Growth of sputter-deposited gold nanoparticles in ionic liquids

The growth of gold nanoparticles (NPs) synthesized by sputter deposition on an ionic liquid surface is studied in situ in the bulk phase of the ionic liquids (ILs) 1-butyl-3-methylimidazolium dicyanamide [C(1)C(4)Im][N(CN)(2)], 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide [C(1)C(4)Im][Tf(2)N], 1-butyl-3-methylimidazolium tetrafluoroborate [C(1)C(4)Im][BF(4)], 1-butyl-3-methylimidazolium hexafluorophosphate [C(1)C(4)Im][PF(6)] and 1-butyl-3-methylimidazolium triflate [C(1)C(4)Im][TfO]. It is found that primary nanoparticles with a diameter smaller than 2.5 nm are present in the sample immediately after sputtering. Growth of these primary particles proceeds after the end of the sputtering process and stops when the nanoparticles reach a certain size. Depending on the viscosity of the ionic liquid this growth process can proceed several hours to several days. The growth speed is fastest for the least viscous ionic liquid and follows the trend [C(1)C(4)Im][N(CN)(2)] > [C(1)C(4)Im][Tf(2)N] > [C(1)C(4)Im][TfO] > [C(1)C(4)Im][BF(4)] > [C(1)C(4)Im][PF(6)]. It is also found that a higher concentration of sputtered gold results in faster growth of the gold nanoparticles. A discussion on the growth mechanism of sputtered gold NPs is included.     

An integrated passive micromixer-magnetic separation-capillary electrophoresis microdevice for rapid and multiplex pathogen detection at the single-cell level

Here we report an integrated microdevice consisting of an efficient passive mixer, a magnetic separation chamber, and a capillary electrophoretic microchannel in which DNA barcode assay, target pathogen separation, and barcode DNA capillary electrophoretic analysis were performed sequentially within 30 min for multiplex pathogen detection at the single-cell level. The intestine-shaped serpentine 3D micromixer provides a high mixing rate to generate magnetic particle-pathogenic bacteria-DNA barcode labelled AuNP complexes quantitatively. After magnetic separation and purification of those complexes, the barcode DNA strands were released and analyzed by the microfluidic capillary electrophoresis within 5 min. The size of the barcode DNA strand was controlled depending on the target bacteria (Staphylococcus aureus, Escherichia coli O157:H7, and Salmonella typhimurium), and the different elution time of the barcode DNA peak in the electropherogram allows us to recognize the target pathogen with ease in the monoplex as well as in the multiplex analysis. In addition, the quantity of the DNA barcode strand (～10(4)) per AuNP is enough to be observed in the laser-induced confocal fluorescence detector, thereby making single-cell analysis possible. This novel integrated microdevice enables us to perform rapid, sensitive, and multiplex pathogen detection with sample-in-answer-out capability to be applied for biosafety testing, environmental screening, and clinical trials.     

The photoluminescent graphene oxide serves as an acceptor rather than a donor in the fluorescence resonance energy transfer pair of Cy3.5-graphene oxide

We have systematically studied the fluorescence resonance energy transfer (FRET) efficiency between the photoluminescent graphene oxide (GO) and Cy3.5 dye by controlling the donor-acceptor distance with a double stranded DNA and demonstrated that the GO serves as an acceptor rather than a donor in this FRET system.     

One-step-impregnation hard templating synthesis of high-surface-area nanostructured mixed metal oxides (NiFe2O4, CuFe2O4 and Cu/CeO2)

We report here on an efficient one-step-impregnation method to synthesize crystalline mesoporous bimetal oxides (e.g. NiFe(2)O(4), CuFe(2)O(4), Cu/CeO(2)) using mesoporous silicas as hard templates under optimized mixing conditions. This new procedure enables a true replication of the mesostructure with high yield and phase purity, while retaining particle morphology of the template.     

A specific and sensitive method for detection of hypochlorous acid for the imaging of microbe-induced HOCl production

A specific and sensitive fluorescence-based method was developed for the imaging of microbe-induced HOCl production. Furthermore, we demonstrate dual oxidase (DUOX)-mediated HOCl generation in the mucosa of live animals providing a novel insight into mucosal innate immunity.     

A concise synthesis of tetrabenazine: an intramolecular aza-Prins-type cyclization via oxidative C-H activation

A concise synthesis of tetrabenazine and dihydrotetrabenazine is described. The key feature of this synthesis is the intramolecular aza-Prins-type cyclization of an amino allylsilane via oxidative C-H activation.     

Three-dimensional tomographic reconstruction of unstable ejection phenomena of droplets for electrohydrodynamic jet

The electrohydrodynamic (EHD) jet is becoming increasingly popular within industrial printing areas based on phenomena induced by electrical potentials. Regardless of the physical observations of unstable ejection phenomena in regions possessing high electric potential, quantitative visualization is still necessary; no report exists exemplifying quantitative visualization. Thus, the size, shape and position of EHD droplets were reconstructed in this study using developed three-dimensional tomography methods. Two computer-synthesized phantoms for the liquid meniscus containing small satellite droplets were generated according to actual images captured by two high-speed cameras. These droplets were made in order to numerically reconstruct droplet behavior. Four three-dimensional tomography methods, such as the algebraic reconstruction technique (ART), the adaptive algebraic reconstruction technique (AART), the simultaneous iterative reconstruction technique (SIRT) and the multiplicative algebraic reconstruction technique (MART), were developed to accurately mimic droplet movement using multiple image views. Four basis functions including the cubic B-spline, cosine, o-Moms and Keys basis functions were adopted in order to improve the performance of the tomographic reconstructions. After completing a comparison of the four tomography results, the MART method in association with the cubic cosine basis function was selected as the means to significantly improve reconstruction accuracy. Additionally, it was the applied method for the reconstruction of the droplet behavior from experimental projections by two cameras.     

Sharp bounds for multiplier operators of negative indices associated with degenerate curves

In this note we show the sharp L ^p ?CL ^q boundedness of multiplier operators of Bochner?CRiesz type having negative indices of which singularity is located in degenerate curve in ${\mathbb{R}^2}$ . L ^p ?CL ^q boundedness of their maximal operators is also obtained.     

Electrooxidation of Glucose at Nanoporous Gold Surfaces: Structure Dependent Electrocatalysis and Its Application to Amperometric Detection

Electrooxidation of glucose is investigated at nanoporous gold (NPG) with controlled surface structures by applying different deposition charges during the formation of Ag? Au layers. As the deposition charge increases, the NPG surfaces exhibit smaller ligament/pore structures and the electrocatalytic oxidation of glucose becomes more effective. Voltammetric responses of NPG suggest that the electrocatalytic oxidation arises from the enrichment of (110) or (100) surface orientation of gold with higher deposition charges. The electrooxidation of glucose is retained at NPG surfaces with higher deposition charges in the presence of Cl^?, which suggests possible applications to the amperometric glucose detection in biological samples.     

Preparation of highly ordered TiO2 nanotubes on Ti-foil for dye-sensitized solar cells

TiO₂ nanotube arrays were grown on Ti foil in mixed electrolyte by the anodizing process. TiO₂ nanotube arrays were immersed in the TiCl₄ solution to improve the photocurrent by enhanced charge transfer between TiO₂ and dye molecules on the activity surface. Internal resistance of dye-sensitized solar cells (DSSC) was measured by impedance spectroscopy measurements. Backside illuminated DSSC with TiCl₄-treated TiO₂ nanotubes exhibited a conversion efficiency of 1.45% and showed improved electron transfer.