Enhanced wear resistance,antibacterial performance,and biocompatibility using nanotubes containing nano-Ag and bioceramics in vitro

A good Ti-based joint implant should prevent stress shielding and achieve good bioactivity and anti-infection performance.To meet these requirements,the low-elastic-modulus alloy—Ti–35Nb–2Ta–3Zr—was used as the substrate,and functional coatings that contained bioceramics and Ag ions were prepared for coating on TiO_(2)nanotubes(diameter:(80±20)nm and(150±40)nm)using anodization,deposition,and spin-coating methods.The effects of the bioceramics(nano-β-tricalcium phosphate,microhydroxyapatite(micro-HA),and meso-CaSiO_(3))and Ag nanoparticles(size:(50±20)nm)on the antibacterial activity and the tribocorrosion,corrosion,and early in vitro osteogenic behaviors of the nanotubes were investigated.The tribocorrosion and corrosion results showed that the wear rate and corrosive rate were highly dependent on the features of the nanotube surface.Micro-HA showed great wear resistance with a wear rate of(1.26±0.06)×10^(−3)mm^(3)/(N·m)due to adhesive and abrasivewear.Meso-CaSiO_(3)showed enhanced cell adhesion,proliferation,and alkaline phosphatase activity.The coatings that contained nano-Ag exhibited good antibacterial activity with an antibacterial rate of≥89.5%against Escherichia coli.These findings indicate that hybrid coatings may have the potential to accelerate osteogenesis.

Self-mode-locking optoelectronic oscillator with ultrashort time delay

The optoelectronic oscillator(OEO)is a typical time-delay system with rich nonlinear dynamical characteristics.Most of the previous research on OEOs has been focused on analyzing the properties of OEOs with a long time delay,which makes it difficult to realize mode locking without additional phaselocking mechanisms.We have achieved,for the first time to our knowledge,a self-mode-locking OEO and generated stable microwave frequency combs by analyzing the characteristics of OEOs with an ultrashort time scale.In the experiment,the self-mode-locking OEOs with fundamental mode,second-order harmonic,and sixth-order harmonic were realized by adjusting the system parameters,all of which produced uniform square wave signals with tunable duty cycles,steep rising and falling edges,and periods of less than 20 ns.The self-fundamental-mode-locking OEOs with different time delays were also implemented and experimentally realized.Furthermore,the experiment revealed the self-hybrid mode-locking OEO,which is the coexistence and synchronization of the three measured self-locking modes in one OEO cavity,demonstrating the complex nonlinear dynamical behaviors of the OEO system and enabling the generation of periodic nonuniform hybrid square wave signals.The realization of the self-mode-locking OEO and the generation of flexible and stable square wave signals at ultrashort time scales enrich the study of OEO nonlinear dynamics in the realm of complex microwave waveform generation,offering promising applications in areas such as atomic clocks,radars,communications,and optoelectronic neural networks.

StSN2 interacts with the brassinosteroid signaling suppressor StBIN2 to maintain tuber dormancy

After harvest,potato tubers undergo an important period of dormancy,which significantly impacts potato quality and seed vigor.StSN2 has been reported as a key gene for maintaining tuber dormancy;in this study,we explored the molecular mechanism by which StSN2 maintains dormancy.StBIN2 was first identified as a candidate protein that interacts with StSN2 by co-immunoprecipitation/mass spectrometry,and both qPCR and enzyme activity experiments showed that StSN2 can promote the StBIN2 expression and activity.In addition,the interaction between StSN2 and StBIN2 was verified by yeast two-hybrid,luciferase complementation experiments and co-immunoprecipitation.Bioinformatics analysis and site-directed mutagenesis confirmed the critical role of cysteine residues of StBIN2 in its binding to StSN2.Similar to that of StSN2,overexpression of StBIN2 extended the dormancy of potato tuber.Interaction between StSN2 and StBIN2 increased the activity of the StBIN2 enzyme,inhibited the expression of StBZR1,and suppressed BR signaling.On the contrary,this interaction promoted the expression of StSnRK2.2/2.3/2.4/2.6 and StABI5,key genes of ABA signaling,and the phosphorylation of StSnRK2.3,thereby promoting ABA signaling.Altogether,our results indicate that StSN2 interacts with StBIN2 through key cysteine residues and StBIN2 maintains tuber dormancy by affecting ABA and BR signaling.Findings of this research offer new insights into the molecular mechanism by which StSN2 maintains potato tuber dormancy through interaction with StSIN2 and provide guidance for potato improvement.

Inhomogeneous deformation of {111} grain in cold rolled tantalum

The microstructures of {111}<uvw> grain were characterized in detailed and systematically investigated with the aid of electron backscatter diffraction(EBSD) and transmission electron microscope(TEM). The stored energy in different regions in the grain was evaluated by the band contrast values collected from EBSD. The results show that the distribution of energy is inhomogeneous through the grain. Especially,the regions containing the least and the largest energy were extracted from the EBSD data, and then quantitatively analyzed based on the misorientation and Schmid factor. Many peaks with large misorientation appeared in the region containing larger energy, and these peaks represent the existences of micro-bands and micro-shear bands in {111} grain. The results of Schmid factor suggest that the region containing larger energy is prone to deforming ahead of the region with less stored energy, implying the more serious subdivision of the microstructure of region with larger stored energy.

选区激光熔化对GCr15高碳钢成形性能的研

以等离子旋转电极制备的GCr15高碳钢粉末为实验原料,采用选区激光熔化(SLM)制备GCr15高碳轴承钢。研究了SLM成形过程中激光功率、扫描速度、体能量密度对GCr15成形性能的影响和成形后的组织转变。实验结果表明,在参数可调节的范围内,激光功率、扫描速度、体能量密度与相对密度呈线性关系。从能量密度曲线可以看出,功率对相对密度的影响大于扫描速度;在低功率情况下,会出现功率与相对密度关系失真;同时,选区激光熔化制备GCr15轴承钢的组织细小、均匀,主要为粗针状的马氏体和残余奥氏体,随着能量密度的增加,残余奥氏体的含量有所增加。

生物素-亲和素系统的应用研究进展

该文综述了生物素-亲和素系统(Biotin-Avidin System,BAS)相关研究的最新进展,对生物素-亲和素系统在免疫学、蛋白质组学和组织化学等研究领域中的应用进行了梳理和总结,提出了生物素-亲和素系统应用中可能出现的问题,并对生物素-亲和素系统应用前景进行了展望,希望为后续相关研究尤其是在植物科学的研究中提供思路。