[en] The phenomena of CP non-conservation are analyzed within the left-right symmetric model with four quarks. Our result is shown to be consistent with experiments. We comment on the previous analyses which exhibit inconsistency from ours. We further apply our result to the case of six quarks. (Author)

[en] Supersymmetry is broken spontaneously at finite temperature due to opposite statistics between bosons and fermions. Using real-time formalism, the massless pole in the fermionic Green's function is seen to be related to the existence of Goldstone fermion mode. If the Lorentz covariance is lost the zero energy mode is realized as thermal superpair mode instead of Goldstone fermion mode. This implies the degeneracy of fermionic and bosonic masses at finite temperature. (Author)

[en] ^99mTc-(V)-DMSA is a tumor seeking agent that has been used to image medullary carcinoma of thyroid, soft tissue sarcoma and lung cancer. This study was designed to assess the clinical role of DMSA in the diagnosis of head and neck cancers. We has evaluated the diagnostic efficacy of planar and SPECT imaging using ^99mTc-(V)-DMSA. Sixty-eight patients with head and neck mass were included in this study. All subjects were diagnosed by biopsy or surgery. Planar and SPECT images were obtained at 2 or 3 hour after intravenous injection of 740 MBq(20 mCi) ^99mTc-(V)-DMSA. Seventeen patients also underwent SPECT imaging using dual head camera. The diagnostic sensitivity of ^99mTc-(V)-DMSA planar and SPECT imaging was 65% and 90%, and specificity was 80% and 66%, respectively. The sensitivity of planar imaging in squamous cell carcinoma was similar to overall sensitivity. Six metastatic lesion were first diagnosed by scintigraphy. But benign lesions such as Kikuchi syndrome, tuberculous lymphadenitis also revealed increased uptake. ^99mTc-(V)-DMSA imaging seems to be a promising method in the evaluation of patients with head and neck mass. We recommend SPECT imaging to delineate anatomic localization of the lesion.

[en] In order to study the energy spectrum response of a CdZnTe detector, we firstly measured the temperature dependence and the bias dependence of the main characteristic parameters for both a quasi-hemispherical detector and a CAPture^TM plus detector. Secondly, we designed a low-noise readout circuit for the CdZnTe detector and measured the noise. Finally, we evaluated the energy spectrum response of the detector to different radioactive sources at different temperatures by connecting the detector to the readout circuit. The research showed that both detectors had low leakage current and junction capacitance, as well as good stability in temperature and bias; the quasi-hemispheric detector had a smaller leakage current and junction capacitance compared to the CAPture^TM plus detector; under zero input capacitor, the noise of the readout circuit was 612e, with the noise slope being 5.44e/pF; at room temperature(20 ℃), the energy resolutions of the detector reached 3.84% and 1.36% for X-rays from ²⁴¹Am (59.5 keV) and gamma-rays from ¹³⁷Cs (662 keV), respectively; the signal-noise ratio of the output signal reached 31:1 with the rise time being 90 ns; at low temperature, the energy resolution reached 3.41% for the X-rays from ²⁴¹Am (59.5 keV); the detector achieved an excellent spectrum response and was able to distinguish clearly the energy peaks of ¹⁵²Eu and ²²⁶Ra.

[en] 304 NG austenitic stainless steel is widely used in nuclear power industry because of its good mechanical properties and corrosion resistance. 304 NG austenitic stainless steel irradiated will produce many kinds of point defects, which will affect the mechanical properties of the material. In order to study the formation mechanism of point defects in 304 NG austenitic stainless steel, the lattice constants, formation energies, binding energies, migration barriers and interactions of various point defect structures are calculated by the first-principles method based on density functional theory in FCC Fe-Cr-Ni alloys, and the corresponding properties in γ-Fe are calculated as a comparison. The results show that Fe vacancy and Fe-Fe <100> dumbbell are easy to form in Fe-Cr-Ni alloys. Based on the analysis of the migration barriers of the two kinds of point defects, it is learnt that Fe-Fe <100> dumbbell is easier to migrate than the Fe vacancy in Fe-Cr-Ni alloys. The calculation of point defects interaction energies show that there is an attractive interaction between adjacent vacancies in Fe-Cr Ni-alloys, which can promote the formation of voids;there is a weak repulsive interaction between Fe vacancy-Fe-Fe <100> dumbbell and Fe vacancy-Fe-Cr <100> dumbbell, and Fe atoms in the octahedral interstitial sites in both the first-nearest-neighbor shell and the second-nearest-neighbor shell enter into vacancy and let the structure become a complete crystal cells. (authors)

[en] Currently, the quantitative analysis methods for uranium that are widely used in laboratories, such as the volumetric method and inductively coupled plasma mass spectrometry (ICP-MS) cannot achieve low cost, simple operation, and little infuence by other elements. The inductively coupled plasma optical emission spectrometer (ICP-OES) has a wide linear range, and high stability, and can be used to identify multiple elements simultaneously. However, when ICP-OES is used for quantitative analysis of uranium, the settings for the RF power, nebulizer fow, and pump rate can afect the analysis results. In this work, these parameters were carefully optimized for identifying uranium. Based on experiments, we selected two spectrum peaks 409.014 nm and 424.167 nm for quantitative analysis with the lowest interference. The optimal parameters obtained are atomizer fow rate of 0.75 L/min, a sample pumping rate of 1.6 mL/min, and a high-frequency power of 1400 W. Then we compared the accuracy of the volumetric method, ICP-MS method and ICP-OES method with the optimized parameter for analysis of experimental samples and references. The results showed that the ICP-OES with the optimized parameters proposed in this paper can be used to perform a convenient, quick, and efcient quantitative analysis of uranium in minerals

[en] Highlights: • Put forward four common structures of the gradational lead screw vacuum pump. • Establish the helix equation of MGLS rotor under a cylindrical coordinate system. • Divide the thermodynamic procedure into four distinctive process. • Deduce the mathematical expressions of seven thermodynamic parameters. • Explanation for MGLS rotor in saving energy, reducing noise and heat dissipation. As a kind of dry mechanical vacuum pump, the twin-screw vacuum pump has an outstanding pumping performance during operation, widely used in the semiconductor industry. Compared with the constant lead screw (CLS) vacuum pump, the gradational lead screw (GLS) vacuum pump is more popularly applied in recent years. Nevertheless, not many comparative studies on the thermodynamic performance of GLS vacuum pump can be found in the literature. Our study focuses on one type of GLS vacuum pump, the multi-stage gradational lead screw (MGLS) vacuum pump, gives a detailed description of its construction and illustrates it with the drawing. Based on the structural analysis, the thermodynamic procedure is divided into four distinctive processes, including sucking process, transferring (compressing) process, backlashing process and exhausting process. The internal mechanism of each process is qualitatively illustrated and the mathematical expressions of seven thermodynamic parameters are given under the ideal situation. The performance curves of MGLS vacuum pump are plotted by MATLAB software and compared with those of the CLS vacuum pump in the same case. The results can well explain why the MGLS vacuum pump has more favorable pumping performance than the CLS vacuum pump in saving energy, reducing noise and heat dissipation.

[en] A nonlinear Schroedinger equation with varying dispersion, nonlinearity and gain (or absorption) is studied for ultrashort optical pulses propagating in inhomogeneous optical fibres in the case of normal dispersion. Using the modified Hirota method and symbolic computation, the bilinear form and analytic soliton solution are derived. Stable bright and dark solitons are observed in the normal dispersion regime. A periodically varying soliton and compressed soliton without any fluctuation are obtained. Combined and kink-shaped solitons are observed. Possibly applicable soliton control techniques, which are used to design dispersion-managed systems, are proposed. The proposed techniques may find applications in soliton management communication links, soliton compression and soliton control. (solitons)

[en] [Background] During the radioactive source inspection or the orphan source disposal, it is essential to estimate the activity of the radioactive source quickly and effectively. However, this may be difficult, especially when the source is under shield with unknown shield thickness. [Purpose] This study aims to establish an activity estimation method of shielded multi-energy gamma-ray sources. [Methods] First of all, based on the relationship between the material attenuation coefficient and energy of the gamma-ray source, a method for the activity estimation of shielded multi-energy gamma-ray source was established. Then, influences of the position bias between the radioactive source and the detector, the characteristic energy selection, and the effect of statistical fluctuations were investigated by experiments. Finally, the optimal characteristic energy of common multi-energy gamma-ray sources and the maximum measurable shield thickness of the radioactive sources with different activities were analyzed. [Results] The experimental results show that the relative errors between the estimated thickness and the real thickness is less than 4%, and the relative errors between the estimated activity and the real activity is less than 5%. [Conclusions] The method proposed in the paper can be applied to the radioactive source inspection or the orphan source disposal. (authors)

[en] Molecular dynamics simulations of nanoindentation are performed to investigate the strengthening mechanisms of graphene coatings on Cu film substrate. It is found that the load bearing capacity of Cu substrate can be evidently improved after covering graphene coatings, and this turns out to be proportional to the number of graphene layers from monolayer to trilayer. The strengthening mechanism of elastic stage mainly results from the stress homogenization effect generated by graphene interface. Moreover, the efficiency of graphene strengthening during plastic stage is much higher than the elastic stage. The interactions between dislocations and graphene coating interface are fully responsible for the strengthening increase of Cu/graphene system in the plastic stage. In addition, a theoretical model to predict the strength of Cu/graphene system depending on the confined layer slip (CLS) model is established.