The preparation of large-scale Cu‒Al‒Ni shape memory alloys with excellent microstructure and texture is a significant challenge in this field. In this study, large-scale Cu‒Al‒Ni shape memory alloy (SMA) slabs with good surface quality and strong orientation were prepared by the horizontal continuous casting (HCC). The microstructure and mechanical properties were compared with the ordinary casting (OC) Cu‒Al‒Ni alloy. The results showed that the microstructure of OC Cu‒Al‒Ni alloy was equiaxed grains with randomly orientation, which had no obvious superelasticity. The alloys produced by HCC had herringbone grains with strong orientation near〈1 0 0〉and the cumulative tensile superelasticity of 4.58%. The superelasticity of the alloy produced by HCC has been improved by 4‒5 times. This work has preliminarily realized the production of large-scale Cu‒Al‒Ni SMA slab with good superelasticity, which lays a foundation for expanding the industrial production and application of Cu-based SMAs.
Hollow nanospheres exhibit unique properties and find a wide interest in several potential applications such as drug delivery. Herein, novel hollow bioactive glass nanospheres (HBGn) with large hollow cavity and large mesopores in their outer shells were synthesized by a simple and facile one-pot ultrasound assisted sol‒gel method using PEG as the core soft-template. Interestingly, the produced HBGn exhibited large hollow cavity with ~43 nm in diameter and mesoporous shell of ~37 nm in thickness and 7 nm pore size along with nanosphere size around 117 nm. XPS confirmed the presence of Si and Ca elements at the surface of the HBGn outer shell. Notably, HBGn showed high protein loading capacity (~570 mg of Cyto c per 1 g of HBGn) in addition to controlled protein release over 5 d. HBGn also demonstrated a good in vitro capability of releasing calcium (Ca2+: 170 ppm) and silicate (SiO44−: 78 ppm) ions in an aqueous medium over 2 weeks under physiological-like conditions. Excellent in vitro growth of bone-like hydroxyapatite nanocrystals was exhibited by HBGn during the soaking in SBF. A possible underlying mechanism involving the formation of spherical aggregates (coils) of PEG was proposed for the formation process of HBGn.
Transformation texture is normally different to deformation and recrystallization textures, thus influencing materials properties differently. As deformation and recrystallization are often inseparable to transformation in materials which shows a variety in types such as diffusional or non-diffusional transformations, different phenomena or rules of strengthening transformation textures occur. This paper summarizes the complicated phenomena and rules by comparison of a lot of authors’ published and unpublished data collected from mainly electrical steels, high manganese steels and pure titanium sheets. Three kinds of influencing deformation are identified, namely the dynamic transformation with concurrent deformation and transformation, the transformation preceded by deformation and recrystallization and the surface effect induced transformation, and the textures related with them develop in different mechanisms. It is stressed that surface effect induced transformation is particularly effective to enhance transformation texture. It is also shown that the materials properties are also improved by controlled transformation textures, in particular in electrical steels. It is hoped that these phenomena and processing techniques are beneficial to the establishment of transformation texture theory and property improvement in practice.
Early detection of cancer has multitude of advantages like early diagnosis, reduced risk, ease in the treatment and follow up of recurrence. New and developed techniques are always under research to control the spreading malignancy. Graphene is an emerging star in biomedical field as it exhibits exceptional thermal, electrical and optical properties. Here, we review application of graphene-based materials in developing biosensing devices for the detection of different cancer biomarkers at concentrations down to sub-toxic levels. Different analytical methodologies chosen for sensing have been undertaken and their performance and background have been discussed. The trend of use of these methodologies can also be perceived from the graphical data presented.
Silicon-based material is considered to be one of the most promising anodes for the next-generation lithium-ion batteries (LIBs) due to its rich sources, non-toxicity, low cost and high theoretical specific capacity. However, it cannot maintain a stable electrode structure during repeated charge/discharge cycles, and therefore long cycling life is difficult to be achieved. To address this problem, herein a simple and efficient method is developed for the fabrication of an integrated composite anode consisting of SiO-based active material and current collector, which exhibits a core–shell structure with nitrogen-doped carbon coating on SiO/P micro-particles. Without binder and conductive agent, the volume expansion of SiO active material in the integrated composite anode is suppressed to prevent its pulverization. At a current density of 500 mA·g−1, this integrated composite anode exhibits a reversible specific capacity of 458 mA·h·g−1 after 200 cycles. Furthermore, superior rate performance and cycling stability are also achieved. This work illustrates a potential method for the fabrication of integrated composite anodes with superior electrochemical properties for high-performance LIBs.
A ternary single-walled carbon nanotubes/RuO2/polyindole (SWCNT/RuO2/PIn) nanocomposite was fabricated by the oxidation polymerization of indole on the prefabricated SWCNT/RuO2 binary nanocomposites. The nanocomposite was measured by FTIR, XRD, SEM, TEM, EDS and XPS, together with the electrochemical technique. The electrochemical results demonstrated that the symmetric supercapacitor used SWCNT/RuO2/PIn as electrodes presented 95% retention rate after 10000 cycles, superior capacitive performance of 1203 F·g−1 at 1 A·g−1, and high energy density of 33 W·h·kg−1 at 5000 W·kg−1. The high capacitance performance of SWCNT/RuO2/PIn nanocomposite was mainly ascribed to the beneficial cooperation effect among components. This indicated that the SWCNT/RuO2/PIn nanocomposite would be a good candidate for high-performance supercapacitors.
Dispersed TiO2 hollow spheres were successfully prepared which was obtained via Ostwald ripening under solvothermal conditions without any templates or surfactants. Then, the AgI/TiO2 was synthesized by the deposition−precipitation process. Finally, Ag/AgI/TiO2 was obtained by a photocatalytic reduction way. Their characteristics were analyzed by XRD, SEM, HRTEM, N2 adsorption−desorption measurements and UV-vis absorption spectra. To demonstrate the potential applications of such composites, their antibacterial activity against Escherichia coli (E. coli) was studied by microcalorimetry for the first time, and their photocatalytic performance for degradation of different organic dyes under simulated UV and visible light was discussed. The results indicated that Ag/AgI/TiO2 hollow spheres revealed elevated antibacterial and photocatalytic activity because of their unique morphology, hollow structure and high surface area. The mechanism of the excellent antibacterial and photocatalytic activity of Ag/AgI/TiO2 hollow spheres are discussed which are attributed to the synergetic effect of Ag, AgI and TiO2. It suggested that the new Ag/AgI/TiO2 photocatalyst has broad application prospects in solar cell, sensor, antibacterial, catalysis and nanotechnology.
Upconversion (UC) lanthanide nanomaterials have attracted enormous attention in the last two decades thanks to their unique ability to convert low-energy infrared photons into high-energy photons. In this mini-review, we briefly discussed the recent achievements related to the direct utilization of UC optical nanomaterials for photocatalysis and photovoltaic applications. In particular, selected examples of UC-containing devices/nanocomposites with improved performance were covered. In addition, we outlined some challenges and future trends associated with the widespread usage of UC nanomaterials.