Evaluation of the biocompatibility of two magnesium alloys as degradable implant materials in comparison to titanium as non‐resorbable material in the rabbit

The aim of this study is to compare the biocompatibility of the two magnesium based alloys LAE442 and LANd442 with that of titanium. For this purpose, cylindrical implants were introduced into the medullary cavity of rabbit's tibiae for 4 and 8 weeks. Animals without any implant served as a control. In the follow-up, clinical, X-ray and μCT-investigations were performed to evaluate the reactions of the bone towards the implanted materials. After euthanasia, ex vivo μCT- and histological investigations were performed to verify the results of the in vivo tests. It could be shown that all materials induce changes in the bone. Whereas LANd442 caused the most pronounced reactions, such as increasing bone volume and bone porosity and decreasing bone density, titanium showed the most bone–implant contact by forming trabeculae. The tibiae of rabbits without implants also reacted by forming cavities, it is therefore assumed that the surgery method itself influences the bone.     

Critical Factors in Opening Pharmaceutical Packages: a Usability Study among Healthcare Workers,Women with Rheumatoid Arthritis and Elderly Women

This cross‐sectional study compared the usability of pharmaceutical packages to determine the critical factors involved in packages with different opening mechanisms. Four packaging types (a bottle with a screw cap, a box with a pill plate, disposable plastic droppers with a container and a jar with a hinge cap) were evaluated by 45 women (nurses, older women and women with rheumatoid arthritis). Usability was evaluated for subjective measures related to the ease of opening and for objective measures related to the time needed to open the packaging, electrical muscular activity (electromyography, EMG) and ranges of motion of the upper extremities. Of the arthritic women, 13% were unable to open the screw‐cap bottle, and 20% did not succeed in opening the plastic dropper packaging. Everyone else, except one older woman handling the plastic dropper packaging, managed to open all the packages. Regarding the ease of opening, the participants gave the plastic dropper packaging the lowest rating (p < 0.001). The arthritic women used greater relative biomechanical strain while opening the screw cap bottle and the box with pill plate compared with the other participants (p < 0.05), with the relative muscular strain in the forearm varying by 29–40% for the maximal EMG activity and the relative range of motion in the wrist being 70–90% of the maximal range of motion. These findings revealed both subjectively and objectively measured features on the usability of pharmaceutical packages. The comprehensibility of the opening mechanism and the ease of handling the package should be considered when user‐friendly products are being created. Copyright © 2013 John Wiley & Sons, Ltd.     

Gradient Type-II CdSe/CdSeTe/CdTe Core/Crown/Crown Heteronanoplatelets with Asymmetric Shape and Disproportional Excitonic Properties

Characterized by their strong 1D confinement and long-lifetime red-shifted emission spectra, colloidal nanoplatelets (NPLs) with type-II electronic structure provide an exciting ground to design complex heterostructures with remarkable properties. This work demonstrates the synthesis and optical characterization of CdSe/CdSeTe/CdTe core/crown/crown NPLs having a step-wise gradient electronic structure and disproportional wavefunction distribution, in which the excitonic properties of the electron and hole can be finely tuned through adjusting the geometry of the intermediate crown. The first crown with staggered configuration gives rise to a series of direct and indirect transition channels that activation/deactivation of each channel is possible through wavefunction engineering. Moreover, these NPLs allow for switching between active channels with temperature, where lattice contraction directly affects the electron–hole (e–h) overlap. Dominated by the indirect transition channels over direct transitions, the lifetime of the NPLs starts to increase at 9 K, indicative of low dark-bright exciton splitting energy. The charge transfer states from the two type-II interfaces promote a large number of indirect transitions, which effectively increase the absorption of low-energy photons critical for nonlinear properties. As a result, these NPLs demonstrate exceptionally high two-photon absorption cross-sections with the highest value of 12.9 × 10⁶ GM and superlinear behavior.     

超细铜粉咪唑改性后的性能

超细铜粉的应用领域广泛,但其表面活性较高、易氧化的问题未能很好解决.为此,采用有机物包覆法对铜粉进行改性以提高其抗氧化能力.结果表明:经咪唑改性后的超细铜粉含氧量低,导电性好;随着咪唑浓度的增加,超细粉体抗氧化能力逐渐增加,但其压实电阻逐渐增大,即粉体的导电性变差,当咪唑的加入量为1.0～1.5 g/L时,超细铜粉常温及高温抗氧化能力较好,且导电性能也较好.本工艺操作简单,可实现工业应用.     

Using synchroton radiation-based micro-computer tomography (SR μ-CT) for the measurement of fibre orientations in cellulose fibre-reinforced polylactide (PLA) composites

The present work deals with the measurement of fibre orientation angles in composites. A study by Bax and Müssig [1] investigated the mechanical properties (tensile and impact characteristics) of injection-moulded flax and Cordenka-reinforced polylactide (PLA) composites with fibre mass fractions between 10 and 30 %. Raising the fibre content from 10 to 30 % resulted in an increase in tensile characteristics, but it was noted that a reinforcement with 10 % flax fibres led to poorer tensile strength as compared to the neat PLA matrix. This behaviour was not expected and needs clarification. Therefore, test specimens with a fibre content of 10 and 30 mass % were examined for their fibre orientations and void content. For the investigations, microcomputer tomography images were created by monochromatic synchrotron radiation. Fibre orientation angles of these micrographs were determined with an adapted measuring mask of the Fibreshape software. It could be shown that the fibre orientation in the composite is dependent on the fibre mass fraction and the type of fibre. No voids were found in all the investigated composites. The average fibre orientation angle of 10 % flax/PLA showed a larger deviation from the longitudinal axis of the test specimen than the other samples, and is made primarily responsible for the lower tensile strength of this composite.     

Capturing Gases in Carbon Honeycomb

In our recent paper (Krainyukova and Zubarev in Phys Rev Lett 116:055501, 2016. doi: 10.1103/PhysRevLett.116.055501) we reported the observation of an exceptionally stable honeycomb carbon allotrope obtained by deposition of vacuum-sublimated graphite. A family of structures can be built from absolutely dominant \({sp}^{2}\)-bonded carbon atoms, and may be considered as three-dimensional graphene. Such structures demonstrate high absorption capacity for gases and liquids. In this work we show that the formation of honeycomb structures is highly sensitive to the carbon evaporation temperature and deposition rates. Both parameters are controlled by the electric current flowing through thin carbon rods. Two distinctly different regimes were found. At lower electric currents almost pure honeycomb structures form owing to sublimation. At higher currents the surface-to-bulk rod melting is observed. In the latter case densification of the carbon structures and a large contribution of glassy graphite emerge. The experimental diffraction patterns from honeycomb structures filled with absorbed gases and analyzed by the advanced method are consistent with the proposed models for composites which are different for Ar, Kr and Xe atoms in carbon matrices.     

Laser-based <Emphasis Type="Italic">in situ</Emphasis> embedding of metal nanoparticles into bioextruded alginate hydrogel tubes enhances human endothelial cell adhesion

Alginate is a widely used hydrogel in tissue engineering owing to its simple and non-cytotoxic gelation process, ease of use, and abundance. However, unlike hydrogels derived from mammalian sources such as collagen, alginate does not contain cell adhesion ligands. Here, we present a novel laser ablation technique for the in situ embedding of gold and iron nanoparticles into hydrogels. We hypothesized that integration of metal nanoparticles in alginate could serve as an alternative material because of its chemical biofunctionalization ability (coupling of RGD ligands) to favor cell adhesion. Cytocompatibility and biofunctionality of the gels were assessed by cell culture experiments using fibroblasts and endothelial cells. Nanoparticles with an average particle size of 3 nm (gold) and 6 nm (iron) were generated and stably maintained in alginate for up to 6 months. Using an extrusion system, several centimeter-long alginate tubes with an outer diameter of approximately 3 mm and a wall thickness of approximately 150 μm were manufactured. Confocal microscopy revealed homogeneously distributed nanoparticle agglomerates over the entire tube volume. Endothelial cells seeded on iron-loaded gels showed significantly higher viability and an increased degree of spreading, and the number of attached cells was also elevated in comparison to the control and gold-loaded alginates. We conclude that laser-based in situ integration of iron nanoparticles (?0.01 wt.%) in alginate is a straightforward method to generate composite materials that favor the adhesion of endothelial cells. In addition, we show that nanoparticle integration does not impair the alginate’s gelation and 3D biofabrication properties.

Open image in new window

     

Synthesis and characterization of manganese containing mesoporous bioactive glass nanoparticles for biomedical applications

Mesoporous bioactive glass (BG) nanoparticles based in the system: SiO₂–P₂O₅–CaO–MnO were synthesized via a modified Stöber process at various concentrations of Mn (0–7 mol %). The synthesized manganese-doped BG nanoparticles were characterized in terms of morphology, composition, in vitro bioactivity and antibacterial activity. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) analysis confirmed that the particles had spherical morphology (mean particle size: 110?nm) with disordered mesoporous structure. Energy dispersive X-ray spectroscopy (EDX) confirmed the presence of Mn, Ca, Si and P in the synthesized Mn-doped BG particles. Moreover, X-ray diffraction (XRD) analysis showed that Mn has been incorporated in the amorphous silica network (bioactive glass). Moreover, it was found that manganese-doped BG particles form apatite crystals upon immersion in simulated body fluid (SBF). Inductively coupled plasma atomic emission spectroscopy (ICP-OES) measurements confirmed that Mn is released in a sustained manner, which provided antibacterial effect against Bacillus subtilis, Pseudomonas aeruginosa and Staphylococcus aureus. The results indicate that the incorporation of Mn in the bioactive glass network is an effective strategy to develop novel multifunctional BG nanoparticles for bone tissue engineering.     

微米六方BN-KH550/聚丁二酸丁二醇酯耐热性复合膜的制备及性能

为进一步改善聚丁二酸丁二醇酯(PBS)的力学性能和耐热性能,采用硅烷偶联剂KH550改性微米六方氮化硼(h-BN),对PBS进行共混改性,通过熔融共混与开炼压延工艺制备了具有较高耐热性的h-BN-KH550/PBS复合膜。对h-BN-KH550粒子结构和复合膜的力学性能、聚集态结构、断面形貌、结晶性能及热稳定性进行了测试和表征。结果表明:与PBS相比,h-BN-KH550/PBS复合膜的力学性能得到改善,当KH550与h-BN质量比为2∶50、h-BN-KH550与PBS质量比为3∶50时,综合力学性能最优;h-BN-KH550粒子可在PBS中均匀分散;在PBS结晶过程中,h-BN-KH550作为成核剂,使PBS的结晶速率加快,结晶度增大;h-BN-KH550/PBS复合膜的热稳定性显著提高,当h-BN-KH550与PBS质量比为3∶50时,复合膜热分解过程中质量损失为5%、10%、50%时的温度(T5d、T10d、T50d)和热分解峰值温度(Tp)分别提高了30.0、22.6、9.5和10.0℃。     

聚苯胺防腐蚀涂料研究进展

介绍了聚苯胺防腐涂料的研究进展及不同的防腐机理.综述了聚苯胺掺杂态和本征态的防腐性能,以及不同涂层体系的防腐性能.