增材制造钛基金字塔点阵结构对镁/钛双金属复合材料界面强化的优化

采用超声辅助固-液复合铸造的方法,通过在界面处采用增材制造的钛基金字塔型点阵材料制备镁/钛异种双金属复合材料。采用正交法对点阵结构参数进行优化。结果表明,优化后的点阵结构参数为:杆直径(d)1 mm,杆长与杆直径比(l/d)3,上节点和下节点直径与杆直径比(d_(1)/d,d_(2)/d)均为2.5,其中l/dd是影响接头失效强度的最显著因素,最优点阵结构参数下镁/钛双金属接头的失效强度为77.3 MPa。实验结果和有限元分析表明:随着点阵结构长径比的增加,镁/钛双金属接头的失效强度先增加后减小,当长径比为3时,失效强度达到最大。

Effect of HEA/Al composite interlayer on microstructure and mechanical property of Ti/Mg bimetal composite by solid-liquid compound casting

In this study,HEA/AI composite interlayer was used to fabricate Ti/Mg bimetal composites by solidliquid compound casting process.The Al layer was prepared on the surface of TC4 alloy by hot dipping,and the FeCoNiCr HEA layer was prepared by magnetron sputtering onto the Al layer.The influence of the HEA layer thickness and pouring temperature on interface evolution was investigated based on SEM observation and thermodynamic analysis.Results indicate that the sluggish diffusion effect of HEA can effectively inhibit the interfacial diffusion between Al and Mg,which is conducive to the formation of solid solution,especially when the thickness of HEA is 800 nm.With the increase of casting temperature from 720 ℃ to 730 ℃,740℃,and 750 ℃,α-Al(Mg),α-Al(Mg)+Al3Mg2,Al3Mg2+Al12Mg17,and Al12Mg17+δ-Mg are formed at the interface of Ti/Mg bimetal,respectively.When the thickness of the HEA layer is 800 nm and the pouring temperature is 720 ℃,the bonding strength of the Ti/Mg bimetal can reach the maximum of 93.6 MPa.

“新懂趣用”的教学思想

如何提高高等学校专业课的教学质量,一直是高等学校专业课教学面临的难题之一。“新懂趣用”的教学思想,认为在本科专业课的教学过程中,应尽量保证教学内容要让学生耳目一新,教学难度上要保证学生基本听懂,教学方式上要有趣味性,教学目标应以学以致用为准。这四点在整个专业课教学周期内合为一个整体,任何一部分都不可或缺,才能在系统的专业教学过程中达到良好的教学效果。通过将上述教学思想应用于地质学专业野外教学实践,为相关教学研究提供参考借鉴。

倍频视角的宽频地震子波优化

宽频地震处理技术可实现数据频带的有效拓宽,提高地震资料分辨率。作为海洋地震宽频处理的主要手段,鬼波压制对水深和声速等参数较敏感,数据处理结果的频谱形态往往差异较大,给地震资料精细解释造成一定困难。为此,在充分考虑宽频数据各频率成分的能量分布前提下,提出一种倍频视角下的宽频地震子波优化方法。首先,对频率取对数,在倍频程坐标系下构建光滑的振幅谱曲线;然后,将振幅谱曲线转换到普通坐标系下,以零相位重构宽频子波,最终得到一种物理意义清晰的宽频地震子波,简称“倍频子波”。实际应用结果表明,该子波可应用于鬼波压制后的宽频地震数据的子波整形,消除因鬼波压制时参数变化引起的频谱形态差异,提高地震剖面质量。

Microstructures and mechanical properties of TC4/AZ91D bimetal prepared by solid-liquid compound casting combined with Zn/Al composite interlayer

To achieve Ti/Mg bimetallic composite with high strength and metallurgical bonding interface,Al interlayer and Zn/Al composite interlayer were used to prepare TC4/AZ91D bimetal composite with metallurgical bonding interface by solid-liquid compound casting,respectively.Al interlayer was prepared on the surface of TC4 alloy by hot dipping,and Zn/Al composite interlayer was prepared by electroplating process.The results suggested that the phases across the interface were Al Ti andα(Al)+Mg_(21)(Al,Zn)_(17)when Zn/Al composite interlayer was used.When Al interlayer was used as interlayer,Al Mg Ti ternary structure and Al_(12)Mg_(17)+δ-Mg eutectic structure were the main phases at the interface.The shear strength of TC4/AZ91D bimetal with Zn/Al composite interlayer was much higher than that with pure Al interlayer,and the value of the shear strength was increased from 48.5 to 67.4 MPa.Thermodynamic models based on different compositions of the interface were established to explain the microstructure evolution of the interfacial zone.

Design of stable covalent organic frameworks for transport regulation of mass and energy

This feature article discusses the design of stable covalent organic frameworks(COFs) for the transport regulation of protons,electrons, and radicals. Transporting these particles through materials is essential for many applications, and porous materials with high surface area and porosity have become powerful platforms for their development. However, the stability of the holes in the material is crucial for adjusting the transmission performance, which may change significantly when the material is not stable enough, and the structure changes when it is in service in the environment. Various strategies have been adopted to improve the stability of COFs, including introducing strong electron-donating groups into the COFs and introducing irreversible reactions into the COF synthesis process. The transport regulation in stable COFs has been explored, and the structure-function relationship has been established. The prospects and challenges of COFs for the transport regulation of protons, electrons, and radicals have also been discussed. Overall, the breakthroughs in COF field have opened new possibilities for developing advanced materials with improved transport properties. The stable COFs have potential applications in energy storage, catalysis,and sensing. However, further research is needed to understand the transport properties of COFs fully and to optimize their performance for specific applications.

The combination therapy of hyperthermia and chemotherapy regimens for the treatment of non-small cell lung cancer: A meta-analysis

Objective:To evaluate the effectiveness and safety of hyperthermia combined with chemotherapy for non-small cell lung cancer(NSCLC).Methods:All of randomized controlled trials(RCT)about hyperthermia in combination with chemotherapy(versus chemotherapy alone)were collected through Cochrane library,PubMed,EMbase,CBM,CNKI,VIP,Wanfang Database from database inception to October 2019,no limit on language.Two researchers extracted data and assess literature quality separately,and made a meta-analysis by RevMan 5.3 software.32 trials with 2361 patients,1154 in treatment group and 1152 in control group,wereincluded in the review.Results:The results of the Meta-analysis exhibited that compared with chemotherapy alone,hyperthermia combined with chemotherapy could can enhance tumor response rate[RR=1.48,95%CI(1.34,1.63),p<0.01],improve the quality of life[RR=1.67,95%CI(1.46,1,91),p<0.01];one year survival rate[RR=1.43,95%CI(1.22,1.68),p<0.01];reduce the gastrointestinal reactions[RR=0.82,95%CI(0.68,0.98),p<0.05].Meanwhile there was no significant difference in the incidence of severe myelosuppression between the two groups:WBC toxicity[RR=0.74,95%CI(0.48,1.13),p=0.16],Platelet toxicity[RR=1.24,95%CI(0.65,2.39),p=0.52].Conclusion:The results showed that for the treatment of NSCLC,the addition of hyperthermia to chemotherapy can increase the long-term and short-term effects of chemotherapy,improve the quality of life of patients,and did not significantly increase the incidence of myelosuppression.More high quality and large-scale randomized controlled trials are required in the future.

Controlled Synthesis of Proton-Conductive Porous Organic Polymer Gels via Electrostatically Stabilized Colloidal Formation

Porous organic polymers(POPs)have attracted extensive interest due to their structural diversity and predesigned functionality.However,the majority of POPs are synthesized as insoluble and unprocessable powders,which greatly impede their advanced applications because of limited mass transport and inadaptation for device integration.Herein,we report a controlled synthetic strategy of macroscopic POP gels by a cation-stabilized colloidal formation mechanism,which is widely adaptable to a large variety of tetra-/tri-amino build blocks for the synthesis of Tröger’s base-linked POP gels,aerogels,and ionic gels.The POP gels combined the integrated advantages of hierarchically porous structures and tailorable mechanical stiffness,whereas they could load substantial amounts of phosphoric acids and construct unimpeded transport pathways for proton conduction,exhibiting unprecedented proton conductivity at subzero temperatures.Our strategy offers a new solution to the intractable processing issues of POPs toward device applications with cutting-edge performances.

In situ protonation in a locally flexible porous coordination polymer for enhancing proton-carrier loading and proton conductivity

Designing efficient proton-conductive materials is crucial in fuel cells.Yet,it remains a substantial challenge because of the issues in proton mobility,proton-carrier amount,and orientation of proton host materials.Herein,we report an in-situ protonation strategy to produce a locally flexible porous coordination polymer(PCP)to enhance the proton-carrier loading and proton conductivity.The local dipole flipping of the ligand allows effective proton exchange with low activation energy,promoting interpore proton transport through the pore apertures and pore walls.The protonation induces substantial charges to the frameworks and enhances the interaction with proton carriers,thereby increasing the loading of the proton carriers.By this design strategy,the resulting PCP exhibits enhanced phosphoric acid loading and extraordinary proton conductivities under both aqueous and anhydrous conditions compared to its isoreticular analog that features rigidity without proton-exchange capability.Our work provides a new avenue for designing proton-conductive materials that combine structural dynamics with performance merits.

Numerical simulation study on the mold strength of magnetic mold casting based on a coupled electromagnetic-structural method

The properties of the magnetic mold in magnetic mold casting directly determine the quality of the final cast parts.In this study,the magnetic mold properties in magnetic mold casting,were studied utilizing a coupled electromagnetic-structural method through numerical simulation.This study investigated key factors including equivalent stress,the distribution of tensile and compressive stresses,and the area ratio of tensile stress.It compared molds made entirely of magnetic materials with those made partially of magnetic materials.Simulation results indicate that as current increases from 4 A to 8 A,both the initial magnetic mold and the material-replaced magnetic mold initially show an increasing trend in equivalent stress,tensile-compressive stress,and the area ratio of tensile stress,peaking at 6 A before declining.After material replacement,the area ratio of tensile stress at 6 A decreases to 19.84%,representing a reduction of 29.72%.Magnetic molds comprising a combination of magnetic and non-magnetic materials exhibit sufficient strength and a reduced area ratio of tensile stress compared to those made entirely from magnetic materials.This study provides valuable insights for optimizing magnetic mold casting processes and offers practical guidance for advancing the application of magnetic molds.

一种利用低频反鬼波滤波器提升深部地震信号能量的方法

海洋地震勘探中鬼波的存在压制了信号中的低频能量,而地球深部结构主要对应低频信号成分,提升受到鬼波压制的低频成分对深部结构探测具有重要意义。鬼波压制过程的关键参数之一是鬼波与一次反射波的到时差,其精度直接影响鬼波压制的效果。受起伏海面、崎岖海底、反射层深度变化和不均匀体分布等因素的影响,鬼波与一次反射波的到时差常无法准确估计,导致鬼波压制无法取得较好的效果。本文在鬼波与一次反射波到时差估计不准的情况下,从反鬼波滤波器的特性出发,设计不扰动高频、仅提升低频的滤波器,绕开对鬼波的压制,仅致力于对低频信号的能量提升。模型测试结果表明:利用本文方法处理后的波形,在形态上接近于无鬼波干扰的一次反射波形,且地震信号主频越低、拖缆的沉放深度越小,本方法对低频信号的能量提升作用越强。在南海实测深反射地震剖面上的测试应用也取得了较好的效果。

Organic single-crystal light-emitting transistors with external quantum efficiency over 20%

Organic light-emitting transistors(OLETs)have attracted increasing attention because of their potential applications in next-generation displays and high-energy operating devices.However,the simultaneous achievement of high luminescent efficiency and carrier mobility in organic semiconductors remains challenging because the localized excitons are advantageous for light emission,whereas the delocalized carriers are beneficial for efficient charge migration.Herein,we report an organic single crystal of a cyano-substituted styrene derivative with balanced mobility yielding a record-high external quantum efficiency of 20.5%in OLETs.Temperature-dependent I–V curves and electronic structure analyses based on firstprinciples calculations were performed to disclose the underlying mechanism as a band transport,which provides an efficient way to achieve high quantum efficiency in OLETs.

Morlet小波匹配追踪方法的时频原子参数分析

匹配追踪方法是目前时频分辨率最高的时频分析方法.但传统的匹配追踪方法在寻找与信号匹配最佳的时频原子时,需在较大的参数搜索范围内对时频原子参数进行多重循环寻优迭代,计算效率较低.针对匹配追踪算法实现方式,本文主要工作及结论如下:(1)以Morlet小波为时频原子,以频率、相位、时延和尺度为时频原子参数,分析了信号在时频原子上的投影振幅对这四项时频原子参数的灵敏度,结果表明灵敏度顺序为:时延、频率、尺度和相位,据此结论可在算法实现时根据灵敏度顺序调整不同参数寻优迭代时的参数搜索范围,改善算法的计算效率;(2)针对频率、相位和时延参数已知尺度参数变化的时频原子,分析了利用Hilbert变换得到的瞬时参数表征时频原子参数初值的准确度,结果表明准确度顺序为:时延、频率和相位.据此结论可在算法实现时确定参数寻优的优先级顺序,改善算法的计算效率.与连续小波变换、广义S变换等时频分析方法的对比及在地震数据去噪中的应用效果表明匹配追踪方法效果较好.

计算机辅助手术导航在单侧复杂颧骨复合体骨折复位与固定中的应用

目的评价计算机辅助手术导航在单侧复杂颧骨复合体骨折复位与固定中的应用效果。方法回顾分析2013年1月至2017年12月在武汉大学口腔医院口腔颌面外科应用计算机辅助导航技术完成的单侧复杂颧骨复合体骨折复位与固定治疗患者的临床资料。术前拍摄螺旋CT,将数据导入BrainLAB导航系统或AccuNavi-A导航系统工作站设计手术方案,然后将手术方案导入术中导航工作站,辅助完成颧骨复合体骨折的复位与固定。术后1周内拍摄三维CT,测量健侧和患侧的颧骨突度值,并采用配对t检验比较双侧的差异;同时以双侧颧骨突度值的差值评价颧骨复合体骨折的复位情况,差值的绝对值小于2 mm为达到了理想的复位标准。术后常规复查,评价伤口愈合情况、面形和功能恢复程度。结果共纳入45例患者,其中男性39例,女性6例,年龄21~68岁。患者术后健侧和患侧的颧骨突度值分别为(80.78±6.14) mm和(80.85±6.10) mm,双侧比较差异无统计学意义(t=0.362,P=0.719)。患者术后健、患双侧颧骨突度差值的绝对值为 (0.92±0.68) mm。43例骨折达到理想复位程度,另外2例颧骨突度差值的绝对值分别为2.3 mm和2.2 mm。术后所有患者手术切口愈合良好,未出现感染等并发症,外形及功能恢复均满意。结论在单侧复杂颧骨复合体骨折手术中应用计算机辅助手术导航可以有效确保骨折复位的精确性,获得较好的临床效果。

3D打印个性化模型联合数字化外科导板在埋伏牙拔除术临床教学中的应用

埋伏牙拔除术作为口腔颌面外科专业临床训练项目之一,是实习医生必须掌握的一项复杂手术技能。由于埋伏牙一般与邻牙牙根、神经等重要解剖结构关系密切,使用传统手术拔除的方法对术者临床操作要求较高,需要准确判断埋伏牙的位置。而实习医生由于临床经验不足,常发生定位不精确而导致手术时间过长、创伤过大甚至发生邻牙损伤等并发症。因此,在埋伏牙拔除术的教学培训过程中,术前进行充足的模拟训练十分必要。本研究联合运用数字化外科导板和3D打印技术制备仿真教学模型,并以此模型辅助实习医生精确了解埋伏牙的形态、位置和方向,进而决定开窗位置、去骨范围,并最终顺利拔除埋伏牙。其中,数字化外科导板能有效提高实习医生在训练拔除埋伏牙手术过程中的准确性,降低邻牙及附近神经血管损伤的概率。而3D打印个性化模型能直观地模拟埋伏牙的形态及其在牙槽骨中的位置,便于实习医生精准定位埋伏牙,迅速积累临床经验并掌握拔除技巧。该教学模型有助于埋伏牙虚拟拔除手术的训练,其设计符合埋伏牙的临床特征,能有效提高实习医生的临床动手能力,适合推广到医学院校用于临床教学。

Three-dimensional visualization and quantification of microporosity in aluminum castings by X-ray micro-computed tomography

Porosity is a major issue in solidification processing of metallic materials.In this work,wedge die casting experiments were designed to investigate the effect of cooling rate on microporosity in an aluminum alloy A356.Microstructure information including dendrites and porosity were measured and observed by optical microscopy and X-ray micro-computed tomography(XMCT).The effects of cooling rate on secondary dendrite arm spacing(SDAS)and porosity were discussed.The relationship between SDAS and cooling rate was established and validated using a mathematical model.Three-dimensional(3-D)porosity information,including porosity percentage,pore volume,and pore number,was determined by XMCT.With the cooling rate decreasing from a lower to a higher position of the wedge die,the observed pore number decreases,the porosity percentage increases,and the equivalent pore radius increases.Sphericity of the pores was discussed as an empirical criterion to distinguish the types of porosity.For different cooling rates,the larger the equivalent pore radius is,the lower the sphericity of the pores.This research suggests that XMCT is a useful tool to provide critical 3-D porosity information for integrated computational materials engineering(ICME)design and process optimization of solidification products.

Predicting gas and shrinkage porosity in solidification microstructure:A coupled three-dimensional cellular automaton model

Porosity formation during solidification of aluminum-based alloys,due to hydrogen gas and alloy shrinkage,has been a major issue adversely affecting the performance of solidification products such as castings,welds or additively manufactured components.A three-dimensional cellular automaton(CA)model has been developed,for the first time,to couple the predictions of hydrogen-induced gas porosity and shrinkage porosity during solidification microstructure evolution of a binary Al-Si alloy.The CA simulation results are validated under various cooling rates by porosity measurements in an experimental wedge die casting using X-ray micro computed tomography(XMCT)technique.This validated porosity moel provides a critical link in integrated computation materials engineering(ICME)design and manufacturing of solidification products.

Photodegradation of Hexafluoropropylene Oxide Trimer Acid under UV Irradiation

As a novel alternative to traditional perfluoroalkyl substances(PFASs),including perfluorooctanoic acid(PFOA)and perfluorooctane sulfonate(PFOS),hexafluoroproplyene oxide trimer acid(HFPO-TA)has been detected worldwide in surface water.Moreover,recent researches have demonstrated that HFPO-TA has stronger bioaccumulation potential and higher hepatotoxicity than PFOA.To treat these contaminants e.g.PFOA and PFOS,some photochemical techniques by adding exogenous substances had been reported.However,there is still no report for the behavior of HFPO-TA itself under direct UV irradiation.The current study investigated the photo-transformation of HFPO-TA under UV irradiation in aqueous solution.After 72 hr photoreaction,75%degradation ratio and 25%defluorination ratio were achieved under ambient condition.Reducing active species,i.e.,hydrated electrons and active hydrogen atoms,generated from water splitting played dominant roles in degradation of HFPO-TA,which was confirmed by different effects of reaction atmospheres and quenching experiments.A possible degradation pathway was proposed based on the products identification and theoretical calculations.In general,HFPO-TA would be transformed into shorter-chain PFASs,including hexafluoropropylene oxide dimer acid(HFPODA),perfluoropropionic acid(PFA)and trifluoroacetate(TFA).This research provides basic information for HFPO-TA photodegradation process and is essential to develop novel remediation techniques for HFPO-TA and other alternatives with similar structures.

可吸收钉板在上颌骨及全面部骨折中的应用

目的评价可吸收钉板在上颌骨与全面部骨折中的应用。方法选择2011年6月至2018年7月在武汉大学口腔医院口腔颌面创伤与颞下颌关节外科接受治疗的涉及上颌骨骨折的患者244例。全面部骨折的纳入标准是同时包含上颌骨骨折、颧骨颧弓眶骨骨折和下颌骨骨折。所有患者均主动要求使用可吸收钉板系统进行内固定。对其人口统计学信息、治疗情况和随访结果进行回顾性分析。结果 244例患者的上颌骨骨折部位全部使用可吸收钉板进行内固定,其中男145例,女99例;年龄6~73岁,平均35岁;上颌骨Le FortⅠ型骨折36例,Le FortⅡ型骨折111例,Le FortⅢ骨折型97例。涉及额骨骨折3例,鼻骨-眶-筛骨(NOE)复合体骨折42例,上颌骨矢状骨折37例,全面部骨折36例。全面部骨折患者中,颧骨颧弓眶骨、上颌骨、下颌骨同时使用可吸收钉板固定的有14例;仅颧骨颧弓眶骨、上颌骨同时使用可吸收钉板固定的有6例;仅颧骨颧弓眶骨使用可吸收钉板固定的有14例;另外2例患者的情况与上述三种分类均不符合。所有患者术前均有面部畸形,且出现咬合紊乱。复位和修复全面部骨折的方法按照"由简单到复杂"进行序列复位固定的原则。术后并发症情况:3例轻度错[牙合]畸形,1例颧骨部分缺损,1例眼球内陷,4例创伤瘢痕,2例眼睑下睑萎缩,2例颞肌萎缩。结论灵活应用可吸收钉板进行上颌骨及全面部骨折复位固定具有可行性。软组织问题引起的手术后并发症,包括撕裂和不对称,难以避免。

Effects of iron(hydr)oxides on the degradation of diethyl phthalate ester in heterogeneous(photo)-Fenton reactions

This work studied the structural effects of hematite(α-Fe2 O3), 2-line ferrihydrite(HFO) and goethite(α-FeOOH) on diethyl phthalate ester(DEP) degradation. The results showed that the degradation of DEP was faster under 365 nm light irradiation than in the dark in the presence of iron(hydr)oxides. The apparent kinetic rates of DEP degradation followed the order HFO > goethite ≈ hematite in the dark and HFO > hematite > goethite under 365 nm light irradiation. Two pathways governed H2 O2 decomposition efficiency on iron(hydr)oxide surfaces:(1) forming UOH on inherent surface hydroxyl groups(Fe-OH) and(2) producing O2 and H2 O on the surface oxygen vacancies. X-ray photoelectron spectroscopy(XPS) analyses indicated that HFO not only has high Fe-OH content but also has high Vo content, resulting in its low H2 O2 utilization efficiency(η). DEP was degraded through hydrogen abstraction and deesterification, and the major products were(OH)2-DEP, mono-ethyl phthalate(MEP), OH-MEP,and phthalate acid(PA). The study is important in understanding the transformation of phthalate esters in top surface soils and surface waters under ultraviolet light.