In-situ investigation of atmospheric corrosion behavior of bronze under thin electrolyte layers using electrochemical technique

The atmospheric corrosion behavior of bronze under thin electrolyte layer （TEL） with different thicknesses was monitored using cathodic polarization curves, open circuit potential （OCP） and electrochemical impedance spectroscopy （EIS）. Cathodic polarization result indicates that the cathodic limiting current density increases with decreasing the TEL thickness. EIS result shows that the corrosion rate increases with decreasing the TEL thickness at the initial stage because the corrosion is dominated by the cathodic process, whereas after long immersion time, the corrosion degree with the TEL thickness is in the sequence of 150 μm 〉 310 μm〉 10μm ≈ bulk solution 〉 57 μm. The measurements of OCP and EIS present in-situ electrochemical corrosion information and their results are in good agreement with that of physical characterizations.

Tribological behaviors of Fe-Al-Cr-Nb alloyed layer deposited on 45 steel via double glow plasma surface metallurgy technique

Double glow plasma surface metallurgy technique was used to fabricate a Fe?Al?Cr?Nb alloyed layer onto the surface of the 45 steel. The microstructures and composition of th?eA Fl?eCr?Nb alloyed layer were analyzed by scanning electronic microscopy, X-ray diffraction and energy dispersive spectroscopy. The results indicate thatthe 20 μm alloyed layer is homogeneous and compact. The alloyed elements exhibit a gradient distribution along the cross section. Microhardness and nanoindentation tests imply that the surface hardness of the alloyed layer reaches HV 580, which is almost 2.8 times that of the substrate. Compared with the substrate, the alloyed layer has a much smaller displacement and a larger elastic modulus. According to the friction and wear tests at room temperature, the? FeAl?Cr?Nb alloyed layer has lower friction coefficient and less wear mass, implying that the Fe?Al?Cr?Nb alloyed layer can effectively improve the surface hardness and wear resistance of the substrate.

A Laboratory Modeling of the Velocity Field in the Convective Boundary Layer with the Particle Image Velocimetry Technique

Based on the research of the convective boundary layer (CBL) temperature field in a convective tank, this paper studies the characteristics of the CBL velocity field in the convective tank. Aluminium powder (400 orders) is used as a tracer particle in the application of the particle image velocimetry (PIV) technique. The experiment demonstrates: the velocity distribution in the mixed layer clearly possesses the characteristics of CBL thermals; the velocity distribution in the top zone of the mixed layer shows entrainment layer characteristics; the vertical distribution of turbulent characteristic variables is reasonable, which is similar to field observations and other tank results; the error analysis demonstrates the validity of aluminium powder, which implies the reliability of the results.

Numerical simulation of protection range in exploiting the upper protective layer with a bow pseudo-incline technique

The developing processes of stress and deformation fields of a protected layer after mining an upper-protective layer with a bow pseudo-incline technique were simulated to locate the protection region. The pressure relief of the protected layer was analyzed after mining the upper-protective layer. The pressure relief angle along the strike and incline were located according to the roles of protection of the deformation and stress pressure-relief of the protective layer after mining. This results show that the upper-protective layer with the bow pseudo-incline technique have an upper and downside pressure relief angle of 85 and 68 degrees respectively; the distribution of strike pressure relief angles along the pseudo-incline working face is uneven and their values range from 38.3 to 51 degrees. The pressure relief angle of the inclined middle location was the largest. The distribution of the protection region of the upper-protective layer with the bow pseudo-incline teelmique located by practical tests and numerical simulation is essentially consistent, compared with the results obtained by these methods.

Uniform stable conformal convolutional perfectly matched layer for enlarged cell technique conformal finite-difference time-domain method

Based on conformal construction of physical model in a three-dimensional Cartesian grid,an integral-based conformal convolutional perfectly matched layer（CPML） is given for solving the truncation problem of the open port when the enlarged cell technique conformal finite-difference time-domain（ECT-CFDTD） method is used to simulate the wave propagation inside a perfect electric conductor（PEC） waveguide.The algorithm has the same numerical stability as the ECT-CFDTD method.For the long-time propagation problems of an evanescent wave in a waveguide,several numerical simulations are performed to analyze the reflection error by sweeping the constitutive parameters of the integral-based conformal CPML.Our numerical results show that the integral-based conformal CPML can be used to efficiently truncate the open port of the waveguide.

Bacteria Adherence Properties of Nitrided Layer on Ti6Al4V by the Plasma Nitriding Technique

The nitrided layer on Ti6A14V substrate was prepared by the plasma nitriding technique. The sample was characterized by X-ray diffraction （XRD）, glow discharge optical emission spectroscopy （GDOES）, X-ray photoelectron spectroscopy （XPS）, and rough-meter. X- ray diffraction analysis reveals that TiN, Ti2N and Ti phase exist in the nitrided layer subsurface. GDOES analysis shows the thickness of the nitrided layer is about 3 ~tm. XPS analysis shows that there is higher N, lower A1 and lower V in the nitrided layer surface than in the Ti6A14V surface. Rough-meter analysis results show the roughness of the nitrided layer is greater than that of Ti6A14V alloy base. The bacteria adherence property of the nitrided layer on Ti6A14V substrate on the Streptococcus mutans was investigated and compared with that of Ti6A14V alloy by fluorescence microscope. It shows that the nitrided layer inhibits the bacteria adherence.

Asexual Propagation of Sheanut Tree (<i>Vitellaria paradoxa</i>C.F. Gaertn.) Using a Container Layering Technique

In spite of the economic potential of the sheanut tree (Vitellaria paradoxa), its domestication still has not been achieved due to the long juvenile period of seed propagated plants and the absence of a reliable vegetative propagation method. Three experiments were conducted by using a modified container layering technique to investigate the effects of season (rainy and dry season), light treatments (etiolation and natural light) and indole 3-butyric acid (IBA) on root formation in juvenile and mature sheanut trees. The effect of light treatments on the internal conditions such as level of sugars (soluble, insoluble and total sugars) and total free phenols in layered sheanut shoots was also considered. Rooting was generally lower in the mature trees (27.9%) compared to that in juvenile 4 year-old plants (40.9%). Etiolation increased the levels of total sugars and phenols in shoots of 4-year-old plants and mature fruit bearing trees, but this increase did not significantly enhance rooting in both the juvenile and mature sheanut trees. The container layering technique holds promise as a method for the asexual propagation of sheanut planting material. Roots formed using this method looked healthy and were vertically orientated giving layered shoots a better chance at survival.

One-half layer pancreaticojejunostomy with the rear wall of the pancreas reinforced:A valuable anastomosis technique

BACKGROUND Postoperative pancreatic fistula(POPF)is one of the most common and serious complications after pancreaticoduodenectomy(PD).To effectively reduce the incidence of POPF,we designed a new type of pancreaticojejunostomy(PJ),which was termed one-half layer PJ with the rear wall of the pancreas reinforced.AIM To explore the clinical application value of this new technique.METHODS We compared 62 patients who had undergone PD by either the traditional ductto-mucosa anastomoses or the new one-half layer PJ with the rear wall of the pancreas reinforced method at our hospital from May 2015 to September 2019.All 62 patients were operated by the same surgeon experienced in both procedures.We retrospectively analyzed patient characteristics,perioperative outcomes,and surgical results.RESULTS There was no significant difference between the two groups in basic information except the postoperative hospital stays,14.7±5.4 d in the traditional duct-tomucosa anastomoses group and 12.0±4.2 d in the one-half layer PJ group(P=0.042).In terms of postoperative complications,the one-half layer PJ group had a lower rate of POPF than the traditional group.The overall number of cases with POPF was 8(24.2%)in the traditional group and 2(6.9%)in the one-half layer group(P=0.017).Additionally,the rate of grades B and C POPF was lower in the one-half layer group(3.4%)compared with that(12.1%)in the traditional group(P=0.010).One patient died due to hemorrhage caused by severe pancreatic fistula in the traditional group.CONCLUSION One-half layer PJ with the rear wall of the pancreas reinforced is a safe and feasible procedure that can successfully reduce the rate of POPF.It may be a promising technique for PJ after PD.

Anti-Corrosion and Reconstruction of Surface Crystal Plane for Zn Anodes by an Advanced Metal Passivation Technique

For the aqueous Zn-ion battery,dendrite formation,corrosion,and interfacial parasitic reactions are major issues,which greatly inhibits their practical application.How to develop a method of Zn construction or treatment to solve these issues for Zn anodes are still great challenges.Herein,a simple and cheap metal passivation technique is proposed for Zn anodes from a corrosion science perspective.Similar to the metal anticorrosion engineering,the formed interfacial protective layer in a chemical way can sufficiently solve the corrosion issues.Furthermore,the proposed passivity approach can reconstruct Zn surface-preferred crystal planes,exposing more(002)planes and improving surface hydrophilicity,which inhibits the formation of Zn dendrites and hydrogen evolution effectively.As expected,the passivated Zn achieves outstanding cycling life(1914 h)with low voltage polarization(<40 mV).Even at 6 mA cm^(−2) and 3 mA h cm^(−2),it can achieve stable Zn deposition over 460 h.The treated Zn anode coupled with MnO_(2) cathode shows prominently reinforced full batteries service life,making it a potential Zn anode candidate for excellent performance aqueous Zn-ion batteries.The proposed passivation approach provides a guideline for other metal electrodes preparation in various batteries and establishes the connections between corrosion science and batteries.

Unsteady Boundary Layer Flow and Heat Transfer Due to a Stretching Sheet by Quasilinearization Technique

In this paper, the problem of unsteady laminar boundary-layer flow and heat transfer of a viscous income-pressible fluid over stretching sheet is studied numerically. The unsteadiness in the flow and temperature is caused by the time-dependent stretching velocity and surface temperature. A similarity transformation is used to reduce the governing boundary-layer equations to couple higher order non-linear ordinary differential equations. These equations are numerically solved using quasi-linearization technique. The effect of the governing parameters unsteadiness parameter and Prandtl number on velocity and temperature profile is discussed. Besides the numerical results for the local skin friction coefficient and local Nusselt number are presented. The computed results are compared with previously reported work.

岩溶山区坡面一孔多层地下水监测试验及科学意义

钻孔是揭露含水层结构和开展地下水监测的重要载体。在场地地下水监测中,不分层的丛式钻孔存在成本高、代表性不全等缺陷。“一孔多层”分层监测对水头或溶质分布的区分度高,在孔隙和裂隙含水层应用广泛,但岩溶介质因结构复杂,极少有案例研究。文章对丫吉试验场西坡径流小区的一个钻孔(ZK6)进行分层并开展监测。依据钻孔岩芯编录资料、抽水试验以及水化学与温度测孔的结果,判断岩溶发育的特征,确定将ZK6孔划分为四层,实施了钻孔封隔。对四个层位的水文观测发现,四个层位的水位动态对降雨的响应有较大差异。其中,第一层一个水文年中无水和充水状态时长分别占79%和21%,说明该层的岩溶介质处于充水和无水交替,且更多时间处于无水状态;第二层水位响应滞后明显;第三层和第四层水头差异表现出地下水排泄区的水头垂直分布特征。ZK6孔四个层位的水化学存在差异,表明岩溶介质结构的差异不仅影响了水文过程也影响水化学特征。第四层的电导率基本稳定在450μS·cm^(-1),而第二层因表层元素积累和水更新速率慢,电导率是第四层的2倍,第一层电导率的剧烈变化则反映表层岩溶带受到降雨补给影响最为强烈。综合钻孔分层的水文和水化学特征,认为第一至第四层分别代表表层岩溶带、裂隙基质带、上部饱水带和下部饱水带。岩溶山坡的“一孔多层”分层技术难度大,但一旦实现不仅可以认识岩溶垂向分带的水动力机制,也为地下水分层开发利用技术突破提供了可能。

分层应变技术联合左心室压力-应变环对儿童胸部霍奇金淋巴瘤放疗后心肌损伤的评估价值

目的 分析采用分层应变技术和左心室压力-应变环(PSL)对胸部霍奇金淋巴瘤(HL)患儿放疗后心肌损伤的评估价值。方法 抽取2020年1月至2022年12月河南省肿瘤医院接受放疗的胸部HL患儿52例,所有患儿均在放疗前进行PSL及分层应变技术检查,并于放疗后进行心肌标志物与影像学检查,统计儿童放疗后心肌损伤发生情况,并根据结果分为心肌损伤组与非心肌损伤组。比较心肌损伤组与非心肌损伤组患者的PSL检测参数[做功指数(GWI)、整体有用功(GCW)、整体无用功(GWW)、整体做功效率(GWE)]、分层应变技术检测参数[心外膜层收缩期纵向峰值应变(LPS-epi)、中层纵向收缩期峰值应变(LPS-mid)、心内膜层纵向收缩期峰值应变(LPS-endo)],采用点二列相关性分析PSL与分层应变技术检查与胸部HL患儿放疗后心肌损伤的相关性,并绘制受试者工作特征(ROC)曲线,分析分层应变技术联合PSL对患儿放疗后心肌损伤的评估价值。结果 经过检查后发现,52例胸部HL患儿中出现心肌损伤占比61.54%,未出现占比38.46%;心肌损伤组GWI、GCW、GWW与GWE低于非心肌损伤组(P<0.05);心肌损伤组LPS-epi、LPS-mid与LPS-endo高于非心肌损伤组(P<0.05);经点二列相关性分析显示,GWI、GCW、GWW、GWE与胸部HL患儿放疗后心肌损伤呈负相关(r<0,P<0.05),LPS-epi、LPS-mid、LPS-endo与胸部HL患儿放疗后心肌损伤呈正相关(r>0,P<0.05);绘制ROC曲线,结果显示,分层应变技术联合PSL对胸部HL患儿放疗后心肌损伤发生的曲线下面积>0.7,联合具有一定的评估价值。结论 分层应变技术联合PSL在胸部HL患儿放疗后心肌损伤情况中具有重要的临床评估价值,能够有效评估患儿心肌损伤情况,为临床患儿的防治提供依据。

马鞍山长江公铁大桥主航道桥中塔下横梁施工关键技术

马鞍山长江公铁大桥主航道桥Z4号中塔采用空间四肢A形钢-混组合塔,横向两塔肢间设下横梁,下横梁间设3道系梁,纵向两塔肢间不设置横梁。下横梁采用支架法分层浇筑施工。下横梁施工支架采用落地式钢管支架配套模板体系,受力性能满足要求;通过有限元计算比选下横梁混凝土分层浇筑方案并进行优化,采取(5.5+2.5)m分层方案,上、下层混凝土分别分为2块、3块分层分块浇筑;通过低温升、易泵送、高抗裂的C60混凝土研制、下横梁与塔柱倒弧结合面抗裂措施优化、分块间接缝构造形式及施工工艺优化、下横梁与系梁混凝土浇筑施工组织优化、混凝土温度智能化监控、预应力束张拉时机控制等混凝土防裂措施,有效解决了下横梁大体积混凝土易开裂的难题。

从大漆皮料到脱胎造型——福州漆艺在包袋设计上的髹饰技艺研究

大漆材料本身与人类不同历史文化中所蕴含的精神美相互滋养,进而呈现出富有精神内涵的美感。漆器作为古代的奢侈品,如何在现代社会中重新找寻属于自己的一方天地成为当前福州漆艺新的奋斗方向。本文以福州漆艺为切入点,对漆艺在包袋面料和包袋造型上的髹饰技艺进行研究与实践。

Pt/Co/Au多层膜中磁斯格明子的密度调控

磁斯格明子是一种拓扑自旋结构,凭借其尺寸小、结构稳定和驱动电流密度低等特性,有望成为新一代赛道磁存储器件的信息存储单元。在存有磁斯格明子的材料体系中,具有界面Dzyaloshinskii-Moriya Interaction(DMI)的铁磁多层膜可与现代纳米制造工艺兼容,并且这种铁磁多层膜产生的磁斯格明子在室温下可稳定存在,这为基于磁斯格明子研发的电子器件提供了材料基础。然而磁性多层膜中界面DM相互作用、交换相互作用和偶极相互作用等各种作用之间的竞争,导致了磁斯格明子密度的随机变化,降低了磁斯格明子器件的可控性。因此,系统的研究材料参数对磁斯格明子密度的调控具有重要的意义。本文通过改变磁性层Co层的厚度调控了磁性多层膜中磁斯格明子的密度。实验结果表明,随着Co层厚度的增加,磁斯格明子的密度先增加后减少,其中Co层为2.1 nm时磁斯格明子密度最大。理论计算表明,磁性层厚度的变化会引起磁各向异性的转变和内禀属性DM相互作用的改变,进而影响磁斯格明子密度的变化。

包扎及合缝工艺对多层绝热性能的影响

利用静态液氮蒸发量热法测试了4种材料包覆工艺方案下的多层绝热结构低温绝热性能,探究了包扎工艺和合缝工艺耦合作用对多层绝热性能的影响。结果表明:采用贝壳式包扎更有利于绝热性能的提升;对比其它合缝工艺,插接式合缝避免了不同反射层间的干涉,实现了同层等温,因而绝热效果最佳;采用贝壳式包扎、插接式合缝的20反射层多层绝热结构的性能最优,其热流密度为1.840 W/m^(2),表观导热系数为6.699×10^(-5)W/(m·K);采用螺旋式包扎、搭接回折式合缝的20反射层多层绝热结构的性能最差,其热流密度和表观导热系数分别为3.775 W/m^(2)、1.266×10^(-4)W/(m·K)。包扎及合缝工艺对多层绝热性能影响显著,应按实际需求对材料的包覆工艺进行合理有效选择。

基于layer-by-layer技术构建胆碱检测生物传感器酶电极的研究

基于层层累积自组装法将PDDA高分子材料和胆碱氧化酶逐层固定在高分子聚合膜PVS／PDDA修饰的电极表面，制备了电流型胆碱检测生物传感器。利用石英晶体微天平（QCM）分别分析了PDDA和胆碱氧化酶的固定过程，结果表明酶的固定量可以得到有效控制。探讨了自组装膜层数、pH值、温度对传感器电流响应的影响。制备的生物传感器在胆碱浓度为5×10^-7～1×10^-4mol／L的范围内对胆碱有良好的线性响应，响应时间为10s，检出限为5×10^-7mol／L。传感器的稳定性好，30天时的响应值仍保持90％。

纯钨表面等离子Ta合金层耐腐蚀性能研究

利用双层辉光等离子表面合金化技术在纯钨表面制备Ta合金化改性层以改善材料的耐腐蚀性。研究不同温度工艺参数对Ta合金层组织结构及耐腐蚀性能的影响。结果表明:在不同温度工艺参数下均制备出连续致密的Ta合金化改性层,且随温度升高,合金层的厚度增加。合金层主要由纯Ta相组成。Ta合金层的自腐蚀电位高于基材的,而自腐蚀电流密度较低,即Ta合金层更难以发生电化学腐蚀反应且腐蚀速率更低。900℃合金层的耐蚀性能最佳,腐蚀速率降至8.45×10^(-3)g·m^(-2)·h^(-1),表现出优良的耐腐蚀性。

双层软组织缝合封闭技术在下颌骨中早期药物相关性颌骨骨坏死患者手术治疗中的应用

目的:探究双层软组织缝合封闭技术在单纯应用抗骨吸收药物引起的发生在下颌骨的中早期药物相关性颌骨骨坏死(medication-related osteonecrosis of the jaw,MRONJ)患者手术治疗中的临床应用效果。方法:选择2021年10月至2022年9月于北京大学口腔医院四病区经手术治疗的中早期下颌骨MRONJ患者的病历资料进行回顾性分析,收集患者术前基线临床资料,包括原发疾病、伴发疾病、用药方案(药物种类、用药时长)、MRONJ分期、临床症状、影像学表现等,所有患者在手术中行下颌骨边缘切除术去除坏死骨,运用双层软组织缝合封闭技术关闭伤口,术后定期复查随访,评价双层软组织缝合封闭技术的治疗效果及并发症,并对患者进行疼痛评分和功能状态评价。结果:研究共纳入13例患者(女12例,男1例),年龄(66.69±13.14)岁。原发疾病包括骨质疏松7例,肺癌2例,乳腺癌3例,前列腺癌1例;2例伴发糖尿病,2例伴发心血管疾病,1例伴发干燥综合征。9例患者静脉注射唑来膦酸,平均用药时间(37.7±20.0)个月,7例患者同时服用了来曲唑片等其他药物;3例患者应用地舒单抗注射液,平均用药时间(10.3±11.9)个月;5例患者服用阿仑膦酸钠片,平均用药时间(55.20±27.20)个月,2例患者不同程度地服用醋酸泼尼松片或阿卡波糖片。MRONJ 1期4例,2期9例。13例患者均采用双层软组织缝合封闭技术关闭伤口,术后平均随访11.9个月(9~17个月),13例患者皆治愈,无溢脓等并发症发生。患者术前Karnofsky功能状态评分量表(Karnofsky performance status,KPS)评分为(68.46±14.05)分,术后评分为(82.31±15.36)分,差异有统计学意义(P<0.05)。患者术前疼痛评估视觉模拟评分量表(visual analogue scale,VAS)评分为(5.77±0.73)分,术后评分为(0.38±0.51)分,差异有统计学意义(P<0.001)。结论:双层软组织缝合封闭技术在中早期单纯使用抗骨吸收类药物的下颌骨MRONJ患者中可以取得良好的临床治疗效果,可为用药情况更加复杂的MRONJ患者提供临床治疗思路。

Study on Quality Standards of Jianjin Zhuanggu Paste

[Objectives]Some Chinese medicinal materials of Jianjin Zhuanggu Paste were microscopically identified,and several active ingredients were studied by thin-layer identification,which provides reference for further improving the quality standards of hospital preparations.[Methods]The effective components of Jianjin Zhuanggu Paste were qualitatively identified by thin-layer chromatography(TLC).[Results]The microscopic identification of the three Chinese medicinal materials in Jianjin Zhuanggu Paste showed the microscopic characteristics of Radix Codonopsis,Radix Astragali and Radix Notoginseng.TLC identification showed that there were characteristic spots of Radix Codonopsis,Radix Astragali,Radix Rehmanniae Preparata and Radix Notoginseng in Jianjin Zhuanggu Paste.[Conclusions]This study established the quality standard research method of Jianjin Zhuanggu Paste,which further strengthens the safety standards of hospital preparations,and improves the clinical efficacy of drugs,as well as the quality standards of hospital preparations to a certain extent.