A novel GEL-OHA/HAp bone substitute

Self-crosslinked gelatin-oxidized hyaluronic acid/ hydroxyapatite (GEL-OHA/HAp) composite bone substitute was successfully prepared with a novel in situ precipitation method without using any toxic chemical cross-linkers, and its characterizations, including elemental composition, surface morphology, crystallinity, and structure of crystalline phase, were carried out. In order to evaluate its corresponding performances, comparisons with glutaraldehyde crosslinked gelatin/hydroxyapatite (GEL-Glu/ HAp) composite were made in detail. The results indicate that nano-HAp crystallites are homogeneously dispersed in both GEL-OHA/HAp and GEL-Glu/HAp composites, and the HAp crystallites in the former take larger particle size than those in the latter. Mechanical property tests show the acceptable mechanical strength at high strain of GEL-OHA/HAp composite. Study of in vitro degradation and swelling demonstrate that the two composites have similar degradation rate and water absorption capability. By in vitro cell culture, it has been found out that the cells on the GEL-OHA/HAp composite show higher proliferative potential than the cells on the GEL-Glu/HAp composite. Compared with GEL-Glu/HAp composite, GEL-OHA/HAp composite provides an excellent strategy for preparation of non-toxic bone substitute with acceptable corresponding properties.     

Electrospun Nanofibers of Hydroxyapatite/Collagen/Chitosan Promote Osteogenic Differentiation of BMSCs

Bone tissue engineering, aiming at developing bone substitutes for repair and regeneration of bone defects instead of using autologous bone grafts, has attracted wide attention in the field of tissue engineering and regenerative medicine. Developing biomimetic biomaterial scaffolds able to regulate osteogenic differentiation of stem cells could be a promising strategy to improve the therapeutic efficacy. In this study, clectrospun composite nanofibers of hydroxyapatite/collagen/chitosan （ HAp/Col/CTS ） resembling the fibrous nanostructure and constituents of the hierarchically organized natural bone, were prepared to investigate their capacity for promoting bone mesenchymal stem cells （BMSCs） to differentiate into the osteogenic lineage in the absence and presence of the osteogenlc supplementation, respectively. Call morphology, proliferation and quantified specific osteogenic protein expression on the electrospun HAp/Coi/CTS scaffolds were evaluated in comparison with different controls including dectrospun nanofibrous CTS, HAp/CTS and tissue culture plate. Our remits showed that the nanofibrous HAp/Col/CTS scaffolds supported better spreading and proliferation of the BMSCs than other substrates （ P 〈 0.01 ）. Expressions of osteogenesis protein markers, alkaline phosphatase （ALP） and Col, were significantly upregulated on the HAp/Col/CTS than those on the CTS （P 〈0.01） and HAp/ CTS （P 〈 0. 05 ） scaffolds in the absence of the osteogeulc supplementation. Moreover, presence of osteogeulc supplementation also proved to enhance osteogeule differentiation of BMSCs on HAp/ Col/CTS scaffolds, indicative of a synergistic effect. This study highlights the potential of BMSCs/HAp/Col/CTS cell-scaffold system for functional bone repair and regeneration applications.     

取心工具用大尺寸疏水吸油海绵的制备与吸油性能研究

海绵取心工具(取心衬筒)中一种关键材料是高吸油海绵,为了满足钻井取心的使用需求,需要制备大尺寸、超疏水的吸油海绵。利用多巴胺(DA)氧化自聚(以NaIO₄为氧化剂)以及聚多巴胺(PDA)与疏水剂(十八胺,ODA)的反应,采用一步和两步浸涂法对小尺寸(30 mm×30 mm×10 mm)和大尺寸(910 mm×400 mm×10 mm)商用三聚氰胺海绵进行疏水改性;利用扫描电子显微镜(SEM)观察改性海绵的表面形貌,并测定其水接触角和吸油性能。结果表明：改性海绵表面形成了PDA粒子,两步法所得改性海绵的表面粒子细密、均匀;增大DA的质量浓度和提高氧化剂含量,海绵表面PDA粒子增多。确定了海绵改性的最优条件：DA质量浓度为4～6 mg/mL,DA与NaIO₄的质量比为1∶1,海绵在ODA溶液中的浸泡时间为2～4 h。在小尺寸样品研究结果的基础上,将大尺寸海绵在DA溶液中浸泡1 min,在空气中放置2 h,然后与ODA溶液反应4 h进行改性,所得大尺寸改性海绵的表面水接触角为152.6°,10 s时吸油量达90 g/g,并且多次吸油、析油后仍保持较...     

Organic dye removal and recycling performances of graphene oxide-coated biopolymer sponge

In this study, a biopolymer sponge (PS) with a crosslinked mixture of gelatin-chitosan-poly(vinyl alcohol) was dipped into graphene oxide (GO) solution to form a composite sponge (CS, GO-coated PS) by a combination of simple dip-coating and freeze-drying procedures, as a sponge-like adsorbent in organic dye removal applications. The morphological, chemical, crystalline, mechanical and thermal characterizations of the as-obtained sponges were further investigated for the possible changes in the structure of sponge-like adsorbent after coating the GO sheets on the 3D porous structure of PS. The results showed that the CS had possessed effectively organic dye removal performances comparing to the PS. In the adsorption, the Langmuir and pseudo-second-order models corresponding to a monolayer approach and a chemical adsorption were appropriated. The maximum adsorption capacity of Rhodamine B and Congo red reached 126.8 and 135.0 ?mg?g^?1; and 145.6 and 148.6 ?mg?g^?1 corresponding onto the PS and CS. It indicates that the maximum adsorption capacity on the CS enhanced significantly comparing to those on the PS owing to the functional GO sheets coated in the 3D porous structure of PS, which leads to supplying further functional adsorption sides on the whole 3D porous structure of CS. Notably, the sponges-like adsorbents could be regenerated and used again without a remarkable decrease of dye removal ability occurred in 9 adsorbing–desorbing cycles. Therefore, the CS prepared in this study can become a potential adsorbent for actual applications because of non-toxic materials, proper structural features, low-cost material and operation, and reliable recyclability.     

Biomimetic mineralization synthesis of hydroxyapatite bacterial cellulose nanocomposites

Hydroxyapatite (HAp)/bacterial cellulose (BC) nanocomposites were prepared by an optimal biomimetic mineralization synthesis approach for bone tissue engineering application. BC with ultrafine three dimensional network was negatively charged by the adsorption of polyvinylpyrrolidone (PVP) to initiate the nucleation of HAp. The HAp was grown in vitro along the nanofiber network of BC via dynamic simulated body fluid (SBF) treatment. It was found that rod-like HAp particles in the nano-scale (100–200 nm) homogeneously deposited on the surface of PVP-BC. ATR-Fourier Transform Infrared Spectroscopy (ATR-FTIR) results showed that carbonate-containing HAp crystals resembling natural bones were formed by biomimetic mineralization method. Moreover, the amount of HAp observed increased with increasing mineralization time. And the Ca/P overall ratio ranged from 1.37 to 1.59. The results from Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) indicated that PVP treatment enhanced the apatite nucleation ability of BC with higher HAp deposit amount.     

3D打印制备HA/PCL复合材料组织工程支架的研究

应用熔融沉积成型技术（FDM）制备羟基磷灰石（HA）/聚己内酯（PCL）组织工程支架,探讨其内部结构和力学性能。以羟基磷灰石和聚己内酯为原料,采用熔融共混技术分别制备HA质量分数为20%的nano-HA/PCL和micro-HA/PCL复合材料,使用自主研发的熔体微分FDM 3D打印机制备HA/PCL复合材料组织工程支架。通过显微镜观察发现,所制备的nano-HA/PCL和micro-HA/PCL组织工程支架具有均匀分布且相互连通的近似矩形的孔隙。nano-HA/PCL和micro-HA/PCL组织工程支架的断面图分析结果表明,nano-HA/PCL组织工程支架中HA粒子分布均匀,而micro-HA/PCL组织工程支架中HA粒子发生了团聚,导致nano-HA/PCL组织工程支架的拉伸强度和弯曲强度均高于micro-HA/PCL组织工程支架。因此,利用熔体微分FDM 3D打印机打印生物活性nano-HA/PCL复合材料组织工程支架在骨组织工程中具有潜在的应用前景。     

Microstructure and mechanical properties of a hot-extruded Al-based composite reinforced with core-shell-structured Ti/Al3Ti

An Al-based composite reinforced with core-shell-structured Ti/Al₃Ti was fabricated through a powder metallurgy route followed by hot extrusion and was found to exhibit promising mechanical properties. The ultimate tensile strength and elongation of the composite sintered at 620℃ for 5h and extruded at a mass ratio of 12.75:1 reached 304 MPa and 14%, respectively, and its compressive deformation reached 60%. The promising mechanical properties are due to the core-shell-structured reinforcement, which is mainly composed of Al₃Ti and Ti and is bonded strongly with the Al matrix, and to the reduced crack sensitivity of Al₃Ti. The refined grains after hot extrusion also contribute to the mechanical properties of this composite. The mechanical properties might be further improved through regulating the relative thickness of Al-Ti intermetallics and Ti metal layers by adjusting the sintering time and the subsequent extrusion process.     

The strain ampli tude-controlled cyclic fatigue behavior of Al2O3 fiber reinforced Al–Si alloy composite at elevated temperatures

The strain amplitude-controlled fatigue characteristics of an Al–Si casting alloy and itscomposite reinforced with 17 vol% Al₂O₃ fibers (Al–Si/Al₂O₃) are studied at three different temperatures. Both the alloy and the composite showed different degrees of cyclic softening at elevated temperatures. Increasing the temperature, fatigue damage of either the alloy or the composite occurred with varying mode from brittle fracture of silicon particles to their separation from the aluminum matrix. This is explained by the different thermal expansion coefficients of silicon particles and the aluminum matrix. The reinforcement Al₂O₃ fibers in the composite showed a similar damage behavior with those silicon particles despite temperature variation     

高应变率下SiCp/Al的断口形貌和变形机制

利用Hopkinson压杆对采用无压浸渗法制备的高体积分数SiCp/Al复合材料进行高应变率冲击压缩实验,研究了应变率对复合材料微观断口形貌的影响,分析了其在高应变率下的变形机制.结果表明：强度较高的复合材料有较强的产生变形局部化的倾向;同时,SiC颗粒尺寸对局部化的形成有明显影响,增强相颗粒尺寸较小（100μm）的复合材料更容易产生变形局部化,在高应变率压缩载荷下,无压浸渗高体积分数SiCp/Al复合材料在增强相颗粒破裂的同时会出现基体的局部化变形,复合材料的损伤行为与材料中的增强相颗粒尺寸密切相关.     

SiCp/ZL102复合材料及其压铸件耐磨性能研究

该文针对制约颗粒增强铝基复合材料应用的关键问题，提出运用压力铸造使其近终成型。在成功制备SiCp／ZL102压铸件的基础上，系统研究了基体合金、复合材料铸锭及其压铸件的耐磨性能。研究结果表明，复合材料的耐磨性能优于基体合金，压铸成型后，压铸件的耐磨性能显著优于复合材料铸锭，将压铸工艺应用于金属基复合材料的成型，能够有效扩大颗粒增强金属基复合材料的应用范围。     

Biomimetic mineralization synthesis of hydroxyapatite bacterial cellulose nanocomposites

Hydroxyapatite (HAp)/bacterial cellulose (BC) nanocomposites were prepared by an optimal biomimet ic mineralization synthesis approach for bone tissue engineering application. BC wi th ultrafine three dimensional network was negatively charged by the adsorption of polyvinylpyrrolidone (PVP) to initiate the nucl eation of HAp. The HAp was grown in vitro along the nanofiber network of BC via dynamic simulated body fluid (SBF) treatment. It was found that rod-like HAp particles in the nano-scale (100 ? 200 nm) homogeneously deposited on the surface of PVP-BC. AT R-Fourier Transform Infrared Spectroscopy (ATR-FTIR) results showed that carbonate-containing HAp crystals resembling natural bones were fo rmed by biomimetic mineralization method. Moreover, the amount of HAp observed increased with increasing mineralization time. And the Ca/P overall ratio ranged from 1.37 to 1.59. The results from Inductively Coupl ed Plasma Atomic Emission Spectroscopy (ICP-AES) indicated that PVP treatment enhanced the apatite nucleation ability of BC with higher HAp deposit amount.     

Microstructure and mechanical properties of a hot-extruded Al-based composite reinforced with core-shell-structured Ti/Al3Ti

An Al-based composite reinforced with core-shell-structured Ti/Al3Ti was fabricated through a powder metallurgy route followed by hot extrusion and was found to exhibit promising mechanical properties. The ultimate tensile strength and elongation of the composite sintered at 620°C for 5 h and extruded at a mass ratio of 12.75:1 reached 304 MPa and 14%, respectively, and its compressive deformation reached 60%. The promising mechanical properties are due to the core-shell-structured reinforcement, which is mainly composed of Al3Ti and Ti and is bonded strongly with the Al matrix, and to the reduced crack sensitivity of Al3Ti. The refined grains after hot extrusion also contribute to the mechanical properties of this composite. The mechanical properties might be further improved through regulating the rela-tive thickness of Al-Ti intermetallics and Ti metal layers by adjusting the sintering time and the subsequent extrusion process.     

热处理对SiC_p/Al2124复合材料显微组织与耐蚀性的影响

为提高 Si C颗粒增强铝基复合材料 Al 2 12 4的耐蚀性 ,采用 X射线衍射、扫描电镜和电化学测试等手段 ,研究了 3种热处理工艺 (T1,T4和 T6 )对复合材料中第二相化合物的析出状况以及该材料在 Na Cl水溶液中的腐蚀行为的影响。结果表明 ,在 T1状态下 ,铝合金基体内及 Si Cp/铝合金界面上析出大量以 Cu Al2 为主的第二相化合物 ,导致复合材料表面点蚀活性位置增多 ,点蚀敏感性增大 ;但是 ,T6和T4热处理显著减少 Cu Al2 相析出并大幅度降低复合材料的点蚀敏感性。 3种热处理状态下 Si Cp/Al 2 12 4复合材料的耐点蚀性能可依下列顺序提高 :T1,T6 ,T4。     

卷丹百合鳞片育苗技术研究

为探索适于卷丹百合鳞片扦插育苗的有效方法,对在不同基质上(悬空海绵组10个处理,盆栽组6个处理)培养80d后鳞片的生长进行研究.结果表明:(1)悬空海绵组在海绵筒中加入的粉状活性炭高度越高鳞片生长状况越差,其中活性炭高度为0.2~0.3cm时鳞片的生长指标最优,生根率为86.33%,叶片抽生率为83.33%,生根系数为2.33,增殖系数达2.97,腐烂率仅为3.33%.(2)悬空海绵组与盆栽组在细沙中加入活性炭的量越多鳞片长势越差;基质相同时,前者培养的鳞片生长状况优于后者.采用悬空海绵法培育卷丹百合鳞片,操作简单、鳞片生长好,增殖多,是其鳞片扦插育苗的一种新方法.     

超声在制备SiC／Al－Mg颗粒增强复合材料中的应用

通过高强度超声处理使ＳｉＣ颗粒均匀分散于铝液中，获得了组织结构良好的ＳｉＣ／Ａｌ－Ｍｇ颗粒增强复合材料．讨论了超声对改善ＳｉＣ颗粒与铝液之间的润湿性和实现颗粒在铝液中均匀分散的作用．结果表明，超声处理是制取颗粒增强金属基复合材料的有效方法。     

硅烷改性三聚氰胺海绵的制备及其油水分离性能研究

利用甲基三甲氧基硅烷和二甲基二甲氧基硅烷水解后形成的水解液涂覆于三聚氰胺海绵上,成功制备了疏水亲油海绵。通过扫描电镜、X射线光电子能谱、傅里叶红外光谱、接触角和吸油能力测试等方法,对硅烷改性三聚氰胺海绵进行了表征。结果表明,硅烷改性使得本身亲水的三聚氰胺海绵表面转变为疏水状态,水的接触角可达149±0.5°,对八种油品或有机试剂的吸油能力可达到自重的47-60倍,使用达200次后吸附容量仅降低了17.7%,分离效率在96%以上。除此外,改性的海绵还具有较好的耐酸碱、耐盐和耐有机溶剂的特性,在溢油回收方面展现了良好的应用前景。     

粘弹基SMA复合材料层合板的有限元分析

用有限元法对粘弹基形状记忆合金 (SMA)复合材料层合板在横向均布载荷作用下的挠度进行了研究 ,结果发现 ,基体的热粘弹性对 SMA的作动性能有较大影响 ,且其程度随板边界的固结方式、SMA丝的数目、SMA的预应变、板的铺设角的不同而不同     

原位观察铜网格增强Al/Cu复合材料的断裂行为

将一种按正交法编织的铜网格作为增强体引入到铝基体中制备了Al/Cu复合材料,再借助原位拉伸扫描电镜(SEM),观察了铝铜复合材料的组织演变,研究了其断裂机理与力学性能之间的关系.结果表明:在相同轧制变形量下,25 ℃冷轧和400 ℃热轧均可破碎增强体铜网格,并使其均匀分布于基体铝板.复合板原位拉伸下的载荷-位移曲线均表现出明显的弹性阶段、塑性阶段和失效阶段,微裂纹在Cu颗粒周围和应力集中处萌生,主裂纹及其扩展主要是Cu颗粒周围界面分层开裂与微裂纹沿滑移线方向的扩展共同作用下形成的,并且最终沿滑移线的断裂路径与单轴拉伸方向呈45°.发生在Al层的塑性断裂和Al/Cu结合界面上的界面分层断裂是Al/Cu复合板两种主要的失效方式.     

On the liquid-phase technology of carbon fiber/aluminum matrix composites

The main problems with the liquid-phase technology of carbon fiber/aluminum matrix composites include poor wetting of the fiber with liquid aluminum and formation of aluminum carbide on the fibers' surface. This paper aims to solve these problems. The theoretical and experimental dependence of porosity on the applied pressure were determined. The possibility of obtaining a carbon fiber/aluminum matrix composite wire with a strength value of about 1500 MPa was shown. The correlation among the strength of the carbon fiber reinforced aluminum matrix composite, the fracture surface, and the degradation of the carbon fiber surface was discussed.     

复合材料层合板非线性粘弹性有限元分析

用有限元方法进行了复合材料层合板非线性粘弹性分析，给出了有限元列式及相应的分析程序，对在机械及热载荷作用下的层合板粘弹性响应进行了研究，得到一些有益的结果。