分类: 材料科学 >> 纳米科学和纳米技术 提交时间: 2017-03-30
摘要: Electrochemical performances of multi-walled carbon nanotubes (CNT)-SiCN composite have been investigated. The sample was synthesized by a simple ultrasonication assisted method combined with high-temperature pyrolysis and characterized by Fourier transfo
分类: 材料科学 >> 纳米科学和纳米技术 提交时间: 2017-03-30
摘要: Electrochemical performances of multi-walled carbon nanotubes (CNT)-SiCN composite have been investigated. The sample was synthesized by a simple ultrasonication assisted method combined with high-temperature pyrolysis and characterized by Fourier transfo
分类: 材料科学 >> 材料科学(综合) 提交时间: 2017-03-30
摘要: Eu2+-doped Ba3Si6O12N2 green phosphors were prepared by microwave assisted sintering method at 1275 degrees C for 4 h, while the counterparts using conventional solid-state reaction method were synthesized at temperature higher than 1300 degrees C and for
分类: 材料科学 >> 材料科学(综合) 提交时间: 2017-03-30
摘要: Eu2+-doped Ba3Si6O12N2 green phosphors were prepared by microwave assisted sintering method at 1275 degrees C for 4 h, while the counterparts using conventional solid-state reaction method were synthesized at temperature higher than 1300 degrees C and for
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: Mesoporous CoFe2O4 nanospheres with an average size of 180 nm were fabricated via a facile hydro- thermal process using ethylene glycol as solvent and sodium acetate (NaAc) as electrostatic stabilizer. In this method, ethylene glycol plays a vital role in the formation of cobalt nanoospheres as a solvent and reducing agent. The structure and morphology of the prepared materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high- resolution TEM (HRTEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The nanospheres exhibited ferromagnetic properties with high saturation magne- tization value of about 60.19 emu/g at room temperature. The BET surface area of the nanospheres was determined using the nitrogen absorption method. The porous CoFe2O4 nanospheres displayed good magnetic properties, which may provide a very promising candidate for their applications in target drug delivery.
分类: 生物学 >> 生物物理学 >> 生物物理、生物化学与分子生物学 提交时间: 2016-05-05
摘要: Oxidative stress is a major cause of sporadic Parkinson's disease (PD). Here, we demonstrated that c-Abl plays an important role in oxidative stress-induced neuronal cell death. C-Abl, a nonreceptor tyrosine kinase, was activated in an 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride (MPTP)-induced acute PD model. Conditional knockout of c-Abl in neurons or treatment of mice with STI571, a c-Abl family kinase inhibitor, reduced the loss of dopaminergic neurons and ameliorated the locomotive defects induced by short-term MPTP treatment. By combining the SILAC (stable isotope labeling with amino acids in cell culture) technique with other biochemical methods, we identified p38 alpha as a major substrate of c-Abl both in vitro and in vivo and c-Abl-mediated phosphorylation is critical for the dimerization of p38 alpha. Furthermore, p38 alpha inhibition mitigated the MPTP-induced loss of dopaminergic neurons. Taken together, these data suggested that c-Abl-p38 alpha signaling may represent a therapeutic target for PD.
提交时间: 2017-04-06
摘要: Electrochemical performances of multi-walled carbon nanotubes (CNT)-SiCN composite have been investigated. The sample was synthesized by a simple ultrasonication assisted method combined with high-temperature pyrolysis and characterized by Fourier transfo
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: The scale behavior of Ti2AlC coating at 750 °C in air and pure water vapor was investigated. A four-layered scale, a thick TiO2 and Al2O3 mix oxide outer layer, followed by a thin α-(Al, Cr)2O3 sublayer, a thick Fe2O3 and TiO2 mix oxide mid-layer and a thin Al2O3-rich oxide inner layer in sequence, developed on the Ti2AlC coatings in air. Whereas internal oxidation occurred, no distinct oxide scale formed on the Ti2AlC coating in the case of the oxidation in pure water vapor. The Ti2AlC coating improved the oxidation resistance of 316LSS in air, especially in wet air.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: Inspired by pressure resistance welding of metallic materials, herein we describe how two MAX phases—Ti3SiC2 and Ti3AlC2—were successfully joined by a rapid electric current heating method in a pulsed electric current sintering furnace. No welding agent was employed and the total processing time was less than 6 min. When the bulk temperature of the joint couple exceeded 1070°C, good joints, with shear strength above 50 MPa, were achieved in both homo- and heterojunction joints.
分类: 材料科学 >> 材料科学(综合) 提交时间: 2017-05-09
摘要: Density functional theory (DFT) calculation is employed to study the adsorption properties of Pb and Cu on recently synthesized two-dimensional materials MXenes, including Ti3C2, V2C1 and Ti2C1. The influence of surface decoration with functional groups such as H, OH and F have also been investigated. Most of these studied MXenes exhibit excellent capability to adsorb Pb and Cu, especially the adsorption capacity of Pb on Ti2C1 is as high as 2560 mg g 1. Both the binding energies and the adsorption capacities are sensitive to the functional groups attached to the MXenes’ surface. Ab initio molecular dynamics (ab-init MD) simulation confirms that Ti2C1 remains stable at room temperature after adsorbing Pb atoms. Our calculations imply that these newly emerging two-dimensional MXenes are promising candidates for wastewater treatment and ion separation.
提交时间: 2017-05-02
摘要: This study reports a viable method for the synthesis of Ti2SC phase using iron disulfide or iron sulfide as sulfur source and a post-treatment with acid. The reaction routes to Ti2SC phases starting from two different chemical compositions of 2Ti-FeS2-2Ti
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: Copper matrix composites reinforced with graphene nanoplatelets (GNPs) were prepared via molecular- level mixing process and spark plasma sintering process. The impacts of graphene content on micro- structure, mechanical performance, thermal diffusivity, electrical conductivity and tribological properties of the composites were investigated. For microstructure, GNPs distributed randomly in composites with low graphene concentration (no more than 0.8 vol.%), but aligned in the direction perpendicular to the consolidation force when graphene concentration was above 2.0 vol.%. The mechanical performance of copper was strengthened evidently by the graphene addition. However, the strengthen effects were firstly enhanced and then deteriorated by increasing graphene content. Thermal diffusivity showed a constant decrease with the increase of graphene content. Anisotropy thermal performance was obtained by composites with graphene alignment. Furthermore, graphene addition showed little negative impact on electrical conductivity but dramatically improved tribological performance.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: MXenes, a novel family of two-dimensional metal carbides, are receiving intense attention for lithium-ion batteries (LIBs) and super- capacitors because they have high volumetric capacitance exceeding all carbon materials. However, serious interlayer stacking exists in MXene particles, which greatly decreases the electrical conductivity in the bulk and hinders the accessibility of interlayers to electrolyte ions. Thus, multi-stacked MXene particles exhibit low capacitance and poor rate capability. Herein, we report an effective strategy to directly improve the electrochemical performance of multi-stacked MXene (Ti3C2Tx) particles as LIB anode materials. It was successfully realized by growing conductive “carbon nanofiber (CNF) bridges” within the gaps of each Ti3C2Tx particle as well as the outside. With the help of these CNFs, the as-prepared Ti3C2/CNF particles exhibited signifi- cantly improved reversible capacity compared with pure Ti3C2Tx particles. More remarkably, even at an ultrahigh rate of 100 C, the capacity of Ti3C2/CNF hybrid particles was just slightly lower than that of pure Ti3C2Tx particles at 1 C, and there was no capacity decay after 2900 cycles at 100 C, demonstrating excellent rate capability and superior long-term stability at the ultrahigh rate.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: A polymer-based visible and quantitative fluorometric assay for CO2 gas is constructed using branched polyethyleneimine (PEI) covalently modified with tetraphenylethylene (TPE). The sensing mechanism relies on the reaction of CO2 with alkylamines of PEI to induce the “solution-to-precipitation” phase transi- tion of the sensory polymer (TPE–PEI), thus resulting in strong aggregation-induced fluorescent emission of TPE–PEI. It works in a relatively environmental benign ethanol medium and avoids the use of toxic amine compounds with unpleasant odor. More importantly, this system is proved to be highly tolerant to possibly coexisting water, carbon monoxide, acid SO2 and H2 S gases as well as many common volatile organic compounds. These characteristics make the presently developed fluorescent chemosensor hold great potential for many real-world applications.
提交时间: 2017-05-02
摘要: V2AlC belongs to a family of ternary nano-laminate alloys known as the MAX phases, which exhibit a unique combination of metallic and ceramic properties. In this work V-Al-C coatings with deposited [V, Al][2]C nano-crystallines and amorphous phase were ma
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: Hexagonal Columnar ZrB2 powders were obtained from irreg- ular commercial powder at low temperature using microwave heating technique. It was confirmed that the raw ZrB2 powders first underwent dissolution process in the glassy coating, fol- lowed by re-crystallization. A growth mechanism involving selective attachment is proposed to explain the formation of the hexagonal tubules.
提交时间: 2017-05-02
摘要: Porous Ti2AlN ceramic, which was measured to be 3.23 g/cm3 about 74.9% of its theoretical value, was successfully synthesized and simultaneously consolidated from starting raw materials of Ti, Al, and TiN powders with a near-stoichiometric molar ratio of
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: The study presents an investigation of irradiation resistance properties of Ti3AlC2 under 500 keV He ions irradiation with the doses ranging from 5.0 1016 to 1.0 1018 ions cm 2 at certain temperatures, like room temperature (RT), 300 and 500 °C. X-ray diffraction (XRD) and Transmission electron microscopy (TEM) are used to study the evolution of structural damage and the behavior of deposited He ions respec- tively. XRD analysis reveals that for the highest dose irradiation ( 52 dpa at peak), no amorphization occurs. And the structural recovery of Ti3AlC2 is more significant accompanied with the gradual disap- pearance of the irradiation-induced TiC phase as the temperature rises from RT to 300 and to 500 °C with the same dose irradiation. TEM observations show that He bubbles appear in the shapes of sphere, string and platelet but no big bubbles are formed for all irradiations. Moreover, no large cracks form in the sam- ple implanted with the highest helium concentration of 6.4 105 appm.
提交时间: 2017-05-02
摘要: The structural transitions of Ti3AlC2 induced by ion irradiation were investigated over a wide fluence range by transmission electron microscopy. No amorphization occurs even at the highest dose of 31 dpa, indicating a great tolerance to irradiation-induc