MOESSBAUER SPECTROSCOPY OF HIGH Tc YBa2（Cu3—xFex）Oy

YBa2(Cu3-xFex)Oy(x is 0.001,0.005,0.01,0.1 and 0.3 respectively),of which Cu is replaced with ^57Fe are studied using Moessbauer spectroscopy to understand the crystal lattics property,the effects of the replacement on superconductivity of the High Tc materials.     

Short Notes ON THE γ—ε TRANSFORMATION BELOW THE NEEL TEMPERATURE IN Fe—Mn—Si ALLOYS

There are two tpyes of phase transformations in Fe-Mn and Fe-Mn-Si alloys when the temperature is decreased,γ(fcc)→ε(hcp) martensitic transformation(MT) and paramagnetic-antiferromagnetic transition (AMT) of γ phase.From the thermodynamic point of view,the former usually appears in a slightly higher temperature range than the latter because if is generally accepted that the magnetic tansition has a suppressing effect on the thermally induced ε martensite(Sato et al.,1984.,Bogachev and Zvigintzeva,1976;Murakami et al.,1987:Yang et al.,1992) Gartstein and Robinkin(1979) even thought that the γ-ε transformation should be terminated below Neel temperature(TN) due to the decrease of free energy arising from the AMT of γ phase.However,some experimental results hae indicated the formation of ε phase below T(Li and Wayman,1994:Fujimori.1966).In the present wert.the behavor of γ-ε transformation below TN was furtherinvestigated by clectrical resistance measurements.     

New modulation structures observed in Bi2.13Sr1.87CuO6 δ superconductors

A new two-dimensional structure modulation along c-and b-axes has been discovered in superconducting single crystals of Bi2.13Sr1.87CuO6 δ(Bi2201)by x-ray scattering.Such modulation structure does not exist in non-superconducting Bi2201 single crystals.But instead lattice distortions are observed in the a-b-plane.This phenomenon may indicate that both strain relaxation and charge modulation in the a-b-plane are important to the occurrence of superconductivity in the copper oxides.     

Measurement of ^17F（d,n）^18Ne Reaction

Explosive hydrogen burning occurs in very massive （M≥ 10^5-10^8 M） star with high temperature and density. Hot pp chain, hot CNO, hot NeNa-MgAl chain and the flowing γp and ap process will play a prominent role in hydrogen burning as. the temperature goes higher. When the temperature of the star is hither than 10^8 K. high temnerature CNO chain is dominant in hydrogen burning,     

The synergic extraction of uranium（VI） with tri－n－butyl phosphate（TBP） and petroleum sulfoxides（POSO）／benzene

The Synergistic extraction of uranium(VI) from nitric acid aqueous solution with a mixture of tri-n-butyl phosphate(TBP) and petroleum sulfoxides(PSO) in benzene was studied.It has been found that the maximum synergistic extraction effect occurs where the molar ratio of PSO to TBP is one to two.The composition of the complex of synergistic extraction is UO2(NO3)2.TBP.PSO.The formation constant of the complex KTP=57.44.     

Multi-technique characterizations of main elements in the vehicle exhaust particles collected in a tunnel in Shnaghai

In this study,vehicle exhaust particles were collected three locations (the middle,entrance and outside) of the Dapu Road tunnel in downtown Shanghai,and the particle samples were characterized using SEM,XAFS,ICP-MS and M?ssbauer spectrometry,and the oxidative damage was assessed by plasmid DNA.Most iron-containing particles are found from vehicle exhaust,and iron oxide is the major species in all samples.Its concentration in the particles inside the tunnel is higher than that the outside particles.The iron particles inside the tunnel have higher proportion of water-soluble fraction in hydrous iron sulfate form or smaller size.ZnCl2 is the main soluble fraction in zinc-containing particles,while higher percentage of insoluble fraction existed in the particles outside of tunnel.Major species of lead-containing particles are PbSO4,Pb3(PO4)2 and PbCO3.In addition,the soluble fraction of other transition metallic elements as Ti and V is higher in the particles inside the tunnel than that outside the tunnel.The plasmid DNA assay results indicate that the particles from vehicle exhaust have a stronger oxidative damage and inflammation than that from outside of the tunnel.     

Pair phase transition and its evolution on even ^64～68Ge isotopes

By using a microscopic sdlBM-2 2q.p, approach which is the phenomenological core plus two-quasi-particle model and the experimental single-particle energies, the levels of the ground-band, β-band, γ-band,and partial two-quasi-particle states on ^64～68Ge isotopes are successfully reproduced. Based on the phenomenological model and microscopic approach, it has been deduced that no s-boson in the nucleus is breaking up and aligning; and that when one d-boson does, the minimum aligned energy can be calculated. This paper explicitly indicates that, with the increase of neutron number, an evolution process of PPT objectes, i.e. from the two-quasi-proton states (on ^64Ge nucleus) to the two-quasi-neutron states (on ^68Ge nucleus) may take place in even Ge isotopes.     

A Simulation Study of Hall Effect on Double Tearing Modes

A Hall magnetohydrodynamics （MHD） simulation is carried out to study the dynamic process of double tearing mode. The results indicated that the growth rates in the earlier nonlinear and transition phases agree with the previous results. With further development of reconnection, the current sheet thickness is much smaller than the ion inertia length, which leads to a strong influence of the Hall effects. As a result, the reconnection in the late nonlinear phase exhibits an explosive nature with a time scale nearly independent of resistivity. A localized and severely intensified current density is observed and the maximum kinetic energy is over one order of magnitude higher in Hall MHD than that in resistive MHD.     

XAFS study of Cu2+ in aqueous solution of CuBr2

Copper ion is the essential microelement to many organisms. In this paper, the local structure of Cu2+ in CuBr2 aqueous solutions with different concentrations are investigated by using X-ray absorption fine structure (XAFS) technique. XANES (X-ray Absorption Near Edge Structure) spectra indicate that charge transfer from Br- to Cu2+ decreases with the solution concentration, which lead to a shift of the absorption edge. The shoulder appearing at the rising edge proves to be characteristic of a tetragonal distortion. The Fourier transform magnitudes of EXAFS (Extended X-ray absorption fine structure) data of Cu species suggest that more Cu-Br bonds may exist in high concentrations. A fivefold coordination configuration like a pyramid is used as the fitting parameters. From the analysis of the coordination numbers, the proportion of Cu-O and Cu-Br is 4:1 in the saturated solution. The Br atom is on the equatorial plane of the model. The fitting results agree well with the experiment data.     

Nondestructive Determination of Cu Residue in Orange Peel by Laser Induced Breakdown Spectroscopy

Laser induced breakdown spectroscopy(LIBS) is an emerging tool with rapid,nondestructive,green characteristics in qualitative or quantitative analyses of composition in materials.But LIBS has its shortcomings in detect limit and sensitivity.In this work,heavy metal Cu in Gannan Navel Orange,which is one of famous fruits from Jiangxi of China,was analyzed.In view of LIBS's limit,it is difficult to determinate heavy metals in natural fruits.In this work,nine orange samples were pretreated in 50-500 μg/mL Cu solution,respectively.Another one orange sample was chosen as a control group without any pollution treatment.Previous researchers observed that the content of heavy metals is much higher in peel than in pulp.So,the content in pulp can be reflected by detecting peel.The real concentrations of Cu in peels were acquired by atomic absorption spectrophotometer(AAS).A calibration model of Cu I 324.7 and Cu Ⅰ 327.4was constructed between LIBS intensity and AAS concentration by six samples.The correlation coefficient of the two models is also 0.95.All of the samples were used to verify the accuracy of the model.The results show that the relative error(RE) between predicted and real concentration is less than 6.5%,and Cu Ⅰ 324.7 line has smaller RE than Cu Ⅰ 327.4.The analysis demonstrated that different characteristic lines decided different accuracy.The results prove the feasibility of detecting heavy metals in fruits by LIBS.But the results are limited in treated samples.The next work will focus on direct analysis of heavy metals in natural fruits without any pretreatment.This work is helpful to explore the distribution of heavy metals between pulp and peel.     

Radar scattering width effects by coating 90Sr/90Y layers on cylindrical targets

In this paper,the ~(90)Sr/~(90)Y coating effects on scattering width(SW) of cylindrical conductor targets are investigated.The electron density distribution of plasma around cylindrical targets of different radiuses is simulated under different radioactivities in normal or oblique incidence.In normal incidence,the SWs are examined as functions of frequency and scattering angle;while in oblique incidence,the SW is inspected as a function of incident angle at the frequency of 1.5 GHz.The results obtained are compared with those from an ideal perfect electric conductor(PEC) cylinder.It is demonstrated that the SW decreases over a wide frequency range in the back scattering region by coating a ~(90)Sr/~(90)Y layer on the cylindrical target.Moreover,the reduction in bi-static SW amplitude can reach 3-20 dB,when the incident angle is smaller than 30° at 1.5 GHz.It is a significant improvement in the stealth effect.     

Metabolic peculiarity of 134Cs and its radioimmunotoxicological effect on central and peripheral immune cells

A fitted equation with least square method to describe the retention of ^134Cs in whole body is obtained by a whole body counter.That is R(t)=18.04exp(-9.3175t) 45.13exp(-0.0423t),where R(t) is in %,and t in d.The equationn consists of two half-life components,the fast component is T1/2=0.07d,and the slow is T1/2=16.14d,Study on the localization of ^134Cs at cellular level was carried out by freezing microautoradiography.The results indicate of ^134Cs at cellular level was carried out by freezing microautoradiography.The results indicate that ^134Cs was chiefly in ionizing form accumulated in red as well as white blood cells.In bone marrow cells ^134Cs predominantly deposited in young cells and less in mature cells.Distribution of ^134Cs penetrated quickly into the tissue cells.The observation of investigating radioimmunotoxicological effect induced by ^134Cs shows that the inhibition of thymocytes is higher than bone marrow cells,the spleen T lynmphocytes are more sensitive to ^134Cs than B lymphocytes and lymphocytes of peripheral immune cells are more sensitive to radiation than central immune cells.     

Theoretical Study of ^2H（d,γ）^4He Reaction Below Ecm〈3 MeV

The reaction cross sections of ^2H（d,γ）^4He at the astrophysically interesting energies （about below few hundreds of keV） are extremely low. Presently it is impractical to measure in the laboratory. Therefore the theoretical investigation is required to predict the relevant cross section data.     

Neutron yields and emission rates in the forward direction for 50MeV／u ^18O—ion on thick Be,Cu,Au targets

Total neutron yields and neutron emission rates in the forward direction for 50MeV/u ^18O-ion on thick Be,Cu,Au targets have been measured using an activation technique.The results indicate that neutron yields and emission rates in the forward direction depend on the atomic number of target nuclei,i.e.the lighter target the greater neurtron yield and neutron emission rate.Meanwhile,the neutron yield of ^18O-ion is greater than that of 12C-ion when target nucleus and incident energy per nucleon are identical.     

Preclinical pharmacology study of neutral myocardial imaging agent ^99mTcN（NOEt）2

To explore the biological properties of a new neutral myocardial imaging agent ^99mTcN(NOEt)2,preparation and characterization of ^99mTcN(NOEt)2, kinetics of blood-drug clearance in rabbits,biodistribution in rats,test of undue toxicity in mice and myocardial imaging in dogs were performed and volunteer imaging,Radiochemical purity of 99m TcN(NOEt)2 was over than90% and stable for 6 hours at room temperature.Blood disappearance was analyzed with biexponential model,T1/2(α)=2.53min,T1/2(β)=330min and Cl=378mL/h were obtained.Biodistribution studies demonstrated that ^99mTcN(NOEt)2 localized selectively in myocardium of rats.Cardiac uptake were 2.79,2.25,2.00 and 1.88%ID/organ at 5,30,60 and 90min of postinjection,respectively.The heart-to-lung activity ratio was 1.16 at 60 min.Images showed that pulmonary uptake decreased faster than cardiac uptake in a dog.The mean heart-to-lung activity ratios in a dog were 1.69,2.40and 2.55at 10,30and 60min of postinjection,respectively.The heart was distinguishable on scans at 30min.Whole body imaging showed that cardiac uptake was 2.82%ID at 90min,but hepatic uptake was 30%ID and remained constant.The test of undue toxicity showed that the dose received by mice was 614 times as by human.Volunteer imaging suggests ^99mTcN(NOEt)2 redistribution with time.^99mTcN(NOEt)2 exhibited favorable stabilities,biological properties and safety,It is worth for further studying in human.     

Ignition Conditions for Simulated Fuel Pellets in Degenerate Plasma

A high-density, low-temperature plasma can be obtained during the compression phase in inertial confinement fusion. When high density and low temperature are reached in the plasma in the fast ignition approach, the plasma electrons can be degenerate. The electronic stopping of a slow ion is smaller than that given by the classical formula, because some transitions between the electron states are forbidden. In this case, bremsstrahlung emission is strongly suppressed and the ignition temperature becomes lower than that in classical plasma. The equations that predict the behavior of these plasmas are different from the classical ones, and this is the main factor in the process of decreasing the ignition temperature of the plasma. In this work, physical conditions of ignition are studied by calculating the effect of radiation loss on the ignition temperature for a simulated fuel pellet, (D/T x / 3 He y ), in degenerate plasma. In fast ignition, the energy needed for obtaining high densities is minimized and the gain can be increased considerably.     

An Accurate Measurement of ~(90)Sr Concentration in the IAEA Reference Material Soil-6

Under an IAEA project for upgrading of the reference materials, an accurate measurement of ~(90)Sr inthe Soil-6 is performed. Both rapid and previous methods are used for measurement of ~(90)Sr. However, theresults show that the chemical procedure of the rapid method is not suitable for the Soil-6 material due tothe contamination of considerable amount of interfering ~(210)Bi, which exists in the natural uranium series.     

Study of the relationship between the local geometric structure and the stability of La_(0.6)Sr_(0.4)MnO_(3-δ) and La_(0.6)Sr_(0.4)FeO_(3-δ)electrodes

Sr-substituted ABO_3 perovskite oxides such as La_(0.6) Sr_(0.4 )Mn_(O3-δ)(LSM) and La_(0.6) Sr_(0.4) FeO_(3-δ)(LSF) are widely used as oxygen electrode materials in solid oxide cells. The substituted Sr is not adequately stable under the operating conditions, because of the surface segregation of Sr. Herein, we focused on investigating the relationship between the local geometric structure due to Sr substitution and stability of LSM and LSF. We characterized the local geometric structure of Sr atoms via X-ray absorption spectroscopy. A greater Debye-Waller factor and a longer bond length of both the second and third Sr-O shells were observed in LSF, which demonstrates that LSF has a higher local structural disorder and that Sr in LSF requires less energy to segregate. After 20 h of heat treatment in the presence of a Fe-Cr alloy interconnect, the Sr/La molar ratio on LSF was observed to be much larger than that on LSM. This result unequivocally suggests that Sr in LSF is not as stable as in LSM, and the reaction between Sr and Cr accelerates the Sr surface segregation in LSF.     

A THEORETICAL CALCULATION OF n-T SCATTERING CROSS SECTIONS

By using the phase shift analysis method,the σ_t,σ_(nn),σ_(non) and σ(θ)of n-Tscattering were calculated.The calculated results are in good agreement withthe new experimental data and better than the previous calculations.     

Research on the method of dual-frequency microwave diagnosis of plasma for solving phase integer ambiguity

In this work,microwaves and terahertz waves have performed a dual-frequency combineddiagnosis in high-temperature,large-scale plasma.According to the attenuation and phase shift of electromagnetic waves in the plasma,the electron density and collision frequency of theplasma can be inversely calculated.However,when the plasma size is large and the electron density is high,the phase shift of the electromagnetic wave is large (multiple times 2π period).Due to the limitations of the test equipment,the true phase shift is difficult to test accurately or to recover reality.That is,there is a problem of phase integer ambiguity.In order to obtain a phase shift of less than 180°,a higher electromagnetic wave frequency (terahertz wave with 890 GHz)is used for diagnosis.However,the attenuation of the terahertz wave diagnosis is too small (less than 0.1 d B),only the electron density can be obtained,and the collision frequency cannot be accurately obtained.Therefore,a combined diagnosis was carried out by combining twofrequencies (microwave with 36 GHz,terahertz wave with 890 GHz) to obtain electron density and collision frequency.The diagnosis result shows that the electron density is in the range of(0.65–1.5)×10~(19)m~(-3),the collision frequency is in the range of 0.65–2 GHz,and the diagnostic accuracy is about 60%.