体内(in Vivo)NMR研究

本文综述了体内(in Vivo)核磁共振波谱技术的目前概况,简要介绍了这一技术的基本原理。对空间定位技术进行了重点评述,并给出了分类表。同时讨论了化学位移对空间定位精确的影响,介绍了提高定位精确度的实验方法。列举了空间定位波谱技术在生命科学研究中的应用,给出了大量的参考文献。     

Λ(Λ)production in p(p) collisions

We describe the production of (AA) in p(p) collisions using a constituent quark model which has been successfully applied to the N(N)system.     

Multi-quasiparticle excitations in ~(145)Tb

Nuclei with N and Z near magic number can be well described by the nuclear shell model. The 145Tb nucleus has a valence proton and a pair of neutron holes with respect to the doubly closed 146Gd nucleus. Therefore, it is expected that the excitations in 145Tb be dominated by single-particle configurations. A detailed measurement of the excitation scheme in 145Tb would give us an opportunity to examine the behavior of multi-particle excitations involving high angular momentum orbits and provi…     

Symmetry Breaking in Finite Volume (Ⅱ)

Using a Hamiltonian approach and the adiabatic approximation, the low-lying spectrum of the lattice O (N) model in the broken phase is analyzed to the next to leading order. It is seen that these corrections appear as a systematic expansion in the inverse power of the lattice size L in the large volume limit.     

T-odd correlations in (n, αγ) reactions

The T-odd correlation (k _α · [σ × k _γ])(k _α · k _γ), where σ is the vector of the neutron polarization and the symbols k denote the respective linear momenta (all vectors are unit ones), in the sequential alpha-gamma cascade induced by a thermal-neutron capture is studied. The study is performed in the one-resonance approximation. Both the final-state interaction of the alpha particle with the residual nucleus and the actual T-noninvariant phase shift are considered as possible origins of the correlation. The problem of suitable target isotopes is analyzed. Related correlations in other neutron- and proton-induced reactions are discussed.     

Polarization observables in (γ,NN) reactions

The formalism of ( γ, NN) reactions is given where the incident photon is polarized and the outgoing-nucleon polarization is detected. Sixteen structure functions and fifteen polarization observables are found in the general case, while only eight structure functions and seven polarization observables survive in coplanar kinematics. Numerical examples are presented for the ¹⁶O(γ, np) and ¹⁶O(γ, pp) reactions. The transitions to the ground state of ¹⁴C and ¹⁴N are calculated in a model where realistic short-range and tensor correlations are taken into account for the np pair, while short-range and long-range correlations are included in a consistent way for pp pairs. The effects of the one-body and two-body components of the nuclear current and the role of correlations in cross-sections and polarizations are studied and discussed. Received: 7 June 2001 / Accepted: 26 September 2001     

Isolating the Λ(1405) in lattice QCD

The odd-parity ground state of the Λ baryon lies surprisingly low in mass. At 1405 MeV, it lies lower than the odd-parity ground-state nucleon, even though it has a valence strange quark. Using the PACS-CS (2+1)-flavor full-QCD ensembles, we employ a variational analysis using source and sink smearing to isolate this elusive state. For the first time we reproduce the correct level ordering with respect to nearby scattering thresholds. With a partially quenched strange quark to produce the appropriate kaon mass, we find a low-lying, odd-parity mass trend consistent with the experimental value.     

Possible effects of oxygen in Te-rich Σ3 (112) grain boundaries in CdTe

Using density functional theory calculation, we show that oxygen (O) exhibits an interesting effect in CdTe. The Te atoms with dangling bonds in a Te-rich rich Σ3 (112) grain boundary (GB) create deep gap states due to strong interaction between Te atoms. However, when such a Te atom is substituted by an O atom, the deep gap states can be shifted toward the valence band, making the site no longer a harmful non-radiative recombination center. We find that O atoms prefer energetically substituting these Te atoms and induce significant lattice relaxation due to their smaller atomic size and stronger electronegativity, which effectively reduces the anion–anion interaction. Consequently, the deep gap states are shifted to lower energy regions close to or even below the top of the valence band.     

Analytic subject index of acoustical papers in China (Appeared in other periodical than Acta Acustica all in Chinese)

Some trends in foreign NDT,Ma Minggang,Non Destructive Testing,11(1989 ),No.2,41.Ultrasonic thickness gauge and its tendency,Zhang Qingxi,Non destructive Testing,11 (1989 ),No.7,187.Analysis of acoustical Properties of listening rooms,Zhu Feng.Audio Engineering,1989,No.1,6Exploration on popularization and application of AM stereo technique in the field of medium-wave broadcasting inChina,Zhang dumin,Audio Engineering,1989,No.3,33.On the development of mode experiment and its analysis(3),Zhang Lingmi,Journal of Vibration and shock,8 (1989),No.1,52.A review of ship vibration research in China(1 ),Guo rixiu,Suo Zhiqiang,Journal of Vibration and shock,8 (1989 ),No.161.     

Analytic subject index of acoustical papers in China(Appeared in other periodical than Acta Acustica all in Chinese)

O.General;1.Physical acoustics;2.Underwater sound;3.Mechanical vibration and shock;4.Noise andnoise control;5.Ultrasonics;6.Speech acoustics and speech communication;7.Physiological acoustics;8.Ar-chitectural acoustics;9.Electroacoustics;10.Acoustical measurement and instrumentation;11.Atmosphericacoustics;12.Geoacoustics;13.Bioaoustics;14.Musical acoustical;15.Signal processing.     

Analytic subject index of acoustical papers in China(Appleared in other periodical than acta acustica all in Chinese)

0.GeneralProgress in last 10 years about acoustics testing technique in-duct,Zhao Songling,Journal of Technical Acoustics,11(1992),No.1-2,13.Sound emission in liquid excited by laser and its application to ocean,Feng Shaosong,Jouranl of Tech- nical Acoustics,11(1992),No.1-2,17.The developing tendency of ultrasonic dianosis,Xu Zhishang,Journal of Technical Acoustics,11(1992), No.1-2,22.Ultrasound microscope and it's applications,W.S.Gan et al.,Journal of Technical Acoustics,11(1992), No.1-2,26.     

Analytic subject index of acoustical papers in China(Appleared in other periodical than acta acustica all in Chinese)

0.General;1.Physical acoustics;2.Underwater sound;3.Mechanical vibration and shock; 4.Noise and noise control;5.Ultrasonics;6.Speech acoustics and speech communication;7.Physio- logical acoustics;8.Architectural acoustics;9 Electroacoustics;10.Acoustical measurement and instrumentation;11oAtmospheric acoustica;12.Geoacoustics;13.Bioacoustics;14.Musical acoustics;15.Signal processing. 0.GeneralLaser ultrasonics and nondestructive evaluation of materials,Zhang Shuyi,Applied Acoustics, 11(1992),No.4,1.Recent domestic advance in ultrasonic therapy,Zhou Wansong,Applied Acoustics,11(1992),No.5,1.Ultrasonic non—destructive testing of structural ceramics,Shen Jianzhong,Jiang Futang Applied Acous- lics,11(1992),No.6,1.     

Quantum Currents in the coset Space SU(2)/U(1)

We propose a rational quantum deformed nonlocal currentsin the homogeneous space SU(2)k/U(1),and in terms of it and a free boson field a representation for the Drinfeld currents of Yangian double at a general level k=c is obtained.In the classical limit h→0,the quantum nonlocal currents become SU(2)k parafermion,and the realization of Yangian double becomes the parafermion realization of SU(2)k current algebra.     

Analytic subject index of acoustical papers in China──(Appeared in other periodical than Acta Acustica all in Chinese)

0.General;I.Physicalacoustics;2.Underwatersound;3.Mechanicalvibrationandshock;4.Noiseandnoisecontrol;5.Ultrasonics;6.Speechacousticsandspeechcommunication;7.Physiologicalacoustics;8.Architecturalacoustics;9.Electroacoustics;10.Acousticalmeasurementandinstrumentation;11.Atmosphericacoustics;12.Gcoacoustics;13.Bioacoustics;14.Musicalacoustics;15.Signalprocessing.0.GeneralSomehottechniquesat'93autumncomdcxcomputcrexhibition,HuoZiqiang,AppIicdAcoustics,l3(l994),No.3,37.Noise-measuringinst…     

Muon Knight shift in platinum and in β-PdHx (x=0.70, 0.75)

The ⁺ Knight shift in platinum has been measured between 20 K and 785 K. It shows a strong temperature dependence and scales with the magnetic bulk susceptibility. A temperature independent contribution of +40 to +60 ppm and a d-electron induced hyperfine field per unpaired d-electron per atom ofB _hf,d =–5.03 kG (±8.5%) are obtained. The ⁺ Knight shift in PdH_0.70 and PdH_0.75 shows no dependence on temperature between 20 K andRT and increases fromK ppm forx=0.70 toK ppm forx=0.75, in good agreement with proton Knight shift measurements.     

Inclusive production of baryons in decays of the γ (9.46) and in quark jets

Inclusive Production of mesons and baryons in quark jets at \(\sqrt s = 9.5 \ldots 36GeV\) and in decays of the γ(9.46) meson has been studied using the Quark Recombination Model (QRM). The model predictions for quark jets agree with data. The QRM-simulation of three-gluon decays of the γ(9.46) shows an enhancement of the inclusive baryon rate, as was observed recently by the DASP II experiment.     

Negative persistent photoconductivity in GaAs (δ-Sn) structures

The effect of illumination with various wavelengths λ (770 nm<λ<1120 nm) on the conductivity of GaAs structures with tin δ-doping of the vicinal faces was investigated in the temperature range 4.2–300 K. Negative persistent photoconductivity was found in strongly doped samples. It was shown on the basis of the results of investigations of the Hall and Shubnikov-de Haas effects that the negative photoconductivity is due to a large decrease in the electron mobility with increasing electron density. The decrease of electron mobility is explained by ionization of DX centers, which destroys the spatial correlation in the distribution of positively charged donors and negatively charged DX centers. Zh. éksp. Teor. Fiz. 116, 2130–2139 (December 1999)     

Charmed-Hadron Production in Υ(1S) Semi-inclusive Decay

In the framework of the NRQCD factorization formalism,we calculate the decay rate for the process Υ(1 S) → ccgg to the next-to-leading order(NLO) in the relative velocity v of the b quark in the bottomonium rest frame.We also study the momentum distributions of the charm quark and the charmed-hadron in the decay.The momentum distribution of the charmed-hadron is obtained by convolving the charm quark momentum distribution with a fragmentation function of the charm quark into the hadron.In addition,we fit the nonperturbative NRQCD matrix element v 2 Υ through comparing the theoretical prediction with the measurement from the BaBar collaboration for the decay rate of Υ(1 S) → D + X.In return,taking this matrix element as an input parameter,we predict the decay rates as well as the momentum distributions for a collection of charmed-hadrons in the process Υ(1S) → ccgg → hX.     

Pseudoscalar-Meson Mixing in ψ(2S)→VP Decays

Based on the branching ratios of ψ(2S)→VP given by the BES collaboration, we make a new analysis to study the mixing of pseudoscalars. The mixing angle of η and η_p, θ_p is determined to be (－7.54±1.52)° which is consistent with the value obtained from quadratic Gell-Mann-Okubo formula. From this work we also know that the strength of DOZI to SOZI is about 14% in ψ(2S)→VP, and the phase angle of electromagnetic amplitude to strong amplitude is (156±89)°.