[en] Objectives: This study aimed to evaluate the changes in choroidal thickness at different parts in patients with stage IV-V diabetic retinopathy (DR) treated by Panretinal Photocoagulation (PRP) or its combination with anti-vascular endothelial growth factor (VEGF) therapy using optical coherence tomography angiography (OCTA). Methods: Patients with proliferative DR (stage IV-V) diagnosed in Shijiazhuang People’s Hospital between January 2016 to January 2020 were selected and treated with conventional PRP or combined with antiVEGF therapy. OCTA was performed before treatment and one three and six months after treatment to observe and compare subfoveal choroidal thickness (SFCT), perifoveal choroidal thickness at 500 um (M500) and 1500 um (M1500). Results: A total of 76 patients (133 eyes) were included. Six months later, re-examination showed effective treatment in 122 eyes (91.72%) and ineffective treatment in 11 eyes. Before treatment and one week, three months and six months after treatment, the choroidal thickness was observed and compared by OCTA. SFCT, M500 and M1500 increased one week after treatment, were significantly thinner 3 months after treatment than those before treatment, and further decreased six months after treatment. Conclusion: OCTA presents a good evaluation of perifoveal choroidal thickness in patients with proliferative DR. It provides a basis for treatment selection and efficacy determination of proliferative DR. (author)

[en] After the Fukushima Daiichi events, the enhanced accident tolerance fuel became a hot topic. This paper analyses three candidate fuel systems FCM-SiC, U_3Si_2-SiC, and UO_2_+BeO-FeCrAl. Through the analysis shows that they have better performance than UO_2-Zr system during the LOCA and SBO conditions. During the LOCA condition, the cladding’s peak temperature of FCM-SiC system is lower than standard UO_2-Zr system 257K. The amount of hydrogen generated is also decreased due to the stability of FeCrAl and SiC. All fuel systems’s failure time have been put off. The fast failure system is UO_2_+BeO-FeCrAl during SBO condition. It’s still 2000 seconds later than the standard UO_2-Zr system. By the preliminary analysis shows that FCM-SiC is the best one. (author)

[en] We investigated the ablation characteristics of a picosecond free-electron laser and compared its ablation effects on ocular tissues at 5.3 μm and 6.0 μm. The Advanced FEL at Los Alamos, operating in the wavelength range 4-6 μm, was used for this study. The 10-μs macropulse consisted of ∼1000 micropulses, each approximately 15 ps in length and separated from one another by 9.2 ns. The FEL beam was passed through a series of attenuator and focused to a 200-μm spot in the sample with a 150-mm f.l. CaF₂ lens. The energy in each macropulse ranged from 5 to 120 mJ. Five transplantable corneal-scleral buttons preserved in corneal storage media were used for this study. The tissue sample was positioned at the focused FEL beam for the ablation, and then fixed for histologic study. Corneal cuts made at 6.0 μm revealed a well-defined ablation boundary. The measured lateral zone of the tissue damage was 11 ± 2 μm. The integrity of the adjacent tissue was well maintained. By contrast, the ablation boundary of the corneal cuts made at 5.3 μm appeared to be very disruptive. The collagen fiber near the ablation was thermally denatured and lost its organized structure. The lateral dimension of such effect extended out to 220 μm beyond the intended cut into the surrounding tissues. We concluded that a short-pulsed laser operating at 6 μm may be a potentially effective tool for cutting ocular tissues

[en] Purpose: Three-dimensional dose verification can detect errors introduced by the treatment planning system (TPS) or differences between planned and delivered dose distribution during the treatment. The aim of the study is to extend a previous in-house developed three-dimensional dose reconstructed model in homogeneous phantom to situtions in which tissue inhomogeneities are present. Methods: The method was based on the portal grey images from an electronic portal imaging device (EPID) and the relationship between beamlets and grey-scoring voxels at the position of the EPID. The relationship was expressed in the form of grey response matrix that was quantified using thickness-dependence scatter kernels determined by series of experiments. From the portal grey-value distribution information measured by the EPID the two-dimensional incident fluence distribution was reconstructed based on the grey response matrix using a fast iterative algorithm. The accuracy of this approach was verified using a four-field intensity-modulated radiotherapy (IMRT) plan for the treatment of lung cancer in anthopomorphic phantom. Each field had between twenty and twenty-eight segments and was evaluated by comparing the reconstructed dose distribution with the measured dose. Results: The gamma-evaluation method was used with various evaluation criteria of dose difference and distance-to-agreement: 3%/3mm and 2%/2 mm. The dose comparison for all irradiated fields showed a pass rate of 100% with the criterion of 3%/3mm, and a pass rate of higher than 92% with the criterion of 2%/2mm. Conclusion: Our experimental results demonstrate that our method is capable of accurately reconstructing three-dimensional dose distribution in the presence of inhomogeneities. Using the method, the combined planning and treatment delivery process is verified, offing an easy-to-use tool for the verification of complex treatments

[en] Purpose: Quantification of the dosimetric impact of the Elekta IGRT treatment couch in different beam field sizes. Established the relationship of relative dose versus beam angle at different beam field sizes. Methods: Measurements of couch attenuation were performed at gantry angles from 180° to 120°, using a 0.125cc semiflex ionization chamber, isocentrically placed in the center of a homogeneous cylindric sliced RW3 phantom for 6 photon beams. Measurements were performed at six different field sizes (3×3, 5×5, 7×7,10×10, 12×12 and 15×15 cm2). The phantom were positioned at the center of the couche,100 MU were delivered at every gantry angle. The dose difference to the ion chamber was determined. Results: For oblique fields with 6 MV photons at the same gantry angle the attenuation coefficient value from the lagest to the smallest the order is field size 7 cm2,5 cm2,10 cm2,12 cm2,15 cm2 and 3 cm2. The biggest couch attenuation by up to 4.15% at the gantry angle of 140°for the field size of 7 cm2, while for the field size of 3 cm2 the couch attenuated value only 3.5%. The other field size couch attenuation values are between the couch attenuated value of field size of 7 cm2 and 3 cm2 Conclusion: The recommended treatment couch attenuation measured beam field size is 10×10 or 12×12 cm2. When measured using the beam field size 3×3 cm2 the tested value will be lower, while measuerd using the beam field size 7×7 cm2 the tested value will be higer than the recommended beam field size. This should be noted when modeling the treatment couch in the treatment planning system

[en] The Fe-W system is systematically investigated through a combined use of first-principles calculation, cluster expansion, special quasirandom structures, and experiments. It is revealed that the ferromagnetic state of BCC Fe-W solid solution has lower heat of formation than its nonmagnetic state within the entire composition range, and intermetallic λ-Fe₂W and μ-Fe₇W₆ phases are energetically favorable with negative heats of formation. Calculations also show that the Fe-W solid solution has much lower coefficient of thermal expansion than its mechanical mixture, and that the descending sequence of temperature-dependent elastic moduli of each Fe-W solid solution is E > G > B. Moreover, magnetic state should have an important effect on mechanical properties of Fe-W phases, and electronic structures can provide a deeper understanding of various properties of Fe-W. The derived results agree well with experimental observations, and can clarify two experimental controversies regarding structural stability and magnetic property of Fe-W phases in the literature

[en] An activity-directed fractionation and purification process was used to isolate the Antibacterial compounds from Evernia divaricata (L.) Ach. Six lichen substances were obtained from the active petroleum ether and ethyl acetate fractions. Antibacterial activity assay showed that (+)-(12R)-Usnic acid and Divaric acid strongly inhibited bacterial growth of Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. However, four other compounds of Atranorin (1), 2,4-Di-O-methyldivaric acid, Divaricatinic acid and 2-0-Methylnordivaricatic acid had no apparent antibacterial activities against the four bacteria. Compounds 3, 4, 5 and 6 are reported here for the first time from E. divaricata (L.) Ach. Furthermore, this is also the first time to report Divaric acid exhibits strong anti-bacterial properties. (author)

[en] We show, using an atomistic model with a Stillinger-Weber potential (SWP), that in the absence of reconstruction, the basic assumption of the Peierls-Nabarro (PN) model that the dislocation core is spread within the glide plane is verified for silicon. The Peierls stress (PS) obtained from the two models are in quantitative agreement (∼0.3μ), when restoring forces obtained from first principles generalized stacking-fault energy surfaces are used in the PN model [B. Joos, Q. Ren, and M. S. Duesbery, Phys. Rev. B 50, 5890 (1994)]. The PS was found to be isotropic in the glide plane. Within the SWP model no evidence of dissociation in the shuffle dislocations is found but glide sets do separate into two partials

[en] The extension of the EFIT equilibrium reconstruction code to fine spatial-grid resolutions is discussed. The residue in the force-balance relation of the Grad-Shafranov (G-S) equation and the convergence property of these fine spatial-grid EFIT equilibria are studied in detail. The results suggest that fine spatial-grid equilibria generally better satisfy the force-balance constraint described by the G-S equation. Finer spatial-grid equilibria have typically smaller average error in satisfying the force-balance equation than coarse-grid equilibria and those extrapolated from coarse-grid results. Analysis of the equilibrium iteration algorithm employed in EFIT reveals that the iteration process is related to the spatial feedback stabilization of the plasma with flux control at various specified locations. Thus, for a converged equilibrium, axisymmetric stability is generally expected with feedback. The iteration error decreases self-similarly in the final stage of the iteration process and is related to the least stable axisymmetric mode in the feedback-stabilized equilibrium.

[en] A new plasma oxynitrocarburizing process in an air and gasoline atmosphere was developed. The influences of the atmosphere with different ratios of gasoline/air on the microstructure, surface hardness, and phase composition of 40Cr steel were characterized using optical microscope, scanning electron microscope (SEM), microhardness tester, and X-ray diffractometer (XRD), respectively. The experimental results showed that the plasma oxynitrocarburized layer was composed of bright layer and diffusion layer. It was found that the thickness, hardness, and Fe₃N concentration of the plasma oxynitrocarburized layer increased with the increment of ratio of gasoline/air