{sub 3}+15LiF+15NaF+xEu{sub 2}O{sub 3} (where x=0.05, 0.1, 0.25, 0.5, 1 and 2 in wt%) have been prepared following the melt quenching technique. Optical properties of the prepared glasses were studied through the absorption, excitation, luminescence and decay spectral measurements. Nephelauxetic's ratios (β{sub R}) and bonding parameters (δ) were calculated from the absorption spectra to examine the nature of the bonding between the Eu{sup 3+} ion and its surrounding ligands. The optical band gap and Urbach's energy of the title glasses were determined from the absorption spectra to study the electronic band structure and it is observed that, the band gap values vary inversely with the Urbach's energy values. The Judd–Ofelt intensity parameters (Ω{sub 2}, Ω{sub 4} and Ω{sub 6}) determined from the emission spectra provides valuable information about the Eu–O bonding nature and the structure of the local environment around the Eu{sup 3+} ion site. The luminescence intensity ratio (R) of the {sup 5}D{sub 0}→{sup 7}F{sub 2}/{sup 5}D{sub 0}→{sup 7}F{sub 1} transition has been calculated from the emission spectra to determine the degree of asymmetry around the Eu{sup 3+} ion site and to identify the strength of the covalence of Eu{sup 3+} ion with its surrounding ligands. The chromaticity coordinates have been calculated from the emission spectra and analyzed with Commission International de I'Eclairage (CIE) 1931 diagram. The JO intensity parameters have been used to determine the radiative properties such as radiative transition probability (A{sub R}), stimulated emission cross-section σ{sub p}{sup E} and branching ratios (β{sub R}) to estimate the lasing power of the emission transitions and optical gain band width due to their practical importance in laser applications. - Highlights: • Concentration

  9. Persistence of the superconducting condensate far above the critical temperature of YBa2(Cu,Zn)3O(y) revealed by c-axis optical conductivity measurements for several Zn concentrations and carrier doping levels.

    Science.gov (United States)

    Uykur, Ece; Tanaka, Kiyohisa; Masui, Takahiko; Miyasaka, Shigeki; Tajima, Setsuko

    2014-03-28

    The superconductivity precursor phenomena in high temperature cuprate superconductors is studied by direct measurements of the superconducting condensate with the use of the c-axis optical conductivity of YBa2(Cu1-xZnx)3Oy for several doping levels (p) as well as for several Zn concentrations. Both the real and imaginary parts of the optical conductivity clearly show that the superconducting carriers persist up to the high temperatures Tp that is higher than the critical temperature Tc but lower than the pseudogap temperature T*. Tp increases with reducing doping level like T*, but decreases with Zn substitution unlike T*.

  10. Concentration dependence of the embryotoxic effects of benzene inhalation in CFY rats.

    Science.gov (United States)

    Tátrai, E; Ungváry, G; Hudák, A; Rodics, K; Lörincz, M; Barcza, G

    1980-01-01

    CFY rats were exposed to continuous benzene inhalation 24 h/day from day 7 to day 14 of gestation at 150, 450, 1500, or 3000 mg/m3 (50, 150, 500, or 1000 ppm) atmospheric concentrations. None of the benzene concentrations used proved to be teratogenic. There was no increase in the incidence of external, visceral, or skeletal malformations. Benzene inhalation at a 150 mg/m3 concentration brought about a slight toxic effect at a 450 mg/m3 concentration a more pronounced effect on both mothers and fetuses. The toxic effects were manifest as an increase in maternal mortality, circulatory damage, decreased gain in body weight, decrease in the weight of the placenta in the mothers and an increase in mortality (early and late), retardation of development (weight and skeleton) in the fetuses. No further change in the parameters was seen with further increases in benzene concentration. Avoidance of the risks of benzene exposure seems desirable before the commencement of planned pregnancy in the human.

  11. Electrokinetic Properties of the Pristine and Oxidized MWCNT Depending on the Electrolyte Type and Concentration

    Science.gov (United States)

    Skwarek, Ewa; Bolbukh, Yuliia; Tertykh, Valentyn; Janusz, Władysław

    2016-03-01

    Electrostatic stabilization is reduced in its efficiency in an electrolyte-containing environment. The effect of electrolyte concentration is mostly described as negative factor for dispersion stabilization. Usually, zeta potential and physical stability decrease at increasing electrolyte concentration. The purpose of the present study was to measure the surface properties of nanotubes in aqueous solution of monovalent electrolytes at different concentration. Characteristics such as size distribution, surface chemistry, surface charge, and dispersability in aqueous phase have been identified. Hydrodynamic size and zeta potential in aqueous multiwalled carbon nanotube (MWCNT) suspensions were determined at different pH with the desired concentrations of electrolyte of the cationic group (NaCl, KCl, CsCl) and the anionic group (NaClO4). The correlations between the response of the surface functionality of pristine and oxidized multiwalled carbon nanotubes and electrical double layer (EDL) forming at different ionic environments in the vicinity of a nanotube surface were determined. The nanotube dispersion stabilization was found to be more affected by ion size and pH medium then electrolyte concentration. The data obtained confirms the predominant role of surface reactions. The most stable dispersion of nanotubes was achieved in KCl electrolyte solution at less negative charge of the surface.

  12. Dependence of ion concentration in simulated body fluid on apatite precipitation on titania surface

    Science.gov (United States)

    Sakaguchi, Akira; Nakano, Masayuki; Hieda, Junko; Ohtake, Naoto; Akasaka, Hiroki

    2015-08-01

    Titanium and its alloys are used as biomaterials, because of their high biocompatibility. Apatite precipitates on a titania surface in vivo, and living bone and titanium alloy are coupled through the thin apatite layer. The initial precipitation behavior of apatite on titania in simulated body fluid (SBF) solutions was evaluated and the effect of inorganic ions in the SBF was investigated. Measurement using the SPR phenomenon was used to evaluate the initial apatite precipitation. An SBF containing approximately equal ion concentrations to those in blood plasma was added to a titania surface and the SPR profile was obtained, from which the initial apatite precipitation rate was found to be 1.14 nm/h. Furthermore, the relationship between the inorganic concentration and the precipitation rate was determined for SBFs with different Na+ and Ca2+ concentrations. Apatite precipitation did not occur in the SBF with a low Na+ concentration, whereas the initial apatite precipitation rate in the SBF that did not contain Ca2+ was 0.32 nm/h. According to these results, Ca2+ has little effect on the initial apatite precipitation. In the initial reaction of apatite precipitation, sodium titanate is formed by the absorption of Na+. Next, calcium titanate precipitates upon the substitution of Na+ with Ca2+. Finally, Na+, phosphate ions and hydroxyl ions are attracted to the surface and apatite is formed. Thus, the rate-limiting factor in the initial nucleation of apatite is the Na+ concentration.

  13. Concentration Dependence of VO2+ Crossover of Nafion for Vanadium Redox Flow Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Lawton, Jamie [University of Tennessee, Knoxville (UTK); Jones, Amanda [University of Tennessee, Knoxville (UTK); Zawodzinski, Thomas A [ORNL

    2013-01-01

    The VO2+ crossover, or permeability, through Nafion in a vanadium redox flow battery (VRFB) was monitored as a function of sulfuric acid concentration and VO2+ concentration. A vanadium rich solution was flowed on one side of the membrane through a flow field while symmetrically on the other side a blank or vanadium deficit solution was flowed. The blank solution was flowed through an electron paramagnetic resonance (EPR) cavity and the VO2+ concentration was determined from the intensity of the EPR signal. Concentration values were fit using a solution of Fick s law that allows for the effect of concentration change on the vanadium rich side. The fits resulted in permeability values of VO2+ ions across the membrane. Viscosity measurements of many VO2+ and H2SO4 solutions were made at 30 60 C. These viscosity values were then used to determine the effect of the viscosity of the flowing solution on the permeability of the ion. 2013 The Electrochemical Society. [DOI: 10.1149/2.004306jes] All rights reserved.

  14. The effect of concentration- and temperature-dependent dielectric constant on the activity coefficient of NaCl electrolyte solutions

    Energy Technology Data Exchange (ETDEWEB)

    Valiskó, Mónika; Boda, Dezső, E-mail: boda@almos.vein.hu [Department of Physical Chemistry, University of Pannonia, P.O. Box 158, H-8201 Veszprém (Hungary)

    2014-06-21

    Our implicit-solvent model for the estimation of the excess chemical potential (or, equivalently, the activity coefficient) of electrolytes is based on using a dielectric constant that depends on the thermodynamic state, namely, the temperature and concentration of the electrolyte, ε(c, T). As a consequence, the excess chemical potential is split into two terms corresponding to ion-ion (II) and ion-water (IW) interactions. The II term is obtained from computer simulation using the Primitive Model of electrolytes, while the IW term is estimated from the Born treatment. In our previous work [J. Vincze, M. Valiskó, and D. Boda, “The nonmonotonic concentration dependence of the mean activity coefficient of electrolytes is a result of a balance between solvation and ion-ion correlations,” J. Chem. Phys. 133, 154507 (2010)], we showed that the nonmonotonic concentration dependence of the activity coefficient can be reproduced qualitatively with this II+IW model without using any adjustable parameter. The Pauling radii were used in the calculation of the II term, while experimental solvation free energies were used in the calculation of the IW term. In this work, we analyze the effect of the parameters (dielectric constant, ionic radii, solvation free energy) on the concentration and temperature dependence of the mean activity coefficient of NaCl. We conclude that the II+IW model can explain the experimental behavior using a concentration-dependent dielectric constant and that we do not need the artificial concept of “solvated ionic radius” assumed by earlier studies.

  15. The effect of concentration- and temperature-dependent dielectric constant on the activity coefficient of NaCl electrolyte solutions.

    Science.gov (United States)

    Valiskó, Mónika; Boda, Dezső

    2014-06-21

    Our implicit-solvent model for the estimation of the excess chemical potential (or, equivalently, the activity coefficient) of electrolytes is based on using a dielectric constant that depends on the thermodynamic state, namely, the temperature and concentration of the electrolyte, ε(c, T). As a consequence, the excess chemical potential is split into two terms corresponding to ion-ion (II) and ion-water (IW) interactions. The II term is obtained from computer simulation using the Primitive Model of electrolytes, while the IW term is estimated from the Born treatment. In our previous work [J. Vincze, M. Valiskó, and D. Boda, "The nonmonotonic concentration dependence of the mean activity coefficient of electrolytes is a result of a balance between solvation and ion-ion correlations," J. Chem. Phys. 133, 154507 (2010)], we showed that the nonmonotonic concentration dependence of the activity coefficient can be reproduced qualitatively with this II+IW model without using any adjustable parameter. The Pauling radii were used in the calculation of the II term, while experimental solvation free energies were used in the calculation of the IW term. In this work, we analyze the effect of the parameters (dielectric constant, ionic radii, solvation free energy) on the concentration and temperature dependence of the mean activity coefficient of NaCl. We conclude that the II+IW model can explain the experimental behavior using a concentration-dependent dielectric constant and that we do not need the artificial concept of "solvated ionic radius" assumed by earlier studies.

  16. The dependence of equilibrium partition coefficient of cesium and iodine between sodium pool and the inert cover gas on the concentration in the pool

    Energy Technology Data Exchange (ETDEWEB)

    Miyahara, Shinya, E-mail: miyahara.shinya@jaea.go.jp [FBR Plant Engineering Center, Japan Atomic Energy Agency, 1 Shiraki, Tsuruga, Fukui 919-1279 (Japan); Research Institute of Nuclear Engineering, University of Fukui, 1-3-9 Bunkyo, Fukui 910-8507 (Japan); Nishimura, Masahiro, E-mail: nishimura.masahiro@jaea.go.jp [O-arai Research and Development Center, Japan Atomic Energy Agency, 4002 Narita, Oarai, Ibaraki 311-1393 (Japan); Nakagiri, Toshio, E-mail: nakagiri.toshio@jaea.go.jp [FBR Plant Engineering Center, Japan Atomic Energy Agency, 1 Shiraki, Tsuruga, Fukui 919-1279 (Japan)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer We measured equilibrium partition coefficients of cesium and iodine between liquid sodium pool and the inert cover gas. Black-Right-Pointing-Pointer The obtained empirical equations were consistent with Castleman's theoretical equations. Black-Right-Pointing-Pointer The effect of cesium concentration upon the partition coefficients was consistent with the theoretical values. Black-Right-Pointing-Pointer That of iodine concentration was incompatible with the theoretical consideration due to the formation of Na{sub 2}I{sub 2} in the cover gas. - Abstract: Equilibrium partition coefficients were experimentally measured for volatile fission products of cesium and iodine between liquid sodium pool and the inert cover gas. In the experiments, the 'transpiration method' was utilized in which the saturation vapor of sodium with cesium and iodine vapor in an isothermal evaporation pot was transported by inert carrier gas and trapped by filters outside the pot. The objectives of the experiments are to: (a)obtain the equilibrium partition coefficients of cesium and iodine at high temperature between 600 and 850 Degree-Sign C and, (b)study the dependence of the partition coefficients upon the concentration in the sodium pool. From the results of previous work and this study, the following empirical equations between the partition coefficients of cesium and iodine and the sodium pool temperature could be obtained: logKd(Cs)=(2173)/T -1.0487(from450to850 Degree-Sign C), logKd(I)=(-215)/T -0.271(from450to850 Degree-Sign C). These equations are consistent with Castleman's theoretical equations. The partition coefficients of cesium measured at five different points of mole concentration in the pool were almost consistent with the theoretical values and decreased with the increase in the concentration. On the other hand, the measured partition coefficients of iodine increased with the increase in the concentration in the

  17. Enhanced Removal of Biogenic Hydrocarbons in Power Plant Plumes Constrains the Dependence of Atmospheric Hydroxyl Concentrations on Nitrogen Oxides

    Science.gov (United States)

    De Gouw, J. A.; Trainer, M.; Parrish, D. D.; Brown, S. S.; Edwards, P.; Gilman, J.; Graus, M.; Hanisco, T. F.; Kaiser, J.; Keutsch, F. N.; Kim, S. W.; Lerner, B. M.; Neuman, J. A.; Pollack, I. B.; Roberts, J. M.; Ryerson, T. B.; Veres, P. R.; Warneke, C.; Wolfe, G.

    2015-12-01

    Hydroxyl (OH) radicals in the atmosphere provide one of the main chemical mechanisms for the removal of trace gases. OH plays a central role in determining the atmospheric lifetime and radiative forcing of greenhouse gases like methane. OH also plays a major role in the oxidation of organic trace gases, which can lead to formation of secondary pollutants such as ozone and PM2.5. Due to its very short atmospheric lifetime of seconds or less, OH concentrations are extremely variable in space and time, which makes measurements and their interpretation very challenging. Several recent measurements have yielded higher than expected OH concentrations. To explain these would require the existence of unidentified, radical recycling processes, but issues with the measurements themselves are also still being discussed. During the NOAA airborne SENEX study in the Southeast U.S., the biogenic hydrocarbons isoprene and monoterpenes were consistently found to have lower mixing ratios in air masses with enhanced nitrogen oxides from power plants. We attribute this to faster oxidation rates of biogenic hydrocarbons due to increased concentrations of OH in the power plant plumes. Measurements at different downwind distances from the Scherer and Harllee Branch coal-fired power plants near Atlanta are used to constrain the dependence of OH on nitrogen oxides. It is found that OH concentrations were highest at nitrogen dioxide concentrations of 1-2 ppbv and decreased at higher and at lower concentrations. These findings agree with the expected dependence of OH on nitrogen oxide concentrations, but do not appear to be consistent with the reports in the literature that have shown high OH concentrations in regions of the atmosphere with high biogenic emissions and low NOx concentrations that would require unidentified radical recycling processes to be explained.

  18. Ionic relaxation in PEO/PVDF-HFP-LiClO4 blend polymer electrolytes: dependence on salt concentration

    Science.gov (United States)

    Das, S.; Ghosh, A.

    2016-06-01

    In this paper, we have studied the effect of LiClO4 salt concentration on the ionic conduction and relaxation in poly ethylene oxide (PEO) and poly (vinylidene fluoride hexafluoropropylene) (PVDF-HFP) blend polymer electrolytes, in which the molar ratio of ethylene oxide segments to lithium ions (R  =  EO: Li) has been varied between 3 and 35. We have observed two phases in the samples containing low salt concentrations (R  >  9) and single phase in the samples containing high salt concentrations (R  ⩽  9). The scanning electron microscopic images indicate that there exists no phase separation in the blend polymer electrolytes. The temperature dependence of the ionic conductivity shows two slopes corresponding to high and low temperatures and follows Arrhenius relation for the samples containing low salt concentrations (R  >  9). The conductivity relaxation as well as the structural relaxation has been clearly observed at around 104 Hz and 106 Hz for these concentrations of the blended electrolytes. However, a single conductivity relaxation peak has been observed for the compositions with R  ⩽  9. The scaling of the conductivity spectra shows that the relaxation mechanism is independent of temperature, but depends on salt concentration.

  19. Concentration-Dependent Dual Role of Thrombin In Protection of Cultured Rat Cortical Neurons

    Science.gov (United States)

    García, Paul S.; Ciavatta, Vincent T.; Fidler, Jonathan A.; Woodbury, Anna; Levy, Jerrold H.; Tyor, William R.

    2015-01-01

    Background Thrombin’s role in the nervous system is not well understood. Under conditions of blood-brain barrier compromise (e.g., neurosurgery or stroke), thrombin can result in neuroapoptosis and the formation of glial scars. Despite this, preconditioning with thrombin has been found to be neuroprotective in models of cerebral ischemia and intracerebral hemorrhage. Methods We investigated the effects of physiologically relevant concentrations of thrombin on cortical neurons using two culture-based assays. We examined thrombin’s effect on neurites by quantitative analysis of fluorescently labeled neurons. To characterize thrombin’s effects on neuron survival, we spectrophotometrically measured changes in enzymatic activity. Using receptor agonists and thrombin inhibitors, we separately examined the role of thrombin and its receptor in neuroprotection. Results We found that low concentrations of thrombin (1 nM) enhances neurite growth and branching, neuron viability, and protects against excitotoxic damage. In contrast, higher concentrations of thrombin (100 nM) are potentially detrimental to neuronal health as evidenced by inhibition of neurite growth. Lower concentrations of thrombin resulted in equivalent neuroprotection as the antifibrinolytic, aprotinin, and the direct thrombin inhibitor, argatroban. Interestingly, exogenous application of the species-specific thrombin inhibitor, antithrombin III, was detrimental to neuronal health; suggesting that some endogenous thrombin is necessary for optimal neuron health in our culture system. Activation of the thrombin receptor, protease-activated receptor - 1 (PAR-1), via micromolar concentrations of the thrombin receptor agonist peptide, TRAP, did not adversely affect neuronal viability. Conclusions An optimal concentration of thrombin exists to enhance neuronal health. Neurotoxic effects of thrombin do not involve activation of PAR receptors and thus separate pharmacologic manipulation of thrombin’s receptor

  20. A kinetic model for evaluating the dependence of the quantum yield of nano-TiO{sub 2} based photocatalysis on light intensity, grain size, carrier lifetime, and minority carrier diffusion coefficient: Indirect interfacial charge transfer

    Energy Technology Data Exchange (ETDEWEB)

    Liu Baoshun, E-mail: liubaoshun@126.co [Key Laboratory of Silicate Materials Science and Engineering, Ministry of Education, Wuhan, Hubei 430070 (China) and School of Material Science and Technology, Wuhan University of Technology, Wuhan, Hubei 430070 (China); Zhao Xiujian [Key Laboratory of Silicate Materials Science and Engineering, Ministry of Education, Wuhan, Hubei 430070 (China)

    2010-04-30

    A model based on spherical TiO{sub 2} nanoparticles was developed to study heterogeneous photocatalysis based on TiO{sub 2} in the case of indirect interfacial charge transfer. In this model, the effect of light intensity (I{sub 0}), grain size (r{sub 0}), carrier lifetime (tau{sub p}), and minority carrier diffusion coefficient (D{sub p}) on the quantum yield (QY) of photocatalytic reactions was investigated in detail. Under conditions of sufficiently low incident-light intensity, the QY was found to be propor toI{sub 0}, while it decreased rapidly with an increase in I{sub 0}. In addition, the QY went to zero at a critically high light intensity. Furthermore, the QY was found to decrease with increasing r{sub 0} due to the bulk-recombination loss, and the effect of r{sub 0} on the QY became increasingly stronger with the increase in I{sub 0}. The QY decreased with the decrease in tau{sub p} and D{sub p}, which was more apparent at the critically high I{sub 0}. Under conditions of low [(RH{sub 2}){sub aq}], the QY increased with an increase in [(RH{sub 2}){sub aq}], while it remained nearly constant at high [(RH{sub 2}){sub aq}] due to the fact that the photoinduced electron interfacial transfer became the limiting step for photocatalytic reactions in the case of high [(RH{sub 2}){sub aq}].

  1. Time-dependent Taylor–Aris dispersion of an initial point concentration

    DEFF Research Database (Denmark)

    Vedel, Søren; Hovad, Emil; Bruus, Henrik

    2014-01-01

    -specific theoretical results, and furthermore predict new phenomena. In particular, for the transient phase before the well-described steady Taylor–Aris limit is reached, we find anomalous diffusion with a dependence of the temporal scaling exponent on the initial release point, generalizing this finding in specific...... cases. During this transient we furthermore identify maxima in the values of the dispersion coefficient which exceed the Taylor–Aris value by amounts that depend on channel geometry, initial point release position, velocity profile and Péclet number. We show that these effects are caused by a difference...

  2. Assessment of regional air quality by a concentration-dependent Pollution Permeation Index

    Science.gov (United States)

    Liang, Chun-Sheng; Liu, Huan; He, Ke-Bin; Ma, Yong-Liang

    2016-10-01

    Although air quality monitoring networks have been greatly improved, interpreting their expanding data in both simple and efficient ways remains challenging. Therefore, needed are new analytical methods. We developed such a method based on the comparison of pollutant concentrations between target and circum areas (circum comparison for short), and tested its applications by assessing the air pollution in Jing-Jin-Ji, Yangtze River Delta, Pearl River Delta and Cheng-Yu, China during 2015. We found the circum comparison can instantly judge whether a city is a pollution permeation donor or a pollution permeation receptor by a Pollution Permeation Index (PPI). Furthermore, a PPI-related estimated concentration (original concentration plus halved average concentration difference) can be used to identify some overestimations and underestimations. Besides, it can help explain pollution process (e.g., Beijing’s PM2.5 maybe largely promoted by non-local SO2) though not aiming at it. Moreover, it is applicable to any region, easy-to-handle, and able to boost more new analytical methods. These advantages, despite its disadvantages in considering the whole process jointly influenced by complex physical and chemical factors, demonstrate that the PPI based circum comparison can be efficiently used in assessing air pollution by yielding instructive results, without the absolute need for complex operations.

  3. A simple relation for the concentration dependence of osmotic pressure and depletion thickness in polymer solutions

    NARCIS (Netherlands)

    Fleer, G.J.; Skvortsov, A.M.; Tuinier, R.

    2007-01-01

    We propose simple expressions II/IIo = 1 + and (omega/omega(ex))(3 alpha-1) and (delta(0)/delta)(2) = 1 + (omega/omega(ex))(2 alpha) for the osmotic pressure II and the depletion thickness 6 as a function of the polymer concentration omega. Here, IIo and delta 0 correspond to the dilute limit, and o

  4. Concentration-dependency of beta-lactam-induced filament formation in Gram-negative bacteria.

    NARCIS (Netherlands)

    Buijs, J.; Dofferhoff, A.S.M.; Mouton, J.W.; Wagenvoort, J.H.T.; Meer, J.W.M. van der

    2008-01-01

    Ceftazidime and cefotaxime are beta-lactam antibiotics with dose-related affinities for penicillin-binding protein (PBP)-3 and PBP-1. At low concentrations, these antibiotics inhibit PBP-3, leading to filament formation. Filaments are long strands of non-dividing bacteria that contain enhanced quant

  5. Bioluminescence in Dinoflagellates: Evidence that the Adaptive Value of Bioluminescence in Dinoflagellates is Concentration Dependent.

    Science.gov (United States)

    Hanley, Karen A; Widder, Edith A

    2017-03-01

    Three major hypotheses have been proposed to explain why dinoflagellate bioluminescence deters copepod grazing: startle response, aposematic warning, and burglar alarm. These hypotheses propose dinoflagellate bioluminescence (A) startles predatory copepods, (B) warns potential predators of toxicity, and (C) draws the attention of higher order visual predators to the copepod's location. While the burglar alarm is the most commonly accepted hypothesis, it requires a high concentration of bioluminescent dinoflagellates to be effective, meaning the bioluminescence selective advantage at lower, more commonly observed, dinoflagellate concentrations may result from another function (e.g. startle response or aposematic warning). Therefore, a series of experiments was conducted to evaluate copepod grazing (Acartia tonsa) on bioluminescent dinoflagellates (during bioluminescent and nonbioluminescent phases, corresponding to night and day, respectively) at different concentrations (10, 1000, and 3000 cells mL(-1) ), on toxic (Pyrodinium bahamense var. bahamense) and nontoxic (Lingulodinium polyedrum) bioluminescent dinoflagellates, and in the presence of nonluminescent diatoms (Thalassiosira eccentrica). Changes in copepod ingestion rates, clearance rates, and feeding preferences as a result of these experimental factors, particularly during the mixed trails with nonluminescent diatoms, indicate there is a concentration threshold at which the burglar alarm becomes effective and below which dinoflagellate bioluminescence functions as an aposematic warning.

  6. A simple relation for the concentration dependence of osmotic pressure and depletion thickness in polymer solutions

    NARCIS (Netherlands)

    Fleer, G.J.; Skvortsov, A.M.; Tuinier, R.

    2007-01-01

    We propose simple expressions II/IIo = 1 + and (omega/omega(ex))(3 alpha-1) and (delta(0)/delta)(2) = 1 + (omega/omega(ex))(2 alpha) for the osmotic pressure II and the depletion thickness 6 as a function of the polymer concentration omega. Here, IIo and delta 0 correspond to the dilute limit, and

  7. Concentration-Dependant Changes of PCB Patterns in Fish-Eating Mammals

    DEFF Research Database (Denmark)

    Boon, J.P.; van der Meer, J.; Allchin, C.R.

    1997-01-01

    Data sets on CB concentrations in fish-eating mammals from five laboratories were combined to test and refine a pharmacokinetic model. Clear differences in PCB patterns were observed between species, The ability to metabolize chlorobiphenyl (CB) congeners with vicinal H-atoms only in the ortho...

  8. Dependence of Shear and Concentration on Fouling in a Membrane Bioreactor with Rotating Membrane Discs

    DEFF Research Database (Denmark)

    Jørgensen, Mads Koustrup; Pedersen, Malene Thostrup; Christensen, Morten Lykkegaard

    2014-01-01

    of shear stress and sludge concentration on the limiting flux. The model was developed by calculating the shear rate at laminar flow regime at different rotation speeds and radii on the membrane. Furthermore, through the shear rate and shear stress, the non-Newtonian behavior of MBR sludge was addressed...

  9. Reduced cooperativeness and reward-dependence in depression with above-normal plasma vasopressin concentration

    NARCIS (Netherlands)

    Goekoop, J. G.; de Winter, R. F. P.; Wolterbeek, R.; Spinhoven, P.; Zitman, F. G.; Wiegant, V. M.

    2009-01-01

    The neuropeptide vasopressin is centrally involved in the regulation of social behaviour and response to stress. We previously found support for a subcategory of depression defined by above-normal plasma vasopressin (AVP) concentration. This subcategory is validated by a positive family history of d

  10. A simple relation for the concentration dependence of osmotic pressure and depletion thickness in polymer solutions

    NARCIS (Netherlands)

    Fleer, G.J.; Skvortsov, A.M.; Tuinier, R.

    2007-01-01

    We propose simple expressions II/IIo = 1 + and (omega/omega(ex))(3 alpha-1) and (delta(0)/delta)(2) = 1 + (omega/omega(ex))(2 alpha) for the osmotic pressure II and the depletion thickness 6 as a function of the polymer concentration omega. Here, IIo and delta 0 correspond to the dilute limit, and o

  11. Investigation of temperature-dependent asymmetric degradation behavior induced by hot carrier effect in oxygen ambiance in In–Ga–Zn-O thin film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Bo-Wei [Department of Photonics, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Chang, Ting-Chang [Department of Physics, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China); Advanced Optoelectronics Technology Center, National Cheng Kung University, Taiwan (China); Hung, Yu-Ju [Department of Photonics, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Hsieh, Tien-Yu [Department of Physics, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China); Tsai, Ming-Yen [Department of Photonics, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Liao, Po-Yung [Department of Physics, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China); Tsai, Wu-Wei; Chiang, Wen-Jen; Yan, Jing-Yi [Industrial Technology Research Institute, 195, Sec. 4, Chung Hsing Rd., Hsinchu, 31040, Taiwan (China)

    2014-12-01

    The effects of oxygen ambiance on electrical characteristic degradation phenomena in a-InGaZnO thin film transistor with different biases and temperatures are investigated. It can be found that oxygen is substantially adsorbed on the backchannel and results in device instabilities during positive gate bias stress. However, visible light irradiation is found to desorb the adsorbed oxygen ions and this verifies that oxygen dominates the degradation behavior. Moreover, comparing with that in vacuum, hot-carrier stress in oxygen ambiance leads to an extra potential barrier height near the drain side due to oxygen adsorption and causes asymmetric degradation. Furthermore, the asymmetric degradation behavior after hot-carrier stress in oxygen ambiance is suppressed at high temperature due to temperature-induced oxygen desorption or heat-induced holes injecting into the gate insulator. - Highlights: • Oxygen adsorbing will occur beneath the active layer under persistent positive gate bias. • Oxygen desorbing under illumination was verified from the recovery of transfer curves. • Additional barrier height is generated after hot-carrier stress because of oxygen adsorption. • The amount of hot-carrier degradation in oxygen ambience will decrease as temperature elevating.

  12. Analytic 1D pn junction diode photocurrent solutions following ionizing radiation and including time-dependent changes in the carrier lifetime.

    Energy Technology Data Exchange (ETDEWEB)

    Axness, Carl L.; Keiter, Eric Richard; Kerr, Bert (New Mexico Tech, Socorro, NM)

    2011-04-01

    Circuit simulation tools (e.g., SPICE) have become invaluable in the development and design of electronic circuits in radiation environments. These codes are often employed to study the effect of many thousands of devices under transient current conditions. Device-scale simulation tools (e.g., MEDICI) are commonly used in the design of individual semiconductor components, but require computing resources that make their incorporation into a circuit code impossible for large-scale circuits. Analytic solutions to the ambipolar diffusion equation, an approximation to the carrier transport equations, may be used to characterize the transient currents at nodes within a circuit simulator. We present new transient 1D excess carrier density and photocurrent density solutions to the ambipolar diffusion equation for low-level radiation pulses that take into account a finite device geometry, ohmic fields outside the depleted region, and an arbitrary change in the carrier lifetime due to neutron irradiation or other effects. The solutions are specifically evaluated for the case of an abrupt change in the carrier lifetime during or after, a step, square, or piecewise linear radiation pulse. Noting slow convergence of the raw Fourier series for certain parameter sets, we use closed-form formulas for some of the infinite sums to produce 'partial closed-form' solutions for the above three cases. These 'partial closed-form' solutions converge with only a few tens of terms, which enables efficient large-scale circuit simulations.

  13. Adjuvant and carrier protein-dependent T-cell priming promotes a robust antibody response against the Plasmodium falciparum Pfs25 vaccine candidate

    Science.gov (United States)

    Radtke, Andrea J.; Anderson, Charles F.; Riteau, Nicolas; Rausch, Kelly; Scaria, Puthupparampil; Kelnhofer, Emily R.; Howard, Randall F.; Sher, Alan; Germain, Ronald N.; Duffy, Patrick

    2017-01-01

    Humoral immune responses have the potential to maintain protective antibody levels for years due to the immunoglobulin-secreting activity of long-lived plasma cells (LLPCs). However, many subunit vaccines under development fail to generate robust LLPC responses, and therefore a variety of strategies are being employed to overcome this limitation, including conjugation to carrier proteins and/or formulation with potent adjuvants. Pfs25, an antigen expressed on malaria zygotes and ookinetes, is a leading transmission blocking vaccine (TBV) candidate for Plasmodium falciparum. Currently, the conjugate vaccine Pfs25-EPA/Alhydrogel is in Phase 1 clinical trials in the USA and Africa. Thus far, it has proven to be safe and immunogenic, but it is expected that a more potent formulation will be required to establish antibody titers that persist for several malaria transmission seasons. We sought to determine the contribution of carrier determinants and adjuvants in promoting high-titer, long-lived antibody responses against Pfs25. We found that both adjuvants and carrier proteins influence the magnitude and capacity of Pfs25-specific humoral responses to remain above a protective level. Furthermore, a liposomal adjuvant with QS21 and a TLR4 agonist (GLA-LSQ) was especially effective at inducing T follicular helper (Tfh) and LLPC responses to Pfs25 when coupled to immunogenic carrier proteins. PMID:28091576

  14. Serum concentrations of cortisol and cortisone in healthy dogs and dogs with pituitary-dependent hyperadrenocorticism treated with trilostane.

    Science.gov (United States)

    Sieber-Ruckstuhl, N S; Boretti, F S; Wenger, M; Maser-Gluth, C; Reusch, C E

    2008-10-18

    The serum concentrations of cortisol and cortisone were measured in 19 healthy dogs and in 13 dogs with pituitary-dependent hyperadrenocorticism (PDH) before and one hour after an injection of synthetic adrenocorticotropic hormone (ACTH). In the dogs with pdh, the cortisol and cortisone concentrations were measured before and after one to two weeks and three to seven weeks of treatment with trilostane. The dogs with PDH had significantly higher baseline and poststimulation concentrations of cortisol and cortisone, and higher baseline cortisol:cortisone ratios than the healthy dogs. During the treatment with trilostane, the poststimulation cortisol, the baseline and poststimulation cortisone concentrations, and the baseline and poststimulation cortisol:cortisone ratios decreased significantly. The decrease in poststimulation cortisone was significantly smaller than the decrease in cortisol.

  15. Concentration Dependent Influence of Lipopolysaccharides on Separation of Hoof Explants and Supernatant Lactic Acid Concentration in an Ex Vivo/In Vitro Laminitis Model.

    Science.gov (United States)

    Reisinger, Nicole; Schaumberger, Simone; Nagl, Veronika; Hessenberger, Sabine; Schatzmayr, Gerd

    2015-01-01

    Laminitis is one of the most common diseases in horses. It is not only painful for the animal, but also has a significant financial impact on the equine industry. This multifactorial disease affects the connective tissue of the hoof. However, the pathogenesis of laminitis is still not fully understood. Endotoxins, also known as lipopolysaccharides (LPS), and bacterial exotoxins seem to play an important role during the development of laminitis. The aim of our study was to investigate the effect of increasing LPS concentrations (0, 2.5, 5, 10, and 100 μg/mL) on cell viability of isolated epidermal and dermal hoof cells as well as on the tissue integrity of hoof explants. Furthermore, glucose, acetic acid, lactic acid, and propionic acid concentrations in explant supernatants were measured to evaluate the energy metabolism in the hoof tissue. LPS did not exhibit cytotoxic effects on epidermal or dermal cells. Force required to separate LPS treated hoof explants decreased in a concentration dependent manner. Specifically, explants incubated with 10 and 100 μg/mL needed significantly less force to separate compared to control explants. Lactic acid concentrations were significantly decreased in explants incubated with 5, 10, or 100 μg/mL LPS, while glucose, acetic acid and propionic acid concentrations were unaffected by LPS treatment. Our study indicates that LPS has no cytotoxic effect on epidermal and dermal cells isolated from hoof tissue, but impairs integrity of hoof explants. In addition, LPS led to an alteration of the lactic acid production in the lamellar tissue. Since our data highlight that LPS can affect the integrity of the equine hoof tissue in vitro, endotoxins should be further explored for their contribution to facilitate the development of laminitis.

  16. Concentration Dependent Influence of Lipopolysaccharides on Separation of Hoof Explants and Supernatant Lactic Acid Concentration in an Ex Vivo/In Vitro Laminitis Model.

    Directory of Open Access Journals (Sweden)

    Nicole Reisinger

    Full Text Available Laminitis is one of the most common diseases in horses. It is not only painful for the animal, but also has a significant financial impact on the equine industry. This multifactorial disease affects the connective tissue of the hoof. However, the pathogenesis of laminitis is still not fully understood. Endotoxins, also known as lipopolysaccharides (LPS, and bacterial exotoxins seem to play an important role during the development of laminitis. The aim of our study was to investigate the effect of increasing LPS concentrations (0, 2.5, 5, 10, and 100 μg/mL on cell viability of isolated epidermal and dermal hoof cells as well as on the tissue integrity of hoof explants. Furthermore, glucose, acetic acid, lactic acid, and propionic acid concentrations in explant supernatants were measured to evaluate the energy metabolism in the hoof tissue. LPS did not exhibit cytotoxic effects on epidermal or dermal cells. Force required to separate LPS treated hoof explants decreased in a concentration dependent manner. Specifically, explants incubated with 10 and 100 μg/mL needed significantly less force to separate compared to control explants. Lactic acid concentrations were significantly decreased in explants incubated with 5, 10, or 100 μg/mL LPS, while glucose, acetic acid and propionic acid concentrations were unaffected by LPS treatment. Our study indicates that LPS has no cytotoxic effect on epidermal and dermal cells isolated from hoof tissue, but impairs integrity of hoof explants. In addition, LPS led to an alteration of the lactic acid production in the lamellar tissue. Since our data highlight that LPS can affect the integrity of the equine hoof tissue in vitro, endotoxins should be further explored for their contribution to facilitate the development of laminitis.

  17. Concentration-dependent enantioselective transport of chiral timolol maleate across hairless mice skin upon using various concentrations of chiral terpene enhancer (D-Limonene.

    Directory of Open Access Journals (Sweden)

    Mohsen I. Afouna

    2013-12-01

    Full Text Available The objective of the present study was to examine the relationship between different concentrations of the chiral enhancer D- Limonene (D-LM on the solubility of individual enantiomers and racemate Timolol maleate (TM The preferential improvement of D-LM on S-TM, R-TM, and racemate transported across the hairless mice skin was also investigated. For solubility studies, excess of R-, S-, or racemate with different concentrations of D-LM were prepared. The samples were agitated, centrifuged, filtered and analyzed using HPLC with a chiral column at a wavelength of 294 nm. For skin transport studies, formulations containing 0.5% solutions of S-TM, R-TM, or racemate in a buffer solution with predetermined concentrations of D-LM were studied. Samples of 1 ml were withdrawn and quantitatively analyzed for their TM contents. Steady-state fluxes (Jss, permeability coefficients and the enhancement factor were calculated. The studies showed that D-LM significantly increased the solubility of the enantiomeric, as well as, the racemate forms of TM in a concentration dependent manner. The permeation studies showed that the presence of D-LM significantly increased the flux values of both enantiomers and racemate. However, D-LM preferentially increased the permeability characteristics of the S-isomer compared to those of the R-isomer. Solubilities of the enantiomeric and the racemate forms of TM were found to be a single-valued function of D-LM concentration. Moreover, the addition of D-LM increased the transport of the S-TM, R-TM enantiomers and the racemate across the hairless mice skin. In conclusion, all the tested formulations, the overall permeability characteristics of the therapeutically active TM (i.e., S-TM proved to be superior to those obtained with the R-TM either as enantiomer or racemate

  18. Thermoelectric power and carrier concentration ofLa2-xSrxCuO4(0.03<x<0.17)single crystals

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Thermoelectric power (S) measurements have been systematically investigated in high-quality La2-x-Srx-CuO4 single crystals with different Sr concentrations (x =0.03, 0.05, 0.07, 0.1, 0.12). In this doping range studied, S remains positive, and with the increase of Sr concentration,room-temperature thermoelectric power S (290 K) decreases.An empirical formula which presents a relationship between hole concentration P and room-temperature thermoelectric power S (290 K) is reported in this note. Based on the theory of metallic diffusion model, the experimental results are discussed.

  19. Is bile salt-dependent lipase concentration in serum of any help in pancreatic cancer diagnosis?

    Science.gov (United States)

    Lombardo, D; Montalto, G; Roudani, S; Mas, E; Laugier, R; Sbarra, V; Abouakil, N

    1993-09-01

    The diagnostic value of bile salt-dependent lipase for pancreatic diseases was tested in sera of 187 patients. Of these patients, 76 suffered from pancreatic carcinoma, 43 from nonmalignant liver diseases (cirrhosis and chronic hepatitis), 18 from acute pancreatitis, and 20 from chronic pancreatitis. The remaining subjects were controls without pancreatic pathology. Bile salt-dependent lipase was determined by a sandwich enzyme-linked immunosorbent assay using polyclonal antibodies. Amylase and CA 19-9 antigen were also determined. In sera from control patients, the mean level of bile salt-dependent lipase was 1.5 micrograms/L. This level is quite similar to that of patients with benign liver diseases (1.1 micrograms/L) and with chronic pancreatitis (1.4 micrograms/L), but it was raised to 3.5 micrograms/L in patients with acute pancreatitis and decreased to 0.5 microgram/L in subjects with pancreatic adenocarcinoma. Thirty percent of control subjects and 73% of cancer patients had a bile salt-dependent lipase serum level below the cutoff value of 0.5 microgram/L. In acute pancreatitis, 11 of 16 subjects had levels above 1.5 micrograms/L. Amylase level largely increased in acute pancreatitis but was normal in all other groups. Concerning CA 19-9 antigen, 65% of control patients and > 80% of patients with nonmalignant pancreatic or liver diseases had normal levels. In sera from cancer patients, 80% presented with high levels. Accordingly, 36 of 38 patients with pancreatic cancer had either low serum levels of bile salt-dependent lipase ( 37 U/ml; sensitivity 95%).(ABSTRACT TRUNCATED AT 250 WORDS)

  20. The Role of Concentration Dependent Static Permittivity of Electrolyte Solutions in the Debye-Hückel Theory.

    Science.gov (United States)

    Shilov, Ignat Yu; Lyashchenko, Andrey K

    2015-08-01

    The Debye-Hückel theory has been extended to allow for arbitrary concentration dependence of the electrolyte solution static permittivity. The theory follows the lines advanced by Erich Hückel ( Hückel, E. Phys. Z. 1925, 26, 93) but gives rise to more general and lucid results. New theoretical expressions have been obtained for the excess free energy of solution, activity coefficient of water and mean ionic activity coefficient. The thermodynamic functions contain two terms representing interionic interactions and ion-water (solvation) interactions. The theory has been applied to calculate the activity coefficients of components in the aqueous solutions of alkali metal chlorides from LiCl to CsCl at ambient conditions making use of permittivities taken from experimental dielectric relaxation studies. Calculations without parameter adjustment have demonstrated a semiquantitative agreement with experimental data, reproducing both the nonmonotonic concentration dependence of the activity coefficients and the ordering of activity coefficients for the salts with different cations. A good agreement with experimental data is obtained for the aqueous solutions of LiCl in the concentration range up to 10 mol/kg. The nonmonotonic concentration dependence of activity coefficients is explained as a result of a balance between the effect of interionic interactions and the solvation contribution which appears quite naturally in the framework of the Debye-Hückel approach after incorporation of variable permittivity of solution.

  1. Hydrogen carriers

    Science.gov (United States)

    He, Teng; Pachfule, Pradip; Wu, Hui; Xu, Qiang; Chen, Ping

    2016-12-01

    Hydrogen has the potential to be a major energy vector in a renewable and sustainable future energy mix. The efficient production, storage and delivery of hydrogen are key technical issues that require improvement before its potential can be realized. In this Review, we focus on recent advances in materials development for on-board hydrogen storage. We highlight the strategic design and optimization of hydrides of light-weight elements (for example, boron, nitrogen and carbon) and physisorbents (for example, metal-organic and covalent organic frameworks). Furthermore, hydrogen carriers (for example, NH3, CH3OH-H2O and cycloalkanes) for large-scale distribution and for on-site hydrogen generation are discussed with an emphasis on dehydrogenation catalysts.

  2. Temperature-dependent accumulation mode particle and cloud nuclei concentrations from biogenic sources during WACS 2010

    Directory of Open Access Journals (Sweden)

    L. Ahlm

    2012-10-01

    Full Text Available Submicron aerosol particles collected simultaneously at the mountain peak (2182 m a.s.l. and at a forested mid-mountain site (1300 m a.s.l. on Whistler Mountain, British Columbia, Canada, during June and July 2010 were analyzed by Fourier transform infrared (FTIR spectroscopy for quantification of organic functional groups. Positive matrix factorization (PMF was applied to the FTIR spectra. Three PMF factors associated with (1 combustion, (2 biogenics, and (3 vegetative detritus, were identified at both sites. The biogenic factor was correlated with both temperature and several volatile organic compounds (VOCs. The combustion factor dominated the submicron particle mass during the beginning of the campaign when the temperature was lower and advection was from the Vancouver area, but as the temperature started to rise in early July the biogenic factor came to dominate as a result of increased emissions of biogenic VOCs and thereby increased formation of secondary organic aerosol (SOA. On average, the biogenic factor represented 69% and 49% of the submicron organic particle mass at Whistler Peak and at the mid-mountain site, respectively. The lower fraction at the mid-mountain site was a result of more vegetative detritus there, and also higher influence from local combustion sources.

    The biogenic factor was strongly correlated (r ~ 0.9 to number concentration of particles with diameter (Dp> 100 nm, whereas the combustion factor was better correlated to number concentration of particles with Dp < 100 nm (r~ 0.4. The number concentration of cloud condensation nuclei (CCN was correlated (r ~ 0.7 to the biogenic factor for supersaturations (S of 0.2% or higher, which indicates that particle condensational growth from biogenic vapors was an important factor in controlling the CCN concentration for clouds where S≥0.2%. Both the number concentration of particles with

  3. Temperature-dependent accumulation mode particle and cloud nuclei concentrations from biogenic sources during WACS 2010

    Directory of Open Access Journals (Sweden)

    L. Ahlm

    2013-03-01

    Full Text Available Submicron aerosol particles collected simultaneously at the mountain peak (2182 m a.s.l. and at a forested mid-mountain site (1300 m a.s.l. on Whistler Mountain, British Columbia, Canada, during June and July 2010 were analyzed by Fourier transform infrared (FTIR spectroscopy for quantification of organic functional groups. Positive matrix factorization (PMF was applied to the FTIR spectra. Three PMF factors associated with (1 combustion, (2 biogenics, and (3 vegetative detritus were identified at both sites. The biogenic factor was correlated with both temperature and several volatile organic compounds (VOCs. The combustion factor dominated the submicron particle mass during the beginning of the campaign, when the temperature was lower and advection was from the Vancouver area, but as the temperature started to rise in early July, the biogenic factor came to dominate as a result of increased emissions of biogenic VOCs, and thereby increased formation of secondary organic aerosol (SOA. On average, the biogenic factor represented 69% and 49% of the submicron organic particle mass at Whistler Peak and at the mid-mountain site, respectively. The lower fraction at the mid-mountain site was a result of more vegetative detritus there, and also higher influence from local combustion sources. The biogenic factor was strongly correlated (r~0.9 to number concentration of particles with diameter (Dp> 100 nm, whereas the combustion factor was better correlated to number concentration of particles with Dpr~0.4. The number concentration of cloud condensation nuclei (CCN was correlated (r~0.7 to the biogenic factor for supersaturations (S of 0.2% or higher, which indicates that particle condensational growth from biogenic vapors was an important factor in controlling the CCN concentration for clouds where S≥0.2%. Both the number concentration of particles with Dp>100 nm and numbers of CCN for S≥0.2% were correlated to temperature. Considering the biogenic

  4. Analytical model of photon reabsorption in ZnO quantum dots with size and concentration dependent dual-color photoluminescence

    Science.gov (United States)

    Fan, Baolu; Guo, Xiaoxiao; Zhang, Yumeng; Fan, Jiyang

    2017-02-01

    We investigate the concentration and size dependent UV/green photoluminescence properties of the ZnO quantum dots (QDs) with sizes in the strong confinement regime. The luminescence characteristics of an ensemble of colloidal semiconductor QDs with quantum confinement effect depend sensitively on particle concentration but this has only been qualitatively understood. By taking ZnO QDs as an ideal prototype, we construct a material-independent theoretical model to study the photon reabsorption phenomenon. The theoretical result agrees well with the experiment. This model can be used to quantitatively study the concentration-dependent luminescence properties of any collection of QDs with considerable size dispersion. On the other hand, the origin of green emission in ZnO QDs remains debated. The comparative study of the size dependence of UV and green emissions in conjunction with the effective-mass approximation calculation suggests that the green emission in the ZnO QDs originates from the conduction band to the deep level transition.

  5. Prostasin-dependent activation of epithelial Na+ channels by low plasmin concentrations

    DEFF Research Database (Denmark)

    Svenningsen, Per; Uhrenholt, Torben R; Palarasah, Yaseelan;

    2009-01-01

    plasmin-stimulated ENaC current in single M-1 cells, as measured by whole-cell patch clamp. In M-1 cells expressing heterologous FLAG-tagged prostasin, gammaENaC and prostasin were colocalized. A monoclonal antibody directed against the inhibitory peptide of gammaENaC produced specific immunofluorescence...... plasmin-stimulated ENaC current in monolayers of M-1 cells at low plasmin concentration (1-4 microg/ml). At a high plasmin concentration of 30 microg/ml, there was no difference between cell layers treated with or without PI-PLC. Knockdown of prostasin attenuated binding of plasmin to M1 cells and blocked......Several pathophysiological conditions, including nephrotic syndrome, are characterized by increased renal activity of the epithelial Na(+) channel (ENaC). We recently identified plasmin in nephrotic urine as a stimulator of ENaC activity and undertook this study to investigate the mechanism...

  6. Concentration dependent effects of dextran on the physical properties of acid milk gels.

    Science.gov (United States)

    Mende, Susann; Peter, Michaela; Bartels, Karin; Dong, Tingting; Rohm, Harald; Jaros, Doris

    2013-11-06

    The effect of dextran from Leuconostoc mesenteroides (DEX500), added to milk prior to acidification with glucono-δ-lactone (GDL) or Streptococcus thermophilus DSM20259, was studied with respect to polysaccharide concentration. The incorporation of 5-30 g/kg DEX500 significantly affected gelation behavior. Increasing DEX500 concentrations resulted in a linear increase of gel stiffness (GDL gels: R(2)=0.96; microbial acidification: R(2)=0.94; Pgels without polysaccharide. The respective stirred gels depicted a significant reduction in syneresis, which decreased from 30.4% (0 g/kg DEX500) to 22.0% (30 g/kg DEX500) for chemically acidified gels after 1 d of storage. Physical characteristics of DEX500 in aqueous solution were helpful to explain its behavior in the complex system milk.

  7. Dependence of the solubility of atmospheric oxygen in weakly alkaline aqueous solutions on surfactant concentration

    Science.gov (United States)

    Chistyakova, G. V.; Koksharov, S. A.; Vladimirova, T. V.

    2012-11-01

    The solubility of atmospheric oxygen in solutions of surfactants of different natures at 293 K and pH 8 is determined by gas chromatography. It is found that additives of nonionic surfactants decrease the oxygen content in the solution in the premicellar region and increase its solubility in the micellar region. It is shown that, for anionic surfactants, a decrease in the solubility of O2 is observed over the entire concentration range.

  8. Electrospun Scaffolds for Osteoblast Cells: Peptide-Induced Concentration-Dependent Improvements of Polycaprolactone.

    Science.gov (United States)

    Dettin, Monica; Zamuner, Annj; Roso, Martina; Gloria, Antonio; Iucci, Giovanna; Messina, Grazia M L; D'Amora, Ugo; Marletta, Giovanni; Modesti, Michele; Castagliuolo, Ignazio; Brun, Paola

    2015-01-01

    The design of hybrid poly-ε-caprolactone (PCL)-self-assembling peptides (SAPs) matrices represents a simple method for the surface functionalization of synthetic scaffolds, which is essential for cell compatibility. This study investigates the influence of increasing concentrations (2.5%, 5%, 10% and 15% w/w SAP compared to PCL) of three different SAPs on the physico-chemical/mechanical and biological properties of PCL fibers. We demonstrated that physico-chemical surface characteristics were slightly improved at increasing SAP concentrations: the fiber diameter increased; surface wettability increased with the first SAP addition (2.5%) and slightly less for the following ones; SAP-surface density increased but no change in the conformation was registered. These results could allow engineering matrices with structural characteristics and desired wettability according to the needs and the cell system used. The biological and mechanical characteristics of these scaffolds showed a particular trend at increasing SAP concentrations suggesting a prevailing correlation between cell behavior and mechanical features of the matrices. As compared with bare PCL, SAP enrichment increased the number of metabolic active h-osteoblast cells, fostered the expression of specific osteoblast-related mRNA transcripts, and guided calcium deposition, revealing the potential application of PCL-SAP scaffolds for the maintenance of osteoblast phenotype.

  9. Influence of repeated permanent coloring and bleaching on ethyl glucuronide concentrations in hair from alcohol-dependent patients.

    Science.gov (United States)

    Crunelle, Cleo L; Yegles, Michel; De Doncker, Mireille; Dom, Geert; Cappelle, Delphine; Maudens, Kristof E; van Nuijs, Alexander L N; Covaci, Adrian; Neels, Hugo

    2015-02-01

    Ethyl glucuronide (EtG), a minor metabolite of alcohol, is used as a sensitive marker in hair to detect the retrospective consumption of alcohol. The proximal 0-3 cm hair segment is often used for analysis, providing information on alcohol consumption over the past 3 months. Using more distal segments would allow the detection of alcohol consumption over longer time periods, thereby addressing the chronicity of the consumption. In view of this, permanent coloring and bleaching were shown in vitro to alter EtG concentrations in hair, but no in vivo studies are available to prove or disprove this. To investigate the influence of repeated bleaching and permanent coloring on EtG concentrations in vivo and to assess the stability of EtG concentrations in distal compared to proximal hair segments. Hair samples from alcohol-dependent patients with uncolored/unbleached (N=4), permanent coloration (N=5) and bleached hair (N=5) were analyzed in two to six 3 cm long segments for EtG concentrations, and alcohol consumption and hair cosmetic treatments were assessed. We observed that hair bleaching and permanent coloring reduces EtG concentrations by 82±11% and 65±24%, respectively, with correlations between the number of cosmetic treatments and the decrease in EtG concentrations. EtG remained stable in untreated hair samples up to 18 cm. EtG is a sensitive marker to assess chronic alcohol consumption up to 18 months in alcohol-dependent patients with no cosmetic hair treatments. However, in alcohol-dependent patients who color or bleach their hair, care should be taken when interpreting EtG measurements. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  10. The Color of Lactotroph Secretory Granules Stained with FM1-43 Depends on Dye Concentration

    OpenAIRE

    Johnson, Joseph M.; Betz, William J.

    2007-01-01

    When pituitary lactotroph granules undergo exocytosis in the presence of FM1-43, their cores absorb dye and fluoresce brightly. We report that different granules fluoresce with different colors, despite being stained with a single fluorescent dye; emission spectra from individual granules show up to a 25 nm difference between the greenest and reddest granules. We found a correlation between granule color and average fluorescence intensity, suggesting that granule color depends upon dye concen...

  11. The dependency of compound biological effectiveness factors on the type and the concentration of administered neutron capture agents in boron neutron capture therapy

    OpenAIRE

    Masunaga, Shin-Ichiro; Sakurai, Yoshinori; Tanaka, Hiroki; Tano, Keizo; Suzuki, Minoru; Kondo, Natsuko; Narabayashi, Masaru; Nakagawa, Yosuke; Watanabe, Tsubasa; Maruhashi, Akira; ONO, KOJI

    2014-01-01

    Purpose To examine the effect of the type and the concentration of neutron capture agents on the values of compound biological effectiveness (CBE) in boron neutron capture therapy. Methods and materials After the subcutaneous administration of a 10 B-carrier, boronophenylalanine- 10 B (BPA) or sodium mercaptododecaborate- 10 B (BSH), at 3 separate concentrations, the 10 B concentrations in tumors were measured by γ-ray spectrometry. SCC VII tumor-bearing C3H/He mice received 5-bromo-2′-deoxyu...

  12. Species-dependent effective concentration of DTPA in plasma for chelation of 241Am.

    Science.gov (United States)

    Sueda, Katsuhiko; Sadgrove, Matthew P; Jay, Michael; Di Pasqua, Anthony J

    2013-08-01

    Diethylenetriaminepentaacetic acid (DTPA) is a chelating agent that is used to facilitate the elimination of radionuclides such as americium from contaminated individuals. Its primary site of action is in the blood, where it competes with various biological ligands, including transferrin and albumin, for the binding of radioactive metals. To evaluate the chelation potential of DTPA under these conditions, the competitive binding of Am between DTPA and plasma proteins was studied in rat, beagle, and human plasma in vitro. Following incubation of DTPA and Am in plasma, the Am-bound ligands were fractionated by ultrafiltration and ion-exchange chromatography, and each fraction was assayed for Am content by gamma scintillation counting. Dose response curves of DTPA for Am binding were established, and these models were used to calculate the 90% maximal effective concentration, or EC90, of DTPA in each plasma system. The EC90 were determined to be 31.4, 15.9, and 10.0 μM in rat, beagle, and human plasma, respectively. These values correspond to plasma concentrations of DTPA that maximize Am chelation while minimizing excess DTPA. Based on the pharmacokinetic profile of DTPA in humans, after a standard 30 μmol kg intravenous bolus injection, the plasma concentration of DTPA remains above EC90 for approximately 5.6 h. Likewise, the effective duration of DTPA in rat and beagle were determined to be 0.67 and 1.7 h, respectively. These results suggest that species differences must be considered when translating DTPA efficacy data from animals to humans and offer further insights into improving the current DTPA treatment regimen.

  13. Temperature sensitivity of soil respiration is dependent on readily decomposable C substrate concentration

    Directory of Open Access Journals (Sweden)

    A. A. Larionova

    2007-06-01

    Full Text Available Temperature acclimation of soil organic matter (SOM decomposition is one of the major uncertainties in predicting soil CO2 efflux by the increase in global mean temperature. A reasonable explanation for an apparent acclimation proposed by Davidson and colleagues (2006 based on Michaelis-Menten kinetics suggests that temperature sensitivity decreases when both maximal activity of respiratory enzymes (Vmax and half- saturation constant (Ks cancel each other upon temperature increase. We tested the hypothesis of the canceling effect by the mathematical simulation of the data obtained in the incubation experiments with forest and arable soils. Our data confirm the hypothesis and suggest that concentration of readily decomposable C substrate as glucose equivalent is an important factor controlling temperature sensitivity. The highest temperature sensitivity was observed when C substrate concentration was much lower than Ks. Increase of substrate content to the half-saturation constant resulted in temperature acclimation associated with the canceling effect. Addition of the substrate to the level providing respiration at a maximal rate Vmax leads to the acclimation of the whole microbial community as such. However, growing microbial biomass was more sensitive to the temperature alterations. This study improves our understanding of the instability of temperature sensitivity of soil respiration under field conditions, explaining this phenomenon by changes in concentration of readily decomposable C substrate. It is worth noting that this pattern works regardless of the origin of C substrate: production by SOM decomposition, release into the soil by rhizodeposition, litter fall or drying-rewetting events.

  14. IMPACT OF DYNAMICAL HYDRATION SHELL AROUND HA PROTEIN ON NONLINEAR CONCENTRATION DEPENDENT T-RAYS ABSORPTION

    Directory of Open Access Journals (Sweden)

    YIWEN SUN

    2013-10-01

    Full Text Available T-rays is sensitive to covalently cross-linked proteins and can be used to probe unique dynamic properties of water surrounding a protein. In this paper, we demonstrate the unique absorption properties of the dynamic hydration shells determined by hemagglutinin (HA protein in terahertz frequency. We study the changes arising from different concentrations in detail and show that nonlinear absorption coefficient is induced by the dynamic hydration water. The binary and ternary component model were used to interpret the nonlinearity absorption behaviors and predict the thickness of the hydration shells around the HA protein in aqueous phase.

  15. The effect of a concentration-dependent viscosity on particle transport in a channel flow with porous walls

    KAUST Repository

    Herterich, James G.

    2014-02-02

    The transport of a dilute suspension of particles through a channel with porous walls, accounting for the concentration dependence of the viscosity, is analyzed. In particular, we study two cases of fluid permeation through the porous channel walls: (1) at a constant flux and (2) dependent on the pressure drop across the wall. We also consider the effect of mixing the suspension first compared with point injection by considering inlet concentration distributions of different widths. We find that a pessimal inlet distribution width exists that maximizes the required hydrodynamic pressure for a constant fluid influx. The effect of an external hydrodynamic pressure, to compensate for the reduced transmembrane pressure difference due to osmotic pressure, is investigated. © 2014 American Institute of Chemical Engineers.

  16. Identification of deletions and duplications in the Duchenne muscular dystrophy gene and female carrier status in western India using combined methods of multiplex polymerase chain reaction and multiplex ligation-dependent probe amplification

    Directory of Open Access Journals (Sweden)

    Rashna S Dastur

    2011-01-01

    Full Text Available Background: The technique of multiplex ligation-dependent probe amplification (MLPA assay is an advanced technique to identify deletions and duplications of all the 79 exons of DMD gene in patients with Duchenne/Becker muscular dystrophy (DMD/BMD and female carriers. Aim: To use MLPA assay to detect deletions which remained unidentified on multiplex polymerase chain reaction (mPCR analysis, scanning 32 exons of the "hot spot" region. Besides knowing the deletions and/or duplications, MLPA was also used to determine the carrier status of the females at risk. Materials and Methods: Twenty male patients showing no deletions on mPCR and 10 suspected carrier females were studied by MLPA assay using P-034 and P-035, probe sets (MRC Holland covering all the 79 exons followed by capillary electrophoresis on sequencing system. Results: On MLPA analysis, nine patients showed deletions of exons other than 32 exons screened by mPCR represented by absence of peak. Value of peak areas were double or more in four patients indicating duplications of exons. Carrier status was confirmed in 50% of females at risk. Conclusion: Combining the two techniques, mPCR followed by MLPA assay, has enabled more accurate detection and extent of deletions and duplications which otherwise would have remained unidentified, thereby increasing the mutation pick up rate. These findings have also allowed prediction of expected phenotype. Determining carrier status has a considerable significance in estimating the risk in future pregnancies and prenatal testing options to limit the birth of affected individuals.

  17. Small scale hybrid concentrated solar power - biomass system. Development, time dependent modelling and validation.

    OpenAIRE

    Tortora, Eileen

    2011-01-01

    Proceeding from the sustainable development principle and the current energy issues, in the present work a small-scale fully renewable power plant was designed, modelled in a time-dependent environment and validated. The plant is design in order to produce both thermal and electric power either in on- or off-grid configuration. With respect to the state of the art, the power plant is composed by standard and well-known technologies. The novelties brought with the present study are entailed...

  18. Nanomolar concentrations of inorganic lead increase Ca2+ efflux and decrease intracellular free Ca2+ ion concentrations in cultured rat hippocampal neurons by a calmodulin-dependent mechanism.

    Science.gov (United States)

    Ferguson, C; Kern, M; Audesirk, G

    2000-06-01

    Inorganic lead (Pb2+) activates calmodulin, which in turn may stimulate many other cellular processes. The plasma membrane Ca2+ ATPase is a calmodulin-stimulated enzyme that plays the major role in regulating the "resting" intracellular free Ca2+ ion concentration, [Ca2+]i. We hypothesized that exposing neurons to low levels of Pb2+ would cause Pb2+ to enter the cytoplasm, and that intracellular Pb2+, by activating calmodulin, would stimulate plasma membrane Ca2+ ATPase activity, thereby increasing Ca2+ extrusion and reducing [Ca2+]i. We used the ratiometric Ca2+ indicator fura-2 to estimate changes in [Ca2+]i. In vitro calibrations of fura-2 with solutions of defined free Ca2+ and free Pb2+ concentrations showed that, at free Ca2+ concentrations from 10 nM to 1000 nM, adding Pb2+ caused either no significant change in the F340/F380 ratio (free Pb2+ concentrations from 100 fM to 1 pM) or increased the F340/F380 ratio (free Pb2+ concentrations from 5 to 50 pM). Therefore, fura-2 should be suitable for estimating Pb2+-induced decreases in [Ca2+]i, but not increases in [Ca2+]i. We exposed cultured embryonic rat hippocampal neurons to 100 nM Pb2+ for periods from 1 hour to 2 days and measured the F340/F380 ratio; the ratio decreased significantly by 9 to 16% at all time points, indicating that Pb2+ exposure decreased [Ca2+]i. In neurons loaded with 45Ca, Pb2+ exposure increased Ca2+ efflux for at least two hours; by 24 hours, Ca2+ efflux returned to control levels. Influx of 45Ca was not altered by Pb2+ exposure. Low concentrations (250 nM) of the calmodulin inhibitor calmidazolium had no effect on either 45Ca efflux or on the F340/F380 ratio in fura-loaded control neurons, but completely eliminated the increase in 45Ca efflux and decrease in F340/F380 ratio in Pb2+-exposed neurons. Zaldoride, another calmodulin inhibitor, also eliminated the decrease in F340/F380 ratio in Pb2+-exposed neurons. We conclude that Pb2+ exposure decreases [Ca2+]i and increases Ca2+ efflux

  19. High content analysis at single cell level identifies different cellular responses dependent on nanomaterial concentrations.

    Science.gov (United States)

    Manshian, Bella B; Munck, Sebastian; Agostinis, Patrizia; Himmelreich, Uwe; Soenen, Stefaan J

    2015-09-08

    A mechanistic understanding of nanomaterial (NM) interaction with biological environments is pivotal for the safe transition from basic science to applied nanomedicine. NM exposure results in varying levels of internalized NM in different neighboring cells, due to variances in cell size, cell cycle phase and NM agglomeration. Using high-content analysis, we investigated the cytotoxic effects of fluorescent quantum dots on cultured cells, where all effects were correlated with the concentration of NMs at the single cell level. Upon binning the single cell data into different categories related to NM concentration, this study demonstrates, for the first time, that quantum dots activate both cytoprotective and cytotoxic mechanisms, resulting in a zero net result on the overall cell population, yet with significant effects in cells with higher cellular NM levels. Our results suggest that future NM cytotoxicity studies should correlate NM toxicity with cellular NM numbers on the single cell level, as conflicting mechanisms in particular cell subpopulations are commonly overlooked using classical toxicological methods.

  20. High content analysis at single cell level identifies different cellular responses dependent on nanomaterial concentrations

    Science.gov (United States)

    Manshian, Bella B.; Munck, Sebastian; Agostinis, Patrizia; Himmelreich, Uwe; Soenen, Stefaan J.

    2015-09-01

    A mechanistic understanding of nanomaterial (NM) interaction with biological environments is pivotal for the safe transition from basic science to applied nanomedicine. NM exposure results in varying levels of internalized NM in different neighboring cells, due to variances in cell size, cell cycle phase and NM agglomeration. Using high-content analysis, we investigated the cytotoxic effects of fluorescent quantum dots on cultured cells, where all effects were correlated with the concentration of NMs at the single cell level. Upon binning the single cell data into different categories related to NM concentration, this study demonstrates, for the first time, that quantum dots activate both cytoprotective and cytotoxic mechanisms, resulting in a zero net result on the overall cell population, yet with significant effects in cells with higher cellular NM levels. Our results suggest that future NM cytotoxicity studies should correlate NM toxicity with cellular NM numbers on the single cell level, as conflicting mechanisms in particular cell subpopulations are commonly overlooked using classical toxicological methods.

  1. EPR study of concentration dependence in Ce, Ce : La and Ce:Y doped SrF2

    NARCIS (Netherlands)

    Dankert, O.; Vainchtein, David; Datema, H.C.; den Hartog, Hendrik

    1995-01-01

    Experimental results of an EPR-study of the concentration dependence of the doubly integrated intensity and linewidth of the signals associated with tetragonal Ce3+-F--dipoles in Sr1-xCexF2+x, Sr-1-0.005-x Ce0.005LaxF2+0.005+x and Sr-1-0.005-x Ce0.005YxF2+0.005+x are presented. Both show a nonlinear

  2. Dependence of plant biometrics of cutting lettuce (Lactuca sativa L. varietis on the concentration of microfertilizer Avatar-1

    Directory of Open Access Journals (Sweden)

    В. Б. Кутовенко

    2017-09-01

    Full Text Available Purpose. To investigate the variability of plant biometrics of cutting lettuce (Lactuca sativa L. varieties depending on the concentration of microfertilizer Avatar-1. Methods. Field study, biometric technique, comparative approach, statistical evaluation, generalization. Results. Dependence of the plant height, the diameter of the leaf rosette, the number of leaves per plant, the leaf area of plants on the concentration of microfertilizer Avatar-1 was defined. Investigations of cutting lettuce ‘Afitsyon’ and ‘Concord’ varieties by Dutch breeding were conducted in 2016–2017 in the collection sites of the department of vegetable growing in the scientific-experimental field  “Fruit and vegetable garden” of the National University of Life and Environmental Sciences of Ukraine. In order to determine dependence of plant biometrics of cutting lettuce varieties on the concentration of complex microfertilizer Avatar-1, the following scheme was used for the both varieties: variant 1 – water (control; variant 2 – 0,10% solution; variant 3 – 0,25% solution; variant 4 – 0,50% solution. Plants were treated with microfertilizer three times during the vegetative period. Alterations of plant biometrics of cutting lettuce ‘Afitsyon’ and ‘Concord’ varieties  depending on the concentration of complex microfertilizer Avatar-1 was studied. Conclusions. It was found that in case of three-time plant treatment with complex microfertilizer Avatar-1 at the time of harvesting, the best plant biometrics was registered in variant 3 (concentration 0,25% for the both ‘Afitsyon’ and ‘Concord’ varie­ties of cutting lettuce. The height of plants of the cutting lettuce in ‘Afitsyon’ variety exceeded this figure in ‘Concord variety by 1,1–1,4 cm. The concentration of microfertilizer had no significant effect on the diameter of the leaf rosette of ‘Concord’ variety (25,1–25,9 см. The diame­ter of the leaf rosette of

  3. Concentration-dependent isoflurane effects on withdrawal reflexes in pigs and the role of the stimulation paradigm.

    Science.gov (United States)

    Spadavecchia, C; Haga, H A; Ranheim, B

    2012-12-01

    In this prospective two-phase experimental trial, 10 pigs were anaesthetized twice with isoflurane only. In the first phase, the individual minimum alveolar concentration (MAC) was determined and in the second phase the effects on withdrawal reflexes of increasing end-tidal isoflurane concentrations (from 1.6% to 2.8%) were assessed. Single, 10 and 60 repeated electrical stimulations were used to evoke withdrawal reflexes which were recorded and quantified by electromyography. Recruitment curves for reflex amplitude for increasing stimulation intensities and isoflurane concentrations were constructed. Isoflurane MAC was 1.9 ± 0.3%. Reflexes evoked by repeated stimulation were suppressed at isoflurane concentrations significantly higher than those which suppressed complex movements during MAC determination (P=0.014 and P=0.006 for 10 and 60 repeated stimuli respectively). Isoflurane up to 2.8% was still not able to abolish reflex activity evoked by repeated stimulations in all pigs. Single stimulation reflexes were suppressed at significantly lower concentrations than repeated stimulation reflexes (P=0.008 and P=0.004 for 10 and 60 repeated stimuli, respectively). Reflex amplitude was significantly correlated with isoflurane concentration (Preflexes is dependent on the stimulation paradigm (single vs. repeated electrical stimulation), and there is limited value in expressing reflex withdrawal suppression in terms of MAC as purposeful and reflex movements are independently affected by isoflurane in individual animals. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Concentration-dependent effects of cocaine on monoamine-induced constriction of cannulated, pressurized cerebral arteries from fetal sheep.

    Science.gov (United States)

    Schreiber, M D; Madden, J A; Covert, R F; Hershenson, M B; Torgerson, L J

    1995-01-01

    Drugs, such as cocaine, which may alter monoamine neurotransmitter responsiveness, could adversely affect the regulation of cerebral vasculature. Cocaine exhibits at least two mechanisms that may alter vascular responsiveness: synaptic uptake inhibition, which may augment response to stimulation, and Na+ channel inhibition, which may attenuate response. To help elicit the concentration-dependent effects of cocaine, the effects of cocaine on monoamine neurotransmitter responsiveness were studied in vitro on fetal sheep cerebral arteries (120 days gestation). The changes in diameter of segments of cannulated, pressurized fetal sheep cerebral artery were measured with a videomicroscaler system. Cumulative concentration-response curves (10(-10) to 10(-4)M) were generated for two monoamines, norepinephrine and serotonin, alone and in the presence of cocaine (10(-5) or 10(-4)M). Cocaine caused concentration-dependent alteration of response. At 10(-4)M, cocaine attenuated mean maximal norepinephrine-induced vasoconstriction 46.2% (P < 0.05). At 10(-5)M, cocaine increased sensitivity to norepinephrine (log EC50 decreased -6.63 +/- 0.09 to -7.11 +/- 0.03) and to serotonin (log EC50 decreased -7.24 +/- 0.04 to -7.81 +/- 0.09) (P < 0.05). The higher concentration of cocaine (10(-4)M) did not significantly decrease log EC50 norepinephrine. Cocaine (10(-4)M) also attenuated the response to single doses of norepinephrine (10(-6)M) and serotonin (10(-6)M) by 26.5% and 40.0%, respectively (P < or = 0.05). It is concluded that cocaine has concentration-dependent effects on vasoconstriction of the fetal sheep cerebral artery in vitro. This cocaine-induced alteration of cerebral vascular responsiveness to monoamines may be important in the regulation of fetal cerebral blood flow.

  5. Time- and concentration-dependent genomic responses of the rat airway to inhaled nickel subsulfide

    Energy Technology Data Exchange (ETDEWEB)

    Efremenko, A.Y., E-mail: aefremenko@thehamner.org [The Hamner Institutes for Health Sciences, 6 Davis Drive, Research Triangle Park, NC 27709 (United States); Campbell, J.L.; Dodd, D.E. [The Hamner Institutes for Health Sciences, 6 Davis Drive, Research Triangle Park, NC 27709 (United States); Oller, A.R. [NiPERA, Inc., 2525 Meridian Parkway, Suite 240, Durham, NC 27713 (United States); Clewell, H.J. [The Hamner Institutes for Health Sciences, 6 Davis Drive, Research Triangle Park, NC 27709 (United States)

    2014-09-15

    Objective: To provide insights into the mode of action for Ni{sub 3}S{sub 2} lung carcinogenicity by examining gene expression changes in target cells after inhalation exposure. Methods: Gene expression changes were determined in micro-dissected lung broncho-alveolar cells from Fischer 344 rats following inhalation of Ni{sub 3}S{sub 2} at 0.0, 0.04, 0.08, 0.15, and 0.60 mg/m{sup 3} (0.03, 0.06, 0.11, and 0.44 mg Ni/m{sup 3}) for one and four weeks (6 h/day, 5 days/week). Results: Broncho-alveolar lavage fluid evaluation and lung histopathology provided evidence of inflammation only at the two highest concentrations, which were similar to those tested in the 2-year bioassay. The number of statistically significant up- and down-regulated genes decreased markedly from one to four weeks of exposure, suggesting adaptation. Cell signal pathway enrichment at both time-points primarily reflected responses to toxicity, including inflammatory and proliferative signaling. While proliferative signaling was up-regulated at both time points, some inflammatory signaling reversed from down-regulation at 1 week to up-regulation at 4 weeks. Conclusions: These results support a mode of action for Ni{sub 3}S{sub 2} carcinogenicity driven by chronic toxicity, inflammation and proliferation, leading to mis-replication, rather than by direct genotoxicity. Benchmark dose (BMD) analysis identified the lowest pathway transcriptional BMD exposure concentration as 0.026 mg Ni/m{sup 3}, for apoptosis/survival signaling. When conducted on the basis of lung Ni concentration the lowest pathway BMD was 0.64 μg Ni/g lung, for immune/inflammatory signaling. Implications: These highly conservative BMDs could be used to derive a point of departure in a nonlinear risk assessment for Ni{sub 3}S{sub 2} toxicity and carcinogenicity. - Highlights: • The mode of action for lung carcinogenicity of inhaled Ni{sub 3}S{sub 2} was investigated in rats. • Gene expression changes were determined in micro

  6. In Vitro Neurotoxicity of PBDE-99: Immediate and Concentration-Dependent Effects on Protein Expression in Cerebral Cortex Cells

    DEFF Research Database (Denmark)

    Alm, Henrik; Scholz, Birger; Kultima, Kim;

    2010-01-01

    Polybrominated diphenyl ethers (PBDEs) are commonly used flame retardants in various consumer products. Pre- and postnatal exposure to congeners of PBDEs disrupts normal brain development in rodents. Two-dimensional difference gel electrophoresis (2D-DIGE) was used to analyze concentration......-dependent differences in protein expression in cultured cortical cells isolated from rat fetuses (GD 21) after 24 h exposure to PBDE-99 (3, 10, or 30 muM). Changes on a post-translational level were studied using a 1 h exposure to 30 muM PBDE-99. The effects of 24 h exposure to 3 and 30 muM PBDE-99 on mRNA levels were...... effects of low-concentration PBDE-99 exposure are fundamentally different than effects of high-concentration exposure. Low-dose PBDE-99 exposure induced marked effects on cytoskeletal proteins, which was not correlated to cytotoxicity or major morphological effects, suggesting that other more regulatory...

  7. DNA duplex length and salt concentration dependence of enthalpy-entropy compensation parameters for DNA melting.

    Science.gov (United States)

    Starikov, E B; Nordén, Bengt

    2009-08-20

    Systematical differential calorimetry experiments on DNA oligomers with different lengths and placed in water solutions with various added salt concentrations may, in principle, unravel important information about the structure and dynamics of the DNA and their water-counterion surrounding. With this in mind, to reinterpret the most recent results of calorimetric experiments on DNA oligomers of such a kind, the recent enthalpy-entropy compensation theory has been used. It is demonstrated that the application of the latter could enable direct estimation of thermodynamic parameters of the microphase transitions connected to the changes in DNA dynamical regimes versus the length of the biopolymers and the ionic strengths of their water solutions, and this calls for much more systematical experimental and theoretical studies in this field.

  8. DNA Duplex Length and Salt Concentration Dependence of Enthalpy−Entropy Compensation Parameters for DNA Melting

    KAUST Repository

    Starikov, E. B.

    2009-08-20

    Systematical differential calorimetry experiments on DNA oligomers with different lengths and placed in water solutions with various added salt concentrations may, in principle, unravel important information about the structure and dynamics of the DNA and their water-counterion surrounding. With this in mind, to reinterpret the most recent results of calorimetric experiments on DNA oligomers of such a kind, the recent enthalpy-entropy compensation theory has been used. It is demonstrated that the application of the latter could enable direct estimation of thermodynamic parameters of the microphase transitions connected to the changes in DNA dynamical regimes versus the length of the biopolymers and the ionic strengths of their water solutions, and this calls for much more systematical experimental and theoretical studies in this field. © 2009 American Chemical Society.

  9. Concentration Dependence of Afterglow Suppression in CsI:Tl,Sm

    Science.gov (United States)

    Kappers, L. A.; Bartram, R. H.; Hamilton, D. S.; Lempicki, A.; Brecher, C.; Gaysinskiy, V.; Ovechkina, E. E.; Nagarkar, V. V.

    2010-11-01

    Combined radioluminescence, afterglow and thermoluminescence experiments on single-crystal samples of co-doped CsI:Tl,Sm suggest that deeper samarium electron traps scavenge electrons from shallower thallium traps and that electrons subsequently released by samarium recombine non-radiatively with holes trapped as VKA(Tl+) centers, thus providing a mechanism for suppression of trapped-charge accumulation in repetitive applications. In the present investigation, experiments performed on two single-crystal samples of CsI:Tl,Sm with nominal concentrations of 0.11% Tl+ and of 0.2% and 0.05% Sm2+, respectively, support the inference that electrons tunnel freely between samarium ions and are trapped preferentially near VKA(Tl+) centers where non-radiative recombination is the rate-limiting step.

  10. Concentration Dependence of Afterglow Suppression in CsI:Tl,Sm

    Energy Technology Data Exchange (ETDEWEB)

    Kappers, L A; Bartram, R H; Hamilton, D S; Lempicki, A; Brecher, C; Gaysinskiy, V; Ovechkina, E E; Nagarkar, V V, E-mail: lawrence.kappers@uconn.ed

    2010-11-01

    Combined radioluminescence, afterglow and thermoluminescence experiments on single-crystal samples of co-doped CsI:Tl,Sm suggest that deeper samarium electron traps scavenge electrons from shallower thallium traps and that electrons subsequently released by samarium recombine non-radiatively with holes trapped as V{sub KA}(Tl{sup +}) centers, thus providing a mechanism for suppression of trapped-charge accumulation in repetitive applications. In the present investigation, experiments performed on two single-crystal samples of CsI:Tl,Sm with nominal concentrations of 0.11% Tl{sup +} and of 0.2% and 0.05% Sm{sup 2+}, respectively, support the inference that electrons tunnel freely between samarium ions and are trapped preferentially near V{sub KA}(Tl{sup +}) centers where non-radiative recombination is the rate-limiting step.

  11. Statins can exert dual, concentration dependent effects on HCV entry in vitro.

    Science.gov (United States)

    Blanchet, Matthieu; Le, Quoc-Tuan; Seidah, Nabil G; Labonté, Patrick

    2016-04-01

    Statins are used daily by a large and increasing number of individuals worldwide. They were initially designed as 3-hydroxy-3-methylglutharyl-coenzyme A reductase (HMG-CoAR) inhibitors to treat patients with hypercholesterolemia. Recent studies on HCV chronically infected individuals have suggested that their use in vivo in combination with PEG-IFN and ribavirin favor the sustained viral response (SVR). Herein, we describe the effects of a set of statins on HCV entry and on HCV key entry factors in vitro. Our results suggest that all tested statins exert a proviral effect through the upregulation of LDLR. Interestingly, at higher concentration, we also provide evidence of a yet unknown competing antiviral effect of statins (except for pravastatin) through the downregulation of CLDN-1. Importantly, this work enlightens the blunt proviral effect of pravastatin at the entry step of HCV in vitro.

  12. Dual dependence of cryobiogical properties of Sf21 cell membrane on the temperature and the concentration of the cryoprotectant.

    Directory of Open Access Journals (Sweden)

    Jianye Wang

    Full Text Available The Sf21 cell line is extensively used for virus research and producing heterologous recombinant proteins. To develop optimal strategies for minimizing cell injury due to intracellular ice formation and excessive volume shrinkage during cryopreservation, the fundamental transport properties including the osmotic inactive volume (Vb , the hydraulic conductivity (Lp , and the glycerol permeability (Ps of Sf21 cell membrane at 25, 15, 5 and -2°C were characterized using a micro-perfusion chamber. The effects of temperature on the hydraulic conductivity and the glycerol permeability of Sf21 cell membrane, reflected by the activation energies, were quantitatively investigated. It was found that the hydraulic conductivity decreases along with the increase of the final CPA concentration at a given temperature, and quantitative analysis indicates that the hydraulic conductivity has a significant linear attenuation along with the increase of the concentration of glycerol. Therefore, we incorporate the concentration dependence of the hydraulic conductivity into the classic Arrhenius relationship by replacing the constant reference value of the hydraulic conductivity at the reference temperature with a function that is linearly dependent on the CPA concentration. Consequently, the prediction of the Arrhenius relationship is improved, and the novel Arrhenius relationship could be very important to the development of optimal strategies for cell cryopreservation.

  13. Concentration-dependent Sildenafil citrate (Viagra) effects on ROS production, energy status, and human sperm function.

    Science.gov (United States)

    Sousa, Maria Inês; Amaral, Sandra; Tavares, Renata Santos; Paiva, Carla; Ramalho-Santos, João

    2014-04-01

    Literature regarding the effects of sildenafil citrate on sperm function remains controversial. In the present study, we specifically wanted to determine if mitochondrial dysfunction, namely membrane potential, reactive oxygen species production, and changes in energy content, are involved in in vitro sildenafil-induced alterations of human sperm function. Sperm samples of healthy men were incubated in the presence of 0.03, 0.3, and 3 μM sildenafil citrate in a phosphate buffered saline (PBS)-based medium for 2, 3, 12, and 24 hours. Sperm motility and viability were evaluated and mitochondrial function, i.e., mitochondrial membrane potential and mitochondrial superoxide production were assessed using flow-cytometry. Additionally, adenosine triphosphate (ATP) levels were determined by high performance liquid chromatography (HPLC) analysis. Results show a decrease in sperm motility correlated with the level of mitochondria-generated superoxide, without a visible effect on mitochondrial membrane potential or viability upon exposure to sildenafil. The effect on both motility and superoxide production was higher for the intermediate concentration of sildenafil (0.3 µM) indicating that the in vitro effects of sildenafil on human sperm do not vary linearly with drug concentration. Adenosine triphosphate levels also decreased following sildenafil exposure, but this decrease was only detected after a decrease in motility was already evident. These results suggest that along with the level of ATP and mitochondrial function other factors are involved in the early sildenafil-mediated decline in sperm motility. However, the further decrease in ATP levels and increase in mitochondria-generated reactive oxygen species after 24 hours of exposure might further contribute towards declining sperm motility.

  14. Greenhouse effect dependence on atmospheric concentrations of greenhouse substances and the nature of climate stability on Earth

    Directory of Open Access Journals (Sweden)

    V. G. Gorshkov

    2002-03-01

    Full Text Available Due to the exponential positive feedback between sea surface temperature and saturated water vapour concentration, dependence of the planetary greenhouse effect on atmospheric water content is critical for stability of a climate with extensive liquid hydrosphere.

    In this paper on the basis of the law of energy conservation we develop a simple physically transparent approach to description of radiative transfer in an atmosphere containing greenhouse substances. It is shown that the analytical solution of the equation thus derived coincides with the exact solution of the well-known radiative transfer equation to the accuracy of 20% for all values of atmospheric optical depth. The derived equation makes it possible to easily take into account the non-radiative thermal fluxes (convection and latent heat and obtain an analytical dependence of the greenhouse effect on atmospheric concentrations of a set of greenhouse substances with arbitrary absorption intervals.

    The established dependence is used to analyse stability of the modern climate of Earth. It is shown that the modern value of global mean surface temperature, which corresponds to the liquid state of the terrestrial hydrosphere, is physically unstable. The observed stability of modern climate over geological timescales is therefore likely to be due to dynamic singularities in the physical temperature-dependent behaviour of the greenhouse effect. We hypothesise that such singularities may appear due to controlling functioning of the natural global biota and discuss major arguments in support of this conclusion.

  15. A Dependence of the Electronuclear System Parameters on the Component Concentration in Fuel MOX

    CERN Document Server

    Barashenkov, V S

    2001-01-01

    A dependence of the parameters of a electronuclear system with U-Pu fuel MOX on the relative share of plutonium and its isotope ^{240}Pu in fuel is investigated by means of mathematical modelling. As an example, we consider an experimental system with a heat power 10-20 kW designed in Dubna on the basis of the 660 MeV proton phasotron. The 2 % admixture of ^{240}Pu decreases the value of the neutron multiplication coefficient from 0.95 down to 0.90, neutron yield and heat power are diminished almost twice. Such a decrease can be compensated by the increase of Plutonium share in MOX from 25 up to 27 %.

  16. Both RIG-I and MDA5 detect alphavirus replication in concentration-dependent mode.

    Science.gov (United States)

    Akhrymuk, Ivan; Frolov, Ilya; Frolova, Elena I

    2016-01-01

    Alphaviruses are a family of positive-strand RNA viruses that circulate on all continents between mosquito vectors and vertebrate hosts. Despite a significant public health threat, their biology is not sufficiently investigated, and the mechanisms of alphavirus replication and virus-host interaction are insufficiently understood. In this study, we have applied a variety of experimental systems to further understand the mechanism by which infected cells detect replicating alphaviruses. Our new data strongly suggest that activation of the antiviral response by alphavirus-infected cells is determined by the integrity of viral genes encoding proteins with nuclear functions, and by the presence of two cellular pattern recognition receptors (PRRs), RIG-I and MDA5. No type I IFN response is induced in their absence. The presence of either of these PRRs is sufficient for detecting virus replication. However, type I IFN activation in response to pathogenic alphaviruses depends on the basal levels of RIG-I or MDA5.

  17. Dependence of SOA oxidation on organic aerosol mass concentration and OH exposure: experimental PAM chamber studies

    Directory of Open Access Journals (Sweden)

    E. Kang

    2011-02-01

    Full Text Available The oxidation of secondary organic aerosol (SOA is studied with mass spectra analysis of SOA formed in a Potential Aerosol Mass (PAM chamber, a small flow-through photo-oxidation chamber with extremely high OH and ozone levels. The OH exposure from a few minutes in the PAM chamber is similar to that from days to weeks in the atmosphere. The mass spectra were measured with a Quadrupole Aerosol Mass Spectrometer (Q-AMS for SOA formed from oxidation of α-pinene, m-xylene, p-xylene, and a mixture of the three. The organic mass fractions of m/z 44 (CO2+ and m/z 43 (mainly C2H3O+, named f44 and f43 respectively, are used as indicators of the degree of organic aerosol (OA oxidation that occurs as the OA mass concentration or the OH exposure are varied. The degree of oxidation is sensitive to both. For a fixed OH exposure, the degree of oxidation initially decreases rapidly and then more slowly as the OA mass concentration increases. For fixed initial precursor VOC amounts, the degree of oxidation increases linearly with OH exposure, with f44 increasing and f43 decreasing. In this study, the degree of SOA oxidation spans much of the range observed in the atmosphere. These results, while sensitive to the determination of f44 and f43, provide evidence that some characteristics of atmospheric OA oxidation can be generated in a PAM chamber. For all measurements in this study, the sum of f44 and f43 is 0.25 ± 0.03, so that the slope of a linear regression is approximately −1 on an f44 vs. f43 plot. This constancy of the sum suggests that these ions are complete proxies for organic mass in the OA studied.

  18. Dependence of bicellar system phase behavior and dynamics on anionic lipid concentration.

    Science.gov (United States)

    MacEachern, Lauren; Sylvester, Alexander; Flynn, Alanna; Rahmani, Ashkan; Morrow, Michael R

    2013-03-19

    Bicellar dispersions of chain perdeuterated 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC-d54) and 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC) were prepared with the molar fraction of DHPC held fixed at 20% and varying amounts of DMPC replaced by the anionic lipid 1,2-dimyristoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DMPG). (2)H NMR spectra were examined to assess the effect of added DMPG on mixture phase behavior and morphology. Quadrupole echo decay and quadrupole-Carr-Purcell-Mieboom-Gill echo train measurements provided information about slow motions contributing to echo decay in the high temperature phases. The spectra and quadrupole echo decay properties of DMPC-d54/DHPC (4:1) and DMPC-d54/DMPG/DHPC (3:1:1) were qualitatively similar. With increasing DMPG concentration, the transition between the magnetically orientable phase and the higher temperature phase became increasingly distinct, and the spectral shape and echo decay characteristics of the high temperature bicellar phase became increasingly similar to those of DMPC-d54 in the liquid crystalline phase. The observation that DMPG changes spectra in the orientable phase incrementally while increasing the distinction between the orientable and high temperature bicellar phases provides new insights into how DMPG influences bicellar mixture morphology.

  19. Assay-dependent variability of serum insulin concentrations: a comparison of eight assays.

    Science.gov (United States)

    Tohidi, Maryam; Arbab, Parvaneh; Ghasemi, Asghar

    2017-04-01

    Although insulin measurement is essential for both clinical and research purposes, there is currently no reference method for insulin assays. The aim of this study was to compare results of serum insulin determined by a number of commercially available assays. We compared eight insulin assays by analyzing 165 serum samples. Assays included two chemiluminescence (Roche and DiaSorin), four ELISA (Tosoh, Mercodia, Monobind, and Diametra), and two IRMA (Izotop and BioSource) methods. Each assay was compared with the mean of all assay methods and Bland-Altman difference plots were used to measure agreement between each assay and overall mean. Least squared perpendicular distance regression analysis (Deming's method) was used to calculate slope and intercept for bias and also for each assay vs. mean of eight assays. Findings showed that the lowest and highest median insulin concentrations varied by a factor of 1.8. Maximum and minimum correlations with mean of assays were observed for Roche (0.992) and BioSource (0.844), respectively. Significant bias was observed in six assays. In pairwise comparisons of different assays, the highest and least mean differences were 7.78 μU/mL and -0.14 μU/mL, respectively. In conclusion, serum insulin measurement with different assays showed a maximum of 1.8-fold difference, a point that should be taken into consideration in the interpretation of circulating insulin levels in both clinical and research fields.

  20. Fluorescent material concentration dependency: Förster resonance energy transfer in quasi-solid state DSSCs

    Science.gov (United States)

    Kim, Dong Woo; Jo, Hyun-Jun; Thogiti, Suresh; Yang, Weon Ki; Cheruku, Rajesh; Kim, Jae Hong

    2017-03-01

    Förster resonance energy transfer (FRET) is critical for wide spectral absorption, an increased dye loading, and photocurrent generation of dye-sensitized solar cells (DSSCs). This process consists of organic fluorescent materials (as an energy donor), and an organic dye (as an energy acceptor on TiO2 surfaces) with quasi-solid electrolyte. The judicious choice of the energy donor and acceptor facilitates a strong spectral overlap between the emission and absorption regions of the fluorescent materials and dye. This FRET process enhances the light-harvesting characteristics of quasi-solid state DSSCs. In this study, DSSCs containing different concentrations (0, 1, and 1.5 wt%) of a fluorescent material (FM) as the energy donor are investigated using FRET. The power conversion efficiency of DSSCs containing FMs in a quasi-solid electrolyte increased by 33% over a pristine cell. The optimized cell fabricated with the quasi-solid state DSSC containing 1.0 wt% FM shows a maximum efficiency of 3.38%, with a short-circuit current density (J SC ) of 4.32 mA/cm-2, and an open-circuit voltage (V OC ) of 0.68 V under illumination of simulated solar light (AM 1.5G, 100 mW/cm-2). [Figure not available: see fulltext.

  1. Dependency of working temperature and equivalent constant of concentric disk-type piezoelectric transformer

    Science.gov (United States)

    Chou, I.-Mu; Lai, Yi-Ying; Wu, Wen-Jong; Lee, Chih-Kung

    2011-03-01

    This paper presents the effect of equivalent constant and output power on working temperature of concentric disk-type piezoelectric transformer. To analyze the energy loss in the piezoelectric transformer, the equivalent circuit model was built. Losses in the piezoelectric transformer are considered generally having two different parts: dielectric loss and mechanical loss. First of all, a measurement circuit based on an impedance analyzer was built. Then, the circuit simulation software PSIM was employed to verify the experimental results obtained. Secondly, according to the experimental results, temperature and input voltage are the two factors which influenced the energy loss in a piezoelectric transformer. As the input voltage and temperature increased, the energy loss rises, as well. In addition, when the input voltage is low, the temperature becomes the main influencing factor for energy loss of the piezoelectric transformer. On the other hand, when the input voltage is high, the main factor for energy loss of the piezoelectric transformer is the input voltage other than the temperature. Furthermore, the control loop that dealt with the energy loss of the piezoelectric transformer was proposed. At different temperatures, the variations of losses of the piezoelectric transformer are presented in this paper. Finally, the dielectric loss and mechanical loss are combined to analyze the losses within piezoelectric transformers. Then, the relationship between the output power of the piezoelectric transformer and the temperature was revealed. The result showed that as the temperature increased, the output power decreased.

  2. Design of concentrator based on electric line broadband carrier and relay routing algorithm%基于电力线宽带载波集中器设计与中继算法

    Institute of Scientific and Technical Information of China (English)

    陈可; 胡晓光

    2011-01-01

    The design scheme of concentrator based on electric line broadband carrier and its automatic relay routing algorithm are proposed. The concentrator takes S3C2440 chip as its core, adopting the electric line broadband carrier technology to communicate with the collector and the GPRS technology to communicate with the management center. Its software is based on the embedded Linux operating system, adopting the multi-channel I/O multiplexing technology and the embedded database technology to realize the receiving, transmitting and storage of user data. For low-voltage electric line, the automatic relay routing algorithm with relay constrains is employed for meter reading. The operating experience indicates that,the concentrator based on electric line broadband carrier has fast transmission speed,high reliability, excellent real-time performance and low operating cost, and the automatic relay routing algorithm with relay constrains improves the meter reading efficiency.%针对国内目前低压电力线抄表系统中采用的窄带载波集中器及人工中继路由方式,提出了基于电力线宽带载波的集中器设计方案及自动中继路由算法.宽带载波集中器硬件是以S3C2440为核心,采用电力线宽带载波技术与采集器通信、通用分组无线服务(GPRS)技术与管理中心通信;软件是基于嵌入式Linux操作系统设计,采用多路I/0复用技术以及嵌入式数据库技术实现对用户电量的接收、转发及存储.同时依据低压电力线的特点,采用具有中继约束条件的自动中继路由算法实现用户电量的抄收.运行经验和实践表明:宽带载波集中器具有传输速率快、可靠性高、实时性强和运行费用低等优点;具有中继约束条件的自动中继路由算法能有效缩短自动中继的时间,提高抄表效率.

  3. Therapeutic Efficacy of pH-Dependent Release Formulation of Mesalazine on Active Ulcerative Colitis Resistant to Time-Dependent Release Formulation: Analysis of Fecal Calprotectin Concentration

    Directory of Open Access Journals (Sweden)

    Kousaku Kawashima

    2014-01-01

    Full Text Available Purpose. Few reports have compared the clinical efficacy of a pH-dependent release formulation of mesalazine (pH-5-ASA with a time-dependent release formulation (time-5-ASA. We examined whether pH-5-ASA is effective for active ulcerative colitis (UC in patients resistant to time-5-ASA. Methods. We retrospectively and prospectively analyzed the efficacy of pH-5-ASA in mildly to moderately active UC patients in whom time-5-ASA did not successfully induce or maintain remission. The clinical efficacy of pH-5-ASA was assessed by clinical activity index (CAI before and after switching from time-5-ASA. In addition, the efficacy of pH-5-ASA on mucosal healing (MH was evaluated in a prospective manner by measuring fecal calprotectin concentration. Results. Thirty patients were analyzed in a retrospective manner. CAI was significantly reduced at both 4 and 8 weeks after switching to pH-5-ASA. In the prospective study (n=14, administration of pH-5-ASA also significantly reduced CAI scores at 4 and 8 weeks in these patients who were resistant to time-5-ASA. In addition, fecal calprotectin concentration was significantly decreased along with improvement in CAI after switching to pH-5-ASA. Conclusions. Our results suggest that pH-5-ASA has clinical efficacy for mildly to moderately active patients with UC in whom time-5-ASA did not successfully induce or maintain remission.

  4. Passage and concentration-dependent effects of Indomethacin on tendon derived cells

    Directory of Open Access Journals (Sweden)

    Scutt Andy

    2009-04-01

    Full Text Available Abstract Background Non-steroidal anti-inflammatory drugs (NSAID are commonly used in the treatment of tendinopathies such as tendonitis and tendinosis. Despite this, little is known of their direct actions on tendon-derived cells. As NSAIDs have been shown to delay healing in a number of mesenchymal tissues we have investigated the direct effects of indomethacin on the proliferation of tendon-derived cells. Results and Discussion The results obtained were dependent on both the type of cells used and the method of measurement. When measured using the Alamar blue assay, a common method for the measurement of cell proliferation and viability, no effect of indomethacin was seen regardless of cell source. It is likely that this lack of effect was due to a paucity of mitochondrial enzymes in tendon cells. However, when cell number was assessed using the methylene blue assay, which is a simple nuclear staining technique, an Indomethacin-induced inhibition of proliferation was seen in primary cells but not in secondary subcultures. Conclusion These results suggest that firstly, care must be taken when deciding on methodology used to investigate tendon-derived cells as these cells have a quite different metabolism to other mesenchymal derive cells. Secondly, Indomethacin can inhibit the proliferation of primary tendon derived cells and that secondary subculture selects for a population of cells that is unresponsive to this drug.

  5. A review of carrier thermoelectric-transport theory in organic semiconductors.

    Science.gov (United States)

    Lu, Nianduan; Li, Ling; Liu, Ming

    2016-07-20

    Carrier thermoelectric-transport theory has recently become of growing interest and numerous thermoelectric-transport models have been proposed for organic semiconductors, due to pressing current issues involving energy production and the environment. The purpose of this review is to provide a theoretical description of the thermoelectric Seebeck effect in organic semiconductors. Special attention is devoted to the carrier concentration, temperature, polaron effect and dipole effect dependence of the Seebeck effect and its relationship to hopping transport theory. Furthermore, various theoretical methods are used to discuss carrier thermoelectric transport. Finally, an outlook of the remaining challenges ahead for future theoretical research is provided.

  6. Dependence of reaction rate of pyrite oxidation on temperature, pH and oxidant concentration

    Institute of Scientific and Technical Information of China (English)

    LU; Long; WANG; Rucheng; XUE; Jiyue; CHEN; Fanrong; CHEN; J

    2005-01-01

    The kinetic sstudy of pyrite oxidation was performed in a series of experiments by a mixed flow reactor. The release rates of Fe(II) are in the order of 3.22×10-9-5.51×10-7 mol·m-2·s-1 at temperature (T ) 25 to 44℃, initial pH (pH )1.4 to 2.7, and initial Fe(III) concentration ([Fe(III)]I) 10-5 to 5×10-3 mol·kg-1. The release rate of Fe(II) increased with increasing T or/and pH or/and [Fe(III)]I in the above range. The rate law and activation energy of pyrite oxidation were derived by statistical analyses of Rfe(II) vs. [Fe(III)]I, Rfe(II) vs. pH and Rfe(II) vs. T, and are given as (1) Rate law: Rfe(II)=104.65e-64.54×103/8.31T[Fe(III)]i0.6./[H+]0.45 ; (2) activation energy: 64.54 ( 8.07 kJ·mol-1. The expression can be applied to more cases (e.g., quantifying the pollutant released from sulfide-rich mining waste and assessing reliable performance of underground repository sites where pyrite acts as an engineered barrier material). Using the rate law derived from this study, the magnitude of the pollutants transferred to secondary phases, soil and water from oxidized pyrite during Jiguanshan mine waste weathering was preliminarily estimated. The estimated magnitude is very high, suggesting that the pile has possibly posed significant impact on the water quality in this region.

  7. Turbulent Concentration of mm-Size Particles in the Protoplanetary Nebula: Scale-Dependent Cascades

    Science.gov (United States)

    Cuzzi, J. N.; Hartlep, T.

    2015-01-01

    The initial accretion of primitive bodies (here, asteroids in particular) from freely-floating nebula particles remains problematic. Traditional growth-by-sticking models encounter a formidable "meter-size barrier" (or even a mm-to-cm-size barrier) in turbulent nebulae, making the preconditions for so-called "streaming instabilities" difficult to achieve even for so-called "lucky" particles. Even if growth by sticking could somehow breach the meter size barrier, turbulent nebulae present further obstacles through the 1-10km size range. On the other hand, nonturbulent nebulae form large asteroids too quickly to explain long spreads in formation times, or the dearth of melted asteroids. Theoretical understanding of nebula turbulence is itself in flux; recent models of MRI (magnetically-driven) turbulence favor low-or- no-turbulence environments, but purely hydrodynamic turbulence is making a comeback, with two recently discovered mechanisms generating robust turbulence which do not rely on magnetic fields at all. An important clue regarding planetesimal formation is an apparent 100km diameter peak in the pre-depletion, pre-erosion mass distribution of asteroids; scenarios leading directly from independent nebula particulates to large objects of this size, which avoid the problematic m-km size range, could be called "leapfrog" scenarios. The leapfrog scenario we have studied in detail involves formation of dense clumps of aerodynamically selected, typically mm-size particles in turbulence, which can under certain conditions shrink inexorably on 100-1000 orbit timescales and form 10-100km diameter sandpile planetesimals. There is evidence that at least the ordinary chondrite parent bodies were initially composed entirely of a homogeneous mix of such particles. Thus, while they are arcane, turbulent concentration models acting directly on chondrule size particles are worthy of deeper study. The typical sizes of planetesimals and the rate of their formation can be

  8. Concentration-Dependent Protection by Ethanol Extract of Propolis against γ-Ray-Induced Chromosome Damage in Human Blood Lymphocytes

    Directory of Open Access Journals (Sweden)

    A. Montoro

    2011-01-01

    Full Text Available Radioprotection with natural products may be relevant to the mitigation of ionizing radiation-induced damage in mammalian systems; in this sense, propolis extracts have shown effects such as antioxidant, antitumoral, anti-inflammatory, and immunostimulant. We report for the first time a cytogenetic study to evaluate the radioprotective effect, in vitro, of propolis against radiation-induced chromosomal damage. Lymphocytes were cultured with increasing concentrations of ethanol extract of propolis (EEP, including 20, 40, 120, 250, 500, 750, 1000, and 2000 μg mL−1 and then exposed to 2 Gy γ-rays. A significant and concentration-dependent decrease is observed in the frequency of chromosome aberrations in samples treated with EEP. The protection against the formation of dicentrics was concentration-dependent, with a maximum protection at 120 μg mL−1 of EEP. The observed frequency of dicentrics is described as negative exponential function, indicating that the maximum protectible fraction of dicentrics is approximately 44%. Free radical scavenging and antioxidant activities are the mechanisms that these substances use to protect cells from ionizing radiation.

  9. [The effects of the microwaves on E. coli cells depend on oxygen concentration and static magnetic field].

    Science.gov (United States)

    Ushakov, V L; Alipov, E D; Shcheglov, V S; Beliaev, I Ia

    2006-01-01

    The effects of non-thermal microwaves (MW), 10(-4) and 10(-10) W/cm(2), on conformation of nucleoids in E. coli cells were analyzed by the method of anomalous viscosity time dependence (AVTD). MW exposure was performed at different values of static magnetic field and concentration of oxygen, 8-90 microT, and 2.3-7.8 mg/l, respectively. It was shown, that slight changes in both static magnetic field and oxygen concentration result in significant changes of MW effects up to their disappearance. It was established, that changes in static magnetic field affected significantly the time kinetics of the MW effects. The obtained data provide further evidence for strong dependence of the effects of non-thermal microwaves on physical parameters of exposure and physiological factors. These dependences should be taken into account in replication studies. The obtained results encourage further investigation of possible modulation of non-thermal MW effects by additional electromagnetic fields.

  10. METABOLIC PARAMETERS CONCENTRATIONS IN BLOOD SERUM OF CZECH PIED BULLS DEPENDING ON SINGLE NUCLEOTIDE POLYMORPHISM OF LEPTIN GENE

    Directory of Open Access Journals (Sweden)

    Aleš Pavlík

    2014-02-01

    Full Text Available The aim of present study was to test hypothesis, that the leptin gene single nucleotide polymorphism (C/T giving missense mutation (Arg25Cys has an effect on concentration of blood serum total cholesterol, beta-hydroxybutyrate and urea in cattle. The experiment were performed in 58 Czech Pied bulls at 240 ± 9 days of age, which were divided in three experimental groups depending on different leptin genotypes (CC, n=28; CT, n=21; TT, n=9. Resulting genotypes in the exon 2 were CC (48.3%, CT (36.2%, and TT (15.5%. There were no differences in serum total cholesterol, urea, beta-hydroxybutyrate concentrations among the genotypes. Based on our results we may assume that analysed SNP of leptin gene have no effect on nutritional status and energy balance in fattened cattle.

  11. Analysis of the phosphorescent dye concentration dependence of triplet-triplet annihilation in organic host-guest systems

    Science.gov (United States)

    Zhang, L.; van Eersel, H.; Bobbert, P. A.; Coehoorn, R.

    2016-10-01

    Using a novel method for analyzing transient photoluminescence (PL) experiments, a microscopic description is obtained for the dye concentration dependence of triplet-triplet annihilation (TTA) in phosphorescent host-guest systems. It is demonstrated that the TTA-mechanism, which could be a single-step dominated process or a diffusion-mediated multi-step process, can be deduced for any given dye concentration from a recently proposed PL intensity analysis. A comparison with the results of kinetic Monte Carlo simulations provides the TTA-Förster radius and shows that the TTA enhancement due to triplet diffusion can be well described in a microscopic manner assuming Förster- or Dexter-type energy transfer.

  12. Associations between Cigarette Smoking and Total Mortality Differ Depending on Serum Concentrations of Persistent Organic Pollutants among the Elderly

    Science.gov (United States)

    Lee, Yu-Mi; Bae, Sang-Geun; Lee, Seon-Hwa; Jacobs, David R.

    2013-01-01

    There are substantial variations of relative risks (RR) in smoking-related mortality by country and time. We hypothesized the RRs in smoking-related mortality might differ depending on serum concentrations of persistent organic pollutants (POPs). We evaluated the associations of cigarette smoking with total mortality in 610 elderly (aged ≥ 70 yr) (702 elderly for organochlorine pesticides [OCPs]) after stratification by serum concentration of POPs, in the National Health and Nutrition Examination Survey (NHANES) 1999-2004 followed through 2006. Summary measures of POPs subclasses showed significant or marginally significant interaction with cigarette smoking on the risk of total mortality. P values for interaction were 0.069 for polychlorinated dibenzo-p-dioxins (PCDDs), 0.008 for polychlorinated biphenyls (PCBs), and 0.024 for OCPs. The effect of smoking on total mortality showed different patterns according to the serum concentration of some POPs. Former or current smokers had 1.4 to 2.9 times higher mortality rates compared with never smokers among participants with higher serum concentrations of POPs (2nd or 3rd tertiles). However, when the level of PCBs or OCPs were low (1st tertile), there were little positive associations between smoking and mortality. Our study suggests that the background exposure to several POPs may be related to variability in smoking-related total mortality. PMID:23960436

  13. Temperature- and concentration-dependence of kainate-induced y oscillation in rat hippocampal slices under submerged condition

    Institute of Scientific and Technical Information of China (English)

    Cheng-biao LU; Zhi-hua WANG; Yan-hong ZHOU; Martin VREUGDENHIL

    2012-01-01

    Aim:Fast neuronal network oscillation at the y frequency band (y oscillation:30-80 Hz) has been studied extensively in hippocampal slices under interface recording condition.The aim of this study is to establish a method for recording Y oscillation in submerged hippocampal slices that allows simultaneously monitoring Y oscillation and the oscillation-related intracellular events,such as intracellular Ca2+ concentration or mitochondrial membrane potentials.Methods:Horizontal hippocampal slices (thickness:300 pm) of adult rats were prepared and placed in a submerged or an interface chamber.Extracellular field recordings Were made in the CA3c pyramidal layer of the slices.Kainate,an AMPA/kainate receptor agonist,was applied via perfusion.Data analysis was performed off-line.Results:Addition of kainate (25-1000 nmol/L) induced Y oscillation in both the submerged and interface slices.Kainate increased the Y power in a concentration-dependent manner,but the duration of steady state oscillation was reduced at higher concentrations of kainate.Long-lasting Y oscillation was maintained at the concentrations of 100-300 nmol/L.Under submerged condition,Y oscillation was temperature-dependent,with the maximum power achieved at 29℃.The induction of Y oscillation under submerged condition also required a fast rate of perfusion (5-7 mL/min) and showed a fast dynamic during development and after the washout.Conclusion:The kainite-induced Y oscillation recorded in submerged rat hippocampal slices is useful for studying the intracellular events related to neuronal network activities and may represent a model to reveal the mechanisms underlying the normal neuronal synchronizations and diseased conditions.

  14. Alpha-amylase inhibitor, CS-1036 binds to serum amylase in a concentration-dependent and saturable manner.

    Science.gov (United States)

    Honda, Tomohiro; Kaneno-Urasaki, Yoko; Ito, Takashi; Kimura, Takako; Matsushima, Nobuko; Okabe, Hiromi; Yamasaki, Atsushi; Izumi, Takashi

    2014-03-01

    (2R,3R,4R)-4-hydroxy-2-(hydroxymethyl)pyrrolidin-3-yl 4-O-(6-deoxy-β-D-glucopyranosyl)-α-D-glucopyranoside (CS-1036), which is an α-amylase inhibitor, exhibited biphasic and sustained elimination with a long t1/2 (18.4-30.0 hours) in rats and monkeys, but exhibited a short t1/2 (3.7-7.9 hours) in humans. To clarify the species differences in the t1/2, the plasma protein binding of CS-1036 was evaluated by ultrafiltration. A concentration-dependent and saturable plasma protein binding of CS-1036 was observed in rats and monkeys with the dissociation rate constant (KD) of 8.95 and 27.2 nM, and maximal binding capacity (Bmax) of 52.8 and 22.1 nM, respectively. By the assessments of the recombinant amylase and immunoprecipitation, the major binding protein of CS-1036 in rats was identified as salivary amylase (KD 5.64 nM). CS-1036 also showed concentration-dependent and saturable binding to human salivary and pancreatic amylase, with similar binding affinity in rats. However, the protein binding of CS-1036 was constant in human plasma (≤10.2%) due to the lower serum amylase level compared with rats and monkeys. From the calculation of the unbound fraction (fu) in plasma based on in vitro KD and Bmax, the dose-dependent increase in fu after oral administration is speculated to lead to a dose-dependent increase in total body clearance and a high area under the curve/dose at lower doses, such as 0.3 mg/kg in rats.

  15. Concentration- and age-dependent effects of chronic caffeine on contextual fear conditioning in C57BL/6J mice.

    Science.gov (United States)

    Poole, Rachel L; Braak, David; Gould, Thomas J

    2016-02-01

    Chronic caffeine exerts negligible effects on learning and memory in normal adults, but it is unknown whether this is also true for children and adolescents. The hippocampus, a brain region important for learning and memory, undergoes extensive structural and functional modifications during pre-adolescence and adolescence. As a result, chronic caffeine may have differential effects on hippocampus-dependent learning in pre-adolescents and adolescents compared with adults. Here, we characterized the effects of chronic caffeine and withdrawal from chronic caffeine on hippocampus-dependent (contextual) and hippocampus-independent (cued) fear conditioning in pre-adolescent, adolescent, and adult mice. The results indicate that chronic exposure to caffeine during pre-adolescence and adolescence enhances or impairs contextual conditioning depending on concentration, yet has no effect on cued conditioning. In contrast, withdrawal from chronic caffeine impairs contextual conditioning in pre-adolescent mice only. No changes in learning were seen for adult mice for either the chronic caffeine or withdrawal conditions. These findings support the hypothesis that chronic exposure to caffeine during pre-adolescence and adolescence can alter learning and memory and as changes were only seen in hippocampus-dependent learning, which suggests that the developing hippocampus may be sensitive to the effects of caffeine.

  16. Defect-dependent carrier transport behavior of polymer:ZnO composites/electrodeposited CdS/indium tin oxide devices

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yow-Jon, E-mail: rzr2390@yahoo.com.tw; You, C. F. [Institute of Photonics, National Changhua University of Education, Changhua 500, Taiwan (China)

    2015-07-28

    Currents through the poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) and ZnO nanoparticles (PEDOT:PSS:ZnO)/CdS/indium tin oxide (ITO) hetero-structures are studied. The authors introduced the electrodeposition technique with sulfide treatment to improve the film quality of CdS. It is shown that sulfide treatment leads to a reduction in the number of donor-like defects (that is, sulfur vacancies and cadmium interstitials) in the CdS films, which leads to the conversion of carrier transport behavior from Poole-Frenkel emission to thermionic emission-diffusion for PEDOT:PSS:ZnO/CdS/ITO devices. A correlation is identified for providing a guide to control the current transport behavior of PEDOT:PSS:ZnO/CdS/ITO devices.

  17. Defect-dependent carrier transport behavior of polymer:ZnO composites/electrodeposited CdS/indium tin oxide devices

    Science.gov (United States)

    Lin, Yow-Jon; You, C. F.

    2015-07-01

    Currents through the poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) and ZnO nanoparticles (PEDOT:PSS:ZnO)/CdS/indium tin oxide (ITO) hetero-structures are studied. The authors introduced the electrodeposition technique with sulfide treatment to improve the film quality of CdS. It is shown that sulfide treatment leads to a reduction in the number of donor-like defects (that is, sulfur vacancies and cadmium interstitials) in the CdS films, which leads to the conversion of carrier transport behavior from Poole-Frenkel emission to thermionic emission-diffusion for PEDOT:PSS:ZnO/CdS/ITO devices. A correlation is identified for providing a guide to control the current transport behavior of PEDOT:PSS:ZnO/CdS/ITO devices.

  18. The Concentration Dependence of the (Delta)s Term in the Gibbs Free Energy Function: Application to Reversible Reactions in Biochemistry

    Science.gov (United States)

    Gary, Ronald K.

    2004-01-01

    The concentration dependence of (delta)S term in the Gibbs free energy function is described in relation to its application to reversible reactions in biochemistry. An intuitive and non-mathematical argument for the concentration dependence of the (delta)S term in the Gibbs free energy equation is derived and the applicability of the equation to…

  19. N2O production by ammonia oxidizing bacteria in an enriched nitrifying sludge linearly depends on inorganic carbon concentration.

    Science.gov (United States)

    Peng, Lai; Ni, Bing-Jie; Ye, Liu; Yuan, Zhiguo

    2015-05-01

    The effect of inorganic carbon (IC) on nitrous oxide (N2O) production by ammonia oxidizing bacteria (AOB) was investigated over a concentration range of 0-12 mmol C/L, encompassing typical IC levels in a wastewater treatment reactors. The AOB culture was enriched along with nitrite-oxidizing bacteria (NOB) in a sequencing batch reactor (SBR) to perform complete nitrification. Batch experiments were conducted with continuous carbon dioxide (CO2) stripping or at controlled IC concentrations. The results revealed a linear relationship between N2O production rate (N2OR) and IC concentration (R(2) = 0.97) within the IC range studied, suggesting a substantial effect of IC on N2O production by AOB. Similar results were also obtained with an AOB culture treating anaerobic sludge digestion liquor. The fundamental mechanism responsible for this dependency is unclear; however, in agreement with previous studies, it was observed that the ammonia oxidation rate (AOR) was also influenced by the IC concentration, which could be well described by the Monod kinetics. These resulted in an exponential relationship between N2OR and AOR, as previously observed in experiments where AOR was altered by varying dissolved oxygen and ammonia concentrations. It is therefore possible that IC indirectly affected N2OR by causing a change in AOR. The observation in this study indicates that alkalinity (mostly contributed by IC) could be a significant factor influencing N2O production and should be taken into consideration in estimating and mitigating N2O emissions in wastewater treatment systems.

  20. Stoichiometry dependence of the optical and minority-carrier lifetime behaviors of CdTe epitaxial films: A low-temperature and time-resolved photoluminescence study

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Kai; Zhu, Xuanting; Zhu, Liangqing; Bai, Wei, E-mail: wbai@mail.sitp.ac.cn; Bai, Jiawei; Dong, Wenxia; Yang, Jing; Zhang, Yuanyuan; Chen, Ye; Tang, Xiaodong, E-mail: xdtang@clpm.ecnu.edu.cn; Chu, Junhao

    2016-11-30

    Highlights: • CdTe epitaxial films with various defect levels were grown by MBE. • Defect levels of the MBE-grown CTEFs were clarified by low-temperature PL. • TRPL supports the minority-carrier lifetime in Cd-rich ambient can be prolonged. - Abstract: Cadmium telluride (CdTe) epitaxial films (EFs) were grown on near-lattice-matched Cd{sub 0.96}Zn{sub 0.04}Te (CZT) substrates by molecular beam epitaxy at different ambients to achieve Cd-rich samples with extra Cd molecular flux or Te-rich samples with extra Te molecular flux. The evolution of epitaxial growth was in situ monitored by reflection high-energy electron diffraction (RHEED). A two-dimensional growth mode was indicated by the streaky RHEED patterns. Crystal structures of the CdTe EFs were characterised by X-ray diffraction (XRD). XRD data suggested that the crystal quality of the CdTe EFs was improved by controlling the Cd and Te flux ratio. Low-temperature photoluminescence (PL) spectra were carried out in these CdTe EFs. The typical characteristic peak at ∼1.552 eV denoted as the bound-to-free transition was only found in CdTe samples grown under an extra Cd flux, and Cd vacancy-related defects were absent in the Cd-rich EFs, confirming the Cd-rich or Te-rich states of the epitaxial CdTe films. Finally, minority-carrier lifetime was prolonged in Cd-rich CdTe EFs as supported by time-resolved photoluminescence (TRPL) measurement.

  1. Submicromolar concentrations of zinc irreversibly reduce a calcium-dependent potassium current in rat hippocampal neurons in vitro.

    Science.gov (United States)

    Sim, J A; Cherubini, E

    1990-01-01

    The action of the endogenous divalent cation zinc on Ca2+ and Ca2(+)-dependent currents was studied in rat hippocampal CA1 and CA3 neurons in vitro, by means of a single electrode voltage clamp technique. Bath application of zinc (0.5-1 microM) produced a small membrane depolarization associated with an increase in synaptic noise and cell excitability and a depression of the afterhyperpolarization following a train of action potentials. The effects on the afterhyperpolarization, could not be reversed on washout. In voltage-clamped neurons, zinc induced a steady inward current and reduced, at resting membrane potential, the peak amplitude of the outward current underlying the afterhyperpolarization, IAHP. In caesium loaded neurons (in the presence of tetrodotoxin and tetraethylammonium), zinc reduced the slow inactivating Ca2+ current activated from a holding potential of -40 mV. Similar results were observed with nickel and cobalt at comparable concentrations, with Zn2+ greater than Ni2+ greater than Co2+, in their order of potency. In contrast to nickel and cobalt the effects of zinc did not reverse on washout. These results suggest that low concentrations of zinc enhance cell excitability by reducing IAHP. In addition, zinc reduces the slow inactivating voltage-dependent Ca2+ current. The irreversible effect of this metal ion is compatible with a toxic, intracellular site of action.

  2. Charge carrier transport in Cu(In,Ga)Se{sub 2} thin-film solar-cells studied by electron beam induced current and temperature and illumination dependent current voltage analysis

    Energy Technology Data Exchange (ETDEWEB)

    Nichterwitz, Melanie

    2012-01-10

    This work contributes to the understanding of generation dependent charge-carrier transport properties in Cu(In,Ga)Se{sub 2} (CIGSe)/ CdS/ ZnO solar cells and a consistent model for the electronic band diagram of the heterojunction region of the device is developed. Cross section electron-beam induced current (EBIC) and temperature and illumination dependent current voltage (IV) measurements are performed on CIGSe solar cells with varying absorber layer compositions and CdS thickness. For a better understanding of possibilities and limitations of EBIC measurements applied on CIGSe solar cells, detailed numerical simulations of cross section EBIC profiles for varying electron beam and solar cell parameters are performed and compared to profiles obtained from an analytical description. Especially the effects of high injection conditions are considered. Even though the collection function of the solar cell is not independent of the generation function of the electron beam, the local electron diffusion length in CIGSe can still be extracted. Grain specific values ranging from (480±70) nm to (2.3±0.2) μm are determined for a CuInSe{sub 2} absorber layer and a value of (2.8±0.3) μm for CIGSe with a Ga-content of 0.3. There are several models discussed in literature to explain generation dependent charge carrier transport, all assuming a high acceptor density either located in the CIGSe layer close to the CIGSe/CdS interface (p{sup +} layer), within the CdS layer or at the CdS/ZnO interface. In all models, a change in charge carrier collection properties is caused by a generation dependent occupation probability of the acceptor type defect state and the resulting potential distribution throughout the device. Numerical simulations of EBIC and IV data are performed with parameters according to these models. The model that explains the experimental data best is that of a p{sup +} layer at the CIGSe/CdS interface and acceptor type defect states at the CdS/ZnO interface

  3. Dependence of bisphenol A photodegradation on the initial concentration of oxalate in the lepidocrocite-oxalate complex system

    Institute of Scientific and Technical Information of China (English)

    DONG Jun; LI Fang-bai; LAN Chong-yu; LIU Cheng-shuai; LI Xiao-min; LUAN Tian-gang

    2006-01-01

    To understand the degradation of endocrine disrupting chemicals (EDCs) in natural environment with existence of iron oxides and carboxylic acids, the dependence ofbisphenol A (BPA) photodegradation on the initial concentration ofoxalate (Cox) in lepidocrocite (γ-FeOOH) aqueous suspension was investigated under both UV and visible lights in this study. Lepidocrocite powder was home-prepared by a hydrothermal process. It was found that BPA degradation was promoted greatly in the presence of oxalate owing to the formation of lepidocrocite-oxalate complex. And there was an optimal Cox, which was 2.0 and 2.4 mmol/L, under UV and visible lights, respectively. The first-order kinetic constant, k value increased 38 times from 0.17 × 10-2 min-1 in the absence of oxalate to 6.39 × 10-2 min-1 in the presence ofoxalate with an optimal Cox (2.0 mmol/L) under UV irradiation, and almost 306 times from 0.02 × 10-2 min-1 in the absence ofoxalate to 6.11 × 10-2 min-1 in the presence of oxalate with an optimal Cox (2.4 mmol/L) under visible irradiation. The BPA degradation rate increased and the first-order kinetic constants decreased with the increase in BPA initial concentration. The dependence of the variation of pH value, total-Fe and Fe2+ during the photoreaction on Cox was also investigated.The pH value increased obviously with the reaction time. Total-Fe increased dramatically at the first 5 min and then decreased quickly under UV irradiation and slowly under visible irradiation. The initial concentration of oxalate is a main factor to affect BPA photodegradation in aqueous suspension under both UV and visible lights.

  4. Concentration-dependent study of electronic and optical properties of c-Si and c-Si:H

    Energy Technology Data Exchange (ETDEWEB)

    Nunez-Gonzalez, R. [Departamento de Matematicas, Universidad de Sonora, C.P. 83000, Hermosillo, Sonora (Mexico); Posada-Amarillas, A. [Departamento de Investigacion en Fisica, Universidad de Sonora, Apdo. Postal 5-088 C.P. 83190, Hermosillo, Sonora (Mexico); Galvan, D.H.; Reyes-Serrato, A. [Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autonoma de Mexico, Ensenada, B. C. (Mexico)

    2011-07-15

    Electronic and optical properties of crystalline silicon (c-Si) and hydrogen-doped crystalline silicon (c-Si:H) were calculated using the full-potential linearized augmented plane waves (FLAPWs) method, within the density functional theory (DFT), and the supercell method to model different hydrogen concentrations. Hydrogen was introduced in both bond-centered (BC) and tetrahedral (Td) interstitial sites to find out the most favorable configuration by searching for the lowest energy structure. The Td interstitial site yields the most stable and lowest energy structure. For several hydrogen concentrations we found that the effect of interstitial hydrogen is to introduce electronic states at the silicon band gap, turning it into a metallic system. Analysis of the calculated energy-loss function of doped silicon shows the existence of a plasmon peak at low energy of the loss spectrum, and the position of this plasmon peak is highly dependent on hydrogen concentration into silicon. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Taxol induces concentration-dependent phosphatidylserine (PS) externalization and cell cycle arrest in ASTC-a-1 cells

    Science.gov (United States)

    Guo, Wen-jing; Chen, Tong-sheng

    2010-02-01

    Taxol (Paclitaxel) is an important natural product for the treatment of solid tumors. Different concentrations of taxol can trigger distinct effects on both the cellular microtubule network and biochemical pathways. Apoptosis induced by low concentrations (5-30 nM) of taxol was associated with mitotic arrest, alteration of microtubule dynamics and/or G2/M cell cycle arrest, whereas high concentrations of this drug (0.2-30 μM) caused significant microtubule damage, and was found recently to induce cytoplasm vacuolization in human lung adenocarcinoma (ASTC-a-1) cells. In present study, cell counting kit (CCK-8) assay, confocal microscope, and flow cytometry analysis were used to analyze the cell death form induced by 35 nM and 70 μM of taxol respectively in human lung adenocarcinoma (ASTC-a-1) cells. After treatment of 35 nM taxol for 48 h, the OD450 value was 0.80, and 35 nM taxol was found to induce dominantly cell death in apoptotic pathway such as phosphatidylserine (PS) externalization, G2/M phase arrest after treatment for 24 h, and nuclear fragmentation after treatment for 48 h. After 70 μM taxol treated the cell for 24 h, the OD450 value was 1.01, and 70 μM taxol induced cytoplasm vacuolization programmed cell death (PCD) and G2/M phase as well as the polyploidy phase arrest in paraptotic-like cell death. These findings imply that the regulated signaling pathway of cell death induced by taxol is dependent on taxol concentration in ASTC-a-1 cells.

  6. Ethanol-Induced ADH Activity in Zebrafish: Differential Concentration-Dependent Effects on High- Versus Low-Affinity ADH Enzymes.

    Science.gov (United States)

    Tran, Steven; Nowicki, Magda; Facciol, Amanda; Chatterjee, Diptendu; Gerlai, Robert

    2016-04-01

    Zebrafish express enzymes that metabolize ethanol in a manner comparable to that of mammals, including humans. We previously demonstrated that acute ethanol exposure increases alcohol dehydrogenase (ADH) activity in an inverted U-shaped dose-dependent manner. It was hypothesized that the biphasic dose-response was due to the increased activity of a high-affinity ADH isoform following exposure to low concentrations of ethanol and increased activity of a low-affinity ADH isoform following exposure to higher concentrations of ethanol. To test this hypothesis, we exposed zebrafish to different concentrations of ethanol (0%, 0.25%, 0.5%, and 1.0% v/v) for 30 min and measured the total ADH activity in the zebrafish liver. However, we also repeated this enzyme activity assay using a low concentration of the substrate (ethanol) to determine the activity of high-affinity ADH isoforms. We found that total ADH activity in response to ethanol induces an inverted U-shaped dose-response similar to our previous study. Using a lower substrate level in our enzyme assay targeting high-affinity isozymes, we found a similar dose-response. However, the difference in activity between the high and low substrate assays (high substrate activity - low substrate activity), which provide an index of activity for low-affinity ADH isoforms, revealed no significant effect of ethanol exposure. Our results suggest that the inverted U-shaped dose-response for total ADH activity in response to ethanol is driven primarily by high-affinity isoforms of ADH.

  7. CSF glutamate/GABA concentrations in pyridoxine-dependent seizures: etiology of pyridoxine-dependent seizures and the mechanisms of pyridoxine action in seizure control.

    Science.gov (United States)

    Goto, T; Matsuo, N; Takahashi, T

    2001-03-01

    Several lines of evidence suggest that the binding affinity of glutamate decarboxylase (GAD) to the active form of pyridoxine is low in cases of pyridoxine-dependent seizures (PDS) and that a quantitative imbalance between excitatory (i.e. glutamate) and inhibitory (i.e. gamma-aminobutyric acid, GABA) neurotransmitters could cause refractory seizures. However, inconsistent findings with GAD insufficiency have been reported in PDS. We report a case of PDS that is not accompanied by an elevated cerebrospinal fluid (CSF) glutamate concentration. Intravenous pyridoxine phosphate terminated generalized seizures which were otherwise refractory to conventional anti-epileptic medicines. No seizure occurred once oral pyridoxine (13.5 mg/kg per day) was started in combination with phenobarbital sodium (PB, 3.7 mg/kg per day). The electroencephalogram (EEG) normalized approximately 8 months after pyridoxine was started. The patient is gradually acquiring developmental milestones during the 15 months follow-up period. The CSF glutamate and GABA concentrations were determined on three separate occasions: (1) during status epilepticus; (2) during a seizure-free period with administration of pyridoxine and PB; and (3) 6 days after suspension of pyridoxine and PB and immediately before a convulsion. The CSF glutamate level was below the sensitivity of detection (pyridoxine supplementation, were within the normal range. We suggest that (1) PDS is not a discrete disease of single etiology in that insufficient activation of GAD may not account for seizure susceptibility in all cases and (2) mechanism(s) of anti-convulsive effect of pyridoxine, at least in some cases, may be independent of GAD activation.

  8. Stoichiometry dependence of the optical and minority-carrier lifetime behaviors of CdTe epitaxial films: A low-temperature and time-resolved photoluminescence study

    Science.gov (United States)

    Tang, Kai; Zhu, Xuanting; Zhu, Liangqing; Bai, Wei; Bai, Jiawei; Dong, Wenxia; Yang, Jing; Zhang, Yuanyuan; Chen, Ye; Tang, Xiaodong; Chu, Junhao

    2016-11-01

    Cadmium telluride (CdTe) epitaxial films (EFs) were grown on near-lattice-matched Cd0.96Zn0.04Te (CZT) substrates by molecular beam epitaxy at different ambients to achieve Cd-rich samples with extra Cd molecular flux or Te-rich samples with extra Te molecular flux. The evolution of epitaxial growth was in situ monitored by reflection high-energy electron diffraction (RHEED). A two-dimensional growth mode was indicated by the streaky RHEED patterns. Crystal structures of the CdTe EFs were characterised by X-ray diffraction (XRD). XRD data suggested that the crystal quality of the CdTe EFs was improved by controlling the Cd and Te flux ratio. Low-temperature photoluminescence (PL) spectra were carried out in these CdTe EFs. The typical characteristic peak at ∼1.552 eV denoted as the bound-to-free transition was only found in CdTe samples grown under an extra Cd flux, and Cd vacancy-related defects were absent in the Cd-rich EFs, confirming the Cd-rich or Te-rich states of the epitaxial CdTe films. Finally, minority-carrier lifetime was prolonged in Cd-rich CdTe EFs as supported by time-resolved photoluminescence (TRPL) measurement.

  9. Anoxia-induced elevation of cytosolic Ca2+ concentration depends on different Ca2+ sources in rice and wheat protoplasts.

    Science.gov (United States)

    Yemelyanov, Vladislav V; Shishova, Maria F; Chirkova, Tamara V; Lindberg, Sylvia M

    2011-08-01

    The anoxia-dependent elevation of cytosolic Ca(2+) concentration, [Ca(2+)](cyt), was investigated in plants differing in tolerance to hypoxia. The [Ca(2+)](cyt) was measured by fluorescence microscopy in single protoplasts loaded with the calcium-fluoroprobe Fura 2-AM. Imposition of anoxia led to a fast (within 3 min) significant elevation of [Ca(2+)](cyt) in rice leaf protoplasts. A tenfold drop in the external Ca(2+) concentration (to 0.1 mM) resulted in considerable decrease of the [Ca(2+)](cyt) shift. Rice root protoplasts reacted upon anoxia with higher amplitude. Addition of plasma membrane (verapamil, La(3+) and EGTA) and intracellular membrane Ca(2+)-channel antagonists (Li(+), ruthenium red and cyclosporine A) reduced the anoxic Ca(2+)-accumulation in rice. Wheat protoplasts responded to anoxia by smaller changes of [Ca(2+)](cyt). In wheat leaf protoplasts, the amplitude of the Ca(2+)-shift little depended on the external level of Ca(2+). Wheat root protoplasts were characterized by a small shift of [Ca(2+)](cyt) under anoxia. Plasmalemma Ca(2+)-channel blockers had little effect on the elevation of cytosolic Ca(2+) in wheat protoplasts. Intact rice seedlings absorbed Ca(2+) from the external medium under anoxic treatment. On the contrary, wheat seedlings were characterized by leakage of Ca(2+). Verapamil abolished the Ca(2+) influx in rice roots and Ca(2+) efflux from wheat roots. Anoxia-induced [Ca(2+)](cyt) elevation was high particularly in rice, a hypoxia-tolerant species. In conclusion, both external and internal Ca(2+) stores are important for anoxic [Ca(2+)](cyt) elevation in rice, whereas the hypoxia-intolerant wheat does not require external sources for [Ca(2+)](cyt) rise. Leaf and root protoplasts similarly responded to anoxia, independent of their organ origin.

  10. Deferasirox demonstrates a dose-dependent reduction in liver iron concentration and consistent efficacy across subgroups of non-transfusion-dependent thalassemia patients.

    Science.gov (United States)

    Taher, Ali T; Porter, John B; Viprakasit, Vip; Kattamis, Antonis; Chuncharunee, Suporn; Sutcharitchan, Pranee; Siritanaratkul, Noppadol; Galanello, Renzo; Karakas, Zeynep; Lawniczek, Tomasz; Habr, Dany; Ros, Jacqueline; Zhang, Yiyun; Cappellini, M Domenica

    2013-06-01

    The 1-year THALASSA study enrolled 166 patients with various non-transfusion-dependent thalassemia (NTDT) syndromes, degrees of iron burden and patient characteristics, and demonstrated the overall efficacy and safety of deferasirox in reducing liver iron concentration (LIC) in these patients. Here, reduction in LIC with deferasirox 5 and 10 mg/kg/day starting dose groups is shown to be consistent across the following patient subgroups-baseline LIC/serum ferritin, age, gender, race, splenectomy (yes/no), and underlying NTDT syndrome (β-thalassemia intermedia, HbE/β-thalassemia or α-thalassemia). These analyses also evaluated deferasirox dosing strategies for patients with NTDT. Greater reductions in LIC were achieved in patients dose-escalated at Week 24 from deferasirox 10 mg/kg/day starting dose to 20 mg/kg/day. Patients who received an average actual dose of deferasirox >12.5-≤17.5 mg/kg/day achieved a greater LIC decrease compared with the ≥7.5-≤12.5 mg/kg/day and >0-<7.5 mg/kg/day subgroups, demonstrating a dose-response efficacy. LIC reduction across patient subgroups was generally consistent with the primary efficacy analysis with a similar safety profile.

  11. Deferasirox demonstrates a dose-dependent reduction in liver iron concentration and consistent efficacy across subgroups of non-transfusion-dependent thalassemia patients

    Science.gov (United States)

    Taher, Ali T; Porter, John B; Viprakasit, Vip; Kattamis, Antonis; Chuncharunee, Suporn; Sutcharitchan, Pranee; Siritanaratkul, Noppadol; Galanello, Renzo; Karakas, Zeynep; Lawniczek, Tomasz; Habr, Dany; Ros, Jacqueline; Zhang, Yiyun; Cappellini, M Domenica

    2013-01-01

    The 1-year THALASSA study enrolled 166 patients with various non-transfusion-dependent thalassemia (NTDT) syndromes, degrees of iron burden and patient characteristics, and demonstrated the overall efficacy and safety of deferasirox in reducing liver iron concentration (LIC) in these patients. Here, reduction in LIC with deferasirox 5 and 10 mg/kg/day starting dose groups is shown to be consistent across the following patient subgroups—baseline LIC/serum ferritin, age, gender, race, splenectomy (yes/no), and underlying NTDT syndrome (β-thalassemia intermedia, HbE/β-thalassemia or α-thalassemia). These analyses also evaluated deferasirox dosing strategies for patients with NTDT. Greater reductions in LIC were achieved in patients dose-escalated at Week 24 from deferasirox 10 mg/kg/day starting dose to 20 mg/kg/day. Patients who received an average actual dose of deferasirox >12.5–≤17.5 mg/kg/day achieved a greater LIC decrease compared with the ≥7.5–≤12.5 mg/kg/day and >0–<7.5 mg/kg/day subgroups, demonstrating a dose–response efficacy. LIC reduction across patient subgroups was generally consistent with the primary efficacy analysis with a similar safety profile. Am. J. Hematol. 88:503–506, 2013. © 2013 Wiley Periodicals, Inc. PMID:23553596

  12. Multi-regional investigation of the relationship between functional MRI blood oxygenation level dependent (BOLD activation and GABA concentration.

    Directory of Open Access Journals (Sweden)

    Ashley D Harris

    Full Text Available Several recent studies have reported an inter-individual correlation between regional GABA concentration, as measured by MRS, and the amplitude of the functional blood oxygenation level dependent (BOLD response in the same region. In this study, we set out to investigate whether this coupling generalizes across cortex. In 18 healthy participants, we performed edited MRS measurements of GABA and BOLD-fMRI experiments using regionally related activation paradigms. Regions and tasks were the: occipital cortex with a visual grating stimulus; auditory cortex with a white noise stimulus; sensorimotor cortex with a finger-tapping task; frontal eye field with a saccade task; and dorsolateral prefrontal cortex with a working memory task. In contrast to the prior literature, no correlation between GABA concentration and BOLD activation was detected in any region. The origin of this discrepancy is not clear. Subtle differences in study design or insufficient power may cause differing results; these and other potential reasons for the discrepant results are discussed. This negative result, although it should be interpreted with caution, has a larger sample size than prior positive results, and suggests that the relationship between GABA and the BOLD response may be more complex than previously thought.

  13. Visualization of carrier dynamics in p(n)-type GaAs by scanning ultrafast electron microscopy.

    Science.gov (United States)

    Cho, Jongweon; Hwang, Taek Yong; Zewail, Ahmed H

    2014-02-11

    Four-dimensional scanning ultrafast electron microscopy is used to investigate doping- and carrier-concentration-dependent ultrafast carrier dynamics of the in situ cleaved single-crystalline GaAs(110) substrates. We observed marked changes in the measured time-resolved secondary electrons depending on the induced alterations in the electronic structure. The enhancement of secondary electrons at positive times, when the electron pulse follows the optical pulse, is primarily due to an energy gain involving the photoexcited charge carriers that are transiently populated in the conduction band and further promoted by the electron pulse, consistent with a band structure that is dependent on chemical doping and carrier concentration. When electrons undergo sufficient energy loss on their journey to the surface, dark contrast becomes dominant in the image. At negative times, however, when the electron pulse precedes the optical pulse (electron impact), the dynamical behavior of carriers manifests itself in a dark contrast which indicates the suppression of secondary electrons upon the arrival of the optical pulse. In this case, the loss of energy of material's electrons is by collisions with the excited carriers. These results for carrier dynamics in GaAs(110) suggest strong carrier-carrier scatterings which are mirrored in the energy of material's secondary electrons during their migration to the surface. The approach presented here provides a fundamental understanding of materials probed by four-dimensional scanning ultrafast electron microscopy, and offers possibilities for use of this imaging technique in the study of ultrafast charge carrier dynamics in heterogeneously patterned micro- and nanostructured material surfaces and interfaces.

  14. Sub-inhibitory tigecycline concentrations induce extracellular matrix binding protein Embp dependent Staphylococcus epidermidis biofilm formation and immune evasion.

    Science.gov (United States)

    Weiser, Julian; Henke, Hanae A; Hector, Nina; Both, Anna; Christner, Martin; Büttner, Henning; Kaplan, Jeffery B; Rohde, Holger

    2016-09-01

    Biofilm-associated Staphylococcus epidermidis implant infections are notoriously reluctant to antibiotic treatment. Here we studied the effect of sub-inhibitory concentrations of penicillin, oxacillin, vancomycin, daptomycin, linezolid and tigecycline on S. epidermidis 1585 biofilm formation, expression of extracellular matrix binding protein (Embp) and potential implications for S. epidermidis - macrophage interactions. Penicillin, vancomycin, daptomycin, and linezolid had no biofilm augmenting effect at any of the concentrations tested. In contrast, at sub-inhibitory concentrations tigecycline and oxacillin exhibited significant biofilm inducing activity. In S. epidermidis 1585, SarA is a negative regulator of giant 1 MDa Embp, and down regulation of sarA induces Embp-dependent assembly of a multi-layered biofilm architecture. Dot blot immune assays, confocal laser scanning microscopy, and qPCR showed that under biofilm inducing conditions, tigecycline augmented embp expression compared to the control grown without antibiotics. Conversely, expression of regulator sarA was suppressed, suggesting that tigecycline exerts its effects on embp expression through SarA. Tigecycline failed to induce biofilm formation in embp transposon mutant 1585-M135, proving that under these conditions Embp up-regulation is necessary for biofilm accumulation. As a functional consequence, tigecycline induced biofilm formation significantly impaired the up-take of S. epidermidis by mouse macrophage-like cell line J774A.1. Our data provide novel evidence for the molecular basis of antibiotic induced biofilm formation, a phenotype associated with inherently increased antimicrobial tolerance. While this could explain failure of antimicrobial therapies, persistence of S. epidermidis infections in the presence of sub-inhibitory antimicrobials is additionally propelled by biofilm-related impairment of macrophage-mediated pathogen eradication.

  15. Concentration dependence of the wings of a dipole-broadened magnetic resonance line in magnetically diluted lattices

    Energy Technology Data Exchange (ETDEWEB)

    Zobov, V. E., E-mail: rsa@iph.krasn.ru [Russian Academy of Sciences, Kirenskii Institute of Physics, Siberian Branch (Russian Federation); Kucherov, M. M. [Siberian Federal University, Institute of Space and Information Technologies (Russian Federation)

    2017-01-15

    The singularities of the time autocorrelation functions (ACFs) of magnetically diluted spin systems with dipole–dipole interaction (DDI), which determine the high-frequency asymptotics of autocorrelation functions and the wings of a magnetic resonance line, are studied. Using the self-consistent fluctuating local field approximation, nonlinear equations are derived for autocorrelation functions averaged over the independent random arrangement of spins (magnetic atoms) in a diamagnetic lattice with different spin concentrations. The equations take into account the specificity of the dipole–dipole interaction. First, due to its axial symmetry in a strong static magnetic field, the autocorrelation functions of longitudinal and transverse spin components are described by different equations. Second, the long-range type of the dipole–dipole interaction is taken into account by separating contributions into the local field from distant and near spins. The recurrent equations are obtained for the expansion coefficients of autocorrelation functions in power series in time. From them, the numerical value of the coordinate of the nearest singularity of the autocorrelation function is found on the imaginary time axis, which is equal to the radius of convergence of these expansions. It is shown that in the strong dilution case, the logarithmic concentration dependence of the coordinate of the singularity is observed, which is caused by the presence of a cluster of near spins whose fraction is small but contribution to the modulation frequency is large. As an example a silicon crystal with different {sup 29}Si concentrations in magnetic fields directed along three crystallographic axes is considered.

  16. Dependence of RNA tertiary structural stability on Mg2+ concentration: interpretation of the Hill equation and coefficient.

    Science.gov (United States)

    Leipply, Desirae; Draper, David E

    2010-03-01

    The Mg(2+)-induced folding of RNA tertiary structures is readily observed via titrations of RNA with MgCl(2). Such titrations are commonly analyzed using a site binding formalism that includes a parameter, the Hill coefficient n, which is sometimes deemed the number of Mg(2+) ions bound by the native RNA at specific sites. However, the long-range nature of electrostatic interactions allows ions some distance from the RNA to stabilize an RNA structure. A complete description of all interactions taking place between Mg(2+) and an RNA uses a preferential interaction coefficient, Gamma(2+), which represents the "excess" Mg(2+) neutralizing the RNA charge. The difference between Gamma(2+) for the native and unfolded RNA forms (DeltaGamma(2+)) is the number of Mg(2+) ions "taken up" by an RNA upon folding. Here we determine the conditions under which the Hill coefficient n can be equated to the ion uptake DeltaGamma(2+) and find that two approximations are necessary: (i) the Mg(2+) activity coefficient is independent of concentration during a titration, and (ii) the dependence of DeltaGamma(2+) on Mg(2+) concentration is weak. Titration experiments with a Mg(2+)-binding dye and an adenine-binding riboswitch were designed to test these approximations. Inclusion of a 30-fold excess of KCl over MgCl(2) was sufficient to maintain a constant Mg(2+) activity coefficient. We also observed that Mg(2+) uptake by the RNA varied from near zero to approximately 2.6 as the Mg(2+) concentration increases over an approximately 100-fold range. It is possible to determine DeltaGamma(2+) from Mg(2+)-RNA titrations, but the values are only applicable to a limited range of solution conditions.

  17. Cell age dependent concentration of Escherichia coli divisome proteins analyzed with ImageJ and ObjectJ.

    Science.gov (United States)

    Vischer, Norbert O E; Verheul, Jolanda; Postma, Marten; van den Berg van Saparoea, Bart; Galli, Elisa; Natale, Paolo; Gerdes, Kenn; Luirink, Joen; Vollmer, Waldemar; Vicente, Miguel; den Blaauwen, Tanneke

    2015-01-01

    The rod-shaped Gram-negative bacterium Escherichia coli multiplies by elongation followed by binary fission. Longitudinal growth of the cell envelope and synthesis of the new poles are organized by two protein complexes called elongasome and divisome, respectively. We have analyzed the spatio-temporal localization patterns of many of these morphogenetic proteins by immunolabeling the wild type strain MC4100 grown to steady state in minimal glucose medium at 28°C. This allowed the direct comparison of morphogenetic protein localization patterns as a function of cell age as imaged by phase contrast and fluorescence wide field microscopy. Under steady state conditions the age distribution of the cells is constant and is directly correlated to cell length. To quantify cell size and protein localization parameters in 1000s of labeled cells, we developed 'Coli-Inspector,' which is a project running under ImageJ with the plugin 'ObjectJ.' ObjectJ organizes image-analysis tasks using an integrated approach with the flexibility to produce different output formats from existing markers such as intensity data and geometrical parameters. ObjectJ supports the combination of automatic and interactive methods giving the user complete control over the method of image analysis and data collection, with visual inspection tools for quick elimination of artifacts. Coli-inspector was used to sort the cells according to division cycle cell age and to analyze the spatio-temporal localization pattern of each protein. A unique dataset has been created on the concentration and position of the proteins during the cell cycle. We show for the first time that a subset of morphogenetic proteins have a constant cellular concentration during the cell division cycle whereas another set exhibits a cell division cycle dependent concentration variation. Using the number of proteins present at midcell, the stoichiometry of the divisome is discussed.

  18. Limitations of serum ferritin to predict liver iron concentration responses to deferasirox therapy in patients with transfusion-dependent thalassaemia.

    Science.gov (United States)

    Porter, John B; Elalfy, Mohsen; Taher, Ali; Aydinok, Yesim; Lee, Szu-Hee; Sutcharitchan, Pranee; El-Ali, Ali; Han, Jackie; El-Beshlawy, Amal

    2017-03-01

    In transfusion-dependent anaemias, while absolute serum ferritin levels broadly correlate with liver iron concentration (LIC), relationships between trends in these variables are unclear. These relationships are important because serum ferritin changes are often used to adjust or switch chelation regimens when liver magnetic resonance imaging (MRI) is unavailable. This post hoc analysis of the EPIC study compared serum ferritin and LIC in 317 patients with transfusion-dependent thalassaemia before and after 1 yr of deferasirox. Serum ferritin responses (decreases) occurred in 73% of patients, 80% of whom also have decreased LIC. However, 52% of patients without a serum ferritin response did decrease LIC and by >1 mg Fe/g dw (median 3.9) in 77% of cases. Absolute serum ferritin and LIC values correlated significantly only when serum ferritin was Serum ferritin response was accompanied by decreased LIC in 89% and 70% of cases when serum ferritin was serum ferritin non-response was associated with LIC decrease in over half of patients, use of liver MRI may be particularly useful for differentiating true from apparent non-responders to deferasirox based on serum ferritin trends alone. © 2016 The Authors. European Journal of Haematology Published by John Wiley & Sons Ltd.

  19. Current-crowded carrier confinement in double-heterostructure lasers

    Energy Technology Data Exchange (ETDEWEB)

    Joyce, W.B.

    1980-05-01

    The profiles (spatial distributions) of injected carriers and current within a double-heterostructure stripe-geometry laser are described theoretically in a one-dimensional-flow model. The one-dimensional model is solved exactly and found to yield comparatively simple analytical expresions even when both radiative (nonlinear) and nonradiative recombination are operative. In the case of a shallow proton bombardment or an oxide stripe, two coupled current components leak from under the stripe: an Ohmic current in the P layer and a diffusion current in the active region. As an example, these wasted leakage currents are evaluated in detail and seen to depend strongly upon the laser design. Features of this work not present in previous analytical studies include incorporation of radiative recombination (Bn/sup 2/) and a carrier-concentration-dependent diffusion coefficient, as well as development of a self-consistent solution for the two current components.

  20. Enzyme IIMtl of the Escherichia coli Phosphoenolpyruvate-Dependent Phosphotransferase System : Identification of the Activity-Linked Cysteine on the Mannitol Carrier

    NARCIS (Netherlands)

    Pas, H.H.; Robillard, G.T.

    1988-01-01

    The cysteines of the membrane-bound mannitol-specific enzyme II (EIIMtl) of the Escherichia coli phosphoenolpyruvate-dependent phosphotransferase system have been labeled with 4-vinylpyridine. After proteolytic breakdown and reversed-phase HPLC, the peptides containing cysteines 110, 384, and 571 co

  1. Kinetics of heterogeneous reaction of ozone with linoleic acid and its dependence on temperature, physical state, RH, and ozone concentration.

    Science.gov (United States)

    Zeng, Guang; Holladay, Sara; Langlois, Danielle; Zhang, Yunhong; Liu, Yong

    2013-03-07

    Heterogeneous reaction between ozone and linoleic acid (LA) thin film was investigated by a flow reactor coupled to attenuated total reflection infrared spectroscopy (FR-ATR-IR) over wide ranges of temperature, relative humidity (RH), and ozone concentration under atmospheric pressure condition. Pseudo-first-order rate constants kapp and overall reactive uptake coefficients γ were acquired on the basis of changes in absorbance from peaks located near 1743, 1710, 1172, and 1110 cm(-1), which can be assigned to C═O in ester, C═O in acid, and C-C and C-O stretching modes, respectively. Results showed that the kapp and γ increased nearly by a factor of 6 with increasing temperatures from 258 to 314 K. It was noted the temperature effect on the reaction kinetics was much more pronounced at lower temperatures. Such behavior can be explained by a change in the physical state of LA at lower temperatures. In addition, kapp and γ were enhanced by 2-fold as the RH increased from 0 to 80%. Moreover, the effect of ozone concentration on the reaction kinetics was reported for the first time. kapp was found to display a Langmuir-Hinshelwood dependence on ozone concentration with KO3 = (1.146 ± 0.017) × 10(-15) molecules cm(-3) and k[S] = 0.0522 ± 0.0004 s(-1), where KO3 is a parameter that describes the partitioning of ozone to the thin film surface, and k[S] is the maximum pseudo-first-order coefficient at high ozone concentration. Furthermore, yields and hygroscopic properties of reaction products were also investigated by FTIR spectroscopy. The intensity ratio of two C═O stretching bands, A1743/A1710, which was utilized as an indicator of the product yields, increased sharply with increasing temperatures in the lower temperature region (258-284 K), and then remained nearly constant in the higher temperature region (284-314 K). The product yields showed no significant variation with RH, for the intensity ratio of A1743/A1710 barely changed in the wide RH range 0

  2. Ultrafast carriers dynamics in filled-skutterudites

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Liang; Xu, Xianfan, E-mail: xxu@purdue.edu [School of Mechanical Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); Salvador, James R. [Chemical and Materials Systems Laboratory, GM Global R and D, Warren, Michigan 48090 (United States)

    2015-06-08

    Carrier dynamics of filled-skutterudites, an important class of thermoelectric materials, is investigated using ultrafast optical spectroscopy. By tuning the wavelength of the probe laser, charge transfers at different electronic energy levels are interrogated. Analysis based on the Kramers-Kronig relation explains the complex spectroscopy data, which is mainly due to band filling caused by photo-excited carriers and free carrier absorption. The relaxation time of hot carriers is found to be about 0.4–0.6 ps, depending on the electronic energy level, and the characteristic time for carrier-phonon equilibrium is about 0.95 ps. These studies of carrier dynamics, which fundamentally determines the transport properties of thermoelectric material, can provide guidance for the design of materials.

  3. Ultrafast carriers dynamics in filled-skutterudites

    Science.gov (United States)

    Guo, Liang; Xu, Xianfan; Salvador, James R.

    2015-06-01

    Carrier dynamics of filled-skutterudites, an important class of thermoelectric materials, is investigated using ultrafast optical spectroscopy. By tuning the wavelength of the probe laser, charge transfers at different electronic energy levels are interrogated. Analysis based on the Kramers-Kronig relation explains the complex spectroscopy data, which is mainly due to band filling caused by photo-excited carriers and free carrier absorption. The relaxation time of hot carriers is found to be about 0.4-0.6 ps, depending on the electronic energy level, and the characteristic time for carrier-phonon equilibrium is about 0.95 ps. These studies of carrier dynamics, which fundamentally determines the transport properties of thermoelectric material, can provide guidance for the design of materials.

  4. In vivo evaluation of a simvastatin-loaded nanostructured lipid carrier for bone tissue regeneration

    Science.gov (United States)

    Yue, Xinxin; Niu, Mao; Zhang, Te; Wang, Cheng; Wang, Zhonglei; Wu, Wangxi; Zhang, Qi; Lai, Chunhua; Zhou, Lei

    2016-03-01

    Alveolar bone loss has long been a challenge in clinical dental implant therapy. Simvastatin (SV) has been demonstrated to exert excellent anabolic effects on bone. However, the successful use of SV to increase bone formation in vivo largely depends on the local concentration of SV at the site of action, and there have been continuing efforts to develop an appropriate delivery system. Specifically, nanostructured lipid carrier (NLC) systems have become a popular type of encapsulation carrier system. Therefore, SV-loaded NLCs (SNs) (179.4 nm in diameter) were fabricated in this study, and the osteogenic effect of the SNs was evaluated in a critical-sized rabbit calvarial defect. Our results revealed that the SNs significantly enhanced bone formation in vivo, as evaluated by hematoxylin and eosin (HE) staining, immunohistochemistry, and a fluorescence analysis. Thus, this novel nanostructured carrier system could be a potential encapsulation carrier system for SV in bone regeneration applications.

  5. Cytotoxicity of β-D-glucose/sucrose-coated silver nanoparticles depends on cell type, nanoparticles concentration and time of incubation

    Science.gov (United States)

    Vergallo, Cristian; Panzarini, Elisa; Carata, Elisabetta; Ahmadi, Meysam; Mariano, Stefania; Tenuzzo, Bernardetta Anna; Dini, Luciana

    2016-06-01

    The use of silver NanoParticles (AgNPs) in several consumer commercialized products, like food contact materials, medical devices and cosmetics has increased significantly, owing to their antibacterial and antifungal properties. Even though the NPs are widely diffused, due to the great variety in size, coating or shape, controversial data on their possible detrimental health effects still exist. Herein, by performing an easy and fast green method synthesis, we used β-D-glucose/sucrose to stabilize AgNPs and avoid the release of cytotoxic soluble silver ions Ag+ in the culture medium. The cytotoxic effects of these β-D-Glucose/Sucrose-Coated AgNPs (AgNPs-GS) was assessed on two cell culture models, which are human liver HepG2 and human Peripheral Blood Lymphocytes (PBLs) cells. AgNPs-GS, as determined by Transmission Electron Microscopy (TEM) analyses, had an average diameter of 30±5 nm, a spherical shape and were well-dispersed in the freshly-prepared solution. In addition, they were found spectrophotometrically stable throughout the experiment. Cytotoxicity, determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction assay, was evaluated by using two AgNPs-GS amounts, indicated as highest (10×103 of NPs/cell) and lowest (2×103 NPs/cell) concentration for 6, 12 and 24 h. The highest concentration of AgNPs-GS was significantly cytotoxic for both HepG2 and PBLs cells at all times, when compared with the negative control; conversely, the lowest amount of AgNPs-GS was toxic only for HepG2 cells. A significant increase of Reactive Oxygen Species (ROS) levels, determined by Nitro Blue Tetrazolium (NBT) reduction assay, was observed only in PBLs after treatment with NPs, by reaching maximum levels after the incubation with the lowest amount of NPs for 24 h. Significant morphological changes, depending on NPs/cell amount, characteristic of cell toxicity, like shape, cytoplasm, and nucleus alterations, were observed in lymphocytes and Hep

  6. Laboratory measurements of ice tensile strength dependence on density and concentration of silicate and polymer impurities at low temperatures

    Science.gov (United States)

    Litwin, K. L.; Beyeler, J. D.; Polito, P. J.; Zygielbaum, B. R.; Sklar, L. S.; Collins, G. C.

    2009-12-01

    The tensile strength of ice bedrock on Titan should strongly influence the effectiveness of the erosional processes responsible for carving the extensive fluvial drainage networks and other surface features visible in images returned by the Cassini and Huygens probes. Recent measurements of the effect of temperature on the tensile strength of low-porosity, polycrystalline ice, without impurities, suggest that ice bedrock at the Titan surface temperature of 93 K may be as much as five times stronger than ice at terrestrial surface temperatures. However, ice bedrock on Titan and other outer solar system bodies may have significant porosity, and impurities such silicates or polymers are possible in such ices. In this laboratory investigation we are exploring the dependence of tensile strength on the density and concentration of impurities, for polycrystalline ice across a wide range of temperatures. We use the Brazilian tensile splitting test to measure strength, and control temperature with dry ice and liquid nitrogen. The 50 mm diameter ice cores are made from a log-normally distributed seed crystal mixture with a median size of 1.4 mm. To control ice density and porosity we vary the packing density of the seed grains in core molds and vary the degree of saturation of the matrix with added near-freezing distilled water. We also vary ice density by blending in a similarly-sized mixture of angular fragments of two types of impurities, a fine-grained volcanic rock and a polyethylene polymer. Because both types of impurities have greater tensile strength than ice at Earth surface temperatures, we expect higher concentrations of impurities to correlate with increased strength for ice-rock and ice-polymer mixtures. However, at the ultra-cold temperatures of the outer planets, we expect significant divergence in the temperature dependence of ice tensile strength for the various mixtures and resulting densities. These measurements will help constrain the range of possible

  7. Further studies on the nature of postsynaptic dopamine uptake and metabolism in rat striatum: sodium dependency and investigation of a possible role for carrier-mediated uptake into serotonin neurons

    Energy Technology Data Exchange (ETDEWEB)

    Schoepp, D.D.; Azzaro, A.J.

    1985-06-01

    The nature of postsynaptic sites involved in the uptake and metabolism of striatal 3,4-dihydroxyphenylethylamine (dopamine, DA) was investigated. The accumulation of (/sup 3/H)DA (10(-7) M) into slices of rat striatum was found to be greatly dependent on the presence of sodium ion in the incubation medium. However, the formation of the (/sup 3/H)dihydroxyphenylacetic acid (DOPAC) and (/sup 3/H)homovanillic acid (HVA) was only partially reduced in the absence of sodium. Inhibition of carrier-mediated DA neuronal uptake with nomifensine significantly decreased DA accumulation (18% of control) and (/sup 3/H)DOPAC formation (62% of control), but enhanced (/sup 3/H)HVA production (143% of control). Inhibition of the 5-hydroxytryptamine (5-HT, serotonin) neuronal uptake system with fluoxetine (10(-6) M) or selective 5-HT neuronal lesions with 5,7-dihydroxytryptamine (5,7-DHT) had no effect on (/sup 3/H)DOPAC or (/sup 3/H)HVA formed from (/sup 3/H)DA in the presence or absence of nomifensine. These results demonstrate that the uptake and subsequent metabolism of striatal DA to DOPAC and HVA is only partially dependent on carrier-mediated uptake mechanism(s) requiring sodium ion. These data support our previous findings suggesting a significant role for synaptic glial cell deamination and O-methylation of striatal DA. Further, experiments with fluoxetine or 5,7-DHT suggest that 5-HT neurons do not significantly contribute in the synaptic uptake and metabolism of striatal DA.

  8. Stimulation of α1a adrenergic receptors induces cellular proliferation or antiproliferative hypertrophy dependent solely on agonist concentration.

    Directory of Open Access Journals (Sweden)

    Beilei Lei

    Full Text Available Stimulation of α1aAdrenergic Receptors (ARs is known to have anti-proliferative and hypertrophic effects; however, some studies also suggests this receptor can increase cell proliferation. Surprisingly, we find the α1aAR expressed in rat-1 fibroblasts can produce either phenotype, depending exclusively on agonist concentration. Stimulation of the α1aAR by high dose phenylephrine (>10(-7 M induces an antiproliferative, hypertrophic response accompanied by robust and extended p38 activation. Inhibition of p38 with SB203580 prevented the antiproliferative response, while inhibition of Erk or Jnk had no effect. In stark contrast, stimulation of the α1aAR with low dose phenylephrine (∼10(-8 M induced an Erk-dependent increase in cellular proliferation. Agonist-induced Erk phosphorylation was preceded by rapid FGFR and EGFR transactivation; however, only EGFR inhibition blocked Erk activation and proliferation. The general matrix metalloprotease inhibitor, GM6001, blocked agonist induced Erk activation within seconds, strongly suggesting EGFR activation involved extracellular triple membrane pass signaling. Erk activation required little Ca(2+ release and was blocked by PLCβ or PKC inhibition but not by intracellular Ca(2+ chelation, suggesting Ca(2+ independent activation of novel PKC isoforms. In contrast, Ca(2+ release was essential for PI3K/Akt activation, which was acutely maximal at non-proliferative doses of agonist. Remarkably, our data suggests EGFR transactivation leading to Erk induced proliferation has the lowest activation threshold of any α1aAR response. The ability of α1aARs to induce proliferation are discussed in light of evidence suggesting antagonistic growth responses reflect native α1aAR function.

  9. Brominated flame retardants in the urban atmosphere of Northeast China: Concentrations, temperature dependence and gas-particle partitioning

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Hong; Li, Wen-Long; Liu, Li-Yan; Song, Wei-Wei; Ma, Wan-Li, E-mail: mawanli002@163.com; Li, Yi-Fan, E-mail: ijrc_pts_paper@yahoo.com

    2014-09-01

    57 pairs of air samples (gas and particle phases) were collected using a high volume air sampler in a typical city of Northeast China. Brominated flame retardants (BFRs) including 13 polybrominated diphenyl ethers (PBDEs, including BDEs 17, 28, 47, 49, 66, 85, 99, 100, 138, 153, 154, 183, and 209) and 9 alternative BFRs (p-TBX, PBBZ, PBT, PBEB, DPTE, HBBZ, γ-HBCD, BTBPE, and DBDPE) were analyzed. The annual average total concentrations of the 13 PBDEs and the 9 alternative BFRs were 69 pg/m{sup 3} and 180 pg/m{sup 3}, respectively. BDE 209 and γ-HBCD were the dominant congeners, according to the one-year study. The partial pressure of BFRs in the gas phase was significantly correlated with the ambient temperature, except for BDE 85, γ-HBCD and DBDPE, indicating the important influence of ambient temperature on the behavior of BFRs in the atmosphere. It was found that the gas–particle partitioning coefficients (logK{sub p}) for most low molecular weight BFRs were highly temperature dependent as well. Gas–particle partitioning coefficients (logK{sub p}) also correlated with the sub-cooled liquid vapor pressure (logP{sub L}{sup o}). Our results indicated that absorption into organic matter is the main control mechanism for the gas–particle partitioning of atmospheric PBDEs. - Highlights: • Both PBDEs and alternative BFRs were analyzed in the atmosphere of Northeast China. • Partial pressure of BFRs was significantly correlated with the ambient temperature. • A strong temperature dependence of gas-particle partitioning was found. • Absorption into organic matter was the control mechanism for G-P partitioning.

  10. A new single-moment microphysics scheme for cloud-resolving models using observed dependence of ice concentration on temperature.

    Science.gov (United States)

    Khairoutdinov, M.

    2015-12-01

    The representation of microphysics, especially ice microphysics, remains one of the major uncertainties in cloud-resolving models (CRMs). Most of the cloud schemes use the so-called bulk microphysics approach, in which a few moments of such distributions are used as the prognostic variables. The System for Atmospheric Modeling (SAM) is the CRM that employs two such schemes. The single-moment scheme, which uses only mass for each of the water phases, and the two-moment scheme, which adds the particle concentration for each of the hydrometeor category. Of the two, the single-moment scheme is much more computationally efficient as it uses only two prognostic microphysics variables compared to ten variables used by the two-moment scheme. The efficiency comes from a rather considerable oversimplification of the microphysical processes. For instance, only a sum of the liquid and icy cloud water is predicted with the temperature used to diagnose the mixing ratios of different hydrometeors. The main motivation for using such simplified microphysics has been computational efficiency, especially in the applications of SAM as the super-parameterization in global climate models. Recently, we have extended the single-moment microphysics by adding only one additional prognostic variable, which has, nevertheless, allowed us to separate the cloud ice from liquid water. We made use of some of the recent observations of ice microphysics collected at various parts of the world to parameterize several aspects of ice microphysics that have not been explicitly represented before in our sing-moment scheme. For example, we use the observed broad dependence of ice concentration on temperature to diagnose the ice concentration in addition to prognostic mass. Also, there is no artificial separation between the pristine ice and snow, often used by bulk models. Instead we prescribed the ice size spectrum as the gamma distribution, with the distribution shape parameter controlled by the

  11. The effects of ABCG5/G8 polymorphisms on HDL-cholesterol concentrations depend on ABCA1 genetic variants in the Boston Puerto Rican health study

    Science.gov (United States)

    Background and aims: ATP-binding cassette transporters G5/G8 (ABCG5/G8) are associated with HDL-C concentrations. To assess whether the effect of ABCG5/G8 genetic variants on HDL-C concentrations is dependent on ATP-binding cassette transporters A1 (ABCA1), we studied potential interactions between ...

  12. Phase separation of polymer solutions. The calculation of the cloudpoint curve with a concentration and temperature-dependent free energy correction parameter

    NARCIS (Netherlands)

    Emmerik, van P.T.; Smolders, C.A.

    1973-01-01

    The free enthalpy correction parameter g in the Flory-Huggins equation for the Gibbs free enthalpy of mixing in polymer solutions is considered generally as a concentration- and temperature-independent parameter. It has been extended here with linear concentration- and temperature-dependent terms. W

  13. Eu2+-activated Ba3Ca3(PO4)4 phosphor with doping-concentration dependent luminescence

    Science.gov (United States)

    Tang, Huidong; Yang, Rong; Li, Rongzhu

    2017-10-01

    A color tunable phosphor of Eu2+-activated monophosphate Ba3Ca3(PO4)4 was developed via facile solid-state reaction synthesis. The samples were tested by X-ray powder diffraction (XRD) patterns, morphological properties, luminescence and decay lifetime measurements. The structural characteristics were discussed. The excitation bands of the phosphors cover the UV-, near-UV and blue-wavelength bands extending from 300 to 440 nm. The luminescence spectra of the phosphors show a great dependence on the Eu2+-concentration in Ba3Ca3(PO4)4, which can give blue to yellow emission colors. There are two kinds of Eu2+ centers in Ba3Ca3(PO4)4 lattices, which give yellow (EuI) and blue (EuII) luminescence with the maximum wavelength at 565 nm and 450 nm, respectively. The structural occupations and luminescence properties of EuI and EuII centers were discussed. EuI (yellow center) has a dominant contribution to the total luminescence with the increase of the Eu2+-doping level. The luminescence internal quantum efficiency and thermal stability (activation energy) were reported. The reported results could be helpful for the further potential application of the phosphor.

  14. Carrier Statistics and Quantum Capacitance Models of Graphene Nanoscroll

    Directory of Open Access Journals (Sweden)

    M. Khaledian

    2014-01-01

    schematic perfect scroll-like Archimedes spiral. The DOS model was derived at first, while it was later applied to compute the carrier concentration and quantum capacitance model. Furthermore, the carrier concentration and quantum capacitance were modeled for both degenerate and nondegenerate regimes, along with examining the effect of structural parameters and chirality number on the density of state and carrier concentration. Latterly, the temperature effect on the quantum capacitance was studied too.

  15. Study on intrinsic carrier concentration of direct bandgap Ge1-xSnx%直接带隙Ge1-xSnx本征载流子浓度研究∗

    Institute of Scientific and Technical Information of China (English)

    白敏; 宣荣喜; 宋建军; 张鹤鸣; 胡辉勇; 舒斌

    2014-01-01

    Indirect bandgap Ge can be turned to a direct bandgap semiconductor by the alloy-modified technique, which can be applied to advanced photonic devices and electronic devices. Based on 8 bands Kronig-Penny Hamilton, this paper focuses on the physical parameters of direct bandgap Ge1−xSnx, such as conduction band effective density of states, valence band effective density of states and the intrinsic carrier concentration, and aims to provide valuable references for understanding the direct bandgap modified Ge materials and device physics as well as their applications. Results show that: conduction band effective density of states in direct bandgap Ge1−xSnx alloy decreases obviously with increasing Sn fraction, while its valence band effective density of states almost does not change with increasing Sn fraction. Compared with bulk Ge, the conduction band effective density of states and valence band effective density of states in direct bandgap Ge1−xSnx alloy are lower by two and one orders of magnitude respectively; the intrinsic carrier concentration in direct bandgap Ge1−xSnx alloy increases with increasing Sn fraction, and its value is an order of magnitude higher than that of bulk Ge.%通过合金化改性技术, Ge可由间接带隙半导体转变为直接带隙半导体。改性后的Ge半导体可同时应用于光子器件和电子器件,极具发展潜力。基于直接带隙Ge1−xSnx半导体合金8带Kronig-Penny模型,重点研究了其导带有效状态密度、价带有效状态密度及本征载流子浓度,旨在为直接带隙改性Ge半导体物理的理解及相关器件的研究设计提供有价值的参考。研究结果表明:直接带隙Ge1−xSnx合金导带有效状态密度随着Sn组分x的增加而明显减小,价带有效状态密度几乎不随Sn组分变化。与体Ge半导体相比,直接带隙Ge1−xSnx合金导带有效状态密度、价带有效状态密度分别低两个和一个数量级;直接带隙Ge1

  16. Dose-dependent response of plasma ghrelin and growth hormone concentrations to bovine ghrelin in Holstein heifers.

    Science.gov (United States)

    ThidarMyint, Hnin; Yoshida, Hiroko; Ito, Tetsuya; Kuwayama, Hideto

    2006-06-01

    The stimulatory effect of the novel gastric-derived hormone, ghrelin, on growth hormone (GH) secretion has been reported in domestic animals as well as in humans and rats. The octanoyl modification on the Ser3 residue of ghrelin appears to be essential for its endocrine activity. A major portion of circulatory ghrelin lacks acylation but possesses some biological activities other than GH stimulation; therefore, both types of acylated and des-acyl ghrelin are supposed to be important for energy homeostasis. The effects of pharmacological doses of rat and/or human ghrelin on GH secretion have been reported recently in ruminants; however, the physiological effect of exogenous bovine ghrelin on its own plasma level and on GH secretion is still unknown. Moreover, the RIA systems for the measurement of bovine active ghrelin and for bovine total ghrelin including acylated ghrelin, des-acyl ghrelin and all ghrelin peptides with an intact bovine C-terminal have not yet been validated. In this study, we established the RIA system for bovine ghrelin, and the dose-dependent effects of synthesized acylated bovine ghrelin(1-27) on plasma active and total ghrelin, GH, insulin and metabolites were measured in Holstein heifers. Six animals were intravenously injected with synthesized acylated bovine ghrelin (0, 0.1, 0.5, 1.0, 5.0, 10.0 microg/kg body weight (BW)) and plasma hormone concentrations were measured from serially collected samples. Bovine ghrelin RIA showed that the basal level of total ghrelin is approximately 16 times higher than that of active ghrelin in bovine plasma. Both forms of ghrelin were increased in a dose-dependent manner in response to bovine ghrelin injections, peak values were reached at 5 min after administration and returned to pre-injected values within 15 min. Plasma GH was responsive to all doses of bovine ghrelin in a dose-dependent manner, peaked as early as at 5-10 min after injection and returned to the basal value within 60 min. The GH area

  17. Carrier localization in In0.21Ga0.79As/GaAs multiple quantum wells: A modified Pässler model for the S-shaped temperature dependence of photoluminescence energy

    Science.gov (United States)

    Fraj, Ibtissem; Hidouri, Tarek; Saidi, Faouzi; Maaref, Hassen

    2017-02-01

    The optical properties of In0.21Ga0.79As/GaAs MQWs, with triple unequal layer thickness NW (3 nm), MW (6 nm) and WW (9 nm) grown on (001) and (113) GaAs substrates, is studied by using continuous wave photoluminescence (cw-PL) spectroscopy. A comparative study has been performed to demonstrate the influence of electric field and QW thickness on the exciton localization. An S-shaped form in temperature-dependent PL peak energy has been observed in polar middle QW (MW (113)) but not seen in non-polar ones (MW (001)). This behavior is linked to carrier localization in triangular potential and polarity. We have observed also this atypical evolution in non-polar wide QW (WW (001)) but not in non-polar middle QW (MW (001)), which is attributed to potential fluctuation in larger ones. With the aid of modified Pässler model for including the effect of localized states, we can persuasively reproduce the S-shaped temperature dependence of PL band gap energy and contribute to the estimated value of exciton localization energy. The values of σ are obtained from adjustment of experimental points, which indicate the degree of localization in QW layer.

  18. Electronic structure and carrier transfer in B-DNA monomer polymers and dimer polymers: Stationary and time-dependent aspects of a wire model versus an extended ladder model

    Science.gov (United States)

    Lambropoulos, K.; Chatzieleftheriou, M.; Morphis, A.; Kaklamanis, K.; Lopp, R.; Theodorakou, M.; Tassi, M.; Simserides, C.

    2016-12-01

    We employ two tight-binding (TB) approaches to systematically study the electronic structure and hole or electron transfer in B-DNA monomer polymers and dimer polymers made up of N monomers (base pairs): (I) at the base-pair level, using the onsite energies of base pairs and the hopping integrals between successive base pairs, i.e., a wire model and (II) at the single-base level, using the onsite energies of the bases and the hopping integrals between neighboring bases, i.e., an extended ladder model since we also include diagonal hoppings. We solve a system of M (matrix dimension) coupled equations [(I) M =N , (II) M =2 N ] for the time-independent problem, and a system of M coupled first order differential equations for the time-dependent problem. We perform a comparative study of stationary and time-dependent aspects of the two TB variants, using realistic sets of parameters. The studied properties include HOMO and LUMO eigenspectra, occupation probabilities, density of states and HOMO-LUMO gaps as well as mean over time probabilities to find the carrier at each site [(I) base pair or (II) base], Fourier spectra, which reflect the frequency content of charge transfer, and pure mean transfer rates from a certain site to another. The two TB approaches give coherent, complementary aspects of electronic properties and charge transfer in B-DNA monomer polymers and dimer polymers.

  19. [The concentrations of halothane in the operating theatre and its dependance on various methods of removal (author's transl)].

    Science.gov (United States)

    Hövener, B; Link, J

    1976-02-01

    Measurement of halothane concentrations by means of gas chromatography was used to compare the efficiency of 1) a filtration system and 2) ducting of gases into the exhaust of the ventilation system of our operating threatre. The concentrations were found to be lower when the latter method was used. Measurements made subsequently provided data on halothane concentrations occurring during routine service when different methods of anaesthesia were used, with and without ducting of gases into the ventilation exhaust system.

  20. Insights from transport modeling of unusual charge carrier behavior of PDTSiTzTz:PC71BM bulk heterojunction materials

    Science.gov (United States)

    Slobodyan, Oleksiy; Moench, Sarah; Liang, Kelly; Danielson, Eric; Holliday, Bradley; Dodabalapur, Ananth

    2015-03-01

    Development of hole-transporting copolymers for use in bulk heterojunctions (BHJs) has significantly improved organic solar cell performance. Despite advances on the materials side, the physics of charge carrier transport remains unsettled. Intrigued by its ability to maintain high fill factors in thick active layers, we studied the copolymer poly[2-(5-(4,4-dioctyl-4H-silolo[3,2-b:4,5-b’]dithiophen-2-yl)-3-tetradecylthiophen-2-yl)- 5-(3-tetradecylthiophen-2-yl)thiazolo[5,4-d]thiazole] (PDTSiTzTz) blended with PC71BM. Results show mobilities which are carrier-concentration-dependent and characterized by a negative Poole-Frenkel effect. Such behavior is not described by current carrier transport models. Established transport mechanisms like multiple-trap-and-release or variable range hopping yield dependence of mobility on carrier concentration. However, a more basic model like Gaussian distribution model (GDM) is needed to produce the negative Poole-Frenkel effect, though GDM cannot describe carrier-concentration-dependent mobility. We have combined key aspects of existing models to create a unified transport model capable of describing phenomena observed in PDTSiTzTz:PC71BM. This model can be used to address open questions about transport physics of organic BHJ materials. U.S. Department of Energy, Award Number DE-SC0001091.

  1. Effects of rhizopheric nitric oxide (NO) on N uptake in Fagus sylvatica seedlings depend on soil CO2 concentration, soil N availability and N source.

    Science.gov (United States)

    Dong, Fang; Simon, Judy; Rienks, Michael; Lindermayr, Christian; Rennenberg, Heinz

    2015-08-01

    Rhizospheric nitric oxide (NO) and carbon dioxide (CO2) are signalling compounds known to affect physiological processes in plants. Their joint influence on tree nitrogen (N) nutrition, however, is still unknown. Therefore, this study investigated, for the first time, the combined effect of rhizospheric NO and CO2 levels on N uptake and N pools in European beech (Fagus sylvatica L.) seedlings depending on N availability. For this purpose, roots of seedlings were exposed to one of the nine combinations (i.e., low, ambient, high NO plus CO2 concentration) at either low or high N availability. Our results indicate a significant effect of rhizospheric NO and/or CO2 concentration on organic and inorganic N uptake. However, this effect depends strongly on NO and CO2 concentration, N availability and N source. Similarly, allocation of N to different N pools in the fine roots of beech seedlings also shifted with varying rhizospheric gas concentrations and N availability.

  2. Condition-dependent cell volume and concentration of Escherichia coli to facilitate data conversion for systems biology modeling

    NARCIS (Netherlands)

    Volkmer, Benjamin; Heinemann, Matthias

    2011-01-01

    Systems biology modeling typically requires quantitative experimental data such as intracellular concentrations or copy numbers per cell. In order to convert population-averaging omics measurement data to intracellular concentrations or cellular copy numbers, the total cell volume and number of cell

  3. Effects of base doping and carrier lifetime on differential current gain and temperature coefficient of 4H-SiC power bipolar junction transistors

    Science.gov (United States)

    Niu, X.; Fardi, H.

    2012-04-01

    4H-SiC NPN bipolar junction transistor (BJT) is studied systematically by performing two-dimensional numerical simulations. Several design issues are discussed. Depending on the doping concentration of the base and the carrier lifetimes, both positive and negative temperature coefficients in the common emitter current gain could exist in 4H-SiC NPN BJTs with aluminium-doped base. The temperature coefficients of the current gain at different base doping concentrations and different carrier lifetimes have been determined. A high base doping concentration can reduce the requirement for the carrier lifetime in order to obtain negative temperature coefficient in current gain. Device simulations are performed to evaluate the carrier lifetimes by fitting the measured output IC -VCE curves. An excellent fitting is obtained and the base electron lifetime and the emitter hole lifetime are extracted to be about 22 and 5.7 ns, respectively.

  4. Concentration dependence of alpha-synuclein fibril length assessed by quantitative atomic force microscopy and statistical-mechanical theory.

    Science.gov (United States)

    van Raaij, Martijn E; van Gestel, Jeroen; Segers-Nolten, Ine M J; de Leeuw, Simon W; Subramaniam, Vinod

    2008-11-15

    The initial concentration of monomeric amyloidogenic proteins is a crucial factor in the in vitro formation of amyloid fibrils. We use quantitative atomic force microscopy to study the effect of the initial concentration of human alpha-synuclein on the mean length of mature alpha-synuclein fibrils, which are associated with Parkinson's disease. We determine that the critical initial concentration, below which low-molecular-weight species dominate and above which fibrils are the dominant species, lies at approximately 15 muM, in good agreement with earlier measurements using biochemical methods. In the concentration regime where fibrils dominate, we find that their mean length increases with initial concentration. These results correspond well to the qualitative predictions of a recent statistical-mechanical model of amyloid fibril formation. In addition, good quantitative agreement of the statistical-mechanical model with the measured mean fibril length as a function of initial protein concentration, as well as with the fibril length distributions for several protein concentrations, is found for reasonable values of the relevant model parameters. The comparison between theory and experiment yields, for the first time to our knowledge, an estimate of the magnitude of the free energies associated with the intermolecular interactions that govern alpha-synuclein fibril formation.

  5. Postsynaptic odorant concentration dependent inhibition controls temporal properties of spike responses of projection neurons in the moth antennal lobe.

    Science.gov (United States)

    Fujiwara, Terufumi; Kazawa, Tomoki; Haupt, Stephan Shuichi; Kanzaki, Ryohei

    2014-01-01

    Although odorant concentration-response characteristics of olfactory neurons have been widely investigated in a variety of animal species, the effect of odorant concentration on neural processing at circuit level is still poorly understood. Using calcium imaging in the silkmoth (Bombyx mori) pheromone processing circuit of the antennal lobe (AL), we studied the effect of odorant concentration on second-order projection neuron (PN) responses. While PN calcium responses of dendrites showed monotonic increases with odorant concentration, calcium responses of somata showed decreased responses at higher odorant concentrations due to postsynaptic inhibition. Simultaneous calcium imaging and electrophysiology revealed that calcium responses of PN somata but not dendrites reflect spiking activity. Inhibition shortened spike response duration rather than decreasing peak instantaneous spike frequency (ISF). Local interneurons (LNs) that were specifically activated at high odorant concentrations at which PN responses were suppressed are the putative source of inhibition. Our results imply the existence of an intraglomerular mechanism that preserves time resolution in olfactory processing over a wide odorant concentration range.

  6. Postsynaptic odorant concentration dependent inhibition controls temporal properties of spike responses of projection neurons in the moth antennal lobe.

    Directory of Open Access Journals (Sweden)

    Terufumi Fujiwara

    Full Text Available Although odorant concentration-response characteristics of olfactory neurons have been widely investigated in a variety of animal species, the effect of odorant concentration on neural processing at circuit level is still poorly understood. Using calcium imaging in the silkmoth (Bombyx mori pheromone processing circuit of the antennal lobe (AL, we studied the effect of odorant concentration on second-order projection neuron (PN responses. While PN calcium responses of dendrites showed monotonic increases with odorant concentration, calcium responses of somata showed decreased responses at higher odorant concentrations due to postsynaptic inhibition. Simultaneous calcium imaging and electrophysiology revealed that calcium responses of PN somata but not dendrites reflect spiking activity. Inhibition shortened spike response duration rather than decreasing peak instantaneous spike frequency (ISF. Local interneurons (LNs that were specifically activated at high odorant concentrations at which PN responses were suppressed are the putative source of inhibition. Our results imply the existence of an intraglomerular mechanism that preserves time resolution in olfactory processing over a wide odorant concentration range.

  7. Concentration dependent survival and neural differentiation of murine embryonic stem cells cultured on polyethylene glycol dimethacrylate hydrogels possessing a continuous concentration gradient of n-cadherin derived peptide His-Ala-Val-Asp-Lle.

    Science.gov (United States)

    Lim, Hyun Ju; Mosley, Matthew C; Kurosu, Yuki; Smith Callahan, Laura A

    2016-12-01

    N-cadherin cell-cell signaling plays a key role in the structure and function of the nervous system. However, few studies have incorporated bioactive signaling from n-cadherin into tissue engineering matrices. The present study uses a continuous gradient approach in polyethylene glycol dimethacrylate hydrogels to identify concentration dependent effects of n-cadherin peptide, His-Ala-Val-Asp-Lle (HAVDI), on murine embryonic stem cell survival and neural differentiation. The n-cadherin peptide was found to affect the expression of pluripotency marker, alkaline phosphatase, in murine embryonic stem cells cultured on n-cadherin peptide containing hydrogels in a concentration dependent manner. Increasing n-cadherin peptide concentrations in the hydrogels elicited a biphasic response in neurite extension length and mRNA expression of neural differentiation marker, neuron-specific class III β-tubulin, in murine embryonic stem cells cultured on the hydrogels. High concentrations of n-cadherin peptide in the hydrogels were found to increase the expression of apoptotic marker, caspase 3/7, in murine embryonic stem cells compared to that of murine embryonic stem cell cultures on hydrogels containing lower concentrations of n-cadherin peptide. Increasing the n-cadherin peptide concentration in the hydrogels facilitated greater survival of murine embryonic stem cells exposed to increasing oxidative stress caused by hydrogen peroxide exposure. The combinatorial approach presented in this work demonstrates concentration dependent effects of n-cadherin signaling on mouse embryonic stem cell behavior, underscoring the need for the greater use of systematic approaches in tissue engineering matrix design in order to understand and optimize bioactive signaling in the matrix for tissue formation.

  8. Peptide-Carrier Conjugation

    DEFF Research Database (Denmark)

    Hansen, Paul Robert

    2015-01-01

    To produce antibodies against synthetic peptides it is necessary to couple them to a protein carrier. This chapter provides a nonspecialist overview of peptide-carrier conjugation. Furthermore, a protocol for coupling cysteine-containing peptides to bovine serum albumin is outlined....

  9. Light-trap Catch of the Common Cockchafer (Melolontha melolontha L. Depending on the Atmospheric Ozone Concentration

    Directory of Open Access Journals (Sweden)

    NOWINSZKY, László

    2011-01-01

    Full Text Available The study deals the efficiency of light trapping of the Common Cockchafer (Melolonthamelolontha L. (Coleoptera: Melolonthidae in connection with the ozone concentration of air. Thedata of the Hungarian forestry light trap network were used for the years 1997 through 2006. Wecalculated relative catch values of from the number of caught insects. We assigned these to the ozonevalues of the respective days. For the classified date pairs regression equations were calculated. Weestablished that the light trapping is most effective if the ozone concentration is high. As opposed tothis, low ozone concentration reduces the success of the catch. Our results may be utilized in plantprotection and forest protection prognoses.

  10. Effects of lauric acid on upper gut motility, plasma cholecystokinin and peptide YY, and energy intake are load, but not concentration, dependent in humans.

    Science.gov (United States)

    Feltrin, Kate L; Little, Tanya J; Meyer, James H; Horowitz, Michael; Rades, Thomas; Wishart, Judith; Feinle-Bisset, Christine

    2007-06-01

    Animal studies suggest that the effects of fatty acids on gastric emptying and pancreatic secretion are both concentration and load dependent, while their suppressive effect on energy intake is only load dependent. We postulated that, in humans, the modulation of antropyloroduodenal pressure waves, plasma cholecystokinin (CCK) and peptide YY (PYY) concentrations and energy intake by intraduodenal lauric acid, a fatty acid with 12 carbon atoms ('C12') would be load, but not concentration, dependent. Two groups of 12 healthy males were each studied on three separate occasions in double-blind randomized fashion. Antropyloroduodenal pressure waves, plasma CCK and PYY, and appetite perceptions were measured during intraduodenal infusions of C12 at (1) different loads of (i) 0.2, (ii) 0.3 and (iii) 0.4 kcal min(-1) (all 56 mM) for 90 min, and (2) different concentrations of (i) 40, (ii) 56 and (iii) 72 mM (all 0.4 kcal min(-1)) for 60 min. Energy intake at a buffet meal consumed immediately following each infusion was quantified. Suppression of antral and duodenal pressure waves, stimulation of pyloric pressure waves, stimulation of plasma CCK and PYY, and suppression of energy intake, were related to the load of C12 administered (r>0.65, P<0.05). In contrast, there were no concentration-dependent effects of C12 on any of these parameters. In conclusion, in humans, the effects of intraduodenal C12 on antropyloroduodenal motility, plasma CCK and PYY and energy intake appear to be related to load, but not concentration, at least at the loads and concentrations evaluated.

  11. Dependence Properties of Sol-Gel Derived CuO@SiO2 Nanostructure to Diverse Concentrations of Copper Oxide

    Directory of Open Access Journals (Sweden)

    V. Homaunmir

    2013-01-01

    Full Text Available Various concentrations of copper oxide were embedded into silica matrix of xerogel forms using copper source Cu(NO32·3H2O. The xerogel samples were prepared by hydrolysis and condensation of tetraethyl orthosilicate (TEOS with determination of new molar ratios of the components by the sol-gel method. In this paper, three samples of copper oxide were doped into silica matrices using different concentrations. We obtained 10, 20, and 30 wt.% of copper oxide in silica matrices labeled as A, B, and C, respectively. The absorption and transmittance spectra of the gel matrices were treated at different concentrations by Uv-vis spectrophotometer. Quantities of water and transparency in the silica network change the spectral characteristics of Cu2+ ions in the host silica. Absorption spectra of the samples heated to higher concentration complete the conversion of Cu2+ ions to Cu+ ions. The effects of concentration of copper oxide were characterized by X-ray diffraction (XRD patterns, and the transmission electron microscope (TEM micrographs. Also, textural properties of samples were studied by surface area analysis (BET method at different concentrations.

  12. Charge transport in disordered organic host-guest systems: effects of carrier density and electric field

    Energy Technology Data Exchange (ETDEWEB)

    Yimer, Y Y; Bobbert, P A [Group Polymer Physics, Eindhoven Polymer Laboratories and Dutch Polymer Institute, 5600 MB Eindhoven (Netherlands); Coehoorn, R [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands)], E-mail: Y.Y.Yimer@tue.nl

    2008-08-20

    We investigate charge transport in disordered organic host-guest systems with a bimodal Gaussian density of states (DOS). The energy difference between the two Gaussians defines the trap depth. By solving the Pauli master equation for the hopping of charge carriers on a regular lattice with site energies randomly drawn from the DOS, we obtain the dependence of the charge-carrier mobility on the relative guest concentration, the trap depth, the energetic disorder, the charge-carrier density and the electric field. At small and high guest concentrations, our work provides support for recent semi-analytical model results on the dependence of the mobility on the charge-carrier density at zero field. However, at the cross-over between the trap-limited and trap-to-trap hopping regimes, where the mobility attains a minimum, our results can almost be one order of magnitude larger than predicted semi-analytically. Furthermore, it is shown that field-induced detrapping can contribute strongly to the electric-field dependence of the mobility. A simple analytical expression is provided which describes the effect. This result can be used in continuum drift-diffusion models for charge transport in devices such as organic light-emitting diodes.

  13. Charge transport in disordered organic host guest systems: effects of carrier density and electric field

    Science.gov (United States)

    Yimer, Y. Y.; Bobbert, P. A.; Coehoorn, R.

    2008-08-01

    We investigate charge transport in disordered organic host-guest systems with a bimodal Gaussian density of states (DOS). The energy difference between the two Gaussians defines the trap depth. By solving the Pauli master equation for the hopping of charge carriers on a regular lattice with site energies randomly drawn from the DOS, we obtain the dependence of the charge-carrier mobility on the relative guest concentration, the trap depth, the energetic disorder, the charge-carrier density and the electric field. At small and high guest concentrations, our work provides support for recent semi-analytical model results on the dependence of the mobility on the charge-carrier density at zero field. However, at the cross-over between the trap-limited and trap-to-trap hopping regimes, where the mobility attains a minimum, our results can almost be one order of magnitude larger than predicted semi-analytically. Furthermore, it is shown that field-induced detrapping can contribute strongly to the electric-field dependence of the mobility. A simple analytical expression is provided which describes the effect. This result can be used in continuum drift-diffusion models for charge transport in devices such as organic light-emitting diodes.

  14. CTX-M-1 β-lactamase expression in Escherichia coli is dependent on cefotaxime concentration, growth phase and gene location

    DEFF Research Database (Denmark)

    Kjeldsen, Thea S. B.; Overgaard, Martin; Nielsen, Søren S.

    2015-01-01

    blaCTX-M-1 mRNA expression and CTX-M-1 protein levels were dependent on cefotaxime concentration, growth phase and gene location. These results provide insight into the expression of cephalosporin resistance in CTX-M-1-producing E. coli, improving our understanding of the relationship between...

  15. Understanding the Concentration Dependence of Viral Capsid Assembly Kinetics—the Origin of the Lag Time and Identifying the Critical Nucleus Size

    National Research Council Canada - National Science Library

    Hagan, Michael F; Elrad, Oren M

    2010-01-01

    ... )), but extracting mechanistic information such as the critical nucleus size or the time to assemble an individual capsid has been challenging. In this article, we theoretically examine two models for capsid assembly kinetics to show that these properties can be determined from the concentration dependence of median assembly times and the la...

  16. Synthesis of {sup 188}Re-DMSA complex using carrier-free {sup 188}Re

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, Kazuyuki; Izumo, Mishiroku [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Islam, M.S.

    1997-03-01

    The synthesis of rhenium-DMSA labelled compound using carrier-free {sup 188}Re from the {sup 188}W/{sup 188}Re generator has been carried out. Stannous chloride was used as the reducing agent for reduction of rhenium and ascorbic acid was used as an antioxidant in the reaction media. The dependence of the yield of Re-DMSA complex upon the concentration of reducing agent, pH, reaction time, anti-oxidant, carrier and temperature was investigated. Under optimum conditions, the yield of Re-DMSA complexes were more than 98% for the carrier-free as well as carrier-added {sup 188}Re. The stability of the Re-DMSA complexes at different pH and time were also investigated. It was found that the Re-DMSA complex was very stable and did not undergo any changes or decomposition with the changes of pH from its initial values even after 48 hours of pH change for carrier-free as well as carrier-added complexes. (author)

  17. Radiative recombination of localized excitons and mobility edge excitons in GaInNAs/GaAs quantum wells with strong carrier localization

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Q.X. [Physical Electronics and Photonics, Department of Physics, Chalmers University of Technology and Goeteborg University, SE-412 96 Goeteborg (Sweden)]. E-mail: zhao@fly.chalmers.se; Wang, S.M. [Photonics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden); Wei, Y.Q. [Photonics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden); Sadeghi, M. [Photonics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden); Larsson, A. [Photonics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden); Willander, M. [Physical Electronics and Photonics, Department of Physics, Chalmers University of Technology and Goeteborg University, SE-412 96 Goeteborg (Sweden)

    2005-06-20

    The radiative recombination in In{sub x}Ga{sub 1-x}N{sub 0.01}As{sub 0.99}/GaAs quantum well structures exhibiting strong carrier localization was investigated by optical spectroscopy. For In-concentration from 0 to 30%, the results indicate that the degree of carrier localization decreases with increasing In-concentration. At temperatures below 100 K, the mobility edge excitons as well as localized excitons are identified and their transitions energies strongly depend on the excitation intensity. At elevated temperatures the localized excitons become quenched. The temperature dependence of the photoluminescence emission energy shows different behaviors at different excitation intensities.

  18. [Concentration-dependent changes in the latency and amplitude of somatosensory-evoked potentials by desflurane, isoflurane and sevoflurane].

    Science.gov (United States)

    Rehberg, B; Rüschner, R; Fischer, M; Ebeling, B J; Hoeft, A

    1998-07-01

    Comparison of the influence of desflurane, isoflurane, and sevoflurane on the parameters of cortical somatosensory evoked potentials (SEP). A total of 41 patients were randomly allocated to either the isoflurane, desflurane or sevoflurane group. Following induction with propofol and intubation, concentration of the volatile anaesthetic was kept constant at 1.3, 1.0, and 0.7 MAC for 15 minutes each in randomised sequences. No opioids or N2O were used. Cortical somatosensory evoked potentials were recorded following median nerve stimulation at the wrist with 1.5 times motor threshold current. SEP were evaluated for latencies of peak N20 and P25 as well as peak-to-peak amplitude N20P25. Measurements at the end of the 15 minute equilibration intervals were compared by analysis of variance for repeated measurements. Latencies and the logarithm of the amplitudes were assumed to be normally distributed. SEP could be recorded in all patients and at all concentrations. Latency of cortical SEP increased with anaesthetic concentration in a linear manner. No differences in latency increase were found between the three anaesthetics (ANOVA). In contrast, the decrease in amplitude with increasing anaesthetic concentration was non-linear. It was large from control to 0.7 MAC, but small in the range between 0.7 and 1.3 MAC. Amplitude reduction was larger with isoflurane than with sevoflurane or desflurane. 1) Sevoflurane and desflurane are better suited for anaesthetic management during intraoperative electrophysiological monitoring than isoflurane, because SEP amplitudes are better preserved. 2) SEP amplitude is less altered by changing anaesthetic concentrations in the concentration range from 0.7 to 1.3 MAC than SEP latency.

  19. Sodium-dependent phosphate uptake in the jejunum is post-transcriptionally regulated in pigs fed a low-phosphorus diet and is independent of dietary calcium concentration.

    Science.gov (United States)

    Saddoris, Kari L; Fleet, James C; Radcliffe, John S

    2010-04-01

    In rodents, severe dietary P restriction increases active phosphate absorption by the intestine. However, it remains unknown if moderate dietary P restriction has a similar effect. Weanling pigs (n = 32; body weight 7.4 +/- 0.55 kg) were used in a 2 x 2 factorial design and fed dietary available P (aP) concentrations of 0.23 or 0.40% and Ca concentrations of 0.58 or 1.00% for 14 d. Diets were formulated on an aP basis instead of a total P basis, because pigs are unable to absorb phytate-P present in corn and soybean meal. Jejunal segments were mounted in modified Ussing chambers for determination of Na(+)-dependent nutrient transport. Intestinal mucosal scrapings were taken for RNA isolation and brush border membrane (BBM) vesicle isolation. Na(+)-dependent phosphate uptake and gene expression of Na-phosphate cotransporter IIb (NaPi-IIb), SGLT-1 (sodium/glucose cotransporter-1), and calbindin D(9k) and protein expression of NaPi-IIb were evaluated. Na(+)-dependent phosphate transport increased (P dietary aP concentration was decreased. However, increased Na(+)-dependent phosphate uptake was not accompanied by increased NaPi-IIb mRNA expression. Expression of NaPi-IIb protein in the BBM increased (P pigs fed low-P diets compared with pigs fed adequate-P diets. No dietary Ca effects or aP x Ca interactions were detected for Na-dependent P uptake, mRNA or protein expression of NaPi-IIb, or mRNA expression of calbindin D(9k). These data suggest that restricting dietary aP concentration by only 43% stimulates Na(+)-dependent phosphate uptake and expression of the NaPi-IIb protein in the BBM of the small intestine and through a post-transcriptional mechanism.

  20. The rate of intestinal glucose absorption is correlated with plasma glucose-dependent insulinotropic polypeptide concentrations in healthy men

    DEFF Research Database (Denmark)

    Wachters-Hagedoorn, Renate E; Priebe, Marion G; Heimweg, Janneke A J

    2006-01-01

    and slowly available glucose. In a crossover study, glucose, insulin, GLP-1, and GIP concentrations were monitored for 6 h after consumption of glucose, uncooked cornstarch (UCCS) or corn pasta in 7 healthy men. All test meals were naturally labeled with 13C. Using a primed, continuous D-[6,6-2H2]glucose...... in the early postprandial phase (15-90 min) occurred after consumption of glucose. There was a strong positive within-subject correlation between RaEx and GIP concentrations (r = 0.73, P

  1. Anion concentration-dependent partitioning mechanism in the extraction of uranium into room-temperature ionic liquids.

    Science.gov (United States)

    Dietz, Mark L; Stepinski, Dominique C

    2008-04-15

    The mode of partitioning of uranyl ion between nitrate-containing aqueous phases and various N,N'-dialkylimidazolium-based room-temperature ionic liquids (RTILs) in the presence of tri-n-butyl phosphate (TBP) is shown to change from an ion-exchange process to one involving extraction of a neutral uranyl-TBP-nitrato complex as the aqueous nitrate concentration is increased. Increasing the hydrophobicity of the RTIL cation eventually leads to nitrato complex extraction as the predominant mode of partitioning, regardless of nitrate concentration.

  2. Performance comparison of a continuous-flow stirred-tank reactor and an anaerobic sequencing batch reactor for fermentative hydrogen production depending on substrate concentration.

    Science.gov (United States)

    Kim, S-H; Han, S-K; Shin, H-S

    2005-01-01

    This study was conducted to compare the performance of a continuous-flow stirred-tank reactor (CSTR) and an anaerobic sequencing batch reactor (ASBR) for fermentative hydrogen production at various substrate concentrations. Heat-treated anaerobic sludge was utilized as an inoculum, and hydraulic retention time (HRT) for each reactor was maintained at 12 h. At the influent sucrose concentration of 5 g COD/L, start-up was not successful in both reactors. The CSTR, which was started-up at 10 g COD/L, showed stable hydrogen production at the influent sucrose concentrations of 10-60 g COD/L during 203 days. Hydrogen production was dependent on substrate concentration, resulting in the highest performance at 30 g COD/L. At the lower substrate concentration, the hydrogen yield (based on hexose consumed) decreased with biomass reduction and changes in fermentation products. At the higher substrate concentration, substrate inhibition on biomass growth caused the decrease of carbohydrate degradation and hydrogen yield (based on hexose added). The ASBR showed higher biomass concentration and carbohydrate degradation efficiency than the CSTR, but hydrogen production in the ASBR was less effective than that in the CSTR at all the substrate concentrations.

  3. Composite cam carrier

    Energy Technology Data Exchange (ETDEWEB)

    Wicks, Christopher Donald; Madin, Mark Michael

    2017-03-14

    A cam carrier assembly includes a cylinder head having valves and a camshaft having lobes. A cam carrier has a first side coupled with the cylinder head engaging around the valves and a second side with bearing surfaces supporting the camshaft. A series of apertures extend between the first and second sides for the lobes to interface with the valves. The cam carrier is made of carbon fiber composite insulating the camshaft from the cylinder head and providing substantial weight reduction to an upper section of an associated engine.

  4. Asymmetric Carrier Random PWM

    DEFF Research Database (Denmark)

    Mathe, Laszlo; Lungeanu, Florin; Rasmussen, Peter Omand;

    2010-01-01

    This paper presents a new fixed carrier frequency random PWM method, where a new type of carrier wave is proposed for modulation. Based on the measurements, it is shown that the spread effect of the discrete components from the motor current spectra is very effective independent of the modulation...... index. The flat motor current spectrum generates an acoustical noise close to the white noise, which may improve the acoustical performance of the drive. The new carrier wave is easy to implement digitally, without employing any external circuits. The modulation method can be used in open, as well...

  5. Concentration-dependent ionic conductivity and thermal stability of magnetron-sputtered nanocrystalline scandia-stabilized zirconia

    DEFF Research Database (Denmark)

    Sillassen, M.; Eklund, P.; Pryds, Nini;

    2010-01-01

    grain size, yielding a grain size of 6 nm and a microstrain of 2.5% at -200 V and -250 V with additional incorporation of argon. Temperature-dependent impedance spectroscopy of the SSZ films showed that the in-plane ionic conductivity had a maximum close to 10.7 mol% and decreased almost an order...... of magnitude as the scandia - content was increased to 15.9 mol%. The activation energy for oxygen ion migration was determined to be between 1.30 - 1.43 eV. In addition, no dependence on grain size was observed. The above observations suggest a bulk mechanism for ionic conduction....

  6. Phase I/II safety study of transfusion of prion-filtered red cell concentrates in transfusion-dependent patients.

    LENUS (Irish Health Repository)

    Cahill, M R

    2010-08-01

    Variant Creutzfeldt-Jakob (vCJD) is a fatal transfusion transmissible prion infection. No test for vCJD in the donor population is currently available. Therefore, prion removal by filtration of red cell concentrate (RCC) is an attractive option for prevention.

  7. Concentration dependent toxicity of approximately 20 nm anatase titanium dioxide nanoparticles--an in vivo study on Wistar rats.

    Science.gov (United States)

    Unnithan, Jyotisree; Rehman, Muneeb U; Ahmad, Farhan J; Samim, M

    2011-02-01

    Titanium dioxide (TiO2) is one of the most widely used nanoparticles. Synthesized TiO2 nanoparticles (approximately 20 nm) at a concentration of 42 mg/kg bw induced biochemical perturbations in Wistar rats. TiO2 nanoparticles exhibited hepatic and renal toxicity in Wistar rats.

  8. Time-dependent changes in saliva cytokine concentrations during alcohol hangover: A comparison of two naturalistic studies

    NARCIS (Netherlands)

    Van De Loo, A.J.A.E.|info:eu-repo/dai/nl/369403649; Slot, K.A.|info:eu-repo/dai/nl/273850784; Kleinjan, M.|info:eu-repo/dai/nl/314087451; Knipping, K.; Garssen, J.|info:eu-repo/dai/nl/086369962; Verster, J.C.|info:eu-repo/dai/nl/241442702

    2016-01-01

    Purpose: A role of the immune system in the pathology of alcohol hangover has been proposed, and previous research have shown changes in serum cytokine concentrations during alcohol hangover relative to a control alcohol-free day. The current analyses compare determinations of saliva cytokine concen

  9. The rate of intestinal glucose absorption is correlated with plasma glucose-dependent insulinotropic polypeptide concentrations in healthy men

    DEFF Research Database (Denmark)

    Wachters-Hagedoorn, Renate E; Priebe, Marion G; Heimweg, Janneke A J;

    2006-01-01

    and slowly available glucose. In a crossover study, glucose, insulin, GLP-1, and GIP concentrations were monitored for 6 h after consumption of glucose, uncooked cornstarch (UCCS) or corn pasta in 7 healthy men. All test meals were naturally labeled with 13C. Using a primed, continuous D-[6,6-2H2]glucose...

  10. Concentration dependence of luminescence efficiency of Dy(3)(+) ions in strontium zinc phosphate glasses mixed with Pb3 O4.

    Science.gov (United States)

    Kumar, Valluri Ravi; Giridhar, G; Veeraiah, N

    2017-02-01

    In this work we synthesized SrO-ZnO-P2 O5 glasses mixed with Pb3 O4 (heavy metal oxide) and doped with different amounts of Dy2 O3 (0.1 to 1.0 mol%). Subsequently their emission and decay characteristics were investigated as a function of Dy2 O3 concentration. The emission spectra exhibited three principal emission bands in the visible region corresponding to (4) F9/2  → (6) H15/2 (482 nm), (6) H13/2 (574 nm) and (6) H11/2 (663 nm) transitions. With increase in the concentration of Dy2 O3 (upto 0.8 mol%) a considerable increase in the intensity of these bands was observed and, for further increase, quenching of photoluminescence (PL) output was observed. Using emission spectra, various radiative parameters were evaluated and all these parameters were found to increase with increase in Dy2 O3 concentration. The Y/B integral emission intensity ratio of Dy(3)(+) ions evaluated from these spectra exhibited a decreasing trend with increase in the Dy2 O3 concentration up to 0.8 mol%. Quenching of luminescence observed in the case of the glasses doped with 1.0 mol% is attributed to clustering of Dy(3)(+) ions. The quantitative analysis of these results together with infra-red (IR) spectral studies indicated that 0.8 mol% is the optimum concentration of Dy(3)(+) ions needed to achieve maximum luminescence efficiency. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  11. The rate of intestinal glucose absorption is correlated with plasma glucose-dependent insulinotropic polypeptide concentrations in healthy men

    NARCIS (Netherlands)

    Wachters-Hagedoorn, Renate E.; Priebe, Marion G.; Heimweg, Janneke A. J.; Heiner, A. Marius; Englyst, Klaus N.; Holst, Jens. J.; Stellaard, Frans; Vonk, Roel J.

    Glucagon-like pepticle-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) both play a role in the control of glucose homeostasis, and GIP is implicated in the regulation of energy storage. The capacity of carbohydrates to induce secretion of these incretin hormones could be one of the

  12. The rate of intestinal glucose absorption is correlated with plasma glucose-dependent insulinotropic polypeptide concentrations in healthy men

    NARCIS (Netherlands)

    Wachters-Hagedoorn, Renate E.; Priebe, Marion G.; Heimweg, Janneke A. J.; Heiner, A. Marius; Englyst, Klaus N.; Holst, Jens. J.; Stellaard, Frans; Vonk, Roel J.

    2006-01-01

    Glucagon-like pepticle-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) both play a role in the control of glucose homeostasis, and GIP is implicated in the regulation of energy storage. The capacity of carbohydrates to induce secretion of these incretin hormones could be one of the

  13. Statistical theory of diffusion in concentrated bcc and fcc alloys and concentration dependencies of diffusion coefficients in bcc alloys FeCu, FeMn, FeNi, and FeCr

    Energy Technology Data Exchange (ETDEWEB)

    Vaks, V. G.; Khromov, K. Yu., E-mail: khromov-ky@nrcki.ru; Pankratov, I. R. [National Research Center “Kurchatov Institute,” (Russian Federation); Popov, V. V. [Russian Academy of Sciences, Mikheev Institute of Metal Physics, Ural Branch (Russian Federation)

    2016-07-15

    The statistical theory of diffusion in concentrated bcc and fcc alloys with arbitrary pairwise interatomic interactions based on the master equation approach is developed. Vacancy–atom correlations are described using both the second-shell-jump and the nearest-neighbor-jump approximations which are shown to be usually sufficiently accurate. General expressions for Onsager coefficients in terms of microscopic interatomic interactions and some statistical averages are given. Both the analytical kinetic mean-field and the Monte Carlo methods for finding these averages are described. The theory developed is used to describe sharp concentration dependencies of diffusion coefficients in several iron-based alloy systems. For the bcc alloys FeCu, FeMn, and FeNi, we predict the notable increase of the iron self-diffusion coefficient with solute concentration c, up to several times, even though values of c possible for these alloys do not exceed some percent. For the bcc alloys FeCr at high temperatures T ≳ 1400 K, we show that the very strong and peculiar concentration dependencies of both tracer and chemical diffusion coefficients observed in these alloys can be naturally explained by the theory, without invoking exotic models discussed earlier.

  14. Non-Monotonic Survival of Staphylococcus aureus with Respect to Ciprofloxacin Concentration Arises from Prophage-Dependent Killing of Persisters

    Directory of Open Access Journals (Sweden)

    Elizabeth L. Sandvik

    2015-11-01

    Full Text Available Staphylococcus aureus is a notorious pathogen with a propensity to cause chronic, non-healing wounds. Bacterial persisters have been implicated in the recalcitrance of S. aureus infections, and this motivated us to examine the persistence of S. aureus to ciprofloxacin, a quinolone antibiotic. Upon treatment of exponential phase S. aureus with ciprofloxacin, we observed that survival was a non-monotonic function of ciprofloxacin concentration. Maximal killing occurred at 1 µg/mL ciprofloxacin, which corresponded to survival that was up to ~40-fold lower than that obtained with concentrations ≥ 5 µg/mL. Investigation of this phenomenon revealed that the non-monotonic response was associated with prophage induction, which facilitated killing of S. aureus persisters. Elimination of prophage induction with tetracycline was found to prevent cell lysis and persister killing. We anticipate that these findings may be useful for the design of quinolone treatments.

  15. Nonlinearity in Intensity versus Concentration Dependence for the Deep UV Resonance Raman Spectra of Toluene and Heptane

    DEFF Research Database (Denmark)

    Liu, Chuan; Berg, Rolf W.

    2013-01-01

    by absorption and Resonance Raman effects. Raman spectra of toluene and heptane mixtures - with progressively increasing concentrations of heptane - were measured by use of 229 nm excitation. The results show that the characteristic band intensities are not directly proportional to the relative concentrations...... of the compounds and deviate due to absorption resonance effects. An approximated mathematical model is developed to demonstrate that the intensities of the normal Raman scattering bands are suppressed. An inhibition coefficient Ki is introduced to describe the situation and determine the penetration depth. Most......The relation between Raman scattering, resonance Raman scattering and absorption is reviewed to see to what extent quantitative analysis can be applied in Resonance Raman spectroscopy. In addition to this it is demonstrated experimentally that normal Raman spectra can be dramatically inhibited...

  16. Non-Monotonic Survival of Staphylococcus aureus with Respect to Ciprofloxacin Concentration Arises from Prophage-Dependent Killing of Persisters

    Science.gov (United States)

    Sandvik, Elizabeth L.; Fazen, Christopher H.; Henry, Theresa C.; Mok, Wendy W.K.; Brynildsen, Mark P.

    2015-01-01

    Staphylococcus aureus is a notorious pathogen with a propensity to cause chronic, non-healing wounds. Bacterial persisters have been implicated in the recalcitrance of S. aureus infections, and this motivated us to examine the persistence of S. aureus to ciprofloxacin, a quinolone antibiotic. Upon treatment of exponential phase S. aureus with ciprofloxacin, we observed that survival was a non-monotonic function of ciprofloxacin concentration. Maximal killing occurred at 1 µg/mL ciprofloxacin, which corresponded to survival that was up to ~40-fold lower than that obtained with concentrations ≥ 5 µg/mL. Investigation of this phenomenon revealed that the non-monotonic response was associated with prophage induction, which facilitated killing of S. aureus persisters. Elimination of prophage induction with tetracycline was found to prevent cell lysis and persister killing. We anticipate that these findings may be useful for the design of quinolone treatments. PMID:26593926

  17. Simulated spatial and temporal dependence of chromium concentration in pure Fe and Fesbnd 14%Cr under high dpa ion irradiation

    Science.gov (United States)

    Vörtler, K.; Mamivand, M.; Barnard, L.; Szlufarska, I.; Garner, F. A.; Morgan, D.

    2016-10-01

    In this work we develop an ab initio informed rate theory model to track the spatial and temporal evolution of implanted ions (Cr+) in Fe and Fesbnd 14%Cr during high dose irradiation. We focus on the influence of the specimen surface, the depth dependence of ion-induced damage, the damage rate, and the consequences of ion implantation, all of which influence the depth dependence of alloy composition evolving with continued irradiation. We investigate chemical segregation effects in the material by considering the diffusion of the irradiation-induced defects. Moreover, we explore how temperature, grain size, grain boundary sink strength, and defect production bias modify the resulting distribution of alloy composition. Our results show that the implanted ion profile can be quite different than the predicted SRIM implantation profile due to radiation enhanced transport and segregation.

  18. Concentration- and age-dependent effects of chronic caffeine on contextual fear conditioning in C57BL/6J mice

    OpenAIRE

    Poole, Rachel L.; Braak, David; Gould, Thomas J.

    2015-01-01

    Chronic caffeine exerts negligible effects on learning and memory in normal adults, but it is unknown whether this is also true for children and adolescents. The hippocampus, a brain region important for learning and memory, undergoes extensive structural and functional modifications during pre-adolescence and adolescence. As a result, chronic caffeine may have differential effects on hippocampus-dependent learning in pre-adolescents and adolescents compared with adults. Here, we characterize...

  19. A complexity measure based method for studying the dependance of 222Rn concentration time series on indoor air temperature and humidity.

    Science.gov (United States)

    Mihailovic, D T; Udovičić, V; Krmar, M; Arsenić, I

    2014-02-01

    We have suggested a complexity measure based method for studying the dependence of measured (222)Rn concentration time series on indoor air temperature and humidity. This method is based on the Kolmogorov complexity (KL). We have introduced (i) the sequence of the KL, (ii) the Kolmogorov complexity highest value in the sequence (KLM) and (iii) the KL of the product of time series. The noticed loss of the KLM complexity of (222)Rn concentration time series can be attributed to the indoor air humidity that keeps the radon daughters in air.

  20. A complexity measure based method for studying the dependence of 222Rn concentration time series on indoor air temperature and humidity

    CERN Document Server

    Mihailovic, Dragutin T; Krmar, Miodrag; Arsenić, Ilija

    2013-01-01

    We have suggested a complexity measure based method for studying the dependence of measured 222Rn concentration time series on indoor air temperature and humidity. This method is based on the Kolmogorov complexity (KL). We have introduced (i) the sequence of the KL, (ii) the Kolmogorov complexity highest value in the sequence (KLM) and (iii) the KL of the product of time series. The noticed loss of the KLM complexity of 222Rn concentration time series can be attributed to the indoor air humidity that keeps the radon daughters in air.

  1. Low pH-Induced Pore Formation by the T Domain of Botulinum Toxin Type A is Dependent upon NaCl Concentration

    Energy Technology Data Exchange (ETDEWEB)

    Lai, B.; Swaminathan, S.; Agarwal, R.; Nelson, L. D.; London, E.

    2010-07-19

    Botulinum neurotoxins (BoNTs) undergo low pH-triggered membrane insertion, resulting in the translocation of their light (catalytic) chains into the cytoplasm. The T (translocation) domain of the BoNT heavy chain is believed to carry out translocation. Here, the behavior of isolated T domain from BoNT type A has been characterized, both in solution and when associated with model membranes. When BoNT T domain prepared in the detergent dodecylmaltoside was diluted into aqueous solution, it exhibited a low pH-dependent conformational change below pH 6. At low pH the T domain associated with, and formed pores within, model membrane vesicles composed of 30 mol% dioleoylphosphatidylglycerol/70 mol% dioleoylphosphatidylcholine. Although T domain interacted with vesicles at low (50 mM) and high (400 mM) NaCl concentrations, the interaction required much less lipid at low salt. However, even at high lipid concentrations pore formation was much more pronounced at low NaCl concentrations than at high NaCl concentration. Increasing salt concentration after insertion in the presence of 50 mM NaCl did not decrease pore formation. A similar effect of NaCl concentration upon pore formation was observed in vesicles composed solely of dioleoylphosphatidylcholine, showing that the effect of NaCl did not solely involve modulation of electrostatic interactions between protein and anionic lipids. These results indicate that some feature of membrane-bound T domain tertiary structure critical for pore formation is highly dependent upon salt concentration.

  2. Low concentrations of hydrogen peroxide or nitrite induced of Paracoccidioides brasiliensis cell proliferation in a Ras-dependent manner.

    Directory of Open Access Journals (Sweden)

    Ana Eliza Coronel Janu Haniu

    Full Text Available Paracoccidioides brasiliensis, a causative agent of paracoccidioidomycosis (PCM, should be able to adapt to dramatic environmental changes inside the infected host after inhalation of air-borne conidia and transition to pathogenic yeasts. Proteins with antioxidant functions may protect fungal cells against reactive oxygen (ROS and nitrogen (RNS species generated by phagocytic cells, thus acting as potential virulence factors. Ras GTPases are involved in stress responses, cell morphology, and differentiation in a range of organisms. Ras, in its activated form, interacts with effector proteins and can initiate a kinase cascade. In lower eukaryotes, Byr2 kinase represents a Ras target. The present study investigated the role of Ras in P. brasiliensis after in vitro stimulus with ROS or RNS. We have demonstrated that low concentrations of H2O2 (0.1 mM or NO2 (0.1-0.25 µM stimulated P. brasiliensis yeast cell proliferation and that was not observed when yeast cells were pre-incubated with farnesyltransferase inhibitor. We constructed an expression plasmid containing the Byr2 Ras-binding domain (RBD fused with GST (RBD-Byr2-GST to detect the Ras active form. After stimulation with low concentrations of H2O2 or NO2, the Ras active form was observed in fungal extracts. Besides, NO2 induced a rapid increase in S-nitrosylated Ras levels. This alternative posttranslational modification of Ras, probably in residue Cys123, would lead to an exchange of GDP for GTP and consequent GTPase activation in P. brasiliensis. In conclusion, low concentrations of H2O2 or NO2 stimulated P. brasiliensis proliferation through Ras activation.

  3. Mechanism-based pharmacokinetic-pharmacodynamic modeling of concentration-dependent hysteresis and biphasic electroencephalogram effects of alphaxalone in rats.

    Science.gov (United States)

    Visser, S A G; Smulders, C J G M; Reijers, B P R; Van der Graaf, P H; Peletier, L A; Danhof, M

    2002-09-01

    The neuroactive steroid alphaxalone reveals a complex biphasic concentration-effect relationship using the 11.5 to 30 Hz frequency band of the electroencephalogram (EEG) as biomarker. The purpose of the present investigation was to develop a mechanism-based pharmacokinetic-pharmacodynamic model to describe this observation. The proposed model is based on receptor theory and aims to separate the drug-receptor interaction from the transduction of the initial stimulus into the observed biphasic response. Individual concentration-time courses of alphaxalone were obtained in combination with continuous recording of the EEG parameter. Alphaxalone was administered intravenously in various dosages. The pharmacokinetics were described by a two-compartment model, and parameter estimates for clearance, intercompartmental clearance, volume of distribution 1 and 2 were 158 +/- 29 ml. min(-1). kg(-1), 143 +/- 31 ml. min(-1). kg(-1), 122 +/- 20 ml. kg(-1) and 606 +/- 48 ml. kg(-1), respectively. Concentration-effect relationships exhibited a biphasic pattern and delay in onset of effect. The hysteresis was described on the basis of an effect-compartment model with C(max) as covariate. The pharmacodynamic model consisted of a receptor model, featuring a monophasic saturable receptor activation model in combination with a biphasic stimulus-response model. The in vivo affinity (K(PD)) was estimated at 432 +/- 26 ng. ml(-1). Unique parameter estimates were obtained that were independent of the dose and the duration of the infusion. In conclusion, we have shown that this mechanism-based approach, which separates drug- and system-related properties in vivo, was successfully applied for the characterization of the biphasic effect versus time patterns of alphaxalone. The model should be of use in the characterization of other biphasic responses.

  4. Concentration and temperature dependence of viscosity of uranium solutions in H2O and 3 mol/L HNO3

    Institute of Scientific and Technical Information of China (English)

    QADEER Riaz

    2004-01-01

    Viscosities of uranium solutions in H2O and 3 mol/L HNO3 medium were measured by Ubbelhode flow viscometer in the concentration range of 0.5%-3.0% from 10 oC to 30 ℃ at 5 ℃ interval. Viscosity data were interpreted in terms of an empirical equation; η =aoexp(boM+coM2). Values of coefficients ao, bo and co were calculated for all the three systems studied. Flow activation energies and thermodynamic parameters were also evaluated.

  5. Photoinduced Transformation between Charge Carrier and Spin Carrier in Polymers

    Institute of Scientific and Technical Information of China (English)

    MEI Yuan; ZHAO Chang; SUN Xin

    2006-01-01

    By dynamical simulations, we show a transforming process between neutral soliton (spin carrier) and charged soliton (charge carrier) in polymers via photo-excitation, taking a polaron as the transitional bridge. It is photoinduced transformation between spin carrier and charge carrier. In this way, we demonstrate an access for polymers to be applied to spintronics.

  6. Dose-dependent ATP depletion and cancer cell death following calcium electroporation, relative effect of calcium concentration and electric field strength

    DEFF Research Database (Denmark)

    Hansen, Emilie Louise; Sozer, Esin Bengisu; Romeo, Stefania;

    2015-01-01

    death and could be a novel cancer treatment. This study aims at understanding the relationship between applied electric field, calcium concentration, ATP depletion and efficacy. METHODS: In three human cell lines--H69 (small-cell lung cancer), SW780 (bladder cancer), and U937 (leukaemia), viability...... was observed with fluorescence confocal microscopy of quinacrine-labelled U937 cells. RESULTS: Both H69 and SW780 cells showed dose-dependent (calcium concentration and electric field) decrease in intracellular ATP (p...-dependently reduced cell survival and intracellular ATP. Increasing extracellular calcium allows the use of a lower electric field. GENERAL SIGNIFICANCE: This study supports the use of calcium electroporation for treatment of cancer and possibly lowering the applied electric field in future trials....

  7. Concentration dependent effects of commonly used pesticides on activation versus inhibition of the quince (Cydonia Oblonga) polyphenol oxidase.

    Science.gov (United States)

    Fattouch, Sami; Raboudi-Fattouch, Faten; Ponce, José Vicente Gil; Forment, Josep Vicent; Lukovic, Dunja; Marzouki, Nejib; Vidal, Daniel Ramón

    2010-03-01

    Polyphenol oxidase (PPO) catalyzes the oxidation of o-diphenols to their respective quinones which undergo autopolymerization and form dark pigments. The interaction of PPO with various substrates and effectors remains the focus of intensive investigations due to the enzyme's key role in pigments biosynthesis including animal melanogenesis and fruit/fungi enzymatic browning. In this study, the effect of a range of commonly used pesticides on the enzyme activity has been evaluated using the purified quince (Cydonia oblonga Miller) PPO. The biochemical analysis showed that, in the presence of high pesticide concentrations, the enzyme was competitively inhibited, particularly with benomyl, carbaryl, deltamethrine and parathion methyl for which inhibition constants (K(i)) were 8.3, 5.7, 12 and 4 microM, respectively. At lower pesticide concentrations (2-10 microM), however, the catecholase activity was significantly activated (pCatechol substrate and parathion methyl inhibitor showed lower total energy scores of -120.06 and -117.4 3 kcal mol(-1), indicating that these ligands had higher PPO-binding affinities. The obtained data bring to light new pesticide functional features of great interest in the medicinal, agro-chemical and environmental circles.

  8. The nonmonotonic concentration dependence of the mean activity coefficient of electrolytes is a result of a balance between solvation and ion-ion correlations.

    Science.gov (United States)

    Vincze, Julianna; Valiskó, Mónika; Boda, Dezso

    2010-10-21

    We propose a simple model to explain the nonmonotonic concentration dependence of the mean activity coefficient of simple electrolytes without using any adjustable parameters. The primitive model of electrolytes is used to describe the interaction between ions computed by the adaptive grand canonical Monte Carlo method. For the dielectric constant of the electrolyte, we use experimental concentration dependent values. This is included through a solvation term in our treatment to describe the interaction between ions and water that changes as the dielectric constant changes with concentration. This term is computed by a Born-treatment fitted to experimental hydration energies. Our results for LiCl, NaCl, KCl, CsCl, NaBr, NaI, MgCl(2), CaCl(2), SrCl(2), and BaCl(2) demonstrate that the principal reason of the nonmonotonic behavior of the activity coefficient is a balance between the solvation and ion-ion correlation terms. This conclusion differs from previous studies that assumed that it is the balance of hard sphere repulsion and electrostatic attraction that produces the nonmonotonic behavior. Our results indicate that the earlier assumption that solvation can be taken into account by a larger, "solvated" ionic radius should be reconsidered. To explain second order effects (such as dependence on ionic size), we conclude that explicit water models are needed.

  9. Anomalous spreading of a density front from an infinite continuous source in a concentration-dependent lattice gas automaton diffusion model

    CERN Document Server

    Kuentz, M

    2003-01-01

    A two-dimensional lattice gas automaton (LGA) is used for simulating concentration-dependent diffusion in a microscopically random heterogeneous structure. The heterogeneous medium is initialized at a low density rho sub 0 and then submitted to a steep concentration gradient by continuous injection of particles at a concentration rho sub 1 >rho sub 0 from a one-dimensional source to model spreading of a density front. Whereas the nonlinear diffusion equation generally used to describe concentration-dependent diffusion processes predicts a scaling law of the type phi = xt sup - sup 1 sup / sup 2 in one dimension, the spreading process is shown to deviate from the expected t sup 1 sup / sup 2 scaling. The time exponent is found to be larger than 1/2, i.e. diffusion of the density front is enhanced with respect to standard Fickian diffusion. It is also established that the anomalous time exponent decreases as time elapses: anomalous spreading is thus not a timescaling process. We demonstrate that occurrence of a...

  10. Membrane potential and Ca2+ concentration dependence on pressure and vasoactive agents in arterial smooth muscle: A model.

    Science.gov (United States)

    Karlin, Arthur

    2015-07-01

    Arterial smooth muscle (SM) cells respond autonomously to changes in intravascular pressure, adjusting tension to maintain vessel diameter. The values of membrane potential (Vm) and sarcoplasmic Ca(2+) concentration (Ca(in)) within minutes of a change in pressure are the results of two opposing pathways, both of which use Ca(2+) as a signal. This works because the two Ca(2+)-signaling pathways are confined to distinct microdomains in which the Ca(2+) concentrations needed to activate key channels are transiently higher than Ca(in). A mathematical model of an isolated arterial SM cell is presented that incorporates the two types of microdomains. The first type consists of junctions between cisternae of the peripheral sarcoplasmic reticulum (SR), containing ryanodine receptors (RyRs), and the sarcolemma, containing voltage- and Ca(2+)-activated K(+) (BK) channels. These junctional microdomains promote hyperpolarization, reduced Ca(in), and relaxation. The second type is postulated to form around stretch-activated nonspecific cation channels and neighboring Ca(2+)-activated Cl(-) channels, and promotes the opposite (depolarization, increased Ca(in), and contraction). The model includes three additional compartments: the sarcoplasm, the central SR lumen, and the peripheral SR lumen. It incorporates 37 protein components. In addition to pressure, the model accommodates inputs of α- and β-adrenergic agonists, ATP, 11,12-epoxyeicosatrienoic acid, and nitric oxide (NO). The parameters of the equations were adjusted to obtain a close fit to reported Vm and Ca(in) as functions of pressure, which have been determined in cerebral arteries. The simulations were insensitive to ± 10% changes in most of the parameters. The model also simulated the effects of inhibiting RyR, BK, or voltage-activated Ca(2+) channels on Vm and Ca(in). Deletion of BK β1 subunits is known to increase arterial-SM tension. In the model, deletion of β1 raised Ca(in) at all pressures, and these

  11. Visible-light photoconductivity of Zn1-xCoxO and its dependence on Co2+ concentration

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Claire A.; Cohn, Alicia; Kaspar, Tiffany C.; Chambers, Scott A.; Salley, G. Mackay; Gamelin, Daniel R.

    2011-09-06

    Many metal oxides investigated for solar photocatalysis or photoelectrochemistry have band gaps that are too wide to absorb a sufficient portion of the solar spectrum. Doping with impurity ions has been extensively explored as a strategy to sensitize such oxides to visible light, but the electronic structures of the resulting materials are frequently complex and poorly understood. Here, we report a detailed photoconductivity investigation of the wide-gap II-VI semiconductor ZnO doped with Co2+ (Zn1-xCoxO), which responds to visible light in photoelectrochemical and photoconductivity experiments and thus represents a well-defined model system for understanding dopant-sensitized oxides. Variable-temperature scanning photoconductivity measurements have been performed on high-structural-quality Zn1-xCoxO epitaxial films to examine the relationship between dopant concentration (x) and visible-light photoconductivity, with particular focus on mid-gap d-d photoactivity. Excitation into the intense 4T1(P) d-d band at ~2.0 eV (620 nm) leads to Co2+/3+ ionization with a quantum efficiency that increases with decreasing cobalt concentration and increasing sample temperature. Both spontaneous and thermally assisted ionization from the Co2+ d-d excited state are found to become less effective as x is increased, attributed to an increasing conduction-band-edge potential. These trends counter the increasing light absorption with increasing x, explaining the experimental maximum in external photon-to-current conversion efficiencies at values well below the solid solubility of Co2+ in ZnO.

  12. Hardening with salicylic acid induces concentration-dependent changes in abscisic acid biosynthesis of tomato under salt stress.

    Science.gov (United States)

    Horváth, Edit; Csiszár, Jolán; Gallé, Ágnes; Poór, Péter; Szepesi, Ágnes; Tari, Irma

    2015-07-01

    The role of salicylic acid (SA) in the control of abscisic acid (ABA) biosynthesis is controversial although both plant growth regulators may accumulate in tissues under abiotic and biotic stress conditions. Hardening of tomato plants to salinity stress with 10(-4)M SA ("high SA") resulted in an up-regulation of ABA biosynthesis genes, zeaxanthin epoxidase (SlZEP1), 9-cis-epoxycarotenoid dioxygenase (SlNCED1) and aldehyde oxidases (SlAO1 and SlAO2) in the roots and led to ABA accumulation both in root and leaf tissues. In plants pre-treated with lower concentration of SA (10(-7)M, "low SA"), the up-regulation of SlNCED1 in the roots promoted ABA accumulation in the root tissues but the hormone concentration remained at control level in the leaves. Salt stress induced by 100mM NaCl reduced the transcript abundance of ABA biosynthetic genes and inhibited SlAO activity in plants hardened with "high SA", but the tissues maintained root ABA level over the untreated control. The combined effect of "high SA" and ABA under salt stress led to partially recovered photosynthetic activity, reduced ethylene production in root apices, and restored root growth, which is one of the main features of salt tolerance. Unlike "high SA", hardening with "low SA" had no influence on ethylene production, and led to reduced elongation of roots in plants exposed to 100mM NaCl. The up-regulation of carotenoid cleavage dioxygenases SlCCD1A and SlCCD1B by SA, which produce apocarotenoids, may open new pathways in SA sensing and signalling processes.

  13. Determining the size and concentration dependence of gold nanoparticles in vitro cytotoxicity (IC{sub 50}) test using WST-1 assay

    Energy Technology Data Exchange (ETDEWEB)

    Rosli, Nur Shafawati binti; Rahman, Azhar Abdul [School of Physics, Universiti Sains Malaysia, 11800, Pulau Pinang (Malaysia); Aziz, Azlan Abdul [School of Physics, Universiti Sains Malaysia, 11800, Pulau Pinang (Malaysia); Nano-Biotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800, Pulau Pinang (Malaysia); Shamsuddin, Shaharum [Nano-Biotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800, Pulau Pinang (Malaysia); School of Health Sciences, Health Campus, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan (Malaysia)

    2015-04-24

    Gold nanoparticles (AuNPs) received a great deal of attention for biomedical applications, especially in diagnostic imaging and therapeutics. Even though AuNPs have potential benefits in biomedical applications, the impact of AuNPs on human and environmental health still remains unclear. The use of AuNPs which is a high-atomic-number materials, provide advantages in terms of radiation dose enhancement. However, before this can become a clinical reality, cytotoxicity of the AuNPs has to be carefully evaluated. Cytotoxicity test is a rapid, standardized test that is very sensitive to determine whether the nanoparticles produced are harmful or benign on cellular components. In this work the size and concentration dependence of AuNPs cytotoxicity in breast cancer cell lines (MCF-7) are tested by using WST-1 assay. The sizes of AuNPs tested were 13 nm, 50 nm, and 70 nm. The cells were seeded in the 96-well plate and were treated with different concentrations of AuNPs by serial dilution for each size of AuNPs. The high concentration of AuNPs exhibit lower cell viability compared to low concentration of AuNPs. We quantified the toxicity of AuNPs in MCF-7 cell lines by determining the IC{sub 50} values in WST-1 assays. The IC{sub 50} values (inhibitory concentrations that effected 50% growth inhibition) of 50 nm AuNPs is lower than 13 nm and 70 nm AuNPs. Mean that, 50nm AuNPs are more toxic to the MCF-7 cells compared to smaller and larger sizes AuNPs. The presented results clearly indicate that the cytotoxicity of AuNPs depend not only on the concentration, but also the size of the nanoparticles.

  14. Asymmetrical dimethylarginine plasma concentrations are related to basal nitric oxide release but not endothelium-dependent vasodilation of resistance arteries in peritoneal dialysis patients.

    Science.gov (United States)

    Mittermayer, Friedrich; Schaller, Georg; Pleiner, Johannes; Vychytil, Andreas; Sunder-Plassmann, Gere; Hörl, Walter H; Wolzt, Michael

    2005-06-01

    Vascular dysfunction in chronic renal failure may be linked to reduced nitric oxide (NO) bioactivity and increased circulating concentrations of the endogenous NO synthase inhibitor asymmetrical dimethyl L-arginine (ADMA). The association between ADMA and basal endothelial NO release and endothelium-dependent vasodilation in resistance arteries of chronic renal failure patients is unknown. Forearm blood flow responses to the endothelium-dependent vasodilator acetylcholine, the endothelium-independent vasodilator nitroglycerine, and the endothelium-dependent vasoconstrictor N(G)-monomethyl-L-arginine (L-NMMA) were assessed in 37 peritoneal dialysis patients. L-arginine and ADMA plasma concentrations were measured by HPLC. ADMA (mean +/- SEM: 0.68 +/- 0.02 micromol/L) was associated with basal forearm blood flow (r = -0.33; P < 0.05) and L-NMMA induced vasoconstriction (r = -0.55; P < 0.0005), but not with dilator effects of acetylcholine or nitroglycerine. L-arginine (68 +/- 3 micromol/L) tended to correlate with acetylcholine-induced vasodilation (r = 0.32; P = 0.05) but was not associated with other parameters. ADMA is related to basal but not to acetylcholine-stimulated NO bioactivity in patients on peritoneal dialysis. Impaired endothelium-dependent vasodilation found in chronic renal failure is not explained by elevated circulating NO synthase inhibitors in renal failure.

  15. Effects of PVA and PEG on pH Dependent Shear Yield Stress of Concentrated Alumina Suspensions

    Institute of Scientific and Technical Information of China (English)

    ZHENGRenjie; B.RAND

    2002-01-01

    The pH dependence of the extrapolated shear yield stress for Alcoa A16 α-Al2O3 suspensions at the powder volume fraction of 0.27 with and without addition of both polyvinyl alcohol (PVA) and polyethylene glycol (PEG) each at fixed 0.18% of the powder mass was studied. Whith the polymer added, the full deflocculation of the suspension shifts from about pH=4 to around pH=1.5, at which the minimum value of shear yied stress is higher than that at pH=4. The addition of both PVA and PEG was found to prevent the filter cake from cracking.

  16. The value of energy carriers

    NARCIS (Netherlands)

    Gool, W. van

    1987-01-01

    The value of energy carriers can be described thermodynamically by the amount of heat (enthalpy method) or work (exergy or availability method) that can be obtained from the carriers. Prices for energy carriers are used in economics to express their values. The prices for energy carriers are often r

  17. Short minority carrier lifetimes in highly nitrogen-doped 4H-SiC epilayers for suppression of the stacking fault formation in PiN diodes

    Science.gov (United States)

    Tawara, T.; Miyazawa, T.; Ryo, M.; Miyazato, M.; Fujimoto, T.; Takenaka, K.; Matsunaga, S.; Miyajima, M.; Otsuki, A.; Yonezawa, Y.; Kato, T.; Okumura, H.; Kimoto, T.; Tsuchida, H.

    2016-09-01

    We investigated the dependency of minority carrier lifetimes on the nitrogen concentration, temperature, and the injected carrier concentration for highly nitrogen-doped 4H-SiC epilayers. The minority carrier lifetimes greatly shortened when the nitrogen concentration exceeded 1018 cm-3 through enhancing direct band-to-band and Auger recombination and showed a slight variation in the temperature range from room temperature (RT) to 250 °C. The epilayer with a nitrogen concentration of 9.3 × 1018 cm-3 exhibited a very short minority carrier lifetime of 38 ns at RT and 43 ns at 250 °C. The short minority carrier lifetimes of the highly nitrogen-doped epilayer were confirmed to maintain the values even after the subsequent annealing of 1700 °C. 4H-SiC PiN diodes were fabricated by depositing a highly nitrogen-doped epilayer as a "recombination enhancing layer" between an n- drift layer free from basal plane dislocations and the substrate. The PiN diodes showed no formation of stacking faults and no increase in forward voltage during current conduction of 600 A/cm2 (DC), demonstrating that a highly nitrogen-doped buffer layer with a short minority carrier lifetime successfully suppresses the "bipolar degradation" phenomenon.

  18. Radio Science Measurements with Suppressed Carrier

    Science.gov (United States)

    Asmar, Sami; Divsalar, Dariush; Oudrhiri, Kamal

    2013-01-01

    Radio Science started when it became apparent with early Solar missions that occultations by planetary atmospheres would affect the quality of radio communications. Since then the atmospheric properties and other aspects of planetary science, solar science, and fundamental physics were studied by scientists. Radio Science data was always extracted from a received pure residual carrier (without data modulation). For some missions, it is very desirable to obtain Radio Science data from a suppressed carrier modulation. In this paper we propose a method to extract Radio Science data when a coded suppressed carrier modulation is used in deep space communications. Type of modulation can be BPSK, QPSK, OQPSK, MPSK or even GMSK. However we concentrate mostly on BPSK modulation. The proposed method for suppressed carrier simply tries to wipe out data that acts as an interference for Radio Science measurements. In order to measure the estimation errors in amplitude and phase of the Radio Science data we use Cramer-Rao bound (CRB). The CRB for the suppressed carrier modulation with non-ideal data wiping is then compared with residual carrier modulation under the same noise condition. The method of derivation of CRB for non-ideal data wiping is an innovative method that presented here. Some numerical results are provided for coded system.

  19. Charge-carrier mobilities in disordered semiconducting polymers: effects of carrier density and electric field

    Science.gov (United States)

    Meisel, K. D.; Pasveer, W. F.; Cottaar, J.; Tanase, C.; Coehoorn, R.; Bobbert, P. A.; Blom, P. W. M.; de Leeuw, D. M.; Michels, M. A. J.

    2006-02-01

    We model charge transport in disordered semiconducting polymers by hopping of charge carriers on a square lattice of sites with Gaussian on-site energy disorder, using Fermi-Dirac statistics. From numerically exact solutions of the Master equation, we study the dependence of the charge-carrier mobility on temperature, carrier density, and electric field. Our results are used in calculating current-voltage characteristics of hole-only polymer diodes. It is found that very good fits to experimental current-voltage characteristics can be obtained at different temperatures, with reasonable fitting parameters for the width of the Gaussian density of states and the lattice constant. In agreement with the experiments we find that the density dependence is dominant over the field dependence. Only at high fields and low temperatures the field dependence becomes noticeable. The potential and current distribution show strong inhomogeneities, which may have important consequences for the operation of polymer opto-electronic devices.

  20. Observed Dependence of Colloid Detachment on the Concentration of Initially Attached Colloids and Collector Surface Heterogeneity in Porous Media.

    Science.gov (United States)

    Li, Tiantian; Jin, Yan; Huang, Yuanfang; Li, Baoguo; Shen, Chongyang

    2017-03-07

    Sand column experiments were conducted to examine the effects of the concentration of attached colloids (CAC) on their subsequent detachment upon decreasing solution ionic strength (IS). Different pore volumes of latex microparticle suspensions were injected into the columns to allow different amounts of colloids to attach at ISs of 0.001, 0.01, and 0.2 M. Then, deionized water was introduced to release the attached colloids. Results show that the fraction of attachments that were reversible to reduction of IS (FRA) increased with increasing CAC at a given IS if the sand was extensively treated using acids to reduce surface charge heterogeneity. This indicates that colloids were preferentially immobilized in sites favoring irreversible attachment and then gradually occupied reversible sites. In contrast, the FRA decreased with increasing CAC at 0.001 M in sand without the acid treatment, illustrating the opposite attachment sequence. Scanning electron microscope examinations reveal that the concave regions favored irreversible colloid attachment. Reversible attachment is likely due to immobilization on flat surfaces with charge heterogeneities, retention in stagnation point regions via secondary minimum association, ripening in the acid-treated sand, and capture of colloids by protruding asperities with charge heterogeneity in the untreated sand. At ISs of 0.01 and 0.2 M, the FRA was essentially independent of CAC in the untreated sand because the colloids were randomly attached on the sand surfaces over time.

  1. The survival of cultured mouse cerebellar granule cells is not dependent on elevated potassium-ion concentration

    DEFF Research Database (Denmark)

    Mogensen, Helle Smidt; Hack, N; Balázs, R

    1994-01-01

    The effects of K(+)-induced membrane depolarization were studied on the survival and biochemical parameters in mouse and rat cerebellar granule cells grown in micro-well cultures. Cell numbers were determined by estimating DNA content using the Hoechst 33258 fluorochrome binding assay. DNA from d...... that although cultivation in 'high' K+ promotes biochemical differentiation in mouse cerebellar granule cells, these cells differ from their rat counterparts in that they do not develop a survival requirement for K(+)-induced membrane depolarization.......The effects of K(+)-induced membrane depolarization were studied on the survival and biochemical parameters in mouse and rat cerebellar granule cells grown in micro-well cultures. Cell numbers were determined by estimating DNA content using the Hoechst 33258 fluorochrome binding assay. DNA from...... degenerated cells was removed by prior DNAase treatment. These DNA estimates of cell numbers were comparable with values obtained by direct counting of fluorescein diacetate-stained viable cells. In agreement with previous studies, the survival of rat granule cells was promoted by increasing the concentration...

  2. Cr concentration dependence of overestimation of long term creep life in strength enhanced high Cr ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Maruyama, K., E-mail: maruyama@material.tohoku.ac.j [Graduate School of Environmental Studies, Tohoku University, 6-6-02 Aobayama, Sendai 980-8579 (Japan); Ghassemi Armaki, H.; Chen, R.P.; Yoshimi, K. [Graduate School of Environmental Studies, Tohoku University, 6-6-02 Aobayama, Sendai 980-8579 (Japan); Yoshizawa, M.; Igarashi, M. [Corporate Research and Development Laboratories, Sumitomo Metal Industry, Ltd., 1-8 Fuso-Cho, Amagasaki 660-0891 (Japan)

    2010-06-15

    Creep rupture data and microstructural degradation during aging of high Cr ferritic boiler steels with enhanced creep strength have been studied with special attention to prediction of long term creep rupture life. Tempered lath martensite structure in the high Cr ferritic steels remains unchanged during short term aging, whereas static recovery of the lath martensite structure proceeds when diffusion distance during aging becomes sufficiently long as is the case in long term creep. The static recovery brings about premature failure in long term creep and decreases in apparent activation energy for creep life. The decrease in activation energy is responsible for overestimation of rupture life reported in strength enhanced high Cr ferritic steels. The boundary from a short term region with high activation energy Q{sub H} to a long term region with low activation energy Q{sub L} moves towards longer time with decreasing Cr concentration. The difference in activation energy (Q{sub H} - Q{sub L}) primarily determines the extent of overestimation of rupture life predicted from short term data. In general, the extent of overestimation is less serious at 9%Cr as compared to 12%Cr.

  3. Concentration Dependence of Luminescent Properties for Sr2TiO4:Eu3+ Red Phosphor and Its Charge Compensation

    Directory of Open Access Journals (Sweden)

    Zhou Lu

    2012-01-01

    Full Text Available Sr2TiO4:Eu3+ phosphors using M+ (M = Li+, Na+, and K+ as charge compensators were prepared by the solid-state reaction. The powders were investigated by powder X-ray diffraction (XRD and photoluminescence spectra (PL to study the phase composition, structure, and luminescent properties. The results showed that Li+ ion was the best charge compensator. The phase was Sr2TiO4 when the doping concentration was small (x≤10.0%. When x reached 15.0%, the phase turned into Sr3Ti3O7 because of the structure damage. The phosphor could be effectively excited by ultraviolet (365, 395 nm and blue light (465 nm, and thenitemitted intense red light that peaked at around 620 nm (5D0→7F2. In addition, the emission of 700 nm (5D0→7F4 enhanced the red light color purity. The CIE chromaticity coordinates of samples with the higher red emission were between (0.650, 0.344 and (0.635, 0.352. Doped layered titanate Sr2TiO4:Eu3+ is a promising candidate red phosphor for white LEDs which can be suited for both near-UV LED chip and blue LED chip.

  4. Age-Dependent Variation in Hormonal Concentration and Biochemical Constituents in Blood Plasma of Indian Native Fowl

    Directory of Open Access Journals (Sweden)

    Avishek Biswas

    2010-01-01

    Full Text Available This experiment was to investigate the age-related changes in hormonal concentration and biochemical constituents of blood plasma in Indian native desi fowl. One hundred and sixty two (54 from each breed, i.e., Kadaknath (KN, Aseel peela (AP, and White leghorn (WLH day-old female chicks were randomly divided into nine groups each of 18 chicks (3 groups × 3 replicates. WLH was taken in this study to compare the characteristics of Indian native desi fowl. The highest level of estrogen hormone in WLH and desi fowl in blood plasma was occurred at 18 and 24 wks of age, respectively. Whereas, the peak of progesterone hormone in WLH hens noticed around 24 wks, in case of desi fowls, it was at 30 wks of age. Irrespective of the breed, the hormonal profile of Triiodothyronine (T3 and Thyroxine (T4 in blood plasma was found highest around 6 to 12 wks of age. Activities of acid phosphatase (ACP increased with the reduction of alkaline phosphate (ALP activities at different time intervals. Irrespective of the breed, transaminases (glutamic oxaloacetic transaminase (GOT and glutamic pyruvic transaminase (GPT activities of blood plasma increased linearly with the advancement of the age. From this study, it may be concluded that sexual maturity of the Indian native desi fowl occurred nearly 6 wk later (24 wk than WLH.

  5. The effect of 3-bromopyruvate on human colorectal cancer cells is dependent on glucose concentration but not hexokinase II expression.

    Science.gov (United States)

    Ho, Nelson; Morrison, Jodi; Silva, Andreza; Coomber, Brenda L

    2016-01-06

    Cancer cells heavily rely on the glycolytic pathway regardless of oxygen tension. Hexokinase II (HKII) catalyses the first irreversible step of glycolysis and is often overexpressed in cancer cells. 3-Bromopyruvate (3BP) has been shown to primarily target HKII, and is a promising anti-cancer compound capable of altering critical metabolic pathways in cancer cells. Abnormal vasculature within tumours leads to heterogeneous microenvironments, including glucose availability, which may affect drug sensitivity. The aim of the present study was to elucidate the mechanisms by which 3BP acts on colorectal cancer (CRC) cells with focus on the HKII/Akt signalling axis. High HKII-expressing cell lines were more sensitive to 3BP than low HKII-expressing cells. 3BP-induced rapid Akt phosphorylation at site Thr-308 and cell death via both apoptotic and necrotic mechanisms. Cells grown under lower glucose concentrations showed greater resistance towards 3BP. Cells with HKII knockdown showed no changes in 3BP sensitivity, suggesting the effects of 3BP are independent of HKII expression. These results emphasize the importance of the tumour microenvironment and glucose availability when considering therapeutic approaches involving metabolic modulation.

  6. Carrier transport uphill. I. General

    DEFF Research Database (Denmark)

    Rosenberg, T; Wilbrandt, W

    1963-01-01

    A quantitative treatment of a carrier pump operating with two carrier forms C and Z is presented. Asymmetric metabolic reactions are assumed to transform Z into C on one and C into Z on the other side of the membrane, establishing a carrier cycle. The kinetical consequences of this mechanism...... concords with equilibrating carrier systems in all characteristic kinetical features is taken to indicate that the carrier mechanism contributes more to the characteristic transport features than the connection with metabolism....

  7. Temperature dependence of the particle/gas partition coefficient: An application to predict indoor gas-phase concentrations of semi-volatile organic compounds.

    Science.gov (United States)

    Wei, Wenjuan; Mandin, Corinne; Blanchard, Olivier; Mercier, Fabien; Pelletier, Maud; Le Bot, Barbara; Glorennec, Philippe; Ramalho, Olivier

    2016-09-01

    The indoor gas-phase concentrations of semi-volatile organic compounds (SVOCs) can be predicted from their respective concentrations in airborne particles by applying the particle/gas partitioning equilibrium. The temperature used for partitioning is often set to 25°C. However, indoor temperatures frequently differ from this reference value. This assumption may result in errors in the predicted equilibrium gas-phase SVOC concentrations. To improve the prediction model, the temperature dependence of the particle/gas partition coefficient must be addressed. In this paper, a theoretical relationship between the particle/gas partition coefficient and temperature was developed based on the SVOC absorptive mechanism. The SVOC particle/gas partition coefficients predicted by employing the derived theoretical relationship agree well with the experimental data retrieved from the literature (R>0.93). The influence of temperature on the equilibrium gas-phase SVOC concentration was quantified by a dimensionless analysis of the derived relationship between the SVOC particle/gas partition coefficient and temperature. The predicted equilibrium gas-phase SVOC concentration decreased by between 31% and 53% when the temperature was lowered by 6°C, while it increased by up to 750% when the indoor temperature increased from 15°C to 30°C.

  8. Molar Absorptivity and Concentration-Dependent Quantum Yield of Fe(II) Photo-Formation for the Aqueous Solutions of Fe(III)-Dicarboxylate Complexes

    Science.gov (United States)

    Hitomi, Y.; Arakaki, T.

    2009-12-01

    Redox cycles of iron in the aquatic environment affect formation of reactive oxygen species such as hydrogen peroxide and hydroxyl radicals, which in turn determines lifetimes of many organic compounds. Although aqueous Fe(III)-dicarboxylate complexes are considered to be important sources of photo-formed Fe(II), molar absorptivity and quantum yield of Fe(II) formation for individual species are not well understood. We initiated a study to characterize Fe(II) photo-formation from Fe(III)-dicarboxylates with the concentration ranges that are relevant to the natural aquatic environment. The Visual MINTEQ computer program was used to calculate the equilibrium concentrations of individual Fe(III)-dicarboxylate species. The molar absorptivity of Fe(III)-dicarboxylate species was obtained by UV-VIS spectrophotometer, and the product of the quantum yield and the molar absorptivity of Fe(III)-dicarboxylate species were obtained from photochemical experiments. These experimental data were combined with the calculated equilibrium Fe(III)-dicarboxylate concentrations to determine individual molar absorptivity and quantum yield of Fe(II) photo-formation for a specific Fe(III)-dicarboxylate species. We used initial concentrations of less than 10 micromolar Fe(III) to study the photochemical formation of Fe(II). Dicarboxylate compounds studied include oxalate, malonate, succinate, malate, and phthalate. We report molar absorptivity and concentration-dependent quantum yields of Fe(II) photo-formation of individual Fe(III)-dicarboxylates.

  9. Temperature dependence of the particle/gas partition coefficient: An application to predict indoor gas-phase concentrations of semi-volatile organic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Wenjuan, E-mail: Wenjuan.Wei@cstb.fr [University of Paris-Est, Scientific and Technical Center for Building (CSTB), Health and Comfort Department, French Indoor Air Quality Observatory (OQAI), 84 Avenue Jean Jaurès, Champs sur Marne, 77447 Marne la Vallée Cedex 2 (France); Mandin, Corinne [University of Paris-Est, Scientific and Technical Center for Building (CSTB), Health and Comfort Department, French Indoor Air Quality Observatory (OQAI), 84 Avenue Jean Jaurès, Champs sur Marne, 77447 Marne la Vallée Cedex 2 (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); LERES-Environment and Health Research Laboratory (Irset and EHESP Technologic Platform), Rennes (France); Blanchard, Olivier [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); Mercier, Fabien [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); LERES-Environment and Health Research Laboratory (Irset and EHESP Technologic Platform), Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); Pelletier, Maud [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); Le Bot, Barbara [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); LERES-Environment and Health Research Laboratory (Irset and EHESP Technologic Platform), Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); and others

    2016-09-01

    The indoor gas-phase concentrations of semi-volatile organic compounds (SVOCs) can be predicted from their respective concentrations in airborne particles by applying the particle/gas partitioning equilibrium. The temperature used for partitioning is often set to 25 °C. However, indoor temperatures frequently differ from this reference value. This assumption may result in errors in the predicted equilibrium gas-phase SVOC concentrations. To improve the prediction model, the temperature dependence of the particle/gas partition coefficient must be addressed. In this paper, a theoretical relationship between the particle/gas partition coefficient and temperature was developed based on the SVOC absorptive mechanism. The SVOC particle/gas partition coefficients predicted by employing the derived theoretical relationship agree well with the experimental data retrieved from the literature (R > 0.93). The influence of temperature on the equilibrium gas-phase SVOC concentration was quantified by a dimensionless analysis of the derived relationship between the SVOC particle/gas partition coefficient and temperature. The predicted equilibrium gas-phase SVOC concentration decreased by between 31% and 53% when the temperature was lowered by 6 °C, while it increased by up to 750% when the indoor temperature increased from 15 °C to 30 °C. - Highlights: • A theoretical relationship between K{sub p} and temperature was developed. • The relationship was based on the SVOC absorptive mechanism. • The temperature impact was quantified by a dimensionless analysis.

  10. Revealing mechanisms of selective, concentration-dependent potentials of 4-hydroxy-2-nonenal to induce apoptosis in cancer cells through inactivation of membrane-associated catalase.

    Science.gov (United States)

    Bauer, Georg; Zarkovic, Neven

    2015-04-01

    Tumor cells generate extracellular superoxide anions and are protected against superoxide anion-mediated intercellular apoptosis-inducing signaling by the expression of membrane-associated catalase. 4-Hydroxy-2-nonenal (4-HNE), a versatile second messenger generated during lipid peroxidation, has been shown to induce apoptosis selectively in malignant cells. The findings described in this paper reveal the strong, concentration-dependent potential of 4-HNE to specifically inactivate extracellular catalase of tumor cells both indirectly and directly and to consequently trigger apoptosis in malignant cells through superoxide anion-mediated intercellular apoptosis-inducing signaling. Namely, 4-HNE caused apoptosis selectively in NOX1-expressing tumor cells through inactivation of their membrane-associated catalase, thus reactivating subsequent intercellular signaling through the NO/peroxynitrite and HOCl pathways, followed by the mitochondrial pathway of apoptosis. Concentrations of 4-HNE of 1.2 µM and higher directly inactivated membrane-associated catalase of tumor cells, whereas at lower concentrations, 4-HNE triggered a complex amplificatory pathway based on initial singlet oxygen formation through H2O2 and peroxynitrite interaction. Singlet-oxygen-dependent activation of the FAS receptor and caspase-8 increased superoxide anion generation by NOX1 and amplification of singlet oxygen generation, which allowed singlet-oxygen-dependent inactivation of catalase. 4-HNE and singlet oxygen cooperate in complex autoamplificatory loops during this process. The finding of these novel anticancer pathways may be useful for understanding the role of 4-HNE in the control of malignant cells and for the optimization of ROS-dependent therapeutic approaches including antioxidant treatments.

  11. An effective approach for the minimization of errors in capacitance-voltage carrier profiling of quantum structures

    Energy Technology Data Exchange (ETDEWEB)

    Biswas, Dipankar, E-mail: diiibiswas@yahoo.co.in; Panda, Siddhartha [Institute of Radiophysics and Electronics, University of Calcutta, 92 A. P. C. Road, Kolkata 700009 (India)

    2014-04-07

    Experimental capacitance–voltage (C-V) profiling of semiconductor heterojunctions and quantum wells has remained ever important and relevant. The apparent carrier distributions (ACDs) thus obtained reveal the carrier depletions, carrier peaks and their positions, in and around the quantum structures. Inevitable errors, encountered in such measurements, are the deviations of the peak concentrations of the ACDs and their positions, from the actual carrier peaks obtained from quantum mechanical computations with the fundamental parameters. In spite of the very wide use of the C-V method, comprehensive discussions on the qualitative and quantitative nature of the errors remain wanting. The errors are dependent on the fundamental parameters, the temperature of measurements, the Debye length, and the series resistance. In this paper, the errors have been studied with doping concentration, band offset, and temperature. From this study, a rough estimate may be drawn about the error. It is seen that the error in the position of the ACD peak decreases at higher doping, higher band offset, and lower temperature, whereas the error in the peak concentration changes in a strange fashion. A completely new method is introduced, for derivation of the carrier profiles from C-V measurements on quantum structures to minimize errors which are inevitable in the conventional formulation.

  12. The mechanism of amyloid-fibril formation by stefin B: temperature and protein concentration dependence of the rates.

    Science.gov (United States)

    Skerget, Katja; Vilfan, Andrej; Pompe-Novak, Marusa; Turk, Vito; Waltho, Jonathan P; Turk, Dusan; Zerovnik, Eva

    2009-02-01

    Cystatins, a family of structurally related cysteine proteinase inhibitors, have proved to be useful model system to study amyloidogenesis. We have extended previous studies of the kinetics of amyloid-fibril formation by human stefin B (cystatin B) and some of its mutants, and proposed an improved model for the reaction. Overall, the observed kinetics follow the nucleation and growth behavior observed for many other amyloidogenic proteins. The minimal kinetic scheme that best fits measurements of changes in CD and thioflavin T fluorescence as a function of protein concentration and temperature includes nucleation (modeled as N(I) irreversible transitions with equivalent rates (k(I)), which fitted with N(I) = 64), fibril growth and nonproductive oligomerization, best explained by an off-pathway state with a rate-limiting escape rate. Three energies of activation were derived from global fitting to the minimal kinetic scheme, and independently through the fitting of the individual component rates. Nucleation was found to be a first-order process within an oligomeric species with an enthalpy of activation of 55 +/- 4 kcal mol(-1). Fibril growth was a second-order process with an enthalpy of activation (27 +/- 5 kcal mol(-1)), which is indistinguishable from that of tetramer formation by cystatins, which involves limited conformational changes including proline trans to cis isomerization. The highest enthalpy of activation (95 +/- 5 kcal mol(-1) at 35 degrees C), characteristic of a substantial degree of unfolding as observed prior to domain-swapping reactions, equated with the escape rate of the off-pathway oligomeric state.

  13. Concentration-Dependent Synergy and Antagonism of Linezolid and Moxifloxacin in the Treatment of Childhood Tuberculosis: The Dynamic Duo

    Science.gov (United States)

    Deshpande, Devyani; Srivastava, Shashikant; Nuermberger, Eric; Pasipanodya, Jotam G.; Swaminathan, Soumya; Gumbo, Tawanda

    2016-01-01

    Background. No treatment regimens have been specifically designed for children, in whom tuberculosis is predominantly intracellular. Given their activity as monotherapy and their ability to penetrate many diseased anatomic sites that characterize disseminated tuberculosis, linezolid and moxifloxacin could be combined to form a regimen for this need. Methods. We examined microbial kill of intracellular Mycobacterium tuberculosis (Mtb) by the combination of linezolid and moxifloxacin multiple exposures in a 7-by-7 mathematical matrix. We then used the hollow fiber system (HFS) model of intracellular tuberculosis to identify optimal dose schedules and exposures of moxifloxacin and linezolid in combination. We mimicked pediatric half-lives and concentrations achieved by each drug. We sampled the peripheral compartment on days 0, 7, 14, 21, and 28 for Mtb quantification, and compared the slope of microbial kill of Mtb by these regimens to the standard regimen of isoniazid, rifampin, and pyrazinamide, based on exponential decline regression. Results. The full exposure-response surface identified linezolid-moxifloxacin zones of synergy, antagonism, and additivity. A regimen based on each of these zones was then used in the HFS model, with observed half-lives of 4.08 ± 0.66 for linezolid and 3.80 ± 1.34 hours for moxifloxacin. The kill rate constant was 0.060 ± 0.012 per day with the moxifloxacin-linezolid regimen in the additivity zone vs 0.083 ± 0.011 per day with standard therapy, translating to a bacterial burden half-life of 11.52 days vs 8.53 days, respectively. Conclusions. We identified doses and dose schedules of a linezolid and moxifloxacin backbone regimen that could be highly efficacious in disseminated tuberculosis