Abstract: Metal and semiconductor oxides are ubiquitous electronic materials. Normally insulating, oxides can change behavior under high electric fields—through ‘electroforming’ or ‘breakdown’—critically affecting CMOS (complementary metal‐oxide‐semiconductor) logic, DRAM (dynamic random access memory) and flash memory, and tunnel barrier oxides. An initial irreversible electroforming process has been invariably required for obtaining metal oxide resistance switches, which may open urgently needed new avenues for advanced computer memory and logic circuits including ultra-dense non-volatile random access memory (NVRAM) and adaptive neuromorphic logic circuits. This electrical switching arises from the coupled motion of electrons and ions within the oxide material, as one of the first recognized examples of a memristor (memory‐resistor) device, the fourth fundamental passive circuit element originally predicted in 1971 by Chua. A lack of device repeatability has limited technological implementation of oxide switches, however. Here we explain the nature of the oxide electroforming as an electro-reduction and vacancy creation process caused by high electric fields and enhanced by electrical Joule heating with direct experimental evidence. Oxygen vacancies are created and drift towards the cathode, forming localized conducting channels in the oxide. Simultaneously, O 2− ions drift towards the anode where they evolve O2 gas, causing physical deformation of the junction. The problematic gas eruption and physical deformation are mitigated by shrinking to the nanoscale and controlling the electroforming voltage polarity. Better yet, electroforming problems can be largely eliminated by engineering the device structure to remove ‘bulk’ oxide effects in favor of interface-controlled electronic switching.

Abstract: The elastic moduli of single layer graphene sheet (SLGS) have been a subject of intensive research in recent years. Calculations of these effective properties range from molecular dynamic simulations to use of structural mechanical models. On the basis of mathematical models and calculation methods, several different results have been obtained and these are available in the literature. Existing mechanical models employ Euler-Bernoulli beams rigidly jointed to the lattice atoms. In this paper we propose truss-type analytical models and an approach based on cellular material mechanics theory to describe the in-plane linear elastic properties of the single layer graphene sheets. In the cellular material model, the C-C bonds are represented by equivalent mechanical beams having full stretching, hinging, bending and deep shear beam deformation mechanisms. Closed form expressions for Young's modulus, the shear modulus and Poisson's ratio for the graphene sheets are derived in terms of the equivalent mechanical C-C bond properties. The models presented provide not only quantitative information about the mechanical properties of SLGS, but also insight into the equivalent mechanical deformation mechanisms when the SLGS undergoes small strain uniaxial and pure shear loading. The analytical and numerical results from finite element simulations show good agreement with existing numerical values in the open literature. A peculiar marked auxetic behaviour for the C-C bonds is identified for single graphene sheets under pure shear loading.

Abstract: A new fabrication method to produce homogeneously fluorescent nanodiamonds with high yields is described. The powder obtained by high energy ball milling of fluorescent high pressure, high temperature diamond microcrystals was converted in a pure concentrated aqueous colloidal dispersion of highly crystalline ultrasmall nanoparticles with a mean size less than or equal to 10 nm. The whole fabrication yield of colloidal quasi-spherical nanodiamonds was several orders of magnitude higher than those previously reported starting from microdiamonds. The results open up avenues for the industrial cost-effective production of fluorescent nanodiamonds with well-controlled properties.

Abstract: Solar cells based on a mesoporous structure of TiO2 and the polysulfide redox electrolyte were prepared by direct adsorption of colloidal CdSe quantum dot light absorbers onto the oxide without any particular linker. Several factors cooperate to improve the performance of quantum-dot-sensitized solar cells: an open structure of the wide bandgap electron collector, which facilitates a higher covering of the internal surface with the sensitizer, a surface passivation of TiO2 to reduce recombination and improved counter electrode materials. As a result, solar cells of 1.83% efficiency under full 1 sun illumination intensity have been obtained. Despite a relatively large short circuit current (J(sc) = 7.13 mA cm(-2)) and open circuit voltage (V(oc) = 0.53 V), the colloidal quantum dot solar cell performance is still limited by a low fill factor of 0.50, which is believed to arise from charge transfer of photogenerated electrons to the aqueous electrolyte.

Abstract: In this paper, a self-sensing carbon nanotube (CNT)/cement composite is investigated for traffic monitoring. The cement composite is filled with multi-walled carbon nanotubes whose piezoresistive properties enable the detection of mechanical stresses induced by traffic flow. The sensing capability of the self-sensing CNT/cement composite is explored in laboratory tests and road tests. Experimental results show that the fabricated self-sensing CNT/cement composite presents sensitive and stable responses to repeated compressive loadings and impulsive loadings, and has remarkable responses to vehicular loadings. These findings indicate that the self-sensing CNT/cement composite has great potential for traffic monitoring use, such as in traffic flow detection, weigh-in-motion measurement and vehicle speed detection.

Abstract: We report nanoscale patterning of graphene using a helium ion microscope configured for lithography. Helium ion lithography is a direct-write lithography process, comparable to conventional focused ion beam patterning, with no resist or other material contacting the sample surface. In the present application, graphene samples on Si/SiO2 substrates are cut using helium ions, with computer controlled alignment, patterning, and exposure. Once suitable beam doses are determined, sharp edge profiles and clean etching are obtained, with little evident damage or doping to the sample. This technique provides fast lithography compatible with graphene, with approximately 15 nm feature sizes.

Abstract: We report the properties of a field effect transistor (FET) and a gas sensor based on CuO nanowires. CuO nanowire FETs exhibit p-type behavior. Large-scale p-type CuO nanowire thin-film transistors (104 devices in a 25?mm2 area) are fabricated and we effectively demonstrate their enhanced performance. Furthermore, CuO nanowire exhibits high and fast response to CO gas at 200??C, which makes it a promising candidate for a poisonous gas sensing nanodevice.

Abstract: Nanoparticles rapidly interact with the proteins present in biological fluids, such as blood. The proteins that are adsorbed onto the surface potentially dictate the biokinetics of the nanomaterials and their fate in vivo. Using nanoparticles with different sizes and surface characteristics, studies have reported the effects of physicochemical properties on the composition of adsorbed plasma proteins. However, to date, few studies have been conducted focusing on the nanoparticles that are commonly exposed to the general public, such as the metal oxides. Using previously established ultracentrifugation approaches, two-dimensional gel electrophoresis and mass spectrometry, the current study investigated the binding of human plasma proteins to commercially available titanium dioxide, silicon dioxide and zinc oxide nanoparticles. We found that, despite these particles having similar surface charges in buffer, they bound different plasma proteins. For TiO2, the shape of the nanoparticles was also an important determinant of protein binding. Agglomeration in water was observed for all of the nanoparticles and both TiO2 and ZnO further agglomerated in biological media. This led to an increase in the amount and number of different proteins bound to these nanoparticles. Proteins with important biological functions were identified, including immunoglobulins, lipoproteins, acute-phase proteins and proteins involved in complement pathways and coagulation. These results provide important insights into which human plasma proteins bind to particular metal oxide nanoparticles. Because protein absorption to nanoparticles may determine their interaction with cells and tissues in vivo, understanding how and why plasma proteins are adsorbed to these particles may be important for understanding their biological responses.

Abstract: Nanosilver is increasingly used in the food industry and biomedical applications. A lot of studies have been done to investigate the potential toxicity of nanosilver. But information on whether or how nanosilver particles bring changes in genetic materials remains scant. In this study, the replication fidelity of the rpsL gene was quantified when nanosilver particles were present in polymerase chain reactions (PCRs) or cell cultures of E. coli transformed with the wild-type rpsL gene. Three types of nanosilver (silver nanopowder, SN; silver-copper nanopowder, SCN; and colloidal silver, CS) were tested. The results showed that the replication fidelity of the rpsL gene was differentially compromised by all three kinds of nanosilver particle compared with that without nanosilver. This assay could be expanded and applied to any other materials to preliminarily assess their potential long-term toxicity as a food additive or biomedical reagent. Moreover, we found that nanosilver materials bind with genomic DNA under atomic force microscopy, and this might be an explanation for the compromised DNA replication fidelity.

Abstract: Glucose-capped gold nanoparticles (Glu-GNPs) have been used to improve cellular targeting and radio-sensitization. In this study, we explored the mechanism of Glu-GNP enhanced radiation sensitivity in radiation-resistant human prostate cancer cells. Cell survival and proliferation were measured using MTT and clonogenic assay. Flow cytometry with staining by propidium iodide (PI) was performed to study the cell cycle changes induced by Glu-GNPs, and western blotting was used to determine the expression of p53 and cyclin proteins that correlated to cell cycle regulation. With 2 Gy of ortho-voltage irradiation, Glu-GNP showed a 1.5-2.0 fold enhancement in growth inhibition when compared to x-rays alone. Comparing the cell cycle change, Glu-GNPs induced acceleration in the G0/G1 phase and accumulation of cells in the G2/M phase at 29.8% versus 18.4% for controls at 24 h. G2/M arrest was accompanied by decreased expression of p53 and cyclin A, and increased expression of cyclin B1 and cyclin E. In conclusion, Glu-GNPs trigger activation of the CDK kinases leading to cell cycle acceleration in the G0/G1 phase and accumulation in the G2/M phase. This activation is accompanied by a striking sensitization to ionizing radiation, which may have clinical implications.

Abstract: With extensive use of metal oxide nanoparticles (NPs) in a variety of applications comes a higher potential of release into aquatic environments. NPs tend to form much larger aggregates in water, which are expected to settle down to the bottom of the water column and possibly get mixed with the sediments. However, little is known about the environmental impacts and biological effects of these aggregated NPs in the sediment column. In this study, we examined the sedimentation of nanoscale ZnO particles (nZnO) in zebrafish culture medium, and assessed the toxicity of settled nZnO aggregates on developing zebrafish embryos and larvae. Given the known dissolution of nZnO particles to release Zn(2+), we also assessed the toxic effect of soluble Zn(2+) in this organism. We demonstrated that within 48 h, micron-sized nZnO aggregates were formed and settled out of the culture medium. These aggregates were found to exert dose-dependent toxicity to zebrafish embryos and larvae, reducing the hatching rate and causing pericardial edema. The observed toxicity of the nZnO aggregates was not likely a result solely of particle dissolution, as soluble Zn(2+) alone caused much less toxicity to zebrafish embryos than nZnO. Instead, the combination of both nZnO and Zn(2+) may contribute to the embryonic toxicity, possibly by increasing reactive oxidative species (ROS) and/or compromising the cellular oxidative stress response. Interestingly, we demonstrated that one type of formulated sediments could mitigate the toxicity of nZnO aggregates, highlighting a possible countermeasure to reduce the adverse impact of nZnO aggregates on the environment.

Abstract: Oral fast-dissolving drug delivery membranes (FDMs) for poorly water-soluble drugs were prepared via electrospinning technology with ibuprofen as the model drug and polyvinylpyrrolidone (PVP) K30 as the filament-forming polymer and drug carrier. Results from differential scanning calorimetry, x-ray diffraction, and morphological observations demonstrated that ibuprofen was distributed in the ultrafine fibers in the form of nanosolid dispersions and the physical status of drug was an amorphous or molecular form, different from that of the pure drug and a physical mixture of PVP and ibuprofen. Fourier-transform infrared spectroscopy results illustrated that the main interactions between PVP and ibuprofen were mediated through hydrogen bonding. Pharmacotechnical tests showed that FDMs with different drug contents had almost the same wetting and disintegrating times, about 15 and 8 s, respectively, but significantly different drug dissolution rates due to the different physical status of the drug and the different drug-release-controlled mechanisms. 84.9% and 58.7% of ibuprofen was released in the first 20 s for FDMs with a drug-to-PVP ratio of 1:4 and 1:2, respectively. Electrospun ultrafine fibers have the potential to be used as solid dispersions to improve the dissolution profiles of poorly water-soluble drugs or as oral fast disintegrating drug delivery systems.

Abstract: Non-spherical nano-/micro-particles can drift laterally (hydrodynamic margination) in a linear laminar flow under the concurrent effect of hydrodynamic and inertial forces. Such a feature can be exploited in the rational design of particle-based intravascular and pulmonary delivery systems and for designing new flow fractioning systems for high-throughput particle separation. A general approach is presented to predict the marginating behavior of non-spherical particles. The lateral drift velocity is shown to depend on the particle Stokes number Sta and to grow with the size, density and rotational inertia of the particle. Elongated particles, in particular, low aspect ratio discoidal particles, exhibit the largest propensity to marginate in a linear laminar flow. In the blood microcirculation, at low shear rates (S<100 s−1), non-spherical particles oscillate around their trajectory and margination can only be achieved through the application of external force fields (gravitational, magnetic); whereas for larger S (100 s−1