High-affinity integration of hydroxyapatite nanoparticles with chemically modified silk fibroin

Hydroxyapatite (HA)-based nanocomposites were prepared by a co-precipitation method with silk fibroin (SF) serving as organic matrix. Silk fibroin was chemically modified with an alkali solution or an enzyme attempting to improve the interface between the mineral and the organic matrix. The influences of the alkali and enzyme pretreatments on microstructure and physicochemical properties of HA–SF composite were examined and compared. The results reveal that both the two kinds of pretreatments facilitate the formation of highly ordered three-dimensional porous network throughout the composites, increase the microhardness of the composite, and promote the preferential growth of HA crystallites along c-axis. Among all the as-prepared samples, the composite containing the enzyme pretreated SF shows desirable hierarchical microstructure with higher degree of organization and more uniform pore size distribution. Due to the enzyme pretreatment, HA crystallites undergo obvious changes in morphology from rod-like to␣whisker-like and in crystal growth towards more apparent epitaxy along c-axis. The alkali pretreatment induces the stronger chemical interactions between HA and SF and thus to strengthen the inorganic–organic interfacial adhesion. The newly developed HA–SF composites are expected to be attractive biomedical materials for bone repair and remodeling.     

Simple model for blistering mechanism

A simple model for blistering mechanism is proposed for energies higher than 20 keV. The model assumes that through the nucleation of smaller bubbles, a critical bubble radius is reached. The planar stress results of Jeffery for a semi-infinite plate with a circular hole subject to a uniform inner normal pressure are roughly taken as valid for the three-dimensional case. Under this assumption, the thickness of the blister's cover and critical ion dose for blister formation are calculated from the knowledge of the mean projected range of ions and blister diameter taken from experimental results. The resulting values are in agreement with the experimental values reported. The model can qualitatively explain breakage at the top of the dome-shaped blisters observed in molybdenum at 1100 K.     

The C2π and the X2σ States of BaF

An extensive calculation was carried out using the precisely measured value of the Q-band heads and the following molecular constants for the C²π¹ ₂ and the X²σ states, which are responsible for the Green Band System of BaF, were determined.     

Metal-doped apatitic calcium phosphates: preparation,characterization, and reactivity in the removal of hydrogen sulfide from gas phase

With the expansion of human activities, there are more and more living areas adjacent to industrial and/or agricultural activities such as chemical processes, petroleum processes, paint finishing, food processing, livestock farming, composting plants etc. Bad odor is part of several nuisances caused by industrial and/or agricultural activities. Hydrogen sulfide (H₂S) is a typical odorous molecule which causes foul odor at very low concentration. This molecule is formed in different industrial installations, in particular in coal combustion, and petrochemical refinery. The separation and/or transformation of H₂S from gas phase to odorless products are important processes for sustainable development. In this paper, we communicate the preparation of new sorbents for the sorption of H₂S from a synthetic gas effluent. These sorbents consist in an inorganic phase (hydroxyapatite) as host particles, and well-dispersed particles of a metal oxide as guest particles which are the active phase for the removal of H₂S. At room conditions, iron, lead, and zinc doped calcium phosphates were found to be effective for the removal of H₂S. The performance of the sorbents depends on preparation method and the nature of active phases. This opens new prospects for the treatment of H₂S from gas phase.     

羟基磷灰石负载Ni催化剂中Ni含量对催化甲烷二氧化碳重整制合成气性能的影响

以低温沉淀方法制备的羟基磷灰石(HAp)为载体,采用浸渍法制备了一系列不同Ni含量的Ni/HAp催化剂,并采用BET、H2-TPR、XRD、SEM、FT-IR、TEM和TG-DTA技术对催化剂进行了表征。结果表明,NiO含量为13%的催化剂表现出最好的催化甲烷二氧化碳重整制合成气活性,在850℃、空速3.6×104mL/(h·gcat)的反应条件下,甲烷和二氧化碳的转化率在10 h内分别稳定在72%和83%。这主要归因于催化剂中金属和载体之间的强相互作用。虽然反应后的催化剂表面有少量的积炭,但这些积炭多以丝状炭存在,并不会影响催化剂的活性和稳定性。     

初始钙-磷物质的量比值对超长羟基磷灰石纳米纤维微观结构的影响

羟基磷灰石(HA)晶体的形核和生长与表面活性剂、初始钙-磷物质的量比值(nCa,0/nP,0)密切相关.因此,本研究以油酸为表面活性剂制备高柔韧超长HA纳米纤维,利用X射线衍射(XRD)、FTIR、场发射扫描电镜(FESEM)和能量色散X射线谱(EDS)探究了不同nCa,0/nP,0对HA纳米纤维微观结构的影响,并基于...     

铽掺杂羟基磷灰石的制备及其荧光特性

在室温下采用化学沉淀法制备了铽掺杂的羟基磷灰石(Tb-HAP),通过X射线衍射分析(XRD)、傅里叶变换红外光谱(FT-IR)和荧光光谱(PL)等对其结构和荧光性能进行了表征分析。XRD和FT-IR测试表明,Tb³⁺的掺杂对羟基磷灰石的结构没有显著影响。荧光光谱分析表明:在545nm波长监测下,测得的最佳激发波长为378nm。样品的发光强度随Tb³⁺在样品中的掺杂摩尔分数先增大后减小,在8%时发光最强。此外,Tb-HAP样品的荧光寿命随着Tb³⁺掺杂摩尔分数的增加呈现减小的趋势。

     

激光诱导分子光谱应用于碳元素形态分析

选用碳元素常见的有机形态（C     

不同钙源的羟基磷灰石的合成及表征

通过比较法研究了不同钙源在水热条件下合成羟基磷灰石的方法。SEM,XRD和FT-IR的测试结果表明,蛋壳不仅可以成为有效钙源,而且多孔结构还可充当硬模板,在磷酸二氢钠缓慢腐蚀CaCO3的同时提供PO3-4诱导生成花状羟基磷灰石。研究表明,磷酸肌酸钠水热缓慢分解释放磷酸根在合成高纯度羟基磷灰石方面有着广阔的应用前景。     

Bioactive materials for bone regeneration based on zinc-modified hydroxyapatite

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