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1.
The following hydrogen and oxygen concentration cells using the oxide protonic conductors, \textCaZ\textr0.98\textI\textn0.02\textO3 - d {\text{CaZ}}{{\text{r}}_{0.98}}{\text{I}}{{\text{n}}_{0.02}}{{\text{O}}_{3 - \delta }} and \textCaZ\textr0.9\textI\textn0.1\textO3 - d {\text{CaZ}}{{\text{r}}_{0.{9}}}{\text{I}}{{\text{n}}_{0.{1}}}{{\text{O}}_{{3} - \delta }} , as the solid electrolyte were constructed, and their polarization behavior was studied,
( \textreversible: - )\text Pt,\textH2 + \textH2\textO/\textCaZ\textr1 - y\textI\textny\textO3 - d( y = 0.02\text or 0.1 )/\textAr( + \textH2 + \textO2 ),\text Pt( + :\textirreversible ) \left( {{\text{reversible}}: - } \right){\text{ Pt}},{{\text{H}}_2}{ + }{{\text{H}}_2}{\text{O}}/{\text{CaZ}}{{\text{r}}_{1 - y}}{\text{I}}{{\text{n}}_y}{{\text{O}}_{3 - \delta }}\left( {y = 0.02{\text{ or }}0.1} \right)/{\text{Ar}}\left( { + {{\text{H}}_2} + {{\text{O}}_2}} \right),{\text{ Pt}}\left( { + :{\text{irreversible}}} \right)  相似文献   

2.
Formation of gold(III) complexes with the synthetic antibiotic norfloxacin (NF) was investigated in aqueous solution at pH 4.0, 7.5 and 10.6, with the ligand in cationic, zwitterionic and anionic forms, respectively. UV-Visible spectroscopy, steady state and time-resolved fluorometry were used to characterize the complexes. Binding sites, association constants and fluorescence lifetimes of the complexes were obtained. Au3+ binding to zwitterionic NF produced a fluorescence decrease and a small red shift. Fluorescence changes as a function of Au3+ concentration were fitted using a one-site binding model and the association constant was obtained, Kbzw = 1.7 ×105  \textM1 K_b^{{zw}} = {1}.{7} \times {1}{0^{{5}}}\;{{\text{M}}^{{1}}} . The association of Au3+ with cationic NF was much weaker, the obtained binding constant being Kbcat = 2.4 ×103  \textM1 K_b^{{cat}} = {2}.{4} \times {1}{0^{{3}}}\;{{\text{M}}^{{1}}} . The Au3+ binding site for these species involves the carboxyl group, in agreement with a much stronger association of the cation with the carboxylate anion than with the neutral acid. Association of Au3+ with nonfluorescent anionic NF presented a clear evidence of two binding sites. The highest affinity site is the unprotonated piperazinyl group with Kbpip \geqslant 5 ×107  \textM - 1 K_b^{{pip}} \geqslant {5} \times {1}{0^{{7}}}\;{{\text{M}}^{{ - {1}}}} , and the low affinity site includes the carboxylate anion. The results point out to important pH dependent differences in complex formation between transition metal ions and fluoroquinolones, leading to different binding sites and association constants that change by several orders of magnitude.  相似文献   

3.
The complex impedance of the Ag2ZnP2O7 compound has been investigated in the temperature range 419–557 K and in the frequency range 200 Hz–5 MHz. The Z′ and Z′ versus frequency plots are well fitted to an equivalent circuit model. Dielectric data were analyzed using complex electrical modulus M* for the sample at various temperatures. The modulus plot can be characterized by full width at half-height or in terms of a non-exponential decay function f( \textt ) = exp( - \textt/t )b \phi \left( {\text{t}} \right) = \exp {\left( { - {\text{t}}/\tau } \right)^\beta } . The frequency dependence of the conductivity is interpreted in terms of Jonscher’s law: s( w) = s\textdc + \textAwn \sigma \left( \omega \right) = {\sigma_{\text{dc}}} + {\text{A}}{\omega^n} . The conductivity σ dc follows the Arrhenius relation. The near value of activation energies obtained from the analysis of M″, conductivity data, and equivalent circuit confirms that the transport is through ion hopping mechanism dominated by the motion of the Ag+ ions in the structure of the investigated material.  相似文献   

4.
Moments of the hadronic invariant mass and of the lepton energy spectra in semileptonic B decays have been determined with the data recorded by the DELPHI detector at LEP. From measurements of the inclusive b-hadron semileptonic decays, and imposing constraints from other measurements on b- and c-quark masses, the first three moments of the lepton energy distribution and of the hadronic mass distribution, have been used to determine parameters which enter into the extraction of |Vcb| from the measurement of the inclusive b-hadron semileptonic decay width. The values obtained in the kinetic scheme are: and include corrections at order 1/mb3. Using these results, and present measurements of the inclusive semileptonic decay partial width of b-hadrons at LEP, an accurate determination of |Vcb| is obtained: Received: 26 April 2005, Revised: 16 September 2005, Published online: 16 November 2005  相似文献   

5.
A method for the determination of the noise spectral density in a high-temperature microwave SQUID operating in the hysteresis regime is developed. Under these conditions, the reflection coefficient serves as an output signal. It is shown that if a directional coupler used for extracting the reflected wave is placed as close to the SQUID loop as possible, the magnetometer can be designed as a microwave integrated circuit with a noise flux spectral density SF 1/2 < 10 - 5 F0 /\textHz\text0\text.5 ,\textwhere F\text0 S_\Phi ^{1/2} < 10^{ - 5} \Phi _0 /{\text{Hz}}^{{\text{0}}{\text{.5}}} ,{\text{where }}\Phi _{\text{0}} , is the magnetic flux quantum.  相似文献   

6.
In order to improve the chemical stability of BaCeO3, Ti4+ was introduced into B site of BaCeO3 to modify the chemical stability. XRD test demonstrates that \textBaC\texte0.6\textT\texti0.2\textY0.2\textO3 - d {\text{BaC}}{{\text{e}}_{0.6}}{\text{T}}{{\text{i}}_{0.2}}{{\text{Y}}_{0.2}}{{\text{O}}_{3 - \delta }} (BCTY) keeps its original pervoskite-type structure at a high doping level of 20%. After exposure in 94% N2 + 3% CO2 + 3% H2O at 700 °C for 10 h, BCTY exhibited adequate chemical stability while decomposition was found in \textBaC\texte0.8\textY0.2\textO3 - d {\text{BaC}}{{\text{e}}_{0.8}}{{\text{Y}}_{0.2}}{{\text{O}}_{3 - \delta }} (BCY). Accordingly, the conductivity of BCTY reaches 0.0072 S/cm at 700 °C in humidified hydrogen which is a little lower than BCY (0.0085). Besides, BCTY displayed better sintering characteristics than BCY at high temperatures and the relative density reaches 96.4% and 94.8%, respectively. The two samples also exhibited similar thermal expansion behavior from 30 to 1,000 °C. A fuel cell with BCTY as electrolyte exhibited 244 mW/cm2 at 700 °C and the stable short-term performance further proved the stability of BCTY.  相似文献   

7.
The conductivity of glasses in the 50\textP\text2 \textO\text5 - x\textV\text2 \textO\text5 - ( 50 - x )\textLi\text2 \textO50{\text{P}}_{\text{2}} {\text{O}}_{\text{5}} - x{\text{V}}_{\text{2}} {\text{O}}_{\text{5}} - \left( {50 - x} \right){\text{Li}}_{\text{2}} {\text{O}} system was studied as a function of temperature and composition. For all compositions, the conductivity variation as a function of temperature followed an Arrhenius type relationship. Isothermal variation of conductivity as a function of composition showed a minimum for a molar ratio x near 20. Probable mechanisms for decrease of conductivity with decrease of vanadium oxide concentration were explained. The minimum in room temperature was attributed to increase of V4+/V5+ with decrease of vanadium oxide in specific concentrations of vanadium oxide. Activation energy increased with decrease of V2O5 content. This behavior was attributed to increase of average spacing between vanadium ions.  相似文献   

8.
Investigations of disperse nonmetallic inclusions in unalloyed alpha titanium VT1-0 have been performed by using transmission electron (including scanning and high-resolution) microscopy. Characteristic electron energy losses spectroscopy has shown that these inclusions are titanium carbide particles. It has been revealed that the disperse carbides are formed in the titanium hcp matrix as a phase based on the fcc sublattice of titanium atoms. The inclusion–matrix orientation relationship corresponds to the well-known Kurdyumov–Sachs and Nishiyama–Wassermann relationships [ 2[`11] 0 ]\upalpha ||[ 011 ]\updelta \text and ( 000[`1] )\upalpha ||( 1[`1] 1 )\updelta {\left[ {2\overline {11} 0} \right]_{{\upalpha }}}\parallel {\left[ {011} \right]_{{\updelta }}}{\text{ and }}{\left( {000\overline 1 } \right)_{{\upalpha }}}\parallel {\left( {1\overline 1 1} \right)_{{\updelta }}} .  相似文献   

9.
In a previous report (J. Fluoresc. 16, 153, 2006) we studied the chaotropiclly induced denaturation of Bovine Serum Albumin (BSA) using the fluorescence decay kinetics at different stages in the denaturation of BSA by guanidinium hydrochloride (GuHCl). In this work, we gain a more detailed insight into the BSA denaturation process by investigating the thermodynamics of the process. Structural changes were monitored spectrophotometrically via the intrinsic protein fluorescence from tryptophan residues, and the extrinsic fluorescence from 1,8-anilinonaphthalene sulphonate (ANS). ANS tends to locate in a variety of binding sites in BSA which are located in different domains, and these can be selectively populated using different, 1:1 and 1:10 molar ratios of BSA to ANS. The data from steady-state and time-resolved fluorescence spectroscopy were analyzed using thermodynamic two-state and three-state models and the lifetime data clearly indicated the presence of an intermediate state during denaturation. A global analysis using non-linear regression gave a DGH2O,D0 = 6.7  \textkcal.\textmo\textl - 1 \Delta G_{{H_2}O,D}^0 = 6.7\;{\text{kcal}}.{\text{mo}}{{\text{l}}^{ - 1}} for the complete unfolding of the BSA-ANS complexes, and a DGH2O,I0 = 0.9  \textkcal.\textmo\textl - 1 \Delta G_{{H_2}O,I}^0 = 0.9\;{\text{kcal}}.{\text{mo}}{{\text{l}}^{ - 1}} for the first step to the intermediate. Therefore, the unfolding energy of the intermediate, which appears mostly at intermediate GuHCl concentrations (1.0 to 1.5 M), to the denatured state, is 5.8 kcal.mol−1. The lifetime analysis of the BSA-ANS complexes also shows clearly that there are differences in stability of the BSA domains, with domain III unfolding first at low GuHCl concentrations (<1.5 M).  相似文献   

10.
The temperature dependence of the electrical conductivity of the compound 2,4,4-trimethyl-4,5-dihydro-3H-benzo[b] [1,4] diazepin-1-ium tetrachlorocadmiate in the different phases follows the Arrhenius law. The imaginary part of the permittivity constant is analyzed with the Cole–Cole formalism. In the temperature range 348–394 K, the activation energy of conductivity obtained from complex permittivity in regions I and II are, respectively, 1.03 and 0.33 eV, and E m (in regions I and II are, respectively, 0.97 and 0.36 eV) obtained from the modulus spectra is close, suggesting that the ion transport is probably due to a hopping mechanism. The Kohlrausch–Williams–Watts function, j(t) = exp( - ( \fractt\textKWW )b ) \varphi (t) = \exp \left( { - {{\left( {\frac{t}{{{\tau_{\text{KWW}}}}}} \right)}^\beta }} \right) , and the coupling model are utilized for analyzing electric modulus at various temperatures. The decreasing of β at 373 K is due to approaching the temperatures of change in the conduction mechanism of the sample.  相似文献   

11.
Oscillations of neutral meson (K 0-$ \overline {K^0 } $ \overline {K^0 } , D 0-$ \overline {D^0 } $ \overline {D^0 } , and B 0-$ \overline {B^0 } $ \overline {B^0 } are extremely sensitive to the meson and antimeson energies at rest. This energy is determined as mc 2—with the corresponding inertial mass—and as the energy of gravitational interaction. Assuming that the CPT theorem is correct for inertial masses and estimating the gravitational potential for which the largest contribution originates from the field of the galaxy center, we obtain the estimate from experimental data on K 0-$ \overline {K^0 } $ \overline {K^0 } oscillations:
$ \left| {\left( {\frac{{m_g }} {{m_i }}} \right)_{K^0 } - \left( {\frac{{m_g }} {{m_i }}} \right)_{\overline {K^0 } } } \right| \leqslant 8 \times 10^{ - 13} , at C.L. = 90\% $ \left| {\left( {\frac{{m_g }} {{m_i }}} \right)_{K^0 } - \left( {\frac{{m_g }} {{m_i }}} \right)_{\overline {K^0 } } } \right| \leqslant 8 \times 10^{ - 13} , at C.L. = 90\%   相似文献   

12.
The capture cross section of a trapping or recombination center for a charge carrier has been defined as the quotient of the capture coefficient and the average thermal velocity of the carrier distribution. For a Maxwellian distribution in a semiconductor band with an ellipsoidal effective mass tensor, this average velocity can be expressed as
á v ñ th = [ \frac8KTpmt ]\frac12 dt \left\langle v \right\rangle _{th} = \left[ {\frac{{8KT}}{{\pi m_t }}} \right]^{\frac{1}{2}} \delta _t  相似文献   

13.
Geometric structures and excited electronic states for free bases of bacteriochlorin (H2BC) and tetraazabacteriochlorin (H2TABC) as well as for their magnesium complexes (MgBC and MgTABC), analogs of bacteriopheophytin a (H2BPhea) and bacteriochlorophyll a (MgBPhea), have been calculated by a DFT method and by an INDO/Sm method (the INDO/S method with parameterization modified by the authors), respectively. The factors responsible for the observed bathochromic shift of the long-wavelength Q x (0–0) band of MgBPhea relative to H2BPhea, \updelta EQx @ - 300  \textc\textm - 1 {{\updelta }}{E_{{Q_x}}} \cong - 300\;{\text{c}}{{\text{m}}^{ - 1}} , have been clarified. Contributions of one- and two-electron interactions to the resulting shift of the Q x (0–0) band have been analyzed in detail for the H2BC/MgBC, H2TABC/MgTABC, and porphine (H2P)/Mg porphine (MgP) pairs. It is shown that the bathochromic shift under consideration for the tetrahydro derivatives is caused by a decrease of the orbital energy gap ε1–ε−1 between the lowest unoccupied and highest occupied molecular orbitals. The variation of δ(ε1–ε−1) is large and amounts to –1660 and –920 cm–1 for the H2BC/MgBC and H2TABC/MgTABC pairs, respectively. The two-electron contributions, both into the energy of electronic configurations and due to the superposition of the configurations, produce a compensating hypsochromic effect such that the shifts \updelta EQx {{\updelta }}{E_{{Q_x}}} are –260 and –150 cm–1 for the H2BC/MgBC and H2TABC/MgTABC pairs, respectively. It is also shown that the calculated electronic spectra for the considered molecules agree quantitatively with the experimental absorption spectra.  相似文献   

14.
The precipitation of lanthanum and neodymium phosphate phases from supersaturated aqueous solutions at pH ~1.9 was studied at 5, 25, 50, and 100 °C in batch reactors for up to 168 h. Crystalline La and Nd–rhabdophane phases precipitated immediately upon mixing of the initial aqueous La or Nd and PO4 solutions. Changes in aqueous PO4 and Rare Earth Element (REE) concentrations during the experiments were determined by ICP-MS and UV–Vis spectrophotometry, while the resulting solids were characterized via powder XRD, SEM, TEM, and FTIR. All precipitated crystals exhibited a nano-rod morphology and their initial size depended on temperature and REE identity. At 5 °C and immediately after mixing the La and Nd–rhabdophane crystals averaged ~44 and 40 nm in length, respectively, while at 100 °C lengths were ~105 and 94 nm. After 168 h of reaction, the average length of the La and Nd rhabdophanes increased by 23 and 53% at 5 °C and 11 and 59% at 100 °C, respectively. The initial reactive solutions in all experiments had activity quotients for rhabdophane precipitation: \textREE 3+ + \textPO43 - + n\textH2 \textO = \textREEPO4 ·  n\textH2 \textO {\text{REE}}^{ 3+ } + {\text{PO}}_{4}^{3 - } + n{\text{H}}_{2} {\text{O}} = {\text{REEPO}}_{4} \cdot\;n{\text{H}}_{2} {\text{O}} of ~10−20.5. This activity quotient decreased with time, consistent with rhabdophane precipitation. The rapid equilibration of rhabdophane supersaturated solutions and the progressive rhabdophane crystal growth observed suggests that the REE concentrations of many natural waters may be buffered by rhabdophane precipitation. In addition, this data can be used to guide crystallization reactions in industrial processes where monodisperse and crystalline La or Nd rhabdophane materials are the target.  相似文献   

15.
The magnetic critical behavior of the manganese perovskite series $ {\text{La}}_{{0.67 - y}} {\left( {{\text{Sr,}}\,\,{\text{Ba,}}\,\,{\text{Ca}}} \right)}_{{0.33 + y}} {\text{Mn}}_{{1 - x}} {\text{Sn}}_{x} {\text{O}}_{3} The magnetic critical behavior of the manganese perovskite series (x = 0.01, 0.02, y = 0, 0.07) is studied by means of dc magnetic measurements and 119Sn M?ssbauer spectroscopy. The structure can be described by a rhombohedral unit cell (space group R–3C) for the samples where the A-site is occupied by La and Sr or La and Ba ions and orthorhombic unit cell (space group Pnma) for the samples where the A-site is occupied by La and Ca ions. Arrott and scaling plots show that the samples, where the A-site is occupied by La and Sr or La and Ba ions, follow the behavior of a conventional second-order ferromagnetic transition. In contrast, the samples that contain La and Ca ions in the A-site show anomalous behavior around Curie point. M?ssbauer measurements show two magnetic phases below T c. One of them exhibits stronger exchange interactions with more rapid electron transfer between Mn3+/Mn4+, compared to the other.  相似文献   

16.
Rhodamine derivatives are popular, photostable fluorophores that are used in a number of fluorescent based techniques, including fluorescence correlation spectroscopy (FCS). Indeed, in FCS, both rhodamine 6G (R6G) and rhodamine 110 (R110) are used as calibration standards to determine the dimensions of the instrument confocal volume. In spite of a requirement for precise values of the diffusion coefficients, literature values are scarce and vary over an order of magnitude. In this paper, the diffusion coefficients of four rhodamine fluorophores (rhodamine 6G (R6G), rhodamine B (RB), rhodamine 123 (R123), rhodamine 110 (R110)) were determined by pulsed field gradient nuclear magnetic resonance (PFG-NMR) spectrometry and then validated by comparison with fluorescence correlation spectroscopy. With the objective of validating the FCS calibration, diffusion coefficients of several dextrans and a polystyrene nanoparticle were also determined and compared with literature values or theoretical values that were based upon the Stoke–Einstein equation. The work presented here lead us to conclude that the diffusion coefficients for R6G and R110 have generally been underestimated in the literature. We propose revised values of 4.4 × 10−10 m2 s−1 for R110 and 4.0 × 10−10 m2 s−1 for R6G. Using the revised D value for R110 to calibrate the FCS instrument, diffusion coefficients have then been systematically determined for different conditions of pH, ionic strength and concentration. To correct for differences due to solvent effects (D2O vs. H2O), an isotopic correction factor, of 1.23, was determined from both FCS and from the solvent auto-diffusion coefficients obtained by NMR.  相似文献   

17.
The Weber potential energy U for charges q and q' separated by the distance R is U = (qq'/R)[1 – (dR/dt)2/2c2]. If this potential arises from a finite velocity c of energy transfer Q', where the retarded rate of transfer from q' to q is dQ(t-R/c)/dt = Q'[1 – (dR/dt)/c] and where the advanced rate from q to q' is dQ(t+R/c)/dt = Q'[1 + (dR/dt)/c], then the resultant time-average root-mean-square action is given by . Identifying Q' with the Coulomb potential energy qq'/R, the Weber potential is obtained. Using the same argument, Newtonian gravitation yields a corresponding Weber potential energy, qq'/R being replaced by ( - Gmm'/R).  相似文献   

18.
OL-1-type material (birnessite) is synthesized by an oxidoreduction process. Different physicochemical techniques were used to characterize the obtained material. AC impedance spectroscopy results show processes associated to the electrical conduction in bulk and grain boundary at high frequency, and an ionic conduction at low frequency. Here σ′(ω) shows a universal Jonscher’s law behavior associated to the electron hopping and charge polarization, and the value of 8.39?×?10?6 Ω?1?cm?1 found in the high frequency region at room temperature suggests its semiconductor nature. The combined results of AOS, TGA, and AA suggest the following chemical formula $ {\text{N}}{{\text{a}}^{ + }}_{{0.28}}\left( {{\text{M}}{{\text{g}}^{{2 + }}}_{{0.16}}{\text{M}}{{\text{n}}^{{4 + }}}_{{0.46}}{\text{M}}{{\text{n}}^{{3 + }}}_{{0.54}}} \right){{\text{O}}_{{2.03}}} \cdot 0.6{{\text{H}}_2}{\text{O}} $ . Finally, the XRD pattern is characteristic of OL-1-type materials, the BET area was 56,25 m2 g?1, and the behavior of N2 isotherms suggests the presence of microporous and mesoporous structures. With the purpose of obtaining a better understanding of the ionic conductivity in these types of materials, magnesium exchange material was prepared and electrical properties at room temperature were analyzed. These results indicate that there is interplay among the structural, morphological, and textural properties with the electrical performance of these materials.  相似文献   

19.
We have obtained inequality $ 1 - {{\Delta \bar \tau } \mathord{\left/ {\vphantom {{\Delta \bar \tau } {\bar \tau }}} \right. \kern-\nulldelimiterspace} {\bar \tau }} < \left( {J \cdot V \cdot \bar \tau } \right)^{ - 1} < 1 + {{\Delta \bar \tau } \mathord{\left/ {\vphantom {{\Delta \bar \tau } {\bar \tau }}} \right. \kern-\nulldelimiterspace} {\bar \tau }} $ 1 - {{\Delta \bar \tau } \mathord{\left/ {\vphantom {{\Delta \bar \tau } {\bar \tau }}} \right. \kern-\nulldelimiterspace} {\bar \tau }} < \left( {J \cdot V \cdot \bar \tau } \right)^{ - 1} < 1 + {{\Delta \bar \tau } \mathord{\left/ {\vphantom {{\Delta \bar \tau } {\bar \tau }}} \right. \kern-\nulldelimiterspace} {\bar \tau }} , where J is the frequency of homogeneous nucleation, V and $ \bar \tau $ \bar \tau are, respectively, volume and average lifetime of the superheated liquid, and $ {{\Delta \bar \tau } \mathord{\left/ {\vphantom {{\Delta \bar \tau } {\bar \tau }}} \right. \kern-\nulldelimiterspace} {\bar \tau }} $ {{\Delta \bar \tau } \mathord{\left/ {\vphantom {{\Delta \bar \tau } {\bar \tau }}} \right. \kern-\nulldelimiterspace} {\bar \tau }} is relative statistical error $ \bar \tau $ \bar \tau . Inequality appears to be a consequence of nucleation homogeneity and stability used at its deduction and taken in the theory as initial and determinant assumption. Calculations with the use of experimental data for the boundaries of the attainable superheating show that inequality is not satisfied. Thus, experimental data can not be considered a proof of the theory fundamentals.  相似文献   

20.
The phenomenon of the diffusion of proton and deuteron in a single crystal of magnesium aluminate spinel was studied by infrared absorption. The chemical diffusion coefficient of proton was determined by the relaxation time of the absorption intensity upon the substitution of deuteron with proton. The temperature dependence of the chemical diffusion coefficient of proton for was expressed as . The chemical diffusion coefficient of proton was found to be independent of the composition of spinel and of the atmosphere. Paper presented at the 11th Euro Conference on the Science and Technology of Ionics, Batz-sur-Mer, Sept. 9–15 2007.  相似文献   

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