[en] Reported are interactions of high-intensity laser pulses (λ=810 nm and I≤3x10¹⁸ W /cm² ) with plasmas in a new parameter regime, in which the pulse duration (τ=29 fs ) corresponds to 0.6-2.6 plasma periods. Relativistic filamentation is observed to cause laser-beam breakup and scattering of the beam out of the vacuum propagation angle. A beam of megaelectronvolt electrons with divergence angle as small as 1 degree sign is generated in the forward direction, which is correlated to the growth of the relativistic filamentation. Raman scattering, however, is found to be much less than previous long-pulse results. (c) 2000 The American Physical Society

[en] Stereotactic body radiation therapy (SBRT), due to its high precision for target localizing, has become widely used to treat tumours at various locations, including the lungs. Lung SBRT program was started at our institution a year ago. Eighteen patients with peripheral lesions up to 3 cm diameter have been treated with 48 Gy in 4 fractions. Based on four-dimensional computed tomography (4DCT) simulation, internal target volume (ITV) was delineated to encompass the respiratory motion of the lesion. A margin of 5 mm was then added to create the planning target volume (PTV) for setup uncertainties. There was no expansion from gross tumour volume (GTV) to clinical target volume (CTV). Pinnacle 9.6 was used as the primary treatment planning system. Volumetric modulated arc therapy (VMAT) technique, with one or two coplanar arcs, generally worked well. For quality assurance (QA), each plan was exported to Eclipse 10 and dose calculation was repeated. Dose volume histograms (DVHs) of the targets and organs at risk (OARs) were then compared between the two treatment planning systems. Winston-Lutz tests were carried out as routine machine QA. Patient-specific QA included ArcCheck measurement with an insert, where an ionization chamber was placed at the centre to measure dose at the isocenter. For the first several patients, and subsequently for the plans with extremely strong modulation, Gafchromic film dosimetry was also employed. For each patient, a mock setup was scheduled prior to treatments. Daily pre- and post-CBCT were acquired for setup and assessment of intra-fractional motion, respectively

[en] Graphical abstract: A novel Tb complex was prepared by a simple way used sulfonate ligands owing to their broaden applications in various areas and abundant coordination modes, and the compound showed excellent electrochemiluminescence properties under the optimized conditions. Then a facile and fast response ECL senor was fabricated for sensitive and specific detection of Cd²⁺ based on effective quenching of ECL signal after addition of Cd²⁺. The low cost, facile preparation and simple instrument offer a alternative strategy for detection metal ions in real samples, and broaden the application fields of ECL system. - Highlights: • A novel Tb complex was synthesized with the ligand of pyridine-3-sulfonic acid, which has excellent ECL performance. • A simple and straightforward ECL senor was constructed for sensitive and selective detection of Cd²⁺. • Low cost, fast analysis and facile operation offered a promising method to detect the Cd²⁺ in real samples. - Abstract: In this paper, we report a novel rare earth metal complex with the weak ligand of aromatic sulphonic acid (pyridine-3-sulfonic acid, 3-pSO₃H), and characterized by FT-IR, UV–vis, energy-dispersive X-ray spectroscopy (EDX), electrochemiluminescence spectra, etc. Then an excellent electrochemiluminescence (ECL) signal was observed with K₂S₂O₈ as the coreactant in NaAc-HAc buffer solution. For another thing, the electrochemical properties of the compound have been thoroughly investigated in acetonitrile solution, the possible ECL reaction mechanism was proposed as well. Furthermore, a simple and straightforward ECL platform was reported for sensitive and selective detection of Cd²⁺ due to the effective quenching after addition of Cd²⁺. Other heavy/transition metal ions do not interfere with the sensing. The limit of detection is determined as 0.13 nM, the results suggested that as-prepared complex could be a promising material for developing ECL senors to detect the Cd²⁺ rapidly indwell in environmental and practical samples.

[en] The content of glycocholic acid (CG) in pregnant women's sera is detected with CG radioimmunoassay (RIA). The content of CG in sera of normal pregnant women after 32 weeks is ascended slightly with the increasing of pregnant month. It is less than 7.0 μmol/l before 31 weeks in pregnancy and less than 9.4 μmol/l after 32 weeks. The serum CG content of patients with intrahepatic cholestasis in pregnancy (ICP) is increased by 100%. The CG value of about half patients appears earlier than pruritus and ALT rise, the earliest CG increasing appears in the 20th pregnant week. It is the most sensitive method for ICP early diagnosis. 136 cases of ICP patients are observed and the results show that the higher the CG content, the higher the rate of intrauterine fetal anoxia; therefore, the dynamic observation of CG content in ICP patients is a dependable objective for surveillance fetal prognosis

[en] Direct X-ray imaging using a Fresnel zone plate (FZP) in the applications of laser plasma or inertial confinement fusion diagnostics has the potential for realizing high spatial resolution in the range of micrometers to sub-micrometers. For such an FZP imaging, the influences of the object size and the spectral bandwidth of the illuminating light have to be considered. In the simulations, numerical calculations such as the Fresnel-Kirchhhoff diffraction integral and convolutions have to be done, which will take a large amount of computer memories and cost a lot of computing time. In this paper we report improved algorithms for these numerical calculations by adopting the Monte-Carlo integration and a new algorithm of convolution. By simulating the two-dimensional imaging of an extended polychromatic X-ray source, it shows that the new algorithm has significant advantages in reducing the computing time over the past algorithms, and thus such simulations can be done by a desktop computer. The imaging indicates that with the increase of the object size and/or the spectral bandwidth, the image background is enhanced which causes the decrease of the contrast and also the image quality. (authors)

[en] X-ray diffraction imaging is capable of realizing near-diffraction-limited spatial resolution. This paper uses analytical and numerical approaches to study and compare Fresnel zone plate (FZP) imaging and projection-type phase contrast imaging of an object backlit by an X-ray source. The energy of X-rays is the Ti Kα line (4.5 keV) or Cu Kα line (8 keV). The results show that the spatial resolution of FZP imaging is better than 1 μm, and it is beneficial to use a backlighting source of larger size. For high transmission or weak absorption object, FZP imaging does not work well due to poor contrast. In this case, projection-type phase contrast imaging may be applied to achieve a spatial resolution of a few microns. By including higher-order effect that was not considered before, analytical formulae for image intensity and contrast are given. Numerical approaches are also used to study the phase contrast imaging of thin film target with thickness fluctuations or spatial density modulations illuminated by a microfocus X-ray source. In the case of a point source the theoretical contrast of images coincides well with simulation result. The influence of X-ray source size and imaging distance on the image's contrast and spatial resolution is discussed. It is indicated that by controlling the source size and changing the distance between the object and the detector, the spatial resolution could be optimized to 1-4 μm. (authors)

[en] Using the computational fluid dynamics software Fluent, the three-dimensional turbulent flow of the reactor coolant pump (RCP) impeller at different flow rates and different concentrations of boric acid is simulated. With the experimental data, different effects on RCP performance are analyzed between water and boric acid, especially the influence to the impeller. The feasibility of taking the water as coolant in RCP by using numerical simulation method is analyzed, and the result shows that negligible differences in water and boric acid was acquired even in abnormal concentration of boric acid. It proved that the using of water as coolant when conducting a simulation is feasible. (authors)

[en] Six new coordination polymers, [ZnLCl]_n(1), [ZnL_2]_n·2nH_2O (2), [Zn_2L(o-bdc)(OH)]_n·0.5nH_2O (3), [Zn_2L(m-bdc)(OH)]_n·nH_2O (4), [Zn_2L_2(p-bdc) (H_2O)_2]_n·nH_2O (5), [Zn_2L(1,2,4-btc)(H_2O)]_n(6), (HL=4′-(3-carboxyphenyl)- 3,2′:6′,3″-terpyridine, H_2(o-bdc)= benzene-1,2-dicarboxylic acid, H_2(m-bdc)= benzene-1,3-dicarboxylic acid, H_2(p-bdc)= benzene-1,4-dicarboxylic acid, H_3(1,2,4-btc)= benzene-1,2,4-tricarboxylic acid) have been synthesized under the hydrothermal conditions. Compound 1 displays a 3-connected 2D network structure with point symbol of {8"2.10}. Compound 2 exhibits 1D infinite loop chain structure. Compound 3 possesses a (3,8)-connected 3D framework composed of tetranuclear units with point symbol of {4"3}_2{4"6.6"1"8.8"4}. Compound 4 features a typical 2D hcb network based on tetranuclear zinc(II) units with point symbol of {4"4.6"2}. Compound 5 presents a classical two-fold penetration sql network with point symbol of {6"3}. Compound 6 can be seen as a (3,3,6)-connected 3D net with point symbol of {4"2.6"4.8"9}{4"2.6}{6"3}. The thermal stability and luminescent properties of compounds 1–6 in the solid state are discussed in detail. - Graphical abstract: Six new Zn(II) coordination polymers based on multicarboxylate and terpyridyl derivative ligands have synthesized under the hydrothermal conditions and the thermal stability and luminescence are discussed. Display Omitted

[en] A Monte Carlo code is developed to study mega-electron-volt (MeV) electron scattering and transport in plasma based on multiple scattering. A scaling law relating the angular width of a scattered beam to the incident electron energy and the areal density of plasma is found, which may provide a method of MeV electron radiography for diagnosing the areal density of high-temperature, dense plasma under fusion conditions. The study on the MeV electron beam radiography also shows that plasma density interfaces could be discriminated by electron scattering. (authors)

[en] The spectral and spatial characteristics of X-ray emission (5-200 A) along or off the axis of the plasma column, produced by 1.06 μm laser beam irradiating aluminium flat target in line focused configurations with an average power density 2 x 10¹² W/cm², are studied by using a pinhole transmission grating spectrograph (PTGS). Problems for the plasma as an X-ray-laser gain medium are also discussed