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1.
The self-diffusion of n-decane in zeolite NaX was studied by NMR PFG method. The situation when the liquid was only in the crystalline channels was studied in details. The restricted molecular motion of liquid in the crystalline channels was observed. The reasons of the anomalous self-diffusion of n-decane in zeolite bed were stated. The technique of the determination of the genuine self-diffusion coefficient in such porous systems was proposed. The genuine self-diffusion coefficients for system NaX/n-decane were obtained.  相似文献   

2.
The 400 MeV/u 12C6+ion beam was successfully cooled by the intensive electron beam near 1 A in CSRe.The momentum cooling time was estimated near 15 s.The cooling force was measured in the cases of different electron beam profiles,and the different angles between the ion beam and electron beam.The lifetime of the ion beam in CSRe was over 80 h.The dispersion in the cooling section was confirmed as positive close to zero.The beam sizes before cooling and after cooling were measured by the moving screen.The beam diameter after cooling was about 1 mm.The bunch length was measured with the help of the signals from the beam position monitor.The diffusion was studied in the absence of the electron beam.  相似文献   

3.
王德真  吴洪涛 《中国物理》2002,11(8):799-803
The radial distributions of ions,electrons and dust particles in the positive colum of glow discharges are investigated in a tripled-pole diffusion model.The dust particles are mainly trapped in the region around the column axis where the electrostatic potential is the highest.The presence of the dust particles results in the ion density increasing and the electron density decreasiung in the dust-trapped region.The dust-trapped region is wider for a higher dust temperature or a smaller particulate redius.The ions and electrons in the dust-free region away from the column axis are in ambipolar diffusion.  相似文献   

4.
The electrical breakdown of microwave plasma in water was investigated between 1 and 30 kPa. The dependency of the ignition power for generating plasma on the size of coaxial electrode was measured. The ignition power decreases with a decrease of the diameter of the inner electrode. The behavior of microwave plasma in water was observed using a high-speed camera. The plasma ignites in a bubble generated by microwave heating. The model for calculating the electric field was created on the basis of the captured images of the bubble just before plasma ignition. The method presented can be used to visualize the electrical field distribution in the bubble. The electric field breakdown was calculated using the measured ignition power. The electric field breakdown of plasma in water is of the same order as gas phase plasma.  相似文献   

5.
The history of pollinosis in Japan before the discovery of Japanese cedar pollinosis was presented in part I in this paper. Until early 1960s, it was believed that there was no pollinosis in Japan except one case of ragweed pollinosis.The summary of how the Japanese cedar pollinosis was discovered and named was presented in part II, by referring to the paper in which we reported the presence of Japanese cedar pollinosis for the first time.The epidemiology after the discovery of Japanese cedar pollinosis was presented in part III. The number of the patients suffering from Japanese cedar pollinosis gradually increased since the 1970s. The annual incidence rate of the pollinosis had correlations with the dispersed pollen count per year. The prevalence rate of the patients with Japanese cedar pollinosis increased from 16.2% in 1998 to 26.5% in 2008 by the nationwide survey. The prevalence rate of the patients with Japanese cedar pollinosis in Tokyo metropolitan area was 10% from 1983 to 1987, 19.4% in 1996, and 28.2% in 2006.The prospects of current research and future studies were discussed in parts IV and V.  相似文献   

6.
The nucleon effective interaction in the nuclear medium is investigated in the framework of the DiracBrueckner-Hartree-Fock (DBHF) approach. A new decomposition of the Dirac structure of nucleon self-energy in the DBHF is adopted for asymmetric nuclear matter. The properties of finite nuclei are investigated with the nucleon effective interaction. The agreement with the experimental data is satisfactory. The relativistic microscopic optical potential in asymmetric nuclear matter is investigated in the DBHF approach. The proton scattering from nuclei is calculated and compared with the experimental data. A proper treatment of the resonant continuum for exotic nuclei is studied. The width effect of the resonant continuum on the pairing correlation is discussed. The quasiparticle relativistic random phase approximation based on the relativistic mean-field ground state in the response function formalism is also addressed.  相似文献   

7.
Pawan Singh  S Prakash 《Pramana》1993,41(3):239-255
The electronic structure of hydrogen and muonium in simple metals is investigated. The spherical solid model potential is used for the discrete lattice and the Blatt correction for lattice dilation. The proton and muon are kept at the octahedral sites in the fcc and hcp lattices and self-consistent non-linear screening calculations are carried out. The scattering phase shifts, electronic charge density, effective impurity potential, self-energy, charge transfer, residual resistivity and Knight shift are calculated. The spherical solid potential changes the scattering character of impurity. The phase shifts are found slowly converging. The scattering is more prominent in Al than in Mg and Cu. The virtual bound states of proton and muon are favoured in all the three metals. The calculated value of residual resistivity for CuH is in good agreement with the experimental value. The results for Knight shift forμ + in Cu and Mg are in reasonable agreement with the experimental values while those forμ + in Al are lower than the experimental value. The analytical expressions for effective impurity potential and electronic charge density are suggested.  相似文献   

8.
The nucleon effective interaction in the nuclear medium is investigated in the framework of the DiracBrueckner-Hartree-Fock (DBHF) approach. A new decomposition of the Dirac structure of nucleon self-energy in the DBHF is adopted for asymmetric nuclear matter. The properties of finite nuclei are investigated with the nucleon effective interaction. The agreement with the experimental data is satisfactory. The relativistic microscopic optical potential in asymmetric nuclear matter is investigated in the DBHF approach. The proton scattering from nuclei is calculated and compared with the experimental data. A proper treatment of the resonant continuum for exotic nuclei is studied. The width effect of the resonant continuum on the pairing correlation is discussed. The quasiparticle relativistic random phase approximation based on the relativistic mean-field ground state in the response function formalism is also addressed.  相似文献   

9.
The nonlinear absorption of electromagnetic radiation by electrons in a quantizing magnetic field is investigated. The inclusion of multiphoton processes is shown to result in additional peaks in the absorption curve. The shape and arrangement of these peaks were found. The absorption is shown to depend on the electric field strength in the electromagnetic wave nonlinearly and nonmonotonically. The results obtained are in good agreement with experimental data.  相似文献   

10.
The relevant equations for describing the Brochard-Leger wall in liquid crystals are found and analyzed. The analogy between the motion of the wall in liquid crystals and nerve propagation is traced. The theoretical results in this work are in excellent agreement with experiments. The basic consideration for the wall in this letter applies to describing other walls in liquid crystals.  相似文献   

11.
The electronic transport properties of pure MgS nanotube based molecular devices, Mn-substituted nanotubes and Se-substituted nanotubes are investigated using density functional theory. The state of the art of this work is to study the transport properties of MgS nanotubes with substitution impurities across electrodes. The electronic transport properties are discussed in terms of device density of states and transmission spectrum of MgS nanotubes. The effects of Mn substitution and Se substitution in nanotubes are studied. The major contribution to density of states arises only from p orbitals in MgS nanotubes. The substitution effect and bias voltages also have influence in the density of states. The transmission spectrum provides information about the transmission of electrons along the nanotube. The information provided in this work gives a clear vision to fine-tune MgS nanostructures with improved transport property in nanoelectronic device fabrication.  相似文献   

12.
The polarization state is modulated by tilting birefringence component placed in the feedback external cavity.The variation of the polarization state in one period of modulation is found to be similar to sine wave.The periods become increasingly smaller.The maximum of variation in one period decreases against the rotated angle.The experimental phenomenon is subjected to the change of optical path and secondary reflection.The phenomenon is analyzed theoretically based on geometrical optics and crystal optics.High-accuracy measurements of absolute and relative angles can be realized based on the experimental phenomenon.The angle resolution is 0.1 arcsec in theory.  相似文献   

13.
Prevalence of spontaneous otoacoustic emissions in neonates.   总被引:4,自引:0,他引:4  
The prevalence of spontaneous otoacoustic emissions (SOAEs) was measured in a group of 100 neonates and in a group of 50 normal-hearing young adults. The prevalence of SOAEs in the adult group (0.62) is at the high end of the range of prevalences reported in other surveys of adult SOAEs based on measurements using similar microphones. The prevalence of SOAEs in neonates (0.64) is not significantly different from that in adults. The various tendencies that have been found to be significant in the pooled results of other surveys are also evident in our adult group: more SOAEs in right ears, a higher prevalence of SOAEs in females, and a dependence between ears for the occurrence of SOAEs. The above-mentioned tendencies are also significant in the infant data. The major differences between the infant and adult results are the predominant SOAE frequency range and the average levels of SOAEs. The majority of adult SOAEs are between 1.0 and 2.0 kHz, whereas the majority of neonatal SOAEs are between 2.5 and 5.0 kHz. The average SOAE level is -2.6 dB SPL for adults and 8.5 dB SPL for infants.  相似文献   

14.
FAAS法测定土壤和蔬菜中的Cd元素   总被引:3,自引:0,他引:3  
本文以油菜为试材,用FAAS法对受Cd污染土壤中的全量Cd、有效态Cd以及油菜茎叶中的Cd含量进行了测定与分析。同时对土壤全量Cd、有效态Cd及茎叶中Cd的样品予处理方法进行了比较研究。结果表明,方法回收率在96%以上,样品测定的相对标准偏差小于3.97%。本方法快速、准确、干扰少。测定结果满意  相似文献   

15.
The quasifission dynamics in the reaction ~(48)Ca+~(244)Pu is investigated in the framework of time-dependent Hartree-Fock(TDHF)theory. The calculations are performed in three-dimensional Cartesian coordinate without any symmetry restrictions. The full Skyrme energy functional is incorporated in our TDHF implementation. The quasifission dynamics is quite sensitive to the angular momentum of colliding system. The contact time of quasifission decreases as a function of angular momentum and then forms a plateau with small oscillations. The quasifission process is accompanied by an important multi-nucleon transfer. The quantum shell effect plays a crucial role in the mass and charge of quasifission fragments. The mass-angle distribution of the fragments is calculated, which can be compared directly with future experiments.  相似文献   

16.
There is growing evidence to suggest that the binding energy of nucleon in nuclear matter comes from a cancellation between large Lorentz scalar and vector potentials[1,2]. The relativistic approach has been of a great success in describing not only the ground state properties of stable nuclei, but also those of exotic nuclei. In the relativistic frame, the spin-orbit coupling can be deduced automatically, which is usually given by hand in the non-relativistic approach. The relativistic method…  相似文献   

17.
This present paper reports the study of cadmium sulphide (CdS) nanoparticles prepared under controlled condition in methanolic solution and also in polyethylene oxide polymer electrolyte matrix. The sulphurations of the cadmium salts were done in situ by a sodium sulphide solution. The concentration of the precursors has been controlled as detailed in the paper. All the preparation and characterization were carried out at room temperature. The nanoparticles were characterized by UV/Vis spectra in the range of 600 to 250 nm. The absence of bulk/micron size particles was noted in either of the system. The absorption edge near 510 nm indicates the presence of bulk CdS, whereas the presence of nanometer-sized particles is also reflected in low wavelength region. The sizes of the particles as well as particle distribution have been estimated using X-ray diffraction and scanning electron microscopy, respectively. A comparison in the spectra has been done for the sample prepared in either of the matrices. The particle size distribution in the polymeric matrix has been found to be more in comparison to that in the methanolic suspension. The polymer is reported to work as a binder, but not as a capping agent.  相似文献   

18.
The effect of plastic deformations on the thermal stability and thermal photostability of F-centers in NaCl crystals was examined. The thermal photostability of F-centers and the thermal stability of some of these centers increases in proportion to the degree of plastic deformation. The concentration of the less stable F-centers increases due to plastic deformation. The effect was studied in crystals which were deformed before and after x-ray excitation. The results were interpreted from the viewpoint of an ionic activation mechanism in the thermal and photothermal decomposition of the color centers in alkalihalide crystals.The authors are indebted to Yu. L. Lukantsever for an evaluation of the results of this work.  相似文献   

19.
The massless field equations for arbitrary spin in curved space-time arereconsidered. The general solution of the field equation in Robertson-Walkerspace-time that was previously determined is briefly discussed after explicitlyshowing that the Weyl spinor vanishes. The case of the Lemaître-Tolman-Bondispace-time is studied in detail. The general expression of the corresponding Weylspinor is obtained and some particular situations exploited. The spin-3/2 andspin-2 massless field equations are solved explicitly. The solutions are simplifiedby the existence of nontrivial algebraic constraints. The angular part of theequations is separated by the usual separation method and integrated directly.The other equations that are not separated in the radial and time dependence arereduced to a simple form. The results obtained are extended, as a consequenceof previous results, to the case of arbitrary spin. The solution of the general caseessentially reduces to the treatment of spin 3/2 and spin 2.  相似文献   

20.
A stable formation of long thin filaments involving heavy particles (heavier than water) suspended in water in an acoustic resonator was observed. The filaments consisted of regularly spaced thin disks formed by coalescent particles. The particles in the disks were tightly packed forming almost solid structures. The disks were arranged perpendicularly to the filament axis and were spaced at half-sound-wavelength intervals. The diameter of the disks was about half-wavelength. The length of the filaments was about hundreds of the sound wavelength. Experiments were performed with particles of different natures and sizes. The filaments were not destroyed under wide variations of sound frequency, acoustic power, length of resonator, size and configuration of the mirror, or its angle of rotation. The particles suspended in water not only visualized the acoustic field but also affected its configuration. The formation of filaments was explained by a nonthermal self-focusing of sound in the resonator, which was caused by the decrease in sound velocity in the region of maximum concentration of particles due to coagulation in the inhomogeneous sound field.  相似文献   

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