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力学性能可调的高氧钛原位电弧增材制造

Transactions of Nonferrous Metals Society of China 2024年第1期34卷 171-183页

作者：李昌远刘长猛鲁涛郭跃岭刘彬北京理工大学机械与车辆学院北京100081 中国运载火箭技术研究院北京宇航系统工程研究所北京100076

通过电弧增材制造原位制备高氧钛,并对高氧钛的成分偏析、显微组织和力学性能进行研究。结果表明,高氧钛试样的显微组织主要呈现为针状α相集束。随着氧含量的增加,试样针状α相逐渐变宽,集束尺寸变大。受氧的强化作用以及晶粒尺寸效应... 详细信息

通过电弧增材制造原位制备高氧钛,并对高氧钛的成分偏析、显微组织和力学性能进行研究。结果表明,高氧钛试样的显微组织主要呈现为针状α相集束。随着氧含量的增加,试样针状α相逐渐变宽,集束尺寸变大。受氧的强化作用以及晶粒尺寸效应共同影响,试样的强度先提高后下降,伸长率显著下降,断裂形式由塑性断裂向解理断裂过渡。当氧含量达到0.37%(质量分数)时,伸长率约为7%,试样抗拉强度超过730 MPa,约为商业纯钛的2倍。

关键词：电弧增材制造纯钛高氧含量显微组织力学性能

Energy Density Dependence of Bonding Characteristics of Selective Laser-Melted Nb–Si-Based Alloy on Titanium Substrate

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Acta Metallurgica Sinica(English Letters) 2018年第5期31卷 477-486页

作者： yue-ling guo Li-Na Jia Bin Kong Yong-Lin Huang Hu Zhang School of Materials Science and Engineering Beihang University

Spherical Nb–20Si–24Ti–2Cr–2Al pre-alloyed powders were processed by selective laser melting（SLM） on Ti6Al4V substrates with different energy densities. A series of single tracks and single layers were produced using different processing parameters, including powder size, laser power, scanning speed and hatch distance. Results showed that the pre-alloyed powders ranging from 45 to 75 lm were more applicable to SLM with less balling tendency, in comparison with those between 75 and 180 lm. The increase in linear energy density（LED） resulted in the decrease in contact angle and the increase in the width of single track as well as its penetration depth into the substrate. Smaller hatch distance leaded to a larger remelted part of the former track and a higher volumetric laser energy density. With a thickness of 75.6 lm, an interfacial intermediate layer, enriched in Ti and depleted in Nb, Si, Cr and Al, was formed between the SLM part and the Ti6Al4V substrate. The mechanisms of the elimination of balling phenomenon by employing a higher LED and the interfacial bonding characteristics between Nb–Si-based alloys via SLM and the Ti6Al4V substrate were discussed.

关键词： Nb-Si alloys Selective laser melting Additive manufacture Bonding character Microstructure

High-temperature oxidation behavior of Nb-Si-based alloy with separate vanadium,tantalum,tungsten and zirconium addition

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Rare Metals 2021年第3期40卷 607-615页

作者： Sheng-Nan Zhang Li-Na Jia yue-ling guo Bin Kong Feng-Xiang Zhang Hu Zhang School of Materials Science and Engineering Beihang UniversityBeijing 100191China

The microstructure and oxidation behavior of directionally solidified(DS) Nb-15 Si-24 Ti-4 Cr-2 Al-2 Hf alloys with separate vanadium,tantalum,tungsten and zirconium additions were investigated by X-ray diffraction(XRD),electron probe microanalyzer(EPMA) equipped with wave-dispersive spectroscopy(WDS),scanning electron microscopy(SEM) and transmission electron microscopy(TEM) equipped with an energy-dispersive spectroscopy(EDS).Results show that the five alloys are all composed of primary(Nb,Ti) solid solution((Nb,Ti)ss)phase and eutectic(Nb,Ti)ss/(Nb,Ti)_(5) S_(3) *** oxidation at 1250℃ for 100 h in air,the surfaces of the five alloys are covered by the oxides of Nb_(2)O_(5),TiNb_(2) O_(7),Ti_(2) Nb10O29,TiO_(2) and amorphous SiO_(2).It is found that the alloying elements of V and W are detrimental for oxidation resistance and the addition of Ta has no obvious *** addition obviously benefits the oxidation resistance at high temperature,by decreasing the weight gain from 242.75 to184.83 mg·cm^(-2).The oxidation mechanism of Nb-Sibased alloys and the effects of different alloying elements on the oxidation resistance of Nb-Si-based alloys were discussed.

关键词： Nb-Si-based alloys Directional solidification Microstructure Oxidation

Microstructure and High-Temperature Oxidation Behavior of Dy-Doped Nb–Si-Based Alloys

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Acta Metallurgica Sinica(English Letters) 2018年第7期31卷 742-752页

作者： yue-ling guo Li-Na Jia Hua-Rui Zhang Bin Kong Yong-Lin Huang Hu Zhang School of Materials Science and Engineering Beihang University

Microstructures and oxidation behaviors of four Dy-doped Nb-Si-based alloys at 1250 ℃ were investigated. The nominal compositions of the four alloys are Nb-15Si-24Ti-4Cr-2Al-2Hf-xDy （at.%）, where x = 0, 0.05, 0.10 and 0.15, respectively. Results showed that the four alloys all consisted of Nbss, αNbsSi3 and γNbsSi3, and the addition of Dy produced no obvious effect on the phase constitution and the microstructures of Nb-Si-based alloys. After oxidation at 1250 ℃ for 58 h, it was found that the addition of Dy accelerated the oxidation rate of Nb-Si-based alloys and caused a larger weight gain, accompanied by the formation of a more porous and less protective oxide scale. The oxides of Nb2O5, Ti2Nb10O29, TiNb2O7, Ti0.4Cr0.3Nb0.302 and glassy SiO2 were formed on Dy-doped Nb-Si-based alloys. The high- temperature oxidation mechanism of Dy-doped Nb-Si-based alloys was discussed.

关键词： Nb-Si alloy Intermetallics Directional solidification - Oxidation - Microstructure

Cone-beam computed tomography noise reduction method based on U-Net with convolutional block attention module in proton therapy

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Nuclear Science and Techniques 2024年第7期35卷 89-100页

作者： Xing-yue Ruan Xiu-Fang Li Meng-Ya guo Mei Chen Ming Lv Rui Li Zhi-ling Chen Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai201800China University of Chinese Academy of Sciences Beijing100049China Shanghai Advanced Research Institute Chinese Academy of SciencesShanghai201210China Department of Radiation Oncology Ruijin HospitalShanghai Jiao Tong University School of MedicineShanghai200025China Shanghai Key Laboratory of Proton therapy Shanghai201801China

Cone-beam computed tomography(CBCT) is mostly used for position verification during the treatment process. However,severe image artifacts in CBCT hinder its direct use in dose calculation and adaptive radiation therapy re-planning for proton therapy. In this study, an improved U-Net neural network named CBAM-U-Net was proposed for CBCT noise reduction in proton therapy, which is a CBCT denoised U-Net network with convolutional block attention modules. The datasets contained 20 groups of head and neck images. The CT images were registered to CBCT images as ground truth. The original CBCT denoised U-Net network, sCTU-Net, was trained for model performance comparison. The synthetic CT(SCT) images generated by CBAM-U-Net and the original sCTU-Net are called CBAM-SCT and U-Net-SCT images, respectively. The HU accuracies of the CT, CBCT, and SCT images were compared using four metrics: mean absolute error(MAE), root mean square error(RMSE), peak signal-to-noise ratio(PSNR), and structure similarity index measure(SSIM). The mean values of the MAE, RMSE, PSNR, and SSIM of CBAM-SCT images were 23.80 HU, 64.63 HU, 52.27 dB, and 0.9919, respectively,which were superior to those of the U-Net-SCT images. To evaluate dosimetric accuracy, the range accuracy was compared for a single-energy proton beam. The γ-index pass rates of a 4 cm × 4 cm scanned field and simple plan were calculated to compare the effects of the noise reduction capabilities of the original U-Net and CBAM-U-Net on the dose calculation results. CBAM-U-Net reduced noise more effectively than sCTU-Net, particularly in high-density tissues. We proposed a CBAM-U-Net model for CBCT noise reduction in proton therapy. Owing to the excellent noise reduction capabilities of CBAM-U-Net, the proposed model provided relatively explicit information regarding patient tissues. Moreover, it maybe be used in dose calculation and adaptive treatment planning in the future.

关键词： Proton therapy Cone-beam CT CBAM-U-Net γ-index

Controlling the Reactivity of IBA-N_(3)by Switching Halogen Salts:Providing a Universal Strategy for Haloazidation of Alkenes

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Chinese Journal of Chemistry 2024年第16期42卷 1839-1845页

作者： Chen-Xi Xia Xin-Lei Sun Jinfeng Zhang yue Ren Yan Yu Kuai Wang ling-guo Meng Key Laboratory of Green and Precise Synthetic Chemistry and Applications Ministry of Education/School of Chemistry and Materials ScienceHuaibeiNormal UniversityHuaibeiAnhui 235000China

Although various routes have been reported for haloazidation,unavoidable problems exist,such as environmentally unfriendly monomer halogen,the need for in situ generation of unstable halogen azides(XN3),applicability to one type of haloazidation and inability to precisely control ***,we developed a universal strategy for haloazidation of alkenes through controlling the reactivity of IBA-N_(3) by switching halogen salts,allowing for the synthesis of a diversity of halogen azide *** studies have shown that by tuning the reactivity of IBA-N_(3) via switching halogen salts,different intermediates can be controllably produced to achieve regioselectivityand chemoselectivity in thehaloazidationof alkenes.

关键词： Haloazidation Alkene IBA-N_(3) Halogen salts Difunctionalization Selectivity Radicals Synthetic methods

Evaluation of the efficacy and safety of endoscopic band ligation in the treatment of bleeding from mild to moderate gastric varices type 1

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World Journal of Gastroenterology 2024年第5期30卷 440-449页

作者： yue Deng Ya Jiang Tong Jiang ling Chen Hai-Jun Mou Bi-Guang Tuo guo-Qing Shi Department of Gastroenterology Digestive Disease HospitalThe Affiliated Hospital of Zunyi Medical UniversityZunyi 563000Guizhou ProvinceChina Department of Gastroenterology Guizhou Hospital of the First Affiliated HospitalSun Yat-sen UniversityGuiyang 550000Guizhou ProvinceChina Department of Gastroenterology Yinjiang Autonomous County People’s HospitalTongren 554300Guizhou ProvinceChina

BACKGROUND According to practice guidelines,endoscopic band ligation(EBL)and endoscopic tissue adhesive injection(TAI)are recommended for treating bleeding from esophagogastric ***,EBL and TAI are known to cause serious complications,such as hemorrhage from dislodged ligature rings caused by EBL and hemorrhage from operation-related ulcers resulting from ***,the optimal therapy for mild to moderate type 1 gastric variceal hemorrhage(GOV1)has not been ***,the aim of this study was to discover an individualized treatment for mild to moderate *** To compare the efficacy,safety and costs of EBL and TAI for the treatment of mild and moderate *** A clinical analysis of the data retrieved from patients with mild or moderate GOV1 gastric varices who were treated under endoscopy was also *** were allocated to an EBL group or an endoscopic TAI *** differences in the incidence of varicose relief,operative time,operation success rate,mortality rate within 6 wk,rebleeding rate,6-wk operation-related ulcer healing rate,complication rate and average operation cost were compared between the two groups of *** The total effective rate of the two treatments was similar,but the efficacy of EBL(66.7%)was markedly better than that of TAI(39.2%)(Pling rate of operation-related ulcers in the EBL group was 80.4%,which was significantly greater than that in the TAI group(35.3%)(P<0.01).The incidence of postoperative complications in the two groups was *** average cost and other related economic factors were g

关键词： Gastric varices Type 1 gastric variceal hemorrhage Endoscopic band ligation Tissue adhesive injection

Enhanced bright green luminescence from GdOF:Ho^(3+) up-conversion phosphor via Yb^(3+) doping

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Journal of Rare Earths 2024年第2期42卷 263-269,I0002页

作者： Linjun Qin yue guo Jing Xu Lixi Wang Qitu Zhang College of Materials Science and Engineering Nanjing Tech UniversityNanjing211816China

In this paper,a series of GdOF-based green phosphors doped with Ho^(3+) and Yb^(3+) ions was prepared by a simple co-precipitation *** crystal structure s and optical prope rties were investigated in *** intensity of the emission of GdOF:Yb^(3+),Ho^(3+) phosphors is enhanced by the effective energy transfer from Yb^(3+) to Ho^(3+),and the optimal luminescence is achieved with the Ho^(3+)doping amount of 0.1 mol%as well as Yb^(3+) doping amount of 5 mol%.Tunable UC emission of samples is achieved by adjusting the doping concentration of Ho^(3+) or Yb^(3+).The purity of the green UC emission is further improved by enhancing the excitation pumping *** addition,logarithmic functions of green,red and nearinfrared radiation intensities were calculated versus logarithmic function of pump power for further study.A possible UC luminescence mechanism between Yb^(3+) and Ho^(3+) is discussed based on powerdependent UC luminescence spectrum and decay *** results suggest that GdOF:Yb^(3+),Ho^(3+)phosphors with bright and high-purity green UC emission have potential applications in the fields of bioimaging,display and illumination.

关键词： Up-conversion GdOF Lanthanide ions Rare earths

Heat transfer and temperature evolution in underground mininginduced overburden fracture and ground fissures: Optimal time window of UAV infrared monitoring

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International Journal of Mining Science and Technology 2024年第1期34卷 31-50页

作者： Yixin Zhao Kangning Zhang Bo Sun Chunwei ling Jihong guo Beijing Key Laboratory for Precise Mining of Intergrown Energy and Resources China University of Mining and Technology-BeijingBeijing 100083China School of Energy&Mining Engineering China University of Mining and Technology-BeijingBeijing 100083China State Key Laboratory of Coal Resources and Safe Mining China University of Mining and Technology-BeijingBeijing 100083China

Heat transfer and temperature evolution in overburden fracture and ground fissures are one of the essential topics for the identification of ground fissures via unmanned aerial vehicle(UAV) infrared imager. In this study, discrete element software UDEC was employed to investigate the overburden fracture field under different mining conditions. Multiphysics software COMSOL were employed to investigate heat transfer and temperature evolution of overburden fracture and ground fissures under the influence of mining condition, fissure depth, fissure width, and month alternation. The UAV infrared field measurements also provided a calibration for numerical simulation. The results showed that for ground fissures connected to underground goaf(Fissure Ⅰ), the temperature difference increased with larger mining height and shallow buried depth. In addition, Fissure Ⅰ located in the boundary of the goaf have a greater temperature difference and is easier to be identified than fissures located above the mining goaf. For ground fissures having no connection to underground goaf(Fissure Ⅱ), the heat transfer is affected by the internal resistance of the overlying strata fracture when the depth of Fissure Ⅱ is greater than10 m, the temperature of Fissure Ⅱ gradually equals to the ground temperature as the fissures’ depth increases, and the fissures are difficult to be identified. The identification effect is most obvious for fissures larger than 16 cm under the same depth. In spring and summer, UAV infrared identification of mining fissures should be carried out during nighttime. This study provides the basis for the optimal time and season for the UAV infrared identification of different types of mining ground fissures.

关键词： Heat transfer Overburden fracture Ground fissures Infrared thermal imaging Unmanned aerial vehicle(UAV) COMSOL simulation