Frequency and Field Dependences of Giant Magneto-Impedance Effect in Sandwiched FeCuCrVSiB Films

The giant magneto-impedance(GMI)effect has been investigated in sandwiched FeCuCrVSiB films annealed at 300℃ for 1.5 h.The frequency and field dependences of the GMI have been observed in the frequency range from 50 kHz to 13 MHz.The GMI ratio increases at first with increasing frequency,and reaches its maximum value of 136%at a very low characteristic frequency of about 4 MHz,and then decreases with further increasing frequency.These superior properties are related to the special structure of the sandwiched films.

Investigation of Coercivity Mechanism for Nd-Fe-B Magnets Prepared by Combination of Strip-Casting with Hydrogen Decrepitation Techniques

The coercivity mechanism of Nd Fe B magnets prepared by combination of strip casting with hydrogen decrepitation techniques was investigated. The microstructure of (Nd 0.935 Dy 0.065 ) 14.5 Fe 79.4 B 6.1 magnet was observed. The average grain size is about 6～12 μm. The magnetizing field dependence of the hardmagnetic properties for the (Nd 0.935 Dy 0.065 ) 14.5 Fe 79.4 B 6.1 and the temperature dependence of the coercivity for the Nd 14.5 Fe 79.4 B 6.1 were investigated. Results show that the coercivity for magnets prepared by the combination of strip casting with hydrogen decrepitation techniques is controlled by the nucleation mechanism.

Nonlinear Electrical Behaviour of the TiO2.Sb2O3 System

The Sb2O3-doped TiO2 varistors were obtained by conventional ceramic processing. The 0.75mol%Sb2O3 99.25 mol%TiO2 varistor has a nonlinear coefficient α = 7 and a minimum breakdown electrical field of 6 V/mm. The nonlinear electrical behaviour of TiO2.Sb2O3 ceramics was explained by the introduction of defects in the crystal lattice that are responsible for the formation of Schottky potential barriers at grain boundaries.

Proton Transmitting Energy Spectra and Transmission Electron Microscope Examinations of Biological Samples

Transmission energy spectra of 530 keV H^(+) ion penetrating 140μm thick seed coat of maize and fruit peel of grape with thickness of 100μm were measured.The result indicates that these thick biological targets,as seen by the penetrating ions,are inhomogeneous,and there are open“channel like”paths along which the incidentions can transmit the targets easily.While most of the incident ions are stopped in the targets,some of the transmitting ions only lose a small fraction of their initial incident energy.The transmission energy spectra show a pure electronic stopping feature.Transmission electron microscope(TEM)micrographes taken from the samples of seed coat of maize and fruit peel of tomato with thickness of 60μm indicate that 150keV electron beam from the TEM can penetrate the thick samples to give very good images with clear contrasts.

Nonlinear Electrical Behaviour of the TiO_(2)·Y_(2)O_(3)·Nb_(2)O_(5) System

The nonlinear properties and the dielectric properties of a new TiO_(2)-based varistor system,TiO_(2)·Y_(2)O_(3)·Nb_(2)O_(5),have been investigated.The(Nb,Y)-doped TiO_(2)ceramics have nonlinear coefficients of α=5-8 and a lower breakdown electrical field of 6-12V·mm^(-1),in which the varistor of(99.3mol%)TiO_(2).(0.6mol%)Y_(2)O_(3).(0.1mol%)Nb_(2)O_(5)composite sintered at 1400℃ has a nonlinear coefficient of α=7.8 and a maximum breakdown electrical field of 12 V·mm^(-1) at 1 mA·cm^(-2).Also,the relative dielectric constants of the composite reach more than 85000,which is almost unchanged within the temperature range from-20 to 280℃ and the frequency range of 0.5 K-2 MHz.Due to these properties the(Nb,Y)-doped TiO_(2)varistors has varistor capacitance bifunctional components,which are quite useful in the situation that the voltage protection and high frequency noise absorption are meanwhile required.

Formation of Endohedral Complexes in Collisions of H_(2 ) and D_(2) with C_(60)

Formations of endohedral complexes in collisions of H_(2) and D_(2) with C_(60) molecules have been studied using a molecular dynamics simulation method.H@C_(60) complex is produced when a H_(2) molecule collides with a C_(60) molecule dong the direction from the center of a hexagonal ring into the center of the C_(60) at collision energy E0=40 eV.At the same collision condition,a D2 molecule colliding with a C_(60) molecule forms a D_(2)@C_(60) complex。

Specific Heat Anomaly of Lithium Sodium Niobate at Low Temperature

A differential scanning calorimetric(DSC)study of the crystal Li_(0.02)Na_(0.98)NbO_(3) was carried out in the temperature range from 120 to 300K.The specific heat changes anomalously at about 180K on cooling and about 260K on heating,implying a first order phase transition.The heat of transition ΔQ=(212±50)J/mol and the corresponding change in entropy AS=0.82J/mol.K.The thermal hysteresis of this transition is about 80K,in agreement with that previously obtained from the dielectric and pyroelectric measurements.

Electronic Stopping Power for 0.05-10 MeV Protons in a Group of Organic Materials

Electronic stopping powers for 0. 05-10 MeV protons in a group of organic materials are systematically calculated. The calculations are based on Ashley＇s dielectric model, and an evaluation approach of optical energy loss function is incorporated into Ashley＇s model because no experimental optical data are available for most of the organic materials under consideration. The Barkas-effect correction and Bloch correction are included. The proton stopping powers for the considered organic materials except for mylar in the energy range from 0.05 to 10 MeV are presented for the first time. The results may be useful for studies of various radiation effects in these materials and for space research.

Density isomer of nuclear matter in an equivalent mass approach

The equation of state of symmetric nuclear matter is studied with an equivalent mass model.The equivalent mass of a nucleon has been expanded to order 4 in density.We first determine the first-order expansion coefficient in the quantum hadron dynamics,then calculate the coefficients of the second to fourth order for the given binding energy and incompressibility at the normal nuclear saturation density.It is found that there appears a density isomeric state if the incompressibility is smaller than a critical value.The model dependence of the conclusion has also been checked by varying the first-order coefficient.

Cable attenuation study of Tibet water Cherenkov muon detector array-A

This work aims at online calibration of signal attenuation of the long cable used in Tibet water Cherenkov muon detector array-A (Tibet MD-A) under the Tibet air shower array.Based on a waterproof connection of the signal cable to PMT (R3600_06) and characters of the high voltage divider,terminal reflection method is used for measuring the signal attenuation with a practical way to eliminate contribution of the pulse baseline.Comparison measurement data-taking method (with charge-to-digital conversion) was carried out by using open-ended cables,confirming that terminal reflection method is a fast and convenient,and suitable to online calibration of the signal attenuation for Tibet MD-A.At 26℃,the measured attenuation coefficient with the 250-m cable connected permanently to the PMT,was ～13.9%.The cable frequency response was measured by using the sinusoidal signals.The method could be used to study time dispersion of signals produced with Tibet MD-A detector via Fourier analysis.

Geometry of time-dependent PT-symmetric quantum mechanics

A new type of quantum theory known as time-dependent𝒫PT-symmetric quantum mechanics has received much attention recently.It has a conceptually intriguing feature of equipping the Hilbert space of a𝒫PT-symmetric system with a time-varying inner product.In this work,we explore the geometry of time-dependent𝒫𝒯PT-symmetric quantum mechanics.We find that a geometric phase can emerge naturally from the cyclic evolution of a PT-symmetric system,and further formulate a series of related differential-geometry concepts,including connection,curvature,parallel transport,metric tensor,and quantum geometric tensor.These findings constitute a useful,perhaps indispensible,tool to investigate geometric properties of𝒫PT-symmetric systems with time-varying system’s parameters.To exemplify the application of our findings,we show that the unconventional geometric phase[Phys.Rev.Lett.91187902(2003)],which is the sum of a geometric phase and a dynamical phase proportional to the geometric phase,can be expressed as a single geometric phase unveiled in this work.

STUDY OF BARYON PRODUCTION IN UPSILON DECAYS AND IN NONRESONANT e^(+)e^(-) ANNIHILATION AT lOGeV ENERGY

We have studied the production of baryon in decays of the upsilon resonance by a simple gluon splitting assumption.The calculated results show that the production rate of baryons is enhanced in direct upsilon decay compared to continuum,and the prediction agrees well with experiments.

Hydrogen Generation from Water Splitting by Catalysts of Platinum-Based Clusters Pt3X(X=Al,Si,Cu)and CO Oxidation by Their By-Products

Reducing sizes of precious metals and utilization of the mixed small clusters of them as catalysts in reactions are important methods due to more active sites for higher catalytic eciency.Based on rst-principles calculations in this work,we found that the platinumbased clusters of Pt3X(X=Al,Si,Cu)which have the magic number 4 can e ectively catalyze the water decomposition and hydrogen production in just one-step reaction process.The adsorbates of the H2O@Pt3X clusters have strong absorption in the ultraviolet and visible regions with wavelength from 300 nm to 760 nm,indicating the sunlight can be used to drive catalytic hydrolysis for producing clean hydrogen.In addition,the O atom remains on the clusters after hydrolysis and can react with CO to form CO2 in activation barrier of 0.340.58 eV,showing the recycling ability of the products after hydrolysis for eliminating the"poisoning"CO by oxidation.Moreover,the formed CO2 molecule can be detached from the Pt3X clusters at 323 K.Our results provide interesting guidance for practical designing the useful photocatalysts.

Surface Modification of the Spontaneous Polarization in Ferroelectric Thin Films

The surface effects on the spontaneous polarization in ferroelectric thin films were discussed based on the Ising model in a transverse field.Both the modifications of the transverse field and the strength of coupling in the surface layer were taken into consideration.At the temperature much lower than the Curie point,the behaviour of the spontaneous polarization deviates from the phenomenological description.The surface effects might lead to the spontaneous polarization and the Curie temperature changing in different direction.The theory gives a reasonable description of the experimental temperature dependence of the spontaneous polarization of triglycine sulfate thin films in the literature.

Range Distribution Parameters of Implanted ^(19)F Ions in Ni_(0.8)Fe_(0.2) Alloy

Depth profiles of fluorine in ^(19)F^(+) implanted Ni_(0.8)Fe_(0.2) alloy have been accurately measured by using ^(19)F(p,αγ)^(16)O resonance nuclear reaction at ER=872.1keV.A proper convolution calculation method was used to extract the true distribution of fluorine from the experimental excitation yield curves.The range parameters,R,and ΔR_(p),were thereby obtained and compared with those simulated wit TRIM'90 code.It shows that the experimental R_(p) values agree with the Monte Carlo simulation values very well,while the experimental ΔR_(p) values are systematically larger than the calculation values.

Discontinuity of the Measurement-Induced Nonlocality Evolution

A novel resource,i.e.measurement-induced nonlocality,was proposed by Luo and Fu [Phys.Rev.Lett.106(2011)120401].It can directly reflect the usefulness of quantum nonlocality in quantum protocols.We investigate the dynamics of measurement-induced nonlocality by exactly solving a model which consists of two independent atoms each subject to a zero-temperature muti-mode cavity.We find that the dynamics of measurement-induced nonlocality is discontinuity under some special conditions.The reason for this phenomenon is the constraint of the von Neumann measurements which do not disturb the reduced density operator.We also find the sudden death phenomenon and the sudden birth phenomenon.

An Improved Calculation of Nonlinear Stopping Power of an Electron Gas for Slow Hydrogen Ions

The stopping power of an electron gas for hydrogen ions is calculated based on the full self-consistent nonlinear density-functional frame.Three different configurations of hydrogen ions are considered and a criterion to test the validity of the self-consistent calculation is proposed.Comparison of calculation with available experimental data shows good agreement.

Surface Effects on Dielectric Susceptibility of a Semi-infinite Ferroelectrie

The profilc of susceptibility uear the surfuce of a senni-ifinite frrclectric is calculatel from Luidau free energy.In surfunce ferroclectric plase,the susceptibility is reduced at surface for|δ|<<βand much enhanced for|δ|-β,whereδandβare the.extrapolation le1ngth and tle coluerent lengtl respectiv:ly.In ferroelectric phase,the surface susceptibility is gcllcrally reduced for8<0.But the crurve is not molnotonic,there is a mininum in the surface layer.Forδ>0,the surface susceptibility is.redced forδ<<βand enhanced fo rδ-β.The curve has a maxiln11 in the srface layer.

RATIO OF CHARMED BARYON TO MESON IN e^(+)e^(-) ANNIHILATION

A method to determine the value of the ratio of charmed baryon to meson in e^(+)e^(-) annihilation is investigated.Using the data of CLEO,HRS and MARK Ⅱ groups,we obtain f≡B_(c)/M_(c)=0.21±0.05,0.24±0.08 and 0.33±0.05,for √s=5.2,10.55 and 29GeV,respectively.

Size and Temperature Dependence of Dielectric Constant of Ultrafine PbTiO_(3) Particles

Using sol-gel method,we prepared ferroelectric PbTiO_(3) fine particles with particle size covering the range 20-200nm;the dielectric properties of powder compact were studied in the present work.The room temperature dielectric constant increases with the decrease in particle size and reaches a maximum value at the size of about 40nm.The temperature dependence of dielectric constant involving the evolution of particle size during the measurement is discussed.