共查询到20条相似文献,搜索用时 687 毫秒
1.
利用循环伏安法将金纳米粒子和钼氧化物共同电沉积在玻碳电极表面,制备了金纳米粒子和钼氧化物复合膜修饰电极,利用SEM和XPS研究了MoOx/AuNPs复合膜的表面形态,并研究其修饰电极对葡萄糖的电催化氧化过程. 首次提出了阳极扫描极化反向催化伏安法,即在反向扫描过程中纯的催化氧化电流通过扣减背景电流的方法被提取出来. 显著提高电流测量灵敏度改善了信噪比. 制备的MoOx/AuNPs复合膜修饰电极在0.01~4.0 mmol/L对葡萄糖具有线性响应,电流灵敏度为2.35 mA·L/(mmol·cm2),检测限为9.01 μmol/L(信噪比为3). 相似文献
2.
It is shown that the list of unusual mesons that are planned to be studied in photoproduction reactions can be supplemented
with I
G (J
PC)=2+ (2++) exotic states X
±(1600), which are natural to seek as manifestations of the ρ±ρ0 decay channels in the reactions γN → ρ±ρ0
N and γN → ρ±ρ0Δ. A classification of the ρ±ρ0 states according to their quantum numbers is presented. A model for the spin structure of the amplitudes for the reactions
γp → f
2(1270)p, γp → a
2
0
(1320)p, and γN → X
±(N, Δ) is proposed, and estimates are obtained for the corresponding cross sections. At E
γ≈6 GeV, it is found that σ(γP → f
2(1270)p)≈0.12 μb, σ(γp → a
2
0
(1320)p)≈0.25 μb, σ(γN → X
±
N → ρ±ρ0
N) ≈ 0.018 μb, and σ(γp → X
−Δ++ → ρ−ρ0Δ++≈0.031 μb. The problem of isolating signals from X
± states against the natural background that is associated with other channels of π±π0π+π− production is discussed. It is deduced that searches for exotic states X
±(2+ (2++)) in experiments at JLAB will be quite efficient—for example, the yield of about 2.8×106 events per month is expected to correspond to the estimated cross sections for the reactions γN → X
±
N → ρ±ρ0
N.
__________
Translated from Yadernaya Fizika, Vol. 63, No. 10, 2000, pp. 1904–1912.
Original Russian Text Copyright ? 2000 by Achasov, Shestakov. 相似文献
3.
Yu. M. Andreev S. I. Bityukov N. V. Krasnikov A. N. Toropin 《Physics of Atomic Nuclei》2007,70(10):1717-1724
The LHC (CMS) discovery potential in the search for supersymmetry and lepton-flavor violation in neutralino decays using the
e
± μ∓ + E
T
miss
signature is studied. A detailed study is done for the CMS test points LM1-LM9. It is shown that, for the point LM1, it is
possible to detect lepton-flavor violation in neutralino decays with lepton-flavor-violating branching Br(
→ μ±
e
∓
) ≥ 0.04 Br(
→ e
+
e
−
, μ+ μ−
) for an integral luminosity of 10 fb−1. The discovery potential in the mSUGRA-SUSY scenario with tan β = 10, sgn(μ) = + in the (m
0, m
1/2) plane using the e
± μ∓ + E
T
miss
signature is determined.
The text was submitted by the authors in English. 相似文献
4.
Gui-Jun Ding Rong-Gang Ping Mu-Lin Yan 《The European Physical Journal A - Hadrons and Nuclei》2006,28(3):351-360
X(1835) has been treated as a baryonium with sizable gluon content, and to be almost flavor singlet. This picture allows us
to rationally understand X(1835) production in J/ψ radiative decays, and its large couplings with pˉ, η′ππ. The processes ϒ(1S) → γX(1835) and J/ψ → ωX(1835) have been examined. It has been found that Br(ϒ(1S) → γX(1835))Br(X(1835) → pˉ) < 6.45×10-7, which is compatible with CLEO's recent experimental result (Phys. Rev. D 73, 032001 (2006) hep-ex/0510015). The branching fractions Br(J/ψ → ωX(1835)), Br(J/ψ → ρX(1835)) with X(1835) → pˉ and X(1835) → η′π+π- have been estimated by the quark-pair creation model. We show that they are heavily suppressed, so the signal of X(1835) is very difficult, if not impossible, to be observed in these processes. The experimental checks for these estimations
are expected. The existence of the baryonium nonet is conjectured, and a model-independent derivation of their production
branching fractions is presented. 相似文献
5.
S. N. Mustafaeva 《Physics of the Solid State》2004,46(6):1008-1010
Frequency dependence of the dissipation factor tanδ, the permittivity ɛ, and the ac conductivity σac across the layers in the frequency range f=5×104−3×107 Hz was studied in layered TlGaS2 single crystals. A significant dispersion in tanδ was observed in the frequency range 106−3×107 Hz. In the range of frequencies studied, the permittivity of TlGaS2 samples varied from 26 to 30. In the frequency range 5×104−106 Hz, the ac conductivity obeyed the f
0.8 law, whereas for f>106 Hz σac was proportional to f
2. It was established that the mechanism of the ac charge transport across the layers in TlGaS2 single crystals in the frequency range 5×104−106 Hz is hopping over localized states near the Fermi level. Estimations yielded the following values of the parameters: the
density of states at the Fermi level N
F=2.1×1018 eV−1 cm−3, the average time of charge carrier hopping between localized states τ=2 μs, and the average hopping distance R=103 ?.
__________
Translated from Fizika Tverdogo Tela, Vol. 46, No. 6, 2004, pp. 979–981.
Original Russian Text Copyright ? 2004 by Mustafaeva. 相似文献
6.
L. Roca C. Hanhart E. Oset U. -G. Meißner 《The European Physical Journal A - Hadrons and Nuclei》2006,27(3):373-380
The Λ(1520)-resonance has been recently studied in a unitarized coupled-channel formalism with πΣ(1385), KΞ(1530), ˉN and πΣ as constituents blocks. We provide a theoretical study of the predictions of this model in physical observables of
the pp → pK+K-p and pp → pK+π0π0Λ reactions. In particular, we show that the ratio between the π0π0Λ and K-p mass distributions can provide valuable information on the ratio of the couplings of the Λ(1520)-resonance to πΣ(1385) and
ˉN than the theory predicts. Calculations are done for energies which are accessible in an experimental facility like COSY at
Jülich or the developing CSR facility at Lanzhou. 相似文献
7.
A. P. Martynenko 《Physics of Atomic Nuclei》2008,71(1):125-135
Corrections of order α
5 and α
6 are calculated for muonic hydrogen in the fine-structure interval ΔE
fs = E(2P
3/2) − E(2P
1/2) and in the hyperfine structure of the 2P
1/2-and 2P
3/2-wave energy levels. The resulting values of ΔE
fs = 8352.08 μeV, ΔẼ
hfs(2P
1/2) = 7819.80 μeV, and ΔẼ
hfs(2P
3/2) = 3248.03 μeV provide reliable guidelines in performing a comparison with relevant experimental data and in more precisely
extracting the experimental value of the (2P–2S) Lamb shift in the muonic-hydrogen atom.
Original Russian Text ? A.P. Martynenko, 2008, published in Yadernaya Fizika, 2008, Vol. 71, No. 1, pp. 126–136. 相似文献
8.
A. A. Samokhvalov T. I. Arbuzova N. A. Viglin V. V. Osipov N. I. Solin S. V. Naumov V. G. Bamburov N. I. Lobachevskaya O. G. Reznitskikh 《Physics of the Solid State》1999,41(2):262-264
Mg1−x
CuxO solid solutions having an NaCl structure with 0⩽x⩽0.20 are synthesized and Cu-Mg1−x
CuxO structures are prepared for superconductivity studies. The magnetic susceptibility χ, electron paramagnetic resonance (EPR), and electrical conductivity of the solid solutions are studied at temperatures of
5–550 K. It is shown that χ
−1(T) obeys the Curie-Weiss law with a paramagnetic Curie temperature Θ close to zero and an effective magnetic moment μ
eff=1.9 μ
B, close to the 1.73 μ
B of a Cu2+ ion with spin S=1/2. The width ΔH of the EPR line depends weakly on temperature and increases as x is raised. The volume narrowing of the EPR linewidth ΔH is used to estimate the exchange interaction parameter, 3×10−4 eV. The g-factor is close to 2 and is temperature independent. The electrical conductivity of Mg1−x
CuxO at T=300 K is ≈10−11–10−12 Ω−1 cm−1 for x=0 and increases to 10−5–10−6 Ω−1 cm−1 for x=0.15–0.20. The conductivity is p-type. Magnetic shielding is observed in Cu-Mg1−x
CuxO structures with x=0.15 and 0.20. The possible connection of this phenomenon with interference superconductivity in the contact layer of the
structure is discussed.
Fiz. Tverd. Tela (St. Petersburg) 41, 293–296 (February 1999) 相似文献
9.
M. N. Vinoslavskiĭ P. A. Belevskii A. V. Kravchenko 《Journal of Experimental and Theoretical Physics》2006,102(3):417-430
The self-organization of an electron-hole plasma (EHP) heated by an electric field in pure p-Ge samples at T = 77 K has been studied experimentally. The derived current-voltage characteristics (CVCs) and the distributions of the electric
field and IR emission of the hot carriers along the samples show that the segments of a steep rise or the S-shaped segments of the CVCs in samples with n-p junctions are related to the formation of longitudinal thermal-diffusion autosolitons (AS‖); as a result, thin (d = 2–20 μm in diameter), melted-through current channels appear. Such AS‖ are formed at high EHP densities (n ≥ 1 × 1016 cm−3), when the electron-hole scattering is dominant, and at electron temperatures T
e
= (2–4.5)T
0 (T
0 is the lattice temperature). The saturation segments and the N-shaped segments in the CVCs are attributable to the generation of transverse thermal-diffusion high-field autosolitons (AS⊥) in the form of narrow strata with electric field strengths
= 1–20 kV cm−1. High-field AS⊥ are formed at EHP densities n = 5 × 1013−1 × 1016 cm−3, when the electron-phonon scattering is dominant, and at electron temperatures T
e
∼ Θ ≥ 5T
0 (Θ is the Debye temperature). The generated longitudinal and transverse autosolitons have high temperatures (T
e
≥ 1000 K) and reduced carrier densities and can exist simultaneously in different parts of the sample.
Original Russian Text ? M.N. Vinoslavskiĭ, P.A. Belevskii, A.V. Kravchenko, 2006, published in Zhurnal éksperimental’noĭ i
Teoreticheskoĭ Fiziki, 2006, Vol. 129, No. 3, pp. 477–492. 相似文献
10.
P. V. Fedorets M. Büscher V. P. Chernyshev S. N. Dymov V. Yu. Grishina C. Hanhart M. Hartmann V. Hejny V. Kleber H. R. Koch L. A. Kondratyuk V. P. Koptev A. E. Kudryavtsev P. Kulessa S. I. Merzliakov S. M. Mikirtychiants M. E. Nekipelov H. Ohm R. Schleichert H. Ströher V. E. Tarasov K. -H. Watzlawik I. Zychor 《Physics of Atomic Nuclei》2006,69(2):306-313
The reaction pp → dπ
+
η has been measured at a beam energy of T
p
= 2.65 GeV (p
p
= 3.46 GeV/c) using the ANKE spectrometer at COSY-Julich. The missing-mass distribution of the detected dπ
+ pairs exhibits a peak around the η mass on top of a strong background of multipion pp → dπ
+(nπ) events. The differential cross section d
4
σ/dΩd
dΩ
π
+
dp
d
dp
π
+ for the reaction pp → dπ
+
η has been determined model independently for two regions of phase space. Employing a dynamical model for the a
0
+
production allows one then to deduce a total cross section of σ(pp → da
0
+
→ dπ
+
η) = 1.1 ± 0.3stat ± 0.7syst μb for the production of π
+
η via the scalar a
0
+
(980) resonance and σ(pp → dπ
+
η) = 3.5 ± 0.3stat ± 1.0syst μb for the nonresonant production. Using the same model as for the interpretation of recent results from ANKE for the reaction
, the ratio of the total cross sections is
, which is in agreement with branching ratios in the literature.
The text was submitted by the authors in English. 相似文献
11.
12.
M.A.A. Moussa M. Muralidhar M. Izumi M. Murakami 《Physica C: Superconductivity and its Applications》2009,469(15-20):1211-1214
Effects of a combined substitute of Yb and Nd on Y site on the superconducting properties of YBa2Cu3Oy have been studied. We synthesized Y1−x(Yb0.9Nd0.1)xBa2Cu3Oz compound with x = 0.2, 0.4, 0.6, 0.8 and 1.0. Here, the ratio of Yb–Nd was fixed to be 9:1 for obtaining 123 phase without secondary phases. The melt processing thermal profiles for Y1−x(Yb0.9Nd0.1)xBa2Cu3Oz with x = 0.2 and 0.4 and the addition of 40 mol% {Y1−x(Yb0.9Nd0.1)x}2BaCuO5 and 0.5 wt% Pt in air were determined on the basis of the thermal analysis results. All samples showed a low grain growth rate, particularly for high x values, which may be partially ascribed to un-optimized thermal schedules. Although almost all the samples exhibited low Jc values, the sample with x = 0.2 exhibited Tc of 88.8 K and a relatively high Jc value of 16,000 A/cm2 at 77 K for H//c-axis. 相似文献
13.
In continuous magnetic fields H up to 28 T, we have studied the out-of-plane transport properties and tunneling characteristics of high-quality nondoped single crystals of the Bi-cuprate family: Bi2Sr2CuO6+δ (Bi2201), Bi2Sr2CaCu2O8+δ (Bi2212) and Bi2Sr2Ca2Cu3O10+δ (Bi2223) grown by an identical method. For all compounds the out-of-plane magnetotransport ρc(H) is negative in the temperature region where ρc(T) shows in the normal state a semiconducting-like temperature dependence. The negative magnetoresistance of ρc corresponds to the suppression of the semiconducting temperature dependence of ρc(T) which is found to be isotropic. For the Bi2201 compound, where the normal state can be reached in the available magnetic fields (28 T), a nearly complete suppression of the low-temperature upturn in ρc(T) is observed in the highest magnetic fields with a tendency towards a metallic behavior down to the lowest temperatures (0.4 K). Using the break-junction technique, especially for the Bi2212 and Bi2232 compounds, a clear superconducting gap structure can be observed. Both for temperatures above the critical temperature and for magnetic fields above the upper critical field, a pseudogap structure remains present in the tunneling spectra. The applied magnetic fields yield a stronger suppression of the superconducting state compared to that of the normal-state gap structures as manifested in ρc(T) transport and tunneling. 相似文献
14.
采用机械合金化制备了n型(Bi1-xAgx)2(Te1-ySey)3合金粉体,对其进行XRD分析表明Bi,Te,Ag,Se单质粉末,经2h球磨后实现了合金化;SEM分析表明随着机械合金化时间延长粉体颗粒变得均匀、细小,颗粒尺寸在微米至亚微米数量级.采用放电等离子烧结制备了块体样品,研究了合金成分和球磨时间对热电性能的影响.结果表明材料的热电性能与掺杂元素有密切关系,Ag有利于提高功率因子和降低晶格热导率,球磨10h的(Bi0.99Ag0.01)2(Te0.96Se0.04)3合金粉末的烧结块体具有最大的功率因子和最低的晶格热导率,并在323K取得最高ZT值0.52.
关键词:
1-xAgx)2(Te1-ySey)3合金')" href="#">(Bi1-xAgx)2(Te1-ySey)3合金
机械合金化
放电等离子烧结
热电性能 相似文献
15.
利用密度泛函理论和非平衡格林函数方法, 本文对小尺寸团簇Tan(B3N3H6)n+1 (n ≤ 4)的磁性和量子输运性质进行了系统的研究. 计算结果表明, 此类体系采用三明治结构作为其基态并且具有较高的稳定性. 体系的磁矩随团簇尺寸的增大而线性增大. 当把Tan(B3N3H6)n+1团簇耦合到Au电极上时, 形成的Au-Tan(B3N3H6)n+1-Au体系在有限偏压下展示出了较强的自旋过滤能力, 因而可以被看做是一类新型的低维自旋过滤器. 相似文献
16.
用溶胶-凝胶法制备1.0%mol Mn,Cr,Co掺杂 BaTiO3(BTO)粉体,在1350℃下烧结成多晶陶瓷样品.X射线衍射和差示扫描量热分析表明,室温下掺杂BaTiO3具有四方钙钛矿结构;居里点和相变潜热随Cr,Mn,Co掺杂逐渐降低.将掺杂BaTiO3与Tb1-xDyxFe2-y(TDF)胶合制成双层磁电复合材料,并研究了Cr:BTO-TDF,Mn∶BTO-TDF,Co:BTO-TDF层状复合材料中的磁电效应.实验表明,在340×80 A·m-1偏置磁场下, Cr:BTO-TDF的横向磁电电压系数达到最大值586 mV·cm-1·(80 A·m-1)-1.在400×80 A·m-1偏置磁场下,Mn∶BTO-TDF和Co:BTO-TDF的横向磁电电压系数的最大值分别为480 mV·cm-1·(80 A·m-1)-1和445mV·cm-1·(80 A·m-1)-1.研究表明掺杂BaTiO3-TDF层状复合材料中具有较强的磁电耦合.作为无铅压电材料,掺杂BaTiO3制备的磁电效应器件颇具应用前景.
关键词:
磁电效应
双层复合材料
3')" href="#">掺杂BaTiO3
1-xDyxFe2-y')" href="#">Tb1-xDyxFe2-y 相似文献
17.
Y. -Q. Song L. Venkataramanan M. D. Hürlimann M. Flaum P. Frulla C. Straley 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2002,154(2):261
Spin relaxation is a sensitive probe of molecular structure and dynamics. Correlation of relaxation time constants, such as T1 and T2, conceptually similar to the conventional multidimensional spectroscopy, have been difficult to determine primarily due to the absense of an efficient multidimensional Laplace inversion program. We demonstrate the use of a novel computer algorithm for fast two-dimensional inverse Laplace transformation to obtain T1–T2 correlation functions. The algorithm efficiently performs a least-squares fit on two-dimensional data with a nonnegativity constraint. We use a regularization method to find a balance between the residual fitting errors and the known noise amplitude, thus producing a result that is found to be stable in the presence of noise. This algorithm can be extended to include functional forms other than exponential kernels. We demonstrate the performance of the algorithm at different signal-to-noise ratios and with different T1–T2 spectral characteristics using several brine-saturated rock samples. 相似文献
18.
19.
T. Matsuoka T. Fujimoto K. Tanaka S. Miyasaka S. Tajima K. Fujii M. Suzuki M. Tonouchi 《Physica C: Superconductivity and its Applications》2009,469(15-20):982-984
We have developed a terahertz time-domain spectroscopy (THz-TDS) system for reflectivity measurement with a temperature-controllable cryostat. For emission and detection of THz radiation, a Ti:Sapphire pulsed laser and photoconductive antennas are used. Two wire-grid polarizers enable us to carry out the polarized reflectivity measurements. Using our THz-TDS system, we measured the c-axis polarized reflectivity spectra for La2−xSrxCuO4 single crystals (x = 0.10 and 0.13) and observed sharp Josephson plasma edges for both samples below Tc. The reflectivity spectra of the x = 0.10 sample were in good agreement with those reported previously, which confirms the validity of the system. For the x = 0.13 sample, we discuss the anomolous features of the optical spectra. 相似文献