In vitro and in vivo evaluations of Mg-Zn-Gd alloy membrane on guided bone regeneration for rabbit calvarial defect

To develop a biodegradable membrane with guided bone regeneration(GBR),a Mg-2.0Zn-1.0Gd alloy(wt.%,MZG)membrane with Ca-P coating was designed and fabricated in this study.The microstructure,hydrophilicity,in vitro degradation,cytotoxicity,antibacterial effect and in vivo regenerative performance for the membrane with and without Ca-P coating were evaluated.After coating,the membrane exhibited an enhance hydrophilicity and corrosion resistance,showed good in vitro cytocompatibility upon MC3T3E-1 cells,and exhibited excellent antibacterial effect against E.coli,Staphylococcus epidermis and Staphylococcus aureus,simultaneously.In vivo experiment using the rabbit calvarial defect model confirmed that Ca-P coated MZG membrane underwent progressive degradation without inflammatory reaction and significantly improved the new bone formation at both 1.5 and 3 months after the surgery.All the results strongly indicate that MZG with Ca-P coating have great potential for clinical application as GBR membranes.

Progress of Palladium Alloy Membranes in Hydrogen Energy

Palladium and palladium alloy membranes have attracted wide attention in hydrogen permeation areas for their excellent permeability, perm -selectivity and thermal stability. This paper review the principle of hydrogen permeation, type of alloys and the fabrication methods. At last, the progress and achievements on palladium alloy membranes by Northwest Institute for Non-Ferrous Metal Research are emphasized.

Preparation Methods and Properties of PdCu Alloy Membrane for Hydrogen Transition

Pd and Pd alloy membranes are of increasing interest for hydrogen separation and purification due to their good thermal stability, high permeability and perfect selectivity. PdCu alloy (60wt% Pd) membranes have similar hydrogen permeability compared with PdAg alloy; meanwhile, it is cheaper than PdAg alloy. Furthermore, it has been reported that PdCu membrane has better resistance to poisoning and deactivation by H 2 S impurity. This paper reviews the properties and manufacturing methods of PdCu alloy membrane, finally, introduced some achievement made by us on PdCu alloy membrane.

Analysis of H_2S Tolerance of Pd-Cu Alloy Hydrogen Separation Membranes

The presence of a limited amount of H2S in H2-rich feed adversely affects the Pd-Cu membrane permeation performance due to the sulphidization of the membrane surface. A theoretical model was proposed to predict the S-tolerant performance of the Pd-Cu membranes in presence of H2S under the industrial water-gas-shift(WGS) reaction conditions. The ideas of surface coverage and competitive adsorption thermodynamics of H2S and H2 on Pd-Cu surface were introduced in the model. The surface sulphidization of the Pd-Cu membranes mainly depended on the pressure ratio of H2S to H2, temperature and S-adsorbed surface coverage, i.e., the occurrence of sulphidization on the surface was not directly related with the bulk compositions and structures [body centered cubic and face centered cubic(bcc or fcc)] of Pd-Cu alloy membranes because of the surface segregation phenomena. The resulting equilibrium equations for the H2S adsorption/sulphidization reactions were solved to calculate the pressure ratio of H2S to H2 over a wide range of temperatures. A validation of the model was performed through a comparison between lots of literature data and the model calculations over a rather broad range of operating conditions. An extremely good agreement was obtained in the different cases, and thus, the model can serve to guide the development of S-resistant Pd alloy membrane materials for hydrogen separation.

Electrochemical Study of Lincomycin on Au-PtNPs/nanoPAN/ Chitosan Nanocomposite Membrane and Its Determination in Injections

The Au-Pt alloy nanoparticles（Au-PtNPs） were electrochemically deposited on the surface of polyaniline nanotube（nanoPAN） and chitosan（CS） modified glassy carbon electrode（GCE）. The electrochemical behavior of lincomycin at Au-PtNPs/nanoPAN/CS modified GCE was investigated by cyclic voltammetry, linear sweep voltammetry and chronocoulometry. Cyclic voltammetric experiments show that lincomycin at the nanocomposite membrane modified electrode exhibited a pair of quasi-reversible redox peaks in pH=6.0 PBS. The membrane could accelerate the electron transfer of lincomycin on the electrode and significantly enhance the peak current. In a range of 3.0-100.0 mg/L, the reductive peak current of lincomycin at 0.42 V was linearly related to its concentration and the linear regression equation was ip,c=0.2703ρ-0.0042（ip, c： μA; ρ： mg/L; r=0.998, n=7） with a detection limit of 1.0 mg/L（S/N =3）. Compared with other methods, this method exhibited many advantages such as high sensitivity, selectivity, wide linear range and low detection limit. The method was used to determine the content of lincomycin in injections commercially available with satisfactory results. Some electrochemical parameters involved in the redox reaction of lincomycin, such as parameter of kinetic ha, standard rate constant ks and the number of H^＋, were also calculated.

Large-scale and high-quality III-nitride membranes through microcavity-assisted crack propagation by engineering tensile-stressed Ni layers

Epitaxially grown III-nitride alloys are tightly bonded materials with mixed covalent-ionic bonds.This tight bonding presents tremendous challenges in developing III-nitride membranes,even though semiconductor membranes can provide numerous advantages by removing thick,inflexible,and costly substrates.Herein,cavities with various sizes were introduced by overgrowing target layers,such as undoped GaN and green LEDs,on nanoporous templates prepared by electrochemical etching of n-type GaN.The large primary interfacial toughness was effectively reduced according to the design of the cavity density,and the overgrown target layers were then conveniently exfoliated by engineering tensile-stressed Ni layers.The resulting III-nitride membranes maintained high crystal quality even after exfoliation due to the use of GaN-based nanoporous templates with the same lattice constant.The microcavity-assisted crack propagation process developed for the current III-nitride membranes forms a universal process for developing various kinds of large-scale and high-quality semiconductor membranes.

Palladium-based Membrane Applications for Hydrogen Purification

It describes the purification of hydrogen isotopes, separation with the preparation of palladium-based membrane's technology, types, application, advantages and disadvantages of palladium in this article. Due to excellent comprehensive properties palladium composite membrane will become the future direction of development. At the same time it will develop preparation methods of the membrane support body with high mechanical strength and heat resistance and low-cost and palladium-based membrane. Also it will explore high service life and high transmittance of novel composite membrane.

Fabrication of anodized aluminum oxide membrane with nanometer pores

The pure aluminum and Al Mg Mn alloy were anodized in 4%, 10% and 18.5% phosphoric acid solution, respectively. As for pure Al, the maximum thickness of anodized aluminum oxide (AAO) membrane, 216 nm, is obtained by being anodized in 4% solution. Its average pore diameter is around 70 nm, and pore density exceeds 10 10 /cm 2. Under the same technology condition, the membrane thickness decreases with increment of electrolyte content. TEM images show that element Mg or Mn added into aluminum alloy can damage the integration of AAO membrane. During anodizing of aluminum, the formed oxide layer is amorphous. After being annealed at 600 ℃ for 24 h, it is still amorphous. However, when membrane is annealed at 930 ℃, the amorphous oxide begins to transform to γ Al 2O 3 .

ETFE膜在怀柔科学城城市客厅A地块项目中的应用

ETFE膜因其良好的透视和遮阳功能,能够有效避免阳光照射进玻璃幕墙而导致的室内温度过高,但其施工经验尚有不足。研究结合怀柔科学城城市客厅A地块项目,充分考虑了施工技术和施工组织管理的重难点,详细介绍了ETFE膜的施工全过程,保证了施工质量,丰富了施工经验。

氮气流量对VNbMoTaWN_(x)薄膜作为PEMFC不锈钢双极板改性层性能的影响

目的降低SS316L表面的接触电阻,提高耐腐蚀性能。方法采用非平衡场磁控溅射离子镀技术在SS316L不锈钢表面制备VNbMoTaW和不同氮气流量的VNbMoTaWN_(x)薄膜。使用场发射扫描电镜、XRD衍射仪、XPS光电子能谱仪、电化学工作站、接触电阻测试装置,研究了改性涂层的组成和结构对接触电阻和耐腐蚀性能的影响。结果扫描电子显微镜结果表明,所有薄膜表面致密且连续、与基体结合良好。随着氮气流量的增加,氮化物相逐渐增多、柱状晶结构减少、薄膜更加致密紧凑。XRD结果表明,未通氮气的高熵合金薄膜具有高熵合金体心立方结构,并沿(110)晶面方向生长。随着氮气流量的增加,氮化物相逐渐增多,薄膜晶体结构开始从体心立方结构转变为面心立方结构。结合XPS分析结果可知,VNbMoTaWN_(x)薄膜表面主要由金属氮化物和少量高熵合金BCC相组成,并且随着氮气流量的增加,金属氮化物相逐渐增多。与单层VNbMoTaW薄膜相比,VNbMoTaWN_(x)薄膜具有更好的耐腐蚀性和导电性能。氮流量为12mL/min的高熵合金氮化物薄膜具有最优异的综合性能。表面改性后的薄膜接触电阻大幅度降低,在1.4MPa的压力下,与碳纸的接触电阻仅为12.2 mΩ·cm^(2),接近美国能源部(DOE)的技术目标。由动电位极化曲线测得VNbMoTaWN_(x)-12mL/min在模拟PEMFC阴极环境下的腐蚀电流密度为0.040μA/cm^(2),与SS316L基体相比,薄膜的耐腐蚀性得到了很大提升。在0.6 V恒电位模拟阴极环境下,VNbMoTaWN_(x)-12 mL/min的电流密度稳定在1.01μA/cm^(2),接近美国能源部1μA/cm^(2)的目标。结论VNbMoTaW和不同氮气流量的VNbMoTaWN_(x)薄膜能显著提高SS316L基体的耐腐蚀性和导电性能。

PEMFC铝合金双极板表面改性研究现状与发展

质子交换膜燃料电池(Proton Exchange Membrane Fuel Cell,PEMFC)作为第五代燃料电池,是最具发展前景的新能源电池,其中双极板作为PEMFC的核心元件,不仅能将单一电池链接起来形成电池堆,起到支撑作用,还具有提供气体流道、隔绝阴阳极两端等作用,对燃料电池工作性能、寿命起到关键作用。其中铝合金作为一种具有良好导电性能、成本低、轻质的材料,在PEMFC双极板材料方面应用潜力巨大。但铝合金双极板耐腐性不佳,在PEMFC工作环境下极易被腐蚀,且其表面生成的钝化膜,增大了电池的接触电阻,从而对电池性能和寿命产生不利影响,而通过铝合金表面改性是解决该问题的主流方法。首先概述了PEMFC原理、双极板材料类型及内部环境,然后阐述了PEMFC中铝合金双极板的服役问题,并对近年来铝合金双极板的表面改性进行分类。重点概括了铝合金表面金属及其化合物涂层(贵金属、金属氮/碳化物、镍磷金属涂层)与非金属涂层(碳基涂层、高分子聚合物涂层)的结构设计、成分优化、服役性能特点。分析结果表明,选用低成本、具有良好耐蚀性和导电性的金属惨杂的无定型碳、金属碳/氮化物涂层,能降低双极板生产成本,提高双极板工作性能,并对涂层设计出多层复合涂层,能打断涂层中的细长针孔缺陷,提高涂层的完整性和致密性。在铝合金表面进行改性研究,以提高其耐蚀性、导电性及服役稳定性,对推动铝合金双极板在PEMFC电堆中的应用至关重要。

High-loading Pt-alloy catalysts for boosted oxygen reduction reaction performance

To improve performance of membrane electrode assembly(MEA)at large current density region,efficient mass transfer at the cathode is desired,for which a feasible strategy is to lower catalyst layer thickness by constructing high loading Pt-alloy catalysts on carbon.But the high loading may induce unwanted par-ticle aggregation.In this work,H-PtNi/C with 33%(mass)Pt loading on carbon and monodisperse distri-bution of 3.55 nm PtNi nanoparticles,was prepared by a bimodal-pore route.In electrocatalytic oxygen reduction reaction(ORR),H-PtNi/C displays an activity inferior to the low Pt loading catalyst L-PtNi/C(13.3%(mass))in the half-cell.While in H_(2)-0_(2) MEA,H-PtNi/C delivers the peak power density of 1.51 W·cm^(-2) and the mass transfer limiting current density of 4.4 A·cm^(-2),being 21%and 16%higher than those of L-PtNi/C(1.25 W·cm^(-2),3.8 A·cm^(-2))respectively,which can be ascribed to enhanced mass trans-fer brought by the thinner catalyst layer in the former.In addition,the same method can be used to pre-pare PtFe alloy catalyst with a high-Pt loading of 36%(mass).This work may lead to a range of catalyst materials for the large current density applications,such as fuel cell vehicles.

Nickel boride alloys as catalysts for successive hydrogen generation from sodium borohydride solution

Nickel boride alloys,Ni-B,were prepared using chemical reduction method by the reaction of metal chloride with sodium borohydride,and heat-treated at various temperatures. The structures of the as-prepared alloys were studied using X-ray diffractometry(XRD),scanning electronic microscopy(SEM) and nitrogen adsorption-desorption analysis. When being adopted as the catalysts for successive hydrogen generation from sodium borohydride solution,the Ni-B alloy treated at 90 ℃ achieves a maximum hydrogen generation rate of 15.4 L/(min·g),and an average hydrogen generation rate of 13.6 L/min,which can give successive hydrogen supply to a 2.2 kW PEMFC at a hydrogen utilization of 100%.

氢分离非钯合金膜表面处理研究进展

镀有Pd层的氢分离纯化用5B族金属膜具有较高的氢选择性和渗透率,但Pd与基底在高温下易发生热扩散,致使氢的解离效率变差,影响合金膜在氢分离时的连续性和稳定性。目前,在合金膜与Pd之间添加中间层或在合金膜表面直接使用非Pd催化材料是防止氢分离合金膜因金属间扩散而失效的主要方法。介绍了金属催化氢解离与合金膜渗氢机理,并从中间层材料、非Pd催化材料及影响这2种材料效果的内外因素等方面综述了近年来在氢分离合金膜表面处理方面的研究进展。中间层材料的类型以金属化合物为主,还包括氧化物及稀土金属Y,针对这些材料防金属间扩散的效果采用高温下渗氢稳定时间和渗透率进行评价分析;非Pd催化材料主要分为金属碳化物和钒氧化物2类,重点分析了材料的解离效率和通用性,其解离效率与晶体结构和实验温度有关。在通用性方面,氧化物能够与不同基底合金结合,并获得较高的氢渗透率,表现出更好的适应性。影响中间层和非Pd催化材料发挥效用的因素主要包括材料内在因素和工艺外部因素,分析了涂层结构和厚度的材料因素,举例说明了制备工艺和制备参数选择等外部因素对材料发挥效用的影响。最后指出了现有涂层研究中,加入中间层材料或直接使用非Pd催化材料时的不足及相应的改进措施,并对氢分离5B族合金膜表面处理的未来发展进行了展望。

氮掺杂PtCo/C合金催化剂的研究

通过调节氮原子在商业化PtCo/C中的含量来调整催化剂的活性和稳定性,最终使催化剂的质量比活性(MA)提升为改性前的2倍,半波电势由0.90 V增加到0.93 V,并且在0.6~1.0 V之间进行5000次循环之后,半波电势下降幅度由原来的66 mV降低到26 mV,表现出优异的氧还原反应活性和出色的循环稳定性.活性的提升主要归因于氮与铂的结合降低了对含氧中间体的吸附结合能,提高了氧还原反应(ORR)过程中羟基的脱附速率.耐久性的提高表明Pt—N键的存在使催化剂不容易在循环过程中溶解,有助于合金催化剂在碳载体上的稳定.

PtMo合金催化剂氧还原反应催化性能研究

采用乙二醇还原法和后续的热处理工艺制备了Pt-Mo合金催化剂。使用透射电子显微镜、X射线衍射、电感耦合等离子体发射光谱、X射线光电子能谱等方法对样品进行了形貌、结构和组分的表征。通过电化学测试方法,探究了不同催化剂的电催化活性和稳定性。结果表明:合适的热处理温度不仅提高了Pt-Mo纳米颗粒的合金化程度,而且改变了催化剂颗粒表面的电子结构和成分。所以,经过400℃热处理的PtMo/C-400催化剂表现出较好的氧还原性能,其电催化活性和稳定性均与商业J01-Pt/C催化剂相当。

电解质对钛合金微弧氧化放电方式和耐磨性能的影响

目的通过比较添加微量磷酸盐对放电方式的影响,表征各膜层的微观结构与成分组成,研究分析放电方式差异对膜层耐磨性能的影响。方法在3组电解液中分别进行TC4钛合金微弧氧化,以磨损率为指标判定每组的最优配比。通过扫描电子显微镜(SEM)观察膜层表面与截面微观形貌。使用X射线能量色散谱仪(EDS)分析膜层表面和磨损区域的元素分布情况。使用X射线衍射仪(XRD)表征膜层物相结构组成,通过维氏显微硬度计测量膜层的硬度,使用摩擦磨损试验机进行膜层摩擦学性能测试,并通过三维形貌仪分析磨痕轮廓。结果在铝酸盐电解液中添加磷酸盐电解质后会增强A、C型放电,减弱B型放电,使制得膜层的缺陷(微孔与微裂纹)明显增多,产生了较厚的疏松层,并且随着电解液中磷酸根离子的增多,放电方式进一步受影响,膜层磨损率也大幅增加。而不添加磷酸盐的20 g/L铝酸盐浓度制备的钛合金微弧氧化膜层在15 N高载荷滑动干摩擦下的摩擦系数为0.6~0.7,磨痕窄且浅,磨损率仅为基体的7.22%。结论磷酸盐电解质极易引起杂质放电,导致微弧氧化反应时B型放电显著减弱,A、C型放电大幅增加,导致膜层致密性显著降低,严重降低了微弧氧化膜层的耐磨性能。20 g/L铝酸盐电解液制备的钛合金微弧氧化膜层缺陷少、硬度高、厚度大,显著改善了高载荷下钛合金的耐磨性能。

Study on repairing canine mandibular defect with porous Mg-Sr alloy combined with Mg-Sr alloy membrane

To discuss the feasibility of the application of porous Mg-Sr alloy combined with Mg-Sr alloy membrane in the repair of mandibular defects in dogs.The second and third mandibular premolars on both sides were extracted from six dogs.The model of mandible buccal fenestration bone defects were prepared after the sockets healed.Twelve bone defects were randomly divided into groups A and B,then Mg-Sr alloy was implanted in bone defects of group A and covered by Mg-Sr alloy membrane while Mg-Sr alloy was implanted in bone defects of group B and covered by mineralized collagen membrane.Bone defects observed on cone beam computed tomographic images and comparing the gray value of the two groups after 4,8 and 12 weeks.After 12 weeks,the healing of bone defects were evaluated by gross observation,X-ray microscopes and histological observation of hard tissue.Bone defects in each group were repaired.At 8 and 12 weeks,the gray value of group A was higher than that of group B(P<0.05).At 12 weeks,the bone volume fraction of group A was higher than that of group B(P<0.05).The newly woven bone in group A is thick and arranged staggered,which was better than that of group B.Porous Mg-Sr alloy combined with Mg-Sr alloy membrane could further promote the repair of mandibular defects,and obtain good osteogenic effect.

硅酸盐体系中的钨酸钠含量对ZM5镁合金微弧氧化膜层的影响

研究硅酸盐电解液体系中的钨酸钠含量对ZM5镁合金微弧氧化膜层结构和性能的影响。使用扫描电子显微镜、EDS能谱仪、X射线衍射仪、电化学工作站分别对ZM5镁合金微弧氧化膜层的微观形貌、元素组成、晶相结构、电化学性能进行测试分析,使用膜层测厚仪、粗糙度检测仪、维氏硬度仪、游标卡尺、分析天平对不同含量钨酸钠处理后的膜层厚度、粗糙度、显微硬度、外延生长率、质量增重进行测试。结果表明,膜层微观形貌上有微孔和微裂纹,膜层元素组成为Mg、O、Si、F、Na、W、K,膜层相结构组成为MgO、MgF_(2)和K_(2)MgF_(4)。随着钨酸钠含量的增加,膜层外观由白色变为灰色,膜层厚度无明显规律为(20~26)μm,膜层粗糙度增加,外延生长率不变约为70%,膜层致密度和显微硬度增加,W元素含量先增加后减少,陶瓷相结构中MgO的比例降低而MgF_(2)的比例增大,耐腐蚀性能先增加后减小,当钨酸钠含量为3 g/L时,膜层耐蚀性最强。

Integrating single Ni site and PtNi alloy on two-dimensional porous carbon nanosheet for efficient catalysis in fuel cell

The performance of catalyst depends on the intrinsic activity of active sites and the structural characteristics of the support.Here,we simultaneously integrate single nickel(Ni)sites and platinum-nickel(PtNi)alloy nanoparticles(NPs)on a two-dimensional(2D)porous carbon nanosheet,demonstrating remarkable catalytic performance in the oxygen reduction reaction(ORR).The single Ni sites can activate the oxygen molecules into key oxygen-containing intermediate that is further efficiently transferred to the adjacent PtNi alloy NPs and rapidly reduced to H_(2)O,which establishes a relay catalysis between active sites.The porous structure on the carbon nanosheet support promotes the transfer of active intermediates between these active sites,which assists the relay catalysis by improving mass diffusion.Remarkably,the obtained catalyst demonstrates a half-wave potential of up to 0.942 V,a high mass activity of 0.54 A·mgPt^(−1),and negligible decay of activity after 30,000 cycles,which are all superior to the commercial Pt/C catalysts with comparable loading of Pt.The theoretical calculation results reveal that the obtained catalyst with defect structure of carbon support presents enhanced relay catalytic effect of PtNi alloy NPs and single Ni sites,ultimately realizing improved catalytic performance.This work provides valuable inspiration for developing low platinum loading catalyst,integrating single atoms and alloy with outstanding performance in fuel cell.