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The relaxor-type behavior, electrical polarization buildup, and switching in 0.92Pb(Zn(1/3)Nb(2/3))O(3)-0.08PbTiO(3) nanostructured ceramics with a grain size of approximately 20 nm is reported for the first time. This composition presents the highest-known piezoelectric coefficients, yet phase stability is an issue. Ceramics can only be obtained by the combination of mechanosynthesis and spark-plasma sintering. The results raise the possibility of using nanoscale, perovskite-relaxor-based morphotropic-phase-boundary materials for sensing and actuation in nanoelectromechanical systems.

A new kind of multifunctional Co0.85 Se-Fe3 O4 nanocomposites is synthesized by loading Fe3 O4 nanoparticles (NPs) with a size of about 5 nm on the surface of Co0.85 Se nanosheets under hydrothermal conditions without using any surfactant or structure-directing agents. The Co0.85 Se-Fe3 O4 nanocomposite exhibits remarkable catalytic performance for hydrogenation of p-nitrophenol (4-NP) at room temperature and good adsorption behavior for methylene blue trihydrate in water. This nanocomposite also shows a high specific surface area and magnetic separation capability for recyclable utilization. The enhanced performances both in catalysis and adsorption are better than either individual component of Co0.85 Se nanosheets or Fe3 O4 nanoparticles, demonstrating the possibility for designing new multifunctional nanocomposites with improved performances for catalysis, adsorbents, and other applications.

Fabrication of a high-temperature deep-ultraviolet photodetector working in the solar-blind spectrum range (190-280 nm) is a challenge due to the degradation in the dark current and photoresponse properties. Herein, β-Ga2 O3 multi-layered nanobelts with (l00) facet-oriented were synthesized, and were demonstrated for the first time to possess excellent mechanical, electrical properties and stability at a high temperature inside a TEM studies. As-fabricated DUV solar-blind photodetectors using (l00) facet-oriented β-Ga2 O3 multi-layered nanobelts demonstrated enhanced photodetective performances, that is, high sensitivity, high signal-to-noise ratio, high spectral selectivity, high speed, and high stability, importantly, at a temperature as high as 433 K, which are comparable to other reported semiconducting nanomaterial photodetectors. In particular, the characteristics of the photoresponsivity of the β-Ga2 O3 nanobelt devices include a high photoexcited current (>21 nA), an ultralow dark current (below the detection limit of 10(-14) A), a fast time response (<0.3 s), a high Rλ (≈851 A/W), and a high EQE (∼4.2 × 10(3) ). The present fabricated facet-oriented β-Ga2 O3 multi-layered nanobelt based devices will find practical applications in photodetectors or optical switches for high-temperature environment.

The successful covalent functionalization of quartz and n-type 6H-SiC with organosilanes and benzo[ghi]perylene-1,2-dicarboxylic dye is demonstrated. In particular, wet-chemically processed self-assembled layers of aminopropyltriethoxysilane (APTES) and benzo[ghi]perylene-1,2-dicarboxylic anhydride are investigated. The structural and chemical properties of these layers are studied by contact angle measurements, attenuated total reflection infrared (ATR-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The optical properties are measured by confocal microscopy. The wetting angles observed for the organic layers are α = 68° for the APTES-functionalized surface, while angles of α = 85° and 78° are determined for dye-functionalized quartz and 6H-SiC surfaces, respectively. However, not all amino groups of the APTES-functionalized surfaces react to bind dye molecules. Further dye functionalization is not uniform throughout the surface, showing different island sizes of the dye and including different chemical environments. The quartz surface exhibits a higher packing density of dyes than the 6H-SiC surface. The fluorescence lifetimes of the surface-attached dye show double exponential decays of about 1.4 and 4.2 ns, largely independent of the substrates.

For the first time, a facile, one-pot hydrofluoric acid vapor-phase hydrothermal (HF-VPH) method is demonstrated to directly grow single-crystalline anatase TiO(2) nanosheets with 98.2% of exposed {001} faceted surfaces on the Ti substrate via a distinctive two-stage formation mechanism. The first stage produces a new intermediate crystal (orthorhombic HTiOF(3) ) that is transformed into anatase TiO(2) nanosheets during the second stage. The findings reveal that the HF-VPH reaction environment is unique and differs remarkably from that of liquid-phase hydrothermal processes. The uniqueness of the HF-VPH conditions can be readily used to effectively control the nanostructure growth.

The properties of InAs quantum dot formation on GaAs(001) using STM within a MBE growth chamber were described. InAs deposited onto an As-terminated GaAs(001) initially forms a two-dimensional (2D) wetting layer (WL). The overall morphology revealed by STMBE is very similar to the results of quenched mode STM. It was shown that it is possible to estimate the additional surface coverage as a function of InAs deposited by comparing the step-terrace-island structures of images in the same location.

Visible-light photocatalysis that can directly harvest energy from incoming solar energy offers a desirable way to solve energy and environment issues. On page 3951, J. L. Gong and co-workers report the preparation of an efficient homotype Ag3PO4 /BiVO4 heterojunction photocatalyst via rational structure design. The Ag3PO4 nanoparticles are preferentially deposited on the highlyactive BiVO4 (040) facets via a surfactantmediated mechanism. The Ag3PO4 /BiVO4 photocatalyst shows high charge separation efficiency as well as an enhanced visiblelight response and thus possesses excellent visible light photocatalytic activity. The capability of synthesizing a highly visible light active and stable heterojunction photocatalyst is useful for other solar conversion applications, such as PEC water splitting, dye-sensitized solar cells and photovoltaic devices.

An efficient homotype Ag3 PO4 /BiVO4 heterojunction photocatalyst is described. Ag3 PO4 nanoparticles preferentially deposit on the highly active BiVO4 (040) facets by means of heterojunction construction together with morphology engineering. The Ag3 PO4 /BiVO4 photocatalyst shows high charge separation efficiency as well as enhanced visible-light response ability and thus possesses superior visible light photocatalytic activity.

The dimension-controlled synthesis of CdS nanocrystals in the strong quantum confinement regime is reported. Zero-, one-, and two-dimensional CdS nanocrystals are selectively synthesized via low-temperature reactions using alkylamines as surface-capping ligands. The shape of the nanocrystals is controlled systematically by using different amines and reaction conditions. The 2D nanoplates have a uniform thickness as low as 1.2 nm. Furthermore, their optical absorption and emission spectra show very narrow peaks indicating extremely uniform thickness. It is demonstrated that 2D nanoplates are generated by 2D assembly of CdS magic-sized clusters formed at the nucleation stage, and subsequent attachment of the clusters. The stability of magic-sized clusters in amine solvent strongly influences the final shapes of the nanocrystals. The thickness of the nanoplates increases in a stepwise manner while retaining their uniformity, similar to the growth behavior of inorganic clusters. The 2D CdS nanoplates are a new type of quantum well with novel nanoscale properties in the strong quantum confinement regime.

The synthesis of 1,18-nucleotide-appended bolaamphiphiles (1, 2, 4, and 6) is reported, in which a 3'-phosphorylated guanidine, adenosine, thymidine, or cytidine is connected to each end of an octadecamethylene chain. Single-component self-assemblies and binary self-assemblies with the complementary oligonucleotides dC(20), dT(20), dA(20), and dG(20) are studied by atomic force microscopy, powder X-ray diffraction analysis, temperature-dependent UV absorption, circular dichroism, and attenuated total-reflection Fourier-transform infrared spectroscopy. The single-component self-assembly of 1 forms a two-dimensional sheet, whereas the binary self-assembly 1/dC(20) gives helical nanofibers. Non-helical nanofibers are observed for the single-component self-assemblies of 2 and 4, and helical nanofibers form from the binary self-assembly 2/dT(20). Interestingly, helical nanorod structures are obtained from the binary self-assembly 4/dA(20), and the aligned nanorods form a nematic phase. The single-component and binary self-assemblies from 6 give unilamellar vesicles owing to a lack of stacking interaction between the cytosine moieties.

The influence of molecular structure on the mechanical properties of self-assembled 1,3,5-benzenetrisamide nanofibers is investigated. Three compounds with different amide connectivity and different alkyl substituents are compared. All the trisamides form well-defined fibers and exhibit significant differences in diameters of up to one order of magnitude. Using nanomechanical bending experiments, the rigidity of the nanofibers shows a difference of up to three orders of magnitude. Calculation of Young's modulus reveals that these differences are a size effect and that the moduli of all systems are similar and in the lower GPa range. This demonstrates that variation of the molecular structure allows changing of the fibers' morphology, whereas it has a minor influence on their modulus. Consequently, the stiffness of the self-assembled nanofibers can be tuned over a wide range--a crucial property for applications as versatile nano- and micromechanical components.

An experiment was conducted to show that very small nanoparticles (NP) can be translocated through the air/blood barrier of the respiratory tract in significant amounts, whereas 18-nm particles are almost trapped in the lungs. Au55 (Ph2PC6H4SO3Na) 12Cl6 and Au NPs were synthesized. Both NPs were activated by neutron activation. These NPs were sealed in quartz tubes either in solid form or in aqueous suspensions and activated at a neutron flux of 10 14 cm-2s-1 at the research reactor of the Hahn-Meitner, Germany. The Np suspension was visually checked for precipitates, and also checked by examination of the UV absorption peak at 523 nm, prior to the administration to rats. The rats were sacrificed by exsanguinations under deep anesthesia through the prepared abdominal aorta 24h after NP administration. Subsequent cytotoxicity investigations with various human tumor cell lines indicated that the cytotoxicity of this compound is unexpectedly high.

Gold nanoparticles (AuNPs) are generally considered nontoxic, similar to bulk gold, which is inert and biocompatible. AuNPs of diameter 1.4 nm capped with triphenylphosphine monosulfonate (TPPMS), Au1.4MS, are much more cytotoxic than 15-nm nanoparticles (Au15MS) of similar chemical composition. Here, major cell-death pathways are studied and it is determined that the cytotoxicity is caused by oxidative stress. Indicators of oxidative stress, reactive oxygen species (ROS), mitochondrial potential and integrity, and mitochondrial substrate reduction are all compromised. Genome-wide expression profiling using DNA gene arrays indicates robust upregulation of stress-related genes after 6 and 12 h of incubation with a 2 x IC50 concentration of Au1.4MS but not with Au15MS nanoparticles. The caspase inhibitor Z-VAD-fmk does not rescue the cells, which suggests that necrosis, not apoptosis, is the predominant pathway at this concentration. Pretreatment of the nanoparticles with reducing agents/antioxidants N-acetylcysteine, glutathione, and TPPMS reduces the toxicity of Au1.4MS. AuNPs of similar size but capped with glutathione (Au1.1GSH) likewise do not induce oxidative stress. Besides the size dependency of AuNP toxicity, ligand chemistry is a critical parameter determining the degree of cytotoxicity. AuNP exposure most likely causes oxidative stress that is amplified by mitochondrial damage. Au1.4MS nanoparticle cytotoxicity is associated with oxidative stress, endogenous ROS production, and depletion of the intracellular antioxidant pool.

Rectangle-and triangle-shaped microscale graphene films are grown on epitaxial Co films deposited on single-crystal MgO substrates with (001) and (111) planes, respectively. A thin film of Co or Ni metal is epitaxially deposited on a MgO substrate by sputtering while heating the substrate. Thermal decomposition of polystyrene over this epitaxial metal film in vacuum gives rectangular or triangular pit structures whose orientation and shape are strongly dependent on the crystallographic orientation of the MgO substrate. Raman mapping measurements indicate preferential formation of few-layer graphene films inside these pits. The rectangular graphene films are transferred onto a SiO 2 /Si substrate while maintaining the original shape and field-effect transistors are fabricated using the transferred films. These findings on the formation of rectangular/triangular graphene give new insights on the formation mechanism of graphene and can be applied for more advanced/controlled graphene growth.

The cover image illustrates how target polymerase chain reaction (PCR) products shield the peroxidase mimicking activity of magnetic nanoparticles (MNPs), leading to a significantly reduced colorimetric signal as compared to the intense colorimetric response by the normal peroxidase activity of MNPs. In the case where PCR products are not formed because a target DNA is absent, MNPs display their normal peroxidase activity generating the red color. On the other hand, peroxidase activity is significantly reduced in the presence of target DNA because the resulting PCR products greatly diminish the accessibility of the colorimetric substrate, o-phenylenediamine. In addition, DNA directly adsorbs onto the surface of MNPs, leading to significant inhibition of the substrate binding to the MNPs, which is required for the peroxidaselike reaction. As a result, the colorimetric substrate is not converted to a red product, retaining its original yellow color. For more information, please read the Communication “Label-Free Colorimetric Detection of Nucleic Acids Based on Target-Induced Shielding Against the Peroxidase-Mimicking Activity of Magnetic Nanoparticles” by H. G. Park and co-workers, beginning on page 1521.

The cover illustration shows the use of ligand-patterned surfaces to study the spatio-temporal organization of integrins mediating cell adhesion on cells of the immune system. Micro-contact printing is used to fabricate large chemically confined areas containing the ligand ICAM-1. The dynamic organization of the integrin LFA-1 in living cells is monitored at the single-molecule level using total reflection microscopy. LFA-1 binding to its ligand ICAM-1 promotes the formation of nano- and microclustering on the cell surface that remains largely immobile. In contrast, in the absence of the ligand (free areas in the cover image), LFA-1 diffuses randomly without interaction with the cytoskeleton. This simple experimental approach allows the study of the intricate coupling between spatial organization, lateral diffusion, and conformational states of receptors orchestrating cell adhesion. For more information, please read the Communication “Dynamic Re-organization of Individual Adhesion Nanoclusters in Living Cells by Ligand-Patterned Surfaces” by M. F. Garcia-Parajo et al., beginning on page 1258.

Specifically targeting and manipulating living cells is a key challenge in biomedicine and in cancer research in particular. Several studies have shown that nanoparticles irradiated by intense lasers are capable of conveying damage to nearby cells for various therapeutic and biological applications. In this work ultrashort laser pulses and gold nanospheres are used for the generation of localized, nanometric disruptions on the membranes of specifically targeted cells. The high structural stability of the nanospheres and the resonance pulse irradiation allow effective means for controlling the induced nanometric effects. The technique is demonstrated by inducing desired death mechanisms in epidermoid carcinoma and Burkitt lymphoma cells, and initiating efficient cell fusion between various cell types. Main advantages of the presented approach include low toxicity, high specificity, and high flexibility in the regulation of cell damage and cell fusion, which would allow it to play an important role in various future clinical and scientific applications.

The cover picture shows how single-stranded DNA can be effectively and promptly adsorbed onto functionalized graphene via hydrophobic and π-stacking interactions. Interestingly, the absorbed single-stranded DNA can be effectively protected from enzymatic cleavage, which is encouraging for potential graphene-based biomedical applications involving complex cellular and biofluids samples. Anisotropy, fluorescence, NMR, and CD studies suggest that single-stranded DNA adsorbed onto functionalized graphene forms strong molecular interactions that prevent DNase I from approaching the constrained DNA. Furthermore, constraining a single-stranded DNA probe on graphene improves the specificity of its response to a target sequence. The unique features of DNA–graphene interactions are promising traits that may be exploited to construct DNA–graphene nanobiosensors with facile design, excellent sensitivity, selectivity, and biostability. For more information, please read the Communication “Constraint of DNA on Functionalized Graphene Improves its Biostability and Specificity” by Y. Lin et al., beginning on page 1205.

A generalized approach to form hybrid organic-inorganic nanocomposite microparticles via the structural reorganization of Pickering emulsion templates is described by V. M. Rotello and co-workers on page 1302. Hydrophilic nanoparticles assembled at the oil/water interface react with a hydrophobic polymer, pulling the particles into the oil core. The combined self-assembly and in-situ covalent conjugation strategy provides a facile method to generate robust porous nanocomposites with excellent stability and high capacity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Creep in graphene platelet-epoxy nanocomposites is significantly slowed down relative to the unfilled epoxy case. This effect is observed primarily at elevated temperatures and when the material is subjected to higher stress. Carbon nanotube-epoxy composites prepared under similar conditions do not exhibit this phenomenon. Fracture surfaces of graphene platelet-epoxy samples, shown here, indicate that graphene flakes also retard the propagation of cracks, while fiber-like ligaments form during the separation process linking the two crack faces and enhancing the material toughness.

A method for forming efficient, ultrathin GaN light-emitting diodes (LEDs) and for their assembly onto foreign substances is reported. The LEDs have lateral dimensions ranging from ~1 mm × 1 mm to ~25 μm × 25 μm. Quantitative experimental and theoretical studies show the benefits of small device geometry on thermal management, for both continuous and pulsed-mode operation, the latter of which suggests the potential use of these technologies in bio-integrated contexts.

A cooperative therapeutic system combining doxorubicin-induced chemotherapy and chlorine 6-triggered photodynamic therapy (PDT) based on upconverting nanoparticles (UCNPs) is designed on page 1929. In this system, the therapeutic efficacy is manageable since the doxorubicin release is sensitive to the environmental pH values and the PDT efficiency can be fine-tuned by the incident near-infrared irradiation. Importantly, the combinational therapeutic system exhibits a greatly enhanced efficacy relative to the individual cancer therapies.

The exocytosis of mesoporous silica nanoparticles (MSNs) from mammalian cells is demonstrated for the first time. The differences in the degree of exocytosis of MSNs between healthy and cancer cells are shown to be responsible for the asymmetric transfer of the particles between both cell types. The exocytosis of highly adsorbent magnetic MSNs proves to be useful as a means for harvesting biomolecules from living cells.

A highly ordered hierarchical periodic structure with a large area is fabricated to support surface plasmon (SP) and surface-enhanced Raman scattering (SERS). This novel metallic submicro-nano structure described on page 1895 exhibits a complex honeycomb-like geometry, which is confirmed in experiments to support both PSPs and LSPs. Multiple modes of SPs are expected to have co-enhanced Raman scattering, heralding a further development of more sophisticated hybrid surface plasmonic nanodevices.

Graphene is an important material with unique electronic properties. Aiming to obtain high quality samples at a large scale, graphene growth on metal surfaces has been widely studied. An important topic in these studies is the atomic scale growth mechanism, which is the precondition for a rational optimization of growth conditions. Theoretical studies have provided useful insights for understanding graphene growth mechanisms, which are reviewed in this article. On the mostly used Cu substrate, graphene growth is found to be more complicated than a simple adsorption-dehydrogenation-growth model. Growth on Ni surface is precipitation dominated. On surfaces with a large lattice mismatch to graphene, epitaxial geometry determin a robust nonlinear growth behavior. Further progresses in understanding graphene growth mechanisms is expected with intense theoretical studies using advanced simulation techniques, which will make a guided design of growth protocols practical.