[en] The spontaneous emission property of a five-level atom with a loop structure driven by three optical fields and a microwave field is intensively studied. Several quantum interference effects can be observed in the spontaneous emission spectra, such as spectral-line narrowing, spectral-line enhancement, spectral-line suppression, partial cancellation and fluorescence quenching. The number of emission peaks, the positions of dark lines can be controlled by varying the intensities of driving fields or the phase of the microwave field coupling the two lower levels in the atomic system. Furthermore, since no rigorous conditions are required, the expected phenomena may easily be achieved experimentally in atomic systems.

[en] We study the steady-state behaviour of spontaneous emission of a driven four-level atom embedded in photonic crystals. Considering different initial conditions, we discuss the influence of photonic band gap and detuning of external driving field on the atomic spontaneous emission spectrum. The photonic band gap and external driving field will impact strongly on the atomic spontaneous emission properties. Some interesting phenomena were found such as laser-induced dark line, laser-induced spectral-line narrowing and laser-induced pushing of a dressed state out of the band gap, which can be attributed to the quantum interference effect and control of the external driving field

[en] We study the influence of quantum interference on 2D sub-half-wavelength atom localization in a four-level atom driven by three external fields with a loop structure. When the dipoles of the two transitions from two upper levels to the lower level are parallel to each other, quantum interference between the two transitions arises. The analytical expression of conditional position probability (CPP) distribution is obtained using the iterative method. We discuss the influence of the detuning of the spontaneously emitted photon, the Rabi frequency of the microwave field and the dipole moment matrix element alignment p on the CPP. 2D sub-half-wavelength atom localization is obtained and the spatial resolution is improved significantly compared with cases with no quantum interference. (letter)

[en] AIM: To investigate the correlation between the degree of contrast enhancement of bladder cancer in the early enhanced phase of helical computed tomography (CT) and microvessel density (MVD), vascular endothelial growth factor (VEGF) and histological grade. MATERIALS AND METHODS: Sixty-five patients with transitional cell carcinoma of the bladder were examined by incremental unenhanced CT and helical CT at 40-45 s after initiation of intravenous administration of contrast medium before surgery. The CT density in Hounsfield units of bladder carcinomas were measured in the middle of the maximum diameter section of the cancer lesions on unenhanced and enhanced CT. The degree of contrast enhancement of the tumour was determined as the absolute increase in Hounsfield units. Histological grade, VEGF and MVD were analysed for each cancer. The Pearson and Spearman correlation tests were used to determine the strength of the relationships between CT enhancement and histological grade, VEGF expression and MVD. RESULTS: Different degrees of enhancement were observed in 91 cancers during the early enhanced phase of helical CT. Mean MVDs and mean CT enhancing values of different histological grade groups were statistically different (p<0.001). A positive correlation was found in the CT-enhancing value of bladder cancer and MVD (Pearson correlation test; r=0.938, p<0.001) and histological grade (Spearman rank correlation; r=0.734, p<0.001). VEGF of bladder cancer did not correlate with the change in CT attenuation (Spearman rank correlation; r=0.087, p=0.410) and MVD (Spearman rank correlation, r=0.103, p=0.330). CONCLUSION: In bladder cancer, the degree of contrast enhancement during the early enhanced helical CT is correlated with the MVD and histological grade of tumour. It is possible that MVD is the histopathological basis of early contrast enhancement of bladder cancer

[en] In order to assess spatial straightness error matched new generation Dimensional Geometrical Product Specification and Verification (GPS), the theory of spatial straightness error assessing is proposed and its advantages are analyzed based on metrology and statistics in this paper. Then, the assessing parameter system is proposed and it is testified in real application comparing to assessment result of the geometric tolerance theory. Statistical parameters of this assessing system post the different characteristics of spatial straightness error, and can reveal the impact of spatial straightness error on the accessory function more roundly to complement the single assessing parameter of geometrical tolerance for straightness error. The statistical spatial straightness tolerance and statistical spatial straightness error proposed in this paper is possible to be applied in evaluation of other error of form, orientation, location and run-out

[en] We study the control of spontaneous emission in a three-level V-type atom that is coupled by a static magnetic field in photonic crystals. We find that by changing the position of the upper band edge and Larmor frequency of the magnetic field, control of the steady-state behavior of spontaneous emission can be achieved. As the transition frequencies move from outside the band gap to inside, the structure of the spectral line changes from a two-peak structure to a single-peak structure, and then to a non-Lorentzian shape. With the increase of the Larmor frequency of the magnetic field, when both transition frequencies are outside the photonic band gap, the partial spectral line disappears; however, when both frequencies are inside the band gap, the non-Lorentzian shape is replaced by a Lorentzian shape. These phenomena arise from the fact that the corresponding transition frequency is pushed into or out of the band gap. (paper)

[en] The spontaneous emission spectrum of a three-level Λ-type atom driven by a microwave field was studied. For the two transitions coupled to the same modified reservoir, we discussed the influence of photonic band gap and Rabi frequency of the microwave field on the emission spectrum. The emission spectrum is given for different locations of the upper band-edge frequency. With the transition frequencies moving from outside the band gap to inside, the number of peaks decreases in the emission spectrum and the multipeak structure of spectral line is finally replaced by a strong non-Lorentzian shape. With increase of the Rabi frequency of the microwave field, we find the spectral line changes from a multipeak structure to a two-peak structure, originating from the inhibition of spontaneous emission for the corresponding decay channel.

[en] For a three-level Λ-type atom embedded in three-dimensional photonic crystals (PCs), the upper state population and spontaneous emission spectra are investigated with both transitions coupled to the same modified reservoir. By using an anisotropic dispersion model the analytic expressions of the upper state population and spontaneous emission spectra were obtained. The upper state population reaches a steady state value with a slight oscillation, and the spectra show a non-Lorentzian for both transition frequencies inside the band gap

[en] Chlorinated hydrocarbons are widely used as organic solvent and chemical raw materials. After treatment, water polluted with trichloroethylene (TCE)/tetrachloroethylene (PCE) can reach the water quality requirements, while water with trace amounts of TCE/PCE is still harmful to humans, which will cause cancers. Water distribution network is an extremely complicated system, in which adsorption, desorption, flocculation, movement, transformation and reduction will occur, leading to changes of TCE/PCE concentrations and products. Therefore, it is important to investigate the transformation rules of TCE/PCE in water distribution network. What’s more, growth-ring, including drinking water pipes deposits, can act as catalysts in Fenton-like reagent (H₂O₂). This review summarizes the status of transformation rules of CAHs in water distribution network. It also evaluates the effectiveness and fruit of CAHs degradation by Fenton-like reagent based on growth-ring. This review is important in solving the potential safety problems caused by TCE/PCE in water distribution network. (paper)

[en] A concept of softgauge has been proposed by ISO in the context of surface texture measurement, in which reference software and reference data are included. In this paper, an effective scheme to build reference software for 2D surface profile measurement is proposed. The advantage of the scheme lies in its effective combination of high numerical calculating capability of MATLAB with perfect interface programming capability of VC. Preliminary reference software is developed, and typical algorithms are tested