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[en] We investigate interplay between external field and interatomic interaction and its applications to coherent control of quantum tunneling for two repulsive bosons confined in a high-frequency driven double well. By using a full solution which is generated analytically as a coherent non-Floquet state, three kinds of the stationary-like states (SLSs) with different degeneracies are illustrated, which corresponding to the different coherent destructions of tunneling (CDT) at the Floquet level-crossing, avoided-crossing and uncrossing points. The analytical results are numerically confirmed and perfect agreements are found. Based on the results, a useful scheme of quantum tunneling switch between the SLSs is presented
[en] We theoretically investigate the influences of the Dzyaloshinskii–Moriya interaction (DMI) on the spin-polarized transport through a single-molecular magnets, which is weakly coupled to ferromagnetic lead-L(pL) and nonmagnetic lead-R. The spin current is obtained by means of the rate-equation approach in the sequential-tunneling region. Due to the coherent superposition of the molecular state |1,m〉± induced by the DMI, we can observe the continuous pure spin current and negative differential conductance (NDC) under the full polarization pL=1 condition and polarization reversal of spin-current in the case of 0< pL<1. These novel phenomena may be useful in the development of molecular spintronics devices.
[en] The secondary electron emission properties of rare-earth-doped molybdenum emitter made by aqueous solution-solid doping method, its microstructure and surface behavior are discussed in this paper. The experimental results show that adding rare-earth oxides La2O3,Y2O3 and Gd2O3 into molybdenum raises the maximum secondary electron yield δm from 1.25 of clean Mo to 2.0-3.24 of doped molybdenum when heated to 1100-1600 deg. C in vacuum. With increasing percentage content of doped rare-earth oxide δm is enhanced in some extent. δm remains nearly constant during 1000 h of test period when cathodes are operated at 1100 deg. C and under primary electron bombardment with bombarding energy of 1000 eV and bombarding power of 300 W/cm2. This demonstrates such cathodes have good anti-bombing insensitivity. A work function of about 2.7-2.8 eV is obtained from Richardson lines. SEM observations and EDS analysis show that distribution of rare-earth oxides in the cathode body is inhomogeneous and tends to aggregate at molybdenum grain boundaries. By AES analysis it is found, that atomic concentrations of La and Y on the surface are about 2.5 times higher than in the bulk for a sintered body and further increase after activation. We believe the rare-earth atoms segregated at the grain boundaries diffuse along the grain boundary during the process of cathode activation. Therefore, the surface of the cathode is covered by a certain amount of rare-earth oxide. As a result, the secondary electron yield is improved
[en] Objective: To evaluate the effects on local radiotherapy and radio-nuclides 89Sr to treat cancer with bone metastasis, analyze the simple radiotherapy treatment and the treatment of side effects of radio- nuclide 89Sr. Methods: 60 patients, who were bone metastasis cancers, divided into 3 groups: local radiotherapy (A group), 6 MV linear accelerator external irradiation dose given 30-60 Gy/2-4 weeks, local radiotherapy and 89Sr treatment (B group), 89Sr treatment (C group), intravenous injection 3-4 mCi. Results: After treatment, B group's bone pain was relieved. B group's primary sites was significant improvement than A and C from bone imaging shown, new pains and metastases sites lower than others. There was no significant difference in toxicity of blood among three groups (P>0.05). Conclusions: Local radiotherapy combined with 89Sr meght be an effective treatment for bone metastasis cancer. It is suggested that the pain relieve effect of local external radiotherapy on single bone metastasis location was remarkable. It is safe and reliable to perform radiotherapy and 89Sr combination treatment for multiple bone metastasis in close proximity. And it has certain effects to carry out 89Sr treatment for whole-body multiple bone metastases. (authors)
[en] Objective: To identify the risk factors of radiation-induced liver disease after three-dimensional conformal radiotherapy (3 DCRT) for primary liver carcinoma in conventional fractions. Methods: Eighty-eight patients with primary, liver carcinoma were treated by 3DCRT to a total dose of 30-66 Gy and 1.8-2.2 Gy per fraction. The relation between radiation-induced liver disease and the possible clinical factors were analyzed, such as the gender, age, pathology, tumor size, tumor site, TACE, portal vein carcinomatous thrombus, hepatic-hilar lymph node, HBV, ascites, curative effect, hepatic cirrhosis, hepatic function, PTV, total dose, mean dose to normal liver and dosimetric parameters (including V5, V10, V15, V20, V25, V30, V35, V40 and V45). Results: Sixteen patients (18.2%) developed radiation-induced liver dis- ease and 9 died. It was found that the age, ascites, HBV, hepatic function, portal vein carcinomatous thrombus, tumor size and PTV were correlated with radiation-induced liver disease. Logistic regression analysis showed that only the HBV and hepatic function were independent factors. Conclusions: As radiation-induced liver disease possesses a very high mortality rate(9/16), when planning three-dimensional conformal radiotherapy for primary liver carcinoma, comprehensive consideration of HBV and hepatic function may lower the incidence of radiation-induced liver disease. (authors)
[en] Graphical abstract: A novel visible-light wavelength matched microspheres assembly of TiO_2 superfine nanorods with a diameter of ∼5 nm was fabricated via a hydrothermal method. The as-prepared rutile TiO_2 microspheres have a uniform diameter of ∼450 nm and show a good light-trapping performance. Dye-sensitized solar cell based on this sample shows a satisfactory energy conversion efficiency of 6.59% and is the highest PCE reported for intrinsic rutile TiO_2. The further optimized DSSC shows a conversion efficiency of 8.3%, though the internal resistance is higher and the dye absorption is lower than that of widely used anatase TiO_2 nanoparticles. - Highlights: • Microsphere assembly of TiO_2 nanorods with a diameter of ∼5 nm was fabricated. • TiO_2 microspheres size is well matched with the visible light wavelength. • TiO_2 microsphere enhances the light-scattering ability. • Rutile TiO_2 microsphere shows an energy conversion efficiency of 6.59%. • The highest PCE reported for intrinsic rutile TiO_2 is obtained. - Abstract: According to the Mie scattering theory, spheres with the size matched with light wavelength are most suitable for light scattering and enhance the light trapping ability. In this paper, a novel visible-light wavelength matched sphere assembly of TiO_2 superfine nanorods was fabricated via a simple one-step hydrothermal method. The morphology and the structure were examined by field emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). The visible subwavelength TiO_2 microsphere resembling an immature chinese chestnut is composed of countless superfine TiO_2 nanorods, the diameter of these building blocks of superfine TiO_2 nanorods is ∼5 nm. The obtained TiO_2 sphere has an average diameter of ca. 450 nm, which matches well with the visible light wavelength and cause the effective light-scattering effect. Furthermore, these TiO_2 superfine nanorods formed V-shaped structure which is usually designed in traditional silicon solar cells. Study show the as-prepared rutile TiO_2 spheres has a good light-trapping property and an excellent photovoltaic performance. Even though the dye absorption is two times lower than that of the widely used anatase TiO_2 nanoparticles, the obtained rutile sample shows a satisfactory energy conversion efficiency of 6.59% and is the highest PCE reported for intrinsic rutile TiO_2. The further optimized DSSC shows a photo to electron conversion efficiency of 8.3%
[en] A novel chiral ionic liquid containing proline moiety was synthesized. It can be used as a highly efficient and recyclable chiral organocatalyst for Michael addition of cyclohexanone with (E)-β-nitroalkenes in methanol at room temperature. The Michael addition affords the corresponding products in satisfactory yields of isolated products ( 78-98%) with high diastereoselectivities and excellent enantioselectivities (up to 98% dr and up to 99% ee). The catalyst can be recycled up to five times without any decrease in yields and stereoselectivities.
[en] Objective: To evaluate the accuracy of image coregistration of FDG PET-CT image and the its impact on radiation treatment planning in non-small cell lung cancer (NSCLC). Methods: Thirteen patients with well-circumscribed NSCLC lesions were examined by in-line PET-CT. The registration accuracy of PET-CT image was measured with two methods-volume and center of geometry (COG). The volume of interest of each lesion was defined separately on PET, CT and fused images (VPET, VCT, VPET+CT). The overlap volume of PET and CT image was calculated from formula: VPET-CT VPET+VCT-VPET+CT. The percentage of VPET-CT on VPET+CT (PPET-CT) was used to assess the fusion accuracy of PET and CT images. The geometric center of gravity (COG) of VPET and VCT was assessed. The COG distance between the PET image and the CT image (DCOG) was measured. The image data were transferred to the radiation treatment planning system. Three plans were made according to different volumes (VPET, VCT, VPET+CT) with the same prescribed dose of 60 Gy. The dose in lung, heart and spinal cord were recorded in plans and compared with one another. Results:The mean of DCOG was (4.95 ± 2.41) mm (1.00-8.68 mm). PPET-CT was 46.7%±19.2%(2.7%-70.4%). Misregistration tended to be more pronounced in the lower lung (DCOG = [4.73 ± 2.50] mm, PPET-CT=52.0%± 23.6%) than in upper lung (DCOG = [5.21 ± 2.51 ] mm, PPET-CT = 40.5% ±11.4%) (P>0.05). The dose to lung (mean lung dose and V20), maximal dose to spinal cord, mean and maximal dose to the heart were higher in plans with VPET+CT than in those with VPET and VCT (P<0.05), but statistical difference was not found among the mean spinal cord doses in the three plans (P =0.05). Conclusions: The registration of lung lesion in PET-CT image is usually accurate. Misregistration may exert on the target volume delineation in radiation treatment planning with PET-CT fused image for non-small cell lung cancer and result in higher dose to normal tissue. More precise measurement and control of the misregistration must be taken into account when fused PET-CT image were used in making radiotherapy planning.(authors)
[en] Objective: To explore the clinical value and effectiveness of strontium chloride (89SrCl2) in the treatment of malignant tumor with multiple bone metastasis. Methods: The 76 cases of malignant tumor with multiple bone metastasis were observed in patients using 89SrCl2 and the pain relief rate as well as the imaging manifestations. Results: Adverse reactions were seen 7 days after the treatment. Blood cells and platelet count are 20% lower than those of before treatment. Blood 30 days after treatment, There was no difference in bolld and the bone marrow 30 days after treatment. The pain relief rate was 71.1% (12 cases complete response, partial response 42 cases) and the total effective rate was 80.3%. Conclusion: The clinical use of 89SrCl2 in patients advanced malignant tumor with multiple bone metastasis can significanthy relieve the symptom of pain and improve their life quality. (authors)
[en] With the help of supercell method, the first-principle calculations were performed for the study of doping crystal Mg1-xAlxB2 and Mg(B1-yCy)2. Analyzing the variations of the charge distribution and the partial densities of states, we found that the compounds with doping Al to MgB2 compound and/or replacing boron by carbon exhibit new covalent bond effects and unexpected electronic properties, related to superconductivity. The study of the density of states indicates that superconductivity decreases with the increase of Al fraction and carbon concentration. There exists a transition of superconductor to non-superconductor with the change of Al doping fraction. The substitution of boron by carbon results in the decrease of the transition temperature since the decrease of the electron concentration and the lattice constant. The theoretical predictions agree with experimental observations.