Three-dimensional dendritic gold nanostructures were prepared via an ultrafast one-step homogeneous solution method. Cationic surfactants, decane-1,10-bis(methylpyrrolidinium bromide) ([mpy-C 10 -mpy]Br 2 ), were used as the capping agent and L-ascorbic acid (AA) was used as the reducing agent. The as-prepared gold dendrites present a [111] plane and grow along the AE211ae direction. The AA plays an important role in the formation of the dendritic nanostructures. The methylpyrrolidinium quaternary ammonium headgroups and bolaform nanostructures of the surfactants are the key factors for the formation of dendritic structures. Further investigation revealed that the reaction time and concentration of HAuCl 4 weakly affect the formation of the dendrites. Moreover, the obtained gold dendrites exhibit excellent activity toward the catalytic reduction of p-nitraniline and higher enhancement of surface-enhanced Raman scattering when using Rhodamine 6G as the model molecules. ' INTRODUCTIONShape controlling of nanostructures became the third major topic coordinated with elemental composition and size control in the chemistry of nanostructures 1 since the morphology of nanostructures considerably influences their intrinsic properties and relevant applications. 2 Noble metal nanostructures, especially gold nanomaterials have attracted tremendous interest due to their fascinating physical and chemical properties and promising application in catalysis, nanoelectronics, sensors, photonics, imaging, and biomedicine. 1À3 Great effort has been devoted to synthesize shape-controlled gold nanostructures. 4 Among a variety of gold architectures, such as rods, 5 wires, 6 belts, 7 cubes, 8 polyhedra, 9 plates, 10 stars 11 and dendrites, 12 which have been widely achieved by certain methods, dendritic surpermolecular nanostructures attracted our attention with their unique morphology and properties. Dendritic nanostructures have special texture nanostructures, such as sharp edges or tips, nanoscale junctions and high surface areas, which brought the potential applications in biosensor, electronics, catalysis, and surface-enhanced Raman scattering (SERS) based analysis. 13 However, Au crystals usually exhibit a highly symmetric facecentered cubic (fcc) structure, and the dominant facets possess similar surface free energies. These features lead to the difficulties in forming dendritic nanostructures with complicated morphologies in homogeneous aqueous solution. The good news is that various methods, such as electrochemical, metal-deposition, and the solution-phase method, have been developed to fabricate dendritic noble metal nanostructures in recent years.The electrochemical method is a traditional way to obtain noble metal dendrites or thorn nanostructures. For example, Pt, Ag, and Au branched or dendritic nanostructures were all obtained by this method. 14 The metal deposition method is another way to obtain dendrite nanostructures. Weak reductive metal zinc plate has been used as deposing metal and reducing agent in the fabrica...

We demonstrate a simple method for transferring large areas (up to A4-size sheets) of CVD graphene from copper foils onto a target substrate using a commercially available polyvinyl alcohol polymer foil as a carrier substrate and commercial hot-roll office laminator. Through the use of terahertz time-domain spectroscopy and Raman spectroscopy, large-area quantitative optical contrast mapping, and the fabrication and electrical characterization of ∼50 individual centimeter-scale van der Pauw field effect devices, we show a nondestructive technique to transfer large-area graphene with low residual doping that is scalable, economical, reproducible, and easy to use and that results in less doping and transferinduced damage than etching or electrochemical delamination transfers. We show that the copper substrate can be used multiple times with minimal loss of material and no observable reduction in graphene quality. We have additionally demonstrated the transfer of multilayer hexagonal boron nitride from copper and iron foils. Finally, we note that this approach allows graphene to be supplied on stand-alone polymer supports by CVD graphene manufacturers to end users, with the only equipment and consumables required to transfer graphene onto target substrates being a commercial office laminator and water.

Fast inline characterization of the electrical properties of graphene on polymeric substrates is an essential requirement for quality control in industrial graphene production. Here we show that it is possible to measure the sheet conductivity of graphene on polymer films by terahertz time-domain spectroscopy (THz-TDS) when all internally reflected echoes in the substrate are taken into consideration. The conductivity measured by THz-TDS is comparable to values obtained from four point probe measurements. THz-TDS maps of 25x30 cm area graphene films were recorded and the DC conductivity and carrier scattering time were extracted from the measurements. Additionally, the THz-TDS conductivity maps highlight tears and holes in the graphene film, which are not easily visible by optical inspection.

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Hierarchical, three-fold symmetrical dendritic gold was prepared in an aqueous solution of the quaternary ammonium cationic surfactant dodecyltrimethylammonium bromide (DTAB). Similar surfactants with different head groups and hydrocarbon chain lengths were also used for comparison. Two-fold and one-fold symmetrical dendritic gold nanostructures were obtained in N-dodecyl-N-methylpyrrolidinium bromide (C(12)-MPB) and dodecyltriethylammonium bromide (DTEAB) aqueous solutions, respectively. Longer hydrocarbon chain lengths were unfavorable for the formation of dendritic nanostructures. The interaction energies between the individual surfactants and Au (111) plane were calculated using molecular dynamics simulations. Based on a series of contrast experiments and molecular dynamics simulations, the possible growth mechanism and fabrication process of the dendritic structures were proposed. The DTAB-capped, three-fold gold dendrites exhibited good surface-enhanced Raman scattering (SERS) sensitivity toward rhodamine 6G (R6G), indicating their potential for use in SERS-based detections and analysis. This work provides a simple and effective strategy for fabricating dendritic gold nanostructures in aqueous solutions.

Valsa mali var. mali (Vmm), is the predominant species of apple valsa canker in China. Modern analysis of genes involved in virulence or pathogenicity usually implicate gene expression analysis most often performed using real-time quantitative polymerase chain reaction (RT-qPCR). However, for relative gene expression analysis pertinent reference genes have to be validated before using them as internal reference. This has not been reported for Vmm, so far. Therefore, eight commonly used housekeeping genes (ACT, CYP, EF1-α, G6PDH, GAPDH, L13, TUB, and UBQ) were cloned and evaluated for their expression stability by geNorm and NormFinder. Overall, all of the candidate reference genes were found to be suitable for gene expression analysis. After analysis of 10 samples from different strains and abiotic stress treatments, G6PDH appeared to be the most suitable reference gene, whereas GAPDH was the least suitable. Moreover, taking G6PDH combined with L13 or CYP as reference genes, improved the reliability of RT-qPCR significantly. The influence of the reference system on expression data was demonstrated by analyzing Vmmpg-1 encoding an endo-polygalacturonase gene. Pectinases are considered key pathogenicity factors for this fungus. In order to better understand the role of pectinases in pathogenicity of Vmm, RT-qPCR was used for expression analysis. Our results may provide a guideline for future studies on gene expression of V. mali var. mali by using RT-qPCR.

We demonstrate terahertz time-domain spectroscopy (THz-TDS) to be an accurate, rapid and scalable method to probe the interaction-induced Fermi velocity renormalization ν F * of charge carriers in graphene. This allows the quantitative extraction of all electrical parameters (DC conductivity σ DC , carrier density n, and carrier mobility µ) of large-scale graphene films placed on arbitrary substrates via THz-TDS. Particularly relevant are substrates with low relative permittivity (< 5) such as polymeric films, where notable renormalization effects are observed even at relatively large carrier densities (> 10 12 cm -2 , Fermi level > 0.1 eV). From an application point of view, the ability to rapidly and non-destructively quantify and map the electrical (σ DC , n, µ) and electronic (ν F * ) properties of large-scale graphene on genericsubstrates is key to utilize this material in applications such as metrology, flexible electronics as well as to monitor graphene transfers using polymers as handling layers.

Graphene plasmons with tightly confined fields and actively tunable resonant frequencies enable the selective detection of molecular vibrational fingerprints with ultrahigh sensitivity, significantly promoting the development of surface‐enhanced infrared absorption spectroscopies (SEIRAS). However, current experimentally obtained enhancements are much smaller than the theoretical prediction due to the extremely low graphene plasmonic mode energy. In this paper, the strategies to improve the mode energy are theoretically and experimentally investigated in a one‐port graphene plasmonic system. By optimizing the Fabry–Pérot cavity length and employing multi‐layer graphene to drive the system into the near critical coupling regime, the localized graphene plasmonic absorptions can be improved from 3% to more than 92%. This induces a 37 times improvement of graphene plasmonic mode energy from 0.4 × 10−13 to 1.5 × 10−12 J per period for the strong plasmon–molecule interactions, enabling the highly sensitive detection of 8 nm thick molecular film. The SEIRAS experimental results demonstrate that a maximum enhancement factor of 162 can be achieved, which is one order larger than that of the reported localized graphene plasmonic sensors. The results showcase the practical usability of localized graphene plasmons for the next‐generation high sensitive nanoscale infrared spectroscopy.