Results 1 - 10 of 14
Results 1 - 10 of 14. Search took: 0.018 seconds
|Sort by: date | relevance|
[en] Objective: To investigate the clinical value of 99Tcm-4,9-diaza-3,3,10,10-tetramethyldodecan-2, 11-dione dioxime (HL91) hypoxia imaging in the treatment of nasopharyngeal carcinoma (NPC). Methods: 99Tcm-HL91 SPECT hypoxia imaging was performed for nasopharyngeal and neck region in 38 NPC patients at 3.5 h after the intravenous injection of 1110 MBq 99Tcm-HL91. Target/nontarget (T/ N) ratio was calculated with semiquantitative analysis. Imaging was performed in 16 patients both pre- and post-treatment, and three dimensional conformal radiotherapy (3DCRT) was taken by adjusting the radiation dose in hypoxic target zone found in imaging. Results: The positive rate for 99Tcm-HL91 hypoxic imaging in NPC was 82%. The sensitivity, specificity and accuracy were 82%, 78% and 87%, respectively. The T/N ratio of nasopharyngeal lesion in 16 patients pre- and post- radiotherapy was 2.21±1.05, 1.29±0.39, respectively with significant difference between them (P<0.001). The hypoxic state of NPC lesions was closely correlated to the response of radiotherapy (r=0.532, P<0.01). The recent effect of 3DCRT was better than conventional therapy with high cure rate and less acute radiation effect. Conclusion: 99Tcm- HL91 hypoxic imaging can monitor the hypoxic state of NPC lesion and also give a guide to 3DCRT, thereby its clinical effects can be improved and the acute radiation side can be reduced. (authors)
[en] Oxide dispersion strengthened (ODS) ferritic steels containing 0.38-0.39 wt% Y2O3 have been produced by mechanical alloying. After thermo-mechanical treatment, the structure of ODS steels includes polygonized extended grains and a great number (to ∼1016-1017 cm-3) of ultrafine complex yttrium oxides ∼2-3 nm in diameter. Irradiation by fast neutrons to 4.5x1026 n/m2 (340 K) and 1.5x1022 n/m2 (77 K) leads to strengthening and plasticity decreasing in ODS alloys. The advantages of ODS ferritic steels in creep resistance and strength against ferritic-martensitic steel 12Cr-2Mo-Nb-B-V and austenitic steel 16Cr-15Ni-3Mo-Ti-V display obviously when creep rate is approximately 10-2 h-1 and fracture time is longer than 1000 h
[en] Objective: To identify pertinent prognostic variables related to adenoid cystic carcinoma (ACC) in the nasal cavity. Methods: A statistic analysis of the clinical results and prognosticators was performed on 38 cases with primary ACC in the nasal cavity. Kaplan-Meier method was used for survival analysis and Log-rank test in comparison, Cox proportional hazard model in multivariate analysis. Results: The 5-, 10- year survival rates were 100% and 88.9% in patients whose lesions disappeared completely after their treatment, whereas 48.0% and 0% in patients with lesion which remained (P<0.01). The 5-, 10- year survival rates were 86.7% and 75.8% in patients with Stage I-II ACC, while they were only 58.6% and 0% in Stage III-IV lesions (P<0.01). The 5-, 10- year survival rates of 51.4% and 25.7% were obtained in patients who received surgical operation, 50.0% and 50.0% in those treated by with radiotherapy. Besides, they were 84.4% and 62.0% by combined therapy (P>0.05). Multivariate analysis revealed that the therapeutic response and clinical stage were independent factors of prognosis. Conclusions: The authors recommend combined therapy for ACC in the nasal cavity. And clinical stage, treatment approach and short-term therapeutic response are identified as ACC predictors
[en] The cross sections for the 63Cu(n,α)60(m+g)Co,65Cu(n,2n)64Cu, and 65Cu(n,p)65Ni reactions have been studied in the neutron energy range of 13.5–14.8 MeV using the activation technique. The neutron beams were produced via the 3H(d,n)4He reaction. The neutron energies of different directions in the measurements were determined beforehand by the method of cross section ratios for the 90Zr(n,2n)89m+gZr and 93Nb(n,2n)92mNb reactions. The results in the present work were discussed and compared with measurement results found in the literatures.
[en] A peculiar first orbit loss type was found apart from the normal ones when we use ORBIT code to simulate fast ion orbits in the EAST tokamak. Fast ion orbits were studied in the presence of toroidal field (TF) ripple and magnetohydrodynamic (MHD) perturbations. We analyzed the properties of the drifted orbits in detail and compared their differences, finding that the combined effects of ripple and magnetic islands are much greater than the effects of either one of them alone. Then we investigated the orbit deviations as a function of pitch angle in different radial positions. The modeling results demonstrate that the loss of trapped particles is mainly caused by the ripple, while MHD perturbation mainly plays an important role in the passing particles. Furthermore we modeled the loss rate using different equilibriums. Results prove that a higher beta can indeed improve the confinement of fast ions, while a little change in the q profile can make the topologies of magnetic islands become quite different and results in quite different total particle losses. (physics of gases, plasmas, and electric discharges)
[en] Theoretical studies on mode propagation and second harmonic generation in periodically poled MgO-doped LiNbO3 on an insulator (PPLNOI) rib waveguide are presented. With a special design, the waveguide can simultaneously support the single-mode propagation of both a pump wave (1550 nm) and a second harmonic wave (775 nm). As a result of the strong confinement and intensive nonlinear effect in the PPLNOI rib waveguide, the calculated results indicate that a second-harmonic generation conversion efficiency of 400%W−1·cm−2 can be achieved at a wavelength of 1550 nm, almost 2.6 times higher than the widely applied reverse proton-exchanged waveguide (150%W−1·cm−2). (fundamental areas of phenomenology(including applications))
[en] We present our extensive research into magnetic anisotropy. We tuned the terrace width of Si(111) substrate by a novel method: varying the direction of heating current and consequently manipulating the magnetic anisotropy of magnetic structures on the stepped substrate by decorating its atomic steps. Laser-induced ultrafast demagnetization of a CoFeB/MgO/CoFeB magnetic tunneling junction was explored by the time-resolved magneto-optical Kerr effect (TR-MOKE) for both the parallel state (P state) and the antiparallel state (AP state) of the magnetizations between two magnetic layers. It was observed that the demagnetization time is shorter and the magnitude of demagnetization is larger in the AP state than those in the P state. These behaviors are attributed to the ultrafast spin transfer between two CoFeB layers via the tunneling of hot electrons through the MgO barrier. Our observation indicates that ultrafast demagnetization can be engineered by the hot electron tunneling current. This opens the door to manipulate the ultrafast spin current in magnetic tunneling junctions. Furthermore, an all-optical TR-MOKE technique provides the flexibility for exploring the nonlinear magnetization dynamics in ferromagnetic materials, especially with metallic materials. (topical review)
[en] Motivated by the urgent demand for the detection of latent fingerprints using fluorescence-based nanotechnology, this work was devoted to developing a simple synthetic approach to obtain positively charged CdTe QDs with enhanced fluorescence and affinity for the improvement of latent fingerprint detection. Through this synthetic method, the positively charged CdTe-COONH3NH3+ QDs were successfully achieved by using hydrazine hydrate as both the surface stabilizer and pH adjuster during the preparation process. In comparison to the negatively charged CdTe-COO- QDs prepared by using sodium hydroxide as the pH adjuster, the CdTe-COONH3NH3+ QDs showed enhanced fluorescence. The effectiveness of CdTe-COO- and CdTe-COONH3NH3+ QDs for detection of latent fingerprints present on a large variety of smooth objects was systematically and comparatively studied. The results indicate that the detection of latent fingerprints by using CdTe-COONH3NH3+ QDs as fluorescent labeling marks was greatly enhanced, and more characteristic finger ridge details were detected and identified due to their enhanced affinity with latent fingerprints, in comparison to the detection by using CdTe-COO- QDs as fluorescent labeling marks. The CdTe-COONH3NH3+ QDs show superior detection capability than the CdTe-COO- QDs, which greatly improves the applicability of CdTe QDs for practical application in latent fingerprint detection.