This paper describes the mechanical properties under nanoindentation of a new glassy alloy with a nominal composition of Ni60Nb37B3, in the form of melt-spun ribbons and 1-mm-thick copper mold-cast sheets. The alloy composition was designed based on the synergy between the topological instability criterion and the difference in electronegativity among the elements. X-ray diffraction and scanning electron microscopy analyses confirmed that both ribbon and sheet samples possess totally amorphous structures with relatively high thermal stability (supercooled liquid region of about 60 K), as evaluated by differential scanning calorimetry (DSC). Nanoindentation tests revealed that the hardness of this alloy, about 15 GPa, is among the highest reported for metallic glasses. The elastic modulus of the cast sheet is higher and its hardness is similar to that of the ribbon. This correlates well with the different amounts of frozen-in free volume in both types of samples detected by DSC.

The present work demonstrates an isothermal reversible variation of magnetization in nanoporous Pd67Ni33 alloy during continuous charging and discharging of the alloy electrode in 1-M KOH solution. A custom-built electrochemical cell, containing the sample as working electrode performed the in situ charging experiments inside an extraction magnetometer at a constant applied magnetic field. The metal–electrolyte response was examined by varying the electrode potential, which apart from polarizing nanoporous structure, may also lead to electrodissociation of the electrolyte medium, being aqueous in nature. The result therefore analyzed hydrogenation as the key parameter for the observed reversible magnetization in the transition metal alloy at room temperature. In addition, electrochemical reactivity due to surface oxidation at the positive potential has been discussed, considering that a change in the band structure is also possible at the negative potential regime due to hydrogenation through cyclic voltammetry study.

Molybdenum trioxide nanostructures were synthesized, to make highly friction resistant molybdenum disulfide, by low temperature hydrothermal reaction without using any template or catalyst. The as-synthesized materials were sulfided with H2S at 400 and 800 °C. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier-transform infra-red spectroscopy, and thermogravimetric analysis were used for the physical characterization of the materials. The oxide material is highly crystalline with unique morphology. The factors affecting the size and shape of the synthesized materials were studied in detail. The crystalline nature of the materials decreased after the sulfidation process at 800 °C without any change in morphology. The wear resistance and lubricity of the material were studied under harsh conditions. The comparative study of these materials with MoS2 prepared by the hard templating method (using mesoporous silica template) reveals that the new material synthesized by direct hydrothermal route is pure phase and has better wear resistance and antifriction properties. Ultra high stability of the material is the most distinguished property of the material synthesized.

Nano-structured graphene has recently attracted extraordinary attention due to its potential use as an electronic or spintronic material. We investigated the electrical conductivities of antidot and Ar-sputtered graphene samples under a magnetic field in terms of the carrier density. Antidot samples exhibit conductivity that is well explained by charged impurity scattering, which is associated with intravalley scattering. This suggestion is supported by the low intensity of the Raman D band, which is related to intervalley scattering induced by structural defects. In contrast, Ar-sputtered samples show a strong D band and conductivity that is affected by defect scattering. The difference in the main scattering mechanism between the two types of samples appears as Shubnikov-de Haas oscillations at high magnetic fields, which are observed in antidot samples but not in Ar-sputtered samples. Furthermore, an analysis of weak localization effects in both samples at low fields reveals that intra- and intervalley scatterings play significant roles in antidot and Ar-sputtered samples, respectively.

The removal of oil spills or oily organic solvents from water surface is a great technological challenge for environmental protection. Here, a facile method to prepare superhydrophobic and superoleophilic sponge for fast and selective removal of oils from water surface has been reported. The as-prepared sponge exhibited superhydrophobic property with the water contact angle around 165°, which can be used for the absorption of oil spills or oily organic solvents. Furthermore, the resultant sponge showed good durability toward temperature. This fabrication technique is easy to grasp and to be extended. So we believe that this new functionalized sponge could be realized for the large-scale commercialized production.

Zr-based bulk metallic glasses (BMGs) exhibit superior physical and chemical properties in comparison to their crystalline counterparts. In the present work, drilling behavior of Zr57.5Cu11.2Ni13.8Al17.5 BMG was investigated at various operating conditions. Drilling was performed using high-speed steel (HSS) and carbide bits. Chip morphology, chip light emission, and burr formation at various drilling parameters were studied to achieve a feasible operating condition for drilling hole without light emission, chip clogging, and debris accumulation. Short spiral chip morphology which is considered ideal in the drilling process was observed at relatively low feed rate (1.5 mm/min) and medium spindle speed (1500 rpm). This also resulted in a small amount of molten debris around the entry hole. It was observed that at the same feed rate, the gradual increase in the speed of the HSS drill bit results in more light emission from the machining surface, whereas no light emission was observed in the case of the carbide drill bit at all drilling parameters.

Ultrathin metal film dewetting continues to grow in interest as a simple means to make nanostructures with well-defined properties. Here, we explored the quantitative thickness-dependent dewetting behavior of Au films under nanosecond (ns) pulsed laser melting on glass substrates. The trend in particle spacing and diameter in the thickness range of 3–16 nm was consistent with predictions of the classical spinodal dewetting theory. The early stage dewetting morphology of Au changed from bicontinuous-type to hole-like at a thickness between 8.5 and 10 nm, and computational modeling of nonlinear dewetting dynamics also captured the bicontinuous morphology and its evolution quite well. The thermal gradient forces were found to be significantly weaker than dispersive forces in Au due to its large effective Hamaker coefficient. This also resulted in Au dewetting length scales being significantly smaller than those of other metals such as Ag and Co.

InN films have been grown on sapphire substrates nitrided by N plasma with different durations by radio-frequency plasma assisted molecular beam epitaxy (RF-MBE). In-depth investigation reveals that AlN is generated on a sapphire surface during the nitridation, and 60 min nitridation helps in the formation of an ordered and flat AlN interlayer between the substrate and the InN film, which improves the surface migration of In atoms on the substrate, and consequently helps in obtaining a single-crystalline c-plane InN film of high quality with 1.0 × 1019 cm−3 carrier density and 1350 cm2/(V·s) carrier mobility. Too short nitridation duration will result in a polycrystalline InN film, and too long nitridation duration will damage the surface quality of the newly generated AlN interlayer which consequently deteriorates the InN film quality. Control of the AlN interlayer quality plays a critical role in the growth of a high-quality InN epitaxial film on the sapphire substrate.

Carbon microspheres (CMSs) were oxidized by a mixture of concentrated sulfuric acid and nitric acid (ratio of 3:1 by volume) to improve their surface activity. Then, poly(3-hexylthiophene):CMSs (P3HT:CMSs) composite film was prepared by spin-coating method with oxidized CMSs and P3HT mixture chloroform solution. Energy levels of oxidized CMSs were investigated by cyclic voltammetry, the morphology of the composite films was characterized by atomic force microscopy, optical performance was analyzed by ultraviolet–visible spectrophotometry and fluorescent spectrometry, and microstructures of the products were characterized by Fourier transformation infrared spectrometry and x-ray diffraction. The results indicate that suspension concentration of 30 mg/mL and spinning rate of 2500 rpm were appropriate for fabricating P3HT:CMSs composite films. Optical properties of the P3HT:CMSs blends were changed by annealing. This lays an experimental foundation for fabricating active layer of polymer solar cells with high photoelectric conversion and low cost.

Atomic force microscopy (AFM) has proven useful in the investigation of porous surfaces due to its nanoscale spatial resolution, micron scale range, compatibility with nonconducting materials, and even applicability ability to biological systems since it can operate in fluids. Since AFM directly measures the surface by contact, it is particularly suited for quantifying the roughness, and more appropriately for porous and particulate materials, the surface area. In this work, a multi-scale porous material, human molar dentin, was studied with AC mode AFM (both in-air and in-liquid), enabling extensive analyses both for plain dentin as well as specimens exposed to nanoparticle TiO2 containing toothpaste to approximate personal dental hygiene. Finally, high speed AFM is also demonstrated in vitro with equivalent results, except that the time required per image is reduced by several orders of magnitude from tens of minutes to as little as 6 s. Careful implementation of AFM, both at standard and high speeds, is therefore effective for investigating highly porous materials, including biological tissue, in environmentally or physiologically relevant conditions.

A straightforward approach allowing three-dimensional (3D) visualization of subsurface deformation beneath nanoindents using reconstructed cross-sectional transmission electron microscopy (TEM) data is demonstrated. This approach relies on generating an array of nanoindents, extracting a thin (<200 nm) cross section using a focused ion beam (FIB) and imaging with a transmission electron microscope. By rotating the orientation of the FIB cross section with respect to the array of nanoindents at the optimal angle, it is guaranteed that a different section of each nanoindent's subsurface plastic zone is contained within the final cross section. Subsequently, TEM images corresponding to different sections are reconstructed into a 3D image of a representative nanoindentation plastic zone. This approach can be extended to any array of nominally identical features that can be patterned with regular spacing and included in a single FIB cross section. It was also found to significantly enhance the throughput of preparing routine site-specific TEM samples, even when 3D visualization is not necessary. In this article, the approach is applied to visualize the plastic zones beneath nanoindents in GaAs (001), for loads of 50–1000 µN.

Tissue engineering principles suggest the formation of 3D scaffolds based on polymer fibers and adhesive proteins. These scaffolds aim to mimic the native extracellular matrix and thus providing a favorable environment for cell attachment and proliferation. The application of an electric field (EF) can influence the quantity and the spatial orientation/conformation of adsorbed proteins, which could lead to changes in their functions. We study the influence of alternating current (AC) EF on the adsorption of fibronectin onto poly(etherimide) (PEI) electrospun fiber materials in 3D structures and subsequent cell adhesion. The results are compared with 2D PEI material and glass surface. 3D scaffolds adsorbed a lower amount of fibronectin than 2D film or glass. Application of AC EF with a frequency of 1 Hz decreased the adsorption of fibronectin. Cell adhesion on 3D materials was reduced compared with 2D film and glass. The application of EF with frequencies between 1 and 10 Hz improved cell adhesion on both 2D and 3D materials.

The liquid phase plasma reduction method has been applied to prepare silver nanoparticles from a solution of silver nitrate (AgNO3) using a bipolar pulsed electrical discharge system. The excited states of atomic silver, hydrogen and oxygen as well as the molecular bands of hydroxyl radicals were detected in the emission spectra. As the discharge duration increased up to 10 min, silver particle peaks produced by surface plasmon absorption were observed around 430 nm. Both the particle size and the particle numbers were observed to increase with the length of the plasma treatment time and with the initial AgNO3 concentration. Spherical nanoparticles of about 5–20 nm in size were obtained with the discharging time of 5 min, whereas aggregates of nanoparticles of about 10–50 nm in size were mainly produced with the discharging time of 20 min. The cationic surfactant of cetyltrimethylammonium bromide (CTAB) added with the CTAB/AgNO3 molar ratio of 30% was shown to inhibit nanoparticle aggregation.

Bismuth vanadate (BiVO4) hierarchical spheres were synthesized successfully by a facile hydrothermal approach without any additive by using novel vanadium-based nanosheets as precursors. The results indicated that as-prepared BiVO4 samples have monoclinic structure with high crystallinity. Scanning electron microscopy images show that the spheres were self-assembled by dozens of nanosheets with good dispersibility and uniform particle size. Meanwhile, the photocatalytic activities of the resulting BiVO4 were evaluated by photodegradation of methylene blue (MB) under visible light irradiation and exhibited enhanced catalytic efficiency. The excellent performance can be attributed to the high purity, the huge specific surface area, and the novel hierarchical structure. It was also found that the photodegradation of dye pollution is attributed to the oxidation process of the generated hydroxyl radicals and the action of ${\rm{h}}_{{\rm{vb}}}^{\rm{ + }}$ via direct hole oxidation.

A functionalization method for the specific and selective immobilization of the streptavidin (SA) protein on semiconductor nanowires (NWs) was developed. Silicon (Si) and silicon carbide (SiC) NWs were functionalized with 3-aminopropyltriethoxysilane (APTES) and subsequently biotinylated for the conjugation of SA. Existence of a thin native oxide shell on both Si and SiC NWs enabled efficient binding of APTES with the successive attachment of biotin and SA as was confirmed with x-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and atomic force microscopy. Fluorescence microscopy demonstrated nonspecific, electrostatic binding of the SA and the bovine serum albumin (BSA) proteins to APTES-coated NWs. Inhibition of nonspecific BSA binding and enhancement of selective SA binding were achieved on biotinylated NWs. The biofunctionalized NWs have the potential to be used as biosensing platforms for the specific and selective detection of proteins.

In this article, we review our recent research efforts on the synthesis, crystallinity control, and photocatalysis of nanostructured titanium dioxide (TiO2) shells. First, we introduce several synthetic methods for preparing TiO2 shell structures using either template-free or template-assisted approaches. Several methods to change the structures from amorphous to crystalline and subsequently ways to enhance the crystallinity are then discussed, including those involving the “silica-protected calcination” and “partial etching and recalcination” strategies. We also discuss the photocatalytic applications of the TiO2 nanoshells and the methods for improving their catalytic activities. Finally, we conclude with a summary and our perspective on the further development of the nanostructured TiO2 shells. It is believed that more rational design and modification strategies such as well-controlled nonmetal doping, plasmonic metal decoration and the hybridization with other semiconducting materials will significantly enhance the photocatalytic efficiency of TiO2-based catalyst materials.

Suction casting (SC) and centrifugal casting (CC) are two common special casting processes. The influences of SC and CC on the microstructural development of Cu–10Al–4Fe–4Ni aluminum bronzes were investigated with continuous cooling method. The results indicate that α, β′, KII, and KIII phases are observed in the quasicast microstructure via the SC process with the precipitation sequence of KII → α → KIII. Additionally, KI and KIV are observed in the quasicast microstructure via the CC process with the precipitation sequence of α + KⅠ → KII → KIV → KIII. Phase initial precipitation temperatures of the CC process are higher than that of the SC process, especially for α phase. As the quenching temperature decreases, the hardness of both alloys shows a rapid decline trend and finally reaches a steady state. It is found that the eutectoid decomposition (β → α + KIII) barely affects the hardness of the alloys.