[en] Graphical abstract: - Highlights: • Adhesion of AlN/metal interfaces mostly depends on lattice mismatch. • Tensile strains in metals are associated with large adhesion strength. • Nucleation of Zr and Ti on AlN proceeds with larger energy decrease than Al and Cu. - Abstract: Devices based on AlN generally require adherent and strong interfaces between AlN and other materials, whereas most metals are known to be nonwetting to AlN and form relatively weak interfaces with AlN. In this study, we selected four representative metals (Al, Cu, Ti, and Zr) to study the adhesion strength of the AlN/metal interfaces. Mathematical models were constructed between the adhesion strength and enthalpy of formation of Al–metal solid solutions, the surface energies of the metals, and the lattice mismatch between the metals and AlN, based on thermodynamic parameters calculated using density functional theory. It appears that the adhesion strength is mainly determined by the lattice mismatch, and is in no linear correlation with either the Al–metal solution's formation enthalpies or the metals’ surface energies. We also investigated the nucleation thermodynamics of the four metals on AlN substrates. It was found that Ti forms the strongest interface with AlN, and has the largest driving force for nucleation on AlN substrates among the four metals.

[en] Objective: To compare the dosimetric, parameters between the use of Tandem and Ring (TR; Nuc1etron#090.617) or Tandem and Ovoid (T0; Nuc1etron#189.730) applicators during three-dimensional (3D) high-dose rate (HDR) brachytherapy (BT) for cervical cancer. Methods: The records of 40 cervical cancer (II_B-IV_A) patients treated with 3D-image-guided HDR-BT were reviewed. Of these 40 patients, 20 were treated with the TO applicator, and 20 with the TR applicator. The D_100% and V_150% of the clinical target volume (CTV) and the D_2cc of organs at risk (OAR) (the rectum, bladder, and small intestine) during 3D-HDR-BT using TO and TR were compared using the independent sample t-test. Results: Overall metrics: CTV volume: 66.04 ± 13.86 cm³(TR) vs. 65.67 ± 15.08 cm³(TO)(P = 0.052); CTV D₁₀₀: 3.71 ± 0.34 Gy (TR) vs. 3.37 ± 0.49 Gy (TO)(P = 0.016); CTV V_150%: 0.54 ± 0.02(TR) vs. 0.56 ± 0.04 (TO)(P = 0.034); rectum D_2cc: 3.38 ± 0.30 Gy (TR) vs. 2.95 ± 0.80 Gy (TO)(P = 0.037); bladder D_2cc: 4.33 ± 0.39 Gy (TR) vs. 2.93 ± 1.27 Gy (TO)(P = 0.00); and small intestine D_2cc: 3.04 ± 1.02 Gy (TR) vs. 3.41 ± 0.57 Gy (TO)(P = 0.171). Conclusions: TR has better CTV coverage than TO during 3D HDR brachytherapy for cervical cancer. In addition, D_2cc of the rectum and bladder were both higher with TR than with TO, though there is no significant dosimetric difference in the small intestine between the two applicators. Therefore, tumor location, extent of invasion, and vaginal conditions should be considered when selecting the suitable applicator for the treatment of cervical cancer. (authors)

[en] Objective: To compare the effective dose deposited in patients between helical tomotherapy (HT) and multi-ISO radiotherapy (M-ISO) in carniospinal irradiation(CSI). Methods: Nine children with craniospinal irradiation were selected. For these patients, new plans were designed with HT and M-ISO centers planning method on the treatment planning system (TPS). The effective dose of the nine patients from 18 treatment plans were calculated, and the difference of the effective dose between HT and M-ISO was compared using paired t-test. Results: The plans designed in two groups were both satisfied all clinical requirements. For the planning target volume (PTV), no statistically significant difference was found in D_95% between two groups (P > 0.05), while D_98%, D_2% and homogeneity index (HI) in HT group were superior to M-ISO group (t = 2.762, 2.413, 4.563, P < 0.05), D_50%, D_mean and CI in M-ISO group were superior to HT group (t = 5.259, 3.685, 7.815, P < 0.05). HT and M-ISO had different advantages in the protection of the OARs. The effective dose of patients in M-ISO group was superior to HT group (t = 5.921, P < 0.05). Conclusions: HT and M-ISO have different advantages in CSI. The low dose area has greater influence on the effective dose in HT group compared to M-ISO group. The low dose area should be concerned while designing the treatment planning for CSI. (authors)

[en] Objective: To investigate the impacts of ring applicator (Nucletron #090.617) reconstruction uncertainties on the radiation dose of computed tomography-guided three-dimensional (3D) brachytherapy for cervical cancer. Methods: Twenty patients with cervical cancer who completed radical treatment were enrolled as subjects. In a treatment planning system, dose distribution was simulated with reconstruction uncertainties of tandem applicator, ring applicator, and both tandem and ring applicators, respectively. Two directions of reconstruction uncertainties were towards the tip (+) and the connector end (-) of the applicator. Reconstruction uncertainties of ± 1 mm, ± 2 mm, and ± 3 mm were simulated. The D₁₀₀, D₉₀, and D₅₀ for clinical target volume (CTV) and D_0.1cc, D_1cc, and D_2cc for the bladder, rectum, and small intestine were evaluated. The effects of applicator reconstruction uncertainties on radiation dose of 3D brachytherapy were analyzed. Results: The tandem applicator had greater impacts on radiation dose than the ring applicator. The dose deviation due to applicator reconstruction uncertainties increased with the increase in volume for CTV parameters but decreased with the increase in volume for parameters of organs at risk. The impacts of applicator reconstruction uncertainties were greatest on the dose to the small intestine. The deviation due to 3 mm reconstruction uncertainty of tandem applicator, ring applicator, and both tandem and ring applicators was 0.90%, 1.62%, and 1.74% for D₉₀ of CTV, 1.33%, 1.53%, and 1.78% for D_2cc of the bladder, 0.89%, 1.85%, and 1.97% for D_2cc of the rectum, and 0.86%, 3.04%, and 3.50% for D_2cc of the small intestine, respectively. Conclusions: Applicator reconstruction uncertainties have certain impacts on the radiation dose of 3D brachytherapy. In order to improve the accuracy of brachytherapy, comprehensive quality control is recommended for applicator reconstruction. (authors)

[en] Cold-rolling emulsion wastewater (CREW) is characterized by high oil content, complex organic components and certain toxicity. By traditional physical and chemical methods, it could not be completely degraded at low cost. In order to optimize treatment process of CREW, a highly effective strain (Pseudomonas fluorescens) was isolated and combined with bioaugmentation technology, biofilm and fluidized bed technology to treat CREW. After 78 days of the system operation, the removal rate of COD and oil reached 94% and 97%. COD and oil content of the effluent were stably below 70mg/L and 4.7mg/L, which met the first order of the national discharge standard (GB8978-1996). The result of high throughput 16SrRNA sequencing showed there were 23 genera of bacteria in the biofilm community of the reactor. This microbial community structure could effectively degrade COD and oil in CREW. At phylum level, γ-proteobacteria, Firmicutes and β-proteobacteria widely existed in carrier and were the main members of pollutant degradation. (paper)

[en] Objective: To simulate and calculate the dosimetric parameters of the GZP ⁶⁰Co source that has been clinically used in high-dose-rate brachytherapy. Methods: The EGSnrc Monte Carlo software was used to simulate and calculate the dosimetric parameters of a well known BEBIG ⁶⁰Co source (Co0.A86). The results were compared with the actual parameters to verify the feasibility of this method. A Monte Carlo model of the GZP ⁶⁰Co source for high-dose-rate brachytherapy was established to simulate and calculate its dosimetric parameters in the same way. Results: For the BEBIG ⁶⁰Co source, the results were well accorded with the standard. The air-kerma strength per unit activity (S_K/A) and dose rate constant (A) deviated from the standard by 0.2% and 1.0%, respectively. The curves of the radial dose function g_L(r) and the anisotropy function F(r, θ) fit well. For the GZP ⁶⁰Co source, the S_K/A and Λ values were calculated as 3.011 × 10^-7 cGycm²h^-1Bq^-1 and 1.118 cGyh^-1U^-1 in channel 1&2 and 3.002 × 10^-7 cGycm²h^-1Bq^-1 and 1.110 cGyh^-1U^-1 in channel 3. The g_L(r), F (r, 0θ), and dose rate per unit air-kerma strength in a liquid water phantom were listed as the American Association of Physicists in Medicine recommended. Conclusions: The results can be used in planning system and quality control for the GZP ⁶⁰Co source. (authors)

[en] The control experimental study on the THz wave parametric oscillator (TPO) output characteristics based on the congruent LiNbO₃ crystal (CLN) and stoichiometric MgO-doped lithium niobate (SLN) crystal is performed. As a nonlinear medium in the aspect of the THz wave output experiments show that the congruent LiNbO₃ crystal is more stable than the SLN crystal. Compared with the CLN crystal SLN showed significant photorefractive effect which adversely the stability of the THz wave output. Experiments indicated that different molar concentration of MgO doped can significantly change the photorefractive properties of SLN crystal. The results showed that with the increase of MgO doping concentration the photorefractive of SLN gradually become weaker and THz wave output stability has the significantly increase. The output stability of mol 5.0% MgO droped SLN crystal has not significantly different with the CLN. In the contrast experiment of TPO with the 160mm cavity length and 65mm crystal length the pump laser threshold of the 5% mol MgO: SLN crystal decreased by 23% than the CLN crystal while the peak THz energy output increased 28%.

[en] Objective: To evaluate the accuracy of image registration based on bony structure (RBS) and grey-scale (RGS) in positioning correction of radiation treatment, and their reliability in clinical application. Methods: Setup errors of anthropomorphic phantom (chest and abdomen, head and neck) were simulated with x-, y-, z-directions.CBCT images were acquired for each simulation and registered with planning CT. using bony structure and grey-scale registration separately. Geometry accuracy of all registration were then obtained and analyzed. Results: The errors of RBS and RGS in x-, y-, z-directions were (-0.65 ±0.22) mm and (-0.70±0.17) mm (P=0.00), (1.02 ±0.27) mm and (0.90±0.20) mm (P=0.00), (1.46 ± 0.53) mm and (1.47 ± 0.47) mm (P=0.54) for head and neck positioning; with (0.82±0.33) mm and (0.79±0.18) mm (P=0.03), (2.45±1.17) mm and (1.61 ±0.84) mm (P=0.00), (1.44 ± 3.25) mm and (0.19 ± 1.11) mm (P=0.00) for chest and abdomen positioning. Conclusions: RGS is more accurate and stable than RBS. The accuracy of image registration is a little better for head and neck than that for chest and abdomen. The algorithms of image registration used in clinical application needs to be tested independently and the systematic error needs to be corrected before applying in different treatment techniques according to their accuracy requirement. (authors)

[en] Vulcanized hydrogenated butadiene-acrylonitrile rubber (HNBR) without the use of vulcanization reagents was cross-linked by γ-ray irradiation. The vulcanization behavior was investigated at the absorbed dose range of 0 ∼ 300 kGy. The micromorphology and dynamic mechanical properties were characterized and analyzed by dynamic mechanical analysis and scanning electron microscope, respectively. The results indicated that the HNBR sample was vulcanized by γ-ray irradiation without vulcanization reagents. With an increase in the absorbed dose, the elastic torque simultaneously increased when the mold filling deformation decreased due to the cross-linked reaction of HNBR. The HNBR sample exhibited excellent mechanical properties and oil resistance when the absorbed dose of 200 ∼ 250 kGy. Compared with the chemical-vulcanized HNBR, the retention rate of tensile strength and the elongation at break of radiation-vulcanized HNBR increased by 24% and 39%, respectively, in air at 150 ℃ for 70 h. Moreover, the compression set of the radiation-vulcanized HNBR (46.20%) was lower than that of chemical-vulcanized HNBR (58.56%) after being immersed in No. 903 oil at 150 ℃ for 24 h. The results prove that radiation vulcanization improves hot-air and hot-oil aging resistance and is, thus, expected to achieve both high performance and long service life. (authors)

[en] Objective: To analyze the relationship between different rectal volume, bladder volume and dose of organs at risk (OARs) in intracavitary brachytherapy for cervical cancer. Methods: A total of 47 patients with cervical cancer were selected. All of them were treated with high dose rate (HDR) intracavitary brachytherapy with a 600 cGy dose for the dosage point. The effects of different volume of rectum bladder and small intestine for corresponding exposure dose under the standard planning were evaluated using a dose-volume histogram (DVH). According to bladder volume, patients were divided into three groups, < 80 cm³ group, 80-120 cm³ group and > 120 cm³ group. And according to rectum volume, patients were divided into > 60 cm³ group and ≤ 60 cm³ group. The relationship between the volume and dosage were analyzed. The ANOVA test and t test were used for analyzing D_{1 cm³}, D_{2 cm³}, D_30% and D_50%. Results: Compared with the group with < 80 cm³ bladder volume, D_30%, D_50% value of bladder in groups with 80-120 cm³ and > 120 cm³ of bladder volume increased (F = 5.074, 5.088, P < 0.05). The difference of D_{1 cm³} and D_{2 cm³} value of the small intestine between 80-120 cm³ and > 120 cm³ bladder volume groups were not statistically significant (P > 0.05). D_{1 cm³} of rectum in groups with ≤ 60 cm³ rectum volume was decreased than that of > 60 cm³ group (t = -2.045, P < 0.05). Conclusions: Keeping an appropriatly full bladder and reducing rectal volume in cervical cancers treated with intracavitary brachytherapy can make the exposure dose of bladder, rectum and small intestine relatively small, and reduce the adverse reactions of radiotherapy. (authors)